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. Antimicrobial Polymeric Materials; Cellulose and m- Aramid Composite Fibers

    Directory of Open Access Journals (Sweden)

    Jaewoong Lee, Ph.D.

    2007-12-01

    Full Text Available Cellulose and m-aramid were dissolved in an ionic liquid, and dry-jet wet spinning was employed to prepare composite fibers which could be rendered antimicrobial through exposure to chlorine bleach. The small domains of the m-aramid allowed a much higher accessibility and degree of chlorination than has been reported even for 100% m-aramid fibers. The mechanical properties including denier, tenacity, and strain at break were evaluated. The chlorinated composite fiber inactivated both Gram-positive and Gram-negative bacteria. The antimicrobial activity was retained after repeated washing and recharging.

  3. 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...

  4. Analysing the nanoporous structure of aramid fibres

    DEFF Research Database (Denmark)

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

    2010-01-01

    for validity against the computed scattering pattern for a simulated nanostructure, after which it is used to fit the scattering from the void structure of commercially available heat-treated poly(p-phenylene terephtalamide) fibre and its as-spun precursor fibre. The application shows a reasonable fit...... fibrillar scattering on the scattering pattern. The fit to the scattering pattern of as-spun aramid fibre is improved by the introduction of the large scatterers, while the fit to the scattering pattern obtained from the heat-treated fibre improves when an orientation distribution is taken into account. It...... is concluded that, as a result of the heat treatment, the average width and length of the scatterers increase....

  5. 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.

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

    International Nuclear Information System (INIS)

    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 SiO2/shape memory polyurethane (SiO2/SMPU) hybrid. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that the synthesized SiO2/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

  7. 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.

  8. 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

  9. 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.

  10. Aramid nanofiber-functionalized graphene nanosheets for polymer reinforcement

    Science.gov (United States)

    Fan, Jinchen; Shi, Zixing; Zhang, Lu; Wang, Jialiang; Yin, Jie

    2012-10-01

    Aramid macroscale fibers, also called Kevlar fibers, exhibit extremely high mechanical performance. Previous studies have demonstrated that bulk aramid macroscale fibers can be effectively split into aramid nanofibers (ANFs) by dissolution in dimethylsulfoxide (DMSO) in the presence of potassium hydroxide (KOH). In this paper, we first introduced the ANFs into the structure of graphene nanosheets through non-covalent functionalization through π-π stacking interactions. Aramid nanofiber-functionalized graphene sheets (ANFGS) were successfully obtained by adding the graphene oxide (GO)/DMSO dispersion into the ANFs/DMSO solution followed by reduction with hydrazine hydrate. The ANFGS, with ANFs absorbed on the surface of the graphene nanosheets, can be easily exfoliated and dispersed in N-methyl-2-pyrrolidone (NMP). Through a combination of these two ultra-strong materials, ANFs and graphene nanosheets (GS), the resultant ANFGS can act as novel nanofillers for polymer reinforcement. We used the ANFGS as an additive for reinforcing the mechanical properties of poly(methyl methacrylate) (PMMA). With a loading of 0.7 wt% of the ANFGS, the tensile strength and Young's modulus of the ANFGS/PMMA composite film approached 63.2 MPa and 3.42 GPa, which are increases of ~84.5% and ~70.6%, respectively. The thermal stabilities of ANFGS/PMMA composite films were improved by the addition of ANFGS. Additionally, the transparencies of the ANFGS/PMMA composite films have a degree of UV-shielding due to the ultraviolet light absorption of the ANFs in the ANFGS.Aramid macroscale fibers, also called Kevlar fibers, exhibit extremely high mechanical performance. Previous studies have demonstrated that bulk aramid macroscale fibers can be effectively split into aramid nanofibers (ANFs) by dissolution in dimethylsulfoxide (DMSO) in the presence of potassium hydroxide (KOH). In this paper, we first introduced the ANFs into the structure of graphene nanosheets through non

  11. 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.

  12. 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.

  13. 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.

  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. Crushing behavior of hybrid hexagonal/octagonal cellular composite system: Aramid/carbon hybrid composite

    International Nuclear Information System (INIS)

    Highlights: • Replacing the carbon/epoxy by aramid/epoxy did not affect the peak load. • The post crush force efficiency showed improvements by using aramid/epoxy packing. • The specific energy showed improvement by using aramid/epoxy packing. • Brittle fracture dominated the crush behavior for the carbon/epoxy packing. • Plastic deformation without fracture was observed for aramid/epoxy packing. - Abstract: In the current paper a series of experiments were conducted to assess the crashworthiness of cellular hexagonal/octagonal composite device. Each device composed of 6 cells of carbon fiber reinforced composite (CFRP). Different arrangements of the octagonal and the hexagonal cells were studied. All the configurations were filled with foam. The main objective of the current paper was to examine the effect of using the aramid/epoxy instead of the carbon/epoxy layers to pack the device. The specimens were tested under quasi-static compression loading up to complete crushing. The results showed that the packing material did not have a significant effect for the case of all hexagonal open cells. For the other configurations, introducing the aramid/epoxy instead of the carbon/epoxy showed improvements in the stroke efficiency, the crush load stability, the average crushing load, the energy absorbed and the specific energy absorption. In order to understand the mechanisms that led to this improvement, the packing material were examine after crushing using an optical microscope and a scanning electron microscope (SEM). For the carbon/epoxy, the images showed many failure mechanisms whereas, for the aramid/epoxy, only delamination was noted

  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. 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)

  1. Accelerated Creep Testing of High Strength Aramid Webbing

    Science.gov (United States)

