WorldWideScience

Sample records for fiber strength characteristics

  1. Strength Characteristics of Fiber Reinforced Quarry Dust Stabilized Fly Ash

    OpenAIRE

    Akshaya Kumar Sabat; Bidula Bose

    2015-01-01

    Effects of quarry dust and polypropylene fiber on compaction properties, shear strength parameters, and California bearing ratio (CBR) of a fly ash have been discussed in this paper. Quarry dust was added to a fly ash from 0 to 60% at an increment of 10%, compaction and soaked CBR tests were conducted on fly ash-quarry dust mixes and the optimum percentage of quarry dust was found out to be 40%. Polypropylene fiber was added to fly ash stabilized with optimum percentage of quarry dust, from 0...

  2. Tensile strength and durability characteristics of high-performance fiber reinforced concrete

    International Nuclear Information System (INIS)

    Ramadoss, P.; Nagamani, K.

    2008-01-01

    This paper presents investigations towards developing a better understanding of the contribution of steel fibers to the tensile strength of high-performance fiber reinforced concrete (HPFRC). For 32 series of mixes, flexural and splitting tensile strengths were determined at 28 days. The variables investigated were fiber volume fraction (0%, 0.5%, 1% and 1.5% with an aspect of 80), silica fume replacement level (SF/CM=0.05 and 0.10) and matrix composition (w/cm ratios ranging from 0.25 t 0.40). The influence of fiber content in terms of fiber reinforcing index on the flexural and splitting tensile strengths of HPFRC is presented. Comparative studies were performed on the tensile behavior of SFRC measured by two different loading tests: flexural test and splitting test. Based on the test results, using the least square method, empirical expressions were developed to predict 28-day tensile strength of HPFRC in terms of fiber reinforcing index. Durability tests were carried out to examine the performance of the SFRC. Relationship between flexural and splitting tensile strengths has been developed using regression analysis. The experimental values of previous researchers were compared with the values predicted by the empirical equations and the absolute variation obtained was within 6% and 5% for flexural and splitting tensile strengths respectively. (author)

  3. Study on strength characteristics of concrete using M-Sand and coconut fibers

    Science.gov (United States)

    Neeraja, D.; Wani, Amir Iqbal; Kamili, Zainulabideen; Agarwal, Krishnakant

    2017-11-01

    In the current world, concrete has become a very important part of the construction industry and the materials which are used in making concrete have evolved due to better quality of cement and better grade of coarse aggregates. The sand is an important part of concrete. It is mainly procured from natural sources. Thus the grade of sand is not under our control. The methods of removing sand from river beds are causing various environmental issues and river sand is depleting at a faster rate than it is replaced by natural methods. Hence, various replacements for the river sand are being done, one of which is manufactured-sand. It is obtained from various granite quarries. Manufactured-sand or M-sand is slowly replacing the fine aggregate in the concrete as the sand is well graded and gives higher strength of concrete. There are various fibers used for reinforcing concrete which consist mainly of artificial or steel fibers. Some of these fibers are quite costly and sometimes difficult to obtain. So there are many natural fibers which can be used in place of these fibers, one of which is coconut fiber, extracted from the shell of a coconut. Coconut fibers are used in various industries like rope making, coir mattresses etc. Since these fibers are one of the strongest fibers among naturally occuring fibers, they can be used in the concrete mix to increase the resistance in concrete. They are also light weight and easily available and thus can be used in reinforcement of concrete. The studies up till now have tested the use of coconut fibers in normal concrete involving river sand but in this study a particular ratio of M-sand and river sand is used to get the maximum possible strength. Hence, in this project an attempt was made to use M-sand and coconut fiber in concrete. Based on the test results, it can be concluded that combination of M-sand and coconut fibers gave favorable results in strength criteria.

  4. Evaluation of deformation-strength characteristics of Fiber-cement-stabilized soil by using Distinct Element Method

    Science.gov (United States)

    Satomi, Tomoaki; Konda, Naoki; Takahashi, Hiroshi

    Fiber-cement-stabilized soil method is an effective way to recycle high-water content mud. The modified soil has several advantages such as high failure stress and high failure strain. However, the quality of the modified soil is not constant and depends on the water content of the mud and additives. Therefore, experimental verification to obtain the strength characteristics of the modified soil is necessary, but conducting experiments under various conditions is ineffective and uneconomic. In this study, a numerical model to estimate deformation-strength characteristics of the modified soil is investigated by using Distinct Element Method (DEM). It was shown that the developed model was effective way to estimate deformation-strength characteristics. Moreover, it was confirmed that the modified soil had high earthquake resistance.

  5. Effect of ultraviolet light irradiation on bond strength of fiber post: Evaluation of surface characteristic and bonded area of fiber post with resin cement

    OpenAIRE

    Reza, Fazal; Ibrahim, Nur Sukainah

    2015-01-01

    Objective: Fiber post is cemented to a root canal to restore coronal tooth structure. This research aims to evaluate the effect of ultraviolet (UV) irradiation on bond strength of fiber post with resin cement. Materials and Methods: A total of 40 of the two types of fiber posts, namely, FRC Prostec (FRC) and Fiber KOR (KOR), were used for the experiment. UV irradiation was applied on top of the fiber post surface for 0, 15, 20, and 30 min. The irradiated surface of the fiber posts (n = 5) wer...

  6. Tensile strength characteristics of polypropylene composites reinforced with stone groundwood fibers from softwood

    OpenAIRE

    López, Joan Pere; Méndez González, José Alberto; Espinach Orús, Xavier; Julián Pérez, Fernando; Mutjé Pujol, Pere; Vilaseca Morera, Fabiola

    2012-01-01

    The behavior of stone groundwood / polypropylene injection-molded composites was evaluated with and without coupling agent. Stone groundwood (SGW) is a fibrous material commonly prepared in a high yield process and mainly used for papermaking applications. In this work, the use of SGW fibers was explored as a reinforcing element of polypropylene (PP) composites. The surface charge density of the composite components was evaluated, as well as the fiber’s length and diameter inside the composit...

  7. Effects of short fiber reinforcement and mean stress on tensile fatigue strength characteristics of polyethersulfone; Tansen`i kyoka porieterusaruhon no hippari hiro tokusei ni oyobosu heikin oryoku no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Furue, H.; Nonaka, K. [Mechanical Engineering Lab., Tsukuba, Ibaraki (Japan)

    1996-01-15

    Thermoplastics are often reinforced with short fibers with aims of improvement of their strengths, rigidities and hardness or maintenance of their dimensional stabilities. Such short fiber reinforced plastic materials have more expectation for high performance plastics. Authors already examined of some effects of reinforced fiber and of orientation in injection molding on flexural fatigue characteristics of the injection-molded high performance thermoplastic materials. However, the examination of short fiber reinforced effects on fatigue strength characteristics was not always sufficient. In this study, in order to obtain a guiding principle for fatigue resistant design of the short fiber reinforced injection molding materials, polyethersulfones (PES) was examined on its tensile fatigue strength and an effect of short fiber reinforcement for improvement of its fundamental dynamic properties on its fatigue characteristics. Especially, its fatigue life characteristics was elucidated mainly on relationship of mean stress, stress amplitude and number of repeating fracture in tensile fatigue behavior. 10 refs., 15 figs., 2 tabs.

  8. Strength Analysis of Coconut Fiber Stabilized Earth for Farm Structures

    Science.gov (United States)

    Enokela, O. S.; P. O, Alada

    2012-07-01

    Investigation of the strength characteristic of soil from alluvial deposit of River Benue in makurdi stabilized with coconut fiber as a stabilizer was carried as local building material for farm structure. Processed coconut fibers were mixed with the soil at four different mix ratios of 1% fiber, 2% fiber, 3% fiber and 4% fiber by percentage weight with 0% fiber as control. Compaction test and compressive strength were carried out on the various stabilizing ratio. From the compaction test, the correlation between the maximum dry density and optimum moisture content is a second order polynomial with a coefficient of 63% obtained at1.91kg/m3and 20.0% respectively while the compressive strength test shows an optimum failure load of 8.62N/mm2 at 2%fibre:100% soil mix ratio at 2.16 maximum dry density.

  9. Cellulosic Fibers: Effect of Processing on Fiber Bundle Strength

    DEFF Research Database (Denmark)

    Thygesen, Anders; Madsen, Bo; Thomsen, Anne Belinda

    2011-01-01

    A range of differently processed cellulosic fibers from flax and hemp plants were investigated to study the relation between processing of cellulosic fibers and fiber bundle strength. The studied processing methods are applied for yarn production and include retting, scutching, carding, and cotto......A range of differently processed cellulosic fibers from flax and hemp plants were investigated to study the relation between processing of cellulosic fibers and fiber bundle strength. The studied processing methods are applied for yarn production and include retting, scutching, carding...

  10. Strength measurement of optical fibers by bending

    Science.gov (United States)

    Srubshchik, Leonid S.

    1999-01-01

    A two-point bending technique has been used not only to measure the breaking stress of optical fiber but also to predict its static and dynamic fatigue. The present theory of this test is based on elastica theory of rod. However, within the limits of elastica theory the tensile and shear stresses cannot be determined. In this paper we study dynamic and static problems for optical fiber in the two- point bending test on the base of geometrically exact theory in which rod can suffer flexure, extension, and shear. We obtain the governing partial differential equations taking into account the fact that the lateral motion of the fiber is restrained by the presence of flat parallel plates. We develop the computational methods for solving the initial and equilibrium free-boundary nonlinear planar problems. We derive the formulas for predicting of the tensile strength from strength in the bending and calculate one example.

  11. Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation

    OpenAIRE

    Choi, Jeong-Il; Lee, Bang

    2015-01-01

    The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber?s suitability as a reinforcing fiber. Single fiber pullout tests were performed and then th...

  12. Effect of cellulase treatment of long fiber fraction on strength ...

    African Journals Online (AJOL)

    fiber and unbeaten short-fiber fractions. The obtained test results have indicate that the application of enzyme on appropriate fiber fraction have positive effects on the strength properties of the corrugated medium. The short span compression ...

  13. The strength and failure of silica optical fibers

    International Nuclear Information System (INIS)

    Yan, C; Bai, R X; Yu, H; Canning, J; Law, S

    2010-01-01

    The mechanical strength and failure behavior of conventional and microstructured silica optical fibers was investigated using a tensile test and fracture mechanics and numerical analyses. The effect of polymer coating on failure behavior was also studied. The results indicate that all these fibers fail in a brittle manner and failure normally starts from fiber surfaces. The failure loads observed in coated fibers are higher than those in bare fibers. The introduction of air holes reduces fiber strength and their geometrical arrangements have a remarkable effect on stress distribution in the longitudinal direction. These results are potentially useful for the design, fabrication and evaluation of optical fibers for a wide range of applications.

  14. Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation.

    Science.gov (United States)

    Choi, Jeong-Il; Lee, Bang Yeon

    2015-09-30

    The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber's suitability as a reinforcing fiber. Single fiber pullout tests were performed and then the tensile strength of fiber was measured according to fiber orientation. The test results showed that basalt fiber has a strong chemical bond with the cementitious matrix, 1.88 times higher than that of polyvinyl alcohol fibers with it. However, other properties of basalt fiber such as slip-hardening coefficient and strength reduction coefficient were worse than PVA and polyethylene fibers in terms of fiber bridging capacity. Theoretical fiber-bridging curves showed that the basalt fiber reinforcing system has a higher cracking strength than the PVA fiber reinforcing system, but the reinforcing system showed softening behavior after cracking.

  15. Bonding Properties of Basalt Fiber and Strength Reduction According to Fiber Orientation

    Directory of Open Access Journals (Sweden)

    Jeong-Il Choi

    2015-09-01

    Full Text Available The basalt fiber is a promising reinforcing fiber because it has a relatively higher tensile strength and a density similar to that of a concrete matrix as well as no corrosion possibility. This study investigated experimentally the bonding properties of basalt fiber with cementitious material as well as the effect of fiber orientation on the tensile strength of basalt fiber for evaluating basalt fiber’s suitability as a reinforcing fiber. Single fiber pullout tests were performed and then the tensile strength of fiber was measured according to fiber orientation. The test results showed that basalt fiber has a strong chemical bond with the cementitious matrix, 1.88 times higher than that of polyvinyl alcohol fibers with it. However, other properties of basalt fiber such as slip-hardening coefficient and strength reduction coefficient were worse than PVA and polyethylene fibers in terms of fiber bridging capacity. Theoretical fiber-bridging curves showed that the basalt fiber reinforcing system has a higher cracking strength than the PVA fiber reinforcing system, but the reinforcing system showed softening behavior after cracking.

  16. Effects of wood fiber surface chemistry on strength of wood–plastic composites

    Energy Technology Data Exchange (ETDEWEB)

    Migneault, Sébastien, E-mail: sebastien.migneault@uqat.ca [University of Quebec in Abitibi-Temiscamingue (UQAT), 445 boulevard de l’Université, Rouyn-Noranda, Québec J9X 5E4 (Canada); Koubaa, Ahmed, E-mail: ahmed.koubaa@uqat.ca [UQAT (Canada); Perré, Patrick, E-mail: patrick.perre@ecp.fr [École centrale de Paris, Grande Voie des Vignes, F-92 295 Chatenay-Malabry Cedex (France); Riedl, Bernard, E-mail: Bernard.Riedl@sbf.ulaval.ca [Université Laval, 2425 rue de la Terrasse, Québec City, Québec G1V 0A6 (Canada)

    2015-07-15

    Highlights: • Infrared spectroscopy and X-ray photoelectron spectroscopy analyses showed variations of surface chemical characteristics according to fiber origin. • Surface chemical characteristics of fibers could partly explain the differences in mechanical properties of the wood–plastic composites. • Fibers with carbohydrate rich surface led to stronger wood–plastic composites because the coupling between the matrix and fibers using coupling agent is achieved with polar sites mostly available on carbohydrates. • Conversely, lignin or extractives rich surface do not have oxidized functions for the esterification reaction with coupling agent and thus led to wood–plastic composites with lower mechanical properties. • Other factors such as mechanical interlocking and fiber morphology interfere with the effects of fiber surface chemistry. - Abstract: Because wood–plastic composites (WPC) strength relies on fiber-matrix interaction at fiber surface, it is likely that fiber surface chemistry plays an important role in WPC strength development. The objective of the present study is to investigate the relationships between fiber surface chemical characteristics and WPC mechanical properties. Different fibers were selected and characterized for surface chemical characteristics using X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR). WPC samples were manufactured at 40% fiber content and with six different fibers. High density polyethylene was used as matrix and maleated polyethylene (MAPE) was used as compatibility agent. WPC samples were tested for mechanical properties and fiber-matrix interface was observed with scanning electron microscope. It was found WPC strength decreases as the amount of unoxidized carbon (assigned to lignin and extractives) measured with XPS on fiber surface increases. In the opposite case, WPC strength increases with increasing level of oxidized carbon (assigned to carbohydrates) on fiber surface. The same

  17. Effects of wood fiber surface chemistry on strength of wood–plastic composites

    International Nuclear Information System (INIS)

    Migneault, Sébastien; Koubaa, Ahmed; Perré, Patrick; Riedl, Bernard

    2015-01-01

    Highlights: • Infrared spectroscopy and X-ray photoelectron spectroscopy analyses showed variations of surface chemical characteristics according to fiber origin. • Surface chemical characteristics of fibers could partly explain the differences in mechanical properties of the wood–plastic composites. • Fibers with carbohydrate rich surface led to stronger wood–plastic composites because the coupling between the matrix and fibers using coupling agent is achieved with polar sites mostly available on carbohydrates. • Conversely, lignin or extractives rich surface do not have oxidized functions for the esterification reaction with coupling agent and thus led to wood–plastic composites with lower mechanical properties. • Other factors such as mechanical interlocking and fiber morphology interfere with the effects of fiber surface chemistry. - Abstract: Because wood–plastic composites (WPC) strength relies on fiber-matrix interaction at fiber surface, it is likely that fiber surface chemistry plays an important role in WPC strength development. The objective of the present study is to investigate the relationships between fiber surface chemical characteristics and WPC mechanical properties. Different fibers were selected and characterized for surface chemical characteristics using X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR). WPC samples were manufactured at 40% fiber content and with six different fibers. High density polyethylene was used as matrix and maleated polyethylene (MAPE) was used as compatibility agent. WPC samples were tested for mechanical properties and fiber-matrix interface was observed with scanning electron microscope. It was found WPC strength decreases as the amount of unoxidized carbon (assigned to lignin and extractives) measured with XPS on fiber surface increases. In the opposite case, WPC strength increases with increasing level of oxidized carbon (assigned to carbohydrates) on fiber surface. The same

  18. Tensile strength of woven yarn kenaf fiber reinforced polyester composites

    OpenAIRE

    A.E. Ismail; M.A. Che Abdul Aziz

    2015-01-01

    This paper presents the tensile strength of woven kenaf fiber reinforced polyester composites. The as-received yarn kenaf fiber is weaved and then aligned into specific fiber orientations before it is hardened with polyester resin. The composite plates are shaped according to the standard geometry and uni-axially loaded in order to investigate the tensile responses. Two important parameters are studied such as fiber orientations and number of layers. According to the results, it is shown that...

  19. Tensile strength of woven yarn kenaf fiber reinforced polyester composites

    Directory of Open Access Journals (Sweden)

    A.E. Ismail

    2015-12-01

    Full Text Available This paper presents the tensile strength of woven kenaf fiber reinforced polyester composites. The as-received yarn kenaf fiber is weaved and then aligned into specific fiber orientations before it is hardened with polyester resin. The composite plates are shaped according to the standard geometry and uni-axially loaded in order to investigate the tensile responses. Two important parameters are studied such as fiber orientations and number of layers. According to the results, it is shown that fiber orientations greatly affected the ultimate tensile strength but it is not for modulus of elasticity for both types of layers. It is estimated that the reductions of both ultimate tensile strength and Young’s modulus are in the range of 27.7-30.9% and 2.4-3.7% respectively, if the inclined fibers are used with respect to the principal axis.

  20. Interfacial (Fiber-matrix) Properties of High-strength Mortar (150 MPa) from Fiber Pullout

    DEFF Research Database (Denmark)

    Shannag, M.J.; Brincker, Rune; Hansen, Will

    1996-01-01

     The steel fiber-matrix properties of high-strength mortar (150 MPa), such as DSP (densified small particle), are obtained and compared to an ordinary strength mortar (40 MPa) using a specially designed fiber pullout apparatus. A new method for estimating the debonding energy of the interfacial z......-strength DSP mortar has significantly improved interfacial properties compared to ordinary strength mortar. These results are important in the understanding of the role of steel fibers in improving the tensile properties of high-strength, brittle, cement-matrix composites....... The steel fiber-matrix properties of high-strength mortar (150 MPa), such as DSP (densified small particle), are obtained and compared to an ordinary strength mortar (40 MPa) using a specially designed fiber pullout apparatus. A new method for estimating the debonding energy of the interfacial...

  1. In vitro study of transverse strength of fiber reinforced composites.

    Science.gov (United States)

    Mosharraf, R; Hashemi, Z; Torkan, S

    2011-01-01

    Reinforcement with fiber is an effective method for considerable improvement in flexural properties of indirect composite resin restorations. The aim of this in-vitro study was to compare the transverse strength of composite resin bars reinforced with pre-impregnated and non-impregnated fibers. Thirty six bar type composite resin specimens (3×2×25 mm) were constructed in three groups. The first group was the control group (C) without any fiber reinforcement. The specimens in the second group (P) were reinforced with pre-impregnated fibers and the third group (N) with non-impregnated fibers. These specimens were tested by the three-point bending method to measure primary transverse strength. Data were statistically analyzed with one way ANOVA and Tukey's tests. There was a significant difference among the mean primary transverse strength in the three groups (Ptransverse strength (Pstudy, it was concluded that reinforcement with fiber considerably increased the transverse strength of composite resin specimens, but impregnation of the fiber used implemented no significant difference in the transverse strength of composite resin samples.

  2. Strength and thermal stability of fiber reinforced plastic composites ...

    African Journals Online (AJOL)

    Therefore, the strength properties and thermal stability of plastic composites reinforced with rattan fibers were investigated in this work. Particles of rattan species (Eremospatha macrocarpa (EM) and Laccosperma secundiflorum (LS)) were blended with High-Density Polyethylene (HDPE) to produce fiber reinforced plastic ...

  3. Strength of cellulosic fiber/starch acetate composites with variable fiber and plasticizer content

    DEFF Research Database (Denmark)

    Joffe, Roberts; Madsen, Bo; Nättinen, Kalle

    2015-01-01

    In this experimental study, the performance of injection-molded short flax and hemp fibers in plasticized starch acetate were analyzed in terms of strength. Parameters involved in the analysis are a variable fiber and plasticizer content. The measured strength of the composites varies in the range...... of 12–51 MPa for flax fibers and 11–42 MPa for hemp fibers, which is significantly higher than the properties of the unreinforced starch acetate matrix. The micro-structural parameters used in modeling of composite strength were obtained from optical observations and indirect measurements. Some...

  4. Mechanical behavior of high strength ceramic fibers at high temperatures

    Science.gov (United States)

    Tressler, R. E.; Pysher, D. J.

    1991-01-01

    The mechanical behavior of commercially available and developmental ceramic fibers, both oxide and nonoxide, has been experimentally studied at expected use temperatures. In addition, these properties have been compared to results from the literature. Tensile strengths were measured for three SiC-based and three oxide ceramic fibers for temperatures from 25 C to 1400 C. The SiC-based fibers were stronger but less stiff than the oxide fibers at room temperature and retained more of both strength and stiffness to high temperatures. Extensive creep and creep-rupture experiments have been performed on those fibers from this group which had the best strengths above 1200 C in both single filament tests and tests of fiber bundles. The creep rates for the oxides are on the order of two orders of magnitude faster than the polymer derived nonoxide fibers. The most creep resistant filaments available are single crystal c-axis sapphire filaments. Large diameter CVD fabricated SiC fibers are the most creep and rupture resistant nonoxide polycrystalline fibers tested to date.

  5. Strength Development of High-Strength Ductile Concrete Incorporating Metakaolin and PVA Fibers

    Directory of Open Access Journals (Sweden)

    Muhammad Fadhil Nuruddin

    2014-01-01

    Full Text Available The mechanical properties of high-strength ductile concrete (HSDC have been investigated using Metakaolin (MK as the cement replacing material and PVA fibers. Total twenty-seven (27 mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers.

  6. Strength development of high-strength ductile concrete incorporating Metakaolin and PVA fibers.

    Science.gov (United States)

    Nuruddin, Muhammad Fadhil; Khan, Sadaqat Ullah; Shafiq, Nasir; Ayub, Tehmina

    2014-01-01

    The mechanical properties of high-strength ductile concrete (HSDC) have been investigated using Metakaolin (MK) as the cement replacing material and PVA fibers. Total twenty-seven (27) mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers.

  7. Impact strength on fiber-reinforced hybrid composite

    International Nuclear Information System (INIS)

    Firdaus, S M; Nurdina; Ariff, M Azmil

    2013-01-01

    Acrylonitrile-Butadiene-Styrene (ABS) has been well known composite in automotive players to have light weight with high impact strength material compared to sheet metal material which has high impact strength but heavy in weight. In this project, the impact strength properties of fabricated pure ABS were compared to the eight samples of hybrid ABS composite with different weight percentages of short fibers and particle sizes of ground rubber. The objective was to improve the impact strength in addition of short fibers and ground rubber particles. These samples were then characterized using an un-notched Izod impact test. Results show that the increasing of filler percentage yielded an adverse effect on the impact strength of the hybrid composite. The effect of the ground rubber particulate sizes however are deemed to be marginal than the effect of varying filler percentage based on the collected impact strength data from all physically tested hybrid composites

  8. Effect of PVA fiber content on creep property of fiber reinforced high-strength concrete columns

    Science.gov (United States)

    Xu, Zongnan; Wang, Tao; Wang, Weilun

    2018-04-01

    The effect of PVA (polyvinyl alcohol) fiber content on the creep property of fiber reinforced high-strength concrete columns was investigated. The correction factor of PVA fiber content was proposed and the creep prediction model of ACI209 was modified. Controlling the concrete strength as C80, changing the content of PVA fiber (volume fraction 0%, 0.25%, 0.5%, 1% respectively), the creep experiment of PVA fiber reinforced concrete columns was carried out, the creep coefficient of each specimen was calculated to characterize the creep property. The influence of PVA fiber content on the creep property was analyzed based on the creep coefficient and the calculation results of several frequently used creep prediction models. The correction factor of PVA fiber content was proposed to modify the ACI209 creep prediction model.

  9. Effect of high pressure hydrogen on the mechanical characteristics of single carbon fiber

    Science.gov (United States)

    Jeon, Sang Koo; Kwon, Oh Heon; Jang, Hoon-Sik; Ryu, Kwon Sang; Nahm, Seung Hoon

    2018-02-01

    In this study, carbon fiber was exposed to a pressure of 7 MPa for 24 h in high pressure chamber. The tensile test for carbon fiber was conducted to estimate the effect on the high pressure hydrogen in the atmosphere. To determine the tensile strength and Weibull modulus, approximately thirty carbon fiber samples were measured in all cases, and carbon fiber exposed to high pressure argon was evaluated to verify only the effect of hydrogen. Additionally, carbon fiber samples were annealed at 1950 °C for 1 h for a comparison with normal carbon fiber and then tested under identical conditions. The results showed that the tensile strength scatter of normal carbon fiber exposed to hydrogen was relatively wider and the Weibull modulus was decreased. Moreover, the tensile strength of the annealed carbon fiber exposed to hydrogen was increased, and these samples indicated a complex Weibull modulus because the hydrogen stored in the carbon fiber influenced the mechanical characteristic.

  10. Radiation resistant characteristics of optical fibers

    International Nuclear Information System (INIS)

    Nakasuji, Masaaki; Tanaka, Gotaro; Watanabe, Minoru; Kyodo, Tomohisa; Mukunashi, Hiroaki

    1983-01-01

    It is required to develop the optical fibers with good radiation resistivity because the fibers cause the increase of transmission loss due to glass colouring when they are used under the presence of radiation such as γ-ray. Generally, it is known that SI (step index) fibers are more resistive to radiation than GI (graded index) fibers. However, since a wide band can not be obtained with SI fibers, the development of radiation resistive GI optical fibers is desirable. In this report, the production for trial of the GI fibers of fluorine-doped silica core, the examination of radiation effect on their optical transmission loss by exposing them to γ-ray, thermal and fast neutron beams and also of mechanical strength are described. The GI fibers of fluorine-doped silica core show better radiation resistivity than Ge-doped ones. The B- and F-doped GI fibers show small increase of loss due to γ-ray, but large increase of loss due to thermal neutron beam. This is supposed to be caused by the far greater neutron absorption cross-section of boron than that of other elements. Significant increase of loss was not recognized when 14 MeV fast neutrons (8.6 x 10 4 n/cm 2 .s) were applied by 1.8 x 10 9 n/cm 2 . It was found that ETFE-covered fiber cores generated fluorine-containing gas due to γ irradiation, and the strength was remarkably lowered, but the lowering of strength can be prevented by adding titanium-white to the covering material. (Wakatsuki, Y.)

  11. Interfacial characteristics of an epoxy composite reinforced with phosphoric acid-functionalized Kevlar fibers

    Science.gov (United States)

    Li, J.; Xia, Y. C.

    2010-07-01

    A Kevlar fiber was functionalized with the phosphoric acid (PA) of different concentrations. The surface characteristics of the fiber were examined by using the X-ray photoelectron spectroscopy. It was found that the PA functionalization considerably increased the bond strength between the Kevlar fiber and an epoxy matrix.

  12. Improving the strength of amalgams by including steel fibers

    Energy Technology Data Exchange (ETDEWEB)

    Cochran, Calvin T. [Hendrix College, Conway, AR 72032 (United States); Van Hoose, James R. [Siemens, Orlando, FL 32826 (United States); McGill, Preston B. [Marshall Space Flight Center, EM20, Huntsville, AL 35812 (United States); Grugel, Richard N., E-mail: richard.n.grugel@nasa.gov [Marshall Space Flight Center, EM30, Huntsville, AL 35812 (United States)

    2012-05-30

    Highlights: Black-Right-Pointing-Pointer A room temperature liquid Ga-In alloy was successfully substituted for mercury. Black-Right-Pointing-Pointer Physically sound amalgams with included steel fibers can be made. Black-Right-Pointing-Pointer A small volume fraction inclusion of fibers increased strength by {approx}20%. - Abstract: Mercury amalgams, due to their material properties, are widely and successfully used in dental practice. They are, however, also well recognized as having poor tensile strength. With the possibility of expanding amalgam applications it is demonstrated that tensile strength can be increased some 20% by including a small amount of steel fibers. Furthermore, it is shown that mercury can be replaced with a room temperature liquid gallium-indium alloy. Processing, microstructures, and mechanical test results of these novel amalgams are presented and discussed in view of means to further improve their properties.

  13. Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

    Directory of Open Access Journals (Sweden)

    Lei Gao

    2015-01-01

    Full Text Available In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%. When the effect of length is researched, different lengths of basalt fibers with 4 mm, 8 mm, 12 mm, and 15 mm are put into soil at the same content of 0.05%. Experimental results show that basalt fiber can effectively improve the UCS of clay soil. And the best content and length are 0.25% and 12 mm, respectively. The results also show that the basalt fiber reinforced clay soil has the “poststrong” characteristic. About the reinforcement mechanism, the fiber and soil column-net model is proposed in this paper. Based on this model and SEM images, the effect of fiber content and length is related to the change of fiber-soil column and formation of effective fiber-soil net.

  14. Normal Strength Steel Fiber Reinforced Concrete Subjected to Explosive Loading

    OpenAIRE

    Mohammed Alias Yusof; Norazman Norazman; Ariffin Ariffin; Fauzi Mohd Zain; Risby Risby; CP Ng

    2011-01-01

    This paper presents the results of an experimental investigation on the behavior of plain reinforced concrete and Normal strength steel fiber reinforced concrete panels (SFRC) subjected to explosive loading. The experiment were performed by the Blast Research Unit Faculty of Engineering, University Pertahanan Nasional Malaysia A total of 8 reinforced concrete panels of 600mm x 600mm x 100mm were tested. The steel fiber reinforced concrete panels incorporated three different volume fraction, 0...

  15. swelling characteristics and tensile properties of natural fiber rei

    African Journals Online (AJOL)

    USER

    The swelling behavior and tensile strength of natural fiber-reinforced plastic in premium motor spirit (PMS), dual ... with fibers usually of glass fiber, Kevlar and carbon have gained ... NIGERIAN JOURNAL OF TECHNOLOGY, VOL. 27 NO.2 ...

  16. Evaluation of residual strength in the basalt fiber reinforced composites under impact damage

    Science.gov (United States)

    Kim, Yun-Hae; Lee, Jin-Woo; Moon, Kyung-Man; Yoon, Sung-Won; Baek, Tae-Sil; Hwang, Kwang-Il

    2015-03-01

    Composites are vulnerable to the impact damage by the collision as to the thickness direction, because composites are being manufactured by laminating the fiber. The understanding about the retained strength after the impact damage of the material is essential in order to secure the reliability of the structure design using the composites. In this paper, we have tried to evaluate the motion of the material according to the kinetic energy and potential energy and the retained strength after impact damage by testing the free fall test of the basalt fiber reinforced composite in the limelight as the environment friendly characteristic.

  17. An experimental study on flexural strength enhancement of concrete by means of small steel fibers

    Directory of Open Access Journals (Sweden)

    Abdoullah Namdar

    2013-10-01

    Full Text Available Cost effective improvement of the mechanical performances of structural materials is an important goal in construction industry. To improve the flexural strength of plain concrete so as to reduce construction costs, the addition of fibers to the concrete mixture can be adopted. The addition of small steel fibers with different lengths and proportion have experimentally been analyzed in terms of concrete flexural strength enhancement. The main objectives of the present study are related to the evaluation of the influence of steel fibers design on the increase of concrete flexural characteristics and on the mode of failure. Two types of beams have been investigated. The force level, deflection and time to failure of beams have been measured. The shear crack, flexural crack and intermediate shear-flexural crack have been studied. The steel fiber content controlled crack morphology. Flexural strength and time to failure of fiber reinforce concrete could be further enhanced if, instead of smooth steel fibers, corrugated fibers were used.

  18. A design method for two-layer beams consisting of normal and fibered high strength concrete

    International Nuclear Information System (INIS)

    Iskhakov, I.; Ribakov, Y.

    2007-01-01

    Two-layer fibered concrete beams can be analyzed using conventional methods for composite elements. The compressed zone of such beam section is made of high strength concrete (HSC), and the tensile one of normal strength concrete (NSC). The problems related to such type of beams are revealed and studied. An appropriate depth of each layer is prescribed. Compatibility conditions between HSC and NSC layers are found. It is based on the shear deformations equality on the layers border in a section with maximal depth of the compression zone. For the first time a rigorous definition of HSC is given using a comparative analysis of deformability and strength characteristics of different concrete classes. According to this definition, HSC has no download branch in the stress-strain diagram, the stress-strain function has minimum exponent, the ductility parameter is minimal and the concrete tensile strength remains constant with an increase in concrete compression strength. The application fields of two-layer concrete beams based on different static schemes and load conditions make known. It is known that the main disadvantage of HSCs is their low ductility. In order to overcome this problem, fibers are added to the HSC layer. Influence of different fiber volume ratios on structural ductility is discussed. An upper limit of the required fibers volume ratio is found based on compatibility equation of transverse tensile concrete deformations and deformations of fibers

  19. Gamma ray irradiation characteristics of SM fibers

    International Nuclear Information System (INIS)

    Ito, Ryuichi; Okano, Hiroaki; Hashiba, Keichi; Nakai, Hisanori

    1987-01-01

    1.3 μm range single mode (SM) optical fibers have been used for wide application of mainly long distance communication. At present, in order to realize the larger capacity and longer distance between relay points, the development of 1.5 μm range SM fibers of low dispersion and small loss has been actively promoted. As for the radiation withstanding property of SM fibers, report is scarce. The authors reported on the gamma ray irradiation characteristics of 1.3 μm range SM fibers, but since 1.5 μm range SM fibers are designed with the different structure from that of 1.3 μm fibers, it is necessary to evaluate from new viewpoint. In this report, mainly on the structure having triangular distribution, the effect that the manufacturing condition and the structural defects of glass exert on the gamma ray irradiation characteristics is described. The specimens were mainly dispersion shift type fibers (DSF), and for comparison, single window, double window and 1.3 μm SM fibers were examined. Co-60 gamma ray was irradiated, and the optical loss and electron spin resonance were measured. By low temperature and low speed drawing, the good result in the optical loss was obtained. The presence of oxygen at the time of sintering materials had no effect. The dependence of the ESR on the drawing condition was not very remarkable. (Kako, I.)

  20. Chain Ends and the Ultimate Tensile Strength of Polyethylene Fibers

    Science.gov (United States)

    O'Connor, Thomas C.; Robbins, Mark O.

    Determining the tensile yield mechanisms of oriented polymer fibers remains a challenging problem in polymer mechanics. By maximizing the alignment and crystallinity of polyethylene (PE) fibers, tensile strengths σ ~ 6 - 7 GPa have been achieved. While impressive, first-principal calculations predict carbon backbone bonds would allow strengths four times higher (σ ~ 20 GPa) before breaking. The reduction in strength is caused by crystal defects like chain ends, which allow fibers to yield by chain slip in addition to bond breaking. We use large scale molecular dynamics (MD) simulations to determine the tensile yield mechanism of orthorhombic PE crystals with finite chains spanning 102 -104 carbons in length. The yield stress σy saturates for long chains at ~ 6 . 3 GPa, agreeing well with experiments. Chains do not break but always yield by slip, after nucleation of 1D dislocations at chain ends. Dislocations are accurately described by a Frenkel-Kontorova model, parametrized by the mechanical properties of an ideal crystal. We compute a dislocation core size ξ = 25 . 24 Å and determine the high and low strain rate limits of σy. Our results suggest characterizing such 1D dislocations is an efficient method for predicting fiber strength. This research was performed within the Center for Materials in Extreme Dynamic Environments (CMEDE) under the Hopkins Extreme Materials Institute at Johns Hopkins University. Financial support was provided by Grant W911NF-12-2-0022.

  1. Study on creep of fiber reinforced ultra-high strength concrete based on strength

    Science.gov (United States)

    Peng, Wenjun; Wang, Tao

    2018-04-01

    To complement the creep performance of ultra-high strength concrete, the long creep process of fiber reinforced concrete was studied in this paper. The long-term creep process and regularity of ultra-high strength concrete with 0.5% PVA fiber under the same axial compression were analyzed by using concrete strength (C80/C100/C120) as a variable. The results show that the creep coefficient of ultra-high strength concrete decreases with the increase of concrete strength. Compared with ACI209R (92), GL2000 models, it is found that the predicted value of ACI209R (92) are close to the experimental value, and the creep prediction model suitable for this experiment is proposed based on ACI209R (92).

  2. Analysis of the strength and stiffness of timber beams reinforced with carbon fiber and glass fiber

    Directory of Open Access Journals (Sweden)

    Juliano Fiorelli

    2003-06-01

    Full Text Available An experimental analysis of pinewood beams (Pinus caribea var hondurensis reinforced with glass and/or carbon fibers is discussed. The theoretical model employed to calculate the beam's bending strength takes into account the timber's ultimate limit states of tensile strength and failure by compression, considering a model of fragile elastic tension and plastic elastic compression. The validity of the theoretical model is confirmed by a comparison of the theoretical and experimental results, while the efficiency of the fiber reinforcement is corroborated by the increased strength and stiffness of the reinforced timber beams.

  3. Recent trends in steel fibered high-strength concrete

    International Nuclear Information System (INIS)

    Shah, Abid A.; Ribakov, Y.

    2011-01-01

    Highlights: → Recent studies on steel fibred high strength concrete (SFHSC) are reviewed. → Different design provisions for SFHSC are compared. → Applications of SFHSC in new and existing structures and elements are discussed. → Using non-destructive techniques for quality control of SFHSC are reviewed. -- Abstract: Steel fibered high-strength concrete (SFHSC) became in the recent decades a very popular material in structural engineering. High strength attracts designers and architects as it allows improving the durability as well as the esthetics of a construction. As a result of increased application of SFHSC, many experimental studies are conducted to investigate its properties and to develop new rules for proper design. One of the trends in SFHSC structures is to provide their ductile behavior that is desired for proper structural response to dynamic loadings. An additional goal is to limit development and propagation of macro-cracks in the body of SFHSC elements. SFHSC is tough and demonstrates high residual strengths after appearance of the first crack. Experimental studies were carried out to select effective fiber contents as well as suitable fiber types, to study most efficient combination of fiber and regular steel bar reinforcement. Proper selection of other materials like silica fume, fly ash and super plasticizer has also high importance because of the influence on the fresh and hardened concrete properties. Combination of normal-strength concrete with SFHSC composite two-layer beams leads to effective and low cost solutions that may be used in new structures as well as well as for retrofitting existing ones. Using modern nondestructive testing techniques like acoustic emission and nonlinear ultrasound allows verification of most design parameters and control of SFHSC properties during casting and after hardening. This paper presents recent experimental results, obtained in the field SFHSC and non-destructive testing. It reviews the

  4. Behavior and strength of beams cast with ultra high strength concrete containing different types of fibers

    Directory of Open Access Journals (Sweden)

    M.M. Kamal

    2014-04-01

    Full Text Available Ultra-high performance concrete (UHPC is a special type of concrete with extraordinary potentials in terms of strength and durability performance. Its production and application implement the most up-to-date knowledge and technology of concrete manufacturing. Sophisticated structural designs in bridges and high-rise buildings, repair works and special structures like nuclear facilities are currently the main fields of applications of UHPC. This paper aimed to evaluate the behavior of ultra-high strength concrete beams. This paper also aimed to determine the effect of adding fibers and explore their effect upon the behavior and strength of the reinforced concrete beams. A total of twelve simple concrete beams with and without shear reinforcements were tested in flexure. The main variables taken into consideration in this research were the type of fibers and the percentage of longitudinal reinforcement as well as the existence or absence of the web reinforcement. Two types of fibers were used including steel and polypropylene fibers. The behavior of the tested beams was investigated with special attention to the deflection under different stages of loading, initial cracking, cracking pattern, and ultimate load. Increased number of cracks was observed at the end of loading due to the use of fibers, which led to the reduced width of cracks. This led to increased stiffness and higher values of maximum loads.

  5. Strength Characteristics of Reinforced Sandy Soil

    OpenAIRE

    S. N. Bannikov; Mahamed Al Fayez

    2005-01-01

    Laboratory tests on determination of reinforced sandy soil strength characteristics (angle of internal friction, specific cohesive force) have been carried out with the help of a specially designed instrument and proposed methodology. Analysis of the obtained results has revealed that cohesive forces are brought about in reinforced sandy soil and an angle of internal soil friction becomes larger in comparison with non-reinforced soil.

  6. Flexural strength of self compacting fiber reinforced concrete beams using polypropylene fiber: An experimental study

    Science.gov (United States)

    Lisantono, Ade; Praja, Baskoro Abdi; Hermawan, Billy Nouwen

    2017-11-01

    One of the methods to increase the tensile strength of concrete is adding a fiber material into the concrete. While to reduce a noise in a construction project, a self compacting concrete was a good choices in the project. This paper presents an experimental study of flexural behavior and strength of self compacting fiber reinforced concrete (RC) beams using polypropylene fiber. The micro monofilament polypropylene fibers with the proportion 0.9 kg/m3 of concrete weight were used in this study. Four beam specimens were cast and tested in this study. Two beams were cast of self compacting reinforced concrete without fiber, and two beams were cast of self compacting fiber reinforced concrete using polypropylene. The beams specimen had the section of (180×260) mm and the length was 2000 mm. The beams had simple supported with the span of 1800 mm. The longitudinal reinforcements were using diameter of 10 mm. Two reinforcements of Ø10 mm were put for compressive reinforcement and three reinforcements of Ø10 mm were put for tensile reinforcement. The shear reinforcement was using diameter of 8 mm. The shear reinforcements with spacing of 100 mm were put in the one fourth near to the support and the spacing of 150 mm were put in the middle span. Two points loading were used in the testing. The result shows that the load-carrying capacity of the self compacting reinforced concrete beam using polypropylene was a little bit higher than the self compacting reinforced concrete beam without polypropylene. The increment of load-carrying capacity of self compacting polypropylene fiber reinforced concrete was not so significant because the increment was only 2.80 % compare to self compacting non fiber reinforced concrete. And from the load-carrying capacity-deflection relationship curves show that both the self compacting polypropylene fiber reinforced concrete beam and the self compacting non fiber reinforced concrete beam were ductile beams.

  7. Optimization Of Fluoride Glass Fiber Drawing With Respect To Mechanical Strength

    Science.gov (United States)

    Schneider, H. W.; Schoberth, A.; Staudt, A.; Gerndt, Ch.

    1987-08-01

    Heavy metal fluoride fibers have attracted considerable attention recently as lightguides for infrared optical devices. Besides the optical loss mechanical performance of the fiber is of major interest. At present fiber strength suffers from surface crystallization prior to or during fiber drawing. We developed an etching method for the preparation of preforms with clean surface. Drawing these preforms under optimized conditions in a dry atmosphere results in fibers with improved strength. So far, mean value of 400 N/mm2 tensile strength have been achieved. Maximum values of 800 N/mm2 measured on etched fibers indicate an even higher strength potential for the material itself.

  8. Tensile strength of solution-spun, ultradrawn ultrahigh-molecular-weight polyethylene fibers. 1. Influence of fiber diameter

    OpenAIRE

    Bastiaansen, C.W.M.

    1992-01-01

    The influence of fiber diam. on the tensile strength of soln.-spun, ultradrawn, ultrahigh-mol.-wt. polyethylene (UHMWPE, mol. wt. >103 kg/mol) fibers was studied. Fibers with a wide range of diams. were produced by varying the polymer concn. in soln. and by applying a drawdown to the fibers. The tensile strength of drawn fibers was compared at a const. Young's modulus in order to eliminate the influence of morphol. parameters, such as degree of chain orientation and extension, on the fracture...

  9. Bond characteristics of steel fiber and deformed reinforcing steel bar embedded in steel fiber reinforced self-compacting concrete (SFRSCC)

    Science.gov (United States)

    Aslani, Farhad; Nejadi, Shami

    2012-09-01

    Steel fiber reinforced self-compacting concrete (SFRSCC) is a relatively new composite material which congregates the benefits of the self-compacting concrete (SCC) technology with the profits derived from the fiber addition to a brittle cementitious matrix. Steel fibers improve many of the properties of SCC elements including tensile strength, ductility, toughness, energy absorption capacity, fracture toughness and cracking. Although the available research regarding the influence of steel fibers on the properties of SFRSCC is limited, this paper investigates the bond characteristics between steel fiber and SCC firstly. Based on the available experimental results, the current analytical steel fiber pullout model (Dubey 1999) is modified by considering the different SCC properties and different fiber types (smooth, hooked) and inclination. In order to take into account the effect of fiber inclination in the pullout model, apparent shear strengths ( τ ( app)) and slip coefficient ( β) are incorporated to express the variation of pullout peak load and the augmentation of peak slip as the inclined angle increases. These variables are expressed as functions of the inclined angle ( ϕ). Furthurmore, steel-concrete composite floors, reinforced concrete floors supported by columns or walls and floors on an elastic foundations belong to the category of structural elements in which the conventional steel reinforcement can be partially replaced by the use of steel fibers. When discussing deformation capacity of structural elements or civil engineering structures manufactured using SFRSCC, one must be able to describe thoroughly both the behavior of the concrete matrix reinforced with steel fibers and the interaction between this composite matrix and discrete steel reinforcement of the conventional type. However, even though the knowledge on bond behavior is essential for evaluating the overall behavior of structural components containing reinforcement and steel fibers

  10. Guiding characteristics of sunflower-type fiber

    Science.gov (United States)

    Liu, Exian; Yan, Bei; Tan, Wei; Xie, Jianlan; Ge, Rui; Liu, Jianjun

    2018-03-01

    In this paper, the guiding characteristics of sunflower-type fiber (SFF) with 6-fold rotational symmetry are investigated theoretically using finite element method (FEM). The behavior of single-mode propagation in SFF is verified. Numerical results reveal that, the cutoff ratio for endlessly single-mode propagation in SFF is 0.575 which is larger than that of photonic crystal fiber (PCF) and photonic quasi-crystal fiber (PQF). Moreover, SFF can present ultra-flattened near-zero chromatic dispersion, 0.249 ± 1.146 ps/nm/km, in a broadband of wavelength covering 1.20-1.84 μm over all the telecommunication wavelengths. In term of chromatic dispersion and confinement loss in the wavelength range from 1.00 to 2.00 μm, a comparison between SFF, PCF and PQF with same structure parameters is carried out. Importantly, the rotational symmetry, as a new manageable structure parameter beyond common air hole diameter and lattice constant, can be employed to manipulate the chromatic dispersion, confinement loss, effective mode area and non-linear coefficient and it dependences on these guiding characteristics are discussed in detail.

  11. Strength characteristics of light weight concrete blocks using mineral admixtures

    Science.gov (United States)

    Bhuvaneshwari, P.; Priyadharshini, U.; Gurucharan, S.; Mithunram, B.

    2017-07-01

    This paper presents an experimental study to investigate the characteristics of light weight concrete blocks. Cement was partially replaced with mineral admixtures like Fly ash (FA), limestone powder waste (LPW), Rice husk ash (RHA), sugarcane fiber waste (SCW) and Chrysopogonzizanioides (CZ). The maximum replacement level achieved was 25% by weight of cement and sand. Total of 56 cubes (150 mm x 150 mm x150 mm) and 18 cylinders (100mmφ and 50mm depth) were cast. The specimens being (FA, RHA, SCW, LPW, CZ, (FA-RHA), (FA-LPW), (FA-CZ), (LPW-CZ), (FA-SCW), (RHA-SCW)).Among the different combination, FA,FA-SCW,CZ,FA-CZ showed enhanced strength and durability, apart from achieving less density.

  12. Fracture strength of fiber-reinforced surface-retained anterior cantilever restorations

    NARCIS (Netherlands)

    Oezcan, Mutlu; Kumbuloglu, Ovul; User, Atilla

    2008-01-01

    Purpose: This study compared the fracture strength of direct anterior cantilever fiber-reinforced composite (FRC) fixed partial dentures (FPD) reinforced with 3 types of E-glass fibers preimpregnated with either urethane tetramethacrylate, bisphenol glycidylmethacrylate/polymethyl methacrylate, or

  13. Evolution of Durable High-Strength Flowable Mortar Reinforced with Hybrid Fibers

    OpenAIRE

    Dawood, Eethar Thanon; Ramli, Mahyuddin

    2012-01-01

    The production and use of durable materials in construction are considered as one of the most challenging things for the professional engineers. Therefore, this research was conducted to investigate the mechanical properties and the durability by using of different percentages of steel fiber with high-strength flowable mortar (HSFM) and also the use of the hybridization of steel fibers, palm fibers, and synthetic fiber (Barchip). Different experimental tests (compressive strength, splitting t...

  14. The effect of silanated and impregnated fiber on the tensile strength of E-glass fiber reinforced composite retainer

    Directory of Open Access Journals (Sweden)

    Niswati Fathmah Rosyida

    2015-12-01

    Full Text Available Background: Fiber reinforced composite (FRC is can be used in dentistry as an orthodontic retainer. FRC  still has a limitations because of to  a weak bonding between fibers and matrix. Purpose: This research was aimed to evaluate the effect of silane as coupling agent and fiber impregnation on the tensile strength of E-glass FRC. Methods: The samples of this research were classified into two groups each of which consisted of three subgroups, namely the impregnated fiber group (original, 1x addition of silane, 2x addition of silane and the non-impregnated fiber group (original, 1x addition of silane, 2x addition of silane. The tensile strength was measured by a universal testing machine. The averages of the tensile strength in all groups then were compared by using Kruskal Wallis and Mann Whitney post hoc tests. Results: The averages of the tensile strength (MPa in the impregnated fiber group can be known as follow; original impregnated fiber (26.60±0.51, 1x addition of silane (43.38±4.42, and 2x addition of silane (36.22±7.23. The averages of tensile strength (MPa in the non-impregnated fiber group can also be known as follow; original non-impregnated fiber (29.38±1.08, 1x addition of silane (29.38±1.08, 2x addition of silane (12.48±2.37. Kruskal Wallis test showed that there was a significant difference between the impregnated fiber group and the non-impregnated fiber group (p<0.05. Based on the results of post hoc test, it is also known that the addition of silane in the impregnated fiber group had a significant effect on the increasing of the tensile strength of E-glass FRC (p<0.05, while the addition of silane in the non-impregnated fiber group had a significant effect on the decreasing of the tensile strength of E-glass FRC. Conclusion: It can be concluded that the addition of silane in the non-silanated fiber group can increase the tensile strength of E-glass FRC, but the addition of silane in the silanated fiber group can

  15. optimizing compressive strength characteristics of hollow building

    African Journals Online (AJOL)

    eobe

    Keywords: hollow building Blocks, granite dust, sand, partial replacement, compressive strength. 1. INTRODUCTION ... exposed to extreme climate. The physical ... Sridharan et al [13] conducted shear strength studies on soil-quarry dust.

  16. Effect of Hybrid Fibers on the Mechanical Properties of High Strength Concrete

    Directory of Open Access Journals (Sweden)

    Hamid H. Hussein, Saeed K. Rejeb Hayder T. Abd

    2014-04-01

    Full Text Available In this study, high strength concrete of 75 MPa compressive strength was investigated. The experimental program was designed to study the effect of fibers and hybrid fibers (steel and polypropylene fibers on the fresh (workability and wet density and hardened properties (compressive strength, splitting strength, flexural strength and dry density of high strength concrete. Results show that decreases in slump flow of all concrete mixtures containing steel, polypropylene and hybrid fibers compared with control mix (0% fiber. Hybrid high strength concrete with steel and polypropylene fibers showed superior compressive, splitting, flexural strengths over the others concrete without or with single fibers content. The test results indicate that the maximum increase in compressive and flexural strengths are obtains with the hybridization ratio (70%steel + 30% polypropylene and were equal to 14.54% and 23.34% respectively, compared with the control mix. While, the maximum increase in splitting tensile strength with (100% steel fiber + 0 polypropylene is 21.19%. 

  17. Notched Strength of Woven Fabric Kenaf Composites with Different Fiber Orientations

    Directory of Open Access Journals (Sweden)

    Ahmad Hilton

    2017-01-01

    Full Text Available The awareness of implementing sustainable materials in construction industry is gaining good attention among engineers worldwide. Kenaf fibers are local renewable materials to combine with epoxy polymers matrix in producing lightweight composite materials which may replace imported synthetic fiber composites especially in developing countries. Other benefits of using kenaf fiber composites are relatively cheap, less abrasive and less hazardous during fabrication handling. Current study investigates parametric study on notched strength of woven fabric kenaf composite plates with different fiber orientations and circular hole sizes. Stress concentration occurred at the notch edge promotes to micro-damage events such as matrix cracking and fiber fracture as remote tensile loading applied. Current study showed that 0° fiber orientation gives optimum notched strength, plates with larger fiber tilting than 0° are associated with further strength reduction. Kenaf fibers give an alternative to material designers to opt woven fabric kenaf composites in low and medium load bearing applications.

  18. Bending strength and fracture surface topography of natural fiber-reinforced shell for investment casting process

    Directory of Open Access Journals (Sweden)

    Kai Lu

    2016-05-01

    Full Text Available In order to improve the properties of silica sol shell for investment casting process, various contents of cattail fibers were added into the slurry to prepare a fiber-reinforced shell in the present study. The bending strength of fiber-reinforced shell was investigated and the fracture surfaces of shell specimens were observed using SEM. It is found that the bending strength increases with the increase of fiber content, and the bending strength of a green shell with 1.0 wt.% fiber addition increases by 44% compared to the fiber-free shell. The failure of specimens of the fiber-reinforced green shell results from fiber rupture and debonding between the interface of fibers and adhesive under the bending load. The micro-crack propagation in the matrix is inhibited by the micro-holes for ablation of fibers in specimens of the fiber-reinforced shell during the stage of being fired. As a result, the bending strength of specimens of the fired shell had no significant drop. Particularly, the bending strength of specimens of the fired shell reinforced with 0.6wt.% fiber reached the maximum value of 4.6 MPa.

  19. The tensile strength of mechanical joint prototype of lontar fiber composite

    Science.gov (United States)

    Bale, Jefri; Adoe, Dominggus G. H.; Boimau, Kristomus; Sakera, Thomas

    2018-03-01

    In the present study, an experimental activity has been programmed to investigate the effect of joint prototype configuration on tensile strength of lontar (Borassus Flabellifer) fiber composite. To do so, a series of tests were conducted to establish the tensile strength of different joint prototype configuration specimen of lontar fiber composite. In addition, post observation of macroscope was used to map damage behavior. The analysis of lontar fiber composite is a challenge since the material has limited information than others natural fiber composites materials. The results shown that, under static tensile loading, the tensile strength of 13 MPa produced by single lap joint of lontar fiber composite is highest compare to 11 MPa of tensile strength generated by step lap joint and double lap joint where produced the lowest tensile strength of 6 MPa. It is concluded that the differences of tensile strength depend on the geometric dimensions of the cross-sectional area and stress distribution of each joint prototype configuration.

  20. Environmental effects on the tensile strength of chemically vapor deposited silicon carbide fibers

    Science.gov (United States)

    Bhatt, R. T.; Kraitchman, M. D.

    1985-01-01

    The room temperature and elevated temperature tensile strengths of commercially available chemically vapor-deposited (CVD) silicon carbide fibers were measured after 15 min heat treatment to 1600 C in various environments. These environments included oxygen, air, argon and nitrogen at one atmosphere and vacuum at 10/9 atmosphere. Two types of fibers were examined which differed in the SiC content of their carbon-rich coatings. Threshold temperature for fiber strength degradation was observed to be dependent on the as-received fiber-flaw structure, on the environment and on the coating. Fractographic analyses and flexural strength measurements indicate that tensile strength losses were caused by surface degradation. Oxidation of the surface coating is suggested as one possible degradation mechanism. The SiC fibers containing the higher percentage of SiC near the surface of the carbon-rich coating show better strength retention and higher elevated temperature strength.

  1. The effect of post material on the characteristic strength of fatigued endodontically treated teeth.

    Science.gov (United States)

    Pereira, Jefferson Ricardo; do Valle, Accácio Lins; Shiratori, Fabio Kenji; Ghizoni, Janaina Salomon; Bonfante, Estevam Augusto

    2014-11-01

    The biomechanical properties of post systems may become more important as the amount of remaining tooth structure decreases, thus different materials may influence the characteristic strength of fatigued endodontically treated teeth. The purpose of this study was to assess the characteristic strength and probability of survival of endodontically treated teeth restored with different intraradicular post systems. Forty human maxillary canines with similar root lengths were randomly divided into 4 groups (n=10): cast post and core, stainless-steel prefabricated post, carbon-fiber post, and glass-fiber post. Cores and metallic crowns were fabricated for all specimens. Restored teeth were exposed to mechanical fatigue (250,000 cycles) in a controlled chewing simulator. Each intact specimen was mounted in a special device and aligned at a 45-degree angle to the long axis of the tooth. A universal testing machine was used to apply a static load at a crosshead speed of 0.5 mm/min until specimen failure. The maximum value was recorded in newtons (N). Probability Weibull curves (2-sided 90% confidence bounds) were calculated for each group, and a probability of survival as a function of load at failure was plotted for the groups. A significantly higher characteristic strength was observed for groups carbon-fiber post (755.82 N) and cast post and core (750.6 N) (P<.05) compared with glass-fiber post (461.35 N) and stainless-steel prefabricated post (524.78 N) groups. All the roots in the cast post and core group demonstrated catastrophic fracture, whereas the remaining groups had no root fractures. Prefabricated posts made of glass fiber and stainless steel showed significantly lower characteristic strength and probability of survival than cast post and core, whereas crowns with carbon-fiber posts presented a single load similar to the fracture values of cast posts. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All

  2. Water absorption and tensile strength degradation of Petung bamboo (Dendrocalamus asper) fiber-reinforced polymeric composites

    NARCIS (Netherlands)

    Judawisastra, H.; Sitohang, Ramona; Rosadi, M. S.

    2017-01-01

    Bamboo fibers have attracted great interest and are believed to have the potential as natural fiber for reinforcing polymer composites. This research aims to study water absorption behavior and its effect to tensile strength of the composites made from petung bamboo fiber, which is one of the most

  3. Novel fiber design with the characteristics similar to LEAF

    CERN Document Server

    Tewari, R; Jakubczyk, Z J

    2002-01-01

    A novel fiber design has been proposed for a (+d) non zero dispersion shifted fiber (NZDSF). The obtained characteristics of this fiber (such as Petermann II-mode field diameter, group delay, group velocity dispersion, dispersion slope, and effective area) are in good agreement with the commercially available (+D) NZDSF with the trade name LEAF. (6 refs).

  4. Sensing characteristics of birefringent microstructured polymer optical fiber

    DEFF Research Database (Denmark)

    Szczurowski, Marcin K.; Frazao, Orlando; Baptista, J. M.

    2011-01-01

    We experimentally studied several sensing characteristics of a birefringent microstructured polymer optical fiber. The fiber exhibits a birefringence of the order 2×10-5 at 1.3 μm because of two small holes adjacent to the core. In this fiber, we measured spectral dependence of phase and group mo...

  5. Bending Characteristics Change of Long-Period fiber Grating due to Co-doping of Boron for Optical fiber Sensors

    International Nuclear Information System (INIS)

    Moon, Dae Seung; Chung, Young Joo

    2005-01-01

    In long-period fiber grating (LPFG) to be made up optical fiber sensors, resonance coupling occurs between the forward-propagating core mode and cladding modes at the wavelength that satisfy the Phase matching condition. The resonance wavelength and the coupling strength depends strongly on the external environment like temperature, strain, and ambient index. These characteristics can be utilized for various applications as optical fiber sensors. Fabrication of optical fiber gratings is typically based on the photosensitivity effect, i.e. the permanent change of the refractive index upon irradiation of the UV beam, and therefore, fabrication of the optical fiber with high phososensitivity is an important part of the research on optical fiber gratings. In this work, we measured the effort of to-doping of boron on the index difference between the core and cladding of the optical fiber and the sensitivity of the LPFC to the temperature and bending changes. We observed that the index difference between the core and the cladding decreased by (1.69x10 -4 /SCCM) and the temperature sensitivity of the resonance wavelength shirt decreased by (0.01145nm/ .deg. C/SCCM). The dependence or the bending-induced changes or the transmission characteristics of LPFG on the tore-cladding index difference was investigated experimentally. The measurement results indicate that the bending sensitivity increases as the index difference decreases

  6. Strength and dynamic characteristics analyses of wound composite axial impeller

    Science.gov (United States)

    Wang, Jifeng; Olortegui-Yume, Jorge; Müller, Norbert

    2012-03-01

    A low cost, light weight, high performance composite material turbomachinery impeller with a uniquely designed blade patterns is analyzed. Such impellers can economically enable refrigeration plants to use water as a refrigerant (R718). A strength and dynamic characteristics analyses procedure is developed to assess the maximum stresses and natural frequencies of these wound composite axial impellers under operating loading conditions. Numerical simulation using FEM for two-dimensional and three-dimensional impellers was investigated. A commercially available software ANSYS is used for the finite element calculations. Analysis is done for different blade geometries and then suggestions are made for optimum design parameters. In order to avoid operating at resonance, which can make impellers suffer a significant reduction in the design life, the designer must calculate the natural frequency and modal shape of the impeller to analyze the dynamic characteristics. The results show that using composite Kevlar fiber/epoxy matrix enables the impeller to run at high tip speed and withstand the stresses, no critical speed will be matched during start-up and shut-down, and that mass imbalances of the impeller shall not pose a critical problem.

  7. Swelling Characteristics and Tensile Properties of Natural Fiber ...

    African Journals Online (AJOL)

    The swelling behavior and tensile strength of natural fiber-reinforced plastic in premium motor spirit (PMS), dual purpose kerosene (DPK) and sea water have been studied. Composite formed by reinforcing polyester resin with Okam fibers was immersed in the selected solvents for 16 weeks (4 months). Swelling ...

  8. Identification of tensile strength properties of abaca fiber by weakest-linkage approach-statistic property of fiber diameter

    Science.gov (United States)

    Suardi; Homma, H.; Abubakar

    2018-02-01

    Fiber reinforced plastics or metals (FRPor FRM) are usually ecological materials, because their specific strength defined as the strengthperunit mass is much larger than metal, and weight ofmachines and structuresfor transport made ofFRP can be significantly reduced so that the consumption of fossil fuel scan be saved to result in tremendous reduction of CO2emissions. However, when we consider life cycle assessment (LCA) of synthetic fibers like carbon fiber and glass fiber, we can recognize much CO2 emission in production of these fibers. Therefore, more ecological reinforcement fibers must be developed. For this end, we should utilization cellulose fibers derived from plant tissue structure as an alternative fibers for synthetic fibers, which are considered as carbon neutral materials, and natural degraded material. This study selectsabaca fiber, which is a natural fiber and is abundant in Indonesia, but its usagehas not been optimized for engineering material. The purpose of this study is to identify the mechanical strength of a single abaca fiber by statistical approach. First, weakest link theory and Weibull theory are used to discuss experimental data. 90 specimens of almost identical geometry and biological aspects are tested under tension. These data are analyzed by Weibull theory or other statistical theory. Final target is to look into optimal method to reduce scatter ratio, ratio of standard deviation to mean value, of less than 0.1, which is the level of metallic materials. If we can reduce scatter ration to such level, we can design machines and structures using abaca fiber in the same way as carbon fibers or glass fibers. Summary of Diameter Measurement the all mean value is 0.1 and standardeviasi. The t-Test showed that mean value of each part is estimated as sampling from group with the same mean value, at confidence level of 99%.

  9. Differentiation of molecular chain entanglement structure through laser Raman spectrum measurement of High strength PET fibers under stress

    Science.gov (United States)

    Go, D.; Takarada, W.; Kikutani, T.

    2017-10-01

    The aim of this study was to investigate the mechanism for the improvement of mechanical properties of poly(ethylene terephthalate) (PET) fibers based on the concept of controlling the state of molecular entanglement. For this purpose, five different PET fibers were prepared through either the conventional melt spinning and drawing/annealing process or the high-speed melt spinning process. In both cases, the melt spinning process was designed so as to realize different Deborah number conditions. The prepared fibers were subjected to the laser Raman spectroscopy measurement and the characteristics of the scattering peak at around 1616 cm-1, which corresponds to the C-C/C=C stretching mode of the aromatic ring in the main chain, were investigated in detail. It was revealed that the fibers drawn and annealed after the melt spinning process of lower Deborah number showed higher tensile strength as well as lower value of full width at half maximum (FWHM) in the laser Raman spectrum. Narrow FWHM was considered to represent the homogeneous state of entanglement structure, which may lead to the higher strength and toughness of fibers because individual molecular chains tend to bare similar level of tensile stress when the fiber is stretched. In case of high-speed spun fibers prepared with a high Deborah number condition, the FWHM was narrow presumably because much lower tensile stress in comparison with the drawing/annealing process was applied when the fiber structure was developed, however the value increased significantly upon applying tensile load to the fibers during the laser Raman spectrum measurement. From these results, it was concluded that the Laser Raman spectroscopy could differentiate molecular chain entanglement structure of various fiber samples, in that low FWHM, which corresponds to either homogeneous state of molecular entanglement or lower level of mean residual stress, and small increase of FWTH upon applying tensile stress are considered to be the key

  10. High efficient and continuous surface modification of carbon fibers with improved tensile strength and interfacial adhesion

    Science.gov (United States)

    Sun, Jingfeng; Zhao, Feng; Yao, Yue; Jin, Zhen; Liu, Xu; Huang, Yudong

    2017-08-01

    Most of the surface modification technologies for carbon fibers, no matter in laboratory scale or for commercial manufacture, are accompanied by a simultaneous decrease in tensile strength. In this paper, a feasible and high efficient strategy for carbon fiber treatment which could obviously improve both tensile strength and interfacial adhesion was proposed. Continuously moving carbon fibers were treated with atmospheric helium plasma for 1 min, followed by a 5 min pyrolytic carbon deposition using ethanol as precursor at 800 °C. The effects of the new approach were characterized by SEM, AFM, nanoindentation, XPS, Raman, wettability analysis, single fiber tensile strength testing and single fiber pull-out testing. After modification, pyrolytic carbon coating was deposited on the fiber surface uniformly, and the roughness and surface energy increased significantly. The single fiber tensile testing results indicate that the resulting fiber strength increased 15.7%, rising from 3.13 to 3.62 GPa. Meanwhile, the interfacial shear strength of its epoxy composites increased from 65.3 to 83.5 MPa. The comparative studies of carbon fibers modified with commercial anodic oxidation and sizing were also carried out. The results demonstrate that the new method can be utilized in the carbon fiber manufacture process and is more efficient than the traditional approaches.

  11. Adsorption characteristics of activated carbon hollow fibers

    Directory of Open Access Journals (Sweden)

    B. V. Kaludjerović

    2009-01-01

    Full Text Available Carbon hollow fibers were prepared with regenerated cellulose or polysulfone hollow fibers by chemical activation using sodium phosphate dibasic followed by the carbonization process. The activation process increases the adsorption properties of fibers which is more prominent for active carbone fibers obtained from the cellulose precursor. Chemical activation with sodium phosphate dibasic produces an active carbon material with both mesopores and micropores.

  12. Strength behaviour of kerosene coated coir fiber-reinforced expansive soil

    OpenAIRE

    Ramasubbarao Godavarthi Venkata

    2014-01-01

    Coir fibers are extracted from the husks surrounding the coconut. Coir fibers can be effectively used as reinforcing material but it has less durability and hence coir fiber coated with kerosene is used as reinforcement in the present study. The objective of the present investigation is to study the strength behavior of expansive soil reinforced with 5mm long randomly distributed kerosene coated coir fibers in 0% (unreinforced), 0.5%, 1% and 1.5% by dry wei...

  13. The Effect of Fiber Strength Stochastics and Local Fiber Volume Fraction on Multiscale Progressive Failure of Composites

    Science.gov (United States)

    Ricks, Trenton M.; Lacy, Jr., Thomas E.; Bednarcyk, Brett A.; Arnold, Steven M.

    2013-01-01

    Continuous fiber unidirectional polymer matrix composites (PMCs) can exhibit significant local variations in fiber volume fraction as a result of processing conditions that can lead to further local differences in material properties and failure behavior. In this work, the coupled effects of both local variations in fiber volume fraction and the empirically-based statistical distribution of fiber strengths on the predicted longitudinal modulus and local tensile strength of a unidirectional AS4 carbon fiber/ Hercules 3502 epoxy composite were investigated using the special purpose NASA Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC); local effective composite properties were obtained by homogenizing the material behavior over repeating units cells (RUCs). The predicted effective longitudinal modulus was relatively insensitive to small (8%) variations in local fiber volume fraction. The composite tensile strength, however, was highly dependent on the local distribution in fiber strengths. The RUC-averaged constitutive response can be used to characterize lower length scale material behavior within a multiscale analysis framework that couples the NASA code FEAMAC and the ABAQUS finite element solver. Such an approach can be effectively used to analyze the progressive failure of PMC structures whose failure initiates at the RUC level. Consideration of the effect of local variations in constituent properties and morphologies on progressive failure of PMCs is a central aspect of the application of Integrated Computational Materials Engineering (ICME) principles for composite materials.

