WorldWideScience

Sample records for aramids

  1. Statistical Constitutive Equation of Aramid Fiber Bundles

    Institute of Scientific and Technical Information of China (English)

    熊杰; 顾伯洪; 王善元

    2003-01-01

    Tensile impact tests of aramid (Twaron) fiber bundles were carried om under high strain rates with a wide range of 0. 01/s~1000/s by using MTS and bar-bar tensile impact apparatus. Based on the statistical constitutive model of fiber bundles, statistical constitutive equations of aramid fiber bundles are derived from statistical analysis of test data at different strain rates. Comparison between the theoretical predictions and experimental data indicates statistical constitutive equations fit well with the experimental data, and statistical constitutive equations of fiber bundles at different strain rates are valid.

  2. The preparation of aramid fibres in silicone based composite materials

    OpenAIRE

    L.A. Dobrzański; A. J. Nowak; A. Pusz; M. Górniak

    2011-01-01

    Purpose: The evaluation of modified aramid fibres – Kevlar – as reinforcement in silicon materials used in medicine.Design/methodology/approach: Samples of laminated material based on modified aramid fibres and medical silicone were made by a method of manual formation of laminates that is impregnation of reinforcement with matrix to hardening silicone process using hardening methods connected with heat. Created material was observed on Scanning Electron Microscopy manufactured by Zeiss.Findi...

  3. Nano-Aramid Fiber Reinforced Polyurethane Foam

    Science.gov (United States)

    Semmes, Edmund B.; Frances, Arnold

    2008-01-01

    Closed cell polyurethane and, particularly, polyisocyanurate foams are a large family of flexible and rigid products the result of a reactive two part process wherein a urethane based polyol is combined with a foaming or "blowing" agent to create a cellular solid at room temperature. The ratio of reactive components, the constituency of the base materials, temperature, humidity, molding, pouring, spraying and many other processing techniques vary greatly. However, there is no known process for incorporating reinforcing fibers small enough to be integrally dispersed within the cell walls resulting in superior final products. The key differentiating aspect from the current state of art resides in the many processing technologies to be fully developed from the novel concept of milled nano pulp aramid fibers and their enabling entanglement capability fully enclosed within the cell walls of these closed cell urethane foams. The authors present the results of research and development of reinforced foam processing, equipment development, strength characteristics and the evolution of its many applications.

  4. Surface modification and characterization of aramid fibers with hybrid coating

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jianrui; Zhu, Yaofeng; Ni, Qingqing; Fu, Yaqin, E-mail: fyq01@zstu.edu.cn; Fu, Xiang

    2014-12-01

    Graphical abstract: - Highlights: • Aramid fibers modification sizing synthesized by sol–gel in the absence of water. • The strength and interfacial adhesion property of modified fibers were improved. • Modified fibers show a special surface structure. • The mechanism explains the function of structure. - Abstract: Aramid fibers were modified through solution dip-coating and interfacial in situ polymerization using a newly synthesized SiO{sub 2}/shape memory polyurethane (SiO{sub 2}/SMPU) hybrid. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that the synthesized SiO{sub 2}/SMPU hybrid successfully coated the fiber surface. The surface morphology of the aramid fibers and the single fiber tensile strength and interfacial shear strength (IFSS) of the composites were determined. The IFSS of the fiber coated with the hybrid improved by 45%, which benefited from a special “pizza-like” structure on the fiber surface.

  5. Effects of Environment on Strengths of UHMWPE and Aramid Fiber

    Institute of Scientific and Technical Information of China (English)

    曹涛; 李显波

    2013-01-01

    This paper is devoted on influences of acid-base,high and low temperature on strength of UHMWPE and aramid fiber, characterized by fracture strength, SEM’s effects on fiber strength and surface morphology. It turns out to be that UHMWPE fiber has a superior acid-base, low temperature and light aging resistance property,with strength keeping above 90% in acid-base environment. Comparing with UHMWPE fiber, aramid fiber does well in mechanical properties, temperature resistant performances and alkali resistances at room temperature, with strength losing less than 10%in alkaline environment.

  6. Carbon molecular sieves for air separation from Nomex aramid fibers.

    Science.gov (United States)

    Villar-Rodil, Silvia; Martínez-Alonso, Amelia; Tascón, Juan M D

    2002-10-15

    Activated carbon fibers prepared from aramid fibers have proved to possess outstanding homogeneity in pore size, most of all when Nomex aramid fiber is used as precursor. Taking advantage of this feature, microporous carbon molecular sieves for air separation have been prepared through carbon vapor deposition of benzene on Nomex-derived carbon fibers activated to two different burnoff degrees. Carbon molecular sieves with good selectivity for this separation and showing acceptable adsorption capacities were obtained from ACFs activated to the two burnoff degrees chosen. PMID:12702417

  7. Extrusion instability in an aramid fibre spinning process

    NARCIS (Netherlands)

    Drost, S.

    2015-01-01

    The efficiency of polymer extrusion processes can be severely limited by the occurrence of viscoelastic extrusion instabilities. In a para-aramid fibre spinning process, for example, a μm-scale extrusion instability is responsible for the waste of tons of polymer per year. At present, a considerab

  8. Strain-induced internal fibrillation in looped aramid filaments

    DEFF Research Database (Denmark)

    Pauw, Brian Richard; Vigild, Martin Etchells; Mortensen, Kell;

    2010-01-01

    By mapping the small-angle X-ray scattering (SAXS) from a looped poly-(para-phenylene terephtalamide) (aramid, PPTA) filament using a synchrotron X-ray microbeam, we investigate the effects of axially compressive and tensile strain on internal fibrillar structures. Unique observations of oscillat...

  9. Tissue biocompatibility of kevlar aramid fibers and polymethylmethacrylate, composites in rabbits.

    Science.gov (United States)

    Henderson, J D; Mullarky, R H; Ryan, D E

    1987-01-01

    Two groups of female NZW rabbits were implanted in the paravertebral muscles with aramid (du Pont Kevlar aramid 49) fibers and aramid-polymethylmethacrylate (PMMA) composites for 14 and 28 days. Rabbits were killed at these times periods, necropsies performed, sites scored for gross tissue response, and tissue specimens containing the implants removed for histopathological evaluation. A mild fibrous tissue reaction was observed around all implants containing aramid fiber similar to that observed around the silicone control implant. Some foreign body giant cells were also present adjacent to the fibers. An intense necrotic inflammatory reaction was present around the positive control material (PVC Y-78). The tissue response to implantation of aramid fiber and fiber-PMMA composites indicates that aramid is a biocompatible material.

  10. Heterocyclic aramid nanoparticle-assisted graphene exfoliation for fabrication of pristine graphene-based composite paper

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Yao; Liu, Qi; Fan, Jinchen, E-mail: Jinchen.fan@shiep.edu.cn; Shi, Penghui; Min, Yulin, E-mail: ahaqmylin@126.com; Xu, Qunjie [Shanghai University of Electric Power, Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, College of Environmental and Chemical Engineering (China)

    2015-07-15

    Mechanically strong, electrically conductive, and flexible pristine graphene-based composite paper was prepared based on heterocyclic aramid nanoparticle-assisted liquid-phase exfoliation of graphite. The macroscopic heterocyclic aramid yarns were split and assembled into heterocyclic aramid nanoparticles with the size of ∼30 nm by deprotonation in dimethylsulfoxide in the presence of potassium hydroxide. The obtained heterocyclic aramid nanoparticles dimethylsulfoxide dispersion was used as good medium solvent for highly efficiency liquid-phase exfoliation of graphite. The results demonstrated that the concentration of exfoliated graphene can facile reaches ∼2.72 mg/mL after direct sonication of 7 h with assist of heterocyclic aramid nanoparticles. After exfoliation, the self-assembled pristine graphene-based composite paper was fabricated by vacuum-assisted filtration. Due to the introduction of heterocyclic aramid nanoparticles, the self-assembled pristine graphene/heterocyclic aramid nanoparticles composite paper exhibited good mechanical property with tensile strength of ∼129.7 MPa, meantime, has a high electrical conductivity of ∼1.42 × 10{sup 4} S/m.

  11. Heterocyclic aramid nanoparticle-assisted graphene exfoliation for fabrication of pristine graphene-based composite paper

    International Nuclear Information System (INIS)

    Mechanically strong, electrically conductive, and flexible pristine graphene-based composite paper was prepared based on heterocyclic aramid nanoparticle-assisted liquid-phase exfoliation of graphite. The macroscopic heterocyclic aramid yarns were split and assembled into heterocyclic aramid nanoparticles with the size of ∼30 nm by deprotonation in dimethylsulfoxide in the presence of potassium hydroxide. The obtained heterocyclic aramid nanoparticles dimethylsulfoxide dispersion was used as good medium solvent for highly efficiency liquid-phase exfoliation of graphite. The results demonstrated that the concentration of exfoliated graphene can facile reaches ∼2.72 mg/mL after direct sonication of 7 h with assist of heterocyclic aramid nanoparticles. After exfoliation, the self-assembled pristine graphene-based composite paper was fabricated by vacuum-assisted filtration. Due to the introduction of heterocyclic aramid nanoparticles, the self-assembled pristine graphene/heterocyclic aramid nanoparticles composite paper exhibited good mechanical property with tensile strength of ∼129.7 MPa, meantime, has a high electrical conductivity of ∼1.42 × 104 S/m.

  12. Statistical Tensile Strength for High Strain Rate of Aramid and UHMWPE Fibers

    Institute of Scientific and Technical Information of China (English)

    YANG Bin; XIONG Tao; XIONG Jie

    2006-01-01

    Dynamic tensile impact properties of aramid (Technora(R)) and UHMWPE (DC851) fiber bundles were studied at two high strain rates by means of reflecting type Split Hopkinson Bar, and stress-strain curves of fiber yarns at different strain rates were obtained. Experimental results show that the initial elastic modulus, failure strength and unstable strain of aramid fiber yarns are strain rate insensitive, whereas the initial elastic modulus and unstable strain of UHMWPE fiber yarns are strain rate sensitive. A fiber-bundle statistical constitutive equation was used to describe the tensile behavior of aramid and UHMWPE fiber bundles at high strain rates. The good consistency between the simulated results and experimental data indicates that the modified double Weibull function can represent the tensile strength distribution of aramid and UHMWPE fibers and the method of extracting Weibull parameters from fiber bundles stress-strain data is valid.

  13. Prediction of Final Velocity of Aramid Fabric-Resin Composite Laminates Subjected to Ballistic Impact

    Institute of Scientific and Technical Information of China (English)

    熊杰; 萧庆亮; 刘冠峰; 顾伯洪; 王善元

    2003-01-01

    The strain rate effects of aramid fiber material,quasi-static and ballistic impact perforation of composite laminates made of aramid fabric and phenolic resin/PVB are investigated respectively by means of MTS, split Hopkinson tension bars and ballistic impact apparatus. The tensile impact experiments on aramid fiber material are performed in strain rate range from 0.01/ s to 1 000/ s. Experinental results show that the mechanical properties of aramid fiber material are insensitive to strain rate in the range from 0. 01/s to 1 000/s. An energy model to predict final velocity of composite laminates subjected to ballistic impact is proposed on the basis of experimental data of quasi-static perforation through the targets. The predicted final velocities show good agreement with the experimental final velocity.

  14. Comparison of properties of segmented copolyetheresteramides containing uniform aramid segments with commercial segmented copolymers

    NARCIS (Netherlands)

    Niesten, M.C.E.J.; Gaymans, R.J.

    2001-01-01

    The thermal (using differential scanning calorimetry), dynamic mechanical (using a dynamic mechanical analyzer), and mechanical properties of segmented copolyetheresteramides with aramid units of uniform length (TT) and poly(tetramethylene oxide) (PTMO) segments were compared to those of commercial

  15. Tensile and Flexural Properties of Aramide/Glass/Onion Fibre Reinforced Epoxy Composites

    OpenAIRE

    G.Meenambika Bai,

    2014-01-01

    Fiber-reinforced Epoxy Composites have played a dominant role for a long time in a variety of applications for their high strength, light weight, cost effectiveness and degradability. The fiber which serves as a reinforcement in reinforced plastics may be synthetic or natural. In this connection, an investigation has been carried out to make use of Aramide/Glass/Onion fibers. The present work describes the development and characterization of mechanical properties of Aramide/Gl...

  16. The elimination of micropores and surface defects in aramid-silicon laminated materials with special properties

    OpenAIRE

    L.A. Dobrzański; A. Pusz; A. J. Nowak

    2009-01-01

    Purpose: Development of the manufacturing technology of aramid-silicon laminated material and define of the micro-cavities amount during production of the laminates and identification of their influence on product properties with assumed medical implantation.Design/methodology/approach: Aramid-silicon laminated material was made by method of manual formation of laminates, that is impregnation of reinforcement with matrix, to hardening silicone process using hardening methods connected with ho...

  17. Aramid-silicon laminated materials with special properties – new perspective of its usage

    OpenAIRE

    L.A. Dobrzański; A. Pusz; A. J. Nowak

    2008-01-01

    Purpose: Development of the manufacturing technology of aramid-silicon laminated material.Design/methodology/approach: Aramid-silicon laminated material was made by method of manual formation of laminates, that is impregnation of reinforcement with matrix, to hardening silicone process using hardening methods connect with hot. Created material was being observed by using MEF4A light-microscope of Leica company at 25-500x magnification.Findings: The results show that the preliminary manufactur...

  18. Aramid-silicon laminated materials with special properties – new perspective of its usage

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2008-05-01

    Full Text Available Purpose: Development of the manufacturing technology of aramid-silicon laminated material.Design/methodology/approach: Aramid-silicon laminated material was made by method of manual formation of laminates, that is impregnation of reinforcement with matrix, to hardening silicone process using hardening methods connect with hot. Created material was being observed by using MEF4A light-microscope of Leica company at 25-500x magnification.Findings: The results show that the preliminary manufacturing technology of aramid-silicon laminated materials allows to create a material with specific and special properties. Aramid silicone laminate could be attractive alternative for composite material used in medical and others purposes.Research limitations/implications: Carried out investigations show the problem with cautioning and ageing which are very important in having proper percentage of intensifier in developed material.Originality/value: Taking into account the material specific properties one can suppose that the aramid-silicon laminated material would be useful in medicine. Aramid silicone laminate could be attractive alternative for composite material used in medical and others purposes.

  19. Molecular Dynamics Modeling of PPTA Crystals in Aramid Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Mercer, Brian Scott [Univ. of California, Berkeley, CA (United States)

    2016-05-19

    In this work, molecular dynamics modeling is used to study the mechanical properties of PPTA crystallites, which are the fundamental microstructural building blocks of polymer aramid bers such as Kevlar. Particular focus is given to constant strain rate axial loading simulations of PPTA crystallites, which is motivated by the rate-dependent mechanical properties observed in some experiments with aramid bers. In order to accommodate the covalent bond rupture that occurs in loading a crystallite to failure, the reactive bond order force eld ReaxFF is employed to conduct the simulations. Two major topics are addressed: The rst is the general behavior of PPTA crystallites under strain rate loading. Constant strain rate loading simulations of crystalline PPTA reveal that the crystal failure strain increases with increasing strain rate, while the modulus is not a ected by the strain rate. Increasing temperature lowers both the modulus and the failure strain. The simulations also identify the C N bond connecting the aromatic rings as weakest primary bond along the backbone of the PPTA chain. The e ect of chain-end defects on PPTA micromechanics is explored, and it is found that the presence of a chain-end defect transfers load to the adjacent chains in the hydrogen-bonded sheet in which the defect resides, but does not in uence the behavior of any other chains in the crystal. Chain-end defects are found to lower the strength of the crystal when clustered together, inducing bond failure via stress concentrations arising from the load transfer to bonds in adjacent chains near the defect site. The second topic addressed is the nature of primary and secondary bond failure in crystalline PPTA. Failure of both types of bonds is found to be stochastic in nature and driven by thermal uctuations of the bonds within the crystal. A model is proposed which uses reliability theory to model bonds under constant strain rate loading as components with time-dependent failure rate

  20. Damage detection of hybrid aramid/metal–PVB composite materials using optical fiber sensors

    Directory of Open Access Journals (Sweden)

    A. Kojović

    2009-09-01

    Full Text Available Embedding optical fiber sensors within laminar thermoplastic composite material results in forming a system known as «smart structure». These sensors present the information about the inner structure health during the material exploitation and especially in the case of exterior impacts when a geometric configuration or the property changes of the material should be expected. This paper evaluates the feasibility of the real-time monitoring of indentation and low energy impact damage in composite laminates from indentation loading and Charpy pendulum impact, using the embedded intensity-based optical fiber sensors. An optical fiber sensing system, which relies solely on monitoring light intensity for providing the indication of the composite structural health, offers simplicity in design and cost-effectiveness. For this, aramid/polyvinylbutyral (PVB and aramid/metal/PVB laminates with embedded optical fibers were fabricated. Four configurations of woven composites were tested, namely, aramid/PVB, and aramid/metal/PVB in three stacking sequences of aramid and metallic woven layers. The initiation of damage and fracture during testing was detected by observation of the intensity drop of light signal transmitted through an optical fiber.

  1. Behavior of RC panels retrofitted with aramid fiber sheets to missile impact

    International Nuclear Information System (INIS)

    An experimental study of behavior of RC panels retrofitted with aramid fiber sheets and rubber sheets subjected to missile impact is reported. The objective is to consider the effect of aramid fiber sheets and rubber sheets on perforation and scabbing of RC panels subjected to high-velocity impact of projectile. Six RC panel specimens of 750 mm square were prepared. Rubber sheet and aramid fiber sheet were used as surface reinforcement on front side of RC panel and on rear side, respectively. Parameters being studied are thickness of rubber sheets and velocity of projectile. The panel specimen was suspended vertically by two steel wire ropes to allow free movement after projectile impact, and was subjected to a projectile. In this study, non-deformable type of projectile with a hemispherical head was used. Tests results show that reinforcement by the aramid fiber sheet and rubber sheet reduces local damage of RC panels effectively, and that the aramid fiber sheet also has an effect on preventing scattering the concrete. (authors)

  2. Surface modification of aramid fiber by plasma induced vapor phase graft polymerization of acrylic acid. I. Influence of plasma conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.X., E-mail: cxwang@mail.dhu.edu.cn [College of Textiles and Clothing, Yancheng Institute of Technology, Jiangsu 224003 (China); School of Textile and Clothing, Nantong University, Jiangsu 226019 (China); Du, M. [College of Textiles and Clothing, Yancheng Institute of Industry Technology, Jiangsu 224000 (China); Lv, J.C.; Zhou, Q.Q. [College of Textiles and Clothing, Yancheng Institute of Technology, Jiangsu 224003 (China); Ren, Y. [School of Textile and Clothing, Nantong University, Jiangsu 226019 (China); Liu, G.L.; Gao, D.W. [College of Textiles and Clothing, Yancheng Institute of Technology, Jiangsu 224003 (China); Jin, L.M. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China)

    2015-09-15

    Highlights: • Aramid fiber surface was modified by PIVPGP of AA to improve wettability, adhesion. • Surface modification effect by PIVPGP of AA increased and then decreased with time. • Surface modification effect increased and then stayed unaltered with output power. • Ar plasma was the most effective in PIVPGP of AA on aramid fiber surface. • In studied range, optimum technology of PIVPGP of AA: Ar plasma, 15 min, 300 W. - Abstract: Plasma induced vapor phase graft polymerization (PIVPGP) method was applied to modify aramid fiber surface. In this study, aramid fibers were pretreated under various plasma conditions such as different treatment times, output powers and working gases to see how these plasma processing parameters influenced the PIVPGP of acrylic acid (AA) on aramid fiber surface and its surface structure and properties. The analysis results of atomic force microscope (AFM) and X-ray photoelectron spectroscope (XPS) showed the increase of surface roughness and the introduction of O=C−OH, which confirmed that the PIVPGP of AA on aramid fiber surface was achieved. The contact angle and interfacial shear strength (IFSS) of the aramid fibers modified by PIVPGP of AA prominently decreased and increased, respectively, indicating the obvious improvements of surface wettability and adhesion between aramid fiber and matrix. The surface modification effects of aramid fiber by PIVPGP of AA firstly increased and then after 15 min slightly decreased with the increasing plasma treatment time, and but firstly increased and then after 300 W nearly remained unchanged with the increasing output power, respectively. Among different working gases, Ar plasma occupied first place, O{sub 2} plasma and N{sub 2} plasma came second and third in the aspect of PIVPGP of AA on aramid fiber surface, respectively. It could be concluded that the PIVPGP of AA on aramid fiber surface could effectively improve surface wettability and adhesion. Plasma conditions had signally

  3. Short aramid-fiber reinforced ultra-high molecular weight polyethylene

    NARCIS (Netherlands)

    Hofste, JM; Bergmans, KJR; deBoer, J; Wevers, R; Pennings, AJ

    1996-01-01

    Ultra-High Molecular Weight Polyethylene (UHMWPE) is frequently used in artificial joints because of its high wear resistance. To extend the lifetime of these joints even further, it is necessary to decrease the wear rate. The wear rate may be decreased by blending UHMWPE with short aramid fibers. O

  4. Liquid Crystal Sulfonated Aramids as Proton Exchange Membranes for Fuel Cell Applications

    NARCIS (Netherlands)

    Gao, J.

    2015-01-01

    Two sulfonated aramids, poly(2,2’-disulfonylbenzidine terephthalamide) (PBDT) and poly(2,2’-disulfonylbenzidine isophthalamide) (PBDI) were synthesized with the aim to explore their unique morphology for proton exchange membrane applications. Due to the different polymer structures, PBDT forms a nem

  5. Study of Aramid Fiber/Polychloroprene Recycling Process by Thermal Degradation

    Directory of Open Access Journals (Sweden)

    Igor Dabkiewicz

    2016-07-01

    Full Text Available Aramid fiber is an important polymer applied as reinforcement in high-performance composites, which, due its exceptional properties, becomes an excellent impact absorption material. It has been broadly utilized in aeronautic industry and ballistic protection. In aircrafts, it is mainly used in secondary structures, such as fairings, floor panels, and bullet proof structures in helicopters, whereas, in ballistic protection industry, it is applied in automotive armor and bullet proof vest. Under environmental perspective, it is worrying the development and application of composites, which generate proportional discards of these materials, whether originated from manufacturing process, spare parts or end of life cycle. High-performance composite materials like those using aramid fiber are generally difficult to recycle due to their properties and the difficulty for the separation of the components, making their recycling economically unviable. From the characteristics of composite materials and environmental viewpoint, this paper presents a new aramid fiber recycling process. The main objective of this research was to study different recycling methods in aramid fibers/Neoprene® composites. To promote the Neoprene® degradation, it was used a pyrolysis oven with controlled atmosphere and CO 2 injection. For the degraded separation, it was designed a mechanical washing machine in which the most degraded separation occurred. To complete the materials separation, it was employed a manual cleaning process, and, at least to prove the efficacy of the process, it was applied a tensile test in the yarns.

  6. Deposition of carbon nanotubes onto aramid fibers using as-received and chemically modified fibers

    Science.gov (United States)

    Rodríguez-Uicab, O.; Avilés, F.; Gonzalez-Chi, P. I.; Canché-Escamilla, G.; Duarte-Aranda, S.; Yazdani-Pedram, M.; Toro, P.; Gamboa, F.; Mazo, M. A.; Nistal, A.; Rubio, J.

    2016-11-01

    Multiwall carbon nanotubes (MWCNTs) oxidized by an acid treatment were deposited on the surface of as-received commercial aramid fibers containing a surface coating ("sizing"), and fibers modified by either a chlorosulfonic treatment or a mixture of nitric and sulfuric acids. The surface of the aramid fiber activated by the chemical treatments presents increasing density of CO, COOH and OH functional groups. However, these chemical treatments reduced the tensile mechanical properties of the fibers, especially when the nitric and sulfuric acid mixture was used. Characterization of the MWCNTs deposited on the fiber surface was conducted by scanning electron microscopy, Raman spectroscopy mapping and X-ray photoelectron spectroscopy. These characterizations showed higher areal concentration and more homogeneous distribution of MWCNTs over the aramid fibers for as-received fibers and for those modified with chlorosulfonic acid, suggesting the existence of interaction between the oxidized MWCNTs and the fiber coating. The electrical resistance of the MWCNT-modified aramid yarns comprising ∼1000 individual fibers was in the order of MΩ/cm, which renders multifunctional properties.

  7. Forbidden reflections from the aramid PPTA—A novel correlation with stacking faults

    Indian Academy of Sciences (India)

    Anjana Jain; Kalyani Vijayan

    2004-02-01

    The occurrence of space group forbidden reflections in the X-ray diffraction patterns from the aramid PPTA has been correlated with the presence of stacking faults. The fraction of sample affected by the presence of such faults has also been estimated.

  8. Validation of the numerical model of single-layer composites reinforced with carbon fiber and aramid

    Science.gov (United States)

    Sava, Mihaela; Hadǎr, Anton; Pǎrǎuşanu, Ioan; Petrescu, Horia-Alexandru; Baciu, Florin; Marinel, Stǎnescu Marius

    2016-06-01

    In this work we studied the experimental validation of the model and finite element analysis for a single layer of composite materials reinforced with carbon (denoted as C), aramid (K) and carbon-aramid (C-K) fibers. In the literature there are not many details about the differences that arise between transversal and longitudinal characteristics of composite materials reinforced with fabric, compared to those with unidirectional fibers. In order to achieve carbon and aramid composites we used twill fabric and for carbon-aramid plain fabric, as shown in Figure 1. In order to observe the static behavior of the considered specimens, numerical simulations were carried out in addition to the experimental determination of the characteristics of these materials. Layered composites are obviously the most widespread formula for getting advanced composite structures. It allows a unique variety of material and structural combinations leading to optimal design in a wide range of applications [1,2]. To design and verify the material composites it is necessary to know the basic mechanical constants of the materials. Almost all the layered composites consider that the every layer is an orthotropic material, so there are nine independent constants of material corresponding to the three principal directions: Young modulus E1, E2 and E3, shear modulus G12, G23 and G13, and major poison ratios ν12, ν23, ν13. Experimental determinations were performed using traction tests and strain gauges. For each of the three above mentioned materials, five samples were manufactured.

  9. Hybrid repowering of transformers using aramids; Repotenciacao hibrida de transformadores com utilizacao de aramida

    Energy Technology Data Exchange (ETDEWEB)

    Neri Junior, Almir Laranjeira; Correia, Fidelis Botelho [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil)

    2010-01-15

    Santiago substation of the PETROBRAS, operated with two transformers fabricated in 1971. To preserve the reliability of power supply, it was relaborated a reformation and repowering project of the equipment using aramids, a special polymeric material. This paper describes the phases of the project, and presents the benefits obtained, and also the characteristics of the electric system of the production unit. (author)

  10. Shape-Memory Properties of Segmented Polymers Containing Aramid Hard Segments and Polycaprolactone Soft Segments

    OpenAIRE

    Arno Kraft; Louis Garnier; Lechmann, Maria C.; Christian Schuh; Kerstin Schuh

    2010-01-01

    A series of segmented multiblock copolymers containing aramid hard segments and extended polycaprolactone soft segments (with an Mn of 4,200 or 8,200 g mol–1) was prepared and tested for their shape-memory properties. Chain extenders were essential to raise the hard segment concentration so that an extended rubbery plateau could be observed. Dynamic mechanical thermal analysis provided a useful guide in identifying (i) the presence of a rubbery plateau, (ii) the flow temperature, and (iii) th...

  11. Experimental study on the thermostable property of aramid fiber reinforced PE-RT pipes

    OpenAIRE

    Guoquan Qi; Yin Wu; Dongtao Qi; Bin Wei; Houbu Li; Nan Ding; Xuehua Cai

    2015-01-01

    Flexible composite pipes are advantageous in ultra high strength, high modulus, pH and corrosion resistance and light weight, but there are still some hidden safety troubles because they are poorer in thermostable capacity. Therefore, test samples of flexible composite pipes were prepared with high-temperature polythene (PE-RT) as the neck bush and aramid fiber as the reinforcement layer. Experimental study was conducted by using HPHT vessel and differential thermal scanner for different work...

  12. Exploring a novel multifunctional agent to improve the dispersion of short aramid fiber in polymer matrix

    Directory of Open Access Journals (Sweden)

    K. Naskar

    2012-04-01

    Full Text Available Composites based on resorcinol formaldehyde latex (RFL coated aramid short fiber and a polyolefin based thermoplastic elastomer, namely ethylene octene copolymer (EOC were prepared by melt mixing technique. The effects of both fiber loading and its length on the mechanical and thermal characteristics of the composite under natural and sheared conditions were investigated. Both the low strain modulus and Young’s modulus were increased as a function of fiber loading and length. However, thermal stability of the composite was found to enhance with increase in fiber loading and was independent of fiber length. Due to poor interfacial interaction between the fiber and the matrix and the formation of fiber aggregation especially with 6 mm fiber at high loading, the elongation and toughness of the composite were found to decrease drastically. In order to solve this problem, a maleic anhydride adducted polybutadiene (MA-g-PB was applied on the aramid fiber. The improvements in tensile strength, elongation at break, toughness to stiffness balance and a good quality of fiber dispersion especially with 6 mm short fiber were achieved. These results indicate the potential use of maleic anhydride adducted PB as a multifunctional interface modifying coupling agent for the aramid short fiber reinforced polymers to enhance the mechanical properties as well as fiber dispersion. FTIR analyses of the treated fiber and SEM analyses of the tensile fractured surfaces of the composite strongly support and explain these results.

  13. Development and characterization of fatigue resistant Aramid reinforced aluminium laminates (ARALL) for fatigue Critical aircraft components

    International Nuclear Information System (INIS)

    The structural weight of an aircraft has always been a controlling parameter that governs its fuel efficiency and transport capacity. In pursuit of achieving light-weight aircraft structures, high design stress levels have to be adopted and materials with high specific strength such as Aluminum etc. are to be deployed. However, an extensive spectrum of fatigue load exists at the aircraft wings and other aerodynamic components that may cause initiation and propagation of fatigue cracks and concludes in a catastrophic rupture. Fatigue is therefore the limiting design parameter in such cases and materials with high fatigue resistance are then required. A major improvement in the fatigue behavior was observed by laminating Kevlar fibers with Aluminum using epoxy. ARALL (Aramid Reinforced ALuminum Laminates) is a fatigue resistant hybrid composite that consists of layers of thin high strength aluminum alloy sheets surface bonded with aramid fibers. The intact aramid fibers tie up the fatigue cracks, thus reducing the stress intensity factor at the crack tip as a result of which the fatigue properties of can be enhanced with orders of magnitude as compared to monolithic high strength Aluminum alloy sheets. Significant amount of weight savings can be achieved in fatigue critical components in comparison with the traditional materials used in aircraft

  14. Wear Behavior of Woven Roving Aramid / Epoxy Composite under Different Conditions

    Directory of Open Access Journals (Sweden)

    Asad A. Khalid

    2012-09-01

    Full Text Available Wear behavior studies of aramid woven roving /epoxy composite has been conducted. Sliding the material against smooth steel counter face under dry and  lubricated with oil conditions has been investigated. Powder of Silicon carbide has been mixed with the epoxy resin and tested also. The powder was mixed in a volumetric fraction of 10% with the epoxy resin. Four Laminates of six layers were fabricated by hand lay up  method. A pin on disc apparatus has been fabricated to conduct the sliding wear tests on specimens of (4 mm   4 mm   12 mm in size have been cut from the four laminates. The effect of sliding condition including dry, lubricated, dry with additives and lubricated with additives have been studied. Wear rate tests have been conducted at different sliding speeds and loads. Results show that the wear characteristics are influenced by the operating conditions and the construction of the composite material used. It was also found that the wear of aramid /epoxy composite onto the steel counter face were significantly reduced by using lubricant and additives but still took place.Keywords: Wear, Composite materials, Woven roving aramid, Epoxy, Additives, Lubricant.