    Jones, Thomas C.; Doggett, William R.; Stnfield, Clarence E.; Valverde, Omar

    2012-01-01

    A series of preliminary accelerated creep tests were performed on four variants of 12K and 24K lbf rated Vectran webbing to help develop an accelerated creep test methodology and analysis capability for high strength aramid webbings. The variants included pristine, aged, folded and stitched samples. This class of webbings is used in the restraint layer of habitable, inflatable space structures, for which the lifetime properties are currently not well characterized. The Stepped Isothermal Method was used to accelerate the creep life of the webbings and a novel stereo photogrammetry system was used to measure the full-field strains. A custom MATLAB code is described, and used to reduce the strain data to produce master creep curves for the test samples. Initial results show good correlation between replicates; however, it is clear that a larger number of samples are needed to build confidence in the consistency of the results. It is noted that local fiber breaks affect the creep response in a similar manner to increasing the load, thus raising the creep rate and reducing the time to creep failure. The stitched webbings produced the highest variance between replicates, due to the combination of higher local stresses and thread-on-fiber damage. Large variability in the strength of the webbings is also shown to have an impact on the range of predicted creep life.

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

    International Nuclear Information System (INIS)

    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, O2 plasma and N2 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 influence on

  4. 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.

  5. 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.

  6. 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...

  7. 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...

  8. 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.

  9. 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

  10. 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)

  11. 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.

  12. 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.

  13. 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.

  14. Plasma penetration depth and mechanical properties of atmospheric plasma-treated 3D aramid woven composites

    International Nuclear Information System (INIS)

    Three-dimensional aramid woven fabrics were treated with atmospheric pressure plasmas, on one side or both sides to determine the plasma penetration depth in the 3D fabrics and the influences on final composite mechanical properties. The properties of the fibers from different layers of the single side treated fabrics, including surface morphology, chemical composition, wettability and adhesion properties were investigated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement and microbond tests. Meanwhile, flexural properties of the composites reinforced with the fabrics untreated and treated on both sides were compared using three-point bending tests. The results showed that the fibers from the outer most surface layer of the fabric had a significant improvement in their surface roughness, chemical bonding, wettability and adhesion properties after plasma treatment; the treatment effect gradually diminished for the fibers in the inner layers. In the third layer, the fiber properties remained approximately the same to those of the control. In addition, three-point bending tests indicated that the 3D aramid composite had an increase of 11% in flexural strength and 12% in flexural modulus after the plasma treatment. These results indicate that composite mechanical properties can be improved by the direct fabric treatment instead of fiber treatment with plasmas if the fabric is less than four layers thick

  15. 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

  16. 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.

  17. Surface silverized meta-aramid fibers prepared by bio-inspired poly(dopamine) functionalization.

    Science.gov (United States)

    Wang, Wencai; Li, Runyuan; Tian, Ming; Liu, Li; Zou, Hua; Zhao, Xiuying; Zhang, Liqun

    2013-03-01

    A facile method was developed to fabricate highly electrically conductive aramid fibers. The immobilization of silver nanoparticles on the surface of polymetaphenylene isophthamide (PMIA) fibers was carried out by the functionalization of the PMIA fibers with poly(dopamine), followed by electroless silver plating. The poly(dopamine) (PDA) layer was deposited on the PMIA surface by simply dipping the PMIA substrate into an alkaline dopamine solution. The silver ions can be chemically bound to the catechol and indole functional groups in PDA. The silver ions were reduced into silver nanoparticles by using glucose as the reducing agent, resulting in a distinct silver layer on the PMIA surface. The obtained silver deposit was homogeneous and compact. The chemical composition of the modified PMIA fibers was studied by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS), and the crystalline structure of the silver-coated PMIA fibers was characterized by powder X-ray diffraction (XRD). The topography of the modified PMIA fibers was investigated by scanning electron microscopy (SEM). The four-point probe resistivity meter was used to study the electrical resistivity of the silver-coated PMIA fibers, the results indicated that the electrical resistivity could be as low as 0.61 mΩ·cm, with a controllable silver content, and a satisfactory stability by ultrasonic treatment. PMID:23465083

  18. Surface treatment of para-aramid fiber by argon dielectric barrier discharge plasma at atmospheric pressure

    International Nuclear Information System (INIS)

    Highlights: ► We use DBD technique to modify the surface of Kelvar29 fibers. ► The changed parameters include treated power, time and argon flux. ► There exists an optimum experimental condition of plasma treatment. ► Adhesion and wettability properties of fibers are improved through plasma treatment. - Abstract: This paper is focused on influence of argon dielectric barrier discharge (DBD) plasma on the adhesive performance and wettability of para-aramid fibers and three parameters including treated power, exposure time and argon flux were detected. The interfacial shear strength (IFSS) was greatly increased by 28% with 300 W, 60 s, 2 L min−1 argon flux plasma treatment. The content of oxygen atom and oxygen-containing polar functional groups were enhanced after the argon plasma treated, so as the surface roughness, which contributed to the improvement of surface wettability and the decrease of contact angle with water. However, long-time exposure, exorbitant power or overlarge argon flux could partly destroy the prior effects of the treatment and damage the mechanical properties of fibers to some degree.

  19. 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

  20. 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.

  1. 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)

  2. 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)

  3. In situ synthesis and hydrothermal crystallization of nanoanatase TiO2 -SiO2 coating on aramid fabric (HTiSiAF) for UV protection.

    Science.gov (United States)

    Deng, Hui; Zhang, Hongda

    2015-10-01

    TiO2 -SiO2 thin film was prepared by sol-gel method and coated on the aramid fabric to prepare functional textiles. The aramid fabric was dipped and withdrawn in TiO2 -SiO2 gel and hydrothermal crystallization at 80(°) C, then its UV protection functionality was evaluated. The crystalline phase and the surface morphology of TiO2 -SiO2 thin film were characterized using SEM, XRD, and AFM respectively. SEM showed hydrothermal crystallization led to a homogeneous dispersion of anatase nonocrystal in TiO2 -SiO2 film, and XRD suggested the mean particle size of the formed anatase TiO2 was less than 30 nm. AFM indicated that hydrothermal treatment enhanced the crystallization of TiO2 . UV protection analysis suggested that the hydrothermally treated coated textile had a better screening property in comparison with TiO2 -SiO2 gel and native aramid fabric. PMID:26303384

  4. 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.