  14. Optimization of mechanical strength of titania fibers fabricated by direct drawing

    Science.gov (United States)

    Hanschmidt, Kelli; Tätte, Tanel; Hussainova, Irina; Part, Marko; Mändar, Hugo; Roosalu, Kaspar; Chasiotis, Ioannis

    2013-11-01

    Nanostructured polycrystalline titania (TiO2) microfibers were produced by direct drawing from visco-elastic alkoxide precursors. The fiber crystallinity and grain size were shown to depend on post-treatment calcination temperature. Tensile tests with individual fibers showed strong sensitivity of the elastic modulus and the tensile strength to microstructural details of the fibers. The elastic modulus of as-fabricated fibers increased about 10 times after calcination at 700 ∘C, while the strain at failure remained almost the same at ˜1.4 %. The highest tensile strength of more than 800 MPa was exhibited by nanoscale grained fibers with a bimodal grain size distribution consisting of rutile grains embedded into an anatase matrix. This structure is believed to have reduced the critical defect size, and thus increased the tensile strength. The resultant fibers showed properties that were appropriate for reinforcement of different matrixes.

  15. Influence of surface modified basalt fiber on strength of cinder lightweight aggregate concrete

    Science.gov (United States)

    Xiao, Liguang; Li, Jiheng; Liu, Qingshun

    2017-12-01

    In order to improve the bonding and bridging effect between volcanic slag lightweight aggregate concrete cement and basalt fiber, The basalt fiber was subjected to etching and roughening treatment by NaOH solution, and the surface of the basalt fiber was treated with a mixture of sodium silicate and micro-silica powder. The influence of modified basalt fiber on the strength of volcanic slag lightweight aggregate concrete was systematically studied. The experimental results show that the modified basalt fiber volcanic slag lightweight aggregate concrete has a flexural strength increased by 47%, the compressive strength is improved by 16% and the toughness is increased by 27% compared with that of the non-fiber.

  16. Strength and fracture behavior of aluminide matrix composites with ceramic fibers

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, M.; Suganuma, K.; Niihara, K.

    1999-07-01

    This paper investigates the fracture behavior of FeAl and Ni{sub 3}Al matrix composites with ceramic continuous fibers 8.5--10 {micro}m in diameter. When stress is applied to these composites, multiple-fracture of fibers predominantly occurs before matrix cracking, because the load carried by the fibers reaches their fracture strength. Fragments which remain longer than the critical length can provide significant strengthening through load bearing even though fiber breaking has occurred. The ultimate fracture strength of the composites also depends on stress relaxation by plastic deformation of the matrix at a crack tip in the multiple-fractured fibers. Ductilizing of the matrix by B doping improves the ultimate strength at ambient temperatures in both composites. However, their mechanical properties at elevated temperatures are quite different. In the case of Ni{sub 3}Al matrix composites, embrittlement of the matrix is undesirable for high strength and reliability at 873--973 K.

  17. Properties of Sugarcane Fiber on the Strength of the Normal and Lightweight Concrete

    Directory of Open Access Journals (Sweden)

    Sheikh Khalid Faisal

    2017-01-01

    Full Text Available The usage of natural fiber in construction are widely used in building materials engineering. However, using sugarcane fiber waste material as a natural in construction is very precious, because it can increase crack control and ductility, brittle concrete. Furthermore, the usage of sugarcane in construction can reduce of environmental pollution.In this study, a mixture of sugarcane fiber to be used in normal grade concrete and lightweight concrete to determine whether there is an increase in the compressive and tensile strength of the concrete. The objective of this study was to determine the compressive and tensile strength between control concrete and concrete mix with sugarcane fiber. In addition, the optimal volume of sugarcane fiber in the concrete mixture where the percentage of sugarcane fiber used was 0.5%, 1.0% and 1.5%. Compessive strength was tested on days 7 and 28 after curing test is carried out. Meanwhile, the tensile test, has been carried out to measure the tensile strength of sugarcane fiber relations in concrete mixes only at 28 day curing. Result of the testing showed that the optimum value containing admixtures of sugarcane is 0.5%. This percentage get the value of compressive strength is nearest with concrete control and the value of tensile strength is higher than concrete control and also the timing of concrete to cracked getting slower. Therefore, the use of sugarcane fiber suitable for addition that do not exceed 0.5% of the concrete mixture.

  18. Alkali-resistant glass fiber reinforced high strength concrete in simulated aggressive environment

    International Nuclear Information System (INIS)

    Kwan, W.H.; Cheah, C.B.; Ramli, M.; Chang, K.Y.

    2018-01-01

    The durability of the alkali-resistant (AR) glass fiber reinforced concrete (GFRC) in three simulated aggresive environments, namely tropical climate, cyclic air and seawater and seawater immersion was investigated. Durability examinations include chloride diffusion, gas permeability, X-ray diffraction (XRD) and scanning electron microscopy examination (SEM). The fiber content is in the range of 0.6 % to 2.4 %. Results reveal that the specimen containing highest AR glass fiber content suffered severe strength loss in seawater environment and relatively milder strength loss under cyclic conditions. The permeability property was found to be more inferior with the increase in the fiber content of the concrete. This suggests that the AR glass fiber is not suitable for use as the fiber reinforcement in concrete is exposed to seawater. However, in both the tropical climate and cyclic wetting and drying, the incorporation of AR glass fiber prevents a drastic increase in permeability. [es

  19. Coating of carbon nanotube fibers: variation of tensile properties, failure behavior and adhesion strength

    Directory of Open Access Journals (Sweden)

    Edith eMäder

    2015-07-01

    Full Text Available An experimental study of the tensile properties of CNT fibers and their interphasial behavior in epoxy matrices is reported. One of the most promising applications of CNT fibers is their use as reinforcement in multifunctional composites. For this purpose, an increase of the tensile strength of the CNT fibers in unidirectional composites as well as strong interfacial adhesion strength is desirable. However, the mechanical performance of the CNT fiber composites manufactured so far is comparable to that of commercial fiber composites. The interfacial properties of CNT fiber/polymer composites have rarely been investigated and provided CNT fiber/epoxy interfacial shear strength of 14.4 MPa studied by the microbond test.In order to improve the mechanical performance of the CNT fibers, an epoxy compatible coating with nano-dispersed aqueous based polymeric film formers and low viscous epoxy resin, respectively, was applied. For impregnation of high homogeneity, low molecular weight epoxy film formers and polyurethane film formers were used. The aqueous based epoxy film formers were not crosslinked and able to interdiffuse with the matrix resin after impregnation. Due to good wetting of the individual CNT fibers by the film formers, the degree of activation of the fibers was improved leading to increased tensile strength and Young’s modulus. Cyclic tensile loading and simultaneous determination of electric resistance enabled to characterize the fiber’s durability in terms of elastic recovery and hysteresis.The pull-out tests and SEM study reveal different interfacial failure mechanisms in CNT fiber/epoxy systems for untreated and film former treated fibers, on the one hand, and epoxy resin treated ones, on the other hand. The epoxy resin penetrated between the CNT bundles in the reference or film former coated fiber, forming a relatively thick CNT/epoxy composite layer and thus shifting the fracture zone within the fiber. In contrast to this

  20. High Strength Concrete Columns under Axial Compression Load: Hybrid Confinement Efficiency of High Strength Transverse Reinforcement and Steel Fibers

    Science.gov (United States)

    Perceka, Wisena; Liao, Wen-Cheng; Wang, Yo-de

    2016-01-01

    Addition of steel fibers to high strength concrete (HSC) improves its post-peak behavior and energy absorbing capability, which can be described well in term of toughness. This paper attempts to obtain both analytically and experimentally the efficiency of steel fibers in HSC columns with hybrid confinement of transverse reinforcement and steel fibers. Toughness ratio (TR) to quantify the confinement efficiency of HSC columns with hybrid confinement is proposed through a regression analysis by involving sixty-nine TRs of HSC without steel fibers and twenty-seven TRs of HSC with hybrid of transverse reinforcement and steel fibers. The proposed TR equation was further verified by compression tests of seventeen HSC columns conducted in this study, where twelve specimens were reinforced by high strength rebars in longitudinal and transverse directions. The results show that the efficiency of steel fibers in concrete depends on transverse reinforcement spacing, where the steel fibers are more effective if the spacing transverse reinforcement becomes larger in the range of 0.25–1 effective depth of the section column. Furthermore, the axial load–strain curves were developed by employing finite element software (OpenSees) for simulating the response of the structural system. Comparisons between numerical and experimental axial load–strain curves were carried out. PMID:28773391

  1. Preparation of carbon fiber unsaturated sizing agent for enhancing interfacial strength of carbon fiber/vinyl ester resin composite

    Science.gov (United States)

    Jiao, Weiwei; Cai, Yemeng; Liu, Wenbo; Yang, Fan; Jiang, Long; Jiao, Weicheng; Wang, Rongguo

    2018-05-01

    The practical application of carbon fiber (CF) reinforced vinyl ester resin (VE) composite was hampered seriously by the poor interfacial adhesion property. In this work, a novel unsaturated sizing agent was designed and prepared to improve the interfacial strength by covalently bonding CF with VE matrix. The main component of the sizing agent, N-(4‧4-diaminodiphenyl methane)-2-hydroxypropyl methacrylate (DMHM), was synthesized and confirmed by FTIR and NMR. XPS results of sized carbon fiber (SCF) showed that DMHM has adhered to desized fiber surface and reacted with some active functional groups on the surface. The SCF was characterized by high surface roughness and surface energy (especially the polar component), which means better wettability by VE. As a result, the interface shear strength and interlaminar shear strength of SCF/VE composite were enhanced by 96.56% and 66.07% respectively compared with CF/VE composite, benefited mainly from the strong and tough interphase.

  2. Study of the strength characteristics of protein-based lightweight ...

    African Journals Online (AJOL)

    Compressive strength test was carried out on the protein-based lightweight foamed concrete produced with cement partially replaced by rice husk ash to ascertain its strength characteristics. Standard concrete cubes of 150 x 150 x 150 mm were produced using ordinary Portland cement (OPC), fine aggregate, aqueous ...

  3. Effects of bond primers on bending strength and bonding of glass fibers in fiber-embedded maxillofacial silicone prostheses.

    Science.gov (United States)

    Hatamleh, Muhanad M; Watts, David C

    2011-02-01

    To evaluate the effect of three commonly used bond primers on the bending strength of glass fibers and their bond strength to maxillofacial silicone elastomer after 360 hours of accelerated daylight aging. Eighty specimens were fabricated by embedding resin-impregnated fiber bundles (1.5-mm diameter, 20-mm long) into maxillofacial silicone elastomer M511 (Cosmesil). Twenty fiber bundles served as control and did not receive surface treatment with primers, whereas the remaining 60 fibers were treated with three primers (n = 20): G611 (Principality Medical), A-304 (Factor II), and A-330-Gold (Factor II). Forty specimens were dry stored at room temperature (23 ± 1°C) for 24 hours, and the remaining specimens were aged using an environmental chamber under accelerated exposure to artificial daylight for 360 hours. The aging cycle included continuous exposure to quartz-filtered visible daylight (irradiance 760 W/m(2) ) under an alternating weathering cycle (wet for 18 minutes, dry for 102 minutes). Pull-out tests were performed to evaluate bond strength between fiber bundles and silicone using a universal testing machine at 1 mm/min crosshead speed. A 3-point bending test was performed to evaluate the bending strength of the fiber bundles. One-way Analysis of Variance (ANOVA), Bonferroni post hoc test, and an independent t-test were carried out to detect statistical significances (p accelerated daylight aging. Treatment with primer and accelerated daylight aging increased bending strength of glass fibers. © 2011 by The American College of Prosthodontists.

  4. The effect of the production method on the mechanical strength of an alumina porous hollow fiber

    NARCIS (Netherlands)

    de Wit, Patrick; van Daalen, Frederique S.; Benes, Nieck E.

    2017-01-01

    The mechanical strength of inorganic porous hollow fibers is an important property and is strongly affected by the production method. Three production methods for fibers are compared: non-solvent induced phase separation (NIPS), bio-ionic gelation with an internal multivalent ion source (BIG-I), and

  5. Enhancement of hydrophobicity and tensile strength of muga silk fiber by radiofrequency Ar plasma discharge

    International Nuclear Information System (INIS)

    Gogoi, D.; Choudhury, A.J.; Chutia, J.; Pal, A.R.; Dass, N.N.; Devi, D.; Patil, D.S.

    2011-01-01

    The hydrophobicity and tensile strength of muga silk fiber are investigated using radiofrequency (RF) Ar plasma treatment at various RF powers (10-30 W) and treatment times (5-20 min). The Ar plasma is characterized using self-compensated Langmuir and emissive probe. The ion energy is observed to play an important role in determining the tensile strength and hydrophobicity of the plasma treated fibers. The chemical compositions of the fibers are observed to be affected by the increase in RF power rather than treatment time. XPS study reveals that the ions that are impinging on the substrates are mainly responsible for the cleavage of peptide bond and side chain of amino acid groups at the surface of the fibers. The observed properties (tensile strength and hydrophobicity) of the treated fibers are found to be dependent on their variation in atomic concentration and functional composition at the surfaces. All the treated muga fibers exhibit almost similar thermal behavior as compared to the virgin one. At RF power of 10 W and treatment time range of 5-20 min, the treated fibers exhibit properties similar to that of the virgin one. Higher RF power (30 W) and the increase in treatment time deteriorate the properties of the fibers due to incorporation of more surface roughness caused by sufficiently high energetic ion bombardment. The properties of the plasma treated fibers are attempted to correlate with the XPS analysis and their surface morphologies.

  6. Micromechanical modeling of strength and damage of fiber reinforced composites

    Energy Technology Data Exchange (ETDEWEB)

    Mishnaevsky, L. Jr.; Broendsted, P.

    2007-03-15

    The report for the first year of the EU UpWind project includes three parts: overview of concepts and methods of modelling of mechanical behavior, deformation and damage of unidirectional fiber reinforced composites, development of computational tools for the automatic generation of 3D micromechanical models of fiber reinforced composites, and micromechanical modelling of damage in FRC, and phenomenological analysis of the effect of frequency of cyclic loading on the lifetime and damage evolution in materials. (au)

  7. Achieving Hydrogen Storage Goals through High-Strength Fiber Glass - Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hong [PPG Industries, Inc., Cheswick, PA (United States); Johnson, Kenneth I. [PPG Industries, Inc., Cheswick, PA (United States); Newhouse, Norman L. [PPG Industries, Inc., Cheswick, PA (United States)

    2017-06-05

    Led by PPG and partnered with Hexagon Lincoln and Pacific Northwest National Laboratory (PNNL), the team recently carried out a project “Achieving Hydrogen Storage Goals through High-Strength Fiber Glass”. The project was funded by DOE’s Fuel Cell Technologies office within the Office of Energy Efficiency and Renewable Energy, starting on September 1, 2014 as a two-year project to assess technical and commercial feasibilities of manufacturing low-cost, high-strength glass fibers to replace T700 carbon fibers with a goal of reducing the composite total cost by 50% of the existing, commercial 700 bar hydrogen storage tanks used in personal vehicles.

  8. Studying of Compressive, Tensile and Flexural Strength of Concrete by Using Steel Fibers

    Directory of Open Access Journals (Sweden)

    Muslim Abdul-Ameer

    2016-12-01

    Full Text Available This research aims to study the effect of adding steel fibers on the mechanical properties of concrete. Steel fiber has a very significant effect on concrete because it delays the propagation of micro cracks that generate due to loading on concrete members such as beams and slabs, therefore ,it increases the strength of concrete. The steel fiber was used in this study as a percentage of the volume of concrete. Mix proportion was 1: 2:4 (cement: sand: gravel by volume for all mixes and using 0% as (control mix,0.1 %,0.2%,0.5 % and 1.0% of steel fibers, these ratios leads to increase the compressive, tensile ,and flexural strength of concrete, where the improvement in flexural strength was significant

  9. Isolation of aramid nanofibers for high strength multiscale fiber reinforced composites

    Science.gov (United States)

    Lin, Jiajun; Patterson, Brendan A.; Malakooti, Mohammad H.; Sodano, Henry A.

    2018-03-01

    Aramid fibers are famous for their high specific strength and energy absorption properties and have been intensively used for soft body armor and ballistic protection. However, the use of aramid fiber reinforced composites is barely observed in structural applications. Aramid fibers have smooth and inert surfaces that are unable to form robust adhesion to polymeric matrices due to their high crystallinity. Here, a novel method to effectively integrate aramid fibers into composites is developed through utilization of aramid nanofibers. Aramid nanofibers are prepared from macroscale aramid fibers (such as Kevlar®) and isolated through a simple and scalable dissolution method. Prepared aramid nanofibers are dispersible in many polymers due to their improved surface reactivity, meanwhile preserve the conjugated structure and likely the strength of their macroscale counterparts. Simultaneously improved elastic modulus, strength and fracture toughness are observed in aramid nanofiber reinforced epoxy nanocomposites. When integrated in continuous fiber reinforced composites, aramid nanofibers can also enhance interfacial properties by forming hydrogen bonds and π-π coordination to bridge matrix and macroscale fibers. Such multiscale reinforcement by aramid nanofibers and continuous fibers results in strong polymeric composites with robust mechanical properties that are necessary and long desired for structural applications.

  10. Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

    OpenAIRE

    Gao, Lei; Hu, Guohui; Xu, Nan; Fu, Junyi; Xiang, Chao; Yang, Chen

    2015-01-01

    In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0...

  11. Effects of ion beam irradiation on the microstructures and strengths of different carbon fibers

    International Nuclear Information System (INIS)

    Oku, Tatsuo; Kurumada, Akira; Kawamata, Kiyohiro; Inagaki, Michio

    1998-01-01

    The high energy argon ion was irradiated to different carbon fibers with various microstructures. The cross-sectional structures and strengths properties have been evaluated before and after ion irradiation. As a result, the diameter of fibers decreased due to ion irradiation, except for the fiber with dual structure. The tensile strength also decreased due to ion irradiation, except for fibers which were not heat-treated. This suggests that it is necessary to consider not only the defects in the vertical cross-section but also changes in defect structures in the axial direction. The results of computer simulation indicated that argon ion with 175MeV/1μA produced homogeneous defects in the carbon fibers with the diameter of about 20 μm. (author)

  12. Characteristics of continuous unidirectional kenaf fiber reinforced epoxy composites

    International Nuclear Information System (INIS)

    Mahjoub, Reza; Yatim, Jamaludin Mohamad; Mohd Sam, Abdul Rahman; Raftari, Mehdi

    2014-01-01

    Highlights: • To show the potential of continuous kenaf fiber to use in bio-composite. • To introduce new method of hand lay-up for fabricating bio-fiber composite. • To characterize the properties of kenaf fiber epoxy composite. • Morphology of the fracture area by using of SEM. • To use analytical method to predict the bio-composite properties. - Abstract: Kenaf fibers generally has some advantages such as eco-friendly, biodegradability, renewable nature and lighter than synthetic fibers. The aims of the study are to characterize and evaluate the physical and mechanical properties of continuous unidirectional kenaf fiber epoxy composites with various fiber volume fractions. The composites materials and sampling were prepared in the laboratory by using the hand lay-up method with a proper fabricating procedure and quality control. Samples were prepared based on ASTM: D3039-08 for tensile test and the scanning electron microscopy (SEM) was employed for microstructure analysis to observe the failure mechanisms in the fracture planes. A total of 40 samples were tested for the study. Results from the study showed that the rule of mixture (ROM) analytical model has a close agreement to predict the physical and tensile properties of unidirectional kenaf fiber reinforced epoxy composites. It was also observed that the tensile strength, tensile modulus, ultimate strain and Poisson’s ratio of 40% fiber volume content of unidirectional kenaf fiber epoxy composite were 164 MPa, 18150 MPa, 0.9% and 0.32, respectively. Due to the test results, increasing the fiber volume fraction in the composite caused the increment in the tensile modulus and reduction in the ultimate tensile strain of composite

  13. Fiber length and pulping characteristics of switchgrass, alfalfa stems, hybrid poplar and willow biomasses.

    Science.gov (United States)

    Ai, Jun; Tschirner, Ulrike

    2010-01-01

    Switchgrass (Panicum virgatum), alfalfa stems (Medicago sativa), second year growth hybrid poplar (Populus) and willow (Salix spp.) were examined to determine fiber characteristics, pulping behavior and paper properties. Alfalfa stems and switchgrass both showed length weighted average fiber length (LWW) of 0.78 mm, a very narrow fiber length distribution and high fines content. Willow and hybrid poplar have lower fines content but a very low average fiber length (0.42 and 0.48 mm LWW). In addition, the four biomass species showed distinctly different chemical compositions. Switchgrass was defibered successfully using Soda and Soda Anthraquinone (AQ) pulping and demonstrated good paper properties. Both fast-growing wood species pulped well using the Kraft process, and showed acceptable tensile strength, but low tear strength. Alfalfa stems reacted very poorly to Soda and Soda AQ pulping but responded well to Kraft and Kraft AQ. Pulps with tensile and tear strength considerably higher than those found for commercial aspen pulps were observed for alfalfa. All four biomass species examined demonstrated low pulp yield. The highest yields were obtained with poplar and switchgrass (around 43%). Considering the short fibers and low yields, all four biomass types will likely only be used in paper manufacturing if they offer considerable economic advantage over traditional pulp wood.

  14. Optical characteristics of modified fiber tips in single fiber, laser Doppler flowmetry

    Science.gov (United States)

    Oberg, P. Ake; Cai, Hongming; Rohman, Hakan; Larsson, Sven-Erik

    1994-02-01

    Percutaneous laser Doppler flowmetry (LDF) and bipolar surface electromyography (EMG) were used simultaneously for measurement of skeletal muscle (trapezius) perfusion in relation to static load and fatigue. On-line computer (386 SX) processing of the LDF- and EMG- signals made possible interpretation of the relationship between the perfusion and the activity of the muscle. The single fiber laser Doppler technique was used in order to minimize the trauma. A ray-tracing program was developed in the C language by which the optical properties of the fiber and fiber ends could be simulated. Isoirradiance graphs were calculated for three fiber end types and the radiance characteristics were measured for each fiber end. The three types of fiber-tips were evaluated and compared in flow model measurements.

  15. Effect of different dispersants in compressive strength of carbon fiber cementitious composites

    Science.gov (United States)

    Lestari, Yulinda; Bahri, Saiful; Sugiarti, Eni; Ramadhan, Gilang; Akbar, Ari Yustisia; Martides, Erie; Khaerudini, Deni S.

    2013-09-01

    Carbon Fiber Cementitious Composites (CFCC) is one of the most important materials in smart concrete applications. CFCC should be able to have the piezoresistivity properties where its resistivity changes when there is applied a stress/strain. It must also have the compressive strength qualification. One of the important additives in carbon fiber cementitious composites is dispersant. Dispersion of carbon fiber is one of the key problems in fabricating piezoresistive carbon fiber cementitious composites. In this research, the uses of dispersants are methylcellulose, mixture of defoamer and methylcellulose and superplasticizer based polycarboxylate. The preparation of composite samples is similar as in the mortar technique according to the ASTM C 109/109M standard. The additives material are PAN type carbon fibers, methylcellulose, defoamer and superplasticizer (as water reducer and dispersant). The experimental testing conducts the compressive strength and resistivity at various curing time, i.e. 3, 7 and 28 days. The results obtained that the highest compressive strength value in is for the mortar using superplasticizer based polycarboxylate dispersant. This also shown that the distribution of carbon fiber with superplasticizer is more effective, since not reacting with the cementitious material which was different from the methylcellulose that creates the cement hydration reaction. The research also found that the CFCC require the proper water cement ratio otherwise the compressive strength becomes lower.

  16. Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical performance used as anodes of structural lithium-ion batteries

    International Nuclear Information System (INIS)

    Feng, Mengjie; Wang, Shubin; Yu, Yalin; Feng, Qihang; Yang, Jiping; Zhang, Boming

    2017-01-01

    Highlights: • Carboxyl functionalized CF is acquired by simple chemical oxidation method. • These CF have preserved the tensile strength, better electrochemical properties. • The presence of H_3PO_4 prevented the turbostratic carbon from over-oxidization. • There CF can be used as anodes of multifunctional structural battery. • The preservation and improvement is result from the hindered over-oxidization. - Abstract: Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical properties were acquired through a simple chemical oxidation method, and the proposed underlying mechanism was verified. The surface of carboxyl functionalizing carbon fibers is necessary in acquiring functional groups on the surface of carbon fibers to further improve the thermal, electrical or mechanical properties of the fibers. Functionalization should preserve the tensile strength and electrochemical properties of carbon fibers, because the anodes of structural batteries need to have high strength and electrochemical properties. Functionalized with mixed H_2SO_4/HNO_3 considerably reduced the tensile strength of carbon fibers. By contrast, the appearance of H_3PO_4 preserved the tensile strength of functionalized carbon fibers, reduced the dispersion level of tensile strength values, and effectively increased the concentration of functional acid groups on the surface of carbon fibers. The presence of phosphoric acid hindered the over-oxidation of turbostratic carbon, and consequently preserved the tensile strength of carbon fibers. The increased proportion of turbostratic carbon on the surface of carbon fibers concurrently enhanced the electrochemical properties of carbon fibers.

  17. In Situ Strength Model for Continuous Fibers and Multi-Scale Modeling the Fracture of C/SiC Composites

    Science.gov (United States)

    Zhang, Sheng; Gao, Xiguang; Song, Yingdong

    2018-04-01

    A new in situ strength model of carbon fibers was developed based on the distribution of defects to predict the stress-strain response and the strength of C/SiC composites. Different levels of defects in the fibers were considered in this model. The defects in the fibers were classified by their effects on the strength of the fiber. The strength of each defect and the probability that the defect appears were obtained from the tensile test of single fibers. The strength model of carbon fibers was combined with the shear-lag model to predict the stress-strain responses and the strengths of fiber bundles and C/SiC minicomposites. To verify the strength model, tensile tests were performed on fiber bundles and C/SiC minicomposites. The predicted and experimental results were in good agreement. Effects of the fiber length, the fiber number and the heat treatment on the final strengths of fiber bundles and C/SiC minicomposites were also discussed.

  18. Strength and conductivity of unidirectional copper composites reinforced by continuous SiC fibers

    International Nuclear Information System (INIS)

    Kimmig, S.; Allen, I.; You, J.H.

    2013-01-01

    A SiC long fiber-reinforced copper composite offers a beneficial combination of high strength and high thermal conductivity at elevated temperatures. Both properties make the composite a promising material for the heat sink of high-heat-flux components. In this work, we developed a novel Cu/SiC f composite using the Sigma fiber. Based on HIP technique, a metallurgical process was established for fabricating high quality specimens using a TiC interface coating. Extensive tensile tests were conducted on the unidirectionally reinforced composite at 20 °C and 300 °C for a wide range of fiber volume fraction (V f ). In this paper, a large amount of test data is presented. The transversal thermal conductivity varies from 260 to 130 W/mK at 500 °C as V f is increased from 13% to 37%. The tensile strength reached up to 1246 MPa at 20 °C for V f = 37.6%, where the fracture strain was limited to 0.8%. The data of both elastic modulus and ultimate strength exhibited a good agreement with the rule-of-mixture predictions indicating a high quality of the materials. The strength of the composite with the Sigma fibers turned out to be superior to those of the SCS6 fibers at 300 °C, although the SCS6 fiber actually has a higher strength than the Sigma fiber. The fractographic pictures of tension test and fiber push-out test manifested a sufficient interfacial bonding

  19. Carbon fiber/carbon nanotube reinforced hierarchical composites: Effect of CNT distribution on shearing strength

    DEFF Research Database (Denmark)

    Zhou, H. W.; Mishnaevsky, Leon; Yi, H. Y.

    2016-01-01

    The strength and fracture behavior of carbon fiber reinforced polymer composites with carbon nanotube (CNT) secondary reinforcement are investigated experimentally and numerically. Short Beam Shearing tests have been carried out, with SEM observations of the damage evolution in the composites. 3D...... CNT nanoreinforcement into the matrix and/or the sizing of carbon fiber/reinforced composites ensures strong increase of the composite strength. The effect of secondary CNTs reinforcement is strongest when some small addition of CNTs in the polymer matrix is complemented by the fiber sizing with high...... multiscale computational (FE) models of the carbon/polymer composite with varied CNT distributions have been developed and employed to study the effect of the secondary CNT reinforcement, its distribution and content on the strength and fracture behavior of the composites. It is shown that adding secondary...

  20. Geckolike high shear strength by carbon nanotube fiber adhesives

    Science.gov (United States)

    Maeno, Y.; Nakayama, Y.

    2009-01-01

    Carbon nanotube adhesives can adhere strongly to surfaces as a gecko does. The number of carbon nanotube layers is an important determinant of the contact area for adhesion. Balancing the catalyst ratio and buffer layer used for chemical vapor deposition processing controls the number of carbon nanotube layers and their distribution. The features of carbon nanotubes determine the shear strength of adhesion. Carbon nanotubes with a broad distribution of layers exhibit enhanced shear strength with equivalent adhesive capability to that of a natural Tokay Gecko (Gekko gecko)

  1. Fabrication of high strength PVA/SWCNT composite fibers by gel spinning

    OpenAIRE

    Xu, Xuezhu; Uddin, Ahmed Jalal; Aoki, Kenta; Gotoh, Yasuo; Saito, Takeshi; Yumura, Motoo

    2010-01-01

    High-strength composite fibers were prepared from polyvinyl alcohol (PVA) (Degree of polymerization: 1500) reinforced by single-walled carbon nanotubes (SWCNTs) containing few defects. The SWCNTs were dispersed in a 10 wt.% PVA/dimethylsulfoxide solution using a mechanical homogenizer that reduced the size of SWCNT aggregations to smaller bundles. The macroscopically homogeneous dispersion was extruded into cold methanol to form fibers by gel spinning followed by a hot-drawing. The tensile st...

  2. Strength and Deformability of Fiber Reinforced Cement Paste on the Basis of Basalt Fiber

    Directory of Open Access Journals (Sweden)

    Yury Barabanshchikov

    2016-01-01

    Full Text Available The research object of the paper is cement paste with the particulate reinforcement of basalt fiber. Regardless of fibers’ length at the same fiber cement mix workability and cement consumption equality compressive solidity of the specimens is reduced with increasing fiber content. This is due to the necessity to increase the water-cement ratio to obtain a given workability. The flexural stability of the specimens with increasing fiber content increments in the same conditions. There is an optimum value of the fibers’ dosage. That is why stability has a maximum when crooking. The basaltic fiber particulate reinforcement usage can abruptly increase the cement paste level limiting extensibility, which is extremely important in terms of crack resistance.

  3. A Theoretical Model for Estimation of Yield Strength of Fiber Metal Laminate

    Science.gov (United States)

    Bhat, Sunil; Nagesh, Suresh; Umesh, C. K.; Narayanan, S.

    2017-08-01

    The paper presents a theoretical model for estimation of yield strength of fiber metal laminate. Principles of elasticity and formulation of residual stress are employed to determine the stress state in metal layer of the laminate that is found to be higher than the stress applied over the laminate resulting in reduced yield strength of the laminate in comparison with that of the metal layer. The model is tested over 4A-3/2 Glare laminate comprising three thin aerospace 2014-T6 aluminum alloy layers alternately bonded adhesively with two prepregs, each prepreg built up of three uni-directional glass fiber layers laid in longitudinal and transverse directions. Laminates with prepregs of E-Glass and S-Glass fibers are investigated separately under uni-axial tension. Yield strengths of both the Glare variants are found to be less than that of aluminum alloy with use of S-Glass fiber resulting in higher laminate yield strength than with the use of E-Glass fiber. Results from finite element analysis and tensile tests conducted over the laminates substantiate the theoretical model.

  4. Directly deposited graphene nanowalls on carbon fiber for improving the interface strength in composites

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Yao [Department of Building Materials Engineering, College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Key Laboratory of Multi-Scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714 (China); Chu, Jin; Li, Chaolong, E-mail: cmf-210@126.com, E-mail: lichaolong@cigit.ac.cn; Piao, Mingxing; Zhang, Heng; Shi, Haofei [Key Laboratory of Multi-Scale Manufacturing Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714 (China); Chen, Mingfeng, E-mail: cmf-210@126.com, E-mail: lichaolong@cigit.ac.cn; Mao, Weijie [Department of Building Materials Engineering, College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Liu, Bao Sheng [Avic Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 (China)

    2016-05-23

    Graphene nanowalls (GNWs) were grown directly on carbon fibers using a chemical vapor deposition technique which is simple and catalyst-free. We found that there is very strong π-π stacking which is a benefit for the GNWs/carbon fiber interface. This single modified filament then was embedded into an epoxy matrix to be a single-fiber composite in which was formed a “tenon-mortise” structure. Such a “tenon-mortise” model provides a simple, stable, and powerful connection between carbon fiber and the epoxy matrix. In addition, it was demonstrated that the epoxy matrix can be well embedded into GNWs through a field emission scanning electron microscope. The results of the single-fiber composite tests indicated that the interfacial strength of the composites was immensely improved by 173% compared to those specimens without GNWs.

  5. High tensile strength fly ash based geopolymer composite using copper coated micro steel fiber

    DEFF Research Database (Denmark)

    Ranjbar, Navid; Mehrali, Mehdi; Mehrali, Mohammad

    2016-01-01

    -matrix interaction. In this present study, effects of micro steel fibers (MSF) incorporation on mechanical properties of fly ash based geopolymer was investigated at different volume ratio of matrix. Various properties of the composite were compared in terms of fresh state by flow measurement and hardened state......As a ceramic-like material, geopolymers show a high quasi-brittle behavior and relatively low fracture energy. To overcome this, the addition of fibers to a brittle matrix is a well-known method to improve the flexural strength. Moreover, the success of the reinforcements is dependent on the fiber...... by variation of shrinkage over time to assess performance of the composites subjected to flexural and compressive load. The fiber-matrix interface, fiber surface and toughening mechanisms were assessed using field emission scan electron microscopy (FESEM) and atomic force microscopy (AFM) through a period...

  6. UV irradiation improves the bond strength of resin cement to fiber posts.

    Science.gov (United States)

    Zhong, Bo; Zhang, Yong; Zhou, Jianfeng; Chen, Li; Li, Deli; Tan, Jianguo

    2011-01-01

    The purpose is to evaluate the effect of UV irradiation on the bond strength between epoxy-based glass fiber posts and resin cement. Twelve epoxy-based glass fiber posts were randomly divided into three groups. Group 1 (Cont.): No surface treatment. Group 2 (Low-UV): UV irradiation was conducted from a distance of 10 cm for 10 min. Group 3 (High-UV): UV irradiation was conducted from a distance of 1 cm for 3 min. A resin cement (CLEARFIL SA LUTING) was used for the post cementation to form resin slabs which contained fiber posts in the center. Microtensile bond strengths were tested and the mean bond strengths (MPa) were 18.81 for Cont. group, 23.65 for Low-UV group, 34.75 for High-UV group. UV irradiation had a significant effect on the bond strength (pUV irradiation demonstrates its capability to improve the bond strength between epoxy-based glass fiber posts and resin cement.

  7. Strength Characteristics of Groundnut Leaf/Stem Ash (GLSA Concrete

    Directory of Open Access Journals (Sweden)

    Oseni O. W.

    2016-09-01

    Full Text Available The compressive strength properties of concrete are substantial factors in the design and construction of concrete structures. Compressive strength directly affects the degree to which the concrete can be able to carry a load over time. These changes are complemented by deflections, cracks etc., in the structural elements of concrete. This research investigated the effect of groundnut leaf/stem ash (GLSA on the compressive strength of concrete at 0%, 5 %, 10 % and 15 % replacements of cement. The effect of the water-cement ratio on properties such as the compressive strength, slump, flow and workability properties of groundnut leaf/stem ash (GLSA mixes with OPC were evaluated to determine whether they are acceptable for use in concrete structural elements. A normal concrete mix with cement at 100 % (i.e., GLSA at 0% with concrete grade C25 that can attain an average strength of 25 N/mm2 at 28 days was used as a control at design water-cement ratios of 0.65 and grading of (0.5-32 mm from fine to coarse aggregates was tested for: (1 compressive strength, and the (2 slump and flow Test. The results and observations showed that the concrete mixes from GLSA at 5 – 15 % ratios exhibit: pozzolanic properties and GLSA could be used as a partial replacement for cement at these percentage mix ratios compared with the control concrete; an increase in the water-cement ratio showed a significant decrease in the compressive strength and an increase in workability. Therefore, it is important that all concrete mixes exude an acceptably designed water-cement ratio for compressive strength characteristics for use in structures, water-cement ratio is a significant factor.

  8. Strength Characteristics of Groundnut Leaf/Stem Ash (GLSA) Concrete

    Science.gov (United States)

    Oseni, O. W.; Audu, M. T.

    2016-09-01

    The compressive strength properties of concrete are substantial factors in the design and construction of concrete structures. Compressive strength directly affects the degree to which the concrete can be able to carry a load over time. These changes are complemented by deflections, cracks etc., in the structural elements of concrete. This research investigated the effect of groundnut leaf/stem ash (GLSA) on the compressive strength of concrete at 0%, 5 %, 10 % and 15 % replacements of cement. The effect of the water-cement ratio on properties such as the compressive strength, slump, flow and workability properties of groundnut leaf/stem ash (GLSA) mixes with OPC were evaluated to determine whether they are acceptable for use in concrete structural elements. A normal concrete mix with cement at 100 % (i.e., GLSA at 0%) with concrete grade C25 that can attain an average strength of 25 N/mm2 at 28 days was used as a control at design water-cement ratios of 0.65 and grading of (0.5-32) mm from fine to coarse aggregates was tested for: (1) compressive strength, and the (2) slump and flow Test. The results and observations showed that the concrete mixes from GLSA at 5 - 15 % ratios exhibit: pozzolanic properties and GLSA could be used as a partial replacement for cement at these percentage mix ratios compared with the control concrete; an increase in the water-cement ratio showed a significant decrease in the compressive strength and an increase in workability. Therefore, it is important that all concrete mixes exude an acceptably designed water-cement ratio for compressive strength characteristics for use in structures, water-cement ratio is a significant factor.

  9. Intrinsic strength of sodium borosilicate glass fibers by using a two-point bending technique

    International Nuclear Information System (INIS)

    Nishikubo, Y; Yoshida, S; Sugawara, T; Matsuoka, J

    2011-01-01

    Flaws existing on glass surface can be divided into two types, extrinsic and intrinsic. Although the extrinsic flaws are generated during processing and using, the intrinsic flaws are regarded as structural defects which result from thermal fluctuation. It is known that the extrinsic flaws determine glass strength, but effects of the intrinsic flaws on the glass strength are still unclear. Since it is considered that the averaged bond-strength and the intrinsic flaw would affect the intrinsic strength, the intrinsic strength of glass surely depends on the glass composition. In this study, the intrinsic failure strain of the glass fibers with the compositions of 20Na 2 O-40xB 2 O 3 -(80-40x)SiO 2 (mol%, x = 0, 0.5, 1.0, 1.5) were measured by using a two-point bending technique. The failure strength was estimated from the failure strain and Young's modulus of glass. It is elucidated that two-point bending strength of glass fiber decreases with increasing B 2 O 3 content in glass. The effects of the glass composition on the intrinsic strength are discussed in terms of elastic and inelastic deformation behaviors prior to fracture.

  10. Restrained Shrinkage Cracking of Fiber-Reinforced High-Strength Concrete

    Directory of Open Access Journals (Sweden)

    Ashkan Saradar

    2018-02-01

    Full Text Available Concrete shrinkage and volume reduction happens due to the loss of moisture, which eventually results in cracks and more concrete deformation. In this study, the effect of polypropylene (PP, steel, glass, basalt, and polyolefin fibers on compressive and flexural strength, drying shrinkage, and cracking potential, using the ring test at early ages of high-strength concrete mixtures, was investigated. The restrained shrinkage test was performed on concrete ring specimens according to the ASTM C1581 standard. The crack width and age of restrained shrinkage cracking were the main parameters studied in this research. The results indicated that the addition of fiber increases the compressive strength by 16%, 20%, and 3% at the age of 3, 7, and 28 days, respectively, and increases the flexural toughness index up to 7.7 times. Steel and glass fibers had a better performance in flexural strength, but relatively poor action in the velocity reduction and cracking time of the restrained shrinkage. Additionally, cracks in all concrete ring specimens except for the polypropylene-containing mixture, was developed to a full depth crack. The mixture with polypropylene fiber indicated a reduction in crack width up to 62% and an increasing age cracking up to 84%.

  11. Study on Fatigue Characteristics of High-Strength Steel Welds

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hong Suk; Yoo, Seung Won; Park, Jong Chan [Hyundai Motor Group, Seoul (Korea, Republic of)

    2015-03-15

    High-strength steel has replaced mild steel as the material of choice for truck decks or frames, owing to the growing demand for lightweight vehicles. Although studies on the weld fatigue characteristics of mild steel are available, studies on high-strength steels have been seldom conducted. In this study, firstly, we surveyed a chosen number of approaches and selected the Radaj method, which uses the notch factor approach, as the one suitable for evaluating the fatigue life of commercial vehicles. Secondly, we obtained the S-N curves of HARDOX and ATOS60 steel welds, and the F-N curves of the T-weld and overlapped-weld structures. Thirdly, we acquired a general S-N curve of welded structures made of high-strength steel from the F-N curve, using the notch factor approach. Fourthly, we extracted the weld fatigue characteristics of high-strength steel and incorporated the results in the database of a commercial fatigue program. Finally, we compared the results of the fatigue test and the CAE prediction of the example case, which demonstrated sufficiently good agreement.

  12. The effect of ultrafast fiber laser application on the bond strength of resin cement to titanium.

    Science.gov (United States)

    Ates, Sabit Melih; Korkmaz, Fatih Mehmet; Caglar, Ipek Satıroglu; Duymus, Zeynep Yeşil; Turgut, Sedanur; Bagis, Elif Arslan

    2017-07-01

    The purpose of this study was to investigate the effect of ultrafast fiber laser treatment on the bond strength between titanium and resin cement. A total of 60 pure titanium discs (15 mm × 2 mm) were divided into six test groups (n = 10) according to the surface treatment used: group (1) control, machining; group (2) grinding with a diamond bur; group (3) ultrafast fiber laser application; group (4) resorbable blast media (RBM) application; group (5) electro-erosion with copper; and group (6) sandblasting. After surface treatments, resin cements were applied to the treated titanium surfaces. Shear bond strength testing of the samples was performed with a universal testing machine after storing in distilled water at 37 °C for 24 h. One-way ANOVA and Tukey's HSD post hoc test were used to analyse the data (P < 0.05). The highest bond strength values were observed in the laser application group, while the lowest values were observed in the grinding group. Sandblasting and laser application resulted in significantly higher bond strengths than control treatment (P < 0.05). Ultrafast fiber laser treatment and sandblasting may improve the bond strength between resin cement and titanium.

  13. The interfacial strength of carbon nanofiber epoxy composite using single fiber pullout experiments.

    Science.gov (United States)

    Manoharan, M P; Sharma, A; Desai, A V; Haque, M A; Bakis, C E; Wang, K W

    2009-07-22

    Carbon nanotubes and nanofibers are extensively researched as reinforcing agents in nanocomposites for their multifunctionality, light weight and high strength. However, it is the interface between the nanofiber and the matrix that dictates the overall properties of the nanocomposite. The current trend is to measure elastic properties of the bulk nanocomposite and then compare them with theoretical models to extract the information on the interfacial strength. The ideal experiment is single fiber pullout from the matrix because it directly measures the interfacial strength. However, the technique is difficult to apply to nanocomposites because of the small size of the fibers and the requirement for high resolution force and displacement sensing. We present an experimental technique for measuring the interfacial strength of nanofiber-reinforced composites using the single fiber pullout technique and demonstrate the technique for a carbon nanofiber-reinforced epoxy composite. The experiment is performed in situ in a scanning electron microscope and the interfacial strength for the epoxy composite was measured to be 170 MPa.

  14. Relining effects on the push-out shear bond strength of glass fiber posts

    Directory of Open Access Journals (Sweden)

    Adriana Rosado Valente ANDRIOLI

    Full Text Available Abstract Introduction The correct use of glass fiber posts in endodontically treated teeth is essential for the clinical success of restorative treatment. Objective This study evaluated the push-out shear bond strength of relined (R or non-relined (NR glass fiber posts, cemented with self-adhesive resin cement [RelyXTM U100 (U100] and conventional resin cement [RelyXTM ARC (ARC]. Material and method Sixty human single-rooted teeth were endodontically treated and divided into ARC-NR; U100-NR; ARC-R; U100-R groups. The teeth were sectioned into cervical, middle and apical thirds, and subjected to the push-out test. Bond strength was analyzed by the Friedman test; cement and post types were compared by the Mann Whitney test. The pattern of failures was evaluated with digital camera through images at 200x magnification, and was classified as adhesive (at the cement/dentin or cement/post interface, cohesive (cement or post, and mixed failures. Result In ARC-NR, bond strength values were higher in the cervical third; in U100-NR and ARC-R they were similar between the thirds. In U100-R, in the cervical and middle thirds the bond strength values were similar, and there was lower value in the apical third. For non-relined glass fiber posts, the highest mean bond strength values were observed with self-adhesive resin cement. Whereas, relined posts cemented with conventional resin cement had stronger cement layer in comparison with non-relined fiber posts. Conclusion The post relining technique was efficient in ARC-R. ARC-NR and U100-R showed improved bond strength in the cervical region of canal walls. The main failures were adhesive at the cement-post interface.

  15. Introducing biomimetic shear and ion gradients to microfluidic spinning improves silk fiber strength.

    Science.gov (United States)

    Li, David; Jacobsen, Matthew M; Gyune Rim, Nae; Backman, Daniel; Kaplan, David L; Wong, Joyce Y

    2017-05-31

    Silkworm silk is an attractive biopolymer for biomedical applications due to its high mechanical strength and biocompatibility; as a result, there is increasing interest in scalable devices to spin silk and recombinant silk so as to improve and customize their properties for diverse biomedical purposes (Vepari and Kaplan 2007 Prog. Polym. Sci. 32 ). While artificial spinning of regenerated silk fibroins adds tunability to properties such as degradation rate and surface functionalization, the resulting fibers do not yet approach the mechanical strength of native silkworm silk. These drawbacks reduce the applicability and attractiveness of artificial silk (Kinahan et al 2011 Biomacromolecules 12 ). Here, we used computational fluid dynamic simulations to incorporate shear in tandem with biomimetic ion gradients by coupling a modular novel glass microfluidic device to our previous co-axial flow device. Fibers spun with this combined apparatus demonstrated a significant increase in mechanical strength compared to fibers spun with the basic apparatus alone, with a three-fold increase in Young's modulus and extensibility and a twelve-fold increase in toughness. These results thus demonstrate the critical importance of ionic milieu and shear stress in spinning strong fibers from solubilized silk fibroin.

  16. Apparent interfacial shear strength of short-flax-fiber/starch acetate composites

    DEFF Research Database (Denmark)

    Andersons, J.; Modniks, J.; Joffe, R.

    2016-01-01

    The paper deals with an indirect industry-friendly method for identification of the interfacial shear strength (IFSS) in a fully bio-based composite. The IFSS of flax fiber/starch acetate is evaluated by a modified Bowyer and Bader method based on an analysis of the stress-strain curve of a short......-fiber-reinforced composite in tension. A shear lag model is developed for the tensile stress-strain response of short-fiber-reinforced composites allowing for an elastic-perfectly plastic stress transfer. Composites with different fiber volume fractions and a variable content of plasticizer have been analyzed. The apparent...... IFSS of flax/starch acetate is within the range of 5.5-20.5 MPa, depending on composition of the material. The IFSS is found to be greater for composites with a higher fiber loading and to decrease with increasing content of plasticizer. The IFSS is equal or greater than the yield strength of the neat...

  17. Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical performance used as anodes of structural lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Mengjie [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Wang, Shubin, E-mail: shubinwang@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Yu, Yalin; Feng, Qihang; Yang, Jiping; Zhang, Boming [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2017-01-15

    Highlights: • Carboxyl functionalized CF is acquired by simple chemical oxidation method. • These CF have preserved the tensile strength, better electrochemical properties. • The presence of H{sub 3}PO{sub 4} prevented the turbostratic carbon from over-oxidization. • There CF can be used as anodes of multifunctional structural battery. • The preservation and improvement is result from the hindered over-oxidization. - Abstract: Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical properties were acquired through a simple chemical oxidation method, and the proposed underlying mechanism was verified. The surface of carboxyl functionalizing carbon fibers is necessary in acquiring functional groups on the surface of carbon fibers to further improve the thermal, electrical or mechanical properties of the fibers. Functionalization should preserve the tensile strength and electrochemical properties of carbon fibers, because the anodes of structural batteries need to have high strength and electrochemical properties. Functionalized with mixed H{sub 2}SO{sub 4}/HNO{sub 3} considerably reduced the tensile strength of carbon fibers. By contrast, the appearance of H{sub 3}PO{sub 4} preserved the tensile strength of functionalized carbon fibers, reduced the dispersion level of tensile strength values, and effectively increased the concentration of functional acid groups on the surface of carbon fibers. The presence of phosphoric acid hindered the over-oxidation of turbostratic carbon, and consequently preserved the tensile strength of carbon fibers. The increased proportion of turbostratic carbon on the surface of carbon fibers concurrently enhanced the electrochemical properties of carbon fibers.

  18. Effects of accelerated artificial daylight aging on bending strength and bonding of glass fibers in fiber-embedded maxillofacial silicone prostheses.

    Science.gov (United States)

    Hatamleh, Muhanad M; Watts, David C

    2010-07-01

    The purpose of this study was to test the effect of different periods of accelerated artificial daylight aging on bond strength of glass fiber bundles embedded into maxillofacial silicone elastomer and on bending strength of the glass fiber bundles. Forty specimens were fabricated by embedding resin-impregnated fiber bundles (1.5-mm diameter, 20-mm long) into maxillofacial silicone elastomer. Specimens were randomly allocated into four groups, and each group was subjected to different periods of accelerated daylight aging as follows (in hours); 0, 200, 400, and 600. The aging cycle included continuous exposure to quartz-filtered visible daylight (irradiance 760 W/m(2)) under an alternating weathering cycle (wet for 18 minutes, dry for 102 minutes). Pull-out tests were performed to evaluate bond strength between fiber bundles and silicone using a universal testing machine at 1 mm/min crosshead speed. Also a three-point bending test was performed to evaluate bending strength of the fiber bundles. One-way ANOVA and Bonferroni post hoc tests were carried out to detect statistical significance (p aging only. After 200 hours of exposure to artificial daylight and moisture conditions, bond strength between glass fibers and heat-cured silicones is optimal, and the bending strength of the glass fiber bundles is enhanced.

  19. Pullout bond strength of fiber posts luted to different depths and submitted to artificial aging.

    Science.gov (United States)

    Macedo, V C; Souza, N A Y; Faria e Silva, A L; Cotes, C; da Silva, C; Martinelli, M; Kimpara, E T

    2013-01-01

    The extension of fiber post cementation often does not seem to influence the fracture resistance of restorations. This study evaluated the effects of cementation depths on the retention of fiber posts submitted to artificial aging. One hundred and sixty bovine incisors were selected to assess post retention. Following endodontic treatment, the canals were flared with diamonds burs. Postholes were prepared in lengths of 5 or 10 mm, after which fiber posts were relined with composite resin and luted with RelyX ARC or RelyX Unicem. The samples were then submitted to thermal and/or mechanical cycling before testing their pullout bond strengths. Absence of cycling was used as a control. The results of each cement were submitted to two-way and post hoc Tukey tests (α=0.05). Independent of the aging protocol, a depth of 10 mm showed higher pullout bond strength than did 5 mm, except for RelyX Unicem without cycling. For RelyX ARC, thermomechanical cycling resulted in lower values than in the absence of cycling. Mechanical cycling alone promoted the highest bond strength when the posts were luted with RelyX Unicem. The effect of artificial aging on the pullout bond strength is dependent on the type of material and the depth.

  20. Characteristics of structural loess strength and preliminary framework for joint strength formula

    OpenAIRE

    Rong-jian Li; Jun-ding Liu; Rui Yan; Wen Zheng; Sheng-jun Shao

    2014-01-01

    The strength of structural loess consists of the shear strength and tensile strength. In this study, the stress path, the failure envelope of principal stress (Kf line), and the strength failure envelope of structurally intact loess and remolded loess were analyzed through three kinds of tests: the tensile strength test, the uniaxial compressive strength test, and the conventional triaxial shear strength test. Then, in order to describe the tensile strength and shear strength of structural lo...

  1. Effect of steel fibers on plastic shrinkage cracking of normal and high strength concretes

    Directory of Open Access Journals (Sweden)

    Özgür Eren

    2010-06-01

    Full Text Available Naturally concrete shrinks when it is subjected to a drying environment. If this shrinkage is restrained, tensile stresses develop and concrete may crack. Plastic shrinkage cracks are especially harmful on slabs. One of the methods to reduce the adverse effects of shrinkage cracking of concrete is by reinforcing concrete with short randomly distributed fibers. The main objective of this study was to investigate the effect of fiber volume and aspect ratio of hooked steel fibers on plastic shrinkage cracking behavior together with some other properties of concrete. In this research two different compressive strength levels namely 56 and 73 MPa were studied. Concretes were produced by adding steel fibers of 3 different volumes of 3 different aspect ratios. From this research study, it is observed that steel fibers can significantly reduce plastic shrinkage cracking behavior of concretes. On the other hand, it was observed that these steel fibers can adversely affect some other properties of concrete during fresh and hardened states.

  2. Influence of Fiber Volume Fraction on the Tensile Properties and Dynamic Characteristics of Coconut Fiber Reinforced Composite

    OpenAIRE

    Izzuddin Zaman; Al Emran Ismail; Muhamad Khairudin Awang

    2011-01-01

    The utilization of coconut fibers as reinforcement in polymer composites has been increased significantly due to their low cost and high specific mechanical properties. In this paper, the mechanical properties and dynamic characteristics of a proposed combined polymer composite which consist of a polyester matrix and coconut fibers are determined. The influence of fibers volume fraction (%) is also evaluated and composites with volumetric amounts of coconut fiber up to 15% are fabricated. In ...

  3. Comparative study of flexural strength and elasticity modulus in two types of direct fiber-reinforced systems.

    Science.gov (United States)

    Gaspar Junior, Alfredo de Aquino; Lopes, Manuela Wanderley Ferreira; Gaspar, Gabriela da Silveira; Braz, Rodivan

    2009-01-01

    The objective of this study was to compare the flexural strength and elasticity modulus of two types of staple reinforcement fibers, Interlig - Angelus/glass (Londrina, PR, Brazil) and Connect - KerrLab(R)/polyethylene (MFG Co., West Collins Orange, CA, USA), which are widely used in Dentistry for chairside use, after varying the number of layers employed and submitting or not to thermocycling. This study was performed on 72 specimens, divided into 8 groups: G1 - single layer of Interlig fibers without thermocycling; G2 - double layer of Interlig fibers without thermocycling; G3 - single layer of Interlig fibers with thermocycling; and G4 - double layer of Interlig fibers with thermocycling; G5 - single layer of Connect fibers without termocycling; G6 - double layer of Connect fibers without termocycling; G7 - single layer of Connect fibers with termocycling; G8 - double layer of Connect fibers with termocycling. For each group, values for flexural strength and elasticity modulus were obtained. The polyethylene fiber employed in a double layer presented the highest flexural strength (p elasticity modulus, when compared to the other groups (p < 0.05). Within the limits of this study, it was concluded that the polyethylene fiber in a double layer appears to be more resistant, regardless of whether it was submitted to thermocycling or not.

  4. Oxidation Kinetics and Strength Degradation of Carbon Fibers in a Cracked Ceramic Matrix Composite

    Science.gov (United States)

    Halbig, Michael C.

    2003-01-01

    Experimental results and oxidation modeling will be presented to discuss carbon fiber susceptibility to oxidation, the oxidation kinetics regimes and composite strength degradation and failure due to oxidation. Thermogravimetric Analysis (TGA) was used to study the oxidation rates of carbon fiber and of a pyro-carbon interphase. The analysis was used to separately obtain activation energies for the carbon constituents within a C/SiC composite. TGA was also conducted on C/SiC composite material to study carbon oxidation and crack closure as a function of temperature. In order to more closely match applications conditions C/SiC tensile coupons were also tested under stressed oxidation conditions. The stressed oxidation tests show that C/SiC is much more susceptible to oxidation when the material is under an applied load where the cracks are open and allow for oxygen ingress. The results help correlate carbon oxidation with composite strength reduction and failure.

  5. Striated muscle fiber size, composition and capillary density in diabetes in relation to neuropathy and muscle strength

    DEFF Research Database (Denmark)

    Andreassen, Christer Swan; Jensen, Jacob Malte; Jakobsen, Johannes

    2014-01-01

    study was to evaluate histologic properties and capillarization of diabetic skeletal muscle in relation to DPN and muscle strength. METHODS: Twenty type 1 and 20 type 2 diabetic (T1D and T2D, respectively) patients underwent biopsy of the gastrocnemic muscle, isokinetic dynamometry at the ankle...... between muscle fiber diameter, muscle fiber type distribution, or capillary density and degree of neuropathy or muscle strength for either patient group. Muscle fiber diameter and the proportion of Type II fibers were greater for T1D patients than both T2D patients and controls. The T2D patients had fewer...

  6. Fracture strengths of chair-side-generated veneers cemented with glass fibers.

    Science.gov (United States)

    Turkaslan, S; Bagis, B; Akan, E; Mutluay, M M; Vallittu, P K

    2015-01-01

    CAD/CAM (computer-aided design and computer-aided manufacturing) systems have refreshed the idea of chair-side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of CAD/CAM-generated ceramic veneers. Therefore, this study compared the fracture strengths of ceramic veneers produced at chair side and cemented with or without glass fibers with those of composite veneers. Thirty intact mandibular incisors were randomly divided into three groups ( n = 10) and treated with CAD/CAM-fabricated veneers cemented with dual-cure composite resin luting cement (CRLC; Group 1), CAD/CAM-fabricated veneers cemented with a glass fiber network (GFN) and dual-cure CRLC (Group 2), and a direct particulate filler composite veneer constructed utilizing fiber and a restorative composite resin (Group 3). The specimens were tested with a universal testing machine after thermal cycling treatment. The loads at the start of fracture were the lowest for traditionally fabricated composite veneers and higher for CAD/CAM-generated. Veneers cemented either without or with the GFN. The failure initiation loads (N) for the veneers were 798.92 for Group 1, 836.27 for Group 2, and 585.93 for Group 3. The predominant failure mode is adhesive failure between the laminates and teeth for Group 1, cohesive failure in the luting layer for Group 2, and cohesive laminate failure for Group 3, which showed chipping and small fractures. Ceramic material is a reliable alternative for veneer construction at chair side. Fibers at the cementation interface may improve the clinical longevity and provide higher fracture strength values.

  7. Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

    Science.gov (United States)

    Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

    2015-01-01

    Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

  8. Modal characteristics and fatigue strength of compressor blades

    International Nuclear Information System (INIS)

    Kim, Kyung Kook; Lee, Young Shin

    2014-01-01

    High-cycle fatigue (HCF) has been identified as one of the primary causes of gas turbine engine failure. The modal characteristics and endurance strength of a 5 MW gas turbine engine blade developed by Doosan Heavy Industries and Construction Co., Ltd. in HCF fracture were verified through analysis and tests to determine the reliability of the compressor blade. A compressor blade design procedure that considers HCF life was performed in the following order: airfoil and blade profile design, modal analysis, stress distribution test, stress endurance limit test, and fatigue life verification. This study analyzed the Campbell diagram and estimated resonance risk on the basis of the natural frequency analysis and modal test of the compressor blade to guarantee safe and operational reliability. In addition, the maximum stress point of the compressor blade was determined through stress distribution analysis and test. The bonding point of the strain gage was determined by using fatigue test. Stress endurance limit test was performed based on the results of these tests. This research compared and verified the modal characteristics and endurance strengths of the compressor blades to prevent HCF fracture, which is among the major causes of gas turbine engine damage. A fatigue life design procedure of compressor blades was established. The 5 MW class gas turbine compressor blade is well designed in terms of resonance stability and fatigue endurance limit.

  9. Modal characteristics and fatigue strength of compressor blades

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Kook [Doosan Heavy Industries and Construction, Changwon (Korea, Republic of); Lee, Young Shin [Chungnam National University, Daejeon (Korea, Republic of)

    2014-04-15

    High-cycle fatigue (HCF) has been identified as one of the primary causes of gas turbine engine failure. The modal characteristics and endurance strength of a 5 MW gas turbine engine blade developed by Doosan Heavy Industries and Construction Co., Ltd. in HCF fracture were verified through analysis and tests to determine the reliability of the compressor blade. A compressor blade design procedure that considers HCF life was performed in the following order: airfoil and blade profile design, modal analysis, stress distribution test, stress endurance limit test, and fatigue life verification. This study analyzed the Campbell diagram and estimated resonance risk on the basis of the natural frequency analysis and modal test of the compressor blade to guarantee safe and operational reliability. In addition, the maximum stress point of the compressor blade was determined through stress distribution analysis and test. The bonding point of the strain gage was determined by using fatigue test. Stress endurance limit test was performed based on the results of these tests. This research compared and verified the modal characteristics and endurance strengths of the compressor blades to prevent HCF fracture, which is among the major causes of gas turbine engine damage. A fatigue life design procedure of compressor blades was established. The 5 MW class gas turbine compressor blade is well designed in terms of resonance stability and fatigue endurance limit.

  10. Influence of sand to coarse aggregate ratio on the interfacial bond strength of steel fibers in concrete for nuclear power plant

    International Nuclear Information System (INIS)

    Kim, Jung Jin; Kim, Dong Joo; Kang, Su Tae; Lee, Jang Hwa

    2012-01-01

    Highlights: ► The final goal is to develop a fiber reinforced concrete for containment buildings. ► We investigated the effect of S/a on the bond strength of steel fibers. ► Deformed steel fibers produced much higher interfacial bond strength. ► As S/a increased, twisted fiber showed a significant enhancement in bond strength. ► Smooth and hooked fiber showed no clear difference as S/a increased. - Abstract: The interfacial bond strength of three high strength steel fibers (smooth, hooked, and twisted fiber) in concrete of nuclear power plants was investigated to develop fiber reinforced concrete for containment building. Sand to aggregate ratio (S/a) was adjusted to compensate reduction in the workability due to adding fibers; the influence of S/a ratio on the interfacial bond strength was investigated. As the S/a ratio increased from 0.444 to 0.615, the bond strength of twisted steel fiber was significantly improved while smooth and hooked steel fiber showed no clear difference. The different sensitivity according to the S/a ratio results from the different pullout mechanism: twisted steel fiber generates more mechanical interaction during fiber pullout at the interface between fiber and matrix than smooth and hooked fibers. The microscopic observation by scanning electron microscope back-scattered electrons images discovered lower porosity at the interfacial transition zone between fiber and concrete with higher S/a ratio.

  11. High-Strength / High Alkaline Resistant Fe-Phosphate Glass Fibers as Concrete Reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Mariano Velez

    2008-03-31

    Calcium-iron-phosphate glasses were developed whose chemical durabilities in alkaline solutions (pH 13) were comparable or superior to those of commercial alkaline-resistant (AR) silica-based glasses. However, the tensile strength of Ca-Fe-phosphate fibers, after being exposed to alkaline environments, including wet Portland cement pastes, is lower than that of current AR silicate fibers. Another series of Ca-Fe-phosphate glasses were developed with excellent chemical durability in strong acidic solutions (H2SO4, HF), indicating potential applications where silica-based fibers degrade very quickly, including E-glass. The new Ca-Fe-phosphate glasses can be melted and processed 300 to 500°C lower than silica-based glasses. This offers the possibility of manufacturing glass fibers with lower energy costs by 40-60% and the potential to reduce manufacturing waste and lower gas emissions. It was found that Ca-Fe-phosphate melts can be continuously pulled into fibers depending on the slope of the viscosity-temperature curve and with viscosity ~100 poise, using multi-hole Pt/Rh bushings.

  12. Effect of Electron Beam Irradiation of the Characteristics of Jute Fibers and the Interfacial Properties of Jute/PLA Green Composites

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Sang Gyu; Cho, Dong Hwan [Kumoh National Institute of Technology, Gumi (Korea, Republic of); Lee, Byung Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-07-01

    Cellulose-based natural fibers such as jute, knife and hemp have promising potential as a replacement for glass fibers in a polymer composite system because of their many advantages like natural abundance, low cost, light weight, biodegradability, carbon dioxide reduction in nature and acceptable mechanical properties. However, natural fibers need an appropriate surface treatment modifying their surface characteristics in order to effectively improve the interfacial properties as well as the mechanical and thermal properties. Electron beam irradiation technique is particularly interesting as it may offer the possibility to modify the surfaces and to enhance the properties of polymer materials such as fibers, films and composites. In addition, electron beam processing has a merit because it is a dry, solvent free and eco-friendly method with a fast throughput rate. In the present study, Jute fibers were irradiated at different dosages of electron beam from 10 to 100 kGy. The result was compared with raw jute fibers un-irradiated, showing the effect on the interfacial shear strength between jute fibers and PLA in terms of single fiber tensile property, fiber surface topology, and chemical composition occurring in jute fibers upon irradiation. It has been found that the surface topology and chemical characteristics of jute fibers significantly depended on the electron beam dosage irradiated, directly influencing the interfacial shear strength and interlaminar shear strength of jute-PLA green composites. It was concluded that electron beam irradiation played a contributing role not only in physically modifying the jute fiber surfaces but also in improving the interfacial properties between jute fibers and poly in the green composite, exhibiting the most effectiveness at a low electron beam energy of 10 kGy.

  13. Behavior of steel fiber high strength concrete under impact of projectiles

    Directory of Open Access Journals (Sweden)

    Cánovas, M. F.

    2012-09-01

    Full Text Available This paper presents the results of the investigation carried out by the authors about the behavior of 80 MPa characteristic compression strength concrete reinforced with different amount of high carbon content steel fiber, submit to impact of different caliber projectiles, determining the thickness of this type of concrete walls needs to prevent no perforation, as well as the maximum penetration to reach into them, so that in the event of no perforation and only penetration, "scabbing" phenomena does not take place on the rear surface of the wall. Prior to ballistic testing was necessary to design the high-strength concrete with specific mechanical properties, especially those related to ductility, since these special concrete must absorb the high energy of projectiles and also the shock waves that accompany them.Este trabajo presenta los resultados de la investigación llevada a cabo por los autores sobre el comportamiento de hormigón de 80 MPa de resistencia característica a compresión reforzado con diferentes cuantías de fibras de acero de alto contenido en carbono sometido al impacto de proyectiles de distintos calibres, determinando el espesor de muros de este tipo de hormigón que sería preciso disponer para impedir su perforación por dichos proyectiles, así como los valores máximos de penetración, para que en el caso de no producirse perforación y sólo penetración, no se genera cráter, “scabbing”, en el trasdós de los mismos. Previamente a los ensayos balísticos fue preciso diseñar los hormigones para que, presentaran determinadas características mecánicas, especialmente las relacionadas con la ductilidad, dado que estos hormigones especiales deben absorber la elevada energía que le transmiten los proyectiles y las ondas de choque que los acompañan.

  14. Effects of neutron irradiation on the strength of continuous fiber reinforced SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Henager, C.H. Jr.; Jones, R.H. [Pacific National Lab., Richland, WA (United States)

    1997-04-01

    Flexural strength data as a function of irradiation temperature and dose for a SiC{sub f}/SiC composite made with Nicalon-CG fiber suggest three major degradation mechanisms. Based on an analysis of tensile strength and microstructural data for irradiated Nicalon-CG and Hi-Nicalon fibers, it is anticipated that these degradation mechanisms will be alleviated in Hi-Nicalon reinforced composites.

  15. Characteristics of shock propagation in high-strength cement mortar

    Science.gov (United States)

    Wang, Zhanjiang; Li, Xiaolan; Zhang, Ruoqi

    2001-06-01

    Planar impact experiments have been performed on high-strength cement mortar to determine characteristics of shock propagation.The experiments were conducted on a light-gas gun,and permanent-magnet particle velocity gages were used to obtain the sand of 0.5 3.5mm size.A bulk density of 2.31g/cm^3,and a compressive and tensile strength of 82MPa and 7.8MPa,respectively,were determined.Three kinds of experimental techniques were used,including the reverse ballistic configuration.These techniques effectively averaged the measured dynamic compression state over a sensibly large volume of the test sample.The impact velocities were controlled over a range of approximately 80m/s to 0.83km/s.Hugoniot equation of state data were obtained for the material over a pressure range of approximately 0.2 2.0GPa,and its nonlinear constitutive relation were analyzed.The experiment results show that,in higher pressure range provided in the experiment,the shock wave in the material splits into two components of an elastic and a plastic,with the Hugoniot elastic limit 0.4 0.5GPa and the precursor velocity about 4.7km/s,and the material presents a very strong nonlinear dynamic response,and its shock amplitude will greatly decrease in propagation.