  15. Development and characterization of fatigue resistant aramid reinforced aluminium laminates (ARALL) for fatigue critical aircraft components

    International Nuclear Information System (INIS)

    The structural weight of an aircraft has always been a controlling parameter that governs its fuel efficiency and transport capacity. In pursuit of achieving light-weight aircraft structures, high design stress levels have to be adopted and materials with high specific strength such as Aluminum etc. are to be deployed. However, an extensive spectrum of fatigue load exists at the aircraft wings and other aerodynamic components that may cause initiation and propagation of fatigue cracks and concludes in a catastrophic rupture. Fatigue is therefore the limiting design parameter in such cases and materials with high fatigue resistance are then required. A major improvement in the fatigue behavior was observed by laminating Kevlar fibers with Aluminum using epoxy. ARALL (Aramid Reinforced Aluminum Laminates) is a fatigue resistant hybrid composite that consists of layers of thin high strength aluminum alloy sheets surface bonded with aramid fibers. The intact aramid fibers tie up the fatigue cracks, thus reducing the stress intensity factor at the crack tip as a result of which the fatigue properties of can be enhanced with orders of magnitude as compared to monolithic high strength Aluminum alloy sheets. Significant amount of weight savings can be achieved in fatigue critical components in comparison with the traditional materials used in aircraft. (author)

  16. From Fragile to Resilient Insulation: Synthesis and Characterization of Aramid-Honeycomb Reinforced Silica Aerogel Composite Materials

    Directory of Open Access Journals (Sweden)

    Marina Schwan

    2015-12-01

    Full Text Available The production of a new composite material embedding aramid honeycomb materials into nano-porous silica aerogels is studied. Our aim is to improve the poor mechanical strength of silica aerogels by aramid honeycombs without losing the amazing properties of the aerogels like little density and low thermal conductivity. The composite materials were prepared using two formulations of silica aerogels in combination with aramid honeycomb materials of different cell sizes. The silica aerogels are prepared using silicon alkoxides methyltrimethoxysilane and tetraethylorthosilicate as precursors in a two-step acid–base sol–gel process. Shortly in advance of the gelation point, the aramid honeycombs were fluted by the sol, gelation occurred and, after the aging process, the gel bodies were supercritically dried. The properties of the received composite materials are satisfying. Even the thermal conductivities and the densities are a bit higher than for pure aerogels. Most importantly, the mechanical strength is improved by a factor of 2.3 compared to aramid honeycomb materials and by a factor of 10 compared to the two silica aerogels themselves. The composite materials have a good prospective to be used as an impressive insulation material.

  17. Experimental study on the thermostable property of aramid fiber reinforced PE-RT pipes

    Directory of Open Access Journals (Sweden)

    Guoquan Qi

    2015-11-01

    Full Text Available Flexible composite pipes are advantageous in ultra high strength, high modulus, pH and corrosion resistance and light weight, but there are still some hidden safety troubles because they are poorer in thermostable capacity. Therefore, test samples of flexible composite pipes were prepared with high-temperature polythene (PE-RT as the neck bush and aramid fiber as the reinforcement layer. Experimental study was conducted by using HPHT vessel and differential thermal scanner for different working conditions, different temperatures, whole-pipe pressure-bearing capacity and 1000 h viability. It is shown by the environmental compatibility test that high temperature has little effect on the weight, Vicat softening temperature, mechanical properties and structures of neck bush PE-RT, but exerts an obvious effect on the tensility and whole-pipe water pressure blasting of the reinforcement aramid fiber. Besides, the drop of whole-pipe pressure-bearing capacity is caused by deformation and breaking of aramid fibers when the reinforcement layer is under the force of internal pressure. Finally, disorientation and crystallization of molecular thermal motion occur with the rise of temperature, so amorphous orientation reduces, crystallinity factor and crystalline orientation factor increase gradually, thus, disorientation of macromolecular chains increases and tensile strength decreases. It is concluded that this type of flexible composite pipe can smoothly pass 1000 h viability test. And it is recommended that it be used in the situations with temperature not higher than 95 °C and internal pressure not higher than 4 MPa.

  18. Shape-Memory Properties of Segmented Polymers Containing Aramid Hard Segments and Polycaprolactone Soft Segments

    Directory of Open Access Journals (Sweden)

    Arno Kraft

    2010-06-01

    Full Text Available A series of segmented multiblock copolymers containing aramid hard segments and extended polycaprolactone soft segments (with an Mn of 4,200 or 8,200 g mol–1 was prepared and tested for their shape-memory properties. Chain extenders were essential to raise the hard segment concentration so that an extended rubbery plateau could be observed. Dynamic mechanical thermal analysis provided a useful guide in identifying (i the presence of a rubbery plateau, (ii the flow temperature, and (iii the temperature when samples started to deform irreversibly.

  19. The influence of magnetic field on ballistic performance of aramid fibre and ultrahigh molecular weight polyethylene

    International Nuclear Information System (INIS)

    Highlights: • Ballistic tests conducted on Kevlar and UHMWPE within a magnetic field. • Repulsion force created by opposing magnet poles reduced the impact momentum. • High speed camera images showed no perforation on Kevlar due to magnetic field. • Standoff distance between magnets has an effect on the repulsion force. - Abstract: An innovative method is introduced here whereby using two sets of arrays of rare earth magnets aligned opposite each other in order to create a repulsion force owing to the like poles when facing close to each other. Ballistic test samples of aramid fibre (Kevlar K29) and ultrahigh molecular weight polyethylene (UHMWPE) were sandwiched by two sets of opposing magnets. Ballistic test was conducted using a gas gun with a 7.62 mm diameter projectile at a velocity ranging from 160 to 220 m/s. High speed camera was used to capture the ballistics testing and it shows that the magnetic repulsion force created by the opposing rare earth magnets managed to suppress the projectile from advancing into the front face of the aramid fibre. Similarly, when magnets were used, the UHMWPE sample shows the projectile perforated through the first few sheets and finally rested on the last sheet showing partial perforation

  20. Pyrolysis Process in Aramid Fibers Investigated by Py-GC/MS & TGA-DTA/MS

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-wei; HU Zu-ming; LIU Zhao-feng

    2007-01-01

    Poly(m-phenylene isophthalamine) (PMIA) and Poly( p-phenylene terphthalamine) (PPTA) are among the most important high-temperature resistant aramid fibers. The pyrolysis behaviors of these two fibers under inert gases were studied using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis coupled with mass spectrometry ( TGA-DTA/MS ). The pyrolysis processes of PMIA and PPTA are distinguishing, and the stepwise pyrolysates reflect these differences. A mechanism system of pyrolysis is suggested, which involving hydrolysis and homolysis. At low pyrolysis temperatures, hydrolysis is a primary reaction, and it is very noticeable in the first-step pyrolysis region of PMIA. Elevating pyrolysis temperature, homolysis is enhanced and keep a large advantage in the high temperature range. On the other hand, at higher temperatures, carbonization appens and the homolysis and carbonization of PPTA are emphasized more than of PMIA.

  1. Edge Delamination and Residual Properties of Drilled Carbon Fiber Composites with and without Short-Aramid-Fiber Interleaf

    Science.gov (United States)

    Sun, Zhi; Hu, Xiaozhi; Shi, Shanshan; Guo, Xu; Zhang, Yupeng; Chen, Haoran

    2016-05-01

    Edge delamination is frequently observed in carbon fiber reinforced plastic (CFRP) laminates after machining, due to the low fracture toughness of the resin interfaces between carbon fiber plies. In this study, the effects of incorporating tough aramid fibers into the brittle CFRP system are quantified by measuring the residual properties of bolted CFRP. By adding short-aramid-fiber interleaves in CFRP laminates, the residual tensile strength have been substantially increased by 14 % for twill-weave laminates and 45 % for unidirectional laminates respectively. Moreover, tensile failure was observed as the major mode of toughened laminates, in contrast to shear failure of plain laminates. The qualitative FEM results agreed well with the experimental results that edge delamination would cause relatively higher shear stress and therefore alter the failure mode from tensile failure to shear failure.

  2. Finite element modeling of reinforced concrete beams with a hybrid combination of steel and aramid reinforcement

    International Nuclear Information System (INIS)

    Highlights: • Modeling of concrete beams reinforced steel and FRP bars. • Developed finite element models achieved good results. • The models are validated via comparison with experimental results. • Parametric studies are performed. - Abstract: Corrosion of steel bars has an adverse effect on the life-span of reinforced concrete (RC) members and is usually associated with crack development in RC beams. Fiber reinforced polymer (FRP) bars have been recently used to reinforce concrete members in flexure due to their high tensile strength and superior corrosion resistance properties. However, FRP materials are brittle in nature, thus RC beams reinforced with such materials would exhibit a less ductile behavior when compared to similar members reinforced with conventional steel reinforcement. Recently, researchers investigated the performance of concrete beams reinforced with a hybrid combination of steel and Aramid Fiber Reinforced Polymer (AFRP) reinforcement to maintain a reasonable level of ductility in such members. The function of the AFRP bars is to increase the load-carrying capacity, while the function of the steel bars is to ensure ductility of the flexural member upon yielding in tension. This paper presents a three-dimensional (3D) finite element (FE) model that predicted the load versus mid-span deflection response of tested RC beams conducted by other researchers with a hybrid combination of steel and AFRP bars. The developed FE models account for the constituent material nonlinearities and bond–slip behavior between the reinforcing bars and adjacent concrete surfaces. It was concluded that the developed models can accurately capture the behavior and predicts the load-carrying capacity of such RC members. In addition, a parametric study is conducted using the validated models to investigate the effect of AFRP bar size, FRP material type, bond–slip action, and concrete compressive strength on the performance of concrete beams when reinforced

  3. A Computational Study on the Use of an Aluminium Metal Matrix Composite and Aramid as Alternative Brake Disc and Brake Pad Material

    Directory of Open Access Journals (Sweden)

    Nosa Idusuyi

    2014-01-01

    Full Text Available A computational model for the heat generation and dissipation in a disk brake during braking and the following release period has been formulated. The model simulates the braking action by investigating the thermal behaviour occurring on the disc and pad surfaces during this period. A comparative study was made between grey cast iron (GCI, asbestos, Aluminium metal matrix composite (AMC, and aramid as brake pad and disc materials. The braking process and following release period were simulated for four material combinations, GCI disc and Asbestos pad, GCI disc and Aramid pad, AMC disc and Asbestos pad, AMC disc and Aramid pad using COMSOL Multiphysics software. The results show similarity in thermal behaviour at the contact surface for the asbestos and aramid brake pad materials with a temperature difference of 1.8 K after 10 seconds. For the brake disc materials, the thermal behaviour was close, with the highest temperature difference being 9.6 K. The GCI had a peak temperature of 489 K at 1.2 seconds and AMC was 465.5 K but cooling to 406.4 K at 10 seconds, while the GCI was 394.7 K.

  4. Effect of fibre orientations on the mechanical properties of kenaf–aramid hybrid composites for spall-liner application

    Institute of Scientific and Technical Information of China (English)

    R. YAHAYA; S.M. SAPUAN; M. JAWAID; Z. LEMAN; E.S. ZAINUDIN

    2016-01-01

    This paper presents the effect of kenaf fibre orientation on the mechanical properties of kenaf–aramid hybrid composites for military vehicle's spall liner application. It was observed that the tensile strength of woven kenaf hybrid composite is almost 20.78%and 43.55%higher than that of UD and mat samples respectively. Charpy impact strength of woven kenaf composites is 19.78%and 52.07%higher than that of UD and mat kenaf hybrid composites respectively. Morphological examinations were carried out using scanning electron microscopy. The results of this study indicate that using kenaf in the form of woven structure could produce a hybrid composite material with high tensile strength and impact resistance properties.

  5. Development study of concrete reinforcement made of aramid fiber-reinforced plastic rods with high radiation resistance. 1. Epoxy resin compounds with a handling at room temperature impregnation

    International Nuclear Information System (INIS)

    Aramid fiber-reinforced plastic (ArFRP) rods were developed in order to avoid from conduction current and/or magnetization of the metallic reinforcement using concrete constructions. For the polymer matrix, new epoxy resin compounds consist of tetraglycidyl diaminodiphenylmethane (30%), diglycidyl ether of bisphenol-A (60%), styrene oxide (10%) and aromatic diamine as a hardner were found to be the best formulation, and which were easily impregnated to the aramid fiber braiding yarn at room temperature. The ArFRP rods has a high radiation resistance, and the tensile strength was maintained to 98% (1.45 GPa) after irradiation dose of 100 MGy (absorbed energy MJ/kg), which is available for the reinforcement of concrete construction for the house of fusion reactor with super conducting magnets. (author)

  6. Development study of concrete reinforcement made of aramid fiber-reinforced plastic rods with high radiation resistance. 1. Epoxy resin compounds with a handling at room temperature impregnation

    Energy Technology Data Exchange (ETDEWEB)

    Udagawa, Akira; Seguchi, Tadao [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Moriya, Toshio; Matsubara, Sumiyuki; Hongou, Yoshihiko

    1999-03-01

    Aramid fiber-reinforced plastic (ArFRP) rods were developed in order to avoid from conduction current and/or magnetization of the metallic reinforcement using concrete constructions. For the polymer matrix, new epoxy resin compounds consist of tetraglycidyl diaminodiphenylmethane (30%), diglycidyl ether of bisphenol-A (60%), styrene oxide (10%) and aromatic diamine as a hardner were found to be the best formulation, and which were easily impregnated to the aramid fiber braiding yarn at room temperature. The ArFRP rods has a high radiation resistance, and the tensile strength was maintained to 98% (1.45 GPa) after irradiation dose of 100 MGy (absorbed energy MJ/kg), which is available for the reinforcement of concrete construction for the house of fusion reactor with super conducting magnets. (author)

  7. Antioxidant activity of new aramide nanoparticles containing redox-active N-phthaloyl valine moieties in the hepatic cytochrome P450 system in male rats.

    Science.gov (United States)

    Hassan, Hammed H A M; El-Banna, Sabah G; Elhusseiny, Amel F; Mansour, El-Sayed M E

    2012-07-10

    We report the synthesis of aramide nanoparticles containing a chiral N-phthaloyl valine moiety and their antioxidant activities on hepatic contents of cytochrome P₄₅₀, amidopyrene N-demethylase, aniline-4-hyroxylase and induced the hepatic content of cytochrome b5 and nicotinamide adenine dinucleotide phosphate (NADPH) cytochrome C-reductase. Polymers were obtained as well-separated spherical nanoparticles while highly aggregated particles via H-bonding organization of the aramide-containing pyridine led to a thin layer formation. The effects of the nanoparticles and CCl₄ on enzyme activities and thiobarbituric acid reactive substances (TBARS) levels of male rat liver were studied. Pretreatments of rats with the polyamides prior to the administration of CCl₄ decreased the hepatic content of the tested enzymes. Doses reduced the toxic effects exerted by (•CCl₃) upon the liver through inhibition of the cytochrome P₄₅₀ system. Inhibition of such metabolizing enzymes could reduce the carcinogenic effects of chemical carcinogens.

  8. The discussion of the photo-thermal fixation process for aramid 1313 fabric%芳纶1313织物使用光热固色工艺探讨

    Institute of Scientific and Technical Information of China (English)

    周东方; 高丽贤

    2014-01-01

    对芳纶1313织物用光线聚焦的方式进行还原染料染色;在光和热的作用下,激发芳纶纤维和还原染料分子的能量,从而完成对芳纶织物的上染。经过不同光热固色方法固色后的芳纶织物色牢度和上染情况较好,可以用于芳纶织物的染色。%The aramid 1313 fabric was dyed with the vat dyes via light focus The molecules energy of the aramid fibers and vat dyes were excited with light and heat treatment, and the aramid fabric completed dyeing. The color fastness and dyeing effect of the aramid fabric fixed with different methods of photo-thermal fixation were satisfactory. It was found that the photo-thermal fixation can be applied to aramid fabric dyeing process.

  9. Effect of layering sequence and chemical treatment on the mechanical properties of woven kenaf–aramid hybrid laminated composites

    International Nuclear Information System (INIS)

    Highlights: • The mechanical properties of woven kenaf/Kevlar hybrid composites were analysed. • The layering sequences affect the mechanical properties of hybrid composites. • Treated kenaf improves the mechanical properties of hybrid composites. - Abstract: This work aims to evaluate the effect of layering sequence and chemical treatment on mechanical properties of woven kenaf–Kevlar composites. Woven kenaf–aramid hybrid laminated composites fabricated through hand lay-up techniques by arranging woven kenaf and Kevlar fabrics in different layering sequences and by using treated kenaf mat. To evaluate the effect of chemical treatment on hybrid composites, the woven kenaf mat was treated with 6% sodium hydroxide (NaOH) diluted solution and compared mechanical properties with untreated kenaf hybrid composites. Results shows that the tensile properties of hybrid composites improved in 3-layer composites compared to 4-layer composites. Hybrid composite with Kevlar as outer layers display a better mechanical properties as compared to other hybrid composites. Tensile and flexural properties of treated hybrid composites are better than non-treated hybrid composites. The fractured surface of hybrid composites was investigated by scanning electron microscopy. This study is a part of exploration of potential application of the hybrid composite in high velocity impact application

  10. Ballistic Impact Response of Ceramic-Faced Aramid Laminated Composites Against 7.62 mm Armour Piercing Projectiles

    Directory of Open Access Journals (Sweden)

    Nityananda Nayak

    2013-07-01

    Full Text Available Ballistic impact response of ceramic- composite armor, consisting of zirconia toughened alumina (ZTA ceramic front and aramid laminated composite as backing, against 7.62 mm armor piercing (AP projectiles has been studied. Two types of backing composite laminates i.e. Twaron-epoxy and Twaron-polypropylene (PP of 10 mm and 15 mm thickness were used with a ceramic face of 4mm thick ZTA. The ceramic- faced and the stand alone composite laminates were subjected to ballistic impact of steel core 7.62 mm AP projectiles with varying impact velocities and their V50 ballistic limit (BL was determined. A sharp rise in BL was observed due to addition of ceramic front layer as compared to stand alone ones. The impact energy was absorbed during penetration primarily by fracture of ceramic, deformation and fracture of projectile and elastic-plastic deformation of flexible backing composite layer. The breaking of ceramic tiles were only limited to impact area and did not spread to whole surface and projectile shattering above BL and blunting on impact below BL was observed. The ceramic- faced composites showed higher BL with Twaron-PP as backing than Twaron-epoxy laminate of same thickness. This combination of ceramic-composite laminates exhibited better multi-hit resistance capability; ideal for light weight armor.Defence Science Journal, 2013, 63(4, pp.369-375, DOI:http://dx.doi.org/10.14429/dsj.63.2616

  11. Behavior of Aramid Fiber/Ultrahigh Molecular Weight Polyethylene Fiber Hybrid Composites under Charpy Impact and Ballistic Impact

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The aramid fiber/UHMWPE (ultrahigh molecular weight polyethylene) fiber hybrid composites (AF/DF) were manufactured. By Charpy impact, the low velocity impact behavior of AF/DF composite was studied. And the high velocity impact behavior under ballistic impact was also investigated. The influence of hybrid ratio on the performances of low and high velocity impact was analyzed, and hybrid structures with good impact properties under low velocity impact and high velocity were optimized. For Charpy impact, the maximal impact load increased with the accretion of the AF layers for AF/DF hybrid composites. The total impact power was reduced with the decrease of DF layers and the delamination can result in the increase of total impact power. For ballistic impact, the DF ballistic performance was better than that of the AF and the hybrid ratio had a crucial influence. The failure morphology of AF/DF hybrid composite under Charpy impact and ballistic impact was analyzed. The AF/DF hybrid composites in suitable hybrid ratio could attain better performance than AF or DF composites.

  12. Mutual irradiation grafting on indigenous aramid fiber-3 in diethanolamine and epichlorohydrin and its effect on interfacially reinforced epoxy composite

    Science.gov (United States)

    Xing, Lixin; Liu, Li; Xie, Fei; Huang, Yudong

    2016-07-01

    The surface of indigenous aramid fiber-3 (IAF3) was decorated via mutual irradiation grafting process in diethanolamine (DEA) and epichlorohydrin (ECH), respectively, with the assist of high energy gamma rays. This modification method with great permeability produced the homogeneous and ameliorative AF3 surfaces, which were observed by the scanning electron microscopy (SEM) and atom forced microscopy (AFM). Enhanced surface free energy and reduced contact angles of irradiated AF3 verified the fabulous effectiveness of mutual irradiation without seriously injured tensile strength. The composites based on epoxy resin (ER) polymer as the matrix and irradiated IAF3 grafted DEA and ECH as the reinforcement. By capitalizing on the irradiated IAF3 which has higher wettability and adsorption on resin, the irradiated IAF3-ECH/ER composites exhibit admirable interfacial mechanical performance as compared to the pristine IAF3 contained composites. The interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and flexural strength of composites were remarkable improved to 86.5, 60.13 and 511 MPa respectively, from the pristine IAF3/ER composite with IFSS of 65.9 MPa, ILSS of 48.1 MPa, and flexural strength of 479 MPa.

  13. Data statistic analysis of China patents relating to aramid fiber%芳纶中国专利数据统计分析

    Institute of Scientific and Technical Information of China (English)

    杨翔

    2015-01-01

    The patents relating to aramid fiber from 1985 to 2011 were searched in China Patent Retrieve System Abstract Database ( CPRSABS) .The distribution of patent kind, situation of grant of patent, annual applications for patent received, source of applicants and major applicants at home and abroad were quantitatively analyzed to reveal the progress and application situation of aramid fiber technologies.%以中国专利检索系统文摘数据库( CPRSABS)中的检索结果为对象,对1985—2011年间芳纶技术专利申请的专利类型及授权情况、年度申请量分布、申请人来源地分布和国内外主要申请人等方面进行统计分析。结果表明,芳纶专利技术集中度较高,跨国公司在技术开发和专利布局上优势明显。

  14. 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)

    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%

  15. Compatibility and mechanical properties of liquid crystalline modified aramid reinforced epoxy resin%液晶改性芳纶增强环氧树脂的相容性与力学性能

    Institute of Scientific and Technical Information of China (English)

    张爱玲; 刘慧; 吕震乾; 王松; 李三喜

    2012-01-01

    针对环氧树脂复合材料存在的应力开裂以及与基体界面相容性差等问题,采用液晶和离子单体对芳纶纤维进行改性,再与环氧树脂及固化剂按一定比例混合,制得液晶改性芳纶增强环氧树脂复合材料.正交试验结果表明,常温下固化20 min,芳纶、环氧树脂与固化剂的质量比为0.07∶35∶11,复合材料的弯曲应力为445.6 MPa,应变为0.975%,比水解芳纶增强环氧树脂复合材料、芳纶增强环氧树脂复合材料的弯曲应力分别提高了29%和33%.扫描电镜研究表明,复合材料中分散相在基体中的分散性较好,有良好的界面相容性,断面处的断裂方式由脆性断裂变为韧性断裂.红外光谱研究表明,加入液晶改性芳纶的复合材料出现了磺酸基团和氮氮双键的特征吸收峰.%To solve such problems as stress crack and poor interface compatibility in epoxy resin composites,a liquid crystalline modified aramid reinforced epoxy resin composite was prepared through modifying aramid fiber by liquid crystalline and ion monomer and then mixing with epoxy resin and curing agent in certain proportion.The results of orthogonal experiment reveal that when the mass ratio of aramid fiber,epoxy resin and curing agent is 0.07∶ 35∶ 11 as well as the curing time at room temperature is 20 minutes,the bending stress and strain of the fabricated composite are 445.6 MPa and 0.975%,respectively.The bending stress of liquid crystalline modified aramid reinforced epoxy resin composite increases by 29% and 33% than that of hydrolytic aramid reinforced epoxy resin composite and raw aramid reinforced epoxy resin composite,respectively.The scanning electron microscope observation shows that the modified aramid has good dispersion and interface compatibility in epoxy resin matrix.The fracture mode for the composite changes from brittle fracture to ductile fracture.The infrared spectroscopy(IR) investigation indicates that the S=O and N

  16. 国产对位芳纶纸蜂窝与NH-1蜂窝性能的对比研究%A contrast Study on Domestic P-Aramid Honeycomb and NH-1 Honeycomb

    Institute of Scientific and Technical Information of China (English)

    郝巍; 罗玉清; 王萌

    2011-01-01

    In this paper,three specifications of honeycomb core material were made by domestic para-aramid paper and Nomex(T412) paper separately,and the comparative analysis of their main physical and mechanical properties was studied.The results showed that the main properties of domestic para-aramid paper honeycomb were better than those of T412 Nomex NH-1 honeycomb.Domestic para-aramid paper honeycomb could basically meet the requirements of users,but its preparation process still need be improved.%对国产对位芳纶纸与T412 Nomex纸分别制作的3种规格蜂窝,并进行了主要物理和力学性能对比分析。结果表明,国产对位芳纶纸蜂窝主要性能优于T412 Nomex纸的NH-1蜂窝,基本能够满足用户的使用要求,但其对位芳纶纸在制备的精度上仍需要改进。

  17. Study on the performances of the Para-aramid fibrid%对位芳纶沉析纤维性能研究

    Institute of Scientific and Technical Information of China (English)

    江明; 张美云; 陆赵情; 杨斌; 刘俊华

    2014-01-01

    The surface morphology,chemical structure,degree of crystallinity and thermal properties of Para-aramid fibrid were studied by using SEM,AFM,FT-IR,XRD and TGA.This paper was used to offer an ex-perimental foundation for promoting its extensive use as one kind of composite reinforced materials.Results in-dicated that Para-aramid fibrid was non-granular and small-sized,it had a fiber or film looking,roughness sur-face,supple shape.The fiber had a secondary amide structure,and its crystallinity was 28.55 percent.As a re-sult,it contained amounts of amorphous compositions,and the crystalline size in fibers was tiny.The initial de-composition temperature of fiber was 490 ℃,TG10% was 550 ℃,thus demonstrated its stable molecular chain structure and excellent thermal properties.%采用 SEM、AFM、FT-IR、XRD 和 TGA 对新型芳纶材料对位芳纶沉析纤维的表面形貌、化学结构、结晶程度和热学特性4个方面进行了分析检测,为研究对位芳纶沉析纤维的结构性能奠定实验基础,有利于其作为复合增强材料的广泛应用。结果表明,对位芳纶沉析纤维是非粒状且尺寸较小,外形上既像纤维又像薄膜,表面粗糙,形态柔顺;纤维具有仲酰胺结构特征;纤维结晶度为28.55%,非晶化的成分较多,且晶粒尺寸较小;纤维初始分解温度为490℃, TG10%为550℃,分子链结构稳定,热学性能优异。

  18. Comparison Of Flat-Knitted Structures Made Of Poly(P-Phenylene-2,6-Benzobisoxazole) And Para-Aramid Referring To Their Stab Resistance

    Science.gov (United States)

    Obermann, M.; Aumann, S.; Heimlich, F.; Weber, M. O.; Schwarz-Pfeiffer, A.

    2016-07-01

    In the field of protective gear, developers always aim for lighter and more flexible material in order to increase the wearing comfort. Suppliers now work on knitted garments in the sports-sector as well as in workwear and protective gear for policemen or security-agents. In a recent project different knitted structures made of a poly(p-phenylene-2,6-benzobisoxazole) (PBO)-multifilament were compared to their counterparts made of para-aramid. In focus of the comparison stood the stab-resistance linked to either the mass per unit area or the stitch density. The tested fabrics were produced on hand flat knitting machines as well as on electronical flat knitting machines of the type Stoll CMS 330TC4, in order to analyse fabrics with different tightness factor and machine gauges. The stab resistance of the different knitted fabrics was examined according to the standard of the Association of Test Laboratories for Bullet, Stab or Pike Resistant Materials and Construction Standards. The presentation includes the depiction of the results of the test series and their interpretation. Furthermore it will give an outlook on most suitable combinations of materials and structures to be used in protective gear.

  19. 碳/芳纶纤维增强混凝土温度变形自约束作用的研究%Research on Self-restraint for Temperature Deformation of Carbon/Aramid Fiber Reinforced Concrete

    Institute of Scientific and Technical Information of China (English)

    姚立宁; 张妃二; 郭仁俊; 谢灵

    2002-01-01

    用具有温度负膨胀特性参数的碳/芳纶纤维增强水泥及混凝土可以增加其强度及机械性能,同时还可以控制其温度变形以防止开裂.文章根据各向异性材料分析方法,对碳/芳纶纤维增强水泥及混凝土的温度变形自约束作用进行了研究和试验.%Cement and concrete reinforced by carbon and aramid fibers which have negative thermal expansion coefficients can improve strength and mechanical properties. And they can also control temperature deformation in the concrete in order to protect from cracks. This paper investigated on analysis and experiment for self-restraint of temperature deformation in carbon/aramid reinforced concrete according to analysis method in anisotropic materials.

  20. 对位芳纶浆粕在密封制品中的应用%The application of para-aramid (PPTA) pulp in sealing product

    Institute of Scientific and Technical Information of China (English)

    邱召明; 马千里; 姜茂忠; 陈文建; 周爱民; 侯春蕾

    2012-01-01

    介绍了对位芳纶浆粕的发展现状及其无石棉垫片的基本特性,通过应用实例表明泰普龙浆粕能满足无石棉垫片技术和市场的需求。指出随着石棉的禁用和限制以及国产对位芳纶生产质量与规模的快速发展,国产芳纶浆粕将有实质性突破,从而促进国产无石棉垫片的研究与生产。%The development of PPTA-pulp and the basic characters of non-asbestos gasket were introduced in this paper. The application examples show that Taparan pulp can meet the requirement of non-asbestos gasket. With the forbidden of asbestos and the rapid development of domestic Para-aramid, domestic PPTA-pulp will have a substantial breakthrough, so the research and production of domestic non-asbestos gasket will be promoted.

  1. Effect of Modification Adhesive on Properties ofAramid UD Plate%改性胶粘剂对芳纶单向布防弹性能的影响

    Institute of Scientific and Technical Information of China (English)

    吴中伟; 高沛; 刘元坤; 潘智勇; 梁立; 方心灵

    2011-01-01

    The hardener and defoamer was added to the acrylic adhesives by physical blending, and improved the surface of UD plate which was sticky and uneven. The mechanical properties of the UD plate were also tested by electronic tensile testing machine. The result showed that the hardener could significantly improve the bond strength of the aramid UD plate and the surface of the UD plate was not sticky; The defoamer could significantly improve the apparent quality that the surface of UD plate was smooth and no bubbles; The hardener could improve the mechanical properties of the UD plate and the performance of the material bullet-proof, and also could reduce the bullet penetration to layers of samples, and depress the average degree of the roughness, then it could decrease the secondary trauma on the human body.%通过物理共混的方法,将固化剂及消泡剂加入到丙烯酸酯胶粘剂中,从而改善丙烯酸酯胶粘剂压合的单向(UD)芳纶布表面粘手及不平整的问题,并利用电子拉力实验机对无纬布进行力学性能测试。研究表明,固化剂的添加可明显提高UD布的粘结强度,并且UD布的表面不粘手;消泡剂的添加能够明显改善UD布的表观质量,UD布表面平整和无气泡;添加固化剂可提高UD布的力学性能,同时还可提高了材料的防弹性能,子弹穿透层数减少,UD布的平均弹坑凹陷深度明显降低,减少了对人体造成的钝伤。

  2. Effect of penetrants on the aramid Nomex

    Indian Academy of Sciences (India)

    Anjana Jain; Kalyani Vijayan

    2000-06-01

    The response of Nomex sheets to some penetrants has been analyzed. The process of moisture uptake depends on the relative humidity (RH) of the ambient atmosphere and the initial characteristics of the polymer. In the case of common laboratory solvents, the uptake by the polymer shows an inverse dependence on the molar volume of the former. Although the calendered and the uncalendered Nomex sheets exhibit an overall similarity in their response to various penetrants, quantitative comparison reveals distinct differences.