  5. 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.

  6. 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

  7. 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%

  8. 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。

  9. Antimicrobial and antitumor activity of platinum and palladium complexes of novel spherical aramides nanoparticles containing flexibilizing linkages: Structure-property relationship

    Science.gov (United States)

    Elhusseiny, Amel F.; Hassan, Hammed H. A. M.

    2013-02-01

    Square planar Pd (II) and octahedral Pt (IV) complexes with novel spherical aramides nanoparticles containing flexible linkages ligands have been synthesized and characterized using analytical and spectral techniques. The synthesized complexes have been tested for their antimicrobial activity using Kirby-Bauer disc diffusion method. The antitumor activity has been performed using liver carcinoma (HEPG2), breast carcinoma (MCF7) and colon carcinoma (HCT 116) cell lines. Palladium complexes of polyamides containing sulfones showed the highest potency as antibacterial and antifungal agents. Platinum complexes containing sulfone and ether flexible linkages and chloro groups exhibited high potency as antitumor and antimicrobial agents. The uniform sizes of these nanomaterials could find biological uses such as immune assay and other medical purposes.

  10. Caracterização térmica de fios de poliaramida Characterization of aramid yarns

    Directory of Open Access Journals (Sweden)

    Nicolas T. Boukouvalas

    2007-12-01

    Full Text Available A poliaramida (aramida é um polímero de alto desempenho, cujas principais características são a elevada tenacidade, baixo alongamento e resistência ao calor. Devido ao desconhecimento do mercado em geral a respeito de materiais têxteis, metodologia de ensaios e a nomenclatura utilizada nesta família de materiais, invariavelmente ocorrem erros na escolha da qualidade do produto a adquirir. O uso de equipamentos inadequados para caracterização deste material pode levar a erros de interpretação. Este trabalho visa a melhor informar sobre este mercado, e discutir análises já realizadas. O gráfico tensão x deformação da poliaramida obtido em equipamento e garras corretas é linear, o que não ocorre se o equipamento de tração equipado com garras não for preparado para ensaios de tração de fios têxteis. Em análise termogravimétrica, verificou-se que a taxa de elevação de temperatura mais adequada é de aproximadamente 3 °C/min. A degradação da poliaramida se inicia a aproximadamente 510 °C, pela decomposição térmica das ligações simples, seguida da decomposição térmica dos anéis aromáticos a aproximadamente 525 ºC, sendo que a temperatura de degradação térmica completa ocorre a cerca de 575 °C.Polyaramid (aramid is a high performance polymer, whose main characteristics are its high tenacity, low elongation and good heat resistance. Owing to the lack of familiarity of the market with textile materials, methods of analysis and the nomenclature used for this family of materials, errors in the choice of the product quality are common. The inadequate use of equipment in the characterization of this material may lead to errors of interpretation. This work aims to inform about this market, and discuss results of previous analyses. A stress x strain graph of polyaramid is linear if obtained with adequate equipment and fixtures, which is not the case if the equipment and fixtures are not suitable for textile yarns

  11. 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

  12. 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。

  13. 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.

  14. 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.

  15. 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.

  16. 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.)

  17. 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

  18. 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...

  19. Composite material based on aramid fibers and polysiloxane matrix modified by ydroxapatite nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Sochor, M.; Balík, Karel; Suchý, Tomáš; Sucharda, Zbyněk; Černý, Martin

    Ostrava: VŠB - Technical University of Ostrava, Faculty of Mechanical Engineering , Department of Mechanics of Materials, 2008 - (Fuxa, J.), s. 219-222 ISBN 978-80-248-1774-3. [Experimental Stress Analysis (EAN) 2008. International scientific conference /46./. Horní Bečva (CZ), 02.06.2008-05.06.2008] R&D Projects: GA ČR(CZ) GA106/06/1576 Institutional research plan: CEZ:AV0Z30460519 Keywords : composite material * hydroxyapatite * mechanical behavior Subject RIV: JI - Composite Materials

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Development and Properties of Hybrid Composites

    OpenAIRE

    G.Meenambika Bai,; H.Raghavendra Rao

    2014-01-01

    The Flexural and tensile properties and Scanning electron Microscope analysis of Aramide/Onion/Glass fibers Reinforced Epoxy Reinforced composites are studied. The effect of the Aramide/Onion/Glass fibers on these properties was also studied. These properties found to be higher when glass fibers were used in the reinforced composites. The elimination of amorphous hemi-cellulose leading to higher crystallinity of the Aramide/ Onion/Glass fibers may be responsible for these obse...

  8. [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

  9. Kevlar, the 'universal fiber'. Properties and applications in industry, sports and recreation. Kevlar - die 'Alleskoenner-Faser'. Eigenschaften und Anwendung in Industrie, Sport und Freizeit

    Energy Technology Data Exchange (ETDEWEB)

    Oehrl, S.

    1988-12-01

    This article gives a survey of the history, properties and applications of 'Kevlar' aramide fibers. For example, the 'Kevlar' para-aramide fiber is used in compound materials in ship-, aircraft- and vehicle construction. 'Kevlar' is used as a replacement for asbestos, for example in brakes, clutches and seals or as rubber reinforcement (tyres, conveyor belts, hoses). The aramide fibers also offer manufacturers of ropes, hawsers and cables a near ideal range of properties. (MM).

  10. 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...

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

    OpenAIRE

    K. Jamroziak; Bocian, M

    2008-01-01

    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 o...

  12. 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.