  16. Influence of surface defects on the tensile strength of carbon fibers

    Science.gov (United States)

    Vautard, F.; Dentzer, J.; Nardin, M.; Schultz, J.; Defoort, B.

    2014-12-01

    The mechanical properties of carbon fibers, especially their tensile properties, are affected by internal and surface defects. In order to asses in what extent the generation of surface defects can result in a loss of the mechanical properties, non-surface treated carbon fibers were oxidized with three different surface treatment processes: electro-chemical oxidation, oxidation in nitric acid, and oxidation in oxygen plasma. Different surface topographies and surface chemistries were obtained, as well as different types and densities of surface defects. The density of surface defects was measured with both a physical approach (Raman spectroscopy) and a chemical approach (Active Surface Area). The tensile properties were evaluated by determining the Weibull modulus and the scale parameter of each reference, after measuring the tensile strength for four different gauge lengths. A relationship between the tensile properties and the nature and density of surface defects was noticed, as large defects largely control the value of the tensile strength. When optimized, some oxidation surface treatment processes can generate surface functional groups as well as an increase of the mechanical properties of the fibers, because of the removal of the contamination layer of pyrolytic carbon generated during the carbonization of the polyacrylonitrile precursor. Oxidation in oxygen plasma revealed to be a promising technology for alternative surface treatment processes, as high levels of functionalization were achieved and a slight improvement of the mechanical properties was obtained too.

  17. ANTHROPOMETRIC, GAIT AND STRENGTH CHARACTERISTICS OF KENYAN DISTANCE RUNNERS

    Directory of Open Access Journals (Sweden)

    Pui W. Kong

    2008-12-01

    Full Text Available This study intended to take a biomechanical approach to understand the success of Kenyan distance runners. Anthropometric, gait and lower extremity strength characteristics of six elite Kenyan distance runners were analyzed. Stride frequency, relative stride length and ground contact time were measured at five running speeds (3.5 - 5.4 m/s using a motion capture system. Isometric knee extension and flexion torques were measured at six angles and hamstrings and quadriceps (H:Q ratios at three angular velocities were determined using an isokinetic dynamometer. These runners were characterized by a low body mass index (20.1 ± 1.8 kg·m- 2, low percentage body fat (5.1 ± 1.6% and small calf circumference (34.5 ± 2.3 cm. At all running speeds, the ground contact time was shorter (p < 0.05 during right (170 - 212 ms compared to left (177 - 220 ms foot contacts. No bilateral difference was observed in other gait or strength variables. Their maximal isometric strength was lower than other runners (knee extension: 1.4 - 2.6 Nm·kg-1, knee flexion: 1.0 - 1.4 Nm·kg-1 but their H:Q ratios were higher than athletes in other sports (1.03 ± 0.51 at 60o/s, 1.44 ± 0.46 at 120o/s, 1.59 ± 0.66 at 180o/s. The slim limbs of Kenyan distance runners may positively contribute to performance by having a low moment of inertia and thus requiring less muscular effort in leg swing. The short ground contact time observed may be related to good running economy since there is less time for the braking force to decelerate forward motion of the body. These runners displayed minor gait asymmetry, though the difference may be too small to be practically significant. Further investigations are needed to confirm whether the bilateral symmetry in strength and high H:Q ratios are related to genetics, training or the lack of injuries in these runners

  18. Investigation Characteristics Of Pulp Fibers AS Green Potential Polymer Reinforcing Agents

    OpenAIRE

    Masruchin, Nanang; Subyakto

    2012-01-01

    Three kinds of pulp fiber (i.e. kenaf, pineapple and coconut fiber)were characterized as reinforcing agents in compositematerials to be applied at automotive interior industry.Abetter understanding on characteristics of fiber will lead to enhance interface adhesion between fiber and matrices. Furthermore, it will improve the properties of polymer significantly. Chemical, surface compositions as well as morphology of pulp fiber were investigated using TAPPI standard test method, Fourier Transf...

  19. Hydrogen bonds, interfacial stiffness moduli, and the interlaminar shear strength of carbon fiber-epoxy matrix composites

    Directory of Open Access Journals (Sweden)

    John H. Cantrell

    2015-03-01

    Full Text Available The chemical treatment of carbon fibers used in carbon fiber-epoxy matrix composites greatly affects the fraction of hydrogen bonds (H-bonds formed at the fiber-matrix interface. The H-bonds are major contributors to the fiber-matrix interfacial shear strength and play a direct role in the interlaminar shear strength (ILSS of the composite. The H-bond contributions τ to the ILSS and magnitudes KN of the fiber-matrix interfacial stiffness moduli of seven carbon fiber-epoxy matrix composites, subjected to different fiber surface treatments, are calculated from the Morse potential for the interactions of hydroxyl and carboxyl acid groups formed on the carbon fiber surfaces with epoxy receptors. The τ calculations range from 7.7 MPa to 18.4 MPa in magnitude, depending on fiber treatment. The KN calculations fall in the range (2.01 – 4.67 ×1017 N m−3. The average ratio KN/|τ| is calculated to be (2.59 ± 0.043 × 1010 m−1 for the seven composites, suggesting a nearly linear connection between ILSS and H-bonding at the fiber-matrix interfaces. The linear connection indicates that τ may be assessable nondestructively from measurements of KN via a technique such as angle beam ultrasonic spectroscopy.

  20. Effect of Fiber Volume Fraction and Water Absorption toward Bending Strength of Coconut Filters/ Polyester Composite

    Directory of Open Access Journals (Sweden)

    I Putu Lokantara

    2012-11-01

    Full Text Available The variation of fibre volume and the duration of water soaking take influence on the mechanical properties of composite. This research aim is to know the influence of fraction volume fibre and soaking duration on the mineral watertoward the tensile strength and flexural of polyester-coconut-tapis composite. This research used coconut-tapis fibre which is cut 1 cm in length with 0%, 5%, 7,5%, and 10% fiber volume fraction, unsaturated-polyester (UPRs matrix resin type Yucalac 157 BQTN-EX, and MEKPO hardener. The flexure specimen are made by press hand lay-up method and cut according ASTM D790-03 for the flexure test. The result of flexure test shows that the duration of soaking and the fiber volume fraction give a significant effect on the flexural strength of composite. The highest strength are reached by composite with 10% fibre volume on 48 hour soaking time equal to 41.994 MPa. The flexure modulus happenend shows increasing until 24 hour soaking time. The highest modulus are reached by composite with 10% fibre volume equal to 7.114 GPa while the lowest are reached by composite with 0% fibre volume equal to 3,023 GPa.

  1. Characteristics and experiences of interns in strength and conditioning.

    Science.gov (United States)

    Read, Paul; Hughes, Jonathan D; Blagrove, Richard; Jeffreys, Ian; Edwards, Mike; Turner, Anthony N

    2017-02-01

    Student coaches undertake internships to develop practical skills and gain experience to improve employability prospects. The characteristics of the coaches who undertake these internships, their experiences and the nature of the work being performed are currently unknown. The purpose of this study was to report the characteristics of strength and conditioning (S&C) coaches who have undertaken internships and their experiences during their respective placements. A total of 113 men and 6 women completed an online survey. Placements generally lasted 6-12 months (66%), were unpaid (93%) and took place at professional teams (63%). All respondents had a standard of experience prior to commencement (82%); a higher-education degree (bachelor's degree 56%; master's degree 18%) and others were qualified S&C coaches (16%). Activities consisted largely of coaching (47%), data collection (22%) and equipment set-up (25%) but lacked provision of appropriate training. Mentors were allocated to interns; however, often developmental objectives were not discussed, meetings were rarely documented, and in some cases, no meetings took place. This study suggests that internships offer worthwhile experiences and assistance in skill development to progress in S&C. However, clearer guidelines are required to define the responsibilities of employers and interns, to maximise these experiential learning opportunities and avoid the exploitation of willing students.

  2. Interlaminar and ductile characteristics of carbon fibers-reinforced plastics produced by nanoscaled electroless nickel plating on carbon fiber surfaces.

    Science.gov (United States)

    Park, Soo-Jin; Jang, Yu-Sin; Rhee, Kyong-Yop

    2002-01-15

    In this work, a new method based on nanoscaled Ni-P alloy coating on carbon fiber surfaces is proposed for the improvement of interfacial properties between fibers and epoxy matrix in a composite system. Fiber surfaces and the mechanical interfacial properties of composites were characterized by atomic absorption spectrophotometer (AAS), scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS), interlaminar shear strength (ILSS), and impact strength. Experimental results showed that the O(1s)/C(1s) ratio or Ni and P amounts had been increased as the electroless nickel plating proceeded; the ILSS had also been slightly improved. The impact properties were significantly improved in the presence of Ni-P alloy on carbon fiber surfaces, increasing the ductility of the composites. This was probably due to the effect of substituted Ni-P alloy, leading to an increase of the resistance to the deformation and the crack initiation of the epoxy system.

  3. Plasma enhanced modification of TMP fiber and its effect on tensile strength of wood fiber/PP composite

    Science.gov (United States)

    Sangyeob Lee; Todd F. Shupe; Chung Y. Hse

    2009-01-01

    Plasma-assisted surface treatment on thermomechanical pulp (TMP) fiber and polypropylene (PP) film was investigated to obtain interfacial adhesion at the wood fiber and PP interface. A metal plate between electrodes prevented thermal damage to the TMP fiber handsheets and PP film. Oxygen-plasma treatment provided better surface activation on the TMP fiber and...

  4. Characterization of polymer concrete with natural fibers

    Science.gov (United States)

    Barbuta, M.; Serbanoiu, A. A.; Teodorescu, R.; Rosca, B.; Mitroi, R.; Bejan, G.

    2017-09-01

    In the study are presented the experimental results obtained for polymer concrete prepared with epoxy resin, aggregates, fly ash as filler and two types of fibers: wool and hemp. The influence of type and dosage of fibers were studied. The density and mechanical characteristics were determined: compressive strength, flexural strength and split tensile strength. For both types of fibers, with increasing the fiber dosage the density decreases. The studied dosages had not an important influence on mechanical strengths. The fibers improved especially the tensile strength and the compressive strength presented generally smaller values than the control mix.

  5. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    International Nuclear Information System (INIS)

    Wang, Yuwei; Meng, Linghui; Fan, Liquan; Wu, Guangshun; Ma, Lichun; Zhao, Min; Huang, Yudong

    2016-01-01

    Graphical abstract: - Highlights: • Carbon fibers are functionalized with benzoic acid groups via aryl diazonium reaction. • Interfacial shear strength of the carbon fibers increases by 66%. • Tensile strength of the carbon fibers is preserved after grafting reaction. • The treatment in molten urea can improve modification efficiency greatly. • Using molten urea as the reaction medium can avoid pollution from organic solvents. - Abstract: Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17–10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  6. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuwei [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Meng, Linghui [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Fan, Liquan [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Wu, Guangshun; Ma, Lichun; Zhao, Min [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Huang, Yudong, E-mail: ydhuang.hit1@yahoo.com.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2016-01-30

    Graphical abstract: - Highlights: • Carbon fibers are functionalized with benzoic acid groups via aryl diazonium reaction. • Interfacial shear strength of the carbon fibers increases by 66%. • Tensile strength of the carbon fibers is preserved after grafting reaction. • The treatment in molten urea can improve modification efficiency greatly. • Using molten urea as the reaction medium can avoid pollution from organic solvents. - Abstract: Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17–10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  7. Time-Dependent Stress Rupture Strength Degradation of Hi-Nicalon Fiber-Reinforced Silicon Carbide Composites at Intermediate Temperatures

    Science.gov (United States)

    Sullivan, Roy M.

    2016-01-01

    The stress rupture strength of silicon carbide fiber-reinforced silicon carbide composites with a boron nitride fiber coating decreases with time within the intermediate temperature range of 700 to 950 degree Celsius. Various theories have been proposed to explain the cause of the time-dependent stress rupture strength. The objective of this paper is to investigate the relative significance of the various theories for the time-dependent strength of silicon carbide fiber-reinforced silicon carbide composites. This is achieved through the development of a numerically based progressive failure analysis routine and through the application of the routine to simulate the composite stress rupture tests. The progressive failure routine is a time-marching routine with an iterative loop between a probability of fiber survival equation and a force equilibrium equation within each time step. Failure of the composite is assumed to initiate near a matrix crack and the progression of fiber failures occurs by global load sharing. The probability of survival equation is derived from consideration of the strength of ceramic fibers with randomly occurring and slow growing flaws as well as the mechanical interaction between the fibers and matrix near a matrix crack. The force equilibrium equation follows from the global load sharing presumption. The results of progressive failure analyses of the composite tests suggest that the relationship between time and stress-rupture strength is attributed almost entirely to the slow flaw growth within the fibers. Although other mechanisms may be present, they appear to have only a minor influence on the observed time-dependent behavior.

  8. Transcriptomic analysis of fiber strength in upland cotton chromosome introgression lines carrying different Gossypium barbadense chromosomal segments.

    Directory of Open Access Journals (Sweden)

    Lei Fang

    Full Text Available Fiber strength is the key trait that determines fiber quality in cotton, and it is closely related to secondary cell wall synthesis. To understand the mechanism underlying fiber strength, we compared fiber transcriptomes from different G. barbadense chromosome introgression lines (CSILs that had higher fiber strengths than their recipient, G. hirsutum acc. TM-1. A total of 18,288 differentially expressed genes (DEGs were detected between CSIL-35431 and CSIL-31010, two CSILs with stronger fiber and TM-1 during secondary cell wall synthesis. Functional classification and enrichment analysis revealed that these DEGs were enriched for secondary cell wall biogenesis, glucuronoxylan biosynthesis, cellulose biosynthesis, sugar-mediated signaling pathways, and fatty acid biosynthesis. Pathway analysis showed that these DEGs participated in starch and sucrose metabolism (328 genes, glycolysis/gluconeogenesis (122 genes, phenylpropanoid biosynthesis (101 genes, and oxidative phosphorylation (87 genes, etc. Moreover, the expression of MYB- and NAC-type transcription factor genes were also dramatically different between the CSILs and TM-1. Being different to those of CSIL-31134, CSIL-35431 and CSIL-31010, there were many genes for fatty acid degradation and biosynthesis, and also for carbohydrate metabolism that were down-regulated in CSIL-35368. Metabolic pathway analysis in the CSILs showed that different pathways were changed, and some changes at the same developmental stage in some pathways. Our results extended our understanding that carbonhydrate metabolic pathway and secondary cell wall biosynthesis can affect the fiber strength and suggested more genes and/or pathways be related to complex fiber strength formation process.

  9. Operational factors influence on service life characteristics of structural carbon fiber-reinforced plastic

    OpenAIRE

    Борозенець, Григорій; Павлов, Віктор; Семак, Інна

    2013-01-01

    The nature of strength changing of aircraft structural carbon fiber-reinforced plastic under influence of water saturation after static preloading and mode changing of structural elements forming process pressure is considered.

  10. Effect of fiber coating on interfacial shear strength of SiC/SiC by nano-indentation technique

    International Nuclear Information System (INIS)

    Hinoki, T.; Zhang, W.; Kohyama, A.; Noda, T.

    1998-01-01

    In order to quantitatively evaluate mechanical properties of fibers, matrices and their interfaces in fiber reinforced SiC/SiC composites, fiber push-out tests have been carried out. From the indentation load vs. displacement relations, the fiber push-out process has been discussed in comparison with the C/C composites and the loads for fiber push-in and those for fiber push-out were estimated. The trends of load-displacement curve of fiber push-out process depended on specimen thickness. The curve in the case of thick specimen had a micro step indicating fiber push-in and a larger step corresponding to fiber push-out. However just a larger step indicating fiber push-out was seen without fiber push-in process in the case of thin specimen. Interfacial shear stress was discussed and defined in both cases. The effects of fiber coatings on interfacial shear stress obtained from thin specimens were analyzed. The relationship between bending stress and interfacial shear stress of SiC (pcs) /SiC (CVI) is preliminarily postulated together with microstructural characteristics of the composites. (orig.)

  11. Influence of different adhesive systems on the pull-out bond strength of glass fiber posts.

    Science.gov (United States)

    da Silva, Luciana Mendonça; Andrade, Andréa Mello de; Machuca, Melissa Fernanda Garcia; da Silva, Paulo Maurício Batista; da Silva, Ricardo Virgolino C; Veronezi, Maria Cecília

    2008-01-01

    This in vitro study evaluated the tensile bond strength of glass fiber posts (Reforpost - Angelus-Brazil) cemented to root dentin with a resin cement (RelyX ARC - 3M/ESPE) associated with two different adhesive systems (Adper Single Bond - 3M/ESPE and Adper Scotchbond Multi Purpose (MP) Plus - 3M/ESPE), using the pull-out test. Twenty single-rooted human teeth with standardized root canals were randomly assigned to 2 groups (n=10): G1- etching with 37% phosphoric acid gel (3M/ESPE) + Adper Single Bond + #1 post (Reforpost - Angelus) + four #1 accessory posts (Reforpin - Angelus) + resin cement; G2- etching with 37% phosphoric acid gel + Adper Scotchbond MP Plus + #1 post + four #1 accessory posts + resin cement. The specimens were stored in distilled water at 37 degrees C for 7 days and submitted to the pull-out test in a universal testing machine (EMIC) at a crosshead speed of 0.5 mm/min. The mean values of bond strength (kgf) and standard deviation were: G1- 29.163 +/- 7.123; G2- 37.752 +/-13.054. Statistical analysis (Student's t-test; a=0.05 showed no statistically significant difference (pAdhesive bonding failures between resin cement and root canal dentin surface were observed in both groups, with non-polymerized resin cement in the apical portion of the post space when Single Bond was used (G1). The type of adhesive system employed on the fiber post cementation did not influence the pull-out bond strength.

  12. Influence of different adhesive systems on the pull-out bond strength of glass fiber posts

    Directory of Open Access Journals (Sweden)

    Luciana Mendonça da Silva

    2008-06-01

    Full Text Available This in vitro study evaluated the tensile bond strength of glass fiber posts (Reforpost - Angelus-Brazil cemented to root dentin with a resin cement (RelyX ARC - 3M/ESPE associated with two different adhesive systems (Adper Single Bond - 3M/ESPE and Adper Scotchbond Multi Purpose (MP Plus - 3M/ESPE, using the pull-out test. Twenty single-rooted human teeth with standardized root canals were randomly assigned to 2 groups (n=10: G1- etching with 37% phosphoric acid gel (3M/ESPE + Adper Single Bond + #1 post (Reforpost - Angelus + four #1 accessory posts (Reforpin - Angelus + resin cement; G2- etching with 37% phosphoric acid gel + Adper Scotchbond MP Plus + #1 post + four #1 accessory posts + resin cement. The specimens were stored in distilled water at 37°C for 7 days and submitted to the pull-out test in a universal testing machine (EMIC at a crosshead speed of 0.5 mm/min. The mean values of bond strength (kgf and standard deviation were: G1- 29.163 ± 7.123; G2- 37.752 ±13.054. Statistical analysis (Student's t-test; a=0.05 showed no statistically significant difference (p<0.05 between the groups. Adhesive bonding failures between resin cement and root canal dentin surface were observed in both groups, with non-polymerized resin cement in the apical portion of the post space when Single Bond was used (G1. The type of adhesive system employed on the fiber post cementation did not influence the pull-out bond strength.

  13. Push-out bond strengths of different dental cements used to cement glass fiber posts.

    Science.gov (United States)

    Pereira, Jefferson Ricardo; Lins do Valle, Accácio; Ghizoni, Janaina Salomon; Lorenzoni, Fábio César; Ramos, Marcelo Barbosa; Barbosa, Marcelo Ramos; Dos Reis Só, Marcus Vinícius

    2013-08-01

    Since the introduction of glass fiber posts, irreversible vertical root fractures have become a rare occurrence; however, adhesive failure has become the primary failure mode. The purpose of this study was to evaluate the push-out bond strength of glass fiber posts cemented with different luting agents on 3 segments of the root. Eighty human maxillary canines with similar root lengths were randomly divided into 8 groups (n=10) according to the cement assessed (Rely X luting, Luting and Lining, Ketac Cem, Rely X ARC, Biscem, Duo-link, Rely X U100, and Variolink II). After standardized post space preparation, the root dentin was pretreated for dual-polymerizing resin cements and untreated for the other cements. The mixed luting cement paste was inserted into post spaces with a spiral file and applied to the post surface that was seated into the canal. After 7 days, the teeth were sectioned perpendicular to their long axis into 1-mm-thick sections. The push-out test was performed at a speed of 0.5 mm/min until extrusion of the post occurred. The results were evaluated by 2-way ANOVA and the all pairwise multiple comparison procedures (Tukey test) (α=.05). ANOVA showed that the type of interaction between cement and root location significantly influenced the push-out strength (Pcements and glass ionomer cements showed significantly higher values compared to dual-polymerizing resin cements. In all root segments, dual-polymerizing resin cements provided significantly lower bond strength. Significant differences among root segments were found only for Duo-link cement. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  14. Muscle Fiber Characteristics, Satellite Cells and Soccer Performance in Young Athletes

    Directory of Open Access Journals (Sweden)

    Thomas I. Metaxas, Athanasios Mandroukas, Efstratios Vamvakoudis, Kostas Kotoglou, Björn Ekblom, Konstantinos Mandroukas

    2014-09-01

    Full Text Available This study is aimed to examine the muscle fiber type, composition and satellite cells in young male soccer players and to correlate them to cardiorespiratory indices and muscle strength. The participants formed three Groups: Group A (n = 13, 11.2 ± 0.4yrs, Group B (n=10, 13.1 ± 0.5yrs and Group C (n = 9, 15.2 ± 0.6yrs. Muscle biopsies were obtained from the vastus lateralis. Peak torque values of the quadriceps and hamstrings were recorded and VO2max was measured on the treadmill. Group C had lower type I percentage distribution compared to A by 21.3% (p < 0.01, while the type IIA relative percentage was higher by 18.1% and 18.4% than in Groups A and B (p < 0.05. Groups B and C had higher cross-sectional area (CSA values in all fiber types than in Group A (0.05 < p < 0.001. The number of satellite cells did not differ between the groups. Groups B and C had higher peak torque at all angular velocities and absolute VO2max in terms of ml·min-1 than Group A (0.05 < p < 0.001. It is concluded that the increased percentage of type IIA muscle fibers noticed in Group C in comparison to the Groups A and B should be mainly attributed to the different workload exercise and training programs. The alteration of myosin heavy chain (MHC isoforms composition even in children is an important mechanism for skeletal muscle characteristics. Finally, CSA, isokinetic muscle strength and VO2max values seems to be expressed according to age.

  15. Experimental Strength of Single-Lap Hybrid Joints on Woven Fabric Kenaf Fiber Composites Under Quasi Static Condition

    Directory of Open Access Journals (Sweden)

    Yee Lee Sim

    2016-01-01

    Full Text Available For the past decades, usage of natural fiber reinforced composites in low bearing load applications are increasing tremendously due to drawbacks concerning the use of synthetic fibers. Kenaf fibers have a good potential to be used as composite reinforcements as they possesses excellent fiber strength compared to own self-weight. Current work concentrates on mechanical properties of woven fabric kenaf composites with single-lap hybrid joints configurations. Four width to diameter ratio, (W/d of cross-ply lay-up joints as designed in testing series were tested by using quasi static mechanical testing. Experimental results showed that the failure load increased with the increasing of W/d ratios. Thinner lay-up had better bearing strength compared to thicker lay-up as found in current study.

  16. Mechanical characteristics of low-cost hybrid fiber reinforced polymer.

    Science.gov (United States)

    2014-07-01

    This report deals with the experimental investigation of using large deformable FRP, 45 oriented fibers, in concrete-filled fiber : tubes (CFFT) under axial cyclic compressive loading. In addition, this report presents finite element modeling (F...

  17. Superconducting properties and uniaxial strain characteristics of Nb3Sn fiber-reinforced superconductors with tantalum reinforcement fibers

    International Nuclear Information System (INIS)

    Arai, Kazuaki; Umeda, Masaichi; Agatsuma, Koh; Tateishi, Hiroshi

    1998-01-01

    We have been developing fiber-reinforced superconductors (FRS) for high-field and large-scale magnets. Tungsten fibers have been selected as the reinforcement fiber for FRS so far because tungsten has the highest elastic modulus of approximately 400 GPa which can minimize the strain from electromagnetic force. The preparation process of FRS consists of sputtering deposition and heat treatment because it may be difficult to apply drawing methods to materials of high-elastic modulus such as tungsten. Tantalum has high elastic modulus of 178 GPa and its thermal expansion coefficient that is closer to that of Nb 3 Sn than tungsten's, which means prestrain in Nb 3 Sn in FRS is reduced by adopting tantalum fibers. Tantalum has been used as barriers between bronze and copper in conventional Nb 3 Sn superconductors which are usually prepared with drawing process despite of the tantalum's high elastic modulus. That implies drawing process may be applied to prepare FRS with tantalum reinforcement fibers. In this paper, FRS using tantalum fibers prepared with sputtering process are described with making comparison with FRS of tungsten to clarify the basic properties of FRS using tantalum fibers. Depth profiles in Nb 3 Sn layer in FRS were measured to examine reaction between superconducting layers and reinforcement fibers. Superconducting properties including strain and stress characteristics were shown. Those data will contribute to design of FRS using tantalum reinforcement fibers with adopts the drawing processes. (author)

  18. Hollow-fiber membrane bioreactor for the treatment of high-strength landfill leachate

    KAUST Repository

    Rizkallah, Marwan

    2013-07-15

    Performance assessment of membrane bioreactor (MBR) technology for the treatability of high-strength landfill leachate is relatively limited or lacking. This study examines the feasibility of treating high-strength landfill leachate using a hollow-fiber MBR. For this purpose, a laboratory-scale MBR was constructed and operated to treat leachate with a chemical oxygen demand (COD) of 9000-11,000 mg/l, a 5-day biochemical oxygen demand (BOD5) of 4000-6,000 mg/l, volatile suspended solids (VSS) of 300-500 mg/l, total nitrogen (TN) of 2000-6000 mg/l, and an ammonia-nitrogen (NH3-N) of 1800-4000 mg/l. VSS was used with the BOD and COD data to simulate the biological activity in the activated sludge. Removal efficiencies > 95-99% for BOD5, VSS, TN and NH3-N were attained. The coupled experimental and simulation results contribute in filling a gap in managing high-strength landfill leachate and providing guidelines for corresponding MBR application. © The Author(s) 2013.

  19. Experimental and analytical investigation of reinforced high strength concrete continuous beams strengthened with fiber reinforced polymer

    International Nuclear Information System (INIS)

    Akbarzadeh, H.; Maghsoudi, A.A.

    2010-01-01

    Carbon and glass fiber reinforced polymer (CFRP and GFRP) are two materials suitable for strengthening the reinforced concrete (RC) beams. Although many in situ RC beams are of continuous constructions, there has been very limited research on the behavior of such beams with externally applied FRP laminate. In addition, most design guidelines were developed for simply supported beams with external FRP laminates. This paper presents an experimental program conducted to study the flexural behavior and redistribution in moment of reinforced high strength concrete (RHSC) continuous beams strengthened with CFRP and GFRP sheets. Test results showed that with increasing the number of CFRP sheet layers, the ultimate strength increases, while the ductility, moment redistribution, and ultimate strain of CFRP sheet decrease. Also, by using the GFRP sheet in strengthening the continuous beam reduced loss in ductility and moment redistribution but it did not significantly increase ultimate strength of beam. The moment enhancement ratio of the strengthened continuous beams was significantly higher than the ultimate load enhancement ratio in the same beam. An analytical model for moment-curvature and load capacity are developed and used for the tested continuous beams in current and other similar studies. The stress-strain curves of concrete, steel and FRP were considered as integrity model. Stress-strain model of concrete is extended from Oztekin et al.'s model by modifying the ultimate strain. Also, new parameters of equivalent stress block are obtained for flexural calculation of RHSC beams. Good agreement between experiment and prediction values is achieved.

  20. Shear strength of reinforced concrete beams strengthened by P.B.O. fiber mesh under loading

    Directory of Open Access Journals (Sweden)

    Blikharskyy Zinoviy

    2017-01-01

    Full Text Available This article presents experimental study of sheer strength of reinforced concrete beams without transverse steel reinforcement, which strengthened by composite materials. The feature of tests is that the beams’ strengthening is made under simultaneous action of loading. The research program involves a series of test beams with size 2100 × 200 × 100 mm and which contains control sample and three reinforced samples by reinforcing FRCM system. FRCM system consisting of two components: mineral mortar based on modified cement Ruredil X Mesh M750 and reinforcing P.B.O. fiber mesh Ruredil X Mesh Gold (Italy. The strength research of test samples was carried out with the shear distance to effective depth ratio a/d = 2. The strengthening loading levels were selected at 0.0, 0.3, 0.5 from shear strength of non strengthened control sample. As a result of experimental studies we found that during strengthening design the inclined cross section of beams we should take into account the existing level of loading. Using the strengthening system Ruredil X Mesh Gold the strengthening effect is reduced at 2.8 to 2.9 times while the existing level of loading increase from 0 to 50%.

  1. Influence of sand to coarse aggregate ratio on the interfacial bond strength of steel fibers in concrete for nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Jin, E-mail: jjinslow@nate.com [Department of Civil and Environmental Engineering, SeJong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Kim, Dong Joo, E-mail: djkim75@sejong.ac.kr [Department of Civil and Environmental Engineering, SeJong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Kang, Su Tae, E-mail: stkang@daegu.ac.kr [Department of Civil Engineering, Daegu University, 201 Daegudae-ro, Jillyang, Gyeongsan, Gyeongbuk 712-714 (Korea, Republic of); Lee, Jang Hwa, E-mail: jhlee@kict.re.kr [Korea Institute of Construction Technology, 2311 Daewha-Dong, Ilsan-Gu, Goyang-Si, Gyeonggi-Do 411-712 (Korea, Republic of)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The final goal is to develop a fiber reinforced concrete for containment buildings. Black-Right-Pointing-Pointer We investigated the effect of S/a on the bond strength of steel fibers. Black-Right-Pointing-Pointer Deformed steel fibers produced much higher interfacial bond strength. Black-Right-Pointing-Pointer As S/a increased, twisted fiber showed a significant enhancement in bond strength. Black-Right-Pointing-Pointer Smooth and hooked fiber showed no clear difference as S/a increased. - Abstract: The interfacial bond strength of three high strength steel fibers (smooth, hooked, and twisted fiber) in concrete of nuclear power plants was investigated to develop fiber reinforced concrete for containment building. Sand to aggregate ratio (S/a) was adjusted to compensate reduction in the workability due to adding fibers; the influence of S/a ratio on the interfacial bond strength was investigated. As the S/a ratio increased from 0.444 to 0.615, the bond strength of twisted steel fiber was significantly improved while smooth and hooked steel fiber showed no clear difference. The different sensitivity according to the S/a ratio results from the different pullout mechanism: twisted steel fiber generates more mechanical interaction during fiber pullout at the interface between fiber and matrix than smooth and hooked fibers. The microscopic observation by scanning electron microscope back-scattered electrons images discovered lower porosity at the interfacial transition zone between fiber and concrete with higher S/a ratio.

  2. A Laboratory Investigation on Shear Strength Behavior of Sandy Soil: Effect of Glass Fiber and Clinker Residue Content

    Directory of Open Access Journals (Sweden)

    Bouaricha Leyla

    2017-12-01

    Full Text Available A study was undertaken to investigate the shear strength parameters of treated sands reinforced with randomly distributed glass fibers by carrying out direct shear test after seven days curing periods. Firstly, we studied the fiber content and fiber length effect on the peak shear strength on samples. The second part gives a parametric analysis on the effect of glass fiber and clinker residue content on the shear strength parameters for two types of uniform Algerian sands having different particle sizes (Chlef sand and Rass sand with an average relative density Dr = 50%. Finally, the test results show that the combination of glass fiber and clinker residue content can effectively improve the shear strength parameters of soil in comparison with unreinforced soil. For instance, there is a significant gain for the cohesion and friction angle of reinforced sand of Chlef. Compared to unreinforced sand, the cohesion for sand reinforced with different ratios of clinker residue increased by 4.36 to 43.08 kPa for Chlef sand and by 3.1 to 28.64 kPa for Rass sand. The feature friction angles increased from 38.73° to 43.01° (+4.28°, and after the treatment, clinker residue content of soil evaluated to 5% (WRC = 5%.

  3. A Laboratory Investigation on Shear Strength Behavior of Sandy Soil: Effect of Glass Fiber and Clinker Residue Content

    Science.gov (United States)

    Bouaricha, Leyla; Henni, Ahmed Djafar; Lancelot, Laurent

    2017-12-01

    A study was undertaken to investigate the shear strength parameters of treated sands reinforced with randomly distributed glass fibers by carrying out direct shear test after seven days curing periods. Firstly, we studied the fiber content and fiber length effect on the peak shear strength on samples. The second part gives a parametric analysis on the effect of glass fiber and clinker residue content on the shear strength parameters for two types of uniform Algerian sands having different particle sizes (Chlef sand and Rass sand) with an average relative density Dr = 50%. Finally, the test results show that the combination of glass fiber and clinker residue content can effectively improve the shear strength parameters of soil in comparison with unreinforced soil. For instance, there is a significant gain for the cohesion and friction angle of reinforced sand of Chlef. Compared to unreinforced sand, the cohesion for sand reinforced with different ratios of clinker residue increased by 4.36 to 43.08 kPa for Chlef sand and by 3.1 to 28.64 kPa for Rass sand. The feature friction angles increased from 38.73° to 43.01° (+4.28°), and after the treatment, clinker residue content of soil evaluated to 5% (WRC = 5%).

  4. Compressive Strength Characteristics of Carbon, Palm Kernel and ...

    African Journals Online (AJOL)

    ADOWIE PERE

    2018-03-15

    Mar 15, 2018 ... reinforced concrete was one of the topics of interest. Once the health risks ... over the Portland cement concrete, some of which includes higher strength ... be used in the construction industry as a binder for aggregates.

  5. Fabricating and strengthening the carbon nanotube/copper composite fibers with high strength and high electrical conductivity

    Science.gov (United States)

    Han, Baoshuai; Guo, Enyu; Xue, Xiang; Zhao, Zhiyong; Li, Tiejun; Xu, Yanjin; Luo, Liangshun; Hou, Hongliang

    2018-05-01

    Combining the excellent properties of carbon nanotube (CNT) and copper, CNT/Cu composite fibers were fabricated by physical vapor deposition (PVD) and rolling treatment. Dense and continuous copper film (∼2 μm) was coated on the surface of the CNT fibers by PVD, and rolling treatment was adopt to strengthen the CNT/Cu composite fibers. After the rolling treatment, the defects between the Cu grains and the CNT bundles were eliminated, and the structure of both the copper film and the core CNT fibers were optimized. The rolled CNT/Cu composite fibers possess high tensile effective strength (1.01 ± 0.13 GPa) and high electrical conductivity ((2.6 ± 0.3) × 107 S/m), and thus, this material may become a promising wire material.

  6. Grafting Carbon Nanotubes on Glass Fiber by Dip Coating Technique to Enhance Tensile and Interfacial Shear Strength

    Directory of Open Access Journals (Sweden)

    Bahador Dastorian Jamnani

    2015-01-01

    Full Text Available The effects of noncovalent bonding and mechanical interlocking of carbon nanotubes (CNT coating on tensile and interfacial strength of glass fiber were investigated. CNT were coated over glass fiber by a simple dip coating method. Acid treated CNT were suspended in isopropanol solution containing Nafion as binding agent. To achieve uniform distribution of CNT over the glass fiber, an optimized dispersion process was developed by two parameters: CNT concentration and soaking time. CNT concentration was varied from 0.4 to 2 mg/mL and soaking time was varied from 1 to 180 min. The provided micrographs demonstrated appropriate coating of CNT on glass fiber by use of CNT-Nafion mixture. The effects of CNT concentration and soaking time on coating layer were studied by performing single fiber tensile test and pull-out test. The obtained results showed that the optimum CNT concentration and soaking time were 1 mg/mL and 60 min, respectively, which led to significant improvement of tensile strength and interfacial shear stress. It was found that, at other concentrations and soaking times, CNT agglomeration or acutely curly tubes appeared over the fiber surface which caused a reduction of nanotubes interaction on the glass fiber.

  7. Strength Analysis of the Carbon-Fiber Reinforced Polymer Impeller Based on Fluid Solid Coupling Method

    Directory of Open Access Journals (Sweden)

    Jinbao Lin

    2014-01-01

    Full Text Available Carbon-fiber reinforced polymer material impeller is designed for the centrifugal pump to deliver corrosive, toxic, and abrasive media in the chemical and pharmaceutical industries. The pressure-velocity coupling fields in the pump are obtained from the CFD simulation. The stress distribution of the impeller couple caused by the flow water pressure and rotation centrifugal force of the blade is analyzed using one-way fluid-solid coupling method. Results show that the strength of the impeller can meet the requirement of the centrifugal pumps, and the largest stress occurred around the blades root on a pressure side of blade surface. Due to the existence of stress concentration at the blades root, the fatigue limit of the impeller would be reduced greatly. In the further structure optimal design, the blade root should be strengthened.

  8. Fatigue Behavior of Steel Fiber Reinforced High-Strength Concrete under Different Stress Levels

    Science.gov (United States)

    Zhang, Chong; Gao, Danying; Gu, Zhiqiang

    2017-12-01

    The investigation was conducted to study the fatigue behavior of steel fiber reinforced high-strength concrete (SFRHSC) beams. A series of 5 SFRHSC beams was conducted flexural fatigue tests at different stress level S of 0.5, 0.55, 0.6, 0.7 and 0.8 respectively. Static test was conducted to determine the ultimate static capacity prior to fatigue tests. Fatigue modes and S-N curves were analyzed. Besides, two fatige life prediction model were analyzed and compared. It was found that stress level S significantly influenced the fatigue life of SFRHSC beams and the fatigue behavior of SFRHSC beams was mainly determined by the tensile reinforcement.

  9. Skeletal muscle fiber characteristics and oxidative capacity in hemiparetic stroke survivors

    DEFF Research Database (Denmark)

    Severinsen, Kaare; Dalgas, Ulrik; Overgaard, Kristian

    2016-01-01

    by ATPase histochemistry. Enzymatic concentrations of citrate synthase (CS) and 3-Hydroxyacyl-coenzymeA-dehydrogenase (HAD) were determined using freeze-dried muscle tissue. Findings were correlated with clinical outcomes. RESULTS: In the paretic muscles the mean fiber area was smaller (P=0.......0004), and a lower proportion of type 1 fibers (P=0.0016) and a higher proportion of type 2X fibers (P=0.0002) were observed. The paretic muscle had lower CS (P=0.013) and HAD concentrations (P=0.037). Mean fiber area correlated with muscle strength (r=0.43, P=0.041), and CS concentration correlated with aerobic...

  10. Agricultural residues based composites part II: Hydration characteristics of cement- cellulosic fibers composites

    International Nuclear Information System (INIS)

    Hekal, E.E.; Kishar, E.A.; Abd-El-Khader, A.H.; Ibrahim, A.A.; Mobarak, F.M.

    2005-01-01

    The aim of this study is the utilization of the local agricultural wastes, such as ice straw bagasse, cotton stalks and linen fibers, which cause a big environmental problem. Different cement-fiber composites were prepared using 1.5, 3, 4.5 and 6% fibers by weight of cement. The lengths of the fibers used were 0.5, 0.8, and 1.25 mm. Hydration of the different, composites was carried out at room temperature for various lime intervals namely, 1.3,7 .28 and 90 days. Combined water contents, compressive strength and phase composition of the different prepared composites were examined

  11. Developmental characteristics of parenchyma and fiber cells and their secondary wall deposition in fargesia yunnanensis

    International Nuclear Information System (INIS)

    Wang, S.G.; Zhan, H.; Wan, C.B.; Lin, S.Y.

    2017-01-01

    The aim of this study is to describe and analyse the morphological characteristics of nuclei and the secondary wall deposition in parenchyma and fiber cells during the whole bamboo growth cycle from shoots to old culms, with a further purpose to assess the developmental differences between fibers and parenchyma cells and analyze the secondary wall deposition mechanism. Initially the fiber wall thickness was less than the parenchyma cell thickness in young shoots, but increased significantly after 1 year. Fibers elongated earlier than both their nuclei and parenchyma cells. Fiber nuclei also elongated and presented the spindle shape in longitudinal section. The formation and elongation of long cells were involved in the fast elongation of internodes. In mature culms, the ways of secondary wall deposition for fibers depended on their diameter and positions. Large diameter fibers usually had more cell wall layers than narrow fibers. (author)

  12. Effect of Reinforcement Using Stainless Steel Mesh, Glass Fibers, and Polyethylene on the Impact Strength of Heat Cure Denture Base Resin - An In Vitro Study.

    Science.gov (United States)

    Murthy, H B Mallikarjuna; Shaik, Sharaz; Sachdeva, Harleen; Khare, Sumit; Haralur, Satheesh B; Roopa, K T

    2015-06-01

    The impact strength of denture base resin is of great concern and many approaches have been made to strengthen acrylic resin dentures. The objective of this study was to compare the impact strength of the denture base resin with and without reinforcement and to evaluate the impact strength of denture base resin when reinforced with stainless steel mesh, glass fiber, and polyethylene fibers in the woven form. The specimens (maxillary denture bases) were fabricated using a standard polyvinylsiloxane mold with conventional heat cured polymethyl methacrylate resin. The specimens were divided into four groups (n = 10). Group I specimens or control group were not reinforced. Group II specimens were reinforced with stainless steel mesh and Group III and Group IV specimens were reinforced with three percent by weight of glass fibers and polyethylene fibers in weave form respectively. All the specimens were immersed in water for 1-week before testing. The impact strength was measured with falling weight impact testing machine. One-way analysis of variance and Tukey's post-hoc test were used for statistical analysis. Highest impact strength values were exhibited by the specimens reinforced with polyethylene fibers followed by glass fibers, stainless steel mesh, and control group. Reinforcement of maxillary complete dentures showed a significant increase in impact strength when compared to unreinforced dentures. Polyethylene fibers exhibit better impact strength followed by glass fibers and stainless steel mesh. By using pre-impregnated glass and polyethylene fibers in woven form (prepregs) the impact strength of the denture bases can be increased effectively.

  13. Influence of periodontal ligament simulation on bond strength and fracture resistance of roots restored with fiber posts

    Directory of Open Access Journals (Sweden)

    Ana Maria Estivalete MARCHIONATTI

    2014-10-01

    Full Text Available Objective: Considering that periodontal ligament simulation may influence the stress distribution over teeth restored with intraradicular retainers, this study aimed to assess the combined effect of mechanical cycling and periodontal ligament simulation on both the bond strength between fiber posts and root dentin and the fracture resistance of teeth restored using glass fiber posts. Material and Methods: Ninety roots were randomly distributed into 3 groups (n=10 (C-MC: control; P-MC: polyether; AS-MC: addition silicone to test bond strength and 6 groups (n=10 (C: control; P: polyether; AS: addition silicone, without mechanical cycling, and C-MC, P-MC and AS-MC with mechanical cycling to test fracture strength, according to the material used to simulate the periodontal ligament. For the bond strength test, fiber posts were cemented, cores were built, mechanical cycling was applied (2×106 cycles, 88 N, 2.2 Hz, and 45º incline, and the teeth cut into 3 slices (2 mm, which were then subjected to the push-out test at 1 mm/min. For the fracture strength test, fiber posts were cemented, cores were built, and half of the groups received mechanical cycling, followed by the compressive strength (45° to the long axis and 1 mm/min performed on all groups. Results: Periodontal ligament simulation did not affect the bond strength (p=0.244 between post and dentin. Simulation of periodontal ligament (p=0.153 and application of mechanical cycling (p=0.97 did not affect fracture resistance. Conclusions: The materials used to simulate the periodontal ligament did not affect fracture or bond strength, therefore periodontal ligament simulation using the tested materials could be considered optional in the conditions of the study.

  14. Effect of surface chemistry, solution pH, and ionic strength on the removal of herbicides diuron and amitrole from water by an activated carbon fiber.

    Science.gov (United States)

    Fontecha-Cámara, M A; López-Ramón, M V; Alvarez-Merino, M A; Moreno-Castilla, C

    2007-01-30

    A study was conducted on the effects of carbon surface chemistry, solution pH, and ionic strength on the removal of diuron and amitrole from aqueous solutions by adsorption on an as-received and oxidized activated carbon fiber. Results obtained were explained by the surface characteristics of the adsorbents and the characteristics of the herbicide molecules. Under the experimental conditions used, diuron uptake was much higher than that of amitrole, despite its larger molecular dimensions, due to the lesser water solubility, greater hydrophobicity, and larger dipolar moment of diuron compared with amitrole. Uptake variations associated with differences in carbon surface oxidation, solution pH, and ionic strength were explained by corresponding changes in electrostatic, hydrophobic, and van der Waals interactions.

  15. Effect of particle size and distribution of the sizing agent on the carbon fibers surface and interfacial shear strength (IFSS) of its composites

    International Nuclear Information System (INIS)

    Zhang, R.L.; Liu, Y.; Huang, Y.D.; Liu, L.

    2013-01-01

    Effect of particle size and distribution of the sizing agent on the performance of carbon fiber and carbon fiber composites has been investigated. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to characterize carbon fiber surface topographies. At the same time, the single fiber strength and Weibull distribution were also studied in order to investigate the effect of coatings on the fibers. The interfacial shear strength and hygrothermal aging of the carbon fiber/epoxy resin composites were also measured. The results indicated that the particle size and distribution is important for improving the surface of carbon fibers and its composites performance. Different particle size and distribution of sizing agent has different contribution to the wetting performance of carbon fibers. The fibers sized with P-2 had higher value of IFSS and better hygrothermal aging resistant properties.

  16. Flexural strength using Steel Plate, Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) on reinforced concrete beam in building technology

    Science.gov (United States)

    Tarigan, Johannes; Patra, Fadel Muhammad; Sitorus, Torang

    2018-03-01

    Reinforced concrete structures are very commonly used in buildings because they are cheaper than the steel structures. But in reality, many concrete structures are damaged, so there are several ways to overcome this problem, by providing reinforcement with Fiber Reinforced Polymer (FRP) and reinforcement with steel plates. Each type of reinforcements has its advantages and disadvantages. In this study, researchers discuss the comparison between flexural strength of reinforced concrete beam using steel plates and Fiber Reinforced Polymer (FRP). In this case, the researchers use Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) as external reinforcements. The dimension of the beams is 15 x 25 cm with the length of 320 cm. Based on the analytical results, the strength of the beam with CFRP is 1.991 times its initial, GFRP is 1.877 times while with the steel plate is 1.646 times. Based on test results, the strength of the beam with CFRP is 1.444 times its initial, GFRP is 1.333 times while the steel plate is 1.167 times. Based on these test results, the authors conclude that beam with CFRP is the best choice for external reinforcement in building technology than the others.

  17. Effect of Endodontic Retreatment on Push-out Bond Strength and Quality of Fiber Postbonding Interface of Resin Cements.

    Science.gov (United States)

    Pelegrine, Rina Andréa; Paulillo, Luís Alexandre Maffei Sartini; Kato, Augusto Shoji; Fontana, Carlos Eduardo; Pinheiro, Sérgio Luiz; De Martin, Alexandre Sigrist; Bueno, Carlos Eduardo da Silveira

    2016-01-01

    The aim of this study is to evaluate the impact of endodontic retreatment on push-out bond strength and dentin interface of two resin cements used for fiber postcementation during endodontic retreatment. The root canals of 40 extracted human canines were prepared, obturated and divided into four groups (n = 10). Gutta-percha was partially removed and fiber posts were immediately cemented in groups 1 and 2 using Panavia F with ED Primer and RelyX™ U200, respectively. In groups 3 and 4, the root canal access was sealed with temporary restorative cement, specimens were stored for 30 days, endodontically retreated, and fiber posts were cemented using the resin cements applied to groups 1 and 2, respectively. Push-out tests and scanning electron microscopy analyses of different areas were performed. Data from push-out bond strengths were analyzed by one-way analysis of variance and Tukey's tests. Higher bond strength values were detected in the apical third for group 1 than group 3 (p 0.05). Comparisons between different thirds in the same group revealed a higher bond strength in the apical third for group 1. Scanning electron microscopy showed formation of hybrid layer and extensive resin tags in group 1. No hybrid layer was observed in groups 2 and 4. Endodontic retreatment had adverse effects on the push-out bond strength and dentinal interface of Panavia F with ED Primer when used for fiber postcementation specifically in the apical third, but not on RelyX™ U200. A significant interaction was detected between endodontic retreatment and resin cement, which indicated that endodontic retreatment might adversely affect the push-out bond strength and dentinal interface of Panavia F with ED Primer when used for fiber postcementation specifically in the apical third.

  18. Interlaminar shear strength of SiC matrix composites reinforced by continuous fibers at 900 °C in air

    International Nuclear Information System (INIS)

    Zhang, Chengyu; Gou, Jianjie; Qiao, Shengru; Wang, Xuanwei; Zhang, Jun

    2014-01-01

    Highlights: • The application of SiC fiber could improve ILSS of the SiC matrix composites. • The orientation of the warp fibers plays a critical role in determining ILSS of 2.5D-C/SiC. • The failure mechanisms of 2D composites involve matrix cracking, and interfacial debonding. - Abstract: To reveal the shear properties of SiC matrix composites, interlaminar shear strength (ILSS) of three kinds of silicon carbide matrix composites was investigated by compression of the double notched shear specimen (DNS) at 900 °C in air. The investigated composites included a woven plain carbon fiber reinforced silicon carbide composite (2D-C/SiC), a two-and-a-half-dimensional carbon fiber-reinforced silicon carbide composite (2.5D-C/SiC) and a woven plain silicon carbon fiber reinforced silicon carbide composite (2D-SiC/SiC). A scanning electron microscope was employed to observe the microstructure and fracture morphologies. It can be found that the fiber type and reinforcement architecture have significant impacts on the ILSS of the SiC matrix composites. Great anisotropy of ILSS can be found for 2.5D-C/SiC because of the different fracture resistance of the warp fibers. Larger ILSS can be obtained when the specimens was loaded along the weft direction. In addition, the SiC fibers could enhance the ILSS, compared with carbon fibers. The improvement is attributed to the higher oxidation resistance of SiC fibers and the similar thermal expansion coefficients between the matrix and the fibers

  19. influence of molding water content on shear strength characteristic

    African Journals Online (AJOL)

    eobe

    INFLUENCE OF MOLDING WATER CONTENT ON SHEAR STRENGTH OF COMPACTED CEMENT KILN DUST, K. J. Osinub. K. J. Osinub. K. J. Osinubi, et al. Nigerian Journal of Technology,. Vol. 34, No. 2, April 2015 267 pavements or as waste containment materials. Therefore, recent studies have been geared towards.

  20. Strength and water absorption characteristics of cement-bonded ...

    African Journals Online (AJOL)

    Contrary to conventional practice, the boards were fabricated in the laboratory without external pressure application. The effects of calcium chloride (CaCl2) addition on the hardening time, appearance, bending and compressive strength, and water absorption properties of the boards were also investigated. The boards had ...

  1. Immediate Repair Bond Strength of Fiber-reinforced Composite after Saliva or Water Contamination.

    Science.gov (United States)

    Bijelic-Donova, Jasmina; Flett, Andrew; Lassila, Lippo V J; Vallittu, Pekka K

    2018-05-31

    This in vitro study aimed to evaluate the shear bond strength (SBS) of particulate filler composite (PFC) to saliva- or water-contaminated fiber-reinforced composite (FRC). One type of FRC substrate with semi-interpenetrating polymer matrix (semi-IPN) (everStick C&B) was used in this investigation. A microhybrid PFC (Filtek Z250) substrate served as control. Freshly cured PFC and FRC substrates were first subjected to different contamination and surface cleaning treatments, then the microhybrid PFC restorative material (Filtek Z250) was built up on the substrates in 2-mm increments and light cured. Uncontaminated and saliva- or water-contaminated substrate surfaces were either left untreated or were cleaned via phosphoric acid etching or water spray accompanied with or without adhesive composite application prior applying the adherent PFC material. SBS was evaluated after thermocycling the specimens (6000 cycles, 5°C and 55°C). Three-way ANOVA showed that both the surface contamination and the surface treatment signficantly affected the bond strength (p contamination reduced the SBS more than did the water contamination. SBS loss after saliva contamination was 73.7% and 31.3% for PFC and FRC, respectively. After water contamination, SBS loss was 17.2% and 13.3% for PFC and FRC, respectively. The type of surface treatment was significant for PFC (p contamination of freshly cured PFC or semi-IPN FRC, surfaces should be re-prepared via phosphoric acid etching, water cleaning, drying, and application of adhesive composite in order to recover optimal bond strength.

  2. Fracture strength and bending of all-ceramic and fiber-reinforced composites in inlay-retained fixed partial dentures

    Directory of Open Access Journals (Sweden)

    Serkan Saridag

    2012-06-01

    Conclusions: Zirconia-based ceramic inlay-retained fixed partial dentures demonstrated the highest fracture strength. The fiber-reinforced composite inlay-retained fixed partial dentures demonstrated higher bending values than did the all-ceramic inlay-retained fixed partial dentures.

  3. Behavior of hybrid high-strength fiber reinforced concrete slab-column connections under the effect of high tempera

    Directory of Open Access Journals (Sweden)

    Reham H. Ahmed

    2016-04-01

    Full Text Available Concrete can be modified to perform in a more ductile form by the addition of randomly distributed discrete fibers in the concrete matrix. The combined effect of the addition of two types of fibers (steel fiber and polypropylene fiber with different percentages to concrete matrix, which is called hybrid effect is currently under investigation worldwide. The current research work presents the conducted experimental program to observe the behavior of hybrid high strength reinforced concrete slab-column connections under the effect of high temperature. For this purpose, ten slab-column connections were casted and tested. The experimental program was designed to investigate the effect of different variables such as concrete mixture, column location and temperature fighting system. All specimens were exposed to a temperature of 500 °C for duration of two hours. To observe the effect of each variable, specimens were divided into four groups according to the studied parameters. The test results revealed that using hybrid high strength concrete HFHSC produced more strength in punching failure compared with high strength concrete HSC when exposed to elevated temperature. Fighting by air had higher initial crack load compared with that for without fighting and fighting by water. On the other hand, fighting by water decreased the ultimate load.

  4. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    Science.gov (United States)

    Wang, Yuwei; Meng, Linghui; Fan, Liquan; Wu, Guangshun; Ma, Lichun; Zhao, Min; Huang, Yudong

    2016-01-01

    Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17-10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  5. Effect of fabric structure and polymer matrix on flexural strength, interlaminar shear stress, and energy dissipation of glass fiber-reinforced polymer composites

    Science.gov (United States)

    We report the effect of glass fiber structure and the epoxy polymer system on the flexural strength, interlaminar shear stress (ILSS), and energy absorption properties of glass fiber-reinforced polymer (GFRP) composites. Four different GFRP composites were fabricated from two glass fiber textiles of...

  6. Environmental Factors Affecting the Strength Characteristics of Modified Resin Mortars

    Science.gov (United States)

    Debska, Bernardeta; Licholai, Lech

    2017-12-01

    Resin concretes are composites in which a cement binder has been completely replaced by a synthetic resin. These materials are a good choice for the construction industry, especially in solutions requiring high strength, fast curing and durability. Polymer mortars are mainly used for the manufacture of industrial floors and prefabricated products such as tanks for aggressive chemicals, sewage pipes, or road and bridge drainage systems, as well as for the repair of damaged concrete structures. In all these applications, the strength and high chemical resistance of the applied material solutions are of key importance. It is particularly crucial to obtain information on how resin composites behave when exposed to aggressive agents over extended periods of time. It is also very important to use waste materials in order to obtain resin composites, as these activities are very well inscribed in the idea of environmental protection and meet the criteria of sustainable construction. The mortars described in this article meet the above principles. The article presents how the compressive strength of glycolyzate-modified epoxy mortars, obtained with the use of poly(ethylene terephthalate), changes after they are immersed in 10% sodium chloride solution. Sodium chloride solution was chosen due to the prospective applicability of the tested composites as repair materials used for e.g. bridges or overpasses that are exposed to this salt solution in wintertime. Changes in the properties of the composite samples were monitored over the period of one year. Statistical analysis of the test results was carried out with the use of Statistica programme. The module available in the mentioned program called Nonparametric Statistics - Comparing multiple independent samples made it possible to check the monitoring times during which the compressive strength values differed significantly. The obtained results allowed for determining the equation of the function approximating the course of

  7. Evaluation of insertion characteristics of less invasive Si optoneural probe with embedded optical fiber

    Science.gov (United States)

    Morikawa, Takumi; Harashima, Takuya; Kino, Hisashi; Fukushima, Takafumi; Tanaka, Tetsu

    2017-04-01

    A less invasive Si optoneural probe with an embedded optical fiber was proposed and successfully fabricated. The diameter of the optical fiber was completely controlled by hydrogen fluoride etching, and the thinned optical fiber can propagate light without any leakage. This optical fiber was embedded in a trench formed inside a probe shank, which causes less damage to tissues. In addition, it was confirmed that the optical fiber embedded in the probe shank successfully irradiated light to optically stimulate gene transfected neurons. The electrochemical impedance of the probe did not change despite the light irradiation. Furthermore, probe insertion characteristics were evaluated in detail and less invasive insertion was clearly indicated for the Si optoneural probe with the embedded optical fiber compared with conventional optical neural probes. This neural probe with the embedded optical fiber can be used as a simple and easy tool for optogenetics and brain science.

  8. Strength Characteristics of Quarry Dust in Replacement of Sand

    Science.gov (United States)

    Shyam Prakash, K.; Hanumantha Rao, Ch, Dr

    2017-08-01

    The replacement of natural fine aggregate by using quarry dust leads to consumption of generated quarry dust, the requirement of land fill area can be reduced and solves the natural sand scarcity problem. The sand availability as a fine aggregate at low cost which needs the reason to search as a alternative material. Even it causes saddle to dump the crusher dust at one place which causes environmental pollution. The chemical analysis, specific gravity, sieve analysis and compressive strength is identified for various percentage and grades of concrete by replacement of sand with quarry dust.

  9. Flow Characteristics of a Thermoset Fiber Composite Photopolymer Resin in a Vat Polymerization Additive Manufacturing Process

    DEFF Research Database (Denmark)

    Hofstätter, Thomas; Spangenberg, Jon; Pedersen, David B.

    Additive manufacturing vat polymerization has become a leading technology and gained a massive amount of attention in industrial applications such as injection molding inserts. By the use of the thermoset polymerization process inserts have increased their market share. For most industrial...... applications, strength and stiffness are crucial factors to a successful implementation of cured photopolymer thermosets. Hence, fiber-reinforced polymers have recently been introduced. The behavior and especially orientation of fibers during the vat photopolymerization process has yet not been fully...

  10. The response characteristics of vibration-sensitive saccular fibers in the grassfrog, Rana temporaria

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, J; Jørgensen, M B

    1988-01-01

    The response characteristics of saccular nerve fibers in European grassfrogs (Rana temporaria) subjected to dorso-ventral, 10-200 Hz sinusoidal vibrations were studied. Only 4 fibers out of a total of 129 did not respond to the vibrations. 70 fibers had an irregular spontaneous activity of 2-48 s...... motion of the otolith relative to the macula is complex. No behavioral role of a vibration receptor has been demonstrated in the grassfrog.(ABSTRACT TRUNCATED AT 250 WORDS)......The response characteristics of saccular nerve fibers in European grassfrogs (Rana temporaria) subjected to dorso-ventral, 10-200 Hz sinusoidal vibrations were studied. Only 4 fibers out of a total of 129 did not respond to the vibrations. 70 fibers had an irregular spontaneous activity of 2......-48 spikes/s. These fibers were very vibration-sensitive. The synchronization thresholds at 10-20 Hz varied from below 0.005 to 0.02 cm/s2. In contrast to earlier results, all these fibers had low-pass characteristics (with respect to acceleration) and responded maximally at 10 and 20 Hz. 55 fibers had...

  11. Numerical Investigation of Characteristic of Anisotropic Thermal Conductivity of Natural Fiber Bundle with Numbered Lumens

    Directory of Open Access Journals (Sweden)

    Guan-Yu Zheng

    2014-01-01

    Full Text Available Natural fiber bundle like hemp fiber bundle usually includes many small lumens embedded in solid region; thus, it can present lower thermal conduction than that of conventional fibers. In the paper, characteristic of anisotropic transverse thermal conductivity of unidirectional natural hemp fiber bundle was numerically studied to determine the dependence of overall thermal property of the fiber bundle on that of the solid region phase. In order to efficiently predict its thermal property, the fiber bundle was embedded into an imaginary matrix to form a unit composite cell consisting of the matrix and the fiber bundle. Equally, another unit composite cell including an equivalent solid fiber was established to present the homogenization of the fiber bundle. Next, finite element thermal analysis implemented by ABAQUS was conducted in the two established composite cells by applying proper thermal boundary conditions along the boundary of unit cell, and influences of the solid region phase and the equivalent solid fiber on the composites were investigated, respectively. Subsequently, an optional relationship of thermal conductivities of the natural fiber bundle and the solid region was obtained by curve fitting technique. Finally, numerical results from the obtained fitted curves were compared with the analytic Hasselman-Johnson’s results and others to verify the present numerical model.

  12. Improvement of Characteristics of Clayey Soil Mixed with Randomly Distributed Natural Fibers

    Science.gov (United States)

    Maity, J.; Chattopadhyay, B. C.; Mukherjee, S. P.

    2017-11-01

    In subgrade construction for flexible road pavement, properties of clayey soils available locally can be improved by providing randomly distributed fibers in the soil. The fibers added in subgrade constructions are expected to provide better compact interlocking system between the fiber and the soil grain, greater resistance to deformation and quicker dissipation of pore water pressure, thus helping consolidation and strengthening. Many natural fibers like jute, coir, sabai grass etc. which are economical and eco-friendly, are grown in abundance in India. If suitable they can be used as additive material in the subgrade soil to result in increase in strength and decrease in deformability. Such application will also reduce the cost of construction of roads, by providing lesser thickness of pavement layer. In this paper, the efficacy of using natural jute, coir or sabai grass fibers with locally available clayey soil has been studied. A series of Standard Proctor test, Soaked and Unsoaked California Bearing Ratio (CBR) test, and Unconfined Compressive Strength test were done on locally available clayey soil mixed with different types of natural fiber for various length and proportion to study the improvement of strength properties of fiber-soil composites placed at optimum moisture content. From the test results, it was observed that there was a substantial increase in CBR value for the clayey soil when mixed with increasing percentage of all three types of randomly distributed natural fibers up to 2% of the dry weight of soil. The CBR attains maximum value when the length for all types of fibers mixed with the clay taken in this study, attains a value of 10 mm.

  13. Predicting the drying shrinkage behavior of high strength portland cement mortar under the combined influence of fine aggregate and steel micro fiber

    International Nuclear Information System (INIS)

    Li, Zhengqi

    2017-01-01

    The workability, 28-day compressive strength and free drying shrinkage of a very high strength (121-142 MPa) steel micro fiber reinforced portland cement mortar were studied under a combined influence of fine aggregate content and fiber content. The test results showed that an increase in the fine aggregate content resulted in decreases in the workability, 28-day compressive strength and drying shrinkage of mortar at a fixed fiber content. An increase in the fiber content resulted in decreases in the workability and drying shrinkage of mortar, but an increase in the 28-day compressive strength of mortar at a fixed fine aggregate content. The modified Gardner model most accurately predicted the drying shrinkage development of the high strength mortars, followed by the Ross model and the ACI 209R-92 model. The Gardner model gave the least accurate prediction for it was developed based on a database of normal strength concrete. [es

  14. Predicting the drying shrinkage behavior of high strength portland cement mortar under the combined influence of fine aggregate and steel micro fiber

    Directory of Open Access Journals (Sweden)

    Zhengqi Li

    2017-03-01

    Full Text Available The workability, 28-day compressive strength and free drying shrinkage of a very high strength (121-142 MPa steel micro fiber reinforced portland cement mortar were studied under a combined influence of fine aggregate content and fiber content. The test results showed that an increase in the fine aggregate content resulted in decreases in the workability, 28-day compressive strength and drying shrinkage of mortar at a fixed fiber content. An increase in the fiber content resulted in decreases in the workability and drying shrinkage of mortar, but an increase in the 28-day compressive strength of mortar at a fixed fine aggregate content. The modified Gardner model most accurately predicted the drying shrinkage development of the high strength mortars, followed by the Ross model and the ACI 209R-92 model. The Gardner model gave the least accurate prediction for it was developed based on a database of normal strength concrete.

  15. Effect of repeated sterilization by different methods on strength of carbon fiber rods used in external fixator systems.

    Science.gov (United States)

    Unal, Omer Kays; Poyanli, Oguz Sukru; Unal, Ulku Sur; Mutlu, Hasan Huseyin; Ozkut, Afsar Timucin; Esenkaya, Irfan

    2018-05-16

    We set out to reveal the effects of repeated sterilization, using different methods, on the carbon fiber rods of external fixator systems. We used a randomized set of forty-four unused, unsterilized, and identical carbon fiber rods (11 × 200 mm), randomly assigned to two groups: unsterilized (US) (4 rods) and sterilized (40 rods). The sterilized rods were divided into two groups, those sterilized in an autoclave (AC) and by hydrogen peroxide (HP). These were further divided into five subgroups based on the number of sterilization repetition to which the fibers were subjected (25-50-75-100-200). A bending test was conducted to measure the maximum bending force (MBF), maximum deflection (MD), flexural strength (FS), maximum bending moment (MBM) and bending rigidity (BR). We also measured the surface roughness of the rods. An increase in the number of sterilization repetition led to a decrease in MBF, MBM, FS, BR, but increased MD and surface roughness (p < 0.01). The effect of the number of sterilization repetition was more prominent in the HP group. This study revealed that the sterilization method and number of sterilization repetition influence the strength of the carbon fiber rods. Increasing the number of sterilization repetition degrades the strength and roughness of the rods.

  16. Effects of dietary fibers with different fermentation characteristics on feeding motivation in adult female pigs

    NARCIS (Netherlands)

    Souza Da Silva, C.; Bolhuis, J.E.; Gerrits, W.J.J.; Kemp, B.; Borne, van den J.J.G.C.

    2013-01-01

    Dietary fibers can be fermented in the colon, resulting in production of short-chain fatty acids (SCFA) and secretion of satiety-related peptides. Fermentation characteristics (fermentation kinetics and SCFA-profile) differ between fibers and could impact their satiating potential. We investigated

  17. A Study on the Interlaminar Shear Strength of Carbon Fiber Reinforced Plastics Depending on the Lamination Methods

    OpenAIRE

    Min Sang Lee; Hee Jae Shin; In Pyo Cha; Sun Ho Ko; Hyun Kyung Yoon; Hong Gun Kim; Lee Ku Kwac

    2015-01-01

    The prepreg process among the CFRP (Carbon Fiber Reinforced Plastic) forming methods is the short term of ‘Pre-impregnation’, which is widely used for aerospace composites that require a high quality property such as a fiber-reinforced woven fabric, in which an epoxy hardening resin is impregnated the reality. However, that this process requires continuous researches and developments for its commercialization because the delamination characteristically develops between th...

  18. The Effects of Fiber Inclusion on Pet Food Sensory Characteristics and Palatability.

    Science.gov (United States)

    Koppel, Kadri; Monti, Mariana; Gibson, Michael; Alavi, Sajid; Donfrancesco, Brizio Di; Carciofi, Aulus Cavalieri

    2015-02-16

    The objectives of this study were to determine (a) the influence of fiber on the sensory characteristics of dry dog foods; (b) differences of coated and uncoated kibbles for aroma and flavor characteristics; (c) palatability of these dry dog foods; and (d) potential associations between palatability and sensory attributes. A total of eight fiber treatments were manufactured: a control (no fiber addition), guava fiber (3%, 6%, and 12%), sugar cane fiber (9%; large and small particle size), and wheat bran fiber (32%; large and small particle size). The results indicated significant effects of fibers on both flavor and texture properties of the samples. Bitter taste and iron and stale aftertaste were examples of flavor attributes that differed with treatment, with highest intensity observed for 12% guava fiber and small particle size sugar cane fiber treatments. Fracturability and initial crispness attributes were lowest for the sugar cane fiber treatments. Flavor of all treatments changed after coating with a palatant, increasing in toasted, brothy, and grainy attributes. The coating also had a masking effect on aroma attributes such as stale, flavor attributes such as iron and bitter taste, and appearance attributes such as porosity. Palatability testing results indicated that the control treatment was preferred over the sugar cane or the wheat bran treatment. The treatment with large sugarcane fiber particles was preferred over the treatment with small particles, while both of the wheat bran treatments were eaten at a similar level. Descriptive sensory analysis data, especially textural attributes, were useful in pinpointing the underlying characteristics and were considered to be reasons that may influence palatability of dog foods manufactured with inclusion of different fibers.

