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Sample records for carbon-fiber reinforced metal

  1. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, Suri A.; Pemsler, J. Paul; Cooke, Richard A.; Litchfield, John K.; Smith, Mark B.

    1996-01-01

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates.

  2. Metal-bonded, carbon fiber-reinforced composites

    DOEpatents

    Sastri, S.A.; Pemsler, J.P.; Cooke, R.A.; Litchfield, J.K.; Smith, M.B.

    1996-03-05

    Metal bonded carbon fiber-reinforced composites are disclosed in which the metal and the composite are strongly bound by (1) providing a matrix-depleted zone in the composite of sufficient depth to provide a binding site for the metal to be bonded and then (2) infiltrating the metal into the matrix-free zone to fill a substantial portion of the zone and also provide a surface layer of metal, thereby forming a strong bond between the composite and the metal. The invention also includes the metal-bound composite itself, as well as the provision of a coating over the metal for high-temperature performance or for joining to other such composites or to other substrates. 2 figs.

  3. Deformation behavior of FRP-metal composites locally reinforced with carbon fibers

    NASA Astrophysics Data System (ADS)

    Scholze, M.; Kolonko, A.; Lindner, T.; Lampke, T.; Helbig, F.

    2016-03-01

    This study investigates variations of hybrid laminates, consisting of one aluminum sheet and a unidirectional glass fiber (GF) reinforced polyamide 6 (PA6) basic structure with partial carbon fiber (CF) reinforcement. To create these heterogeneous FRP laminates, it is necessary to design and produce semi-finished textile-based products. Moreover, a warp knitting machine in conjunction with a warp thread offset unit was used to generate bionic inspired compounds. By the variation of stacking prior to the consolidation process of the hybrid laminate, an oriented CF reinforcement at the top and middle layer of the FRP is realized. In both cases the GFRP layer prevents contact between the aluminum and carbon fibers. In so doing, the high strength of carbon fibers can be transferred to the hybrid laminate in load directions with an active prevention of contact corrosion. The interface strength between thermoplastic and metal component was improved by a thermal spray coating on the aluminum sheet. Because of the high surface roughness and porosity, mechanical interlock was used to provide high interface strength without bonding agents between both components. The resulting mechanical properties of the hybrid laminates are evaluated by three point bending tests in different load directions. The effect of local fiber orientation and layer positioning on failure and deformation mechanism is additionally investigated by digital image correlation (DIC).

  4. [Fusion implants of carbon fiber reinforced plastic].

    PubMed

    Früh, H J; Liebetrau, A; Bertagnoli, R

    2002-05-01

    Carbon fiber reinforced plastics (CFRP) are used in the medical field when high mechanical strength, innovative design, and radiolucency (see spinal fusion implants) are needed. During the manufacturing process of the material CFRP carbon fibers are embedded into a resin matrix. This resin material could be thermoset (e.g., epoxy resin EPN/DDS) or thermoplastic (e.g., PEAK). CFRP is biocompatible, radiolucent, and has higher mechanical capabilities compared to other implant materials. This publication demonstrates the manufacturing process of fusion implants made of a thermoset matrix system using a fiber winding process. The material has been used clinically since 1994 for fusion implants of the cervical and lumbar spine. The results of the fusion systems CORNERSTONE-SR C (cervical) and UNION (lumbar) showed no implant-related complications. New implant systems made of this CFRP material are under investigation and are presented.

  5. Radiation effects on carbon fiber reinforced thermoplastics

    SciTech Connect

    Sasuga, Tsuneo; Udagawa, Akira; Seguchi, Tadao

    1993-12-31

    Polyether-ether-ketone (PEEK) and a newly developed thermoplastic polyimide ``new-TPI`` were applied to carbon fiber reinforced plastic (CFRP) as a matrix resin. PEEK and new-TPI showed excellent resistance over 50 MGy to electron irradiation and the crosslinking proceeded predominantly by irradiation. The changes in mechanical properties induced by electron irradiation of the CFRP with the two resins were examined at various temperatures. The flexural strength and modulus measured at {minus}196 and 25{degree}C were scarcely affected up to 120 MGy and both the values measured at high temperature were increased with dose.

  6. Experimental Behavior of Carbon Fiber Reinforced Isolators

    SciTech Connect

    Russo, Gaetano; Pauletta, Margherita; Cortesia, Andrea; Dal Bianco, Alberto

    2008-07-08

    This paper describes an investigation on the experimental behavior of innovative elastomeric isolators reinforced by carbon fiber fabrics. These fabrics are very much lighter than steel plates used in conventional isolators and able to transfer to the adjacent elastomer layers tangential stresses adequate to oppose the transversal deformation of rubber under vertical loads. The isolators are not bonded to the sub- and super-structure (elimination of the steel end-plates), hence their weight and cost are reduced. The experimental investigation is carried out on small-scale isolator prototypes reinforced by quadridirectional carbon fiber fabrics. The isolators are subjected to the following qualification tests prescribed by the Italian Code 'Ordinanza 3274' for steel reinforced isolators: 1) 'Static assessment of the compression stiffness'; 2) 'Static assessment of the shear modulus G'; 3) 'Dynamic assessment of the dynamic shear modulus G{sub din} and of the damping coefficient {xi}; 4) 'Assessment of the G{sub din}-{gamma} and {xi}-{gamma} diagrams by means of dynamic tests'; 5) 'Assessment of creep characteristics'; 6) 'Evaluation of the capacity of sustaining at least 10 cycles'. As a result of the tests, the isolators survived large shear strains, comparable to those expected for conventional isolators.

  7. Carbon Fiber Reinforced Glass Matrix Composites for Space Based Applications.

    DTIC Science & Technology

    1987-08-31

    Nardone , "Carbon Fiber Reinforced Glass Matrix Composites for Space Based Applications", Office of Naval Research Contract N00014-85-C-0332, Report R86... Nardone and K M. Prewo, "Tensile Performance of Carbon Fiber Reinforced Glass", J. Mater. Sci. accepted for publication, 1987. 27. R. F. Cooper and K

  8. Stronger Carbon Fibers for Reinforced Plastics

    NASA Technical Reports Server (NTRS)

    Cagliostro, D. E.; Lerner, N. R.

    1983-01-01

    Process makes fibers 70 percent stronger at lower carbonization temperature. Stronger carbon fibers result from benzoic acid pretreatment and addition of acetylene to nitrogen carbonizing atmosphere. New process also makes carbon fibers of higher electrical resistance -- an important safety consideration.

  9. Carbon fiber reinforced root canal posts. Mechanical and cytotoxic properties.

    PubMed

    Torbjörner, A; Karlsson, S; Syverud, M; Hensten-Pettersen, A

    1996-01-01

    The aim of this study was to compare the mechanical properties of a prefabricated root canal post made of carbon fiber reinforced composites (CFRC) with metal posts and to assess the cytotoxic effects elicited. Flexural modulus and ultimate flexural strength was determined by 3 point loading after CRFC posts had been stored either dry or in water. The bending test was carried out with and without preceding thermocycling of the CFRC posts. The cytotoxicity was evaluated by an agar overlay method after dry and wet storage. The values of flexural modulus and ultimate flexural strength were for dry stored CFRC post 82 +/- 6 GPa and 1154 +/- 65 MPa respectively. The flexural values decreased significantly after water storage and after thermocycling. No cytotoxic effects were observed adjacent to any CFRC post. Although fiber reinforced composites may have the potential to replace metals in many clinical situations, additional research is needed to ensure a satisfying life-span.

  10. [Carbon fiber-reinforced plastics as implant materials].

    PubMed

    Bader, R; Steinhauser, E; Rechl, H; Siebels, W; Mittelmeier, W; Gradinger, R

    2003-01-01

    Carbon fiber-reinforced plastics have been used clinically as an implant material for different applications for over 20 years.A review of technical basics of the composite materials (carbon fibers and matrix systems), fields of application,advantages (e.g., postoperative visualization without distortion in computed and magnetic resonance tomography), and disadvantages with use as an implant material is given. The question of the biocompatibility of carbon fiber-reinforced plastics is discussed on the basis of experimental and clinical studies. Selected implant systems made of carbon composite materials for treatments in orthopedic surgery such as joint replacement, tumor surgery, and spinal operations are presented and assessed. Present applications for carbon fiber reinforced plastics are seen in the field of spinal surgery, both as cages for interbody fusion and vertebral body replacement.

  11. Carbon fiber reinforced thermoplastic composites for future automotive applications

    NASA Astrophysics Data System (ADS)

    Friedrich, K.

    2016-05-01

    After a brief introduction to polymer composite properties and markets, the state of the art activities in the field of manufacturing of advanced composites for automotive applications are elucidated. These include (a) long fiber reinforced thermoplastics (LFT) for secondary automotive components, and (b) continuous carbon fiber reinforced thermosetting composites for car body applications. It is followed by future possibilities of carbon fiber reinforced thermoplastic composites for e.g. (i) crash elements, (ii) racing car seats, and (iii) production and recycling of automotive fenders.

  12. Mechanical strength of additive manufactured carbon fiber reinforced polyetheretherketone

    NASA Astrophysics Data System (ADS)

    Chumaevskii, A. V.; Tarasov, S. Yu.; Filippov, A. V.; Kolubaev, E. A.; Rubtsov, V. E.; Eliseev, A. A.

    2016-11-01

    Mechanical properties of both pure and chopped carbon fiber reinforced polyetheretherketone samples have been carried out. It was shown that the reinforcement resulted in increasing the elasticity modulus, compression and tensile ultimate strength by a factor of 3.5, 2.9 and 2.8, respectively. The fracture surfaces have been examined using both optical and scanning electron microscopy.

  13. High-frequency components made of carbon-fiber reinforced plastics for satellite payloads

    NASA Astrophysics Data System (ADS)

    Saulich, G.

    1981-06-01

    The design and the material characteristics of carbon-fiber reinforced plastics (CFRP) are discussed, taking into account characteristic data for various types of fibers and details of material construction. Waveguide filters made of carbon-fiber reinforced plastics are considered. These filters are used in satellite transponders in connection with the high resonator quality required. Attention is given to tubes and plates of CFRF, aspects of metallization, and adhesive bonding. Reflector antennas of CFRP are discussed, taking into account the design of CFRP reflectors, the reflection characteristics of CFRP reflectors, CFRP laminate characteristics, reflector coatings, and selection criteria for the design of CFRP reflectors.

  14. Puncture-Healing Thermoplastic Resin Carbon-Fiber-Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Gordon, Keith L. (Inventor); Siochi, Emilie J. (Inventor); Grimsley, Brian W. (Inventor); Cano, Roberto J. (Inventor); Czabaj, Michael W. (Inventor)

    2015-01-01

    A composite comprising a combination of a self-healing polymer matrix and a carbon fiber reinforcement is described. In one embodiment, the matrix is a polybutadiene graft copolymer matrix, such as polybutadiene graft copolymer comprising poly(butadiene)-graft-poly(methyl acrylate-co-acrylonitrile). A method of fabricating the composite is also described, comprising the steps of manufacturing a pre-impregnated unidirectional carbon fiber preform by wetting a plurality of carbon fibers with a solution, the solution comprising a self-healing polymer and a solvent, and curing the preform. A method of repairing a structure made from the composite of the invention is described. A novel prepreg material used to manufacture the composite of the invention is described.

  15. Mechanical characterization of commercially made carbon-fiber-reinforced polymethylmethacrylate.

    PubMed

    Saha, S; Pal, S

    1986-01-01

    Acrylic bone cement is significantly weaker and of lower modulus of elasticity than compact bone. It is also weaker in tension than in compression. This limits its use in orthopedics to areas where tensile stresses were minimum. Many authors have shown that addition of small percentages of fiber reinforcement by hand mixing improved the mechanical properties significantly but with variable results. In this investigation we have examined the mechanical properties of machine-mixed, commercially available carbon-fiber-reinforced bone cement. Appropriate samples of normal low-viscosity cement and carbon-fiber-reinforced cement were prepared and tested mechanically. Carbon fiber increased the tensile strength and modulus by 30% and 35.8% respectively. The compression strength and modulus, however, increased by only 10.7%. Similarly, bending and shear strengths improved by 29.5% and 18.5%, respectively. Diametral compression strength, which is an indirect measure of tensile strength, however, showed only 6.2% improvement. The maximum temperature rise during polymerization was also reduced significantly by the fiber reinforcement.

  16. Carbon Fiber Reinforced Carbon Composite Valve for an Internal Combustion Engine

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

    1999-01-01

    A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers throughout the valve's stem and head is disclosed. The valve includes braided carbon fiber material over axially aligned unidirectional carbon fibers forming a valve stem; the braided and unidirectional carbon fibers being broomed out at one end of the valve stem forming the shape of the valve head; the valve-shaped structure being densified and rigidized with a matrix of carbon containing discontinuous carbon fibers: and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.

  17. Bisphenyl-Polymer/Carbon-Fiber-Reinforced Composite Compared to Titanium Alloy Bone Implant

    PubMed Central

    Petersen, Richard C.

    2014-01-01

    Aerospace/aeronautical thermoset bisphenyl-polymer/carbon-fiber-reinforced composites are considered as new advanced materials to replace metal bone implants. In addition to well-recognized nonpolar chemistry with related bisphenol-polymer estrogenic factors, carbon-fiber-reinforced composites can offer densities and electrical conductivity/resistivity properties close to bone with strengths much higher than metals on a per-weight basis. In vivo bone-marrow tests with Sprague-Dawley rats revealed far-reaching significant osseoconductivity increases from bisphenyl-polymer/carbon-fiber composites when compared to state-of-the-art titanium-6-4 alloy controls. Midtibial percent bone area measured from the implant surface increased when comparing the titanium alloy to the polymer composite from 10.5% to 41.6% at 0.8 mm, P < 10−4, and 19.3% to 77.7% at 0.1 mm, P < 10−8. Carbon-fiber fragments planned to occur in the test designs, instead of producing an inflammation, stimulated bone formation and increased bone integration to the implant. In addition, low-thermal polymer processing allows incorporation of minerals and pharmaceuticals for future major tissue-engineering potential. PMID:25553057

  18. Method of making carbon fiber-carbon matrix reinforced ceramic composites

    NASA Technical Reports Server (NTRS)

    Williams, Brian (Inventor); Benander, Robert (Inventor)

    2007-01-01

    A method of making a carbon fiber-carbon matrix reinforced ceramic composite wherein the result is a carbon fiber-carbon matrix reinforcement is embedded within a ceramic matrix. The ceramic matrix does not penetrate into the carbon fiber-carbon matrix reinforcement to any significant degree. The carbide matrix is a formed in situ solid carbide of at least one metal having a melting point above about 1850 degrees centigrade. At least when the composite is intended to operate between approximately 1500 and 2000 degrees centigrade for extended periods of time the solid carbide with the embedded reinforcement is formed first by reaction infiltration. Molten silicon is then diffused into the carbide. The molten silicon diffuses preferentially into the carbide matrix but not to any significant degree into the carbon-carbon reinforcement. Where the composite is intended to operate between approximately 2000 and 2700 degrees centigrade for extended periods of time such diffusion of molten silicon into the carbide is optional and generally preferred, but not essential.

  19. Life Cycle Assessment of Carbon Fiber-Reinforced Polymer Composites

    SciTech Connect

    Das, Sujit

    2011-01-01

    Carbon fiber-reinforced polymer matrix composites is gaining momentum with the pressure to lightweight vehicles, however energy-intensity and cost remain some of the major barriers before this material could be used in large-scale automotive applications. A representative automotive part, i.e., a 30.8 kg steel floor pan having a 17% weight reduction potential with stringent cash performance requirements has been considered for the life cycle energy and emissions analysis based on the latest developments occurring in the precursor type (conventional textile-based PAN vs. renewable-based lignin), part manufacturing (conventional SMC vs. P4) and fiber recycling technologies. Carbon fiber production is estimated to be about 14 times more energy-intensive than conventional steel production, however life cycle primary energy use is estimated to be quite similar to the conventional part, i.e., 18,500 MJ/part, especially when considering the uncertainty in LCI data that exists from using numerous sources in the literature. Lignin P4 technology offers the most life cycle energy and CO2 emissions benefits compared to a conventional stamped steel technology. With a 20% reduction in energy use in the lignin conversion to carbon fiber and free availability of lignin as a by-product of ethanol and wood production, a 30% reduction in life cycle energy use could be obtained. A similar level of life cycle energy savings could also be obtained with a higher part weight reduction potential of 43%.

  20. Defect depth measurement of carbon fiber reinforced polymers by thermography

    NASA Astrophysics Data System (ADS)

    Chen, Terry Y.; Chen, Jian-Lun

    2016-01-01

    Carbon fiber reinforced polymers has been widely used in all kind of the industries. However the internal defects can result in the change of material or mechanical properties, and cause safety problem. In this study, step-heating thermography is employed to measure the time series temperature distribution of composite plate. The principle of heat conduction in a flat plate with defect inside is introduced. A temperature separation criterion to determine the depth of defect inside the specimen is obtained experimentally. Applying this criterion to CFRP specimens with embedded defects, the depth of embedded defect in CFRP can be determined quite well from the time series thermograms obtained experimentally.

  1. Carbon Fiber Reinforced Ceramic Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Freedman, Marc (Technical Monitor); Shivakumar, Kunigal N.

    2003-01-01

    Fiber reinforced ceramic composites are materials of choice for gas turbine engines because of their high thermal efficiency, thrust/weight ratio, and operating temperatures. However, the successful introduction of ceramic composites to hot structures is limited because of excessive cost of manufacturing, reproducibility, nonuniformity, and reliability. Intense research is going on around the world to address some of these issues. The proposed effort is to develop a comprehensive status report of the technology on processing, testing, failure mechanics, and environmental durability of carbon fiber reinforced ceramic composites through extensive literature study, vendor and end-user survey, visits to facilities doing this type of work, and interviews. Then develop a cooperative research plan between NASA GRC and NCA&T (Center for Composite Materials Research) for processing, testing, environmental protection, and evaluation of fiber reinforced ceramic composites.

  2. Static and dynamic behavior of carbon fiber reinforced aluminum (CARALL) laminates

    NASA Astrophysics Data System (ADS)

    Dhaliwal, Gurpinder Singh

    The main aim of this research work was to investigate the static and dynamic properties of carbon fiber reinforced aluminum laminates cured without using any external adhesive and acid treatment of aluminum layers. A comprehensive study was undertaken to study the effect of adding epoxy resin rich polyester synthetic surface veil cloth layers on the failure modes and flexural and tensile response of these fiber metal laminates (FMLs). The main purpose of adding veil cloth layers was to prevent the occurrence of galvanic corrosion by avoiding direct contact between aluminum and carbon fiber layers. The addition of veil cloth layers leads to the combined failure of all layers in carbon fiber reinforced aluminum laminates at the same time, whereas the carbon fiber/ epoxy layers break before the failure of aluminum layers in samples cured without using veil cloth layers under tensile loading. The delamination was found to be reduced to a great extent in these laminate configurations due to the addition of veil cloth layers. Thermal residual stress developed during the curing of fiber metal laminates were predicted by utilizing analytical equations and finite element modeling. It was found out that the veil cloth layer does not affect much in reducing the thermal residual stress. Low-velocity impact tests were carried out using a drop-weight impact tower by impacting these fiber metal laminates at the center with three different energy levels to address energy absorption characteristics of these composites. Results showed that these laminates give higher forces and smaller displacement with the addition of polyester veil cloth layers due to reduced delaminated area across all interfaces of aluminum and carbon fiber layers, thus increasing slightly the energy absorption capabilities of these laminates. Primary failure modes observed during impact tests in these FMLs were cracks in the non-impacted aluminum layer, carbon fiber (CFRP) layer breakage and delamination b

  3. Recognizing defects in carbon-fiber reinforced plastics

    NASA Technical Reports Server (NTRS)

    Schuetze, R.; Hillger, W.

    1982-01-01

    The damage tolerance of structures made of carbon-fiber-reinforced plastic is tested under various loads. Test laminate (73/1/1, 24/9/1, 1465 A) specimens of thickness 1.5-3.2 mm with various defects were subjected to static and dynamic loads. Special attention was given to delamination, and ultrasonic C-scans were made on the specimens. It was shown that cracks from even small defects are detected with great accuracy. The same probes were also X rayed; defects that could not be detected under ordinary X rays were bored and studied under vacuum by a contrast technique. The nondestructive ultrasonic and X ray tests were controlled by partially destructive tests, and good agreement was observed.

  4. [Improving fiber adhesion by surface oxidation in carbon fiber reinforced bone cement].

    PubMed

    Hopf, T; Büttner, S; Brill, W

    1989-01-01

    The mechanical superiority of carbon fiber reinforced PMMA containing additional apatite was shown previously. For further improvement these carbon fibers were now submitted to a superficial oxidation treatment by HNO3. A closer contact between the carbon fibers and PMMA and even trabeculae-like adhesions were detected by Scanning Electron Microscopy. The fatigue strength of the carbon fiber reinforced bone cement could be increased at 17% by this oxidation treatment. This increase, however, is less than that observed in the case of other fiber reinforced composites. Most likely this is caused by the pronounced polymerisation contraction of PMMA. Further improvement of the adhesion of the fibers to cement may be achieved by different oxidation techniques, further extraction of foreign substances or graft polymerization of the carbon fibers by PMMA or other polymers.

  5. Effects of EB irradiation on stress-strain curves for carbon fiber reinforced composite materials

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Yamada, K.; Mizutani, A.; Uchida, N.; Tanaka, K.; Nishi, Yoshitake

    2004-02-01

    In order to evaluate influence of electron beam (EB) irradiation on elasticity and stress- strain curve of composite materials reinforced by carbon fiber (CF), carbon fiber reinforced polymer (CFRP) and carbon fiber reinforced graphite (C/C) were treated by EB irradiation of 0.3 MGy. Since the EB strengthening was mainly dominated by the ductility enhancements of carbon fiber and matrix of epoxy resin, EB irradiation enlarged fracture stress and enhanced fracture strain of CFRP. Furthermore, EB irradiation slightly enhanced bending elasticity of CFRP and largely enhanced the initial spring constant related to elasticity of C/C coil. Although the elasticity enhancement of carbon fibers did not largely contribute that of CFRP, that of treated graphite matrix in C/C mainly caused the C/C coil elasticity enhancement by EB irradiation. Such a new treatment is a dream-worthy technology for structural materials to be applied in the fields of future engineering.

  6. Guided wave propagation in porous unidirectional carbon fiber reinforced plastic

    NASA Astrophysics Data System (ADS)

    Dobmann, Nicolas; Bach, Martin

    2017-02-01

    Networks of piezoelectric transducers mounted on aircraft structures for Acousto Ultrasonics (AU) purposes are designed to be applied during the service life of the aircraft. The approach to integrate these sensor networks already during the manufacture of carbon fiber reinforced plastic (CFRP) host structures prompts ideas to achieve an additional benefit by their application for cure monitoring, thus extending their use to the manufacturing chain. This benefit could be extended even further if guided waves generated by AU sensor networks could be used for porosity testing extensively applied for CFRP aircraft structures. In light of this, an experimental study was conducted to investigate effects of porosity on the propagation of guided waves in a basic configuration of unidirectional CFRP. Several samples were manufactured at different porosity levels by variation of the processing pressure. Wave fields were acquired using an ultrasonic scanning device. In the present work, phase velocities are chosen as best measurable and quantifiable propagation feature and the approach for the analysis of phase velocities in porosity samples is outlined. First results are presented and discussed regarding the influence of porosity on guided wave phase velocity and basic applicability for porosity testing of aircraft structures.

  7. Oxidation Behavior of Carbon Fiber Reinforced Silicon Carbide Composites

    NASA Technical Reports Server (NTRS)

    Valentin, Victor M.

    1995-01-01

    Carbon fiber reinforced Silicon Carbide (C-SiC) composites offer high strength at high temperatures and good oxidation resistance. However, these composites present some matrix microcracks which allow the path of oxygen to the fiber. The aim of this research was to study the effectiveness of a new Silicon Carbide (SiC) coating developed by DUPONT-LANXIDE to enhance the oxidation resistance of C-SiC composites. A thermogravimetric analysis was used to determine the oxidation rate of the samples at different temperatures and pressures. The Dupont coat proved to be a good protection for the SiC matrix at temperatures lower than 1240 C at low and high pressures. On the other hand, at temperatures above 1340 C the Dupont coat did not seem to give good protection to the composite fiber and matrix. Even though some results of the tests have been discussed, because of time restraints, only a small portion of the desired tests could be completed. Therefore, no major conclusions or results about the effectiveness of the coat are available at this time.

  8. Thermal diffusivity measurements on porous carbon fiber reinforced polymer tubes

    NASA Astrophysics Data System (ADS)

    Gruber, Jürgen; Gresslehner, Karl Heinz; Mayr, Günther; Hendorfer, Günther

    2017-02-01

    This work presents the application of methods for the determination of the thermal diffusivity well suited for flat bodies adapted to cylindrical bodies. Green's functions were used to get the temperature time history for small and large times, for the approach of intersecting these two straight lines. To verify the theoretical considerations noise free data are generated by finite element simulations. Furthermore effects of inhomogeneous excitation and the anisotropic heat conduction of carbon fiber reinforced polymers were taken into account in these numerical simulations. It could be shown that the intersection of the two straight lines is suitable for the determination of the thermal diffusivity, although the results have to be corrected depending on the ratio of the cylinders inner and outer radii. Inhomogeneous excitation affects the results of this approach as it lead to multidimensional heat flux. However, based on the numerical simulations a range of the azimuthal angle exists, where the thermal diffusivity is nearly independent of the angle. The method to determine the thermal diffusivity for curved geometries by the well suited Thermographic Signal Reconstruction method and taking into account deviations from the slab by a single correction factor has great advantages from an industrial point of view, just like an easy implementation into evaluation software and the Thermographic Signal Reconstruction methods rather short processing time.

  9. Novel surface modifications of carbon fiber-reinforced polyetheretherketone hip stem in an ovine model.

    PubMed

    Nakahara, Ichiro; Takao, Masaki; Bandoh, Shunichi; Bertollo, Nicky; Walsh, William R; Sugano, Nobuhiko

    2012-01-01

    A carbon fiber-reinforced polymer (CFRP) is theoretically a suitable material for use in an uncemented hip prosthesis considering it can provide isoelastic environment with the surrounding bone, adequate fatigue strength, and a metal-free radiographic evaluation. To date, the selection of polymer material and optimization of both design and surface finish of the prostheses for osseointegration has not been accomplished. This study examined radiographic and histologic results of an uncemented CFRP stem manufactured from carbon fiber-reinforced polyetheretherketone (CFR/PEEK) with a roughened surface and a bioactive treatment in an adult ovine model following a 12-month implantation period. A unilateral hemiarthroplasty of the hip was performed using the CFRP stem or a titanium stem as a control. Four cases with the CFRP stem and five cases with titanium stem were evaluated. Bone on-growth fixation was achieved in two cases with the CFRP stem and in all the cases with the titanium stem. The CFRP cases showed minimal stress shielding while three of five cases with the titanium stem demonstrated typical osteopenia associated with stiff metal stems. Bone on-growth to the uncemented CFRP stem was achieved by using the CFR/PEEK for the material and modifying the surface design and the bioactive surface finish. Bone resorption and osteopenia observed with the Ti stems was not found with the CFRP design.

  10. Titanium Implant Osseointegration Problems with Alternate Solutions Using Epoxy/Carbon-Fiber-Reinforced Composite

    PubMed Central

    Petersen, Richard C.

    2014-01-01

    The aim of the article is to present recent developments in material research with bisphenyl-polymer/carbon-fiber-reinforced composite that have produced highly influential results toward improving upon current titanium bone implant clinical osseointegration success. Titanium is now the standard intra-oral tooth root/bone implant material with biocompatible interface relationships that confer potential osseointegration. Titanium produces a TiO2 oxide surface layer reactively that can provide chemical bonding through various electron interactions as a possible explanation for biocompatibility. Nevertheless, titanium alloy implants produce corrosion particles and fail by mechanisms generally related to surface interaction on bone to promote an inflammation with fibrous aseptic loosening or infection that can require implant removal. Further, lowered oxygen concentrations from poor vasculature at a foreign metal surface interface promote a build-up of host-cell-related electrons as free radicals and proton acid that can encourage infection and inflammation to greatly influence implant failure. To provide improved osseointegration many different coating processes and alternate polymer matrix composite (PMC) solutions have been considered that supply new designing potential to possibly overcome problems with titanium bone implants. Now for important consideration, PMCs have decisive biofunctional fabrication possibilities while maintaining mechanical properties from addition of high-strengthening varied fiber-reinforcement and complex fillers/additives to include hydroxyapatite or antimicrobial incorporation through thermoset polymers that cure at low temperatures. Topics/issues reviewed in this manuscript include titanium corrosion, implant infection, coatings and the new epoxy/carbon-fiber implant results discussing osseointegration with biocompatibility related to nonpolar molecular attractions with secondary bonding, carbon fiber in vivo properties, electrical

  11. Titanium Implant Osseointegration Problems with Alternate Solutions Using Epoxy/Carbon-Fiber-Reinforced Composite.

    PubMed

    Petersen, Richard C

    2014-12-01

    The aim of the article is to present recent developments in material research with bisphenyl-polymer/carbon-fiber-reinforced composite that have produced highly influential results toward improving upon current titanium bone implant clinical osseointegration success. Titanium is now the standard intra-oral tooth root/bone implant material with biocompatible interface relationships that confer potential osseointegration. Titanium produces a TiO2 oxide surface layer reactively that can provide chemical bonding through various electron interactions as a possible explanation for biocompatibility. Nevertheless, titanium alloy implants produce corrosion particles and fail by mechanisms generally related to surface interaction on bone to promote an inflammation with fibrous aseptic loosening or infection that can require implant removal. Further, lowered oxygen concentrations from poor vasculature at a foreign metal surface interface promote a build-up of host-cell-related electrons as free radicals and proton acid that can encourage infection and inflammation to greatly influence implant failure. To provide improved osseointegration many different coating processes and alternate polymer matrix composite (PMC) solutions have been considered that supply new designing potential to possibly overcome problems with titanium bone implants. Now for important consideration, PMCs have decisive biofunctional fabrication possibilities while maintaining mechanical properties from addition of high-strengthening varied fiber-reinforcement and complex fillers/additives to include hydroxyapatite or antimicrobial incorporation through thermoset polymers that cure at low temperatures. Topics/issues reviewed in this manuscript include titanium corrosion, implant infection, coatings and the new epoxy/carbon-fiber implant results discussing osseointegration with biocompatibility related to nonpolar molecular attractions with secondary bonding, carbon fiber in vivo properties, electrical

  12. Aspects regarding wearing behaviour in case of aluminium composite materials reinforced with carbon fibers

    NASA Astrophysics Data System (ADS)

    Caliman, R.

    2016-08-01

    This paper presents a study regarding wear comportment of sintered composite materials obtained by mixture of aluminium with short carbon fibers. The necessity to satisfying more and more the specific functions during design of high performance structures leads to perform multi-materials such as reinforced composite parts. The wear tests were made on three different orientations of fibers on a standard machine of tribology, pin disk type. Counter-disk was made of cast iron with a superficial hardness of 92 HB. The wear rate and friction coefficient decreased exponentially with time of friction and reached a stationary value. This behaviour was attributed to the development of a lubricating film on the friction surface. To conduct this work was performed measurements on samples from the Al matrix composites and carbon fiber 43%, wear mechanism was investigated by scanning electron microscopy. In addition to fiber orientation, the tribological behaviour of metal matrix composites reinforced with fiber is influenced by the interfacial reaction of fiber-matrix. The characteristics and the dimensions of the interface depend on the cycle of temperature and time at which the material has been subjected during the manufacturing process and thereafter.

  13. Enhancement of osteogenesis on micro/nano-topographical carbon fiber-reinforced polyetheretherketone-nanohydroxyapatite biocomposite.

    PubMed

    Xu, Anxiu; Liu, Xiaochen; Gao, Xiang; Deng, Feng; Deng, Yi; Wei, Shicheng

    2015-03-01

    As an FDA-approved implantable material, carbon fiber-reinforced polyetheretherketone (CFRPEEK) possesses excellent mechanical properties similar to those of human cortical bone and is a prime candidate to replace conventional metallic implants. The bioinertness and inferior osteogenic properties of CFRPEEK, however, limit its clinical application as orthopedic/dental implants. The present work aimed at developing a novel carbon fiber-reinforced polyetheretherketone-nanohydroxyapatite (PEEK/CF/n-HA) ternary biocomposite with micro/nano-topographical surface for the enhancement of the osteogenesis as a potential bioactive material for bone grafting and bone tissue-engineering applications. The combined modification of oxygen plasma and sand-blasting could improve the hydrophily and generate micro/nano-topographical structures on the surface of the CFRPEEK-based ternary biocomposite. The results clearly showcased that the micro-/nano-topographical PEEK/n-HA/CF ternary biocomposite demonstrated the outstanding ability to promote the proliferation and differentiation of MG-63 cells in vitro as well as to boost the osseointegration between implant and bone in vivo, thereby boding well application to bone tissue engineering.

  14. [Preparation of carbon fiber reinforced fluid type resin denture (author's transl)].

    PubMed

    Kasuga, H; Sato, H; Nakabayashi, N

    1980-01-01

    Transverse strength of cured fluid resins is weaker than that of the heat cured. We have studied to improve the mechanical strength of self-cured acrylic resin by application of carbon fibers as reinforcement and simple methods which must be acceptable for technicians are proposed. A cloth type carbon fiber was the best reinforcement among studied carbon fibers such as chopped or mat. The chopped fibers were difficult to mix homogeneously with fluid resins and effectiveness of the reinforcement was low. Breaking often occurred at the interface between the reinforcement and resin in the cases of mat which gave defects to the test specimens. To prepare reinforced denture, the cloth was trimmed on the master cast after removal of wax and the prepreg was formed with the alginate impression on the cast by Palapress and the cloth. Other steps were same as the usual fluid resin.

  15. Method of Manufacturing Carbon Fiber Reinforced Carbon Composite Valves

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

    1998-01-01

    A method for forming a carbon composite valve for internal combustion engines is discussed. The process includes the steps of braiding carbon fiber into a rope thereby forming a cylindrically shaped valve stem portion and continuing to braid said fiber while introducing into the braiding carbon fiber rope a carbon matrix plug having an outer surface in a net shape of a valve head thereby forming a valve head portion. The said carbon matrix plug acting as a mandrel over which said carbon fiber rope is braided, said carbon fiber rope and carbon matrix plug forming a valve head portion suitable for mating with a valve seat; cutting said braided carbon valve stem portion at one end to form a valve tip and cutting said braided carbon fiber after said valve head portion to form a valve face and thus provide a composite valve preform; and densifying said preform by embedding the braided carbon in a matrix of carbon to convert said valve stem portion to a valve stem and said valve head portion to a valve head thereby providing said composite valve.

  16. Carbon Fiber Reinforced Carbon Composites Rotary Valves for Internal Combustion Engines

    NASA Technical Reports Server (NTRS)

    Northam, G. Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

    1999-01-01

    Carbon fiber reinforced carbon composite rotary, sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or warp-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties, do not present the sealing and lubrication problems that have prevented rotary, sleeve, and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  17. Carbon Fiber Reinforced Carbon Composite Rotary Valve for an Internal Combustion Engine

    NASA Technical Reports Server (NTRS)

    Northam, G.Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

    2000-01-01

    Carbon fiber reinforced carbon composite rotary sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or wrap-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties do not present the sealing and lubrication problems that have prevented rotary sleeve and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  18. Strain-rate dependence of the compressive properties of normal and carbon-fiber-reinforced bone cement.

    PubMed

    Saha, S; Pal, S

    1983-11-01

    Normal and carbon-fiber-reinforced (1 wt. %) bone cement samples were tested in compression at various strain rates. Both the compressive strength and proportional limit increased in general with increasing strain rate. Similar strain-rate sensitivity was also shown by the carbon-fiber-reinforced bone cement. The mechanical properties, namely the modulus of elasticity, the proportional limit, and the compressive strength of the carbon-fiber-reinforced bone cement showed highly significant positive correlations with the strain rate.

  19. [Experimental study on carbon fiber reinforced plastic plate--analysis of stabilizing force required for plate].

    PubMed

    Iizuka, H

    1990-11-01

    Plates currently in use for the management of bone fracture made of metal present with various problems. We manufactured carbon fiber reinforced plastic (CFRP) plates from Pyrofil T/530 puriplegs overlaid at cross angles of +/- 10 degrees, +/- 20 degrees, and +/- 30 degrees for trial and carried out an experimental study on rabbit tibiofibular bones using 316L stainless steel plates of comparable shape and size as controls. The results indicate the influence of CFRP plate upon cortical bone was milder than that of stainless steel plate, with an adequate stabilizing force for the repair of fractured rabbit tibiofibular bones. CFRP has the advantages over metals of being virtually free from corrosion and fatigue, reasonably radiolucent and able to meet a wide range of mechanical requirements. This would make CFRP plate quite promising as a new devices of treating fracture of bones.

  20. Effects of irradiated polypropylene compatibilizer on the properties of short carbon fiber reinforced polypropylene composites

    NASA Astrophysics Data System (ADS)

    Gamze Karsli, Nevin; Aytac, Ayse; Akbulut, Meshude; Deniz, Veli; Güven, Olgun

    2013-03-01

    In this study, the effects of irradiated polypropylene (PP) compatibilizer addition into PP matrix on the interfacial adhesion between the carbon fiber (CF) and PP matrix were investigated. Unirradiated and irradiated PPs were blended, and two types of carbon fibers; unsized (surface treated) and sized, were used for composites preparation. In order to characterize the physical and morphological properties of all CF reinforced composites prepared, tensile tests, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Positron annihilation lifetime spectroscopy (PALS) were performed. The strong compatibilizing effects of irradiated PP on the mechanical properties of composites were noticed. It has been found that breaking strength values were increased up to 30%. The compatibilizing effect of irradiated PP was also confirmed with SEM micrographs and PALS. It has been seen that blending PP matrix with irradiated PP improved the interfacial adhesion between the carbon fiber and matrix materials. The melting point temperatures of composites were not changed significantly for all composites. The results showed that irradiated PP as a compatibilizer together with unsized carbon fiber in place of sized carbon fiber can be used in order to improve the mechanical properties of carbon fiber reinforced PP composites.

  1. Advanced in situ multi-scale characterization of hardness of carbon-fiber-reinforced plastic

    NASA Astrophysics Data System (ADS)

    Wang, Hongxin; Masuda, Hideki; Kitazawa, Hideaki; Onishi, Keiko; Kawai, Masamichi; Fujita, Daisuke

    2016-10-01

    In situ multi-scale characterization of hardness of carbon-fiber-reinforced plastic (CFRP) is demonstrated by a traditional hardness tester, instrumented indentation tester and atomic-force-microscope (AFM)-based nanoindentation. In particular, due to the large residual indentation and nonuniform distribution of the microscale carbon fibers, the Vickers hardness could not be calculated by the traditional hardness tester. In addition, the clear residual microindentation could not be formed on the CFRP by instrumented indentation tester because of the large tip half angle of the Berkovich indenter. Therefore, an efficient technique for characterizing the true nanoscale hardness of CFRP was proposed and evaluated. The local hardness of the carbon fibers or plastic matrix on the nanoscale did not vary with nanoindentation location. The Vickers hardnesses of the carbon fiber and plastic matrix determined by AFM-based nanoindentation were 340 ± 30 and 40 ± 2 kgf/mm2, respectively.

  2. Research on the melt impregnation of continuous carbon fiber reinforced nylon 66 composites

    NASA Astrophysics Data System (ADS)

    Jia, M. Y.; Li, C. X.; Xue, P.; Chen, K.; Chen, T. H.

    2016-07-01

    Impregnation mold of continuous carbon fiber reinforced thermoplastic composites was designed and built in the article. Based on the theory of fluid mechanics and Darcy's law, a model of the melt impregnation was also established. The influences of fiber bundle width and impregnation pins’ diameter on the impregnation degree were studied by numerical simulation. Continuous carbon fiber reinforced nylon 66 composites were prepared. The effects of coated angle and impregnation mold temperature on the mechanical properties of the composites were also described.The agreement between the experimental data and prediction by the model was found to be satisfactory.

  3. Properties of glass/carbon fiber reinforced epoxy hybrid polymer composites

    NASA Astrophysics Data System (ADS)

    Patel, R. H.; Sevkani, V. R.; Patel, B. R.; Patel, V. B.

    2016-05-01

    Composite Materials are well known for their tailor-made properties. For the fabrication of composites different types of reinforcements are used for different applications. Sometimes for a particular application, one type of reinforcement may not fulfill the requirements. Therefore, more than one type of reinforcements may be used. Thus, the idea of hybrid composites arises. Hybrid composites are made by joining two or more different reinforcements with suitable matrix system. It helps to improve the properties of composite materials. In the present work glass/carbon fiber reinforcement have been used with a matrix triglycidyl ether of tris(m-hydroxy phenyl) phosphate epoxy resin using amine curing agent. Different physical and mechanical properties of the glass, carbon and glass/carbon fiber reinforced polymeric systems have been found out.

  4. FIBER LENGTH DISTRIBUTION MEASUREMENT FOR LONG GLASS AND CARBON FIBER REINFORCED INJECTION MOLDED THERMOPLASTICS

    SciTech Connect

    Kunc, Vlastimil; Frame, Barbara J; Nguyen, Ba N.; TuckerIII, Charles L.; Velez-Garcia, Gregorio

    2007-01-01

    Procedures for fiber length distribution (FLD) measurement of long fiber reinforced injection molded thermoplastics were refined for glass and carbon fibers. Techniques for sample selection, fiber separation, digitization and length measurement for both fiber types are described in detail. Quantitative FLD results are provided for glass and carbon reinforced polypropylene samples molded with a nominal original fiber length of 12.7 mm (1/2 in.) using equipment optimized for molding short fiber reinforced thermoplastics.

  5. A New Generation of Sub Mm Telescopes, Made of Carbon Fiber Reinforced Plastic

    NASA Technical Reports Server (NTRS)

    Mezger, P.; Baars, J. W. M.; Ulich, B. L.

    1984-01-01

    Carbon fiber reinforced plastic (CFRP) appears to be the material most suited for the construction of submillimeter telescopes (SMT) not only for ground-based use but also for space applications. The accuracy of the CFRP reflectors needs to be improved beyond value of the 17 micron rms envisaged for the 10 m SMT.

  6. Oxidation of carbon fiber surfaces for use as reinforcement in high-temperature cementitious material systems

    DOEpatents

    Sugama, Toshifumi

    1990-01-01

    The interfacial bond characteristics between carbon fiber and a cement matrix, in high temperature fiber-reinforced cementitious composite systems, can be improved by the oxidative treatment of the fiber surfaces. Compositions and the process for producing the compositions are disclosed.

  7. Oxidation of carbon fiber surfaces for use as reinforcement in high-temperature cementitious material systems

    DOEpatents

    Sugama, Toshifumi.

    1990-05-22

    The interfacial bond characteristics between carbon fiber and a cement matrix, in high temperature fiber-reinforced cementitious composite systems, can be improved by the oxidative treatment of the fiber surfaces. Compositions and the process for producing the compositions are disclosed. 2 figs.

  8. Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone.

    PubMed

    Neumann, Eduardo Aloisio Fleck; Villar, Cristina Cunha; França, Fabiana Mantovani Gomes

    2014-01-01

    Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK) and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1), polyetheretherketone (PEEK) screws (Group 2), and 30% carbon fiber-reinforced PEEK screws (Group 3). The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45o off-axis, in a universal testing machine. A 200 N load (static load) was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey's range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p < 0.05). In contrast, no statistically significant difference was observed between the fracture resistance of the PEEK and the 30% carbon fiber-reinforced PEEK screws (p> 0.05). Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws.

  9. Mechanical properties of long carbon fiber reinforced thermoplastic (LFT) at elevated temperature

    NASA Astrophysics Data System (ADS)

    Wang, Qiushi

    Long fiber reinforced thermoplastics (LFT) possess high specific modulus and strength, superior damage tolerance and fracture toughness and have found increasing use in transportation, military, and aerospace applications. However, one of the impediments to utilizing these materials is the lack of performance data in harsh conditions, especially at elevated temperature. In order to quantify the effect of temperature on the mechanical properties of carbon fiber reinforced thermoplastic composites, carbon fiber PAA composite plates containing 20% and 30% carbon fiber were produced using extrusion/compression molding process and tested at three representative temperatures, room temperature (RT 26°C), middle temperature (MID 60°C) and glass transition temperature (Tg 80°C). A heating chamber was designed and fabricated for the testing at elevated temperature. As temperature increases, flexural modulus, flexural strength, tensile modulus and tensile strength decrease. The highest reduction observed in stiffness (modulus) values of 30% CF/PAA at Tg in the 00 orientation is 75%. The reduction values were larger for the transverse (perpendicular to flow direction) samples than the longitudinal (flow direction) samples. The property reduction in 30% CF/PAA is larger than 20% CF/PAA. Furthermore, an innovative method was developed to calculate the fiber content in carbon fiber reinforced composites by burning off the neat resin and sample in a tube furnace. This method was proved to be accurate (within 1.5 wt. % deviation) by using burning off data obtained from CF/Epoxy and CF/Vinyl Ester samples. 20% and 30% carbon/PAA samples were burned off and carbon fiber content was obtained using this method. The results of the present study will be helpful in determining the end-user applications of these composite materials. Keywords: Long Carbon Fibers, Elevated Temperature, Mechanical Properties, Burn off Test.

  10. An Electrical Resistance Change Method for Carbon Fiber Reinforced Plastic Inspection

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Todoroki, A.; Mei, G.; Ren, Z.; Kwan, C.

    2007-03-01

    Carbon fibers are intrinsically conductive. They form an equivalent impedance network inside a carbon fiber reinforced plastic (CFRP) composite material. This paper presents a method of using the resistance value change to detect, localize and size the damage or defect initiated inside the CFRP. Impact delamination and fatigue cracks are successfully monitored with this approach. This low cost, easy-to-implement technology could benefit aerospace and automotive industries for in-situ structural health monitoring of graphite-epoxy based components and subsystems.

  11. Impact absorption properties of carbon fiber reinforced bucky sponges.

    PubMed

    Thevamaran, Ramathasan; Saini, Deepika; Karakaya, Mehmet; Zhu, Jingyi; Podila, Ramakrishna; Rao, Apparao; Daraio, Chiara

    2017-03-24

    We describe the super compressible and highly recoverable response of bucky sponges as they are struck by a heavy flat-punch striker. The bucky sponges studied here are structurally stable, self-assembled mixtures of multiwalled carbon nanotubes (MWCNTs) and carbon fibers (CFs). We engineered the microstructure of the sponges by controlling their porosity using different CF contents. Their mechanical properties and energy dissipation characteristics during impact loading are presented as a function of their composition. The inclusion of CFs improves the impact force damping by up to 50% and the specific damping capacity by up to 7% compared to bucky sponges without CFs. The sponges also exhibit significantly better stress mitigation characteristics compared to vertically aligned carbon nanotube foams of similar densities. We show that delamination on the MWCNT-CF interfaces occurs during unloading, and arises from the heterogeneous fibrous microstructure of the bucky sponges.

  12. Development of Carbon Fiber Reinforced Stellite Alloy Based Composites for Tribocorrosion Applications

    NASA Astrophysics Data System (ADS)

    Khoddamzadeh, Alireza

    This thesis reports the design and development of two classes of new composite materials, which are low-carbon Stellite alloy matrices, reinforced with either chopped plain carbon fiber or chopped nickel-coated carbon fiber. The focus of this research is on obviating the problems related to the presence of carbides in Stellite alloys by substituting carbides as the main strengthening agent in Stellite alloys with the aforementioned carbon fibers. Stellite 25 was selected as the matrix because of its very low carbon content (0.1 wt%) and thereby relatively carbide free microstructure. The nickel coating was intended to eliminate any chance of carbide formation due to the possible reaction between carbon fibers and the matrix alloying additions. The composite specimens were fabricated using the designed hot isostatic pressing and sintering cycles. The fabricated specimens were microstructurally analyzed in order to identify the main phases present in the specimens and also to determine the possible carbide formation from the carbon fibers. The material characterization of the specimens was achieved through density, hardness, microhardness, corrosion, wear, friction, and thermal conductivity tests. These novel materials exhibit superior properties compared to existing Stellite alloys and are expected to spawn a new generation of materials used for high temperature, severe corrosion, and wear resistant applications in various industries.

  13. Oxidation Behavior of Carbon Fiber-Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Sullivan, Roy M.

    2008-01-01

    OXIMAP is a numerical (FEA-based) solution tool capable of calculating the carbon fiber and fiber coating oxidation patterns within any arbitrarily shaped carbon silicon carbide composite structure as a function of time, temperature, and the environmental oxygen partial pressure. The mathematical formulation is derived from the mechanics of the flow of ideal gases through a chemically reacting, porous solid. The result of the formulation is a set of two coupled, non-linear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined at each time step using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The non-linear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual finite element method, allowing for the solution of the differential equations numerically.

  14. [A study on alpha-tricalcium phosphate bone cement carbon fiber-reinforced].