  13. Natural Curaua Fiber-Reinforced Composites in Multilayered Ballistic Armor

    Science.gov (United States)

    Monteiro, Sergio Neves; Louro, Luis Henrique Leme; Trindade, Willian; Elias, Carlos Nelson; Ferreira, Carlos Luiz; de Sousa Lima, Eduardo; Weber, Ricardo Pondé; Miguez Suarez, João Carlos; da Silva Figueiredo, André Ben-Hur; Pinheiro, Wagner Anacleto; da Silva, Luis Carlos; Lima, Édio Pereira

    2015-10-01

    The performance of a novel multilayered armor in which the commonly used plies of aramid fabric layer were replaced by an equal thickness layer of distinct curaua fiber-reinforced composites with epoxy or polyester matrices was assessed. The investigated armor, in addition to its polymeric layer (aramid fabric or curaua composite), was also composed of a front Al2O3 ceramic tile and backed by an aluminum alloy sheet. Ballistic impact tests were performed with actual 7.62 caliber ammunitions. Indentation in a clay witness, simulating human body behind the back layer, attested the efficacy of the curaua-reinforced composite as an armor component. The conventional aramid fabric display a similar indentation as the curaua/polyester composite but was less efficient (deeper indentation) than the curaua/epoxy composite. This advantage is shown to be significant, especially in favor of the lighter and cheaper epoxy composite reinforced with 30 vol pct of curaua fiber, as possible substitute for aramid fabric in multilayered ballistic armor for individual protection. Scanning electron microscopy revealed the mechanism associated with the curaua composite ballistic performance.

  14. 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.

  15. 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,…

  16. 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.

  17. 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.

  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. Effective crack lengths by compliance measurement for ARALL-2 laminates

    Science.gov (United States)

    Wilson, Christopher D.; Wilson, Dale A.

    1991-01-01

    As a means of determining a stress intensity factor solution, the compliance properties of an ARALL-2 laminated-sheet composite were investigated. Fatigue crack growth rate (FCGR) tests were conducted on middle crack tension (MT) specimens fabricated from a layup consisting of three sheets of 2024-T3 aluminum bonded together with unidirectional aramid fibers embedded in epoxy. Excellent fatigue crack growth properties are obtained by the presence of unbroken aramid fibers in the wake of the crack tip. These unbroken fibers act as a bridging mechanism to inhibit further crack growth. To quantify the effect of maximum fatigue load on compliance, a series of FCGR tests were performed. Effective crack lengths were determined to be at least 10 mm shorter than surface measured crack lengths for a 76-mm-wide specimen. The bridging zone was estimated to be at least 5 mm. Compliance and stress intensity factor as functions of effective crack length were determined.

  20. Biocompatibility optimization of fabric composites by calcium phosphates

    Czech Academy of Sciences Publication Activity Database

    Sochor, M.; Balík, Karel; Suchý, Tomáš; Sucharda, Zbyněk

    Vol. 47. Liberec : Technical University of Liberec, 2009 - (Marvalová, B.; Petríková, I.; Čapek, L.), s. 28-31 ISBN 978-80-7372-483-2. [Experimental Stress Analysis 2009. Sychrov (CZ), 08.06.2009-11.06.2009] R&D Projects: GA ČR(CZ) GA106/06/1576 Institutional research plan: CEZ:AV0Z30460519 Keywords : polydimethylsiloxane * aramid * hydroxyapatite Subject RIV: JI - Composite Materials

  1. 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.

  2. 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...

  3. 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 ...

  4. 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...

  5. 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.

  6. 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...

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

    OpenAIRE

    Omar I. Abdelkarim; Mohamed A. ElGawady

    2015-01-01

    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...

  8. 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.

  9. 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...

  10. 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...

  11. 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...

  12. Studies into the detection of buried objects (particularly optical fibres) in saturated sediment. Part 1: background

    OpenAIRE

    Leighton, T.G.; Evans, R.C.P.

    2007-01-01

    Damaged submarine fibre optic telecommunication cables have, in the past, been located by the use of remotely operated underwater vehicles. These are fitted with sensors which have the capability to detect the metal shielding in the metallic cores used in cable technology. However, it is anticipated that the next generation of cables will have a much reduced metal content, their strength being derived from synthetic materials such as aramid fibres. Such structures will have gre...

  13. 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...

  14. 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.

  15. FIRE PROTECTION OF TIMBER STRUCTURES STRENGTHENED WITH FRP MATERIALS

    OpenAIRE

    Radek Zigler; Marek Pokorný

    2015-01-01

    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...

  16. 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

  17. 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.

  18. 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.

  19. 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

  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. 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.

  3. 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.

  4. 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...... properties 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...

  5. 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.

  6. Ballistic properties of bidirectional fiber/resin composites

    International Nuclear Information System (INIS)

    The aim 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) plainly woven fabric 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 chosen was, which is applicable for personal ballistic protection and the ultimate resin content range 20 - 50 vol.%. Ballistic test of the composites has shown that the best results exhibit HPPE based composites; aramid based composites have been the second best followed by the polyamide based composites. The worst results have been shown by the glass based composites. All composites with lower resin content (20%) have performed much better than their counterparts with higher resin content (50 %).The plot of the ballistic strength (V50) versus areal weight has shown a linear increase of V50 with the increase of areal weight. The ballistic strength of the composites is highly dependant on the fiber/resin ratio and increases with the increase of the fiber content. (Author)

  7. Comparative hazards of chrysotile asbestos and its substitutes: A European perspective.

    Science.gov (United States)