  19. Fretting friction and wear characteristics of magnetorheological fluid under different magnetic field strengths

    International Nuclear Information System (INIS)

    Zhang, P.; Lee, K.H.; Lee, C.H.

    2017-01-01

    A magnetorheological fluid (MRF) performs differently under different magnetic field strength. This study examined the fretting friction and wear characteristics of MRFs under a range of magnetic field strengths and oscillation frequencies. The fretting friction and wear behaviors of MRF are investigated using a fretting friction and wear tester. The surfaces of specimen are examined by optical microscopy and 3D surface profilometer before and after the tests and wear surface profiles, the wear volume loss and wear coefficient for each magnetic field strength are evaluated. The results show that the friction and wear properties of MRF change according to the magnetic field strength and oscillation frequency. - Highlights: • Fretting friction and wear characteristics of MRF is examined. • The friction coefficients increased with increasing magnetic field strength. • The coefficient of friction decreased with increasing oscillation frequency. • Wear volume and coefficient become worse with increasing magnetic field strength.

  20. Bond strength of resin cement to dentin and to surface-treated posts of titanium alloy, glass fiber, and zirconia

    DEFF Research Database (Denmark)

    Sahafi, Alireza; Peutzfeldt, Anne; Asmussen, Erik

    2003-01-01

    PURPOSE: To determine the effect of surface treatments on bond strength of two resin cements (ParaPost Cement and Panavia F) to posts of titanium alloy (ParaPost XH), glass fiber (ParaPost Fiber White), and zirconia (Cerapost), and to dentin. MATERIALS AND METHODS: After embedding, planar surfaces...... of posts (n = 9 to 14) and human dentin (n = 10) were obtained by grinding. The posts received one of three surface treatments: 1. roughening (sandblasting, hydrofluoric acid etching), 2. application of primer (Alloy Primer, Metalprimer II, silane), or 3. roughening followed by application of primer...

  1. Increasing the strength and bioactivity of collagen scaffolds using customizable arrays of 3D-printed polymer fibers.

    Science.gov (United States)

    Mozdzen, Laura C; Rodgers, Ryan; Banks, Jessica M; Bailey, Ryan C; Harley, Brendan A C

    2016-03-01

    Tendon is a highly aligned connective tissue which transmits force from muscle to bone. Each year, people in the US sustain more than 32 million tendon injuries. To mitigate poor functional outcomes due to scar formation, current surgical techniques rely heavily on autografts. Biomaterial platforms and tissue engineering methods offer an alternative approach to address these injuries. Scaffolds incorporating aligned structural features can promote expansion of adult tenocytes and mesenchymal stem cells capable of tenogenic differentiation. However, appropriate balance between scaffold bioactivity and mechanical strength of these constructs remains challenging. The high porosity required to facilitate cell infiltration, nutrient and oxygen biotransport within three-dimensional constructs typically results in insufficient biomechanical strength. Here we describe the use of three-dimensional printing techniques to create customizable arrays of acrylonitrile butadiene styrene (ABS) fibers that can be incorporated into a collagen scaffold under development for tendon repair. Notably, mechanical performance of scaffold-fiber composites (elastic modulus, peak stress, strain at peak stress, and toughness) can be selectively manipulated by varying fiber-reinforcement geometry without affecting the native bioactivity of the collagen scaffold. Further, we report an approach to functionalize ABS fibers with activity-inducing growth factors via sequential oxygen plasma and carbodiimide crosslinking treatments. Together, we report an adaptable approach to control both mechanical strength and presence of biomolecular cues in a manner orthogonal to the architecture of the collagen scaffold itself. Tendon injuries account for more than 32 million injuries each year in the US alone. Current techniques use allografts to mitigate poor functional outcomes, but are not ideal platforms to induce functional regeneration following injury. Tissue engineering approaches using biomaterial

  2. Properties of Fiber Reinforced Polymer Concrete

    Directory of Open Access Journals (Sweden)

    Marinela Bărbuţă

    2008-01-01

    Full Text Available Polymer concrete is a composite material realized with resin and aggregates. In the present study the epoxy resin was used for binding the aggregates. In the composition were introduced near the fly ash, used as filler, the cellulose fibers. The mechanical characteristics such as compressive strength, flexural strength and split tensile strength of polymer concrete with fibers were investigated. The fiber percentage was constant, the epoxy resin and the filler dosages were varied. The cellulose fiber had not improved the mechanical characteristics of the polymer concrete in comparison to that of polymer concrete without cellulose fibers.

  3. Push-out bond strength of fiber posts to root dentin using glass ionomer and resin modified glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Jefferson Ricardo PEREIRA

    2014-10-01

    Full Text Available OBJECTIVE: The purpose of this study was to assess the push-out bond strength of glass fiber posts to root dentin after cementation with glass ionomer (GICs and resinmodified glass ionomer cements (RMGICs. MATERIAL AND METHODS: Fifty human maxillary canines were transversally sectioned at 15 mm from the apex. Canals were prepared with a step back technique until the application of a #55 K-file and filled. Post spaces were prepared and specimens were divided into five groups according to the cement used for post cementation: Luting & Lining Cement; Fuji II LC Improved; RelyX Luting; Ketac Cem; and Ionoseal. After cementation of the glass fiber posts, all roots were stored at 100% humidity until testing. For push-out test, 1-mm thick slices were produced. The push-out test was performed in a universal testing machine at a crosshead speed of 0.5 mm/minute and the values (MPa were analyzed by Kolmogorov-Smirnov and Levene's tests and by two-way ANOVA and Tukey's post hoc test at a significance level of 5%. RESULTS: Fiber posts cemented using Luting & Lining Cement, Fuji II LC Improved, and Ketac Cem presented the highest bond strength to root dentin, followed by RelyX Luting. Ionoseal presented the lowest bond strength values (P>0.05. The post level did not influence the bond strength of fiber posts to root dentin (P=0.148. The major cause of failure was cohesive at the cement for all GICs and RMGICs. CONCLUSIONS: Except for Ionoseal, all cements provided satisfactory bond strength values.

  4. Effects of Different Environment Temperatures on Some Motor Characteristics and Muscle Strength

    Science.gov (United States)

    Çakir, Ergün; Yüksek, Selami; Asma, Bülent; Arslanoglu, Erkal

    2016-01-01

    The aim of this study was determine the effects of different environment temperatures on motor characteristics and muscle strength. 15 athletes participated to study. Flexibility, vertical jump, hand grip-leg strength, 30m sprint, 20-meter shuttle run and coordination-agility tests were measured in five different environment temperatures. (22°C,…

  5. Bonding Characteristics of Macrosynthetic Fiber in Latex-Modified Fiber-Reinforced Cement Composites as a Function of Carbon Nanotube Content

    Directory of Open Access Journals (Sweden)

    Ji-Hong Jean

    2016-01-01

    Full Text Available The effect of carbon nanotube content (0, 0.5, 1.0, 1.5, and 2.0% of the cement weight on the bonding properties of macrosynthetic fiber in latex-modified hybrid fiber cement-based composites (LMHFRCCs was evaluated. The slump value, compressive strength, and bonding strength were measured for each LMHFRCC. As the carbon nanotube content increased to 1.5%, the bonding properties of the macrosynthetic fiber improved. However, the bonding performance deteriorated at a carbon nanotube content of 2.0%. A decrease in the fluidity of the mix negatively affected the dispersion of the nanotubes in the LMHFRCCs. The addition of carbon nanotubes also affected the relative bonding strength independently of the improvement in compressive strength. Microscopic analysis of the macrosynthetic fiber surfaces was used to understand changes in the bonding behavior.

  6. Characteristics in Paintability of Advanced High Strength Steels

    International Nuclear Information System (INIS)

    Park, Ha Sun

    2007-01-01

    It is expected that advanced high strength steels (AHSS) would be widely used for vehicles with better performance in automotive industries. One of distinctive features of AHSS is the high value of carbon equivalent (Ceq), which results in the different properties in formability, weldability and paintability from those of common grade of steel sheets. There is an exponential relation between Ceq and electric resistance, which seems also to have correlation with the thickness of electric deposition (ED) coat. higher value of Ceq of AHSS lower the thickness of ED coat of AHSS. Some elements of AHSS such as silicon, if it is concentrated on the surface, affect negatively the formation of phosphates. In this case, silicon itself doesn't affect the phosphate, but its oxide does. This phenomenon is shown dramatically in the welding area. Arc welding or laser welding melts the base material. In the process of cooling of AHSS melt, the oxides of Si and Mn are easily concentrated on the surface of boundary between welded and non welded area because Si and Mn cold be oxidized easier than Fe. More oxide on surface results in poor phosphating and ED coating. This is more distinctive in AHSS than in mild steel. General results on paintability of AHSS would be reported, being compared to those of mild steel

  7. Properties and mesostructural characteristics of linen fiber reinforced self-compacting concrete in slender columns

    Directory of Open Access Journals (Sweden)

    Sabry A. Ahmed

    2013-06-01

    Full Text Available In this study the linen fibers were used to reinforce self-compacting concrete (SCC with 2 and 4 kg/m3 contents; then their effects on the fresh and hardened properties of SCC were investigated. Furthermore, three circular slender columns were cast using both plain and linen fiber reinforced (LFR SCC in order to study the variations of hardened properties and mesostructural characteristics along the columns height. The addition of linen fibers to SCC reduced its workability and affected its self-compacting characteristics in a manner depending on the fiber content. Also, noticeable improvement in mechanical properties and slight reduction in unit weight and UPV were recorded. The hardened properties did not vary significantly along the height of columns, however, lower values were observed at the upper end of columns. The aggregate distribution was slightly more homogenous in case of LFRSCC, and the variation of fiber density along the height of columns was relatively high.

  8. Effect of Chicory Fiber and Smoking on Quality Characteristics of Restructured Sausages

    Science.gov (United States)

    Choi, Hyun-Su; Choi, Hyung-Gyu; Choi, Yeong-Seok; Kim, Jong-Hee; Lee, Ju-Ho; Jung, Eun-Hee; Lee, Sang-Hwa; Choi, Yang-Il

    2016-01-01

    This study was conducted to investigate the effects of chicory fiber for the replacement of fat and smoking on quality characteristics of restructured sausages. Treatments were as follows; Control: Pork backfat 20%, T1: Pork backfat 10% + Chicory fiber 10%, T2: Control + Smoking, T3: T1 + Smoking. The addition of chicory fiber significantly reduced the moisture, fat, hardness and pH values, whereas the smoking treatment increased the fat, redness and pH values of restructured sausages (psausages. As a result, although the addition of chicory fiber decreased the quality characteristics of sausage, smoking treatment improved the reduced quality. Therefore, the chicory fiber and smoking treatment is helpful to develop restructured sausage products with reduced fat and compensated quality. PMID:27499674

  9. Evaluation of Variation in Residual Strength of Carbon Fiber Reinforced Plastic Plate with a Hole Subjected to Fatigue Load

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Young; Kang, Min Sung; Koo, Jae Mean; Seok, Chang Sung [Sungkyunkwan University, Seoul (Korea, Republic of)

    2010-10-15

    CFRP (Carbon Fiber Reinforced Plastic) has received considerable attention in various fields as a structural material, because of its high specific strength, high specific stiffness, excellent design flexibility, favorable chemical properties, etc. Most products consisting of several parts are generally assembled by mechanical joining methods (using rivets, bolts, pins, etc.). Holes must be drilled in the parts to be joined, and the strength of the components subjected to static and fatigue loads caused by stress concentration must be decreased. In this study, we experimentally evaluated the variation in the residual strength of a holenotched CFRP plate subjected to fatigue load. We repeatedly subjected the hole-notched specimen to fatigue load for a certain number of cycles, and then we investigated the residual strength of the hole-notched specimen by performing the fracture test. From the results of the test, we can observe the initiation of a directional crack caused by the applied fatigue load. Further, we observed that the residual strength increases with a decrease in the notch effect due to this crack. It was evaluated that the residual strength increases to a certain level and subsequently decreases. This variation in the residual strength was represented by a simple equation by using a model of the decrease in residual strength for plain plate, which was developed by Reifsnider and a stress redistribution model for hole-notched plate, which was developed by Yip.

  10. Polarization characteristics of double-clad elliptical fibers.

    Science.gov (United States)

    Zhang, F; Lit, J W

    1990-12-20

    A scalar variational analysis based on a Gaussian approximation of the fundamental mode of a double-clad elliptical fiber with a depressed inner cladding is studied. The polarization properties and graphic results are presented; they are given in terms of three parameters: the ratio of the major axis to the minor axis of the core, the ratio of the inner cladding major axis to the core major axis, and the difference between the core index and the inner cladding index. The variations of both the spot size and the field intensity with core ellipticity are examined. It is shown that high birefringence and dispersion-free orthogonal polarization modes can be obtained within the single-mode region and that the field intensity distribution may be more confined to the fiber center than in a single-clad elliptical fiber.

  11. Effect OF NaOH Treatment on Bending Strength Of The Polyester Composite Reinforce By Sugar Palm Fibers

    Science.gov (United States)

    Arif Irfai, Mochamad; Wulandari, Diah; Sutriyono; Marsyahyo, Eko

    2018-04-01

    The objective of this research is to investigate the effect of NaOH treatment on bending strength of lamina composite reinforced by sugar palm fiber. To know of mechanism fracture can be done with visual inspection of the fracture surface. The Materials used are random sugar palm fibers that have been in the treatment of NaOH, polyester resin and hardener. Sugar palm fibers after washed and dried then soaked NaOH with a long time soaking 0, 2, 4, 6 and 8 hours. The bending test specimens were produced according to ASTM D 790. All specimens were post cured at 62°C for 4 hours. The Bending test was carried out on a universal testing machine. The SEM analysis has conducted to provide the analysis on interface adhesion between the surfaces of fiber with the matrix. The result shows that polyester composite reinforced by sugar palm fiber has highest bending stress 176.77 N/mm2 for 2 hours of a long time soaking NaOH, the highest flexural strain 0.27 mm for 2 hours of a long time soaking NaOH, elongation 24.05% for 2 hours of a long time soaking NaOH and the highest bending modulus 1.267 GPa for 2 hours of a long time soaking NaOH. Based on the results, it can be concluded that the polyester composite reinforced by sugar palm fiber has the optimum bending properties for a long time soaking 2 hours. The fracture surface shows that the polyester composite reinforced by sugar palm fiber pull out that indicate weakens the bond between fiber and matrix.

  12. Experimental and Numerical Study of the Interfacial Shear Strength in Carbon Fiber/Epoxy Resin Composite under Thermal Loads

    Directory of Open Access Journals (Sweden)

    Hongxiao Wang

    2018-01-01

    Full Text Available This study examined the influence mechanism of temperature on the interfacial shear strength (IFSS between carbon fiber (CF and epoxy resin (EP matrices under various thermal loads using experimental and numerical simulation methods. To evaluate the change in IFSS as a function of the increase in temperature, a microbond test was performed under controlled temperature environment from 23°C to 150°C. The experimental results showed that IFSS values of CF/EP reduce significantly when the temperature reaches near glass transition temperature. To interpret the effect of thermal loads on IFSS, a thermal-mechanical coupling finite element model was used to simulate the process of fiber pull-out from EP. The results revealed that temperature dependence of IFSS is linked to modulus of the matrix as well as to the coefficients of thermal expansion of the fiber and matrix.

  13. In Vitro Evaluation of Various Surface Treatments of Fiber Posts on the Bond Strength to Composite Core

    Directory of Open Access Journals (Sweden)

    Sareh Nadalizadeh

    Full Text Available Introduction: The reliable bond at the root-post-core interface is critical for the clinical success of post-retained restorations. To decrease the risk of fracture, it is important to optimize the adhesion. Therefore, various post surface treatments have been proposed. The purpose of this study was to investigate the influence of various surface treatments of fiber posts on the bond strength to composite core. Materials & Methods: In this study, 40 fiber reinforced posts were used. After preparing and sectioning them, resulting specimens were divided into four groups (N=28. The posts received different surface treatments such as no surface treatment (control group, preparing with hydrogen peroxide 10%, preparing with silane, preparing with HF and silane. Then, posts were tested in micro tensile testing machine. The results were analyzed by One-Way ANOVA and Dunnett T3 test. Results: The greatest bond strength observed was in treatment with hydrogen peroxide 10% (19.84±8.95 MPa, and the lowest strength was related to the control group (12.44±3.40 MPa. The comparison of the groups with Dunnett T3 test showed that the differences between the groups was statistically significant (α=0.05.Conclusion: Based on the results of this study, preparing with H2O2 -10 % and silane increases the bond strength of FRC posts to the composite core more than the other methods. Generally, the bond strength of posts to the composite core increases by surface treatment.

  14. The influence of groundwater flow effect on changes of loess soil strength characteristics

    Directory of Open Access Journals (Sweden)

    Bida S.V.

    2015-09-01

    Full Text Available The problem of stability of slopes - one of the most topical at present. It is proved that the reliability of the slope stability assessment affects the accuracy of the strength characteristics of the soil. One of the most common methods is one-plane shifts method Established that processing of results of soil shift test in logarithmic coordinates can more accurately identify indicators of strength. Discovered that the magnitude of the strength characteristics of soil test results which is obtained on one plane shift depends on the vertical pressure during testing.

  15. Characteristics of upper limb muscular strength in male wheelchair tennis players

    Science.gov (United States)

    Moon, Hyo-Bin; Park, Seung-Jae; Kim, Al-Chan; Jang, Jee-Hun

    2013-01-01

    The purpose of this study was to identify the characteristics of muscular strength in upper limb and to present the preliminary information for development of sports injury prevention program and exercise rehabilitation program in wheelchair tennis players. Participants were 12 male wheelchair tennis players. Muscular strength was measured in shoulder and elbow joints with isokinetic dynamometer. Ipsilateral (IR) and bilateral (BR) balance ratio were calculated with isokinetic strength at 60°/sec. As a result, extension strength (ES) was significantly higher than flexion strength (FS) (Pelbow joint FS was significantly higher than ES (Pelbow joints and lower IR and BR in elbow joints could be the characteristics in male wheelchair tennis players. It is suggested that flexor strengthening program in nondominant shoulder joint, extensor strengthening program in both elbow joint, and flexor strengthening program in non-dominant elbow joint should be introduced for male wheelchair tennis players. PMID:24278887

  16. Bond Characteristics of Macro Polypropylene Fiber in Cementitious Composites Containing Nanosilica and Styrene Butadiene Latex Polymer

    Directory of Open Access Journals (Sweden)

    Jae-Woong Han

    2015-01-01

    Full Text Available This study evaluated the bond properties of polypropylene (PP fiber in plain cementitious composites (PCCs and styrene butadiene latex polymer cementitious composites (LCCs at different nanosilica contents. The bond tests were evaluated according to JCI SF-8, in which the contents of nanosilica in the cement were 0, 2, 4, 6, 8, and 10 wt%, based on cement weight. The addition of nanosilica significantly affected the bond properties between macro PP fiber and cementitious composites. For PCCs, the addition of 0–2 wt% nanosilica enhanced bond strength and interface toughness, whereas the addition of 4 wt% or more reduced bond strength and interface toughness. The bond strength and interfacial toughness of LCCs also increased with the addition of up to 6% nanosilica. The analysis of the relative bond strength showed that the addition of nanosilica affects the bond properties of both PCC and LCC. This result was confirmed via microstructural analysis of the macro PP fiber surface after the bond tests, which revealed an increase in scratches due to frictional forces and fiber tearing.

  17. Gain characteristics of a saturated fiber optic parametric amplifier

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Lorenzen, Michael Rodas; Noordegraaf, Danny

    2008-01-01

    In this work we discuss saturation performance of a fiber optic parametric amplifier. A simple numerical model is described and applied to specific cases. A system experiment using a saturated amplifier illustrates a 4 dB improvement in required signal to noise ratio for a fixed bit error ratio....

  18. Effects of high-intensity physical training on muscle fiber characteristics in poststroke patients

    DEFF Research Database (Denmark)

    Andersen, Jesper Løvind; Jørgensen, Jørgen R.; Zeeman, Peter

    2017-01-01

    INTRODUCTION: Stroke is a leading cause of disability worldwide. High-intensity physical training can improve muscle strength and gait speed, but adaptive mechanisms at the muscle cellular level are largely unknown. METHODS: Outpatients with poststroke hemiparesis participated in a 3-month...... rehabilitation program combining high-intensity strength and body-weight supported treadmill-training. Biopsies sampled bilaterally from vastus lateralis muscles, before, after, and at 1-year follow-up after intervention, were analyzed for fiber size, type, and capillarization. RESULTS: At baseline, paretic...... lower limbs had smaller muscle fiber size and lower type I and IIA and higher type IIX percentages than nonparetic lower limbs. Paretic lower limbs had increased type IIA fibers after training. At follow-up, no difference between the lower limbs remained. CONCLUSIONS: Although high-intensity training...

  19. Differences in interfacial bond strengths of graphite fiber-epoxy resin composites

    Science.gov (United States)

    Needles, H. L.

    1985-01-01

    The effect of epoxy-size and degree of cure on the interfacial bonding of an epoxy-amine-graphite fiber composite system is examined. The role of the fiber-resin interface in determining the overall mechanical properties of composites is poorly understood. A good interfacial adhesive bond is required to achieve maximum stress transfer to the fibers in composites, but at the same time some form of energy absorbing interfacial interaction is needed to achieve high fracture toughening. The incompatibility of these two processes makes it important to understand the nature and basic factors involved at the fiber-resin interface as stress is applied. The mechanical properties including interlaminar shear values for graphite fiber-resin composites are low compared to glass and boron-resin composites. These differences have been attributed to poor fiber-matrix adhesion. Graphite fibers are commonly subjected to post-treatments including application of organic sizing in order to improve their compatibility with the resin matrix and to protect the fiber tow from damage during processing and lay-up. In such processes, sized graphite fiber tow is impregnated with epoxy resin and then layed-up i nto the appropriate configuration. Following an extended ambient temperature cure, the graphite-resin composite structure is cured at elevated temperature using a programmed temperature sequence to cure and then cool the product.

  20. Impact strength and flexural properties enhancement of methacrylate silane treated oil palm mesocarp fiber reinforced biodegradable hybrid composites.

    Science.gov (United States)

    Eng, Chern Chiet; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Ariffin, Hidayah; Yunus, Wan Md Zin Wan

    2014-01-01

    Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites.

  1. RELATIONSHIP BETWEEN ISOKINETIC KNEE STRENGTH AND JUMP CHARACTERISTICS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION.

    Science.gov (United States)

    Laudner, Kevin; Evans, Daniel; Wong, Regan; Allen, Aaron; Kirsch, Tom; Long, Brian; Meister, Keith

    2015-06-01

    Clinicians are often challenged when making return-to-play decisions following anterior cruciate ligament reconstruction (ACL-R). Isokinetic strength and jump performance testing are common tools used to make this decision. Unfortunately, vertical jump performance standards have not been clearly established and many clinicians do not have access to isokinetic testing equipment. To establish normative jump and strength characteristics in ACL-R patients cleared by an orthopedic physician to return-to-play and to determine if relationships exist between knee isokinetic strength measurements and jump characteristics described using an electronic jump map system. Descriptive laboratory study. Thirty-three ACL-R patients who had been cleared to return to athletic competition participated in this study. Twenty-six of these ACL-R participants were also matched to 26 asymptomatic athletes based on sex, limb, height, and mass to determine isokinetic strength and jump characteristic differences between groups. Jump tests consisted of single leg vertical, double leg vertical, and a 4-jump single leg vertical jump assessed using an electronic jump mat system. Independent t-tests were used to determine differences between groups and multiple regression analyses were used to identify any relationships between jump performance and knee strength (pjump capabilities and some bilateral knee strength deficiencies compared to the matched control group. The ACL-R group also showed several moderate-to-strong positive relationships for both knee extension and flexion strength with several jump performance characteristics, such as single and double leg vertical jump height. The current results indicate that ACL-R patients present with several knee strength and vertical jump differences compared to a matched control group at the time of return-to-play. Also, ACL-R patient's performance on an electronic jump mat system is strongly related to isokinetic knee strength measures. 2b.

  2. Steel fiber reinforced concrete

    International Nuclear Information System (INIS)

    Baloch, S.U.

    2005-01-01

    Steel-Fiber Reinforced Concrete is constructed by adding short fibers of small cross-sectional size .to the fresh concrete. These fibers reinforce the concrete in all directions, as they are randomly oriented. The improved mechanical properties of concrete include ductility, impact-resistance, compressive, tensile and flexural strength and abrasion-resistance. These uniqlte properties of the fiber- reinforcement can be exploited to great advantage in concrete structural members containing both conventional bar-reinforcement and steel fibers. The improvements in mechanical properties of cementitious materials resulting from steel-fiber reinforcement depend on the type, geometry, volume fraction and material-properties of fibers, the matrix mix proportions and the fiber-matrix interfacial bond characteristics. Effects of steel fibers on the mechanical properties of concrete have been investigated in this paper through a comprehensive testing-programme, by varying the fiber volume fraction and the aspect-ratio (Lid) of fibers. Significant improvements are observed in compressive, tensile, flexural strength and impact-resistance of concrete, accompanied by marked improvement in ductility. optimum fiber-volume fraction and aspect-ratio of steel fibers is identified. Test results are analyzed in details and relevant conclusions drawn. The research is finally concluded with future research needs. (author)

  3. Effects of strength training on muscle fiber types and size; consequences for athletes training for high-intensity sport

    DEFF Research Database (Denmark)

    Andersen, J L; Aagaard, P

    2010-01-01

    Training toward improving performance in sports involving high intense exercise can and is done in many different ways based on a mixture of tradition in the specific sport, coaches' experience and scientific recommendations. Strength training is a form of training that now-a-days have found its...... way into almost all sports in which high intense work is conducted. In this review we will focus on a few selected aspects and consequences of strength training; namely what effects do strength training have of muscle fiber type composition, and how may these effects change the contractile properties...... functional training advises can be made. Thus, more than a review in the traditional context this review should be viewed upon as an attempt to bring sports-physiologists and coaches or others working directly with the athletes together for a mutual discussion on how recently acquired physiological knowledge...

  4. Effects of strength training on muscle fiber types and size; consequences for athletes training for high-intensity sport

    DEFF Research Database (Denmark)

    Andersen, J L; Aagaard, P

    2010-01-01

    way into almost all sports in which high intense work is conducted. In this review we will focus on a few selected aspects and consequences of strength training; namely what effects do strength training have of muscle fiber type composition, and how may these effects change the contractile properties......Training toward improving performance in sports involving high intense exercise can and is done in many different ways based on a mixture of tradition in the specific sport, coaches' experience and scientific recommendations. Strength training is a form of training that now-a-days have found its...... functional training advises can be made. Thus, more than a review in the traditional context this review should be viewed upon as an attempt to bring sports-physiologists and coaches or others working directly with the athletes together for a mutual discussion on how recently acquired physiological knowledge...

  5. THE IMPACT OF ANTHROPOMETRIC CHARACTERISTICS ON MANIFESTATION OF EXPLOSIVE STRENGTH IN VOLLEYBALL PLAYERS AGED 13 YEARS

    Directory of Open Access Journals (Sweden)

    Goran Nesic

    2006-04-01

    Full Text Available With the aim to investigate the plyometric training model used for the increase of explosive strength type (the vertical jump, an experimental research was carried out, drawing a sample of 40 volleyball players at the cadet level. For the purpose of this research, we applied nine anthropometric characteristics, which made the predictor system of variables. For the assessment of explosive strength, three tests were performed. The data were processed by descriptive and regression analyses. Based on the findings of the research and the discussion, one could unfailingly conclude that the applied system of anthropometric characteristics, as a predictor, has a significant impact on manifestation of explosive strength in volleyball players, aged 13 years, that is, it is possible to predict results of the tests of explosive strength based on the measures of anthropometric status of examinees.

  6. Enrichment of probiotic ice cream with different dietary fibers: Structural characteristics and culture viability.

    Science.gov (United States)

    Akalın, A S; Kesenkas, H; Dinkci, N; Unal, G; Ozer, E; Kınık, O

    2018-01-01

    This study evaluated the effect of 5 dietary fibers (apple, orange, oat, bamboo, and wheat) on the physicochemical, rheological, and textural characteristics; sensory properties; and culture viability of probiotic ice cream stored at -18°C for 180 d. The presence of orange and apple fibers increased the titratable acidity, decreased the lightness (color) value of the ice creams, and enhanced the red and yellow coloration. Compared with the control sample, the consistency indices and apparent viscosities of the experimental samples increased with the addition of all dietary fibers except oat fiber. The highest viscosity was obtained in the sample fortified with apple fiber, whereas the ice cream containing orange fiber showed the highest hardness after d 60 of storage. The addition of orange and apple fibers significantly increased melting resistance; however, panelists did not generally like these samples in terms of taste-flavor. All ice creams had viable counts of Lactobacillus acidophilus of ≥7 log cfu/g during storage except the samples with orange and bamboo fiber. Bifidobacterium lactis counts were also found to be >6 log cfu/g in those samples until d 150 of storage. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  7. Nanostructural Characteristics and Interfacial Properties of Polymer Fibers in Cement Matrix.

    Science.gov (United States)

    Shalchy, Faezeh; Rahbar, Nima

    2015-08-12

    Concrete is the most used material in the world. It is also one of the most versatile yet complex materials that humans have used for construction. However, an important weakness of concrete (cement-based composites) is its low tensile properties. Therefore, over the past 30 years many studies were focused on improving its tensile properties using a variety of physical and chemical methods. One of the most successful attempts is to use polymer fibers in the structure of concrete to obtain a composite with high tensile strength and ductility. The advantages of polymer fiber as reinforcing material in concrete, both with regard to reducing environmental pollution and the positive effects on a country's economy, are beyond dispute. However, a thorough understanding of the mechanical behavior of fiber-reinforced concrete requires a knowledge of fiber/matrix interfaces at the nanoscale. In this study, a combination of atomistic simulations and experimental techniques has been used to study the nanostructure of fiber/matrix interfaces. A new model for calcium-silicate-hydrate (C-S-H)/fiber interfaces is also proposed on the basis of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. Finally, the adhesion energy between the C-S-H gel and three different polymeric fibers (poly(vinyl alcohol), nylon-6, and polypropylene) were numerically studied at the atomistic level because adhesion plays a key role in the design of ductile fiber-reinforced composites. The mechanisms of adhesion as a function of the nanostructure of fiber/matrix interfaces are further studied and discussed. It is observed that the functional group in the structure of polymer macromolecule affects the adhesion energy primarily by changing the C/S ratio of the C-S-H at the interface and by absorbing additional positive ions in the C-S-H structure.

  8. Assessment of strength characteristics of Al2024 ECAP metal using small punch testing

    International Nuclear Information System (INIS)

    Ma, Young Wha; Choi, Jeong Woo; Yoon, Kee Bong; Kim, Seon Hwa

    2006-01-01

    When subjected to severe shear deformation by ECAP, microstructure of Al2024 becomes extremely refined. To measure the strength of that, Small Punch(SP) testing method was adopted as a substitute for the conventional uniaxial tensile testing because the size of material processed by ECAP were limited to ψ12 mm in transverse direction. SP tests were performed with specimens in longitudinal and transverse directions of Al2024 ECAP metal. For comparing the strength values with those assessed by SP tests, uniaxial tensile tests were also conducted with specimens in longitudinal direction. Failure surfaces of the tested SP specimens showed that failure mode was shear deformation and Al2024 ECAP metal has an anisotropy in strength. Thus, conventional equations proposed for assessing the strength characteristics were improper to assess those of Al2024 ECAP metal. In this paper a way of assessing the strength of Al2024 ECAP metal was proposed and was proven to be effective

  9. Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide.

    Science.gov (United States)

    Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

    2013-05-10

    Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents.

  10. Physical and Mechanical Characteristics of Kevlar Fiber-Reinforced PC/ABS Composites

    Directory of Open Access Journals (Sweden)

    Kuljira Sujirote

    2012-01-01

    Full Text Available In this research, the composites between polycarbonate (PC and acrylonitrile-butadiene-styrene (ABS alloy and Kevlar fiber were prepared. The flexural and tensile properties of PC/ABS alloy and its composites were determined using a universal testing machine. The synergistic behavior of flexural modulus was observed for all regions of PC contents, while the synergism of flexural strength and tensile strength were found in some PC contents. It was found that the optimum weight ratio of PC:ABS was 60:40. In the Kevlar Fiber-reinforced PC/ABS composite system at PC:ABS of 60:40, both flexural modulus and strength were increased with matrix contents. Additionally, the flexural strength drastically increased with the matrix content and then reached the maximum value of 167 MPa at the matrix content of 33.4 wt%. The results from peel test, water contact measurement, and scanning electron microscopy (SEM reveal that the interfacial adhesion between the Kevlar fiber and the polymer matrix could be improved by increasing the PC content in the matrix.

  11. Residual stress effects on the impact resistance and strength of fiber composites

    Science.gov (United States)

    Chamis, C. C.

    1973-01-01

    Equations have been derived to predict degradation effects of microresidual stresses on impact resistance of unidirectional fiber composites. Equations also predict lamination residual stresses in multilayered angle ply composites.

  12. EFFECT OF ELEVATED TEMPERATURE ON COMPRESSIVE STRENGTH OF FIBER REINFORCED CONCRETE

    OpenAIRE

    Prashant shinkar*, Prof. Deepak kakade, Dr.A.P.Wadekar

    2017-01-01

    This paper deals with the mechanical properties of concrete with steel fibers subjected to temperatures up to 500°C. Now a day concrete are being used extensively in the construction that might be subjected to elevated temperatures. The behavior of concrete structures at elevated temperatures is of significant importance in predicting the safety of structures in response to certain accidents or particular service conditions. Concrete mixes of M 50 have been designed along with steel fibers fr...

  13. Extraction and characterization of Retama monosperma fibers | Aizi ...

    African Journals Online (AJOL)

    The Young's modulus was 13.3 GPa, tensile strength was 110 MPa and density was 1.3 g/cm3. The average fiber length was 155.7 mm. The fibers yield and characteristics showed that R. monosperma plant may in future be suitable source for natural fibers. Key words: Retama monosperma young stems, fibers, extraction, ...

  14. Optimizing the Flexural Strength of Beams Reinforced with Fiber Reinforced Polymer Bars Using Back-Propagation Neural Networks

    Directory of Open Access Journals (Sweden)

    Bahman O. Taha

    2015-06-01

    Full Text Available The reinforced concrete with fiber reinforced polymer (FRP bars (carbon, aramid, basalt and glass is used in places where a high ratio of strength to weight is required and corrosion is not acceptable. Behavior of structural members using (FRP bars is hard to be modeled using traditional methods because of the high non-linearity relationship among factors influencing the strength of structural members. Back-propagation neural network is a very effective method for modeling such complicated relationships. In this paper, back-propagation neural network is used for modeling the flexural behavior of beams reinforced with (FRP bars. 101 samples of beams reinforced with fiber bars were collected from literatures. Five important factors are taken in consideration for predicting the strength of beams. Two models of Multilayer Perceptron (MLP are created, first with single-hidden layer and the second with two-hidden layers. The two-hidden layer model showed better accuracy ratio than the single-hidden layer model. Parametric study has been done for two-hidden layer model only. Equations are derived to be used instead of the model and the importance of input factors is determined. Results showed that the neural network is successful in modeling the behavior of concrete beams reinforced with different types of (FRP bars.

  15. Effect of neutron irradiation on the dimension and the strength of carbon fiber/carbon composite derived from thermosetting resin precursor

    International Nuclear Information System (INIS)

    Yasuda, Eiichi; Tanabe, Yasuhiro; Kimura, Shiushichi; Maruyama, Tadashi; Iseki, Takayoshi; Yano, Toyohiko.

    1988-01-01

    Unidirectionally reinforced carbon fiber/carbon composite whose matrix was derived from thermosetting resin, was prepared. The heat-treatment temperature was 2800 deg C. The change in size and 4 point bending strength of the composite was measured after neutron irradiation (640 deg C, 6 x 10 24 n/m 2 , E > 1 MeV). Shrinkage in normal to the fiber direction was larger than that in fiber direction. Increase in strength and Young's modulus of the composite was observed after irradiation. Irradiated composite showed much higher deflection to fracture than unirradiated one. (author)

  16. Characteristic Analysis Light Intensity Sensor Based On Plastic Optical Fiber At Various Configuration

    Science.gov (United States)

    Arifin, A.; Lusiana; Yunus, Muhammad; Dewang, Syamsir

    2018-03-01

    This research discusses the light intensity sensor based on plastic optical fiber. This light intensity sensor is made of plastic optical fiber consisting of two types, namely which is cladding and without cladding. Plastic optical fiber used multi-mode step-index type made of polymethyl metacrylate (PMMA). The infrared LED emits light into the optical fiber of the plastic and is subsequently received by the phototransistor to be converted to an electric voltage. The sensor configuration is made with three models: straight configuration, U configuration and gamma configuration with cladding and without cladding. The measured light source uses a 30 Watt high power LED with a light intensity of 0 to 10 Klux. The measured light intensity will affect the propagation of light inside the optical fiber sensor. The greater the intensity of the measured light, the greater the output voltage that is read on the computer. The results showed that the best optical fiber sensor characteristics were obtained in U configuration. Sensors with U-configuration without cladding had the best sensitivity and resolution values of 0.0307 volts/Klux and 0.0326 Klux. The advantages of this measuring light intensity based on the plastic optical fiber instrument are simple, easy-to-make operational systems, low cost, high sensitivity and resolution.

  17. Modification of Oil Palm Mesocarp Fiber Characteristics Using Superheated Steam Treatment

    Directory of Open Access Journals (Sweden)

    Subbian Karuppuchamy

    2013-07-01

    Full Text Available In this study, oil palm mesocarp fiber (OPMF was treated with superheated steam (SHS in order to modify its characteristics for biocomposite applications. Treatment was conducted at temperatures 190–230 °C for 1, 2 and 3 h. SHS-treated OPMF was evaluated for its chemical composition, thermal stability, morphology and crystallinity. OPMF treated at 230 °C exhibited lower hemicellulose content (9% compared to the untreated OPMF (33%. Improved thermal stability of OPMF was found after the SHS treatment. Moreover, SEM and ICP analyses of SHS-treated OPMF showed that silica bodies were removed from OPMF after the SHS treatment. XRD results exhibited that OPMF crystallinity increased after SHS treatment, indicating tougher fiber properties. Hemicellulose removal makes the fiber surface more hydrophobic, whereby silica removal increases the surface roughness of the fiber. Overall, the results obtained herewith suggested that SHS is an effective treatment method for surface modification and subsequently improving the characteristics of the natural fiber. Most importantly, the use of novel, eco-friendly SHS may contribute to the green and sustainable treatment for surface modification of natural fiber.

  18. Strength characteristics of lightly solidified dredged marine clay admixed with bentonite

    Science.gov (United States)

    Ariffin, Syazwana Tajul; Chan, Chee-Ming

    2017-11-01

    Strength characteristic is a significant parameter in measuring the effect of soil improvement and effective composition of solidification. In this study, the dredged marine sediment (DMS) collected from Kuala Perlis (Malaysia) was examined to determine its strength characteristics under light cement solidification with bentonite. Dredged marine clay generally has the low shear strength and high void ratio, and consists mainly of soil particles of the fine-grained type. As a discarded geo-waste, it can be potentially treated to for reuse as a backfill material instead of being disposed of, hence reducing the negative impact on the environment. Physico-chemical parameters of the dredged sample were first determined, then solidification was carried out to improve the engineering properties by admixing ordinary Portland cement (OPC) as the binder and bentonite as a volume enhancer to the soil. The DMS was treated with the addition of 3 % and 6 % cement and bentonite within the range of 0-30 %. The specimens were cured at room temperature for 3, 7 and 14 days. The strength gain was measured by unconfined compression test and vane shear test. The laboratory test results were analyzed to establish the relationship between strength properties and solidification specifications. In summary, the strength of specimens increased with the increase of the quantity of bentonite and cement to get the effective composition of the specimen.

  19. Tapered optical fibers as tools for probing magneto-optical trap characteristics

    International Nuclear Information System (INIS)

    Morrissey, Michael J.; Deasy, Kieran; Wu Yuqiang; Nic Chormaic, Sile; Chakrabarti, Shrabana

    2009-01-01

    We present a novel technique for measuring the characteristics of a magneto-optical trap (MOT) for cold atoms by monitoring the spontaneous emission from trapped atoms coupled into the guided mode of a tapered optical nanofiber. We show that the nanofiber is highly sensitive to very small numbers of atoms close to its surface. The size and shape of the MOT, determined by translating the cold atom cloud across the tapered fiber, is in excellent agreement with measurements obtained using the conventional method of fluorescence imaging using a charge coupled device camera. The coupling of atomic fluorescence into the tapered fiber also allows us to monitor the loading and lifetime of the trap. The results are compared to those achieved by focusing the MOT fluorescence onto a photodiode and it was seen that the tapered fiber gives slightly longer loading and lifetime measurements due to the sensitivity of the fiber, even when very few atoms are present.

  20. Parametric methods of describing and extrapolating the characteristics of long-term strength of refractory materials

    International Nuclear Information System (INIS)

    Tsvilyuk, I.S.; Avramenko, D.S.

    1986-01-01

    This paper carries out the comparative analysis of the suitability of parametric methods for describing and extrapolating the results of longterm tests on refractory materials. Diagrams are presented of the longterm strength of niobium based alloys tested in a vacuum of 1.3 X 10 -3 Pa. The predicted values and variance of the estimate of endurance of refractory alloys are presented by parametric dependences. The longterm strength characteristics can be described most adequately by the Manson-Sakkop and Sherby-Dorn methods. Several methods must be used to ensure the reliable extrapolation of the longterm strength characteristics to the time period an order of magnitude longer than the experimental data. The most suitable method cannot always be selected on the basis of the correlation ratio

  1. Electrochemical behaviour and nanoscale characteristics of CNT-based fibers as new substrate for cell growth

    Energy Technology Data Exchange (ETDEWEB)

    Polizu, S.; Yahia, L.H. [Ecole Polytechnique de Montreal, PQ (Canada). Laboratoire d' innovation et d' analyse de la bioperformance; Savadogo, O. [Ecole Polytechnique de Montreal, Montreal, PQ (Canada). Laboratoire de nouveaux materiaux pour l' energie et l' electrochimie; Maugey, M.; Poulin, P. [Centre de Recherche Paul Pascal, CNRS, Bordeaux (France); Rouabhia, M. [Laval Univ., Quebec City, PQ (Canada). Faculty of Medicine

    2008-07-01

    This paper reported on a study in which carbon nanotube (CNT) macroscopic fibers were formulated by a newly developed non-covalent method for fabricating fibrous substrate. The covalent and noncovalent chemistry of CNTs has been widely used in the development of CNT-based biomaterials as active substrates for living cells. Time of Flight Mass Spectroscopy (TOF-SIMS) analysis was used to determine the surface characteristics of the CNT-based fibers produced by wet spinning method. The structure and texture of fibers were imaged using Low-Vacuum Scanning Electron Microscopy (LV-SEM) equipped with an Energy Dispersive Spectrometer (EDS) for microanalysis. Atomic Force Microscopy (AFM) imaging revealed the structure of fibers. Cyclic Voltametry (CV) measurements were performed to examine the electrochemical behaviour of fibers. Sulfuric acid and a cell culture medium was used as the 2 different electrolytes. The influences of environmental parameters on the electrochemical phenomena taking place were identified. The intrinsic electrochemical characteristics of fibers were revealed through measurements in acid environment. The cell culture medium simulated the physiological conditions. It was concluded that the newly developed wet spinning method is very efficient for making CNT-based fibers as electroactive biomaterials. The structural nanoscale details evidenced a good alignment of nanotubes in the thread and the critical role it plays in electrochemical interactions. The differences induced by the variation of electrolytes suggest that a relationship could be established between the fiber chemistry and the electrochemical response. This correlation has considerably potential for the design of new biomedical devices. 2 refs.

  2. Effect of resin cement, aging process and root level on the bond strength of the resin-fiber posts

    Science.gov (United States)

    Almuhim, Khalid Salman

    Background. Little is known about the long-term clinical bonding effectiveness of the Fiber-reinforced composite (FRC) posts cemented with self-etch adhesive systems. Bond stability and longevity of the cemented post are adversely affected by physical and chemical factors over time, such as expansion and contraction stresses caused by thermal changes and occlusal load. This clinical condition can be simulated in vitro by thermocyclic loading; and bonding effectiveness can be evaluated by applying the micropush out test. Therefore, more in vitro studies are needed to evaluate the bond strength of the fiber posts cemented with different resin cement systems after simulating the artificial aging induced by thermocycling. The aim of this study was to compare the microtensile bond strength of two different resin cement systems (total etch, and self-etch resin cement system) used for cementation of fiber reinforced composite posts in three different aging periods using thermocycling. Methods. Following IRB approval, sixty freshly extracted bicuspid single rooted natural teeth were endodontically treated, and the post-spaces were prepared to receive a fiber-post cemented with either a total etch resin cement (Rely-X Ultimate) or with a self-etch resin cement (Rely-X Unicem). No thermocycling, 20,000 and 40,000 cycles was used to age the specimens. Teeth were randomly allocated into six different groups: G1 - Control: Rely-X Ultimate cement with no thermocycling. G2: Rely-X Ultimate cement with 20,000 thermocycling. G3: Rely-X Ultimate cement with 40,000 thermocycling. G4: Rely-X Unicem cement. G5: Rely-X Unicem cement. G6: Rely-X Unicem cement. Microtensile bond strength determined using a micropush out test on a universal testing machine (MTS). Additionally, the failure mode of each specimen was observed under a stereomicroscope (Olympus) at 40x magnification. Finally, one representative sample was randomly selected from each of the five failure modes for scanning

  3. Comparison of Speed, Agility, Anaerobic Strength and Anthropometric Characteristics in Male Football and Futsal Players

    Science.gov (United States)

    Kartal, Resat

    2016-01-01

    The purpose of this study is to compare speed, agility, anaerobic strength and some anthropometric characteristics in male football and futsal players. The sample of the study is composed of male futsal team players of Aydin Adnan Menderes University (19-24 aged) (n = 12) and Aydin Merkez Yeniköy Football Club players (19-24 aged) (n = 12). Within…

  4. Hollow-fiber membrane bioreactor for the treatment of high-strength landfill leachate

    KAUST Repository

    Rizkallah, Marwan; El-Fadel, Mutasem E.; Saikaly, Pascal; Ayoub, George M.; Darwiche, Nadine D.; Hashisho, Jihan

    2013-01-01

    -fiber MBR. For this purpose, a laboratory-scale MBR was constructed and operated to treat leachate with a chemical oxygen demand (COD) of 9000-11,000 mg/l, a 5-day biochemical oxygen demand (BOD5) of 4000-6,000 mg/l, volatile suspended solids (VSS) of 300

  5. A meso-scale model to study the compressive strength of woven carbon fiber reinforced plastics

    NARCIS (Netherlands)

    Schormans, J.M.J.; Remmers, J.J.C.; Wilson, W.; Deshpande, V.S.

    2016-01-01

    Modeling kink-band formation in woven composites using a detailed micro-model is numerically expensive. In order to reduce the computational resources, a method to homogenize fiber-tows is proposed which uses a rules of mixture approach. The method is tested by comparing the stiffness and

  6. Improved strength of silk fibers in Bombyx mori trimolters induced by an anti-juvenile hormone compound.

    Science.gov (United States)

    Guo, Kaiyu; Dong, Zhaoming; Zhang, Yan; Wang, Dandan; Tang, Muya; Zhang, Xiaolu; Xia, Qingyou; Zhao, Ping

    2018-05-01

    Bombyx mori silk fibers with thin diameters have advantages of lightness and crease-resistance. Many studies have used anti-juvenile hormones to induce trimolters in order to generate thin silk; however, there has been comparatively little analysis of the morphology, structure and mechanical properties of trimolter silk. This study induced two kinds of trimolters by appling topically anti-juvenile hormones and obtained thin diameter silk. Scanning electron microscope (SEM), FTIR analysis, tensile mechanical testing, chitin staining were used to reveal that the morphology, conformation and mechanical property of the trimolter silk. Cocoon of trimolters were highly densely packed by thinner fibers and thus had small apertures. We found that the conformation of trimolter silk fibroin changed and formed more β-sheet structures. In addition, analysis of mechanical parameters yielded a higher Young's modulus and strength in trimolter silk than in the control. By chitin staining of silk gland, we postulated that the mechanical properties of trimolters' silk was enhanced greatly during to the structural changes of silk gland. We induced trimolters by anti-juvenile hormones and the resulting cocoons were more closely packed and had smaller silk fiber diameters. We found that the conformation of trimolters silk fibroin had a higher content of β-sheet structures and better mechanical properties. Our study revealed the structures and mechanical properties of trimolter silk, and provided a valuable reference to improve silk quality by influencing molting in silkworms. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Effect of Anatomical Customization of the Fiber Post on the Bond Strength of a Self-Adhesive Resin Cement.

    Science.gov (United States)

    Rocha, Adricyla Teixeira; Gonçalves, Leticia Machado; Vasconcelos, Ana Júlia de Carvalho; Matos Maia Filho, Etevaldo; Nunes Carvalho, Ceci; De Jesus Tavarez, Rudys Rodolfo

    2017-01-01

    The aim of the study was to evaluate, by means of the push-out test, the effect of the anatomical customization of the fiber post on the bond strength of a self-adhesive resin cement. Twelve endodontically treated, human, upper central incisors were randomly divided into two groups ( n = 6): control (glass fiber posts cemented with Relyx® U200) and customized (glass fiber posts anatomically customized with translucent composite resin cemented with Relyx U200). The roots were sectioned into three slices, cervical, middle, and apical, and photographed with a digital camera attached to a stereomicroscopic loupe. The images were analyzed by software, for evaluation of the cement line. The slices were subsequently submitted to the push-out test until the post had completely extruded, and the fracture mode was analyzed with a stereomicroscopic loupe. The results showed significant differences between the groups in the different root thirds in relation to the area occupied by air bubbles ( p customized group. The customized group showed greater bond resistance than the control group and a more uniform cement layer.

  8. [Influence of retainer design on fixation strength of resin-bonded glass fiber reinforced composite fixed cantilever dentures].

    Science.gov (United States)

    Petrikas, O A; Voroshilin, Iu G; Petrikas, I V

    2013-01-01

    Fiber-reinforced composite (FRC) fixed partial dentures (FPD) have become an accepted part of the restorative dentist's armamentarium. The aim of this study was to evaluate in vitro the influence of retainer design on the strength of two-unit cantilever resin-bonded glass FRC-FPDs. Four retainer designs were tested: a dual wing, a dual wing + horizontal groove, a dual wing + occlusal rest and a step-box. Of each design on 7 human mandibular molars, FRC-FPDs of a premolar size were produced. The FRC framework was made of resin Revolution (Kerr) impregnated glass fibers (GlasSpan, GlasSpan) and veneered with hybrid resin composite (Charisma, Kulzer). Revolution (Kerr) was used as resin luting cement. FRC-FPDs were loaded to failure in a universal testing machine. T (Student's)-test was used to evaluate the data. The four designs were analyzed with finite element analysis (FEA) to reveal the stress distribution within the tooth/restoration complex. Significantly lower fracture strengths were observed with inlay-retained FPDs (step-box: 172±11 N) compared to wing-retained FPDs (poptimal design for replacement of a single premolar by means of a two-unit cantilever FRC-FPDs.

  9. Sensing characteristics of nanocrystalline bismuth oxide clad-modified fiber optic gas sensor

    Science.gov (United States)

    Manjula, M.; Karthikeyan, B.; Sastikumar, D.

    2017-08-01

    Gas sensing properties of nanocrystalline bismuth oxide clad - modified fiber optic sensor is reported for ammonia, ethanol, methanol and acetone gasses at room temperature. The output of sensor increases or decreases for certain gasses when the concentration of the gas is increased. The sensor exhibits high response and good selectivity to methanol gas. Time response characteristics of the sensor are also reported.

  10. Analysis of the characteristics of a two-fiber sensor for monitorship of a turbid medium

    International Nuclear Information System (INIS)

    Zaccanti, G.; Bruscaglioni, P.; Luzi, G.

    1987-01-01

    Certain characteristics of a two-fiber sensor device, of the type proposed by Papa et al. for sea water turbidity monitorship, are examined. The extension of medium from which most of the received backscattered power originates is investigated, together with possible effects of multiple scattering on the received power

  11. Thermal characteristics of carbon fiber reinforced epoxy containing multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Jin-woo Lee

    2018-06-01

    Full Text Available The material with irregular atomic structures such as polymer material exhibits low thermal conductivity because of the complex structural properties. Even materials with same atomic configurations, thermal conductivity may be different based on their structural properties. It is expected that nanoparticles with conductivity will change non-conductive polymer base materials to electrical conductors, and improve the thermal conductivity even with extremely small filling amount. Nano-composite materials contain nanoparticles with a higher surface ratio which makes the higher interface percentage to the total surface of nanoparticles. Therefore, thermal resistance of the interface becomes a dominating factor determines the effective thermal conductivity in nano-composite materials. Carbon fiber has characteristic of resistance or magnetic induction and Also, Carbon nanotube (CNT has electronic and thermal property. It can be applied for heating system. These characteristic are used as heating composite. In this research, the exothermic characteristics of Carbon fiber reinforced composite added CNT were evaluated depend on CNT length and particle size. It was found that the CNT dispersed in the resin reduces the resistance between the interfaces due to the decrease in the total resistance of the heating element due to the addition of CNTs. It is expected to improve the life and performance of the carbon fiber composite material as a result of the heating element resulting from this paper. Keywords: Carbon Nanotube (CNT, Carbon Fiber Reinforcement Plastic (CFRP, Heater, Exothermic characteristics

  12. A study on damage and fatigue characteristics of plain woven carbon fiber reinforced composite material(I)

    International Nuclear Information System (INIS)

    Kim, Kwang Soo; Kim, Sang Tae

    1993-01-01

    The characteristics of damage and fatigue subjected to tensile fatigue loading in plain woven carbon fiber reinforced composite material were studied. Constant amplitude load of 90% stress of notch strength was applied to each specimen, which had different initial notch length, and crack dectectvie compliance curve was determined form load-displacement data. The effective crack length(a eff ) was obtained form this compliance curve and the effective crack growth could be divided to three-steps and explained separately. After cycling the shape of fatigue crack was observed by S.E.M.. Change of elastic modulus(E N ) during fatigue cycle was explained by repeated sudden-death medel. The material constant determined by Jen-Hsu model was more useful to evaluate damage than Wang-Chim model. (Author)

  13. Advanced Backcross QTL Analysis of Fiber Strength and Fineness in a Cross between Gossypium hirsutum and G. mustelinum

    Directory of Open Access Journals (Sweden)

    Baohua Wang

    2017-10-01

    Full Text Available The molecular genetic basis of cotton fiber strength and fineness in crosses between Gossypium mustelinum and Gossypium hirsutum (Upland cotton was dissected using 21 BC3F2 and 12 corresponding BC3F2:3 and BC3F2:4 families. The BC3F2 families were genotyped with simple sequence repeat markers from a G. hirsutum by G. mustelinum linkage map, and the three generations of BC3-derived families were phenotyped for fiber strength (STR and fineness (Micronaire, MIC. A total of 42 quantitative trait loci (QTLs were identified through one-way analysis of variance, including 15 QTLs for STR and 27 for MIC, with the percentage of variance explained by individual loci averaging 13.86 and 14.06%, respectively. Eighteen of the 42 QTLs were detected at least twice near the same markers in different generations/families or near linked markers in the same family, and 28 of the 42 QTLs were identified in both mixed model-based composite interval mapping and one-way variance analyses. Alleles from G. mustelinum increased STR for eight of 15 and reduced MIC for 15 of 27 QTLs. Significant among-family genotypic effects (P < 0.001 were detected in 13 and 10 loci for STR and MIC respectively, and five loci showed significant (P < 0.001 genotype × family interaction for MIC. These results support the hypothesis that fiber quality improvement for Upland cotton could be realized by introgressing G. mustelinum alleles although complexities due to the different effects of genetic background on introgressed chromatin might be faced. Building on prior work with G. barbadense, G. tomentosum, and G. darwinii, QTL mapping involving introgression of G. mustelinum alleles offers new allelic variation to Upland cotton germplasm.

  14. Modeling the characteristic of the optical wavelength discriminator with fiber Bragg grating

    Science.gov (United States)

    Sikora, Aleksandra

    2017-08-01

    Using the transfer matrix method, the influence of fiber Bragg gratings' (FBG) characteristics on the optical wavelength discriminator characteristics was analyzed. The wavelength discriminator forms FBG and cooperates with the identical FBG sensor. The calculation was made for uniform and chirped FBGs. The comparison of the discriminators processing range measurement was analyzed. Presented results are crucial while choosing parameters of FBG used in constructing optical wavelength discriminators for strain and pressure sensor.

  15. Hydrodynamic Characteristics and Strength Analysis of a Novel Dot-matrix Oscillating Wave Energy Converter

    Science.gov (United States)

    Shao, Meng; Xiao, Chengsi; Sun, Jinwei; Shao, Zhuxiao; Zheng, Qiuhong

    2017-12-01

    The paper analyzes hydrodynamic characteristics and the strength of a novel dot-matrix oscillating wave energy converter, which is in accordance with nowadays’ research tendency: high power, high efficiency, high reliability and low cost. Based on three-dimensional potential flow theory, the paper establishes motion control equations of the wave energy converter unit and calculates wave loads and motions. On this basis, a three-dimensional finite element model of the device is built to check its strength. Through the analysis, it can be confirmed that the WEC is feasible and the research results could be a reference for wave energy’s exploration and utilization.

  16. Strength, shrinkage, erodibility and capillary flow characteristics of cement-treated recycled pavement materials

    Directory of Open Access Journals (Sweden)

    William Fedrigo

    2017-09-01

    Full Text Available Full-depth recycling with portland cement (FDR-PC has been widely used for pavement rehabilitation; however, doubts remain regarding factors affecting some properties of the recycled material. Aiming on quantifying the effects of those factors on the strength, drying shrinkage, erodibility, capillary rise and absorption of cement-treated mixtures (CTM of reclaimed asphalt pavement (RAP and graded crushed stone, tests were conducted considering different RAP contents, cement contents, compaction efforts and curing times. Cement addition increased the mixtures strength and reduced their erodibility and capillary flow characteristics, but increased shrinkage. Low cement contents resulted in acceptable strength for CTM, but in high capillary rise and absorption, not being suitable if the layer is exposed to long periods of water soaking. Higher compaction effort led to similar effects as cement addition, counterbalancing low cement contents usage and reducing costs and shrinkage cracking risk. Strength and shrinkage showed higher growth rates at early stages, and then precautions should be taken in order to avoid moisture loss. Increasing RAP content decreased strength; though, RAP effect on the other properties was statistically non-significant, indicating a similar behaviour as CTM without RAP. Considering the studied properties, the mixture with most satisfactory behaviour for field applications was identified. The results highlighted strength is not the only property to be considered when designing FDR-PC mixtures; although presenting acceptable strength, some mixtures may fail due to shrinkage cracking or erosion, when exposed to water content variations. Keywords: Full-depth recycling with cement, Strength, Drying shrinkage, Erodibility, Capillary rise, Absorption

  17. Effect of surface roughness variation on the transmission characteristics of D-shaped fibers with ambient index change

    International Nuclear Information System (INIS)

    Kim, Hyun-Joo; Kwon, Oh-Jang; Han, Young-Geun

    2010-01-01

    The influence of surface roughness on the sensitivity of D-shaped fibers to changes in the ambient index was investigated. In order to obtain D-shaped fibers with different surface roughness, we polished one side of the fibers by using different abrasive grits. The topographies of the surfaces of the polished D-shaped fibers were then observed by using atomic force microscopy (AFM). The light scattered from the rough surfaces of the D-shaped fibers was measured by using optical microscopy. The effect of an ambient index change on the transmission characteristics of D-shaped fibers was measured for various values of the surface roughness. The experimental results indicate that variations in the surface roughness have a considerable influence on the sensitivity of the transmission characteristics of D-shaped fibers to changes in the ambient index.

  18. Fiber-Optic Magnetic-Field-Strength Measurement System for Lightning Detection

    Science.gov (United States)

    Gurecki, Jay; Scully, Robert; Davis, Allen; Kirkendall, Clay; Bucholtz, Frank

    2011-01-01

    A fiber-optic sensor system is designed to measure magnetic fields associated with a lightning stroke. Field vector magnitudes are detected and processed for multiple locations. Since physical limitations prevent the sensor elements from being located in close proximity to highly conductive materials such as aluminum, the copper wire sensor elements (3) are located inside a 4-cubic-in. (.66-cubic-cm) plastic housing sensor head and connected to a fiber-optic conversion module by shielded cabling, which is limited to the shortest length feasible. The signal path between the conversion module and the avionics unit which processes the signals are fiber optic, providing enhanced immunity from electromagnetic radiation incident in the vicinity of the measurements. The sensors are passive, lightweight, and much smaller than commercial B-dot sensors in the configuration which measures a three-dimensional magnetic field. The system is expandable, and provides a standard-format output signal for downstream processing. Inside of the sensor head, three small search coils, each having a few turns on a circular form, are mounted orthogonally inside the non-metallic housing. The fiber-optic conversion module comprises three interferometers, one for each search coil. Each interferometer has a high bandwidth optical phase modulator that impresses the signal received from its search coil onto its output. The output of each interferometer travels by fiber optic cable to the avionics unit, and the search coil signal is recovered by an optical phase demodulator. The output of each demodulator is fed to an analog-to-digital converter, whose sampling rate is determined by the maximum expected rate of rise and peak signal magnitude. The output of the digital processor is a faithful reproduction of the coil response to the incident magnetic field. This information is provided in a standard output format on a 50-ohm port that can be connected to any number of data collection and processing

  19. Microstructural, mechanical, and thermal characteristics of recycled cellulose fiber-halloysite-epoxy hybrid nanocomposites

    KAUST Repository

    Alamri, H.

    2012-02-26

    Epoxy hybrid-nanocomposites reinforced with recycled cellulose fibers (RCF) and halloysite nanotubes (HNTs) have been fabricated and investigated. The dispersion of HNTs was studied by synchrotron radiation diffraction (SRD) and transmission electron microscopy (TEM). The influences of RCF/HNTs dispersion on the mechanical properties and thermal properties of these composites have been characterized in terms of flexural strength, flexural modulus, fracture toughness, impact toughness, impact strength, and thermogravimetric analysis. The fracture surface morphology and toughness mechanisms were investigated by SEM. Results indicated that mechanical properties increased because of the addition of HNTs into the epoxy matrix. Flexural strength, flexural modulus, fracture toughness, and impact toughness increased by 20.8, 72.8, 56.5, and 25.0%, respectively, at 1 wt% HNTs load. The presence of RCF dramatically enhanced flexural strength, fracture toughness, impact strength, and impact toughness of the composites by 160%, 350%, 444%, and 263%, respectively. However, adding HNTs to RCF/epoxy showed only slight enhancements in flexural strength and fracture toughness. The inclusion of 5 wt% HNTs into RCF/epoxy ecocomposites increased the impact toughness by 27.6%. The presence of either HNTs or RCF accelerated the thermal degradation of neat epoxy. However, at high temperature, samples reinforced with RCF and HNTs displayed better thermal stability with increased char residue than neat resin. © 2012 Society of Plastics Engineers.

  20. Strength and deformability of compressed concrete elements with various types of non-metallic fiber and rods reinforcement under static loading

    Science.gov (United States)

    Nevskii, A. V.; Baldin, I. V.; Kudyakov, K. L.

    2015-01-01

    Adoption of modern building materials based on non-metallic fibers and their application in concrete structures represent one of the important issues in construction industry. This paper presents results of investigation of several types of raw materials selected: basalt fiber, carbon fiber and composite fiber rods based on glass and carbon. Preliminary testing has shown the possibility of raw materials to be effectively used in compressed concrete elements. Experimental program to define strength and deformability of compressed concrete elements with non-metallic fiber reinforcement and rod composite reinforcement included design, manufacture and testing of several types of concrete samples with different types of fiber and longitudinal rod reinforcement. The samples were tested under compressive static load. The results demonstrated that fiber reinforcement of concrete allows increasing carrying capacity of compressed concrete elements and reducing their deformability. Using composite longitudinal reinforcement instead of steel longitudinal reinforcement in compressed concrete elements insignificantly influences bearing capacity. Combined use of composite rod reinforcement and fiber reinforcement in compressed concrete elements enables to achieve maximum strength and minimum deformability.

  1. Influence of different catilever extensions and glass or polyamaramid reinforcement fibers on fracture strength of implant-supported temporary

    Directory of Open Access Journals (Sweden)

    Paola Colán Guzmán

    2008-04-01

    Full Text Available In long-term oral rehabilitation treatments, resistance of provisional crowns is a very important factor, especially in cases of an extensive edentulous distal space. The aim of this laboratorial study was to evaluate an acrylic resin cantilever-type prosthesis regarding the flexural strength of its in-balance portion as a function of its extension variation and reinforcement by two types of fibers (glass and polyaramid, considering that literature is not conclusive on this subject. Each specimen was composed by 3 total crowns at its mesial portion, each one attached to an implant component (abutment, while the distal portion (cantilever had two crowns. Each specimen was constructed by injecting acrylic resin into a two-part silicone matrix placed on a metallic base. In each specimen, the crowns were fabricated with either acrylic resin (control group or acrylic resin reinforced by glass (Fibrante, Angelus or polyaramide (Kevlar 49, Du Pont fibers. Compression load was applied on the cantilever, in a point located 7, 14 or 21 mm from the distal surface of the nearest crown with abutment, to simulate different extensions. The specimen was fixed on the metallic base and the force was applied until fracture in a universal test machine. Each one of the 9 sub-groups was composed by 10 specimens. Flexural strength means (in kgf for the distances of 7, 14 and 21 mm were, respectively, 28.07, 8.27 and 6.39 for control group, 31.89, 9.18 and 5.16 for Kevlar 49 and 30.90, 9.31 and 6.86 for Fibrante. Data analysis ANOVA showed statistically significant difference (p<0.05 only regarding cantilever extension. Tukey's test detected significantly higher flexural strength for the 7 mm-distance, followed by 14 and 21 mm. Fracture was complete only on specimens of non-reinforced groups.

  2. A study on the fracture strength of steel fiber reinforced concrete structures with initial cracks

    International Nuclear Information System (INIS)

    Chang, Dong Il; Chai, Won Kyu; Lee, Myeong Gu

    1991-01-01

    Fracture tests were carried out in order to investigate the fracture behavior of SFRC(Steel Fiber Reinforced Concrete) structures with initial cracks. Sixty three SFRC beams were used in the tests. And the fracture mode, and relations between loading and mid-span deflection of the beams were observed. On the base of test results, fracture behavior of SFRC beams resulted from steel fiber content and initial crack length to beam depth ratio were found out, and the stress intensity factors, the modulus of rupture and the fracture energy of SFRC beams may then be calculated. According to the results of regression analysis, prediction formulas for the modulus of rupture and the fracture energy of SFRC beams are also suggested. (Author)

  3. Probabilistic analysis of strength and thermal-physic WWER fuel rod characteristics using START-3 code

    International Nuclear Information System (INIS)

    Medvedev, A.; Bogatyr, S.; Khramtsov; Sokolov, F.