    PubMed

    Wu, Wenjin; Yang, Weizhong; Zhou, Dali; Ma, Jiang; Xiao, Bin

    2006-06-01

    In order to improve the mechanical properties of alpha-tricalcium phosphate (alpha-TCP), we prepared surface-modified carbon fibers (CF) reinforced alpha-TCP composite bone cement. Bone cement was soaked in Ringer's body solution to test its capacity of fast formation of hydroxyapatite crystals and self-solidification. Scan electronic microscope (SEM) observation and compressive strength measurement were taken to analyze the mechanical properties and the micro- morphological structure of CF reinforced alpha-TCP bone cement. The results showed that the bone cement was transferred into hydroxyapatite plates after being soaked in Ringer's simulated body fluid for 5 days. Suitable amount of carbon fibers could well spread in and bond with the matrix of the bone cement. The mechanical properties of the bone cement have been improved by CF reinforcing; the compressive strength reaches 46.7 MPa when the amount of carbon fibers is 0.5% in weight percent, which is 22% higher than that of the non-reinforced alpha-TCP bone cement.

  15. Carbon Fiber Reinforced Glass Matrix Composites for Structural Space Based Applications

    DTIC Science & Technology

    1989-07-31

    1988) 2745-2752. 2 R89-917704-1 10. V. C. Nardone and K. M. Prewo, "Tensile Performance of Carbon-Fibre-Reinforced Glass," J. Mater. Sci., 23 (1988...168-180. 11. K. M. Prewo and V. C. Nardone , "Carbon Fiber Reinforced Glass Matrix Composites for Space Based Applications," UTRC Report R86-917161-1...Mater. Sci., 23 (1988) 2745-2752. 11. V. C. Nardone and K. M. Prewo, "Tensile Performance of Carbon-Fibre-Reinforced Glass," J. Mater. Sci., 23 (1988

  16. Multiscale carbon nanotube-carbon fiber reinforcement for advanced epoxy composites.

    PubMed

    Bekyarova, E; Thostenson, E T; Yu, A; Kim, H; Gao, J; Tang, J; Hahn, H T; Chou, T-W; Itkis, M E; Haddon, R C

    2007-03-27

    We report an approach to the development of advanced structural composites based on engineered multiscale carbon nanotube-carbon fiber reinforcement. Electrophoresis was utilized for the selective deposition of multi- and single-walled carbon nanotubes (CNTs) on woven carbon fabric. The CNT-coated carbon fabric panels were subsequently infiltrated with epoxy resin using vacuum-assisted resin transfer molding (VARTM) to fabricate multiscale hybrid composites in which the nanotubes were completely integrated into the fiber bundles and reinforced the matrix-rich regions. The carbon nanotube/carbon fabric/epoxy composites showed approximately 30% enhancement of the interlaminar shear strength as compared to that of carbon fiber/epoxy composites without carbon nanotubes and demonstrate significantly improved out-of-plane electrical conductivity.

  17. Tensile strength and its scatter of unidirectional carbon fiber reinforced composites

    SciTech Connect

    Hamada, H.; Oya, N.; Yamashita, K.; Maekawa, Z.I.

    1995-12-31

    0 (along the fiber direction) and 90 degree (transverse to the fiber direction) tension tests of Carbon Fiber Reinforced Plastics (CFRP) using a great number of specimens were conducted. Tensile properties and their scatter were evaluated by means of the data base. Materials used in this study were seven kinds of carbon fibers and three kinds of epoxy resins. Reinforcing fiber and matrix resin properties strongly affected on 0 and 90 degree properties of CFRP respectively. In 0 degree tension tests, fracture mode of specimen vaned in each material, and a relationship between the scatter of strength and the fracture mode existed. From the results of 9 degree tension tests, some differences of interfacial properties between each laminate were` also detected. According to some considerations on fracture mechanism in 0 degree tension test, it was deduced that the fracture mode depended on the balance of fiber, matrix and interface properties.

  18. Wear in carbon fiber-reinforced polyethylene (poly-two) knee prostheses.

    PubMed

    Busanelli, L; Squarzoni, S; Brizio, L; Tigani, D; Sudanese, A

    1996-01-01

    The authors report a case of massive wear of carbon fiber-reinforced polyethylene used as an insert in a knee prosthesis. The finding, which was studied under a scanning electron microscope, in agreement with mechanical resistance and laboratory testing reported in the literature, confirms that this composite material (poly-two) is not more advantageous to use that ultra-high molecular weight polyethylene in terms of wear, despite favorable experimental premises.

  19. Coded excitation for infrared non-destructive testing of carbon fiber reinforced plastics.

    PubMed

    Mulaveesala, Ravibabu; Venkata Ghali, Subbarao

    2011-05-01

    This paper proposes a Barker coded excitation for defect detection using infrared non-destructive testing. Capability of the proposed excitation scheme is highlighted with recently introduced correlation based post processing approach and compared with the existing phase based analysis by taking the signal to noise ratio into consideration. Applicability of the proposed scheme has been experimentally validated on a carbon fiber reinforced plastic specimen containing flat bottom holes located at different depths.

  20. The reflectivity of carbon fiber reinforced polymer short circuit illuminated by guided microwaves

    NASA Astrophysics Data System (ADS)

    Bojovschi, A.; Scott, J.; Ghorbani, K.

    2013-09-01

    An investigation of the interaction between guided electromagnetic waves and carbon fibre reinforced polymer waveguide short circuits is presented. To determine the electromagnetic response of the composite waveguide short circuit, its anisotropic characteristics are considered. The reflection coefficients of the short circuit, at the reference plane, are about 0.98 over the whole 8 GHz to 12 GHz band. The results indicate the viability of carbon fiber based short circuits for lightweight waveguides.

  1. Interlaminar damage of carbon fiber reinforced polymer composite laminate under continuous wave laser irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Yan-Chi; Wu, Chen-Wu; Huang, Yi-Hui; Song, Hong-Wei; Huang, Chen-Guang

    2017-01-01

    The interlaminar damages were investigated on the carbon fiber reinforced polymer (CFRP) composite laminate under laser irradiation. Firstly, the laminated T700/BA9916 composites were exposed to continuous wave laser irradiation. Then, the interface cracking patterns of such composite laminates were examined by optical microscopy and scanning electron microscopy. Finally, the Finite Element Analysis (FEA) was performed to compute the interface stress of the laminates under laser irradiation. And the effects of the laser parameters on the interlaminar damage were discussed.

  2. Studying Impact Damage on Carbon-Fiber Reinforced Aircraft Composite Panels with Sonicir

    NASA Astrophysics Data System (ADS)

    Han, Xiaoyan; Zhao, Xinyue; Zhang, Ding; He, Qi; Song, Yuyang; Lubowicki, Anthony; Newaz, Golam.; Favro, Lawrence D.; Thomas, Robert L.

    2011-06-01

    Composites are becoming more important materials in commercial aircraft structures such as the fuselage and wings with the new B787 Dreamliner from Boeing which has the target to utilize 50% by weight of composite materials. Carbon-fiber reinforced composites are the material of choice in aircraft structures. This is due to their light weight and high strength (high strength-to-weight ratio), high specific stiffness, tailorability of properties, design flexibility etc. Especially, by reducing the aircraft's body weight by using such lighter structures, the cost of fuel can be greatly reduced with the high jet fuel price for commercial airlines. However, these composites are prone to impact damage and the damage may occur without any observable sign on the surface, yet resulting in delaminations and disbonds that may occur well within the layers. We are studying the impact problem with carbon-fiber reinforced composite panels and developing SonicIR for this application as a fast and wide-area NDE technology. In this paper, we present our results in studying composite structures including carbon-fiber reinforced composite materials, and preliminary quantitative studies on delamination type defect depth identification in the panels.

  3. Studying impact damage on carbon-fiber reinforced aircraft composite panels with sonicir

    SciTech Connect

    Han Xiaoyan; Zhang Ding; He Qi; Song Yuyang; Lubowicki, Anthony; Zhao Xinyue; Newaz, Golam.; Favro, Lawrence D.; Thomas, Robert L.

    2011-06-23

    Composites are becoming more important materials in commercial aircraft structures such as the fuselage and wings with the new B787 Dreamliner from Boeing which has the target to utilize 50% by weight of composite materials. Carbon-fiber reinforced composites are the material of choice in aircraft structures. This is due to their light weight and high strength (high strength-to-weight ratio), high specific stiffness, tailorability of properties, design flexibility etc. Especially, by reducing the aircraft's body weight by using such lighter structures, the cost of fuel can be greatly reduced with the high jet fuel price for commercial airlines. However, these composites are prone to impact damage and the damage may occur without any observable sign on the surface, yet resulting in delaminations and disbonds that may occur well within the layers. We are studying the impact problem with carbon-fiber reinforced composite panels and developing SonicIR for this application as a fast and wide-area NDE technology. In this paper, we present our results in studying composite structures including carbon-fiber reinforced composite materials, and preliminary quantitative studies on delamination type defect depth identification in the panels.

  4. Multilevel surface engineering of nanostructured TiO2 on carbon-fiber-reinforced polyetheretherketone.

    PubMed

    Lu, Tao; Liu, Xuanyong; Qian, Shi; Cao, Huiliang; Qiao, Yuqin; Mei, Yongfeng; Chu, Paul K; Ding, Chuanxian

    2014-07-01

    As an implantable material, carbon-fiber-reinforced polyetheretherketone (CFRPEEK) possesses an adjustable elastic modulus similar to that of cortical bone and is a prime candidate to replace metallic surgical implants. However, the bioinertness and poor osteogenic properties of CFRPEEK limit its clinical application as orthopedic implants. In this work, titanium ions are introduced energetically into CFRPEEK by plasma immersion ion implantation (PIII). Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) reveal the formation of nanopores with the side wall and bottom embedded with ∼20 nm TiO2 nanoparticles on the CFRPEEK surface. Nanoindentation measurements confirm the stability and improved elastic resistance of the structured surfaces. In vitro cell adhesion, viability assay, and real-time PCR analyses disclose enhanced adhesion, proliferation, and osteo-differentiation of rat bone mesenchymal stem cells (bMSCs). The multilevel structures on CFRPEEK also exhibit partial antibacterial activity to Staphylococcus aureus and Escherichia coli. Our results indicate that a surface with multifunctional biological properties can be produced by multilevel surface engineering and application of CFRPEEK to orthopedic and dental implants can be broadened and expedited based on this scheme.

  5. Effect of Thermal Cycling on the Tensile Behavior of Polymer Composites Reinforced by Basalt and Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Khalili, S. Mohammad Reza; Najafi, Moslem; Eslami-Farsani, Reza

    2017-01-01

    The aim of the present work was to investigate the effect of thermal cycling on the tensile behavior of three types of polymer-matrix composites — a phenolic resin reinforced with woven basalt fibers, woven carbon fibers, and hybrid basalt and carbon fibers — in an ambient environment. For this purpose, tensile tests were performed on specimens previously subjected to a certain number of thermal cycles. The ultimate tensile strength of the specimen reinforced with woven basalt fibers had by 5% after thermal cycling, but the strength of the specimen with woven carbon fibers had reduced to a value by 11% higher than that before thermal cycling.

  6. Carbon Fiber Reinforced Glass Matrix Composites for Satellite Applications

    DTIC Science & Technology

    1992-06-01

    graphite basal planes. On the other hand, a high elastic modulus fiber derived from a mesophase pitch precursor, such as P-100, has a radial...and B. V. Perov. Elsevier Science Publishers B. V., Amsterdam, 1985. 2. B. Rand, "Carbon Fibres from Mesophase Pitch " pp. 495-575 in ibid.. 3. W. K...HMU fiber and the other reinforced with pitch -based fiber (P- 100 or FT700), will be described and compared with respect to various features of the

  7. Carbon Fiber Reinforced Ceramic Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Shivakumar, Kunigal; Argade, Shyam

    2003-01-01

    This report presents a critical review of the processing techniques for fabricating continuous fiber-reinforced CMCs for possible applications at elevated temperatures. Some of the issues affecting durability of the composite materials such as fiber coatings and cracking of the matrix because of shrinkage in PIP-process are also examined. An assessment of the potential inexpensive processes is also provided. Finally three potential routes of manufacturing C/SiC composites using a technology that NC A&T developed for carbon/carbon composites are outlined. Challenges that will be encountered are also listed.

  8. Mechanical Properties of Carbon Fiber-Reinforced Aluminum Manufactured by High-Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Kachold, Franziska; Singer, Robert

    2016-08-01

    Carbon fiber reinforced aluminum was produced by a specially adapted high-pressure die casting process. The MMC has a fiber volume fraction of 27%. Complete infiltration was achieved by preheating the bidirectional, PAN-based carbon fiber body with IR-emitters to temperatures of around 750 °C. The degradation of the fibers, due to attack of atmospheric oxygen at temperatures above 600 °C, was limited by heating them in argon-rich atmosphere. Additionally, the optimization of heating time and temperature prevented fiber degradation. Only the strength of the outer fibers is reduced by 40% at the most. The fibers in core of fiber body are nearly undamaged. In spite of successful manufacturing, the tensile strength of the MMC is below strength of the matrix material. Also unidirectional MMCs with a fiber volume fraction of 8% produced under the same conditions, lack of the reinforcing effect. Two main reasons for the unsatisfactory mechanical properties were identified: First, the fiber-free matrix, which covers the reinforced core, prevents effective load transfer from the matrix to the fibers. And second, the residual stresses in the fiber-free zones are as high as 100 MPa. This causes premature failure in the matrix. From this, it follows that the local reinforcement of an actual part is limited. The stress distribution caused by residual stresses and by loading needs to be known. In this way, the reinforcing phase can be placed and aligned accordingly. Otherwise delamination and premature failure might occur.

  9. NMR detection of thermal damage in carbon fiber reinforced epoxy resins.

    PubMed

    Brady, Steven K; Conradi, Mark S; Vaccaro, Christopher M

    2005-02-01

    Composite materials of epoxy resins reinforced by carbon fibers are increasingly being used in the construction of aircraft. In these applications, the material may be thermally damaged and weakened by jet blast and accidental fires. The feasibility of using proton NMR relaxation times T1, T1rho, and T2 to detect and quantify the thermal damage is investigated. In conventional spectrometers with homogeneous static magnetic fields, T1rho is readily measured and is found to be well correlated with thermal damage. This suggests that NMR measurements of proton T1rho may be used for non-destructive evaluation of carbon fiber-epoxy composites. Results from T1rho measurements in the inhomogeneous static and RF magnetic fields of an NMR-MOUSE are also discussed.

  10. Rate dependent response and failure of a ductile epoxy and carbon fiber reinforced epoxy composite

    SciTech Connect

    Brown, Eric N; Rae, Philip J; Dattelbaum, Dana M; Stahl, David B

    2010-01-01

    An extensive characterization suite has been performed on the response and failure of a ductile epoxy 55A and uniaxial carbon fiber reinforced epoxy composite of IM7 fibers in 55A resin from the quasistatic to shock regime. The quasistatic and intermediate strain rate response, including elastic modulus, yield and failure have are characterized by quasistatic, SHPB, and DMA measurements as a function of fiber orientation and temperature. The high strain rate shock effect of fiber orientation in the composite and response of the pure resin are presented for plate impact experiments. It has previously been shown that at lower impact velocities the shock velocity is strongly dependent on fiber orientation but at higher impact velocity the in-plane and through thickness Hugoniots converge. The current results are compared with previous studies of the shock response of carbon fiber composites with more conventional brittle epoxy matrices. The spall response of the composite is measured and compared with quasistatic fracture toughness measurements.

  11. The effect of exfoliated graphite on carbon fiber reinforced composites for cryogenic applications

    NASA Astrophysics Data System (ADS)

    McLaughlin, Adam Michael

    It is desirable to lighten cryogenic fuel tanks through the use of composites for the development of a reusable single stage launch vehicle. Conventional composites fall victim to microcracking due to the cyclic loading and temperature change experienced during launch and re-entry conditions. Also, the strength of a composite is generally limited by the properties of the matrix. The introduction of the nanoplatelet, exfoliated graphite or graphene, to the matrix shows promise of increasing both the microcracking resistivity and the mechanical characteristics. Several carbon fiber composite plates were manufactured with varying concentrations of graphene and tested under both room and cryogenic conditions to characterize graphene's effect on the composite. Results from tensile and fracture testing indicate that the ideal concentration of graphene in our carbon fiber reinforced polymer composites for cryogenic applications is 0.08% mass graphene.

  12. Effect of plasma surface treatment of recycled carbon fiber on carbon fiber-reinforced plastics (CFRP) interfacial properties

    NASA Astrophysics Data System (ADS)

    Lee, Hooseok; Ohsawa, Isamu; Takahashi, Jun

    2015-02-01

    We studied the effects of plasma surface treatment of recycled carbon fiber on adhesion of the fiber to polymers after various treatment times. Conventional surface treatment methods have been attempted for recycled carbon fiber, but most require very long processing times, which may increase cost. Hence, in this study, plasma processing was performed for 0.5 s or less. Surface functionalization was quantified by X-ray photoelectron spectroscopy. O/C increased from approximately 11% to 25%. The micro-droplet test of adhesion properties and the mechanical properties of CFRP were also investigated.

  13. Effects of oxyfluorination on surface and mechanical properties of carbon fiber-reinforced polarized-polypropylene matrix composites.

    PubMed

    Kim, Hyun-Ii; Choi, Woong-Ki; Oh, Sang-Yub; Seo, Min-Kang; Park, Soo-Jin; An, Kay-Hyeok; Lee, Young Sil; Kim, Byung-Joo

    2014-12-01

    In this work, oxyfluorination treatments on carbon fiber surfaces were carried out to improve the interfacial adhesion between carbon fibers and polarized-polypropylene (P-PP). The surface properties of oxyfluorinated carbon fibers were characterized using a single fiber contact angle, and X-ray photoelectron spectroscopy. The mechanical properties of the composites were calculated in terms of work of adhesion between fibers and matrices and also measured by a critical stress intensity factor (K(IC)). The K(IC) of oxyfluorinated carbon fibers-reinforced composites showed higher values than those of as-received carbon fibers-reinforced composites. The results showed that the adhesion strength between the carbon fibers and P-PP had significantly increased after the oxyfluorination treatments. As the theoretical and practical comparisons, OF-CF-60s showed the best mechanical interfacial performance due to the good surface free energy. This indicates that oxyfluorination produced highly polar functional groups on the fiber surface, resulting in strong adhesion between carbon fibers and P-PP in this composite system.

  14. The strong diamagnetic behaviour of unidirectional carbon fiber reinforced polymer laminates

    NASA Astrophysics Data System (ADS)

    Galehdar, A.; Nicholson, K. J.; Callus, P. J.; Rowe, W. S. T.; John, S.; Wang, C. H.; Ghorbani, K.

    2012-12-01

    Carbon fibers are finite conductors with a weak diamagnetic response in a static magnetic field. When illuminated with a high-frequency alternating electromagnetic wave such that the skin depth is greater than the fiber diameter, carbon-fiber composites are shown to exhibit a strong dynamic diamagnetic response. The magnetic susceptibility (χm) is controlled by the polarization angle (θ), which is the angle between the incident electric field and conductor direction. A closed form solution for this behaviour was derived using Maxwell's equations and an understanding of the induced conductor currents. The equation was verified using simulation and free space "wall" and waveguide measurements on unidirectional IM7/977-3 carbon fiber reinforced polymer laminates. The measured responses ranged from non-magnetic at θ = 90°, χm = 0, up to strongly diamagnetic at θ = 30°, χm = -0.75, over the 8-18 GHz bandwidth. The experimental results are in good agreement with theoretical predictions and computational simulations.

  15. Physical and mechanical properties of carbon fiber reinforced smart porous concrete for planting

    NASA Astrophysics Data System (ADS)

    Park, Seung-Bum; Kim, Jung-Hwan; Seo, Dae-Seuk

    2005-05-01

    The reinforcement strength of porous concrete and its applicability as a recycled aggregate was measured. Changes in physical and mechanical properties, subsequent to the mixing of carbon fiber and silica fume, were examined, and the effect of recycled aggregate depending on their mixing rate was evaluated. The applicability of planting to concrete material was also assessed. The results showed that there were not any remarkable change in the porosity and strength characteristics although its proportion of recycled aggregate increased. Also, the mixture of 10% of silica was found to be most effective for strength enforcement. In case of carbon fiber, the highest flexural strength was obtained with its mixing rate being 3%. It was also noticed that PAN-derived carbon fiber was superior to Pitch-derived ones in view of strength. The evaluation of its use for vegetation proved that the growth of plants was directly affected by the existence of covering soil, in case of having the similar size of aggregate and void.

  16. In vivo implant fixation of carbon fiber-reinforced PEEK hip prostheses in an ovine model.

    PubMed

    Nakahara, Ichiro; Takao, Masaki; Bandoh, Shunichi; Bertollo, Nicky; Walsh, William R; Sugano, Nobuhiko

    2013-03-01

    Carbon fiber-reinforced polyetheretherketone (CFR/PEEK) is theoretically suitable as a material for use in hip prostheses, offering excellent biocompatibility, mechanical properties, and the absence of metal ions. To evaluate in vivo fixation methods of CFR/PEEK hip prostheses in bone, we examined radiographic and histological results for cementless or cemented CFR/PEEK hip prostheses in an ovine model with implantation up to 52 weeks. CFR/PEEK cups and stems with rough-textured surfaces plus hydroxyapatite (HA) coatings for cementless fixation and CFR/PEEK cups and stems without HA coating for cement fixation were manufactured based on ovine computed tomography (CT) data. Unilateral total hip arthroplasty was performed using cementless or cemented CFR/PEEK hip prostheses. Five cementless cups and stems and six cemented cups and stems were evaluated. On the femoral side, all cementless stems demonstrated bony ongrowth fixation and all cemented stems demonstrated stable fixation without any gaps at both the bone-cement and cement-stem interfaces. All cementless cases and four of the six cemented cases showed minimal stress shielding. On the acetabular side, two of the five cementless cups demonstrated bony ongrowth fixation. Our results suggest that both cementless and cemented CFR/PEEK stems work well for fixation. Cup fixation may be difficult for both cementless and cemented types in this ovine model, but bone ongrowth fixation on the cup was first seen in two cementless cases. Cementless fixation can be achieved using HA-coated CFR/PEEK implants, even under load-bearing conditions.

  17. Field applications of a carbon fiber sheet material for strengthening reinforced concrete structure

    SciTech Connect

    Thomas, J.; Kliger, H.S.; Yoshizawa, Hiroyuki

    1996-12-31

    Forca Tow Sheet is now being introduced into the USA as a viable alternative to conventional concrete strengthen techniques. This carbon fiber shoot material is externally bonded to reinforced concrete and masonry structures and serves to strengthen existing conditions. Based on the growing use of Tow Sheet in the Japanese market die US infrastructure market is beginning to apply this technology on a number of diverse repair projects. This paper describes actual field applications on industrial and public structures in the US and Japan. Also included are the results of one yen of monitoring of die Japanese structure.

  18. Anomalous enhancement of drilling rate in carbon fiber reinforced plastic using azimuthally polarized CO2 laser

    NASA Astrophysics Data System (ADS)

    Endo, Masamori; Araya, Naohiro; Kurokawa, Yuki; Uno, Kazuyuki

    2016-09-01

    We developed an azimuthally polarized pulse-periodic CO2 laser for high-performance drilling applications. We discovered an anomalous enhancement in the drilling rate with the azimuthally polarized beam compared to that with radially or randomly polarized beams. We drilled 0.45 mm-thick carbon fiber reinforced plastic (CFRP) using a focusing lens with a focal length of 50 mm and a numerical aperture (NA) of 0.09. The conditions other than polarization states were identical for all the experiments. The azimuthally polarized beam exhibited a drilling rate more than 10 times greater on average than those of the other two polarizations.

  19. Nondestructive Evaluation of Carbon Fiber Reinforced Polymer Composites Using Reflective Terahertz Imaging.

    PubMed

    Zhang, Jin; Li, Wei; Cui, Hong-Liang; Shi, Changcheng; Han, Xiaohui; Ma, Yuting; Chen, Jiandong; Chang, Tianying; Wei, Dongshan; Zhang, Yumin; Zhou, Yufeng

    2016-06-14

    Terahertz (THz) time-domain spectroscopy (TDS) imaging is considered a nondestructive evaluation method for composite materials used for examining various defects of carbon fiber reinforced polymer (CFRP) composites and fire-retardant coatings in the reflective imaging modality. We demonstrate that hidden defects simulated by Teflon artificial inserts are imaged clearly in the perpendicular polarization mode. The THz TDS technique is also used to measure the thickness of thin fire-retardant coatings on CFRP composites with a typical accuracy of about 10 micrometers. In addition, coating debonding is successfully imaged based on the time-delay difference of the time-domain waveforms between closely adhered and debonded sample locations.

  20. Selective Carbon Fiber Reinforced Nylon 66 Spur Gears: Development and Performance

    NASA Astrophysics Data System (ADS)

    Senthilvelan, S.; Gnanamoorthy, R.

    2006-01-01

    A new design methodology is developed to mold the polymer spur gears with high strength fiber reinforcement only in the highly stressed region. High performance high cost short carbon fiber reinforced Nylon 66 is used in the highly stressed tooth region and low cost unreinforced Nylon 66 is used in the hub region. Two different geometries, circular and spline shaped hubs were used for developing the selective reinforced gears by multi-shot injection-molding process. Joint strength of the selectively reinforced gear was estimated using shear tests. Clear hub and tooth region separation without any distortion was observed in joint shear tests. A molten material due to fusion bonding was observed at the interfaces. The joint strength was also evaluated by conducting gear fatigue tests using a power absorption test rig at various torque levels and at a constant gear rotational speed. Monolithic reinforced gear and selective reinforced gears with spline hub exhibited similar fatigue behavior. The failure mode depends upon the test torque level. The selective reinforced gears with circular hub showed joint failures at high-test torque levels. Absence of mechanical interlocking feature in the circular hub geometry contributes to the joint failure. Thermal bond, part interference and mechanical interlocking feature provide sufficient joint strength to the selective reinforced gear with spline hub.

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

    PubMed

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

    2002-01-15

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

  2. Development of Rapid Pipe Moulding Process for Carbon Fiber Reinforced Thermoplastics by Direct Resistance Heating

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuto; Harada, Ryuki; Uemura, Toshiki; Katayama, Tsutao; Kuwahara, Hideyuki

    To deal with environmental issues, the gasoline mileage of passenger cars can be improved by reduction of the car weight. The use of car components made of Carbon Fiber Reinforced Plastics (CFRP) is increasing because of its superior mechanical properties and relatively low density. Many vehicle structural parts are pipe-shaped, such as suspension arms, torsion beams, door guard bars and impact beams. A reduction of the car weight is expected by using CFRP for these parts. Especially, when considering the recyclability and ease of production, Carbon Fiber Reinforced Thermoplastics are a prime candidate. On the other hand, the moulding process of CFRTP pipes for mass production has not been well established yet. For this pipe moulding process an induction heating method has been investigated already, however, this method requires a complicated coil system. To reduce the production cost, another system without such complicated equipment is to be developed. In this study, the pipe moulding process of CFRTP using direct resistance heating was developed. This heating method heats up the mould by Joule heating using skin effect of high-frequency current. The direct resistance heating method is desirable from a cost perspective, because this method can heat the mould directly without using any coils. Formerly developed Non-woven Stitched Multi-axial Cloth (NSMC) was used as semi-product material. NSMC is very suitable for the lamination process due to the fact that non-crimp stitched carbon fiber of [0°/+45°/90°/-45°] and polyamide 6 non-woven fabric are stitched to one sheet, resulting in a short production cycle time. The use of the pipe moulding process with the direct resistance heating method in combination with the NSMC, has resulted in the successful moulding of a CFRTP pipe of 300 mm in length, 40 mm in diameter and 2 mm in thickness.

  3. Suitability of carbon fiber-reinforced polyetheretherketone cages for use as anterior struts following corpectomy.

    PubMed

    Heary, Robert F; Parvathreddy, Naresh K; Qayumi, Zainab S; Ali, Naiim S; Agarwal, Nitin

    2016-08-01

    OBJECTIVE Fibular allograft remains a widely used strut for corpectomy surgeries. The amount of graft material that can be packed into an allograft strut has not been quantified. Cages are an alternative to fibular allograft for fusion surgeries. The authors of this study assessed the suitability of carbon fiber-reinforced polyetheretherketone (CFRP) cages for anterior corpectomy surgeries. They further explored the parameters known to affect fusion rates in clinical practice. METHODS Six fibular allografts were tested at standard lengths. Three sets of carbon fiber cages (Bengal, DePuy Spine), each with a different footprint size but the same lengths, were tested. The allografts and cages were wrapped in adhesive, fluid-tight transparent barriers and filled with oil. The volume and weight of the oil instilled as well as the implant footprints were measured. The fibular allografts and cages were tested at 20-, 40-, and 50-mm lengths. Two investigators independently performed all measurements 5 times. Five CFRP cubes (1 × 1 × 1 cm) were tested under pure compression, and load versus displacement curves were plotted to determine the modulus of elasticity. RESULTS Significantly more oil fit in the CFRP cages than in the fibular allografts (p < 0.0001). The weight and volume of oil was 4-6 times greater in the cages. Interobserver (r = 0.991) and intraobserver (r = 0.993) reliability was excellent. The modulus of elasticity for CFRP was 16.44 ± 2.07 GPa. CONCLUSIONS Carbon fiber-reinforced polyetheretherketone cages can accommodate much more graft material than can fibular allografts. In clinical practice, the ability to deliver greater amounts of graft material following a corpectomy may improve fusion rates.

  4. Crashworthiness characteristics of a carbon fiber reinforced dual-phase epoxy–polyurea hybrid matrix composite

    DOE PAGES

    Zhou, Hongyu; Attard, Thomas L.; Dhiradhamvit, Kittinan; ...

    2014-11-07

    In this paper, the crashworthiness characteristics of rectangular tubes made from a Carbon-fiber reinforced Hybrid-Polymeric Matrix (CHMC) composite were investigated using quasi-static and impact crush tests. The hybrid matrix formulation of the CHMC was created by combining an epoxy-based thermosetting polymer with a lightly crosslinked polyurea elastomer at various cure-time intervals and volumetric ratios. The load–displacement responses of both CHMC and carbon-fiber reinforced epoxy (CF/epoxy) specimens were obtained under various crushing speeds; and crashworthiness parameters, such as the average crushing force and specific energy absorption (SEA), were calculated using subsequent load–displacement relationships. The CHMC maintained a high level of structuralmore » integrity and post-crush performance, relative to traditional CF/epoxy. The influence of the curing time and volumetric ratios of the polyurea/epoxy dual-hybridized matrix system on the crashworthiness parameters was also investigated. The results reveal that the load carrying capacity and total energy absorption tend to increase with greater polyurea thickness and lower elapsed reaction curing time of the epoxy although this is typically a function of the loading rate. In conclusion, the mechanism by which the CHMC provides increased damage tolerance was also investigated using scanning electron microscopy (SEM).« less

  5. Crashworthiness characteristics of a carbon fiber reinforced dual-phase epoxy–polyurea hybrid matrix composite

    SciTech Connect

    Zhou, Hongyu; Attard, Thomas L.; Dhiradhamvit, Kittinan; Wang, Yanli; Erdman, Donald

    2014-11-07

    In this paper, the crashworthiness characteristics of rectangular tubes made from a Carbon-fiber reinforced Hybrid-Polymeric Matrix (CHMC) composite were investigated using quasi-static and impact crush tests. The hybrid matrix formulation of the CHMC was created by combining an epoxy-based thermosetting polymer with a lightly crosslinked polyurea elastomer at various cure-time intervals and volumetric ratios. The load–displacement responses of both CHMC and carbon-fiber reinforced epoxy (CF/epoxy) specimens were obtained under various crushing speeds; and crashworthiness parameters, such as the average crushing force and specific energy absorption (SEA), were calculated using subsequent load–displacement relationships. The CHMC maintained a high level of structural integrity and post-crush performance, relative to traditional CF/epoxy. The influence of the curing time and volumetric ratios of the polyurea/epoxy dual-hybridized matrix system on the crashworthiness parameters was also investigated. The results reveal that the load carrying capacity and total energy absorption tend to increase with greater polyurea thickness and lower elapsed reaction curing time of the epoxy although this is typically a function of the loading rate. In conclusion, the mechanism by which the CHMC provides increased damage tolerance was also investigated using scanning electron microscopy (SEM).

  6. [Tribological properties of carbon fiber-reinforced plastic. Experimental and clinical results].

    PubMed

    Früh, H J; Ascherl, R; Hipp, E

    1997-02-01

    Wear of the articulating components (especially PE-UHMW) of total hip endoprostheses is the most important technical factor limiting the functional lifetime. To minimize wear debris, ceramic heads, according to ISO 6474 (Al2O3), have been used, from 1969 paired with Al2O3 and since 1975 paired with PE-UHMW. Al2O3 balls articulating with cups made from CFRP have been in clinical use since 1988. Laboratory experiments and in-vivo testing showed minimized wear debris and mild biological response to wear products using CFRP (carbon fiber reinforced plastic) instead of PE-UHMW as the cup material. The articulating surfaces of retrieved ceramic heads (Al2O3-Biolox) and cementless CFRP cups (carbon fiber reinforced plastic, Caproman) were compared using sphericity measurement techniques, scanning electron microscopy (SEM) and roughness measurements (including advanced roughness parameters Rvk or Rpk according to ISO 4287). Altogether, the first results of the clinical study showed that the combination Al2O3-ball/CFRP-cup came up to the expected lower wear rates compared with the conventional combinations. The wear rates are comparable with the combination Al2O3/Al2O3 without the material-related problems of ceramic components in all ceramic combinations.

  7. Strength Evaluation and Failure Prediction of Short Carbon Fiber Reinforced Nylon Spur Gears by Finite Element Modeling

    NASA Astrophysics Data System (ADS)

    Hu, Zhong; Hossan, Mohammad Robiul

    2013-06-01

    In this paper, short carbon fiber reinforced nylon spur gear pairs, and steel and unreinforced nylon spur gear pairs have been selected for study and comparison. A 3D finite element model was developed to simulate the multi-axial stress-strain behaviors of the gear tooth. Failure prediction has been conducted based on the different failure criteria, including Tsai-Wu criterion. The tooth roots, where has stress concentration and the potential for failure, have been carefully investigated. The modeling results show that the short carbon fiber reinforced nylon gear fabricated by properly controlled injection molding processes can provide higher strength and better performance.

  8. Active rigidization of carbon-fiber reinforced polymer composites for ultra-lightweight space structures

    NASA Astrophysics Data System (ADS)

    Sarles, Stephen A.; Leo, Donald J.

    2006-03-01

    An active approach for initiating rigidization in carbon-fiber reinforced polymer (CFRP) thermosets links controllable mechanical stiffening to inherent electrical resistivity. With direct applications toward the rigidization of ultra-lightweight, inflatable space structures, temperature-controlled resistive heating is used to create oncommand rigidization. As required by the on-orbit conditions in space, flexible, rigidizable structures demand stable and space-survivable materials that incorporate techniques for providing shape control and structural stiffening. Methods currently employed to achieve a mechanical hardening include many passive techniques: UV curing, sub-T g hardening, and hydro-gel evaporation. The benefits of a passive system (simplicity, energy efficiency) are offset by their inherent lack of control, which can lead to long curing times and weak spots due to uneven curing. In efforts to significantly reduce the transition time of the composite from a structurally-vulnerable state to a fully-rigidized shape and to increase control of the curing process, an active approach is taken. Specifically, temperature-controlled internal resistive heating initiates thermoset curing in a coated carbon fiber composite to form an electrically-controlled, thermally-activated material. Through controlled heating, this research examines how selective temperature control can be used to prescribe matrix consolidation and material rigidization on two different thermosetting resins, U-Nyte Set 201A and 201B. Feedback temperature control, based on a PID control algorithm, was applied to the process of resistive heating. Precise temperature tracking (less than 1.1°C RMS or +/-3.3% error) was achieved for controlled sample heating. Using samples of the thermoset-coated carbon-fiber tow, composite hardening through resistive heating occurred in 24 minutes and required roughly 1 W-hr/inch of electrical energy. The rigidized material was measured to be 14-21 times stiffer

  9. Material characterization of several resin systems for high temperature carbon fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Yoon, Sung Ho; Oh, Jin Oh; Choi, Dong Hyun; Lee, Sang Woo

    2011-11-01

    Material characterization of several resin systems for high temperature carbon fiber reinforced composites was performed through a series of the tensile test, the dynamic mechanical analysis (DMA) test, and the strand test. The modified tensile specimens and the DMA specimens were used to evaluate the tensile and thermal analysis properties of resin systems. The strand specimens were used to evaluate the tensile properties and load transfer efficiencies of the specimens. Four types of resin systems were considered. One was a conventional resin system currently used for filament wound structures and other three were high temperature resin systems. According to the tensile and DMA test results, the tensile modulus decreases slightly and the tensile strength decreases rapidly until the temperature reaches glass transition temperature. The tensile modulus and tensile strength are almost negligible above glass transition temperature. The tensile modulus obtained from the tensile test is consistent with that from the DMA test at different temperatures. From the strand test results, considering, the load transfer efficiency is found to be around 87 to 90 % of the tensile strength of T800H-12K carbon fibers for all resin systems except the specimen with the Type 2. Finally we found that the Type 4 is the best candidate for high temperature resin system applicable to filament wound structures in the view of the glass transition temperature as well as the tensile properties.

  10. Material characterization of several resin systems for high temperature carbon fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Yoon, Sung Ho; Oh, Jin Oh; Choi, Dong Hyun; Lee, Sang Woo

    2012-04-01

    Material characterization of several resin systems for high temperature carbon fiber reinforced composites was performed through a series of the tensile test, the dynamic mechanical analysis (DMA) test, and the strand test. The modified tensile specimens and the DMA specimens were used to evaluate the tensile and thermal analysis properties of resin systems. The strand specimens were used to evaluate the tensile properties and load transfer efficiencies of the specimens. Four types of resin systems were considered. One was a conventional resin system currently used for filament wound structures and other three were high temperature resin systems. According to the tensile and DMA test results, the tensile modulus decreases slightly and the tensile strength decreases rapidly until the temperature reaches glass transition temperature. The tensile modulus and tensile strength are almost negligible above glass transition temperature. The tensile modulus obtained from the tensile test is consistent with that from the DMA test at different temperatures. From the strand test results, considering, the load transfer efficiency is found to be around 87 to 90 % of the tensile strength of T800H-12K carbon fibers for all resin systems except the specimen with the Type 2. Finally we found that the Type 4 is the best candidate for high temperature resin system applicable to filament wound structures in the view of the glass transition temperature as well as the tensile properties.

  11. Mechanical properties of neat polymer matrix materials and their unidirectional carbon fiber-reinforced composites

    NASA Technical Reports Server (NTRS)

    Zimmerman, Richard S.; Adams, Donald F.

    1988-01-01

    The mechanical properties of two neat resin systems for use in carbon fiber epoxy composites were characterized. This included tensile and shear stiffness and strengths, coefficients of thermal and moisture expansion, and fracture toughness. Tests were conducted on specimens in the dry and moisture-saturated states, at temperatures of 23, 82 and 121 C. The neat resins tested were American Cyanamid 1806 and Union Carbide ERX-4901B(MPDA). Results were compared to previously tested neat resins. Four unidirectional carbon fiber reinforced composites were mechanically characterized. Axial and transverse tension and in-plane shear strengths and stiffness were measured, as well as transverse coefficients of thermal and moisture expansion. Tests were conducted on dry specimens only at 23 and 100 C. The materials tested were AS4/3502, AS6/5245-C, T300/BP907, and C6000/1806 unidirectional composites. Scanning electron microscopic examination of fracture surfaces was performed to permit the correlation of observed failure modes with the environmental test conditions.

  12. Optics of carbon fiber-reinforced plastics - A theoretical and an experimental study

    NASA Astrophysics Data System (ADS)

    Hohmann, Ansgar; ElMaklizi, Ahmed; Foschum, Florian; Voit, Florian; Bergmann, Florian; Simon, Emanuel; Reitzle, Dominik; Kienle, Alwin

    2016-09-01

    Laser processing of carbon fiber-reinforced plastics (CFRP) as well as their design optimization are strongly emerging fields. As the optics of CFRP is still rather unknown, the optical behavior of CFRP was investigated in this study. Different simulation models were implemented to simulate reflectance from CFRP samples as well as distribution and absorption of light within these samples. The methods include an analytical solution of Maxwell's equations and Monte Carlo solutions of the radiative transfer theory. We show that strong inaccurracies occur, if light propagation in CFRP is modeled using the radiative transfer theory. Therefore, the solution of Maxwell's equations is the method of choice for calculation of light propagation in CFRP. Furthermore, measurements of the reflectance of light from CFRP were performed and compared to the simulations for investigation of the optical behavior. Information on the refractive index of carbon fibers was obtained via goniometric measurements. The amount of reflected light was determined as 6.05±0.38% for light polarized parallel to the fiber direction, while it was 3.65±0.41% for light polarized perpendicular to the fiber direction in case of laser-processed CFRP.

  13. Laser Processing of Carbon Fiber Reinforced Plastics - Release of Carbon Fiber Segments During Short-pulsed Laser Processing of CFRP

    NASA Astrophysics Data System (ADS)

    Walter, Juergen; Brodesser, Alexander; Hustedt, Michael; Bluemel, Sven; Jaeschke, Peter; Kaierle, Stefan

    Cutting and ablation using short-pulsed laser radiation are promising technologies to produce or repair CFRP components with outstanding mechanical properties e.g. for automotive and aircraft industry. Using sophisticated laser processing strategies and avoiding excessive heating of the workpiece, a high processing quality can be achieved. However, the interaction of laser radiation and composite material causes a notable release of hazardous substances from the process zone, amongst others carbon fiber segments or fibrous particles. In this work, amounts and geometries of the released fiber segments are analyzed and discussed in terms of their hazardous potential. Moreover, it is investigated to what extent gaseous organic process emissions are adsorbed at the fiber segments, similar to an adsorption of volatile organic compounds at activated carbon, which is typically used as filter material.

  14. Clinical evaluation of carbon fiber reinforced carbon endodontic post, glass fiber reinforced post with cast post and core: A one year comparative clinical study

    PubMed Central

    Preethi, GA; Kala, M

    2008-01-01

    Aim: Restoring endodontically treated teeth is one of the major treatments provided by the dental practitioner. Selection and proper use of restorative materials continues to be a source of frustration for many clinicians. There is controversy surrounding the most suitable choice of restorative material and the placement method that will result in the highest probability of successful treatment. This clinical study compares two different varieties of fiber posts and one cast post and core in terms of mobility of crown margin under finger pressure, recurrent caries detected at the crown margin, fracture of the restoration, fracture of the root and periapical and periodontal pathology requiring crown removal over the period of 12months as evaluated by clinical and radiographical examination. Materials and Methods: 30 root canal treated, single rooted maxillary anterior teeth of 25 patients in the age range of 18–60 years where a post retained crown was indicated were selected for the study between January 2007 and August 2007; and prepared in a standard clinical manner. It was divided into 3 groups of 10 teeth in each group. After post space preparation, the Carbon fiber and Glass fiber reinforced posts were cemented with Scotch bond multipurpose plus bonding agent and RelyX adhesive resin cement in the first and second groups respectively. The Cast post and cores were cemented with Zinc Phosphate cement in the third group. Following post- cementation, the preparation was further refined and a rubber base impression was taken for metal-ceramic crowns which was cemented with Zinc Phosphate cement. A baseline periapical radiograph was taken once each crown was cemented. All patients were evaluated after one week (baseline), 3 months, 6 months and one year for following characteristics mobility of crown margin under finger pressure, recurrent caries detected at the crown margin, fracture of the restoration, fracture of the root and periapical and periodontal pathology

  15. Ultrasonic inspection of carbon fiber reinforced plastic by means of sample-recognition methods

    NASA Technical Reports Server (NTRS)

    Bilgram, R.

    1985-01-01

    In the case of carbon fiber reinforced plastic (CFRP), it has not yet been possible to detect nonlocal defects and material degradation related to aging with the aid of nondestructive inspection method. An approach for overcoming difficulties regarding such an inspection involves an extension of the ultrasonic inspection procedure on the basis of a use of signal processing and sample recognition methods. The basic concept involved in this approach is related to the realization that the ultrasonic signal contains information regarding the medium which is not utilized in conventional ultrasonic inspection. However, the analytical study of the phyiscal processes involved is very complex. For this reason, an empirical approach is employed to make use of the information which has not been utilized before. This approach uses reference signals which can be obtained with material specimens of different quality. The implementation of these concepts for the supersonic inspection of CFRP laminates is discussed.

  16. Graphite Sheet Coating for Improved Thermal Oxidative Stability of Carbon Fiber Reinforced/PMR-15 Composites

    NASA Technical Reports Server (NTRS)

    Campbell, Sandi; Papadopoulos, Demetrios; Heimann, Paula; Inghram, Linda; McCorkle, Linda

    2005-01-01

    Expanded graphite was compressed into graphite sheets and used as a coating for carbon fiber reinforced PMR-15 composites. BET analysis of the graphite indicated an increase in graphite pore size on compression, however the material was proven to be an effective barrier to oxygen when prepegged with PMR-15 resin. Oxygen permeability of the PMR-15/graphite was an order of magnitude lower than the compressed graphite sheet. By providing a barrier to oxygen permeation, the rate of oxidative degradation of PMR-15 was decreased. As a result, the composite thermo-oxidative stability increased by up to 25%. The addition of a graphite sheet as a top ply on the composites yielded little change in the material's flexural strength or interlaminar shear strength.

  17. Wear of ceramic-on-carbon fiber-reinforced poly-ether ether ketone hip replacements.

    PubMed

    Brockett, Claire L; John, Gemma; Williams, Sophie; Jin, Zhongmin; Isaac, Graham H; Fisher, John

    2012-08-01

    Total hip replacement has been a successful surgical intervention for over 50 years, with the majority of bearings using a polyethylene cup. Long-term failure due to osteolysis and loosening has been widely documented and alternative bearings have been sought. A novel carbon fiber-reinforced poly-ether ether ketone (CFR-PEEK) cup was investigated through experimental friction and wear studies. Friction studies demonstrated the bearings operated in a boundary lubrication condition, with friction factors higher than those for other hip replacement bearings. The wear study was conducted with 36 mm diameter bearings tested against Biolox Delta heads for a period of 10 million cycles. The mean volumetric wear rate was 0.3 mm(3)/Mc, indicating the ceramic-on-CFR-PEEK bearing to be a very low wearing option for total hip replacement.

  18. Nondestructive Evaluation of Carbon Fiber Reinforced Polymer Composites Using Reflective Terahertz Imaging

    PubMed Central

    Zhang, Jin; Li, Wei; Cui, Hong-Liang; Shi, Changcheng; Han, Xiaohui; Ma, Yuting; Chen, Jiandong; Chang, Tianying; Wei, Dongshan; Zhang, Yumin; Zhou, Yufeng

    2016-01-01

    Terahertz (THz) time-domain spectroscopy (TDS) imaging is considered a nondestructive evaluation method for composite materials used for examining various defects of carbon fiber reinforced polymer (CFRP) composites and fire-retardant coatings in the reflective imaging modality. We demonstrate that hidden defects simulated by Teflon artificial inserts are imaged clearly in the perpendicular polarization mode. The THz TDS technique is also used to measure the thickness of thin fire-retardant coatings on CFRP composites with a typical accuracy of about 10 micrometers. In addition, coating debonding is successfully imaged based on the time-delay difference of the time-domain waveforms between closely adhered and debonded sample locations. PMID:27314352

  19. Carbon fiber/copper mesh reinforced carbon composite for sliding contact material

    NASA Astrophysics Data System (ADS)

    Deng, Chaoyong; Zhang, Hongbo; Yin, Jian; Xiong, Xiang; Wang, Pei; Sun, Miao

    2017-02-01

    A novel carbon fiber/copper mesh knitted fabric reinforced carbon (Cf/Cu/C) composite was fabricated by a CVI-I/C technique. The mechanical, electrical, arc discharge and tribological properties of the Cf/Cu/C composite were compared with those of a traditional C/Cu composite fabricated by powder metallurgy. The results show that the copper mesh distributes uniformly in the Cf/Cu/C composite, and it exhibits higher mechanical property and more excellent electrical resistivity than those of the C/Cu composite. Meanwhile, the arc resistance property of Cf/Cu/C composite is also better than the C/Cu composite under the same testing conditions. The wear rate is about 80% of the C/Cu composite.

  20. Multifunctional integration of thin-film silicon solar cells on carbon-fiber-reinforced epoxy composites

    SciTech Connect

    Jason Maung, K.; Hahn, H. Thomas; Ju, Y.S.

    2010-03-15

    Multifunction integration of solar cells in load-bearing structures can enhance overall system performance by reducing parasitic components and material redundancy. The article describes a manufacturing strategy, named the co-curing scheme, to integrate thin-film silicon solar cells on carbon-fiber-reinforced epoxy composites and eliminate parasitic packaging layers. In this scheme, an assembly of a solar cell and a prepreg is cured to form a multifunctional composite in one processing step. The photovoltaic performance of the manufactured structures is then characterized under controlled cyclic mechanical loading. The study finds that the solar cell performance does not degrade under 0.3%-strain cyclic tension loading up to 100 cycles. Significant degradation, however, is observed when the magnitude of cyclic loading is increased to 1% strain. The present study provides an initial set of data to guide and motivate further studies of multifunctional energy harvesting structures. (author)

  1. Segmenting delaminations in carbon fiber reinforced polymer composite CT using convolutional neural networks

    NASA Astrophysics Data System (ADS)

    Sammons, Daniel; Winfree, William P.; Burke, Eric; Ji, Shuiwang

    2016-02-01

    Nondestructive evaluation (NDE) utilizes a variety of techniques to inspect various materials for defects without causing changes to the material. X-ray computed tomography (CT) produces large volumes of three dimensional image data. Using the task of identifying delaminations in carbon fiber reinforced polymer (CFRP) composite CT, this work shows that it is possible to automate the analysis of these large volumes of CT data using a machine learning model known as a convolutional neural network (CNN). Further, tests on simulated data sets show that with a robust set of experimental data, it may be possible to go beyond just identification and instead accurately characterize the size and shape of the delaminations with CNNs.