  3. Analysing the nanoporous structure of aramid fibres

    DEFF Research Database (Denmark)

    Pauw, Brian Richard; Vigild, Martin Etchells; Mortensen, Kell;

    2010-01-01

    After consideration of the applicability of classical methods, a novel analysis method for the characterization of fibre void structures is presented, capable of fitting the entire anisotropic two-dimensional scattering pattern to a model of perfectly aligned, polydisperse ellipsoids. It is teste...

  4. 耐酸型玻纤填充芳纶1313复合针刺毡滤料的制备与性能%Preparation and Properties of Acid Resistant Glass Fiber/Aramid Fiber Compound Filter Materials of Needled Felt

    Institute of Scientific and Technical Information of China (English)

    郑玉婴; 蔡伟龙; 程雷

    2011-01-01

    By using domestic aramid fiber 1313 and glass fiber as main raw materials,the composite needled felts were prepared by reasonable structure design,process optimization and advanced non-woven needle technology,of which the process included high temperature heat-setting,singeing,calendering,acid-resisting treatment,and so on.The wearability,bursting strength,acid-resistance and filtration performance were characterized;it is found that the compound filter materials have excellent acid-resistance,filtering precision,abrasion resistance and high performance-cost ratio.The scanning electron microscope(SEM) photos show that the surface of composite filters is coated with polytetrafluoroethylene(PTFE),improving chemical resistance and friction coefficient of filter materials.%以国产芳纶1313为主要原料,通过合理的结构设计与工艺优化,填充一定比例的玻璃纤维,利用先进的无纺针刺工艺制作成毡,再经高温热定型、烧毛压光及耐酸处理等多种技术制作成产品。通过对其进行耐磨性、耐破性、耐酸性和过滤性能测试,研究发现,该复合滤料具有强耐酸性、过滤精度高、耐磨损、高性价比等特点。通过扫描电子显微镜观察发现,滤料表面形成一层聚四氟乙烯(PTFE)层,PTFE优良的抗化学性能和较低的摩擦系数大大改善了复合滤料的综合性能。

  5. Nanofibrous polymeric beads from aramid fibers for efficient bilirubin removal.

    Science.gov (United States)

    Peng, Zihang; Yang, Ye; Luo, Jiyue; Nie, Chuanxiong; Ma, Lang; Cheng, Chong; Zhao, Changsheng

    2016-08-16

    Polymer based hemoperfusion has been developed as an effective therapy to remove the extra bilirubin from patients. However, the currently applied materials suffer from either low removal efficiency or poor blood compatibility. In this study, we report the development of a new class of nanofibrous absorbent that exhibited high bilirubin removal efficiency and good blood compatibility. The Kevlar nanofiber was prepared by dissolving micron-sized Kevlar fiber in proper solvent, and the beads were prepared by dropping Kevlar nanofiber solutions into ethanol. Owing to the nanofiborous structure of the Kevlar nanofiber, the beads displayed porous structures and large specific areas, which would facilitate the adsorption of toxins. In the adsorption test, it was noticed that the beads possessed an adsorption capacity higher than 40 mg g(-1) towards bilirubin. In plasma mimetic solutions, the beads still showed high bilirubin removal efficiency. Furthermore, after incorporating with carbon nanotubes, the beads were found to have increased adsorption capacity for human degradation waste. Moreover, the beads showed excellent blood compatibility in terms of a low hemolysis ratio, prolonged clotting times, suppressed coagulant activation, limited platelet activation, and inhibited blood related inflammatory activation. Additionally, the beads showed good compatibility with endothelial cells. In general, the Kevlar nanofiber beads, which integrated with high adsorption capacity, good blood compatibility and low cytotoxicity, may have great potential for hemoperfusion and some other applications in biomedical fields. PMID:27481656

  6. Nanofibrous polymeric beads from aramid fibers for efficient bilirubin removal.

    Science.gov (United States)

    Peng, Zihang; Yang, Ye; Luo, Jiyue; Nie, Chuanxiong; Ma, Lang; Cheng, Chong; Zhao, Changsheng

    2016-08-16

    Polymer based hemoperfusion has been developed as an effective therapy to remove the extra bilirubin from patients. However, the currently applied materials suffer from either low removal efficiency or poor blood compatibility. In this study, we report the development of a new class of nanofibrous absorbent that exhibited high bilirubin removal efficiency and good blood compatibility. The Kevlar nanofiber was prepared by dissolving micron-sized Kevlar fiber in proper solvent, and the beads were prepared by dropping Kevlar nanofiber solutions into ethanol. Owing to the nanofiborous structure of the Kevlar nanofiber, the beads displayed porous structures and large specific areas, which would facilitate the adsorption of toxins. In the adsorption test, it was noticed that the beads possessed an adsorption capacity higher than 40 mg g(-1) towards bilirubin. In plasma mimetic solutions, the beads still showed high bilirubin removal efficiency. Furthermore, after incorporating with carbon nanotubes, the beads were found to have increased adsorption capacity for human degradation waste. Moreover, the beads showed excellent blood compatibility in terms of a low hemolysis ratio, prolonged clotting times, suppressed coagulant activation, limited platelet activation, and inhibited blood related inflammatory activation. Additionally, the beads showed good compatibility with endothelial cells. In general, the Kevlar nanofiber beads, which integrated with high adsorption capacity, good blood compatibility and low cytotoxicity, may have great potential for hemoperfusion and some other applications in biomedical fields.

  7. 2D-ACAR investigations of PPT aramid fibres

    International Nuclear Information System (INIS)

    2D-ACAR spectra of PPT (poly(p-phenylene terephthalamide)) fibres which contain structural elongated open spaces in the crystallographic unit cell show a p-Ps peak with an elliptical cross-section and side lobes. Peak broadening suggests dimensions of ∝14-17 by 7-9 A for the open spaces and indicates some penetration of Ps into the interlayer spacing. The side lobes can be related to projected reciprocal lattice points and indicate Ps delocalization. 2D-ACAR has also been used to study the evolution of water release from the open spaces. (orig.)

  8. Viscoelastic properties of short aramid fibres-reinforced rubbers

    NARCIS (Netherlands)

    Shirazi, S.; Talma, A.G.; Noordermeer, J.W.M.

    2013-01-01

    Among short fiber-reinforced composites, those with rubber matrices have gained great importance due to the advantages they have in processing and low cost, coupled with high strength. These composites combine the elastic behavior of rubbers with strength and stiffness of fibers. Reinforcement with

  9. Wear behaviour of discontinuous aramid fibre reinforced ultra-high molecular weight polyethylene

    NARCIS (Netherlands)

    Hofste, JM; Smit, HHG; Pennings, AJ

    1996-01-01

    The wear of Ultra-High Molecular Weight Polyethylene has generated new concern regarding the long-term clinical performance of total joint replacements. To extend the lifetime of artificial joints, it is necessary to decrease tt-le wear rate of UHMWPE. One possible solution is the incorporation of a

  10. Influence of Stitching Parameters on Tensile Strength of Aramid/Vinyl Ester Composites

    Directory of Open Access Journals (Sweden)

    Mehmet KARAHAN

    2013-03-01

    Full Text Available Stitching process is used to provide structural integrity and through-the-thickness reinforcement in the composite materials. In this study, the effect of sewing parameters on tensile strength in stitched composite laminates was examined. In the production of composite laminates, Twaron T-750 type plain weave fabric was used as reinforcement material and a Polives 702 Bisphenol-A type epoxy based vinyl ester as resin. The effects of stitch density and stitch direction or stitch pattern on tensile strength of composite samples were studied and, as a result of the experiments, it was observed that higher tensile strength occurs with low stitch densities in stitched laminates.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3829

  11. Influence of Stitching Parameters on Tensile Strength of Aramid/Vinyl Ester Composites

    OpenAIRE

    Karahan, Mehmet; Yusuf ULCAY; KARAHAN, Nevin; Kuş, Abdil

    2013-01-01

    Stitching process is used to provide structural integrity and through-the-thickness reinforcement in the composite materials. In this study, the effect of sewing parameters on tensile strength in stitched composite laminates was examined. In the production of composite laminates, Twaron T-750 type plain weave fabric was used as reinforcement material and a Polives 702 Bisphenol-A type epoxy based vinyl ester as resin. The effects of stitch density and stitch direction or stitch pattern on ten...

  12. Poly-m-aramid nanofiber mats: Production for application as structural modifiers in CFRP laminates

    Science.gov (United States)

    Mazzocchetti, Laura; D'Angelo, Emanuele; Benelli, Tiziana; Belcari, Juri; Brugo, Tommaso Maria; Zucchelli, Andrea; Giorgini, Loris

    2016-05-01

    Poly(m-phenylene isophtalamide) electrospun nanofibrous membranes were produced to be used as structural reinforcements for carbon fiber reinforced composites production. In order for the polymer to be electrospun, it needs however to be fully solubilized, so the addition of some salts is required to help disrupt the tight macromolecular packing based on intra- and inter-molecular hydrogen bonding. Such salts may also contribute to the electrospinnability of the overall solution, since the provide it with a higher conductivity, whatever the solvent might be. The salt haobwever stays in the final nanofibrous mat. The membranes containing the salt are also observed to be highly hygroscopic, with a water content up to 26%, in the presence of 20%wt LiCl in the nanofibrous mat. When those membranes were interleaved among prepregs to produce a laminates, the obtained composite displayed thermal properties comparable to those of a reference nanofiber-free composite, though the former showed also easier delamination. Hence the removal of the hygroscopic salt was performed, that lead to thinner membranes, whose water content matched that of the pristine polymer. The washing step induced a thinning of the layers and of the fibers diameters, though no fiber shrinking nor membrane macroscopic damages were observed. These preliminary encouraging results thus pave the way to a deeper study of the optimized condition for producing convenient poly(m-phenylene isophtalamide) electrospun nanofibrous membranes to be used for carbon fiber reinforced composites structural modification.

  13. Synthesis and properties of lyotropic poly(amide-block-aramid) copolymers

    NARCIS (Netherlands)

    De Ruijter, C.

    2006-01-01

    This thesis describes the synthesis and properties of liquid crystalline block copolymers comprised of alternating rigid and flexible blocks for the preparation of self-reinforcing materials. The incentive for this work was the expectation that the rigid segments would phase separate on a microscopi

  14. Lung response to ultrafine Kevlar aramid synthetic fibrils following 2-year inhalation exposure in rats.

    Science.gov (United States)

    Lee, K P; Kelly, D P; O'Neal, F O; Stadler, J C; Kennedy, G L

    1988-07-01

    Four groups of 100 male and 100 female rats were exposed to ultrafine Kevlar fibrils at concentrations of 0, 2.5, 25, and 100 fibrils/cc for 6 hr/day, 5 days/week for 2 years. One group was exposed to 400 fibrils/cc for 1 year and allowed to recover for 1 year. At 2.5 fibrils/cc, the lungs had normal alveolar architecture with a few dust-laden macrophages (dust cell response) in the alveolar airspaces. At 25 fibrils/cc, the lungs showed a dust cell response, slight Type II pneumocyte hyperplasia, alveolar bronchiolarization, and a negligible amount of collagenized fibrosis in the alveolar duct region. At 100 fibrils/cc, the same pulmonary responses were seen as at 25 fibrils/cc. In addition, cystic keratinizing squamous cell carcinoma (CKSCC) was found in 4 female rats, but not in male rats. Female rats had more prominent foamy alveolar macrophages, cholesterol granulomas, and alveolar bronchiolarization. These pulmonary lesions were related to the development of CKSCC. The lung tumors were derived from metaplastic squamous cells in areas of alveolar bronchiolarization. At 400 fibrils/cc following 1 year of recovery, the lung dust content, average fiber length, and the pulmonary lesions were markedly reduced, but slight centriacinar emphysema and minimal collagenized fibrosis were found in the alveolar duct region. One male and 6 female rats developed CKSCC. The lung tumors were a unique type of experimentally induced tumors in the rats and have not been seen as spontaneous tumors in man or animals. Therefore, the relevance of this type of lung tumor to the human situation is minimal.

  15. Analysis on the Adherent Mechanism between Aramid Fiber and Fibrids of Aramid Paper by AFM%AFM分析芳纶纸中纤维与浆粕的粘附机理

    Institute of Scientific and Technical Information of China (English)

    张素风; 孙杰; 康春蕾

    2013-01-01

    对芳纶纤维和浆粕进行SEM和AFM形貌观察,采用原子力显微镜(AFM)探针修饰技术,对芳纶纤维与浆粕间的粘附力进行探索性研究.芳纶浆粕薄膜修饰的探针与芳纶纤维和浆粕间的粘附力测试结果分别为1.71 nN和9.26 nN.借助Derjaguin Muller Toporov (DMT)理论和表面自由能,计算出理论作用力,证实了AFM法测定表面粘附力的结果.

  16. Study on the dyeing properties of Nomex aramid fibers%芳纶-Nomex染色性能探讨

    Institute of Scientific and Technical Information of China (English)

    谭艳君; 余艳娥

    2007-01-01

    芳纶织物具有很高的结晶度和取向度,化学结构稳定,很难上染.通过采用化学助剂使芳纶分子之间的间隙增大,降低芳纶分子间的范德华力,有利于染料进入纤维内部,提高染料的上染率.

  17. Effects of different fluorination routes on aramid fiber surface structures and interlaminar shear strength of its composites

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jie; Dai, Yunyang; Wang, Xu; Huang, Jieyang; Yao, Jin [State Key Laboratory of Polymer Material and Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Yang, Jin [State Key Lab of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Liu, Xiangyang, E-mail: lxy6912@sina.com [State Key Laboratory of Polymer Material and Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2013-04-01

    Poly-p-phenylene-benzimidazole-terephthalamide (PBIA) fiber was surface modified by direct fluorination under three different routes. The fiber was dried under vacuum to remove physisorbed water trapped on it and then fluorinated by the fluorine and oxygen gases or by the fluorine gas only. Results show that the interlaminar shear strength (ILSS) value of these two kinds of fluorinated fiber reinforced epoxy resin was 43.9 MPa and 51.0 MPa, which was improved about 14.0% and 32.5% compared with that of the virgin fiber (38.5 MPa), respectively. In the third route, the fiber was fluorinated by the fluorine and oxygen gases without removing physisorbed water, and the ILSS value decreased for nearly 31.2%, i.e. from 38.5 MPa to 26.5 MPa. X-ray photoelectron spectroscopy (XPS) showed that oxygen-containing and fluorine-containing chemical groups were introduced onto the fiber surface after fluorination, providing a stronger chemical bonding to polymeric matrices. Scanning electronic microscopy (SEM) indicated that the surface morphology of the fluorinated PBIA fiber varied with the different fluorination routes. A mass of compact micro groove structures was formed by the route that the fiber was dried to remove physisorbed water and then fluorinated with fluorine gas only. And these structures would markedly improve the ILSS of the composites. But, a mass of unstable flake surface structures was formed by the route that the fiber was fluorinated with the fluorine and oxygen gases without removing physisorbed water. And these structures would be the weak interface between the fiber and matrix and decrease the ILSS, even a lot of polar chemical groups were bonded onto the fiber surface as well.

  18. 芳纶Ⅲ防弹性能分析%Anti-ballistic properties of aramid fiber Ⅲ

    Institute of Scientific and Technical Information of China (English)

    刘克杰; 高虹; 黄献聪; 王凤德; 彭涛

    2014-01-01

    以Staramid F358芳纶Ⅲ作为防弹材料,通过单向复合工艺制造成靶板,采用V50靶板实验研究了芳纶Ⅲ的防弹性能,对其防弹性能进行了理论分析,并与芳纶Ⅱ防弹材料进行了比较.结果表明:芳纶Ⅲ靶板的V50值为572.1 m/s,比吸能值为153 Jm2/kg;芳纶Ⅲ防弹性能比芳纶Ⅱ提高近30%;超高的拉伸断裂强度是芳纶Ⅲ防弹性能更优的根本原因,芳纶Ⅲ的防弹性能还有进一步提升的空间.

  19. 英威达己二胺和尼龙66聚合物项目在中国上海奠基

    Institute of Scientific and Technical Information of China (English)

    周甜

    2014-01-01

    Aluminum glue was made up to coat the outer layer of aramid1313 fabric for new fire insulation clothing . Combustion performance and thermal protective performance of aramid 1313 fabric, before aluminum glue coating and after , were compared .The results show that the damage length of aramid 1313 fabric , coated with aluminum glue , is less than that of aramid1313 fabric and the thermal protective coefficient of the former is higher than aramid1313 fabric.In conclusion, the aramid1313 fabric coated can be used as the outer layer of fire insulation protective clothing , having the advantages of retardant , insula-tion thermal and high temperature thermal protective .

  20. The effect of chromic acid treatment on the mechanical and tribological properties of aramid fibre reinforced ultra-high molecular weight polyethylene composite

    NARCIS (Netherlands)

    Hofste, JM; Pennings, AJ; Schut, J.A.

    1998-01-01

    Surface oxidation of ultra-high molecular weight polyethylene (UHMWPE) powder has an influence on the mixing procedure of chopped fibres and UHMWPE powder. Due to this oxidation hydrogen bonds can be formed between the fibres and powder particles, leading to a more homogeneous fibre-powder mixture.

  1. 几种高性能芳纶纤维的耐光性评价%Investigation on Photodegradation of High Performance Aramid Fibers

    Institute of Scientific and Technical Information of China (English)

    刘晓艳; 于伟东

    2007-01-01

    利用氙弧灯和碳弧灯分别照射3种高性能芳纶纤维(Kevlar(R)129,Zylon(R)AS(PBO)和Kermel(R)纤维),分析它们力学性能的变化.Kevlar(R)129纤维耐光性最好,Kermel(R)纤维耐光稳定性最差.实验发现,尽管Zylon(R)AS(PBO)纤维初始强力最高,但其耐光性较差,在光照条件下下降剧烈.同时发现碳弧灯下纤维试样的损失比氙弧灯下辐照损失大.通过纤维表观和断裂端形貌观察可清楚看出,这3种高性能纤维都因光辐照损伤,且都有脆性断裂特征.

  2. 芳纶无纬布生产质量的控制研究%PROCESS RESEARCH FOR IMPROVING QUALITY OF ROLLED ARAMID NON-WOOF CLOTH

    Institute of Scientific and Technical Information of China (English)

    刘元坤; 许冬梅; 艾青松; 方心灵

    2015-01-01

    通过对卷状芳纶无纬布生产工艺的研究,探究几个关键工艺条件(包括丝束退绕张力、胶粘剂的配方、层压复合的温度、压力及运行速度等)对卷状芳纶无纬布的性能(包括表观性能和防弹性能)的影响,摸索出一组最佳的工艺条件,由此制备的无纬布产品综合性能最优.由此工艺织造成的卷状无纬布防弹芯片通过美国NIJ0101.06测试标准和公安部GA141-2010标准测试,验证了此生产工艺的优越性.

  3. Separator material for electrochemical cells

    Science.gov (United States)

    Cieslak, Wendy R.; Storz, Leonard J.

    1991-01-01

    An electrochemical cell characterized as utilizing an aramid fiber as a separator material. The aramid fibers are especially suited for lithium/thionyl chloride battery systems. The battery separator made of aramid fibers possesses superior mechanical strength, chemical resistance, and is flame retardant.

  4. 芳纶1414纤维生产过程中的节能减排措施%Energy Saving and Emission Reducing Measures in P-Aramide Production

    Institute of Scientific and Technical Information of China (English)

    齐士原

    2014-01-01

    中蓝晨光化工研究设计院有限公司在芳纶1414生产过程中采取有效技术改造措施,使用目前较先进的芳纶1414生产装置和节能环保设备,在降低能源消耗的同时,达到了减排、保护环境的目的.

  5. 芳纶Ⅲ与Kevlar-49纤维组成、结构与力学性能的对比%Comparision of Aramid Ⅲ Fibre's Component, Structure and Mechanical Properties With Kevlar-49 Fibre

    Institute of Scientific and Technical Information of China (English)

    周玉玺; 曾金芳; 王斌

    2007-01-01

    通过红外光谱和元素分析对芳纶Ⅲ和Kevlar-49纤维的进行对比研究得出,芳纶Ⅲ纤维中存在含氮的芳杂环结构,并结合X射线衍射方法分析芳纶Ⅲ和Kevlar-49纤维的晶体结构,其中芳纶Ⅲ纤维的结晶度为30.44%,明显低于Kevlar-49.芳纶Ⅲ力学性能优于Kevlar-49,其拉伸强度、弹性模量和断裂延伸率分别为4 250 MPa、139 MPa和3.2%.

  6. Study of the bullet-proof properties of the sandwich structure of armor steel reinforced by aramid fiber%装甲钢复合芳纶泡沫夹层结构防弹性能研究

    Institute of Scientific and Technical Information of China (English)

    李欢秋; 陈德兴; 王洪泳

    2010-01-01

    装甲钢或芳纶防弹板具有良好的防高速弹丸贯穿性能,而采用复合结构则可以大大提高单一防弹板的防弹性能.通过弹道实验方法研究了装甲钢复合芳纶泡沫夹层结构抗56式7.62mm普通钢芯弹贯穿特性;探讨了不同复合形式的装甲钢复合芳纶泡沫夹层结构抵抗速度为450~550m/s弹丸的防护效能和影响防弹板吸收子弹动能的因素;提出了装甲钢复合芳纶泡沫夹层结构最佳防弹速度区间的概念和相应的V50估算公式,由此可以设计出防弹效费比最佳的防弹板.

  7. [The choice of work clothes and the risk of ignition].

    Science.gov (United States)

    Larsen, T K; Ebbehøj, J

    1989-12-11

    Cotton is easily ignited in atmospheric air. Aramid (Nomex) is only ignited if the oxygen concentration is 30% and the ignition temperature is 800 degrees C. Thirty one steelmill employees used one hundred and twenty suits of working clothes made of cotton, cotton/polyamide, cotton/polyester or Aramid (Nomex) in a four month period. 17% were more comfortable when using cotton/polyester. No differences were found between cotton and Aramid. Cotton should not be used as textile for working clothes in environments with risks of ignition. PMID:2609447

  8. The effect of micropores on output properties of laminate materials with assumed medical implantation

    OpenAIRE

    L.A. Dobrzański; A. Pusz; A. J. Nowak

    2009-01-01

    Purpose: Examination of elaborated composite material in terms of specific application in medicine – as internal prostheses of oesophagus. Development of the manufacturing technology of aramid-silicon laminated material and definition of the micro-cavities amount formed during production of the laminates.Design/methodology/approach: Aramid-silicon laminated material was made by a method of manual formation of laminates that is impregnation of reinforcement with matrix to hardening silicone pr...

  9. Zinc Oxide Nanowire Interphase for Enhanced Lightweight Polymer Fiber Composites

    Science.gov (United States)

    Sodano, Henry A.; Brett, Robert

    2011-01-01

    The objective of this work was to increase the interfacial strength between aramid fiber and epoxy matrix. This was achieved by functionalizing the aramid fiber followed by growth of a layer of ZnO nanowires on the fiber surface such that when embedded into the polymer, the load transfer and bonding area could be substantially enhanced. The functionalization procedure developed here created functional carboxylic acid surface groups that chemically interact with the ZnO and thus greatly enhance the strength of the interface between the fiber and the ZnO.

  10. Surface charges in blending short fibres with polyethylene powder

    NARCIS (Netherlands)

    Hofste, JM; Kersten, MJE; van Turnhout, J; Pennings, AJ

    1998-01-01

    Short fibres and ultra-high molecular weight polyethylene (UHMWPE) powder were mixed by swirling in a glass jar with compressed nitrogen. It was found that a kind of attraction between the fibres and UHMWPE particles is crucial for making a composite with a proper fibre distribution. If aramid and U

  11. Bio-Based Nanocomposites: An Alternative to Traditional Composites

    Science.gov (United States)

    Tate, Jitendra S.; Akinola, Adekunle T.; Kabakov, Dmitri

    2009-01-01

    Polymer matrix composites (PMC), often referred to as fiber reinforced plastics (FRP), consist of fiber reinforcement (E-glass, S2-glass, aramid, carbon, or natural fibers) and polymer matrix/resin (polyester, vinyl ester, polyurethane, phenolic, and epoxies). Eglass/ polyester and E-glass/vinyl ester composites are extensively used in the marine,…

  12. High-pressure apparatus

    NARCIS (Netherlands)

    Schepdael, van L.J.M.; Bartels, P.V.; Berg, van den R.W.

    1999-01-01

    The invention relates to a high-pressure device (1) having a cylindrical high-pressure vessel (3) and prestressing means in order to exert an axial pressure on the vessel. The vessel (3) can have been formed from a number of layers of composite material, such as glass, carbon or aramide fibers which

  13. 連続繊維ロープの性能評価(第1報)

    OpenAIRE

    関島, 謙蔵||セキジマ, ケンゾウ||Kenzo, Sekijima; 小菅, 拓朗||コスゲ, タクロウ||Takuro, Kosuge; 関, 直哉||セキ, ナオヤ||Naoya, Seki; 出雲, 淳一||イズモ, ジュンイチ||IZUMO, Junichi

    2007-01-01

    Continuous Fiber Rope is made of aramid fiber or vinylon fiber and shaped in the form of rope as reinforcement for concrete members. It is light in weight, and it has a high tensile strength and an excellent durability. It has a good transportability and is flexible to be easily arranged at site.

  14. Mechanical anchorage of FRP tendons – A literature review

    DEFF Research Database (Denmark)

    Schmidt, Jacob W.; Bennitz, Anders; Täljsten, Björn;

    2012-01-01

    anchorage systems for use with Aramid, Glass and Carbon FRP tendons have been proposed over the last two decades. Each system is usually tailored to a particular type of tendon. This paper presents a brief overview of bonded anchorage applications while the primary literature review discusses three methods...

  15. Long term behavior of Arall laminates

    OpenAIRE

    Osiroff, Ricardo

    1988-01-01

    The behavior of ARALL (ARamid ALuminum Laminates) subjected to tensionâ tension cyclic loading was experimentally investigated as a first step towards the understanding of the fatigue damage mechanisms in Arall laminates, and the relationships between damage and stiffness change, remaining strength and life.

  16. Strength Distribution Analysis of Typical Staple Fibers

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The strength of staple fiber is an important property for yarns and fabrics. Usually there are variations in individual fiber strength, and this will affect the final strength of yarns and fabrics. In this study, Weibull distribution function is used to analyze the strength distribution of various staplefibers. The strengths of wool, silk, cotton, flax, acrylic, polyester, glass, aramid and carbon fiber are tested. It isfound that the strengths of cotton, polyester, glass, aramid and carbon fiber fit well with the two-factor Weibulldistribution, while those of wool and silk with the threefactir Weibull distribution. However, the strength distributionof flax cannot be expressed by either two- or three-factor Weibull distribution convincingly.

  17. Development of Textile Laminates for Improved Cut Resistance

    Directory of Open Access Journals (Sweden)

    G. Thilagavathi

    2010-06-01

    Full Text Available Mechanical properties of fibres viz. tensile modulus, tenacity, elongation are the key performance indicators of cut resistance besides yarn and fabric structure. p-aramid and UHDPE (Ultra High Density Polyethylene based high performance fibres are most commonly used for protection against mechanical risks. Specially engineered composite yarns and fabrics would help enhance cut resistance. This paper discusses on the influence textile structure configuration on the performance of cut resistant textiles. A three tier laminate composite was made using knitted Kevlar fabric (p-aramid as outer surface, Polyurethane foam in the middle and a knitted nylon fabric as skin contact layer. This specially engineered laminate showed a 20% increase in cut resistance force when compared with the Kevlar fabric used for lamination. The combination of breathable PU foam and knitted structure of fabric yielded high stretch with improved breathability and dexterity.

  18. Analysis of discontinuities influence on the differences between static and dynamic elastic modulus of composite materials

    Science.gov (United States)

    Sava, Mihaela; Hadǎr, Anton; Pǎrǎuşanu, Ioan; Petrescu, Horia-Alexandru; Baciu, Florin; Marinel, Stǎnescu Marius

    2016-06-01

    The influence of discontinuities is important for a correct determination of static and dynamic elastic characteristics of the material. In this paper we presented differences arising between the elastic modulus static and dynamic, laminated composite materials reinforced with carbon fiber, aramid and carbon-aramid, depending on the non-uniformity coefficient. For the study were determined static elastic modulus by carrying out traction tests and dynamic elastic modulus by determining the vibration frequency, on specimens of each type of material with and without discontinuities [1]. The elastic properties of composite materials resistance and can be influenced by various defects that arise from technological manufacturing process. This is important for the production of large series of parts of fiber-reinforced composite material, the fibers in the matrix distribution is not uniform. Studies on the mechanical behavior of composites with random distribution of fabrics are made in [2].

  19. Modelling poly(p-phenylene teraphthalamide) at Extreme Tensile Loading using Reactive Potentials

    Science.gov (United States)

    Yilmaz, Dundar

    2015-03-01

    Aromatic polyamides classified as rigid-rod polymers due to orientation of their monomers. Because of their excellent mechanical and thermal properties, aramids are widely used in the industry. For example DuPont's brand Kevlar, for its commercial aromatic polyamide polymer, due to wide usage of this polymer in ballistic applications, habitually used as a nickname for bulletproof vests. In order to engineer these ballistic fabrics, material properties of aramid fibers should be studied. In this work we focused on the poly(p-phenylene teraphthalamide) PPTA fiber, known as brand name Kevlar. We employed Reactive potentials to simulate PPTA polymer under tensile loading. We first simulated both amorphous and crystalline phases of PPTA. We also introduced defects with varying densities. We further analysed the recorded atomic positions data to understand how tensile load distributed and failure mechanisms at extreme tensile loads. This work supported by TUBITAK under Grant No: 113F358.

  20. Tensile Properties of Fiber Materials under Different Strain Rates

    Institute of Scientific and Technical Information of China (English)

    XIONG Jie; GU Bo-hong; WANG Shan-yuan

    2002-01-01

    The quasi-static and dynamic tensile tests of aranid and high strength PVA fiber bundles are carried out under a wider range of strain rate by use of MTS (Materials Testing System) and bar-bar tensile impact apparatus.The influences of strain rate on mechanical properties of aramid and high strength polyvinyl alcohol fibers ar estudied. Micro failure mechanisms of fibers at different strain rates are examined by means of SEM.

  1. Analysing the Mechanical Properties of Natural Fiber Reinforced Polymer Composites Using FEA

    OpenAIRE

    A.Dyson Bruno; Baskaran, M

    2014-01-01

    Over the last thirty years composite materials such as polymer, alloys and ceramics have been the dominant emerging materials. The volume and number of applications of Composite materials have grown steadily, penetrating and conquering new markets relentlessly. Polymeric Materials Reinforced with Synthetic Fibers such as glass, carbon, and aramid provide advantages of high stiffness and high strength to weight ratio as compared to conventional materials, i.e. wood, concrete, a...

  2. 連続繊維ロープでせん断補強したRCはりの性能改善効果

    OpenAIRE

    出雲, 淳一||イズモ, ジュンイチ||IZUMO, Junichi; 関島, 謙蔵||セキジマ, ケンゾウ||Kenzo, Sekijima

    2013-01-01

    Continuous Fiber Rope made of Aramid fiber or Vinylon fiber has been developed to apply for the reinforcement of concrete members. It is characterized by a lightweight, a high tensile strength and excellent durability compared with reinforcing steel bar. It has also good transportability, and it is flexible to be easily arranged at a construction site. In this study, in order to investigate the shear reinforcing effect of Continuous Fiber Rope, the reinforced concrete(RC)beams without shear r...