    Harrison, P T; Levy, L S; Patrick, G; Pigott, G H; Smith, L L

    1999-08-01

    Although the use of amphibole asbestos (crocidolite and amosite) has been banned in most European countries because of its known effects on the lung and pleura, chrysotile asbestos remains in use in a number of widely used products, notably asbestos cement and friction linings in vehicle brakes and clutches. A ban on chrysotile throughout the European Union for these remaining applications is currently under consideration, but this requires confidence in the safety of substitute materials. The main substitutes for the residual uses of chrysotile are p-aramid, polyvinyl alcohol (PVA), and cellulose fibers, and it is these materials that are evaluated here. Because it critically affects both exposure concentrations and deposition in the lung, diameter is a key determinant of the intrinsic hazard of a fiber; the propensity of a material to release fibers into the air is also important. It is generally accepted that to be pathogenic to the lung or pleura, fibers must be long, thin, and durable; fiber chemistry may also be significant. These basic principles are used in a pragmatic way to form a judgement on the relative safety of the substitute materials, taking into account what is known about their hazardous properties and also the potential for uncontrolled exposures during a lifetime of use (including disposal). We conclude that chrysotile asbestos is intrinsically more hazardous than p-aramid, PVA, or cellulose fibers and that its continued use in asbestos-cement products and friction materials is not justifiable in the face of available technically adequate substitutes. PMID:10417355

  8. Comparação do comportamento à flexão com restrições à deflexão de placas de compósitos de matriz polimérica epoxídica em função do tipo de fibra de reforço Comparison of the bending behavior with restrained deflection of epoxy matrix composite plates as a function of the reinforcement fiber

    Directory of Open Access Journals (Sweden)

    Willy A. de Morais

    2003-07-01

    Full Text Available Placas finas de compósitos de matriz polimérica epoxídica reforçada por fibras de vidro, carbono ou aramida, bem como placas de um compósito híbrido vidro-aramida, foram submetidas a ensaios de flexão. As condições de fixação dos corpos de prova foram tais que o ensaios foram realizados com deflexão restrita. Os resultados experimentais obtidos para a deflexão máxima dos compósitos puderam ser qualitativamente previstos usando-se o método de balanço de energia de Ritz. Os compósitos reforçados por fibras de carbono apresentaram os maiores valores de energia de iniciação e de força máxima, o que foi atribuído às altas propriedades intrínsecas das fibras. As propriedades específicas do compósito híbrido foram superiores às dos compósitos apenas com fibras de vidro ou fibras aramidas. Este efeito sinergístico indicou um projeto adequado na fabricação deste compósito. O modo de falha macroscópico de todos os compósitos foi semelhante. Na face frontal, a interação compósito - punção seguiu o comportamento previsto pela Lei de Hertz. Na face posterior, houve preferencialmente delaminação.Thin plates of epoxy resin matrix composites reinforced with glass, carbon and aramid fibers, as well as a plate from a hybrid glass-aramid composite, were submitted to flexure tests. The specimens were fixed in order to conduct the testes under restricted conditions of deflection. The experimental results of the maximum deflection agreed qualitatively with the Ritz method of energy balance. Carbon fiber reinforced composites showed the highest values for the initiation energy and for the maximum force. Both results were attributed to the high intrinsic properties of carbon fibers. The specific properties of the hybrid composite were higher than the properties of the glass or aramid reinforced composites. This synergistic effect is indicative of a properly designed hybrid composite. The macroscopic failure mode of all

  9. 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

  10. Knitting Technologies And Tensile Properties Of A Novel Curved Flat-Knitted Three-Dimensional Spacer Fabrics

    Directory of Open Access Journals (Sweden)

    Li Xiaoying

    2015-09-01

    Full Text Available This paper introduces a knitting technique for making innovative curved three-dimensional (3D spacer fabrics by the computer flat-knitting machine. During manufacturing, a number of reinforcement yarns made of aramid fibres are inserted into 3D spacer fabrics along the weft direction to enhance the fabric tensile properties. Curved, flat-knitted 3D spacer fabrics with different angles (in the warp direction were also developed. Tensile tests were carried out in the weft and warp directions for the two spacer fabrics (with and without reinforcement yarns, and their stress–strain curves were compared. The results showed that the reinforcement yarns can reduce the fabric deformation and improve tensile stress and dimensional stability of 3D spacer fabrics. This research can help the further study of 3D spacer fabric when applied to composites.

  11. 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 ...

  12. A process to separate the sodium from radioactive aqueous effluents resulting from spent fuels reprocessing

    International Nuclear Information System (INIS)

    This invention concerns the separation of sodium from radioactive aqueous effluents resulting from spent fuels reprocessing. The sodium separation is carried out with the use of charged porous membranes methods and of nano-filtration. Membranes are formed by a polymer layer as poly-aramids, sulfonated poly-sulfone or ionomer containing fluorine. The tangential filtration technology limits the accumulation phenomenon of the retained species at the membrane surface and is then used preferentially. In order to obtain the wished retention rates, the pH value of the aqueous effluent, the temperature, the pressure and the flow rates have to be adjusted. The membrane retention rate for the radioactive elements can be improved by the complexation with the use of chelating agents of one or several elements present in the effluent. Radioactive effluents without sodium can be then stored in vitreous matrices. (O.M.). 4 refs., 26 figs., 4 tabs

  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. Design and performance of a shape memory alloy-reinforced composite aerodynamic profile

    International Nuclear Information System (INIS)

    Based on a shape memory alloy (SMA)-reinforced composite developed separately, the applicability of the composite has been demonstrated through realization of a realistically scaled aerodynamic profile of around 0.5 m span by 0.5 m root chord whose skins had been made from this composite. The design, manufacturing and assembly of the profile are described. The curved skins were manufactured with two layers of SMA wires integrated into the layup of aramid fibre prepregs. All SMA wires were connected such that they can be operated as individual sets of wires and at low voltages, similar to the conditions for electrical energy generation in a real aircraft. The profile was then mounted on a vibration test rig and excited by a shaker at its tip which allowed the dynamic performance of the profile to be validated under internal actuation conditions generated through the SMA wires

  15. Prompt response and durability of polymer ablation from synthetic fibers irradiated by thermal plasmas for arc resistant clothes

    International Nuclear Information System (INIS)

    Interactions between thermal plasmas and synthetic fibers such as polyamide, polyester, phenol and aramid were investigated by thermal plasma irradiation technique. Understanding the above interactions is crucial to design effective flame retardant synthetic fiber clothes with arc resistance to protect a human from arc flash accidents. To investigate the interactions, an Ar inductively coupled thermal plasma (ICTP) was used instead of the arc discharge because the ICTP has high controllability and no contamination. The ICTP irradiation raises polymer ablation in case of polyamide and polyester. Two features of the polymer ablation such as prompt response and durability were fundamentally investigated from viewpoint of shielding the heat flux. It was found that polyamide fiber has both a high prompt response and a long durability.