  2. First light with a carbon fiber reinforced polymer 0.4 meter telescope

    NASA Astrophysics Data System (ADS)

    Wilcox, Christopher C.; Santiago, Freddie; Jungwirth, Matthew E.; Martinez, Ty; Restaino, Sergio R.; Bagwell, Brett; Romeo, Robert

    2014-03-01

    For the passed several years, the Naval Research Laboratory (NRL) has been investigating the use of Carbon Fiber Reinforced Polymer (CFRP) material in the construction of a telescope assembly including the optical components. The NRL, Sandia National Laboratories (SNL), and Composite Mirror Applications, Inc. (CMA) have jointly assembled a prototype telescope and achieved "first light" images with a CFRP 0.4 m aperture telescope. CFRP offers several advantages over traditional materials such as creating structures that are lightweight and low coefficient of thermal expansion and conductivity. The telescope's primary and secondary mirrors are not made from glass, but CFRP, as well. The entire telescope weighs approximately 10 kg while a typical telescope of this size would weigh quite a bit more. We present the achievement of "first light" with this telescope demonstrating the imaging capabilities of this prototype and the optical surface quality of the mirrors with images taken during a day's quiescent periods.

  3. Carbon Fiber Reinforced Polymer (CFRP) Optics Quality Assessment for Lightweight Deployable Optics

    NASA Astrophysics Data System (ADS)

    Andrews, J.; Martinez, T.; Restaino, S.; Santiago, F.; Wilcox, C.; Teare, S.; Romeo, R.; Martin, R.

    2010-09-01

    The Naval Research Laboratory and Composite Mirror Applications (CMA) have been working together for several years on the development of Carbon Fiber Reinforced Polymer (CFRP) optics and telescopes. We have documented the potential advantages of this technology in several other publications, including structural, thermal and weight advantages over traditional steel and glass optical systems. In this paper we present results of a battery of optical tests done on various CFRP replicated mirrors. Our goal is to demonstrate not only the optical quality of such mirrors but also their reproducibility and stability. We show test results on a sample of four mirrors. We performed extensive optical tests and also stability and repeatability tests. These tests are geared towards proving the use of this technology for a variety of optical applications including use in our CFRP telescopes.

  4. Low-velocity impact damage characterization of carbon fiber reinforced polymer (CFRP) using infrared thermography

    NASA Astrophysics Data System (ADS)

    Li, Yin; Zhang, Wei; Yang, Zheng-wei; Zhang, Jin-yu; Tao, Sheng-jie

    2016-05-01

    Carbon fiber reinforced polymer (CFRP) after low-velocity impact is detected using infrared thermography, and different damages in the impacted composites are analyzed in the thermal maps. The thermal conductivity under pulse stimulation, frictional heating and thermal conductivity under ultrasonic stimulation of CFRP containing low-velocity impact damage are simulated using numerical simulation method. Then, the specimens successively exposed to the low-velocity impact are respectively detected using the pulse infrared thermography and ultrasonic infrared thermography. Through the numerical simulation and experimental investigation, the results obtained show that the combination of the above two detection methods can greatly improve the capability for detecting and evaluating the impact damage in CFRP. Different damages correspond to different infrared thermal images. The delamination damage, matrix cracking and fiber breakage are characterized as the block-shape hot spot, line-shape hot spot, and

  5. Influence of attenuation on acoustic emission signals in carbon fiber reinforced polymer panels.

    PubMed

    Asamene, Kassahun; Hudson, Larry; Sundaresan, Mannur

    2015-05-01

    Influence of attenuation on acoustic emission (AE) signals in Carbon Fiber Reinforced Polymer (CFRP) crossply and quasi-isotropic panels is examined in this paper. Attenuation coefficients of the fundamental antisymmetric (A0) and symmetric (S0) wave modes were determined experimentally along different directions for the two types of CFRP panels. In the frequency range from 100 kHz to 500 kHz, the A0 mode undergoes significantly greater changes due to material related attenuation compared to the S0 mode. Moderate to strong changes in the attenuation levels were noted with propagation directions. Such mode and frequency dependent attenuation introduces major changes in the characteristics of AE signals depending on the position of the AE sensor relative to the source. Results from finite element simulations of a microscopic damage event in the composite laminates are used to illustrate attenuation related changes in modal and frequency components of AE signals.

  6. Oxygen-assisted multipass cutting of carbon fiber reinforced plastics with ultra-short laser pulses

    SciTech Connect

    Kononenko, T. V.; Komlenok, M. S.; Konov, V. I.; Freitag, C.; Onuseit, V.; Weber, R.; Graf, T.

    2014-03-14

    Deep multipass cutting of bidirectional and unidirectional carbon fiber reinforced plastics (CFRP) with picosecond laser pulses was investigated in different static atmospheres as well as with the assistance of an oxygen or nitrogen gas flow. The ablation rate was determined as a function of the kerf depth and the resulting heat affected zone was measured. An assisting oxygen gas flow is found to significantly increase the cutting productivity, but only in deep kerfs where the diminished evaporative ablation due to the reduced laser fluence reaching the bottom of the kerf does not dominate the contribution of reactive etching anymore. Oxygen-supported cutting was shown to also solve the problem that occurs when cutting the CFRP parallel to the fiber orientation where a strong deformation and widening of the kerf, which temporarily slows down the process speed, is revealed to be typical for processing in standard air atmospheres.

  7. Laser Cutting of Carbon Fiber Reinforced Polymers using Highly Brilliant Laser Beam Sources

    NASA Astrophysics Data System (ADS)

    Klotzbach, Annett; Hauser, Markus; Beyer, Eckhard

    Carbon fiber reinforced polymers (CFRP) are applied more and more in the aircraft industry as well as in the automobile industry. The principal reason is the highly mechanical load capacity along with the low density. Moreover, the corrosion resistance plus the damping behavior of the material can be utilized fully in highly stressed structures. However, the concept of manufacture CFRP-parts close to the final contour does not substitute the need of cutting them. The different properties of fiberand matrix-material constitute an ambitious challenge while cutting CFRP using a laser beam. This paper deals with elementary analysis of the laser remote cutting process and the gas assisted laser cutting of CFRP.

  8. Basic failure mechanisms in advanced composites. [composed of epoxy resins reinforced with carbon fibers

    NASA Technical Reports Server (NTRS)

    Mazzio, V. F.; Mehan, R. L.; Mullin, J. V.

    1973-01-01

    The fundamental failure mechanisms which result from the interaction of thermal cycling and mechanical loading of carbon-epoxy composites were studied. This work was confined to epoxy resin uniderictionally reinforced with HTS carbon fibers, and consists of first identifying local fiber, matrix and interface failure mechanisms using the model composite specimen containing a small number of fibers so that optical techniques can be used for characterization. After the local fracture process has been established for both mechanical loading and thermal cycling, engineering composite properties and gross fracture modes are then examined to determine how the local events contribute to real composite performance. Flexural strength in high fiber content specimens shows an increase in strength with increased thermal cycling. Similar behavior is noted for 25 v/o material up to 200 cycles; however, there is a drastic reduction after 200 cycles indicating a major loss of integrity probably through the accumulation of local cleavage cracks in the tensile region.

  9. Effect of tool wear on quality of carbon fiber reinforced polymer laminate during edge trimming

    NASA Astrophysics Data System (ADS)

    Hamedanianpour, Hossein

    Polymer matrix composites, especially carbon fiber reinforced polymers (CFRPs) are vastly used in different high technology industries, including aerospace, automotive and wind energy. Normally, when CFRPs are cured to near net shape, finishing operations such as trimming, milling or drilling are used to remove excess materials. The quality of these finishing operations is highly essential at the level of final assembly. The present study aims to study the effect of cutting tool wear on the resulting quality for the trimming process of high performance CFRP laminates, in the aerospace field. In terms of quality parameters, the study focuses on surface roughness and material integrity damages (uncut fibers, fiber pullout, delamination or thermal damage of the matrix), which could jeopardize the mechanical performance of the components. In this study, a 3/8 inch diameter CVD diamond coated carbide tool with six flutes was used to trim 24-ply carbon fiber laminates. Cutting speeds ranging from 200 m/min to 400 m/min and feed rates ranging from 0.3048 mm/rev to 0.4064 mm/rev were used in the experiments. The results obtained using a scanning electron microscope (SEM) showed increasing defect rates with an increase in tool wear. The worst surface integrity, including matrix cracking, fiber pull-out and empty holes, was also observed for plies oriented at -45° degrees. For the surface finish, it was observed that an increase in tool wear resulted in a decrease in surface roughness. Regarding tool wear, a lower rate was observed at lower feed rates and higher cutting speeds, while a higher tool wear rate was observed at intermediate values of our feed rate and cutting speed ranges.

  10. Spectroscopic study of terahertz reflection and transmission properties of carbon-fiber-reinforced plastic composites

    NASA Astrophysics Data System (ADS)

    Zhang, Jin; Shi, Changcheng; Ma, Yuting; Han, Xiaohui; Li, Wei; Chang, Tianying; Wei, Dongshan; Du, Chunlei; Cui, Hong-Liang

    2015-05-01

    Carbon-fiber-reinforced plastic (CFRP) composites are widely used in aerospace and concrete structure reinforcement due to their high strength and light weight. Terahertz (THz) time-domain spectroscopy is an attractive tool for defect inspection in CFRP composites. In order to improve THz nondestructive testing of CFRP composites, we have carried out systematic investigations of THz reflection and transmission properties of CFRP. Unidirectional CFRP composites with different thicknesses are measured with polarization directions 0 deg to 90 deg with respect to the fiber direction, in both reflection and transmission modes. As shown in the experiments, CFRP composites are electrically conducting and therefore exhibit a high THz reflectivity. In addition, CFRP composites have polarization-dependent reflectivity and transmissivity for THz radiation. The reflected THz power in the case of parallel polarization is nearly 1.8 times higher than for perpendicular polarization. At the same time, in the transmission of THz wave, a CFRP acts as a Fabry-Pérot cavity resulting from multiple internal reflections from the CFRP-air interfaces. Moreover, from the measured data, we extract the refractive index and absorption coefficient of CFRP composites in the THz frequency range.

  11. Preparation and mechanical properties of carbon fiber reinforced hydroxyapatite/polylactide biocomposites.

    PubMed

    Shen, Lie; Yang, Hui; Ying, Jia; Qiao, Fei; Peng, Mao

    2009-11-01

    A novel biocomposite of carbon fiber (CF) reinforced hydroxyapatite (HA)/polylactide (PLA) was prepared by hot pressing a prepreg which consisting of PLA, HA and CF. The prepreg was manufactured by solvent impregnation process. Polymer resin PLA dissolved with chloroform was mixed with HA. After reinforcement CF bundle was impregnated in the mixture, the solvent was dried completely and subsequently hot-pressed uniaxially under a pressure of 40 MPa at 170 degrees C for 20 min. A study was carried out to investigate change in mechanical properties of CF/HA/PLA composites before and after degradation in vitro. The composites have excellent mechanical properties. A peak showed in flexural strength, flexural modulus and shear strength aspects, reaching up 430 MPa, 22 GPa, 212 MPa, respectively, as the HA content increased. Degraded in vitro for 3 months, the flexural strength and flexural modulus of the CF/HA/PLA fell 13.2% and 5.4%, respectively, while the shear strength of the CF/HA/PLA composites remains at the 190 MPa level. The SEM photos showed that there were gaps between the PLA matrix and CF after degradation. Water uptake increased to 5%, but the mass loss rate was only 1.6%. The pH values of the PBS dropped less than 0.1. That's because the alkaline of HA neutralize the acid degrades from PLA, which can prevent the body from the acidity harm.

  12. Recycling high-performance carbon fiber reinforced polymer composites using sub-critical and supercritical water

    NASA Astrophysics Data System (ADS)

    Knight, Chase C.

    Carbon fiber reinforced plastics (CFRP) are composite materials that consist of carbon fibers embedded in a polymer matrix, a combination that yields materials with properties exceeding the individual properties of each component. CFRP have several advantages over metals: they offer superior strength to weight ratios and superior resistance to corrosion and chemical attack. These advantages, along with continuing improvement in manufacturing processes, have resulted in rapid growth in the number of CFRP products and applications especially in the aerospace/aviation, wind energy, automotive, and sporting goods industries. Due to theses well-documented benefits and advancements in manufacturing capabilities, CFRP will continue to replace traditional materials of construction throughout several industries. However, some of the same properties that make CFRP outstanding materials also pose a major problem once these materials reach the end of service life. They become difficult to recycle. With composite consumption in North America growing by almost 5 times the rate of the US GDP in 2012, this lack of recyclability is a growing concern. As consumption increases, more waste will inevitably be generated. Current composite recycling technologies include mechanical recycling, thermal processing, and chemical processing. The major challenge of CFRP recycling is the ability to recover materials of high-value and preserve their properties. To this end, the most suitable technology is chemical processing, where the polymer matrix can be broken down and removed from the fiber, with limited damage to the fibers. This can be achieved using high concentration acids, but such a process is undesirable due to the toxicity of such materials. A viable alternative to acid is water in the sub-critical and supercritical region. Under these conditions, the behavior of this abundant and most environmentally friendly solvent resembles that of an organic compound, facilitating the breakdown

  13. Toughening of carbon fiber-reinforced epoxy polymer composites via copolymers and graphene nano-platelets

    NASA Astrophysics Data System (ADS)

    Downey, Markus A.

    Carbon fiber-reinforced epoxy composites currently play a significant role in many different industries. Due to their high cross-link density, aromatic epoxy polymers used as the matrix in composite materials are very strong and stiff however they lack toughness. This dissertation investigates three areas of the carbon fiber-reinforced composite, which have the potential to increase toughness: the carbon fiber surface; the fiber/matrix interphase; and the matrix material. Approaches to improving each area are presented which lead to enhancing the overall composite toughness without reducing other composite mechanical properties. The toughening of the base matrix material, DGEBA/mPDA, was accomplished by two methods: first, using low concentrations of aliphatic copolymers to enhance energy absorption and second by adding graphene nano-platelets (GnP) to act as crack deflection agents. 1wt% copolymer concentration was determined to substantially increase the notched Izod impact strength without reducing other static-mechanical properties. Toughening of DGEBA/mPDA using 3wt% GnP was found to be dependent on the aspect ratio of GnP and treatment of GnP with tetraethylenepentamine (TEPA). GnP C750 enhanced flexural properties but not fracture toughness because the small aspect ratio cannot effectively deflect cracks. TEPA-grafting enhanced GnP/matrix bonding. Larger aspect ratio GnP M5 and M25 showed significant increases in fracture toughness due to better crack deflection but also decreased flexural strength based on limited GnP/matrix bonding. TEPA-grafting mitigated some of the flexural strength reductions for GnP M5, due to enhanced GnP/matrix adhesion. In the high-fiber volume fraction composite, the fiber/matrix bonding was enhanced with UV-ozone surface treatment by reducing a weak fiber surface boundary layer and increasing the concentration of reactive oxygen groups on the fiber surface. Further increases in Mode I fracture toughness were seen with the

  14. The fabrication of artifacts out of glassy carbon and carbon-fiber-reinforced carbon for biomedical applications.

    PubMed

    Jenkins, G M; Grigson, C J

    1979-05-01

    Polymeric carbons are produced by the carbonization of a wide range of organic polymeric systems. We have concentrated on the fabrication of two types of polymeric carbons, glassy carbon and carbon-fiber-reinforced carbon (CFRC), both involving phenolic resin precursors. We describe herein the technology which enables us to make dental implants and heart valves out of glassy carbon. We also show how carbon-fiber-reinforced carbon can be made in the form of rods and plates for orthopedic use and molded before firing to produce complex, rigid, individually sculptured shapes suitable for maxillofacial bone replacement. The mechanical properties will be discussed in relation to the structure of these various forms of polymeric carbon. The main purpose of the work is to show that the technology of polymeric-carbon manufacture is essentially simple and the manufacturing process is readily carried out in laboratories which have already been equipped to fabricate standard dental prostheses.

  15. Laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) by single-mode fiber laser irradiation

    NASA Astrophysics Data System (ADS)

    Niino, Hiroyuki; Kawaguchi, Yoshizo; Sato, Tadatake; Narazaki, Aiko; Kurosaki, Ryozo; Muramatsu, Mayu; Harada, Yoshihisa; Anzai, Kenji; Aoyama, Mitsuaki; Matsushita, Masafumi; Furukawa, Koichi; Nishino, Michiteru; Fujisaki, Akira; Miyato, Taizo; Kayahara, Takashi

    2014-03-01

    We report on the laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) with a cw IR fiber laser (single-mode fiber laser, average power: 350 W). CFRTP is a high strength composite material with a lightweight, and is increasingly being used various applications. A well-defined cutting of CFRTP which were free of debris and thermal-damages around the grooves, were performed by the laser irradiation with a fast beam galvanometer scanning on a multiple-scanpass method.

  16. Modeling the Tensile Strength of Carbon Fiber - Reinforced Ceramic - Matrix Composites Under Multiple Fatigue Loading

    NASA Astrophysics Data System (ADS)

    Li, Longbiao

    2016-06-01

    An analytical method has been developed to investigate the effect of interface wear on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs) under multiple fatigue loading. The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure and the difference existed in the new and original interface debonded region. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The interface shear stress degradation model and fibers strength degradation model have been adopted to analyze the interface wear effect on the tensile strength of the composite subjected to multiple fatigue loading. Under tensile loading, the fibers failure probabilities were determined by combining the interface wear model and fibers failure model based on the assumption that the fiber strength is subjected to two - parameter Weibull distribution and the loads carried by broken and intact fibers satisfy the Global Load Sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength corresponding to multiple fatigue peak stress levels and different cycle number have been analyzed.

  17. Durability of carbon fiber reinforced shape memory polymer composites in space

    NASA Astrophysics Data System (ADS)

    Jang, Joon Hyeok; Hong, Seok Bin; Ahn, Yong San; Kim, Jin-Gyun; Nam, Yong-Youn; Lee, Geun Ho; Yu, Woong-Ryeol

    2016-04-01

    Shape memory polymer (SMP) is one of smart polymers which exhibit shape memory effect upon external stimuli. Recently, shape memory polymer composites (SMPCs) have been considered for space structure instead of shape memory alloys due to their deformability, lightweight and large recovery ratio, requiring characterization of their mechanical properties against harsh space environment and further prediction of the durability of SMPCs in space. As such, the durability of carbon fiber reinforced shape memory polymer composites (CF-SMPCs) was investigated using accelerated testing method based on short-term testing of CF-SMPCs in harsh condition. CF-SMPCs were prepared using woven carbon fabrics and a thermoset SMP via vacuum assisted resin transfer molding process. Bending tests with constant strain rate of CF-SMPCs were conducted using universal tensile machine (UTM) and Storage modulus test were conducted using dynamic mechanical thermal analysis (DMTA). Using the results, a master curve based on time-temperature superposition principle was then constructed, through which the mechanical properties of CF-SMPCs at harsh temperature were predicted. CF-SMPCs would be exposed to simulated space environments under ultra-violet radiations at various temperatures. The mechanical properties including flexural and tensile strength and shape memory properties of SMPCs would be measured using UTM before and after such exposures for comparison. Finally, the durability of SMPCs in space would be assessed by developing a degradation model of SMPC.

  18. Heat accumulation effects in short-pulse multi-pass cutting of carbon fiber reinforced plastics

    NASA Astrophysics Data System (ADS)

    Kononenko, T. V.; Freitag, C.; Komlenok, M. S.; Onuseit, V.; Weber, R.; Graf, T.; Konov, V. I.

    2015-09-01

    The formation of a matrix evaporation zone (MEZ) in carbon fiber reinforced plastics during multi-pass laser cutting with picosecond laser pulses is studied for a wide range of pulse frequencies (fp = 10-800 kHz) and feed rates (vf = 0.002-10 m/s). Three regimes of the formation of the MEZ are found and related with different heat accumulation effects: (i) small MEZ (<2 μm) with negligible heat accumulation, (ii) moderate-size MEZ (up to a few hundred microns) determined by heat accumulation between pulses, and (iii) large MEZ (up to a few millimeters) caused by heat accumulation between scans. The dependence of the size of the MEZ on the number of scans and the scan frequency was studied to distinguish the two heat accumulation effects (between pulses and between scans), which occur on different time-scales. A diagram to illustrate the boundaries between the three regimes of the formation of the MEZ as a function of feed rate and pulse frequency is proposed as a promising base for further studies and as a useful tool to optimize the processing parameters in practice.

  19. Carbon-Fiber Reinforced Plastic Passive Composite Damper by Use of Piezoelectric Polymer/Ceramic

    NASA Astrophysics Data System (ADS)

    Tanimoto, Toshio

    2002-11-01

    In this study, the passive damping of carbon-fiber reinforced plastic (CFRP) cantilever beams is examined using (1) interleaving of viscoelastic thermoplastic films, (2) piezoelectric polymer (PVDF) film interlayers and (3) surface-bonded piezoelectric ceramics. Introducing polyethylene-based film interlayers between composite plies resulted in a significant increase in the vibration loss factor. It is also shown that the vibration damping of CFRP laminates can be improved passively by means of PVDF film interlayers and resistively shunted, surface-bonded piezoelectric ceramic, PbZrO3-PbTiO3 (PZT) sheets. This paper also discusses the enhanced vibration damping of CFRP laminates with dispersed PZT particle interlayers. All these damping methods, interleaving of thermoplastic films, interlayers of PVDF films or dispersed PZT particles between composite plies, and resistively shunted, surface-bonded PZT sheets, can be jointly used to improve the damping of CFRP laminates/structures. The use of CFRP beams in combination with several damping concepts discussed here is promising for application in structures where light weight and improved vibration damping are desired.

  20. Inflammatory response against different carbon fiber-reinforced PEEK wear particles compared with UHMWPE in vivo.

    PubMed

    Utzschneider, Sandra; Becker, Fabian; Grupp, Thomas M; Sievers, Birte; Paulus, Alexander; Gottschalk, Oliver; Jansson, Volkmar

    2010-11-01

    Poly(ether ether ketone) (PEEK) and its composites are recognized as alternative bearing materials for use in arthroplasty because of their mechanical properties. The objective of this project was to evaluate the biological response of two different kinds of carbon fiber-reinforced (CFR) PEEK compared with ultra-high molecular weight polyethylene (UHMWPE) in vivo as a standard bearing material. Wear particles of the particulate biomaterials were injected into the left knee joint of female BALB/c mice. Assessment of the synovial microcirculation using intravital fluorescence microscopy as well as histological evaluation of the synovial layer were performed 7 days after particle injection. Enhanced leukocyte-endothelial cell interactions and an increase in functional capillary density as well as histological investigations revealed that all tested biomaterials caused significantly (P < 0.05) increased inflammatory reactions compared with control animals (injected with sterile phosphate-buffered saline), without any difference between the tested biomaterials (P > 0.05). These data suggest that wear debris of CFR-PEEK is comparable with UHMWPE in its biological activity. Therefore, CFR-PEEK represents an alternative bearing material because of its superior mechanical and chemical behavior without any increased biological activity of the wear particles, compared with a standard bearing material.

  1. Numerical simulation of combustion effects during laser processing of carbon fiber reinforced plastics

    NASA Astrophysics Data System (ADS)

    Ohkubo, Tomomasa; Tsukamoto, Masahiro; Sato, Yuji

    2016-03-01

    We applied the finite difference method to a numerical simulation of material removal in the laser ablation of a carbon fiber reinforced plastic (CFRP). Although a few theoretical and numerical studies of heat-affected zone (HAZ) formation have been reported, there has been no report describing heat generation due to oxidization of the materials. It is important to consider combustion effects when discussing the generation of a HAZ in order to improve the quality of CFRP cutting by laser. To develop a new calculation model that includes the effects of the combustion of each element of the CFRP, thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were performed for CFRP in air. We succeeded in qualitatively simulating the generation of a HAZ, including the effects of combustion, using data obtained by TGA and DTA. Therefore, not only thermal conductivity, but also combustion effects, should be considered when discussing how a HAZ is generated and in order to improve the cutting quality of CFRPs in laser processing.

  2. The Use of Carbon-Fiber-Reinforced (CFR) PEEK Material in Orthopedic Implants: A Systematic Review

    PubMed Central

    Li, Chuan Silvia; Vannabouathong, Christopher; Sprague, Sheila; Bhandari, Mohit

    2015-01-01

    Carbon-fiber-reinforced polyetheretherketone (CFR-PEEK) has been successfully used in orthopedic implants. The aim of this systematic review is to investigate the properties, technical data, and safety of CFR-PEEK biomaterial and to evaluate its potential for new innovation in the design of articulating medical devices. A comprehensive search in PubMed and EMBASE was conducted to identify articles relevant to the outcomes of CFR-PEEK orthopedic implants. The search was also expanded by reviewing the reference sections of selected papers and references and benchmark reports provided by content experts. A total of 23 articles were included in this review. There is limited literature available assessing the performance of CFR-PEEK, specifically as an implant material for arthroplasty systems. Nevertheless, available studies strongly support CFR-PEEK as a promising and suitable material for orthopedic implants because of its biocompatibility, material characteristics, and mechanical durability. Future studies should continue to investigate CFR-PEEK’s potential benefits. PMID:25780341

  3. Short carbon fiber reinforced ceramic - Cesic - for optical-mechanical applications

    NASA Astrophysics Data System (ADS)

    Kroedel, Matthias; Kutter, G. S.; Deyerler, M.; Pailer, Norbert M.

    2003-02-01

    Ceramic mirrors and complex structures are becoming more important for high-precision lightweighted optomechanical applications. Carbon-fiber reinforced silicon carbon (C/SiC) is a composite ceramic material consisting of SiC as its major constituent. Developments over the past 10 years by IABM, ECM, and Astrium GhbH have demonstrated the feasibility and versitility of this ceramic material for different applications. Furthermore, Cesic-a trademark of ECM for C/SiC- allows relatively quick and cheap manufacturing of components because the components can be shaped with conventional tools in a milling and/or drilling process of the greenbody material. Through a joining process and our new development of optical surfaces based on a slurry cladding technology, Cesic allows for a direct up-scaling of structures and optical surfaces to large size applications and systems. The size of the structures and mirrors that can be manufactured is limited only by the scale of the available production facilities, the largest of which currently is 2.4 m in diameter.

  4. Microstructure and Mechanical Properties of Warm-Sprayed Titanium Coating on Carbon Fiber-Reinforced Plastic

    NASA Astrophysics Data System (ADS)

    Ganesan, Amirthan; Takuma, Okada; Yamada, Motohiro; Fukumoto, Masahiro

    2016-04-01

    Polymer materials are increasingly dominating various engineering fields. Recently, polymer-based composite materials' surface performances—in particular, surface in relative motion—have been improved markedly by thermal spray coating. Despite this recent progress, the deposition of high-strength materials—producing a coating thickness of the order of more than 500 μm—remains highly challenging. In the present work, a highly dense and thick titanium coating was successfully deposited onto the carbon fiber-reinforced plastic (CFRP) substrate using a newly developed high-pressure warm spray (WS) system. The coating properties, such as hardness (300 ± 20 HV) and adhesion strength (8.1 ± 0.5 MPa), were evaluated and correlated with the microstructures of the coating. In addition, a wipe-test and in situ particle velocity and temperature measurement were performed to validate the particle deposition behavior as a function of the nitrogen flow rate in the WS system. It was found that the microstructures, deposition efficiency, and mechanical properties of the coatings were highly sensitive to nitrogen flow rates. The coating porosity increased with increasing nitrogen flow rates; however, the highest density was observed for nitrogen flow rate of 1000 standard liters per minute (SLM) samples due to the high fraction of semi-molten particles in the spray stream.

  5. Assessment of carbon fiber-reinforced polyphenylene sulfide by means of laser ultrasound

    NASA Astrophysics Data System (ADS)

    Kalms, Michael; Peters, Christian; Wierbos, Ronald

    2011-04-01

    From automobile industry to aerospace, thermoformed composites are more and more in use. Thermoplastics offer a number of attractive applications in commercial use like short production times, tailored solutions, recyclability and lower cost. The thermoforming process allows for producing carbon fiber-reinforced parts in a wide range of different geometric shapes. On the other hand this benefit requires a demanding nondestructive testing procedure especially for security relevant parts. A contactless method which is able to fulfil this requirement is the extension of the ultrasound technique with laser technology. It opens up new opportunities for quality assessment during manufacturing like inspection of complex surfaces including small radii, remote observation and nondestructive testing of hot items directly after the thermal forming process. We describe the successful application of laser-based ultrasound on small complex thermoformed composite parts (Cetex® PPS). Cetex consists of semicrystalline polyphenylene sulfide thermoplastics providing outstanding toughness and excellent chemical and solvent resistance. It is qualified in aircraft industry for multiple structural applications. For instance, Cetex is used in the Airbus A380 engine air intakes and the wing fixed leading edge (J-Nose). We investigated several test samples with intentionally introduced defects. The smallest flaw size detected was 2 mm in diameter for delaminations and 6 mm in diameter for porosity.

  6. Delamination behavior of carbon fiber/epoxy composite laminates with short fiber reinforcement

    SciTech Connect

    Sohn, M.S.; Hu, X.Z. . Dept. of Mechanical and Materials Engineering)

    1994-06-01

    Delamination in laminated materials is one major mode of damage and failure encountered in application. Fracture mechanics is often used to characterize the interlaminar fracture behavior. The interlaminar fracture energies, G[sub I], G[sub II] and G[sub I/II] are the major concerns to characterize the interlaminar toughness of the composite laminates. Typical mode-I fracture is caused by normal tension, and typical mode-II fracture by shear in the direction of crack extension. The objective of the present study is to compare and discuss the mode-I and mode-II interlaminar fracture energies, G[sub I] and G[sub II] of carbon fiber/epoxy composite laminates with and without the reinforcement of short Kevlar fibers (5--7 mm in length) and to identify the microfracture features of the Kevlar fibers under those two delamination modes through SEM observations. Double cantilever beam (DCB) specimens and end notched flexure (ENF) specimens are used for the mode-I and -II delamination experiments.

  7. Interactive Exploration and Visualization using MetaTracts extracted from Carbon Fiber Reinforced Composites.

    PubMed

    Bhattacharya, Arindam; Weissenbock, Johannes; Wenger, Rephael; Amirkhanov, Artem; Kastner, Johann; Heinzl, Christoph

    2016-06-16

    This work introduces a tool for interactive exploration and visualization using MetaTracts. MetaTracts is a novel method for extraction and visualization of individual fiber bundles and weaving patterns from X-ray computed tomography (XCT) scans of endless carbon fiber reinforced polymers (CFRPs). It is designed specifically to handle XCT scans of low resolutions where the individual fibers are barely visible, which makes extraction of fiber bundles a challenging problem. The proposed workflow is used to analyze unit cells of CFRP materials integrating a recurring weaving pattern. First, a coarse version of integral curves is used to trace subsections of the individual fiber bundles in the woven CFRP materials. We call these sections MetaTracts. In the second step, these extracted fiber bundle sections are clustered using a two-step approach: first by orientation, then by proximity. The tool can generate volumetric representations as well as surface models of the extracted fiber bundles to be exported for further analysis. In addition a custom interactive tool for exploration and visual analysis of MetaTracts is designed. We evaluate the proposed workflow on a number of real world datasets and demonstrate that MetaTracts effectively and robustly identifies and extracts fiber bundles.

  8. Failure of a carbon fiber-reinforced polymer implant used for transforaminal lumbar interbody fusion.

    PubMed

    Sardar, Zeeshan; Jarzem, Peter

    2013-12-01

    Lumbar interbody fusion is a common procedure owing to the high prevalence of degenerative spinal disorders. During such procedures, carbon fiber-reinforced polymer (CFRP) cages are frequently utilized to fill the void created between adjacent vertebral bodies, to provide mechanical stability, and to carry graft material. Failure of such implants can lead to significant morbidity. We discuss the possible causes leading to the failure of a CFRP cage in a patient with rheumatoid arthritis. Review of a 49-year-old woman who underwent revision anterior lumbar interbody fusion 2 years after posterior instrumentation and transforaminal lumbar interbody fusion at L4-L5 and L5-S1. The patient developed pseudarthrosis at the two previously fused levels with failure of the posterior instrumentation. Revision surgery reveled failure with fragmentation of the CFRP cage at the L5-S1 level. CFRP implants can break if mechanical instability or nonunion occurs in the spinal segments, thus emphasizing the need for optimizing medical management and meticulous surgical technique in achieving stability.

  9. Flexural Properties of E Glass and TR50S Carbon Fiber Reinforced Epoxy Hybrid Composites

    NASA Astrophysics Data System (ADS)

    Dong, Chensong; Sudarisman; Davies, Ian J.

    2013-01-01

    A study on the flexural properties of E glass and TR50S carbon fiber reinforced hybrid composites is presented in this paper. Specimens were made by the hand lay-up process in an intra-ply configuration with varying degrees of glass fibers added to the surface of a carbon laminate. These specimens were then tested in the three-point bend configuration in accordance with ASTM D790-07 at three span-to-depth ratios: 16, 32, and 64. The failure modes were examined under an optical microscope. The flexural behavior was also simulated by finite element analysis, and the flexural modulus, flexural strength, and strain to failure were calculated. It is shown that although span-to-depth ratio shows an influence on the stress-strain relationship, it has no effect on the failure mode. The majority of specimens failed by either in-plane or out-of-plane local buckling followed by kinking and splitting at the compressive GFRP side and matrix cracking combined with fiber breakage at the CFRP tensile face. It is shown that positive hybrid effects exist for the flexural strengths of most of the hybrid configurations. The hybrid effect is noted to be more obvious when the hybrid ratio is small, which may be attributed to the relative position of the GFRP layer(s) with respect to the neutral plane. In contrast to this, flexural modulus seems to obey the rule of mixtures equation.

  10. Durability-Based Design Criteria for a Quasi-Isotropic Carbon-Fiber-Reinforced Thermoplastic Automotive Composite

    SciTech Connect

    Naus, Dan J; Corum, James; Klett, Lynn B; Davenport, Mike; Battiste, Rick; Simpson, Jr., William A

    2006-04-01

    This report provides recommended durability-based design properties and criteria for a quais-isotropic carbon-fiber thermoplastic composite for possible automotive structural applications. The composite consisted of a PolyPhenylene Sulfide (PPS) thermoplastic matrix (Fortron's PPS - Ticona 0214B1 powder) reinforced with 16 plies of carbon-fiber unidirectional tape, [0?/90?/+45?/-45?]2S. The carbon fiber was Hexcel AS-4C and was present in a fiber volume of 53% (60%, by weight). The overall goal of the project, which is sponsored by the U.S. Department of Energy's Office of Freedom Car and Vehicle Technologies and is closely coordinated with the Advanced Composites Consortium, is to develop durability-driven design data and criteria to assure the long-term integrity of carbon-fiber-based composite systems for automotive structural applications. This document is in two parts. Part 1 provides design data and correlations, while Part 2 provides the underlying experimental data and models. The durability issues addressed include the effects of short-time, cyclic, and sustained loadings; temperature; fluid environments; and low-energy impacts (e.g., tool drops and kickups of roadway debris) on deformation, strength, and stiffness. Guidance for design analysis, time-independent and time-dependent allowable stresses, rules for cyclic loadings, and damage-tolerance design guidance are provided.

  11. Cutting and drilling of carbon fiber reinforced plastics (CFRP) by 70W short pulse nanosecond laser

    NASA Astrophysics Data System (ADS)

    Jaeschke, Peter; Stolberg, Klaus; Bastick, Stefan; Ziolkowski, Ewa; Roehner, Markus; Suttmann, Oliver; Overmeyer, Ludger

    2014-02-01

    Continuous carbon fibre reinforced plastics (CFRP) are recognized as having a significant lightweight construction potential for a wide variety of industrial applications. However, a today`s barrier for a comprehensive dissemination of CFRP structures is the lack of economic, quick and reliable manufacture processes, e.g. the cutting and drilling steps. In this paper, the capability of using pulsed disk lasers in CFRP machining is discussed. In CFRP processing with NIR lasers, carbon fibers show excellent optical absorption and heat dissipation, contrary to the plastics matrix. Therefore heat dissipation away from the laser focus into the material is driven by heat conduction of the fibres. The matrix is heated indirectly by heat transfer from the fibres. To cut CFRP, it is required to reach the melting temperature for thermoplastic matrix materials or the disintegration temperature for thermoset systems as well as the sublimation temperature of the reinforcing fibers simultaneously. One solution for this problem is to use short pulse nanosecond lasers. We have investigated CFRP cutting and drilling with such a laser (max. 7 mJ @ 10 kHz, 30 ns). This laser offers the opportunity of wide range parameter tuning for systematic process optimization. By applying drilling and cutting operations based on galvanometer scanning techniques in multi-cycle mode, excellent surface and edge characteristics in terms of delamination-free and intact fiber-matrix interface were achieved. The results indicate that nanosecond disk laser machining could consequently be a suitable tool for the automotive and aircraft industry for cutting and drilling steps.

  12. Effect of TiO2 deposition on the mechanical properties of a carbon-fiber-reinforced bismaleimide composite

    NASA Astrophysics Data System (ADS)

    Di, Jang; Chunhua, Cao; Jie, Wu

    2013-07-01

    In order to improve the mechanical properties of carbon-fiber-reinforced bismaleimide (CF/BMI) composites, TiO2 was deposited on the carbon fibers. The short-beam shear and mechanical properties of the composites were investigated. Both raw and TiO2-coated CFs were utilized for their fabrication. The tensile strength of the composites, both with raw and TiO2-coated fibers, grew with increasing filler content. The tensile strength of the CF/BMI composites with treated fibers, at all mixing ratios, was found to be by 18% higher than that of the composites with untreated ones. The surface morphologies of fracture surfaces of the composites were recorded using the scanning electron microscopy (SEM) to gain information about the interfacial fiber-matrix adhesion in the composites.

  13. Exposure Assessment of a High-energy Tensile Test With Large Carbon Fiber Reinforced Polymer Cables.

    PubMed

    Schlagenhauf, Lukas; Kuo, Yu-Ying; Michel, Silvain; Terrasi, Giovanni; Wang, Jing

    2015-01-01

    This study investigated the particle and fiber release from two carbon fiber reinforced polymer cables that underwent high-energy tensile tests until rupture. The failing event was the source of a large amount of dust whereof a part was suspected to be containing possibly respirable fibers that could cause adverse health effects. The released fibers were suspected to migrate through small openings to the experiment control room and also to an adjacent machine hall where workers were active. To investigate the fiber release and exposure risk of the affected workers, the generated particles were measured with aerosol devices to obtain the particle size and particle concentrations. Furthermore, particles were collected on filter samples to investigate the particle shape and the fiber concentration. Three situations were monitored for the control room and the machine hall: the background concentrations, the impact of the cable failure, and the venting of the exposed rooms afterward. The results showed four important findings: The cable failure caused the release of respirable fibers with diameters below 3 μm and an average length of 13.9 μm; the released particles did migrate to the control room and to the machine hall; the measured peak fiber concentration of 0.76 fibers/cm(3) and the overall fiber concentration of 0.07 fibers/cm(3) in the control room were below the Permissible Exposure Limit (PEL) for fibers without indication of carcinogenicity; and the venting of the rooms was fast and effective. Even though respirable fibers were released, the low fiber concentration and effective venting indicated that the suspected health risks from the experiment on the affected workers was low. However, the effect of long-term exposure is not known therefore additional control measures are recommended.

  14. Improvement of fatigue life and prevention of internal crack initiation of chopped carbon fiber reinforced plastics modified with micro glass fibers

    NASA Astrophysics Data System (ADS)

    Fujitani, Ryohei; Okubo, Kazuya; Fujii, Toru

    2016-04-01

    The purpose of this study is to improve fatigue properties of chopped carbon fiber reinforced plastics fabricated by SMC (Sheet Molding Compound) method and to clarify the mechanism for improvement. To enhance the properties, micro glass fibers with 500nm in diameter were added directly into vinyl ester resin with 0.3wt% contents. The chopped carbon fiber reinforced plastics were fabricated and cured at room temperature for 1hour under 1MPa and then at 60degree-C for 3hours. After curing, the fabricated plate was cut into the dimension of specimen. Tensile and bending strength and fatigue life of chopped carbon fiber reinforced plastics were investigated by tensile and three point bending test and cyclic tension-tension test, respectively. The behavior of strain concentration around the tips of carbon fiber were discussed with model specimen on the observations with DIC (Digital Image Correlation) method and polarizing microscope under tensile loading, in which one chopped carbon fiber was embedded into the matrix. In conclusion, when toughened vinyl ester resin modified with micro glass fibers was used as matrix, tensile and bending strength and fatigue life of chopped carbon fiber reinforced plastics were increased 56.6%, 49.8% and 14 to 23 times compared with those of unmodified specimens. It should be explained that static and dynamic properties of chopped carbon fiber reinforced plastics were improved by that crack initiation and propagation were prevented according to the prevention of the locally increasing of strain around the tip of carbon fiber, when vinyl ester resin modified with micro glass fibers was used as matrix.

  15. Corrosion detection of steel reinforced concrete using combined carbon fiber and fiber Bragg grating active thermal probe

    NASA Astrophysics Data System (ADS)

    Li, Weijie; Ho, Siu Chun Michael; Song, Gangbing

    2016-04-01

    Steel reinforcement corrosion is one of the dominant causes for structural deterioration for reinforced concrete structures. This paper presents a novel corrosion detection technique using an active thermal probe. The technique takes advantage of the fact that corrosion products have poor thermal conductivity, which will impede heat propagation generated from the active thermal probe. At the same time, the active thermal probe records the temperature response. The presence of corrosion products can thus be detected by analyzing the temperature response after the injection of heat at the reinforcement-concrete interface. The feasibility of the proposed technique was firstly analyzed through analytical modeling and finite element simulation. The active thermal probe consisted of carbon fiber strands to generate heat and a fiber optic Bragg grating (FBG) temperature sensor. Carbon fiber strands are used due to their corrosion resistance. Wet-dry cycle accelerated corrosion experiments were performed to study the effect of corrosion products on the temperature response of the reinforced concrete sample. Results suggest a high correlation between corrosion severity and magnitude of the temperature response. The technique has the merits of high accuracy, high efficiency in measurement and excellent embeddability.

  16. Laser drilling of carbon fiber reinforced plastics (CFRP) by picosecond laser pulses: comparative study of different drilling tools

    NASA Astrophysics Data System (ADS)

    Herrmann, T.; Stolze, M.; L'huillier, J.

    2014-03-01

    Carbon fiber reinforced plastic (CFRP) as a lightweight material with superior properties is increasingly being used in industrial manufacturing. Using ultrashort laser pulses can improve the quality in cutting or drilling applications, but at high power levels it is more complicated to maintain the accuracy and precision in CFRP drilling. According to the application requirements for the extent of the heat affected zone, the geometric precision and the productivity different drilling tools can be used. Therefore we report on the application of three different beam delivery systems to drilling processes of CFRP: Galvanometer scanner, trepanning head and diffractive optical elements.

  17. Fabrication and static characterization of carbon-fiber-reinforced polymers with embedded NiTi shape memory wire actuators

    NASA Astrophysics Data System (ADS)

    de Araújo, C. J.; Rodrigues, L. F. A.; Coutinho Neto, J. F.; Reis, R. P. B.

    2008-12-01

    In this work, unidirectional carbon-fiber-reinforced polymers (CFRP) with embedded NiTi shape memory alloy (SMA) wire actuators were manufactured using a universal testing machine equipped with a thermally controlled chamber. Beam specimens containing cold-worked, annealed and trained NiTi SMA wires distributed along their neutral plane were fabricated. Several tests in a three-point bending mode at different constant temperatures were performed. To verify thermal buckling effects, electrical activation of the specimens was realized in a cantilevered beam mode and the influence of the SMA wire actuators on the tip deflection of the composite is demonstrated.

  18. Mechanical analysis of three dimensional woven carbon fiber-reinforced composites using fiber-based continuum model

    NASA Astrophysics Data System (ADS)

    Ahn, Hyunchul; An, Yongsan; Yu, Woong-Ryeol

    2016-10-01

    A new numerical method for analyzing the mechanical behavior of three-dimensional (3D) woven carbon fiber-reinforced composites was developed by considering changes in the fiber orientation and calculating the stress increments due to incremental deformations. The model consisted of four steps, starting update of the yarn orientation based on incremental deformation gradient. The stiffness matrix was then computed using the updated yarn orientation. Next, partial damage and propagation were incorporated into the stress calculation using modified ply discount method. The failure conditions were obtained by testing the unidirectional composites and formulated using Puck's criterion. This numerical model was finally implemented into commercial finite element software, ABAQUS, as a user material subroutine. As for experiment, 3D woven composite samples was manufactured using laboratory built-in system and characterized, the results of which were compared with simulated results, demonstrating that the current numerical model can properly predict the mechanical behavior of 3D fiber-reinforced composites.

  19. Radiation damage and thermal shock response of carbon-fiber-reinforced materials to intense high-energy proton beams

    NASA Astrophysics Data System (ADS)

    Simos, N.; Zhong, Z.; Ghose, S.; Kirk, H. G.; Trung, L.-P.; McDonald, K. T.; Kotsina, Z.; Nocera, P.; Assmann, R.; Redaelli, S.; Bertarelli, A.; Quaranta, E.; Rossi, A.; Zwaska, R.; Ammigan, K.; Hurh, P.; Mokhov, N.

    2016-11-01

    A comprehensive study on the effects of energetic protons on carbon-fiber composites and compounds under consideration for use as low-Z pion production targets in future high-power accelerators and low-impedance collimating elements for intercepting TeV-level protons at the Large Hadron Collider has been undertaken addressing two key areas, namely, thermal shock absorption and resistance to irradiation damage. Carbon-fiber composites of various fiber weaves have been widely used in aerospace industries due to their unique combination of high temperature stability, low density, and high strength. The performance of carbon-carbon composites and compounds under intense proton beams and long-term irradiation have been studied in a series of experiments and compared with the performance of graphite. The 24-GeV proton beam experiments confirmed the inherent ability of a 3D C/C fiber composite to withstand a thermal shock. A series of irradiation damage campaigns explored the response of different C/C structures as a function of the proton fluence and irradiating environment. Radiolytic oxidation resulting from the interaction of oxygen molecules, the result of beam-induced radiolysis encountered during some of the irradiation campaigns, with carbon atoms during irradiation with the presence of a water coolant emerged as a dominant contributor to the observed structural integrity loss at proton fluences ≥5 ×1020 p /cm2 . The carbon-fiber composites were shown to exhibit significant anisotropy in their dimensional stability driven by the fiber weave and the microstructural behavior of the fiber and carbon matrix accompanied by the presence of manufacturing porosity and defects. Carbon-fiber-reinforced molybdenum-graphite compounds (MoGRCF) selected for their impedance properties in the Large Hadron Collider beam collimation exhibited significant decrease in postirradiation load-displacement behavior even after low dose levels (˜5 ×1018 p cm-2 ). In addition, the

  20. X-ray photoelectron spectroscopic studies of graphitic materials and interfacial interactions in carbon-fiber-reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Viswanathan, Hema L.

    This dissertation involves the X-ray photoelectron spectroscopic (XPS) study of the chemistry associated with carbon fiber-reinforced composites fabricated using PAN-based carbon fibers and a thermoplastic polyimide resin. The mechanical properties of the ultimate composite are significantly affected by the nature of the fiber/matrix interface. Interfacial interaction can be promoted by the electrochemical modification of the fiber surface. The determination of carbon fiber microstructure was conducted through angle-resolved valence band photoemission studies of highly ordered graphite. The change in orientation of the basal planes and reactive edge sites with take-off angle provided a method for the determination of surface microstructure. The electronic structure of solid-state graphite was described using a band structure model and the results obtained were compared with the multiple scattered wave X a calculations. PAN-based fibers were electrochemically oxidized and studied using monochromatic X-radiation. The extremely narrow natural linewidth of the monochromatized Al K a radiation allowed previously unresolved features to be seen. In addition, sample decomposition due to radiative heat from the X-ray source is eliminated. Fibers that were pretreated by the manufacturer were subjected to further electrochemical oxidation. The fibers behaved in an erratic and non-reproducible manner. The surface treatment was removed by heating the fibers in vacuum, followed by XPS analysis and electrochemical oxidation. The fiber/matrix interface was simulated by coating a very thin layer of the polyimide resin on the surface of the fiber followed by XPS analysis. The validity of a proposed structure for the resin was confirmed by comparison with ab initio calculations conducted on the resin repeat unit. A high level of fiber/matrix interaction was observed for electrochemically oxidized fibers. The possibility of solvent interaction with the fiber surface was eliminated by

  1. Fabrication and characterization of a novel carbon fiber-reinforced calcium phosphate silicate bone cement with potential osteo-inductivity.

    PubMed

    Zheng, Jiangjiang; Xiao, Yu; Gong, Tianxing; Zhou, Shuxin; Troczynski, Tom; Yang, Quanzu; Bao, Chongyun; Xu, Xiaoming

    2015-12-23

    The repair of bone defects is still a pressing challenge in clinics. Injectable bone cement is regarded as a promising material to solve this problem because of its special self-setting property. Unfortunately, its poor mechanical conformability, unfavorable osteo-genesis ability and insufficient osteo-inductivity seriously limit its clinical application. In this study, novel experimental calcium phosphate silicate bone cement reinforced by carbon fibers (CCPSC) was fabricated and characterized. First, a compressive strength test and cell culture study were carried out. Then, the material was implanted into the femoral epiphysis of beagle dogs to further assess its osteo-conductivity using a micro-computed tomography scan and histological analysis. In addition, we implanted CCPSC into the beagles' intramuscular pouches to perform an elementary investigation of its osteo-inductivity. The results showed that incorporation of carbon fibers significantly improved its mechanical properties. Meanwhile, CCPSC had better biocompatibility to activate cell adhesion as well as proliferation than poly-methyl methacrylate bone cement based on the cell culture study. Moreover, pronounced biodegradability and improved osteo-conductivity of CCPSC could be observed through the in vivo animal study. Finally, a small amount of osteoid was found at the heterotopic site one month after implantation which indicated potential osteo-inductivity of CCPSC. In conclusion, the novel CCPSC shows promise as a bioactive bone substitute in certain load-bearing circumstances.