  3. 連続繊維ロープの性能評価(第2報)

    OpenAIRE

    関島, 謙蔵||セキジマ, ケンゾウ||Kenzo, Sekijima; 川上, 清陛||カワカミ, キョウヘイ||KAWAKAMI, Kyouhei; 田丸, 武||タマル, タケシ||Tamaru, Takeshi; 出雲, 淳一||イズモ, ジュンイチ||IZUMO, Junichi

    2008-01-01

    Continuous Fiber Rope is made of aramid fiber or vinylon fiber and shaped in the form of rope as reinforcement for concrete members. It is light in weight, and it has a high tensile strength and an excellent durability. It has a good transportability and is flexible to be easily arranged at site. However, neither Continuous Fiber Rope has been applied to civil engineering structures, nor the evaluating method for this material has been established.

  4. 太径の連続繊維ロープの引張特性

    OpenAIRE

    関島, 謙蔵||セキジマ, ケンゾウ||Kenzo, Sekijima; 川上, 清陛||カワカミ, キョウヘイ||KAWAKAMI, Kyouhei; 鈴木, 翔||スズキ, ショウ||Sho, Suzuki; 藤本, 正巳||フジモト, マサミ||Masami, Fujimoto; 出雲, 淳一||イズモ, ジュンイチ||IZUMO, Junichi

    2009-01-01

    Continuous Fiber Rope is made of Aramid fiber or Vinylon fiber and shaped in the form of rope as reinforcement for concrete members. It is characterized by a lightweight, a high tensile strength and an excellent durability. It has also a good transportability, and it is flexible to be easily arranged at a construction site. However, neither Continuous Fiber Rope has been applied to concrete structures, nor the evaluating method for this material has been established. Before, the tensile prope...

  5. SYNTHESIS AND CHARACTERIZATION OF AN ORDERED LADDER POLYESTER

    Institute of Scientific and Technical Information of China (English)

    Ping-ping Zhang; Tao-yi Zhang; Chuan-feng Zhu; Yu-xia Diao; You-zhi Wan; Ping Xie; Rong-ben Zhang

    2006-01-01

    An ordered ladder polyester (LPE) was first synthesized through the ladder superstructure (LS) constructed by concerted interactions of hydroxyl- and aramide-based H-bonding and p-terphenyl (TP)-based π-stacking by dehydrochlorination condensation using phosgene (COCl2) as coupling agent. LPE was characterized by GPC, FTIR, NMR,XRD, DSC and AFM. Among them, a distinct image of regularly linear alignment corresponding to the ladder main chain of LPE was first revealed by high-resolution AFM.

  6. Non-standard test methods for long-fibrous reinforced composite materials

    OpenAIRE

    L.A. Dobrzański; A. J. Nowak; Błażejewski, W.; R. Rybczyński

    2011-01-01

    Purpose: The investigations serve as comparative verification of silicone-aramid material designed for oesophageal prosthesis.Design/methodology/approach: In this work, non-standard research techniques, particularly designated for comparative tests of long-fibrous composite materials, are presented. Those tests are carried out on equipment similar to so called NOL rings test and pressure tests using rubber as a working mediumFindings: During interpretation of pressure tests results according ...

  7. Study on Mechanical Behavior of Bio-Fiber Reinforced Polymer Matrix Composite

    OpenAIRE

    V.N.Loganathan*; M.Palanisamy; K.Sathish Kumar

    2014-01-01

    Presently polymer matrix composites reinforced with fibers such as glass, carbon, aramid, etc. are being used more because of their favorable mechanical properties in spite of they being more expensive materials. Nowadays natural fibers such as sisal, flax, hemp, jute, coir, bamboo, banana, etc. are widely used for environmental concern on synthetic fibers. This coming generation of engineered bio-composites must provide construction materials and building products that exceed cur...

  8. Ballistic strength of woven fabrics for personal protection

    OpenAIRE

    Dimeski, Dimko; Spaseska, Dijana; Srebrenkoska, Vineta

    2009-01-01

    The purpose of the research was to make evaluation of the ballistic strength of four different fiber/resin composites intended to be used in manufacturing of ballistic items for personal protection. Research has been performed on glass, ballistic nylon, aramid and HPPE (High Performance Polyethylene) plain woven fabrics based composites. As a matrix system, in all cases, polyvinylbutyral modified phenolic resin was used. For the investigation, areal weight range 2-9 kg/m2, appl...

  9. Lignocellulosic Fibers and Nanocellulose as Reinforcing Filler in Thermoplastic Composites

    OpenAIRE

    Ayrilmis, Nadir; Ashori, Alireza

    2014-01-01

    Natural fibers have received considerable attention as a substitute for synthetic fiber reinforcements in thermoplastics. As replacements for conventional synthetic fibers like aramid and glass fibers, natural fibers are increasingly used for reinforcement in thermoplastics due to their low density, good thermal insulation and mechanical properties, reduced tool wear, unlimited availability, low price, and problem-free disposal. Natural fibers also offer economical and environmental advantage...

  10. Performance-Related Specifications for Concrete Bridge Superstructures, Volume 3: Nonmetallic Reinforcement

    OpenAIRE

    Frosch, Robert J.; Mosley, Christopher P.; Tureyen, Ahmet Koray

    2002-01-01

    In Volume 3 of the final report, research work conducted to investigate the behavior of fiber reinforced polymer (FRP) reinforcement is summarized. This study focused on the behavior of FRP reinforced concrete structures with an emphasis on bond and shear. For the bond investigation, three series of beam splice tests were performed on specimens reinforced with steel, glass FRP, and aramid FRP to determine the effect of the different types of reinforcement on bond, cracking, and deflections. T...

  11. The design, construction and in-service performance of the all-composite Aberfeldy footbridge

    OpenAIRE

    Cadei, John; Stratford, Tim

    2002-01-01

    The world’s longest span advanced composite bridge was opened on 3rd October1992. It crosses the River Tay in Scotland, where it connects the two halves of Aberfeldy golf course. The bridge combines a variety of innovative advanced composite technologies, including a pultruded glass-fibre-reinforced-polymer (GFRP) deck and aramid cables.The bridge was fabricated on site with minimal heavy equipment, causing significantly less disruption than a conventional steel or concrete structure, and off...

  12. DOPANT FLEXIBILITY AND PROCESSABILITY STUDIES WITH ELECTRICALLY CONDUCTIVE, FACE-TO-FACE METALLOMACROCYCLIC POLYMERS

    OpenAIRE

    Inabe, T.; Lyding, J.; Moguel, M.; Marks, T.

    1983-01-01

    In doping experiments on the cofacially arrayed phthalocyanine polymer [Si(Pc)O]n using high potential quinone, halogen, or nitrosyl electron acceptors, the achievable degree of partial oxidation, the inhomogeneity of the doping process, and the conductivity mechanism remain remarkably constant. Using wet spinning techniques, it has proven possible to prepare electrically conductive fibers of [Si(Pc)O]n alone or blended with the high performance aramid polymer Kevlar.

  13. Test study on the performance of shielding configuration with stuffed layer under hypervelocity impact

    Science.gov (United States)

    Ke, Fa-wei; Huang, Jie; Wen, Xue-zhong; Ma, Zhao-xia; Liu, Sen

    2016-10-01

    In order to study the cracking and intercepting mechanism of stuffed layer configuration on the debris cloud and to develop stuffed layer configuration with better performance, the hypervelocity impact tests on shielding configurations with stuffed layer were carried out. Firstly, the hypervelocity impact tests on the shielding configuration with stuffed layer of 3 layer ceramic fibre and 3 layer aramid fibre were finished, the study results showed that the debris cloud generated by the aluminum sphere impacting bumper at the velocity of about 6.2 km/s would be racked and intercepted by the stuffed layer configuration efficiently when the ceramic fibre layers and aramid fibre layers were jointed together, however, the shielding performance would be declined when the ceramic fibre layers and aramid fibre layers were divided by some distance. The mechanism of stuffed layer racking and intercepting the debris cloud was analyzed according to the above test results. Secondly, based on the mechanism of the stuffed layer cracking and intercepint debirs cloud the hypervelocity impact tests on the following three stuffed layer structures with the equivalent areal density to the 1 mm-thick aluminum plate were also carried out to compare their performance of cracking and intercepting debris cloud. The mechanisms of stuffed layer racking and intercepting the debris cloud were validated by the test result. Thirdly, the influence of the stuffed layer position on the shielding performance was studied by the test, too. The test results would provide reference for the design of better performance shielding configuration with stuffed layer.

  14. Porous texture evolution in Nomex-derived activated carbon fibers.

    Science.gov (United States)

    Villar-Rodil, S; Denoyel, R; Rouquerol, J; Martínez-Alonso, A; Tascón, J M D

    2002-08-01

    In the present work, the textural evolution of a series of activated carbon fibers with increasing burn-off degree, prepared by the pyrolysis and steam activation of Nomex aramid fibers, is followed by measurements of physical adsorption of N(2) (77 K) and CO(2) (273 K) and immersion calorimetry into different liquids (dichloromethane, benzene, cyclohexane). The immersion calorimetry results are discussed in depth, paying special attention to the choice of the reference material. The activated carbon fibers studied possess an essentially homogeneous microporous texture, which suggests that these materials may be applied in gas separation, either directly or with additional CVD treatment. PMID:16290775

  15. Carbon Nanostructures for Electromagnetic Shielding and Lightning Strike Protection Applications in Aircraft

    Science.gov (United States)

    Shah, T.; Jones, M.; Alberding, M.; Laszewski, M.

    2012-05-01

    Applied NanoStructured Solutions, LLC (ANS) has developed a unique Chemical Vapor Deposition (CVD) process for the growth of Carbon Nanotubes (CNT) onto various fiber substrates including carbon, glass, ceramics and aramids. This process is continuous and operates at atmospheric pressures enabling high volume/low cost manufacturing. This process infuses conductive CNTs in a highly entangled form referred to as Carbon Nanostructures (CNS) onto the surface of the normally insulative fiber making it highly conductive overall. Composites made from this CNS-infused filler then have unique Electromagnetic Interference (EMI) shielding and Lightening Strike Protection (LSP) properties.

  16. Chemical resistance of valve packing and sealing materials to molten nitrate salt

    International Nuclear Information System (INIS)

    Chemical compatibility between a number of compression packings and sealing materials and molten sodium nitrate-potassium nitrate was evaluated at temperatures of 2880C (5500F), 4000C (7500F), and 5650C (10500F). The types of packing materials tested included graphite, asbestos, PTFE, aramid, glass and ceramic fibers; perfluoroelastomers, and boron nitride. Several materials were chemically resistant to the molten salt at 2880C, but the compatibility of packings at 4000C and 5650C was not adequate. The chemical and physical phenomena affecting compatibility are discussed and recommendations concerning materials selection are made

  17. The Present Situation and Development Trend of Japan Chemical Fiber Industry%日本化纤业的现状和发展方向

    Institute of Scientific and Technical Information of China (English)

    刘辅庭

    2012-01-01

    The present situation and development trend of Japan chemical fiber industry is reviewed. The development of functional fiber and high performance fiber especilly aramid fiber, carbon fiber and reinforced composite fiber, etc, is introduced.%综述了日本化纤业的发展现状及发展方向,对其主要发展的功能性纤维材料、高性能纤维材料,特别是芳香族聚酰胺纤维、碳纤维增强复合材料等进行了介绍.

  18. Feasibility of Kevlar 49/PMR-15 polyimide for high temperature applications

    Science.gov (United States)

    Hanson, M. P.

    1980-01-01

    Kevlar 49 aramid organic fiber reinforced PMR-15 polyimide laminates were characterized to determine the applicability of the material to high temperature aerospace structures. Kevlar 49/3501-6 epoxy laminates were fabricated and characterized for comparison with the Kevlar 49/PMR-15 polyimide material. Flexural strengths and moduli and interlaminar shear strengths were determined from 75 to 600 F for the PMR-15 and from 75 to 450 F for the Kevlar 49/3501-6 epoxy material. The study also included the effects of hydrothermal and long-term elevated temperature exposures on the flexural strengths and moduli and the interlaminar shear strengths.

  19. 高强轻质的开夫拉(Kevlar)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ 开夫拉(Kevler),实际上是众所周知的HMA(High Modular Aramid,高模芳香尼龙),以极高的成纤强度著称,"Kevlar"为商品名,因杜邦公司最早批量生产这种纤维而使"Kevlar"声名远扬,甚至成为高强尼龙的代名词.因其超高的强力和较轻的比重,开夫拉纤维被优先应用于军用防弹防刺服及航空材料当中.

  20. 連続繊維ロープとコンクリートとの付着特性

    OpenAIRE

    関島, 謙蔵||セキジマ, ケンゾウ||Kenzo, Sekijima; 出雲, 淳一||イズモ, ジュンイチ||IZUMO, Junichi

    2011-01-01

    Continuous Fiber Rope is made of Aramid fiber or Vinylon fiber and shaped in the form of rope as reinforcement for concrete members.It is characterized by a lightweight,a high tensile strength and an excellent durability compared with steel reinforcing bar.It has also a good transportability,and it is flexible to be easily arranged at a construction site.The authors have already investigated not only the tensile properties of Continuous Fiber Rope but also the capacities of some kinds of spli...

  1. 太径の連続繊維ロープの接続方法

    OpenAIRE

    関島, 謙蔵||セキジマ, ケンゾウ||Kenzo, Sekijima; 川上, 清陛||カワカミ, キョウヘイ||KAWAKAMI, Kyouhei; 小原, 真澄||オバラ, マスミ||OBARA, Masumi; 柴田, 将吾||シバタ, ショウゴ||SHIBATA, Shogo; 出雲, 淳一||イズモ, ジュンイチ||IZUMO, Junichi

    2010-01-01

    Continuous Fiber Rope is made of Aramid fiber or Vinylon fiber and shaped in the form of rope as reinforcement for concrete members.It is characterized by a lightweight,a high tensile strength and an excellent durability.It has also a good transportability,and it is flexible to be easily arranged at a construction site.When the length of Continuous Fiber Rope is short at a construction site,the splice will become necessary.Before,some kinds of splice of Continuous Fiber Rope with a small diam...

  2. FIRE PROTECTION OF TIMBER STRUCTURES STRENGTHENED WITH FRP MATERIALS

    Directory of Open Access Journals (Sweden)

    Radek Zigler

    2015-12-01

    Full Text Available Modern, progressive methods of structures’ strengthening based on the use of composite materials composed of high strength fibers (carbon, glass, aramid or basalt and matrices based on epoxy resins brings, among many indisputable advantages (low weight, high effectiveness, easy application etc. also some disadvantages. One of the major disadvantages is a low fire resistance of these materials due to the low glass transition temperature Tg of the resin used. Based on an extensive research of strengthening of historic structures with FRP materials [1], the article outlines possible approaches to this problem, especially while strengthening timber load- bearing structures of historic buildings.

  3. Hybrid Three-Dimensional (3-D) Woven Thick Composite Architectures in Bending

    Science.gov (United States)

    Pankow, Mark; Quabili, Ashiq; Yen, Chian-Fong

    2013-11-01

    In this study, three 3-dimensional (3-D) woven composite materials were examined to determine how yarn tow configurations affect the flexural response of the structure. Woven fabric preforms were manufactured with a Z-fiber architecture in 2-3 in. thicknesses. These preforms contained S-2 Glass (AGY, Aiken, SC, USA), carbon, and Twaron (Teijin Aramid, Arnhem, The Netherlands) yarns in different architectures creating a hybrid material system. Due to the thickness of the material, these samples required a significant span length (30 in.). The results showed a change in the strength and degradation after failure with the addition of carbon layers in tension.

  4. Evaluation of high temperature capacitor dielectrics

    Science.gov (United States)

    Hammoud, Ahmad N.; Myers, Ira T.

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  5. The effect of particle addition and fibrous reinforcement on epoxy-matrix composites for severe sliding conditions

    DEFF Research Database (Denmark)

    Larsen, Thomas Ricco Ølholm; Løgstrup Andersen, Tom; Thorning, Bent;

    2008-01-01

    This paper reports production and tribological testing of epoxy-matrix composites for dry-sliding conditions. The examined composites are produced using the following components: epoxy resin (EP), glass fiber weave (G), carbon/aramid hybrid weave (CA), PTFE particles and nano-scale CuO particles...... are seen when the fibers are parallel and anti-parallel (P-AP) to the sliding direction compared to normal and parallel (N-P). Experiments with incorporating micro-scale PTFE particles and nano-scale CuO particles, respectively, into the epoxy resin along with the carbon/aramid weave shows no difference...... in friction but minor improvements in wear. When micro-scale PTFE particles are incorporated into the neat epoxy resin, i.e. without fibers, an increase in and a decrease in A are measured. When the same is done with nano-CuO a deterioration of both friction and wear properties are seen. At the three roughest...

  6. Fragmentation of hypervelocity aluminum projectiles on fabrics

    Science.gov (United States)

    Rudolph, Martin; Schäfer, Frank; Destefanis, Roberto; Faraud, Moreno; Lambert, Michel

    2012-07-01

    This paper presents work performed for a study investigating the ability of different flexible materials to induce fragmentation of a hypervelocity projectile. Samples were chosen to represent a wide range of industrially available types of flexible materials like ceramic, aramid and carbon fabrics as well as a thin metallic mesh. Impact conditions and areal density were kept constant for all targets. Betacloth and multi-layer insulation (B-MLI) are mounted onto the targets to account for thermal system engineering requirements. All tests were performed using the Space light-gas gun facility (SLGG) of the Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI. Projectiles were aluminum spheres with 5 mm diameter impacting at approximately 6.3 km/s. Fragmentation was evaluated using a witness plate behind the target. An aramid and a ceramic fabric lead the ranking of fabrics with the best projectile fragmentation and debris cloud dispersion performance. A comparison with an equal-density rigid aluminum plate is presented. The work presented can be applied to optimize the micrometeoroid and space debris (MM/SD) shielding structure of inflatable modules.

  7. The cryogenic bonding evaluation at the metallic-composite interface of a composite overwrapped pressure vessel with additional impact investigation

    Science.gov (United States)

    Clark, Eric A.

    A bonding evaluation that investigated the cryogenic tensile strength of several different adhesives/resins was performed. The test materials consisted of 606 aluminum test pieces adhered to a wet-wound graphite laminate in order to simulate the bond created at the liner-composite interface of an aluminum-lined composite overwrapped pressure vessel. It was found that for cryogenic applications, a flexible, low modulus resin system must be used. Additionally, the samples prepared with a thin layer of cured resin -- or prebond -- performed significantly better than those without. It was found that it is critical that the prebond surface must have sufficient surface roughness prior to the bonding application. Also, the aluminum test pieces that were prepared using a surface etchant slightly outperformed those that were prepared with a grit blast surface finish and performed significantly better than those that had been scored using sand paper to achieve the desired surface finish. An additional impact investigation studied the post impact tensile strength of composite rings in a cryogenic environment. The composite rings were filament wound with several combinations of graphite and aramid fibers and were prepared with different resin systems. The rings were subjected to varying levels of Charpy impact damage and then pulled to failure in tension. It was found that the addition of elastic aramid fibers with the carbon fibers mitigates the overall impact damage and drastically improves the post-impact strength of the structure in a cryogenic environment.

  8. A new experimental setup to characterize the dynamic mechanical behaviour of ballistic yarns

    Science.gov (United States)

    Chevalier, C.; Kerisit, C.; Boussu, F.; Coutellier, D.; Faderl, N.; Klavzar, A.

    2016-10-01

    Fabrics have been widely used as part of ballistic protections since the 1970s and the development of new ballistic solutions made from fabrics need numerical simulations, in order to predict the performance of the ballistic protection. The performances and the induced mechanisms in ballistic fabrics during an impact depend on the weaving parameters and also on the inner parameters of the yarns used inside these structures. Thus, knowing the dynamic behaviour of yarn is essential to determine the ballistic behaviour of fabrics during an impact. Two major experimental devices exist and are used to test ballistic yarns in a dynamic uniaxial tension. The first one corresponds to the Split Hopkinson Tensile Bars device, which is commonly used to characterize the mechanical properties of materials in uniaxial tension and under high loading. The second one is the transversal impact device. The real conditions of ballistic impact can be realized with this device. Then, this paper deals with a new experimental setup developed in our laboratory and called the ‘tensile impact test for yarn’ (TITY) device. With this device, specific absorbed energy measurements of para-aramid yarns (336 Tex, Twaron™, 1000 filaments) have been carried out and revealed that static and dynamic properties of para-aramid are different.

  9. The stress-strain relationships in wood and fiber-reinforced plastic laminae of reinforced glued-laminated wood beams

    Science.gov (United States)

    Tingley, Daniel Arthur

    The reinforcement of wood and wood composite structural products to improve their mechanical properties has been in practice for many years. Recently, the use of high-strength fiber-reinforced plastic (FRP) as a reinforcement in such applications has been commercialized. The reinforcement is manufactured using a standard pultrusion process or alternatively a sheet-forming process commonly referred to as "pulforming". The high-modulus fibers are predominately unidirectional, although off-axis fibers are often used to enhance off-axis properties. The fibers used are either of a single type or multiple types, which are called "hybrids". Unidirectional, single, and hybrid fiber FRP physical properties and characteristics were compared to wood. Full-scale reinforced glulams were tested. Aramid-reinforced plastics (ARP) used as tensile reinforcements were found to be superior in strength applications to other types of FRP made with fiber, such as carbon and fiberglass. Carbon/aramid-reinforced plastic (CARP) was shown to be superior in both modulus and strength design situations. Fiberglass was shown to be suitable only in hybrid situations with another fiber such as aramid or carbon and only in limited use situations where modulus was a design criteria. The testing and analysis showed that the global response of reinforced glulam beams is controlled by localized strength variations in the wood such as slope of grain, knots, finger joints, etc. in the tensile zone. The elemental tensile strains in the extreme wood tensile laminae, due to global applied loads, were found to be well below the strain at failure in clear wood samples recovered from the failure area. Two areas affecting the relationship between the wood and the FRP were investigated: compatibility of the wood and FRP materials and interface characteristics between the wood and FRP. The optimum strain value at yield point for an FRP was assessed to be slightly higher than the clear wood value in tension for a

  10. Toughening of phenolic foam

    Science.gov (United States)

    Shen, Hongbin

    2003-06-01

    Phenolic foam has excellent FST performance with relatively low cost, and thus is an attractive material for many applications. However, it is extremely brittle and fragile, precluding it from load-bearing applications. In order to make it tougher and more viable for structural purposes, an effective approach has been proposed and investigated in this study. Composite phenolic foam with short fiber reinforcements resulted in significant improvement in mechanical performance while retaining FST properties comparable to conventional phenolic foam. For example, composite phenolic foam with aramid fibers exhibited a seven-fold increase in peel resistance together with a five-fold reduction in friability. In shear tests, aramid composite foam endured prolonged loading to high levels of strain, indicating the potential for use in structural applications. On the other hand, glass fiber-reinforced phenolic foam produced substantial improvement in the stiffness and strength relative to the unreinforced counterpart. In particular, the Young's modulus of the glass fiber composite foam was increased by as much as 100% relative to the plain phenolic foam in the foam rise direction. In addition, different mechanical behavior was observed for aramid and glass fiber-reinforced foams. In an attempt to understand the mechanical behavior of composite foam, a novel NDT technique, micro-CT, was used to acquire information on fiber length distribution (FLD) and fiber orientation distribution (FOD). Results from micro-CT measurements were compared with theoretical distribution models, achieving various degrees of agreement. Despite some limitations of current micro-CT technology, the realistic observation and measurement of cellular morphology and fiber distribution within composite foams portend future advances in modeling of reinforced polymer foam. To explain the discrepancy observed in shear stiffness between traditional shear test results and those by the short sandwich beam test, a

  11. Fiber reinforced hybrid phenolic foam

    Science.gov (United States)

    Desai, Amit

    Hybrid composites in recent times have been developed by using more than one type of fiber reinforcement to bestow synergistic properties of the chosen filler and matrix and also facilitating the design of materials with specific properties matched to end use. However, the studies for hybrid foams have been very limited because of problems related to fiber dispersion in matrix, non uniform mixing due to presence of more than one filler and partially cured foams. An effective approach to synthesize hybrid phenolic foam has been proposed and investigated here. Hybrid composite phenolic foams were reinforced with chopped glass and aramid fibers in varied proportions. On assessing mechanical properties in compression and shear several interesting facts surfaced but overall hybrid phenolic foams exhibited a more graceful failure, greater resistance to cracking and were significantly stiffer and stronger than foams with only glass and aramid fibers. The optimum fiber ratio for the reinforced hybrid phenolic foam system was found to be 1:1 ratio of glass to aramid fibers. Also, the properties of hybrid foam were found to deviate from rule of mixture (ROM) and thus the existing theories of fiber reinforcement fell short in explaining their complex behavior. In an attempt to describe and predict mechanical behavior of hybrid foams a statistical design tool using analysis of variance technique was employed. The utilization of a statistical model for predicting foam properties was found to be an appropriate tool that affords a global perspective of the influence of process variables such as fiber weight fraction, fiber length etc. on foam properties (elastic modulus and strength). Similar approach could be extended to study other fiber composite foam systems such as polyurethane, epoxy etc. and doing so will reduce the number of experimental iterations needed to optimize foam properties and identify critical process variables. Diffusivity, accelerated aging and flammability

  12. Heating of thermoplastic-based unidirectional composite prepregs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.; Weber, M.E.; Charrier, J.M. (McGill Univ., Montreal (Canada))

    1989-04-01

    Thermoplastic-based prepregs offer a potential for faster manufacture of composite products than with thermoset-based prepregs. The winding or controlled placement of thermoplastic-based prepreg tapes requires the rapid heating of the moving tape, just prior to its contact with the substrate on the mandrel. In the case of complex shapes, geometrical constraints and significant variations in tape speeds in the course of manufacture, make it particularly desirable to be able to model the heating process. A mathematical model and its experimental verification for convection/conduction heat transfer to and through either a homogeneous thermoplastic material, or thermoplastic-based unidirectional composites featuring glass, aramid and carbon fibers, is discussed. 12 refs.

  13. Standard practice for infrared flash thermography of composite panels and repair patches used in aerospace applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This practice describes a procedure for detecting subsurface flaws in composite panels and repair patches using Flash Thermography (FT), in which an infrared (IR) camera is used to detect anomalous cooling behavior of a sample surface after it has been heated with a spatially uniform light pulse from a flash lamp array. 1.2 This practice describes established FT test methods that are currently used by industry, and have demonstrated utility in quality assurance of composite structures during post-manufacturing and in-service examinations. 1.3 This practice has utility for testing of polymer composite panels and repair patches containing, but not limited to, bismaleimide, epoxy, phenolic, poly(amide imide), polybenzimidazole, polyester (thermosetting and thermoplastic), poly(ether ether ketone), poly(ether imide), polyimide (thermosetting and thermoplastic), poly(phenylene sulfide), or polysulfone matrices; and alumina, aramid, boron, carbon, glass, quartz, or silicon carbide fibers. Typical as-fabricate...

  14. Reinforcing materials in conveyor belts: their requirements and developments; Verstaerkungsmaterialien in Foerdergurten: Tendenzen, Anforderungen und Entwicklungen

    Energy Technology Data Exchange (ETDEWEB)

    Kopmels, P. [Akzo Nobel Fibers, Arnhem (Netherlands)

    1994-12-31

    During this century one can observe a gradual change in the textile materials used to reinforce conveyor belt. In the beginning of the 20th century only cotton was used, then rayon came up followed by polyamide and polyester. Nowadays aramid is also used for special applications. These changes in textile reinforcing materials were driven by a better fulfilment of the existing technical requirements and/or a better price/performance ratio. In addition to the search for new polymers, the fiber producers try to improve the yarn properties of existing polymers. An example of a newly developed polyester type is presented. By raising the yarn strength and at the same time improving the efficiency of the yarn in respect to the necessary converting steps like twisting, weaving and dipping the price/performance ratio of this new yarn type has been greatly improved. 11 figs.

  15. Cutting of fiber reinforced polymers with a CW CO-2 laser: An experimental study

    Science.gov (United States)

    Flaum, M.

    1984-01-01

    A 250 W CO2 CW laser cutter auxiliary equipment, especially the gas nozzle with novel features for the protection gas (air, nitrogen, argon, helium, or carbon dioxide) are described. Cutting results, e.g., the dependance of maximum cutting speed on different parameters, are reported. A simple thermic model is given for the description of the influence of anisotropy. A method for cut quality diagnosis is outlined and preliminary tests presented. Good cutting results are noted for aramid fibers/epoxy and glass fibers/epoxy composites while boron fibers/epoxy and carbon fibers/epoxy were hard to process. As protection gas, carbon dioxide is preferable for glass fibers, and helium for boron fibers.

  16. 2nd International Conference on Historic Earthquake-Resistant Timber Frames in the Mediterranean Area

    CERN Document Server

    Machado, José; Costa, Alfredo; Candeias, Paulo; Ruggieri, Nicola; Catarino, José

    2016-01-01

    This book presents a selection of the best papers from the HEaRT 2015 conference, held in Lisbon, Portugal, which provided a valuable forum for engineers and architects, researchers and educators to exchange views and findings concerning the technological history, construction features and seismic behavior of historical timber-framed walls in the Mediterranean countries. The topics covered are wide ranging and include historical aspects and examples of the use of timber-framed construction systems in response to earthquakes, such as the gaiola system in Portugal and the Bourbon system in southern Italy; interpretation of the response of timber-framed walls to seismic actions based on calculations and experimental tests; assessment of the effectiveness of repair and strengthening techniques, e.g., using aramid fiber wires or sheets; and modelling analyses. In addition, on the basis of case studies, a methodology is presented that is applicable to diagnosis, strengthening and improvement of seismic performance ...

  17. SHPB横向冲击法研究AF/ZF混杂纤维复合材料吸能特性%ENERGY ABSORPTION CHARACTERISTICS OF AF/ZF HYBRID COMPOSITE UNDER SHPB TRANSVERSE IMPACT

    Institute of Scientific and Technical Information of China (English)

    孙志杰; 龚元明; 贺成红; 张佐光

    2005-01-01

    采用SHPB冲击试验装置,对AF/ZF(Aramid Fiber/Zylon Fiber)混杂纤维防弹复合材料进行了横向冲击试验,获得了不同混杂比的混杂复合材料的载荷历史与位移历史,进一步分析了其破坏过程和能量吸收特性.所得结果与不同混杂比的AF/ZF混杂纤维复合材料实弹靶试吸能特性变化趋势相似.结果表明,进行不同混杂比AF/ZF混杂纤维复合材料的横向冲击试验对预测实弹冲击的破坏吸能有参考价值.

  18. High Performance Fibers for Nonwoven and Technical Textiles Industries%非织造和产业用高性能纤维

    Institute of Scientific and Technical Information of China (English)

    金立国

    2013-01-01

    The development situation of carbon fiber(CF), aramid(AR) fiber, poly-p-phenylene benzobisoxa-zole (PBO) fiber, ultra-high molecular weight polyethylene (UHMWPE) fiber, polyphenylene sulfide(PPS) fiber, polyimide(PI) fiber, basalt fiber (BF) and polysulfonamide(PSA) fiber at home and abroad and their applications in the industries are introduced.%介绍了碳纤维、芳纶、聚对苯撑苯并双噁唑(PBO)纤维、超高相对分子质量聚乙烯(UHMWPE)纤维、聚苯硫醚(PPS)纤维、聚酰亚胺(PI)纤维、玄武岩纤维、芳砜纶的国内外发展概况及其在产业领域的应用.

  19. Moisture dependence of positron lifetime in Kevlar-49

    Science.gov (United States)

    Singh, Jag J.; Holt, William H.; Mock, Willis, Jr.