    2001-01-01

    During the last years probabilistic methods for evaluation of the influence of the fuel geometry and technology parameters on fuel operational reliability are widely used. In the present work the START-3 procedure is used to calculate the thermal physics and strength characteristics of WWER fuel rods behavior. The procedure is based on the Monte-Carlo method with the application of Sobol quasi-random sequences. This technique allows to treat the fuel rod technological and operating parameters as well as its strength and thermal physics characteristics as random variables. The work deals with a series of WWER-1000 fuel rod statistical tests and verification based on the PIE results. Also preliminary calculations are implemented with the aim to determine the design schema parameters. This should ensure the accuracy of the assessment of the parameters of WWER fuel rod characteristics distribution. The probability characteristics of fuel rod strength and thermal physics are assessed via the statistical analysis of the results of probability calculations

  4. Characteristics and applications of high-performance fiber reinforced asphalt concrete

    Science.gov (United States)

    Park, Philip

    Steel fiber reinforced asphalt concrete (SFRAC) is suggested in this research as a multifunctional high performance material that can potentially lead to a breakthrough in developing a sustainable transportation system. The innovative use of steel fibers in asphalt concrete is expected to improve mechanical performance and electrical conductivity of asphalt concrete that is used for paving 94% of U. S. roadways. In an effort to understand the fiber reinforcing mechanisms in SFRAC, the interaction between a single straight steel fiber and the surrounding asphalt matrix is investigated through single fiber pull-out tests and detailed numerical simulations. It is shown that pull-out failure modes can be classified into three types: matrix, interface, and mixed failure modes and that there is a critical shear stress, independent of temperature and loading rate, beyond which interfacial debonding will occur. The reinforcing effects of SFRAC with various fiber sizes and shapes are investigated through indirect tension tests at low temperature. Compared to unreinforced specimens, fiber reinforced specimens exhibit up to 62.5% increase in indirect tensile strength and 895% improvements in toughness. The documented improvements are the highest attributed to fiber reinforcement in asphalt concrete to date. The use of steel fibers and other conductive additives provides an opportunity to make asphalt pavement electrically conductive, which opens up the possibility for multifunctional applications. Various asphalt mixtures and mastics are tested and the results indicate that the electrical resistivity of asphaltic materials can be manipulated over a wide range by replacing a part of traditional fillers with a specific type of graphite powder. Another important achievement of this study is development and validation of a three dimensional nonlinear viscoelastic constitutive model that is capable of simulating both linear and nonlinear viscoelasticity of asphaltic materials. The

  5. Coupling Characteristics of Fused Optical Fiber Coupler Formed with Single-Mode Fiber and Photonic Crystal Fiber Having Air Hole Collapsed Taper

    Directory of Open Access Journals (Sweden)

    Hirohisa Yokota

    2016-01-01

    Full Text Available Fused coupler forming with a single-mode fiber (SMF and a photonic crystal fiber (PCF is one of the solutions for optical coupling from a light source to a PCF. In this paper, we presented coupling characteristics of a fused fiber coupler formed with an ordinary SMF and a PCF having air hole collapsed taper. A prototype of SMF-PCF coupler with air hole collapsed taper was fabricated using CO2 laser irradiation. The coupling efficiency from SMF to PCF was −6.2 dB at 1554 nm wavelength in the fabricated coupler. The structure of the SMF-PCF coupler to obtain high coupling efficiency was theoretically clarified by beam propagation analysis using an equivalent model of the coupler with simplification. It was clarified that appropriately choosing the prestretched or etched SMF diameter and the length of air hole collapsed region was effective to obtain high coupling efficiency that was a result of high extinction ratio at cross port and low excess loss. We also demonstrated that the diameter of prestretched SMF to obtain high coupling efficiency was insensitive to the air hole diameter ratio to pitch of the PCF in the air hole collapsed SMF-PCF coupler.

  6. Characteristics of plasma plume in fiber laser welding of aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Ming; Chen, Cong; Hu, Ming; Guo, Lianbo; Wang, Zemin, E-mail: zmwang@mail.hust.edu.cn; Zeng, Xiaoyan

    2015-01-30

    Highlights: • Spectroscopic properties of fiber laser induced Al plasma plume are measured. • The plume is usually a metal vapor dominated weakly ionized plasma. • The plume is a strongly ionized plasma after laser power is higher than 5 kW. • Plasma shielding effect must be considered after laser power reaches 5 kW. • Plasma shielding effect is dominated by inverse bremsstrahlung absorption. - Abstract: To understand the laser–matter interaction in fiber laser welding of aluminum alloys, the effects of laser power on the characteristics of fiber laser induced plasma plume were studied by emission spectroscopic analysis firstly. The plasma characteristic parameters including electron temperature, electron density, ionization degree, and inverse bremsstrahlung linear absorption coefficient were computed according to the spectral data. It was found that the laser power of 5 kW is a turning point. After the laser power reaches 5 kW, the plume changes from a metal vapor dominated weakly ionized plasma to a strongly ionized plasma. The corresponding phenomena are the dramatic increase of the value of characteristic parameters and the appearance of strong plasma shielding effect. The calculation of effective laser power density demonstrated that the plasma shielding effect is dominated by inverse bremsstrahlung absorption. The finding suggested the plasma shielding effect must be considered in fiber laser welding of aluminum alloys, rather than is ignored as claimed in previous view.

  7. PROTECTIVE COATINGS OF FIBER BRAGG GRATING FOR MINIMIZING OF MECHANICAL IMPACT ON ITS WAVELENGTH CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    A. S. Munko

    2015-03-01

    Full Text Available The paper deals with the scheme for the study of the Bragg wavelength shift dependence on the applied tensile force. Samples of fiber Bragg gratings with different coatings have been studied: the restored acrylate coating, the heatshrinkable fusion splice protection sleeve without metal rod, the heat-shrinkable fusion splice protection sleeve with a metal rod, the metal capillary, polyvinylchloride tube. For different coatings of diffractive structure, dependences of wavelength shift for the Bragg grating resonance have been obtained on the tensile strength applied to the ends of an optical fiber. It was determined that the studied FBG coatings give the possibility to reduce the mechanical impact on the Bragg wavelength shift for 1.1-15 times as compared to an uncoated waveguide. The most effective version of coated fiber Bragg grating is the heatshrinkable fusion splice protection sleeve with a metal rod. When the force (equal to 6 N is applied to the 100 mm optical fiber area with the inscribed diffractive structure, the Bragg wavelength shift is 7.5 nm for the unprotected sample and 0.5 nm for the one coated with the heat-shrinkable fusion splice protection sleeve.

  8. Changes of strength characteristics of pervious concrete due to variations in water to cement ratio

    Science.gov (United States)

    Kovac, M.; Sicakova, A.

    2017-10-01

    Pervious concrete is considered to be a sustainable pavement material due to high water permeability. The experiment presented in this paper was aimed at study the influence of water to cement ratio on both the compressive and splitting tensile strength of pervious concrete. Typically, less water content in concrete mixture leads to less porosity of cement paste and thus it provides desirable mechanical properties. In case of conventional dense concrete, the lower is the water to cement ratio, the higher or better is the strength, density and durability of concrete. This behaviour is not quite clear in case of pervious concrete because of low amount of cement paste present. Results of compressive and splitting tensile strength of pervious concrete are discussed in the paper while taking into account values measured after 2 and 28 days of hardening and variations in water to cement ratio. The results showed that changes of water to cement ratio from 0.25 to 0.35 caused only slight differences in strength characteristics, and this applied to both types of tested strength.

  9. Volumetric composition and shear strength evaluation of pultruded hybrid kenaf/glass fiber composites

    DEFF Research Database (Denmark)

    Hashemi, Fariborz; Tahir, Paridah Md; Madsen, Bo

    2015-01-01

    by using a gravimetrically based method. Optical microscopy was used to determine the location of voids. The short-beam test method was used to determine the interlaminar shear strength of the composites, and the failure mode was observed. It was found that the void volume fraction of the composites...

  10. The influence of double nested layer waviness on compression strength of carbon fiber composite materials

    International Nuclear Information System (INIS)

    Khan, Z.M.

    1997-01-01

    As advanced composite materials having superior physical and mechanical properties are being developed, optimization of their production processes in eagerly being sought. One of the most common defect in production of structural composites is layer waviness. Layer waviness is more pronounced in thick section flat and cylindrical laminates that are extensively used in missile casings, submersibles and space platforms. Layer waviness undulates the entire layers of a multidirectional laminate in through-the-thickness direction leading to gross deterioration of its compression strength. This research investigates the influence of multiple layer waviness in a double nest formation on the compression strength of a composite laminate. Different wave fractions of wave 0 degree centigrade layer fabricated in IM/85510-7 carbon - epoxy composite laminate on a steel mold using single step fabrication procedure. The laminate was cured on a heated press according to specific curing cycle. Static compression testing was performed using NASA short block compression fixture on an MTS servo Hydraulic machine. The purpose of these tests was to determine the effects of multiple layer wave regions on the compression strength of composite laminate. The experimental and analytical results revealed that up to about 35% fraction of wave 0 degree layer exceeded 35%. This analysis indicated that the percentage of 0 degree wavy layer may be used to estimate the reduction in compression strength of a composite laminate under restricted conditions. (author)

  11. A STUDY OF TRANSVERSE AND LONGITUDINAL SIZE EFFECTS IN HIGH-STRENGTH POLYETHYLENE FIBERS

    NARCIS (Netherlands)

    PENNING, JP; DEVRIES, AA; PENNINGS, AJ; HOOGSTRATEN, HW

    The results of an experimental study of the effects of fibre diameter and testing length on the strength of polyethylene fibres prepared by the gel-spinning-hot-drawing process are reported. These size effects have been studied in fibres covering a range of mechanical properties in order to

  12. High Resolution Consensus Mapping of Quantitative Trait Loci for Fiber Strength, Length and Micronaire on Chromosome 25 of the Upland Cotton (Gossypium hirsutum L..

    Directory of Open Access Journals (Sweden)

    Zhen Zhang

    Full Text Available Cotton (Gossypium hirsutum L. is an important agricultural crop that provides renewable natural fiber resources for the global textile industry. Technological developments in the textile industry and improvements in human living standards have increased the requirement for supplies and better quality cotton. Upland cotton 0-153 is an elite cultivar harboring strong fiber strength genes. To conduct quantitative trait locus (QTL mapping for fiber quality in 0-153, we developed a population of 196 recombinant inbred lines (RILs from a cross between 0-153 and sGK9708. The fiber quality traits in 11 environments were measured and a genetic linkage map of chromosome 25 comprising 210 loci was constructed using this RIL population, mainly using simple sequence repeat markers and single nucleotide polymorphism markers. QTLs were identified across diverse environments using the composite interval mapping method. A total of 37 QTLs for fiber quality traits were identified on chromosome 25, of which 17 were stably expressed in at least in two environments. A stable fiber strength QTL, qFS-chr25-4, which was detected in seven environments and was located in the marker interval between CRI-SNP120491 and BNL2572, could explain 6.53%-11.83% of the observed phenotypic variations. Meta-analysis also confirmed the above QTLs with previous reports. Application of these QTLs could contribute to improving fiber quality and provide information for marker-assisted selection.

  13. High Resolution Consensus Mapping of Quantitative Trait Loci for Fiber Strength, Length and Micronaire on Chromosome 25 of the Upland Cotton (Gossypium hirsutum L.).

    Science.gov (United States)

    Zhang, Zhen; Li, Junwen; Muhammad, Jamshed; Cai, Juan; Jia, Fei; Shi, Yuzhen; Gong, Juwu; Shang, Haihong; Liu, Aiying; Chen, Tingting; Ge, Qun; Palanga, Koffi Kibalou; Lu, Quanwei; Deng, Xiaoying; Tan, Yunna; Li, Wei; Sun, Linyang; Gong, Wankui; Yuan, Youlu

    2015-01-01

    Cotton (Gossypium hirsutum L.) is an important agricultural crop that provides renewable natural fiber resources for the global textile industry. Technological developments in the textile industry and improvements in human living standards have increased the requirement for supplies and better quality cotton. Upland cotton 0-153 is an elite cultivar harboring strong fiber strength genes. To conduct quantitative trait locus (QTL) mapping for fiber quality in 0-153, we developed a population of 196 recombinant inbred lines (RILs) from a cross between 0-153 and sGK9708. The fiber quality traits in 11 environments were measured and a genetic linkage map of chromosome 25 comprising 210 loci was constructed using this RIL population, mainly using simple sequence repeat markers and single nucleotide polymorphism markers. QTLs were identified across diverse environments using the composite interval mapping method. A total of 37 QTLs for fiber quality traits were identified on chromosome 25, of which 17 were stably expressed in at least in two environments. A stable fiber strength QTL, qFS-chr25-4, which was detected in seven environments and was located in the marker interval between CRI-SNP120491 and BNL2572, could explain 6.53%-11.83% of the observed phenotypic variations. Meta-analysis also confirmed the above QTLs with previous reports. Application of these QTLs could contribute to improving fiber quality and provide information for marker-assisted selection.

  14. Effect of Self-Adhesive and Separate Etch Adhesive Dual Cure Resin Cements on the Bond Strength of Fiber Post to Dentin at Different Parts of the Root

    Directory of Open Access Journals (Sweden)

    Ehsan Mohamadian Amiri

    2017-10-01

    Full Text Available Objectives: Bonding of fiber posts to intracanal dentin is challenging in the clinical setting. This study aimed to compare the effect of self-adhesive and separate etch adhesive dual cure resin cements on the bond strength of fiber post to dentin at different parts of the root.Materials and Methods: This in-vitro experimental study was conducted on 20 single-rooted premolars. The teeth were decoronated at 1mm coronal to the cementoenamel junction (CEJ, and the roots underwent root canal treatment. Post space was prepared in the roots. Afterwards, the samples were randomly divided into two groups. In group 1, the fiber posts were cemented using Rely X Unicem cement, while in group 2, the fiber posts were cemented using Duo-Link cement, according to the manufacturer's instructions. The intracanal post in each root was sectioned into three segments of coronal, middle, and apical, and each cross-section was subjected to push-out bond strength test at a crosshead speed of 1mm/minute until failure. Push-out bond strength data were analyzed using independent t-test and repeated measures ANOVA.Results: The bond strength at the middle and coronal segments in separate etch adhesive cement group was higher than that in self-adhesive cement group. However, the bond strength at the apical segment was higher in self-adhesive cement group compared to that in the other group. Overall, the bond strength in separate etch adhesive cement group was significantly higher than that in self-adhesive cement group (P<0.001.Conclusions: Bond strength of fiber post to intracanal dentin is higher after the use of separate etch adhesive cement compared to self-adhesive cement.

  15. Field emission characteristics of a small number of carbon fiber emitters

    Directory of Open Access Journals (Sweden)

    Wilkin W. Tang

    2016-09-01

    Full Text Available This paper reports an experiment that studies the emission characteristics of small number of field emitters. The experiment consists of nine carbon fibers in a square configuration. Experimental results show that the emission characteristics depend strongly on the separation between each emitter, providing evidence of the electric field screening effects. Our results indicate that as the separation between the emitters decreases, the emission current for a given voltage also decreases. The authors compare the experimental results to four carbon fiber emitters in a linear and square configurations as well as to two carbon fiber emitters in a paired array. Voltage-current traces show that the turn-on voltage is always larger for the nine carbon fiber emitters as compared to the two and four emitters in linear configurations, and approximately identical to the four emitters in a square configuration. The observations and analysis reported here, based on Fowler-Nordheim field emission theory, suggest the electric field screening effect depends critically on the number of emitters, the separation between them, and their overall geometric configuration.

  16. ANTHROPOMETRIC AND STRENGTH CHARACTERISTICS OF TENPIN BOWLERS WITH DIFFERENT PLAYING ABILITIES

    Directory of Open Access Journals (Sweden)

    Rizal Razman

    2012-01-01

    Full Text Available The primary purpose of this study was to investigate the strength and anthropometric characteristics of elite and semi-elite tenpin bowlers as compared to non-bowlers, and to establish whether it was possible to discriminate playing level through selected predictor variables. Elite and semi-elite bowlers were distinguished by their bowling score average (BSave, with participants scoring 200 pin falls and above assigned to the elite group. Eighteen elite bowlers (M=10, F=8; BSave 213.2±6.80, 12 semi-elite bowlers (M=7, F=5; BSave 181.3±9.36 and 33 sedentary university students (M=14, F=19 were recruited. Anthropometric measurements were taken and isometric arm strength was recorded. Between-group differences were identified through a two-way ANOVA, while discriminant analysis was used to predict group membership. For anthropometric characteristics, the results indicated that the elite bowlers were heavier, had longer lower leg and hand length and had a wider arm span as compared to the non-bowlers. The elite group also had stronger forearm/wrist internal rotation compared to non-bowlers. In addition, the male elite group were stronger than the non-bowling group for arm flexion. There appeared to be a 54% success rate for predicting group membership from selected anthropometric and strength discriminating variables, with forearm/wrist internal rotation strength being the best discriminating variable. It is suggested that coaches should benefit by selecting larger built bowlers with long limbs. Furthermore, bowlers could potentially gain by paying extra attention to increasing the strength levels of forearm/wrist internal rotators and arm flexors during training. These findings also provide normative data for elite and semi-elite bowlers.

  17. Optimisation of hybrid high-modulus/high-strength carbon fiber reinforced plastic composite drive

    OpenAIRE

    Montagnier, Olivier; Hochard, Christian

    2011-01-01

    International audience; This study deals with the optimisation of hybrid composite drive shafts operating at subcritical or supercritical speeds, using a genetic algorithm. A formulation for the flexural vibrations of a composite drive shaft mounted on viscoelastic supports including shear effects is developed. In particular, an analytic stability criterion is developed to ensure the integrity of the system in the supercritical regime. Then it is shown that the torsional strength can be compu...

  18. Influence of Cutting Temperature on the Tensile Strength of a Carbon Fiber-Reinforced Polymer

    Directory of Open Access Journals (Sweden)

    Jérémy Delahaigue

    2017-12-01

    Full Text Available Carbon fiber-reinforced plastics (CFRP have seen a significant increase in use over the years thanks to their specific properties. Despite continuous improvements in the production methods of laminated parts, a trimming operation is still necessary to achieve the functional dimensions required by engineering specifications. Laminates made of carbon fibers are very abrasive and cause rapid tool wear, and require high cutting temperatures. This creates damage to the epoxy matrix, whose glass-transition temperature is often recognized to be about 180 °C. This study aims to highlight the influence of the cutting temperature generated by tool wear on the surface finish and mechanical properties obtained from tensile tests. Trimming operations were performed on a quasi-isotropic 24-ply carbon/epoxy laminate, of 3.6 mm thickness, with a 6 flutes diamond-coated (CVD cutter. The test specimens of 6 mm and 12 mm wide were obtained by trimming. The reduced width of the coupons allowed amplification of the effect of defects on the measured properties by increasing the proportion of coupon cross-section occupied by the defects. A new tool and a tool in an advanced state of wear were used to generate different cutting temperatures. Results showed a cutting temperature of 300 °C for the new tool and 475 °C for the worn tool. The analysis revealed that the specimens machined with the new tool have no thermal damage and the cut is clean. The plies oriented at −45° presented the worst surface finish according to the failure mode of the fiber. For the worn tool, the surface was degraded and the matrix was carbonized. After cutting, observations showed a degraded resin spread on the machined surface, which reduced the surface roughness and hid the cutting defects. In support of these observations, the tensile tests showed no variation of the mechanical properties for the 12 mm-wide specimens, but did show a 10% loss in mechanical properties for the 6 mm

  19. Influence of Er,Cr:YSGG Laser Surface Treatments on Micro Push-Out Bond Strength of Fiber Posts to Composite Resin Core Materials

    Directory of Open Access Journals (Sweden)

    Mehrsima Ghavami-Lahiji

    2018-03-01

    Full Text Available Statement of problem: The bonding of fiber post to resin core or root dentin is challenged by limited penetration of resin material to the polymeric matrix of fiber posts. Objectives: The purpose of this study was to investigate the effect of Er,Cr:YSGG on micro push-out bond strength of glass fiber posts to resin core material. Materials and Methods: We used 2 commercially available fiber posts, Exacto (Angelus and White Post DC (FGM, which had similar coronal diameters. Specimens of each fiber post (n=36 were randomly divided into three subgroups (n=12 posts per group according to different surface treatment methods: control (no surface treatment, irradiation by 1W Er,Cr:YSGG, and irradiation by 1.5W Er,Cr:YSGG. A cylindrical plastic tube was placed around the post. Resin core material was filled into the tube and cured. Coronal portions of the posts were sectioned into 1-mm-thick slices. Then, the specimens were subjected to a thermocyling device for 3000 cycles. The micro push-out test was carried out using a Universal Testing Machine. Data were analyzed using one-way ANOVA followed by Tukey’s HSD post hoc test to investigate the effect of different surface treatments on each type of fiber post. Results: The 1.5W Er,Cr:YSGG laser statistically reduced micro push-out bond strength values in the Exacto groups (P0.05. Mode of failure analysis showed that mixed failure was the predominant failure type for all surface treatment groups. Conclusions: The beneficial effect of Er,Cr:YSGG laser application could not be confirmed based on the results of this in vitro study. Er,Cr:YSGG laser could not significantly enhance the bond strength values. However, the 1.5W laser statistically decreased micro push-out bond strength in the Exacto fiber posts.

  20. Modeling and experiments on the drive characteristics of high-strength water hydraulic artificial muscles

    Science.gov (United States)

    Zhang, Zengmeng; Hou, Jiaoyi; Ning, Dayong; Gong, Xiaofeng; Gong, Yongjun

    2017-05-01

    Fluidic artificial muscles are popular in robotics and function as biomimetic actuators. Their pneumatic version has been widely investigated. A novel water hydraulic artificial muscle (WHAM) with high strength is developed in this study. WHAMs can be applied to underwater manipulators widely used in ocean development because of their environment-friendly characteristics, high force-to-weight ratio, and good bio-imitability. Therefore, the strength of WHAMs has been improved to fit the requirements of underwater environments and the work pressure of water hydraulic components. However, understanding the mechanical behaviors of WHAMs is necessary because WHAMs use work media and pressure control that are different from those used by pneumatic artificial muscles. This paper presents the static and dynamic characteristics of the WHAM system, including the water hydraulic pressure control circuit. A test system is designed and built to analyze the drive characteristics of the developed WHAM. The theoretical relationships among the amount of contraction, pressure, and output drawing force of the WHAM are tested and verified. A linearized transfer function is proposed, and the dynamic characteristics of the WHAM are investigated through simulation and inertia load experiments. Simulation results agree with the experimental results and show that the proposed model can be applied to the control of WHAM actuators.

  1. Response surface optimization of pH and ionic strength for emulsion characteristics of egg yolk.

    Science.gov (United States)

    Kurt, S; Zorba, O

    2009-11-01

    Effects of pH (3.5, 4.5, 6.0, 7.5, and 8.5) and ionic strength (0.05, 0.15, 0.30, 0.45, and 0.55 M NaCl) on emulsion capacity, emulsion stability (ES), apparent yield stress of emulsion (AYS), and emulsion density (ED) of egg yolk were studied by using a model system. Ionic strength and pH had significant (P emulsion characteristics of egg yolk. Their interaction effects also have been found significant on ES, AYS, and ED. Predicted solutions of ES, emulsion capacity, and ED were minimum. The critical point of ES was determined to be at pH 6.08 and an ionic strength of 0.49 (M NaCl). Predicted solution for AYS was a maximum, which was determined to be at pH 6.04 and an ionic strength of 0.29 (M NaCl). Optimum values of pH and ionic strenght were 4.61 to 7.43 and 0.10 to 0.47, respectively.

  2. Microstructure Characterization of Fiber Laser Welds of S690QL High-Strength Steels

    Science.gov (United States)

    Li, Baoming; Xu, Peiquan; Lu, Fenggui; Gong, Hongying; Cui, Haichao; Liu, Chuangen

    2018-02-01

    The use of fiber laser welding to join S690QL steels has attracted interest in the field of construction and assembly. Herein, 13-mm-thick S690QL welded joints were obtained without filler materials using the fiber laser. The as-welded microstructures and the impact energies of the joints were characterized and measured using electron microscopy in conjunction with high-resolution transmission electron images, X-ray diffraction, and impact tests. The results indicated that a single-sided welding technique could be used to join S690QL steels up to a thickness of 12 mm (fail to fuse the joint in the root) when the laser power is equal to 12 kW (scan speed 1 m/min). Double-side welding technique allows better weld penetration and better control of heat distribution. Observation of the samples showed that the fusion zone exhibited bainitic and martensitic microstructures with increased amounts of martensites (Ms) compared with the base materials. Also, the grains in the fusion zone increased in coarseness as the heat input was increased. The fusion zone exhibited increased hardness (397 HV0.2) while exhibiting a simultaneous decrease in the impact toughness. The maximum impact energy value of 26 J was obtained from the single-side-welded sample, which is greater than those obtained from the double-side-welded samples (maximum of 18 J). Many more dislocations and plastic deformations were found in the fusion zone than the heat-affected zone in the joint, which hardened the joints and lowered the impact toughness. The microstructures characterized by FTEM-energy-dispersive X-ray spectrometer also exhibited laths of M, as well as stacking faults and dislocations featuring high-density, interfacial structure ledges that occur between the high-angle grain boundaries and the M and bainite.

  3. Strength and microstructure characteristics of the recycled rubber tire-sand mixtures as lightweight backfill.

    Science.gov (United States)

    Zhang, Tao; Cai, Guojun; Duan, Weihong

    2018-02-01

    The disposal of scrap rubber tires has induced critical environmental issue worldwide due to the rapid increase in the number of vehicles. Recycled scrap tires as a construction material in civil engineering have significant environmental benefits from a waste management perspective. A systematic study that deals with strength and microstructure characteristics of the rubber-sand mixtures is initiated, and mechanical response of the mixtures is discussed in this investigation. Experiments were conducted to evaluate the effects of rubber fraction on the basic properties including mass density (ρ), stress-strain characteristics, shear strength, and unconfined compression strength (q u ) of the rubber-sand mixtures. Additionally, scanning electron microscopy (SEM) was carried out to reveal the microstructure characteristics of the mixtures with various rubber fractions. A discussion on the micromechanics of the mixtures also was conducted. This study demonstrates that the ρ, friction angle, and q u decrease linearly with an increase in rubber fraction, whereas shear strain at peak increases. The stress-strain characteristics of the rubber-sand mixtures shift from brittle to ductile as the rubber fraction increase. These changes are attributed to remarkably lower stiffness and higher compressibility of the rubber particle compared with those of the conventional mineral aggregates. With an increase in the rubber fraction, the mechanical response of rubber-sand mixtures exhibits two types: sand-like material and rubber-like material. Rubber particle possesses the capacity to prevent the contacted sand particles from sliding at lower rubber fraction, whereas it transmits the applied loadings as the rubber fraction increased. This outcome reinforces the practicability of using recycled rubber tire-sand mixtures as a lightweight backfill in subbase/base applications.

  4. Thermal characteristics of carbon fiber reinforced epoxy containing multi-walled carbon nanotubes

    Science.gov (United States)

    Lee, Jin-woo; Park, Soo-Jeong; Kim, Yun-hae; Riichi-Murakami

    2018-06-01

    The material with irregular atomic structures such as polymer material exhibits low thermal conductivity because of the complex structural properties. Even materials with same atomic configurations, thermal conductivity may be different based on their structural properties. It is expected that nanoparticles with conductivity will change non-conductive polymer base materials to electrical conductors, and improve the thermal conductivity even with extremely small filling amount. Nano-composite materials contain nanoparticles with a higher surface ratio which makes the higher interface percentage to the total surface of nanoparticles. Therefore, thermal resistance of the interface becomes a dominating factor determines the effective thermal conductivity in nano-composite materials. Carbon fiber has characteristic of resistance or magnetic induction and Also, Carbon nanotube (CNT) has electronic and thermal property. It can be applied for heating system. These characteristic are used as heating composite. In this research, the exothermic characteristics of Carbon fiber reinforced composite added CNT were evaluated depend on CNT length and particle size. It was found that the CNT dispersed in the resin reduces the resistance between the interfaces due to the decrease in the total resistance of the heating element due to the addition of CNTs. It is expected to improve the life and performance of the carbon fiber composite material as a result of the heating element resulting from this paper.

  5. EFFECT OF GAMMA RAY IRRADIATION ON INTERLAMINAR SHEAR STRENGTH OF GLASS FIBER REINFORCED PLASTICS AT 77 K

    International Nuclear Information System (INIS)

    Nishimura, A.; Nishijima, S.; Izumi, Y.

    2008-01-01

    It is known that an organic material is damaged by gamma ray irradiation, and the strength after irradiation has dependence on the gamma ray dose. These issues are important not only to make global understanding of electric insulating performance of glass fiber reinforced plastics (GFRP) under irradiation condition but also to develop new insulation materials. This paper presents the dependence of fracture mode and interlaminar shear strength (ILSS) on the material and the gamma ray irradiation effect on the fracture mode and the ILSS. 6 mm radius loading nose and supports were used to prompt ILS fracture for a short beam test. A 2.5 mm thick small specimen machined out of a 13 mm thick G-10CR GFRP plate (sliced specimen) showed lower ILSS and translaminar shear (TLS) fracture, although the same size specimen prepared from a 2.5 mm G-10CR GFRP plate (non-sliced specimen) showed ILS fracture and the higher ILSS. Both type of specimens showed the degradation of ILSS after gamma ray irradiation. The fracture mode of the non-sliced specimen changed from ILS to TLS fracture and no bending fracture was observed. The resistance to shear deformation of glass cloth/epoxy laminate structure would be damaged by the irradiation

  6. Effect of the Volume Fraction of Jute Fiber on the Interlaminar Shear Stress and Tensile Behavior Characteristics of Hybrid Glass/Jute Fiber Reinforced Polymer Composite Bar for Concrete Structures

    Directory of Open Access Journals (Sweden)

    Chan-Gi Park

    2016-01-01

    Full Text Available Hybrid glass/jute fiber reinforced polymer (HGJFRP composite bars were manufactured for concrete structures, and their interlaminar shear stress and tensile performance were evaluated. HGJFRP composite bars were manufactured using a combination of pultrusion and braiding processes. Jute fiber was surface-treated with a silane coupling agent. The mixing ratio of the fiber to the vinyl ester used in the HGJFRP composite bars was 7 : 3. Jute fiber was used to replace glass fiber in proportions of 0, 30, 50, 70, and 100%. The interlaminar shear stress decreased as the proportion of jute fiber increased. Fractures appeared due to delamination between the surface-treated component and the main part of the HGJFRP composite bar. Tensile load-strain curves with 50% jute fiber exhibited linear behavior. With a jute fiber volume fraction of 70%, some plastic deformation occurred. A jute fiber mixing ratio of 100% resulted in a display of linear elastic brittle behavior from the fiber; however, when the surface of the fiber was coated with poly(vinyl acetate, following failure, the jute fiber exhibited partial load resistance. The tensile strength decreased as the jute fiber content increased; however, the tensile strength did not vary linearly with jute fiber content.

  7. Examining Mechanical Strength Characteristics of Selective Inhibition Sintered HDPE Specimens Using RSM and Desirability Approach

    Science.gov (United States)

    Rajamani, D.; Esakki, Balasubramanian

    2017-09-01

    Selective inhibition sintering (SIS) is a powder based additive manufacturing (AM) technique to produce functional parts with an inexpensive system compared with other AM processes. Mechanical properties of SIS fabricated parts are of high dependence on various process parameters importantly layer thickness, heat energy, heater feedrate, and printer feedrate. In this paper, examining the influence of these process parameters on evaluating mechanical properties such as tensile and flexural strength using Response Surface Methodology (RSM) is carried out. The test specimens are fabricated using high density polyethylene (HDPE) and mathematical models are developed to correlate the control factors to the respective experimental design response. Further, optimal SIS process parameters are determined using desirability approach to enhance the mechanical properties of HDPE specimens. Optimization studies reveal that, combination of high heat energy, low layer thickness, medium heater feedrate and printer feedrate yielded superior mechanical strength characteristics.

  8. PMR Polyimide prepreg with improved tack characteristics. [Polymerization of Monomer Reactants applications to fiber reinforced plastics

    Science.gov (United States)

    Serafini, T. T.; Delvigs, P.

    1978-01-01

    Current PMR Polyimide prepreg technology utilizes methanol or ethanol solvents for preparation of the PMR prepreg solutions. The volatility of these solvents limits the tack and drape retention characteristics of unprotected prepreg exposed to ambient conditions. Studies conducted to achieve PMR 15 Polyimide prepreg with improved tack and drape characteristics are described. Improved tack and drape retention were obtained by incorporation of an additional monomer. The effects of various levels of the added monomer on the thermo-oxidative stability and mechanical properties of graphite fiber reinforced PMR 15 composites exposed and tested at 316 C (600 F) are discussed.

  9. Ankle and toe muscle strength characteristics in runners with a history of medial tibial stress syndrome.

    Science.gov (United States)

    Saeki, Junya; Nakamura, Masatoshi; Nakao, Sayaka; Fujita, Kosuke; Yanase, Ko; Morishita, Katsuyuki; Ichihashi, Noriaki

    2017-01-01

    A high proportion of flexor digitorum longus attachment is found at the posteromedial border of the tibia, which is the most common location of medial tibial stress syndrome (MTSS). Therefore, plantar flexion strength of the lesser toes could be related to MTSS; however, the relationship between MTSS and muscle strength of the hallux and lesser toes is not yet evaluated due to the lack of quantitative methods. This study investigated the muscle strength characteristics in runners with a history of MTSS by using a newly developed device to measure the muscle strength of the hallux, lesser toes, and ankle. This study comprised 27 collegiate male runner participants (20.0 ± 1.6 years, 172.1 ± 5.1 cm, 57.5 ± 4.0 kg). Maximal voluntary isometric contraction (MVIC) torque of the plantar flexion, dorsiflexion, inversion, and eversion of the ankle were measured by using an electric dynamometer. MVIC torque of the 1st metatarsophalangeal joint (MTPJ) and 2nd-5th MTPJ were measured by using a custom-made torque-measuring device. MVIC torques were compared between runners with and without a history of MTSS. MVIC torque of the 1st MTPJ plantar flexion was significantly higher in runners with a history of MTSS than in those without it. In contrast, there were no significant differences in the MVIC torque values of the 2nd-5th MTPJ plantar flexion and each MVIC torque of the ankle between runners with and without a history of MTSS. A history of MTSS increased the isometric FHL strength.

  10. DIFFERENCES IN MORPHOLOGICAL CHARACTERISTICS BETWEEN JUNIOR BASKETBALL PLAYERS WHO HAVE DIFFERENT LEVELS OF EXPLOSIVE STRENGTH

    Directory of Open Access Journals (Sweden)

    Nedim Sisic

    2014-06-01

    Full Text Available Introduction: The aim of this study was to determine differences in morphological characteristics between junior basketball players who have different levels of explosive strength. Methods: The study was conducted on a sample of 84 junior basketball players from (B&H Bosnia and Herzegovina (16-18 years in spring 2013th. The sample of morphological variables consited of: body height, leg length, body weight, upper arm girth in extension, calf girth, triceps skinfold, abdominal skinfold, front thigh skinfold, BMI, the relative body fat percentage. The variables of explosive strength were: vertical jump (VJ, broad jump (BJ and throwing a medicine ball from chest with 3 kg from a standing position. Ward's method of cluster analysis, based on variables of explosive strength we formed four homogeneous groups. Subsequently, using the ANOVA and post-hoc analysis, these groups are differentiated with regard to morphological characteristics. Results: Clusters differed significantly in BJ and VJ. ANOVA found significant differences between clusters in variables of skinfolds, such as the: triceps, abdomen and thigh. Discussion: Defined the influence of morphological variables on explosive strength can be regarded as expected, given that it is primarily about a negative influence of the amount of body fat on relative explosive strength type. This research has shown that junior basketball players in B&H are shorter and ligther when compared to top-level European juniors (Jelicic et al., 2002. Subjects with the lowest skinfolds of the upper limbs and body weight, achieved the best results in the manifestation of relative explosive strength, which has so far rarely been found in samples of trained subjects (Milanese et al., 2010. Possible explanations can be required in a number of training, the intensity and quality of training. Although at this point with certainty, we can't determine on which of these factors involved. This can be confirmed by the results of

  11. Effect of nano-SiO2 particles and curing time on development of fiber-matrix bond properties and microstructure of ultra-high strength concrete

    International Nuclear Information System (INIS)

    Wu, Zemei; Khayat, Kamal Henri; Shi, Caijun

    2017-01-01

    Bond properties between fibers and cementitious matrix have significant effect on the mechanical behavior of composite materials. In this study, the development of steel fiber-matrix interfacial bond properties in ultra-high strength concrete (UHSC) proportioned with nano-SiO 2 varying between 0 and 2%, by mass of cementitious materials, was investigated. A statistical model relating either bond strength or pullout energy to curing time and nano-SiO 2 content was proposed by using the response surface methodology. Mercury intrusion porosimetry (MIP) and backscatter scanning electron microscopy (BSEM) were used to characterize the microstructure of the matrix and the fiber-matrix interface, respectively. Micro-hardness around the embedded fiber and hydration products of the matrix were evaluated as well. Test results indicated that the optimal nano-SiO 2 dosage was 1% in terms of the bond properties and the microstructure. The proposed quadratic model efficiently predicted the bond strength and pullout energy with consideration of curing time and nano-SiO 2 content. The improvement in bond properties associated with nano-silica was correlated with denser matrix and/or interface and stronger bond and greater strength of hydration products based on microstructural analysis.

  12. Flexural Strength of Carbon Fiber Reinforced Polymer Repaired Cracked Rectangular Hollow Section Steel Beams

    Directory of Open Access Journals (Sweden)

    Tao Chen

    2015-01-01

    Full Text Available The flexural behavior of rectangular hollow section (RHS steel beams with initial crack strengthened externally with carbon fiber reinforced polymer (CFRP plates was studied. Eight specimens were tested under three-point loading to failure. The experimental program included three beams as control specimens and five beams strengthened with CFRP plates with or without prestressing. The load deflection curves were graphed and failure patterns were observed. The yield loads and ultimate loads with or without repairing were compared together with the strain distributions of the CFRP plate. It was concluded that yield loads of cracked beams could be enhanced with repairing. Meanwhile, the ultimate loads were increased to some extent. The effect of repair became significant with the increase of the initial crack depth. The failure patterns of the repaired specimens were similar to those of the control ones. Mechanical clamping at the CFRP plate ends was necessary to avoid premature peeling between the CFRP plate and the steel beam. The stress levels in CFRP plates were relatively low during the tests. The use of prestressing could improve the utilization efficiency of CFRP plates. It could be concluded that the patching repair could be used to restore the load bearing capacity of the deficient steel beams.

  13. A Study on the Response Characteristics of a Fiber-Optic Radiation Sensor Model Based on Cerenkov Principle

    Energy Technology Data Exchange (ETDEWEB)

    Han, Hwa Jeong; Kim, Beom Kyu; Park, Byung Gi [Soonchunhyang Univ., Asan (Korea, Republic of)

    2016-10-15

    In recent year, various fiber-optic radiation sensors using Cerenkov principle have been developed without employing any scintillators for measuring high-energy photon, electron, etc. The main advantages of the optical fibers are the remote transmission of the light signal and immunity to pressure and electromagnetic waves. Therefore, the sensors utilizing the optical fibers can be used in hazardous radiation environments, such as the high-level radiation areas of a nuclear facility. The study to be simulated a fiber-optic radiation sensor based on Cerenkov principle and to be analyzed the response characteristics of the sensor. For the aforementioned study, the GEANT simulation toolkit was used. It is able to take into all the optical properties of fibers and is found to be appropriate to realistically describe the response of fiber-optic radiation sensor. In the recently, the fiber-optic radiation sensor have been developed in nuclear industry. Because sensor can detect gamma ray in harsh nuclear environments. In this study, we analyzed response characteristics of the fiber-optic radiation sensor. We have simulated the Monte Carlo model, for detecting the Cerenkov radiation using the fiber-optic radiation sensor. And the y-axis distribution of Cerenkov photons was obtained using output file. Simulation is performed with reference to the method of the previous research, and then the simulation results exhibited a good agreement with the previous research.

  14. A Study on the Response Characteristics of a Fiber-Optic Radiation Sensor Model Based on Cerenkov Principle

    International Nuclear Information System (INIS)

    Han, Hwa Jeong; Kim, Beom Kyu; Park, Byung Gi

    2016-01-01

    In recent year, various fiber-optic radiation sensors using Cerenkov principle have been developed without employing any scintillators for measuring high-energy photon, electron, etc. The main advantages of the optical fibers are the remote transmission of the light signal and immunity to pressure and electromagnetic waves. Therefore, the sensors utilizing the optical fibers can be used in hazardous radiation environments, such as the high-level radiation areas of a nuclear facility. The study to be simulated a fiber-optic radiation sensor based on Cerenkov principle and to be analyzed the response characteristics of the sensor. For the aforementioned study, the GEANT simulation toolkit was used. It is able to take into all the optical properties of fibers and is found to be appropriate to realistically describe the response of fiber-optic radiation sensor. In the recently, the fiber-optic radiation sensor have been developed in nuclear industry. Because sensor can detect gamma ray in harsh nuclear environments. In this study, we analyzed response characteristics of the fiber-optic radiation sensor. We have simulated the Monte Carlo model, for detecting the Cerenkov radiation using the fiber-optic radiation sensor. And the y-axis distribution of Cerenkov photons was obtained using output file. Simulation is performed with reference to the method of the previous research, and then the simulation results exhibited a good agreement with the previous research

  15. The effect of joint surface contours and glass fiber reinforcement on the transverse strength of repaired acrylic resin: An in vitro study

    Directory of Open Access Journals (Sweden)

    Nayana Anasane

    2013-01-01

    Full Text Available Background : Denture fracture is an unresolved problem in complete denture prosthodontics. However, the repaired denture often experiences a refracture at the repaired site due to poor transverse strength. Hence, this study was conducted to evaluate the effect of joint surface contours and glass fiber reinforcement on the transverse strength of repaired acrylic resins. Materials and Methods: A total of 135 specimens of heat polymerized polymethyl methacrylate resin of dimensions 64 × 10 × 2.5 mm were fabricated. Fifteen intact specimens served as the control and 120 test specimens were divided into four groups (30 specimens each, depending upon the joint surface contour (butt, bevel, rabbet and round, with two subgroups based on type of the repair. Half of the specimens were repaired with plain repair resin and the other half with glass fibers reinforced repair resin. Transverse strength of the specimens was determined using three-point bending test. The results were analyzed using one-way ANOVA and Tukey post-hoc test (α= 0.05. Results: Transverse strength values for all repaired groups were significantly lower than those for the control group ( P < 0.001 (88.77 MPa, with exception of round surface design repaired with glass fiber reinforced repair resin (89.92 MPa which was significantly superior to the other joint surface contours ( P < 0.001. Glass fiber reinforced resin significantly improved the repaired denture base resins as compared to the plain repair resin ( P < 0.001. Conclusion: Specimens repaired with glass fiber reinforced resin and round surface design exhibited highest transverse strength; hence, it can be advocated for repair of denture base resins.

  16. Study on magnetic fluid optical fiber devices for optical logic operations by characteristics of superparamagnetic nanoparticles and magnetic fluids

    International Nuclear Information System (INIS)

    Chieh, J. J.; Hong, C. Y.; Yang, S. Y.; Horng, H. E.; Yang, H. C.

    2010-01-01

    We propose two optical fiber-based schemes using two magnetic fluid optical fiber modulators in series or in parallel for optical logic signal processing and operation. Here, each magnetic fluid optical fiber modulator consists of a bare multimode fiber surrounded by magnetic fluid in which the refractive index is adjustable by applying external magnetic fields amplifying the input electrical signal to vary the transmission intensity of the optical fiber-based scheme. The physical mechanisms for the performances of the magnetic fluid optical fiber devices, such as the transmission loss related to Boolean number of the logic operation as well as the dynamic response, are studied by the characteristics of superparamagnetic nanoparticles and magnetic fluids. For example, in the dynamic response composed of the retarding and response sub-procedures except the response times of the actuation coil, the theoretical evaluation of the retarding time variation with cladding magnetic fluids length has good agreement with the experimental results.

  17. Fiber

    Science.gov (United States)

    ... meals instead of white rice. Add beans (kidney, black, navy, and pinto) to rice dishes for even more fiber. Spice up salads with berries and almonds, chickpeas, cooked artichokes, and beans (kidney, black, navy, or pinto). Use whole-grain (corn or ...

  18. Ultimate strength, low stress creep characteristics, and thermal intercept methods for an epoxy fiberglass tension member support

    International Nuclear Information System (INIS)

    Niemann, R.C.; Gonczy, J.D.; Hoffman, J.A.; Mataya, K.F.; Smelser, P.; Young, W.C.

    1979-01-01

    A support system utilizing epoxy fiberglass tension members will be used for the UTSI Superconducting Dipole Magnet. Elements of a support system have a basic member which is a link in which a composite is wound around a mandrel. This element uses the strength of the material fibers in a most advantageous way. The flexural and torsional load imputs to the link at its end must be minimized. A spherical bearing with a cylindrical outer surface functions as the central pin. Experience gained in the application with emphasis on tension member material, ultimate strength, creep, and heat intercepts is presented

  19. Speed-strength abilities and morphological characteristics of basketball players aged 10 and 11

    Directory of Open Access Journals (Sweden)

    Đorđević Alen

    2016-01-01

    Full Text Available The aim of this study was to identify several morphological characteristics and speed-strength abilities in basketball players aged 10 and 11, and to determine possible differences between them, connected with their age. The research was conducted on a sample of 84 young basketball players aged 10 (N=46 and 11 (N=38. The following motor variables were measured: shoulder explosiveness (throwing the ball from basketball position, leg explosiveness (vertical jump, speed strength of the trunk (sit up exercises in 10 seconds, stamina in speed strength of the trunk (sit up exercises in 30 seconds, the speed of changing the direction of moving (agility T-test, acceleration (running for 5 and 20 meters. The following morphological variables were also measured: body height, body mass, percentage of body fat and percentage of muscle tissue. Eleven-year-olds achieved better results than the ten-year-olds in all categories. Statistically significant differences (p<0.01 between the two groups of subjects were found in body height, percentage of muscle tissue in the body, shoulder explosiveness, as well as in the speed of changing the direction of moving. Differences in body mass and ability for acceleration were found on the level of statistical significance (p<0.05.

  20. Effects of conventional welding and laser welding on the tensile strength, ultimate tensile strength and surface characteristics of two cobalt-chromium alloys: a comparative study.

    Science.gov (United States)

    Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

    2012-06-01

    The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt-chromium alloy. Samples were prepared with two commercially available cobalt-chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scanning electron microscope to evaluate the surface characteristics at the welded site. Both on laser welding as well as on conventional welding technique, Diadur alloy samples showed lesser values when tested for tensile and ultimate tensile strength when compared to Wironium alloy samples. Under the scanning electron microscope, the laser welded joints show uniform welding and continuous molt pool all over the surface with less porosity than the conventionally welded joints. Laser welding is an advantageous method of connecting or repairing cast metal prosthetic frameworks.

  1. Effects of the addition of mechanically deboned poultry meat and collagen fibers on quality characteristics of frankfurter-type sausages.

    Science.gov (United States)

    Pereira, Anirene Galvão Tavares; Ramos, Eduardo Mendes; Teixeira, Jacyara Thaís; Cardoso, Giselle Pereira; Ramos, Alcinéia de Lemos Souza; Fontes, Paulo Rogério

    2011-12-01

    The effects of mechanically deboned poultry meat (MDPM) and levels of collagen fibers on comminuted, cooked sausage quality characteristics were investigated using the central composite rotatable design of response surface methodology (RSM). Use of collagen fiber as an additive affected the sausage characteristics, but the effect depended on the amount of the MDPM used. While MDPM additions resulted in higher cooking loss and darker and redder frankfurters, the addition of collagen fibers improved cooking yields and contributed to the lightness of the final product. Higher collagen fiber content was also accompanied by a significant increase in frankfurter hardness regardless of the MDPM content. Use of collagen fibers countered the negative effects of MDPM on sausage quality attributes, especially on cooking yields and final product color. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Influence of aramid fiber moisture regain during atmospheric plasma treatment on aging of treatment effects on surface wettability and bonding strength to epoxy

    International Nuclear Information System (INIS)

    Ren Yu; Wang Chunxia; Qiu Yiping

    2007-01-01

    One of the main differences between a low-pressure plasma treatment and an atmospheric pressure plasma treatment is that in atmosphere, the substrate material may absorb significant amount of water which may potentially influence the plasma treatment effects. This paper investigates how the moisture absorbed by aramid fibers during the atmospheric pressure plasma treatment influences the aging behavior of the modified surfaces. Kevlar 49 fibers with different moisture regains (MR) (0.5, 3.5 and 5.5%, respectively) are treated with atmospheric pressure plasma jet (APPJ) with helium as the carrier gas and oxygen as the treatment gas. Surface wettability and chemical compositions, and interfacial shear strengths (IFSS) to epoxy for the aramid fibers in all groups are determined using water contact angle measurements, X-ray photoelectron spectroscopy (XPS), and micro-bond pull out tests, respectively. Immediately after the plasma treatment, the treated fibers have substantially lower water contact angles, higher surface oxygen and nitrogen contents, and larger IFSS to epoxy than those of the control group. At the end of 30 day aging period, the fibers treated with 5.5% moisture regain had a lower water contact angle and more polar groups on the fiber surface, leading to 75% improvement of IFSS over the control fibers, while those for the 0.5 and 3.5% moisture regain groups were only 30%

  3. Refractive index and temperature-sensing characteristics of a cladding-etched thin core fiber interferometer

    Science.gov (United States)

    Wang, Weiying; Dong, Xinran; Chu, Dongkai; Hu, Youwang; Sun, Xiaoyan; Duan, Ji-An

    2018-05-01

    A high refractive index (RI) sensor based on an in-line Mach-Zehnder mode interferometer (MZI) is proposed. The sensor was realized by splicing a 2-cm length of cladding-etched thin core fiber (TCF) between two single mode fibers (SMFs). The TCF-structured MZI exhibited good fringe visibility as high as 15 dB in air and the high RI sensitivity attained a value of 1143.89 nm/RIU at a RI of 1.447. The experimental data revealed that the MZI has high RI sensitivity after HF etching realizing 2599.66 nm/RIU. Studies were performed on the temperature characteristics of the device. It is anticipated that this high RI sensor will be deployed in new and diverse applications in the chemical and biological fields.

  4. Sensing Characteristics of Side-Hole Fiber-Based Long-Period Grating

    Directory of Open Access Journals (Sweden)

    Yi Xin

    2013-01-01

    Full Text Available Long-period gratings (LPGs have been fabricated in a side-hole fiber (SHF by using a pulsed CO2 laser. Sensing characteristics of this SHF-LPG to temperature surrounding refractive index and bend have been investigated. Experimental results show that resonant wavelength of the SHF-LPG has a blue shift with temperature with sensitivity of −0.11 nm/°C, a blue shift with increasing sensitivity with surrounding refractive index ranging from 1.335 to 1.44 (the maximum sensitivity is achieved when the surrounding refractive index reaches the effective index of the fiber cladding, and a red shift with bend-direction-dependent sensitivity up to 9.36 nm/m−1.

  5. Determination of deformation and strength characteristics of artificial geomaterial having step-shaped discontinuities under uniaxial compression

    Science.gov (United States)

    Tsoy, PA

    2018-03-01

    In order to determine the empirical relationship between the linear dimensions of step-shaped macrocracks in geomaterials as well as deformation and strength characteristics of geomaterials (ultimate strength, modulus of deformation) under uniaxial compression, the artificial flat alabaster specimens with the through discontinuities have been manufactured and subjected to a series of the related physical tests.

  6. Effects of dietary fibers with different fermentation characteristics on feeding motivation in adult female pigs.

    Science.gov (United States)

    Souza da Silva, Carol; Bolhuis, J Elizabeth; Gerrits, Walter J J; Kemp, Bas; van den Borne, Joost J G C

    2013-02-17

    Dietary fibers can be fermented in the colon, resulting in production of short-chain fatty acids (SCFA) and secretion of satiety-related peptides. Fermentation characteristics (fermentation kinetics and SCFA-profile) differ between fibers and could impact their satiating potential. We investigated the effects of fibers with varying fermentation characteristics on feeding motivation in adult female pigs. Sixteen pair-housed pigs received four diets in four periods in a Latin square design. Starch from a control (C) diet was exchanged, based on gross energy, for inulin (INU), guar gum (GG), or retrograded tapioca starch (RS), each at a low (L) and a high (H) inclusion level. This resulted in a decreased metabolizable energy intake when feeding fiber diets as compared with the C diet. According to in vitro fermentation measurements, INU is rapidly fermentable and yields relatively high amounts of propionate, GG is moderately rapidly fermentable and yields relatively high amounts of acetate, and RS is slowly fermentable and yields relatively high amounts of butyrate. Feeding motivation was assessed using behavioral tests at 1h, 3h and 7h after the morning meal, and home pen behavioral observations throughout the day. The number of wheel turns paid for a food reward in an operant test was unaffected by diet. Pigs on H-diets ran 25% slower for a food reward in a runway test than pigs on L-diets, and showed less spontaneous physical activity and less stereotypic behavior in the hours before the afternoon meal, reflecting increased interprandial satiety. Reduced feeding motivation with increasing inclusion level was most pronounced for RS, as pigs decreased speed in the runway test and tended to have a lower voluntary food intake in an ad libitum food intake test when fed RS-H. In conclusion, increasing levels of fermentable fibers in the diet seemed to enhance satiety in adult pigs, despite a reduction in metabolizable energy supply. RS was the most satiating fiber

  7. Effect of post space treatment with adhesives on the push-out bond strength of fiber posts luted with self-adhesive resin cements

    Directory of Open Access Journals (Sweden)

    Tufan Can Okay

    2017-01-01

    Full Text Available Objective: The aim of this study was to evaluate the push-out bond strength of fiber posts used in the restoration of endodontically-treated teeth with extreme material loss, luted with two different self-adhesive resin cements alone or with the combination of an adhesive. Materials and Method: The post spaces of 80 extracted mandibular first premolar roots were prepared and divided into 4 experimental groups according to fiber post (RelyX Fiber Post luting material. Group 1 was luted with RelyX Unicem, Group 2 was luted with RelyX Unicem + Adper Easy One, Group 3 was luted with Clearfil SA Cement, and Group 4 was luted with Clearfil SA Cement + S3 Bond. After 24 h and 1 month, horizontal sections of 1 mm thickness were made from the coronal, middle and apical root parts of the fiber posts, and push-out tests were performed. Groups were compared by using one way analysis of variance (ANOVA and Tukey’s HSD post hoc tests and storage periods were compared by using independent samples t-test (α=0.05. Results: For both evaluation time periods, RelyX Unicem + Adper Easy One showed the highest bond strength. Regarding the 24 h period, the lowest bond strength values were found for the apical sections followed by middle and coronal sections. One month results revealed similar bond strength values for the middle and apical sections (p>0.05 which were significantly lower than the values found for the coronal sections (p<0.05. RelyX Unicem + Adper Easy One exhibited greater push-out bonding strength compared to other groups in the middle and apical sections (p<0.05. Conclusion: According to the results of this in vitro study it can be concluded that, using an adhesive system in combination with a self-adhesive resin cement during post cementation may improve the bond strength.

  8. An Assessment of Omani Native Sheep Fiber Production and Quality Characteristics

    Directory of Open Access Journals (Sweden)

    Osman Mahgoub

    2010-01-01

    Full Text Available Wool production and quality measurements were carried out on 100 Omani native female sheep (body weight 38.6 ± 5.5 kg; age 993 ± 488 d. Sheep were kept in partially shaded pens and fed ad libitum Rhodes grass hay (crude protein 8.83% plus a daily amount of 200 g general ruminant concentrate (crude protein 16.5% DM. Animals were shorn once a year and samples were taken from the left mid-side site to determine fleece and fiber characteristics. The scanning electron microscope (SEM was used to study the fine appearance of the wool fibers. A skin sample was used to study the histological arrangement and number of secondary and primary follicles. The greasy fleece weight (GFW in Omani sheep ranged between 0.50- 2.65 kg (mean 1.12 ± 0.43 kg and the GFW expressed as a percentage of BW ranged between 1.0-7.6 with a mean of 2.9 ± 1.16. Clean wool yield in Omani sheep fleece ranged between 57.1 and 88.4% with a mean of 76.4 ± 7.6. Omani sheep fleece contained various staple shapes and had a mean staple length of 22.9 ± 1.16 cm, 4.3 ± 0.8 crimps per staple; and a mean fiber diameter of 46 ± 12 µm. Electron microscopy revealed three types of fibers; wrap-around, angled type and polygonal and elongated scales. This study indicated a wide variation in the wool characteristics of Omani native sheep fleece, which suggested that selection may be employed to improve wool production and quality in these sheep.

  9. Effect of ultraviolet light irradiation period on bond strengths between fiber-reinforced composite post and core build-up composite resin.

    Science.gov (United States)

    Asakawa, Yuya; Takahashi, Hidekazu; Iwasaki, Naohiko; Kobayashi, Masahiro

    2014-01-01

    The aim of the present study was to characterize the effects of the ultraviolet light (UV) irradiation period on the bond strength of fiber-reinforced composite (FRC) posts to core build-up resin. Three types of FRC posts were prepared using polymethyl methacrylate, urethane dimethacrylate, and epoxy resin. The surfaces of these posts were treated using UV irradiation at a distance of 15 mm for 0 to 600 s. The pull-out bond strength was measured and analyzed with the Dunnett's comparison test (α=0.05). The bond strengths of the post surfaces without irradiation were 6.9 to 7.4 MPa; those after irradiation were 4.2 to 26.1 MPa. The bond strengths significantly increased after 15 to 120-s irradiation. UV irradiation on the FRC posts improved the bond strengths between the FRC posts and core build-up resin regardless of the type of matrix resin.

  10. Evaluation of Strength Characteristics of Laterized Concrete with Corn Cob Ash (CCA) Blended Cement

    Science.gov (United States)

    Ikponmwosa, E. E.; Salau, M. A.; Kaigama, W. B.

    2015-11-01

    Agricultural wastes are dumped in landfills or left on land in which they constitute nuisance. This study presents the results of investigation of strength characteristics of reinforced laterized concrete beams with cement partially replaced with corn cob (agricultural wastes) ash (CCA). Laterized concrete specimen of 25% laterite and 75% sharp sand were made by blending cement with corn cob ash at 0 to 40% in steps of 10%. A concrete mix ratio of 1:2:4 was used to cast 54 cubes of 150×150×150mm size and 54 beams of dimension 750×150×150mm. The results show that the consistency and setting time of cement increased as the percentage replacement of cement with CCA increased while the workability and density of concrete decreased as the percentage of CCA increased. There was a decrease in compressive strength when laterite was introduced to the concrete from 25.04 to 22.96N/mm2 after 28 days and a continual reduction in strength when CCA was further added from 10% to 40% at steps of 10%. Generally, the beam specimens exhibited majorly shear failure with visible diagonal cracks extending from support points to the load points. The corresponding central deflection in beams, due to two points loading, increased as the laterite was added to the concrete mix but reduced and almost approaching that of the control as 10% CCA was added. The deflection then increased as the CCA content further increased to 20%, 30% and 40% in the mix. It was also noted that the deflection of all percentage replacement including 40% CCA is less than the standard recommended maximum deflection of the beam. The optimal flexural strength occurred with 10% CCA content.

  11. Age related differences of selected Hatha yoga practices on anthropometric characteristics, muscular strength and flexibility of healthy individuals

    Directory of Open Access Journals (Sweden)

    Kaushik Halder

    2015-01-01

    Summary and Conclusion: Hatha yoga can improve anthropometric characteristics, muscular strength and flexibility among volunteers of different age group and can also be helpful in preventing and attenuating age related deterioration of these parameters.

  12. Characteristics of upper extremity's muscle strength in Turkish national wheelchair basketball players team.

    Science.gov (United States)

    Akınoğlu, Bihter; Kocahan, Tuğba

    2017-02-01

    The objective of this study was to reveal characteristics of muscle strength of upper extremities of wheelchair (WC) basketball players and to ensure more-specific training program preparation. Isokinetic muscle strength of 12 WC basketball players were assessed by ISOMED 2000 device. The assessment protocol was evaluated at 60°/sec velocity with 5 times repeated force and at 240°/sec with 15 times repeated force. This protocol was carried out individually for shoulder flexion-extension and wrist flexion-extension movements at the right and left extremities. The flexion/extension ratio was determined to be outside of the ratios accepted as normal for primarily shoulder joint and for wrist joint. The extension movement was stronger than flexion movement in the shoulders at both velocities and the flexion movement was stronger than ex-tension movement in the wrist. The repeat times where the peak torque occurred were 2-3 repeats at 60°/sec velocity during flexion and extension movements for the wrist and shoulders, and the peak torque occurred at an average of 5-6 repeats in the shoulders at 240°/sec velocity and it occurred at 3-4 repeats in the wrist. The angles where the peak torque of the shoulder flexion and extension occurred varied between 80°-115° at both velocities, and it varied between 5°-30° angles for the wrist. As this study revealed, determination of muscle strength characteristics of WC athletes and especially using objective isokinetic devices will guide the planning of the appropriate training and exercise programs and preventing sports injuries in long term.

  13. A new concept for design of fibered high strength reinforced concrete elements using ultimate limit state method

    International Nuclear Information System (INIS)

    Iskhakov, I.; Ribakov, Y.

    2013-01-01

    Highlights: • A new concept for design of two layer reinforced concrete beams is proposed. • Concrete class and section height of bending elements are calculated. • Good correlation between experimental and numerical results is obtained. - Abstract: Existing methods for design of reinforced concrete (RC) bending elements in the ultimate limit state are based on calculating the compressed zone depth of the section. At the same time, in isotropic materials the neutral axis of the bending section crosses its center of gravity (CG). It was proved that if a neutral axis of bending RC element crosses the section’s CG, the total reinforcement section (A s +A s ′ ) is minimal. Therefore the compressed zone depth should be selected so that under the design load the neutral axis should pass through the section’s CG. In this case the compressed zone depth that is unknown in existing design methods becomes a known value. This concept enables to select other parameters as unknowns (bending element concrete class, section height, etc.). It is especially important for design of modern high strength concrete (HSC) bending elements, for which the concrete class can be calculated, but not selected. It is demonstrated that applying the proposed concept enables to assume that the neutral axis location is constant for all stages of stress - strain state in bending. As HSC is rather brittle, stresses diagram in the compressed section zone has a form close to triangular. However, adding steel fibers allows improving the elastic–plastic properties of HSC. In this case a rectangular stresses diagram can be used, as for normal strength concrete. Consequently, the proposed concept yields more economical solutions and allows more effective using the HSC properties

  14. Evaluation of the resin cement thicknesses and push-out bond strengths of circular and oval fiber posts in oval-shapes canals

    Science.gov (United States)

    Er, Özgür; Kılıç, Kerem; Kılınç, Halil İbrahim; Sağsen, Burak

    2015-01-01

    PURPOSE The aim of this study was to evaluate whether the push-out bond strength varies between oval and circular fiber posts, and to examine the effect on the resin cement thicknesses around the posts. MATERIALS AND METHODS Eighteen mandibular premolar roots were separated into two groups for oval and circular fiber posts systems. Post spaces were prepared and fiber posts were luted to the post spaces. Roots were cut horizontally to produce 1-mm-thick specimens. Resin cement thicknesses were determined with a metallographic optical microscope and push-out tests were done. RESULTS No significant differences were observed in terms of push-out bond strength between the oval and circular fiber posts (P>.05) The resin cement thicknesses of the oval posts were greater than those of the circular posts group in the coronal, middle and apical specimens (P<.05). CONCLUSION In the light of these results, it can be stated that resin cement thickness does not affect the push-out bond strength. PMID:25722832

  15. Comparison of Open-Hole Compression Strength and Compression After Impact Strength on Carbon Fiber/Epoxy Laminates for the Ares I Composite Interstage

    Science.gov (United States)

    Hodge, Andrew J.; Nettles, Alan T.; Jackson, Justin R.

    2011-01-01

    Notched (open hole) composite laminates were tested in compression. The effect on strength of various sizes of through holes was examined. Results were compared to the average stress criterion model. Additionally, laminated sandwich structures were damaged from low-velocity impact with various impact energy levels and different impactor geometries. The compression strength relative to damage size was compared to the notched compression result strength. Open-hole compression strength was found to provide a reasonable bound on compression after impact.

  16. Characteristics of regenerated nanocellulosic fibers from cellulose dissolution in aqueous solutions for wood fiber/polypropylene composites

    Science.gov (United States)

    Sangyeob Lee; Hui Pan; Chung Y. Hse; Alfred R. Gunasekaran; Todd F. Shupe

    2014-01-01

    The effects of aqueous solutions were evaluated on the properties of regenerated cellulosic nanofibers prepared from pure cellulose fibers in various formulations of aqueous solutions. Thermoplastic composites were prepared with reinforcement of the regenerated cellulosic nanofibers. The regenerated cellulosic fibers from cellulosic woody biomass were obtained from...

  17. Relationships between maximal strength of lower limb, anthropometric characteristics and fundamental explosive performance in handball players.

    Science.gov (United States)

    Hermassi, Souhail; Chelly, Mohamed Souhaiel; Wagner, Herbert; Fieseler, Georg; Schulze, Stephan; Delank, Karl-Stefan; Shephard, Roy J; Schwesig, René

    2018-02-14

     The purpose of this study was to examine relationships between lower body muscular strength, anthropometric characteristics and several measures of explosive performance in elite team-handball players.  22 male elite team-handball players (age: 19.1 ± 1.7 years) were studied during the competitive season. Standard anthropometric and body composition measures included body mass index, lower limb and thigh muscle volume, and body fat percentage. Maximal leg strength was determined by a one-repetition maximum (1-RM) half back-squat. Vertical jump performance was assessed using a squat jump (SJ) and a counter movement jump (CMJ). Repeated shuttle-sprint ability (RSA) was tested by 6 (2 × 15 m) shuttle sprints with 20 s of active recovery intervals. The best time in a single shuttle sprint (30m; RSA best ), fastest total time (RSA TT ) and RSA test performance decrement (RSA dec ) were recorded. Agility was measured using a modified T-half test (MAT). Throwing velocities of jump shooting and 3-step throwing were recorded by digital video camera.  The explained variance of 1-RM half-back-squats ranged from 0.2 % (RSA% Fatigue Index) to 70.1 % (CMJ). Four out of 8 variables (RSA Best Time, CMJ, SJ, throwing velocity of jump shoot) demonstrated an r 2  > 0.5. Jump performances seemed closely related to 1-RM half-back-squats. Furthermore, 1-RM half-back-squats were positively correlated with leg and thigh muscle volumes (r = 0.652, r = 0.768).  The anthropometric characteristics and some physical performance tests are closely related to the maximal strength performance of handball players. Coaches should focus on maximal strength training programs for the lower limbs when seeking improvements in the throwing velocity and jump performance of handball players. © Georg Thieme Verlag KG Stuttgart · New York.

  18. The covariability of North American land-atmosphere coupling strength and rainfall characteristics in reanalyses

    Science.gov (United States)

    Ferguson, C. R.; Roundy, J. K.; Kim, W.

    2016-12-01

    The GEWEX North American Regional Hydroclimate Project (RHP): Water for the Food Baskets of the World initiative is aimed at: improving understanding of key processes—both natural and anthropogenic—that determine water availability, improving understanding of the independent and collective sensitivity of these processes to local and global change, and the integration of knowledge gained into the next model development cycle for the benefit of improved water availability forecasts. Considering that the agricultural sector accounts for three quarters of water withdrawals and suffers the brunt of drought-related financial damages, a rational RHP focal point is subseasonal-to-seasonal forecast skill. Forecasts on this timescale over the Great Plains food basket have shown particular sensitivity to land initial conditions (i.e., soil moisture, snow cover, and vegetative stress) and the realism of modeled land-atmosphere (L-A) coupling. L-A coupling strength denotes the degree to which the model's land scheme (i.e., soil column memory and surface flux partitioning) affect the atmospheric forecast scheme's daytime evolution of the convective boundary layer, including cloud development and precipitation. Prior studies have connected L-A coupling strength to the phase and amplitude of the diurnal precipitation cycle, as well as the evolution of heatwaves and drought. In this study, we apply three metrics of L-A coupling strength: soil moisture memory, the two-legged coupling metric, and the convective triggering potential-humidity index, to the 161-year NOAA-Cooperative Institute for Research in Environmental Sciences Twentieth Century Reanalysis (20CRV2c). Over the full period, we also analyze warm-season rainfall characteristics and subsequently perform statistical trend and change point analyses on both sets of results. We test the stationarity of both coupling and rainfall characteristics as well as the hypothesis that any detected shifts in coupling strength and

  19. Thermo-optic characteristics of hybrid polymer/silica microstructured optical fiber: An analytical approach

    Science.gov (United States)

    Sharma, Dinesh Kumar; Sharma, Anurag; Tripathi, Saurabh Mani

    2018-04-01

    Microstructured optical fibers (MOFs) allow a variety of advanced materials to be infiltrated in their air-voids for obtaining the increased fiber functionality, and offering a new versatile platform for developing the compact sensors devices. We aim to investigate the thermal characteristics of high-index core triangular hybrid polymer/silica MOFs with circular air-voids infused with polymer by using the analytical field model [1]. We demonstrate that infiltration of air-voids with polymer, e.g., polydimethylsiloxane (PDMS) can facilitate to tune the fundamental modal properties of MOF such as effective index of the mode, near and the far-field profiles, effective mode area and the numerical aperture over the temperature ranging from 0 °C to 100 °C, for different values of relative air-void ratios. The evolution of the mode shape for a given temperature has been investigated in transition from near-field to far-field regime. We have studied the thermal dependence of splice losses between hybrid MOF and the standard step-index single-mode optical fiber in combination with Fresnel losses. For enhancing the evanescent field interactions, we have evaluated fraction of power associated with fundamental mode of hybrid MOF. We have compared the accuracy of our results with those based on full-vector finite-difference (FD) method, as available in the literature.