  2. Computational modeling of the electromagnetic characteristics of carbon fiber-reinforced polymer composites with different weave structures

    NASA Astrophysics Data System (ADS)

    Hassan, A. M.; Douglas, J. F.; Garboczi, E. J.

    2014-02-01

    Carbon fiber reinforced polymer composites (CFRPC) are of great interest in the aerospace and automotive industries due to their exceptional mechanical properties. Carbon fibers are typically woven and inter-laced perpendicularly in warps and wefts to form a carbon fabric that can be embedded in a binding matrix. The warps and wefts can be interlaced in different patterns called weaving structures. The primary weaving structures are the plain, twill, and satin weaves, which give different mechanical composite properties. The goal of this work is to computationally investigate the dependence of CFRPC microwave and terahertz electromagnetic characteristics on weave structure. These bands are good candidates for the Nondestructive Evaluation (NDE) of CFRPC since their wavelengths are comparable to the main weave features. 3D full wave electromagnetic simulations of several different weave models have been performed using a finite element (FEM) simulator, which is able to accurately model the complex weave structure. The computational experiments demonstrate that the reflection of electromagnetic waves from CFRPC depend sensitively on weave structure. The reflection spectra calculated in this work can be used to identify the optimal frequencies for the NDE of each weave structure.

  3. Determining the material parameters for the reconstruction of defects in carbon fiber reinforced polymers from data measured by flash thermography

    NASA Astrophysics Data System (ADS)

    Müller, Jan P.; Götschel, Sebastian; Maierhofer, Christiane; Weiser, Martin

    2017-02-01

    Flash thermography is a fast and reliable non-destructive testing method for the investigation of defects in carbon fiber reinforced polymer (CFRP) materials. In this paper numerical simulations of transient thermography data are presented, calculated for a quasi-isotropic flat bottom hole sample. They are compared to experimental data. These simulations are one important step towards the quantitative reconstruction of a flaw by assessing thermographic data. The applied numerical model is based on the finite-element method, extended by a semi-analytical treatment of the boundary of the sample, which is heated by the flash light. A crucial part for a reliable numerical model is the prior determination of the material parameters of the specimen as well as of the experimental parameters of the set-up. The material parameters in plane and in depth diffusivity are measured using laser line excitation. In addition, the absorption and heat transfer process of the first layers is investigated using an IR microscopic lens. The performance of the two distinct components of CFRP during heating - epoxy resin and carbon fibers - is examined. Finally, the material parameters are optimized by variation and comparison of the simulation results to the experimental data. The optimized parameters are compared to the measured ones and further methods to ensure precise material parameter measurements are discussed.

  4. Carbon fiber-reinforced cyanate ester/nano-ZrW2O8 composites with tailored thermal expansion.

    PubMed

    Badrinarayanan, Prashanth; Rogalski, Mark K; Kessler, Michael R

    2012-02-01

    Fiber-reinforced composites are widely used in the design and fabrication of a variety of high performance aerospace components. The mismatch in coefficient of thermal expansion (CTE) between the high CTE polymer matrix and low CTE fiber reinforcements in such composite systems can lead to dimensional instability and deterioration of material lifetimes due to development of residual thermal stresses. The magnitude of thermally induced residual stresses in fiber-reinforced composite systems can be minimized by replacement of conventional polymer matrices with a low CTE, polymer nanocomposite matrix. Zirconium tungstate (ZrW(2)O(8)) is a unique ceramic material that exhibits isotropic negative thermal expansion and has excellent potential as a filler for development of low CTE polymer nanocomposites. In this paper, we report the fabrication and thermal characterization of novel, multiscale, macro-nano hybrid composite laminates comprising bisphenol E cyanate ester (BECy)/ZrW(2)O(8) nanocomposite matrices reinforced with unidirectional carbon fibers. The results reveal that incorporation of nanoparticles facilitates a reduction in CTE of the composite systems, which in turn results in a reduction in panel warpage and curvature after the cure because of mitigation of thermally induced residual stresses.

  5. Analysis of surface damage in retrieved carbon fiber-reinforced and plain polyethylene tibial components from posterior stabilized total knee replacements.

    PubMed

    Wright, T M; Rimnac, C M; Faris, P M; Bansal, M

    1988-10-01

    The performance of carbon fiber-reinforced ultra-high molecular weight polyethylene was compared with that of plain (non-reinforced) polyethylene on the basis of the damage that was observed on the articulating surfaces of retrieved tibial components of total knee prostheses. Established microscopy techniques for subjectively grading the presence and extent of surface damage and the histological structure of the surrounding tissues were used to evaluate twenty-six carbon fiber-reinforced and twenty plain polyethylene components that had been retrieved after an average of twenty-one months of implantation. All of the tibial components were from the same design of total knee replacement. The two groups of patients from whom the components were retrieved did not differ with regard to weight, the length of time that the component had been implanted, the radiographic position and angular alignment of the component, the original diagnosis, or the reason for removal of the component. The amounts and types of damage that were observed did not differ for the two materials. For both materials, the amount of damage was directly related to the length of time that the component had been implanted. The histological appearance of tissues from the area around the component did not differ for the two materials, except for the presence of fragments of carbon fiber in many of the samples from the areas around carbon fiber-reinforced components.

  6. The influence of porosity on ultrasound attenuation in carbon fiber reinforced plastic composites using the laser-ultrasound spectroscopy

    NASA Astrophysics Data System (ADS)

    Karabutov, A. A.; Podymova, N. B.; Belyaev, I. O.

    2013-11-01

    Wideband acoustic spectroscopy with a laser ultrasound source for quantitative analysis of the effect of porosity on the attenuation coefficient of longitudinal acoustic waves in carbon fiber reinforced plastic (CFRP) composite materials was experimentally implemented. The samples under study had different bulk-porosity levels (up to 10%), which were determined using X-ray computer tomography. A resonance ultrasound attenuation peak associated with the one-dimensional periodicity of the layered composite structure was observed for all samples. The absolute value of the resonance-peak maximum and its width depend on the local concentration of microscopic isolated pores and extended delaminations in the sample structure. The obtained empirical relationships between these parameters of the frequency dependence of the ultrasound attenuation coefficient and the type of inhomogeneities and their volume concentration can be used for rapid evaluation of the structural quality of CFRP composites.

  7. Prestressing Effects on the Performance of Concrete Beams with Near-surface-mounted Carbon-fiber-reinforced Polymer Bars

    NASA Astrophysics Data System (ADS)

    Hong, Sungnam; Park, Sun-Kyu

    2016-07-01

    The effects of various prestressing levels on the flexural behavior of concrete beams strengthened with prestressed near-surface-mounted (NSM) carbon-fiber-reinforced polymer (CFRP) bars were investigated in this study. Four-point flexural tests up to failure were performed using a total of six strengthened prestressed and nonprestressed concrete beams. The nonprestressed strengthened beam failed by premature debonding at the interface of concrete and the epoxy adhesive, but the prestressed one failed owing due to rupture of the CFRP bar. As the prestressing level of the CFRP bar increased, the cracking and yield loads of the prestressed beams increased, but its effect on their deflections was insignificant. The ultimate load was constant regardless of prestressing level, but the ultimate deflection was almost inversely proportional to the level.

  8. Carbon Fiber Reinforced/Silicon Carbide Turbine Blisk Testing in the SIMPLEX Turbopump

    NASA Technical Reports Server (NTRS)

    Genge, Gary G.; Marsh, Matthew W.

    1999-01-01

    A program designed to implement a ceramic matrix composite integrally bladed disk (blisk) into rocket engine style turbomachinery has successfully completed testing. The Marshall Space Flight Center (MSFC) program, utilizing the MSFC turbomachinery design, analysis, and testing capabilities along with materials development capabilities from both Glenn Research Center (GRC) and MSFC, has tested two carbon fiber reinforced silicon carbide blisks in the Simplex Turbopump at MSFC's Test Stand 500. One blisk contained a polar woven fiber preform, while the second blisk tested utilized a quasi-isotropic preform. Vhile earlier papers have chronicled the program's design, material testing, and torque testing efforts, this paper focuses on the testing of the blisks in the Simplex turbopump. Emphasis will be placed on the actual condition of the blisks before and after the testing test program design methodology, and conclusions that can be drawn from the test data and blisk final conditions. The program performed three separate test series. The first series was needed to validate that the Simplex turbopump was correctly re-built following a major incident to the turbopump. The turbopump had two major differences from the original design. The most obvious difference was the sleeve required throughout the bore of the main housing. The second major difference was modifications to the pump diffuser to improve performance. Several areas were burnt during the incident and were either repaired by weld repair (pump inlet housing) or simply smoothed out (turbine nozzle discharge). The test series was designed to weed out any turbopump design and manufacturing flaws or fatigue issues prior to putting the C/SiC blisks into it. The second and third series were the C/SiC blisk test series. The primary goal of these series was to expose the blisks to as much fatigue causing dynamic stress as possible to examine the material's capability. Initially, the test plan was to put equal time on

  9. Mechanical analysis of carbon fiber reinforced shape memory polymer composite for self-deployable structure in space environment

    NASA Astrophysics Data System (ADS)

    Hong, Seok Bin; Ahn, Yong San; Jang, Joon Hyeok; Kim, Jin-Gyun; Goo, Nam Seo; Yu, Woong-Ryeol

    2016-04-01

    Shape memory polymer (SMP) is one of smart polymers which exhibit shape memory effect upon external stimuli. Reinforcements as carbon fiber had been used for making shape memory polymer composite (CF-SMPC). This study investigated a possibility of designing self-deployable structures in harsh space condition using CF-SMPCs and analyzed their shape memory behaviors with constitutive equation model.CF-SMPCs were prepared using woven carbon fabrics and a thermoset epoxy based SMP to obtain their basic mechanical properties including actuation in harsh environment. The mechanical and shape memory properties of SMP and CF-SMPCs were characterized using dynamic mechanical analysis (DMA) and universal tensile machine (UTM) with an environmental chamber. The mechanical properties such as flexural strength and tensile strength of SMP and CF-SMPC were measured with simple tensile/bending test and time dependent shape memory behavior was characterized with designed shape memory bending test. For mechanical analysis of CF-SMPCs, a 3D constitutive equation of SMP, which had been developed using multiplicative decomposition of the deformation gradient and shape memory strains, was used with material parameters determined from CF-SMPCs. Carbon fibers in composites reinforced tensile and flexural strength of SMP and acted as strong elastic springs in rheology based equation models. The actuation behavior of SMP matrix and CF-SMPCs was then simulated as 3D shape memory bending cases. Fiber bundle property was imbued with shell model for more precise analysis and it would be used for prediction of deploying behavior in self-deployable hinge structure.

  10. Mechanical properties and failure mechanisms of carbon fiber reinforced epoxy laminated composites

    NASA Astrophysics Data System (ADS)

    Richards Thissell, W.; Zurek, Anna K.; Addessio, Frank

    1996-05-01

    The mechanical behavior of quasi-isotropic and unidirectional epoxy-matrix carbon-fiber laminated composites subjected to compressive loading at strain rates of 10-3 and 2000 s-1 are described. Failure in the studied composites was dominated by delamination which proceeded by brittle fracture of the epoxy-matrix. The matrix-fiber bonding in these composites is very strong and prevented the occurrence of significant fiber-pullout. The mode I delamination strain energy release rate of the unidirectional composites was determined using the double cantilever beam and hole in plate compression method. The DCB method indicated a significant R curve effect attributed to fiber bridging while the presently available hole in plate analytical methods show questionable validity for highly anisotropic materials.

  11. Mechanical properties and failure mechanisms of carbon fiber reinforced epoxy laminated composites

    SciTech Connect

    Thissell, W.R.; Zurek, A.K.; Addessio, F.

    1995-09-01

    The mechanical behavior of quasi-isotropic and unidirectional epoxy-matrix carbon-fiber laminated composites subjected compressive loading at strain rates of 10{sup {minus}3} and 2000 s{sup {minus}1} are described. Failure in the studied composites was dominated by delamination which proceeded by brittle fracture of the epoxy-matrix. The matrix-fiber bonding in these composites is very strong and prevented the occurrence of significant fiber-pullout. The mode I delamination strain energy release rate of the unidirectional composites was determined using the double cantilever beam and hole in plate compression method. The DCB method indicated a significant R curve effect attributed to fiber bridging while the presently available hole in plate analytical methods show questionable validity for highly anisotropic materials.

  12. Effects of the Amount and Shape of Carbon Fiber-Reinforced Polymer Strengthening Elements on the Ductile Behavior of Reinforced Concrete Beams

    NASA Astrophysics Data System (ADS)

    Hong, Sungnam

    2014-09-01

    A series of beam tests were performed to evaluate the ductility of reinforced concrete (RC) beams strengthened with carbon-fiber-reinforced polymer (CFRP) elements. A total of nine RC beams were produced and loaded up to failure in three-point bending under deflection control. In addition, the amount and shape of the CFRP elements (plates/sheets) were considered as the key test variables. Test results revealed that the strengthening with CFRP elements in the width direction was more effective than the strengthening across their height. The energy method used in an analysis showed that the energy ratio of the beams strengthened with CFRP plates were half or less than half of the energy ratio of the beams strengthened with CFRP sheets. In addition, the ductility of the beams decreased as the strengthening ratio of the CFRP elements increased.

  13. Poly(vinylidene fluoride) reinforced by carbon fibers: Structural parameters of fibers and fiber-polymer adhesion

    NASA Astrophysics Data System (ADS)

    Wang, Jianghong; Wu, Defeng; Li, Xiang; Zhang, Ming; Zhou, Weidong

    2012-10-01

    Poly(vinylidene fluoride) (PVDF) composites containing carbon fibers (CFs) with or without surface treatment were prepared via melt mixing. The mechanical properties of the PVDF/CF composites were then studied to explore the relations between the short-range and long-range structures of CFs and the properties of the composites. The results showed that the presence of CFs had a reinforcement effect on the PVDF and the Nielsen model was used to describe the concentration effect of CFs, especially at the lower concentration levels. The short-range aspect ratio structure and the long-range orientation structure of the CFs are the two most important structures that affected the final properties of the composites. The effective aspect ratio and orientation degree of the CFs in the PVDF matrix can be evaluated by the Halpin-Tsai and the Krenchel-COX models, which agree well with the experimental observations. After surface treatment, the CFs show stronger reinforcement effect due to reduced interfacial tension and increased interfacial area between two phases

  14. The influence of sterilization processes on the micromechanical properties of carbon fiber-reinforced PEEK composites for bone implant applications.

    PubMed

    Godara, A; Raabe, D; Green, S

    2007-03-01

    The effect of sterilization on the structural integrity of the thermoplastic matrix composite polyetheretherketone (PEEK) reinforced with carbon fibers (CF) is investigated by nanoindentation and nanoscratch tests. The use of the material as a medical implant grade requires a detailed understanding of the micromechanical properties which primarily define its in vivo behavior. Sterilization is a mandatory process for such materials used in medical applications like bone implants. The steam and gamma radiation sterilization processes employed in this study are at sufficient levels to affect the micromechanical properties of some polymer materials, particularly in the interphase region between the polymer matrix and the reinforcing fibers. Nanoindentation and nanoscratch tests are used in this work to reveal local gradients in the hardness and the elastic properties of the interphase regions. Both methods help to explore microscopic changes in the hardness, reduced stiffness and scratch resistance in the interphase region and in the bulk polymer matrix due to the different sterilization processes employed. The results reveal that neither steam nor gamma radiation sterilization entails significant changes of the reduced elastic modulus, hardness or coefficient of friction in the bulk polymer matrix. However, minor material changes of the PEEK matrix were observed in the interphase region. Of the two sterilization methods used, the steam treatment has a more significant influence on these small changes in this region and appears to increase slightly the thickness of the interphase zone.

  15. Mechanical properties of several neat polymer matrix materials and unidirectional carbon fiber-reinforced composites

    NASA Technical Reports Server (NTRS)

    Coguill, Scott L.; Adams, Donald F.

    1989-01-01

    The mechanical and physical properties of three neat matrix materials, i.e., PEEK (polyetheretherketone) thermoplastic, Hexcel F155 rubber-toughened epoxy and Hercules 8551-7 rubber-toughened epoxy, were experimentally determined. Twelve unidirectional carbon fiber composites, incorporating matrix materials characterized in this or earlier studies (with one exception; the PISO(sub 2)-TPI matrix itself was not characterized), were also tested. These composite systems included AS4/2220-1, AS4/2220-3, T500/R914, IM6/HX1504, T300/4901A (MDA), T700/4901A (MDA), T300/4901B (MPDA), T700/4901B (MPDA), APC2 (AS4/PEEK, ICI), APC2 (AS4/PEEK, Langley Research Center), AS4/8551-7, and AS4/PISO(sub 2)-TPI. For the neat matrix materials, the tensile, shear, fracture toughness, coefficient of thermal expansion, and coefficient of moisture expansion properties were measured as a function of both temperature and moisture content. For the unidirectional composites, axial and transverse tensile, longitudinal shear, coefficient of thermal expansion, and coefficient of moisture expansion properties were determined, at room temperature and 100 C.

  16. Carbon Fiber Biocompatibility for Implants

    PubMed Central

    Petersen, Richard

    2016-01-01

    Carbon fibers have multiple potential advantages in developing high-strength biomaterials with a density close to bone for better stress transfer and electrical properties that enhance tissue formation. As a breakthrough example in biomaterials, a 1.5 mm diameter bisphenol-epoxy/carbon-fiber-reinforced composite rod was compared for two weeks in a rat tibia model with a similar 1.5 mm diameter titanium-6-4 alloy screw manufactured to retain bone implants. Results showed that carbon-fiber-reinforced composite stimulated osseointegration inside the tibia bone marrow measured as percent bone area (PBA) to a great extent when compared to the titanium-6-4 alloy at statistically significant levels. PBA increased significantly with the carbon-fiber composite over the titanium-6-4 alloy for distances from the implant surfaces of 0.1 mm at 77.7% vs. 19.3% (p < 10−8) and 0.8 mm at 41.6% vs. 19.5% (p < 10−4), respectively. The review focuses on carbon fiber properties that increased PBA for enhanced implant osseointegration. Carbon fibers acting as polymer coated electrically conducting micro-biocircuits appear to provide a biocompatible semi-antioxidant property to remove damaging electron free radicals from the surrounding implant surface. Further, carbon fibers by removing excess electrons produced from the cellular mitochondrial electron transport chain during periods of hypoxia perhaps stimulate bone cell recruitment by free-radical chemotactic influences. In addition, well-studied bioorganic cell actin carbon fiber growth would appear to interface in close contact with the carbon-fiber-reinforced composite implant. Resulting subsequent actin carbon fiber/implant carbon fiber contacts then could help in discharging the electron biological overloads through electrochemical gradients to lower negative charges and lower concentration. PMID:26966555

  17. Carbon Fiber Biocompatibility for Implants.

    PubMed

    Petersen, Richard

    Carbon fibers have multiple potential advantages in developing high-strength biomaterials with a density close to bone for better stress transfer and electrical properties that enhance tissue formation. As a breakthrough example in biomaterials, a 1.5 mm diameter bisphenol-epoxy/carbon-fiber-reinforced composite rod was compared for two weeks in a rat tibia model with a similar 1.5 mm diameter titanium-6-4 alloy screw manufactured to retain bone implants. Results showed that carbon-fiber-reinforced composite stimulated osseointegration inside the tibia bone marrow measured as percent bone area (PBA) to a great extent when compared to the titanium-6-4 alloy at statistically significant levels. PBA increased significantly with the carbon-fiber composite over the titanium-6-4 alloy for distances from the implant surfaces of 0.1 mm at 77.7% vs. 19.3% (p < 10(-8)) and 0.8 mm at 41.6% vs. 19.5% (p < 10(-4)), respectively. The review focuses on carbon fiber properties that increased PBA for enhanced implant osseointegration. Carbon fibers acting as polymer coated electrically conducting micro-biocircuits appear to provide a biocompatible semi-antioxidant property to remove damaging electron free radicals from the surrounding implant surface. Further, carbon fibers by removing excess electrons produced from the cellular mitochondrial electron transport chain during periods of hypoxia perhaps stimulate bone cell recruitment by free-radical chemotactic influences. In addition, well-studied bioorganic cell actin carbon fiber growth would appear to interface in close contact with the carbon-fiber-reinforced composite implant. Resulting subsequent actin carbon fiber/implant carbon fiber contacts then could help in discharging the electron biological overloads through electrochemical gradients to lower negative charges and lower concentration.

  18. Non destructive FTIR-photoacoustic spectroscopy studies on carbon fiber reinforced polyimide composite and water diffusion in epoxy resin

    NASA Astrophysics Data System (ADS)

    Vijayaraghavan, Ravikumar

    Photo-acoustic (PA) detection is a non-destructive, non-disruptive mode of sample analysis. The principle of PA detection is monitoring the change in thermal properties of the material as a result of optical absorption. The ability to use with any incident radiation source makes it an attractive technique to study molecular excitations, vibrations and defects in any sample. Given the need for non-destructive analysis, the tool can be employed to study plethora of samples ranging from organic to inorganic. In the polymeric domain, there is a significant need for studying samples non-destructively with the architecture intact. For instance, molecular characterization in carbon fiber reinforced polymer, chemical diffusion in polymer resin/membrane and particulate/fillers incorporated thermosets suffer in characterization due to sample make-up. These samples are affected by opacity and thickness, which make them a very difficult set-up to study using conventional spectroscopic tools. We have employed PA mode of detection in tandem with a FTIR source to study the molecular vibrations to get an understanding of the systems considered. The first part of the work involved employing PA spectroscopy to study the curing in carbon fiber reinforced polymer (CFRP). Phenyl-ethynyl terminated oligoamic acid impregnated composite system was studied. The curing of composite and resin was monitored using PAS and compared with Transmission FTIR on resin and dynamic scanning calorimetry (DSC). The composite showed two distinct reactions as a function of thermal treatment. (1) Imidization at low temperatures due to cyclo-dehydration and (2) at high temperatures, crosslinking due to ethynyl addition reaction. Composite exhibited enhanced curing trends compared to neat resin. Our results indicate that the thermal conductivity of the carbon fiber might play a role in heat transfer facilitating the reaction. The activation energy was found to be 23kcal/mol for the crosslinking step. The

  19. A retrospective long term study of teeth restored with prefabricated carbon fiber reinforced epoxy resin posts.

    PubMed

    Segerström, Susanna; Astbäck, Johnny; Ekstrand, Karl D

    2006-01-01

    The Composipost endodontic post, made of stretched aligned carbon fibers embedded in an epoxy-resin matrix, has since the beginning of the nineties been widely used for the restoration of endodontically treated teeth. The aim of this retrospective study was to evaluate the treatment outcome of the Composipost system up to 7 years. In a study published 1998, 236 patients treated during 1992-93 by seven Swedish general dental private practitioners were studied. Five of the former seven private practitionersi consented to participate in this follow up of that study. Thus the material was reduced to 138 patients. Thirty-nine of these were excluded due to insufficient data. For the remaining 99 patients, data were collected from dental records. All patients were offered a clinical examination but only 25 accepted. Data were collected from dental records for the remaining 74 patients. The mean follow up time was 6,7 years with a range from 1 month to 10 years (median 7.6 years, SD 2.5 years), (five teeth were extracted during the previous study). The outcome was considered successful if the post and core was in situ and showed no clinical or radiographic signs of technical failures. Sixty-four teeth (65%) restored with the Composipost system were successful after a mean time of 6.7 years. Thirty-two teeth were extracted due to fractures, periapical lesions and periodontitis. Dislodgment of post was observed in three cases. In conclusion, within the limitations of this study, after a mean time of 6.7 years, the Composipost restored teeth had shorter survival times than those of previously documented cast posts.

  20. The Importance of Carbon Fiber to Polymer Additive Manufacturing

    SciTech Connect

    Love, Lonnie J; Kunc, Vlastimil; Rios, Orlando; Duty, Chad E; Post, Brian K; Blue, Craig A

    2014-01-01

    Additive manufacturing holds tremendous promise in terms of revolutionizing manufacturing. However, fundamental hurdles limit mass adoption of the technology. First, production rates are extremely low. Second, the physical size of parts is generally small, less than a cubic foot. Third, while there is much excitement about metal additive manufacturing, the major growth area is in polymer additive manufacturing systems. Unfortunately, the mechanical properties of the polymer parts are poor, limiting the potential for direct part replacement. To address this issue, we describe three benefits of blending carbon fiber with polymer additive manufacturing. First, development of carbon fiber reinforced polymers for additive manufacturing achieves specific strengths approaching aerospace quality aluminum. Second, carbon fiber radically changes the behavior of the material during deposition, enabling large scale, out-of-the-oven, high deposition rate manufacturing. Finally, carbon fiber technology and additive manufacturing complement each other. Merging the two manufacturing processes enables the construction of complex components that would not be possible otherwise.

  1. Identification of the elastic and damping characteristics of carbon fiber-reinforced plastic based on a study of damping flexural vibrations of test specimens

    NASA Astrophysics Data System (ADS)

    Paimushin, V. N.; Firsov, V. A.; Gyunal, I.; Shishkin, V. M.

    2016-07-01

    A theoretical and experimental method for determining the elastic and damping characteristics of materials is proposed based on analysis of vibrograms of damping flexural vibrations of test specimens with different structures. It is shown that during tension-compression and shear of a carbon fiber-reinforced plastic made of Porcher 3692 carbon fabric and EDT-69NM polymer binder, its dynamic elastic modulus decreases considerably with increasing frequency of deformation in the range of 0-120 Hz. The amplitude dependences of the logarithmic vibration decrements of the carbon fiber-reinforced plastic are determined by minimizing the discrepancy between the experimental and calculated internal-damping parameters of the test specimens in tension-compression and shear.

  2. Temperature Dependence on the Strength and Stress Rupture Behavior of a Carbon-Fiber Reinforced Silicon Carbide (C/SiC) Composite

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.; Calomino, Anthony

    2002-01-01

    Tensile strengths and stress rupture lives of carbon-fiber reinforced silicon carbide (C/SiC) specimens were measured at 800 C and are compared to previously reported 1200 C data. All tests were conducted in an environmental chamber containing 1000 ppm of oxygen in argon. The average 800 C tensile strength of 610 MPa is 10% greater than at 1200 C. Average stress rupture lives at 800 C were 2.5 times longer than those obtained at 1200 C. The difference in the 800 and 1200 C lives is related to the oxidation rate of the reinforcing carbon fibers, which is the primary damage mode of C/SiC composites in oxygen-containing environments.

  3. Impact strength of continuous-carbon-fiber-reinforced silicon nitride measured by using the split Hopkinson pressure bar

    SciTech Connect

    Ogawa, Kinya; Sugiyama, Fumiko; Pezzotti, G.; Nishida, Toshihiko

    1998-01-01

    Three-point impact bending tests, using the split Hopkinson pressure bar method, were performed to evaluate the fracture resistance of monolithic silicon nitride (SN) and carbon-fiber-reinforced silicon nitride (CFRSN) ceramics. By applying ramped incident-stress waves in the split Hopkinson pressure bar apparatus, relatively smooth stress-time curves could be recorded without using any artificial filtering process. The maximum load in the load-deflection curve of the CFRSN material increased, in comparison to its static value, when impact testing was applied. Such behavior was substantially different from that of the monolithic SN material, for which the maximum load values from impact and static testing were almost the same. The time dependence of strength in the CFRSN ceramic was then investigated by using relaxation tests, and the impact strength behavior could be explained by these results. Also, the shear strength was significantly dependent on the deformation rate, whereas the tensile strength was almost independent of it. The experimental results were compared with the numerical predictions of the stress distribution that were obtained by using finite-element analysis.

  4. Modeling the Effect of Interface Wear on Fatigue Hysteresis Behavior of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    An analytical method has been developed to investigate the effect of interface wear on fatigue hysteresis behavior in carbon fiber-reinforced ceramic-matrix composites (CMCs). The damage mechanisms, i.e., matrix multicracking, fiber/matrix interface debonding and interface wear, fibers fracture, slip and pull-out, have been considered. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. Upon first loading to fatigue peak stress and subsequent cyclic loading, the fibers failure probabilities and fracture locations were determined by combining the interface wear model and fiber statistical failure model based on the assumption that the loads carried by broken and intact fibers satisfy the global load sharing criterion. The effects of matrix properties, i.e., matrix cracking characteristic strength and matrix Weibull modulus, interface properties, i.e., interface shear stress and interface debonded energy, fiber properties, i.e., fiber Weibull modulus and fiber characteristic strength, and cycle number on fibers failure, hysteresis loops and interface slip, have been investigated. The hysteresis loops under fatigue loading from the present analytical method were in good agreement with experimental data.

  5. Modeling the Effect of Oxidation on Tensile Strength of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    An analytical method has been developed to investigate the effect of oxidation on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs). The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The fiber strength degradation model and oxidation region propagation model have been adopted to analyze the oxidation effect on tensile strength of the composite, which is controlled by diffusion of oxygen gas through matrix cracks. Under tensile loading, the fibers failure probabilities were determined by combining oxidation model and fiber statistical failure model based on the assumption that fiber strength is subjected to two-parameter Weibull distribution and the loads carried by broken and intact fibers statisfy the global load sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength considering oxidation time and temperature have been analyzed.

  6. Evaluation of fatigue strength of plain and notched specimens of short carbon-fiber reinforced polyetheretherketone in comparison with polyetheretherketone

    NASA Astrophysics Data System (ADS)

    Nisitani, H.; Noguchi, H.; Kim, Y.-H.

    1992-11-01

    Rotating-bending fatigue tests of short carbon-fiber reinforced polyetheretherketone (CFRPEEK) and polyetheretherketone (PEEK) were carried out to investigate the fatigue characteristics of plain and notched specimens at room temperature. The fatigue mechanisms in the matrix and composite were clarified through successive surface observations using the replica method. The results were discussed using linear notch mechanics. In the plain specimen of PEEK, fracture always occurs from defects and the fatigue crack initiation is of the point-initiation type. Furthermore, the fatigue crack growth rate is very high and the fatigue strength is very sensitive to a notch. The fatigue strength of the composite is much more insensitive to a notch than that of PEEK. In general the fatigue crack initiates from near the fiber end, and propagates to the circumferential direction after it grows to some extent along the fiber. The fatigue strength of an arbitrary notched specimen of these two materials will be estimated from the present results rearranged based on 'linear notch mechanics'.

  7. Effects of Temperature, Oxidation and Fiber Preforms on Fatigue Life of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-08-01

    In this paper, the effects of temperature, oxidation and fiber preforms on the fatigue life of carbon fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) have been investigated. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface wear model and fibers statistical failure model at room temperature, and interface/fibers oxidation model, interface wear model and fibers statistical failure model at elevated temperatures in the oxidative environments. When the broken fibers fraction approaches to the critical value, the composites fatigue fracture. The fatigue life S-N curves and fatigue limits of unidirectional, cross-ply, 2D, 2.5D and 3D C/SiC composites at room temperature, 800 °C in air, 1100, 1300 and 1500 °C in vacuum conditions have been predicted.

  8. Carbon fiber reinforced polymer dimensional stability investigations for use on the laser interferometer space antenna mission telescope.

    PubMed

    Sanjuán, J; Preston, A; Korytov, D; Spector, A; Freise, A; Dixon, G; Livas, J; Mueller, G

    2011-12-01

    The laser interferometer space antenna (LISA) is a mission designed to detect low frequency gravitational waves. In order for LISA to succeed in its goal of direct measurement of gravitational waves, many subsystems must work together to measure the distance between proof masses on adjacent spacecraft. One such subsystem, the telescope, plays a critical role as it is the laser transmission and reception link between spacecraft. Not only must the material that makes up the telescope support structure be strong, stiff, and light, but it must have a dimensional stability of better than 1 pm Hz(-1/2) at 3 mHz and the distance between the primary and the secondary mirrors must change by less than 2.5 μm over the mission lifetime. Carbon fiber reinforced polymer is the current baseline material; however, it has not been tested to the pico meter level as required by the LISA mission. In this paper, we present dimensional stability results, outgassing effects occurring in the cavity and discuss its feasibility for use as the telescope spacer for the LISA spacecraft.

  9. Tolerancing of a carbon fiber reinforced polymer metering tube structure of a high-resolution space-borne telescope

    NASA Astrophysics Data System (ADS)

    Ekinci, Mustafa

    2016-07-01

    High resolution space borne telescopes require dimensionally stable structures to meet very stringent optical requirements. Furthermore, high resolution space borne telescope structures need to have high stiffness and be lightweight in order to survive launch loads. Carbon fiber reinforced polymers (CFRP) are lightweight and have tailorable mechanical properties like stiffness and coefficient of thermal expansion. However, mechanical properties are highly dependent on manufacturing processes and manufacturing precision. Moreover CFRP tend to absorb moisture which affects dimensional stability of the structure in the vacuum environment. In order to get specified properties out of manufacturing, tolerances need to be defined very accurately. In this paper, behavior of CFRP metering tube structure of a high resolution space borne camera is investigated for ply orientation, fiber and void content deviations which may arise from manufacturing errors and limitations. A computer code is generated to determine laminate properties of stacked up uni-directional (UD) laminae using classical laminate theory with fiber and matrix properties obtained from suppliers and literature. After defining laminate stackup, many samples are virtually created with ply orientations, volumetric fiber and void content that randomly deviates in a tolerance range which will be used in manufacturing. Normal distribution, standard deviation and mean values are presented for elasticity modulus, coefficient of thermal expansion (CTE), coefficient of moisture expansion (CME) and thermal conductivity in axial and transverse directions of quasi-isotropic stackups and other stackups which have properties presented in literature.

  10. Feasibility study of ultrasonic elliptical vibration-assisted reaming of carbon fiber reinforced plastics/titanium alloy stacks.

    PubMed

    Geng, Daxi; Zhang, Deyuan; Li, Zhe; Liu, Dapeng

    2017-03-01

    The production of high quality bolt holes, especially on the carbon fiber reinforced plastics/titanium alloy (CFRP/Ti) stacks, is essential to the manufacturing process in order to facilitate part assembly and improve the component mechanical integrity in aerospace industry. Reaming is widely used as a mandatory operation for bolt holes to meet the strict industry requirements. In this paper, the ultrasonic elliptical vibration-assisted reaming (UEVR) which is considered as a new method for finish machining of CFRP/Ti stacked holes is studied. The paper outlines an analysis of tool performance and hole quality in UEVR compared with that in conventional reaming (CR). Experimental results show that the quality of holes was significantly improved in UEVR. This is substantiated by monitoring cutting force, hole geometric precision and surface finish. The average thrust forces and torque in UEVR were decreased over 30% and 60% respectively. It is found that, during first 45 holes, better diameter tolerance (IT7 vs. IT8), smaller diameter difference of CFRP and Ti holes (around 3μm vs. 12μm), better geometrical errors were achieved in UEVR as compared to CR. As for surface finish, both of the average roughness and hole surface topography in UEVR were obviously improved.

  11. Selective responses of human gingival fibroblasts and bacteria on carbon fiber reinforced polyetheretherketone with multilevel nanostructured TiO2.

    PubMed

    Wang, Xiao; Lu, Tao; Wen, Jin; Xu, Lianyi; Zeng, Deliang; Wu, Qianju; Cao, Lingyan; Lin, Shuxian; Liu, Xuanyong; Jiang, Xinquan

    2016-03-01

    The long-term success of dental implants relies not only on stable osseointegration but also on the integration of implant surfaces with surrounding soft tissues. In our previous work, titanium plasma immersion ion implantation (PIII) technique was applied to modify the carbon-fiber-reinforced polyetheretherketone (CFRPEEK) surface, constructing a unique multilevel TiO2 nanostructure thus enhancing certain osteogenic properties. However, the interactions between the modified surface and soft-tissue cells are still not clear. Here, we fully investigate the biological behaviors of human gingival fibroblasts (HGFs) and oral pathogens on the structured surface, which determine the early peri-implant soft tissue integration. Scanning electron microscopy (SEM) shows the formation of nanopores with TiO2 nanoparticles embedded on both the sidewall and bottom. In vitro studies including cell adhesion, viability assay, wound healing assay, real-time PCR, western blot and enzyme-linked immunosorbent assay (ELISA) disclose improved adhesion, migration, proliferation, and collagen secretion ability of HGFs on the modified CFRPEEK. Moreover, the structured surface exhibits sustainable antibacterial properties towards Streptococcus mutans, Fusobacterium nucleatum and Porphyromonas gingivalis. Our results reveal that the multilevel TiO2 nanostructures can selectively enhance soft tissue integration and inhibit bacterial reproduction, which will further support and broaden the adoption of CFRPEEK materials in dental fields.

  12. Effects of Prior Aging at 288 deg C in Argon Environment on Creep Response of Carbon Fiber Reinforced PMR-15 Composite with + or - 45 deg Fiber Orientation at 288 deg C

    DTIC Science & Technology

    2009-06-01

    PMR-15 COMPOSITE WITH ±45° FIBER ORIENTATION AT 288 °C Tyler Gruters AFIT/GAE/ENY/09-J02 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR...CREEP RESPONSE OF CARBON FIBER REINFORCED PMR-15 COMPOSITE WITH ±45° FIBER ORIENTATION AT 288 °C THESIS Presented to the Faculty Department...RESPONSE OF CARBON FIBER REINFORCED PMR-15 COMPOSITE WITH ±45° FIBER ORIENTATION AT 288 °C Tyler Gruters Approved

  13. Fatigue Hysteresis of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Li, Longbiao

    2016-02-01

    When the fiber-reinforced ceramic-matrix composites (CMCs) are first loading to fatigue peak stress, matrix multicracking and fiber/matrix interface debonding occur. Under fatigue loading, the stress-strain hysteresis loops appear as fiber slipping relative to matrix in the interface debonded region upon unloading/reloading. Due to interface wear at room temperature or interface oxidation at elevated temperature, the interface shear stress degredes with increase of the number of applied cycles, leading to the evolution of the shape, location and area of stress-strain hysteresis loops. The evolution characteristics of fatigue hysteresis loss energy in different types of fiber-reinforced CMCs, i.e., unidirectional, cross-ply, 2D and 2.5D woven, have been investigated. The relationships between the fatigue hysteresis loss energy, stress-strain hysteresis loops, interface frictional slip, interface shear stress and interface radial thermal residual stress, matrix stochastic cracking and fatigue peak stress of fiber-reinforced CMCs have been established.

  14. A comprehensive study of woven carbon fiber-reinforced nylon 6 composites

    NASA Astrophysics Data System (ADS)

    Pillay, Selvum

    Liquid molding of thermoset composites has become very popular in all industry sectors, including aerospace, automotive, mass transit, and sporting goods, but the cost of materials and processing has limited the use to high-end applications. Thermoplastic composites are relatively cheap; however, the use has been limited to components with short fiber reinforcing. The high melt viscosity and short processing window precludes their use in the liquid molding of large structures and applications with continuous fiber reinforcement. The current research addresses the processing parameters, methodology, and limitations of vacuum assisted resin transfer molding (VARTM) of carbon fabric-reinforced, thermoplastic polyamide 6 (PA6). The material used is casting grade PA6. The process developed for using VARTM to produce carbon fabric-reinforced PA6 composites is explained in detail. The effects of infusion temperature and flow distance on the fiber weight fraction and crystallinity of the PA6 resin are presented. The degree of conversion from monomer to polymer was determined. Microscopic studies to show the wet-out of the fibers at the filament level are also presented. Tensile, flexural, short beam shear strength (SBSS), and low-velocity impact test results are presented and compared to a equivalent thermoset matrix composite. The rubber toughened epoxy system (SC-15) was chosen for the comparative study because the system has been especially developed to overcome the brittle nature of epoxy composites. The environmental effects of moisture and ultraviolet (UV) radiation on the carbon/nylon 6 composite were investigated. The samples were immersed in boiling water for 100 hr, and mechanical tests were conducted. Results showed that moisture causes plasticization of the matrix and attacks the fiber matrix interface. This leads to deterioration of the mechanical properties. The samples were also exposed to UV for up to 600 hr, and post exposure tests were conducted. The

  15. Forming of carbon fiber reinforced thermoplastic composite tubes - Experimental and numerical approaches

    NASA Astrophysics Data System (ADS)

    Maron, Bernhard; Garthaus, Christian; Lenz, Florian; Hornig, Andreas; Hübner, Michael; Gude, Maik

    2016-10-01

    Continuous-reinforced thermoplastic composites are of growing importance for series production of lightweight components in manifold industrial areas. Novel manufacturing technologies allow the production of hollow semi-finished products that are post formed to enhance functionality. To maximize efficiency in the development process of such components it is necessary to map the forming processes numerically using Finite Elements(FE)-methods. The aim is to perform feasibility studies at an early stage, reduce development time by virtual process optimization and to generate a detailed understanding of the post formed fiber architecture for further structural-mechanical analysis.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. ["Elastic osteosynthesis" with autocompression plates of carbon fiber reinforced thermoplastic material].

    PubMed

    Stange, J; Mittelmeier, H

    1989-06-01

    The problem of atrophic bone that occurs in osteosynthesis employing rigid plates is first depicted. Attempts at fabricating "simirigid" plates, which, however, have so far failed to gain any practical importance are then discussed. The reason for this seems to be that made of duroplastics cannot be molded during the operation and the thermoplastics do not have sufficient strength. The production of semirigid plates made of thermoplastic Polyethersulfon (PES), reinforced with 20% short carbon fibres, results in plates which are made moldable by heating in a small oven, white retaining sufficient static strength, although only limited fatigue strength. Biomechanical examinations revealed that with appropriate dimensioning of the plates, "elastic osteosynthesis" results in less loss of mechanical function of the stabilized bones, so that less atrophy of the bone may be expected. During more pronounced exercise loading, a reversible "springiness" of the fracture results, which might stimulate callus formation and improved stability.

  18. Modification of carbon fabrics by radio-frequency capacitive discharge at low pressure to regulate mechanical properties of carbon fiber reinforced plastics based on it

    NASA Astrophysics Data System (ADS)

    Garifullin, A. R.; Krasina, I. V.; Skidchenko, E. A.; Shaekhov, M. F.; Tikhonova, N. V.

    2017-01-01

    To increase the values of mechanical properties of carbon fiber (CF) composite materials used in sports equipment production the method of radio-frequency capacitive (RFC) low-pressure plasma treatment in air was proposed. Previously it was found that this type of modification allows to effectively regulate the surface properties of fibers of different nature. This treatment method differs from the traditional ones by efficiency and environmental friendliness as it does not require the use of aggressive, environmentally hazardous chemicals. In this paper it was established that RFC low-pressure air plasma treatment of carbon fabrics enhances the interlaminar shear strength (ILSS) of carbon fiber reinforced plastic (CFRP). As a result of experimental studies of CF by Fourier Transform Infrared (FTIR) spectroscopy method it was proved that after radio-frequency capacitive plasma treatment at low pressure in air the oxygen-containing functional groups is grafted on the surface. These groups improve adhesion at the interface “matrix-fiber”.

  19. Preparation of three-dimensional braided carbon fiber-reinforced PEEK composites for potential load-bearing bone fixations. Part I. Mechanical properties and cytocompatibility.

    PubMed

    Luo, Honglin; Xiong, Guangyao; Yang, Zhiwei; Raman, Sudha R; Li, Qiuping; Ma, Chunying; Li, Deying; Wang, Zheren; Wan, Yizao

    2014-01-01

    In this study, we focused on fabrication and characterization of three-dimensional carbon fiber-reinforced polyetheretherketone (C3-D/PEEK) composites for orthopedic applications. We found that pre-heating of 3-D fabrics before hot-pressing could eliminate pores in the composites prepared by 3-D co-braiding and hot-pressing techniques. The manufacturing process and the processing variables were studied and optimum parameters were obtained. Moreover, the carbon fibers were surface treated by the anodic oxidization and its effect on mechanical properties of the composites was determined. Preliminary cell studies with mouse osteoblast cells were also performed to examine the cytocompatibility of the composites. Feasibility of the C3-D/PEEK composites as load-bearing bone fixation materials was evaluated. Results suggest that the C3-D/PEEK composites show good promising as load-bearing bone fixations.

  20. Micromechanical Modeling for Tensile Behaviour of Carbon Fiber - Reinforced Ceramic - Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    The stress-strain curves of fiber - reinforced ceramic - matrix composites (CMCs) exhibit obvious non-linear behaviour under tensile loading. The occurrence of multiple damage mechanisms, i.e., matrix multicracking, fiber/matrix interface debonding and fibers fracture, is the mainly reason for the non-linear characteristic. The micromechanics approach has been developed to predict the tensile stress-strain curves of unidirectional, cross-ply and woven CMCs. The shear-lag model was used to describe the micro stress field of the damaged composite. The damage models were used to determine the evolution of micro damage parameters, i.e., matrix crack spacing, interface debonded length and broken fibers fraction. By combining the shear-lag model with damage models and considering the effect of transverse multicracking in the 90° plies or transverse yarns in cross-ply or woven CMCs, the tensile stress-strain curves of unidirectional, cross-ply, 2D and 2.5D woven CMCs have been predicted. The results agreed with experimental data.

  1. ABA and ABC type thermoplastic elastomer toughening of epoxy matrices and its effect on carbon fiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Pitchiaya, Gomatheeshwar

    Epoxy-matrices have high modulus, strength, excellent creep resistance, but lacks ductility. One approach to improve the mechanical toughness is the addition of thermoplastic elastomers (TPEs). The TPEs investigated here are triblock copolymers of styrene-butadiene-methyl methacrylate (SBM) and methylmethacrylate-butylacrylate-methylmethacrylate (MAM) of the ABC and ABA type, respectively. The effect of concentration (1-12.5 wt %) of these TPEs on a diglycidyl ether of bisphenol-A (DGEBA) epoxy cured with metaphenylenediamine (mPDA), has been investigated. The TPE-DGEBA epoxies were characterized by TGA, DMA, SEM and impact. The flexural modulus, flexural strength and thermal resistance remained unaffected up to 5 wt% loading of TPEs, and exhibited less than 10% decrease at higher weight percent. T g was unaffected for all concentrations. Fracture toughness was improved 250% and up to 375% (when non- stoichiometric amount of curing agent was used) with TPE addition to epoxy/mPDA matrix. A SBM(1phr)EPON system was chosen to be the matrix of choice for a fiber reinforced composite system with a 4wt% aromatic epoxy sizing on a AS4 (UV-treated) carbon fiber. The 0° and 90° flexural modulus and strength of a SBM modified system was compared with the neat and their fracture surfaces were analyzed. A 89% increase in flexural strength was observed in a 90° flexural test for the modified system when compared with the neat. Novel sizing agents were also developed to enhance interfacial shear strength (IFSS) and the fiber-matrix adhesion and their birefringence pattern were analyzed.

  2. Study on experimental characterization of carbon fiber reinforced polymer panel using digital image correlation: A sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Kashfuddoja, Mohammad; Prasath, R. G. R.; Ramji, M.

    2014-11-01

    In this work, the experimental characterization of polymer-matrix and polymer based carbon fiber reinforced composite laminate by employing a whole field non-contact digital image correlation (DIC) technique is presented. The properties are evaluated based on full field data obtained from DIC measurements by performing a series of tests as per ASTM standards. The evaluated properties are compared with the results obtained from conventional testing and analytical models and they are found to closely match. Further, sensitivity of DIC parameters on material properties is investigated and their optimum value is identified. It is found that the subset size has more influence on material properties as compared to step size and their predicted optimum value for the case of both matrix and composite material is found consistent with each other. The aspect ratio of region of interest (ROI) chosen for correlation should be the same as that of camera resolution aspect ratio for better correlation. Also, an open cutout panel made of the same composite laminate is taken into consideration to demonstrate the sensitivity of DIC parameters on predicting complex strain field surrounding the hole. It is observed that the strain field surrounding the hole is much more sensitive to step size rather than subset size. Lower step size produced highly pixilated strain field, showing sensitivity of local strain at the expense of computational time in addition with random scattered noisy pattern whereas higher step size mitigates the noisy pattern at the expense of losing the details present in data and even alters the natural trend of strain field leading to erroneous maximum strain locations. The subset size variation mainly presents a smoothing effect, eliminating noise from strain field while maintaining the details in the data without altering their natural trend. However, the increase in subset size significantly reduces the strain data at hole edge due to discontinuity in

  3. Multilayer Fiber Interfaces for Improved Environmental Resistance and Slip in Carbon Fiber Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Babcock, Jason R.; Ramachandran, Gautham; Williams, Brian E.; Effinger, Michael R.

    2004-01-01

    Ultraviolet-enhanced chemical vapor deposition (UVCVD) has been developed to lower the required substrate temperature thereby allowing for the application of metal oxide-based coatings to carbon and ceramic fibers without causing significant fiber damage. An effort to expand this capability to other ceramic phases chosen to maximize oxidation protection in the likely event of matrix cracking and minimize possible reaction between the coating and fiber during long-term high temperature use will be presented along with studies aimed at the demonstration of these and other benefits for the next-generation interface coating systems being developed herein.