    1984-01-01

    Because of filamentary character of Kevlar-49 aramid fibers, there is some concern about the moisture uptake and its effect on plastic composites reinforced with Kevlar-49 fibers. As part of continuing studies of positron lifetime in polymers, we have measured positron lifetime spectra in Kevlar-49 fibers as a function of their moisture content. The long lifetime component intensities are rather low, being only of the order of 2-3 percent. The measured values of long component lifetimes at various moisture levels in the specimens are as follows: 2072 +/- 173 ps (dry); 2013 +/- 193 ps (20.7 percent saturation); 1665 +/- 85 ps (25.7 percent saturation); 1745 +/- 257 ps (32.1 percent saturation); and 1772 +/- 217 ps (100 percent saturation). It is apparent that the long component lifetime at first decreases and then increases as the specimen moisture content increases. These results have been compared with those inferred from Epon-815 and Epon-815/K-49 composite data.

  20. H.Ea.R.T. 2013 Conference

    CERN Document Server

    Tampone, Gennaro; Zinno, Raffaele; Historical Earthquake-Resistant Timber Frames in the Mediterranean Area

    2015-01-01

    This book presents a selection of the best papers from the HEaRT 2013 conference, held in Cosenza, Italy, which provided a valuable forum for engineers and architects, researchers, and educators to exchange views and findings concerning the technological history, construction features, and seismic behavior of historical timber-framed walls in the Mediterranean countries. The topics covered are wide ranging and include historical aspects and examples of the use of timber-framed construction systems in response to earthquakes, such as the gaiola system in Portugal and the Bourbon system in southern Italy; interpretation of the response of timber-framed walls to seismic actions based on calculations and experimental tests; assessment of the effectiveness of repair and strengthening techniques, e.g., using aramid fiber wires or sheets; and modelling analyses. In addition, on the basis of case studies, a methodology is presented that is applicable to diagnosis, strengthening, and improvement of seismic performance...

  1. Impact and residual fatigue behavior of ARALL and AS6/5245 composite material

    Science.gov (United States)

    Johnson, W. S.

    1989-01-01

    The impact sensitivity of aramide fiber-reinforced aluminum laminates (ARALL) was investigated by testing two types of ARALL (7075 aluminum prestrained and 2024 aluminum not prestrained), via static indentation, and the results were compared to those of sheet aluminum alloys 7075-T6 and 2024-T3 and to a state of the art composite AS6/5245. It was found that the impact resistance of the two ARALL samples was inferior to that of monolithic sheet aluminum samples, although the ARALL material made with 2024-T3 aluminum was superior to that made with 7075-T6 aluminum. The impact damage resistance of ARALL materials was at least equal to that of AS6/5245, and the AS6/5245 had higher residual tension-tension fatigue strength after impact than the ARALL samples. It was also found that the prestraining of the ARALL reduced the fatigue growth of impact damage.

  2. Performance of adhesives base on PU, Epoxy and silane in the Kevlar/alumina interface; Desempenho de adesivos a base de PU, epoxi e silano na interface Kevlar/alumina

    Energy Technology Data Exchange (ETDEWEB)

    Noronha, K.F.; Melo, F.C.L.; Lopes, C.M.A. [Divisao de Materiais, Instituto de Aeronautica e Espaco (IAE), Sao Jose dos Campos, SP (Brazil); Divisao de Engenharia Mecanica-Aeronautica, Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil)], e-mail: cmoniz@iae.cta.br

    2010-07-01

    Hybrid ceramic/polymer composites are used for ballistic protection due to the good high-velocity impact absorption properties. The choice of the proper adhesive used to bond ceramic and polymer layers is one of the major issues for hybrid armor development due to its influence in the ballistic resistance behaviour. This work presents an adhesion study in composites of aramid textile (Kevlar) and alumina. Adhesives of different chemical nature, based on polyurethane, epoxy and silane were evaluated. T-Peel test was performed for the interface characterization and the post- failure surfaces were examined by optical microscopy. In all samples the failure occurred at the interface. The silane-based adhesive showed no interaction with the polymer, while the PU hot melt adhesive presented the highest adhesion strengths. (author)

  3. Terahertz imaging of composite materials in reflection and transmission mode with a time-domain spectroscopy system

    Science.gov (United States)

    Sørgârd, Trygve R.; van Rheenen, Arthur D.; Haakestad, Magnus W.

    2016-02-01

    A fiber-coupled Terahertz time domain spectroscopy (THz-TDS) system based on photoconductive antennas, pumped by a 100-fs fiber laser, has been used to characterize materials in transmission and reflection mode. THz images are acquired by mounting the samples under investigation on an x-y stage, which is stepped through the beam while the transmitted or reflected THz waveform is captured. The samples include a carbon fiber epoxy composite and a sandwich-structured composite panel with an aramid fiber honeycomb core in between two skin layers of fiberglass reinforced plastic. The former has an artificially induced void, and from a comparison of recorded reflected time-domain signals, with and without the void, a simple model for the structure of the composite is proposed that describes the time-domain signals reasonably well.

  4. Bioassay of thermal protection afforded by candidate flight suit fabrics.

    Science.gov (United States)

    Knox, F S; Wachtel, T L; McCahan, G R

    1979-10-01

    The United States Army Aeromedical Research Laboratory (USAARL) porcine cutaneous bioassay technique was used to determine what mitigating effect four thermally protective flight suit fabrics would have on fire-induced skin damage. The fabrics were 4.8-ox twill weave Nomex aramide, 4.5-oz stabilized twill weave polybenzimidazole, 4.8-oz plain weave experimental high-temperature polymer (HT4), and 4.8-oz plain weave Nomex aramide (New Weave Nomex or NWN). Each fabric sample was assayed 20 times in each of four configurations: as a single layer in contact with the skin; as a single layer with a 6.35 mm (0.25 in) air gap between fabric and skin; in conjuction with a cotton T-shirt with no air gaps; and, finally, in conjuction with a T-shirt with a 6.35 mm air gap between T-shirt and fabric. Bare skin was used as a control. A JP-4 fueled furnace was used as a thermal source and was adjested to deliver a mean heat flux of 3.07 cal/cm2/s. The duration of exposure was 5 s. Four hundred burn sites were graded using clinical observation and microscopic techniques. Used as single layers, none of the fabrics demonstrated superiority in providing clinically significant protection. When used with a cotton T-shirt, protection was improved. Protection improved progressively for all fabrics and configuration when an air gap was introduced. The experimental high-temperature polymer consistently demonstrated lower heat flux transmission in all configurations, but did not significantly reduce clinical burns. PMID:518445

  5. Identification of composite materials at high speed deformation with the use of degenerated model

    Directory of Open Access Journals (Sweden)

    K. Jamroziak

    2008-06-01

    Full Text Available Purpose: Composite materials on account of some their characteristics have application in a construction of ballistic shield. An example of the ballistic shield is laminate with the mix-structure materials such as layer pressed of aramid cloths on matrix polymer. Because of the shield’s assignment the aramid cloths are exposed to impact loads caused by an energy made by impact force of cumulated mass (bullet. Previous analyses of the effect are based on linear-elastic reaction of resisting forces between the materials of a bullet and a shield. The article exemplifies the procedure of mechanical properties analysis in the punch effect of the ballistic shield with the use of some of the non-elastic models.Design/methodology/approach: In the article the theoretical analysis of punch effect in the quasi-static load condition based on some of the degenerated models is also presented.Findings: The results of the analysis make aware of demand for designing safety ballistic shields.Research limitations/implications: The main conception was optimum material selection (composite that has to be done according to the theoretical analysis, which is based on non-elastic models selected in the context of velocity and mass of punching bullet.Practical implications: Application of the complex degenerated model allows to define more characteristics of the punching process of the ballistic shield. Determination of the effect of energy impact dissipation causes material damage of the ballistic shield is enabled to do because of implementation of boundary conditions.Originality/value: Based on the boundary conditions of energy in the way of changing parameters of model we are able to describe non-destructive deformation process.

  6. Thermal diffusivity measurements of selected fiber reinforced polymer composites using heat pulse method

    Directory of Open Access Journals (Sweden)

    G. Wróbel a, S. Pawlak a, *, G. Muzia

    2011-03-01

    Full Text Available Purpose: The objective of this paper was to examine the effect of fiber content on the thermal diffusivity in selected fiber reinforced polymer composites. The influence of fiber type on the thermal diffusivity was also considered and discussed.Design/methodology/approach: The experiments have been performed using a heat pulse method for the thermal diffusivity measurements of engineering materials. For the purpose of the present study, two different types of composite materials with glass or aramid fiber and with different fiber content were prepared.Findings: For the GFRP composites, the obtained results indicate that the higher is glass fiber content the higher is the thermal diffusivity value. These results shows a linear relationship between fiber content and thermal diffusivity. In the case of KFRP composites, the thermal diffusivity decreases marginally with an increase of fiber content.Research limitations/implications: Due to the relatively high thickness of investigated specimens, in comparison with standard specimens for thermal diffusivity measurements, the obtained values of thermal diffusivity are affected by several factors, e.g. heat losses or temperature-dependent thermo-physical properties. This indicates that the real quantity determined in the present study, was, so-called, apparent thermal diffusivity.Practical implications: The method applied in this work allows to obtain quantitative results, which would be satisfactory to industrial or laboratory applications in the field of non-destructive testing of composite materials.Originality/value: The method initially proposed by Parker et al. in 1961 for the thermal diffusivity measurements of homogeneous solids was successfully applied to determine the thermal diffusivity of non-homogeneous glass and aramid fiber reinforced polymer composites

  7. Etude de l'isolation hybride en vue de son application dans les transformateurs de puissance

    Science.gov (United States)

    Kassi, Koutoua Simon

    For nearly a century the conventional insulation (oil / cellulose complex) was the type of insulation used in the power transformers and most electrical power equipments. But the cellulose paper, the solid part of this insulation has many weaknesses. Indeed, the aging of cellulose paper in power transformers is accelerated by moisture, oxygen, metal catalysts, temperature, etc.). The risk of failures is thereby increased. Another major weakness of cellulose paper is its inability to protect the electrical transformer windings against the harmful effects of corrosive sulfur. Given all the weaknesses of cellulose paper, several studies have been conducted to evaluate the performance of aramid paper, which has better thermal properties. The aramid paper is currently used as high temperature insulation, combined with high fire point oils (synthetic and vegetable oils), mainly in electric traction transformers. The hybrid solid insulation is associated with mineral oil or with high fire point oils; it finds application in transformers of fixed and mobile substations. Manufacturing technology is controlled by manufacturers but operators of electrical networks do not have baseline data (standards) as diagnostic tools, allowing them to monitor the health/condition of the isolation in this new type of transformer. The overall objective of this research was to study the hybrid insulation and to demonstrate its potential use in power transformers. This overall objective has been subdivided into three specific objectives, namely: (i) improving the diagnostic of the condition of solid hybrid insulation and conventional solid insulation; (ii) diagnosing the condition of oils sampled from hybrid, high temperature and conventional insulation and finally (iii) investigating the ability of aramid paper and cellulose paper to protect the copper (electrical windings) against harmful effects of corrosive sulfur. In order to achieve these objectives, thermal accelerated aging were

  8. Etude sur les tendons en materiaux composites et leur application aux ancrages postcontraints

    Science.gov (United States)

    Chennouf, Adil

    L'objectif general de la presente these est d'evaluer le comportement a l'arrachement et au fluage d'ancrages injectes constitues de tendons en materiaux composites afin d'etablir des recommandations plus appropriees et realistes pour le dimensionnement et la conception. Quatre types de tendons en materiaux composites, deux a base de fibres d'aramide et deux a base de fibres de carbone, ont ete utilises dans l'etude. Les travaux de recherche de cette these ont porte notamment sur: (I) Une caracterisation physique et mecanique des tendons en materiaux composites utilises dans l'etude. (II) Une etude en laboratoire sur les coulis de scellement. La premiere etape de cette etude a concerne le developpement d'un coulis de scellement performant adapte aux tendons en materiaux composites et a differentes situations d'injection. La seconde etape a traite des essais de caracterisations physique et mecanique du coulis de scellement developpe comparativement a trois coulis de scellement usuels d'un meme rapport E/L de 0,4. (III) Une etude sur des modeles reduits d'ancrages injectes. (IV) Une etude sur des modeles d'ancrages a grande echelle. La synthese de ces etudes a permis d'enoncer les principales conclusions suivantes: (1) Les valeurs moyennes des charges de rupture des tendons en materiaux composites ont ete de 1% a 29% superieures a celles specifiees par les manufacturiers. (2) L'etude sur les coulis de scellement a permis le developpement de coulis de ciment repondant aux criteres fixes, soient une grande stabilite, une bonne fluidite, une legere expansion et de bonnes caracteristiques mecaniques. (3) Les tendons en materiaux composites ont montre des contraintes d'adherence maximum superieures a celles des tendons en acier. (4) Le type de fibre, la configuration et le fini de surface des tendons en materiaux composites gouvernent leur resistance a l'adherence. (5) L'introduction de sable et d'autres ajouts comme les fines de silice et la poudre d'aluminium au coulis

  9. 主要高新技术纤维的最新发展%The newest development of main new & hi-tech fibers

    Institute of Scientific and Technical Information of China (English)

    罗益锋

    2012-01-01

    全球高性能纤维的需求依然强劲,PAN基碳纤维(PAN-CF)的需求量预计将从2012年的4×104t左右,扩大至2015和2020年的7×104t和1.4×105t。碳纤维复合材料市场的平均增长率约为31.5%。中间相沥青基碳纤维将在大型风电叶片、隧道补强、导热材料、超导电材料等获得新发展。对位芳酰胺纤维新产品不断出现,其年均需求增长率约为7%~9%。超高相对分子质量聚乙烯(UHMWPE)薄膜切割纤维及条带作为新防护材料得到了新发展。聚乳酸(PLA)的复合纤维、混纺制品及改进产品,推动了其不断发展,而溶剂法纤维素纤维通过改进原纤化、起球等,也获得了长足发展。此外,间位芳酰胺、芳酰胺-酰亚胺、酚醛及聚苯并咪唑纤维,都有不同程度的新发展。%The demand of global high performance fibers are also powerful,the demand of PAN-based carbon fiber will expand from about 4×104t in 2012 to 7×104t and 14×104t in 2015 and 2020 respectively.The market of carbon fiber composite materials will grow about 31.5% annual.New developments for pitch-based carbon fiber in big wind blade,tunnel reinforcing,heat conductor ultra-electric conductor materials will be achieved.The annual demand of p-Aramid fiber will increase of about 7%~9%,and new products are arising.New developments of ultra-high molecular weight polyethylene(UHMWPE) tape and membrane cutting fiber for used as new protection materials are achieving.The development of polylactic acid(PLA) is promoting by their fibers,mixing fabrics and improved products,while solvent type cellulose fibers are also developed by improving their fibrillation and pile etc.Moreover,new developments of meta-aramid,aramid-amide,phenolic and poly benzimidazole(PBI) fibers are achieving in different level.

  10. Avaliação dos modos de falha sob impacto de compósitos de matriz polimérica reforçados por fibras

    Directory of Open Access Journals (Sweden)

    Marcelo M. M. Naglis

    1998-03-01

    Full Text Available RESUMO: Neste trabalho é feita uma avaliação dos modos de falha de compósitos de matriz polimérica reforçados por fibras de vidro, carbono ou aramida, submetidos a carregamento dinâmico. Os compósitos unidirecionais analisados foram fabricados por prensagem e cura à vácuo de lâminas de pré-impregnados. A energia total absorvida na fratura mostrou uma correlação inversamente proporcional ao módulo elástico das fibras usadas como reforço. Os compósitos com fibras de carbono falharam de um modo frágil. Para estes compósitos o comportamento ao impacto pode ser modelado usando-se uma análise puramente elástica. Para os compósitos com fibras de vidro a falha foi controlada por um mecanismo misto de cisalhamento ao longo da interface fibra-matriz e tensão normal trativa atuando perpendicularmente às fibras. O modelo elástico empregado para simular o comportamento ao impacto subestima a energia absorvida por estes compósitos, porém, a diferença entre os valores experimentais e os calculados não ultrapassou 20 %. A falha dos compósitos com fibras aramidas foi atribuída, principalmente, ao componente de tensão trativa atuando perpendicularmente às fibras. Nestes compósitos foi observado arrancamento superficial nas fibras aramidas e o comportamento ao impacto não obedece o modelo elástico empregado.ABSTRACT: In this work an evaluation of the fracture mode of fiber reinforced resin matrix composites submitted to three point bending dynamic impact testing was undertaken. The unidirectional glass, carbon and aramid fiber-epoxy matrix composites used were fabricated by vacuum bagging prepreg laminas. The energy absorbed to fracture the composites had an inverse correlation to the fibres' elastic modulus. The carbon fiber composites failed in a brittle mode. The analysis of the fracture surfaces showed that for the glass fiber composites, the failure is controlled by a coupled mechanism of shear along the fiber

  11. Experimental study of acoustical characteristics of honeycomb sandwich structures

    Science.gov (United States)

    Peters, Portia Renee

    Loss factor measurements were performed on sandwich panels to determine the effects of different skin and core materials on the acoustical properties. Results revealed inserting a viscoelastic material in the core's mid-plane resulted in the highest loss factor. Panels constructed with carbon-fiber skins exhibited larger loss factors than glass-fiber skins. Panels designed to achieve subsonic wave speed did not show a significant increase in loss factor above the coincidence frequency. The para-aramid core had a larger loss factor value than the meta-aramid core. Acoustic absorption coefficients were measured for honeycomb sandwiches designed to incorporate multiple sound-absorbing devices, including Helmholtz resonators and porous absorbers. The structures consisted of conventional honeycomb cores filled with closed-cell polyurethane foams of various densities and covered with perforated composite facesheets. Honeycomb cores filled with higher density foam resulted in higher absorption coefficients over the frequency range of 50 -- 1250 Hz. However, this trend was not observed at frequencies greater than 1250 Hz, where the honeycomb filled with the highest density foam yielded the lowest absorption coefficient among samples with foam-filled cores. The energy-recycling semi-active vibration suppression method (ERSA) was employed to determine the relationship between vibration suppression and acoustic damping for a honeycomb sandwich panel. Results indicated the ERSA method simultaneously reduced the sound transmitted through the panel and the panel vibration. The largest reduction in sound transmitted through the panel was 14.3% when the vibrations of the panel were reduced by 7.3%. The influence of different design parameters, such as core density, core material, and cell size on wave speeds of honeycomb sandwich structures was experimentally analyzed. Bending and shear wave speeds were measured and related to the transmission loss performance for various material

  12. Carbon fiber based composites stress analysis. Experimental and computer comparative studies

    Science.gov (United States)

    Sobek, M.; Baier, A.; Buchacz, A.; Grabowski, Ł.; Majzner, M.

    2015-11-01

    Composite materials used nowadays for the production of composites are the result of advanced research. This allows assuming that they are among the most elaborate tech products of our century. That fact is evidenced by the widespread use of them in the most demanding industries like aerospace and space industry. But the heterogeneous materials and their advantages have been known to mankind in ancient times and they have been used by nature for millions of years. Among the fibers used in the industry most commonly used are nylon, polyester, polypropylene, boron, metal, glass, carbon and aramid. Thanks to their physical properties last three fiber types deserve special attention. High strength to weight ratio allow the use of many industrial solutions. Composites based on carbon and glass fibers are widely used in the automotive. Aramid fibers ideal for the fashion industry where the fabric made from the fibers used to produce the protective clothing. In the paper presented issues of stress analysis of composite materials have been presented. The components of composite materials and principles of composition have been discussed. Particular attention was paid to the epoxy resins and the fabrics made from carbon fibers. The article also includes basic information about strain measurements performed on with a resistance strain gauge method. For the purpose of the laboratory tests a series of carbon - epoxy composite samples were made. For this purpose plain carbon textile was used with a weight of 200 g/mm2 and epoxy resin LG730. During laboratory strain tests described in the paper Tenmex's delta type strain gauge rosettes were used. They were arranged in specific locations on the surface of the samples. Data acquisition preceded using HBM measurement equipment, which included measuring amplifier and measuring head. Data acquisition was performed using the Easy Catman. In order to verify the results of laboratory tests numerical studies were carried out in a

  13. High-strength fiber-reinforced plastic reinforcement of wood and wood composite

    Energy Technology Data Exchange (ETDEWEB)

    Tingley, D.A.; Eng, P. [Oregon State Univ., Corvallis, OR (United States)

    1996-12-31

    Research and development underway since 1982 has led to the development of a method of reinforcing wood and wood composite structural products (WWC) using high-strength fiber-reinforced plastic. This method allows the use of less wood fiber and lower grade wood fiber for a given load capacity. The first WWC in which reinforcement has been marketed is glulam beams. Marketed under the trade name FiRP{trademark} Reinforced glulam, the product has gained code approval and is now being used in the construction of buildings and bridges in the United States, Japan and other countries. The high-strength fiber-reinforced plastic (FiRP{trademark} Reinforced panel (RP)) has specific characteristics that are required to provide for proper use in WWC`s. This paper discusses these characteristics and the testing requirements to develop code approved allowable design values for carbon, aramid and fiberglass RP`s for such uses. Specific issues such as in-service characteristics, i.e. long term creep tests and tension-tension fatigue tests, are discussed.

  14. INTERFACIAL STUDIES OF CONTINUOUS FIBERS REINFORCED POLY( AROMATIC ETHERS) CONTAINING PHTHALAZINONE MOIETIES%连续纤维增强含二氮杂萘酮联苯结构聚芳醚砜酮树脂基复合材料的界面

    Institute of Scientific and Technical Information of China (English)

    陈平; 陆春; 王静; 张承双; 于祺

    2011-01-01

    groups; the plasma etched the fiber surface obviously, enhancing the surface roughness and surface free energy and improving the wettability of the fiber distinctly. Plasma treatment conditions should be appropriate during surface modification of fibers by clod plasma. After CF was treated for 5 min ,CF surface polar group was increased to a relatively higher level. However,the effect of plasma etching on CF surface is relatively slower. After CF was treated for 5 mmin, CF surface roughness was changed a little.However,after CF was treated for more than 15 min CF surface roughness was increased significantly. Based onthe study above, the interfacial adhesion and fracture mechanism of continuous fiber reinforced soluble polyaromatic ether resin composites was also systematically analysed by interlaminar shear strength ( ILSS),water absorption and scanning electron microscopy (SEM) measurements. It was found that CF reinforced poly(phthalazinone ether su]fone ketone)(PPESK) composite interracial adhesion mechanism analysis indicats that both chemical bonding and mechanical interlocking interaction has a positive effect on composite interfacial adhesion,however, mechanical interaction has a dominant effect on composite interfacial adhesion than chemical bonding interaction. Armos aramid fiber composite interlaminar shear strength increased from 59.5 MPa for untreated sample to 68.8 MPa for plasma treated for 10 rain under discharge power at 200 W,with an increase of 15.6%. The water absorption decrease of composite also indirectly showed that oxygen plasma treatment improved composite interfacial adhesion. The primary failure mode of Armos aramid or PBO/PPESK composites shifted from interface failure to matrix fracture after oxygen plasma treatment. The interfacial adhesion of Armos aramid or PBO/PPESK composites was improved by oxygen plasma treatment due to thechemical linkage and mechanical bonding between Armos aramid or PBO fibers and PPESK matrices, and the chemical

  15. Development of fly ash-based automotive brake lining

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, S.; Chugh, Y.P. [South Illinois University, Carbondale, IL (United States). College of Engineering

    2007-07-15

    Coal-fired power plants all over the world generate huge amounts of fly ash each year, 70 million tons of which are produced in the United States alone. Only 40% of all fly ashes generated in the USA find beneficial applications and rest have to be disposed off, which is burden for the generation industry. Fly ash particles possess certain characteristics that make them suitable for use in friction composites as a filter material. An attempt has been made through this research to incorporate more than 50wt% of fly ash particles in automotive brake lining friction composites. This paper presents the research carried out on development of friction composites, using fly ash obtained from a specific power plant in Illinois. Ingredients such as phenolic resin, aramid pulp, glass fiber, potassium titanate, graphite, aluminum fiber and copper powder were used in the composite development phase, in addition to the fly ash. The developed brake lining composites have exhibited consistent coefficients of friction in the range of 0.35-0.4, and wear rates lower than 12wt%.

  16. Effect of Short Fiber Reinforcement on Mechanical Properties of Hybrid Phenolic Composites

    Directory of Open Access Journals (Sweden)

    Sembian Manoharan

    2014-01-01

    Full Text Available Fiber plays an important role in determining the hardness, strength, and dynamic mechanical properties of composite material. In the present work, enhancement of viscoelastic behaviour of hybrid phenolic composites has been synergistically investigated. Five different phenolic composites, namely, C1, C2, C3, C4, and C5, were fabricated by varying the weight percentage of basalt and aramid fiber, namely, 25, 20, 15, 10, and 5% by compensating with barium sulphate (BaSO4 to keep the combined reinforcement concentration at 25 wt%. Hardness was measured to examine the resistance of composites to indentation. The hardness of phenolic composites increased from 72.2 to 85.2 with increase in basalt fiber loading. Composite C1 (25 wt% fiber is 1.2 times harder than composite C5. Compression test was conducted to find out compressive strength of phenolic composites and compressive strength increased with increase in fiber content. Dynamic mechanical analysis (DMA was carried out to assess the temperature dependence mechanical properties in terms of storage modulus (E′, loss modulus (E′′, and damping factor (tan δ. The results indicate great improvement of E′ values and decrease in damping behaviour of composite upon fiber addition. Further X-ray powder diffraction (XRD and energy-dispersive X-ray (EDX analysis were employed to characterize the friction composites.

  17. Synthesis and Characterization of Fibre Reinforced Silica Aerogel Blankets for Thermal Protection

    Directory of Open Access Journals (Sweden)

    S. Chakraborty

    2016-01-01

    Full Text Available Using tetraethoxysilane (TEOS as the source of silica, fibre reinforced silica aerogels were synthesized via fast ambient pressure drying using methanol (MeOH, trimethylchlorosilane (TMCS, ammonium fluoride (NH4F, and hexane. The molar ratio of TEOS/MeOH/(COOH2/NH4F was kept constant at 1 : 38 : 3.73 × 10−5 : 0.023 and the gel was allowed to form inside the highly porous meta-aramid fibrous batting. The wet gel surface was chemically modified (silylation process using various concentrations of TMCS in hexane in the range of 1 to 20% by volume. The fibre reinforced silica aerogel blanket was obtained subsequently through atmospheric pressure drying. The aerogel blanket samples were characterized by density, thermal conductivity, hydrophobicity (contact angle, and Scanning Electron Microscopy. The radiant heat resistance of the aerogel blankets was examined and compared with nonaerogel blankets. It has been observed that, compared to the ordinary nonaerogel blankets, the aerogel blankets showed a 58% increase in the estimated burn injury time and thus ensure a much better protection from heat and fire hazards. The effect of varying the concentration of TMCS on the estimated protection time has been examined. The improved thermal stability and the superior thermal insulation of the flexible aerogel blankets lead to applications being used for occupations that involve exposure to hazards of thermal radiation.

  18. Aerosol resuspension from fabric: implications for personal monitoring in the beryllium industry.

    Science.gov (United States)

    Bohne, J E; Cohen, B S

    1985-02-01

    The fabric used for work clothing at an industrial site can significantly influence personal monitor (PM) exposure estimates because dust resuspension from clothing can increase the concentration at the sampler inlet. The magnitude of the effect depends on removal forces and on the interaction of the contaminant particles with work garments. Aerosol deposition and resuspension on cotton and Nomex aramid fabrics was evaluated at a beryllium refinery. Electrostatically charged cotton backdrops collected more beryllium than neutral controls, but electronegative Nomex backdrops did not. Moving fabrics collected more beryllium than did stationary controls. When contaminated fabrics were agitated, PMs mounted 2.5 cm in front of the fabric collected more beryllium than monitors above the fabric, positioned to simulate the nose or mouth. The difference between the air concentrations measured by these PMs increased with Be loading and tended to level off for highly contaminated fabric. Cotton resuspended a larger fraction of its contaminant load than Nomex. These results are consistent with current knowledge of the behavior of particles on fabric fibers. Aerosol resuspension from garments is an important consideration in assessing inhalation exposure to toxic dusts. A garment may attract and retain toxic particles. This contamination is then available for later resuspension. PMID:3976498

  19. Liquid electrolyte-free cylindrical Al polymer capacitor review: Materials and characteristics

    Science.gov (United States)

    Yoo, Jeeyoung; Kim, Jaegun; Kim, Youn Sang

    2015-06-01

    The manufacturing methods for liquid electrolyte-free Al polymer capacitors are introduced by using new materials like novel oxidants, separators and negative current collectors. The Al polymer capacitor is constructed by an Al foil as an anode, Al2O3 as a dielectric, and poly(3, 4-ethylenedioxythiophene) (PEDOT) as a cathode. There are also various synthetic methods of 3, 4-ethylenedioxythiophene (EDOT) and the chemical polymerization of PEDOT from EDOT using iron benzenesulfonate as a new oxidant and dopant. Furthermore, various cathodic current collectors such as conventional Al foils, carbon and titanium dioxide deposited on Al foils or substrates, as well as various separators with manila-esparto paper and synthetic fibers (series of acryl, PET, etc.) are studied. The Al polymer capacitors with the newly introduced oxidant (iron benzenesulfonate), separator (aramid based synthetic fibers) and current collector (TiO2) exhibit considerably enhanced capacitance values and the extremely low resistance (7 mΩ), so there is low power consumption and high reliability. Additionally, the newly developed Al polymer capacitor is guaranteed for 5,000 h at 125 °C, which means there is a long life time operation over ∼ 5 × 106 h at 65 °C.

  20. 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.

  1. Production and application of chemical fibers with special properties for manufacturing composite materials and goods of different usage

    Science.gov (United States)

    Levit, R.

    1993-01-01

    The development of modern technologies demands the creation of new nonmetallic, fibrous materials with specific properties. The fibers and materials developed by NII 'Chimvolokno', St. Petersburg, can be divided into two groups. The first group includes heat-resistant fibers, fire-resistant fibers, thermotropic fibers, fibers for medical application, and textile structures. The second group contains refractory fibers, chemoresistant and antifriction fibers, fibers on the basis of polyvinyl alcohol, microfiltering films, and paperlike and nonwoven materials. In cooperation with NPO 'Chimvolokno' MYTITSHI, we developed and started producing heat-resistant high-strength fibers on the base of polyhetarearilin and aromatic polyimides (SVM and terlon); heat-resistant fibers on the base of polyemede (aramid); fire-retardant fibers (togilen); chemoresistant and antifriction fibers on the basis of homo and copolymers of polytetrafluoroethylene (polyfen and ftorin); and water soluble, acetylated, and high-modulus fibers from polyvinyl alcohol (vylen). Separate reports will deal with textile structures and thermotropic fibers, as well as with medical fibers. One of the groups of refractory fibers carbon fibers (CF) and the corresponding paperlike nonwoven materials are discussed in detail. Also, composite materials (CM) and their base, which is the subject of the author's research since 1968, is discussed.