  20. Swimming Characteristics of Bioinspired Helical Microswimmers Based on Soft Lotus-Root Fibers

    Directory of Open Access Journals (Sweden)

    Jia Liu

    2017-11-01

    Full Text Available Various kinds of helical swimmers inspired by E. coli bacteria have been developed continually in many types of researches, but most of them are proposed by the rigid bodies. For the targeted drug delivery, the rigid body may hurt soft tissues of the working region with organs. Due to this problem, the biomedical applications of helical swimmers may be restricted. However, the helical microswimmers with the soft and deformable body are appropriate and highly adaptive in a confined environment. Thus, this paper presents a lotus-root-based helical microswimmer, which is fabricated by the fibers of lotus-root coated with magnetic nanoparticles to active under the magnetic fields. The helical microstructures are derived from the intrinsic biological structures of the fibers of the lotus-root. This paper aims to study the swimming characteristic of lotus-root-based microswimmers with deformable helical bodies. In the initial step under the uniform magnetic actuation, the helical microswimmers are bent lightly due to the heterogeneous distribution of the internal stress, and then they undergo a swimming motion which is a spindle-like rotation locomotion. Our experiments report that the microswimmers with soft bodies can locomote faster than those with rigid bodies. Moreover, we also find that the curvature of the shape decreases as a function of actuating field frequency which is related to the deformability of lotus-root fibers.

  1. Weathering effects on tensile and stress rupture strength of glass fiber reinforced vinylester and epoxy thermoset pipes

    Science.gov (United States)

    Nizamuddin, Syed

    Glass fiber reinforced vinylester (GFRE) and epoxy (GFRE) pipes have been used for more than three decades to mitigate corrosion problems in oil fields, chemical and industrial plants. In these services, both GFRV and GFRE pipes are exposed to various environmental conditions. Long-term mechanical durability of these pipes after exposure to environmental conditions, which include natural weathering exposure to seasonal temperature variation, sea water, humidity and other corrosive fluids like crude oil, should be well known. Although extensive research has been undertaken, several major issues pertaining to the performance of these pipes under a number of environmental conditions still remain unresolved. The main objective of this study is to investigate the effects of natural weathering, combined natural weathering with seawater and crude oil exposure, for time periods ranging from 3 to 36 months respectively, on the tensile and stress rupture behavior of GFRV and GFRE pipes. Ring specimens are machined from GFRV and GFRE pipes and tested before and after exposure to different weathering conditions prevalent in the eastern region (Dhahran) of Saudi Arabia and present under service conditions. The natural weathering and combined natural weathering with crude oil exposure of GFRV specimens revealed increased tensile strength even after 36 months of exposure when compared with that of the as received samples. However, the combined natural weathering with seawater exposure of GFRV samples revealed better tensile behavior till 24 months of exposure, and after 36 months their tensile strength was seen to be below that of the as received GFRV samples. The stress rupture behavior of natural weather exposed GFRV samples showed an improvement after 12 months of exposure and it decreased after 24 and 36 months of exposure when compared with the as received GFRV samples. The combined natural weathering with crude oil and seawater exposure of GFRV sample revealed improved

  2. Fiber digestion kinetics and protein degradability characteristics of stockpiled Tifton 85 bermudagrass.

    Science.gov (United States)

    Sechler, S R; Mullenix, M K; Holland, C M; Muntifering, R B

    2017-09-01

    A 2-yr study was conducted to determine effects of N fertilization level on fiber digestion kinetics and protein degradability characteristics of stockpiled Tifton 85 bermudagrass (T85). Six 0.76-ha pastures of stockpiled T85 were cut to a 10-cm stubble height on August 1 of each yr and fertilized with 56 (56N), 112 (112N), or 168 (168N) kg N/ha (2 pastures/treatment). Fiber digestion kinetics included the 72-hr potential extent of NDF digestion (PED), rate of NDF digestion, and lag time. In yr 1 and 2, PED decreased over the stockpile season. Rates of NDF digestion did not differ ( > 0.05) among N fertilization treatments in either yr. In yr 1, rate of NDF digestion was greatest ( digestion decreased ( digestion rates were similar for November and January 21 sampling dates. Lag time was greater ( digestion ( = -0.60 and -0.25 in yr 1 and 2, respectively) was observed. There was a trend ( = 0.06) for lignin concentration to be positively correlated with lag time ( = 0.39) in yr 1, and a strong relationship was observed in yr 2 ( = 0.91; digestion in stockpiled T85 were influenced more by temporal changes over the stockpile season than by N fertilization level. Supplement formulations based on kinetic parameters of fiber digestion may require periodic adjustment to insure that energy-yielding components of NDF are sufficient to meet animal requirements throughout the stockpile season. The CP fraction in stockpiled T85 contains sufficient RDP to support fibrolytic activity and growth of ruminal microorganisms throughout the stockpile season. Toward the latter end of the season, supplementation with sources of digestible fiber and RDP could be expected to increase MP supply to the host animal.

  3. Aggregate effects on γ-ray shielding characteristics and compressive strength on concrete

    International Nuclear Information System (INIS)

    Oh, Jeong Hwan; Choi, Soo Seok; Mun, Young Bun; Lee, Jae Hyung; Choi, Hyun Kook

    2016-01-01

    We observed the γ-ray shielding characteristics and compressive strength of five types of concrete using general aggregates and high-weight aggregates. The aggregates were classified into fine aggregate and coarse aggregate according to the average size. The experimental results obtained an attenuation coefficient of 0.371 cm-1 from a concrete with the oxidizing slag sand (OSS) and oxidizing slag gravel (OSG) for a γ-ray of "1"3"7Cs, which is improved by 2% compared with a concrete with typical aggregates of sand and gravel. In the unit weight measurement, a concrete prepared by iron ore sand (IOS) and OSG had the highest value of 3,175 kg·m"-"3. Although the unit weight of the concrete with OSS and OSG was 3,052 kg·m"-"3, which was lower than the maximum unit weight condition by 123 kg·m"-"3, its attenuation coefficient was improved by 0.012 cm-1. The results of chemical analysis of aggregates revealed that the magnesium content in oxidizing slag was lower than that in iron ore, while the calcium content was higher. The concrete with oxidizing slag aggregates demonstrated enhanced γ-ray shielding performance due to a relatively high calcium content compared with the concrete with OSS and OSG in spite of a low unit weight. All sample concretes mixed with high-weight aggregates had higher compressive strength than the concrete with typical sand and gravel. When OSS and IOS were used, the highest compressive strength was 50.2 MPa, which was an improvement by 45% over general concrete, which was achieved after four weeks of curing

  4. Aggregate effects on γ-ray shielding characteristics and compressive strength on concrete

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jeong Hwan; Choi, Soo Seok [Jeju National University, Jeju (Korea, Republic of); Mun, Young Bun; Lee, Jae Hyung; Choi, Hyun Kook [Sungshin Cement Co., Ltd, Sejong (Korea, Republic of)

    2016-12-15

    We observed the γ-ray shielding characteristics and compressive strength of five types of concrete using general aggregates and high-weight aggregates. The aggregates were classified into fine aggregate and coarse aggregate according to the average size. The experimental results obtained an attenuation coefficient of 0.371 cm-1 from a concrete with the oxidizing slag sand (OSS) and oxidizing slag gravel (OSG) for a γ-ray of {sup 137}Cs, which is improved by 2% compared with a concrete with typical aggregates of sand and gravel. In the unit weight measurement, a concrete prepared by iron ore sand (IOS) and OSG had the highest value of 3,175 kg·m{sup -3}. Although the unit weight of the concrete with OSS and OSG was 3,052 kg·m{sup -3}, which was lower than the maximum unit weight condition by 123 kg·m{sup -3}, its attenuation coefficient was improved by 0.012 cm-1. The results of chemical analysis of aggregates revealed that the magnesium content in oxidizing slag was lower than that in iron ore, while the calcium content was higher. The concrete with oxidizing slag aggregates demonstrated enhanced γ-ray shielding performance due to a relatively high calcium content compared with the concrete with OSS and OSG in spite of a low unit weight. All sample concretes mixed with high-weight aggregates had higher compressive strength than the concrete with typical sand and gravel. When OSS and IOS were used, the highest compressive strength was 50.2 MPa, which was an improvement by 45% over general concrete, which was achieved after four weeks of curing.

  5. Strengths and Failure Characteristics of Self-Compacting Concrete Containing Recycled Waste Glass Aggregate

    Directory of Open Access Journals (Sweden)

    Rahman Khaleel AL-Bawi

    2017-01-01

    Full Text Available The effects of different proportions of green-colored waste glass (WG cullet on the mechanical and fracture properties of self-compacting concrete (SCC were experimentally investigated. Waste bottles were collected, washed, crushed, and sieved to prepare the cullet used in this study. Cullet was incorporated at different percentages (0%, 20%, 40%, 60%, 80%, and 100% by weight instead of natural fine aggregate (NFA and/or natural coarse aggregate (NCA. Three SCC series were designed with a constant slump flow of 700±30 mm, total binder content of 570 kg/m3 and at water-to-binder (w/b ratio of 0.35. Moreover, fly ash (FA was used in concrete mixtures at 20% of total binder content. Mechanical aspects such as compressive, splitting tensile, and net flexural strengths and modulus of elasticity of SCC were investigated and experimentally computed at 28 days of age. Moreover, failure characteristics of the concretes were also monitored via three-point bending test on the notched beams. The findings revealed that the mechanical properties as well as fracture parameters were adversely influenced by incorporating of WG cullet. However, highest reduction of compressive strength did not exceed 43% recorded at 100% WG replacement level. Concretes containing WG showed less brittle behavior than reference concrete at any content.

  6. Effect of Lime on characteristics of consolidation, strength, swelling and plasticity of fine grained soil

    Science.gov (United States)

    Estabragh, A. R.; Bordbar, A. T.; Parsaee, B.; Eskandari, Gh.

    2009-04-01

    Using Lime as an additive material to clayey soil is one of the best effective technique in building the soil structures to get some purposes such as soil stabilization, soil reinforcement and decreasing soil swelling. In this research the effect of Lime on geotechnical characteristics of a clayey soil was investigated. Soil specimen types used in this study were consisted of clayey soil as the control treatment and clay mixed with different weight fractions of lime, 4, 6, 8 & 10 percent. Some experiments such as CBR, atterburg limits, compaction, consolidation and swelling was conducted on specimens. Results revealed that adding lime to soil would change its physical and mechanical properties. Adding lime increase the compression strength and consolidation coefficient and decrease swelling potential and maximum dry density. According to the results, Atterburg experiments show that presence of lime in soil increase the liquid limit of low plasticity soil and decrease the liquid limit of high plasticity soil, but totally it decreases the plasticity index of soils. Key words: soil stabilization, lime, compression strength, swelling, atterburg limits, compaction

  7. The pore characteristics of geopolymer foam concrete and their impact on the compressive strength and modulus

    Science.gov (United States)

    Zhang, Zuhua; Wang, Hao

    2016-08-01

    The pore characteristics of GFCs manufactured in the laboratory with 0-16% foam additions were examined using image analysis (IA) and vacuum water saturation techniques. The pore size distribution, pore shape and porosity were obtained. The IA method provides a suitable approach to obtain the information of large pores, which are more important in affecting the compressive strength of GFC. By examining the applicability of the existing models of predicting compressive strength of foam concrete, a modified Ryshkevitch’s model is proposed for GFC, in which only the porosity that is contributed by the pores over a critical diameter (>100 μm) is considered. This “critical void model” is shown to have very satisfying prediction capability in the studied range of porosity. A compression-modulus model for Portland cement concrete is recommended for predicting the compression modulus elasticity of GFC. This study confirms that GFC have similar pore structures and mechanical behavior as those Portland cement foam concrete and can be used alternatively in the industry for the construction and insulation purposes.

  8. Thermo-optic characteristic of DNA thin solid film and its application as a biocompatible optical fiber temperature sensor.

    Science.gov (United States)

    Hong, Seongjin; Jung, Woohyun; Nazari, Tavakol; Song, Sanggwon; Kim, Taeoh; Quan, Chai; Oh, Kyunghwan

    2017-05-15

    We report unique thermo-optical characteristics of DNA-Cetyl tri-methyl ammonium (DNA-CTMA) thin solid film with a large negative thermo-optical coefficient of -3.4×10-4/°C in the temperature range from 20°C to 70°C without any observable thermal hysteresis. By combining this thermo-optic DNA film and fiber optic multimode interference (MMI) device, we experimentally demonstrated a highly sensitive compact temperature sensor with a large spectral shift of 0.15 nm/°C. The fiber optic MMI device was a concatenated structure with single-mode fiber (SMF)-coreless silica fiber (CSF)-single mode fiber (SMF) and the DNA-CTMA film was deposited on the CSF. The spectral shifts of the device in experiments were compared with the beam propagation method, which showed a good agreement.

  9. Determination of Terfenol-D magnetostriction characteristics for sensor application using fiber Bragg grating

    Science.gov (United States)

    de Morais Sousa, Kleiton; Zandonay, Ricardo; Vagner da Silva, Erlon; Martelli, Cicero; Cardozo da Silva, Jean Carlos

    2014-08-01

    Electric current sensor based on magnetostriction phenomenon has been reported in several papers. In common these previous papers used a fiber Bragg grating (FBG) to determine the strain of the magnetostrictive material. However, magnetostriction sensors present few disadvantages often neglected, such as the temperature dependence of magnetostriction. In this paper a Terfenol-D rod (a giant magnetostrictive material-GMM) is used for tests. For simultaneous measurement of temperature and strain two multiplexed FBGs are used. The first test presents unipolar characteristics of Terfenol-D magnetostriction. Other test determines the Terfenol-D response for different temperatures. The Terfenol-D sensitivity increase when the temperature increases, however the saturation of the material occurs in small field values. The characteristics presented in this paper must be taken into account in the development of magnetostrictive sensors and its limitations.

  10. Numerical Study on Flow Characteristics of Hollow Fiber Membrane Module for Water Recovery Cooling Tower

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang Cheol; Shin, Weon Gyu [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Park, Hyun Seol; Lee, Hyung Keun [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2017-08-15

    The purpose of this study is to analyze the flow characteristics when a staggered hollow fiber membrane module is modeled as a porous medium. The pressure-velocity equation was used for modeling the porous medium, using pressure drop data. In terms of flow characteristics, we compared the case of the 'porous medium' when the membrane module was modeled as a porous medium with the case of the 'membrane module' when considering the original shape of the membrane module. The difference in pressure drop between the 'porous medium' and 'membrane module' was less than 0.6%. However, the maximum flow velocity and mean turbulent kinetic energy of the 'porous medium' were 2.5 and 95 times larger than those of the 'membrane module,' respectively. Our results indicate that modeling the hollow fiber module as a porous medium is useful for predicting pressure drop, but not sufficient for predicting the maximum flow velocity and mean turbulent kinetic energy.

  11. The effect of joint surface contours and glass fiber reinforcement on the transverse strength of repaired acrylic resin: An in vitro study.

    Science.gov (United States)

    Anasane, Nayana; Ahirrao, Yogesh; Chitnis, Deepa; Meshram, Suresh

    2013-03-01

    Denture fracture is an unresolved problem in complete denture prosthodontics. However, the repaired denture often experiences a refracture at the repaired site due to poor transverse strength. Hence, this study was conducted to evaluate the effect of joint surface contours and glass fiber reinforcement on the transverse strength of repaired acrylic resins. A total of 135 specimens of heat polymerized polymethyl methacrylate resin of dimensions 64 × 10 × 2.5 mm were fabricated. Fifteen intact specimens served as the control and 120 test specimens were divided into four groups (30 specimens each), depending upon the joint surface contour (butt, bevel, rabbet and round), with two subgroups based on type of the repair. Half of the specimens were repaired with plain repair resin and the other half with glass fibers reinforced repair resin. Transverse strength of the specimens was determined using three-point bending test. The results were analyzed using one-way ANOVA and Tukey post-hoc test (α= 0.05). Transverse strength values for all repaired groups were significantly lower than those for the control group (P transverse strength; hence, it can be advocated for repair of denture base resins.

  12. Temperature-dependent residual shear strength characteristics of smectite-rich landslide soils

    Science.gov (United States)

    Shibasaki, Tatsuya; Matsuura, Sumio; Okamoto, Takashi

    2015-04-01

    behaviors were also recognized during cooling-event tests. Shear stress fluctuations, which were obtained by 1 Hz data sampling, showed that shear behavior characteristically changed in response to temperature conditions. Stick-slip behavior prevailed under room temperature conditions, whereas shear behavior gradually changed into stable sliding behavior as temperature decreased. SEM (Scanning Electric Microscope) observation on shear surfaces indicated that silt- and sand-size asperities in the vicinity of the shear surface influence the occurrence of stick-slip behavior. It is also characteristically noted that rod-shaped smectitic clays, here called "roll", developed on shear surfaces and are arrayed densely perpendicular to the shearing direction in a micrometer scale. We assume that these rolls are probably rotating slowly within shear zone and acting as a lubricant which affects the temperature-dependent frictional properties of the shearing plane. These experimental results show that residual strength characteristics of smectite-rich soils are sensitive to temperature conditions. Our findings imply that if slip surface soils contain a high fraction of smectite, a decrease in ground temperature can lead to lowered shear resistance of the slip surface and triggering of slow landslide movement.

  13. Assessment of Tensile Bond Strength of Fiber-Reinforced Composite Resin to Enamel Using Two Types of Resin Cements and Three Surface Treatment Methods

    Directory of Open Access Journals (Sweden)

    Tahereh Ghaffari

    2015-10-01

    Full Text Available Background: Resin-bonded bridgework with a metal framework is one of the most conservative ways to replace a tooth with intact abutments. Visibility of metal substructure and debonding are the complications of these bridgeworks. Today, with the introduction of fiber-reinforced composite resins, it is possible to overcome these complications. The aim of this study was to evaluate the bond strength of fiber-reinforced composite resin materials (FRC to enamel. Methods: Seventy-two labial cross-sections were prepared from intact extracted teeth. Seventy-two rectangular samples of cured Vectris were prepared and their thickness was increased by adding Targis. The samples were divided into 3 groups for three different surface treatments: sandblasting, etching with 9% hydrofluoric acid, and roughening with a round tapered diamond bur. Each group was then divided into two subgroups for bonding to etched enamel by Enforce and Variolink II resin cements. Instron universal testing machine was used to apply a tensile force. The fracture force was recorded and the mode of failure was identified under a reflective microscope. Results: There were no significant differences in bond strength between the three surface treatment groups (P=0.53. The mean bond strength of Variolink II cement was greater than that of Enforce (P=0.04. There was no relationship between the failure modes (cohesive and adhesive and the two cement types. There was some association between surface treatment and failure mode. There were adhesive failures in sandblasted and diamond-roughened groups and the cohesive failure was dominant in the etched group. Conclusion: It is recommended that restorations made of fiber-reinforced composite resin be cemented with VariolinkII and surface-treated by hydrofluoric acid.   Keywords: Tensile bond strength; surface treatment methods; fiber-reinforced composite resin

  14. Effect of polymerization mode of two adhesive systems on push-out bond strength of fiber post to different regions of root canal dentin

    Directory of Open Access Journals (Sweden)

    Shahram Farzin Ebrahimi

    2014-01-01

    Full Text Available Background: A few studies have investigated the effect of the activation mode of adhesive systems on bond strength of fiber posts to root canal dentin. This study investigated the push-out bond strengths of a glass fiber post to different root canal regions with the use of two adhesives with light- and dual-cure polymerization modes. Materials and Methods: In this in vitro study, 40 maxillary central incisors were decoronated at cement-enamel junction with 15 ± 1 mm root length. After root canal therapy and post space preparations, they were randomly divided into four groups. Post spaces were treated with four different adhesives: Excite, Excite Dual cure Single Component (DSC, self-etch adhesive (AdheSE, and AdheSE dual-cure. Then the fiber-reinforced composite (FRC post, Postec Plus, was cemented with dual-cure resin cement, Variolink II. The roots were cut into three 2-mm-thick slices. Push-out tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min. The mode of failures was determined under a stereomicroscope. Data were analyzed by three-way analysis of variance (ANOVA and Tukey test was conducted to compare post hoc with P < 0.05 as the level of significance. Results: The highest bond strength was obtained for AdheSE dual-cure (15.54 ± 6.90 MPa and the lowest was obtained for Excite light-cure (10.07 ± 7.45 MPa and only the bond strength between these two adhesives had significant difference (P = 0.02. Bond strength decreased from the coronal to the apical in all groups and this was significant in Excite (group 1 and AdheSE (group 3 (P < 0.001. In apical regions, bond strength of dual-cure adhesives was significantly higher than light-cure adhesives (P < 0.001. Conclusion: Push-out bond strength of fiber post to different regions of root canal dentin was affected by both adhesive systems and their polymerization modes.

  15. EFFECT OF SEA WATER ON THE STRENGTH OF POROUS CONCRETE CONTAINING PORTLAND COMPOSITE CEMENT AND MICROFILAMENT POLYPROPYLENE FIBER

    OpenAIRE

    TJARONGE, M.W

    2011-01-01

    The aim of this research is to study the influence of sea water on the strength of porous concrete containing Portland Composite cement and micro monofilament polypropylene fibre. The specimens of porous concrete were immersed in the sea water up to 28 days. The compressive strength test and flexural strength test were carried out at 3, 7 and 28 days in order to investigate the strength development. The test result indicated that the strength of porous concrete can develop in t...

  16. Multipoint fiber-optic laser-ultrasonic actuator based on fiber core-opened tapers.

    Science.gov (United States)

    Tian, Jiajun; Dong, Xiaolong; Gao, Shimin; Yao, Yong

    2017-11-27

    In this study, a novel fiber-optic, multipoint, laser-ultrasonic actuator based on fiber core-opened tapers (COTs) is proposed and demonstrated. The COTs were fabricated by splicing single-mode fibers using a standard fiber splicer. A COT can effectively couple part of a core mode into cladding modes, and the coupling ratio can be controlled by adjusting the taper length. Such characteristics are used to obtain a multipoint, laser-ultrasonic actuator with balanced signal strength by reasonably controlling the taper lengths of the COTs. As a prototype, we constructed an actuator that generated ultrasound at four points with a balanced ultrasonic strength by connecting four COTs with coupling ratios of 24.5%, 33.01%, 49.51%, and 87.8% in a fiber link. This simple-to-fabricate, multipoint, laser-ultrasonic actuator with balanced ultrasound signal strength has potential applications in fiber-optic ultrasound testing technology.

  17. A novel detector based on dual-mode fiber polished half block's characteristics for sensitive monitorings of radiation and materials

    International Nuclear Information System (INIS)

    Saeed, Ghadirli

    2005-01-01

    Full text : The overlay index dependence characteristics of the power distribution between two modes of dual-mode fiber polished half blocks is studied. The heat dependence characteristics of a certain overlay index affects the modal power distributions at the input of interferometer sensors used for monitoring the sensitive heat radiation changes. The other fundamental applications such as material recognitions through the index dependence characteristics in the closed chambers is also suggested

  18. Development of glass-fiber high-efficiency particulate air filters of high structural strength on the basis of the establishment of failure mechanisms

    International Nuclear Information System (INIS)

    Ruedinger, V.; Ricketts, C.I.; Wilhelm, J.G.; Alken, W.

    1987-01-01

    Practical experience from routine operation in nuclear installations as well as extensive bench and laboratory testing proved the structural limits of HEPA filters to be very low thus demonstrating the need for improvement of their structural strength. Detailed analysis of the courses and modes of filter failure under the challenge of dry air at high velocities and ambient temperature, together with additional measurements, allowed the establishment of the dominating mechanisms of filter failure. Based on this information, the following three options for effective and economical improvements in filter structural limits exist: (1) an increase in the tensile strength of the filter medium; (2) an increase in the stability of the pack to prevent the swelling of individual pleats; and (3) an increase in the area moment of inertia of the separators and a decrease in the sharpness of their edges. By using a reinforced glass fiber filter medium, the structural strength of standard size HEPA filters was increased to 31 kPa with dry air and beyond 10 kPa with air at high humidity. Prototype filters built with standard glass-fiber media and separators with inclined corrugations exhibited failure pressures of approximately 50 kPa under high velocity airflows. The combination of both types of improvements, together with other measures, will soon lead to even higher HEPA-filter structural strength

  19. The Effect Of Water/powder Material Ratio And Fiber Strength On The Mechanical Properties Of Fiber Reinforced Self-compacting Concrete

    OpenAIRE

    Dinç, Alihan

    2007-01-01

    Apart from the normal concrete to fulfill the necessities, specially designed high performance concrete has started to find a place for use towards special application purposes. Performance does not only mean increase in strength rather it also encompasses the quality of preserving the strength and other functions under external effects during the service life of the structure. High performance concrete can be defined as a concrete with high workability, durability and strength along with pre...

  20. Characteristic compression strength of a brickwork masonry starting from the strength of its components. Experimental verification of analitycal equations of european codes

    Directory of Open Access Journals (Sweden)

    Rolando, A.

    2006-09-01

    Full Text Available In this paper the compression strength of a clay brickwork masonry bound with cement mortar is analyzed. The target is to obtain the characteristic compression strength of unreinforced brickwork masonry. This research try to test the validity of the analytical equations in European codes, comparing the experimental strength with the analytically obtained from the strength of its components (clay brick and cement mortar.En este artículo se analiza la resistencia a compresión de una fábrica de ladrillo cerámico, asentado con mortero de cemento.El objetivo es obtener la resistencia característica a compresión de la fábrica sin armar.La investigación comprueba la fiabilidad de las expresiones analíticas existentes en la normativa europea, comparando la resistencia obtenida experimentalmente con la obtenida analíticamente, a partir de la resistencia de sus componentes (ladrillo cerámico y mortero de cemento.

  1. The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences.

    Science.gov (United States)

    Yuan, Jing; Gao, Yanan; Wang, Xinyu; Liu, Hongzhuo; Che, Xin; Xu, Lu; Yang, Yang; Wang, Qifang; Wang, Yan; Li, Sanming

    2014-01-01

    Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug-fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug-fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid.

  2. The mechanical and thermal characteristics of phenolic foam reinforced with kaolin powder and glass fiber fabric

    Science.gov (United States)

    Xiao, Wenya; Huang, Zhixiong; Ding, Jie

    2017-12-01

    In this work, kaolin powder and glass fiber fabric were added to PF in order to improve its thermal stability and mechanical property. Micro-structures of carbonized PF with kaolin powder were inspected by scanning electron microscopy (SEM) to demonstrate the filler’s pinning effect. SEM results illustrated modified PF had well morphology after high-temperature heat treatment. The Fourier transform infrared spectrometer (FTIR) test was carried out and found that kaolin powder only physically dispersed in PF. The compression test and thermal weight loss test were done on two groups of modified PF (Group A: add powder and fabric; Group B: add powder only). Results showed that all modified PF were better than pure PF, while foams with powder and fabric showed better mechanical characteristic and thermal stability compared with foams with powder only.

  3. Transport and flow characteristics of an oscillating cylindrical fiber for total artificial lung application

    KAUST Repository

    Qamar, Adnan; Bull, Joseph L.

    2017-01-01

    Mass transport and fluid dynamics characteristics in the vicinity of an oscillating cylindrical fiber with an imposed pulsatile inflow condition are computationally investigated in the present study. The work is motivated by a recently proposed design modification to the Total Artificial Lung (TAL) device, which is expected to provide better gas exchange. Navier–Stokes computations, coupled with convection–diffusion equation are performed to assess flow dynamics and mass transport behavior around the oscillating fiber. The oscillations and the pulsatile free stream velocity are represented by two sinusoidal functions. The resulting non-dimensional parameters are Keulegan–Carpenter number (KC), Schmidt number (Sc), Reynolds number (Re), pulsatile inflow amplitude (), and amplitude of cylinder oscillation (). Results are computed for , Sc = 1000, Re = 5 and 10, and 0.7 and 0.25 5.25. The pulsatile inflow parameters correspond to the flow velocities found in human pulmonary artery while matching the operating TAL Reynolds number. Mass transport from the surface of the cylinder to the bulk fluid is found to be primarily dependent on the size of surface vortices created by the movement of the cylinder. Time-averaged surface Sherwood number (Sh) is dependent on the amplitude and KC of cylinder oscillation. Compared to the fixed cylinder case, a significant gain up to 380% in Sh is achieved by oscillating the cylinder even at the small displacement amplitude (AD = 0.75D). Moreover, with decrease in KC the oscillating cylinder exhibits a lower drag amplitude compared with the fixed cylinder case. Inflow pulsation amplitude has minor effects on the mass transport characteristics. However, an increase in results in an increase in the amplitude of the periodic drag force on the cylinder. This rise in the drag amplitude is similar to that measured for the fixed cylinder case. Quantifications of shear stress distribution in the bulk fluid suggest that the physiological

  4. Transport and flow characteristics of an oscillating cylindrical fiber for total artificial lung application

    KAUST Repository

    Qamar, Adnan

    2017-06-28

    Mass transport and fluid dynamics characteristics in the vicinity of an oscillating cylindrical fiber with an imposed pulsatile inflow condition are computationally investigated in the present study. The work is motivated by a recently proposed design modification to the Total Artificial Lung (TAL) device, which is expected to provide better gas exchange. Navier–Stokes computations, coupled with convection–diffusion equation are performed to assess flow dynamics and mass transport behavior around the oscillating fiber. The oscillations and the pulsatile free stream velocity are represented by two sinusoidal functions. The resulting non-dimensional parameters are Keulegan–Carpenter number (KC), Schmidt number (Sc), Reynolds number (Re), pulsatile inflow amplitude (), and amplitude of cylinder oscillation (). Results are computed for , Sc = 1000, Re = 5 and 10, and 0.7 and 0.25 5.25. The pulsatile inflow parameters correspond to the flow velocities found in human pulmonary artery while matching the operating TAL Reynolds number. Mass transport from the surface of the cylinder to the bulk fluid is found to be primarily dependent on the size of surface vortices created by the movement of the cylinder. Time-averaged surface Sherwood number (Sh) is dependent on the amplitude and KC of cylinder oscillation. Compared to the fixed cylinder case, a significant gain up to 380% in Sh is achieved by oscillating the cylinder even at the small displacement amplitude (AD = 0.75D). Moreover, with decrease in KC the oscillating cylinder exhibits a lower drag amplitude compared with the fixed cylinder case. Inflow pulsation amplitude has minor effects on the mass transport characteristics. However, an increase in results in an increase in the amplitude of the periodic drag force on the cylinder. This rise in the drag amplitude is similar to that measured for the fixed cylinder case. Quantifications of shear stress distribution in the bulk fluid suggest that the physiological

  5. Fiber Amplifiers

    DEFF Research Database (Denmark)

    Rottwitt, Karsten

    2017-01-01

    The chapter provides a discussion of optical fiber amplifiers and through three sections provides a detailed treatment of three types of optical fiber amplifiers, erbium doped fiber amplifiers (EDFA), Raman amplifiers, and parametric amplifiers. Each section comprises the fundamentals including...... the basic physics and relevant in-depth theoretical modeling, amplifiers characteristics and performance data as a function of specific operation parameters. Typical applications in fiber optic communication systems and the improvement achievable through the use of fiber amplifiers are illustrated....

  6. Strength, leachability and microstructure characteristics of cement-based solidified plating sludge

    International Nuclear Information System (INIS)

    Asavapisit, Suwimol; Naksrichum, Siripat; Harnwajanawong, Naraporn

    2005-01-01

    The solidification of the stabilized zinc-cyanide plating sludge was carried out using ordinary Portland cement (OPC) and pulverized fuel ash (PFA) as solidification binders. The plating sludge were used at the level of 0%, 10%, 20% and 30% dry weight, and PFA was used to replace OPC at 0%, 10%, 20% and 30% dry weight, respectively. Experimental results showed that a significant reduction in strength was observed when the plating sludge was added to both the OPC and OPC/PFA binders, but the negative effect was minimized when PFA was used as part substitute for OPC. SEM observation reveals that the deposition of the plating sludge on the surface of the clinkers and PFA could be the cause for hydration retardation. In addition, calcium zinc hydroxide hydrate complex and the unreacted di- and tricalcium silicates were the major phases in X-ray diffraction (XRD) patterns of the solidified plating waste hydrated for 28 days, although the retardation effect on hydration reactions but Cr concentration in toxicity characteristic leaching procedure (TCLP) leachates was lower than the U.S. EPA regulatory limit

  7. Muscle Fiber Type Composition and Knee Extension Isometric Strength Fatigue Patterns in Power- and Endurance-Trained Males.

    Science.gov (United States)

    Kroll, Walter; And Others

    1980-01-01

    There is a degree of uniqueness in fatigue patterns, particularly between different levels of absolute maximum strength. Caution should be used when analyzing fatigue curves among subjects with unspecified strength levels. (CJ)

  8. Mechanical properties of unidirectional oil palm empty fruit bunch (OPEFB) fiber reinforced epoxy composite

    Science.gov (United States)

    Hassan, C. S.; Yeo, C. W.; Sahari, B.; Salit, M. S.; Aziz, N. Abdul

    2017-06-01

    Natural fibers have proven to be an excellent reinforcement material for various polymers. In this study, OPEFB fiber with unidirectional alignment was incorporated in epoxy and an investigation on tensile and flexural characteristics of the composite has been carried out. A fiber surface modification utilizing alkaline treatment with 1 sodium hydroxide solution was used in order to increase the fiber matrix bond in the composite. The investigation was carried out for 0°, 45° and 90° fiber orientation. Result showed that the higher the angle of the fiber orientation, the higher the tensile strength and flexural strength the composite will yield.

  9. Shear strength characteristics of mechanically biologically treated municipal solid waste (MBT-MSW) from Bangalore

    International Nuclear Information System (INIS)

    Sivakumar Babu, G.L.; Lakshmikanthan, P.; Santhosh, L.G.

    2015-01-01

    Highlights: • Shear strength properties of mechanically biologically treated municipal solid waste. • Effect of unit weight and particle size on the shear strength of waste. • Effect of particle size on the strength properties. • Stiffness ratio and the strength ratio of MSW. - Abstract: Strength and stiffness properties of municipal solid waste (MSW) are important in landfill design. This paper presents the results of comprehensive testing of shear strength properties of mechanically biologically treated municipal solid waste (MBT-MSW) in laboratory. Changes in shear strength of MSW as a function of unit weight and particle size were investigated by performing laboratory studies on the MSW collected from Mavallipura landfill site in Bangalore. Direct shear tests, small scale and large scale consolidated undrained and drained triaxial tests were conducted on reconstituted compost reject MSW samples. The triaxial test results showed that the MSW samples exhibited a strain-hardening behaviour and the strength of MSW increased with increase in unit weight. Consolidated drained tests showed that the mobilized shear strength of the MSW increased by 40% for a unit weight increase from 7.3 kN/m 3 to 10.3 kN/m 3 at 20% strain levels. The mobilized cohesion and friction angle ranged from 5 to 9 kPa and 8° to 33° corresponding to a strain level of 20%. The consolidated undrained tests exhibited reduced friction angle values compared to the consolidated drained tests. The friction angle increased with increase in the unit weight from 8° to 55° in the consolidated undrained tests. Minor variations were found in the cohesion values. Relationships for strength and stiffness of MSW in terms of strength and stiffness ratios are developed and discussed. The stiffness ratio and the strength ratio of MSW were found to be 10 and 0.43

  10. Shear strength characteristics of mechanically biologically treated municipal solid waste (MBT-MSW) from Bangalore

    Energy Technology Data Exchange (ETDEWEB)

    Sivakumar Babu, G.L., E-mail: gls@civil.iisc.ernet.in [Department of Civil Engineering, Indian Institute of Science, Bangalore 560012 (India); Lakshmikanthan, P., E-mail: lakshmikanthancp@gmail.com [Centre for Sustainable Technologies (CST), Indian Institute of Science, Bangalore 560012 (India); Santhosh, L.G., E-mail: lgsanthu2006@gmail.com [Centre for Sustainable Technologies (CST), Indian Institute of Science, Bangalore 560012 (India)

    2015-05-15

    Highlights: • Shear strength properties of mechanically biologically treated municipal solid waste. • Effect of unit weight and particle size on the shear strength of waste. • Effect of particle size on the strength properties. • Stiffness ratio and the strength ratio of MSW. - Abstract: Strength and stiffness properties of municipal solid waste (MSW) are important in landfill design. This paper presents the results of comprehensive testing of shear strength properties of mechanically biologically treated municipal solid waste (MBT-MSW) in laboratory. Changes in shear strength of MSW as a function of unit weight and particle size were investigated by performing laboratory studies on the MSW collected from Mavallipura landfill site in Bangalore. Direct shear tests, small scale and large scale consolidated undrained and drained triaxial tests were conducted on reconstituted compost reject MSW samples. The triaxial test results showed that the MSW samples exhibited a strain-hardening behaviour and the strength of MSW increased with increase in unit weight. Consolidated drained tests showed that the mobilized shear strength of the MSW increased by 40% for a unit weight increase from 7.3 kN/m{sup 3} to 10.3 kN/m{sup 3} at 20% strain levels. The mobilized cohesion and friction angle ranged from 5 to 9 kPa and 8° to 33° corresponding to a strain level of 20%. The consolidated undrained tests exhibited reduced friction angle values compared to the consolidated drained tests. The friction angle increased with increase in the unit weight from 8° to 55° in the consolidated undrained tests. Minor variations were found in the cohesion values. Relationships for strength and stiffness of MSW in terms of strength and stiffness ratios are developed and discussed. The stiffness ratio and the strength ratio of MSW were found to be 10 and 0.43.

  11. The effect of resistance training combined with timed ingestion of protein on muscle fiber size and muscle strength

    DEFF Research Database (Denmark)

    Andersen, L.L.; Tufekovic, G.; Zebis, M.K.

    2005-01-01

    of resistance training combined with timed ingestion of isoenergetic protein vs carbohydrate supplementation on muscle fiber hypertrophy and mechanical muscle performance. Supplementation was administered before and immediately after each training bout and, in addition, in the morning on nontraining days...

  12. The effect of pressure changes during simulated diving on the pull out strength of glass fiber posts

    Directory of Open Access Journals (Sweden)

    Meenal Nitin Gulve

    2013-01-01

    Conclusion: Dentist should consider using resin reinforced glass ionomer or resin cement, for the cementation of glass fiber post, for the patients such as divers, who are likely to be exposed to pressure cycling.

  13. In vitro fermentation characteristics of novel fibers, coconut endosperm fiber and chicory pulp, using canine fecal inoculum.

    Science.gov (United States)

    de Godoy, M R C; Mitsuhashi, Y; Bauer, L L; Fahey, G C; Buff, P R; Swanson, K S

    2015-01-01

    The objective of this experiment was to determine the effects of in vitro fermentation of coconut endosperm fiber (CEF), chicory pulp (CHP), and selective blends of these substrates on SCFA production and changes in microbiota using canine fecal inocula. A total of 6 individual substrates, including short-chain fructooligosaccharide (scFOS; a well-established prebiotic source), pectin (PEC; used as a positive control), pelletized cellulose (PC; used as a negative control), beet pulp (BP; considered the gold standard fiber source in pet foods), CEF, and CHP, and 3 CEF:CHP blends (75:25% CEF:CHP [B1], 50:50% CEF:CHP [B2], and 25:75% CEF:CHP [B3]) were tested. Triplicate samples of each substrate were fermented for 0, 8, and 16 h after inoculation. A significant substrate × time interaction (P fiber substrates. Future research should investigate the effects of CEF, CHP, and their blends on gastrointestinal health and fecal quality in dogs.

  14. Effect of different light curing methods on the push-out bond strength of glass fiber post to different root canal regions

    Directory of Open Access Journals (Sweden)

    Ali Eskandarizadeh

    2016-07-01

    Full Text Available Background and Aims: Slow polymerization rate in early stage of light curing process leads to higher monomers movement and entering in polymer network that cause higher mechanical properties.The aim of this study was to evaluate the effect of light activation methodes (immediate, 5 and 10 minutes delay on the push-out bond strength of cemented fiber posts in different regions of root canal with two types of resin cements. Materials and Methods: In sixty extracted human single canal, the teeth were decoronated from cement enamel junction and after root canal therapy, FRC postec plus were cemented with two resin cements, Duolink and Variolink 2, in three curing methods; immediate, 5 and 10 minutes of delay. After storing in a dark place for 24 hours, they were cut into three sections: coronal, middle and apical. The push-out bond strength test was performed using a universal testing machine. The failure modes were observed using a stereomicroscope. Data were analyzed using ANOVA and Tukey post hoc test (P0.05. In immediate light curing method, regardless of root region, Duolink had higher push-out bond strength than that of Variolink 2 (P=0.02. In all subgroups, there were reductions in the bond strengths from coronal to apical. Mixed failure at the cement-fiber post interface was predominent in all groups. Conclusion: 5 and 10 minutes delay caused reduction in the push-out bond strength for Variolink 2 but did not have significant effect for Duolink resin cement.

  15. Effects of addition of different fibers on rheological characteristics of cake batter and quality of cakes.

    Science.gov (United States)

    Aydogdu, Ayca; Sumnu, Gulum; Sahin, Serpil

    2018-02-01

    The aim of this study was to investigate the effects of addition of dietary fibers on rheological properties of batter and cake quality. Wheat flour was replaced by 5 and 10% (wt%) oat, pea, apple and lemon fibers. All cake batters showed shear thinning behavior. Incorporation of fibers increased consistency index (k), storage modulus (G') and loss modulus (G″). As quality parameters, specific volume, hardness, weight loss, color and microstructure of cakes were investigated. Cakes containing oat and pea fibers (5%) had similar specific volume and texture with control cakes which contained no fiber. As fiber concentration increased, specific volume decreased but hardness increased. No significant difference was found between weight loss of control cake and cakes with oat, pea and apple fibers. Lemon fiber enriched cakes had the lowest specific volume, weight loss and color difference. When microstructural images were examined, it was seen that control cake had more porous structure than fiber enriched cakes. In addition, lemon and apple fiber containing cakes had less porous crumb structure as compared to oat and pea containing ones. Oat and pea fiber (5%) enriched cakes had similar physical properties (volume, texture and color) with control cakes.

  16. Characteristics of Highly Birefringent Photonic Crystal Fiber with Defected Core and Equilateral Pentagon Architecture

    Directory of Open Access Journals (Sweden)

    Fei Yu

    2016-01-01

    Full Text Available A novel high birefringence and nearly zero dispersion-flattened photonic crystal fiber (PCF with elliptical defected core (E-DC and equilateral pentagonal architecture is designed. By applying the full-vector finite element method (FEM, the characteristics of electric field distribution, birefringence, and chromatic dispersion of the proposed E-DC PCF are numerically investigated in detail. The simulation results reveal that the proposed PCF can realize high birefringence, ranging from 10-3 to 10-2 orders of magnitude, owing to the embedded elliptical air hole in the core center. However, the existence of the elliptical air hole gives rise to an extraordinary electric field distribution, where a V-shaped notch appears and the size of the V-shaped notch varies at different operating wavelengths. Also, the mode field diameter is estimated to be about 2 μm, which implies the small effective mode area and highly nonlinear coefficient. Furthermore, the investigation of the chromatic dispersion characteristic shows that the introduction of the elliptical air hole is helpful to control the chromatic dispersion to be negative or nearly zero flattened over a wide wavelength bandwidth.

  17. Strength and deformational characteristics of three-way reinforced concrete containment models subjected to lateral forces

    International Nuclear Information System (INIS)

    Aoyagi, Y.; Yamada, K.; Takahashi, T.

    1981-01-01

    With a view to investigating the earthquake resistance characteristics of reinforced concrete containments two cylindrical models with three-way system of bars were made and loaded laterally up to failure combined with or without internal pressures, simulating the conditions in which containments were subjected to earthquake forces at a simultaneous LOCA or at normal operation. The main conclusions obtained withing the limit of the experiments are as follows. (1) Stresses in reinforcements in three-way reinforced concrete plate elements can reasonably be estimated by the equations proposed by Baumann. It is, however, necessary to take into consideration the contributions of concrete between cracks to the deformation in order to accurately estimate the average strains in the plate elements, applying such a formula as CEB as reformed by the authors. (2) The strength capacity of three-way reinforced concrete containments against lateral forces combined with internal pressure is somewhat inferior to that of orthogonally reinforced one if compared on the condition that the volumetric reinforcement ratios are the same for the two cases of reinforcement arrangements. However, three-way reinforcement improves initial shear rigidity as well as ultimate horizontal deformability for lateral forces. (3) The ability for three-way reinforced concrete containment to absorb strain energy in the range of large deformations is superior to that of orthogonally reinforced one. The equivalent viscous damping coefficient for the former is markedly larger than that for the latter, especially at the increased deformational stages. These experimental evidences suggent that three-way system of reinforcement may constitute one of the prospective measures to improve the earthquake resistance of reinforced concrete containments. (orig./HP)

  18. The Influence of GI and GII on the Compression After Impact Strength of Carbon Fiber/Epoxy Laminates and Sandwich Structure

    Science.gov (United States)

    Nettles, A. T.; Scharber, L. L.

    2017-01-01

    This study measured the compression after impact strength of IM7 carbon fiber laminates made from epoxy resins with various mode I and mode II toughness values to observe the effects of these toughness values on the resistance to damage formation and subsequent residual compression strength-carrying capabilities. Both monolithic laminates and sandwich structure were evaluated. A total of seven different epoxy resin systems were used ranging in approximate GI values of 245-665 J/sq m and approximate GII values of 840-2275 J/sq m. The results for resistance to impact damage formation showed that there was a direct correlation between GII and the planar size of damage, as measured by thermography. Subsequent residual compression strength testing suggested that GI had no influence on the measured values and most of the difference in compression strength was directly related to the size of damage. Thus, delamination growth assumed as an opening type of failure mechanism does not appear to be responsible for loss of compression strength in the specimens examined in this study.

  19. Thermoluminescence characteristics of Ge-doped optical fibers with different dimensions for radiation dosimetry

    International Nuclear Information System (INIS)

    Begum, Mahfuza; Rahman, A.K.M. Mizanur; Abdul-Rashid, H.A.; Yusoff, Z.; Begum, Mahbuba; Mat-Sharif, K.A.; Amin, Y.M.; Bradley, D.A.

    2015-01-01

    Important thermoluminescence (TL) properties of five (5) different core sizes Ge-doped optical fibers have been studied to develop new TL material with better response. These are drawn from same preform applying different speed and tension during drawing phase to produce Ge-doped optical fibers with five (5) different core sizes. The results of the investigations are also compared with most commonly used standard TLD-100 chips (LiF:Mg,Ti) and commercial multimode Ge-doped optical fiber (Yangtze Optical Fiber, China). Scanning Electron Microscope (SEM) and EDX analysis of the fibers are also performed to map Ge distribution across the deposited region. Standard Gamma radiation source in Secondary Standard Dosimetry Lab (SSDL) was used for irradiation covering dose range from 1 Gy to 10 Gy. The essential dosimetric parameters that have been studied are TL linearity, reproducibility and fading. Prior to irradiation all samples ∼0.5 cm length are annealed at temperature of 400 °C for 1 h period to standardize their sensitivities and background. Standard TLD-100 chips are also annealed for 1 h at 400 °C and subsequently 2 h at 100 °C to yield the highest sensitivity. TL responses of these fibers show linearity over a wide gamma radiation dose that is an important property for radiation dosimetry. Among all fibers used in this study, 100 μm core diameter fiber provides highest response that is 2.6 times than that of smallest core (20 μm core) optical fiber. These fiber-samples demonstrate better response than commercial multi-mode optical fiber and also provide low degree of fading about 20% over a period of fifteen days for gamma radiation. Effective atomic number (Z eff ) is found in the range (13.25–13.69) which is higher than soft tissue (7.5) however within the range of human-bone (11.6–13.8). All the fibers can also be re-used several times as a detector after annealing. TL properties of the Ge-doped optical fibers indicate promising applications in

  20. New true-triaxial rock strength criteria considering intrinsic material characteristics

    Science.gov (United States)

    Zhang, Qiang; Li, Cheng; Quan, Xiaowei; Wang, Yanning; Yu, Liyuan; Jiang, Binsong

    2018-02-01

    A reasonable strength criterion should reflect the hydrostatic pressure effect, minimum principal stress effect, and intermediate principal stress effect. The former two effects can be described by the meridian curves, and the last one mainly depends on the Lode angle dependence function. Among three conventional strength criteria, i.e. Mohr-Coulomb (MC), Hoek-Brown (HB), and Exponent (EP) criteria, the difference between generalized compression and extension strength of EP criterion experience a firstly increase then decrease process, and tends to be zero when hydrostatic pressure is big enough. This is in accordance with intrinsic rock strength characterization. Moreover, the critical hydrostatic pressure I_c corresponding to the maximum difference of between generalized compression and extension strength can be easily adjusted by minimum principal stress influence parameter K. So, the exponent function is a more reasonable meridian curves, which well reflects the hydrostatic pressure effect and is employed to describe the generalized compression and extension strength. Meanwhile, three Lode angle dependence functions of L_{{MN}}, L_{{WW}}, and L_{{YMH}}, which unconditionally satisfy the convexity and differential requirements, are employed to represent the intermediate principal stress effect. Realizing the actual strength surface should be located between the generalized compression and extension surface, new true-triaxial criteria are proposed by combining the two states of EP criterion by Lode angle dependence function with a same lode angle. The proposed new true-triaxial criteria have the same strength parameters as EP criterion. Finally, 14 groups of triaxial test data are employed to validate the proposed criteria. The results show that the three new true-triaxial exponent criteria, especially the Exponent Willam-Warnke criterion (EPWW) criterion, give much lower misfits, which illustrates that the EP criterion and L_{{WW}} have more reasonable meridian

  1. Transport and flow characteristics of an oscillating cylindrical fiber for total artificial lung application.

    Science.gov (United States)

    Qamar, Adnan; Bull, Joseph L

    2017-08-01

    Mass transport and fluid dynamics characteristics in the vicinity of an oscillating cylindrical fiber with an imposed pulsatile inflow condition are computationally investigated in the present study. The work is motivated by a recently proposed design modification to the Total Artificial Lung (TAL) device, which is expected to provide better gas exchange. Navier-Stokes computations, coupled with convection-diffusion equation are performed to assess flow dynamics and mass transport behavior around the oscillating fiber. The oscillations and the pulsatile free stream velocity are represented by two sinusoidal functions. The resulting non-dimensional parameters are Keulegan-Carpenter number (KC), Schmidt number (Sc), Reynolds number (Re), pulsatile inflow amplitude ([Formula: see text]), and amplitude of cylinder oscillation ([Formula: see text]). Results are computed for [Formula: see text], Sc = 1000, Re = 5 and 10, [Formula: see text] and 0.7 and 0.25 [Formula: see text][Formula: see text][Formula: see text] 5.25. The pulsatile inflow parameters correspond to the flow velocities found in human pulmonary artery while matching the operating TAL Reynolds number. Mass transport from the surface of the cylinder to the bulk fluid is found to be primarily dependent on the size of surface vortices created by the movement of the cylinder. Time-averaged surface Sherwood number (Sh) is dependent on the amplitude and KC of cylinder oscillation. Compared to the fixed cylinder case, a significant gain up to 380% in Sh is achieved by oscillating the cylinder even at the small displacement amplitude (AD = 0.75D). Moreover, with decrease in KC the oscillating cylinder exhibits a lower drag amplitude compared with the fixed cylinder case. Inflow pulsation amplitude has minor effects on the mass transport characteristics. However, an increase in [Formula: see text] results in an increase in the amplitude of the periodic drag force on the cylinder. This rise in the drag amplitude is

  2. Fabrication and Characteristics of Sintered Cutting Stainless Steel Fiber Felt with Internal Channels and an Al2O3 Coating

    Directory of Open Access Journals (Sweden)

    Shufeng Huang

    2018-03-01

    Full Text Available A novel sintered cutting stainless steel fiber felt with internal channels (SCSSFFC composed of a stainless-steel fiber skeleton, three-dimensional interconnected porous structure and multiple circular microchannels is developed. SCSSFFC has a jagged and rough surface morphology and possesses a high specific surface area, which is approximately 2.4 times larger than that of the sintered bundle-drawing stainless steel fiber felt with internal channels (SBDSSFFC and is expected to enhance adhesive strength. The sol-gel and wet impregnation methods are adopted to prepare SCSSFFC with an Al2O3 coating (SCSSFFC/Al2O3. The adhesive strength of SCSSFFC/Al2O3 is investigated using ultrasonic vibration and thermal shock tests. The experimental results indicate that the weight loss rate of the Al2O3 coating has a 4.2% and 8.42% reduction compared with those of SBDSSFFCs based on ultrasonic vibration and thermal shock tests. In addition, the permeability of SCSSFFC/Al2O3 is investigated based on forced liquid flow tests. The experimental results show that the permeability and inertial coefficients of SCSSFFC/Al2O3 are mainly affected by the coating rate, porosity and open ratio; however, the internal microchannel diameter has little influence. It is also found that SCSSFFC/Al2O3 yields superior permeability, as well as inertial coefficients compared with those of other porous materials reported in the literature.

  3. Photonic crystal fiber sensing characteristics research based on alcohol asymmetry filling

    Science.gov (United States)

    Shi, Fu-quan; Luo, Yan; Li, Hai-tao; Peng, Bao-jin

    2018-02-01

    A new type of Sagnac fiber temperature sensor based on alcohol asymmetric filling photonic crystal fiber is proposed. First, the corrosion of photonic crystal fiber and the treatment of air hole collapse are carried out. Then, the asymmetric structure of photonic crystal fiber is filled with alcohol, and then the structure is connected to the Sagnac interference ring. When the temperature changes, the thermal expansion effect of filling alcohol will lead to the change of birefringence of photonic crystal fiber, so that the interference spectrum of the sensor will drift along with the change of temperature. The experimental results show that the interference red shift will occur with the increase of temperature, and the temperature sensitivity is 0.1864nm/ °C. The sensor has high sensitivity to temperature. At the same time, the structure has the advantages of high stability, anti electromagnetic interference and easy to build. It provides a new method for obtaining birefringence in ordinary photonic crystal fibers.

  4. Coupling characteristics of the spun optical fiber with triple stress elements

    Science.gov (United States)

    Ji, Minning; Shang, Fengtao; Chen, Dandan

    2018-06-01

    An empirical formula related to the stress field distribution in the optical fiber with triple stress elements is proposed and proved. The possible intercoupling between the fundamental modes and the higher order modes is demonstrated. The transmission property of the spun optical fiber with triple stress elements is analyzed. The experimental data from a sample of the spun optical fiber with triple stress elements confirm the theoretical results very well.

  5. Deformation Characteristics of Ultrahigh-Strength Concrete under Unrestrained and Restrained States

    Directory of Open Access Journals (Sweden)

    Joo-Ha Lee

    2017-01-01

    Full Text Available As structures like skyscrapers and long-span bridges become larger, the demand for higher strength of concrete is increasing. However, research on ultrahigh-strength concrete (UHSC is still in its infancy. In particular, UHSC is known to have a considerably higher level of autogenous shrinkage than normal strength concrete (NSC, and the possibility of cracking at an early age is very high. Therefore, in this study, shrinkage and cracking behavior of high-strength concrete (HSC, very-high-strength concrete (VHSC, and UHSC were evaluated through unrestrained shrinkage test and restrained shrinkage test (ring test. The primary experimental variables are the compressive strength level according to the water-to-binder ratio (W/B, fly ash content, and concrete specimen thickness. The experimental results demonstrated that the drying shrinkage decreased as the W/B ratio and the fly ash replacement ratio increased, and the restraint cracks appeared to be the earliest and most brittle in the UHSC with the smallest W/B. Increased concrete thickness and incorporation of fly ash were observed to inhibit crack initiation effectively.

  6. Experimental and Numerical Investigations on the Mechanical Characteristics of Carbon Fiber Sensors

    Directory of Open Access Journals (Sweden)

    Salem Bashmal

    2017-09-01

    Full Text Available Carbon fiber-based materials possess excellent mechanical properties and show linear piezoresistive behavior, which make them good candidate materials for strain measurements. They have the potential to be used as sensors for various applications such as damage detection, stress analysis and monitoring of manufacturing processes and quality. In this paper, carbon fiber sensors are prepared to perform reliable strain measurements. Both experimental and computational studies were carried out on commercially available carbon fibers in order to understand the response of the carbon fiber sensors due to changes in the axial strain. Effects of parameters such as diameter, length, and epoxy-hardener ratio are discussed. The developed numerical model was calibrated using laboratory-based experimental data. The results of the current study show that sensors with shorter lengths have relatively better sensitivity. This is due to the fact short fibers have low initial resistance, which will increase the change of resistance over initial resistance. Carbon fibers with low number of filaments exhibit linear behavior while nonlinear behavior due to transverse resistance is significant in fibers with large number of filaments. This study will allow researchers to predict the behavior of the carbon fiber sensor in real life and it will serve as a basis for designing carbon fiber sensors to be used in different applications.

  7. Shear transfer in concrete reinforced with carbon fibers

    Science.gov (United States)

    El-Mokadem, Khaled Mounir

    2001-10-01

    Scope and method of study. The research started with preliminary tests and studies on the behavior and effect of carbon fibers in different water solutions and mortar/concrete mixes. The research work investigated the use of CF in the production of concrete pipes and prestressed concrete double-tee sections. The research then focused on studying the effect of using carbon fibers on the direct shear transfer of sand-lightweight reinforced concrete push-off specimens. Findings and conclusions. In general, adding carbon fibers to concrete improved its tensile characteristics but decreased its compressive strength. The decrease in compressive strength was due to the decrease in concrete density as fibers act as three-dimensional mesh that entrapped air. The decrease in compressive strength was also due to the increase in the total surface area of non-cementitious material in the concrete. Sand-lightweight reinforced concrete push-off specimens with carbon fibers had lower shear carrying capacity than those without carbon fibers for the same cement content in the concrete. Current building codes and specifications estimate the shear strength of concrete as a ratio of the compressive strength. If applying the same principals then the ratio of shear strength to compressive strength for concrete reinforced with carbon fibers is higher than that for concrete without carbon fibers.

  8. Measurement of characteristics of solid flow in the cyclone separators with fiber optical probe

    International Nuclear Information System (INIS)

    Li Shaohua; Li Yan; Li Jinjing; Yang Shi; Yang Hairui; Zhang Hai; Lu Junfu; Yue Guangxi

    2009-01-01

    In some applications, e.g. circulating fluidized beds (CFB), cyclones are usually operated at high solid loadings. Under high inlet solid concentration, most of the particles are collected at the wall and form a dense particle spiral band because of high separation efficiency. As a result, gas-solid reactions should occur mostly in the near-wall region. To understand the gas-solid reaction mechanism in the cyclone, an experimental study was conducted in a plexiglass CFB cold apparatus, with a riser of 0.2m I.D. and 5m high, and a standard Lapple cyclone. Fiber optical probe was used to measure the characteristics of solid flow in the cyclone, including particle velocity and volumetric solid concentration, especially in the near-wall region of the cyclone. Based on the experiment results, the combustion of carbon particles in the cyclone of a CFB boiler was estimated with group combustion theory. The calculated results show that combustion effectiveness factor ηeff of near-wall particle cloud is smaller than 1/25, which means the combustion rate of a carbon particle in the near-wall region is greatly restricted by other particles in the cloud.

  9. Mechanism and Characteristics of Humidity Sensing with Polyvinyl Alcohol-Coated Fiber Surface Plasmon Resonance Sensor.

    Science.gov (United States)

    Shao, Yu; Wang, Ying; Cao, Shaoqing; Huang, Yijian; Zhang, Longfei; Zhang, Feng; Liao, Changrui; Wang, Yiping

    2018-06-25

    A surface plasmon resonance (SPR) sensor based on a side-polished single mode fiber coated with polyvinyl alcohol (PVA) is demonstrated for relative humidity (RH) sensing. The SPR sensor exhibits a resonant dip in the transmission spectrum in ambient air after PVA film coating, and the resonant wavelength shifts to longer wavelengths as the thickness of the PVA film increases. When RH changes, the resonant dip of the sensor with different film-thicknesses exhibits interesting characteristics for optical spectrum evolution. For sensors with initial wavelengths between 550 nm and 750 nm, the resonant dip shifts to longer wavelengths with increasing RH. The averaged sensitivity increases firstly and then drops, and shows a maximal sensitivity of 1.01 nm/RH%. Once the initial wavelength of the SPR sensor exceeds 850 nm, an inflection point of the resonant wavelength shift can be observed with RH increasing, and the resonant dip shifts to shorter wavelengths for RH values exceeding this point, and sensitivity as high as −4.97 nm/RH% can be obtained in the experiment. The sensor is expected to have potential applications in highly sensitive and cost effective humidity sensing.

  10. Mechanism and Characteristics of Humidity Sensing with Polyvinyl Alcohol-Coated Fiber Surface Plasmon Resonance Sensor

    Directory of Open Access Journals (Sweden)

    Yu Shao

    2018-06-01

    Full Text Available A surface plasmon resonance (SPR sensor based on a side-polished single mode fiber coated with polyvinyl alcohol (PVA is demonstrated for relative humidity (RH sensing. The SPR sensor exhibits a resonant dip in the transmission spectrum in ambient air after PVA film coating, and the resonant wavelength shifts to longer wavelengths as the thickness of the PVA film increases. When RH changes, the resonant dip of the sensor with different film-thicknesses exhibits interesting characteristics for optical spectrum evolution. For sensors with initial wavelengths between 550 nm and 750 nm, the resonant dip shifts to longer wavelengths with increasing RH. The averaged sensitivity increases firstly and then drops, and shows a maximal sensitivity of 1.01 nm/RH%. Once the initial wavelength of the SPR sensor exceeds 850 nm, an inflection point of the resonant wavelength shift can be observed with RH increasing, and the resonant dip shifts to shorter wavelengths for RH values exceeding this point, and sensitivity as high as −4.97 nm/RH% can be obtained in the experiment. The sensor is expected to have potential applications in highly sensitive and cost effective humidity sensing.

  11. Efeito da tenacidade da fibra sobre propriedades tecnológicas do fio de algodão Effect of the cotton fiber strength on yarn properties

    Directory of Open Access Journals (Sweden)

    Nelson Paulieri Sabino

    1995-01-01

    Full Text Available Consideraram-se três variedades de algodão com valores de tenacidade da fibra variando de 20,5 a 22,2 g/Tex: IAC 16, IAC 13-1 e IAC 17, classificadas, respectivamente, como de alta, média e baixa tenacidade. Tais variedades apresentaram características tecnológicas semelhantes quanto a comprimento, uniformidade de comprimento, índice de finura Micronaire e maturidade. As amostras foram processadas em estabelecimentos industriais, da maneira convencional, produzindo, cada uma, fios de títulos Ne20, Ne30 e Ne40. Para cada título, empregaram-se sete coeficientes de torção, representados pelas constantes 3,4, 3,6, 3,8, 4,0, 4,2, 4,5 e 4,7. Efetuaram-se as análises da variância dos resultados, de acordo com o delineamento fatorial 3 x 3 x 7, representado pelas três variedades, pelos três títulos e pelos sete níveis de coeficientes de torção. Mediante os resultados, conclui-se que fibras de algodão com alta tenacidade produzem fios mais resistentes e elásticos do que aquelas de baixa tenacidade, para qualquer título ou torção. A quantidade de torções requeridas para a obtenção de máxima resistência dos fios de algodão é pouco afetada pela tenacidade da fibra. Os fios de títulos mais altos têm os menores valores de tenacidade e elongação. A variedade IAC 16 apresentou fios com os maiores valores de tenacidade, seguida da 'IAC 13-1' e da 'IAC 17', e fios mais elásticos, acompanhada da 'IAC 17' e da 'IAC 13-1'.Three cottons with fiber strength of 20.5, 20.9 and 22.2 g/Tex and having other important fiber properties approximately equal were selected. The cottons were processed on conventional processing equipment into 20/1, 30/1 and 40/1 yarn counts, using a range of twist multipliers of 3.4, 3.6, 3.8, 4.0, 4.2, 4.5 and 4.7. Yarn strength and elongation determinations were made on a pendulum-type tester of 150-300 lbs capacity. It was found that: 1 - High strength cotton produced stronger yarns than low strength for any

  12. Characteristics and formation mechanism for stainless steel fiber with periodic micro-fins

    Science.gov (United States)

    Tang, Tao; Wan, Zhenping; Lu, Longsheng; Tang, Yong

    2016-05-01

    Metal fibers have been widely used in many industrial applications due to their unique advantages. In certain applications, such as catalyst supports or orthopedic implants, a rough surface or tiny outshoots on the surface of metal fibers to increase surface area are needed. However, it has not been concerned about the surface morphologies of metal fiber in the current research of metal fiber manufacturing. In this paper, a special multi-tooth tool composed of a row of triangular tiny teeth is designed. The entire cutting layer of multi-tooth tool bifurcates into several thin cutting layers due to tiny teeth involved in cutting. As a result, several stainless steel fibers with periodic micro-fins are produced simultaneously. Morphology of periodic micro-fins is found to be diverse and can be classified into three categories: unilateral plane, unilateral tapering and bilateral. There are two forming mechanisms for the micro-fins. One is that periodic burrs remained on the free side of cutting layer of a tiny tooth create micro-fins of stainless steel fiber produced by the next neighboring tiny tooth; the other is that the connections between two fibers stuck together come to be micro-fins if the two fibers are finally detached. Influence of cutting conditions on formation of micro-fins is investigated. Experimental results show that cutting depth has no significant effect on micro-fin formation, high cutting speed is conducive to micro-fin formation, and feed should be between 0.12 mm/r and 0.2 mm/r to reliably obtain stainless steel fiber with micro-fins. This research presents a new pattern of stainless steel fiber characterized by periodic micro-fins formed on the edge of fiber and its manufacturing method.

  13. Thermal and strength performance of reinforced self-compacting concrete slabs mixed with basalt and PVA fibers in high intensity fire

    Directory of Open Access Journals (Sweden)

    Mohd Jani Noraniza

    2017-01-01

    Full Text Available Fibers addition to concrete and the innovation of self-compacting concrete technology lead to the development of high-performance concrete. However, high intensity fire may adversely affect the performance of this type of concrete. A series of fire resistance test experiments to evaluate the performance of fiber reinforced self-compacting concrete (FR-SCC slabs consisting of various mix of basalt and PVA fibers were carried out by subjecting the concrete slabs as an element of construction to high intensity Hydrocarbon fire heating condition. The fire testing condition was in accordance with the standard time-temperature fire curve for 120 minutes up to 1100°C heating temperature. The temperatures on the surface and within the concrete slabs were recorded and the performance of each type of FRSCC slabs were evaluated. The performance of Basalt FR-SCC was found to be more resistant to fire in comparison to PVA FRSCC. There residual compressive strength of core samples were tested and SEM analysis were carried out to determine the effect of high intensity fire on the basalt and PVA FR-SCC slabs.

  14. F2 layer characteristics and electrojet strength over an equatorial station

    Science.gov (United States)

    Adebesin, B. O.; Adeniyi, J. O.; Adimula, I. A.; Reinisch, B. W.; Yumoto, K.

    2013-09-01

    The data presented in this work describes the diurnal and seasonal variation in hmF2, NmF2, and the electrojet current strength over an African equatorial station during a period of low solar activity. The F2 region horizontal magnetic element H revealed that the Solar quiet Sq(H) daily variation rises from early morning period to maximum around local noon and falls to lower values towards evening. The F2 ionospheric current responsible for the magnetic field variations is inferred to build up at the early morning hours, attaining maximum strength around 1200 LT. The Sq variation across the entire months was higher during the daytime than nighttime. This is ascribed to the variability of the ionospheric parameters like conductivity and winds structure in this region. Seasonal daytime electrojet (EEJ) current strength for June solstice, March and September equinoxes, respectively had peak values ranging within 27-35 nT (at 1400 LT) , 30-40 nT (at 1200 LT) and 35-45 nT (at 1500 LT). The different peak periods of the EEJ strength were attributed to the combined effects of the peak electron density and electric field. Lastly, the EEJ strength was observed to be higher during the equinoxes than the solstice period.

  15. Effect of carbonation on leachability, strength and microstructural characteristics of KMP binder stabilized Zn and Pb contaminated soils.