  4. Laminates and reinforced metals

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1980-01-01

    A selective review is presented of the state of the art of metallic laminates and fiber reinforced metals called metallic matrix laminates (MMLs). Design and analysis procedures that are used for, and typical structural components that have been made from MMLs are emphasized. Selected MMLs, constituent materials, typical material properties and fabrication procedures are briefly described, including hybrids and superhybrids. Advantages, disadvantages, and special considerations required during design, analysis, and fabrication of MMLs are examined. Tabular and graphical data are included to illustrate key aspects of MMLs. Appropriate references are cited to provide a selective bibliography of a rapidly expanding and very promising research and development field.

  5. Dynamic response of concrete beams externally reinforced with carbon fiber reinforced plastic (CFRP) subjected to impulsive loads

    SciTech Connect

    Jerome, D.M.; Ross, C.A.

    1996-12-31

    A series of 54 laboratory scale concrete beams 3 x 3 x 30 in. in size were impulsively loaded to failure in a drop weight impact machine. The beams had no internal reinforcement, but instead were externally reinforced on the bottom or tension side of the beams with 1, 2, and 3 ply AS4C/1919 graphite epoxy panels. In addition, several of the beams were also reinforced on the sides with 3 ply CFRP. The beams were simply supported in a drop weight machine and subjected to impact loads with amplitudes up to 10 kips, and durations less than 1 ms, at beam midspan. Measurements made during the loading event included beam total load, midspan displacement, as well as midspan strain at 3 locations in the beam`s cross-section. A high speed framing camera was also used to record the beam`s displacement-time behavior as well as to gain insight into the failure mechanisms. Beam midspan accelerations were determined by double differentiation of the displacement versus time data, and in turn, the beam`s inertial loads were calculated using the beam`s equivalent mass. Beam dynamic bending loads versus time were determined from the difference between the total load versus time and the inertial load versus time data. Bending loads versus displacements were also determined along with fracture energies. Failure to correct the loads for inertia will result in incorrect conclusions being drawn from the data, especially for bending resistance of brittle concrete test specimens. A comparison with quasistatic bending (fracture) energy data showed that the dynamic failure energy absorbed by the beams was always less than the static fracture energy, due to the brittle nature of concrete when impulsively loaded.

  6. Effect of Environment on Stress-Rupture Behavior of a Carbon Fiber-Reinforced Silicon Carbide (C/SiC) Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Verrilli, Michael J.; Opila, Elizabeth J.; Calomino, Anthony; Kiser, J. Douglas

    2002-01-01

    Stress-rupture tests were conducted in air, vacuum, and steam-containing environments to identify the failure modes and degradation mechanisms of a carbon fiber-reinforced silicon carbide (C/SiC) composite at two temperatures, 600 and 1200 C. Stress-rupture lives in air and steam containing environments (50 - 80% steam with argon) are similar for a composite stress of 69 MPa at 1200 C. Lives of specimens tested in a 20% steam/argon environment were about twice as long. For tests conducted at 600 C, composite life in 20% steam/argon was 20 times longer than life in air. Thermogravimetric analysis of the carbon fibers was conducted under similar conditions to the stress-rupture tests. The oxidation rate of the fibers in the various environments correlated with the composite stress-rupture lives. Examination of the failed specimens indicated that oxidation of the carbon fibers was the primary damage mode for specimens tested in air and steam environments at both temperatures.

  7. The Reinforcing Effect of Carbon Fibers and PA6 on the Mechanical Properties of a PU Composites

    NASA Astrophysics Data System (ADS)

    Peng, Yongxin; Chi, Yilin; Dong, Weimin; Sun, Dongming; Mi, Weijian

    2013-07-01

    Ternary blend composites composed of two immiscible organic phases, polyurethane (PU) and polyamide-6 (PA6), and carbon fibers (CFs) as an inorganic filler are studied in terms of mechanical properties and morphology of the composites. The effects of different filler component ratios on its tensile, flexural, and impact strengths are investigated. Using the scanning electron microscopy (SEM), it is found that the addition of carbon fibers and PA6 is beneficial for raising the mechanical strength by increasing the dispersed interface phase. The optimum impact properties of CF/PA6/PU composites were obtained when the PA6 content in the 15 vol.% CF/PU composite was 6 vol.%.

  8. Effect of surface roughness on osteogenesis in vitro and osseointegration in vivo of carbon fiber-reinforced polyetheretherketone–nanohydroxyapatite composite

    PubMed Central

    Deng, Yi; Liu, Xiaochen; Xu, Anxiu; Wang, Lixin; Luo, Zuyuan; Zheng, Yunfei; Deng, Feng; Wei, Jie; Tang, Zhihui; Wei, Shicheng

    2015-01-01

    As United States Food and Drug Administration-approved implantable material, carbon fiber-reinforced polyetheretherketone (CFRPEEK) possesses an adjustable elastic modulus similar to cortical bone and is a prime candidate to replace surgical metallic implants. The bioinertness and inferior osteogenic properties of CFRPEEK, however, limit its clinical application as orthopedic/dental implants. In this study, CFRPEEK–nanohydroxyapatite ternary composites (PEEK/n-HA/CF) with variable surface roughness have been successfully fabricated. The effect of surface roughness on their in vitro cellular responses of osteoblast-like MG-63 cells (attachment, proliferation, apoptosis, and differentiation) and in vivo osseointegration is evaluated. The results show that the hydrophilicity and the amount of Ca ions on the surface are significantly improved as the surface roughness of composite increases. In cell culture tests, the results reveal that the cell proliferation rate and the extent of osteogenic differentiation of cells are a function of the size of surface roughness. The composite with moderate surface roughness significantly increases cell attachment/proliferation and promotes the production of alkaline phosphatase (ALP) activity and calcium nodule formation compared with the other groups. More importantly, the PEEK/n-HA/CF implant with appropriate surface roughness exhibits remarkably enhanced bioactivity and osseointegration in vivo in the animal experiment. These findings will provide critical guidance for the design of CFRPEEK-based implants with optimal roughness to regulate cellular behaviors, and to enhance biocompability and osseointegration. Meanwhile, the PEEK/n-HA/CF ternary composite with optimal surface roughness might hold great potential as bioactive biomaterial for bone grafting and tissue engineering applications. PMID:25733834

  9. Thermal oxidation induced degradation of carbon fiber reinforced composites and carbon nanotube sheet enhanced fiber/matrix interface for high temperature aerospace structural applications

    NASA Astrophysics Data System (ADS)

    Haque, Mohammad Hamidul

    Recent increase in the use of carbon fiber reinforced polymer matrix composite, especially for high temperature applications in aerospace primary and secondary structures along with wind energy and automotive industries, have generated new challenges to predict its failure mechanisms and service life. This dissertation reports the experimental study of a unidirectional carbon fiber reinforced bismaleimide (BMI) composites (CFRC), an excellent candidate for high temperature aerospace components, undergoing thermal oxidation at 260 °C in air for over 3000 hours. The key focus of the work is to investigate the mechanical properties of the carbon fiber BMI composite subjected to thermal aging in three key aspects - first, studying its bulk flexural properties (in macro scale), second, characterizing the crack propagation along the fiber direction, representing the interfacial bonding strength between fiber and matrix (in micro scale), and third, introducing nano-structured materials to modify the interface (in nano scale) between the carbon fiber and BMI resin and mechanical characterization to study its influence on mitigating the aging effect. Under the first category, weight loss and flexural properties have been monitored as the oxidation propagates through the fiber/matrix interface. Dynamic mechanical analysis and micro-computed tomography analysis have been performed to analyze the aging effects. In the second category, the long-term effects of thermal oxidation on the delamination (between the composite plies) and debonding (between fiber and matrix) type fracture toughness have been characterized by preparing two distinct types of double cantilever beam specimens. Digital image correlation has been used to determine the deformation field and strain distribution around the crack propagation path. Finally the resin system and the fiber/matrix interface have been modified using nanomaterials to mitigate the degradations caused by oxidation. Nanoclay modified

  10. Pulsed micro-laser line thermography on submillimeter porosity in carbon fiber reinforced polymer composites: experimental and numerical analyses for the capability of detection.

    PubMed

    Zhang, Hai; Fernandes, Henrique; Djupkep Dizeu, Frank Billy; Hassler, Ulf; Fleuret, Julien; Genest, Marc; Ibarra-Castanedo, Clemente; Robitaille, François; Joncas, Simon; Maldague, Xavier

    2016-12-01

    In this article, pulsed micro-laser line thermography (pulsed micro-LLT) was used to detect the submillimeter porosities in a 3D preformed carbon fiber reinforced polymer composite specimen. X-ray microcomputed tomography was used to verify the thermographic results. Then, finite element analysis was performed on the corresponding models on the basis of the experimental results. The same infrared image processing techniques were used for the experimental and simulation results for comparative purposes. Finally, a comparison of experimental and simulation postprocessing results was conducted. In addition, an analysis of probability of detection was performed to evaluate the detection capability of pulsed micro-LLT on submillimeter porosity.

  11. Carbonized asphaltene-based carbon-carbon fiber composites

    DOEpatents

    Bohnert, George; Lula, James; Bowen, III, Daniel E.

    2016-12-27

    A method of making a carbon binder-reinforced carbon fiber composite is provided using carbonized asphaltenes as the carbon binder. Combinations of carbon fiber and asphaltenes are also provided, along with the resulting composites and articles of manufacture.

  12. Acoustic emission and acousto-ultrasonic signature analysis of failure mechanisms in carbon fiber reinforced polymer materials

    NASA Astrophysics Data System (ADS)

    Carey, Shawn Allen

    Fiber reinforced polymer composite materials, particularly carbon (CFRPs), are being used for primary structural applications, particularly in the aerospace and naval industries. Advantages of CFRP materials, compared to traditional materials such as steel and aluminum, include: light weight, high strength to weight ratio, corrosion resistance, and long life expectancy. A concern with CFRPs is that despite quality control during fabrication, the material can contain many hidden internal flaws. These flaws in combination with unseen damage due to fatigue and low velocity impact have led to catastrophic failure of structures and components. Therefore a large amount of research has been conducted regarding nondestructive testing (NDT) and structural health monitoring (SHM) of CFRP materials. The principal objective of this research program was to develop methods to characterize failure mechanisms in CFRP materials used by the U.S. Army using acoustic emission (AE) and/or acousto-ultrasonic (AU) data. Failure mechanisms addressed include fiber breakage, matrix cracking, and delamination due to shear between layers. CFRP specimens were fabricated and tested in uniaxial tension to obtain AE and AU data. The specimens were designed with carbon fibers in different orientations to produce the different failure mechanisms. Some specimens were impacted with a blunt indenter prior to testing to simulate low-velocity impact. A signature analysis program was developed to characterize the AE data based on data examination using visual pattern recognition techniques. It was determined that it was important to characterize the AE event , using the location of the event as a parameter, rather than just the AE hit (signal recorded by an AE sensor). A back propagation neural network was also trained based on the results of the signature analysis program. Damage observed on the specimens visually with the aid of a scanning electron microscope agreed with the damage type assigned by the

  13. Structural Foaming at the Nano-, Micro-, and Macro-Scales of Continuous Carbon Fiber Reinforced Polymer Matrix Composites

    DTIC Science & Technology

    2012-10-29

    electrospinning . (Accomplishment 2) We improved material properties through the inclusion of aligned carbon nano- tubes, as evaluated with our...carbon fiber development during processing, degradation and electrospinning , in order to evaluate their structural contribution to the...Electrospun CNTs in polymer solution Figure 4 illustrates the basic electrospinning configuration that utilized a simple syringe-like apparatus

  14. Investigation of Electromagnetic Wave Absorber Based on Carbon Fiber Reinforced Aerated Concrete, Using Time-Domain Method

    NASA Astrophysics Data System (ADS)

    Laukaitis, A.; Sinica, M.; Balevičius, S.; Levitas, B.

    2008-03-01

    The electromagnetic wave absorbers prepared from autoclaved aerated concrete containing carbon fibers as additions in the shape of slabs with pyramids cut on one plane of these slabs were tested using dc microwave source and the time-domain method. It was demonstrated that autoclaved aerated concrete allows one to fabricate electromagnetic wave absorbers which have a reflection coefficient up to -30 dB in the frequency range from 2 GHz to 18 GHz.

  15. Self-healable interfaces based on thermo-reversible Diels-Alder reactions in carbon fiber reinforced composites.

    PubMed

    Zhang, W; Duchet, J; Gérard, J F

    2014-09-15

    Thermo-reversible Diels-Alder (DA) bonds formed between maleimide and furan groups have been used to generate an interphase between carbon fiber surface and an epoxy matrix leading to the ability of interfacial self-healing in carbon:epoxy composite materials. The maleimide groups were grafted on an untreated T700 carbon fiber from a three step surface treatment: (i) nitric acid oxidization, (ii) tetraethylenepentamine amination, and (iii) bismaleimide grafting. The furan groups were introduced in the reactive epoxy system from furfuryl glycidyl ether. The interface between untreated carbon fiber and epoxy matrix was considered as a reference. The interfacial shear strength (IFSS) was evaluated by single fiber micro-debonding test. The debonding force was shown to have a linear dependence with embedded length. The highest healing efficiency calculated from the debonding force was found to be about 82% more compared to the value for the reference interface. All the interphases designed with reversible DA bonds have a repeatable self-healing ability. As after the fourth healing, they can recover a relatively high healing efficiency (58% for the interphase formed by T700-BMI which is oxidized for 60 min during the first treatment step).

  16. Fast voltammetry of metals at carbon-fiber microelectrodes: copper adsorption onto activated carbon aids rapid electrochemical analysis.

    PubMed

    Pathirathna, Pavithra; Samaranayake, Srimal; Atcherley, Christopher W; Parent, Kate L; Heien, Michael L; McElmurry, Shawn P; Hashemi, Parastoo

    2014-09-21

    Rapid, in situ trace metal analysis is essential for understanding many biological and environmental processes. For example, trace metals are thought to act as chemical messengers in the brain. In the environment, some of the most damaging pollution occurs when metals are rapidly mobilized and transported during hydrologic events (storms). Electrochemistry is attractive for in situ analysis, primarily because electrodes are compact, cheap and portable. Electrochemical techniques, however, do not traditionally report trace metals in real-time. In this work, we investigated the fundamental mechanisms of a novel method, based on fast-scan cyclic voltammetry (FSCV), that reports trace metals with sub-second temporal resolution at carbon-fiber microelectrodes (CFMs). Electrochemical methods and geochemical models were employed to find that activated CFMs rapidly adsorb copper, a phenomenon that greatly advances the temporal capabilities of electrochemistry. We established the thermodynamics of surface copper adsorption and the electrochemical nature of copper deposition onto CFMs and hence identified a unique adsorption-controlled electrochemical mechanism for ultra-fast trace metal analysis. This knowledge can be exploited in the future to increase the sensitivity and selectivity of CFMs for fast voltammetry of trace metals in a variety of biological and environmental models.

  17. [Survey of carbon fiber reinforced plastic orthoses and occupational and medical problems based on a questionnaire administered to companies involved in the manufacture of prosthetics and orthotics].

    PubMed

    Kaneshiro, Yuko; Furuta, Nami; Makino, Kenichiro; Wada, Futoshi; Hachisuka, Kenji

    2011-09-01

    We surveyed carbon fiber reinforced plastic orthoses (carbon orthoses) and their associated occupational and medical problems based on a questionnaire sent to 310 companies which were members of the Japan Orthotics and Prosthetics Association. Of all the companies, 232 responded: 77 of the 232 companies dealt with ready-made carbon orthoses, 52 dealt with fabricated custom-made orthoses, and 155 did not dealt with carbon orthoses. Although the total number of custom-made carbon ortheses in Japan was 829/ 5 years, there was a difference by region, and one company fabricated only 12 (per 5 years) custom-made carbon orthoses on average. The advantages of the carbon orthosis were the fact that it was "light weight", "well-fitted", had a "good appearance", and "excellent durability", while the disadvantages were that it was "expensive", "high cost of production", of "black color", and required a "longer time for completion", and "higher fabrication techniques". From the standpoint of industrial medicine, "scattering of fine fragments of carbon fibers", "itching on the skin" and "health hazards" were indicated in companies that manufacture the orthosis. In order to make the carbon orthosis more popular, it is necessary to develop a new carbon material that is easier to fabricate at a lower cost, to improve the fabrication technique, and to resolve the occupational and medical problems.

  18. The impact of hygrothermal preconditioning on mode II interlaminar fracture toughness in unidirectional carbon fiber reinforced epoxy composites: An experimental investigation

    NASA Astrophysics Data System (ADS)

    Hempowicz, Michael L.

    The correlation between the interlaminar Mode II fracture toughness (GIIC) of a carbon fiber reinforced epoxy and other material properties across different conditioning regimes was investigated. Specimens were preconditioned using select hygrothermal criteria to evaluate how changes in the material and mechanical properties in a carbon fiber/epoxy composite correlations with changes in GIIC for each regime. An increase in GIIC from baseline values was demonstrated across all conditions from end-notched flexure (ENF) testing. Dynamic mechanical analysis (DMA) and tensile tests had varying responses based on preconditioning environment. Since tensile and some DMA properties rely on fiber strength and show property loss with increased plasticization, fiber strength may not have a large impact on GIIC properties. Test data also implied that the GIIC increased when consolidation of the polymer chains occurred in the arid condition as well as when crosslink density increased in the moisture exposed conditions. From these results it is believed that the chemical and physical changes in matrix cohesion are more important to GIIC behavior prediction than fiber behavior.

  19. Metal catalysts supported on activated carbon fibers for removal of polycyclic aromatic hydrocarbons from incineration flue gas.

    PubMed

    Lin, Chiou-Liang; Cheng, Yu-Hsiang; Liu, Zhen-Shu; Chen, Jian-Yuan

    2011-12-15

    The aim of this research was to use metal catalysts supported on activated carbon fibers (ACFs) to remove 16 species of polycyclic aromatic hydrocarbons (PAHs) from incineration flue gas. We tested three different metal loadings (0.11 wt%, 0.29 wt%, and 0.34 wt%) and metals (Pt, Pd, and Cu), and two different pretreatment solutions (HNO(3) and NaOH). The results demonstrated that the ACF-supported metal catalysts removed the PAHs through adsorption and catalysis. Among the three metals, Pt was most easily adsorbed on the ACFs and was the most active in oxidation of PAHs. The mesopore volumes and density of new functional groups increased significantly after the ACFs were pretreated with either solutions, and this increased the measured metal loading in HNO(3)-0.48% Pd/ACFs and NaOH-0.52% Pd/ACFs. These data confirm that improved PAH removal can be achieved with HNO(3)-0.48% Pd/ACFs and NaOH-0.52% Pd/ACFs.

  20. Global Carbon Fiber Composites Supply Chain Competitiveness Analysis

    SciTech Connect

    Das, Sujit; Warren, Josh; West, Devin; Schexnayder, Susan M.

    2016-05-01

    This analysis identifies key opportunities in the carbon fiber supply chain where resources and investments can help advance the clean energy economy. The report focuses on four application areas — wind energy, aerospace, automotive, and pressure vessels — that top the list of industries using carbon fiber and carbon fiber reinforced polymers. For each of the four application areas, the report addresses the supply and demand trends within that sector, supply chain, and costs of carbon fiber and components.

  1. Time dependence of mesoscopic strain distribution for triaxial woven carbon-fiber-reinforced polymer under creep loading measured by digital image correlation

    NASA Astrophysics Data System (ADS)

    Koyanagi, Jun; Nagayama, Hideo; Yoneyama, Satoru; Aoki, Takahira

    2016-06-01

    This paper presents the time dependence of the mesoscopic strain of a triaxial woven carbon-fiber-reinforced polymer under creep loading measured using digital image correlation (DIC). Two types of DIC techniques were employed for the measurement: conventional subset DIC and mesh DIC. Static tensile and creep tests were carried out, and the time dependence of the mesoscopic strain distribution was investigated by applying these techniques. The ultimate failure of this material is dominated by inter-bundle decohesion caused by relative rigid rotation and relating shear stress. Therefore, these were focused on in the present study. During the creep tests, the fiber directional strain, shear strain, and rotation were monitored using the DIC, and the mechanism for the increase in the specimen's macro-strain over time was investigated based on the results obtained by the DIC measurement.

  2. Carbon fiber reinforced plastic (CFRP) plates versus stainless steel dynamic compression plates in the treatment of fractures of the tibiae in dogs.

    PubMed

    Skirving, A P; Day, R; Macdonald, W; McLaren, R

    1987-11-01

    In a series of 14 dogs, fractures of both tibiae were caused by a "bone-breaker" designed in the authors' department and observed to produce a consistent and realistic canine fracture. One tibia was plated with a carbon fiber reinforced plastic (CFRP) plate and the other with a dynamic compression (DC) plate. Roentgenographic examination demonstrated healing of the CFRP-plated tibiae with abundant callus, and almost total remodeling of the fracture callus between ten and 20 weeks. Biomechanical testing by three-point bending revealed little difference between the strength of union of the fractures at 12-16 weeks. At 20 weeks, although the numbers were too small for statistical confirmation, the CFRP-plated tibiae were consistently stronger than the DC-plated tibiae.

  3. Influence of Layup and Curing on the Surface Accuracy in the Manufacturing of Carbon Fiber Reinforced Polymer (CFRP) Composite Space Mirrors

    NASA Astrophysics Data System (ADS)

    Yang, Zhiyong; Zhang, Jianbao; Xie, Yongjie; Zhang, Boming; Sun, Baogang; Guo, Hongjun

    2017-03-01

    Carbon fiber reinforced polymer, CFRP, composite materials have been used to fabricate space mirror. Usually the composite space mirror can completely replicate the high-precision surface of mould by replication process, but the actual surface accuracy of replicated space mirror is always reduced, still needed further study. We emphatically studied the error caused by layup and curing on the surface accuracy of space mirror through comparative experiments and analyses, the layup and curing influence factors include curing temperature, cooling rate of curing, method of prepreg lay-up, and area weight of fiber. Focusing on the four factors, we analyzed the error influence rule and put forward corresponding control measures to improve the surface figure of space mirror. For comparative analysis, six CFRP composite mirrors were fabricated and surface profile of mirrors were measured. Four guiding control measures were described here. Curing process of composite space mirror is our next focus.

  4. Scanning tone burst eddy-current thermography (S-TBET) for NDT of carbon fiber reinforced plastic (CFRP) components

    SciTech Connect

    Libin, M. N.; Maxfield, B. W.; Balasubramanian, Krishnan

    2014-02-18

    Tone Burst Eddy Current technique uses eddy current to apply transient heating inside a component and uses a conventional IR camera for visualization of the response to the transient heating. This technique has been earliest demonstrated for metallic components made of AL, Steel, Stainless Steel, etc., and for detection of cracks, corrosion and adhesive dis-bonds. Although, not nearly as conducting as metals, the Carbon Fibre Reinforced Plastic (CFRP) material absorbs measurable electromagnetic radiation in the frequency range above 10 kHz. When the surface temperature is observed on the surface that is being heated (defined as the surface just beneath and slightly to one side of the heating coil), the surface temperature increases with increasing frequency because the internal heating increases with frequency. A 2-D anisotropic transient Eddy current heating and thermal conduction model has been developed that provides a reasonable description of the processes described above. The inherent anisotropy of CFRP laminates is included in this model by calculating the heating due to three superimposed, tightly coupled isotropic layers having a specified ply-layup. The experimental apparatus consists of an induction heating coil and an IR camera with low NETD and high frame rates. The coil is moved over the sample using a stepper motor controlled manipulator. The IR data recording is synchronized with the motion control to provide a movie of the surface temperature over time. Several components were evaluated for detection of impact damage, location of stiffeners, etc. on CFRP components.

  5. Scanning tone burst eddy-current thermography (S-TBET) for NDT of carbon fiber reinforced plastic (CFRP) components

    NASA Astrophysics Data System (ADS)

    Libin, M. N.; Maxfield, B. W.; Balasubramanian, Krishnan

    2014-02-01

    Tone Burst Eddy Current technique uses eddy current to apply transient heating inside a component and uses a conventional IR camera for visualization of the response to the transient heating. This technique has been earliest demonstrated for metallic components made of AL, Steel, Stainless Steel, etc., and for detection of cracks, corrosion and adhesive dis-bonds. Although, not nearly as conducting as metals, the Carbon Fibre Reinforced Plastic (CFRP) material absorbs measurable electromagnetic radiation in the frequency range above 10 kHz. When the surface temperature is observed on the surface that is being heated (defined as the surface just beneath and slightly to one side of the heating coil), the surface temperature increases with increasing frequency because the internal heating increases with frequency. A 2-D anisotropic transient Eddy current heating and thermal conduction model has been developed that provides a reasonable description of the processes described above. The inherent anisotropy of CFRP laminates is included in this model by calculating the heating due to three superimposed, tightly coupled isotropic layers having a specified ply-layup. The experimental apparatus consists of an induction heating coil and an IR camera with low NETD and high frame rates. The coil is moved over the sample using a stepper motor controlled manipulator. The IR data recording is synchronized with the motion control to provide a movie of the surface temperature over time. Several components were evaluated for detection of impact damage, location of stiffeners, etc. on CFRP components.

  6. Storing Fluorine In Graphitelike Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1995-01-01

    Fluorine stored in graphite or graphitelike carbon fibers for later release and/or use in chemical reactions. Storage in carbon fibers eliminates difficulty and risk of using high-pressure tanks and pipes to hold corrosive gas. Storage in carbon fibers makes fluorine more readily accessible than does storage as constituent of metal fluoride. Carbon fibers heated to release stored fluorine, which draws away to vessel where reacts with material to be fluorinated, possibly at temperature other than release temperature. Alternatively, material to be fluorinated mixed or otherwise placed in contact with fibers and entire mass heated to or beyond release temperature.

  7. Comparison of Fracture Characteristics of Openhole-Notch Carbon-Fiber-Reinforced Composites Subjected to Tensile and Compressive Loadings

    NASA Astrophysics Data System (ADS)

    Saeed, M.-U.; Chen, Z. F.; Chen, Z. H.; Li, B. B.

    2017-01-01

    Open-hole tension (OHT) and open-hole compression (OHC) tests were carried out on hot-pressed carbon-fiberreinforced composite samples with a singular open hole. The fracture surfaces of the OHT- and OHC-tested specimens were examined by using scanning electron microscopy (SEM). SEM micrographs showed significant features on the surface of carbon fiber, matrix, and especially in the fiber/matrix interface. Interpretation of these micrographs revealed the possible failure mechanism of composite samples with an open hole under tensile and compressive loadings. Furthermore, a comparative study of these micrographs also pointed to certain specific differences between the fracture characteristics of open-hole composite samples failed under tension and compression. This information is useful in the post-failure analysis of a composite structure.

  8. Comparison of Fracture Characteristics of Open-Hole-Notch Carbon-Fiber-Reinforced Composites Subjected to Tensile and Compressive Loadings

    NASA Astrophysics Data System (ADS)

    Saeed, M.-U.; Chen, Z. F.; Chen, Z. H.; Li, B. B.

    2017-01-01

    Open-hole tension (OHT) and open-hole compression (OHC) tests were carried out on hot-pressed carbon-fiberreinforced composite samples with a singular open hole. The fracture surfaces of the OHT- and OHC-tested specimens were examined by using scanning electron microscopy (SEM). SEM micrographs showed significant features on the surface of carbon fiber, matrix, and especially in the fiber/matrix interface. Interpretation of these micrographs revealed the possible failure mechanism of composite samples with an open hole under tensile and compressive loadings. Furthermore, a comparative study of these micrographs also pointed to certain specific differences between the fracture characteristics of open-hole composite samples failed under tension and compression. This information is useful in the post-failure analysis of a composite structure.

  9. Comparative study on submillimeter flaws in stitched T-joint carbon fiber reinforced polymer by infrared thermography, microcomputed tomography, ultrasonic c-scan and microscopic inspection

    NASA Astrophysics Data System (ADS)

    Zhang, Hai; Hassler, Ulf; Genest, Marc; Fernandes, Henrique; Robitaille, Francois; Ibarra-Castanedo, Clemente; Joncas, Simon; Maldague, Xavier

    2015-10-01

    Stitching is used to reduce dry-core (incomplete infusion of T-joint core) and reinforce T-joint structure. However, it may cause new types of flaws, especially submillimeter flaws. Microscopic inspection, ultrasonic c-scan, pulsed thermography, vibrothermography, and laser spot thermography are used to investigate the internal flaws in a stitched T-joint carbon fiber-reinforced polymer (CFRP) matrix composites. Then, a new microlaser line thermography is proposed. Microcomputed tomography (microCT) is used to validate the infrared results. A comparison between microlaser line thermography and microCT is performed. It was concluded that microlaser line thermography can detect the internal submillimeter defects. However, the depth and size of the defects can affect the detection results. The microporosities with a diameter of less than 54 μm are not detected in the microlaser line thermography results. Microlaser line thermography can detect the microporosity (a diameter of 0.162 mm) from a depth of 90 μm. However, it cannot detect the internal microporosity (a diameter of 0.216 mm) from a depth of 0.18 mm. The potential causes are given. Finally, a comparative study is conducted.

  10. Carbon nanotube- and carbon fiber-reinforcement of ethylene-octene copolymer membranes for gas and vapor separation.

    PubMed

    Sedláková, Zuzana; Clarizia, Gabriele; Bernardo, Paola; Jansen, Johannes Carolus; Slobodian, Petr; Svoboda, Petr; Kárászová, Magda; Friess, Karel; Izak, Pavel

    2014-01-03

    Gas and vapor transport properties were studied in mixed matrix membranes containing elastomeric ethylene-octene copolymer (EOC or poly(ethylene-co-octene)) with three types of carbon fillers: virgin or oxidized multi-walled carbon nanotubes (CNTs) and carbon fibers (CFs). Helium, hydrogen, nitrogen, oxygen, methane, and carbon dioxide were used for gas permeation rate measurements. Vapor transport properties were studied for the aliphatic hydrocarbon (hexane), aromatic compound (toluene), alcohol (ethanol), as well as water for the representative samples. The mechanical properties and homogeneity of samples was checked by stress-strain tests. The addition of virgin CNTs and CFs improve mechanical properties. Gas permeability of EOC lies between that of the more permeable PDMS and the less permeable semi-crystalline polyethylene and polypropylene. Organic vapors are more permeable than permanent gases in the composite membranes, with toluene and hexane permeabilities being about two orders of magnitude higher than permanent gas permeability. The results of the carbon-filled membranes offer perspectives for application in gas/vapor separation with improved mechanical resistance.

  11. Carbon Nanotube- and Carbon Fiber-Reinforcement of Ethylene-Octene Copolymer Membranes for Gas and Vapor Separation

    PubMed Central

    Sedláková, Zuzana; Clarizia, Gabriele; Bernardo, Paola; Jansen, Johannes Carolus; Slobodian, Petr; Svoboda, Petr; Kárászová, Magda; Friess, Karel; Izak, Pavel

    2014-01-01

    Gas and vapor transport properties were studied in mixed matrix membranes containing elastomeric ethylene-octene copolymer (EOC or poly(ethylene-co-octene)) with three types of carbon fillers: virgin or oxidized multi-walled carbon nanotubes (CNTs) and carbon fibers (CFs). Helium, hydrogen, nitrogen, oxygen, methane, and carbon dioxide were used for gas permeation rate measurements. Vapor transport properties were studied for the aliphatic hydrocarbon (hexane), aromatic compound (toluene), alcohol (ethanol), as well as water for the representative samples. The mechanical properties and homogeneity of samples was checked by stress-strain tests. The addition of virgin CNTs and CFs improve mechanical properties. Gas permeability of EOC lies between that of the more permeable PDMS and the less permeable semi-crystalline polyethylene and polypropylene. Organic vapors are more permeable than permanent gases in the composite membranes, with toluene and hexane permeabilities being about two orders of magnitude higher than permanent gas permeability. The results of the carbon-filled membranes offer perspectives for application in gas/vapor separation with improved mechanical resistance. PMID:24957119

  12. Electrochemical Stability of Carbon Fibers Compared to Metal Foils as Current Collectors for Lithium-Ion Batteries

    SciTech Connect

    Martha, Surendra K; Dudney, Nancy J; Kiggans, Jim; Nanda, Jagjit

    2012-01-01

    The electrochemical behaviors of highly conductive, fully-graphitic, semi-graphitic and non-graphitic carbon fibers were studied as the cathode current collectors of lithium batteries in standard electrolyte (alkyl carbonate/LiPF6) solutions and compared to bare aluminum (Al). All of these current collectors demonstrate a stable electrochemical behavior within the potential range of 2.5 to 5 V, due to passivation by surface films. Carbon fibers have comparable electrochemical stability of Al and may be used in place Al foil. While the carbon fibers do not contribute any irreversible or extra capacity when they are cycled below 4.5 V, for fully-graphitic and semi-graphitic fibers PF6 intercalation and deintercalation into the carbon fiber may occur when they are cycled at high potentials >4.5 V.

  13. Coating Carbon Fibers With Platinum

    NASA Technical Reports Server (NTRS)

    Effinger, Michael R.; Duncan, Peter; Coupland, Duncan; Rigali, Mark J.

    2007-01-01

    A process for coating carbon fibers with platinum has been developed. The process may also be adaptable to coating carbon fibers with other noble and refractory metals, including rhenium and iridium. The coated carbon fibers would be used as ingredients of matrix/fiber composite materials that would resist oxidation at high temperatures. The metal coats would contribute to oxidation resistance by keeping atmospheric oxygen away from fibers when cracks form in the matrices. Other processes that have been used to coat carbon fibers with metals have significant disadvantages: Metal-vapor deposition processes yield coats that are nonuniform along both the lengths and the circumferences of the fibers. The electrical resistivities of carbon fibers are too high to be compatible with electrolytic processes. Metal/organic vapor deposition entails the use of expensive starting materials, it may be necessary to use a furnace, and the starting materials and/or materials generated in the process may be hazardous. The present process does not have these disadvantages. It yields uniform, nonporous coats and is relatively inexpensive. The process can be summarized as one of pretreatment followed by electroless deposition. The process consists of the following steps: The surfaces of the fiber are activated by deposition of palladium crystallites from a solution. The surface-activated fibers are immersed in a solution that contains platinum. A reducing agent is used to supply electrons to effect a chemical reduction in situ. The chemical reduction displaces the platinum from the solution. The displaced platinum becomes deposited on the fibers. Each platinum atom that has been deposited acts as a catalytic site for the deposition of another platinum atom. Hence, the deposition process can also be characterized as autocatalytic. The thickness of the deposited metal can be tailored via the duration of immersion and the chemical activity of the solution.

  14. Adhesion bonding techniques for highly loaded parts of continuous carbon-fiber reinforced polyetheretherketone (CF-PEEK/APC2)

    NASA Astrophysics Data System (ADS)

    Kempe, G.; Krauss, H.

    It is shown that the adhesion technology is applicable to the bonding of continuous fiber reinforced thermplastics. The influences and conditions under which an enhancement of the bonding strength can be achieved are described. Attention is focused on the applicability of the adhesion method to continuous fiber reinforced PEEK, acknowledging that PEEK is very resistant to chemicals and thereby, a poor candidate for the technique.

  15. Flexible Fiber-Shaped Supercapacitor Based on Nickel-Cobalt Double Hydroxide and Pen Ink Electrodes on Metallized Carbon Fiber.

    PubMed

    Gao, Libo; Surjadi, James Utama; Cao, Ke; Zhang, Hongti; Li, Peifeng; Xu, Shang; Jiang, Chenchen; Song, Jian; Sun, Dong; Lu, Yang

    2017-02-15

    Flexible fiber-shaped supercapacitors (FSSCs) are recently of extensive interest for portable and wearable electronic gadgets. Yet the lack of industrial-scale flexible fibers with high conductivity and capacitance and low cost greatly limits its practical engineering applications. To this end, we here present pristine twisted carbon fibers (CFs) coated with a thin metallic layer via electroless deposition route, which exhibits exceptional conductivity with ∼300% enhancement and superior mechanical strength (∼1.8 GPa). Subsequently, the commercially available conductive pen ink modified high conductive composite fibers, on which uniformly covered ultrathin nickel-cobalt double hydroxides (Ni-Co DHs) were introduced to fabricate flexible FSSCs. The synthesized functionalized hierarchical flexible fibers exhibit high specific capacitance up to 1.39 F·cm(-2) in KOH aqueous electrolyte. The asymmetric solid-state FSSCs show maximum specific capacitance of 28.67 mF·cm(-2) and energy density of 9.57 μWh·cm(-2) at corresponding power density as high as 492.17 μW·cm(-2) in PVA/KOH gel electrolyte, with demonstrated high flexibility during stretching, demonstrating their potential in flexible electronic devices and wearable energy systems.

  16. Fast voltammetry of metals at carbon-fiber microelectrodes: towards an online speciation sensor.

    PubMed

    Pathirathna, Pavithra; Siriwardhane, Thushani; McElmurry, Shawn P; Morgan, Stephen L; Hashemi, Parastoo

    2016-11-14

    Speciation controls the chemical behavior of trace metals. Thus, there is great demand for rapid speciation analysis in a variety of fields. In this study, we describe the application of fast scan cyclic voltammetry (FSCV) and fast scan adsorption controlled voltammetry (FSCAV) to trace metal speciation analysis. We show that Cu(2+) can be detected using FSCAV in different matrices. We find that matrices with different Cu(2+) binding ability do not affect the equilibrium of Cu(2+) adsorption onto CFMs, and thus are an excellent predictor for free Cu(2+) ([Cu(2+)]free) in solution. We modelled a correlation between the FSCV response, [Cu(2+)]free and log Kf for 15 different Cu(2+) complexes. Using our model, we rapidly predicted, and verified [Cu(2+)]free and Kf of a real groundwater sample spiked with Cu(2+). We thus highlight the potential of fast voltammetry as a rapid trace metal speciation sensor.

  17. Quantitative Damage Detection and Sparse Sensor Array Optimization of Carbon Fiber Reinforced Resin Composite Laminates for Wind Turbine Blade Structural Health Monitoring

    PubMed Central

    Li, Xiang; Yang, Zhibo; Chen, Xuefeng

    2014-01-01

    The active structural health monitoring (SHM) approach for the complex composite laminate structures of wind turbine blades (WTBs), addresses the important and complicated problem of signal noise. After illustrating the wind energy industry's development perspectives and its crucial requirement for SHM, an improved redundant second generation wavelet transform (IRSGWT) pre-processing algorithm based on neighboring coefficients is introduced for feeble signal denoising. The method can avoid the drawbacks of conventional wavelet methods that lose information in transforms and the shortcomings of redundant second generation wavelet (RSGWT) denoising that can lead to error propagation. For large scale WTB composites, how to minimize the number of sensors while ensuring accuracy is also a key issue. A sparse sensor array optimization of composites for WTB applications is proposed that can reduce the number of transducers that must be used. Compared to a full sixteen transducer array, the optimized eight transducer configuration displays better accuracy in identifying the correct position of simulated damage (mass of load) on composite laminates with anisotropic characteristics than a non-optimized array. It can help to guarantee more flexible and qualified monitoring of the areas that more frequently suffer damage. The proposed methods are verified experimentally on specimens of carbon fiber reinforced resin composite laminates. PMID:24763210

  18. Connecting high-performance carbon-fiber-reinforced polymer cables of suspension and cable-stayed bridges through the use of gradient materials

    NASA Astrophysics Data System (ADS)

    Meier, Urs; Farshad, Mehdi

    1996-08-01

    Carbon-fiber-reinforced polymer (CFRP) cables offer a very attractive combination of high specific strength and modulus (ratio of strength or modulus to density), outstanding fatigue performance, good corrosion resistance, and low axial thermal expansion. The high specific strength permits the design of structures with highly increased spans. The high specific modulus translates into a high relative equivalent modulus. This factor is very important in view of the deflection constraints imposed on large bridges. A relative high modulus coupled with a low mass density offer CFRP cables already an advantage for spans above 1000 m. Since 1980 EMPA has been developing CFRP cables for cable-stayed and suspension bridges that are produced as assemblies of parallel CFRP wires. The key problem facing the application of CFRP cables, and thus their widespread use in the future, is how to connect them. A new reliable anchoring scheme developed with computer-aided materials design and produced with advanced gradient materials based on ceramics and polymers is described. Early 1996 such CFRP cables with a load-carrying capacity of 12 MN (1200 metric tons) have been applied for the first time on a cable-stayed road bridge with a 124-m span. Each cable is built up from 241 CFRP wires having a diameter of 5 mm.

  19. Quantitative damage detection and sparse sensor array optimization of carbon fiber reinforced resin composite laminates for wind turbine blade structural health monitoring.

    PubMed

    Li, Xiang; Yang, Zhibo; Chen, Xuefeng

    2014-04-23

    The active structural health monitoring (SHM) approach for the complex composite laminate structures of wind turbine blades (WTBs), addresses the important and complicated problem of signal noise. After illustrating the wind energy industry's development perspectives and its crucial requirement for SHM, an improved redundant second generation wavelet transform (IRSGWT) pre-processing algorithm based on neighboring coefficients is introduced for feeble signal denoising. The method can avoid the drawbacks of conventional wavelet methods that lose information in transforms and the shortcomings of redundant second generation wavelet (RSGWT) denoising that can lead to error propagation. For large scale WTB composites, how to minimize the number of sensors while ensuring accuracy is also a key issue. A sparse sensor array optimization of composites for WTB applications is proposed that can reduce the number of transducers that must be used. Compared to a full sixteen transducer array, the optimized eight transducer configuration displays better accuracy in identifying the correct position of simulated damage (mass of load) on composite laminates with anisotropic characteristics than a non-optimized array. It can help to guarantee more flexible and qualified monitoring of the areas that more frequently suffer damage. The proposed methods are verified experimentally on specimens of carbon fiber reinforced resin composite laminates.

  20. Improvement of the mode II interface fracture toughness of glass fiber reinforced plastics/aluminum laminates through vapor grown carbon fiber interleaves

    PubMed Central

    Ning, Huiming; Li, Yuan; Hu, Ning; Cao, Yanping; Yan, Cheng; Azuma, Takesi; Peng, Xianghe; Wu, Liangke; Li, Jinhua; Li, Leilei

    2014-01-01

    The effects of acid treatment, vapor grown carbon fiber (VGCF) interlayer and the angle, i.e., 0° and 90°, between the rolling stripes of an aluminum (Al) plate and the fiber direction of glass fiber reinforced plastics (GFRP) on the mode II interlaminar mechanical properties of GFRP/Al laminates were investigated. The experimental results of an end notched flexure test demonstrate that the acid treatment and the proper addition of VGCF can effectively improve the critical load and mode II fracture toughness of GFRP/Al laminates. The specimens with acid treatment and 10 g m−2 VGCF addition possess the highest mode II fracture toughness, i.e., 269% and 385% increases in the 0° and 90° specimens, respectively compared to those corresponding pristine ones. Due to the induced anisotropy by the rolling stripes on the aluminum plate, the 90° specimens possess 15.3%–73.6% higher mode II fracture toughness compared to the 0° specimens. The improvement mechanisms were explored by the observation of crack propagation path and fracture surface with optical, laser scanning and scanning electron microscopies. Moreover, finite element analyses were carried out based on the cohesive zone model to verify the experimental fracture toughness and to predict the interface shear strength between the aluminum plates and GFRP laminates. PMID:27877680

  1. Improvement of the mode II interface fracture toughness of glass fiber reinforced plastics/aluminum laminates through vapor grown carbon fiber interleaves.

    PubMed

    Ning, Huiming; Li, Yuan; Hu, Ning; Cao, Yanping; Yan, Cheng; Azuma, Takesi; Peng, Xianghe; Wu, Liangke; Li, Jinhua; Li, Leilei

    2014-06-01

    The effects of acid treatment, vapor grown carbon fiber (VGCF) interlayer and the angle, i.e., 0° and 90°, between the rolling stripes of an aluminum (Al) plate and the fiber direction of glass fiber reinforced plastics (GFRP) on the mode II interlaminar mechanical properties of GFRP/Al laminates were investigated. The experimental results of an end notched flexure test demonstrate that the acid treatment and the proper addition of VGCF can effectively improve the critical load and mode II fracture toughness of GFRP/Al laminates. The specimens with acid treatment and 10 g m(-2) VGCF addition possess the highest mode II fracture toughness, i.e., 269% and 385% increases in the 0° and 90° specimens, respectively compared to those corresponding pristine ones. Due to the induced anisotropy by the rolling stripes on the aluminum plate, the 90° specimens possess 15.3%-73.6% higher mode II fracture toughness compared to the 0° specimens. The improvement mechanisms were explored by the observation of crack propagation path and fracture surface with optical, laser scanning and scanning electron microscopies. Moreover, finite element analyses were carried out based on the cohesive zone model to verify the experimental fracture toughness and to predict the interface shear strength between the aluminum plates and GFRP laminates.

  2. Improvement of the mode II interface fracture toughness of glass fiber reinforced plastics/aluminum laminates through vapor grown carbon fiber interleaves

    NASA Astrophysics Data System (ADS)

    Ning, Huiming; Li, Yuan; Hu, Ning; Cao, Yanping; Yan, Cheng; Azuma, Takesi; Peng, Xianghe; Wu, Liangke; Li, Jinhua; Li, Leilei

    2014-06-01

    The effects of acid treatment, vapor grown carbon fiber (VGCF) interlayer and the angle, i.e., 0° and 90°, between the rolling stripes of an aluminum (Al) plate and the fiber direction of glass fiber reinforced plastics (GFRP) on the mode II interlaminar mechanical properties of GFRP/Al laminates were investigated. The experimental results of an end notched flexure test demonstrate that the acid treatment and the proper addition of VGCF can effectively improve the critical load and mode II fracture toughness of GFRP/Al laminates. The specimens with acid treatment and 10 g m-2 VGCF addition possess the highest mode II fracture toughness, i.e., 269% and 385% increases in the 0° and 90° specimens, respectively compared to those corresponding pristine ones. Due to the induced anisotropy by the rolling stripes on the aluminum plate, the 90° specimens possess 15.3%-73.6% higher mode II fracture toughness compared to the 0° specimens. The improvement mechanisms were explored by the observation of crack propagation path and fracture surface with optical, laser scanning and scanning electron microscopies. Moreover, finite element analyses were carried out based on the cohesive zone model to verify the experimental fracture toughness and to predict the interface shear strength between the aluminum plates and GFRP laminates.

  3. Machinability of drilling T700/LT-03A carbon fiber reinforced plastic (CFRP) composite laminates using candle stick drill and multi-facet drill

    NASA Astrophysics Data System (ADS)

    Wang, Cheng-Dong; Qiu, Kun-Xian; Chen, Ming; Cai, Xiao-Jiang

    2015-03-01

    Carbon Fiber Reinforced Plastic (CFRP) composite laminates are widely used in aerospace and aircraft structural components due to their superior properties. However, they are regarded as difficult-to-cut materials because of bad surface quality and low productivity. Drilling is the most common hole making process for CFRP composite laminates and drilling induced delamination damage usually occurs severely at the exit side of drilling holes, which strongly deteriorate holes quality. In this work, the candle stick drill and multi-facet drill are employed to evaluate the machinability of drilling T700/LT-03A CFRP composite laminates in terms of thrust force, delamination, holes diameter and holes surface roughness. S/N ratio is used to characterize the thrust force while an ellipse-shaped delamination model is established to quantitatively analyze the delamination. The best combination of drilling parameters are determined by full consideration of S/N ratios of thrust force and the delamination. The results indicate that candle stick drill will induce the unexpected ellipse-shaped delamination even at its best drilling parameters of spindle speed of 10,000 rpm and feed rate of 0.004 mm/tooth. However, the multi-facet drill cutting at the relative lower feed rate of 0.004 mm/tooth and lower spindle speed of 6000 rpm can effectively prevent the delamination. Comprehensively, holes quality obtained by multi-facet drill is much more superior to those obtained by candle stick drill.

  4. Analysis of Carbon Fiber Reinforced PEEK Hinge Mechanism Articulation Components in a Rotating Hinge Knee Design: A Comparison of In Vitro and Retrieval Findings

    PubMed Central

    Giurea, Alexander; Pfaff, Andreas M.; Tozzi, Gianluca

    2016-01-01

    Carbon fiber reinforced poly-ether-ether-ketone (CFR-PEEK) represents a promising alternative material for bushings in total knee replacements, after early clinical failures of polyethylene in this application. The objective of the present study was to evaluate the damage modes and the extent of damage observed on CFR-PEEK hinge mechanism articulation components after in vivo service in a rotating hinge knee (RHK) system and to compare the results with corresponding components subjected to in vitro wear tests. Key question was if there were any similarities or differences between in vivo and in vitro damage characteristics. Twelve retrieved RHK systems after an average of 34.9 months in vivo underwent wear damage analysis with focus on the four integrated CFR-PEEK components and distinction between different damage modes and classification with a scoring system. The analysis included visual examination, scanning electron microscopy, and energy dispersive X-ray spectroscopy, as well as surface roughness and profile measurements. The main wear damage modes were comparable between retrieved and in vitro specimens (n = 3), whereby the size of affected area on the retrieved components showed a higher variation. Overall, the retrieved specimens seemed to be slightly heavier damaged which was probably attributable to the more complex loading and kinematic conditions in vivo. PMID:28101512

  5. Analysis of Carbon Fiber Reinforced PEEK Hinge Mechanism Articulation Components in a Rotating Hinge Knee Design: A Comparison of In Vitro and Retrieval Findings.