  2. Preparation and Properties of A Low-cost Triad Mica Tape Material%一种低成本三合一云母带材料的制备及性能研究

    Institute of Scientific and Technical Information of China (English)

    高云霞; 赵琬倩; 陈子荣

    2016-01-01

    A triad mica tape material was designed and prepared, and its mechanical properties and electri-cal properties were tested. The results show that comparing with the polyimide aramid mica tape, the triad mica tape has better mechanical properties and equivalent breakdown voltage. The dielectric loss factor of simulation bars prepared by the triad mica tape material is less than 8%. So the triad mica tape could be used as a kind of low cost alternative material for manufacturing low voltage motor.%设计并制备了一种三合一云母带材料,并对其力学性能和电气性能进行测试。结果表明:与二合一聚酰亚胺芳纶云母带材料相比,三合一云母带的力学性能更加优异,击穿电压与二合一云母带相当,采用三合一云母带制备的模拟线棒热态介损低于8%。因此三合一云母带可以作为一种低成本替代材料用于低压电机的制造。

  3. Influence of PEO and CPAM on the Formation of the Base Paper for Paper Based Friction Material%PEO和CPAM对纸基摩擦材料原纸性能的影响

    Institute of Scientific and Technical Information of China (English)

    陆赵情; 陈杰; 张大坤

    2013-01-01

    The experiment used carbon fiber, chopped Kevlar fiber and aramid pulp, bamboo fiber and sepiolite flocking as raw material to prepare paper based friction material by wet-forming process. Polyethylene oxide ( PEO) and cationic polyacrylamides ( CPAM) were used as chemical additives and the influence of the dosages of PEO and CPAM on furnish dispersion and the paper formation was studied. The results show that the furnish dispersion and the paper formation were the best when the dosages of PEO and CPAM were 0.2% and 0.16% respectively%采用碳纤维、短切芳纶纤维、芳纶浆粕、竹纤维以及海泡石绒为原料,并用抄纸的方法抄造纸基摩擦材料原纸;通过在抄造浆料中添加聚氧化乙烯(PEO)和阳离子聚丙烯酰胺(CPAM),探究了PEO和CPAM对浆料分散性能和纸张匀度和抗张强度的影响.结果表明,PEO对浆料有良好的分散作用,CPAM对纸张有很好的增强效果,当PEO用量为0.2%、CPAM用量为0.16%时,浆料分散效果最好,成纸的匀度最高.

  4. LDEF results for polymer-matrix composite experiment AO 180

    International Nuclear Information System (INIS)

    This report represents a summary of the results obtained to-date on a polymer matrix composite experiment (AO 180) located at station D-12, about 82 deg off the 'ram' direction. Different material systems comprised of graphite, boron, and aramid (Kevlar) fiber reinforcements were studied. Although previous results were presented on in-situ thermal-vacuum cycling effects, particularly dimensional changes associated with outgassing, additional comparative data will be shown from ground-based tests on control and flight samples. The system employed was fully automated for thermal-vacuum cycling using a laser interferometer for monitoring displacements. Erosion of all three classes of materials due to atomic oxygen (AO) will also be discussed, including angle of incidence effects. Data from this experiment will be compared to published results for similar materials in other LDEF experiments. Composite materials' erosion yields will be presented on an AO design nomogram useful for estimating total material loss for given exposure conditions in low Earth orbit (LEO). Optical properties of these materials will also be compared with control samples. A survey of the damage caused by micrometeoroids/debris impacts will be addressed as they relate to polymer matrix composites. Correlations between hole size and damage pattern will be given. Reference to a new nomogram for estimating the number distribution of micrometeoroid/debris impacts for a given space structure as a function of time in LEO will be addressed based on LDEF data

  5. Improvement of surface wettability and interfacial adhesion of poly-(p-phenylene terephthalamide) by incorporation of the polyamide benzimidazole segment

    Energy Technology Data Exchange (ETDEWEB)

    Cai Renqin [State key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Peng Tao [State key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); China Blue Star Chengrand Chemical Co. Ltd., Chengdu, 610041 (China); Wang Fengde [China Blue Star Chengrand Chemical Co. Ltd., Chengdu, 610041 (China); Ye Guangdou [State key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); Xu Jianjun, E-mail: xujj@scu.edu.cn [State key Laboratory of Polymer Materials Engineering, College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2011-09-01

    In order to investigate the effect of the polyamide benzimidazole group on the surface wettability and interfacial adhesion of fiber/matrix composites, surface features of two kinds of aramid fibers, poly (p-phenylene terephthalamide) fiber (Kevlar-49) and poly-(polyamide benzimidazole-co-p-phenylene terephthalamide) (DAFIII), have been analyzed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis (CAA) system, respectively. The results show that with the incorporation of the polyamide benzimidazole segment, more polar functional groups exist on DAFIII surface. The contact angles of water and diiodomethane on DAFIII surface get smaller. The surface free energy of DAFIII increases to 36.5 mJ/m{sup 2}, which is 2.3% higher than that of Kevlar-49. In addition, DAFIII has a larger rough surface compared with that of Kevlar-49 due to different spinning processes. The interfacial shear strength (IFSS) of DAFIII/matrix composite is 25.7% higher than that of Kevlar-49/matrix composite, in agreement with the observed results from surface feature tests. SEM micrographs of failed micro-droplet specimens reveal a strong correlation between the fracture features and the observed test data.

  6. Analysis of composite structural elements

    Directory of Open Access Journals (Sweden)

    A. Baier

    2010-12-01

    Full Text Available Purpose: The themes of the study are composite structural components. For this purpose have been designed and built several research positions.Design/methodology/approach: Using different structural materials to build new device components requires multiple tests of the components. Research posts were designed in the advanced graphical program CAx Siemens NX 7.5. Analysed samples were made from the glass fibre, aramid and carbon of various weights. Due to the specific use of composite materials it focuses on the elements in the form of plates and flat bars. For the examination of experimental strain gauge technique was used bead, the force sensor and displacement sensor. The experimental methods were compared with computer simulation using the FEM.Findings: The aim of this study was to determine the basic material constants and a comparison of the experimental method and the method of computer simulation.Research limitations/implications: Change the number of layers and how to connect the laminate with the steel plate changes mechanical properties of the structural component.Practical implications: The ultimate result will be knowledge on the different forms of laminates, such as material properties, the stresses in all layers, strain and comparing the results obtained by two methods.Originality/value: The expected outcome of the study will be the composition and method of joining composite laminate with a steel plate to the possible application in the repair and construction of structural elements of freight wagons.

  7. Investigation of Optimum Parameters for Mechanical Properties of Ecofriendly Molded Plant Fibre Polymer Matrix Composite by Experimental Methods

    Directory of Open Access Journals (Sweden)

    S.BENJAMIN LAZARUS

    2014-03-01

    Full Text Available Natural fibre composites are mainly price-driven commodity composites, which have useable structural properties at relatively low cost. The manufacture of such types of composites are environmentally sustainable alternative to conventional composites made of glass, carbon and aramid fibres which are considered critical because of the growing environmental consciousness. Fibres derived from plants are renewable and have low levels of embodied energy compared to synthetic fibres. Therefore this research work explains the development of natural fibre composite, [9] to attain the optimum mechanical property parameters which are equivalent and better to the traditional reinforcing fibres such as glass and carbon. The research work illustrates the manufacture and tested values of one such composite manufactured from a plant fibre which is used as green manuring plant called Crotalaria juncea. Retted fibres after alkali treatment [17] is taken and plate preparation is done using polyester resin mixed with random orientation of the fibre of lengths 20,30,40 and 50mm to a weight of 21,28,31,35,42 and 45 grams as the first part. In the second part of the work woven orientation of biaxial, biaxially stitched and unidirectional mat in 2 layer and 3 layer separately and they are mixed with polyester resin and plates are prepared. Both the stages are tested for mechanical properties [10,16] such that the breakeven value of each property is analyzed, and the results acquired derive the usefulness of the material for required application.

  8. Ultralight weight hybrids - the coming revolution

    Energy Technology Data Exchange (ETDEWEB)

    Lovins, A.B. [Rocky Mountain Inst., Snowmass, CO (United States)

    1995-12-31

    An interview with Amory Lewins of the Rocky Mountain Institute in the USA is reported. The Institute exists to foster the efficient and sustainable use of resources and has conducted what is possibly the most extensive and detailed work in the world on new ways to save electricity. The focus of the interview is the concept of ultralight-weight electric ``hypercars``. Advanced composite materials are envisaged for hypercars. From a safety engineering point of view, composites incorporating aramid or polyethylene fibres into a carbon fibre structure are desirable. The energy absorption of such materials in the event of a crash is five times greater than that of steel. Vehicle curb weights of about 480kg are predicted for a 4/5 seater car in the short-term. This could reduce to around 400 kg with the development of lighter-weight storage systems such as ultra capacitors, superflywheels or possibly thin-film lithium polymer batteries. There would still be a small steel content but the reduction in iron and steel in a platform could rise to 98%. As far as propulsion technology is concerned, the key issue is software; many interesting possibilities for smarter controls exist. It is thought that the radical simplification incorporated in a hypercar would make it cost advantageous and that it is a technology which may very soon revolutionise the motor industry. (UK)

  9. Effects of composite adherend properties on stresses in double lap bonded joints

    International Nuclear Information System (INIS)

    Highlights: ► We analysis the maximal stresses distribution in the adhesive and the adherend for double lap joint. ► We modified the mechanical properties of adherend layer to decreases the stresses in adhesive layer. ► Then, we analysis the influence of modifying the types of fibers on maximal stresses distributions. ► We analysis the thickness modifications of some layers on maximal stresses distribution. ► In last, we analysis the combination of different modifications on maximal stresses distribution. -- Abstract: The effects of composite layer stiffness, thickness and ply orientations on stresses in the adhesive layer of a double lap bonded joint are investigated using three-dimensional finite element analysis code ABAQUS. A special 3-layer modelling technique is used in the finite element analysis. The non-linear behaviour of adhesive is also considered. Six composite laminates with different ply orientations are used in the lap-joint analysis. The composite materials considered in the analysis are – carbon epoxy, boron epoxy, T300/934 graphite-epoxy, and aramid epoxy. The analysis results indicate that the maximum stress in the adhesive can be significantly reduced by changing the stiffness and fibre orientations in the composite layer. Also, the use of hybrid composite (changing the nature of the fibres in two layers which are near the adhesive layer) results in reducing adhesive shear stresses.

  10. Applications of phase change polymers in fibrous substrates

    International Nuclear Information System (INIS)

    This paper reports on insolubilization of polyethylene glycols (Mn of 600-20,000) onto a variety of fibrous substrates by reaction with a methylolamide resin (DMDHEU or dimethyloldihydroxyethyleneurea) in the presence of acid catalysts produced modified materials that have several improved functional properties and that are useful for numerous applications. Crosslinking or insolubilization of the polyols occurs under mild cuing conditions (80-100 degrees C). The resultant properties of the modified substrate (essentially a flexible composite of fiber and crosslinked polyol in the matrix) are markedly dependent on the proper choice of curing conditions (time and temperature). Representative fiber types and blends that have been modified by this process include: cotton, polyester, polyamide, cotton blends, wool blends, aramids, glass, acrylic, polypropylene, elastomeric fibers and short fibers used to make paper. All types of fabric constructions have been used (woven, nonwoven, and knit). The most novel property is the thermal adaptability of the modified fabrics or substrates to a variety of climatic conditions. This adaptability is due to the high enthalpy of fusion (cooling effect in hot weather) and crystallization (liberation of heat in cold weather) of the crosslinked polyethylene glycols (insolubilized phase change materials or PCM's). The novel thermal effects are due to the hydrophilic nature of the crosslinked polyol as well as its reduced thermal conductivity. Thermal profiles of the modified materials have been characterized by differential scanning calorimetry, infrared thermography, and by limited wear trials with garments containing the polymeric PCM's. There are other enhanced functional properties of the modified fabrics

  11. The Use of Zylon Fibers in ULDB Balloons

    Science.gov (United States)

    Zimmerman, M.; Seely, L.; McLaughlin, J.

    Early in the development of the ULDB balloon, Zylon (PBO) was selected as the tendon material due to its favorable stress-strain properties. It is a next generation super fiber whose strength and modulus are almost double those of the p-Aramid fibers. In addition there are two versions of the Zylon, As Spun (AS) and High Modulus (HM). Data will be presented on why the HM was chosen. Early in the development process, it was learned that this material exhibited an unusual sensitivity to degradation by ambient light. This is in addition to the expected sensitivity to UV radiation (Ultraviolet). The fiber manufacturer reported all of these properties in their literature. Due to the operating environment of the ULDB (Ultra Long Duration Balloon) it is necessary to protect the tendons from both visible and UV radiation. Methods to protect the tendons will be discussed. In addition, information on the long term exposure of the braided tendon over a thirty-six month period in a controlled manufacturing plant will be provided.

  12. Power generation from base excitation of a Kevlar composite beam with ZnO nanowires

    Science.gov (United States)

    Malakooti, Mohammad H.; Hwang, Hyun-Sik; Sodano, Henry A.

    2015-04-01

    One-dimensional nanostructures such as nanowires, nanorods, and nanotubes with piezoelectric properties have gained interest in the fabrication of small scale power harvesting systems. However, the practical applications of the nanoscale materials in structures with true mechanical strengths have not yet been demonstrated. In this paper, piezoelectric ZnO nanowires are integrated into the fiber reinforced polymer composites serving as an active phase to convert the induced strain energy from ambient vibration into electrical energy. Arrays of ZnO nanowires are grown vertically aligned on aramid fibers through a low-cost hydrothermal process. The modified fabrics with ZnO nanowires whiskers are then placed between two carbon fabrics as the top and the bottom electrodes. Finally, vacuum resin transfer molding technique is utilized to fabricate these multiscale composites. The fabricated composites are subjected to a base excitation using a shaker to generate charge due to the direct piezoelectric effect of ZnO nanowires. Measuring the generated potential difference between the two electrodes showed the energy harvesting application of these multiscale composites in addition to their superior mechanical properties. These results propose a new generation of power harvesting systems with enhanced mechanical properties.

  13. Development of multifunctional fiber reinforced polymer composites through ZnO nanowire arrays

    Science.gov (United States)

    Malakooti, Mohammad H.; Patterson, Brendan A.; Hwang, Hyun-Sik; Sodano, Henry A.

    2016-04-01

    Piezoelectric nanowires, in particular zinc oxide (ZnO) nanowires, have been vastly used in the fabrication of electromechanical devices to convert wasted mechanical energy into useful electrical energy. Over recent years, the growth of vertically aligned ZnO nanowires on various structural fibers has led to the development of fiber-based nanostructured energy harvesting devices. However, the development of more realistic energy harvesters that are capable of continuous power generation requires a sufficient mechanical strength to withstand typical structural loading conditions. Yet, a durable, multifunctional material system has not been developed thoroughly enough to generate electrical power without deteriorating the mechanical performance. Here, a hybrid composite energy harvester is fabricated in a hierarchical design that provides both efficient power generating capabilities while enhancing the structural properties of the fiber reinforced polymer composite. Through a simple and low-cost process, a modified aramid fabric with vertically aligned ZnO nanowires grown on the fiber surface is embedded between woven carbon fabrics, which serve as the structural reinforcement as well as the top and the bottom electrodes of the nanowire arrays. The performance of the developed multifunctional composite is characterized through direct vibration excitation and tensile strength examination.

  14. 树脂基防弹防刺材料的研究%The Research of Resin Based Bullet and Puncture Proof Materials

    Institute of Scientific and Technical Information of China (English)

    高晓清; 左向春; 袁承军; 樊凤彬

    2012-01-01

    本文通过不同芳纶织物与改性环氧树脂复合实验,优选出适用防弹防刺材料的增强体,并最终制备出防弹防刺材料。实验表明材料满足GA141—2010《警用防弹衣》、GA68—2008《警用防刺服》3级标准要求,且轻质、柔软、舒适,具有良好的市场前景。%Bullet and puncture proof materials finally have been made in this paper by applying modified epoxy on different aramid fabrics and optimizing the ingredients of composite. It shows that the materials which are light-weight, soft, flexible have a good perspective of application meet all the requirement of level 3 in the standard of GA141-2010 "Police Ballistic Resistance of Body Armor" and the standard of GA68-2008 "Stab Resistance Body Armor for Police".

  15. Atomistic simulations of aromatic polyurea and polyamide for capacitive energy storage

    Science.gov (United States)

    Dong, Rui; Ranjan, V.; Buongiorno Nardelli, Marco; Bernholc, J.

    2015-07-01

    Materials for capacitive energy storage with high energy density and low loss are desired in many fields. We investigate several polymers with urea and amide functional groups using density functional theory and classical molecular dynamics simulations. For aromatic polyurea (APU) and para-aramid (PA), we find several nearly energetically degenerate ordered structures, while meta-aromatic polyurea (mAPU) tends to be rotationally disordered along the polymer chains. Simulated annealing of APU and PA structures results in the formation of hydrogen-bonded sheets, highlighting the importance of dipole-dipole interactions. In contrast, hydrogen bonding does not play a significant role in mAPU, hence the propensity to disorder. We find that the disordered structures with misaligned chains have significantly larger dielectric constants, due to significant increase in the free volume, which leads to easier reorientation of dipolar groups in the presence of an electric field. Large segment motion is still not allowed below the glass transition temperature, which explains the experimentally observed very low loss at high field and elevated temperature. However, the degree of disorder needs to be controlled, because highly entangled structures diminish the free dipoles and decrease permittivity. Among the considered materials, mAPU is the most promising dielectric for capacitive energy storage, but the concept of increasing permittivity while maintaining low loss through disorder-induced free volume increase is generally applicable and provides an alternative pathway for the design of high-performance dielectrics for capacitive energy storage.

  16. Filled Ethylene-propylene Diene Terpolymer Elastomer as ThermalInsulator for Case-bonded Solid Rocket Motors

    Directory of Open Access Journals (Sweden)

    C. M. Bhuvaneswari

    2008-01-01

    Full Text Available Ethylene-propylene diene terpolymer (EPDM-based insulation system is being globallyused for case-bonded solid rocket motors. A study was undertaken using EPDM as base polymer,blended with hypalon and liquid EPDM and filled with fibrous and non-fibrous fillers. Theseformulations were evaluated as rocket motor insulation system. The basic objective of the studywas to develop an insulation system based on EPDM for case-bonded applications. A series ofrocket motor insulator compositions based on EPDM, filled with particulate and fibrous fillerslike precipitated silica, fumed silica, aramid, and carbon fibres have been studied for mechanical,rheological, thermal, and interface properties. Compositions based on particulate fillers wereoptimised for the filler content. Comparatively, fumed silica was found to be superior as fillerin terms of mechanical and interface properties. Addition of fibrous filler (5 parts improved thepeel strength, and reduced the thermal conductivity and erosion rate. All the compositions wereevaluated for sulphur and peroxide curing. Superior mechanical properties were achieved forsulphur-cured products, whereas peroxide-cured products exhibited an excellent ageing resistance.Rocket motors were insulated with optimised composition and propellant cast, and the motorswere evaluated by conducting static test in end-burning mode.Defence Science Journal, 2008, 58(1, pp.94-102, DOI : http://dx.doi.org/10.14429/dsj.58.1628

  17. Analysis of the ballistic impact response of a composite material using FAST Infrared Imagery

    Science.gov (United States)

    Marcotte, Frederick; Ouellet, Simon; Farley, Vincent

    2013-05-01

    The level of protection offered by a given ballistic material is typically evaluated in terms of a set of projectiles and their associated velocity at which a certain percentage of the projectiles are expected to perforate. (i.e. FSP 17gr : V50 = 500m/s, 9mm FMJ; V0=500m/s). These metrics give little information about the physical phenomena by which energy is dispersed, spread or absorbed in a specific target material. Aside from post-test inspection of the impacted material, additional information on the target response is traditionally obtained during a test from the use of high speed imaging, whether it is from a single camera aimed at the impact surface or the backface, or from a set of camera allowing full 3-D reconstruction of a deformed surface. Again, this kind of data may be difficult to interpret if the interest is in the way energy is managed in the target in real time. Recent technological progress in scientific grade high-speed infrared (IR) camera demonstrated that these phenomena can straightforwardly be measured using IR thermal imaging. This paper presents promising results obtained from Telops FAST-IR 1500 infrared camera on an aramid-based ballistic composite during an impact from a small caliber fragment simulating projectile (FSP).

  18. Influence of Polymer Restraint on Ballistic Performanceof Alumina Ceramic Tiles

    Directory of Open Access Journals (Sweden)

    P.R.S. Reddy

    2008-03-01

    Full Text Available An experimental study has been carried out to evaluate the influence of confinement ofalumina ceramic tiles through polymer restraint, on its ballistic performance. Tiles of 99.5 per centpurity alumina were subjected to ballistic impact against 7.62 mm armour piercing projectiles atvelocities of about 820 m/s. The tiles of size 75 mm x 75 mm x 7 mm were confined on both facesby effectively bonding varying numbers of layers of polymer fabrics. These were then bondedto a 10 mm thick fibre glass laminate as a backing using epoxy resin. High performance polyethyleneand aramid polymer fabrics were used in the current set of experiments for restraining the tiles.Comparative effects of confinement on energy absorption of tiles with varied number of layersof fabrics were evaluated. It was observed that by providing effective confinement to the tile,energy absorption could be doubled with increase in areal density by about 13 per cent.Photographs of the damage and the effects of restraint on improvement in energy absorptionof ceramic tiles are presented and discussed.

  19. Fiber Reinfoced Polymer Used for Flooding Protection of Engineering Structures Made of RC and Brick Masonry

    Directory of Open Access Journals (Sweden)

    Gabriel Oprişan

    2008-01-01

    Full Text Available Urban and rural floods are becoming nowadays a frequent problem to be dealt with, by both the population and the authorities. Floods and flood related natural disasters act against the civil, industrial and agricultural structures by the hydrostatic and hydrodynamic pressures of water. A set of protective solutions based on Fiber Reinforced Polymer (FRP composite materials, for structural elements of buildings subjected to flood loadings, is proposed and analysed. These solutions are achieved by using the hand lay-up forming technique utilizing glass, carbon or aramid fibers fabrics pre-impregnated with thermosetting epoxy, polyester or vynilester resins. The application of these FRP composites is carried out on reinforced concrete columns and beams as well as on brick masonry works aiming to increase in the overall load bearing capacity, especially against horizontal loads. An improved protection against excessive humidity is also envisaged. The Finite Elements Method based LUSAS software was used to simulate a partially flooded structure. The numerical modeling was carried out in both the un-strengthened and strengthened conditions of the structure in order to assess the increasing in load and deformation capacities of the structural elements. Volumetric finite elements were used for modeling the concrete and masonry members.

  20. Armored garment for protecting

    Science.gov (United States)

    Purvis, James W.; Jones, II, Jack F.; Whinery, Larry D.; Brazfield, Richard; Lawrie, Catherine; Lawrie, David; Preece, Dale S.

    2009-08-11

    A lightweight, armored protective garment for protecting an arm or leg from blast superheated gases, blast overpressure shock, shrapnel, and spall from a explosive device, such as a Rocket Propelled Grenade (RPG) or a roadside Improvised Explosive Device (IED). The garment has a ballistic sleeve made of a ballistic fabric, such as an aramid fiber (e.g., KEVLAR.RTM.) cloth, that prevents thermal burns from the blast superheated gases, while providing some protection from fragments. Additionally, the garment has two or more rigid armor inserts that cover the upper and lower arm and protect against high-velocity projectiles, shrapnel and spall. The rigid inserts can be made of multiple plies of a carbon/epoxy composite laminate. The combination of 6 layers of KEVLAR.RTM. fabric and 28 plies of carbon/epoxy laminate inserts (with the inserts being sandwiched in-between the KEVLAR.RTM. layers), can meet the level IIIA fragmentation minimum V.sub.50 requirements for the US Interceptor Outer Tactical Vest.

  1. Breeding waterbirds (Pelecaniformes at Maracujá island, Babitonga bay estuary, north coast of Santa Catarina, Brazil

    Directory of Open Access Journals (Sweden)

    Alexandre Venson Grose

    2014-06-01

    Full Text Available Waterbirds usually breed in an aggregate way, forming large breeding colonies with different species. This study describes biological aspects of waterbirds from a colony at Maracujá island, in the Babitonga bay estuary, north coast of Santa Catarina, Brazil. We collected data on species richness, abundance, breeding chronology, predation, and nest distribution in the island. Within the period from September 2010 to February 2011, 15 waterbird species were identified using the feeding and resting site, and, out of them, 5 species bred in the island (Nycticorax nycticorax, Nyctanassa violacea, Egretta caerulea, Phimosus infuscatus, and Aramides cajanea. We registered 154 active nests, 79 nests of N. Nycticorax, 14 nests of N. violacea, 6 nests of P. infuscatus, 5 nests of E. caerulea, and only 1 nest of A. cajanea. The estimated local population was 308 breeding individuals, and N. nycticorax was the most abundant species, accounting for 51% of nests. The months with higher concentration of nests were September, October, and November. In addition to waterbirds, 4 birds of prey and scavenger species were registered, which were responsible for egg and/or chick losses, along with Larus dominicanus. Maracujá island has been used for breeding by at least 5 species and its protection deserves attention, in order to ensure the maintenance and possibility to expand this breeding site.

  2. Concrete-Filled-Large Deformable FRP Tubular Columns under Axial Compressive Loading

    Directory of Open Access Journals (Sweden)

    Omar I. Abdelkarim

    2015-10-01

    Full Text Available The behavior of concrete-filled fiber tubes (CFFT polymers under axial compressive loading was investigated. Unlike the traditional fiber reinforced polymers (FRP such as carbon, glass, aramid, etc., the FRP tubes in this study were designed using large rupture strains FRP which are made of recycled materials such as plastic bottles; hence, large rupture strain (LRS FRP composites are environmentally friendly and can be used in the context of green construction. This study performed finite element (FE analysis using LS-DYNA software to conduct an extensive parametric study on CFFT. The effects of the FRP confinement ratio, the unconfined concrete compressive strength ( , column size, and column aspect ratio on the behavior of the CFFT under axial compressive loading were investigated during this study. A comparison between the behavior of the CFFTs with LRS-FRP and those with traditional FRP (carbon and glass with a high range of confinement ratios was conducted as well. A new hybrid FRP system combined with traditional and LRS-FRP is proposed. Generally, the CFFTs with LRS-FRP showed remarkable behavior under axial loading in strength and ultimate strain. Equations to estimate the concrete dilation parameter and dilation angle of the CFFTs with LRS-FRP tubes and hybrid FRP tubes are suggested.

  3. Impact and residual fatigue behavior of ARALL and AS6/5245 composite materials

    Science.gov (United States)

    Johnson, W. S.

    1986-01-01

    Aramide fiber reinforced aluminum laminates (ARALL) represent a cross between resin matrix composites and metals. The purpose of this study was to evaluate the impact sensitivity of this concept. Two types of ARALL (7075 aluminum prestrained and 2024 aluminum not prestrained) were tested through static indentation and the results compared to sheet 2024-T3 and 7075-T6 aluminum alloys. A state-of-the-art composite (AS6/5245) was also tested and compared to the ARALL. Further, the two types of ARALL material and the composite were dynamically impacted at two energy levels and fatigue tested to determine residual fatigue strength. Both forms of the ARALL material had worse impact resistance than monolithic sheet aluminum. The ARALL material made with 2024-T3 aluminum had better impact resistance than did the laminates made with 7075-T6 aluminum. The ARALL materials are at least equal to the composite material in impact damage resistance and are better for impact detection. The composite material has higher residual fatigue strength after impact than the ARALL material and is 25 percent lighter. The prestraining of the ARALL greatly reduces the fatigue growth of impact damage.

  4. Tribological and Wear Properties of Multi-Layered Materials

    Directory of Open Access Journals (Sweden)

    V. Bria

    2011-09-01

    Full Text Available The usage of fabrics as reinforcements in composites is spreading due to fabrics’ properties. The use of fabrics allows obtaining of sinuous surfaces, for instance, unlike the use of prepregs. Using fabrics as reinforcements it is also possible to obtain laminate-like materials having the same matrix in all their volume. In the case of pre-pregs usage always it is necessary to discuss about the bonding between individual plies. For this study eight materials were formed. The forming method consisted in placing the pre-polymer imbued fabric pieces into a mould to obtain plates of composites. Two types of fabric were used: one simple type of untwisted tows of carbon fibres and the second one simple type of alternated untwisted tows of carbon and aramide fibres. Both fabrics were prepared in order to ensure the matrix adherence. The polymer matrix is realised from epoxy system EPIPHEN RE 4020 / EPIPHEN DE 4020 filled with clay and talc in equal amounts of 5% (weight ratio. The use of clay and talc were meant to improve the thermal dimensional stability of final materials. Tribological properties of formed materials were studied using pin-on-disk method with steel disk and pins made of materials. Both orientation of reinforcement fibres relative to friction direction were taken into account. Results are encouraging further studies in order to identify the best solution of forming a multi-component material with more than one designable property.

  5. Improvement of surface wettability and interfacial adhesion of poly-(p-phenylene terephthalamide) by incorporation of the polyamide benzimidazole segment

    Science.gov (United States)

    Cai, Ren-Qin; Peng, Tao; Wang, Feng-De; Ye, Guang-Dou; Xu, Jian-Jun

    2011-09-01

    In order to investigate the effect of the polyamide benzimidazole group on the surface wettability and interfacial adhesion of fiber/matrix composites, surface features of two kinds of aramid fibers, poly (p-phenylene terephthalamide) fiber (Kevlar-49) and poly-(polyamide benzimidazole-co-p-phenylene terephthalamide) (DAFIII), have been analyzed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis (CAA) system, respectively. The results show that with the incorporation of the polyamide benzimidazole segment, more polar functional groups exist on DAFIII surface. The contact angles of water and diiodomethane on DAFIII surface get smaller. The surface free energy of DAFIII increases to 36.5 mJ/m 2, which is 2.3% higher than that of Kevlar-49. In addition, DAFIII has a larger rough surface compared with that of Kevlar-49 due to different spinning processes. The interfacial shear strength (IFSS) of DAFIII/matrix composite is 25.7% higher than that of Kevlar-49/matrix composite, in agreement with the observed results from surface feature tests. SEM micrographs of failed micro-droplet specimens reveal a strong correlation between the fracture features and the observed test data.

  6. Novel self-sensing carbon nanotube-based composites for rehabilitation of structural steel members

    Science.gov (United States)

    Ahmed, Shafique; Doshi, Sagar; Schumacher, Thomas; Thostenson, Erik T.; McConnell, Jennifer

    2016-02-01

    Fatigue and fracture are among the most critical forms of damage in metal structures. Fatigue damage can initiate from microscopic defects (e.g., surface scratches, voids in welds, and internal defects) and initiate a crack. Under cyclic loading, these cracks can grow and reach a critical level to trigger fracture of the member which leads to compromised structural integrity and, in some cases, catastrophic failure of the entire structure. In our research, we are investigating a solution using carbon nanotube-based sensing composites, which have the potential to simultaneously rehabilitate and monitor fatigue-cracked structural members. These composites consist of a fiber-reinforced polymer (FRP) layer and a carbon nanotube-based sensing layer, which are integrated to form a novel structural self-sensing material. The sensing layer is composed of a non-woven aramid fabric that is coated with carbon nanotubes (CNT) to form an electrically conductive network that is extremely sensitive to detecting deformation as well as damage accumulation via changes in the resistance of the CNT network. In this paper, we introduce the sensing concept, describe the manufacturing of a model sensing prototype, and discuss a set of small-scale laboratory experiments to examine the load-carrying capacity and damage sensing response.

  7. Linearized Model of an Actively Controlled Cable for a Carlina Diluted Telescope

    Science.gov (United States)

    Andersen, T.; Le Coroller, H.; Owner-Petersen, M.; Dejonghe, J.

    2014-04-01

    The Carlina thinned pupil telescope has a focal unit (``gondola'') suspended by cables over the primary mirror. To predict the structural behavior of the gondola system, a simulation building block of a single cable is needed. A preloaded cable is a strongly non-linear system and can be modeled either with partial differential equations or non-linear finite elements. Using the latter, we set up an iteration procedure for determination of the static cable form and we formulate the necessary second-order differential equations for such a model. We convert them to a set of first-order differential equations (an ``ABCD''-model). Symmetrical in-plane eigenmodes and ``axial'' eigenmodes are the only eigenmodes that play a role in practice for a taut cable. Using the model and a generic suspension, a parameter study is made to find the influence of various design parameters. We conclude that the cable should be as stiff and thick as practically possible with a fairly high preload. Steel or Aramid are suitable materials. Further, placing the cable winches on the gondola and not on the ground does not provide significant advantages. Finally, it seems that use of reaction-wheels and/or reaction-masses will make the way for more accurate control of the gondola position under wind load. An adaptive stage with tip/tilt/piston correction for subapertures together with a focus and guiding system for freezing the fringes must also be studied.