  16. Problems and solutions in using short fiber reinforcements

    International Nuclear Information System (INIS)

    The performance potential and current technical and economic shortcomings of short fiber reinforcements are assessed. Short fibers include (1) monocrystalline whiskers, such as those of silicon carbide, which offer the highest tensile strength and elastic modulus achievable but remain the most expensive reinforcement alternative, (2) microfibers, which are of lower cost than whiskers and have a polycrystalline microstructure whose imperfections significantly lower a given material's strength, (3) processed mineral fibers, which are produced by fiberizing blast furnace slag and are of low cost and glass fiber-like performance, (4) natural mineral fibers such as Wollastonite, and (5) chopped and milled fibers, whose precursors are continuous glass, carbon/graphite and aramid polymer fibers, as well as metal fibers. Attention is given to the mixing and blending and fiber orientation problems encountered in the use of short fibers, and recommendations are made toward their solution

  17. 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)

  18. 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.

  19. Determination of CTODC in Fibre Metal Laminates by ASTM and Schwalbe Methods

    Directory of Open Access Journals (Sweden)

    Castrodeza E.M.

    2002-01-01

    Full Text Available Fibre Metal Laminates (FMLs have arisen as a demand of the aeronautical industry to use thin sheets with high resistance to fatigue crack growth, high damage tolerance, corrosion resistance and high specific strength. Considering these requirements, FMLs are an advantageous choice when compared to metal alloys currently used. In order to employ FMLs in aircraft structures, designers must hold a deep knowledge of a wide set of their properties including fracture toughness. The aim of this work was to evaluate the available methodologies to measure fracture toughness at instability (CTOD C in unidirectional fibre metal laminates reinforced with aramid fibres (ARALL®. To achieve this, tests were performed to obtain traditional and Schwalbe CTODs by using experimental ASTM based techniques, especially adapted to these laminates. Results achieved point out that Schwalbe method is more appropriate and also that there are differences between both CTOD parameters.

  20. 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.

  1. Low temperature properties of carbon fibre reinforced expoxide resins

    International Nuclear Information System (INIS)

    This chapter reports on the testing of two epoxide resin systems: the semiflexible epoxy CY221/HY979 and the rigid epoxy LY556/HY917. Discusses selection of materials and main properties; evaluation and stress analysis of different specimens; sample manufacture; test equipment for low temperatures; results of mechanical and thermal tests; and investigation on lugs for a cryogenic tank for space application. Finds that most mechanical properties of unidirectional Carbon Fiber Reinforced Composites show higher values at low temperatures. Concludes that interlaminar shear strength appears to reach a maximum at 218K; and that fatigue tests with glass-, carbon- and aramid composites (Lugs) show a remarkable increase in fatigue life at low temperatures relative to room temperature

  2. 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...

  3. Low temperature properties of carbon fibre reinforced epoxide resins

    International Nuclear Information System (INIS)

    The material properties of carbon fibre reinforced epoxide resins are studied for applications at room temperature, as well as the high ratio of strength and stiffness to specific weight in structures. The test equipment, the specimens and the manufacturing procedures are described. Test equipment for low temperatures are illustrated in photos and charts. Results of mechanical and thermal tests are given and an investigation on lugs for a cryogenic tank for space application is proposed. Conclusions include the fact that most mechanical properties of unidirectional carbon fibre reinforced composites show higher values at low temperatures. Results of fatigue tests with glass-, carbon- and aramid compositions (Lugs) show a remarkable increase in fatigue life at low temperatures relative to room temperature

  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. 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

  6. Copper-coated textiles: armor against MDR nosocomial pathogens.

    Science.gov (United States)

    Irene, Galani; Georgios, Priniotakis; Ioannis, Chronis; Anastasios, Tzerachoglou; Diamantis, Plachouras; Marianthi, Chatzikonstantinou; Philippe, Westbroek; Maria, Souli

    2016-06-01

    Soft surfaces in the health-care setting harbor potentially pathogenic bacteria and fungi that can be transferred to patients and personnel. We evaluated the in vitro antimicrobial efficacy of two types of innovative copper-coated textiles against a variety of nosocomial multi-drug resistant (MDR) pathogens. Five isolates each of MDR Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Enterococcus faecium as well as three Candida parapsilosis were tested. The antimicrobial activity of copper-coated para-aramide and copper-coated polyester swatches was compared to that of non-copper coated controls using a quantitative method. Reduction of viable colonies by >3log10 from starting inoculum was characterized as bactericidal activity. No viable colonies of S. aureus, P. aeruginosa, E. faecium and C. parapsilosis were recovered after the first hour of contact while for A. baumannii, no viable colonies were recovered after only 15min of contact with either type of copper-coated textiles. Copper-coated para-aramide exhibited a bactericidal effect at 15min of contact with A. baumannii, at 1h with S. aureus, P. aeruginosa, E. faecium and C. parapsilosis and at 3h with K. pneumoniae. Copper-coated polyester was bactericidal at 15min of contact for A. baumannii and at 1h for the other species tested. Both copper-coated textiles exhibited a rapid and significant antimicrobial effect. Antimicrobial textiles may have a role in the arsenal of strategies aiming to reduce environmental contamination in the health-care setting. PMID:27055400

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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%.