    PubMed

    Schierjott, Ronja A; Giurea, Alexander; Neuhaus, Hans-Joachim; Schwiesau, Jens; Pfaff, Andreas M; Utzschneider, Sandra; Tozzi, Gianluca; Grupp, Thomas M

    2016-01-01

    Carbon fiber reinforced poly-ether-ether-ketone (CFR-PEEK) represents a promising alternative material for bushings in total knee replacements, after early clinical failures of polyethylene in this application. The objective of the present study was to evaluate the damage modes and the extent of damage observed on CFR-PEEK hinge mechanism articulation components after in vivo service in a rotating hinge knee (RHK) system and to compare the results with corresponding components subjected to in vitro wear tests. Key question was if there were any similarities or differences between in vivo and in vitro damage characteristics. Twelve retrieved RHK systems after an average of 34.9 months in vivo underwent wear damage analysis with focus on the four integrated CFR-PEEK components and distinction between different damage modes and classification with a scoring system. The analysis included visual examination, scanning electron microscopy, and energy dispersive X-ray spectroscopy, as well as surface roughness and profile measurements. The main wear damage modes were comparable between retrieved and in vitro specimens (n = 3), whereby the size of affected area on the retrieved components showed a higher variation. Overall, the retrieved specimens seemed to be slightly heavier damaged which was probably attributable to the more complex loading and kinematic conditions in vivo.

  6. Thermoplastic-carbon fiber hybrid yarn

    NASA Technical Reports Server (NTRS)

    Ketterer, M. E.

    1984-01-01

    Efforts were directed to develop processing methods to make carbon fiber/thermoplastic fiber preforms that are easy to handle and drapeable, and to consolidate them into low void content laminates. The objectives were attained with the development of the hybrid yarn concept; whereby, thermoplastic fiber can be intimately intermixed with carbon fiber into a hybrid yarn. This was demonstrated with the intermixing of Celion 3000 with a Celanese liquid crystal polymer fiber, polybutylene terepthalate fiber, or polyetheretherketone fiber. The intermixing of the thermoplastic matrix fiber and the reinforcing carbon fiber gives a preform that can be easily fabricated into laminates with low void content. Mechanical properties of the laminates were not optimized; however, initial results indicated properties typical of a thermoplastic/carbon fiber composites prepared by more conventional methods.

  7. Selective Reinforcement to Enhance the Structural Performance of Metallic Compression Panels

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    2004-01-01

    An experimental and analytical investigation of the influence of selective reinforcement on metallic panels with cutouts was conducted. Selective reinforcement was shown to be a weight effective concept for increasing structural performance of panels with cutouts designed to carry loads into the post-buckled regime. For instance, a selectively reinforced aluminum panel under shear load exhibited a 68 percent increase in specific-buckling load as compared to a geometrically comparable unreinforced aluminum panel. In comparison, a quasi-isotropic carbon-fiber-reinforced-polymer composite panel only produced a 45 percent higher specific-buckling load than the same unreinforced aluminum panel. Selective reinforcement offers the potential to tailor structural response through local strengthening and stiffening the structure for a broad range of structural application.

  8. Influence of laminate sequence and fabric type on the inherent acoustic nonlinearity in carbon fiber reinforced composites.

    PubMed

    Chakrapani, Sunil Kishore; Barnard, Daniel J; Dayal, Vinay

    2016-05-01

    This paper presents the study of influence of laminate sequence and fabric type on the baseline acoustic nonlinearity of fiber-reinforced composites. Nonlinear elastic wave techniques are increasingly becoming popular in detecting damage in composite materials. It was earlier observed by the authors that the non-classical nonlinear response of fiber-reinforced composite is influenced by the fiber orientation [Chakrapani, Barnard, and Dayal, J. Acoust. Soc. Am. 137(2), 617-624 (2015)]. The current study expands this effort to investigate the effect of laminate sequence and fabric type on the non-classical nonlinear response. Two hypotheses were developed using the previous results, and the theory of interlaminar stresses to investigate the influence of laminate sequence and fabric type. Each hypothesis was tested by capturing the nonlinear response by performing nonlinear resonance spectroscopy and measuring frequency shifts, loss factors, and higher harmonics. It was observed that the laminate sequence can either increase or decrease the nonlinear response based on the stacking sequence. Similarly, tests were performed to compare unidirectional fabric and woven fabric and it was observed that woven fabric exhibited a lower nonlinear response compared to the unidirectional fabric. Conjectures based on the matrix properties and interlaminar stresses were used in an attempt to explain the observed nonlinear responses for different configurations.

  9. Numerical Predictions of Damage and Failure in Carbon Fiber Reinforced Laminates Using a Thermodynamically-Based Work Potential Theory

    NASA Technical Reports Server (NTRS)

    Pineda, Evan Jorge; Waas, Anthony M.

    2013-01-01

    A thermodynamically-based work potential theory for modeling progressive damage and failure in fiber-reinforced laminates is presented. The current, multiple-internal state variable (ISV) formulation, referred to as enhanced Schapery theory (EST), utilizes separate ISVs for modeling the effects of damage and failure. Consistent characteristic lengths are introduced into the formulation to govern the evolution of the failure ISVs. Using the stationarity of the total work potential with respect to each ISV, a set of thermodynamically consistent evolution equations for the ISVs are derived. The theory is implemented into a commercial finite element code. The model is verified against experimental results from two laminated, T800/3900-2 panels containing a central notch and different fiber-orientation stacking sequences. Global load versus displacement, global load versus local strain gage data, and macroscopic failure paths obtained from the models are compared against the experimental results.

  10. Quench Crucibles Reinforced with Metal

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Carrasquillo, Edgar; O'Dell, J. Scott; McKehnie, N.

    2008-01-01

    Improved crucibles consisting mainly of metal-reinforced ceramic ampules have been developed for use in experiments in which material specimens are heated in the crucibles to various high temperatures, then quenched by, for example, plunging the crucibles into water at room temperature. In a traditional quench crucible, the gap between the ampule and the metal cartridge impedes the transfer of heat to such a degree that the quench rate (the rate of cooling of the specimen) can be too low to produce the desired effect in the specimen. One can increase the quench rate by eliminating the metal cartridge to enable direct quenching of the ampule, but then the thermal shock of direct quenching causes cracking of the ampule. In a quench crucible of the present improved type, there is no gap and no metal cartridge in the traditional sense. Instead, there is an overlay of metal in direct contact with the ampule, as shown on the right side of the figure. Because there is no gap between the metal overlay and the ampule, the heat-transfer rate can be much greater than it is in a traditional quench crucible. The metal overlay also reinforces the ampule against cracking.

  11. Modeling for Fatigue Hysteresis Loops of Carbon Fiber-Reinforced Ceramic-Matrix Composites under Multiple Loading Stress Levels

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    In this paper, the fatigue hysteresis loops of fiber-reinforced ceramic-matrix composites (CMCs) under multiple loading stress levels considering interface wear has been investigated using micromechanical approach. Under fatigue loading, the fiber/matrix interface shear stress decreases with the increase of cycle number due to interface wear. Upon increasing of fatigue peak stress, the interface debonded length would propagate along the fiber/matrix interface. The difference of interface shear stress existed in the new and original debonded region would affect the interface debonding and interface frictional slipping between the fiber and the matrix. Based on the fatigue damage mechanism of fiber slipping relative to matrix in the interface debonded region upon unloading and subsequent reloading, the interface slip lengths, i.e., the interface debonded length, interface counter-slip length and interface new-slip length, are determined by fracture mechanics approach. The fatigue hysteresis loops models under multiple loading stress levels have been developed. The effects of single/multiple loading stress levels and different loading sequences on fatigue hysteresis loops have been investigated. The fatigue hysteresis loops of unidirectional C/SiC composite under multiple loading stress levels have been predicted.

  12. Numerical and experimental investigation of the structural behavior of a carbon fiber reinforced ankle-foot orthosis.

    PubMed

    Stier, Bertram; Simon, Jaan-Willem; Reese, Stefanie

    2015-05-01

    Ankle-foot orthoses (AFOs) are designed to enhance the gait function of individuals with motor impairments. Recent AFOs are often made of laminated composites due to their high stiffness and low density. Since the performance of AFO is primarily influenced by their structural stiffness, the investigation of the mechanical response is very important for the design. The aim of this paper is to present a three dimensional multi-scale structural analysis methodology to speed up the design process of AFO. The multi-scale modeling procedure was applied such that the intrinsic micro-structure of the fiber reinforced laminates could be taken into account. In particular, representative volume elements were used on the micro-scale, where fiber and matrix were treated separately, and on the textile scale of the woven structure. For the validation of this methodology, experimental data were generated using digital image correlation (DIC) measurements. Finally, the structural behavior of the whole AFO was predicted numerically for a specific loading scenario and compared with experimental results. It was shown that the proposed numerical multi-scale scheme is well suited for the prediction of the structural behavior of AFOs, validated by the comparison of local strain fields as well as the global force-displacement curves.

  13. Numerical simulating and experimental study on the woven carbon fiber-reinforced composite laminates under low-velocity impact

    NASA Astrophysics Data System (ADS)

    Liu, Hanyang; Tang, Zhanwen; Pan, Lingying; Zhao, Weidong; Sun, Baogang; Jiang, Wenge

    2016-05-01

    Impact damage has been identified as a critical form of the defects that constantly threatened the reliability of composite structures, such as those used in the aerospace structures and systems. Low energy impacts can introduce barely visible damage and cause the degradation of structural stiffness, furthermore, the flaws caused by low-velocity impact are so dangerous that they can give rise to the further extended delaminations. In order to improve the reliability and load carrying capacity of composite laminates under low-velocity impact, in this paper, the numerical simulatings and experimental studies on the woven fiber-reinforced composite laminates under low-velocity impact with impact energy 16.7J were discussed. The low velocity impact experiment was carried out through drop-weight system as the reason of inertia effect. A numerical progressive damage model was provided, in which the damages of fiber, matrix and interlamina were considered by VUMT subroutine in ABAQUS, to determine the damage modes. The Hashin failure criteria were improved to cover the failure modes of fiber failure in the directions of warp/weft and delaminations. The results of Finite Element Analysis (FEA) were compared with the experimental results of nondestructive examination including the results of ultrasonic C-scan, cross-section stereomicroscope and contact force - time history curves. It is found that the response of laminates under low-velocity impact could be divided into stages with different damage. Before the max-deformation of the laminates occurring, the matrix cracking, fiber breakage and delaminations were simulated during the impactor dropping. During the releasing and rebounding period, matrix cracking and delaminations areas kept increasing in the laminates because of the stress releasing of laminates. Finally, the simulating results showed the good agreements with the results of experiment.

  14. Polarization dependence of laser interaction with carbon fibers and CFRP.

    PubMed

    Freitag, Christian; Weber, Rudolf; Graf, Thomas

    2014-01-27

    A key factor for laser materials processing is the absorptivity of the material at the laser wavelength, which determines the fraction of the laser energy that is coupled into the material. Based on the Fresnel equations, a theoretical model is used to determine the absorptivity for carbon fiber fabrics and carbon fiber reinforced plastics (CFRP). The surface of each carbon fiber is considered as multiple layers of concentric cylinders of graphite. With this the optical properties of carbon fibers and their composites can be estimated from the well-known optical properties of graphite.

  15. Composite reinforced metallic cylinder for? high-speed rotation

    NASA Astrophysics Data System (ADS)

    Pradhan, Sahadev, , Dr.

    2017-01-01

    The objective of the present study is to design and development of the composite reinforced thin metallic cylinder to increase the peripheral speed significantly and thereby? improve the separation performance in a centrifugal gas separation processes through? proper optimization of the internal parameters. According to Dirac equation (Cohen? (1951)), the maximum separative work for a centrifugal gas separation process increase? with 4th power of the peripheral speed. Therefore, it has been intended to reinforce the? metallic cylinder with composites (carbon fibers: T-700 and T- 1000 grade with suitable? epoxy resin) to increase the stiffness and hoop stress so that the peripheral speed can? be increased significantly, and thereby enhance the separative output. Here, we have developed the mathematical model to investigate the elastic stresses of? a laminated cylinder subjected to mechanical, thermal and thermo-mechanical loading? A detailed analysis is carried out to underline the basic hypothesis of each formulation? Further, we evaluate the steady state creep response of the rotating cylinder and analyze? the stresses and strain rates in the cylinder.

  16. Investigation of Selectively-Reinforced Metallic Lugs

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Abada, Christopher H.

    2007-01-01

    An investigation of the effects of material and geometric variables on the response of U-shaped band-reinforced metallic lugs was performed. Variables studied were reinforcement, adhesive and metallic lug mechanical properties, hole diameter, reinforcement and adhesive thickness, and the distance from the hole s center to the end of the lug. Generally, U-shaped band reinforced lugs exhibited superior performance than non-reinforced lugs, that is higher load at the conventional lug design criteria of four percent hole elongation. Depending upon the reinforcement configuration the increase in load may be negligible to 15 or 20 percent. U-shaped band reinforcement increases lug load carrying capability primarily through two mechanisms; increasing the slope of the response curve after the initial knee and restraining overall deformation of the metallic portion of the lug facilitating increased yielding of metallic material between the hole and the edge of the metallic portion of the lug.

  17. Lightning Strike Induced Damage Mechanisms of Carbon Fiber Composites

    NASA Astrophysics Data System (ADS)

    Kawakami, Hirohide

    Composite materials have a wide application in aerospace, automotive, and other transportation industries, because of the superior structural and weight performances. Since carbon fiber reinforced polymer composites possess a much lower electrical conductivity as compared to traditional metallic materials utilized for aircraft structures, serious concern about damage resistance/tolerance against lightning has been rising. Main task of this study is to clarify the lightning damage mechanism of carbon fiber reinforced epoxy polymer composites to help further development of lightning strike protection. The research on lightning damage to carbon fiber reinforced polymer composites is quite challenging, and there has been little study available until now. In order to tackle this issue, building block approach was employed. The research was started with the development of supporting technologies such as a current impulse generator to simulate a lightning strike in a laboratory. Then, fundamental electrical properties and fracture behavior of CFRPs exposed to high and low level current impulse were investigated using simple coupon specimens, followed by extensive parametric investigations in terms of different prepreg materials frequently used in aerospace industry, various stacking sequences, different lightning intensity, and lightning current waveforms. It revealed that the thermal resistance capability of polymer matrix was one of the most influential parameters on lightning damage resistance of CFRPs. Based on the experimental findings, the semi-empirical analysis model for predicting the extent of lightning damage was established. The model was fitted through experimental data to determine empirical parameters and, then, showed a good capability to provide reliable predictions for other test conditions and materials. Finally, structural element level lightning tests were performed to explore more practical situations. Specifically, filled-hole CFRP plates and patch

  18. Simulations of carbon fiber composite delamination tests

    SciTech Connect

    Kay, G

    2007-10-25

    Simulations of mode I interlaminar fracture toughness tests of a carbon-reinforced composite material (BMS 8-212) were conducted with LSDYNA. The fracture toughness tests were performed by U.C. Berkeley. The simulations were performed to investigate the validity and practicality of employing decohesive elements to represent interlaminar bond failures that are prevalent in carbon-fiber composite structure penetration events. The simulations employed a decohesive element formulation that was verified on a simple two element model before being employed to perform the full model simulations. Care was required during the simulations to ensure that the explicit time integration of LSDYNA duplicate the near steady-state testing conditions. In general, this study validated the use of employing decohesive elements to represent the interlaminar bond failures seen in carbon-fiber composite structures, but the practicality of employing the elements to represent the bond failures seen in carbon-fiber composite structures during penetration events was not established.

  19. Wettability of a Single Carbon Fiber.

    PubMed

    Qiu, Si; Fuentes, Carlos A; Zhang, Dongxing; Van Vuure, Aart Willem; Seveno, David

    2016-09-27

    Wettability as determined from contact angle measurements is a suitable parameter for characterizing the physical bonding of a polymer matrix and reinforcing fibers, but it is very challenging to measure the capillary force exerted by a probe liquid on a fiber accurately for very fine fibers such as single carbon fibers. Herein, we propose an innovative method for measuring dynamic contact angles with a tensiometer, considering both the intrinsic variability of the carbon fiber diameter and the extremely small amplitude of the capillary forces, allowing the measurement of reliable dynamic contact angles over a large range of contact line velocities. The analysis of the contact angle dynamics by the molecular-kinetic theory permits us to check the relevancy of the measured contact angles and to obtain the static contact angle value, improving the prospect of employing tensiometry to better understand the wetting behavior of carbon fibers.

  20. Carbon fiber content measurement in composite

    NASA Astrophysics Data System (ADS)

    Wang, Qiushi

    Carbon fiber reinforced polymers (CFRPs) have been widely used in various structural applications in industries such as aerospace and automotive because of their high specific stiffness and specific strength. Their mechanical properties are strongly influenced by the carbon fiber content in the composites. Measurement of the carbon fiber content in CFRPs is essential for product quality control and process optimization. In this work, a novel carbonization-in-nitrogen method (CIN) is developed to characterize the fiber content in carbon fiber reinforced thermoset and thermoplastic composites. In this method, a carbon fiber composite sample is carbonized in a nitrogen environment at elevated temperatures, alongside a neat resin sample. The carbon fibers are protected from oxidization while the resin (the neat resin and the resin matrix in the composite sample) is carbonized under the nitrogen environment. The residue of the carbonized neat resin sample is used to calibrate the resin carbonization rate and calculate the amount of the resin matrix in the composite sample. The new method has been validated on several thermoset and thermoplastic resin systems and found to yield an accurate measurement of fiber content in carbon fiber polymer composites. In order to further understand the thermal degradation behavior of the high temperature thermoplastic polymer during the carbonization process, the mechanism and the kinetic model of thermal degradation behavior of carbon fiber reinforced poly (phenylene sulfide) (CPPS) are studied using thermogravimetry analysis (TGA). The CPPS is subjected to TGA in an air and nitrogen atmosphere at heating rates from 5 to 40°C min--1. The TGA curves obtained in air are different from those in nitrogen. This demonstrates that weight loss occurs in a single stage in nitrogen but in two stages in air. To elucidate this difference, thermal decomposition kinetics is analyzed by applying the Kissinger, Flynn-Wall-Ozawa, Coat-Redfern and

  1. Matrix structure evolution and thermo-mechanical properties of carbon fiber-reinforced Al{sub 2}O{sub 3}-SiC-C castable composites

    SciTech Connect

    Li, Xiangcheng Li, Yaxiong; Chen, Liufang; Zhu, Boquan

    2015-01-15

    Highlights: • Carbon fibers are formed in Al{sub 2}O{sub 3}-SiC-C castable composites under the action of nano Ni. • Starting growth temperature is 900 °C and growth mechanism agrees with V–S model. • The high temperature strength of composites can be increased by above 40%. • The thermal shock resistance can be enhanced by above 20%. - Abstract: The spalling and corrosion during the thermal cycles are the main causes of the damages observed in Al{sub 2}O{sub 3}-SiC-C castable composites that are used in molten-iron system. Using the catalyst of nano Ni and ball pitch in the matrix, Al{sub 2}O{sub 3}-SiC-C castable composites were prepared with the anti-oxidant addition of silicon. The results indicate that the high temperature of the Al{sub 2}O{sub 3}-SiC-C castable composites can be increased by above 42%, and the thermal shock resistance can be enhanced by above 20% because the ball pitch is carbonized and releases C{sub x}H{sub y} vapor, which can be pyrolized to carbon atoms and subsequently deposited into carbon fibers under the catalyst action. The starting temperature of carbon fiber growth is approximately 900 °C, and their diameter and aspect ratio can increase with the rising temperature. The in-situ generation of carbon fibers in Al{sub 2}O{sub 3}-SiC-C castable composites can significantly improve the fibers’ thermo-mechanical properties.

  2. Boron nitride converted carbon fiber

    SciTech Connect

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  3. Voltammetric detection of biological molecules using chopped carbon fiber.

    PubMed

    Sugawara, Kazuharu; Yugami, Asako; Kojima, Akira

    2010-01-01

    Voltammetric detection of biological molecules was carried out using chopped carbon fibers produced from carbon fiber reinforced plastics that are biocompatible and inexpensive. Because chopped carbon fibers normally are covered with a sizing agent, they are difficult to use as an electrode. However, when the surface of a chopped carbon fiber was treated with ethanol and hydrochloric acid, it became conductive. To evaluate the functioning of chopped carbon fibers, voltammetric measurements of [Fe(CN)(6)](3-) were carried out. Redoxes of FAD, ascorbic acid and NADH as biomolecules were recorded using cyclic voltammetry. The sizing agents used to bundle the fibers were epoxy, polyamide and polyurethane resins. The peak currents were the greatest when using the chopped carbon fibers that were created with epoxy resins. When the electrode response of the chopped carbon fibers was compared with that of a glassy carbon electrode, the peak currents and the reversibility of the electrode reaction were sufficient. Therefore, the chopped carbon fibers will be useful as disposable electrodes for the sensing of biomolecules.

  4. CARBON FIBER COMPOSITES IN HIGH VOLUME

    SciTech Connect

    Warren, Charles David; Das, Sujit; Jeon, Dr. Saeil

    2014-01-01

    Vehicle lightweighting represents one of several design approaches that automotive and heavy truck manufacturers are currently evaluating to improve fuel economy, lower emissions, and improve freight efficiency (tons-miles per gallon of fuel). With changes in fuel efficiency and environmental regulations in the area of transportation, the next decade will likely see considerable vehicle lightweighting throughout the ground transportation industry. Greater use of carbon fiber composites and light metals is a key component of that strategy. This paper examines the competition between candidate materials for lightweighting of heavy vehicles and passenger cars. A 53-component, 25 % mass reduction, body-in-white cost analysis is presented for each material class, highlighting the potential cost penalty for each kilogram of mass reduction and then comparing the various material options. Lastly, as the cost of carbon fiber is a major component of the elevated cost of carbon fiber composites, a brief look at the factors that influence that cost is presented.

  5. Comparison of carbon fiber and stainless steel root canal posts.

    PubMed

    Purton, D G; Payne, J A

    1996-02-01

    This in vitro study compared physical properties of root canal posts made of carbon fiber-reinforced epoxy resin with those of stainless steel posts. Three-point bending tests were used to derive the transverse modulus of elasticity of the posts. Resin composite cores on the posts were subjected to tensile forces to test the bonds between the cores and posts. Carbon fiber posts appeared to have adequate rigidity for their designed purpose. The bond strength of the resin composite cores to the carbon fiber posts was significantly less than that to the stainless steel posts.

  6. Global Carbon Fiber Composites. Supply Chain Competitiveness Analysis

    SciTech Connect

    Das, Sujit; Warren, Joshua A.; West, Devin; Schexnayder, Susan M.

    2016-05-01

    The objective of this study is to identify key opportunities in the carbon fiber (CF) supply chain where resources and investments can help advance the clean energy economy. The report focuses on four application areas—wind energy, aerospace, automotive, and pressure vessels—that top the list of industries using CF and carbon fiber reinforced polymers (CFRP) and are particularly relevant to the mission of U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (DOE EERE). For each of the four application areas, the report addresses the supply and demand trends within that sector, supply chain, and costs of carbon fiber and components.

  7. High performance carbon fibers from very high molecular weight polyacrylonitrile precursors

    SciTech Connect

    Morris, E. Ashley; Weisenberger, Matthew C.; Abdallah, Mohamed G.; Vautard, Frederic; Grappe, Hippolyte A.; Ozcan, Soydan; Paulauskas, Felix L.; Eberle, Cliff; Jackson, David C.; Mecham, Sue J.; Naskar, Amit K.

    2016-02-02

    In this study, carbon fibers are unique reinforcing agents for lightweight composite materials due to their outstanding mechanical properties and low density. Current technologies are capable of producing carbon fibers with 90-95% of the modulus of perfect graphite (~1025 GPa). However, these same carbon fibers possess less than 10% of the theoretical carbon fiber strength, estimated to be about 100 GPa.[1] Indeed, attempts to increase carbon fiber rigidity results in lower breaking strength. To develop advanced carbon fibers with both very high strength and modulus demands a new manufacturing methodology. Here, we report a method of manufacturing high strength, very high modulus carbon fibers from a very high molecular weight (VHMW) polyacrylonitrile (PAN) precursor without the use of nanomaterial additives such as nucleating or structure-templating agents, as have been used by others.[2,3

  8. High performance carbon fibers from very high molecular weight polyacrylonitrile precursors

    DOE PAGES

    Morris, E. Ashley; Weisenberger, Matthew C.; Abdallah, Mohamed G.; ...

    2016-02-02

    In this study, carbon fibers are unique reinforcing agents for lightweight composite materials due to their outstanding mechanical properties and low density. Current technologies are capable of producing carbon fibers with 90-95% of the modulus of perfect graphite (~1025 GPa). However, these same carbon fibers possess less than 10% of the theoretical carbon fiber strength, estimated to be about 100 GPa.[1] Indeed, attempts to increase carbon fiber rigidity results in lower breaking strength. To develop advanced carbon fibers with both very high strength and modulus demands a new manufacturing methodology. Here, we report a method of manufacturing high strength, verymore » high modulus carbon fibers from a very high molecular weight (VHMW) polyacrylonitrile (PAN) precursor without the use of nanomaterial additives such as nucleating or structure-templating agents, as have been used by others.[2,3]« less

  9. CTE Measurements of Carbon Fibers in ESEM

    NASA Technical Reports Server (NTRS)

    Effinger, Michael; Ochoa, Ozden; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The strong appeal of carbon fiber reinforced ceramic matrix and carbon-carbon composites arises from their promising high temperature performance within laboratory-simulated nozzle, leading edge and combustor environments. The main drawback in these systems are two fold; namely oxidation affinity and CTE mismatch. To date the emphasis has been on axial CTE mismatch with the push on estimating (component) laminate level data. However, in heterogeneous and anisotropic systems, all failure mechanisms are at micro or nano scales. This paper will report plans and progress on single carbon fibers efforts in order to develop its temperature dependent, anisotropic thermophysical and thermomechanical properties using combination of x-ray spectroscopy and environmental scanning electron microscopy to capture circumferential expansion from 20-900 C in within the SEM chamber. Surface roughness measurements were also determined. Crystallinity was also determined by the quality of the electron diffraction (ED) patterns.

  10. Carbon-fiber technology

    NASA Technical Reports Server (NTRS)

    Hansen, C. F.; Parker, J. A.

    1980-01-01

    The state of the art of PAN based carbon fiber manufacture and the science of fiber behavior is surveyed. A review is given of the stabilization by oxidation and the subsequent carbonization of fibers, of the apparent structure of fibers deduced from scanning electron microscopy, from X-ray scattering, and from similarities with soft carbons, and of the known relations between fiber properties and heat treatment temperature. A simplified model is invoked to explain the electrical properties of fibers and recent quantum chemical calculations on atomic clusters are used to elucidate some aspects of fiber conductivity. Some effects of intercalation and oxidative modification of finished fibers are summarized.

  11. Nanotailored Carbon Fibers

    DTIC Science & Technology

    2009-06-07

    Chae, Han Gi, Ph.D. Nano Engineered Materials Corporation 2349 Lake Forest Trail Lawrenceville, GA 30043 Air Force Office of Scientific...0065, AF08‐T028  Nanotailored Carbon Fibers  Nano  Engineered Materials Corp    Nanotailored Carbon Fibers (STTR Phase I final technical report...14   FA9550‐08‐C‐0065, AF08‐T028  Nanotailored Carbon Fibers  Nano

  12. Global Carbon Fiber Composites Supply Chain Competitiveness Analysis

    SciTech Connect

    Das, Sujit; Warren, Josh; West, Devin; Schexnayder, Susan M.

    2016-05-01

    This study identifies key opportunities in the carbon fiber supply chain where the United States Department of Energy's Office of Energy Efficiency and Renewable Energy resources and investments can help the United States achieve or maintain a competitive advantage. The report focuses on four application areas--wind energy, aerospace, automotive, and pressure vessels--that top the list of industries using carbon fiber and carbon fiber reinforced polymers and are also particularly relevant to EERE's mission. For each of the four application areas, the report addresses the supply and demand trends within that sector, supply chain, and costs of carbon fiber and components, all contributing to a competitiveness assessment that addresses the United States' role in future industry growth. This report was prepared by researchers at Oak Ridge National Laboratory and the University of Tennessee for the Clean Energy Manufacturing Analysis Center.

  13. The surface properties of carbon fibers and their adhesion to organic polymers

    NASA Technical Reports Server (NTRS)

    Bascom, W. D.; Drzal, L. T.

    1987-01-01

    The state of knowledge of the surface properties of carbon fibers is reviewed, with emphasis on fiber/matrix adhesion in carbon fiber reinforced plastics. Subjects treated include carbon fiber structure and chemistry, techniques for the study of the fiber surface, polymer/fiber bond strength and its measurement, variations in polymer properties in the interphase, and the influence of fiber matrix adhesion on composite mechanical properties. Critical issues are summarized and search recommendations are made.

  14. Carbon Fiber Risk Analysis. [conference

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The scope and status of the effort to assess the risks associated with the accidental release of carbon/graphite fibers from civil aircraft is presented. Vulnerability of electrical and electronic equipment to carbon fibers, dispersal of carbon fibers, effectiveness of filtering systems, impact of fiber induced failures, and risk methodology are among the topics covered.

  15. Carbon Fiber Composites

    NASA Technical Reports Server (NTRS)

    1997-01-01

    HyComp(R), Inc. development a line of high temperature carbon fiber composite products to solve wear problems in the harsh environment of steel and aluminum mills. WearComp(R), self-lubricating composite wear liners and bushings, combines carbon graphite fibers with a polyimide binder. The binder, in conjunction with the fibers, provides the slippery surface, one that demands no lubrication, yet wears at a very slow rate. WearComp(R) typically lasts six to ten times longer than aluminum bronze. Unlike bronze, WearComp polishes the same surface and imparts a self-lube film for years of service. It is designed for continuous operation at temperatures of 550 degrees Fahrenheit and can operate under high compressive loads.

  16. Improved method for producing metal-reinforced ceramics

    NASA Technical Reports Server (NTRS)

    Landingham, R. L.

    1972-01-01

    Vacuum impregnation process produces metal-reinforced ceramics with only 3 percent void space volumes. Method may be used to produce metal-reinforced ceramics for high temperature or structural applications such as furnace supports and armor.

  17. Patterned functional carbon fibers from polyethylene

    SciTech Connect

    Hunt, Marcus A; Saito, Tomonori; Brown, Rebecca H; Kumbhar, Amar S; Naskar, Amit K

    2012-01-01

    Patterned, continuous carbon fibers with controlled surface geometry were produced from a novel melt-processible carbon precursor. This portends the use of a unique technique to produce such technologically innovative fibers in large volume for important applications. The novelties of this technique include ease of designing and fabricating fibers with customized surface contour, the ability to manipulate filament diameter from submicron scale to a couple of orders of magnitude larger scale, and the amenable porosity gradient across the carbon wall by diffusion controlled functionalization of precursor. The geometry of fiber cross-section was tailored by using bicomponent melt-spinning with shaped dies and controlling the melt-processing of the precursor polymer. Circular, trilobal, gear-shaped hollow fibers, and solid star-shaped carbon fibers of 0.5 - 20 um diameters, either in self-assembled bundle form, or non-bonded loose filament form, were produced by carbonizing functionalized-polyethylene fibers. Prior to carbonization, melt-spun fibers were converted to a char-forming mass by optimizing the sulfonation on polyethylene macromolecules. The fibers exhibited distinctly ordered carbon morphologies at the outside skin compared to the inner surface or fiber core. Such order in carbon microstructure can be further tuned by altering processing parameters. Partially sulfonated polyethylene-derived hollow carbon fibers exhibit 2-10 fold surface area (50-500 m2/g) compared to the solid fibers (10-25 m2/g) with pore sizes closer to the inside diameter of the filaments larger than the sizes on the outer layer. These specially functionalized carbon fibers hold promise for extraordinary performance improvements when used, for example, as composite reinforcements, catalyst support media, membranes for gas separation, CO2 sorbents, and active electrodes and current collectors for energy storage applications.

  18. Development of the experimental procedure to examine the response of carbon fiber-reinforced polymer composites subjected to a high-intensity pulsed electric field and low-velocity impact.

    PubMed

    Hart, Robert J; Zhupanska, Olesya I

    2016-01-01

    A new fully automated experimental setup has been developed to study the response of carbon fiber reinforced polymer (CFRP) composites subjected to a high-intensity pulsed electric field and low-velocity impact. The experimental setup allows for real-time measurements of the pulsed electric current, voltage, impact load, and displacements on the CFRP composite specimens. The setup includes a new custom-built current pulse generator that utilizes a bank of capacitor modules capable of producing a 20 ms current pulse with an amplitude of up to 2500 A. The setup enabled application of the pulsed current and impact load and successfully achieved coordination between the peak of the current pulse and the peak of the impact load. A series of electrical, impact, and coordinated electrical-impact characterization tests were performed on 32-ply IM7/977-3 unidirectional CFRP composites to assess their ability to withstand application of a pulsed electric current and determine the effects of the pulsed current on the impact response. Experimental results revealed that the electrical resistance of CFRP composites decreased with an increase in the electric current magnitude. It was also found that the electrified CFRP specimens withstood higher average impact loads compared to the non-electrified specimens.

  19. Development of the experimental procedure to examine the response of carbon fiber-reinforced polymer composites subjected to a high-intensity pulsed electric field and low-velocity impact

    NASA Astrophysics Data System (ADS)

    Hart, Robert J.; Zhupanska, Olesya I.

    2016-01-01

    A new fully automated experimental setup has been developed to study the response of carbon fiber reinforced polymer (CFRP) composites subjected to a high-intensity pulsed electric field and low-velocity impact. The experimental setup allows for real-time measurements of the pulsed electric current, voltage, impact load, and displacements on the CFRP composite specimens. The setup includes a new custom-built current pulse generator that utilizes a bank of capacitor modules capable of producing a 20 ms current pulse with an amplitude of up to 2500 A. The setup enabled application of the pulsed current and impact load and successfully achieved coordination between the peak of the current pulse and the peak of the impact load. A series of electrical, impact, and coordinated electrical-impact characterization tests were performed on 32-ply IM7/977-3 unidirectional CFRP composites to assess their ability to withstand application of a pulsed electric current and determine the effects of the pulsed current on the impact response. Experimental results revealed that the electrical resistance of CFRP composites decreased with an increase in the electric current magnitude. It was also found that the electrified CFRP specimens withstood higher average impact loads compared to the non-electrified specimens.

  20. Oxidation of Carbon Fibers in Water Vapor Studied

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.

    2003-01-01

    T-300 carbon fibers (BP Amoco Chemicals, Greenville, SC) are a common reinforcement for silicon carbide composite materials, and carbon-fiber-reinforced silicon carbide composites (C/SiC) are proposed for use in space propulsion applications. It has been shown that the time to failure for C/SiC in stressed oxidation tests is directly correlated with the fiber oxidation rate (ref. 1). To date, most of the testing of these fibers and composites has been conducted in oxygen or air environments; however, many components for space propulsion, such as turbopumps, combustors, and thrusters, are expected to operate in hydrogen and water vapor (H2/H2O) environments with very low oxygen contents. The oxidation rate of carbon fibers in conditions representative of space propulsion environments is, therefore, critical for predicting component lifetimes for real applications. This report describes experimental results that demonstrate that, under some conditions, lower oxidation rates of carbon fibers are observed in water vapor and H2/H2O environments than are found in oxygen or air. At the NASA Glenn Research Center, the weight loss of the fibers was studied as a function of water pressure, temperature, and gas velocity. The rate of carbon fiber oxidation was determined, and the reaction mechanism was identified.

  1. Biomechanical analysis of a new carbon fiber/flax/epoxy bone fracture plate shows less stress shielding compared to a standard clinical metal plate.

    PubMed

    Bagheri, Zahra S; Tavakkoli Avval, Pouria; Bougherara, Habiba; Aziz, Mina S R; Schemitsch, Emil H; Zdero, Radovan

    2014-09-01

    Femur fracture at the tip of a total hip replacement (THR), commonly known as Vancouver B1 fracture, is mainly treated using rigid metallic bone plates which may result in "stress shielding" leading to bone resorption and implant loosening. To minimize stress shielding, a new carbon fiber (CF)/Flax/Epoxy composite plate has been developed and biomechanically compared to a standard clinical metal plate. For fatigue tests, experiments were done using six artificial femurs cyclically loaded through the femoral head in axial compression for four stages: Stage 1 (intact), stage 2 (after THR insertion), stage 3 (after plate fixation of a simulated Vancouver B1 femoral midshaft fracture gap), and stage 4 (after fracture gap healing). For fracture fixation, one group was fitted with the new CF/Flax/Epoxy plate (n = 3), whereas another group was repaired with a standard clinical metal plate (Zimmer, Warsaw, IN) (n = 3). In addition to axial stiffness measurements, infrared thermography technique was used to capture the femur and plate surface stresses during the testing. Moreover, finite element analysis (FEA) was performed to evaluate the composite plate's axial stiffness and surface stress field. Experimental results showed that the CF/Flax/Epoxy plated femur had comparable axial stiffness (fractured = 645 ± 67 N/mm; healed = 1731 ± 109 N/mm) to the metal-plated femur (fractured = 658 ± 69 N/mm; healed = 1751 ± 39 N/mm) (p = 1.00). However, the bone beneath the CF/Flax/Epoxy plate was the only area that had a significantly higher average surface stress (fractured = 2.10 ± 0.66 MPa; healed = 1.89 ± 0.39 MPa) compared to bone beneath the metal plate (fractured = 1.18 ± 0.93 MPa; healed = 0.71 ± 0.24 MPa) (p < 0.05). FEA bone surface stresses yielded peak of 13 MPa at distal epiphysis (stage 1), 16 MPa at distal epiphysis (stage 2), 85 MPa for composite and 129

  2. Polishing and coating carbon fiber-reinforced carbon composites with a carbon-titanium layer enhances adhesion and growth of osteoblast-like MG63 cells and vascular smooth muscle cells in vitro.

    PubMed

    Bacáková, L; Starý, V; Kofronová, O; Lisá, V

    2001-03-15

    Carbon fiber-reinforced carbon composites (CFRC) are considered to be promising materials for orthopedic and dental surgery. Their mechanical properties can be tailored to be similar to those of bone, and their chemical composition (close to pure carbon) promises that they will be tolerated well by the surrounding tissue. In this study, CFRC composites were fabricated from phenolic resin and unidirectionally oriented Torayca carbon fibers by carbonization (1000 degrees C) and graphitization (2500 degrees C). The material then was cut with a diamond saw into sheets of 8 x 10 x 3 mm, and the upper surface was polished by colloidal SiO2 and/or covered with a carbon-titanium (C:Ti) layer (3.3 microm) using the plasma-enhanced physical vapor deposition method. Three different kinds of modified samples were prepared: polished only, covered only, and polished + covered. Untreated samples served as a control. The surface roughness of these samples, measured by a Talysurf profilometer, decreased significantly after polishing but usually did not decrease after coating with a C:Ti layer. On all three modified surfaces, human osteoblast-like cells of the MG63 line and rat vascular smooth muscle cells (both cultured in a Dulbecco's minimum essential medium with 10% fetal bovine serum) adhered at higher numbers (by 21-87% on day 1 after seeding) and exhibited a shorter population doubling time (by 13-40%). On day 4 after seeding, these cells attained higher population densities (by 61-378%), volume (by 18-37%), and protein content (by 16-120%). These results were more pronounced in VSMC than in MG63 cells and in both groups of C:Ti-covered samples than in the polished only samples. The release of carbon particles from the CFRC composites was significantly decreased--by 8 times in the polished only, 24 times in the covered only, and 42 times in the polished + covered samples. These results show that both polishing and carbon-titanium covering significantly improve the

  3. Carbon Fiber Risk Analysis: Conclusions

    NASA Technical Reports Server (NTRS)

    Huston, R. J.

    1979-01-01

    It was concluded that preliminary estimates indicate that the public risk due to accidental release of carbon fiber from air transport aircraft is small. It was also concluded that further work is required to increase confidence in these estimates.

  4. Fibrous Carbon-Metallic Materials and a Method of Manufacturing Carbon-Metallic Fibrous Materials,

    DTIC Science & Technology

    1983-05-12

    fibers associated with a carbon binder and an additive in the form of boron nitride, boron silicide and heat-resistant metal borides. On the other hand...Great Britain patent description No. 1302331 refers to metal parts reinforced by carbon fibers with a galvanized coating or as a result of a...carbon fibers, a carbonaceous binder and additives such as boron, niobium , silicon, tantalum and others. United States patent deocription No. 3622283

  5. Interfacial Microstructure and Enhanced Mechanical Properties of Carbon Fiber Composites Caused by Growing Generation 1-4 Dendritic Poly(amidoamine) on a Fiber Surface.

    PubMed

    Gao, Bo; Zhang, Ruliang; Gao, Fucheng; He, Maoshuai; Wang, Chengguo; Liu, Lei; Zhao, Lifen; Cui, Hongzhi

    2016-08-23

    In an attempt to improve the mechanical properties of carbon fiber composites, propagation of poly(amidoamine) (PAMAM) dendrimers by in situ polymerization on a carbon fiber surface was performed. During polymerization processes, PAMAM was grafted on carbon fiber by repeated Michael addition and amidation reactions. The changes in surface microstructure and the chemical composition of carbon fibers before and after modification were investigated by atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. All the results indicated that PAMAM was successfully grown on the carbon fiber surface. Such propagation could significantly increase the surface roughness and introduce sufficient polar groups onto the carbon fiber surface, enhancing the surface wettability of carbon fiber. The fractured surface of carbon fiber-reinforced composites showed a great enhancement of interfacial adhesion. Compared with those of desized fiber composites, the interlaminar shear strength and interfacial shear strength of PAMAM/fiber-reinforced composites showed increases of 55.49 and 110.94%, respectively.

  6. Nanowire modified carbon fibers for enhanced electrical energy storage

    NASA Astrophysics Data System (ADS)

    Shuvo, Mohammad Arif Ishtiaque; (Bill) Tseng, Tzu-Liang; Ashiqur Rahaman Khan, Md.; Karim, Hasanul; Morton, Philip; Delfin, Diego; Lin, Yirong

    2013-09-01

    The study of electrochemical super-capacitors has become one of the most attractive topics in both academia and industry as energy storage devices because of their high power density, long life cycles, and high charge/discharge efficiency. Recently, there has been increasing interest in the development of multifunctional structural energy storage devices such as structural super-capacitors for applications in aerospace, automobiles, and portable electronics. These multifunctional structural super-capacitors provide structures combining energy storage and load bearing functionalities, leading to material systems with reduced volume and/or weight. Due to their superior materials properties, carbon fiber composites have been widely used in structural applications for aerospace and automotive industries. Besides, carbon fiber has good electrical conductivity which will provide lower equivalent series resistance; therefore, it can be an excellent candidate for structural energy storage applications. Hence, this paper is focused on performing a pilot study for using nanowire/carbon fiber hybrids as building materials for structural energy storage materials; aiming at enhancing the charge/discharge rate and energy density. This hybrid material combines the high specific surface area of carbon fiber and pseudo-capacitive effect of metal oxide nanowires, which were grown hydrothermally in an aligned fashion on carbon fibers. The aligned nanowire array could provide a higher specific surface area that leads to high electrode-electrolyte contact area thus fast ion diffusion rates. Scanning Electron Microscopy and X-Ray Diffraction measurements are used for the initial characterization of this nanowire/carbon fiber hybrid material system. Electrochemical testing is performed using a potentio-galvanostat. The results show that gold sputtered nanowire carbon fiber hybrid provides 65.9% higher energy density than bare carbon fiber cloth as super-capacitor.

  7. Carbon Fiber from Biomass

    SciTech Connect

    Milbrandt, Anelia; Booth, Samuel

    2016-09-01

    Carbon fiber (CF), known also as graphite fiber, is a lightweight, strong, and flexible material used in both structural (load-bearing) and non-structural applications (e.g., thermal insulation). The high cost of precursors (the starting material used to make CF, which comes predominately from fossil sources) and manufacturing have kept CF a niche market with applications limited mostly to high-performance structural materials (e.g., aerospace). Alternative precursors to reduce CF cost and dependence on fossil sources have been investigated over the years, including biomass-derived precursors such as rayon, lignin, glycerol, and lignocellulosic sugars. The purpose of this study is to provide a comprehensive overview of CF precursors from biomass and their market potential. We examine the potential CF production from these precursors, the state of technology and applications, and the production cost (when data are available). We discuss their advantages and limitations. We also discuss the physical properties of biomass-based CF, and we compare them to those of polyacrylonitrile (PAN)-based CF. We also discuss manufacturing and end-product considerations for bio-based CF, as well as considerations for plant siting and biomass feedstock logistics, feedstock competition, and risk mitigation strategies. The main contribution of this study is that it provides detailed technical and market information about each bio-based CF precursor in one document while other studies focus on one precursor at a time or a particular topic (e.g., processing). Thus, this publication allows for a comprehensive view of the CF potential from all biomass sources and serves as a reference for both novice and experienced professionals interested in CF production from alternative sources.

  8. X-ray-cured carbon-fiber composites for vehicle use

    NASA Astrophysics Data System (ADS)

    Herer, Arnold; Galloway, Richard A.; Cleland, Marshall R.; Berejka, Anthony J.; Montoney, Daniel; Dispenza, Dan; Driscoll, Mark

    2009-07-01

    Carbon-fiber-reinforced composites were cured in molds using X-rays derived from a high-energy, high-current electron beam. X-rays could penetrate the mold walls as well as the fiber reinforcements and polymerize a matrix system. Matrix materials made from modified epoxy-acrylates were tailored to suitably low viscosity so that fiber wetting and adhesion could be attained. Techniques similar to vacuum-assisted resin transfer molding (VARTM) and conventional vacuum bagging of wet lay-ups were used. Inexpensive reinforced polyester molds were used to fabricate vehicle fenders. Moderately low-dose X-ray exposure was sufficient to attain functional properties, such as resistance to heat distortion at temperatures as high as 180 °C. The matrix system contained an impact additive which imparted toughness to the cured articles. "Class A" high gloss surfaces were achieved. Thermo-analytical techniques were used on small-sized samples of X-ray-cured matrix materials to facilitate selection of a system for use in making prototypes of vehicle components. X-rays-penetrated metal pieces that were placed within layers of carbon-fiber twill, which were cured and bonded into a structure that could be mechanically attached without concern over fracturing the composite. X-ray curing is a low temperature process that eliminates residual internal stresses which are imparted by conventional thermo-chemical curing processes.

  9. On the nature of interface of carbon nanotube coated carbon fibers with different polymers

    NASA Astrophysics Data System (ADS)

    Singh Bedi, Harpreet; Padhee, Srikant S.; Agnihotri, Prabhat K.

    2016-07-01

    Experimental investigations are carried out to analyse the wetting behaviour of carbon nanotube (CNT) coated carbon fiber to determine their suitability to process carbon nanotube coated carbon fiber/polymer multiscale composites for structural applications. To overcome the problem of agglomeration, CNTs are grown directly on the surface of carbon fibers as well as fabric using thermal chemical vapour deposition (CVD) technique. The term multiscale is used because different reinforcement mechanisms operate at the scale of long fibers and CNTs which are of few micrometers in length. The load carrying capacity of these multiscale composites critically depends on the efficiency and extent of load transfer from low strength matrix to high strength fiber which in turn depends on the interfacial strength between CNT coated carbon fiber and polymer matrix. A systematic analysis of wetting behaviour of CNT coated carbon fiber with epoxy and polyester matrix is carried out in this study. It is shown that CNT coated carbon fibers as well as fabric show better wettability with epoxy matrix as compared to polyester matrix. This results in stronger interface of CNT coated carbon fiber with epoxy as compared to polyester in multiscale composite system. A similar observation is made in nanoindentation testing of single fiber multiscale composites processed with epoxy and polyester matrix. In addition, it is observed that wettability, interfacial strength and average properties of CNT coated carbon fiber/polymer composites are a function of CNT density on the surface of carbon fibers.

  10. Interfacial microstructure and properties of carbon fiber composites modified with graphene oxide.

    PubMed

    Zhang, Xiaoqing; Fan, Xinyu; Yan, Chun; Li, Hongzhou; Zhu, Yingdan; Li, Xiaotuo; Yu, Liping

    2012-03-01

    The performance of carbon fiber-reinforced composites is dependent to a great extent on the properties of fiber-matrix interface. To improve the interfacial properties in carbon fiber/epoxy composites, we directly introduced graphene oxide (GO) sheets dispersed in the fiber sizing onto the surface of individual carbon fibers. The applied graphite oxide, which could be exfoliated to single-layer GO sheets, was verified by atomic force microscope (AFM). The surface topography of modified carbon fibers and the distribution of GO sheets in the interfacial region of carbon fibers were detected by scanning electron microscopy (SEM). The interfacial properties between carbon fiber and matrix were investigated by microbond test and three-point short beam shear test. The tensile properties of unidirectional (UD) composites were investigated in accordance with ASTM standards. The results of the tests reveal an improved interfacial and tensile properties in GO-modified carbon fiber composites. Furthermore, significant enhancement of interfacial shear strength (IFSS), interlaminar shear strength (ILSS), and tensile properties was achieved in the composites when only 5 wt % of GO sheets introduced in the fiber sizing. This means that an alternative method for improving the interfacial and tensile properties of carbon fiber composites by controlling the fiber-matrix interface was developed. Such multiscale reinforced composites show great potential with their improved mechanical performance to be likely applied in the aerospace and automotive industries.

  11. Property and Shape Modulation of Carbon Fibers Using Lasers.

    PubMed

    Blaker, Jonny J; Anthony, David B; Tang, Guang; Shamsuddin, Siti-Ros; Kalinka, Gerhard; Weinrich, Malte; Abdolvand, Amin; Shaffer, Milo S P; Bismarck, Alexander

    2016-06-29

    An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes.