  8. Full metal jacket!

    CERN Document Server

    Laëtitia Pedroso

    2011-01-01

    Ten years ago, standard issue clothing only gave CERN firemen partial protection but today our fire-fighters are equipped with state-of-the-art, full personal protective equipment.   CERN's Fire Brigade team. For many years, the members of CERN's Fire Brigade went on call-outs clad in their work trousers and fire-rescue coats, which only afforded them partial protection. Today, textile manufacturing techniques have moved on a long way and CERN's firemen are now kitted out with state-of-the-art personal protective equipment. The coat and trousers are three-layered, comprising fire-resistant aramide, a protective membrane and a thermal lining. The CERN Fire Brigade' new state-of-the-art personal protection equipment. "This equipment is fully compliant with the standards in force and is therefore resistant to cuts, abrasion, electrical arcs with thermal effects and, of course, fire," explains Patrick Berlinghi, the CERN Fire Brigade's Logistics Officer. You might think that su...

  9. Reinforcement and recovery of timber structures

    Directory of Open Access Journals (Sweden)

    Antonio Alves Dias

    2006-02-01

    Full Text Available Preservation of timber structures is a reason for constant concern because their deterioration often involves compromising the historical patrimony, besides endangering the safety of the structure, and consequently, of their users. Many are the examples of churches, residences or other constructions where this manifestation is a fact. The technique of reinforcing structurally endangered pieces with the addition of natural or synthetic fibers, is an alternative that has been researched. In the group of synthetic fibers, fiberglass, carbon and aramid ones are included. On the other hand, it has been frequent in the restoration of old buildings, especially in Europe, the employment of materials that were not available in the past, aiming to achieve structural, acoustic and aesthetic benefits. On an existing timber structure floor, a concrete slab has been carried out, with an appropriate connection system among the parts, constituting the composite timber-concrete structures. This alternative has been considered as extraordinarily viable, because it gathers a series of convenience related with the durability and it presents better mechanic performance than conventional timber structures. In this work, the state-of-the-art of the use of fibers as structural reinforcement and of the timber-concrete composite structures, is presented.

  10. Avaliação da temperatura de transição vítrea de compósitos poliméricos reparados de uso aeronáutico Evaluation of glass transition temperature of the repaired polymeric composites of aeronautical use

    Directory of Open Access Journals (Sweden)

    Jane M. F. de Paiva

    2006-03-01

    Full Text Available Este trabalho mostra a avaliação da temperatura de transição vítrea (Tg, por DMTA, de três famílias de compósitos poliméricos reparados, tendo como laminados base tecidos de fibras de carbono/resina epóxi modificada com elastômero (F584, vidro/resina epóxi (F161 e aramida/resina epóxi (F161. Os compósitos foram laminados manualmente por processo convencional e curados em autoclave de indústria aeronáutica. Posteriormente, danos foram simulados sendo, em seguida, reparados adotando-se a técnica de sobreposição de camadas de pré-impregnados de resina epóxi (F155, com adição de filme adesivo de epóxi (FM 73. As curvas DMTA mostram os efeitos da combinação de diferentes sistemas de resinas na Tg e, conseqüentemente, na temperatura de serviço do componente reparado. O material de reparo utilizado, baseado em pré-impregnados com resina epóxi F155 e filme adesivo de epóxi, provocou a redução da Tg dos compósitos reparados. Para os laminados base com tecido de fibras de carbono e vidro foram verificadas reduções de aproximadamente 30 °C na Tg. Este efeito foi mais pronunciado (redução de aproximadamente 40 °C quando o laminado reparado de aramida foi submetido a condicionamento higrotérmico a temperatura e umidade elevadas. Esta redução na Tg dos laminados reparados é atribuída à migração do adesivo para o pré-impregnado de resina epóxi F155 utilizado no reparo, durante o processo de cura, e à plasticização do sistema polimérico pela água, durante o condicionamento higrotérmico. A redução da Tg leva a uma conseqüente redução da temperatura de serviço do compósito polimérico reparado.This work shows the evaluation of the glass transition temperature (Tg by DMTA of three different families of repaired polymeric composites, manufactured with carbon fiber fabric/epoxy F584, glass fabric/epoxy F161 and aramide fabric/epoxy F161, respectively. The composites were laminated by conventional hand

  11. Macroscopic fibres of CNTs as electrodes for multifunctional electric double layer capacitors: from quantum capacitance to device performance

    Science.gov (United States)

    Senokos, E.; Reguero, V.; Palma, J.; Vilatela, J. J.; Marcilla, Rebeca

    2016-02-01

    In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m2 g-1, high electrical conductivity (3.5 × 105 S m-1) and mechanical properties in the high-performance range including toughness (35 J g-1) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg-1 and 14 Wh kg-1, respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10 000 cycles of charge-discharge at 3.5 V.In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through

  12. Molecular Self-Assembly of Short Aromatic Peptides: From Biology to Nanotechnology and Material Science

    Science.gov (United States)

    Gazit, Ehud

    2013-03-01

    The formation of ordered amyloid fibrils is the hallmark of several diseases of unrelated origin. In spite of grave clinical consequence, the mechanism of amyloid formation is not fully understood. We have suggested, based on experimental and bioinformatic analysis, that aromatic interactions may provide energetic contribution as well as order and directionality in the molecular-recognition and self-association processes that lead to the formation of these assemblies. This is in line with the well-known central role of aromatic-stacking interactions in self-assembly processes. Our works on the mechanism of aromatic peptide self-assembly, lead to the discovery that the diphenylalanine recognition motif self-assembles into peptide nanotubes with a remarkable persistence length. Other aromatic homodipeptides could self-assemble in nano-spheres, nano-plates, nano-fibrils and hydrogels with nano-scale order. We demonstrated that the peptide nanostructures have unique chemical, physical and mechanical properties including ultra-rigidity as aramides, semi-conductive, piezoelectric and non-linear optic properties. We also demonstrated the ability to use these peptide nanostructures as casting mold for the fabrication of metallic nano-wires and coaxial nano-cables. The application of the nanostructures was demonstrated in various fields including electrochemical biosensors, tissue engineering, and molecular imaging. Finally, we had developed ways for depositing of the peptide nanostructures and their organization. We had use inkjet technology as well as vapour deposition methods to coat surface and from the peptide ``nano-forests''. We recently demonstrated that even a single phenylalanine amino-acid can form well-ordered fibrilar assemblies.

  13. Investigation of VEGGIE Root Mat

    Science.gov (United States)

    Subbiah, Arun M.

    2013-01-01

    VEGGIE is a plant growth facility that utilizes the phenomenon of capillary action as its primary watering system. A cloth made of Meta Aramid fiber, known as Nomex is used to wick water up from a reservoir to the bottom of the plants roots. This root mat system is intended to be low maintenance with no moving parts and requires minimal crew interface time. Unfortunately, the water wicking rates are inconsistent throughout the plant life cycle, thus causing plants to die. Over-wicking of water occurs toward the beginning of the cycle, while under-wicking occurs toward the middle. This inconsistency of wicking has become a major issue, drastically inhibiting plant growth. The primary objective is to determine the root cause of the inconsistent wicking through experimental testing. Suspect causes for the capillary water column to break include: a vacuum effect due to a negative pressure gradient in the water reservoir, contamination of material due to minerals in water and back wash from plant fertilizer, induced air bubbles while using syringe refill method, and material limitations of Nomex's ability to absorb and retain water. Experimental testing will be conducted to systematically determine the cause of under and over-wicking. Pressure gages will be used to determine pressure drop during the course of the plant life cycle and during the water refill process. A debubbler device will be connected to a root mat in order to equalize pressure inside the reservoir. Moisture and evaporation tests will simultaneously be implemented to observe moisture content and wicking rates over the course of a plant cycle. Water retention tests will be performed using strips of Nomex to determine materials wicking rates, porosity, and absorptivity. Through these experimental tests, we will have a better understanding of material properties of Nomex, as well as determine the root cause of water column breakage. With consistent test results, a forward plan can be achieved to resolve

  14. Intracranial Pressure Response to Non-Penetrating Ballistic Impact: An Experimental Study Using a Pig Physical Head Model and Live Pigs

    Directory of Open Access Journals (Sweden)

    Hai Liu, Jianyi Kang, Jing Chen, Guanhua Li, Xiaoxia Li, Jianmin Wang

    2012-01-01

    Full Text Available This study was conducted to characterize the intracranial pressure response to non-penetrating ballistic impact using a "scalp-skull-brain" pig physical head model and live pigs. Forty-eight ballistic tests targeting the physical head model and anesthetized pigs protected by aramid plates were conducted with standard 9 mm bullets at low (279-297 m/s, moderate (350-372 m/s, and high (409-436 m/s velocities. Intracranial pressure responses were recorded with pressure sensors embedded in similar brain locations in the physical head model and the anesthetized pigs. Three parameters of intracranial pressure were determined from the measured data: intracranial maximum pressure (Pmax, intracranial maximum pressure impulse (PImax, and the duration of the first positive phase (PPD. The intracranial pressure waves exhibited blast-like characteristics for both the physical model and l live pigs. Of all three parameters, Pmax is most sensitive to impact velocity, with means of 126 kPa (219 kPa, 178 kPa (474 kPa, and 241 kPa (751 kPa for the physical model (live pigs for low, moderate, and high impact velocities, respectively. The mean PPD becomes increasingly short as the impact velocity increases, whereas PImax shows the opposite trend. Although the pressure parameters of the physical model were much lower than those of the live pigs, good correlations between the physical model and the live pigs for the three pressure parameters, especially Pmax, were found using linear regression. This investigation suggests that Pmax is a preferred parameter for predicting the severity of the brain injury resulting from behind armor blunt trauma (BABT.

  15. Study of mechanical properties and fracture mechanisms of synthetic fibers nylon-and-polyester type, used in engineering products

    International Nuclear Information System (INIS)

    Fibers are groups formed by molecular-chain-oriented filaments. Fibers play a fundamental role in human being's daily life and they can be found in several forms and geometries, such as filaments, yarns, beams, rope, fabric, composite, coatings, others. They are used in various segments such as civil, mechanical, electrical, electronics, military, naval, nautical, aviation, health, medicine, environment, communications, safety, space, others. Fibers are divided into two distinct classes: natural and chemical ones, which cover synthetic and man-made sub-classes. They can be produced from several materials, such as wool, cotton, rayon, flax, silk, rock, nylon, polyester, polyethylene, poly-propylene, aramid, glass, carbon, steel, ceramic, others. Globally, the participation of chemical fibers corresponds to approximately 59,9%, and the synthetic fiber polyester, the most used one, represents approximately 63% of the world market. Vital needs have led to the development of multi-function fibers and the focus has changed in the last 10 years with the use of nano technology for environmental responsibility and smart fibers. The study of mechanical properties and fracture mechanisms of fibers is of great relevance for characterization and understanding of causes as consequence of failures. For such reason, it was selected technical fabrics made of high performance synthetic fiber nylon-and-polyester type, used in engineered products such as tires, belts, hoses and pneumatic springs, which have been analyzed in each processing phase. Fiber samples were extracted after each processing phase to be analyzed, by traction destructive tests and scanning electron microscopy. The results of analysis of mechanical properties showed loss of resistance to temperature and multi axial stress during fiber processing phase. Through microscopy tests, it was possible to find contamination, surface stains, plastic deformations, scaling, variations in the fracture faces of the filaments and

  16. Strength Evaluation of Steel-Nylon Hybrid Fibre Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Maniram Kumar

    2014-07-01

    Full Text Available When fibres like steel, glass, polypropylene, nylon, carbon, aramid, polyester, jute, etc are mixed with concrete known as fibre reinforced concrete. To overcome the deficiencies of concrete; fibres are added to improve the performance of concrete. In this research hybrid reinforced concrete is made by using steel and nylon 6 fibres. The inclusion of both steel and nylon 6 fibres are used in order to combine the benefits of both fibers; structural improvements provided by steel fibers and the resistance to plastic shrinkage improvements provided by nylon fibers. So the aim of this project is to investigate the mechanical properties (compressive strength, flexure strength and split tensile strength of hybrid fiber reinforced concrete under compression, flexure & tension. The total volume of fibre was taken 0.75 % of total volume of concrete. In this experimental work, four different concrete mix proportions were casted with fibres and one mix without fibres. Four different mix combinations of steel- nylon 6 fibres were 100-00%, 75-25%, 50-50% and 25-75%. Superplasticizer was used in all mixes to make concrete more workable. The results shown that compressive, split tensile and flexural strength of hybrid fibre reinforced concrete increase by increasing quantity of steel and nylon 6 fibres. The increase in compressive and tensile strength due to incorporation of steel fibre is greater than that of using nylon fibre. For the nylon 6 fibres, adding more fibres into the concrete has a limited improvement on splitting tensile strength. Inclusion of nylon 6 fibres along with steel fibres results in considerable improvement in flexural strength as compared to solo steel fibre.

  17. Effect of Gamma-Irradiation on the Properties of Tyre Cords

    International Nuclear Information System (INIS)

    The industrial cord fabrics are used for reinforcing of tyre carcass. Tyre reinforcing elements carry the major share of the structural load of the automobiles. For the better service life of a tyre, the reinforcing material should exhibit excellent strength properties, fatigue resistance, modulus, cord-tyre adhesion level, and dimensional stability. The tyre cord fabrics can be produced with different type of materials. Yarns offered at the market, are namely, Polyamide 6 and 66, Polyester, Rayon and Aramid. One of the successful industrial application of radiation processing has been the pre-vulcanization of tyres imparting shapes stability prior to final vulcanization. Since tyre is a composite of reinforcing materials and rubber compounds, the influence of high energy irradiation on the reinforcing materials, i.e. on the textile cord needs to be investigated. In this study, gamma irradiation of high tenacity nylon 66 and polyester tyre cords was investigated. The untreated tyre cords with different twist levels were irradiated in air. The changes in the mechanical and thermal properties with absorbed dose were measured. The mechanical properties were deteriorated with increasing dose for nylon 66 cords, while almost unchanged for polyester cords. Hot shrinkage for the nylon cords was found to be improved, i.e. decreased. A slight decrease in the hot shrinkage of irradiated polyester cords was also observed. It has been found that the effect of irradiation on both nylon 66 and polyester cords was not dependent on the twist levels of the cords. It is also concluded that polyester cord has higher radiation resistance than nylon 66 cord, and polyester cord seems to be more suitable reinforcing material for pre-vulcanization of tyres with high energy radiation

  18. Multiscale modeling of interwoven Kevlar fibers based on random walk to predict yarn structural response

    Science.gov (United States)

    Recchia, Stephen

    Kevlar is the most common high-end plastic filament yarn used in body armor, tire reinforcement, and wear resistant applications. Kevlar is a trade name for an aramid fiber. These are fibers in which the chain molecules are highly oriented along the fiber axis, so the strength of the chemical bond can be exploited. The bulk material is extruded into filaments that are bound together into yarn, which may be chorded with other materials as in car tires, woven into a fabric, or layered in an epoxy to make composite panels. The high tensile strength to low weight ratio makes this material ideal for designs that decrease weight and inertia, such as automobile tires, body panels, and body armor. For designs that use Kevlar, increasing the strength, or tenacity, to weight ratio would improve performance or reduce cost of all products that are based on this material. This thesis computationally and experimentally investigates the tenacity and stiffness of Kevlar yarns with varying twist ratios. The test boundary conditions were replicated with a geometrically accurate finite element model, resulting in a customized code that can reproduce tortuous filaments in a yarn was developed. The solid model geometry capturing filament tortuosity was implemented through a random walk method of axial geometry creation. A finite element analysis successfully recreated the yarn strength and stiffness dependency observed during the tests. The physics applied in the finite element model was reproduced in an analytical equation that was able to predict the failure strength and strain dependency of twist ratio. The analytical solution can be employed to optimize yarn design for high strength applications.

  19. Macroscopic fibres of CNTs as electrodes for multifunctional electric double layer capacitors: from quantum capacitance to device performance.

    Science.gov (United States)

    Senokos, E; Reguero, V; Palma, J; Vilatela, J J; Marcilla, Rebeca

    2016-02-14

    In this work we present a combined electrochemical and mechanical study of mesoporous electrodes based on CNT fibres in the context of electric double layer capacitors. We show that through control of the synthetic and assembly processes of the fibres, it is possible to obtain an active material that combines a surface area of 250 m(2) g(-1), high electrical conductivity (3.5 × 10(5) S m(-1)) and mechanical properties in the high-performance range including toughness (35 J g(-1)) comparable to that of aramid fibre (e.g. Kevlar). These properties are a consequence of the predominant orientation of the CNTs, observed by wide- and small-angle X-ray diffraction, and to the exceptionally long CNT length on the millimetre scale. Cyclic voltammetry measurements in a three-electrode configuration and using 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR14TFSI) ionic liquid electrolyte, show that the CNT fibres have a large quantum capacitance, evidenced by the near linear dependence of geometric capacitance (and conductivity) on potential bias. This reflects the low dimensionality of the CNT building blocks, which were purposely synthesised to have 1-5 layers and a high degree of graphitization. From the charge-discharge measurements of supercapacitor devices with symmetric CNT fibre electrodes we obtain power and energy densities as high as 58 kW kg(-1) and 14 Wh kg(-1), respectively. These record-high values for CNT fibre-based supercapacitors, are a consequence of the low equivalent series resistance due to the high conductivity of the fibres, the large contribution from quantum capacitance, and the wide stability window of the ionic liquid (3.5 V). Cycle life experiments demonstrate stable capacitance and energy retention over 10,000 cycles of charge-discharge at 3.5 V. PMID:26809811

  20. Composite molding of SPECTRA{reg_sign} extended chain polyethylene fibers in a flexible rubber matrix

    Energy Technology Data Exchange (ETDEWEB)

    McKeehan, K.

    1997-08-01

    THETA Technologies, Inc. is a multidisciplinary research and development firm involved in the design and development of affordable, lightweight, high ballistic protection modular body armor ensemble for future military, law enforcement, and specialized commercial market applications. In the course of their research, THETA Technologies, Inc. identified that current state-of-the-art in ballistic protection and overall composite reinforcement is a high density extended chain polyethylene (HDECPE) fiber known as SPECTRA{reg_sign}, a product of AlliedSignal Fibers, Petersburg, VA. SPECTRA{reg_sign} is ten times stronger than steel of equal weight. As a non-aramid polyethylene, it offers highly desirable properties in areas of resistance to chemical degradation, virtual neutral buoyancy (0.97), and increased capacity for composite bonding over competing nylon-based fibers, such as KEVLAR{reg_sign}. SPECTRA Shield{trademark}, a woven ballistic-resistant fabric using the SPECTRA{reg_sign} fiber, is presently the most effective ballistic-resistant component for both flexible and hard plate composite armors. THETA Technologies, Inc. identified a market need for a boot sole design that would measurably increase protection to the wearer without significantly degrading performance in other areas, such as flexibility and overall weight. THETA Technologies, Inc. proposed a nitrile rubber and SPECTRA{reg_sign} fiber matrix to produce an optimal boot sole. The objective of this CRADA effort was to develop and test a process for combining the SPECTRA{reg_sign} fiber, in both chopped fiber and SPECTRA Shield{trademark} form, within a semiflexible nitrile composite having desirable and marketable properties in areas of resistance to penetration and mechanical stress.

  1. Bag filters at biofuelled plants, reliability and economy of operation; Slangfilter vid bioeldade anlaeggningar, tillfoerlitlighet och driftsekonomi

    Energy Technology Data Exchange (ETDEWEB)

    Lindau, Leif [SYCON Energikonsult, Malmoe (Sweden)

    2002-04-01

    The background to this work is the increased requirements on dust emission control for smaller (2-50 MW) biofuel plants in Sweden, where established technology consisting of multi cyclones cannot meet the emission demands, and where the specific cost of the large scale established technology (electrostatic precipitators) quickly increases with decreased plant size. Operational experience of bag filters on Swedish biofuel plants down to a size of 2 MW has been collected. The operational experience is remarkably uniform and positive and availability is high. Bag life, being the most important operational cost factor, is between two and eleven years. Most frequent material used is aramide, but also PPS is employed and the experience of both materials is good. The cost relation between bag filter (including an upstream skimmer) and electrostatic precipitator has been studied based on supplier quotations. Bag filter always has the lowest first cost. At one year bag life, the total cost of a bag filter is less than that for an electrostatic precipitator for plants smaller than 15 MW, and at more than one year's bag life, the bag filter has the lowest total cost for plants up to 50 MW. For plants smaller than 5-10 MW, the difference in total cost is very high. With some simple means for quality assurance of new bags, premature failure rate can be reduced. Following up cleaning interval and/or emission during operation time, gives information about the development of bag condition and necessary bag change can be foreseen. Since bag filters are more prone to damage by fire than electrostatic precipitators, the process of damage due to entrained sparks has been analysed based on practical observations and a thermal calculation. This consideration shows that this damage mode can be eliminated by an upstream skimmer having moderate but reliable performance. The result is well in coherence with the practical operational experience found that with an adequate skimmer

  2. Simulation and Experiments of Bird Impact Resistance of Full-scale Composite Leading Edge of Vertical Empennage%全尺寸复合材料垂尾前缘抗鸟撞仿真与试验

    Institute of Scientific and Technical Information of China (English)

    庞华华; 韩全民

    2014-01-01

    基于Pam/crash软件,建立SPH鸟体模型,仿真分析了两种工况:芳纶与玻璃钢全尺寸复合材料垂尾前缘分别在3.6 kg鸟体以114 m/s速度冲击下的动力学特性;通过模拟与试验结果的对比,验证了仿真方法有效。结果表明:在鸟体与结构接触区域以及前缘与盒段连接区域,需要划分更为精细的网格以真实模拟实际情况;芳纶及玻璃钢前缘的抗鸟撞性能与蒙皮的具体铺层信息相关。仿真及试验方法对工程设计具有实际参考价值。%Numerical analyses of 3.6 kg birds impacting on full-scale composite leading edge ( FCLD) of aircraft′s vertical tail have been performed by employing Pam/Crash package and SPH bird model was built.The simulation method was validated according to comparisons of experiment and calculating re-sults.It is suggested that the grids of impact zones should be meshed as accurate as possible .The anti-impacting ability of aramid and glass fiber reinforced plastics ( FRP) leading edge is related to the layups of skin.Moreover ,the simulating and test processes can be utilized and referred by industry directly .

  3. 芳纶纤维加固钢筋混凝土梁锚固长度的简化计算方法%SIMPLIFIED CALCULATING METHOD OF AFRP BONDING LENGTH FOR REINFORCED CONCRETE BEAMS STRENGTHENED WITH EXTERNALLY BONDED AFRP

    Institute of Scientific and Technical Information of China (English)

    田国芝; 王旭荣; 王有志; 张慎伟

    2009-01-01

    Based on the test results of RC beam strengthened with externally bonded AFRP, this paper analyzes the premature failure process of reinforced concrete members strengthened with externally bonded AFRP, the inteffacial shear stress is maximum at the AFRP cut-off point and starts to decay as the distance from the cut-off point is increased, the insufficiency and the high interracial shear stress concentration in the plate containment region are the main causes leading to the failure of reinforced concrete members strengthened with externally bonded AFRP. This paper also analyzes the effective anchorage length of AFRP with the mechanics model of tooth block and crack theory of concrete, works out the calculating formula of least anchorage length of AFRP for strengthening reinforced concrete beam with further simplified correction, and finally puts forward the tolerance strain value of FRP and the measures taken to avoid the premature failure of FRP, which provide theory basis for design and construction of strengthening with externally bonded FRP.%根据芳纶纤维(Aramid Fiber Reinforced Plastic,简称 AFRP)补强加固钢筋混凝土梁的粘结破坏的试验结果,分析AFRP加固钢筋混凝土抗弯构件粘结界面的剪应力的分布规律,即在纤维截断点处存在较高的应力集中,随着离截断点距离的增大剪应力分布逐渐趋于均匀.粘结锚固长度不足和过高的应力集中是造成AFRP加固钢筋混凝土构件早期破坏的主要原因.采用"齿"状块体力学计算模型和混凝土裂缝理论推导了AFRP加固钢筋混凝土梁所需要的有效锚固长度,并通过修正得出了AFRP加固钢筋混凝土受弯构件最小锚固长度的简化计算公式,提出了AFRP的容许应变值和避免AFRP早期破坏应采用的措施,可供AFRP加固工程设计和施工参考.

  4. On the role of CFRP reinforcement for wood beams stiffness

    Science.gov (United States)

    Ianasi, A. C.

    2015-11-01

    In recent years, carbon fiber composites have been increasingly used in different ways in reinforcing structural elements. Specifically, the use of composite materials as a reinforcement for wood beams under bending loads requires paying attention to several aspects of the problem such as the number of the composite layers applied on the wood beams. Study consolidation of composites revealed that they are made by bonding fibrous material impregnated with resin on the surface of various elements, to restore or increase the load carrying capacity (bending, cutting, compression or torque) without significant damage of their rigidity. Fibers used in building applications can be fiberglass, aramid or carbon. Items that can be strengthened are concrete, brick, wood, steel and stone, and in terms of structural beams, walls, columns and floors. This paper describes an experimental study which was designed to evaluate the effect of composite material on the stiffness of the wood beams. It proposes a summary of the fundamental principles of analysis of composite materials and the design and use. The type of reinforcement used on the beams is the carbon fiber reinforced polymer (CFRP) sheet and plates and also an epoxy resin for bonding all the elements. Structural epoxy resins remain the primary choice of adhesive to form the bond to fiber-reinforced plastics and are the generally accepted adhesives in bonded CFRP-wood connections. The advantages of using epoxy resin in comparison to common wood-laminating adhesives are their gap-filling qualities and the low clamping pressures that are required to form the bond between carbon fiber plates or sheets and the wood beams. Mechanical tests performed on the reinforced wood beams showed that CFRP materials may produce flexural displacement and lifting increases of the beams. Observations of the experimental load-displacement relationships showed that bending strength increased for wood beams reinforced with CFRP composite plates

  5. Adhesion of PBO Fiber in Epoxy Composites

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The high mechanical and thermal performance of poly p-phenylene- 2, 6-benzobisoxazole ( PBO ) fiber provides great potential applications as reinforcement fibers for composites. A composite of PBO fiber and epoxy resin has excellent electrical insulation properties, therefore, it is considered to be the best choice for the reinforcement in high magnetic field coils for pulsed magnetic fields up to 100 T.However, poor adhesion between PBO fiber and matrix is found because of the chemically inactive and/or relatively smooth surface of the reinforcement fiber preventing efficient chemical bonding in the interface, which is a challenging issue to improve mechanical properties. Here, we report the surface modification of PBO fibers by ultraviolet (UV)irradiation, O2 and NH3 plasma, as well as acidic treatments. The interfacial adhesion strength values of all the treatments show the similar level as determined for aramid fibers by pull-out tests, a significant impact on fibermatrix-adhesion was not achieved. The surface free energy and roughness are increased for both sized and extracted fibers after plasma treatments together with maleic anhydride grafting. The sized fiber shows marginal improvement in adhesion strength and no change in fiber tensile strength because of the barrier effect of the finish.For the extracted fiber, different surface treatments either show no apparent effect or cause reduction in adhesion strength. Atomic force microscopy (AFM) topography analysis of the fracture surfaces proved adhesive failure at the fiber surface. The fiber surface roughness is increased and more surface flaws are induced, which could result in coarse interface structures when the treated fiber surface has no adequate wetting and functional groups. The adhesion failure is further confirmed by similar adhesion strength and compression shear strength values when the fiber was embedded in various epoxy resins with different temperature behavior. The tensile strength of fiber

  6. Combination of natural fiber Boehmeria nivea (ramie) with matrix epoxide for bullet proof vest body armor

    Energy Technology Data Exchange (ETDEWEB)

    Anggoro, Didi Dwi, E-mail: anggorophd@gmail.com; Kristiana, Nunung, E-mail: nuna.c631@gmail.com [Master of Chemical Engineering, Faculty of Engineering, Diponegoro University Jln. Prof. Sudharto, Tembalang, Semarang, 50239 (Indonesia)

    2015-12-29

    Ballistic protection equipment, such as a bulletproof vest, is a soldier’s most important means of preserving life and survivability in extreme combat conditions. The bulletproof vests are designed to protect the user’s chest from injury without disturbing the ability to perform his duties. Aromatic polyamide or aramid fibers known under the trade name Kevlar, Trawon and so is synthetic fiber materials commonly used in the manufacture of bulletproof vests. This synthetic fibers have high tensile strength and ductility. Kevlar is expensive and imported material. In this study, will introduce local natural raw materials, ramie fiber (Boehmeria nivea) which is cheaper and environmentally friendly. It has enough tenacity and tensile strength as a bulletproof vest. This experiment uses two panels, there are Panel A as front surface of Panel B. Panel A is a combination of ramie and epoxide matrix, while panel B is only ramie. From several variations of experimental combinations between Panel A and Panel B, optimal combination obtained with 16 layers of panel A and 31-34 layers of panel B which is able to protect againts cal. 7.65 mm × 17 mm (.32 ACP) bullet fired through pistol .32 Pindad from a distance of 20 meters. Panel with a size of 20 cm × 20 cm has a total thickness between 12,922 to13,745 mm and a total weight between 506,26 to 520,926gram. Scanning electron microscopy (SEM) observations indicated that the porosity and surface area of the ramie fiber is smooth, fiber surfaces showed topography with micropores. SEM also showed well-arranged structure of fibers bonding. Energy Dispersive X-ray (EDX) analysis indicated 100 % carbon contents in ramie fiber. Test result indicates that panel from composite ramie-epoxide can reach the level 1of International Standard of NIJ - 010104. Compared to panel from polyester fiber, the panel from composite ramie-epoxide (0,50-0,52 kg) is lighter weight than panel polyester fiber (1,642 kg)

  7. Fram-2014/2015: A 400 Day Investigation of the Arctic's Oldest Sediments over the Alpha Ridge with a Research Hovercraft

    Science.gov (United States)

    Hall, J. K.; Kristoffersen, Y.

    2014-12-01

    The thickest multi-year ice in the Arctic covers a secret. Four short cores raised from the Alpha Ridge in the 1970s and 1980s from drift stations T-3 and CESAR showed ages between 45 and 76 my. The reason for these old ages became clear when examination of legacy seismic data from T-3 showed that in some places up to 500 m of sediments had been removed within an area of some 200 by 600 km, presumably by an impact of asteroid fragments. To investigate the impact area, the authors conceived an innovative research platform in 2007. Named the R/H SABVABAA, this 12m by 6m hovercraft has been home-based in Svalbard since June 2008. During the following 6 years the craft and its evolving innovative light-weight equipment have made 18 trips to the summer ice pack, traveling some 4410 km over ice during some six months of scientific investigations. An opportunity to get a lift to this area, some 1500 km from Svalbard, came in a 2011 invitation to join AWI's icebreaker POLARSTERN in its ARK-XXVIII/4 expedition departing Tromsö August 5, 2014. The 400 day drift will be the first wintering over, ever, of a mobile research platform with geophysical, geological, and oceanographic capabilities. The Arctic ice pack continually moves due to winds and currents. While at the main camp, observations will consist of marine geophysics (seismic profiling with four element CHIRP, a 20 in³ airgun with single hydrophone, as well as 12 kHz bathymetry and 200 kHz sounding of the deep scattering layer), marine geology (coring with a hydrostatically-boosted 3 or 6 m corer; bottom photography; and two rock dredges), and oceanography. Deployed away from the camp, four sonobuoys will allow 3-D seismic acquisition. Access to the depths below the ice is via a hydraulic capstan winch, with 6500 m of Kevlar aramid fiber rope with 2.8 ton breaking strength. Ice thickness monitoring of the local 100 km² will be made with the craft's EM-31 probe when away from the camp, moving to choice locations for

  8. Behavior of composite and polycarbonate plate under impact

    Directory of Open Access Journals (Sweden)

    Viot P.