  13. Hypervelocity impact testing of advanced materials and structures for micrometeoroid and orbital debris shielding

    Science.gov (United States)

    Ryan, Shannon; Christiansen, Eric L.

    2013-02-01

    A series of 66 hypervelocity impact experiments have been performed to assess the potential of various materials (aluminium, titanium, copper, stainless steel, nickel, nickel/chromium, reticulated vitreous carbon, silver, ceramic, aramid, ceramic glass, and carbon fibre) and structures (monolithic plates, open-cell foam, flexible fabrics, rigid meshes) for micrometeoroid and orbital debris (MMOD) shielding. Arranged in various single-, double-, and triple-bumper configurations, screening tests were performed with 0.3175 cm diameter Al2017-T4 spherical projectiles at nominally 6.8 km/s and normal incidence. The top performing shields were identified through target damage assessments and their respective weight. The top performing candidate shield at the screening test condition was found to be a double-bumper configuration with a 0.25 mm thick Al3003 outer bumper, 6.35 mm thick 40 PPI aluminium foam inner bumper, and 1.016 mm thick Al2024-T3 rear wall (equal spacing between bumpers and rear wall). In general, double-bumper candidates with aluminium plate outer bumpers and foam inner bumpers were consistently found to be amongst the top performers. For this impact condition, potential weight savings of at least 47% over conventional all-aluminium Whipple shields are possible by utilizing the investigated materials and structures. The results of this study identify materials and structures of interest for further, more in-depth, impact investigations.

  14. Development and Testing Of Natural Fiber Reinforced Composites With Polyester Resin.

    Directory of Open Access Journals (Sweden)

    S.P. Akbar Hussain

    2013-10-01

    Full Text Available Now --a – days most of the automotive parts are made with different materials which cannot be recycled. Recently European Union (E.U and Asian countries have released stringent norms concerning automotive end-life requirements i.e the parts of the automotives should be recycled. This increased the use of natural fibres in composite materials. Natural fibers have recently become more attractive to researchers, engineers and scientists as an alternative reinforcement for fiber reinforced polymer composites. Due to their low cost, low density, stiffness, fairly good mechanical properties, high specific strength, non-abrasive, eco-friendly and biodegradable characteristics, they are exploited as a replacement for the conventional fiber, such as glass, aramid and carbon. The tensile properties of natural fiber reinforced polymers (both thermoplastics and thermosets are mainly influenced by the interfacial adhesion between the matrix and the fibers. Further the mechanical properties can be improved with several chemical modifications on the composites. In the present work, natural fiber (sisal, hemp, hemp and sisal combination reinforced polyester resin composites were produced and are tested for mechanical properties and further compared with the normal plastics. The mechanical properties of sisal and hemp reinforced polyester resin composites were found to increase with increasing fiber weight fraction. In important properties hemp and sisal combination composite showed the best.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  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. Full metal jacket!

    CERN Multimedia

    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...

  1. 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

  2. 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.

  3. Fiber-Reinforced Reactive Nano-Epoxy Composites

    Science.gov (United States)

    Zhong, Wei-Hong

    2011-01-01

    An ultra-high-molecular-weight polyethylene/ matrix interface based on the fabrication of a reactive nano-epoxy matrix with lower surface energy has been improved. Enhanced mechanical properties versus pure epoxy on a three-point bend test include: strength (25 percent), modulus (20 percent), and toughness (30 percent). Increased thermal properties include higher Tg (glass transition temperature) and stable CTE (coefficient of thermal expansion). Improved processability for manufacturing composites includes faster wetting rates on macro-fiber surfaces, lower viscosity, better resin infusion rates, and improved rheological properties. Improved interfacial adhesion properties with Spectra fibers by pullout tests include initial debonding force of 35 percent, a maximum pullout force of 25 percent, and energy to debond at 65 percent. Improved mechanical properties of Spectra fiber composites (tensile) aging resistance properties include hygrothermal effects. With this innovation, high-performance composites have been created, including carbon fibers/nano-epoxy, glass fibers/nano-epoxy, aramid fibers/ nano-epoxy, and ultra-high-molecularweight polyethylene fiber (UHMWPE).

  4. 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.

  5. Field responsive shear thickening fluids for personal protective equipment and MMOD shielding for spacecraft and astronauts

    Science.gov (United States)

    Wagner, Norman

    2015-03-01

    Shear thickening fluids (STFs) are novel, field responsive materials and have been shown to provide enhanced ballistic and puncture resistance when integrated into nanocomposites. In this talk, I will review the basic principles of shear thickening in colloidal dispersions by introducing new, recent results describing the unique material functions of the shear thickened state and how these material functions relate to those observed in simulation and experiments, as well as models for these material functions and their dependence on particle concentration. Next, performance data for STF-Armor(TM) nanocomposites (STF intercalated with aramid and other textiles) in puncture, ballistic and hypervelocity impact experiments, as well as energy absorbing impact experiments, will be shown and related back to the material properties of the STF fluids. Finally, advances in product development to achieve suitable puncture resistance for novel applications such as puncture resistant surgical gloves (STF Technologies LLC) will be presented along with challenges for the future product development. Support from NSF STTR # IIP-1346269 and NASA NNX11AQ28A is gratefully acknowledged.

  6. 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.

  7. 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.

  8. 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.