  12. Aligning carbon fibers in micro-extruded composite ink

    NASA Astrophysics Data System (ADS)

    Mahajan, Chaitanya G.

    Direct write processes include a wide range of additive manufacturing techniques with the ability to fabricate structures directly onto planar and non-planar surfaces. Most additive manufacturing techniques use unreinforced polymers to produce parts. By adding carbon fiber as a reinforcing material, properties such as mechanical strength, electrical conductivity, and thermal conductivity can be enhanced. Carbon fibers can be long and continuous, or short and discontinuous. The strength of carbon fiber composite parts is greatly increased when the fibers are preferentially aligned. This research focuses on increasing the strength of additively manufactured parts reinforced using discontinuous carbon fibers that have been aligned during the micro extrusion process. A design of experiments (DOE) approach was used to identify significant process parameters affecting fiber alignment. Factors such as the length of carbon fibers, nozzle diameter, fiber loading fraction, air pressure, translational speed and standoff distance were considered. A two dimensional Fast Fourier Transform (2D FFT) was used to quantify the degree of fiber alignment in the extruded composite inks. ImageJ software supported by an oval profile plugin was used with micrographs of printed samples to obtain the carbon fiber alignment values. The optimal value for the factors was derived by identifying the significant main and interaction effects. Based on the results of the DOE, tensile test samples were printed with fibers aligned parallel and perpendicular to the tensile axis. A standard test method for tensile properties of plastic revealed that the extruded parts with fibers aligned along the tensile axis were better in tensile strength and modulus.

  13. Rapid Fabrication of Carbide Matrix/Carbon Fiber Composites

    NASA Technical Reports Server (NTRS)

    Williams, Brian E.; Bernander, Robert E.

    2007-01-01

    Composites of zirconium carbide matrix material reinforced with carbon fibers can be fabricated relatively rapidly in a process that includes a melt infiltration step. Heretofore, these and other ceramic matrix composites have been made in a chemical vapor infiltration (CVI) process that takes months. The finished products of the CVI process are highly porous and cannot withstand temperatures above 3,000 F (approx.1,600 C). In contrast, the melt-infiltration-based process takes only a few days, and the composite products are more nearly fully dense and have withstood temperatures as high as 4,350 F (approx.2,400 C) in a highly oxidizing thrust chamber environment. Moreover, because the melt- infiltration-based process takes much less time, the finished products are expected to cost much less. Fabrication begins with the preparation of a carbon fiber preform that, typically, is of the size and shape of a part to be fabricated. By use of low-temperature ultraviolet-enhanced chemical vapor deposition, the carbon fibers in the preform are coated with one or more interfacial material(s), which could include oxides. The interfacial material helps to protect the fibers against chemical attack during the remainder of the fabrication process and against oxidation during subsequent use; it also enables slippage between the fibers and the matrix material, thereby helping to deflect cracks and distribute loads. Once the fibers have been coated with the interfacial material, the fiber preform is further infiltrated with a controlled amount of additional carbon, which serves as a reactant for the formation of the carbide matrix material. The next step is melt infiltration. The preform is exposed to molten zirconium, which wicks into the preform, drawn by capillary action. The molten metal fills most of the interstices of the preform and reacts with the added carbon to form the zirconium carbide matrix material. The zirconium does not react with the underlying fibers because they

  14. Fatigue Life Prediction of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures. Part II: Experimental Comparisons

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    This paper follows on from the earlier study (Part I) which investigated the fatigue behavior of unidirectional, cross-ply and 2.5D C/SiC composites at room and elevated temperatures. In this paper, a micromechanics approach to predict the fatigue life S-N curves of fiber-reinforced CMCs has been developed considering the fatigue damage mechanism of interface wear or interface oxidation. Upon first loading to fatigue peak stress, matrix multicracking and fiber/matrix interface debonding occur. The two-parameter Weibull model is used to describe fibers strength distribution. The stress carried by broken and intact fibres on the matrix crack plane under fatigue loading is determined based on the Global Load Sharing (GLS) criterion. The fibres failure probabilities under fatigue loading considering the degradation of interface shear stress and fibres strength have been obtained. When the broken fibres fraction approaches critical value, the composite would fatigue fail. The fatigue life S-N curves of unidirectional, cross-ply and 2.5D C/SiC composites at room and elevated temperatures have been predicted. The predicted results agreed with experimental data.

  15. Carbon fiber study

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A coordinated Federal Government action plan for dealing with the potential problems arising from the increasing use of graphite fiber reinforced composite materials in both military and civilian applications is presented. The required dissemination of declassified information and an outline of government actions to minimize the social and economic consequences of proliferated composite materials applications were included.

  16. Development of carbon fiber-based piezoresistive linear sensing technique

    NASA Astrophysics Data System (ADS)

    Yang, Caiqian; Wu, Zhishen; Huang, Huang

    2009-03-01

    In this paper, the development of carbon fiber-based piezoresistive linear sensing technique and its application in civil engineering structures is studied and summarized. The sensing mechanism is based on the electrical conductivity and piezoresistivity of different types of carbon fibers. Firstly, the influences of values of signal currents and temperature on the sensing properties are studied to decide the suitable sensing current. Then, the linear temperature and strain sensing feasibility of different types of carbon fibers is addressed and discussed. Finally, the application of this kind of sensors is studied in monitoring the health of reinforced concrete (RC) and prestressed concrete (PC) structures. A good linearity of fractional change in electrical resistance (ER) (ΔR/R0)-strain and &DeltaR/R0-temperature is demonstrated. The &DeltaR/R0-strain and &DeltaR/R0-temperature curves of CFRP/HCFRP sensors can be well fitted with a line with a correlation coefficient larger than 0.978. All these reveal that carbon fibers reinforced polymer (CFRP) can be used as both piezoresistive linear strain and temperature sensors.

  17. Liquid crystal polyester-carbon fiber composites

    NASA Technical Reports Server (NTRS)

    Chung, T. S.

    1984-01-01

    Liquid crystal polymers (LCP) have been developed as a thermoplastic matrix for high performance composites. A successful melt impregnation method has been developed which results in the production of continuous carbon fiber (CF) reinforced LCP prepreg tape. Subsequent layup and molding of prepreg into laminates has yielded composites of good quality. Tensile and flexural properties of LCP/CF composites are comparable to those of epoxy/CF composites. The LCP/CF composites have better impact resistance than the latter, although epoxy/CF composites possess superior compression and shear strength. The LCP/CF composites have good property retention until 200 F (67 % of room temperature value). Above 200 F, mechanical properties decrease significantly. Experimental results indicate that the poor compression and shear strength may be due to the poor interfacial adhesion between the matrix and carbon fiber as adequate toughness of the LCP matrix. Low mechanical property retention at high temperatures may be attributable to the low beta-transition temperature (around 80 C) of the LCP matrix material.

  18. Compression Molding of CFRTP Used with Carbon Fiber Extracted from CFRP Waste

    NASA Astrophysics Data System (ADS)

    Kimura, Teruo; Ino, Haruhiro; Nishida, Yuichi; Aoyama, Naoki; Shibata, Katsuji

    This study investigated a compression molding method of carbon fiber reinforced thermoplastics (CFRTP) made of carbon fiber extracted from CFRP waste. The short carbon fibers were mixed with polyester fibers using a papermaking method to make the preform sheet of compression molding. The waste obtained from a textile water jet loom was used as a matrix material. The setting speed of each fiber during the papermaking process was regulated by using a dispersing agent to obtain the good dispersion of each fiber. Laminated preform sheets combined with polyester fibers and carbon fibers were compressed with heating at 300°C and then the polyester fiber was melted as a matrix material. It was cleared from the experimental results that the mechanical properties of molded CFRTP largely depends on both the fiber dispersion and the content of carbon fiber in the preform.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  20. Hierarchical nanostructured noble metal/metal oxide/graphene-coated carbon fiber: in situ electrochemical synthesis and use as microelectrode for real-time molecular detection of cancer cells.

    PubMed

    Abdurhman, Abduraouf Alamer Mohamed; Zhang, Yan; Zhang, Guoan; Wang, Shuai

    2015-10-01

    We report the design and fabrication of a new type of nanohybrid microelectrode based on a hierarchical nanostructured Au/MnO2/graphene-modified carbon fiber (CF) via in situ electrochemical synthesis, which leads to better structural integration of different building blocks into the CF microelectrode. Our finding demonstrates that wrapping CF with graphene nanosheets has dramatically increased the surface area and electrical conductivity of the CF microelectrode. The subsequent template-free electrodeposition of MnO2 on graphene-wrapped CF gives rise to a porous nanonest architecture built up from twisted and intersectant MnO2 nanowires, which serves as an ideal substrate for the direct growth of Au nanoparticles. Owing to the structural merit and synergy effect between different components, the hierarchical nanostructured noble metal/metal oxide/graphene-coated CF demonstrates dramatically enhanced electrocatalytic activity. When used for nonenzymatic H2O2 sensing, the resultant modified microelectrode exhibits acceptable sensitivity, reproducibility, stability, and selectivity, which enable it to be used for real-time tracking H2O2 secretion in human cervical cancer cells. Graphical abstract A schematic illustration of preparation of hierarchical Au/MnO2/ERGO/CF nanohybrid electrode for real-time molecular detection of cancer cells.

  1. In-Situ Nondestructive Evaluation of Kevlar(Registered Trademark)and Carbon Fiber Reinforced Composite Micromechanics for Improved Composite Overwrapped Pressure Vessel Health Monitoring

    NASA Technical Reports Server (NTRS)

    Waller, Jess; Saulsberry, Regor

    2012-01-01

    NASA has been faced with recertification and life extension issues for epoxy-impregnated Kevlar 49 (K/Ep) and carbon (C/Ep) composite overwrapped pressure vessels (COPVs) used in various systems on the Space Shuttle and International Space Station, respectively. Each COPV has varying criticality, damage and repair histories, time at pressure, and pressure cycles. COPVs are of particular concern due to the insidious and catastrophic burst-before-leak failure mode caused by stress rupture (SR) of the composite overwrap. SR life has been defined [1] as the minimum time during which the composite maintains structural integrity considering the combined effects of stress level(s), time at stress level(s), and associated environment. SR has none of the features of predictability associated with metal pressure vessels, such as crack geometry, growth rate and size, or other features that lend themselves to nondestructive evaluation (NDE). In essence, the variability or surprise factor associated with SR cannot be eliminated. C/Ep COPVs are also susceptible to impact damage that can lead to reduced burst pressure even when the amount of damage to the COPV is below the visual detection threshold [2], thus necessitating implementation of a mechanical damage control plan [1]. Last, COPVs can also fail prematurely due to material or design noncompliance. In each case (SR, impact or noncompliance), out-of-family behavior is expected leading to a higher probability of failure at a given stress, hence, greater uncertainty in performance. For these reasons, NASA has been actively engaged in research to develop NDE methods that can be used during post-manufacture qualification, in-service inspection, and in-situ structural health monitoring. Acoustic emission (AE) is one of the more promising NDE techniques for detecting and monitoring, in real-time, the strain energy release and corresponding stress-wave propagation produced by actively growing flaws and defects in composite

  2. Mesophase pitch-based carbon fiber for improved inflammability of CFRP

    SciTech Connect

    Nakagoshi, Akira; Tomonoh, Shigeki; Sakamoto, Yosihiro

    1995-10-01

    Carbon Fiber Reinforced Plastics (CFRP) are extensively used because of their favorable physical properties such as high strength-to-weight ratio and small thermal expansion. However, flammability of CFRP has limited their application especially in the transportation and industrial field. Exposed to flame, CFRP laminates made of PAN-based carbon fibers burst into flame in short time, while CFRP laminates made from mesophase pitch-based carbon fibers don`t burst into flame. This paper describes the experimental results of local heating test by gas burner. When the flame temperature was 1,000 C, a CFRP laminate made from PAN-based carbon fiber burned within 40 sec. Under the same condition, a CFRP laminate made from mesophase pitch-based carbon fiber didn`t burn in 10 min. The matrix resin of both laminates was 250 F curable epoxy resin. This behavior mainly depends upon the thermal conductivity of the carbon fibers. The mesophase pitch-based carbon fibers have high thermal conductivity, so they can diffuse thermal energy and lower laminate surface temperature. On the other hand, PAN-based carbon fibers have low thermal conductivity, so they can`t diffuse thermal energy enough, and the laminates made from them burn easily. Mechanical properties of CFRP during local heating test in comparison with Aluminum plate are also discussed.

  3. Influence of carbon nanotubes coatings onto carbon fiber by oxidative treatments combined with electrophoretic deposition on interfacial properties of carbon fiber composite

    NASA Astrophysics Data System (ADS)

    Deng, Chao; Jiang, Jianjun; Liu, Fa; Fang, Liangchao; Wang, Junbiao; Li, Dejia; Wu, Jianjun

    2015-12-01

    To improve the interfacial performance of carbon fiber (CF) and epoxy resin, carbon nanotubes (CNTs) coatings were utilized to achieve this purpose through coating onto CF by the treatment with hydrogen peroxide and concentrated nitric acid combined with electrophoretic deposition (EPD) process. The influence of electrophoretically deposited CNTs coatings on the surface properties of CFs were investigated by Fourier transform infrared spectrometer, atomic force microscopy, scanning electron microscopy and dynamic contact angle analysis. The results indicated that the deposition of carbon nanotubes introduced some polar groups to carbon fiber surfaces, enhanced surface roughness and changed surface morphologies of carbon fibers. Surface wettability of carbon fibers may be significantly improved by increasing surface free energy of the fibers due to the deposition of CNTs. The thickness and density of the coatings increases with the introduction of pretreatment of the CF during the EPD process. Short beam shear test was performed to examine the effect of carbon fiber functionalization on mechanical properties of the carbon fiber/epoxy resin composites. The interfacial adhesion of CNTs/CF reinforced epoxy composites showed obvious enhancement of interlaminar shear strength by 60.2% and scanning electron microscope photographs showed that the failure mode of composites was changed after the carbon fibers were coated with CNTs.

  4. RADIATION EFFECTS ON EPOXY CARBON FIBER COMPOSITE

    SciTech Connect

    Hoffman, E

    2008-05-30

    Carbon fiber-reinforced bisphenol-A epoxy matrix composite was evaluated for gamma radiation resistance. The composite was exposed to total gamma doses of 50, 100, and 200 Mrad. Irradiated and baseline samples were tested for tensile strength, hardness and evaluated using FTIR (Fourier transform infrared) spectroscopy and DSC (differential scanning calorimetry) for structural changes. Scanning electron microscopy was used to evaluate microstructural behavior. Mechanical testing of the composite bars revealed no apparent change in modulus, strain to failure, or fracture strength after exposures. However, testing of only the epoxy matrix revealed changes in hardness, thermal properties, and FTIR results with increasing gamma irradiation. The results suggest the epoxy within the composite can be affected by exposure to gamma irradiation.

  5. Microwave axial dielectric properties of carbon fiber

    PubMed Central

    Hong, Wen; Xiao, Peng; Luo, Heng; Li, Zhuan

    2015-01-01

    Randomly distributed carbon fibers (CFs) reinforced epoxy resin composites are prepared by the pouring method, the dielectric properties of CF composites with different fiber content and length have been performed in the frequency range from 8.2 to 12.4 GHz. The complex permittivity of the composite increases with the fiber length, which is attributed to the decrease of depolarization field, and increases with the volume fraction, which is attributed to the increase of polarization. A formula, based on the theory of Reynolds-Hugh, is proposed to calculate the effective permittivity of CF composites, and validated by the experiments. The proposed formula is further applied to derive the axial permittivity of CF and analyze the effect of fiber length on the axial permittivity. PMID:26477579

  6. Indium phosphide nanowires integrated directly on carbon fibers

    NASA Astrophysics Data System (ADS)

    Lohn, Andrew J.; Longson, Timothy J.; Kobayashi, Nobuhiko P.

    2011-10-01

    We have demonstrated the growth of a group III-V semiconductor binary alloy, indium phosphide (InP), directly on carbon fibers thereby enabling a union of semiconductor and structural materials. Carbon fibers were prepared by electrospinning solutions of polyacrilonitrile (PAN) and dimethylformamide (DMF) followed by carbonization at 750 °C in inert atmosphere. Gold nanoparticles dispersed on the fibers catalyzed nanowire growth by metal organic chemical vapor deposition. X-ray diffraction suggests that the nanowires appear to be epitaxially grown along the (110) direction. Geometrical parameters have been determined by scanning electron microscopy and transmission electron microscopy and elemental analysis has been carried out using energy dispersive spectroscopy. The nanowires grown from carbon fibers are composed of an amorphous shell and crystalline core which alternates at high spatial frequency.mountai

  7. Fabrication of polytetrafluoroethylene/carbon fiber composites using radiation crosslinking

    NASA Astrophysics Data System (ADS)

    Oshima, Akihiro; Udagawa, Akira; Tanaka, Shigeru

    2001-07-01

    A fabrication method for fiber-reinforced plastic (FRP) composites based on carbon fibers and polytetrafluoroethylene (PTFE) which was crosslinked by electron beam (EB) irradiation under specific conditions was studied. Though the fabricated composite showed high mechanical properties compared with a ready-made PTFE composite (non-crosslinked PTFE with 5˜20 wt% filler), mechanical properties of laminated panels were a bit poor compared with those of usual FRP. It was found that the toughness of the PTFE matrix is poor in the composite. On the other hand, the one-ply sheet of carbon fibers and crosslinked PTFE composite showed good mechanical properties for sheet-shape materials. The wettability of the obtained crosslinked PTFE composite is hardly changed by crosslinking and reinforcement.

  8. The development of high precision carbon fiber composite mirror

    NASA Astrophysics Data System (ADS)

    Xu, Liang; Ding, Jiao-teng; Wang, Yong-jie; Xie, Yong-jie; Ma, Zhen; Fan, Xue-wu

    2016-10-01

    Due to low density, high stiffness, low thermal expansion coefficient, duplicate molding, etc., carbon fiber reinforced polymer (CFRP) is one of the potential materials of the optical mirror. The process developed for Φ300mm high precision CFRP mirror described in this paper. A placement tool used to improve laying accuracy up to ± 0.1°.A special reinforced cell structure designed to increase rigidity and thermal stability. Optical replication process adopted for surface modification of the carbon fiber composite mirror blank. Finally, surface accuracy RMS of Φ300mm CFRP mirror is 0.22μm, surface roughness Ra is about 2nm, and the thermal stability can achieve 13nm /°C from the test result. The research content is of some reference value in the infrared as well as visible light applications.

  9. Development of Commodity Grade, Lower Cost Carbon Fiber - Commercial Applications

    SciTech Connect

    Warren, Charles David; Paulauskas, Felix L; Baker, Frederick S; Eberle, Cliff; Naskar, Amit K

    2009-01-01

    In pursuit of the goal to produce ultra-lightweight fuel efficient vehicles, there has been great excitement during the last few years about the potential for using carbon fiber reinforced composites in high volume applications. Currently, the greatest hurdle that inhibits wider implementation of carbon fiber composites in transportation is the high cost of the fiber when compared to other candidate materials. As part of the United States Department of Energy s FreedomCAR initiative, significant research is being conducted to develop lower cost, high volume technologies for producing carbon fiber. This paper will highlight the on-going research in this area. Through Department of Energy (DOE) sponsorship, Oak Ridge National Laboratory (ORNL) and its partners have been working with the US Automotive Composites Consortium (ACC) to develop technologies that would enable the production of carbon fiber at 5-7 dollars per pound. Achievement of this cost goal would allow the introduction of carbon fiber based composites into a greater number of applications for future vehicles. The approach has necessitated the development of both alternative precursors and more efficient production methods. Alternative precursors under investigation include textile grade polyacrylonitrile (PAN) fibers and fibers from lignin-based feedstocks. Previously, as part of the research program, Hexcel Corporation developed the science necessary to allow textile grade PAN to be used as a precursor rather than typical carbon fiber grade precursors. Efforts are also underway to develop carbon fiber precursors from lignin-based feedstocks. ORNL and its partners are working on this effort with domestic pulp and paper producers. In terms of alternative production methods, ORNL has developed a microwave-based carbonization unit that can process pre-oxidized fiber at over 200 inches per minute. ORNL has also developed a new method of high speed oxidation and a new method for precursor stabilization

  10. Production of graphene oxide from pitch-based carbon fiber.

    PubMed

    Lee, Miyeon; Lee, Jihoon; Park, Sung Young; Min, Byunggak; Kim, Bongsoo; In, Insik

    2015-07-09

    Pitch-based graphene oxide (p-GO) whose compositional/structural features are comparable to those of graphene oxide (GO) was firstly produced by chemical exfoliation of pitch-based carbon fiber rather than natural graphite. Incorporation of p-GO as nanofillers into poly(methyl methacrylate) (PMMA) as a matrix polymer resulted in excellent mechanical reinforcement. p-GO/PMMA nanocomposite (1 wt.-% p-GO) demonstrated 800% higher modulus of toughness of neat PMMA.

  11. Production of graphene oxide from pitch-based carbon fiber

    NASA Astrophysics Data System (ADS)

    Lee, Miyeon; Lee, Jihoon; Park, Sung Young; Min, Byunggak; Kim, Bongsoo; in, Insik

    2015-07-01

    Pitch-based graphene oxide (p-GO) whose compositional/structural features are comparable to those of graphene oxide (GO) was firstly produced by chemical exfoliation of pitch-based carbon fiber rather than natural graphite. Incorporation of p-GO as nanofillers into poly(methyl methacrylate) (PMMA) as a matrix polymer resulted in excellent mechanical reinforcement. p-GO/PMMA nanocomposite (1 wt.-% p-GO) demonstrated 800% higher modulus of toughness of neat PMMA.

  12. Production of graphene oxide from pitch-based carbon fiber

    PubMed Central

    Lee, Miyeon; Lee, Jihoon; Park, Sung Young; Min, Byunggak; Kim, Bongsoo; In, Insik

    2015-01-01

    Pitch-based graphene oxide (p-GO) whose compositional/structural features are comparable to those of graphene oxide (GO) was firstly produced by chemical exfoliation of pitch-based carbon fiber rather than natural graphite. Incorporation of p-GO as nanofillers into poly(methyl methacrylate) (PMMA) as a matrix polymer resulted in excellent mechanical reinforcement. p-GO/PMMA nanocomposite (1 wt.-% p-GO) demonstrated 800% higher modulus of toughness of neat PMMA. PMID:26156067

  13. Carbide-reinforced metal matrix composite by direct metal deposition

    NASA Astrophysics Data System (ADS)

    Novichenko, D.; Thivillon, L.; Bertrand, Ph.; Smurov, I.

    Direct metal deposition (DMD) is an automated 3D laser cladding technology with co-axial powder injection for industrial applications. The actual objective is to demonstrate the possibility to produce metal matrix composite objects in a single-step process. Powders of Fe-based alloy (16NCD13) and titanium carbide (TiC) are premixed before cladding. Volume content of the carbide-reinforced phase is varied. Relationships between the main laser cladding parameters and the geometry of the built-up objects (single track, 2D coating) are discussed. On the base of parametric study, a laser cladding process map for the deposition of individual tracks was established. Microstructure and composition of the laser-fabricated metal matrix composite objects are examined. Two different types of structures: (a) with the presence of undissolved and (b) precipitated titanium carbides are observed. Mechanism of formation of diverse precipitated titanium carbides is studied.

  14. Treated carbon fibers with improved performance for electrochemical and chemical applications

    DOEpatents

    Chu, X.; Kinoshita, Kimio

    1999-02-23

    A treated mesophase carbon fiber is disclosed having a high density of exposed edges on the fiber surface, and a method is described for making such a treated fiber. A carbon electrode is also described which is constructed from such treated mesophase carbon fibers. The resulting electrode, formed from such treated flexible carbon fibers, is characterized by a high density of active sites formed from such exposed edges, low corrosion, and good mechanical strength, and may be fabricated into various shapes. The treated mesophase carbon fibers of the invention are formed by first loading the surface of the mesophase carbon fiber with catalytic metal particles to form catalytic etch sites on a hard carbon shell of the fiber. The carbon fiber is then subject to an etch step wherein portions of the hard carbon shell or skin are selectively removed adjacent the catalytic metal particles adhering to the carbon shell. This exposes the underlying radial edges of the graphite-like layers within the carbon shell of the mesophase carbon fiber, which exposed radial edges then act as active sites of a carbon electrode subsequently formed from the treated mesophase carbon fibers. 14 figs.

  15. Treated carbon fibers with improved performance for electrochemical and chemical applications

    DOEpatents

    Chu, Xi; Kinoshita, Kimio

    1999-01-01

    A treated mesophase carbon fiber is disclosed having a high density of exposed edges on the fiber surface, and a method of making such a treated fiber. A carbon electrode is also described which is constructed from such treated mesophase carbon fibers. The resulting electrode, formed from such treated flexible carbon fibers, is characterized by a high density of active sites formed from such exposed edges, low corrosion, and good mechanical strength, and may be fabricated into various shapes. The treated mesophase carbon fibers of the invention are formed by first loading the surface of the mesophase carbon fiber with catalytic metal particles to form catalytic etch sites on a hard carbon shell of the fiber. The carbon fiber is then subject to an etch step wherein portions of the hard carbon shell or skin are selectively removed adjacent the catalytic metal particles adhering to the carbon shell. This exposes the underlying radial edges of the graphite-like layers within the carbon shell of the mesophase carbon fiber, which exposed radial edges then act as active sites of a carbon electrode subsequently formed from the treated mesophase carbon fibers.

  16. Repairable Woven Carbon Fiber Composites with Full Recyclability Enabled by Malleable Polyimine Networks.

    PubMed

    Taynton, Philip; Ni, Huagang; Zhu, Chengpu; Yu, Kai; Loob, Samuel; Jin, Yinghua; Qi, H Jerry; Zhang, Wei

    2016-04-20

    Carbon-fiber reinforced composites are prepared using catalyst-free malleable polyimine networks as binders. An energy neutral closed-loop recycling process has been developed, enabling recovery of 100% of the imine components and carbon fibers in their original form. Polyimine films made using >21% recycled content exhibit no loss of mechanical performance, therefore indicating all of the thermoset composite material can be recycled and reused for the same purpose.

  17. Carbon fibers from aromatic hydrocarbons

    SciTech Connect

    Mochida, Isao; Yoon, S.H.; Korai, Yozo; Kanno, Koichi; Sakai, Yukio; Komatsu, Makoto

    1995-02-01

    Carbon filter is widely used as a lightweight and high-strength material for composite structures. Its uses are expected to expand in the next century. Currently the best precursor for making these fibers is polyacrylonitrile (PAN). This is a relatively expensive feedstock. Carbon fibers also have been made starting with so-called mesophase pitch fractions derived from low-cost hydrocarbons such as petroleum residuum. But these fibers suffer from low mechanical strength. In the past few years, significant advances have been made in understanding the mechanism of formation of mesophase pitch, which may lead to improved performance for carbon fibers and other specialty carbons. This article introduces such advances, based principally on the authors` recent results.

  18. Carbon fibers from SRC pitch

    DOEpatents

    Greskovich, Eugene J.; Givens, Edwin N.

    1981-01-01

    This invention relates to an improved method of manufacturing carbon fibers from a coal derived pitch. The improvement resides in the use of a solvent refined coal which has been hydrotreated and subjected to solvent extraction whereby the hetero atom content in the resulting product is less than 4.0% by weight and the softening point is between about 100.degree.-250.degree. F.

  19. A Silicon detector system on carbon fiber support at small radius

    SciTech Connect

    Marvin E. Johnson

    2004-04-28

    The design of a silicon detector for a p{bar p} collider experiment will be described. The detector uses a carbon fiber support structure with sensors positioned at small radius with respect to the beam. A brief overview of the mechanical design is given. The emphasis is on the electrical characteristics of the detector. General principles involved in grounding systems with carbon fiber structures will be covered. The electrical characteristics of the carbon fiber support structure will be presented. Test results imply that carbon fiber must be regarded as a conductor for the frequency region of interest of 10 to 100 MHz. No distinction is found between carbon fiber and copper. Performance results on noise due to pick-up through the low mass fine pitch cables carrying the analogue signals and floating metal is discussed.

  20. Continuous Processing of Multi-Walled Carbon Nanotube-Studded Carbon Fiber Tapes for Enhanced Through-Thickness Thermal Diffusivity Composites.

    PubMed

    Craddock, John D; Qian, Dali; Lester, Catherine; Matthews, JohnJ; Mansfield, J Patrick W; Foedinger, Richard; Weisenberger, Matthew C

    2015-09-01

    Carbon fiber reinforced polymer (CFRP) composites offer advantages over traditional metallic structures, particularly specific strength and stiffness, but at much reduced thermal conductivity. Moreover, fiber-to-fiber heat conduction in the composite transverse directions is significantly lower. When these structures contain electronics (heat generators), shortfalls in heat transport can be problematic. Here we report the achievement of a continuous, reel-to-reel process for growing short multiwalled carbon nanotubes (MWCNT) on the surfaces of spread-tow carbon fiber tapes. These tapes were subsequently prepregged with an epoxy matrix, and laid up into multi-ply laminate panels, cured and tested for through-thickness thermal diffusivity. The results showed up to a 57% increase in through thickness thermal diffusivity compared to the baseline composite with no MWCNT.

  1. Properties of carbon fibers with various coatings

    NASA Technical Reports Server (NTRS)

    Seegel, V.; Mcmahon, P.

    1983-01-01

    It is shown that all high modulus carbon fibers are durable with respect to thermal oxidation in air. Among the more widely used and economical materials with low modulus, Celion displays particularly good oxidative durability at high temperatures. This contrast to other materials is due to the low content of Natrium and Kalium in Celion carbon fibers. It is also noted that improved characteristics are attained in Celion carbon fiber/polyimide systems when fibers are used with high temperature resistant polyimide coatings.

  2. Assessment of Carbon Fiber Electrical Effects

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The risks associated with the use of carbon fiber composites in civil aircraft are discussed along with the need for protection of civil aircraft equipment from fire-released carbon fibers. The size and number of carbon fibers released in civil aircraft crash fires, the downwind dissemination of the fibers, their penetration into buildings and equipment, and the vulnerability of electrical/electronic equipment to damage by the fibers are assessed.

  3. Overview of the carbon fiber problem

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Carbon fibers (CF) composite structures are being utilized more as alternatives to metals in both civilian and military applications. They are valued for their light weight and high strength as well as for their ease of designing structures with specific shapes and sizes. However, a problem may exist due to the high conductivity of CF. CF are manufactured from a precursor material which is subjected to great stress and heat treatment causing a change in the physical and electrical properties. The fibers are bound together by a matrix of epoxy. In the event of fire (aircraft accident) the epoxy would burn away releasing these fibers into the atmosphere. When these fibers come in contact with electronic equipment, they might cause damage to by settling on electrical junctions. An overview is given of the objectives for a study, and the approach and methodology developed for determination of risk profiles.

  4. Interfacial Studies of Sized Carbon Fiber

    SciTech Connect

    Shahrul, S. N.; Hartini, M. N.; Hilmi, E. A.; Nizam, A.

    2010-03-11

    This study was performed to investigate the influence of sizing treatment on carbon fiber in respect of interfacial adhesion in composite materials, Epolam registered 2025. Fortafil unsized carbon fiber was used to performed the experiment. The fiber was commercially surface treated and it was a polyacrylonitrile based carbon fiber with 3000 filament per strand. Epicure registered 3370 was used as basic sizing chemical and dissolved in two types of solvent, ethanol and acetone for the comparison purpose. The single pull out test has been used to determine the influence of sizing on carbon fiber. The morphology of carbon fiber was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The apparent interfacial strength IFSS values determined by pull out test for the Epicure registered 3370/ethanol sized carbon fiber pointed to a good interfacial behaviour compared to the Epicure registered 3370/acetone sized carbon fiber. The Epicure registered 3370/ethanol sizing agent was found to be effective in promoting adhesion because of the chemical reactions between the sizing and Epolam registered 2025 during the curing process. From this work, it showed that sized carbon fiber using Epicure registered 3370 with addition of ethanol give higher mechanical properties of carbon fiber in terms of shear strength and also provided a good adhesion between fiber and matrix compared to the sizing chemical that contain acetone as a solvent.

  5. Method for the preparation of carbon fiber from polyolefin fiber precursor, and carbon fibers made thereby

    DOEpatents

    Naskar, Amit Kumar; Hunt, Marcus Andrew; Saito, Tomonori

    2015-08-04

    Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

  6. RADIATION EFFECTS ON EPOXY/CARBON FIBER COMPOSITE

    SciTech Connect

    Hoffman, E; Eric Skidmore, E

    2008-12-12

    The Department of Energy Savannah River Site vitrifies nuclear waste incident to defense programs through its Defense Waste Processing Facility (DWPF). The piping in the DWPF seal pot jumper configuration must withstand the stresses during an unlikely but potential deflagration event, and maintain its safety function for a 20-year service life. Carbon fiber-reinforced epoxy composites (CFR) were proposed for protection and reinforcement of piping during such an event. The proposed CFR materials have been ASME-approved (Section XI, Code Case N-589-1) for post-construction maintenance and is DOT-compliant per 49CFR 192 and 195. The proposed carbon fiber/epoxy composite reinforcement system was originally developed for pipeline rehabilitation and post-construction maintenance in petrochemical, refineries, DOT applications and other industries. The effects of ionizing radiation on polymers and organic materials have been studied for many years. The majority of available data are based on traditional exposures to gamma irradiation at high dose rates ({approx}10,000 Gy/hr) allowing high total dose within reasonable test periods and general comparison of different materials exposed at such conditions. However, studies in recent years have shown that degradation of many polymers are sensitive to dose rate, with more severe degradation often observed at similar or even lower total doses when exposed to lower dose rates. This behavior has been primarily attributed to diffusion-limited oxidation which is minimized during very high dose rate exposures. Most test standards for accelerated aging and nuclear qualification of components acknowledge these limitations. The results of testing to determine the radiation resistance and microstructural effects of gamma irradiation exposure on a bisphenol-A based epoxy matrix composite reinforced with carbon fibers are presented. This work provides a foundation for a more extensive evaluation of dose rate effects on advanced epoxy

  7. Interfacial adhesion of carbon fibers

    NASA Technical Reports Server (NTRS)

    Bascom, Willard D.

    1987-01-01

    Relative adhesion strengths between AS4, AS1, and XAS carbon fibers and thermoplastic polymers were determined using the embedded single filament test. Polymers studied included polycarbonate, polyphenylene oxide, polyetherimide, polysulfone, polyphenylene oxide blends with polystyrene, and polycarbonate blends with a polycarbonate polysiloxane block copolymer. Fiber surface treatments and sizings improved adhesion somewhat, but adhesion remained well below levels obtained with epoxy matrices. An explanation for the differences between the Hercules and Grafil fibers was sought using X ray photon spectroscopy, wetting, scanning electron microscopy and thermal desorption analysis.

  8. FIBER-REINFORCED METALLIC COMPOSITE MATERIALS.

    DTIC Science & Technology

    COMPOSITE MATERIALS), (*FIBER METALLURGY, TITANIUM ALLOYS , NICKEL ALLOYS , REINFORCING MATERIALS, TUNGSTEN, WIRE, MOLYBDENUM ALLOYS , COBALT ALLOYS , CHROMIUM ALLOYS , ALUMINUM ALLOYS , MECHANICAL PROPERTIES, POWDER METALLURGY.

  9. Enhancement of the in-plane shear properties of carbon fiber composites containing carbon nanotube mats

    NASA Astrophysics Data System (ADS)

    Kim, Hansang

    2015-01-01

    The in-plane shear property of carbon fiber laminates is one of the most important structural features of aerospace and marine structures. Fiber-matrix debonding caused by in-plane shear loading is the major failure mode of carbon fiber composites because of the stress concentration at the interfaces. In this study, carbon nanotube mats (CNT mat) were incorporated in two different types of carbon fiber composites. For the case of woven fabric composites, mechanical interlocking between the CNTs and the carbon fibers increased resistance to shear failure. However, not much improvement was observed for the prepreg composites as a result of incorporation of the CNT mats. The reinforcement mechanism of the CNT mat layer was investigated by a fractographic study using scanning electron microscopy. In addition, the CNT mat was functionalized by three different methods and the effectiveness of the functionalization methods was determined and the most appropriate functionalization method for the CNT mat was air oxidation.

  10. Carbon fiber composites inspection and defect characterization using active infrared thermography: numerical simulations and experimental results.

    PubMed

    Fernandes, Henrique; Zhang, Hai; Figueiredo, Alisson; Ibarra-Castanedo, Clemente; Guimarares, Gilmar; Maldague, Xavier

    2016-12-01

    Composite materials are widely used in the aeronautic industry. One of the reasons is because they have strength and stiffness comparable to metals, with the added advantage of significant weight reduction. Infrared thermography (IT) is a safe nondestructive testing technique that has a fast inspection rate. In active IT, an external heat source is used to stimulate the material being inspected in order to generate a thermal contrast between the feature of interest and the background. In this paper, carbon-fiber-reinforced polymers are inspected using IT. More specifically, carbon/PEEK (polyether ether ketone) laminates with square Kapton inserts of different sizes and at different depths are tested with three different IT techniques: pulsed thermography, vibrothermography, and line scan thermography. The finite element method is used to simulate the pulsed thermography experiment. Numerical results displayed a very good agreement with experimental results.

  11. Tailoring micro-mesoporosity in activated carbon fibers to enhance SO₂ catalytic oxidation.

    PubMed

    Diez, Noel; Alvarez, Patricia; Granda, Marcos; Blanco, Clara; Gryglewicz, Grażyna; Wróbel-Iwaniec, Iwona; Sliwak, Agata; Machnikowski, Jacek; Menendez, Rosa

    2014-08-15

    Enhanced SO2 adsorption of activated carbon fibers is obtained by tailoring a specific micro-mesoporous structure in the fibers. This architecture is obtained via metal catalytic activation of the fibers with a novel precursor, cobalt naphthenate, which contrary to other precursors, also enhances spinnability and carbon fiber yield. In the SO2 oxidation, it is demonstrated that the combination of micropores and large mesopores is the main factor for an enhanced catalytic activity which is superior to that observed in other similar microporous activated carbon fibers. This provides an alternative way for the development of a new generation of catalytic material.

  12. Solvent recovery improved with activated carbon fibers

    SciTech Connect

    Not Available

    1982-11-01

    A non-woven net of activated carbon fibers as absorbing media, representing a major advancement in vapor recovery technology, is presented. The carbon fiber exhibits mass transfer coefficients for adsorption description of up to 100 times that of conventional systems.

  13. Patterned functional carbon fibers from polyethylene.

    PubMed

    Hunt, Marcus A; Saito, Tomonori; Brown, Rebecca H; Kumbhar, Amar S; Naskar, Amit K

    2012-05-08

    Carbon fibers having unique morphologies, from hollow circular to gear-shaped, are produced from a novel melt-processable precursor and method. The resulting carbon fiber exhibits microstructural and topological properties that are dependent on processing conditions, rendering them highly amenable to myriad applications.

  14. Newer Carbon Fibers and Their Properties

    NASA Technical Reports Server (NTRS)

    Bacon, R.

    1984-01-01

    The newer carbon fibers that are either on the market or coming in the near future are described. The structure of carbon fibers is discussed along with the relationship between structure and physical property. Finally, how different types of structure are designed by control of process parameters is described.

  15. Mesophase pitches, carbon fiber precursors, and carbonized fibers

    SciTech Connect

    Sumner, M.B.; Hettinger, M.P.

    1993-08-24

    A process is described for the production of a stabilized carbon fiber which process comprises: forming a film having a thickness in the range of about 0.025 mm (0.001 in) to about 2.5 mm (0.1 in), of a catalytic pitch; maintaining said film at a temperature in the range of about 327 C to about 427 C and a pressure in the range of about 20 microns of mercury to about 1 atm for a time that is sufficient to produce a heavy isotropic pitch having a softening point in the range of about 127 C to about 288 C, a coking value in the range of about 55 wt % to about 95 wt %, and a maximum mesophase content of 5 vol %; agitating said heavy isotropic pitch while passing an inert gas through said heavy isotropic pitch at a rate of up to about 30 SCFH/1b at a temperature in the range of about 327 C to about 454 C for a time that is sufficient to provide a mesophase pitch having a vol. % of mesophase of at least 60; converting said mesophase pitch into green fibers; and stabilizing for a minimum time ranging from about 14 to about 288 minutes said green fibers with an oxidizing agent while heating said green fibers to a starting temperature of about 41 C to 221 C that is below the glass transition temperature of the mesophase pitch, and thereafter increasing the temperature of said green fiber at a rate of between about 1 C/min and 6 C/min to a final temperature in the range of about 282 C to 343 C to provide a stabilized carbon fiber.

  16. Fabrication and Characterization of Multi-Walled Carbon Nanotube (MWCNT) and Ni-Coated Multi-Walled Carbon Nanotube (Ni-MWCNT) Repair Patches for Carbon Fiber Reinforced Composite Systems

    NASA Technical Reports Server (NTRS)

    Johnson, Brienne; Caraccio, Anne; Tate, LaNetra; Jackson, Dionne

    2011-01-01

    Multi-walled carbon nanotube (MWCNT)/epoxy and nickel-coated multi-walled carbon nanotube (Ni-MWCNT)/epoxy systems were fabricated into carbon fiber composite repair patches via vacuum resin infusion. Two 4 ply patches were manufactured with fiber orientations of [90/ 90/ 4590] and [0/90/ +45/ -45]. Prior to resin infusion, the MWCNT/Epoxy system and NiMWCNT/ epoxy systems were optimized for dispersion quality. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to determine the presence ofcarbon nanotubes and assess dispersion quality. Decomposition temperatures were determined via thermogravametric analysis (TGA). SEM and TGA were also used to evaluate the composite repair patches.

  17. Reinforcement of a mandibular complete denture with internal metal framework.

    PubMed

    Balch, J Heath; Smith, Pamela D; Marin, Mark A; Cagna, David R

    2013-03-01

    Metal framework reinforcement is used in complete dentures to improve the fracture resistance, dimensional stability, accuracy, weight, and retention of a definitive prosthesis. A novel technique for suspending a metal framework within the denture base of mandibular complete dentures is described.

  18. An investigation of carbon fiber/polyphenylene sulfide adhesion

    SciTech Connect

    Fisher, G.S.; Drzal, L.T.

    1996-12-31

    The level of adhesion between reinforcing fibers and a thermoplastic matrix can have a strong effect on composite mechanical properties. In composites of polyphenylene sulfide (PPS) with carbon fibers, Phillips Petroleum Company has reported an increase in transverse tensile strength from 30 MPa to 74 MPa and an increase in transverse flexural strength from 44 to 141 MPa when extrusion grade PPS resin is replaced with a composite grade resin. Since transverse composite properties are particularly sensitive to adhesion, it was suspected that improved fiber/matrix adhesion could be responsible for the improved mechanical properties. Several factors can affect the adhesion between carbon fibers and a semicrystalline thermoplastic such as PPS. These factors include fiber surface structure and chemistry, adsorption of matrix onto fibers, chemical bonding between fiber and matrix, and morphology of the matrix near the fibers. The objectives of this study were to determine the interfacial shear strengths of several types of carbon fibers with both grades of PPS and to determine which factors affect fiber/matrix adhesion. This will allow the authors to determine whether the differences in composite mechanical properties can be correlated to different levels of adhesion and to identify the key factor(s) that lead to any differences in adhesion.

  19. Plasma polymerized thin coating as a protective layer of carbon nanotubes grafted on carbon fibers

    NASA Astrophysics Data System (ADS)

    Einig, A.; Rumeau, P.; Desrousseaux, S.; Magga, Y.; Bai, J. B.

    2013-04-01

    Nanoparticles addition is widely studied to improve properties of carbon fiber reinforced composites. Here, hybrid carbon fiber results from grafting of carbon nanotubes (CNT) by Chemical Vapor Deposition (CVD) on the carbon fiber for mechanical reinforcement and conductive properties. Both tows and woven fabrics made of the hybrid fibers are added to the matrix for composite processing. However handling hybrid fibers may induce unwilling health risk due to eventual CNT release and a protective layer is required. A thin coating layer is deposited homogeneously by low pressure plasma polymerization of an organic monomer without modifying the morphology and the organization of grafted CNTs. The polymeric layer effect on the electrical behavior of hybrid fiber is assessed by conductivity measurements. Its influence on the mechanical properties is also studied regarding the interface adhesion between fiber and matrix. The protective role of layer is demonstrated by means of friction constraints applied to the hybrid fiber.

  20. Laser ultrasound technology for fault detection on carbon fiber composites

    NASA Astrophysics Data System (ADS)

    Seyrkammer, Robert; Reitinger, Bernhard; Grün, Hubert; Sekelja, Jakov; Burgholzer, Peter

    2014-05-01

    The marching in of carbon fiber reinforced polymers (CFRPs) to mass production in the aeronautic and automotive industry requires reliable quality assurance methods. Laser ultrasound (LUS) is a promising nondestructive testing technique for sample inspection. The benefits compared to conventional ultrasound (US) testing are couplant free measurements and an easy access to complex shapes due to remote optical excitation and detection. Here the potential of LUS is present on composite test panels with relevant testing scenarios for industry. The results are evaluated in comparison to conventional ultrasound used in the aeronautic industry.

  1. FIBER ORIENTATION IN INJECTION MOLDED LONG CARBON FIBER THERMOPLASTIC COMPOSITES

    SciTech Connect

    Wang, Jin; Nguyen, Ba Nghiep; Mathur, Raj N.; Sharma, Bhisham; Sangid, Michael D.; Costa, Franco; Jin, Xiaoshi; Tucker III, Charles L.; Fifield, Leonard S.

    2015-03-23

    A set of edge-gated and center-gated plaques were injection molded with long carbon fiber-reinforced thermoplastic composites, and the fiber orientation was measured at different locations of the plaques. Autodesk Simulation Moldflow Insight (ASMI) software was used to simulate the injection molding of these plaques and to predict the fiber orientation, using the anisotropic rotary diffusion and the reduced strain closure models. The phenomenological parameters of the orientation models were carefully identified by fitting to the measured orientation data. The fiber orientation predictions show very good agreement with the experimental data.

  2. RADIATION EFFECTS ON EPOXY/CARBON-FIBER COMPOSITE

    SciTech Connect

    Hoffman, E

    2008-01-11

    Piping in the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) must withstand the stresses involved during an unlikely but potential deflagration event. One method proposed for protection and reinforcement of piping during such an event is the use of a carbon fiber-reinforced epoxy composite (Diamond-Wrap{reg_sign}). In the DWPF, this reinforcement composite product would be required to maintain its safety function for a 20-year service life. This product has been ASME-approved (nuclear code case 589) for post-construction maintenance and is DOT-compliant per 49CFR 192 and 195. However, its radiation resistance properties have not been evaluated. This report documents initial radiation resistance testing of the product and microstructural effects. Additional testing is recommended to evaluate radiation effects on specific properties such as burst strength, chemical resistance/weeping and for service life prediction in critical applications.

  3. Modeling the Role of Bulk and Surface Characteristics of Carbon Fiber on Thermal Conductance across the Carbon-Fiber/Matrix Interface.

    PubMed

    Varshney, Vikas; Roy, Ajit K; Baur, Jeffery W

    2015-12-09

    The rapid heating of carbon-fiber-reinforced polymer matrix composites leads to complex thermophysical interactions which not only are dependent on the thermal properties of the constituents and microstructure but are also dependent on the thermal transport between the fiber and resin interfaces. Using atomistic molecular dynamics simulations, the thermal conductance across the interface between a carbon-fiber near-surface region and bismaleimide monomer matrix is calculated as a function of the interface and bulk features of the carbon fiber. The surface of the carbon fiber is modeled as sheets of graphitic carbon with (a) varying degrees of surface functionality, (b) varying defect concentrations in the surface-carbon model (pure graphitic vs partially graphitic), (c) varying orientation of graphitic carbon at the interface, (d) varying interface saturation (dangling vs saturated bonds), (e) varying degrees of surface roughness, and (f) incorporating high conductive fillers (carbon nanotubes) at the interface. After combining separately equilibrated matrix system and different surface-carbon models, thermal energy exchange is investigated in terms of interface thermal conductance across the carbon fiber and the matrix. It is observed that modifications in the studied parameters (a-f) often lead to significant modulation of thermal conductance across the interface and, thus, showcases the role of interface tailoring and surface-carbon morphology toward thermal energy exchange. More importantly, the results provide key bounds and a realistic degree of variation to the interface thermal conductance values at fiber/matrix interfaces as a function of different surface-carbon features.

  4. Prediction of Initiation Site of Destruction of Flat Braided Carbon Fiber Composites Using HTS-SQUID Gradiometer

    NASA Astrophysics Data System (ADS)

    Shinyama, Y.; Hatsukade, Y.; Tanaka, S.; Takai, Y.; Aly-Hassan, M. S.; Nakai, A.; Hamada, H.

    Carbon fiber reinforced polymers (CFRPs) are composite materials with lightweight and high specific strength. As the braided CFRPs have continuous carbon-fiber bundles in their longitudinal direction, they are stronger than conventional CFRPs. In this study, we applied a current-injection-based NDE method using a HTS-SQUID gradiometer to the flat braided CFRPs with and without carbon nanotubes (CNTs), and estimated conditions of the carbon fibers while applying a step-by-step tensile load to the CFRPs. From the results, a possibility to predict an initiation site of the destruction in the braided CFRPs was demonstrated.

  5. Fatigue evaluation of composite-reinforced, integrally stiffened metal panels

    NASA Technical Reports Server (NTRS)

    Dumesnil, C. E.