    Science.gov (United States)

    Du, Yan-Jun; Wei, Ming-Li; Reddy, Krishna R; Wu, Hao-liang

    2016-02-01

    This study presents a systematic investigation of effects of carbonation on the contaminant leachability and unconfined compressive strength of KMP stabilized contaminated soils. A field soil spiked with Zn and Pb individually and together is stabilized using a new KMP additive under standard curing conditions and also with carbonation. The KMP additive is composed of oxalic acid-activated phosphate rock, monopotassium phosphate and reactive magnesia. The stabilized soils are tested for acid neutralization capacity, toxic characteristics leaching characteristics, contaminant speciation and unconfined compression strength. X-ray diffraction, scanning electron microscope and energy dispersive spectroscopy analyses are performed to assess reaction products. The results demonstrate that carbonation increases both acid buffer capacity index and unconfined compressive strength, but decreases leachability of KMP stabilized soils. These results are interpreted based on the changes in chemical speciation of Zn and Pb and also stability and solubility of the reaction products (metal phosphates and carbonates) formed in the soils. Overall, this study demonstrates that carbonation has positive effects on leachability and strength of the KMP stabilized soils. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Rearing Tenebrio molitor in BLSS: Dietary fiber affects larval growth, development, and respiration characteristics

    Science.gov (United States)

    Li, Leyuan; Stasiak, Michael; Li, Liang; Xie, Beizhen; Fu, Yuming; Gidzinski, Danuta; Dixon, Mike; Liu, Hong

    2016-01-01

    Rearing of yellow mealworm (Tenebrio molitor L.) will provide good animal nutrition for astronauts in a bioregenerative life support system. In this study, growth and biomass conversion data of T. molitor larvae were tested for calculating the stoichiometric equation of its growth. Result of a respiratory quotient test proved the validity of the equation. Fiber had the most reduction in mass during T. molitor‧s consumption, and thus it is speculated that fiber is an important factor affecting larval growth of T. molitor. In order to further confirm this hypothesis and find out a proper feed fiber content, T. molitor larvae were fed on diets with 4 levels of fiber. Larval growth, development and respiration in each group were compared and analyzed. Results showed that crude-fiber content of 5% had a significant promoting effect on larvae in early instars, and is beneficial for pupa eclosion. When fed on feed of 5-10% crude-fiber, larvae in later instars reached optimal levels in growth, development and respiration. Therefore, we suggest that crude fiber content in feed can be controlled within 5-10%, and with the consideration of food palatability, a crude fiber of 5% is advisable.

  17. System Construction for the Measurement of Bragg Grating Characteristics in Optical Fibers

    Science.gov (United States)

    West, Douglas P.

    1995-01-01

    Bragg gratings are used to measure strain in optical fibers. To measure strain they are sometimes used as a smart structure. They must be characterized after they are written to determine their spectral response. This paper deals with the test setup to characterize Bragg grating spectral responses.Bragg gratings are a photo-induced phenomena in optical fibers. The gratings can be used to measure strain by measuring the shift in wavelength. They placed the fibers into a smart structure to measure the stress and strain produced on support columns placed in bridges. As the cable is subjected to strain the grating causes a shift to a longer wavelength if the fiber is stretched and a shift to a shorter wavelength shift if the fiber is compacted. Our applications involve using the fibers to measure stress and strain on airborne systems. There are many ways to write Bragg gratings into optical fibers. Our focus is on side writing the grating. Our capabilities are limited in the production rate of the gratings. The Bragg grating is written into a fiber and becomes a permanent fixture. We are writing the grating to be centered at 1300 nm because that is the standard phase mask wavelength.

  18. A Study of Compressive Strength Characteristics of Laterite Sand Hollow Blocks

    Directory of Open Access Journals (Sweden)

    Abiodun Olanipekun

    2007-01-01

    Full Text Available This paper presents the results of experimental investigations carried out on partial replacement of sand with laterite as it affects the compressive strength of sandcrete hollow blocks. Two mix proportions (1:6 and 1:8 were used with laterite content varying between 0 and 50% at 10% intervals. Hand and machine compaction methods were used. Curing was done by sprinkling water on the specimens. The results showed that for each mix proportion and compaction method, the compressive strength decreases with increase in laterite content. Machine compacted hollow sandcrete blocks made from mix ratio 1:6 and with up to 10% laterite content is found suitable and hence recommended for building construction having attained a 28-day compressive strength of 2.07N/mm2 as required by the Nigerian Standards.

  19. Basic response characteristics of auditory nerve fibers in the grassfrog (Rana temporaria)

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, J; Jørgensen, M B; Kanneworff, M

    1998-01-01

    -excitatory suppression (PS) of their spontaneous activity. The duration of PS increased with sound level, also in fibers showing a decrease in firing rate at high intensities. Most fibers showing one-tone suppression did not show PS at their best suppression frequencies. Strong suppression was observed also in very......Responses to free-field sound of 401 fibers from the VIIIth nerve of the grassfrog, Rana temporaria, are described. The spontaneous activities of the fibers ranged from 0 to 75 spikes/s, showing only weak correlation with frequency or sensitivity of the fibers. The highest spontaneous activities...... were approximately twice as high as reported previously for frogs. Best frequencies ranged from 100 to 1600 Hz and thresholds ranged from 21 to 80 dB SPL. The median dynamic range was 20 dB and the slopes of the rate-level curves ranged from 5 to 20 spikes/(s-dB). Most of the units showed post...

  20. A Study on Special Characteristics of Sports Aerobics Competitor : The Capacity of Aerobic Power and Isokinetic Strength of Knee Joint

    OpenAIRE

    菊地, はるひ; 佐々木, 浩子

    2004-01-01

    Sports Aerobics is the competitive sports including the complex aerobic step combination and difficulty elements. The competition time is 1 minute and 45±5 seconds. Sports Aerobics requires mainly anaerobic energy for competitive performance. But also it is very important to get the high capacity of aerobic power for performing the perfect execution. In this study, we tried to find out the characteristics for aerobic capacity and leg muscle strength in Sports Aerobics world champions (2 males...

  1. The Effect of Type and Volume Fraction (Vf) of Steel Fiber on the Mechanical Properties of Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Ghanbarpour, S.; Mazaheripour, H.; Mirmoradi, S. H.

    2010-01-01

    is to investigate the effects of type and volume fraction of steel fiber on the compressive strength, split tensile strength, flexural strength and modulus of elasticity of steel fiber reinforced self-compacting concrete (SFRSCC). Design/methodology/approach – For this purpose, Micro wire and Wave type steel fibers......Purpose – Self-compacting concrete (SCC) offers several economic and technical benefits; the use of steel fibers extends its possibilities. Steel fibers bridge cracks, retard their propagation, and improve several characteristics and properties of the SCC. The purpose of this paper...... – It was found that, inclusion of steel fibers significantly affect the split tensile and flexural strength of SCC accordance with type and vf. Besides, mathematical expressions were developed to estimate the flexural, modulus of elasticity and split tensile strength of SFRSCCs regarding of compressive strength...

  2. Influence of steel fibers on the shear and flexural performance of high-strength concrete beams tested under blast loads

    Science.gov (United States)

    Algassem, O.; Li, Y.; Aoude, H.

    2017-09-01

    This paper presents the results of a study examining the effect of steel fibres on the blast behaviour of high-strength concrete beams. As part of the study, a series of three large-scale beams built with high-strength concrete and steel fibres are tested under simulated blast loading using the shock-tube testing facility at the University of Ottawa. The specimens include two beams built with conventional high-strength concrete (HSC) and one beam built with high-strength concrete and steel fibres (HSFRC). The effect of steel fibres on the blast behaviour is examined by comparing the failure mode, mid-span displacements and, overall blast resistance of the specimens. The results show that the addition of steel fibres in high-strength concrete beams can prevent shear failure and substitute for shear reinforcement if added in sufficient quantity. Moreover, the use of steel fibres improves flexural response under blast loading by reducing displacements and increasing blast capacity. Finally, the provision of steel fibres is found to improve the fragmentation resistance of high-strength concrete under blast loads.

  3. Qualitative-feed-restricted heavy swine: meat quality and morpho-histochemical characteristics of muscle fibers

    Directory of Open Access Journals (Sweden)

    Maria Cristina Thomaz

    2009-10-01

    Full Text Available To evaluate the effect of different levels of qualitative feed restriction (0, 5, 10, 15 and 20% on pork quality and muscle morpho-histochemical characteristics, 60 castrated male swines were used. Ten animals were slaughtered at 89 kg BW. Other 50 pigs were fed experimental diets and slaughtered at 128 kg BW. Qualitative restriction increased pH45, and water holding capacity, and reduced the redness, yellowness and cholesterol concentrations of Longissimus lumborum. Quadratic tendency for oleic acid contents of loin and fiber cross-section area of Multifidus dorsi (P=0.08 were observed, with maximum point at 11-12% of restriction. No effect (P>0.1 on percentage of M. dorsi fibers SO, FG and FOG was found. The meat from 128-kg-BW pig showed numerically higher values for colorness, water losses, and lipid content and lower shear force than 89-kg-BW pigs. Qualitative feed restriction for finishing swines neither affected negatively pork quality nor modified the muscle fiber profile.Para avaliar o efeito de diferentes níveis de restrição alimentar qualitative (0, 5, 10, 15 e 20% sobre a qualidade da carne e características morfohistoquímicas musculares, sessenta suínos machos castrados foram utilizados. Dez suínos formaram o grupo abatido inicialmente (89 kg PV e outros 50 suínos foram alimentados com as dietas experimentais e foram abatidos aos 128 kg PV. A restrição qualitativa aumentou o pH45, e a capacidade de retenção de água, bem como reduziu a coloração vermelha e amarela, e o teor de colesterol do músculo Longissimus lumborum. Tendência quadrática para conteúdo de ácido oléico do lombo e da área de seção transversal do músculo Multifidus dorsi (P=0.08 foram observada, com ponto de máxima em11-12% de restrição. Não foi encontrado efeito (P>0.1 na porcentagem de fibras SO, FG e FOG no músculo Multifidus. A carne dos animais abatidos aos 128 kg PV apresentou valores numericamente maiores para coloração, perda de

  4. Experimental Investigation of the Relationship between Breakdown Strength and Tracking Characteristics of Composites

    DEFF Research Database (Denmark)

    Madsen, Søren Find; Holbøll, Joachim; Henriksen, Mogens

    2005-01-01

    ]. The breakdown field strength of specimens cut from similar samples is then determined by a new method capable of estimating the stressed volume [8]. The two values are finally compared and sought incorporated in an analytical formula. All test specimens are supplied by Danish manufacturers of wind turbine...

  5. Investigating the characteristic strength of flocs formed from crude and purified Hibiscus extracts in water treatment.

    Science.gov (United States)

    Jones, Alfred Ndahi; Bridgeman, John

    2016-10-15

    The growth, breakage and re-growth of flocs formed using crude and purified seed extracts of Okra (OK), Sabdariffa (SB) and Kenaf (KE) as coagulants and coagulant aids was assessed. The results showed floc size increased from 300 μm when aluminium sulphate (AS) was used as a coagulant to between 696 μm and 722 μm with the addition of 50 mg/l of OK, KE and SB crude samples as coagulant aids. Similarly, an increase in floc size was observed when each of the purified proteins was used as coagulant aid at doses of between 0.123 and 0.74 mg/l. The largest floc sizes of 741 μm, 460 μm and 571 μm were obtained with a 0.123 mg/l dose of purified Okra protein (POP), purified Sabdariffa (PSP) and purified Kenaf (PKP) respectively. Further coagulant aid addition from 0.123 to 0.74 mg/l resulted in a decrease in floc size and strength in POP and PSP. However, an increase in floc strength and reduced d50 size was observed in PKP at a dose of 0.74 mg/l. Flocs produced when using purified and crude extract samples as coagulant aids exhibited high recovery factors and strength. However, flocs exhibited greater recovery post-breakage when the extracts were used as a primary coagulant. It was observed that the combination of purified proteins and AS improved floc size, strength and recovery factors. Therefore, the applications of Hibiscus seeds in either crude or purified form increases floc growth, strength, recoverability and can also reduce the cost associated with the import of AS in developing countries. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  6. Trunk Strength Characteristics of Elite Alpine Skiers - A Comparison with Physically Active Controls

    Directory of Open Access Journals (Sweden)

    Hildebrandt Carolin

    2017-06-01

    Full Text Available Core muscle imbalances and weak trunk strength are relevant for injury prevention and performance. Information regarding core strength requirements and ideal flexion/extension ratios in alpine skiing is limited. We aimed to compare trunk strength capacities in elite alpine skiers with those of a matched control group. The concentric maximal trunk flexion and extension of 109 elite skiers and 47 active controls were measured at 150°/s in a ballistic mode using the CON-TREX® TP 1000 test system. The relative flexion peak torque was higher in male ski racers (p = 0.003; 2.44 ± 0.30 Nm/kg than in the controls (2.32 ± 0.42 Nm/kg. The relative peak torque for extension was 4.53 ± 0.65 Nm/kg in ski racers and 4.11 ± 0.52 Nm/kg in the controls (p = 0.001. Female athletes were significantly stronger in both, relative flexion force (p = 0.006; skiers 2.05 ± 0.22 Nm/kg; controls 1.74 ± 0.28 Nm/kg and relative extension force (p = 0.001; skiers 3.55 ± 0.53 Nm/kg; controls 3.14 ± 0.48 Nm/kg. No significant differences were found in the ratios of flexion to extension forces in females and males. Ski racers are engaged in extensive strength training for both leg and trunk muscles, which explains the higher peak values. Both groups indicated a low ratio from 0.54-0.59, which represents high trunk extensor muscles strength relative to flexor muscles.

  7. Influence of different adhesive systems on bond strength of carbon fiber posts used to restore endodontically treated teeth

    OpenAIRE

    Silva, Lorena dos Santos; Reis, Kátia Rodrigues; Ambrosano, Glaucia Maria Bovi; Chuí, Fabíola Mendonça da Silva; Sena, Neylla Teixeira; Carvalhal, Cintia Iara Oda; Oliveira, Jonas Alves de

    2013-01-01

    The aim of this study was to evaluate the influence of three adhesive systems on resinous bonding of carbon fiber posts on roots of endodontically treated bovine incisors. Thirty bovine lower incisors with similar dimensions were selected for this study. The roots were endodontically treated and subsequently prepared for post cementation. The posts were treated with adhesive systems Scotchbond MultiPurpose Plus – 3M chemical cure (Group I), light cure (Group II) and dual cure (Group III). Car...

  8. Modifying the strength and strain concentration profile within collagen scaffolds using customizable arrays of poly-lactic acid fibers.

    Science.gov (United States)

    Mozdzen, Laura C; Vucetic, Alan; Harley, Brendan A C

    2017-02-01

    The tendon-to-bone junction is a highly specialized tissue which dissipates stress concentrations between mechanically dissimilar tendon and bone. Upon injury, the local heterogeneities across this insertion are not regenerated, leading to poor functional outcomes such as formation of scar tissue at the insertion and re-failure rates exceeding 90%. Although current tissue engineering methods are moving towards the development of spatially-graded biomaterials to begin to address these injuries, significant opportunities remain to engineer the often complex local mechanical behavior of such biomaterials to enhance their bioactivity. Here, we describe the use of three-dimensional printing techniques to create customizable arrays of poly-lactic acid (PLA) fibers that can be incorporated into a collagen scaffold under development for tendon bone junction repair. Notably, we use additive manufacturing concepts to generate arrays of spatially-graded fibers from biodegradable PLA that are incorporated into collagen scaffolds to create a collagen-PLA composite. We demonstrate the ability to tune the mechanical performance of the fiber-scaffold composite at the bulk scale. We also demonstrate the incorporation of spatially-heterogeneous fiber designs to establish non-uniform local mechanical performance of the composite biomaterial under tensile load, a critical element in the design of multi-compartment biomaterials for tendon-to-bone regeneration applications. Together, this work highlights the capacity to use multi-scale composite biomaterials to control local and bulk mechanical properties, and provides key insights into design elements under consideration for mechanically competent, multi-tissue regeneration platforms. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Thermoluminescence characteristics of different dimensions of Ge-doped optical fibers in radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Begum, M.; Mizanur R, A. K. M.; Abdul R, H. A.; Yusoff, Z. [Multimedia University, Faculty of Engineering, 63100 Cyberjaya, Selangor Darul Ehsan (Malaysia); Begum, M. [Bangladesh Atomic Energy Commission, E-12/A, Agargaon, Sher-e-Blanga Nagar Dhaka-1207 (Bangladesh); Mat-Sharif, K. A. [Lingkaran Teknokrat Timur, Telekom Research and Development, 63000 Cyberjaya, Selangor Darul Ehsan (Malaysia); Amin, Y. M. [University of Malaya, Faculty of Science, Depatment of Physics, 50603 Kuala Lumpur (Malaysia); Bradley, D. A., E-mail: go2munmun@yahoo.com [University of Surrey, Department of Physics, Guildford GU2 7XH (United Kingdom)

    2014-08-15

    Important thermoluminescence (Tl) properties of five (5) different core sizes Ge doped optical fibers have been studied to develop new Tl material with better response. These are drawn from same preform applying different speed and tension during drawing phase. The results of the investigations are also compared with most commonly used standard TLD-100 chips (LiF:Mg,Ti) and commercial multimode Ge doped optical fiber (Yangtze Optical Fiber, China). Scanning Electron Microscope (Sem) and EDX analysis of the fibers are also performed to map Ge distribution across the deposited region. Standard Gamma radiation source in SSDL (Secondary Standard Dosimetry Lab) was used for irradiation covering dose range from 1 Gy to 10 Gy. The essential dosimetric parameters that have been studied are Tl linearity, reproducibility and fading. Prior to irradiation all samples ∼0.5 cm length are annealed at temperature of 400 grades C for 1 hour period to standardize their sensitivities and background. Standard TLD-100 chips are also annealed for 1 hour at 400 grades C and subsequently 2 hours at 100 grades C to yield the highest sensitivity. Tl responses of these fibers show linearity over a wide gamma radiation dose that is an important property for radiation dosimetry. Among all fibers used in this study, 100 μm core diameter fiber provides highest response that is 2.6 times than that of smallest core (20 μm core) optical fiber. These fiber-samples demonstrate better response than commercial multi-mode optical fiber and also provide low degree of fading about 20% over a period of fifteen days for gamma radiation. Effective atomic number (Z{sub eff}) is found in the range (13.25 to 13.69) that is higher than soft tissue (7.5) however within the range of human-bone (11.6-13.8). All the fibers can also be re-used several times as a detector after annealing. Tl properties of the Ge-doped optical fibers indicate promising applications in ionizing radiation dosimetry. (author)

  10. Thermoluminescence characteristics of different dimensions of Ge-doped optical fibers in radiation dosimetry

    International Nuclear Information System (INIS)

    Begum, M.; Mizanur R, A. K. M.; Abdul R, H. A.; Yusoff, Z.; Begum, M.; Mat-Sharif, K. A.; Amin, Y. M.; Bradley, D. A.

    2014-08-01

    Important thermoluminescence (Tl) properties of five (5) different core sizes Ge doped optical fibers have been studied to develop new Tl material with better response. These are drawn from same preform applying different speed and tension during drawing phase. The results of the investigations are also compared with most commonly used standard TLD-100 chips (LiF:Mg,Ti) and commercial multimode Ge doped optical fiber (Yangtze Optical Fiber, China). Scanning Electron Microscope (Sem) and EDX analysis of the fibers are also performed to map Ge distribution across the deposited region. Standard Gamma radiation source in SSDL (Secondary Standard Dosimetry Lab) was used for irradiation covering dose range from 1 Gy to 10 Gy. The essential dosimetric parameters that have been studied are Tl linearity, reproducibility and fading. Prior to irradiation all samples ∼0.5 cm length are annealed at temperature of 400 grades C for 1 hour period to standardize their sensitivities and background. Standard TLD-100 chips are also annealed for 1 hour at 400 grades C and subsequently 2 hours at 100 grades C to yield the highest sensitivity. Tl responses of these fibers show linearity over a wide gamma radiation dose that is an important property for radiation dosimetry. Among all fibers used in this study, 100 μm core diameter fiber provides highest response that is 2.6 times than that of smallest core (20 μm core) optical fiber. These fiber-samples demonstrate better response than commercial multi-mode optical fiber and also provide low degree of fading about 20% over a period of fifteen days for gamma radiation. Effective atomic number (Z eff ) is found in the range (13.25 to 13.69) that is higher than soft tissue (7.5) however within the range of human-bone (11.6-13.8). All the fibers can also be re-used several times as a detector after annealing. Tl properties of the Ge-doped optical fibers indicate promising applications in ionizing radiation dosimetry. (author)

  11. Electrospun gelatin fiber mats containing a herbal—Centella asiatica—extract and release characteristic of asiaticoside

    Science.gov (United States)

    Sikareepaisan, Panprung; Suksamrarn, Apichart; Supaphol, Pitt

    2008-01-01

    Ultra-fine gelatin (type A, porcine skin, ~180 Bloom) fiber mats containing a methanolic crude extract of Centella asiatica (L.) Urban, a medicinal plant widely known for its traditional medical applications including its wound healing ability, were fabricated, for the first time, from the neat gelatin solution (22% w/v in 70 vol% acetic acid) containing the crude extract (mCA) in various amounts (i.e. 5-30 wt% based on the weight of gelatin powder) by electrospinning. Incorporation of mCA in the neat gelatin solution did not affect both the morphology and the size of the mCA-loaded gelatin fibers, as both of the neat and the mCA-loaded gelatin fibers were smooth and the average diameters of these fibers ranged between 226 and 232 nm. The cross-linked mCA-loaded e-spun gelatin fiber mat from the neat gelatin solution containing 30 wt% of mCA was further investigated for the release characteristic of asiaticoside, identified as the most active compound associated with the healing of wounds, in two different types of releasing medium, i.e. acetate buffer and the buffer containing 10 vol% of methanol, based on the thin-layer chromatography (TLC)-densitometry technique. Based on the unit weight of the actual amount of asiaticoside present in the specimens, the total amount of asiaticoside released from the fiber mat specimens was lower than that from the film counterparts while, based on the unit weight of the specimens, an opposite trend was observed.

  12. Electrospun gelatin fiber mats containing a herbal-Centella asiatica-extract and release characteristic of asiaticoside

    International Nuclear Information System (INIS)

    Sikareepaisan, Panprung; Suksamrarn, Apichart; Supaphol, Pitt

    2008-01-01

    Ultra-fine gelatin (type A, porcine skin, ∼180 Bloom) fiber mats containing a methanolic crude extract of Centella asiatica (L.) Urban, a medicinal plant widely known for its traditional medical applications including its wound healing ability, were fabricated, for the first time, from the neat gelatin solution (22% w/v in 70 vol% acetic acid) containing the crude extract (mCA) in various amounts (i.e. 5-30 wt% based on the weight of gelatin powder) by electrospinning. Incorporation of mCA in the neat gelatin solution did not affect both the morphology and the size of the mCA-loaded gelatin fibers, as both of the neat and the mCA-loaded gelatin fibers were smooth and the average diameters of these fibers ranged between 226 and 232 nm. The cross-linked mCA-loaded e-spun gelatin fiber mat from the neat gelatin solution containing 30 wt% of mCA was further investigated for the release characteristic of asiaticoside, identified as the most active compound associated with the healing of wounds, in two different types of releasing medium, i.e. acetate buffer and the buffer containing 10 vol% of methanol, based on the thin-layer chromatography (TLC)-densitometry technique. Based on the unit weight of the actual amount of asiaticoside present in the specimens, the total amount of asiaticoside released from the fiber mat specimens was lower than that from the film counterparts while, based on the unit weight of the specimens, an opposite trend was observed

  13. Effect of the ionic strength of pulsed electric field treatment medium on the physicochemical and structural characteristics of lactoferrin.

    Science.gov (United States)

    Sui, Qian; Roginski, Hubert; Williams, Roderick P W; Wooster, Tim J; Versteeg, Cornelis; Wan, Jason

    2010-11-24

    Pulsed electric field (PEF) treatment (35 kV cm(-1) for 19.2 μs using bipolar 2 μs pulses) was conducted on bovine lactoferrin (LF; 0.4 mg mL(-1)) prepared in simulated milk ultrafiltrate (SMUF), at concentrations between 0.2× and 2× normal strength, with electrical conductivities ranging from 0.17 to 1.04 S m(-1). The physicochemical and structural characteristics (LF content by a spectrophotometric and an ELISA method, surface hydrophobicity, electrophoretic mobility, far-UV circular dichroism spectra, and tryptophan fluorescence) of LF dissolved in SMUF of all strengths tested were not changed after PEF treatment. The PEF treatment of LF in 0.2 strength SMUF did not cause the release of LF-bound ferric ion into the aqueous phase, with a concentration of LF-bound iron being the same as that of the untreated LF control (174 μg L(-1)). However, in treatment media with higher ionic strengths, ferric ion was released from the LF molecule into the aqueous phase. The concentration of LF-bound iron decreased from 174 μg L(-1) for the LF treated in 0.2 strength SMUF to 80 μg L(-1) for that treated in double-strength SMUF. The results suggest that the PEF-induced iron depletion of LF does not appear to cause an appreciable conformational change in LF molecules. PEF treatment could be developed as a novel physical way to produce iron-depleted LF, as an alternative to the existing chemical method.

  14. An in situ evaluation of the polymerization shrinkage, degree of conversion, and bond strength of resin cements used for luting fiber posts.

    Science.gov (United States)

    Pulido, Camilo Andrés; de Oliveira Franco, Ana Paula Gebert; Gomes, Giovana Mongruel; Bittencourt, Bruna Fortes; Kalinowski, Hypolito José; Gomes, João Carlos; Gomes, Osnara Maria Mongruel

    2016-10-01

    The behavior and magnitude of the deformations that occur during polymerization and the behavior of the luting agents of glass fiber posts inside the root canal require quantification. The purpose of this in vitro study was to investigate the in situ polymerization shrinkage, degree of conversion, and bond strength inside the root canal of resin cements used to lute fiber posts. Thirty maxillary canines were prepared to lute fiber posts. The teeth were randomly divided into 2 groups (n=15) according to the cementation system used, which included ARC, the conventional dual-polymerized resin cement RelyX ARC, and the U200 system, a self-adhesive resin cement, RelyX U200. Two fiber optic sensors with recorded Bragg gratings (FBG) were attached to each post before inserting the resin cement inside the root canal to measure the polymerization shrinkage (PS) of the cements in the cervical and apical root regions (με). Specimens were sectioned (into cervical and apical regions) to evaluate bond strength (BS) with a push-out test and degree of conversion (DC) with micro-Raman spectroscopy. Data were statistically analyzed with 2-way ANOVA and the Tukey honestly significant difference post hoc test (α=.05). The ARC and U200 system showed similar PS values (-276.4 ±129.2 με and -252.1 ±119.2 με, respectively). DC values from ARC were higher (87.5 ±2.7%) than those of U200 (55.9 ±9.7%). The cervical region showed higher DC values (74.8 ±15.2%) and PS values (-381.6 ±53.0 με) than those of the apical region (68.5 ±20.1% and -146.9 ±43.5 με, respectively) for both of the resin cements. BS was only statistically different between the cervical and apical regions for ARC (P<.05). The ARC system showed the highest PS and DC values compared with U200; and for both of the resin cements, the PS and DC values were higher at the cervical region than at the apical region of the canal root. BS was higher in the cervical region only for ARC. Copyright © 2016

  15. Microstructural, mechanical, and thermal characteristics of recycled cellulose fiber-halloysite-epoxy hybrid nanocomposites

    KAUST Repository

    Alamri, H.; Low, I. M.

    2012-01-01

    Epoxy hybrid-nanocomposites reinforced with recycled cellulose fibers (RCF) and halloysite nanotubes (HNTs) have been fabricated and investigated. The dispersion of HNTs was studied by synchrotron radiation diffraction (SRD) and transmission

  16. Inclusion of inhomogeneous deformation and strength characteristics in the problem on zonal disintegration of rocks

    Science.gov (United States)

    Chanyshev, AI; Belousova, OE

    2018-03-01

    The authors determine stress and deformation in a heterogeneous rock mass at the preset displacement and Cauchy stress vector at the boundary of an underground excavation. The influence of coordinates on Young’s modulus, shear modulus and ultimate strength is shown. It is found that regions of tension and compression alternate at the excavation boundary—i.e. zonal rock disintegration phenomenon is observed.

  17. Strength and Compressibility Characteristics of Reconstituted Organic Soil at Khulna Region of Bangladesh

    OpenAIRE

    Tahia Rabbee; Islam M. Rafizul

    2012-01-01

    This study depicts the experimental investigations into the effect of organic content on the shear strength and compressibility parameters of reconstituted soil. To these attempts, disturbed soil samples were collected from two selected locations of Khulna region. The reconstituted soil having organic content of 5-35 % were prepared in the laboratory to mix at various proportions of inorganic and organic soil at the water content equal to 1.25 times of liquid limits of collected samples .The ...

  18. Dual characteristics of yield and ultimate strength as applied to two grades of beryllium

    International Nuclear Information System (INIS)

    Priddy, T.G.; Benzley, S.E.; Johnson, R.L.

    1977-02-01

    Published yield and ultimate biaxial strength data for two grades of beryllium are correlated with the use of a macroscopic failure model. Cross sections of the resulting surfaces in three-dimensional stress space are drawn to illustrate the expected transition from ductile to brittle fracture for triaxial tension states of stress. The usefulness of these models to the prediction of fracture in ductile materials is discussed. 5 tables, 8 figures, 11 references

  19. Influence of aggregate characteristics on the compressive strength of normal weight concrete

    International Nuclear Information System (INIS)

    Qureshi, M.A.; Aslam, M.

    2015-01-01

    Experimental investigations on the properties of concrete have been performed around the globe and their correlation is interpreted in relevant design codes. The structural behavior of cement concrete significantly relies on the material resources, properties of the aggregates constituting the concrete and the local construction practice. These factors vary from place to place. Therefore, the compressive strength of concrete prepared from the aggregates available in one locality may not be directly applicable to the other areas. The purpose of this study is to evaluate the Influence of locally available coarse aggregates on the compressive strength of normal weight concrete (NWC) prepared under local environmental conditions of district Khairpur Mir's, Sindh, Pakistan. The coarse aggregates were collected from five different quarries in the vicinity of Khairpur Mir's, Pakistan. In total; 180 cubes were tested. 10 different batches were formed in order to arrange individual characterization of concrete. Each batch was contained of 18 cubes and each quarry contains 2 batches making a total of 36 cube with four different ratios for each quarry. Dry density and compressive strength of concrete was calculated and a comparison is provided as a guideline for the future construction work in the local community. (author)

  20. Strength and deformation characteristics of reinforced concrete shell elements subjected to in-plane forces

    International Nuclear Information System (INIS)

    Aoyagi, Yukio; Yamada, Kazuie.

    1983-01-01

    Reactor containment vessels have been made of steel so far, but since it was decided to adopt a prestressed concrete vessel in the Tsuruga No. 2 plant of Japan Atomic Power Co., the construction of the containment vessels made of prestressed concrete and reinforced concrete has been studied by various electric power companies. However in Japan, there is no standard for the design and construction of concrete structures of this kind. In the standard of foreign countries used for reference, the basis of the stipulation concerning the aseismatic design of concrete containment vessels is not distinct. In this study, the clarification of the strength and deformation when RC vessels are subjected to seismic force only or to internal pressure and seismic force was aimed at, and the result of the loading test by one or two-direction in-plane forces on RC shell elements was examined. Based on this, the method of estimating the strength and deformation of RC shell elements was proposed. The orthogonal reinforcement was adopted, and the strength of shell elements was determined by the yielding of reinforcing bars. (Kako, I.)

  1. Effect of Age on Fiber Characteristics of one-humped Female Camels of Semnan Province (Short article

    Directory of Open Access Journals (Sweden)

    H.R Ansari Renani

    2012-01-01

    Full Text Available The aim of this study was to determine the effect of age on fiber characteristics of one-humped female camels of Semnan province. 50 grams of wool samples from the left midside area were randomly collected from 28 camels of three different age groups: young, adult and old and fibre characteristics were measured. Statistical model used for this research was completely randomized design (CRD. Analysis of data and comparison of means were performed using Duncan's new multiple range test. The results showed that staple length and cashmere percent in young camels were significantly (P

  2. Is PPARα intron 7 G/C polymorphism associated with muscle strength characteristics in nonathletic young men?

    Science.gov (United States)

    Broos, S; Windelinckx, A; De Mars, G; Huygens, W; Peeters, M W; Aerssens, J; Vlietinck, R; Beunen, G P; Thomis, M A

    2013-08-01

    Peroxisome proliferator-activated receptor alpha (PPARα), a ligand-dependent transcription factor, regulates fatty acid metabolism in heart and skeletal muscle. The intron 7 G/C polymorphism (rs4253778) has been associated with athletic performance. The rare C-allele was predominant in power athletes, whereas the G-allele was more frequent in endurance athletes. In the present study, we investigated the association between this polymorphism and strength characteristics in nonathletic, healthy young adults (n = 500; age 24.2 ± 4.4 years). Knee torque was measured during concentric knee flexion and extension movements at 60°/s, 120°/s, and 240°/s during 3, 25, and 5 repetitions, respectively. Also, resistance to muscle fatigue (i.e. work last 20% repetitions/work first 20% repetitions *100) was calculated. Differences in knee strength phenotypes between GG homozygous individuals and C-allele carriers were analyzed. The polymorphism did not influence the ability to produce isometric or dynamic knee flexor or extensor peak torque during static or dynamic conditions in this population (0.23 < P < 0.95). Similar results were found for the endurance ratio, a measure for resistance to muscle fatigue. In conclusion, the PPARα intron 7 G/C polymorphism does not seem to influence strength characteristics in a nonathletic population. © 2011 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Elastic, Frictional, Strength and Dynamic Characteristics of the Bell Shape Shock Absorbers Made of MR Wire Material

    Science.gov (United States)

    Lazutkin, G. V.; Davydov, D. P.; Boyarov, K. V.; Volkova, T. V.

    2018-01-01

    The results of the mechanical characteristic experimental studies are presented for the shock absorbers of DKU type with the elastic elements of the bell shape made of MR material and obtained by the cold pressing of mutually crossing wire spirals with their inclusion in the array of reinforcing wire harnesses. The design analysis and the technology of MR production based on the methods of similarity theory and dimensional analysis revealed the dimensionless determined and determining parameters of elastic frictional, dynamic and strength characteristics under the static and dynamic loading of vibration isolators. The main similarity criteria of mechanical characteristics for vibration isolators and their graphical and analytical representation are determined, taking into account the coefficients of these (affine) transformations of the hysteresis loop family field.

  4. Flexural strength and translucent characteristics of lithium disilicate glass-ceramics with different P2O5 content

    International Nuclear Information System (INIS)

    Wang, Fu; Gao, Jing; Wang, Hui; Chen, Ji-hua

    2010-01-01

    Lithium disilicate glass-ceramics derived from the SiO 2 -Li 2 O-K 2 O-Al 2 O 3 -ZrO 2 -P 2 O 5 system with different P 2 O 5 content (from 0.5 mol.% to 2.0 mol.% at a step of 0.5 mol.%) were prepared for dental restorative application. Flexural strength of final glass-ceramics and translucent characteristics expressed in term of contrast ratio (CR) were measured. The interrelations between P 2 O 5 content, microstructure and properties were discussed. Glass-ceramic with a P 2 O 5 content of 1.0 mol.%, in which elongated rod-like Li 2 Si 2 O 5 crystals formed an interlocking microstructure, showed the highest flexural strength and suitable contrast ratio for dental restorative application.

  5. Experimental studies of fiber concrete creep

    Directory of Open Access Journals (Sweden)

    Korneeva Irina

    2017-01-01

    Full Text Available The results of two-stage experimental studies of the strength and deformation characteristics of fibrous concrete reinforced with steel fiber. In the experiments we used steel fiber with bent ends, which practically does not form "hedgehogs", which allows to achieve an even distribution of the fiber by volume. At the first stage, the cube and prismatic strength, deformability at central compression, a number of special characteristics are determined: water absorption, frost resistance, abrasion; the optimal percentage of fiber reinforcement and the maximum size of the coarse aggregate fraction were selected. Fiber reinforcement led to an increase in the strength of concrete at compression by 1,35 times and an increase in the tensile strength at bending by 3,4 times. At the second stage, the creep of fibrous concrete and plain concrete of similar composition at different stress levels was researched. Creep curves are plotted. It is shown that the use of fiber reinforcement leads to a decrease in creep strain by 21 to 30 percent, depending on the stress level.

  6. Improving stability and strength characteristics of framed structures with nonlinear behavior

    Science.gov (United States)

    Pezeshk, Shahram

    1990-01-01

    In this paper an optimal design procedure is introduced to improve the overall performance of nonlinear framed structures. The design methodology presented here is a multiple-objective optimization procedure whose objective functions involve the buckling eigenvalues and eigenvectors of the structure. A constant volume with bounds on the design variables is used in conjunction with an optimality criterion approach. The method provides a general tool for solving complex design problems and generally leads to structures with better limit strength and stability. Many algorithms have been developed to improve the limit strength of structures. In most applications geometrically linear analysis is employed with the consequence that overall strength of the design is overestimated. Directly optimizing the limit load of the structure would require a full nonlinear analysis at each iteration which would be prohibitively expensive. The objective of this paper is to develop an algorithm that can improve the limit-load of geometrically nonlinear framed structures while avoiding the nonlinear analysis. One of the novelties of the new design methodology is its ability to efficiently model and design structures under multiple loading conditions. These loading conditions can be different factored loads or any kind of loads that can be applied to the structure simultaneously or independently. Attention is focused on optimal design of space framed structures. Three-dimensional design problems are more complicated to carry out, but they yield insight into real behavior of the structure and can help avoiding some of the problems that might appear in planar design procedure such as the need for out-of-plane buckling constraint. Although researchers in the field of structural engineering generally agree that optimum design of three-dimension building frames especially in the seismic regions would be beneficial, methods have been slow to emerge. Most of the research in this area has dealt

  7. Influence of Laser Activated Irrigation with Erbium Lasers on Bond Strength of Inidividually Formed Fiber Reinforced Composite Posts to Root Canal Dentin

    Directory of Open Access Journals (Sweden)

    Ivana Miletić

    2016-01-01

    Full Text Available Objective: The aim of this in vitro study was to investigate the effect of laser activated irrigation (LAI using two erbium lasers on bond strength of individually formed fiber-reinforced composite (FRC posts to root canal dentin. Materials and methods: Twenty-seven single-rooted human teeth were endodontically treated and after post space preparation divided into three groups (n=9 per group, according to the pre-treatment of post space preparation: 1 Conventional syringe irrigation (CSI and saline; 2 Er.YAG photon-induced photoacoustic streaming (PIPS technique and saline; 3 Er,Cr:YSGG activated irrigation with RFT2 tip. Two specimens from each group were used for SEM analysis. The remaining specimens (n=7 per group received individually formed FRC post, everStick POST, luted with self-adhesive cement, G-CEM LinkAce. After cementation, the roots were perpendicularly sectioned into 1 mm thin sections and a push-out test was carried out (0.5 mm/min. The data were calculated as megapascals and were log transformed and statistically analysed using one-way ANOVA at the level of significance set at 5%. Results: In the control group, the smear layer was still present. In the Er:YAG group, the smear layer was removed. In the Er,Cr:YSGG group, the smear layer was partially removed. The Er,Cr:YSGG group achieved the highest bond strength values, followed by the control group and then the Er:YAG group, but no statistically significant difference was found in bond strength values in the tested group of post space pretreatment (p=0.564. Conclusions: LAI using two erbium lasers, with PIPS or RFT2 tip, did not affect the bond strength of individually formed FRC posts to root canal dentin.

  8. A study on the fatigue strength characteristics of ship structural steel with gusset welds

    Directory of Open Access Journals (Sweden)

    Sung-Jo Park

    2012-06-01

    Full Text Available This study aims to assess fatigue property by the static overload and average load in the fillet welded joints which is on the ship structural steel having gusset welds. To this end, a small specimen was made, to which the same welding condition for the actual ship structure was applied, to perform fatigue tests. In this study, a method to simply assess changes in welding residual stress according to different static overload was suggested. By measuring actual strain at the weld toe, the weld stress concentration factor and property which is determined by recrystallization in the process of welding were estimated to investigate the relation between overload and fatigue strength.

  9. High strength bimetallic composite material fabricated by electroslag casting and characteristics of its composite interface

    Directory of Open Access Journals (Sweden)

    Tian-shun Dong

    2016-11-01

    Full Text Available Bimetallic composite material of bainitic steel and PD3 steel was produced with electroslag casting process, and element distribution of its composite interface was investigated by theoretical calculation and energy dispersive spectrometer (EDS. Results show that the tensile strength (1,450 MPa, hardness (HRC 41-47 and impact toughness (94.7J·cm-2 of bainitic steel were comparatively high, while its elongation was slightly low (4.0%. Tensile strength (1,100 MPa, hardness (>HRC 31 and elongation (7.72% of the interface were also relatively high, but its impact toughness was low at 20.4 J·cm-2. Results of theoretical calculation of the element distribution in the interface region were basically consistent with that of EDS. Therefore, electroslag casting is a practical process to produce bimetallic composite material of bainitic steel and PD3 steel, and theoretical calculation also is a feasible method to study element distribution of their interface.

  10. Sociodemographic Characteristics, Behavioral Problems, Parental Concerns and Children’s Strengths Reported by Parents

    Directory of Open Access Journals (Sweden)

    Deisy Ribas Emerich

    Full Text Available Abstract: Parental report is essential to understand adaptive difficulties in childhood. The aim of the study was to identify concerns of parents and qualities of children reported by parents, as well as the association of these variables with sociodemographic factors and child behavior problems. Parents of 353 schoolchildren from three public schools and one private school took part in the study. Assessment of behavior problems and parental reports about concerns and children’s strengths were obtained from the Child Behavior Checklist - CBCL. We submitted parents’ answers to the open-ended questions in the CBCL to a lexical analysis with the IRAMUTEQ software. Results concerning ‘strengths’ were related to affective and social interaction, while ‘concerns’ were related to academic performance and prevention of behavior problems. We concluded that parent concerns are targets of preventive interventions in childhood, while child strengths reported by parents are skills that need to be developed, as they help in adaptive functioning.

  11. Study on Strength and Durability Characteristics of Concrete with Ternary Blend

    Science.gov (United States)

    Nissi Joy, C.; Ramakrishnan, K.; Snega, M.; Ramasundram, S.; Venkatasubramanian, C.; Muthu, D.

    2017-07-01

    In the present scenario to fulfill the demands of sustainable construction, concrete made with multi-blended cement system of Ordinary Portland Cement (OPC) and different mineral admixtures is the wise choice for the construction industry. In this research work, M20 grade mix of concrete (with water - binder ratio as 0.48) is adopted with glass powder (GP) and Sugar Cane Bagasse Ash (SCBA) as partial replacement of cement. GP is an inert material, they occupy the landfill space for considerable amount of time unless there is a potential for recycling. Such glass wastes in the crushed form have a good potential in the infrastructure industry. Replacement of cement by GP from 30% to 0% by weight of cement in step of 5% and by SCBA from 0% to 30% in step of 5% respectively was adopted. In total, seven different combinations of mixes were studied at two different ages of concrete namely 7 and 28 days. Compressive strength of cubes for various percentage of replacement were investigated and compared with conventional concrete to find out the maximum mix ratio. Flexural strength of concrete for the maximum mix ratio was found out and durability parameters viz., water absorption and sorptivity were studied. From the experimental study, 20% SCBA and 10% GP combination was found to be the maximum mix ratio.

  12. Compressive strength and microstructural characteristics of class C fly ash geopolymer

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaolu; Shi, Huisheng; Dick, Warren A [Key Laboratory of Advanced Civil Engineering Materials (Tongji University), Shanghai (China)

    2010-02-15

    Geopolymers prepared from a class C fly ash (CFA) and a mixed alkali activator of sodium hydroxide and sodium silicate solution were investigated. A high compressive strength was obtained when the modulus of the activator viz., molar ratio of SiO{sub 2}/Na{sub 2}O was 1.5, and the proper content of this activator as evaluated by the mass proportion of Na{sub 2}O to CFA was 10%. The compressive strength of these samples was 63.4 MPa when they were cured at 75{sup o}C for 8 h followed by curing at 23{sup o}C for 28 d. In FTIR spectroscopy, the main peaks at 1036 and 1400 cm{sup -1} have been attributed to asymmetric stretching of Al-O/Si-O bonds, while those at 747 cm{sup -1} are due to the Si-O-Si/Si-O-Al bending band. The main geopolymeric gel and calcium silicate hydrate (C-S-H) gel co-exist and bond some remaining unreacted CFA spheres as observed in XRD and SEM-EXDA. The presence of gismondine (zeolite) was also observed in the XRD pattern.

  13. Theoretical Analysis of the Optical Propagation Characteristics in a Fiber-Optic Surface Plasmon Resonance Sensor

    Directory of Open Access Journals (Sweden)

    Xiaolin Zheng

    2013-06-01

    Full Text Available Surface plasmon resonance (SPR sensor is widely used for its high precision and real-time analysis. Fiber-optic SPR sensor is easy for miniaturization, so it is commonly used in the development of portable detection equipment. It can also be used for remote, real-time, and online detection. In this study, a wavelength modulation fiber-optic SPR sensor is designed, and theoretical analysis of optical propagation in the optical fiber is also done. Compared with existing methods, both the transmission of a skew ray and the influence of the chromatic dispersion are discussed. The resonance wavelength is calculated at two different cases, in which the chromatic dispersion in the fiber core is considered. According to the simulation results, a novel multi-channel fiber-optic SPR sensor is likewise designed to avoid defaults aroused by the complicated computation of the skew ray as well as the chromatic dispersion. Avoiding the impact of skew ray can do much to improve the precision of this kind of sensor.

  14. Quality characteristics and consumer acceptance of yogurt fortified with date fiber.

    Science.gov (United States)

    Hashim, I B; Khalil, A H; Afifi, H S

    2009-11-01

    Yogurt is considered a healthy food and incorporating dietary fiber will make it even healthier. Date fiber (DF), a by-product of date syrup production, is a good source of dietary fiber. The effect of fortification with DF on fresh yogurt quality was investigated. Acidity, pH, color [L* (lightness), a* (redness), and b* (yellowness) values], texture profile, sensory properties, and consumer acceptance were studied. Control yogurt (without fiber), yogurt fortified with 1.5, 3.0, and 4.5% DF, and yogurt with 1.5% wheat bran (WB) were prepared. Fortification with DF did not cause significant changes in yogurt acidity, although pH was increased. Yogurts fortified with DF had firmer texture (higher hardness values) and darker color (lower L* and higher a*) compared with control or WB yogurts. Consumer test results indicated that the appearance, color, and flavor ratings were significantly affected by fiber fortification. Yogurt fortified with up to 3% DF had similar sourness, sweetness, firmness, smoothness, and overall acceptance ratings as the control yogurt. Sensory ratings and acceptability of yogurt decreased significantly when increasing DF to 4.5% or using 1.5% WB. Flavoring yogurt fortified with 4.5% DF with vanilla did not improve flavor or overall acceptance ratings. Thus, fortifying yogurt with 3% DF produced acceptable yogurt with beneficial health effects.

  15. Application Specific Optical Fibers

    OpenAIRE

    Pal, Bishnu P.

    2010-01-01

    In this chapter we have attempted to provide a unified summary description of the most important propagation characteristics of an optical fiber followed by discussion on several variety of special fibers for realizing fiber amplifiers, dispersion compensating fibers, microstructured optical fibers, and so on. Even though huge progress has been made on development of optical fibers for telecom application, a need for developing special fibers, not necessarily for telecom alone, has arisen. Th...

  16. Electrophysiological characteristics of motor units and muscle fibers in trained and untrained young male subjects

    DEFF Research Database (Denmark)

    Duez, Lene; Qerama, Erisela; Fuglsang-Frederiksen, Anders

    2010-01-01

    We hypothesized that the amplitudes of compound muscle action potentials (CMAPs) and interference pattern analysis (IPA) would be larger in trained subjects compared with untrained subjects, possibly due to hypertrophy of muscle fibers and/or increased central drive. Moreover, we hypothesized...... and untrained subjects in IPA power spectrum and turns per second or amplitude of the CMAPs obtained by DMS. Muscle fiber hypertrophy and/or altered central drive may account for our results, but there was no indication of changes in muscle fiber excitability. Muscle Nerve, 2010....... that the untrained muscle is less excitable compared with the trained muscle. An electromyographic (EMG) needle electrode was used to record the IPA at maximal voluntary effort. The CMAP was obtained by stimulating the musculocutaneous nerve and recording the brachial biceps muscle using surface electrodes. CMAPs...

  17. Influence of the addition of soy product and wheat fiber on rheological, textural, and other quality characteristics of pizza.

    Science.gov (United States)

    Glicerina, Virginia; Balestra, Federica; Capozzi, Francesco; Dalla Rosa, Marco; Romani, Santina

    2017-11-17

    The effect of partial replacement of wheat flour with soy paste and wheat fiber on rheological, textural, physicochemical, and organoleptic characteristics of an enriched pizza base (E) was investigated in comparison with those of a control pizza base (C). New ingredients (e.g., enriched cooked ham, whey cheese, and tomato sauce realized using food industry by-products) were also used in E pizza topping to further increase its nutritional properties. Enriched dough was developed first at a laboratory level. Large and small deformation, moisture, leavening activity, and metabolic heat were tested. On the final product, produced at the industrial level, textural, color, sensory, and nutritional analyses were performed. Preliminary rheological analysis was essential to evaluate the suitability of the new pizza to be processed at industrial level. Both pizza dough samples showed a solid elastic-like behavior; however, the addition of soy and fiber increased moisture content of E pizza, due to the water binding ability of soy protein and to the effect of fibers that also decreased E dough elasticity. No differences in extensibility between the two samples were observed, whereas significantly lower values of resistance to extension and dough force were shown in sample E. These differences were likely due to the presence of soy that interfere with gluten formation and to the dietary fibers that interact with water. Ingredients used in E pizza improved its nutritional quality increasing dietary fibers and protein, and decreasing saturated fatty acids and cholesterol content, which contributed to decrease energy value, in terms of kilocalorie reduction. In this work, the effects of using new ingredients (e.g., soy paste, wheat fiber) on the rheological, textural, physicochemical, nutritional, and organoleptic characteristics of an enriched pizza type were investigated both at laboratory and industrial levels. The new pizza provides a product that combines solid

  18. Evaluation of capillary pore size characteristics in high-strength concrete at early ages

    International Nuclear Information System (INIS)

    Igarashi, Shin-ichi; Watanabe, Akio; Kawamura, Mitsunori

    2005-01-01

    The quantitative scanning electron microscope-backscattered electron (SEM-BSE) image analysis was used to evaluate capillary porosity and pore size distributions in high-strength concretes at early ages. The Powers model for the hydration of cement was applied to the interpretation of the results of image analysis. The image analysis revealed that pore size distributions in concretes with an extremely low water/binder ratio of 0.25 at early ages were discontinuous in the range of finer capillary pores. However, silica-fume-containing concretes with a water/binder ratio of 0.25 had larger amounts of fine pores than did concretes without silica fume. The presence of larger amounts of fine capillary pores in the concretes with silica fume may be responsible for greater autogenous shrinkage in the silica-fume-containing concretes at early ages

  19. Effects of hydrogen on the tensile strength characteristics of stainless steels

    International Nuclear Information System (INIS)

    Blanchard, R.; Pelissier, J.; Pluchery, M.; Commissariat a l'Energie Atomique, Saclay

    1961-01-01

    This paper deals with the effects of hydrogen on stainless steel, that might possibly be used as a canning material in hydrogen-cooled reactors. Apparent ultimate-tensile strength is only 80 per cent of initial value for hydrogen content about 50 cc NTP/ 100 g, and reduction in area decreases from 80 to 55 per cent. A special two-stage replica technique has been developed which allows fracture surface of small tensile specimens (about 0.1 mm diam.) to be examined in an electron microscope. All the specimens showed evidence of ductile character throughout the range of hydrogen contents investigated, but the aspect of the fracture surfaces gradually changes with increasing amounts. (author) [fr

  20. Fabrication characteristics and strength of polymer-impregnated concrete polymerized by accelerated electron

    International Nuclear Information System (INIS)

    Ohgishi, Sakichi; Matsunaga, Katsumi; Ono, Hironobu; Iwamoto, Takeo.

    1977-01-01

    Since the accelerated electron has by far a higher dose rate than gamma-rays, the electron polymerizing method is more suitable for the efficient fabrication of polymer-impregnated concrete (PIC) with a thin cross section. However, there are few published papers on the manufacturing process of PIC polymerized by electron beam. This experiment was carried out to investigate the effects of density of cement mortar, dose rate of electron beam (4 MeV), total exposure dose and other factors which have influences upon the strength of MMA-PIC. The density of mortar, size of cross section of mortar specimens, dose rate of electron, total exposure dose and irradiating time interval were varied respectively as follow; rho=1.55 -- 3.13 g/cm 3 (the kinds of aggregates in cement mortar used are perlite, artificial light weight aggregate, normal river sand and iron sand), t=3.5 -- 40 mm in thickness, 0.55 or 1.10 Mrads/sec, 12.5 -- 100 Mrads per face, and 15 -- 60 sec/cycle. The test results of mechanical strength of PIC show that the optimum total exposure dose is about 40 Mrads at 0.55 Mrads/sec rate and 50 Mrads at 1.1 Mrads/sec in the ordinary mortar. It is also shown that the impregnation depth from the surface of specimen has a linear relation with the density of cement mortar, and that its depth is about 1 cm in conventional mortar. (auth.)

  1. Study on Mechanical Properties of Hybrid Fiber Reinforced Concrete

    Science.gov (United States)

    He, Dongqing; Wu, Min; Jie, Pengyu

    2017-12-01

    Several common high elastic modulus fibers (steel fibers, basalt fibers, polyvinyl alcohol fibers) and low elastic modulus fibers (polypropylene fiber) are incorporated into the concrete, and its cube compressive strength, splitting tensile strength and flexural strength are studied. The test result and analysis demonstrate that single fiber and hybrid fiber will improve the integrity of the concrete at failure. The mechanical properties of hybrid steel fiber-polypropylene fiber reinforced concrete are excellent, and the cube compressive strength, splitting tensile strength and flexural strength respectively increase than plain concrete by 6.4%, 3.7%, 11.4%. Doped single basalt fiber or polypropylene fiber and basalt fibers hybrid has little effect on the mechanical properties of concrete. Polyvinyl alcohol fiber and polypropylene fiber hybrid exhibit ‘negative confounding effect’ on concrete, its splitting tensile and flexural strength respectively are reduced by 17.8% and 12.9% than the single-doped polyvinyl alcohol fiber concrete.

  2. Statistical characteristics of surface integrity by fiber laser cutting of Nitinol vascular stents

    International Nuclear Information System (INIS)

    Fu, C.H.; Liu, J.F.; Guo, Andrew

    2015-01-01

    Graphical abstract: - Highlights: • Precision kerf with tight tolerance of Nitinol stents can be cut by fiber laser. • No HAZ in the subsurface was detected due to large grain size. • Recast layer has lower hardness than the bulk. • Laser cutting speed has a higher influence on surface integrity than laser power. - Abstract: Nitinol alloys have been widely used in manufacturing of vascular stents due to the outstanding properties such as superelasticity, shape memory, and superior biocompatibility. Laser cutting is the dominant process for manufacturing Nitinol stents. Conventional laser cutting usually produces unsatisfactory surface integrity which has a significant detrimental impact on stent performance. Emerging as a competitive process, fiber laser with high beam quality is expected to produce much less thermal damage such as striation, dross, heat affected zone (HAZ), and recast layer. To understand the process capability of fiber laser cutting of Nitinol alloy, a design-of-experiment based laser cutting experiment was performed. The kerf geometry, roughness, topography, microstructure, and hardness were studied to better understand the nature of the HAZ and recast layer in fiber laser cutting. Moreover, effect size analysis was conducted to investigate the relationship between surface integrity and process parameters.

  3. Statistical characteristics of surface integrity by fiber laser cutting of Nitinol vascular stents

    Energy Technology Data Exchange (ETDEWEB)

    Fu, C.H., E-mail: cfu5@crimson.ua.edu [Dept of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); Liu, J.F. [Dept of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); Guo, Andrew [Dept of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); College of Arts and Science, Vanderbilt University, Nashville, TN 37235 (United States)

    2015-10-30

    Graphical abstract: - Highlights: • Precision kerf with tight tolerance of Nitinol stents can be cut by fiber laser. • No HAZ in the subsurface was detected due to large grain size. • Recast layer has lower hardness than the bulk. • Laser cutting speed has a higher influence on surface integrity than laser power. - Abstract: Nitinol alloys have been widely used in manufacturing of vascular stents due to the outstanding properties such as superelasticity, shape memory, and superior biocompatibility. Laser cutting is the dominant process for manufacturing Nitinol stents. Conventional laser cutting usually produces unsatisfactory surface integrity which has a significant detrimental impact on stent performance. Emerging as a competitive process, fiber laser with high beam quality is expected to produce much less thermal damage such as striation, dross, heat affected zone (HAZ), and recast layer. To understand the process capability of fiber laser cutting of Nitinol alloy, a design-of-experiment based laser cutting experiment was performed. The kerf geometry, roughness, topography, microstructure, and hardness were studied to better understand the nature of the HAZ and recast layer in fiber laser cutting. Moreover, effect size analysis was conducted to investigate the relationship between surface integrity and process parameters.

  4. Effect of age and sex on fiber and follicle characteristics of an Iranian ...

    African Journals Online (AJOL)

    All the hair follicles were surrounded by associated structures such as the sweat and sebaceous glands and arrector pili muscles and located only in papillary layer of the dermis. The most common number of the secondary hair follicles in compound hair follicles was 4. The histology of all fibers and follicles in various skin ...

  5. Mechanical Properties of Steel Fiber Reinforced all Lightweight Aggregate Concrete

    Science.gov (United States)

    Yang, Y. M.; Li, J. Y.; Zhen, Y.; Nie, Y. N.; Dong, W. L.

    2018-05-01

    In order to study the basic mechanical properties and failure characteristics of all lightweight aggregate concrete with different volume of steel fiber (0%, 1%, 2%), shale ceramsite is used as light coarse aggregate. The shale sand is made of light fine aggregate and mixed with different volume of steel fiber, and the mix proportion design of all lightweight aggregate concrete is carried out. The cubic compressive strength, axial compressive strength, flexural strength, splitting strength and modulus of elasticity of steel fiber all lightweight aggregate concrete were studied. Test results show that the incorporation of steel fiber can restrict the cracking of concrete, improve crack resistance; at the same time, it shows good plastic deformation ability and failure morphology. It lays a theoretical foundation for further research on the application of all lightweight aggregate concrete in structural systems.

  6. SHEAR STRENGTH, COLLAPSIBILITY AND COMPRESSIBILITY CHARACTERISTICS OF COMPACTED BAIJI DUNE SOILS

    Directory of Open Access Journals (Sweden)

    ABBAS JAWAD AL-TAIE

    2017-03-01

    Full Text Available Baiji city is a vital industrial centre in Iraq since it has the biggest oil refinery. Therefore, Baiji has become an attractive site for strategic construction projects. Dune sand covers about 220 km2 of the area of Baiji city. However, few researches had attempted to study its behaviour. In this study laboratory tests were conducted to determine the shear strength, collapsibility and compressibility of the dune sand at its natural and compacted status. The effect of dry unit weight, moisture content, relative density and soaking on mechanical properties of dune soil was investigated. The results demonstrated that dry and soaked dune specimens tested at their in-situ condition exhibited similar volume changes during shear and identical friction angles. The results of shear tests of both of compacted soaked and unsoaked samples were identical. The collapse potential of dune soil is inversely proportional with the relative density. The minimum axial strain is observed when the samples are compacted to modified effort. The compression index of the compacted specimens is affected by moulding water content, while the rebound index is less sensitive.

  7. Precipitation characteristic of high strength steels microalloyed with titanium produced by compact strip production

    Institute of Scientific and Technical Information of China (English)

    Jian Zhou; Yonglin Kang; Xinping Mao

    2008-01-01

    Transmission electron microscopy (TEM) and physics-chemical phase analysis were employed to investigate the precipitates in high strength steels microalloyed with Ti produced by compact strip production (CSP). It was seen that precipitates in Ti mieroalloyed steels mainly included TiN, Ti4C2S2, and TiC. The size of TiN particles varied from 50 to 500 nm, and they could precipitate during or before soaking. The Ti4C2S>2 with the size of 40-100 nm might precipitate before rolling, and the TiC particles with the size of 5-50 nm precipitated heterogeneously. High Ti content would lead to the presence of bigger TiC particles that precipitated in austenite, and by contrast, TiC particles that precipitated in ferrite and the transformation of austenite to ferrite was smaller. They were less than 30 nm and mainly responsible for precipitate strengthening. It should be noted that the TiC particles in higher Ti content were generally smaller than those in the steel with a lower Ti content.

  8. Increase in the strength characteristics of Portland cement due to introduction of the compound mineral supplements

    Science.gov (United States)

    Il'ina, Liliia; Gichko, Nikolai; Mukhina, Irina

    2016-01-01

    At the initial phase of hardening it is the limestone component that plays a major role in the hardening process, which acts as the substrate for the crystallization of hydrate tumors due to its chemical affinity with the products of Portland cement hydration. After 7 days, the diopside supplement influences the processes more significantly. Diopside has a high modulus of elasticity compared to the cement paste. As a result, stresses are redistributed within the cement paste and the whole composition is hardened. An increase in the quantity of diopside in the compound supplement to more than 66.7% does not provide a substantial increase in the strength of the cement paste. As the hardness of diopside is higher than the hardness of limestone, much more energy is required to grind it down to a usable component. Therefore, a further increase in the quantity of diopside in the compound supplement is not economically feasible. An evaluation of the optimum quantity of input compound mineral supplements can be made based on the ideas of close packing of spherical particles and the Pauling rules. The optimum content of the supplement is 8-8.5% provided that its dispersion and density are close to the dispersion and density of the binder. An increase in the dispersion of the supplement reduces its optimal quantity.

  9. Study of the Emission Characteristics of Single-Walled CNT and Carbon Nano-Fiber Pyrograf III

    Science.gov (United States)

    Mousa, Marwan S.; Al-Akhras, M.-Ali H.; Daradkeh, Samer

    2018-02-01

    Field emission microscopy measurements from Single-Walled Carbon Nanotubes (SWCNTs) and Carbon Nano-Fibers Pyrograf III PR-1 (CNF) were performed. Details of the materials employed in the experiments are as follows: (a) Carbon Nano-Fibers Pyrograf III PR-1 (CNF), having an average fiber diameter that is ranging between (100-200) nm with a length of (30-100) μm. (b) Single walled Carbon Nanotubes were produced by high-pressure CO over Fe particle (HiPCO: High-Pressure Carbon Monoxide process), having an average diameter ranging between (1-4) nm with a length of (1-3) μm. The experiments were performed under vacuum pressure value of (10-7 mbar). The research work reported here includes the field electron emission current-voltage (I-V) characteristics and presented as Fowler-Nordheim (FN) plots and the spatial emission current distributions (electron emission images) obtained and analyzed in terms of electron source features. For both the SWCNT and the CNF a single spot pattern for the electron spatial; distributions were observed.

  10. Tissue-engineering with muscle fiber fragments improves the strength of a weak abdominal wall in rats

    DEFF Research Database (Denmark)

    Jangö, Hanna; Gräs, Søren; Christensen, Lise

    2017-01-01

    INTRODUCTION AND HYPOTHESIS: Alternative approaches to reinforce the native tissue in patients with pelvic organ prolapse (POP) are needed to improve surgical outcome. Our aims were to develop a weakened abdominal wall in a rat model to mimic the weakened vaginal wall in women with POP and then e...... showed a significantly higher strength than the group with MPEG-PLGA alone (p = 0.034). CONCLUSION: Tissue-engineering with MFFs seeded on a scaffold of biodegradable MPEG-PLGA might be an interesting adjunct to future POP repair.......INTRODUCTION AND HYPOTHESIS: Alternative approaches to reinforce the native tissue in patients with pelvic organ prolapse (POP) are needed to improve surgical outcome. Our aims were to develop a weakened abdominal wall in a rat model to mimic the weakened vaginal wall in women with POP...

  11. Towards Rocket Engine Components with Increased Strength and Robust Operating Characteristics

    Science.gov (United States)

    Marcu, Bogdan; Hadid, Ali; Lin, Pei; Balcazar, Daniel; Rai, Man Mohan; Dorney, Daniel J.

    2005-01-01

    High-energy rotating machines, powering liquid propellant rocket engines, are subject to various sources of high and low cycle fatigue generated by unsteady flow phenomena. Given the tremendous need for reliability in a sustainable space exploration program, a fundamental change in the design methodology for engine components is required for both launch and space based systems. A design optimization system based on neural-networks has been applied and demonstrated in the redesign of the Space Shuttle Main Engine (SSME) Low Pressure Oxidizer Turbo Pump (LPOTP) turbine nozzle. One objective of the redesign effort was to increase airfoil thickness and thus increase its strength while at the same time detuning the vane natural frequency modes from the vortex shedding frequency. The second objective was to reduce the vortex shedding amplitude. The third objective was to maintain this low shedding amplitude even in the presence of large manufacturing tolerances. All of these objectives were achieved without generating any detrimental effects on the downstream flow through the turbine, and without introducing any penalty in performance. The airfoil redesign and preliminary assessment was performed in the Exploration Technology Directorate at NASA ARC. Boeing/Rocketdyne and NASA MSFC independently performed final CFD assessments of the design. Four different CFD codes were used in this process. They include WIL DCA T/CORSAIR (NASA), FLUENT (commercial), TIDAL (Boeing Rocketdyne) and, a new family (AardvarWPhantom) of CFD analysis codes developed at NASA MSFC employing LOX fluid properties and a Generalized Equation Set formulation. Extensive aerodynamic performance analysis and stress analysis carried out at Boeing Rocketdyne and NASA MSFC indicate that the redesign objectives have been fully met. The paper presents the results of the assessment analysis and discusses the future potential of robust optimal design for rocket engine components.

  12. Impact of Steel Fiber Size and Shape on the Mechanical Properties of Ultra-High Performance Concrete

    Science.gov (United States)

    2015-08-01

    characteristics of steel fiber reinforcement to the mechanical properties of high-strength concretes , this study investigated four commercially available...Standard test method for flexural performance of fiber - reinforced concrete (using beam with third-point loading). Designation: C1609/1609M. West...STEEL FIBERS are low-carbon, drawn w ire for reinforced concrete . NYCON-SF fibers distribute stresses within the concrete and provide improvement

  13. Cyclic behavior, development, and characteristics of a ductile hybrid fiber-reinforced polymer (DHFRP) for reinforced concrete members

    Science.gov (United States)

    Hampton, Francis Patrick

    Reinforced concrete (R/C) structures especially pavements and bridge decks that constitute vital elements of the infrastructure of all industrialized societies are deteriorating prematurely. Structural repair and upgrading of these structural elements have become a more economical option for constructed facilities especially in the United States and Canada. One method of retrofitting concrete structures is the use of advanced materials. Fiber reinforced polymer (FRP) composite materials typically are in the form of fabric sheets or reinforcing bars. While the strength and stiffness of the FRP is high, composites are inherently brittle, with limited or no ductility. Conventional FRP systems cannot currently meet ductility demand, and therefore, may fail in a catastrophic failure mode. The primary goal of this research was to develop an optimized prototype 10-mm diameter DHFRP bar. The behavior of the bar under full load reversals to failure was investigated. However, this bar first needed to be designed and manufactured in the Fibrous Materials Research at Drexel University. Material properties were determined through testing to categorize the strength properties of the DHFRP. Similitude was used to demonstrate the scaling of properties from the original model bars. The four most important properties of the DHFRP bars are sufficient strength and stiffness, significant ductility for plasticity to develop in the R/C section, and sufficient bond strength for the R/C section to develop its full strength. Once these properties were determined the behavior of reinforced concrete members was investigated. This included the testing of prototype-size beams under monotonic loading and model and prototype beam-columns under reverse cyclic loading. These tests confirmed the large ductility exhibited by the DHFRP. Also the energy absorption capacity of the bar was demonstrated by the hysteretic behavior of the beam-columns. Displacement ductility factors in the range of 3

  14. Refractive index and temperature sensitivity characteristics of a micro-slot fiber Bragg grating.

    Science.gov (United States)

    Saffari, Pouneh; Yan, Zhijun; Zhou, Kaiming; Zhang, Lin

    2012-07-10

    Fabrication and characterization of a UV inscribed fiber Bragg grating (FBG) with a micro-slot liquid core is presented. Femtosecond (fs) laser patterning/chemical etching technique was employed to engrave a micro-slot with dimensions of 5.74 μm(h)×125 μm(w)×1388.72 μm(l) across the whole grating. The device has been evaluated for refractive index (RI) and temperature sensitivities and exhibited distinctive thermal response and RI sensitivity beyond the detection limit of reported fiber gratings. This structure has not just been RI sensitive, but also maintained the robustness comparing with the bare core FBGs and long-period gratings with the partial cladding etched off.

  15. Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide

    OpenAIRE

    Kim, Gun-Hee; Lee, Jeong-Won; Seo, Tae-Il

    2013-01-01

    Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this stud...

  16. Thermal characteristics of an end-pumped high-power ytterbium-sensitized erbium-doped fiber laser under natural convection.

    Science.gov (United States)

    Jeong, Y; Baek, S; Dupriez, P; Maran, J-N; Sahu, J K; Nilsson, J; Lee, B

    2008-11-24

    We investigate the thermal characteristics of a polymer-clad fiber laser under natural convection when it is strongly pumped up to the damage point of the fiber. For this, we utilize a temperature sensing technique based on a fiber Bragg grating sensor array. We have measured the longitudinal temperature distribution of a 2.4-m length ytterbium-sensitized erbium-doped fiber laser that was end-pumped at approximately 975 nm. The measured temperature distribution decreases exponentially, approximately, decaying away from the pump-launch end. We attribute this to the heat dissipation of absorbed pump power. The maximum temperature difference between the fiber ends was approximately 190 K at the maximum pump power of 60.8 W. From this, we estimate that the core temperature reached approximately 236 degrees C.