  9. Glass Fiber Reinforced Concrete & Its Properties

    Directory of Open Access Journals (Sweden)

    Shrikant Harle

    2014-01-01

    Full Text Available Glass fiber reinforced concrete (GFRC is a recent introduction in the field of civil engineering. So, it has been extensively used in many countries since its introduction two decades ago. This product has advantage of being light weight and thereby reducing the overall cost of construction, ultimately bringing economy in construction. Steel reinforcement corrosion and structural deterioration in reinforced concrete structures are common and prompted many researchers to seek alternative materials and rehabilitation techniques. So, researchers all over the world are attempting to develop high performance concrete using glass fibers and other admixtures in the concrete up to certain extent. In the view of global sustainable scenario, it is imperative that fibers like glass, carbon, aramid and poly-propylene provide very wide improvements in tensile strength, fatigue characteristics, durability, shrinkage characteristics, impact, cavitations, erosion resistance and serviceability of concrete. The present work is only an accumulation of information about GFRC and the research work which is already carried out by other researchers.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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)

  15. 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

  16. 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.

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Design and testing of a deformable wind turbine blade control surface

    International Nuclear Information System (INIS)

    Wind tunnel tests were conducted on a 1.3 m chord NACA 63–418 blade section fitted with an adaptive trailing edge flap. The 20% chord flap had an aramid honeycomb core covered with a silicone skin and was actuated using servo motors. The honeycomb core had a high stiffness in the thickness direction but was compliant in chordwise bending. These anisotropic properties offer a potential solution for the conflicting design requirements found in morphing trailing edge structures. Static and dynamic tests were performed up to a Reynolds number of 5.4 × 106. The tests showed that deflecting the flap from − 10° to + 10° changes the blade section lift coefficient by 1.0 in non-stalled conditions. Dynamic tests showed the flap to be capable of operating up to 9° s−1 using a 15 V power supply. A two-dimensional static aeroelastic model of the morphing flap was developed to analyse strains, predict actuator requirements and study fluid–structure interaction effects. The model was used to conduct parametric studies to further improve the flap design. Potential applications include wind turbine blade load alleviation and increased wind energy capture. (paper)

  5. 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.

  6. 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

  7. 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

  8. Hygrothermal degradation and fracture process of advanced fibre-reinforced plastics

    Energy Technology Data Exchange (ETDEWEB)

    Komai, K.; Minoshima, K.; Shiroshita, S. (Dept. of Mechanical Engineering, Kyoto Univ. (Japan))

    1991-09-15

    An investigation has been carried out on the effects of water absorption on the mechanical properties and fatigue strength of unidirectionally reinforced carbon-epoxy (CFRP) and aramid-epoxy (AFRP). T-1/347 normal-type CFRP absorbed more water than MM-1/982X heat-resistant-type CFRP. After a long immersion of about 7 months, however, MM-1/982X composites absorbed water rapidly and the fatigue strength was considerably decreased. In T-1/347 wet specimens preconditioned in water for 2 months a high amount of water absorption degraded the matrix and decreased the strength of the fibre-matrix interface, thereby worsening the mechanical properties. For MM-1/982X composites a small amount of water absorption moderately decreased the interfacial strength and increased the ductility of the matrix, thereby improving the mechanical properties. However, the fatigue lives of wet specimens of both CFRPs were decreased in water. Water absorption lowered the yield strength of the epoxy resin, thereby changing the shape of the stress-strain curves of AFRP. This had no effect on the tensile strength of the composites. Water absorption increased the fatigue strength of both Dupont's Kevlar-49 and Teijin's Technora AFRP. The water absorption increased the ductility of the matrix and enabled local realignment of the fibres. The Technora composite had a stronger interface than the Kevlar-49 composite. Water absorption lowered the interfacial strength of both AFRPs and changed the failure mechanisms. In these tests the synthesized evaluation of acoustic emission (AE) signals using several AE parameters was carried out and the fracture mechanisms were discussed in terms of the observations of internal damage by a scanning acoustic microscope and of fracture surfaces by a scanning electron microscope.

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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).

  3. 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)

  4. Advanced Clothing Studies

    Science.gov (United States)

    Orndoff, Evelyne; Poritz, Darwin

    2014-01-01

    All human space missions require significant logistical mass and volume that add an unprecedented burden on longduration missions beyond low-Earth orbit. For these missions with limited cleaning resources, a new wardrobe must be developed to reduce this logistical burden by reducing clothing mass and extending clothing wear. The present studies have been undertaken, for the first time, to measure length of wear and to assess the acceptance of such extended wear. Garments in these studies are commercially available exercise T-shirts and shorts, routine-wear T-shirts, and longsleeved pullover shirts. Fabric composition (cotton, polyester, light-weight, superfine Merino wool, modacrylic, cotton/rayon, polyester/Cocona, modacrylic/Xstatic, modacrylic/rayon, modacrylic/lyocell/aramid), construction (open knit, tight knit, open weave, tight weave), and finishing treatment (none, quaternary ammonium salt) are the independent variables. Eleven studies are reported here: five studies of exercise T-shirts, three of exercise shorts, two of routine wear Tshirts, and one of shirts used as sleep-wear. All studies are conducted in a climate-controlled environment, similar to a space vehicle's. For exercise clothing, study participants wear the garments during aerobic exercise. For routine wear clothing, study participants wear the T-shirts daily in an office or laboratory. Daily questionnaires collected data on ordinal preferences of nine sensory elements and on reason for retiring a used garment. Study 1 compares knitted cotton, polyester, and Merino exercise T-shirts (61 participants), study 2, knitted polyester, modacrylic, and polyester/Cocona exercise T-shirts (40 participants), study 3, cotton and polyester exercise shorts, knitted and woven (70 participants), all three using factorial experimental designs with and without a finishing treatment, conducted at the Johnson Space Center, sharing study participants. Study 4 compares knitted polyester and ZQ Merino exercise T

  5. 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

  6. 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.

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

    International Nuclear Information System (INIS)

    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)

  8. 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。

  9. 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.

  10. 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.

  11. 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。

  12. 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。

  13. 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

  14. 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.

  15. 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