    2010-06-01

    for filled polycarbonate because of an extension due to the addition of silicon. b Damage like fiber failure, decohesion, delamination and matrix failure are expected for composite material to dissipate energy [5]. Carbon fiber was chosen with thermoplastic matrix (Polyamide and Polyurethane to dissipate energy by plasticity and damage. This means that a higher tensile strain is expected. c Aramid fibers were chosen because of their high tensile strain (εr = 4.5%. Consequently a larger affected zone is expected to dissipate as much as possible energy. An epoxy matrix was loaded with carbon nanotubes in order to increase branching and micro-cracking and also increase dissipated energy.

  9. 不锈钢内衬纤维复合材料球形高压容器研制%DEVELOPMENT OF FIBRE COMPOSITE SPHERICAL HIGH PRESSURE VESSEL WITH STAINLESSSTEEL LINER

    Institute of Scientific and Technical Information of China (English)

    陈晓丽; 谭云; 姜一鸣; 丰杰

    2009-01-01

    By using high strength aramid fibre Ⅱ and kevlar - 49 fibre and stainlesssteel liner, one small spherical epoxy resin matrix fibre composite pressure vessel is developed. The structure material, design and testing methods of the vessel are introduced. Through pressure tests and hydrostatic pressure blast tests of the composite vessel before storage and after storage, the results show that design of the vessel is successful, and it can meet the requirement for use in a certain product. The weight of the composite vessel is over 60% lighter than that of the same kind of steel pressure vessel when the inner and outer diameter, work pressure and safety coefficient are same. The veak rate is lower than 1 × 10~(-8) Pa·m /s. After three years' storage of definite environment, the blast pressure goes a little higher instead of decreasing.%采用高强芳纶Ⅱ和凯芙拉-49纤维及不锈钢内衬,研制出小型球形环氧树脂基纤维复合材料压力容器.主要介绍了容器的结构材料、设计、试验方法.通过容器的密封性检验及贮存前后的液压爆破试验,结果表明,容器的设计是成功的,满足了设计使用要求.与同类钢制压力容器相比,在内径、外径、工作压力、安全系数相同情况下,该复合材料容器质量可减轻60%以上,漏率小于1×10~(-8) Pa·m3/s,且贮存3年后爆破压力不会下降并略有提高.

  10. Combination of natural fiber Boehmeria nivea (ramie) with matrix epoxide for bullet proof vest body armor

    Science.gov (United States)

    Anggoro, Didi Dwi; Kristiana, Nunung

    2015-12-01

    Ballistic protection equipment, such as a bulletproof vest, is a soldier's most important means of preserving life and survivability in extreme combat conditions. The bulletproof vests are designed to protect the user's chest from injury without disturbing the ability to perform his duties. Aromatic polyamide or aramid fibers known under the trade name Kevlar, Trawon and so is synthetic fiber materials commonly used in the manufacture of bulletproof vests. This synthetic fibers have high tensile strength and ductility. Kevlar is expensive and imported material. In this study, will introduce local natural raw materials, ramie fiber (Boehmeria nivea) which is cheaper and environmentally friendly. It has enough tenacity and tensile strength as a bulletproof vest. This experiment uses two panels, there are Panel A as front surface of Panel B. Panel A is a combination of ramie and epoxide matrix, while panel B is only ramie. From several variations of experimental combinations between Panel A and Panel B, optimal combination obtained with 16 layers of panel A and 31-34 layers of panel B which is able to protect againts cal. 7.65 mm × 17 mm (.32 ACP) bullet fired through pistol .32 Pindad from a distance of 20 meters. Panel with a size of 20 cm × 20 cm has a total thickness between 12,922 to13,745 mm and a total weight between 506,26 to 520,926gram. Scanning electron microscopy (SEM) observations indicated that the porosity and surface area of the ramie fiber is smooth, fiber surfaces showed topography with micropores. SEM also showed well-arranged structure of fibers bonding. Energy Dispersive X-ray (EDX) analysis indicated 100 % carbon contents in ramie fiber. Test result indicates that panel from composite ramie-epoxide can reach the level 1of International Standard of NIJ - 010104. Compared to panel from polyester fiber, the panel from composite ramie-epoxide (0,50-0,52 kg) is lighter weight than panel polyester fiber (1,642 kg).

  11. Improved, Low-Stress Economical Submerged Pipeline

    Science.gov (United States)

    Jones, Jack A.; Chao, Yi

    2011-01-01

    A preliminary study has shown that the use of a high-strength composite fiber cloth material may greatly reduce fabrication and deployment costs of a subsea offshore pipeline. The problem is to develop an inexpensive submerged pipeline that can safely and economically transport large quantities of fresh water, oil, and natural gas underwater for long distances. Above-water pipelines are often not feasible due to safety, cost, and environmental problems, and present, fixed-wall, submerged pipelines are often very expensive. The solution is to have a submerged, compliant-walled tube that when filled, is lighter than the surrounding medium. Some examples include compliant tubes for transporting fresh water under the ocean, for transporting crude oil underneath salt or fresh water, and for transporting high-pressure natural gas from offshore to onshore. In each case, the fluid transported is lighter than its surrounding fluid, and thus the flexible tube will tend to float. The tube should be ballasted to the ocean floor so as to limit the motion of the tube in the horizontal and vertical directions. The tube should be placed below 100-m depth to minimize biofouling and turbulence from surface storms. The tube may also have periodic pumps to maintain flow without over-pressurizing, or it can have a single pump at the beginning. The tube may have periodic valves that allow sections of the tube to be repaired or maintained. Some examples of tube materials that may be particularly suited for these applications are non-porous composite tubes made of high-performance fibers such as Kevlar, Spectra, PBO, Aramid, carbon fibers, or high-strength glass. Above-ground pipes for transporting water, oil, and natural gas have typically been fabricated from fiber-reinforced plastic or from more costly high-strength steel. Also, previous suggested subsea pipeline designs have only included heavy fixed-wall pipes that can be very expensive initially, and can be difficult and expensive

  12. Study for Key Technology of Light Kevlar Non-Woof Cloth Body Armour%轻质芳纶无纬布防弹衣关键技术研究

    Institute of Scientific and Technical Information of China (English)

    吴中伟; 刘元坤; 常浩

    2014-01-01

    本研究采用单因素实验设计的方法,以及采用添加压敏胶粘剂及固化剂的方法,研究了一种新型防凹陷芳纶无纬布。该无纬布无需进行二次上胶即可压制成防凹陷材料,并通过对防凹陷材料结构设计、压制工艺的优化,开发出了一种轻薄、穿着舒适的防弹衣产品。与传统的防弹衣产品相比,该结构防弹衣产品防弹性能达到NIJ IIIA级要求,防凹陷材料制备的防弹芯片面密度更低,产品重量降低了20%以上,产品的厚度由12mm减少至5.5mm,可明显减轻作战人员的负荷,芯片结构更加隐形,穿着更加舒适,满足了目前市场的发展需求。%In this study, a novel preventing depression of aramid non-woof cloth was prepared by adding pressure-sensitive adhesives and curing agent based on single factor experimental design methods. This non-woof cloth can be pressed into preventing depression materials without the secondary using adhesive. And a lightweight and comfortable body armour was developed by structural design of preventing depression material and optimization of pressing process. Compared to traditional body armour, the product could reach NIJ IIIA level requirements, and had the lower the density of the bullet-proof chip. The weight of product was decreased by more than 20%, and the thickness of product was reduced from 12mm to 5.5mm. These can significantly reduce the load, meanwhile, chip structure was more invisible and wearing more comfortable, these could meet current market trends.

  13. Hybrid Composite Cryogenic Tank Structure

    Science.gov (United States)

    DeLay, Thomas

    2011-01-01

    A hybrid lightweight composite tank has been created using specially designed materials and manufacturing processes. The tank is produced by using a hybrid structure consisting of at least two reinforced composite material systems. The inner composite layer comprises a distinct fiber and resin matrix suitable for cryogenic use that is a braided-sleeve (and/or a filamentwound layer) aramid fiber preform that is placed on a removable mandrel (outfitted with metallic end fittings) and is infused (vacuum-assisted resin transfer molded) with a polyurethane resin matrix with a high ductility at low temperatures. This inner layer is allowed to cure and is encapsulated with a filamentwound outer composite layer of a distinct fiber resin system. Both inner and outer layer are in intimate contact, and can also be cured at the same time. The outer layer is a material that performs well for low temperature pressure vessels, and it can rely on the inner layer to act as a liner to contain the fluids. The outer layer can be a variety of materials, but the best embodiment may be the use of a continuous tow of carbon fiber (T-1000 carbon, or others), or other high-strength fibers combined with a high ductility epoxy resin matrix, or a polyurethane matrix, which performs well at low temperatures. After curing, the mandrel can be removed from the outer layer. While the hybrid structure is not limited to two particular materials, a preferred version of the tank has been demonstrated on an actual test tank article cycled at high pressures with liquid nitrogen and liquid hydrogen, and the best version is an inner layer of PBO (poly-pphenylenebenzobisoxazole) fibers with a polyurethane matrix and an outer layer of T-1000 carbon with a high elongation epoxy matrix suitable for cryogenic temperatures. A polyurethane matrix has also been used for the outer layer. The construction method is ideal because the fiber and resin of the inner layer has a high strain to failure at cryogenic

  14. 高端车内饰阻燃针刺毡的研制%Study on Flame-Retardent Needle Felt of Interior Materials in High-End Car

    Institute of Scientific and Technical Information of China (English)

    张瑜; 黄婷婷; 王洪云; 殷媛; 李素英; 张伟

    2012-01-01

    将芳纶1414、三维中空涤纶阻燃纤维(PET)、聚丙烯腈预氧化纤维以及丙纶(PP)等按照不同的质量比均匀混配.采用非织造针刺加工技术制成了能够供高端车内饰材料使用的多种纤维交织的立体复合结构针刺毡.考察了原料混合比对材料性能的影响,发现试样混合比例为50:25:15:10时,材料的阻燃、耐磨、高回弹及透气等性能最佳.通过对轧光整理工艺参数的分析发现,轧光温度为140℃,压力为3MPa和时间为4min时,所得材料的综合性能最好.%The aramid fiber 1414, three-dimensional crimp hollow fire-retardant polyester fiber, polyacrylonitrile oxi- dized fibers and polypropylene are evenly mixed according to the different proportion. A variety of fiber mixed needl felt with three-dimensional composite structure is prepared by nonwoven needle-punched processing technology and is used in high-end car interior materials. The effect on material properties of mixing ratio of raw material is probed. It is found that the flame retardant, wear-resisting, high resilience, and permeability properties are good, when the mixing ratio of raw material is 50:25:15:10. Calendering technological parameter is also studied. It is found that the materail properties are the best, when the calendering temperature, calendering pressure and calendering time are 140 ℃, 3 MPa and 4 rain, respectively.

  15. 静电纺丝制备纳米纤维及其工业化研究进展%Research and Industrial Development of Nanofibers Prepared by Eiectrospinning

    Institute of Scientific and Technical Information of China (English)

    杨大祥; 李恩重; 郭伟玲; 王海斗; 徐滨士

    2011-01-01

    针对静电纺丝技术从实验室走向工业化还存在产率低的问题,重点分析了为提高生产效率而采用的多针头纺丝和无针头纺丝等批量化生产方法,简述了静电纺丝的基本原理和实施方法,介绍了静电纺丝制备聚合物纤维、无机物纤维、同轴及中空纤维的情况和特点.随着对静电纺丝方法、设备、工艺和材料研究的深入,通过对高压静电场分布的控制采用多喷头组合方式和无针滚筒方式将成为产业化制备纳米纤维的有效手段.通过控制高压电场分布利用提高效率后的单孔纺丝方法制备出了长、宽、厚分别为1000mm、350mm、1.28mm的芳纶1313纳米纤维布.最后对静电纺丝工业化规模制备纳米纤维材料进行了展望.%According to the problems that the electrospinning technology transfer from the laboratory to the industrialization, the principle and methods of electrospinning are outlined, the nanofibers of polymer and inorganic materials produced by electrospinning, including coaxial and hollow fibers are introduced, and then the methods of improving the production efficiency of multi-needles spinning and needless spinning are analyzed. With the development of the method, equipment, technique and materials of electrospinning, both the multi-needles with high-voltage controlling and the needleless with roller modes will be the most effective methods of producing nanofibers through electrospinning. Aramid-1313 nano-fiber non-woven fabrics with length, width and thickenss of 1000mm, 350mm, 1. 28mm, respectively have been produced via modified single needle electrospinning method. At last, industrialized nanofibers produced by electrospinning goes to practice in China is in dire need and with great prospects.

  16. Structural Behavior of Concrete Beams Reinforced with Basalt Fiber Reinforced Polymer (BFRP) Bars

    Science.gov (United States)

    Ovitigala, Thilan

    The main challenge for civil engineers is to provide sustainable, environmentally friendly and financially feasible structures to the society. Finding new materials such as fiber reinforced polymer (FRP) material that can fulfill the above requirements is a must. FRP material was expensive and it was limited to niche markets such as space shuttles and air industry in the 1960s. Over the time, it became cheaper and spread to other industries such as sporting goods in the 1980-1990, and then towards the infrastructure industry. Design and construction guidelines are available for carbon fiber reinforced polymer (CFRP), aramid fiber reinforced polymer (AFRP) and glass fiber reinforced polymer (GFRP) and they are currently used in structural applications. Since FRP is linear elastic brittle material, design guidelines for the steel reinforcement are not valid for FRP materials. Corrosion of steel reinforcement affects the durability of the concrete structures. FRP reinforcement is identified as an alternative to steel reinforcement in corrosive environments. Although basalt fiber reinforced polymer (BFRP) has many advantages over other FRP materials, but limited studies have been done. These studies didn't include larger BFRP bar diameters that are mostly used in practice. Therefore, larger beam sizes with larger BFRP reinforcement bar diameters are needed to investigate the flexural and shear behavior of BFRP reinforced concrete beams. Also, shear behavior of BFRP reinforced concrete beams was not yet studied. Experimental testing of mechanical properties and bond strength of BFRP bars and flexural and shear behavior of BFRP reinforced concrete beams are needed to include BFRP reinforcement bars in the design codes. This study mainly focuses on the use of BFRP bars as internal reinforcement. The test results of the mechanical properties of BFRP reinforcement bars, the bond strength of BFRP reinforcement bars, and the flexural and shear behavior of concrete beams

  17. 外粘 AFRP 布加固 RC梁冲击试验分析%Impact Damage Test of RC Beams Strengthened with Externally Bonded AFRP Sheet

    Institute of Scientific and Technical Information of China (English)

    王兴国; 朱坤佳; 栗橋祐介

    2015-01-01

    Experimental tests were carried out respectively on the performance of non‐strengthened RC beams and RC beams strengthened with externally bonded (EB) aramid fiber reinforced polymer (AFRP) sheet under two loading methods ,the monotonically static and falling‐weight impact loading methods ,to analyze the failure process of RC beams and strain curve of EB AFRP sheet during test loading .Failure patterns and crack devel‐opment of the test beams under different impact height were compared to conclude the correlation between im‐pact height and final failure patterns of the beams .Test results showed that ,under the static loading ,the non‐strengthened beams failed as a result of steel bar yielding while the strengthened beams failed as a result of EB AFRP sheet debonding .Under the falling‐weight impact loading ,the non‐strengthened beams were destroyed as a result of steel bar yielding caused by impact damage ,while the strengthened beams were destroyed as a re‐sult of either EB AFRP sheet debonding or abrupt tension fracture .%通过单调静力和重锤冲击两种加载方式,分别对未加固梁和外粘A FRP布加固梁的性能进行试验研究,分析冲击加载时混凝土梁的破坏过程及外粘A FRP布的应变曲线。比较不同冲击高度下梁体的损伤形态和裂缝分布规律,从而得出冲击高度与梁体最终破坏形态的相关性。试验表明:在静力加载条件下,未加固梁是因钢筋屈服而破坏,加固梁是因外粘A FRP布剥离而破坏;在重锤冲击加载条件下,未加固梁是因梁体出现冲击损伤时钢筋屈服而破坏,加固梁是因梁体出现冲击损伤时外粘AFRP布可能发生端部剥离或跨中断裂而破坏。

  18. 混杂FRP复合材料性能及其加固腐蚀RC梁弯曲性能研究%Research on Material Properties of Hybrid FRP Composites and Flexural Performance for Strengthening Corroded RC Beams

    Institute of Scientific and Technical Information of China (English)

    邵运达; 李建辉

    2012-01-01

    在混杂FRP(Fiber Reinforced Polymer)复合材料单轴拉伸性能研究的基础上,通过对四根腐蚀混凝土梁的弯曲试验,研究了碳/芳纶/玻璃三种纤维层间混杂布对腐蚀混凝土梁弯曲性能的影响.结果表明:(1)混杂FRP复合材料均表现出良好的混杂效应,但碳/芳纶/玻璃三种纤维的混杂效应最优,其混杂效应系数达到0.453.(2)碳/芳纶/玻璃层间混杂纤维布加固腐蚀梁的开裂、屈服、峰值、极限荷载相比未加固腐蚀梁分别提高了14%、60%、98%和91%,而位移延性系数仅降低11%,表明混杂纤维布可显著改善腐蚀混凝土梁的弯曲性能,这将为混杂FRP复合材料加固腐蚀混凝土结构性能评估与加固设计提供参考.%Based on the uniaxial tensile properties of hybrid FRP composites, The effects of CFRP (Carbon FRP)/AFRP (Aramid FRP)/GFRP (Glass FRP) laminated hybrid fiber sheets on the flexural performance of corroded RC beam was investigated by ihe flexural experiments of four corroded RC beams, results show that (1) the hybrid FRP composites occurs good hybrid effect, and hybrid effect of CFRP/AFRP/GFRP laminated hybrid composites is optimum, its hybrid effect coefficients is 0.453. (2) compared with the un - strengthened corroded RC beam, the cracking load, yield load, maximum load and ultimate load of corroded RC beam strengthened with CFRP/AFRP/GFRP hybrid sheets is respectively increased by 14% , 60% , 98% and 91% , but the displacement ductility index is only decreased by 11 % , which indicates that the hybrid FRP sheets can improve significantly the flexural performance of corroded RC beam. The reference of the evaluating and design of corroded RC structures strengthened with hybrid FRP composites is provided.

  19. 外粘AFRP布加固RC梁耐冲击性能试验研究%Impact-resistant performance of a RC beam strengthened with externally bonded AFRP sheet

    Institute of Scientific and Technical Information of China (English)

    王兴国; 栗桥介; 朱坤佳

    2015-01-01

    设计了8根钢筋混凝土试验梁,其中2根未加固,6根在梁体受拉面采用不同类型的AFRP布进行外粘加固。然后采用重锤冲击加载试验,重点研究每种试验梁在不同冲击高度下的耐冲击性能。试验结果表明,经过外粘AFRP布加固后,混凝土梁体的挠度变形及塑性变形得到有效抑制,同时这种加固措施还可以延缓梁体裂纹开裂,减轻重锤冲击加载对梁体造成的冲击损伤。另外,AFRP布类型、冲击高度在一定程度上决定着梁体的损伤形态。由此表明,外粘AFRP布加固法能有效提高混凝土梁的耐冲击性,且AFRP布类型与梁体的耐冲击性能直接相关。%Eight RC beams were designed to test their impact-resistant behaviors.6 RC beams were strengthened with externally bonded(EB)aramid fiber reinforced polymer(AFRP)sheet.The falling-weight impact tests were focused on the anti-impact performance of each beam with different impacting heights.The test results showed that the deflection and plastic deformation of RC beams strengthened with EB AFRP sheet can be restrained effectively;at the same time,EB AFRP sheet can slow crack development and mitigate the impact damage caused by falling-weight loading;the RC beams'damage states are dependent upon the type of AFRP sheets and impacting heights to a certain level;EB AFRP sheet can obviously improve the impact-resistant performance of RC beams.

  20. 基于短纤维增韧的复合材料制孔毛刺和分层抑制研究%The Study of Chopped Fiber Reinforcement on the Prevention of Burrs and Delamination of Composite Materials in Drilling

    Institute of Scientific and Technical Information of China (English)

    孙士勇; 闫子彬; 赵延广; 杨睿; 贾振元

    2015-01-01

    由于复合材料的各向异性、树脂导热性差和层间韧性低,在二次机械加工特别是钻削制孔过程中,复合材料易产生毛刺、分层等缺陷和损伤,将短纤维层间增韧方法用于钻削损伤的抑制研究.制备低密度芳纶短纤维薄膜,采用低压接触成型工艺制备了含短纤维增韧与未增韧的复合材料层合板,进而在加工试验台上进行钻削试验.通过对试件加工孔的红外无损检测和显微观测,研究转速和短纤维增韧对复合材料制孔损伤的影响,结果表明提高转速和短纤维界面增韧可改善制孔质量.基于短纤维与基体间相互作用,揭示其增韧机理是由于短纤维在层间形成的丰富桥联抑制了分层扩展,同时短纤维与层间树脂复杂的破坏机制而产生额外的能量耗散,并讨论短纤维参数对增韧效果的影响.该方法为复合材料高质量加工提供借鉴意义.%The mechanical property of composites presents anisotropy, the low thermal conductivity of resin, and low interlaminar toughness. So the process of secondary machining composites could lead to defects like burrs and delamination, especially in drilling. The chopped fibers reinforcement technology is employed to prevent the delamination of composites in drilling process. Aramid fibers are selected to manufacture low-density thin film. The composite laminates with and without chopped fibers reinforcement are manufactured by low pressure contact forming process. And the experiments are also performed to investigate the machining surface quality. The preventing effects of increasing spindle speed and chopped fibers on the defects of composites in drilling are validated by infrared nondestructive testing and microscope observation. The reinforced mechanism is the extra energy dissipation caused by the complex failure process between chopped fibers and matrix. The influence of chopped fiber parameters on the energy dissipation is also discussed. The

  1. Experimental investigation on high temperature resistance performance of glass fiber needled composite filter material%玻璃纤维针刺复合滤料耐高温性能研究

    Institute of Scientific and Technical Information of China (English)

    赵振兴; 汪黎明; 聂换换; 蒋树军

    2014-01-01

    Glass fiber and Yilun®, aramid fiber were made to three different specifications of needle-punched composite filter material by certain proportion .The change of mechanical properties and permeability of the material were tested at 160 , 200 , 240 and 280 ℃ high temperature treatment in the 24 h and in the 200 ℃oven for 48 , 72 and 96 h.The results indicated that glass fiber composite filter material of breaking force remained more than 2 000 N after four kinds of temperature treatment .Its warp and weft elongation retention were over 80%, can satisfied the change of the temperature on the properties of filter material requirements in the working process .After the different time treatment , filter material breaking force of warp and weft remained over 80%, and kept good elongation at break .The influence of processing temperature and time on the filter material permeability is smaller .Treated with different temperature and time , the various indicators of sample which mass area ratio is 750 g/m2 were the smallest fluctuation , showed that the sample of parameter design was reasonable .%将玻璃纤维与轶纶、芳纶按一定比例混合制成三种不同规格的针刺复合滤料,测试其在160、200、240和280℃高温处理24 h和在200℃烘箱中处理48、72和96 h后的力学性能和透气性的变化,并研究了在不同试验条件下,滤料设计参数与性能之间的关系。结果表明:玻璃纤维复合滤料经四种温度处理后强力仍保持在2000 N/(5 cm ×20 cm)以上,经向和纬向伸长率保持率均在80%以上,能够满足工作过程中温度的变化对滤料性能的要求;经不同时间处理后滤料经向和纬向的断裂强力保持率均在80%以上,且断裂伸长率保持良好;处理温度和时间对滤料透气性的影响较小;经不同温度和时间处理后,面密度为750 g/m2的试样各项指标的波动幅度最小,表明该试样的参数选择比较合理。

  2. Pyroshock Protection Research for Explosive Cutting%爆炸切割冲击防护技术研究

    Institute of Scientific and Technical Information of China (English)

    关焕文; 宋文娟; 张絮

    2015-01-01

    According to safety limits of human auditory organ damage and human non-auditory injury, and considering the engineering application of explosive cutting on clearance ejection path, the damage safety limits of pilot was revealed during ejection. Pyroshock effect on pilot was simpliifed as the propagation of pyroshock in free air ifelds, and the estimation formula of pyroshock overpressure was proposed. The physical process of explosive cutting was described in order to avoid the crew from hurt by pyroshock and explosive remainders. Research was emphasized on the protector of linear shaped charge(LSC) or similar structure. Four sorts of material involving Kevlar fabric, Kevlar fabric reinforced rubber, Aramid ifber reinforced rubber and rubber, were applied to carry explosive cutting protection experiment, the protective outcome of these different material was contrasted. And then rubber was selected as the ideal protective material to do the single specimen test and dual specimen test to analyze the explosive effect. Comparison of pyroshock effect for single specimen and dual specimen was conducted.%根据人体听觉损伤安全极限和非听觉损伤安全极限,结合爆炸切割清理弹射通道技术的工程实践,确定了飞行员弹射时对爆炸冲击的损伤安全极限。将爆炸冲击波对飞行员的影响,简化成爆炸冲击波在自由场的传播对飞行员的影响,提出了爆炸冲击超压的估算公式。通过爆炸切割过程的物理描述,提出避免爆炸冲击及飞散物对乘员的损伤影响,需要重点研究切割索保护套或者类似结构,采用了芳纶布、芳纶布增强橡胶、芳纶纤维增强橡胶、橡胶等四种材料进行了爆炸切割防护试验,对4种不同材料的爆炸冲击防护效果进行了对比。最后确定采用橡胶作为防护材料,进行了单件试验和两件试验的爆炸冲击的对比,提出两件相比单件爆炸冲击的叠加影响。

  3. 玄武岩纤维布/不饱和聚酯复合材料耐老化性能%Aging-resistant performance of basalt fabrics/unsaturated polyester resin composites

    Institute of Scientific and Technical Information of China (English)

    杨越飞; 杨文斌; 徐建锋; 赖佳佳; 宋剑斌; 张欣向

    2014-01-01

    为探明玄武岩纤维/不饱和聚酯(UP,unsaturated polyester resin)复合材料的耐候性和力学性能,通过人工模拟加速气候箱对复合材料进行紫外光和冷凝处理,并测试、分析老化前后复合材料的力学性能、微观结构及化学结构的变化。力学性能测试发现,老化后的复合材料力学性能下降明显,拉伸强度、断裂伸长率、弯曲强度和弹性模量与未老化相比分别下降了35%、20%、60%和52%。扫描电子显微镜(SEM,scan electron microscope)观察老化前后的复合材料,发现包裹在纤维周围的树脂逐渐脱落,基体降解并产生碎片和横向裂纹并不断扩展形成多级开裂。傅立叶红外光谱分析(FTIR,Fourier transform infrared spectrum)测试发现,老化后的复合材料在1725 cm-1处的酯羰基吸收峰减弱,1280和1130 cm-1处酯基消失;同时,在747和702 cm-1处的邻苯型1,2-二取代吸收峰也消失。研究结果表明,不饱和聚酯上的羰基与双键或苯环上的羰基共轭体系发生变化,使酯羰基分解产生 CO;同时,聚酯发生链断裂、自由基终止等交联反应。玄武岩纤维/UP 复合材料的耐老化研究有利于延长该产品的使用寿命,对下一阶段制备玄武岩纤维/亚麻纤维混杂复合材料的耐候性和力学性能提供参考依据。%Fiber-reinforced composites made up of unsaturated polyester resin (UP) matrices reinforced with glass, carbon and aramid fibers were commonly standard structural materials in engineering fields. In recent years, basalt fibers, have recently gained an increasing attention as possible replacement of the conventional glass or carbon fibers due to their advantages in terms of environmental-friendly, cost-effective, high chemical and physical properties. In order to verify the mechanical properties of basalt fiber fabrics/UP composites, the author used the artificial simulating climate box (UV and

  4. Strengthening of monolithic floor slabs of residential buildings that have wall design sustems УСИЛЕНИЕ МОНОЛИТНЫХ ПЛИТ ПЕРЕКРЫТИЙ ЖИЛЫХ ЗДАНИЙ СТЕНОВОЙ КОНСТРУКТИВНОЙ СИСТЕМЫ

    Directory of Open Access Journals (Sweden)

    Malakhova Anna Nikolaevna

    2012-12-01

    Full Text Available The author proposes several structural solutions aimed at the reinforcement of monolithic floor slabs by means of fastening metal stripes onto the surface of slabs, laying supplementary reinforcement rods inside indents and attaching them by dowels. The author describes a force redistribution pattern identified in the course of analysis of monolithic floor slabs of buildings that have a wall design system. The author provides recommendations concerning the method of trial loading designated for the assessment of the true bearing capacity of floor slabs of residential buildings. The monolithic nature of reinforced slabs is attained by supplementary dowel connections. The dowel joint of old and new concrete elements takes the transverse shearing force in the event of bending to assure the monolithic behaviour of elements. Efficient behaviour of a monolithic slab is attained by means of a reliable connection between supplementary reinforcement rods and reinforcement rods inside slabs. Elements made of composite materials have been recently applied to strengthen reinforced concrete structures. These materials are basically composed of polymer tars and reinforcement materials (glass fiber, carbon and aramid fibers. Polymer sheets, stripes and fabric replace metal sheets, stripes and reinforcing meshes.Предложены конструктивные решения по усилению монолитных плит перекрытия: путем закрепления к поверхности плиты металлических полос и путем прокладки дополнительных арматурных стержней в штрабах со шпонками. Показано использование механизма перераспределения усилий при расчете монолитных плит перекрытия в зданиях стеновой конструктивной системы.

  5. PREFACE Proceedings of the XIV International Conference on Small-Angle Scattering, SAS-2009

    Science.gov (United States)

    King, Stephen; Terrill, Nicholas

    2010-10-01

    nine awards were presented at the conference. The Lifetime Achievement, or 'Andre Guinier', Award, given to those who have made a sustained and recognised contribution to the development or application of Small-Angle Scattering, went to Vittorio Luzzati, Emeritus Research Scientist at the Centre de Génétique Moléculaire du CNRS, France. Dr Luzzati has had a long and distinguished career in X-ray scattering publishing over 170 research papers - 10 in Nature - which have so far accumulated over 3500 citations. The award for 'Excellence in SAS Technical/Instrumental Development' went to J Polte, BAM, Germany, for 'New insights into nucleation and growth processes of gold nanoparticles derived via coupled in-situ methods'. That for 'Excellence in the Theoretical Development of SAS' went to C Gommes, Liege, Belgium, for 'SAXS Data Analysis of Ordered and Disordered Morphologies with Gaussian Random Field Models'. B Pauw, Technical University, Denmark, received the award for 'Excellence in the Application of SAS' for work on 'Strain-induced Internal Fibrillation of Aramid Filaments'. And the award for 'Excellence in the Communication of SAS Science' went to J G Grossmann, Liverpool, UK, for his talk on 'Probing the Structure of Biological Macromolecules in the Gas Phase'. A Hexemer, LBNL, USA, won the prize for the 'Best Poster in Technical/Instrumental Development' for 'SAXS/WAXS using a Multilayer Monochromator'. The prize for 'Best Poster in Theoretical Development' went to S Haas, Helmholtz Centre Berlin, Germany, for 'Simultaneous structure and chemical nano-analysis of an efficient frequency upconversion glass-ceramic by ASAXS'. And in a remarkable 'double', the prizes for 'Best Poster for Application in Life Sciences' and 'Best Poster for Application in Physical Sciences' went to A Maerten and J Prass, respectively, both from MPI Golm, Germany, for their work on 'SAXS studies of human tooth dentine: analysis of a spatially inhomogeneous and varying bio