  17. Axial Collapse Characteristics of Aluminum/Carbon Fiber Reinforced Plastic Composite Thin-Walled Members with Different Section Shapes

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Woo Chae; Kim, Ji Hoon; Yang, In Young [Chosun University, Gwangju (Korea, Republic of); Lee, Kil Sung [Humancomposites CO. Ltd, Gunsan (Korea, Republic of); Cha, Cheon Seok [Dongkang College, Gwangju (Korea, Republic of); Ra, Seung Woo [SEOUL METAL CO. Ltd, Seoul (Korea, Republic of)

    2014-09-15

    In the present study, we aimed to obtain design data that can be used for the side members of lightweight cars by experimentally examining the types of effects that the changes in the section shape and outermost layer of an aluminum (Al)/carbon fiber reinforced plastic (CFRP) composite structural member have on its collapse characteristics. We have drawn the following conclusions based on the test results: The circular Al/CFRP composite impact-absorbing member in which the outermost layer angle was laminated at 0° was observed to be 52.9 and 49.93 higher than that of the square and hat-shaped members, respectively. In addition, the energy absorption characteristic of the circular Al/CFRP composite impact-absorbing member in which the outermost layer angle was laminated at 90° was observed to be 50.49 and 49.2 higher than that of the square and hat-shaped members, respectively.

  18. Adhesion strength and spreading characteristics of EPS on membrane surfaces during lateral and central growth.

    Science.gov (United States)

    Tansel, Berrin; Tansel, Derya Z

    2013-11-01

    Deposition of extracellular polymeric substances (EPS) on membrane surfaces is a precursor step for bacterial attachment. The purpose of this study was to analyze the morphological changes on a clean polysulfone ultrafilration membrane after exposure to effluent from a membrane bioreactor. The effluent was filtered to remove bacteria before exposing the membrane. The morphological characterization was performed by atomic force microscopy (AFM). The lateral (2D) and central growth characteristics (3D) of the EPS deposits were evaluated by section and topographical analyses of the height images. The contact angle of single EPS units was 9.07 ± 0.50° which increased to 24.41 ± 1.00° for large clusters (over 10 units) and decreased to 18.68 ± 1.00° for the multilayered clusters. The surface tension of the single EPS units was 49.34 ± 1.70 mNm(-1). The surface tension of single layered small and large EPS clusters were 51.26 ± 2.05 and 53.48 ± 2.01 mNm(-1), respectively. For the multilayered clusters, the surface tension was 51.43 ± 2.05 mNm(-1). The spreading values were negative for all deposits on the polysulfone membrane indicating that the EPS clusters did not have tendency to spread but preferred to retain their shapes. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Comparison of anthropometry, upper-body strength, and lower-body power characteristics in different levels of Australian football players.

    Science.gov (United States)

    Bilsborough, Johann C; Greenway, Kate G; Opar, David A; Livingstone, Steuart G; Cordy, Justin T; Bird, Stephen R; Coutts, Aaron J

    2015-03-01

    The aim of this study was to compare the anthropometry, upper-body strength, and lower-body power characteristics in elite junior, sub-elite senior, and elite senior Australian Football (AF) players. Nineteen experienced elite senior (≥4 years Australian Football League [AFL] experience), 27 inexperienced elite senior (free soft tissue mass [FFSTM], fat mass, and bone mineral content) with dual-energy x-ray absorptiometry, upper-body strength (bench press and bench pull), and lower-body power (countermovement jump [CMJ] and squat jump with 20 kg). A 1-way analysis of variance assessed differences between the playing levels in these measures, whereas relationships between anthropometry and performance were assessed with Pearson's correlation. The elite senior and sub-elite senior players were older and heavier than the elite junior players (p ≤ 0.05). Both elite playing groups had greater total FFSTM than both the sub-elite and junior elite players; however, there were only appendicular FFSTM differences between the junior elite and elite senior players (p squat performance measures (r = 0.33-0.55). Australian Football players' FFSTM are different between playing levels, which are likely because of training and partly explain the observed differences in performance between playing levels highlighting the importance of optimizing FFSTM in young players.

  20. Design of strength characteristics on the example of a mining support

    Science.gov (United States)

    Gwiazda, A.; Sękala, A.; Banaś, W.; Topolska, S.; Foit, K.; Monica, Z.

    2017-08-01

    It is a special group of particular design aproches that could be characterized as “design for X”. All areas of specific these design methodology, taking into account the requirements of the life cycle are described with the acronym DfX. It means an integrated computing platform approach to design binding together both the area of design knowledge and area of computer systems. In this perspective, computer systems are responsible for the link between design requirements with the subject of the project and to filter the information being circulated throughout the operation of the project. The DfX methodologies together form an approach integrating to different functional areas of industrial organization. Among the internal elements it can distinguish the structure of the project team, the people making it, the same process design, control system design and implementation of the action tools to assist this process. Among the elements that are obtained in the framework of this approach should be distinguished: higher operating efficiency, professionalism, the ability to create innovation, incremental progress of the project and the appropriate focus of the project team. It have been done attempts to integrate identified specific areas for action in the field of design methodology. They have already taken place earlier in the design due to the Economic Design for Manufacture. This approach was characteristic for European industry. In this case, an approach was developed in methodology, which can be defined as the Design to/for Cost. The article presents the idea of an integrated design approach related with the DfX approach. The results are described on the base of a virtual 3D model of a mining support. This model was elaborated in the advanced engineering platform like Siemens PLM NX.

  1. Evaluation of the impact of higher-order energy enhancement characteristics of solitons in strongly dispersion-managed optical fibers

    International Nuclear Information System (INIS)

    Diaz-Otero, Francisco J.; Guillán-Lorenzo, Omar; Pedrosa-Rodríguez, Laura

    2017-01-01

    Highlights: • Empirical model describing the pulse energy enhancement required to obtain stable pulses to higher-order polynomial equations • An improvement in the accuracy is obtained through the addition of a new quartic addend dependent on the map strength. • This conclusion is validated through a comparison in a commercial DM soliton submarine network. • The error in the interaction distance for two adjacent pulses in the same channel is of the same order as the energy error - Abstract: We study the propagation properties of nonlinear pulses with periodic evolution in a dispersion-managed transmission link by means of a variational approach. We fit the energy enhancement required for stable propagation of a single soliton in a prototypical commercial link to a polynomial approximation that describes the dependence of the energy on the map strength of the normalized unit cell. We present an improvement of a relatively old and essential result, namely, the dependence of the energy-enhancement factor of dispersion-management solitons with the square of the map strength of the fiber link. We find that adding additional corrections to the conventional quadratic formula up to the fourth order results in an improvement in the accuracy of the description of the numerical results obtained with the variational approximation. Even a small error in the energy is found to introduce large deviations in the pulse parameters during its evolution. The error in the evaluation of the interaction distance between two adjacent time division multiplexed pulses propagating in the same channel in a prototypical submarine link is of the same order as the error in the energy.

  2. Development of HMPE fiber for deep water permanent mooring applications

    Energy Technology Data Exchange (ETDEWEB)

    Vlasblom, Martin; Fronzaglia, Bill; Boesten, Jorn [DSM Dyneema, Urmond (Netherlands); Leite, Sergio [Lankhorst Ropes, Sneek (Netherlands); Davies, Peter [Institut Francais de Recherche pour L' Exploration de la Mer (IFREMER) (France)

    2012-07-01

    For a number of years, the creep performance of standard High Modulus Polyethylene (HMPE) fiber types has limited their use in synthetic offshore mooring systems. In 2003, a low creep HMPE fiber was introduced and qualified for semi-permanent MODU moorings. This paper reports on a new High Modulus Polyethylene fiber type with significantly improved creep properties compared to any other HMPE fiber type, which, for the first time, allows its use in permanent offshore mooring systems, for example for deep water FPSO moorings. Results on fiber and rope creep experiments and stiffness measurements are reported. Laboratory testing shows that ropes made with the new fiber type retain the properties characteristic of HMPE such as high static strength, high fatigue resistance and stiffness, and illustrate that stiffness properties determined on HMPE fiber or rope are dependent on the applied load and temperature. (author)

  3. Effect of fiber orientation on tensile and impact properties of Zalacca Midrib fiber-HDPE composites by compression molding

    Science.gov (United States)

    Lasikun, Ariawan, Dody; Surojo, Eko; Triyono, Joko

    2018-02-01

    The research aims to investigate the fiber orientation effect on the tensile and impact properties of zalacca midrib fiber /HDPE composites. The composites were produced by compression molding with pressing temperature at 150°C, pressing pressure at 50 bar, and holding time of 25 minutes. The fiber orientations applied in composites were 0°, 15°, 30°, 45°, 60°, 75°, and 90°, at 10% fiber volume fraction. The samples were evaluated by using: Tensile test and Izod impact test according to ASTM D638 and ASTM D5941, respectively. The result of experiments indicate that the orientation of zalacca midrib fiber influences the characteristics of HDPE composite-zalacca midrib fiber. The composite mechanical strength decline with the increase of orientation fibers from 0° to 90°. The composite failure mode of composites are observed by Scanning Electron Microscope (SEM).

  4. [Ecological regionalization of national cotton fiber quality in China using GGE biplot analysis method].

    Science.gov (United States)

    Xu, Nai Yin; Jin, Shi Qiao; Li, Jian

    2017-01-01

    The distinctive regional characteristics of cotton fiber quality in the major cotton-producing areas in China enhance the textile use efficiency of raw cotton yarn by improving fiber quality through ecological regionalization. The "environment vs. trait" GGE biplot analysis method was adopted to explore the interaction between conventional cotton sub-regions and cotton fiber quality traits based on the datasets collected from the national cotton regional trials from 2011 to 2015. The results showed that the major cotton-producing area in China were divided into four fiber quality ecological regions, namely, the "high fiber quality ecological region", the "low micronaire ecological region", the "high fiber strength and micronaire ecological region", and the "moderate fiber quality ecological region". The high fiber quality ecological region was characterized by harmonious development of cotton fiber length, strength, micronaire value and the highest spinning consistency index, and located in the conventional cotton regions in the upper and lower reaches of Yangtze River Valley. The low micronaire value ecological region composed of the northern and south Xinjiang cotton regions was characterized by low micronaire value, relatively lower fiber strength, and relatively high spinning consistency index performance. The high fiber strength and micronaire value ecological region covered the middle reaches of Yangtze River Valley, Nanxiang Basin and Huaibei Plain, and was prominently characterized by high strength and micronaire value, and moderate performance of other traits. The moderate fiber quality ecological region included North China Plain and Loess Plateau cotton growing regions in the Yellow River Valley, and was characterized by moderate or lower performances of all fiber quality traits. This study effectively applied "environment vs. trait" GGE biplot to regionalize cotton fiber quality, which provided a helpful reference for the regiona-lized cotton growing

  5. The influence of controlled nutrition intensity on the muscle fiber characteristics in fattening pigs

    Directory of Open Access Journals (Sweden)

    Luboš Brzobohatý

    2015-03-01

    Full Text Available The aim of this study was to evaluate the influence of controlled nutrition on the selected muscle fibres indicators and carcass value in pork. The test included 72 hybrid pigs of the D x (LWD x L genotype of a balanced sex (barrows/gilts. Animals were divided into two groups; the 1st (control group was fed ad libitum, while the nutrition of the 2nd (experimental group was restricted upon reaching 80 kg of live weight. The nutritional restriction was achieved by feeding the animals with maximum dose of CFM up to 2.8 kg*day-1 (corresponding to 36.4 MJ ME*day-1, 46.76 g NS*day-1 and 23.52 g LYS*day-1. From the obtained results it is evident that the daily feed intake restriction corresponds with greater number of the MLLT muscle fibers as well as with a higher IIB type muscle fibers share, higher lean meat share and a higher shoulder proportion in the carcass.

  6. Evanescent Field Enhancement in Liquid Crystal Optical Fibers: A Field Characteristics Based Analysis

    Directory of Open Access Journals (Sweden)

    P. K. Choudhury

    2013-01-01

    Full Text Available The paper presents the analysis of the electromagnetic wave propagation through liquid crystal optical fibers (LCOFs of two different types—conventional guides loaded with liquid crystals (addressed as LCOFs and those with additional twists due to conducting helical windings (addressed as HCLCOFs. More precisely, the three-layer optical waveguide structures are considered along with its outermost region being loaded with radially anisotropic liquid crystal material and the inner regions being made of usual silica, as used in conventional optical fibers. In addition to that, LCOF with twists introduced in the form of conducting helical windings at the interface of the silica core and the liquid crystal clad is also taken into account. Emphasis has been put on the power confinements by the lower-order TE modes sustained in the different sections of the LCOF structure. The results demonstrate useful applications of these guides in integrated optics as the power sustained in the liquid crystal section by the excited TE modes remains very high. In the case of twisted clad liquid crystal guides, descriptions are limited to the nature of dispersion relation only under the TE mode excitation, and corresponding to the cases of helix orientations being parallel and perpendicular to the optical axis.

  7. Interface and its effect on the interlaminate shear strength of novel glass fiber/hyperbranched polysiloxane modified maleimide-triazine resin composites

    International Nuclear Information System (INIS)

    Liu Ping; Guan Qingbao; Gu Aijuan; Liang Guozheng; Yuan Li; Chang Jianfei

    2011-01-01

    Interface is Key topic of developing advanced fiber reinforced polymeric composites. Novel advanced glass woven fabric (GF) reinforced composites, coded as GF/mBT, were prepared, of which the matrix resin was hyperbranched polysiloxane (HBPSi) modified maleimide-triazine (mBT) resin. The influence of the composition of the matrix on the interfacial nature of the GF/mBT composites were studied and compared with that of the composite based on GF and BT resin using contact angle, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and dielectric properties over wide frequency and temperature ranges. Results show that the interfacial nature of the composites is dependent on the chemistries of the matrices, mBT matrices have better interfacial adhesion with GF than BT resin owing to the formation of chemical and hydrogen bonds between mBT resin and GF; while in the case of mBT resins, the content of HBPSi also plays an important role on the interfacial feature and thus the macro-performance. Specifically, with increasing the content of HBPSi in the matrix, the interlaminate shear strength of corresponding composites significantly improves, demonstrating that better interfacial adhesion guarantees outstanding integrated properties of the resultant composites.

  8. A novel anaerobic electrochemical membrane bioreactor (AnEMBR) with conductive hollow-fiber membrane for treatment of low-organic strength solutions

    KAUST Repository

    Katuri, Krishna; Werner, Craig M.; Jimenez Sandoval, Rodrigo J.; Chen, Wei; Jeon, Sungil; Logan, Bruce E.; Lai, Zhiping; Amy, Gary L.; Saikaly, Pascal

    2014-01-01

    A new anaerobic treatment system that combined a microbial electrolysis cell (MEC) with membrane filtration using electrically conductive, porous, nickel-based hollow-fiber membranes (Ni-HFMs) was developed to treat low organic strength solution and recover energy in the form of biogas. This new system is called an anaerobic electrochemical membrane bioreactor (AnEMBR). The Ni-HFM served the dual function as the cathode for hydrogen evolution reaction (HER) and the membrane for filtration of the effluent. The AnEMBR system was operated for 70 days with synthetic acetate solution having a chemical oxygen demand (COD) of 320 mg/L. Removal of COD was >95% at all applied voltages tested. Up to 71% of the substrate energy was recovered at an applied voltage of 0.7 V as methane rich biogas (83% CH4; < 1% H2) due to biological conversion of the hydrogen evolved at the cathode to methane. A combination of factors (hydrogen bubble formation, low cathode potential and localized high pH at the cathode surface) contributed to reduced membrane fouling in the AnEMBR compared to the control reactor (open circuit voltage). The net energy required to operate the AnEMBR system at an applied voltage of 0.7 V was significantly less (0.27 kWh/m3) than that typically needed for wastewater treatment using aerobic membrane bioreactors (1-2 kWh/m3).

  9. A novel anaerobic electrochemical membrane bioreactor (AnEMBR) with conductive hollow-fiber membrane for treatment of low-organic strength solutions

    KAUST Repository

    Katuri, Krishna

    2014-11-04

    A new anaerobic treatment system that combined a microbial electrolysis cell (MEC) with membrane filtration using electrically conductive, porous, nickel-based hollow-fiber membranes (Ni-HFMs) was developed to treat low organic strength solution and recover energy in the form of biogas. This new system is called an anaerobic electrochemical membrane bioreactor (AnEMBR). The Ni-HFM served the dual function as the cathode for hydrogen evolution reaction (HER) and the membrane for filtration of the effluent. The AnEMBR system was operated for 70 days with synthetic acetate solution having a chemical oxygen demand (COD) of 320 mg/L. Removal of COD was >95% at all applied voltages tested. Up to 71% of the substrate energy was recovered at an applied voltage of 0.7 V as methane rich biogas (83% CH4; < 1% H2) due to biological conversion of the hydrogen evolved at the cathode to methane. A combination of factors (hydrogen bubble formation, low cathode potential and localized high pH at the cathode surface) contributed to reduced membrane fouling in the AnEMBR compared to the control reactor (open circuit voltage). The net energy required to operate the AnEMBR system at an applied voltage of 0.7 V was significantly less (0.27 kWh/m3) than that typically needed for wastewater treatment using aerobic membrane bioreactors (1-2 kWh/m3).

  10. Bond-Slip Behavior of Basalt Fiber Reinforced Polymer Bar in Concrete Subjected to Simulated Marine Environment: Effects of BFRP Bar Size, Corrosion Age, and Concrete Strength

    Directory of Open Access Journals (Sweden)

    Yongmin Yang

    2017-01-01

    Full Text Available Basalt Fiber Reinforced Polymer (BFRP bars have bright potential application in concrete structures subjected to marine environment due to their superior corrosion resistance. Available literatures mainly focused on the mechanical properties of BFRP concrete structures, while the bond-slip behavior of BFRP bars, which is a key factor influencing the safety and service life of ocean concrete structures, has not been clarified yet. In this paper, effects of BFRP bars size, corrosion age, and concrete strength on the bond-slip behavior of BFRP bars in concrete cured in artificial seawater were investigated, and then an improved Bertero, Popov, and Eligehausen (BPE model was employed to describe the bond-slip behavior of BFRP bars in concrete. The results indicated that the maximum bond stress and corresponding slip decreased gradually with the increase of corrosion age and size of BFRP bars, and ultimate slip also decreased sharply. The ascending segment of bond-slip curve tends to be more rigid and the descending segment tends to be softer after corrosion. A horizontal end in bond-slip curve indicates that the friction between BFRP bars and concrete decreased sharply.

  11. Modeling the Role of Bulk and Surface Characteristics of Carbon Fiber on Thermal Conductance across the Carbon Fiber/Matrix Interface (Postprint)

    Science.gov (United States)

    2015-11-09

    heat flow from carbon fiber to the matrix (most of the laser energy is absorbed by the carbon fiber), subsequently determining the temperature rise and...Reductase- Trimethoprim , a Drug-Receptor System. Proteins: Struct., Funct., Genet. 1988, 4, 31−47. (37) Sun, H.; Mumby, S. J.; Maple, J. R.; Hagler, A. T

  12. Deposition characteristics of titanium coating deposited on SiC fiber by cold-wall chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xian, E-mail: luo_shenfan@hotmail.com; Wu, Shuai; Yang, Yan-qing; Jin, Na; Liu, Shuai; Huang, Bin

    2016-12-01

    The deposition characteristics of titanium coating on SiC fiber using TiCl{sub 4}-H{sub 2}-Ar gas mixture in a cold-wall chemical vapor deposition were studied by the combination of thermodynamic analysis and experimental studies. The thermodynamic analysis of the reactions in the TiCl{sub 4}-H{sub 2}-Ar system indicates that TiCl{sub 4} transforms to titanium as the following paths: TiCl{sub 4} → TiCl{sub 3} → Ti, or TiCl{sub 4} → TiCl{sub 3} → TiCl{sub 2} → Ti. The experimental results show that typical deposited coating contains two distinct layers: a TiC reaction layer close to SiC fiber and titanium coating which has an atomic percentage of titanium more than 70% and that of carbon lower than 30%. The results illustrate that a carbon diffusion barrier coating needs to be deposited if pure titanium is to be prepared. The deposition rate increases with the increase of temperature, but higher temperature has a negative effect on the surface uniformity of titanium coating. In addition, appropriate argon gas flow rate has a positive effect on smoothing the surface morphology of the coating. - Highlights: • Both thermodynamic analysis and experimental studies were adopted in this work. • The transformation paths of TiCl{sub 4} to Ti is: TiCl{sub 4} → TiCl{sub 3} → Ti, or TiCl{sub 4} → TiCl{sub 3} → TiCl{sub 2} → Ti. • Typical deposited Ti coating on SiC fiber contained two distinct layers. • Deposition temperature is important on deposition rate and morphologies. • Appropriate argon gas flow rate has a positive effect on smoothing of the coating.

  13. Statistical characteristics of climbing fiber spikes necessary for efficient cerebellar learning.

    Science.gov (United States)

    Kuroda, S; Yamamoto, K; Miyamoto, H; Doya, K; Kawat, M

    2001-03-01

    Mean firing rates (MFRs), with analogue values, have thus far been used as information carriers of neurons in most brain theories of learning. However, the neurons transmit the signal by spikes, which are discrete events. The climbing fibers (CFs), which are known to be essential for cerebellar motor learning, fire at the ultra-low firing rates (around 1 Hz), and it is not yet understood theoretically how high-frequency information can be conveyed and how learning of smooth and fast movements can be achieved. Here we address whether cerebellar learning can be achieved by CF spikes instead of conventional MFR in an eye movement task, such as the ocular following response (OFR), and an arm movement task. There are two major afferents into cerebellar Purkinje cells: parallel fiber (PF) and CF, and the synaptic weights between PFs and Purkinje cells have been shown to be modulated by the stimulation of both types of fiber. The modulation of the synaptic weights is regulated by the cerebellar synaptic plasticity. In this study we simulated cerebellar learning using CF signals as spikes instead of conventional MFR. To generate the spikes we used the following four spike generation models: (1) a Poisson model in which the spike interval probability follows a Poisson distribution, (2) a gamma model in which the spike interval probability follows the gamma distribution, (3) a max model in which a spike is generated when a synaptic input reaches maximum, and (4) a threshold model in which a spike is generated when the input crosses a certain small threshold. We found that, in an OFR task with a constant visual velocity, learning was successful with stochastic models, such as Poisson and gamma models, but not in the deterministic models, such as max and threshold models. In an OFR with a stepwise velocity change and an arm movement task, learning could be achieved only in the Poisson model. In addition, for efficient cerebellar learning, the distribution of CF spike

  14. Fiber reinforced concrete as a material for nuclear reactor containment buildings

    International Nuclear Information System (INIS)

    Mallikarjuna; Banthia, N.; Mindess, S.

    1991-01-01

    The fiber reinforced concrete as a constructional material for nuclear reactor containment buildings calls for an examination of its individual characteristics and potentialities due to its inherent superiority over normal plain and reinforced concrete. In the present investigation, first, to study the static behavior of straight, hooked-end and crimped fibers, recently developed nonlinear three-dimensional interface (contact) element has been used in conjunction with the eight nodded hexahedron and two nodded bar elements for concrete and steel fiber respectively. Then impact tests were carried out on fiber reinforced concrete beams with an instrumented drop weight impact machine. Two different concrete mixes were tested: normal strength and high strength concrete specimens. Fibers in the concrete mix found to significantly increase the ductility and the impact resistance of the composite. Deformed fibers increase peak pull-out load and pull-out distance, and perform better in the steel fiber reinforced concrete (SFRC) structures. (author)

  15. Flow Characteristics of a Thermoset Fiber Composite Photopolymer Resin in a Vat Polymerization Additive Manufacturing Process

    DEFF Research Database (Denmark)

    Hofstätter, Thomas; Spangenberg, Jon; Pedersen, David B.

    Additive manufacturing vat polymerization has become a leading technology and gained a massive amount of attention in industrial applications such as injection molding inserts. By the use of the thermoset polymerization process inserts have increased their market share. For most industrial...... understood. Research indicates an orientation within the manufacturing layer and efforts have been made to achieve a more uniform orientation within the part. A vat polymerization machine consisting of a resin vat and a moving build plate has been simulated using the fluid flow module of Comsol Multiphysics...... photopolymer resin. The prediction can be used to identify potential clusters or misalignment of fibers and in the future allow for optimization of the machine design and manufacturing process....

  16. Characteristics of hot-pressed fiber-reinforced ceramics with SiC matrix

    Science.gov (United States)

    Miyoshi, Tadahiko; Kodama, Hironori; Sakamoto, Hiroshi; Goto, Akihiro; Iijima, Shiroo

    1989-11-01

    Silicon carbide ceramics’ matrix composites with SiC or C filaments were fabricated through hot pressing, and the effects of the filament pullout on their fracture toughness were experimentally investigated. The C-rich coating layers on the SiC filaments were found to have a significant effect on the frictional stress at the filament/matrix interfaces, through assising the filamet pullout from the matrix. Although the coating layers were apt to burn out in the sintering process of SiC matrix compposites, a small addition of carbon to the raw materials was found to be effective for the retention of the layers on the fibers, thus increasing the fracture toughness of the composites. The fracture toughness of the C filament/SiC matrix composite increased with temperature due to the larger interfacial frictional stress at higher temperatures, because of the higher thermal expansion of the filament in the radial direction than that of the matrix.

  17. An investigation of the compressive strength of Kevlar 49/epoxy composites

    Science.gov (United States)

    Kulkarni, S. V.; Rosen, B. W.; Rice, J. S.

    1975-01-01

    Tests were performed to evaluate the effect of a wide range of variables including matrix properties, interface properties, fiber prestressing, secondary reinforcement, and others on the ultimate compressive strength of Kevlar 49/epoxy composites. Scanning electron microscopy is used to assess the resulting failure surfaces. In addition, a theoretical study is conducted to determine the influence of fiber anisotropy and lack of perfect bond between fiber and matrix on the shear mode microbuckling. The experimental evaluation of the effect of various constituent and process characteristics on the behavior of these unidirectional composites in compression did not reveal any substantial increase in strength. However, theoretical evaluations indicate that the high degree of fiber anisotropy results in a significant drop in the predicted stress level for internal instability. Scanning electron microscope data analysis suggests that internal fiber failure and smooth surface debonding could be responsible for the measured low compressive strengths.

  18. Experimental Investigation on Bonding Characteristics of Low-Strength Mortars Used to Repoint the Joints of the Damaged Historical Masonry Structures

    OpenAIRE

    Covatariu, Daniel; Toma, Ionuţ-Ovidiu; Budescu, Mihai

    2011-01-01

    Masonry represents the oldest building material in the history. The rehabilitation of a damaged building involves knowledge about the building material’s properties, the execution technology, the elaboration of the rehabilitation project and, also, theoretical knowledge about the strength calculus of the rehabilitated structure. All these are required in order to assess the bearing capacity. With the view to determine the strength and deformability characteristics of the old masonry (made fro...

  19. Low strength ultrasonication positively affects the methanogenic granules toward higher AD performance. Part I: Physico-chemical characteristics

    DEFF Research Database (Denmark)

    Cho, S. K.; Hwang, Yuhoon; Kim, D. H.

    2013-01-01

    To elucidate the correlation between enhanced biogas production and changed physico-chemical properties of methanogenic granules after low strength ultrasonication, in this study, the effects of low strength ultrasonication on the settling velocity, permeability, porosity, and fluid collection ef...

  20. Photonic crystal fibers -

    DEFF Research Database (Denmark)

    Libori, Stig E. Barkou

    2002-01-01

    . Such micro-structured fibers are the ones most often trated in literature concerning micro-structured fibers. These micro-structured fibers offer a whole range of novel wave guiding characteristics, including the possibility of fibers that guide only one mode irrespective of the frequency of light...

  1. Shear Behavior Models of Steel Fiber Reinforced Concrete Beams Modifying Softened Truss Model Approaches.

    Science.gov (United States)

    Hwang, Jin-Ha; Lee, Deuck Hang; Ju, Hyunjin; Kim, Kang Su; Seo, Soo-Yeon; Kang, Joo-Won

    2013-10-23

    Recognizing that steel fibers can supplement the brittle tensile characteristics of concrete, many studies have been conducted on the shear performance of steel fiber reinforced concrete (SFRC) members. However, previous studies were mostly focused on the shear strength and proposed empirical shear strength equations based on their experimental results. Thus, this study attempts to estimate the strains and stresses in steel fibers by considering the detailed characteristics of steel fibers in SFRC members, from which more accurate estimation on the shear behavior and strength of SFRC members is possible, and the failure mode of steel fibers can be also identified. Four shear behavior models for SFRC members have been proposed, which have been modified from the softened truss models for reinforced concrete members, and they can estimate the contribution of steel fibers to the total shear strength of the SFRC member. The performances of all the models proposed in this study were also evaluated by a large number of test results. The contribution of steel fibers to the shear strength varied from 5% to 50% according to their amount, and the most optimized volume fraction of steel fibers was estimated as 1%-1.5%, in terms of shear performance.

  2. Shear Behavior Models of Steel Fiber Reinforced Concrete Beams Modifying Softened Truss Model Approaches

    Directory of Open Access Journals (Sweden)

    Joo-Won Kang

    2013-10-01

    Full Text Available Recognizing that steel fibers can supplement the brittle tensile characteristics of concrete, many studies have been conducted on the shear performance of steel fiber reinforced concrete (SFRC members. However, previous studies were mostly focused on the shear strength and proposed empirical shear strength equations based on their experimental results. Thus, this study attempts to estimate the strains and stresses in steel fibers by considering the detailed characteristics of steel fibers in SFRC members, from which more accurate estimation on the shear behavior and strength of SFRC members is possible, and the failure mode of steel fibers can be also identified. Four shear behavior models for SFRC members have been proposed, which have been modified from the softened truss models for reinforced concrete members, and they can estimate the contribution of steel fibers to the total shear strength of the SFRC member. The performances of all the models proposed in this study were also evaluated by a large number of test results. The contribution of steel fibers to the shear strength varied from 5% to 50% according to their amount, and the most optimized volume fraction of steel fibers was estimated as 1%–1.5%, in terms of shear performance.

  3. Effects of variation in porcine MYOD1 gene on muscle fiber characteristics, lean meat production, and meat quality traits.

    Science.gov (United States)

    Lee, E A; Kim, J M; Lim, K S; Ryu, Y C; Jeon, W M; Hong, K C

    2012-09-01

    Three single nucleotide polymorphisms (SNPs) in the porcine MYOD1 gene were used for association analysis and haplotype construction to evaluate the effects of their substitution. Four hundred and three pigs of Yorkshire and Berkshire breeds were used. The mRNA expression levels of MYOD1 were examined. The g.489C>T and g.1264C>A SNPs were significantly associated with several muscle fiber characteristics, the loin eye area, and lightness. Particularly, animals having hetero-genotypes of both sites showed good performance both in lean meat production and meat quality traits. The results of haplotype substitution were similar to the associations of individual SNPs. Moreover, the 2 SNPs had significant effects on mRNA expression. Therefore, the g.489C>T and g.1264C>A SNPs in MYOD1 may be meaningful DNA markers that can be used for improving important porcine economic traits. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. The Importance of Muscular Strength: Training Considerations.

    Science.gov (United States)

    Suchomel, Timothy J; Nimphius, Sophia; Bellon, Christopher R; Stone, Michael H

    2018-04-01

    This review covers underlying physiological characteristics and training considerations that may affect muscular strength including improving maximal force expression and time-limited force expression. Strength is underpinned by a combination of morphological and neural factors including muscle cross-sectional area and architecture, musculotendinous stiffness, motor unit recruitment, rate coding, motor unit synchronization, and neuromuscular inhibition. Although single- and multi-targeted block periodization models may produce the greatest strength-power benefits, concepts within each model must be considered within the limitations of the sport, athletes, and schedules. Bilateral training, eccentric training and accentuated eccentric loading, and variable resistance training may produce the greatest comprehensive strength adaptations. Bodyweight exercise, isolation exercises, plyometric exercise, unilateral exercise, and kettlebell training may be limited in their potential to improve maximal strength but are still relevant to strength development by challenging time-limited force expression and differentially challenging motor demands. Training to failure may not be necessary to improve maximum muscular strength and is likely not necessary for maximum gains in strength. Indeed, programming that combines heavy and light loads may improve strength and underpin other strength-power characteristics. Multiple sets appear to produce superior training benefits compared to single sets; however, an athlete's training status and the dose-response relationship must be considered. While 2- to 5-min interset rest intervals may produce the greatest strength-power benefits, rest interval length may vary based an athlete's training age, fiber type, and genetics. Weaker athletes should focus on developing strength before emphasizing power-type training. Stronger athletes may begin to emphasize power-type training while maintaining/improving their strength. Future research should

  5. Correlações entre a maturidade da fibra e outros caracteres econômicos do algodoeiro Simple correlations between fiber maturity and economic characteristics in cotton

    Directory of Open Access Journals (Sweden)

    Nélson Paulieri Sabino

    1976-07-01

    Full Text Available As características da fibra - comprimento, uniformidade, índice Micronaire (finura, resistência Pressley -, a resistência do fio, assim como a porcentagem de fibra, peso de um capulho, peso de 100 sementes e a produção, foram correlacionados com a maturidade da fibra, determinada pelo fibrógrafo digital. Para tanto foram utilizados os dados de 12 ensaios regionais de variedades instalados no ano agrícola de 1970/71, e de 13 ensaios instalados em 1971/72, em diferentes locais do Estado de São Paulo. Esses ensaios, em quadrado latino 6x6, forneceram 72 pares de valores no primeiro ano e 78 pares no segundo, para os cálculos dos coeficientes de correlação. Estes foram computados por ano e por variedade. Valores médios foram estimados através da transformação Z de Fisher. Houve variações sensíveis no valor dos coeficientes entre anos dentro de variedades e entre variedades dentro de ano. As estimativas médias foram significativas, com exceção da resistência da fibra, da resistência do fio e da porcentagem de fibra. Houve falta de homogeneidade nos casos do índice Micronaire e da uniformidade de comprimento. No ano de 1971/72, de condições piores para o algodoeiro, os coeficientes de correlação alcançaram valores mais altos.Simple correlations between maturity indices determined by the digital fibrograph and the characteristics of fiber length, uniformity, Micronaire, Pressley (1/8 gauge, yarn strength, mean boll weight, mean weight of 100 seeds, percentage of fiber, and yield were studied. Data of 12 experiments of regional variety tests planted in 1970/71 and of 13 experiments planted in 1971/72 in different regions of the State of São Paulo were used. These experiments delined in 6x6 latin squares yielded 72 pairs of data in the first year and 78 in the second year. Correlation coefficients were computed by variety within years and mean estimates obtained through Fisher's Z transformation. Large variations of the

  6. QUANTITATIVE AND QUALITATIVE DIFFERENCES OF MORPHOLOGICAL CHARACTERISTICS AND EXPLOSIVE STRENGTH OF LEGS IN UNDER-16 FEMALE AND MALE VOLLEYBALL PLAYERS

    Directory of Open Access Journals (Sweden)

    Slobodan Andrašić

    2015-05-01

    Full Text Available In order to achieve an advantage over the opponent, all the game elements, for which it is possible, are tended to be performed by jumping (Ziv & Lidor, 2010. This is supported by the fact that research of vertical jumping ability of volleyball players of different levels, found that players at a higher level of competition also achieve better results on tests of the assessment of vertical jumping ability (Forthomme, Croisier, Ciccarone, Crielaard, & Cloes, 2005. The research subject was aimed at detecting the difference between male and female volleyball players in morphological characteristics and explosive strength of legs, as well as determining the size of the impact of morphological characteristics of the explosive power of the lower limbs between groups formed on the basis of gender dimorphism. Method: The sample in this study was derived from a population of volleyball players of OK “RFU” from Futog, N=27 and female volleyball players of ŽOK “Futog” from Futog, N=38. For the purposes of this research morphological characteristics were measured. By using MANOVA and ANOVA differences were determined between the two sub-samples of respondents formed on the basis of gender dimorphism regarding the analyzed morphological and motor variables. In order to determine effects of the system of predictor variables on the criteria variables we used Linear Regression Analysis. Results: Statistically significant differences were observed for the variables Body height, Legs length and Lower-leg circumference, as well as for all three motor variables: Spike jump, Standing triple jump and Standing vertical jump in favor of volleyball players. Linear Regression Analysis revealed the impact of the predictor system of morphological characteristics on the criterion Spike jump in both subsamples. It was found that Body height gives the highest contribution to achieving better results regarding the height reached during spike jump in both groups

  7. Understanding the relationship between cotton fiber properties and non-cellulosic cell wall polysaccharides

    DEFF Research Database (Denmark)

    Rajasundaram, Dhivyaa; Runavot, Jean-Luc; Guo, Xiaoyuan

    2014-01-01

    cotton fibers, which are of both biological and industrial importance. To this end, we attempted to study cotton fiber characteristics together with glycan arrays using regression based approaches. Taking advantage of the comprehensive microarray polymer profiling technique (CoMPP), 32 cotton lines from...... different cotton species were studied. The glycan array was generated by sequential extraction of cell wall polysaccharides from mature cotton fibers and screening samples against eleven extensively characterized cell wall probes. Also, phenotypic characteristics of cotton fibers such as length, strength...

  8. To evaluate and compare the effect of different Post Surface treatments on the Tensile Bond Strength between Fiber Posts and Composite Resin.

    OpenAIRE

    Shori, Deepa; Pandey, Swapnil; Kubde, Rajesh; Rathod, Yogesh; Atara, Rahul; Rathi, Shravan

    2013-01-01

    Background: Fiber posts are widely used for restoration of mutilated teeth that lack adequate coronal tooth structure to retain a core for definitive restoration, bond between the fiber post and composite material depends upon the chemical reaction between the post surface and the resin material used for building up the core. In attempt to maximize the resin bonding with fiber post, different post surface conditioning is advocated. Therefore the purpose of the study is to examine the interfac...

  9. Compression Behavior of High Performance Polymeric Fibers

    National Research Council Canada - National Science Library

    Kumar, Satish

    2003-01-01

    Hydrogen bonding has proven to be effective in improving the compressive strength of rigid-rod polymeric fibers without resulting in a decrease in tensile strength while covalent crosslinking results in brittle fibers...

  10. Physicomechanical properties of porous fiber materials and prediction of them

    International Nuclear Information System (INIS)

    Kostornov, A.G.; Galstyan, L.G.

    1985-01-01

    A comparison is presented of the experimentally determined values of certain properties of porous fiber materials obtained by the optimum method from monodisperse fibers of copper, nickel, and Nichrome of different diameters with the corresponding theoretical values. The electrical conductivity, tensile strength, and modulus of elasticity, the basic properties of a porous body, which are determined both by the structural characteristics of the elements and by the condition of the interparticle contacts, were considered

  11. Peripapillary retinal nerve fiber layer and optic nerve head characteristics in eyes with situs inversus of the optic disc.

    Science.gov (United States)

    Kang, Sunah; Jin, Sunyoung; Roh, Kyu Hwa; Hwang, Young Hoon

    2015-01-01

    This study was performed to investigate the peripapillary retinal nerve fiber layer (RNFL) and optic nerve head (ONH) characteristics, as determined using a spectral-domain optical coherence tomography (OCT), in eyes with situs inversus of the optic disc. The peripapillary RNFL and the ONH were assessed in 12 eyes belonging to 6 subjects with situs inversus of the optic disc (situs inversus group) and 24 eyes in 12 age-matched, sex-matched, and refractive error-matched healthy subjects (control group) by using OCT. The average, quadrant, and clock-hour RNFL thicknesses (clock-hour 9 on the scan represented the temporal side of the optic disc in both eyes), the superior/inferior RNFL peak locations, and ONH characteristics such as disc area, rim area, cup-to-disc ratio, vertical cup-to-disc ratio, and cup volume were obtained. The differences in RNFL and ONH characteristics between the 2 groups were analyzed. The situs inversus group had a thicker RNFL in the clock-hour sectors 3 and 4, a thinner RNFL in the clock-hour sectors 7, 8, and 11, and more nasally located superior and inferior RNFL peak locations than the control group (P≤0.001). The situs inversus group had a smaller cup-to-disc area ratio, smaller vertical cup-to-disc ratio, and a lesser cup volume than the control group (Poptic disc showed different peripapillary RNFL and ONH characteristics from those without this abnormality. These findings should be considered when assessing eyes with situs inversus of the optic disc.

  12. Methods for evaluating tensile and compressive properties of plastic laminates reinforced with unwoven glass fibers

    Science.gov (United States)

    Karl Romstad

    1964-01-01

    Methods of obtaining strength and elastic properties of plastic laminates reinforced with unwoven glass fibers were evaluated using the criteria of the strength values obtained and the failure characteristics observed. Variables investigated were specimen configuration and the manner of supporting and loading the specimens. Results of this investigation indicate that...

  13. Dynamic mechanical analysis and high strain-rate energy absorption characteristics of vertically aligned carbon nanotube reinforced woven fiber-glass composites

    Science.gov (United States)

    The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and...

  14. Surface and Bulk Characteristics of Cesium Iodide (CsI) coated Carbon (C) Fibers for High Power Microwave (HPM) Field Emission Cathodes

    Science.gov (United States)

    Vlahos, Vasilios; Morgan, Dane; Booske, John H.; Shiffler, Don

    2008-11-01

    CsI coated C fibers [1] are promising field emission cathodes for HPM applications. Ab initio computational modeling has shown that atomically-thin CsI coatings reduce the work function of C substrates by a surface dipole mechanism [2]. Characterization measurements of the composition and morphology of the CsI-coated C fibers are underway for determining the properties and characteristics of the following important regions of the fiber: (i) the surface on the tip of the fiber where the majority of electron emission is believed to occur, (ii) the surface covering the body of the fiber and its role on the emission properties of the system, and (iii) the interior volume of the fiber and its effects on the CsI surface re-supply process and rate. The results will be interpreted in terms of surface electronic properties and theoretical electron emission models. [1]D. Shiffler, et al., Phys. Plasmas 11 (2004) 1680. [2]V.Vlahos et al., Appl. Phys. Lett. 91 (2007) 144102.

  15. Thermal conductivity and retention characteristics of composites made of boron carbide and carbon fibers with extremely high thermal conductivity for first wall armour

    Science.gov (United States)

    Jimbou, R.; Kodama, K.; Saidoh, M.; Suzuki, Y.; Nakagawa, M.; Morita, K.; Tsuchiya, B.

    1997-02-01

    The thermal conductivity of the composite hot-pressed at 2100°C including B 4C and carbon fibers with a thermal conductivity of 1100 W/ m· K was nearly the same as that of the composite including carbon fibers with a thermal conductivity of 600 W/ m· K. This resulted from the higher amount of B diffused into the carbon fibers through the larger interface. The B 4C content in the composite can be reduced from 35 to 20 vol% which resulted from the more uniform distribution of B 4C by stacking the flat cloth woven of carbon fibers (carbon fiber plain fabrics) than in the composite with 35 vol% B 4C including curled carbon fiber plain fabrics. The decrease in the B 4C content does not result in the degradation of D (deuterium)-retention characteristics or D-recycling property, but will bring about the decreased amount of the surface layer to be melted under the bombardment of high energy hydrogen ions such as disruptions because of higher thermal conduction of the composite.

  16. Effect of gamma rays on yield , fiber and seed characteristics of flax

    International Nuclear Information System (INIS)

    Amer, I.M.A.

    1980-01-01

    The present investigation deals with effect of radiation on flex in two main experiments . In the first one which could be considered as a pilot experiment, the seeds of giza-4 (the dominating local variety of flax) were irradiated with gamma ray doses ranging from 2.5 to 200 Kr to find out the suitable doses for a long - term program of mutation breeding in flax. The finding of such preliminary program could be summarized in the following: a) A dose of 100 kr affected the germination rate and inhibited the growth of flax plants. b) A dose of 200 kr was shown to be a lethal one under the conditions of this experiment. c) Some deviations in plant and yield characteristics than the normal type ( i . e., plant and yield characteristics of Gaza 4) were observed at relatively low doses. These deviations were tested in the M2 generation . True mutations (i.e., deviations that proved to breed true) were selected and their seeds (M2- derived lines were tested in M3 generation). Data about these M2 -derived lines when tested in the M3 generation will be summarized with the data of the main experiment

  17. Influence of loading and unloading velocity of confining pressure on strength and permeability characteristics of crystalline sandstone

    Science.gov (United States)

    Zhang, Dong-ming; Yang, Yu-shun; Chu, Ya-pei; Zhang, Xiang; Xue, Yan-guang

    2018-06-01

    The triaxial compression test of crystalline sandstone under different loading and unloading velocity of confining pressure is carried out by using the self-made "THM coupled with servo-controlled seepage apparatus for containing-gas coal", analyzed the strength, deformation and permeability characteristics of the sample, the results show that: with the increase of confining pressures loading-unloading velocity, Mohr's stress circle center of the specimen shift to the right, and the ultimate intensity, peak strain and residual stress of the specimens increase gradually. With the decrease of unloading velocity of confining pressure, the axial strain, the radial strain and the volumetric strain of the sample decrease first and then increases, but the radial strain decreases more greatly. The loading and unloading of confining pressure has greater influence on axial strain of specimens. The deformation modulus decreases rapidly with the increase of axial strain and the Poisson's ratio decreases gradually at the initial stage of loading. When the confining pressure is loaded, the deformation modulus decrease gradually, and the Poisson's ratio increases gradually. When the confining pressure is unloaded, the deformation modulus increase gradually, and the Poisson's ratio decreases gradually. When the specimen reaches the ultimate intensity, the deformation modulus decreases rapidly, while the Poisson's ratio increases rapidly. The fitting curve of the confining pressure and the deformation modulus and the Poisson's ratio in accordance with the distribution of quadratic polynomial function in the loading-unloading confining pressure. There is a corresponding relationship between the evolution of rock permeability and damage deformation during the process of loading and unloading. In the late stage of yielding, the permeability increases slowly, and the permeability increases sharply after the rock sample is destroyed. Fitting the permeability and confining pressure

  18. Isometric and isokinetic muscle strength in patients with fibrositis syndrome. New characteristics for a difficult definable category of patients

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Danneskiold-Samsøe, B

    1987-01-01

    A common complaint among patients with fibrositis syndrome is exhaustion and fatique. It was therefore felt desirable to evaluate the muscle strength of these patients compared with normal subjects. Maximum isometric and isokinetic strength of knee extension was measured in 15 patients and 15...... healthy matched subjects, using an isokinetic dynamometer (Cybex II). Maximum isometric strength at various knee extension angles (90 degrees, 60 degrees and 30 degrees degrees) was significantly (p less than 0.001) lower in the fibrositis group than in controls, a reduction of approximately 58......-66%. Maximum isokinetic strength at various knee extension velocities (30-240 degrees per second) was also significantly (p less than 0.01) lower in the fibrositis group than in controls, the reduction being approximately 41-51%. In conclusion, isometric and isokinetic muscle strength is found to be lower...

  19. Effect of the molecular structure of phenolic novolac precursor resins on the properties of phenolic fibers

    International Nuclear Information System (INIS)

    Ying, Yong-Gang; Pan, Yan-Ping; Ren, Rui; Dang, Jiang-Min; Liu, Chun-Ling

    2013-01-01

    A series of phenolic resins with different weight-average molecular weights (M w ) and ortho/para (O/P) ratios were prepared. The effect of the phenolic precursor resin structure on the structure and properties of the resulting phenolic fibers was investigated. The structures of the resins and fibers were characterized by nuclear magnetic resonance spectroscopy, gel permeation chromatography, melt rheometry, dynamic mechanical analysis, and thermogravimetric analysis. The results show that the O/P ratio, unsubstituted ortho and para carbon ratio (O u /P u ), and M w of the phenolic resins play an important role in determining the properties of the phenolic fibers. The tensile strength of the phenolic fibers increases with increasing novolac precursor O u /P u ratios, corresponding to low O/P ratios, at comparable resin M w values. Also, the tensile strength of the phenolic fibers increases with increasing novolac M w values at comparable O/P ratios. Phenolic fibers with high tensile strength and good flame resistance characteristics were generated from a phenolic precursor resin, possessing a high weight-average molecular weight and a low O/P value. - Highlights: • Phenolic resins with different weight-average molecular weights and ortho/para ratios have been prepared. • The tensile strength of the phenolic fibers increases with reducing novolac O/P ratio. • The tensile strength of the phenolic fibers increases with increasing novolac M w

  20. Study on basalt fiber parameters affecting fiber-reinforced mortar

    Science.gov (United States)

    Orlov, A. A.; Chernykh, T. N.; Sashina, A. V.; Bogusevich, D. V.

    2015-01-01

    This article considers the effect of different dosages and diameters of basalt fibers on tensile strength increase during bending of fiberboard-reinforced mortar samples. The optimal dosages of fiber, providing maximum strength in bending are revealed. The durability of basalt fiber in an environment of cement, by means of microscopic analysis of samples of fibers and fiberboard-reinforced mortar long-term tests is examined. The article also compares the behavior of basalt fiber in the cement stone environment to a glass one and reveals that the basalt fiber is not subject to destruction.

  1. Natural Fiber Filament Wound Composites: A Review

    Directory of Open Access Journals (Sweden)

    Mohamed Ansari Suriyati

    2017-01-01

    Full Text Available In recent development, natural fibers have attracted the interest of engineers, researchers, professionals and scientists all over the world as an alternative reinforcement for fiber reinforced polymer composites. This is due to its superior properties such as high specific strength, low weight, low cost, fairly good mechanical properties, non-abrasive, eco-friendly and bio-degradable characteristics. In this point of view, natural fiber-polymer composites (NFPCs are becoming increasingly utilized in a wide variety of applications because they represent an ecological and inexpensive alternative to conventional petroleum-derived materials. On the other hand, considerable amounts of organic waste and residue from the industrial and agricultural processes are still underutilized as low-value energy sources. This is a comprehensive review discussing about natural fiber reinforced composite produced by filament winding technique.

  2. Alkali-resistant glass fiber reinforced high strength concrete in simulated aggressive environment; Hormigón de altas resistencia reforzado con fibras de vidrio resistentes a alcalis en ambientes agresivos simulados.

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, W.H.; Cheah, C.B.; Ramli, M.; Chang, K.Y.

    2018-04-01

    The durability of the alkali-resistant (AR) glass fiber reinforced concrete (GFRC) in three simulated aggresive environments, namely tropical climate, cyclic air and seawater and seawater immersion was investigated. Durability examinations include chloride diffusion, gas permeability, X-ray diffraction (XRD) and scanning electron microscopy examination (SEM). The fiber content is in the range of 0.6 % to 2.4 %. Results reveal that the specimen containing highest AR glass fiber content suffered severe strength loss in seawater environment and relatively milder strength loss under cyclic conditions. The permeability property was found to be more inferior with the increase in the fiber content of the concrete. This suggests that the AR glass fiber is not suitable for use as the fiber reinforcement in concrete is exposed to seawater. However, in both the tropical climate and cyclic wetting and drying, the incorporation of AR glass fiber prevents a drastic increase in permeability. [Spanish] Este trabajo se centra en el estudio de la durabilidad de hormigón reforzado con fibra de vidrio resistente a álcalis (CRFVRA) en tres ambientes agresivos simulados como son, condiciones de clima tropical, ciclos de aire y agua de mar e inmersión marina. Los tests de durabilidad incluyeron la difusión de cloruros, permeabilidad de gas, difracción de rayos X (XRD) y evaluacion por microscopía electrónica de barrido (SEM). Los contenidos de fibra evaluados estuvieron en el rango desde 0.6% hasta 2.4%. Los resultados revelan que la muestra que contiene el mayor porcentaje de fibra sufre una severa pérdida de resistencia en condiciones de agua de mar, y una menor disminución de resistencia bajo condiciones cíclicas. Su permeabilidad disminuyó al incrementar el contenido de fibras en el hormigón. Lo anterior sugiere que el refuerzo con fibra resistente a alcalinos no es adecuado para su uso en hormigón en ambiente de agua de mar. Sin embargo, bajo condiciones de clima

  3. Developmental and hormonal regulation of fiber quality in two natural-colored cotton cultivars

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiang; HU Da-peng; LI Yuan; CHEN Yuan; Eltayib H.M.A.Abidallha; DONG Zhao-di; CHEN De-hua; ZHANG Lei

    2017-01-01

    Cotton cultivars with brown (Xiangcaimian 2),green (Wanmian 39) and white (Sumian 9) fiber were investigated to study fiber developmental characteristics of natural-colored cotton and the effect of hormones on fiber quality at different stages after anthesis.Fiber lengths of both natural-colored cottons were lower than the white-fibered control,with brown-flbered cotton longer than green.Fiber strength,micronaire and maturation of natural-colored cotton were also lower than the control.The shorter fiber of the green cultivar was due to slower growth during 10 to 30 days post-anthesis (DPA).Likewise,the lower fiber strength,micronaire and maturation of natured-colored cotton were also due to slower growth during this pivotal stage.Indole-3-acetic acid (IAA) content at 10 DPA,and abscisic acid (ABA) content at 30 to 40 DPA were lower in the fibers of the natural-colored than that of the white-flbered cotton.After applying 20 mg L-1 gibberellic acid (GA3),the IAA content at 20 DPA in the brown and green-fibered cottons increased by 51.07 and 64.33%,fiber ABA content increased by 38.96 and 24.40%,and fiber length increased by 8.13 and 13.96%,respectively.Fiber strength,micronaire and maturation were also enhanced at boll opening stage.Those results suggest that the level of endogenous hormones affect fiber quality.Application of external hormones can increase hormone content in natural-colored cotton fiber,improving its quality.

  4. Effect of Reduced Phosphoric Acid Pre-etching Times 
on Enamel Surface Characteristics and Shear Fatigue Strength Using Universal Adhesives.

    Science.gov (United States)

    Tsujimoto, Akimasa; Fischer, Nicholas; Barkmeier, Wayne; Baruth, Andrew; Takamizawa, Toshiki; Latta, Mark; Miyazaki, Masashi

    2017-01-01

    To examine the effect of reduced phosphoric acid pre-etching times on enamel fatigue bond strength of universal adhesives and surface characteristics by using atomic force microscopy (AFM). Three universal adhesives were used in this study (Clearfil Universal Bond [C], G-Premio Bond [GP], Scotchbond Universal Adhesive [SU]). Four pre-etching groups were employed: enamel pre-etched with phosphoric acid and immediately rinsed with an air-water spray, and enamel pre-etched with phosphoric acid for 5, 10, or 15 s. Ground enamel was used as the control group. For the initial bond strength test, 15 specimens per etching group for each adhesive were used. For the shear fatigue test, 20 specimens per etching group for each adhesive were loaded using a sine wave at a frequency of 20 Hz for 50,000 cycles or until failure occurred. Initial shear bond strengths and fatigue shear strengths of composite adhesively bonded to ground and pre-etched enamel were determined. AFM observations of ground and pre-etched enamel were also conducted, and surface roughness as well as surface area were evaluated. The initial shear bond strengths and fatigue shear strengths of the universal adhesives in the pre-etched groups were significantly higher than those of the control group, and were not influenced by the pre-etching time. Significantly higher surface roughness and surface area of enamel surfaces in pre-etched groups were observed compared with those in the control group. While the surface area was not significantly influenced by etching time, surface roughness of the enamel surfaces in the pre-etched groups significantly increased with pre-etching time. The results of this in vitro study suggest that reduced phosphoric acid pre-etching times do not impair the fatigue bond strength of universal adhesives. Although fatigue bond strength and surface area were not influenced by phosphoric-acid etching times, surface roughness increased with increasing etching time.

  5. Optical coherence tomography detection of characteristic retinal nerve fiber layer thinning in nasal hypoplasia of the optic disc.

    Science.gov (United States)

    Haruta, M; Kodama, R; Yamakawa, R

    2017-12-01

    PurposeTo determine the clinical usefulness of optical coherence tomography (OCT) for detecting thinning of the retinal nerve fiber layer (RNFL) in eyes with nasal hypoplasia of the optic discs (NHOD).Patients and methodsThe medical records of five patients (eight eyes) with NHOD were reviewed. The ratio of the disc-macula distance to the disc diameter (DM/DD) and the disc ovality ratio of the minimal to maximal DD were assessed using fundus photographs. The RNFL thicknesses of the temporal, superior, nasal, and inferior quadrants were evaluated using OCT quadrant maps.ResultsAll eight eyes had temporal visual field defects that respected the vertical meridians that needed to be differentiated from those related to chiasmal compression. The mean DM/DD ratio was 3.1 and the mean disc ovality ratio was 0.81. The mean RNFL thicknesses of the temporal, superior, nasal, and inferior quadrants were 90.3, 103.1, 34.8, and 112.8 microns, respectively.ConclusionSmall optic discs and tilted discs might be associated with NHOD. Measurement of the RNFL thickness around the optic disc using OCT scans clearly visualized the characteristic RNFL thinning of the nasal quadrants corresponding to the temporal sector visual field defects in eyes with NHOD. OCT confirmed the presence of NHOD and might differentiate eyes with NHOD from those with chiasmal compression.

  6. Effect of Nutrient Supply on Chemical and Energetic Characteristics of Fiber Sorghum Biomass

    International Nuclear Information System (INIS)

    Ciria, P.; Gonzalez, E.; Negro, M. J.; Solano, M. L.

    1998-01-01

    The main objective of the present work, is to study the effect of the addition of different nutrients and irrigation doses on the chemical and energetic characteristics of the Sorghum bicolor (L.) Moench ssp. bicolor biomass. The effect of compost addition is compared with the mineral fertilisation in two different irrigation doses . The experimental parcel, is located at CIEMAT-CEDER (Soria), at 1000 m above sea level, with a extremely weather and a loam sandy soil texture. The results obtained in the tested conditions show: a) the average biomass productivity was 9.81 d.m./ha, and no significant differences between treatments were observed. b) Mean values of the proximate analysis were 72.6 volatile matter, 6.2% ashes and 21.2 % fixed carbon. The volatile matter increases (1.1 %) and the ashes decreases (1.4 %) for the highest irrigation dose both in plots with no addition and in plots amended with compost. c) The N, S and Cl contents decreases for the highest irrigation dose in the same cases above mentioned. Mean values of the elemental analysis were: 45.0 % C, 6.3 % H, 1.4 % N, 0.15 % S and 0.49 % Cl. d) The average High Heating Value was 18071 kJ/kg d.m. and no significant differences between treatments were observed e) For the highest irrigation doses, a reduction in the K 2 O, P 2 O 5 , Mg and Si content, and a increase in the Al, Fe and Ti in ashes were detected. (Author) 13 refs

  7. Evaluation of the performance characteristics of bilayer tablets: Part II. Impact of environmental conditions on the strength of bilayer tablets.

    Science.gov (United States)

    Kottala, Niranjan; Abebe, Admassu; Sprockel, Omar; Bergum, James; Nikfar, Faranak; Cuitiño, Alberto M

    2012-12-01

    Ambient air humidity and temperature are known to influence the mechanical strength of tablets. The objective of this work is to understand the influence of processing parameters and environmental conditions (humidity and temperature) on the strength of bilayer tablets. As part of this study, bilayer tablets were compressed with different layer ratios, dwell times, layer sequences, material properties (plastic and brittle), first and second layer forces, and lubricant concentrations. Compressed tablets were stored in stability chambers controlled at predetermined conditions (40C/45%RH, 40C/75%RH) for 1, 3, and 5 days. The axial strength of the stored tablets was measured and a statistical model was developed to determine the effects of the aforementioned factors on the strength of bilayer tablets. As part of this endeavor, a full 3 × 2(4) factorial design was executed. Responses of the experiments were analyzed using PROC GLM of SAS (SAS Institute Inc, Cary, North Carolina, USA). A model was fit using all the responses to determine the significant interactions (p < 0.05). Results of this study indicated that storage conditions and storage time have significant impact on the strength of bilayer tablets. For Avicel-lactose and lactose-Avicel tablets, tablet strength decreased with the increasing humidity and storage time. But for lactose-lactose tablets, due to the formation of solid bridges upon storage, an increase in tablet strength was observed. Significant interactions were observed between processing parameters and storage conditions on the strength of bilayer tablets.

  8. Fiber Patterns in Young Adults Living in Different Environments (USA, Spain, and Tunisia. Anthropometric and Lifestyle Characteristics

    Directory of Open Access Journals (Sweden)

    María José García-Meseguer

    2017-09-01

    Full Text Available Benefits of dietary fiber go beyond its effect on chronic diseases associated with development. Consequently, the pattern of fiber intake has been considered an indicator for diet quality. Young adults are especially vulnerable to a food environment that drives an increase in chronic diseases linked to economic development. The aim of this work was to characterize patterns of fiber intake among university students. A cross-sectional study was conducted on a sample of 730 students enrolled at the University of Castilla-La Mancha (Spain, the University of Carthage (Tunisia, and Florida International University (USA. Mean age was 21.2. Food consumption was self-reported in two 24-h recalls. Mean dietary fiber intake was 17.8 g, not reaching the adequate intake. Contrary to expectations, American participants were the highest consumers (p < 0.001, and also exhibited the highest BMI. Cereals, legumes, vegetables and fruit were the main food sources of fiber. Fiber from appetizers, prepared and precooked meals, sauces, spices and condiments accounted for 16.7% in American participants, 7.4% in Spanish participants and 2.6% in Tunisian participants. Total fiber intake increased with energy intake but did not depend on smoking habits and physical activity in any country. It is essential to improve consumers’ interpretation of guidelines on fiber intake.

  9. Preparation by low-temperature nonthermal plasma of graphite fiber and its characteristics for solid-phase microextraction

    International Nuclear Information System (INIS)

    Luo Fan; Wu Zucheng; Tao Ping; Cong Yanqing

    2009-01-01

    Low-temperature nonthermal plasma has been used to prepare solid-phase microextraction (SPME) fibers with high adsorbability, long-term serviceability, and high reproducibility. Graphite rods serving as fiber precursors were treated by an air plasma discharged at 15.2-15.5 kV for a duration of 8 min. Sampling results revealed that the adsorptive capacity of the homemade fiber was 2.5-34.6 times that of a polyacrylate (PA) fiber for alcohols (methanol, ethanol, isopropyl alcohol, n-butyl alcohol), and about 1.4-1.6 times and 2.5-5.1 times that of an activated carbon fiber (ACF) for alcohols and BTEX (benzene, toluene, ethylbenzene, and xylenes), respectively. It is confirmed from FTIR (Fourier transform infrared spectrophotometer) and SEM (scanning electron microscope) analyses that the improvement in the adsorptive performance attributed to increased surface energy and roughness of the graphite fiber. Using gas chromatography (GC)-flame-ionization detector (FID), the limits of detection (LODs) of the alcohols and BTEX ranged between 0.19 and 3.75 μg L -1 , the linear ranges were between 0.6 and 35619 μg L -1 with good linearity (R 2 = 0.9964-0.9997). It was demonstrated that nonthermal plasma offers a fast and simple method for preparing an efficient graphite SPME fiber, and that SPME using the homemade fiber represents a sensitive and selective extraction method for the analysis of a wide range of organic compounds

  10. Preparation by low-temperature nonthermal plasma of graphite fiber and its characteristics for solid-phase microextraction.

    Science.gov (United States)

    Luo, Fan; Wu, Zucheng; Tao, Ping; Cong, Yanqing

    2009-01-05

    Low-temperature nonthermal plasma has been used to prepare solid-phase microextraction (SPME) fibers with high adsorbability, long-term serviceability, and high reproducibility. Graphite rods serving as fiber precursors were treated by an air plasma discharged at 15.2-15.5 kV for a duration of 8 min. Sampling results revealed that the adsorptive capacity of the homemade fiber was 2.5-34.6 times that of a polyacrylate (PA) fiber for alcohols (methanol, ethanol, isopropyl alcohol, n-butyl alcohol), and about 1.4-1.6 times and 2.5-5.1 times that of an activated carbon fiber (ACF) for alcohols and BTEX (benzene, toluene, ethylbenzene, and xylenes), respectively. It is confirmed from FTIR (Fourier transform infrared spectrophotometer) and SEM (scanning electron microscope) analyses that the improvement in the adsorptive performance attributed to increased surface energy and roughness of the graphite fiber. Using gas chromatography (GC)-flame-ionization detector (FID), the limits of detection (LODs) of the alcohols and BTEX ranged between 0.19 and 3.75 microg L(-1), the linear ranges were between 0.6 and 35,619 microg L(-1) with good linearity (R(2)=0.9964-0.9997). It was demonstrated that nonthermal plasma offers a fast and simple method for preparing an efficient graphite SPME fiber, and that SPME using the homemade fiber represents a sensitive and selective extraction method for the analysis of a wide range of organic compounds.

  11. Nanostructured Basaltfiberconcrete Exploitational Characteristics

    Science.gov (United States)

    Saraykina, K. A.; Shamanov, V. A.

    2017-11-01

    The article demonstrates that the mass use of basalt fiber concrete (BFC) is constrained by insufficient study of their durability and serviceability in a variety of environments. This research is aimed at the study of the basalt fiber corrosion processes in the cement stone of BFC, the control of the new products structure formation in order to protect the reinforcing fiber from alkaline destruction and thereby improve the exploitational characteristics of the composite. The research result revealed that the modification of basaltfiber concrete by the dispersion of MWNTs contributes to the directional formation of new products in the cement matrix. The HAM additive in basaltfiberconcrete provides for the binding of portlandite to low-basic calcium hydroaluminosilicates, thus reducing the aggressive effect of the cement environment on the reinforcing fibers properties. The complex modification of BFC with nanostructured additives provides for an increase in its durability and exploitational properties (strength, frost resistance and water resistance) due to basalt fiber protection from alkali corrosion on account of the compacting of the contact zone “basalt fiber - cement stone” and designing of the new products structure and morphology of cement matrix over the fiber surface.

  12. Peripheral origins and functional characteristics of vibration-sensitive VIIIth nerve fibers in the frog Rana temporaria

    DEFF Research Database (Denmark)

    Jøgensen, Morten Buhl; Christensen-Dalsgaard, Jakob

    1991-01-01

    were studied. 2) Vibration-sensitive fibers were found in both the anterior and posterior branch of the VIIIth nerve. 3) No vibration-sensitive fibers were found in the lagenar nerve. 4) The vibration-sensitive fibers in the posterior branch probably innervated the amphibian papilla and many...... of these fibers also responded to low-frequency sound. 5) The vibration-sensitive fibers in the anterior branch probably innervated the sacculus and the utriculus. 6) Hence, the grassfrog has at least two, and probably three, vibration-sensitive organs in the inner ear. 7) All fibers had V-shaped vibrational...... tuning curves. In the posterior branch best frequencies (BFs) ranged from 10 to 300 Hz, in the anterior branch from 10 to 100 Hz. In the posterior branch spike-rate thresholds at BF ranged from 0.04 to 1.28 cm/s2, in the anterior branch from 0.02 to 1.28 cm/s2. All fibers showed strong synchronization...

  13. Effects of withdrawing high-fiber ingredients before marketing on finishing pig growth performance, carcass characteristics, and intestinal weights.

    Science.gov (United States)

    Coble, Kyle F; DeRouchey, Joel M; Tokach, Mike D; Dritz, Steve S; Goodband, Robert D; Woodworth, Jason C

    2018-02-15

    Two experiments were conducted to determine the duration of high-fiber ingredient removal from finishing pig diets before marketing to restore carcass yield and carcass fat iodine value (IV), similar to pigs continuously fed a corn-soybean meal diet. In experiment 1, 288 pigs (initially 38.4 ± 0.3 kg body weight [BW]) were used in an 88-d study and fed either a low-fiber corn-soybean meal diet from day 0 to 88 or a high-fiber diet containing 30% corn distillers dried grains with solubles and 19% wheat middlings until day 20, 15, 10, 5, or 0 before slaughter and switched to the low-fiber corn-soybean meal diet thereafter. Diets were not balanced for net energy. From day 0 to 88, pigs continuously fed the high-fiber diet tended to have increased average daily feed intake (P = 0.072) and decreased G:F and carcass yield (P = 0.001) compared with pigs fed the low-fiber corn-soybean meal diet. Pigs continuously fed the high-fiber diet had greater (P market increased carcass yield (experiment 1) or HCW (experiment 2) with the improvement most prominent during the first 5 to 9 d after withdrawal.

  14. Robust Fiber Coatings

    National Research Council Canada - National Science Library

    Goettler, Richard

    2002-01-01

    The highly desired ceramic matrix composite is the one in which the high strength and strain-to-failure is achieved through judicious selection of a fiber coating that can survive the high-temperature...

  15. Hysteretic evaluation of seismic performance of normal and fiber reinforced concrete shear walls

    International Nuclear Information System (INIS)

    Choun, Young Sun; Hahm, Dae Gi

    2012-01-01

    The use of fibers in concrete or cement composites can enhance the performance of structural elements. Fibers have been used for a cement mixture to increase the toughness and tensile strength, and to improve the cracking and