    1973-01-01

    The fatigue behavior of composite-reinforced, integrally stiffened metal panels was investigated in combined metal and composite materials subjected to fatigue loading. The systems investigated were aluminum-graphite/epoxy, and aluminum-S glass/epoxy. It was found that the composite material would support the total load at limit stress after the metal had completely failed, and the weight of the composite-metal system would be equal to that of an all metal system which would carry the same total load at limit stress.

  6. Risk analysis approach. [of carbon fiber release

    NASA Technical Reports Server (NTRS)

    Huston, R. J.

    1979-01-01

    The assessment of the carbon fiber hazard is outlined. Program objectives, requirements of the risk analysis, and elements associated with the physical phenomena of the accidental release are described.

  7. Novel method for carbon nanofilament growth on carbon fibers

    SciTech Connect

    Phillips, Johathan; Luhrs, Claudia; Terani, Mehran; Al - Haik, Marwan; Garcia, Daniel; Taha, Mahmoud R

    2009-01-01

    Fiber reinforced structural composites such as fiber reinforced polymers (FRPs) have proven to be key materials for blast mitigation due to their enhanced mechanical performance. However, there is a need to further increase total energy absorption of the composites in order to retain structural integrity in high energy environments, for example, blast events. Research has shown that composite failure in high energy environments can be traced to their relatively low shear strength attributed to the limited bond strength between the matrix and the fibers. One area of focus for improving the strength of composite materials has been to create 'multi-scale' composites. The most common approach to date is to introduce carbon nanotubes into a more traditional composite consisting of epoxy with embedded micron scale fibers. The inclusion of carbon nanotubes (CNT) clearly toughens different matrices. Depositing CNT in brittle matrix increases stiffness by orders of magnitude. Currently, this approach to create multiscale composites is limited due to the difficulty of dispersing significant amounts of nanotubes. It has repeatedly been reported that phase separation occurs above relatively low weight percent loading (ca. 3%) due to the strong van der Waals forces between CNTs compared with that between CNT and polymer. Hence, the nanotubes tend to segregate and form inclusions. One means to prevent nanotube or nanofilament agglomeration is to anchor one end of the nanostructure, thereby creating a stable multi-phase structure. This is most easily done by literally growing the CNTs directly on micron scale fibers. Recently, CNT were grown on carbon fibers, both polyacrylonitrile- (PAN-) and pitch-based, by hot filament chemical vapor deposition (HFCVD) using H2 and CH4 as precursors. Nickel clusters were electrodeposited on the fiber surfaces to catalyze the growth and uniform CNT coatings were obtained on both the PAN- and pitch-based carbon fibers. Multiwalled CNTs with

  8. Photoconductivity of activated carbon fibers

    SciTech Connect

    Kuriyama, K.; Dresselhaus, M.S. )

    1990-08-01

    The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity. 54 refs., 11 figs., 3 tabs.

  9. Carbon fiber composite molecular sieves

    SciTech Connect

    Burchell, T.D.; Rogers, M.R.; Williams, A.M.

    1996-06-01

    The removal of CO{sub 2} is of significance in several energy applications. The combustion of fossil fuels, such as coal or natural gas, releases large volumes of CO{sub 2} to the environment. Several options exist to reduce CO{sub 2} emissions, including substitution of nuclear power for fossil fuels, increasing the efficiency of fossil plants and capturing the CO{sub 2} prior to emission to the environment. All of these techniques have the attractive feature of limiting the amount of CO{sub 2} emitted to the atmosphere, but each has economic, technical, or societal limitations. In the production of natural gas, the feed stream from the well frequently contains contaminants and diluents which must be removed before the gas can enter the pipeline distribution system. Notable amongst these diluent gasses is CO{sub 2}, which has no calorific value. Currently, the pipeline specification calls for <2 mol % CO{sub 2} in the gas. Gas separation is thus a relevant technology in the field of energy production. A novel separation system based on a parametric swing process has been developed that utilizes the unique combination of properties exhibited by our carbon fiber composite molecular sieve (CFCMS).

  10. Thermoplastic coating of carbon fibers

    NASA Technical Reports Server (NTRS)

    Edie, D. D.; Lickfield, G. C.; Allen, L. E.; Mccollum, J. R.

    1989-01-01

    A continuous powder coating system was developed for coating carbon fiber with LaRC-TPI (Langley Research Center-Thermoplastic Polyimide), a high-temperature thermoplastic polymide invented by NASA-Langley. The coating line developed used a pneumatic fiber spreader to separate the individual fibers. The polymer was applied within a recirculating powder coating chamber then melted using a combination of direct electrical resistance and convective heating to make it adhere to the fiber tow. The tension and speed of the line were controlled with a dancer arm and an electrically driven fiber wind-up and wind-off. The effects of heating during the coating process on the flexibility of the prepreg produced were investigated. The uniformity with which the fiber tow could be coated with polymer also was examined. Composite specimens were fabricated from the prepreg and tested to determine optimum process conditions. The study showed that a very uniform and flexible prepeg with up to 50 percent by volume polymer could be produced with this powder coating system. The coating line minimized powder loss and produced prepeg in lengths of up to 300 m. The fiber spreading was found to have a major effect on the coating uniformity and flexibility. Though test results showed low composite tensile strengths, analysis of fracture surfaces under scanning electron microscope indicated that fiber/matrix adhesion was adequate.

  11. Photoconductivity of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    Kuriyama, K.; Dresselhaus, M. S.

    1990-08-01

    The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity.

  12. High voltage spark carbon fiber detection system

    NASA Technical Reports Server (NTRS)

    Yang, L. C.

    1980-01-01

    The pulse discharge technique was used to determine the length and density of carbon fibers released from fiber composite materials during a fire or aircraft accident. Specifications are given for the system which uses the ability of a carbon fiber to initiate spark discharge across a high voltage biased grid to achieve accurate counting and sizing of fibers. The design of the system was optimized, and prototype hardware proved satisfactory in laboratory and field tests.

  13. Studies of the Surface Treatment and Sizing of Carbon Fiber Surfaces on the Mechanical Properties of Composites Containing Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Sherwood, Peter M. A.; Lease, Kevin B.; Locke, James E.; Tomblin, John S.; Wang, Youqi

    1996-01-01

    Carbon fiber reinforced composites are materials where carbon fibers are used to reinforce a matrix to produce a light and strong material with important applications in the aerospace industry. There are many aspects of the preparation of these materials that would benefit from a study which combines the research of groups involved in the production, testing and analysis of these materials, and studies of the basic surface chemistry involved. This final reports presents the results of a project that has developed a collaboration between groups in all three of the major research universities in the State of Kansas, and promises to lead to a collaborative program that covers the major aspects of composite development and application. Sherwood has provided initial fiber surface treatment and sizing together with fiber and composite surface analysis; Lease, Tomblin and Wang have worked together toward the goal of preparing pre-preg and fabrication of laminated panels; Locke has developed computational models to evaluate the effect of surface treatment (and chemistry) on mechanical properties; Lease, Tomblin and Wang have worked together to perform all necessary mechanical testing. The research has been focused on materials that would benefit the High Speed Civil Transport (HSCT) program. The group has visited Dr. Howard Maars and his colleagues at NASA Langley, and has focused their studies on the NASA requirements discussed in this meeting. An important development, requested by NASA scientists, has been the acquisition and study of K3B as a matrix material for the composites. The project has led to the successful acquisition and surface analysis of K3B, together with the successful deposition of this material onto surface oxidized carbon fibers. Mechanical testing, modelling and the construction of composite preparation equipment has been achieved during the grant period.

  14. Fracture criteria for discontinuously reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Rack, H. J.; Goree, J. G.; Albritton, J.; Ratnaparkhi, P.

    1988-01-01

    Summarized is the progress achieved during the period September 16, 1987 to August 15, l988 on NASA Grant NAG1-724, Fracture Criteria for Discontinuously Reinforced Metal Matrix Composites. Appended are copies of three manuscripts prepared under NASA funding during the performance period.

  15. Fracture criteria for discontinuously reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Rack, H. J.; Goree, J. G.; Albritton, J.; Ratnarparkhi, P.

    1988-01-01

    The effect of sample configuration on the details of initial crack propagation in discontinuously whisker reinforced aluminum metal matrix composites was investigated. Care was taken to allow direct comparison of fracture toughness values utilizing differing sample configurations and orientations, holding all materials variables constant, e.g., extrusion ration, heat treatment, and chemistry.

  16. 3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties

    PubMed Central

    Lewicki, James P.; Rodriguez, Jennifer N.; Zhu, Cheng; Worsley, Marcus A.; Wu, Amanda S.; Kanarska, Yuliya; Horn, John D.; Duoss, Eric B.; Ortega, Jason M.; Elmer, William; Hensleigh, Ryan; Fellini, Ryan A.; King, Michael J.

    2017-01-01

    Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response. PMID:28262669

  17. 3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties

    NASA Astrophysics Data System (ADS)

    Lewicki, James P.; Rodriguez, Jennifer N.; Zhu, Cheng; Worsley, Marcus A.; Wu, Amanda S.; Kanarska, Yuliya; Horn, John D.; Duoss, Eric B.; Ortega, Jason M.; Elmer, William; Hensleigh, Ryan; Fellini, Ryan A.; King, Michael J.

    2017-03-01

    Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.

  18. 3D-Printing of Meso-structurally Ordered Carbon Fiber/Polymer Composites with Unprecedented Orthotropic Physical Properties.

    PubMed

    Lewicki, James P; Rodriguez, Jennifer N; Zhu, Cheng; Worsley, Marcus A; Wu, Amanda S; Kanarska, Yuliya; Horn, John D; Duoss, Eric B; Ortega, Jason M; Elmer, William; Hensleigh, Ryan; Fellini, Ryan A; King, Michael J

    2017-03-06

    Here we report the first example of a class of additively manufactured carbon fiber reinforced composite (AMCFRC) materials which have been achieved through the use of a latent thermal cured aromatic thermoset resin system, through an adaptation of direct ink writing (DIW) 3D-printing technology. We have developed a means of printing high performance thermoset carbon fiber composites, which allow the fiber component of a resin and carbon fiber fluid to be aligned in three dimensions via controlled micro-extrusion and subsequently cured into complex geometries. Characterization of our composite systems clearly show that we achieved a high order of fiber alignment within the composite microstructure, which in turn allows these materials to outperform equivalently filled randomly oriented carbon fiber and polymer composites. Furthermore, our AM carbon fiber composite systems exhibit highly orthotropic mechanical and electrical responses as a direct result of the alignment of carbon fiber bundles in the microscale which we predict will ultimately lead to the design of truly tailorable carbon fiber/polymer hybrid materials having locally programmable complex electrical, thermal and mechanical response.

  19. Improved thermoplastic composite by alignment of vapor-grown carbon fiber

    NASA Astrophysics Data System (ADS)

    Kuriger, Rex Jerrald

    2000-10-01

    Vapor grown carbon fiber (VGCF) is a new and inexpensive carbon fiber produced by vapor deposition of hydrocarbons on metal catalysts. Unlike continuous conventional PAN or pitch-derived carbon fibers, VGCF is discontinuous with diameters of about 200 nanometers and lengths ranging from 10 to 200 micrometers. The microscopic size and random entanglement of the fibers create several problems when processing VGCF composites. It is particularly difficult to disperse the entangled fibers in the matrix and orient them along a preferred axis to provide directional reinforcement. This work introduces a technique to produce an improved polymeric composite by alignment of vapor grown carbon nano-fibers in a polypropylene matrix. A twin-screw extruder was used to shear mix and disperse the fibers in the polymer matrix. The composite mixtures were extruded through a converging-annular die that generates flow-induced fiber alignment along the extrusion direction. The effect that the various extrusion conditions have on the bulk properties of the extrudate was investigated. It was found that the extrusion process is strongly dependent on the fiber content of the composite. The extrusion pressure increased and the flow rate decreased with fiber volume fraction. The tensile strength and modulus for the composite samples varied with extrusion temperature and screw speed, and the void content increased with fiber volume fraction. It was shown that fiber alignment could be improved by increasing the residence time in the die channel and was verified using x-ray diffraction. The mechanical properties of the aligned samples increased with fiber content. Also, the tensile strength improved with greater fiber orientation; however, more fiber alignment had little affect on the modulus. To better predict the strength of these partially aligned fiber composites, an experimental and theoretical approach was introduced. The experimental data correspond reasonably well when compared with the

  20. Large-scale carbon fiber tests

    NASA Technical Reports Server (NTRS)

    Pride, R. A.

    1980-01-01

    A realistic release of carbon fibers was established by burning a minimum of 45 kg of carbon fiber composite aircraft structural components in each of five large scale, outdoor aviation jet fuel fire tests. This release was quantified by several independent assessments with various instruments developed specifically for these tests. The most likely values for the mass of single carbon fibers released ranged from 0.2 percent of the initial mass of carbon fiber for the source tests (zero wind velocity) to a maximum of 0.6 percent of the initial carbon fiber mass for dissemination tests (5 to 6 m/s wind velocity). Mean fiber lengths for fibers greater than 1 mm in length ranged from 2.5 to 3.5 mm. Mean diameters ranged from 3.6 to 5.3 micrometers which was indicative of significant oxidation. Footprints of downwind dissemination of the fire released fibers were measured to 19.1 km from the fire.

  1. Reinforcement of titanium by laser metal deposition

    NASA Astrophysics Data System (ADS)

    Sampedro, Jesús; Pérez, Irene; Cárcel, Bernabé; Amigó, Vicente; Sánchez, José María

    2010-09-01

    Pure commercial titanium is widely used because of its high corrosion resistance and lower cost compared with other titanium alloys, in particular when there is no high wear requirements. Nevertheless, the wear resistance is poor and surface damage occurs in areas under contact loadings. Laser melting deposition using a high power laser is a suitable technique for manufacturing precise and defect free coatings of a dissimilar material with higher wear and corrosion resistance. In this work a good understanding of laser metal deposition mechanisms allowed to obtain defect free coatings of Ti6Al4V and TiC metal matrix composite (MMC) using a flash lamp pumped Nd:YAG laser of 1 kW. A complete investigation of the process parameters is discussed and resultant wear and corrosion properties are shown. The results show the feasibility to apply the process for manufacturing, improving or repairing high added value components for a wide range of industrial sectors.

  2. Epoxy/Glass and Polyimide (LaRC(TradeMark) PETI-8)/Carbon Fiber Metal Laminates Made by the VARTM Process

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Loos, Alfred C.; Jensen, Brian J.; Britton, Sean M.; Tuncol, Goker; Long, Kai

    2010-01-01

    Recent work at NASA Langley Research Center (LaRC) has concentrated on developing new polyimide resin systems for advanced aerospace applications that can be processed without the use of an autoclave. Polyimide composites are very attractive for applications that require a high strength to weight ratio and thermal stability. Vacuum assisted resin transfer molding (VARTM) has shown the potential to reduce the manufacturing cost of composite structures. Fiber metal laminates (FML) made via this process with aluminum, glass fabric, and epoxy resins have been previously fabricated at LaRC. In this work, the VARTM process has been refined for epoxy/glass FMLs and extended to the fabrication of FM Ls with titanium/carbon fabric layers and a polyimide system developed at NASA, LARC(TradeMark) PETI-8. Resin flow pathways were introduced into the titanium foils to aid the infiltration of the polyimide resin. Injection temperatures in the range of 250-280 C were required to achieve the necessary VARTM viscosities (<10 Poise). Laminate quality and initial mechanical properties will be presented.

  3. Process Optimization of Bismaleimide (BMI) Resin Infused Carbon Fiber Composite

    NASA Technical Reports Server (NTRS)

    Ehrlich, Joshua W.; Tate, LaNetra C.; Cox, Sarah B.; Taylor, Brian J.; Wright, M. Clara; Faughnan, Patrick D.; Batterson, Lawrence M.; Caraccio, Anne J.; Sampson, Jeffery W.

    2013-01-01

    Engineers today are presented with the opportunity to design and build the next generation of space vehicles out of the lightest, strongest, and most durable materials available. Composites offer excellent structural characteristics and outstanding reliability in many forms that will be utilized in future aerospace applications including the Commercial Crew and Cargo Program and the Orion space capsule. NASA's Composites for Exploration (CoEx) project researches the various methods of manufacturing composite materials of different fiber characteristics while using proven infusion methods of different resin compositions. Development and testing on these different material combinations will provide engineers the opportunity to produce optimal material compounds for multidisciplinary applications. Through the CoEx project, engineers pursue the opportunity to research and develop repair patch procedures for damaged spacecraft. Working in conjunction with Raptor Resins Inc., NASA engineers are utilizing high flow liquid infusion molding practices to manufacture high-temperature composite parts comprised of intermediate modulus 7 (IM7) carbon fiber material. IM7 is a continuous, high-tensile strength composite with outstanding structural qualities such as high shear strength, tensile strength and modulus as well as excellent corrosion, creep, and fatigue resistance. IM7 carbon fiber, combined with existing thermoset and thermoplastic resin systems, can provide improvements in material strength reinforcement and deformation-resistant properties for high-temperature applications. Void analysis of the different layups of the IM7 material discovered the largest total void composition within the [ +45 , 90 , 90 , -45 ] composite panel. Tensile and compressional testing proved the highest mechanical strength was found in the [0 4] layup. This paper further investigates the infusion procedure of a low-cost/high-performance BMI resin into an IM7 carbon fiber material and the

  4. Study and modification of the reactivity of carbon fibers

    NASA Technical Reports Server (NTRS)

    Walker, P. L., Jr.; Ismail, I. M.; Mahajan, O. P.; Eapen, T. A.

    1980-01-01

    The reactivity to air of polyactylonitrile-based carbon fiber cloth was enhanced by the addition of metals to the cloth. The cloth was oxidized in 54 wt% nitric acid in order to increase the surface area of the cloth and to add carbonyl groups to the surface. Metal addition was then achieved by soaking the cloth in metal acetate solution to effect exchange between the metal carbon and hydrogen on the carbonyl groups. The addition of potassium, sodium, calcium and barium enhanced fiber cloth reactivity to air at 573 K. Extended studies using potassium addition showed that success in enhancing fiber cloth reactivity to air depends on: extent of cloth oxidation in nitric acid, time of exchange in potassium acetate solution and the thoroughness of removing metal acetate from the fiber pore structure following exchange. Cloth reactivity increases essentially linearly with increase in potassium addition via exchange.

  5. The assessment of metal fiber reinforced polymeric composites

    NASA Technical Reports Server (NTRS)

    Chung, Wenchiang R.

    1990-01-01

    Because of their low cost, excellent electrical conductivity, high specific strength (strength/density), and high specific modulus (modulus/density) short metal fiber reinforced composites have enjoyed a widespread use in many critical applications such as automotive industry, aircraft manufacturing, national defense, and space technology. However, little data has been found in the study of short metal fibrous composites. Optimum fiber concentration in a resin matrix and fiber aspect ratio (length-to-diameter ratio) are often not available to a user. Stress concentration at short fiber ends is the other concern when the composite is applied to a load-bearing application. Fracture in such composites where the damage will be initiated or accumulated is usually difficult to be determined. An experimental investigation is therefore carefully designed and undertaken to systematically evaluate the mechanical properties as well as electrical properties. Inconel 601 (nickel based) metal fiber with a diameter of eight microns is used to reinforce commercially available thermoset polyester resin. Mechanical testing such as tensile, impact, and flexure tests along with electrical conductivity measurements is conducted to study the feasibility of using such composites. The advantages and limitations of applying chopped metal fiber reinforced polymeric composites are also discussed.

  6. Thermophysical ESEM Characterization of Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Sue, Jiwoong; Ochoa, Ozden O.; Effinger, Michael R.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    Coefficients of thermal expansion (CTE) of carbon fibers create residual stresses in aggressive manufacturing and service environments. In this effort, environmental scanning electron microscope (ESEM) is used for in situ observations of a carbon fiber cross-section up to 1000 C in order to evaluate the much neglected transverse CTE. The perimeter of fiber cross-section is calculated with the Scion image processing program from images that were taken at every 100 C increments. CTE values are calculated by linear regression of the strain data based on the perimeter changes. Furthermore, through SEM, WDS and TEM observations, we are in the process of bringing an interactive rationale between CTE, crystallinity and surface roughness of carbon fibers.

  7. Hybrid solar cell on a carbon fiber

    NASA Astrophysics Data System (ADS)

    Grynko, Dmytro A.; Fedoryak, Alexander N.; Smertenko, Petro S.; Dimitriev, Oleg P.; Ogurtsov, Nikolay A.; Pud, Alexander A.

    2016-05-01

    In this work, a method to assemble nanoscale hybrid solar cells in the form of a brush of radially oriented CdS nanowire crystals around a single carbon fiber is demonstrated for the first time. A solar cell was assembled on a carbon fiber with a diameter of ~5-10 μm which served as a core electrode; inorganic CdS nanowire crystals and organic dye or polymer layers were successively deposited on the carbon fiber as active components resulting in a core-shell photovoltaic structure. Polymer, dye-sensitized, and inverted solar cells have been prepared and compared with their analogues made on the flat indium-tin oxide electrode.

  8. Heat Treated Carbon Fiber Material Selection Database

    NASA Technical Reports Server (NTRS)

    Effinger, M.; Patel, B.; Koenig, J.

    2008-01-01

    Carbon fibers are used in a variety high temperature applications and materials. However, one limiting factor in their transition into additional applications is an understanding of their functional properties during component processing and function. The requirements on the fibers are governed by the nature of the materials and the environments in which they will be used. The current carbon fiber vendor literature is geared toward the polymeric composite industry and not the ceramic composite industry. Thus, selection of carbon fibers is difficult, since their properties change as a function of heat treatment, processing or component operational temperature, which ever is greatest. To enable proper decisions to be made, a program was established wherein multiple fibers were selected and heat treated at different temperatures. The fibers were then examined for their physical and mechanical properties which are reported herein.

  9. Carbon-Fiber Brush Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Knowles, Timothy R.

    2004-01-01

    Velvetlike and brushlike pads of carbon fibers have been proposed for use as mechanically compliant, highly thermally conductive interfaces for transferring heat. A pad of this type would be formed by attaching short carbon fibers to either or both of two objects that one desires to place in thermal contact with each other. The purpose of using a thermal-contact pad of this or any other type is to reduce the thermal resistance of an interface between a heat source and a heat sink.

  10. Effects of carbon fibers on consumer products

    NASA Technical Reports Server (NTRS)

    Wise, R. A.; Lovett, C. D.

    1980-01-01

    The potential effects of carbon fibers on consumer products such as dishwashers, microwave ovens, and smoke detectors were investigated. The investigation was divided into two categories to determine the potential faults and hazards that could occur if fibers should enter the electrical circuits of the selected appliances. The categories were a fault analysis and a hazard analysis. Hazards considered were fire, flood, physical harm, explosion, and electrical shock. Electrical shock was found to be a possible occurrence related to carbon fibers. Faults were considered to be any effect on the performance of an appliance which would result in complaint or require service action.

  11. Three-dimensional carbon fibers and method and apparatus for their production

    DOEpatents

    Muradov, Nazim Z [Melbourne, FL

    2012-02-21

    This invention relates to novel three-dimensional (3D) carbon fibers which are original (or primary) carbon fibers (OCF) with secondary carbon filaments (SCF) grown thereon, and, if desired, tertiary carbon filaments (TCF) are grown from the surface of SCF forming a filamentous carbon network with high surface area. The methods and apparatus are provided for growing SCF on the OCF by thermal decomposition of carbonaceous gases (CG) over the hot surface of the OCF without use of metal-based catalysts. The thickness and length of SCF can be controlled by varying operational conditions of the process, e.g., the nature of CG, temperature, residence time, etc. The optional activation step enables one to produce 3D activated carbon fibers with high surface area. The method and apparatus are provided for growing TCF on the SCF by thermal decomposition of carbonaceous gases over the hot surface of the SCF using metal catalyst particles.

  12. Application of ceramic fibers to the manufacture of reinforced metal-matrix composites

    SciTech Connect

    Wielage, B.; Rahm, J.; Steinhaeuser, S.

    1995-12-31

    The application of the thermal spraying process is a new way to produce carbon fiber or Tyranno fiber reinforced aluminum matrix composites. Spreaded fiber rovings are enveloped in the matrix material with wire flame spraying. The advantage of the thermal spraying process is based in the low times for contacting between the fibers and the liquid matrix material. Chemical reactions on the interface fiber/matrix, which are caused by the decreasing of the fiber tensile strength, can be excluded. The thermal sprayed prepregs can be compressed to MMC by hot pressing process. This longfiber reinforced composites are used to increase f.e. casted components of motors. The aim of this research is the estimation of possibilities to applicate the wire flame spray process for prepreg manufacturing.

  13. Friction Behaviour of Polymeric Composite Materials Mixed with Carbon Fibers Having Different Orientations Layout

    NASA Astrophysics Data System (ADS)

    Caliman, R.

    2016-06-01

    This paper presents a study of the friction properties of polymeric composite materials reinforced with unidirectional carbon fibers having different stratified structure. So, the composites are complex and versatile materials but their behaviour in practice is not fully studied. For instance, these polymeric composite materials mixed with carbon fibers after being investigated in terms of wear, did not elucidate the effect of fiber orientation on wear properties. Is therefore necessary to investigate the effect of carbon fibers orientation on the friction-wear properties of the reinforced composite materials tested to abrasive and adhesive friction. Research work has been done with unidirectional composite materials having overlap 18 successive layers made from a polymeric resine and 60% of carbon fibers. The stratified structure was obtained by compressing multiple pre-impregnated strips, positioned manually. During this experimental work, three types of test samples were investigated: parallel, normal and anti-parallel, taking in consideration the carbon fibre orientation with respect to the sliding direction. The friction coefficient is computed function to the friction load and loading value. Also, the specific wear rate was calculated according to: the mass loss, density, the normal contact surface, the sliding distance and load rating.

  14. The Tensile Behavior of High-Strength Carbon Fibers.

    PubMed

    Langston, Tye

    2016-08-01

    Carbon fibers exhibit exceptional properties such as high stiffness and specific strength, making them excellent reinforcements for composite materials. However, it is difficult to directly measure their tensile properties and estimates are often obtained by tensioning fiber bundles or composites. While these macro scale tests are informative for composite design, their results differ from that of direct testing of individual fibers. Furthermore, carbon filament strength also depends on other variables, including the test length, actual fiber diameter, and material flaw distribution. Single fiber tensile testing was performed on high-strength carbon fibers to determine the load and strain at failure. Scanning electron microscopy was also conducted to evaluate the fiber surface morphology and precisely measure each fiber's diameter. Fiber strength was found to depend on the test gage length and in an effort to better understand the overall expected performance of these fibers at various lengths, statistical weak link scaling was performed. In addition, the true Young's modulus was also determined by taking the system compliance into account. It was found that all properties (tensile strength, strain to failure, and Young's modulus) matched very well with the manufacturers' reported values at 20 mm gage lengths, but deviated significantly at other lengths.

  15. Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Composites

    NASA Technical Reports Server (NTRS)

    Kang, Jin Ho; Cano, Roberto J.; Ratcliffe, James G.; Luong, Hoa; Grimsley, Brian W.; Siochi, Emilie J.

    2016-01-01

    For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strengthand stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Despite several attempts to solve these issues with the addition of carbon nanotubes (CNT) into polymer matrices, and/or by interleaving CNT sheets between conventional carbon fiber (CF) composite layers, there are still interfacial problems that exist between CNTs (or CF) and the resin. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing (double cantilever beam and end-notched flexure test). Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated. Interleaving CNT sheets significantly improved the in-plane (axial and perpendicular direction of CF alignment) thermal conductivity of the hybrid composite laminates by 50 - 400%.

  16. Thermal Properties of Hybrid Carbon Nanotube/Carbon Fiber Polymer

    NASA Technical Reports Server (NTRS)

    Kang, Jin Ho; Cano, Roberto J.; Luong, Hoa; Ratcliffe, James G.; Grimsley, Brian W.; Siochi, Emilie J.

    2016-01-01

    Carbon fiber reinforced polymer (CFRP) composites possess many advantages for aircraft structures over conventional aluminum alloys: light weight, higher strength- and stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low thermal and electrical conductivities of CFRP composites are deficient in providing structural safety under certain operational conditions such as lightning strikes. One possible solution to these issues is to interleave carbon nanotube (CNT) sheets between conventional carbon fiber (CF) composite layers. However, the thermal and electrical properties of the orthotropic hybrid CNT/CF composites have not been fully understood. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel (Registered Trademark) IM7/8852 prepreg. The CNT sheets were infused with a 5% solution of a compatible epoxy resin prior to composite fabrication. Orthotropic thermal and electrical conductivities of the hybrid polymer composites were evaluated. The interleaved CNT sheets improved the in-plane thermal conductivity of the hybrid composite laminates by about 400% and the electrical conductivity by about 3 orders of magnitude.

  17. Manufacturing of Nanocomposite Carbon Fibers and Composite Cylinders

    NASA Technical Reports Server (NTRS)

    Tan, Seng; Zhou, Jian-guo

    2013-01-01

    Pitch-based nanocomposite carbon fibers were prepared with various percentages of carbon nanofibers (CNFs), and the fibers were used for manufacturing composite structures. Experimental results show that these nanocomposite carbon fibers exhibit improved structural and electrical conductivity properties as compared to unreinforced carbon fibers. Composite panels fabricated from these nanocomposite carbon fibers and an epoxy system also show the same properties transformed from the fibers. Single-fiber testing per ASTM C1557 standard indicates that the nanocomposite carbon fiber has a tensile modulus of 110% higher, and a tensile strength 17.7% times higher, than the conventional carbon fiber manufactured from pitch. Also, the electrical resistance of the carbon fiber carbonized at 900 C was reduced from 4.8 to 2.2 ohm/cm. The manufacturing of the nanocomposite carbon fiber was based on an extrusion, non-solvent process. The precursor fibers were then carbonized and graphitized. The resultant fibers are continuous.

  18. Risk Assessment of Carbon Fiber Composite in Surface Transportation

    NASA Technical Reports Server (NTRS)

    Hathaway, W. T.; Hergenrother, K. M.

    1980-01-01

    The vulnerability of surface transportation to airborne carbon fibers and the national risk associated with the potential use of carbon fibers in the surface transportation system were evaluated. Results show airborne carbon fibers may cause failure rates in surface transportation of less than one per year by 1995. The national risk resulting from the use of carbon fibers in the surface transportation system is discussed.

  19. Characterization of electrospun lignin based carbon fibers

    NASA Astrophysics Data System (ADS)

    Poursorkhabi, Vida; Mohanty, Amar; Misra, Manjusri

    2015-05-01

    The production of lignin fibers has been studied in order to replace the need for petroleum based precursors for carbon fiber production. In addition to its positive environmental effects, it also benefits the economics of the industries which cannot take advantage of carbon fiber properties because of their high price. A large amount of lignin is annually produced as the byproduct of paper and growing cellulosic ethanol industry. Therefore, finding high value applications for this low cost, highly available material is getting more attention. Lignin is a biopolymer making about 15 - 30 % of the plant cell walls and has a high carbon yield upon carbonization. However, its processing is challenging due to its low molecular weight and also variations based on its origin and the method of separation from cellulose. In this study, alkali solutions of organosolv lignin with less than 1 wt/v% of poly (ethylene oxide) and two types of lignin (hardwood and softwood) were electrospun followed by carbonization. Different heating programs for carbonization were tested. The carbonized fibers had a smooth surface with an average diameter of less than 5 µm and the diameter could be controlled by the carbonization process and lignin type. Scanning electron microscopy (SEM) was used to study morphology of the fibers before and after carbonization. Thermal conductivity of a sample with amorphous carbon was 2.31 W/m.K. The electrospun lignin carbon fibers potentially have a large range of application such as in energy storage devices and water or gas purification systems.

  20. The transport properties of activated carbon fibers

    SciTech Connect

    di Vittorio, S.L. . Dept. of Materials Science and Engineering); Dresselhaus, M.S. . Dept. of Electrical Engineering and Computer Science Massachusetts Inst. of Tech., Cambridge, MA . Dept. of Physics); Endo, M. . Dept. of Electrical Engineering); Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons. 19 refs., 4 figs.

  1. Risk methodology overview. [for carbon fiber release

    NASA Technical Reports Server (NTRS)

    Credeur, K. R.

    1979-01-01

    Some considerations of risk estimation, how risk is measured, and how risk analysis decisions are made are discussed. Specific problems of carbon fiber release are discussed by reviewing the objective, describing the main elements, and giving an example of the risk logic and outputs.

  2. The Transport Properties of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  3. Interfacial engineering of the interphase between carbon fibers and vinyl ester resin

    NASA Astrophysics Data System (ADS)

    Xu, Lanhong

    Vinyl ester resins have been extensively used for the manufacture of low cost high performance composites. Carbon fibers are important reinforcement materials. The use of vinyl ester composites reinforced with carbon fibers requires an improvement in the fiber/matrix adhesion levels. The objectives of this study were to gain an understanding of the factors controlling interfacial adhesion between carbon fibers and vinyl ester resin; to model the contributions of the factors controlling fiber/matrix adhesion; and to provide an engineered and optimized interface between carbon fiber and vinyl ester for tailoring structurally efficient carbon fiber/vinyl ester composites. This work consists of three parts. Part I. A partially cross-linked DGEBA epoxy polymer sizing placed onto carbon fiber surface was found to be a beneficial interphase between the carbon fiber and vinyl ester resin resulting in an increase in fiber-matrix adhesion. The adhesion was evaluated as interfacial shear strength (IFSS) with micro-indentation. Nano-indentation and nano-scratch technique were used to investigate the gradient between this epoxy sizing and vinyl ester resin. An optimized thickness of this sizing was found and the mechanism by which this sizing improved adhesion was also investigated. A set of 2-D non-linear finite element models was set up for simulation of the micro-indentation process and consistent results were found between the experimental data and numerical results. It was found that the epoxy sizing formed more chemical bonds with the surface of the carbon fiber reinforcement and an interpenetrating interphase with the vinyl ester resin. The resulting interphase between vinyl ester matrix and epoxy sizing reduced the residual stress caused by the volume shrinkage of the vinyl ester after curing. Part II. Since it is known that the carbon fiber surface can interfere with the vinyl ester polymerization, the effects of preferential adsorption of the catalysts and styrene on

  4. Characterization of adhesion at carbon fiber-fluorinated epoxy interface and effect of environmental degradation

    NASA Astrophysics Data System (ADS)

    Dasgupta, Suman

    2011-12-01

    Carbon fiber reinforced polymers are excellent candidates for aerospace, automobile and other mobile applications due to their high specific strength and modulus. The most prominent aerospace application of carbon fiber composites in recent times is the Boeing 787 Dreamliner, which is the world's first major commercial airliner to extensively use composite materials. The critical issue, which needs to be addressed hereby, is long-term safety. Hence, long-term durability of composite materials in such applications becomes a point of concern. Conventional polymer matrices, such as thermosetting resins, which are used as matrix material in carbon fiber composites, are susceptible to degradation in the form of chemical corrosion, UV degradation and moisture, in severe environmental conditions. Fluorinated polymers offer a viable alternative as matrix material, due to their reduced susceptibility to environmental degradation. The epoxy system used in this study is fluorinated Tetra-glycidyl methylene di-aniline (6F-TGMDA), which was developed by polymer scientists at NASA Langley Research Center. The hydrophobic nature of this epoxy makes it a potential matrix material in aerospace applications. However, its compatibility in carbon fiber-reinforced composites remains to be investigated. This study aims to characterize the interfacial properties in carbon fiber reinforced fluorinated epoxy composites. Typical interfacial characterization parameters, like interfacial shear strength, estimated from the microbond test, proved to be inadequate in accurately estimating adhesion since it assumes a uniform distribution of stresses along the embedded fiber length. Also, it does not account for any residual stresses present at the interface, which might arise due to thermal expansion differences and Poisson's ratio differences of the fiber and matrix. Hence, an analytical approach, which calculates adhesion pressure at the interface, was adopted. This required determination of

  5. Experimental and analytical studies for the NASA carbon fiber risk assessment

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Various experimental and analytical studies performed for the NASA carbon fiber risk assessment program are described with emphasis on carbon fiber characteristics, sensitivity of electrical equipment and components to shorting or arcing by carbon fibers, attenuation effect of carbon fibers on aircraft landing aids, impact of carbon fibers on industrial facilities. A simple method of estimating damage from airborne carbon fibers is presented.

  6. Vapor grown carbon fiber for space thermal management systems

    NASA Technical Reports Server (NTRS)

    Lake, Max L.; Hickok, J. Kyle; Brito, Karren K.; Begg, Lester L.

    1990-01-01

    Research that uses a novel, highly graphitic, vapor grown carbon fiber (VGCF) to fabricate composites for thermal management applications is described. These VGCF/Carbon composites have shown a specific thermal conductivity with values of twenty-to-ten times that of copper in the 500-900 K temperature range needed for waste heat management. It is concluded that development of this high specific thermal conductivity composite for thermal radiator panels will provide the foundation for a reevaluation of space power designs heretofore limited by the mass of waste heat dissipation systems. Further, it is suggested that through optimization of fiber handling and composite processing, thermal conductivities exceeding 1000 W/m-K (at 300 K) are achievable in composites reinforced with VGCF.

  7. Development and Characterization of Healable Carbon Fiber Composites with a Reversibly Cross Linked Polymer

    SciTech Connect

    Ghezzo, Fabrizia; Smith, David R.; Starr, Tatiana N.; Perram, Timothy; Starr, Anthony F.; Darlington, Thomas K.; Baldwin, Richard K.; Oldenburg, Steven J.

    2010-10-18

    Carbon fiber reinforced polymer (CFRP) laminates with remendable cross-linked polymeric matrices were fabricated using a modified resin transfer mold (RTM) technique. The healable composite resin, bis-maleimide tetrafuran (2MEP4F), was synthesized by mixing two monomers, furan (4F) and maleimide (2MEP), at elevated temperatures. The fast kinetic rate of the reaction of polymer constituents requires a fast injection of the healable resin into the carbon fiber preform. The polymer viscosity as a function of time and temperature was experimentally quantified in order to optimize the fabrication of the composite material and to guarantee a uniform flow of the resin through the reinforcement. The method was validated by characterizing the thermo-mechanical properties of the polymerized 2MEP4F. Additionally, the thermo-mechanical properties of the remendable CFRP material were studied.

  8. Performance Enhancement Using Selective Reinforcement for Metallic Single- and Multi-Pin Loaded Holes

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Seshadri, Banavara R.

    2005-01-01

    An analysis based investigation of aluminum with metal matrix composite selectively reinforced single- and multi-hole specimens was performed and their results compared with results from geometrically comparable non-reinforced specimens. All reinforced specimens exhibited a significant increase in performance. Performance increase of up to 170 percent was achieved. Specimen failure modes were consistent with results from reinforced polymeric matrix composite specimens. Localized reinforcement application (circular) proved as effective as a broader area (strip) reinforcement. Also, selective reinforcement is an excellent method of increasing the performance of multi-hole specimens.

  9. Surface Characterization of Carbon Fiber Polymer Composites and Aluminum Alloys After Laser Interference Structuring

    NASA Astrophysics Data System (ADS)

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles D.; Daniel, Claus

    2016-07-01

    The increasing use of carbon fiber-reinforced polymer matrix composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (1) structuring of the AL 5182 surface, (2) removal of the resin layer on top of carbon fibers, and (3) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg—T83 epoxy, 5 ply thick, 0°/90° plaques were used. The effects of laser fluence, scanning speed, and number of shots-per-spot were investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope imaging were used to study the effect of the laser processing on the surface morphology. It was found that an effective resin ablation and a low density of broken fibers for CFPC specimens was attained using laser fluences of 1-2 J/cm2 and number of 2-4 pulses per spot. A relatively large area of periodic line structures due to energy interference were formed on the aluminum surface at laser fluences of 12 J/cm2 and number of 4-6 pulses per spot.

  10. Surface characterization of carbon fiber polymer composites and aluminum alloys after laser interference structuring

    DOE PAGES

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; ...

    2016-05-03

    Here, the increasing use of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (a) structuring of the AL 5182 surface, (b) removal of the resin layer on top of carbon fibers, and (c) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg - T83 epoxy, 5 ply thick, 0/90o plaques weremore » used. The effect of laser fluence, scanning speed, and number of shots-per-spot was investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope (SEM) imaging were used to study the effect of the laser processing on surface morphology.« less

  11. Surface characterization of carbon fiber polymer composites and aluminum alloys after laser interference structuring

    SciTech Connect

    Sabau, Adrian S.; Greer, Clayton M.; Chen, Jian; Warren, Charles David; Daniel, Claus

    2016-05-03

    Here, the increasing use of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) and aluminum alloys as lightweight materials in the automotive and aerospace industries demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using an Nd:YAG laser in a two-beam interference setup, enabling the (a) structuring of the AL 5182 surface, (b) removal of the resin layer on top of carbon fibers, and (c) structuring of the carbon fibers. CFPC specimens of T700S carbon fiber, Prepreg - T83 epoxy, 5 ply thick, 0/90o plaques were used. The effect of laser fluence, scanning speed, and number of shots-per-spot was investigated on the removal rate of the resin without an excessive damage of the fibers. Optical micrographs, 3D imaging, and scanning electron microscope (SEM) imaging were used to study the effect of the laser processing on surface morphology.

  12. Adhesion of preceramic inorganic polymer coatings to carbon fibers

    SciTech Connect

    Chaudhry, T.M.; Drzal, L.T.; Ho, H.; Laine, R.

    1996-12-31

    To determine whether the preceramic inorganic polymer coating can provide not only the thermal oxidative protection during both processing and use in metal matrix composites or ceramic matrix composites but also the appropriate composite properties, it is desirable to know how and at what point in the thermal processing cycle the coating-carbon fiber interface undergoes changes that affect the interfacial adhesion and failure mode. Also, it is important to identify the locus of interfacial failure i.e. between fiber and coating or between coating and matrix. This work is directed at determining the interfacial changes and the locus of failure in order to optimize both the coating chemistry and the conversion process. The characteristics of the benchmark interface coating material, silicon oxycarbide, SiO{sub x}C{sub y} or black glass have been studied. SiO{sub x}C{sub y} was chosen because (1) SiO{sub x}C{sub y} is amorphous, (2) it is possible to prepare very well-defined materials, where the chemistry and the evolution of the material with time and temperature are known in detail, and (3) SiO{sub x}C{sub y} is a matrix material used in commercial composites. It has been shown that these coatings are effective in increasing the oxidation resistance of the carbon fibers themselves.

  13. Graphene nanoribbons as an advanced precursor for making carbon fiber.

    PubMed

    Xiang, Changsheng; Behabtu, Natnael; Liu, Yaodong; Chae, Han Gi; Young, Colin C; Genorio, Bostjan; Tsentalovich, Dmitri E; Zhang, Chenguang; Kosynkin, Dmitry V; Lomeda, Jay R; Hwang, Chih-Chau; Kumar, Satish; Pasquali, Matteo; Tour, James M

    2013-02-26

    Graphene oxide nanoribbons (GONRs) and chemically reduced graphene nanoribbons (crGNRs) were dispersed at high concentrations in chlorosulfonic acid to form anisotropic liquid crystal phases. The liquid crystal solutions were spun directly into hundreds of meters of continuous macroscopic fibers. The relationship of fiber morphology to coagulation bath conditions was studied. The effects of colloid concentration, annealing temperature, spinning air gap, and pretension during annealing on the fibers' performance were also investigated. Heat treatment of the as-spun GONR fibers at 1500 °C produced thermally reduced graphene nanoribbon (trGNR) fibers with a tensile strength of 378 MPa, Young's modulus of 36.2 GPa, and electrical conductivity of 285 S/cm, which is considerably higher than that in other reported graphene-derived fibers. This better trGNR fiber performance was due to the air gap spinning and annealing with pretension that produced higher molecular alignment within the fibers, as determined by X-ray diffraction and scanning electron microscopy. The specific modulus of trGNR fibers is higher than that of the commercial general purpose carbon fibers and commonly used metals such as Al, Cu, and steel. The properties of trGNR fibers can be further improved by optimizing the spinning conditions with higher draw ratio, annealing conditions with higher pretensions, and using longer flake GONRs. This technique is a new high-carbon-yield approach to make the next generation carbon fibers based on solution-based liquid crystal phase spinning.

  14. Carbon fiber manufacturing via plasma technology

    DOEpatents

    Paulauskas, Felix L.; Yarborough, Kenneth D.; Meek, Thomas T.

    2002-01-01

    The disclosed invention introduces a novel method of manufacturing carbon and/or graphite fibers that avoids the high costs associated with conventional carbonization processes. The method of the present invention avoids these costs by utilizing plasma technology in connection with electromagnetic radiation to produce carbon and/or graphite fibers from fully or partially stabilized carbon fiber precursors. In general, the stabilized or partially stabilized carbon fiber precursors are placed under slight tension, in an oxygen-free atmosphere, and carbonized using a plasma and electromagnetic radiation having a power input which is increased as the fibers become more carbonized and progress towards a final carbon or graphite product. In an additional step, the final carbon or graphite product may be surface treated with an oxygen-plasma treatment to enhance adhesion to matrix materials.

  15. Thermoplastic coated carbon fibers for textile preforms

    NASA Technical Reports Server (NTRS)

    Allen, L. E.; Edie, D. D.; Lickfield, G. C.; Mccollum, J. R.

    1988-01-01

    A continuous process for producing prepreg from carbon fiber and thermoplastic matrix is described. After the tow has been spread using a pneumatic device, the process utilizes a fluidized bed to apply thermoplastic powder to the bundle. Finally, direct electrical heating of the coated fiber tow melts the polymer on the individual fibers, creating a uniform and extremely flexible prepreg. The efficiency of the process was evaluated during initial trials in which a thermoplastic polyimide, LaRC-TPI, was applied to T-300, 3K (3000 filament) carbon fiber tow. The physical properties of unidirectional composite specimens fabricated from this prepreg were measured, and the matrix uniformity and void content of the samples was determined. The results of these evaluations are detailed and discussed.

  16. Binder for Carbon-Fiber Coating

    NASA Technical Reports Server (NTRS)

    Dowler, W. L.; Ramohalli, K. N.; Yen, S. P. S.; Mueller, W. A.; Harper, J.

    1984-01-01

    Insoluble, even coating formed by soaking in polyacrylic acid. Carbon fiber material prepared by soaking in solution of 20 percent polyacrylic acid in water. Material blotted and dried at 120 degrees C for at least 2 hours. Dried material reacted with boiling aqueous solution of calcium acetate. Treated material removed from boiling solution, blotted, dried at 120 degrees C, washed with distilled water, and dried again.

  17. Characterization of electrospun lignin based carbon fibers

    SciTech Connect

    Poursorkhabi, Vida; Mohanty, Amar; Misra, Manjusri

    2015-05-22

    The production of lignin fibers has been studied in order to replace the need for petroleum based precursors for carbon fiber production. In addition to its positive environmental effects, it also benefits the economics of the industries which cannot take advantage of carbon fiber properties because of their high price. A large amount of lignin is annually produced as the byproduct of paper and growing cellulosic ethanol industry. Therefore, finding high value applications for this low cost, highly available material is getting more attention. Lignin is a biopolymer making about 15 – 30 % of the plant cell walls and has a high carbon yield upon carbonization. However, its processing is challenging due to its low molecular weight and also variations based on its origin and the method of separation from cellulose. In this study, alkali solutions of organosolv lignin with less than 1 wt/v% of poly (ethylene oxide) and two types of lignin (hardwood and softwood) were electrospun followed by carbonization. Different heating programs for carbonization were tested. The carbonized fibers had a smooth surface with an average diameter of less than 5 µm and the diameter could be controlled by the carbonization process and lignin type. Scanning electron microscopy (SEM) was used to study morphology of the fibers before and after carbonization. Thermal conductivity of a sample with amorphous carbon was 2.31 W/m.K. The electrospun lignin carbon fibers potentially have a large range of application such as in energy storage devices and water or gas purification systems.

  18. Prestressed Carbon Fiber Composite Overwrapped Gun Tube

    DTIC Science & Technology

    2008-10-15

    DD-MM-YYYY) 15-10-2008 2. REPORT TYPE FINAL 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE PRESTRESSED CARBON FIBER COMPOSITE...mismatch between the steel substrate and the composite jacket causing a gap, and the lack of favorable prestress in the jacket. Dealing with these...eliminated, and a favorable prestress has been achieved. A 120mm barrel has been manufactured using this process with IM7 fibers in a PEEK matrix and

  19. The properties of metal-reinforced glass ionomer materials.

    PubMed

    Chung, K H

    1993-01-01

    The physical properties and bond strengths of two glass ionomer materials reinforced with silver and amalgam alloy powders were compared with those of a conventional material from the same manufacture as well as two commercially available products. The diametral tensile strength, hardness and bonding strength are improved with the addition of either commercial available silver particles or fabricated high-copper amalgam alloy powders to the glass. Simple mixture of the metal or alloy powders with the glass ionomer cement seems to be feasible to improve the properties of the regular cement. However, further studies in formulating an optimal composition of metal or alloy, setting characteristics and long-term clinical evaluation are necessary before proposing uses for this new material.

  20. Glass Fiber Reinforced Metal Pressure Vessel Design Guide

    NASA Technical Reports Server (NTRS)

    Landes, R. E.

    1972-01-01

    The Engineering Guide presents curves and general equations for safelife design of lightweight glass fiber reinforced (GFR) metal pressure vessels operating under anticipated Space Shuttle service conditions. The high composite vessel weight efficiency is shown to be relatively insensitive to shape, providing increased flexibility to designers establishing spacecraft configurations. Spheres, oblate speroids, and cylinders constructed of GFR Inconel X-750, 2219-T62 aluminum, and cryoformed 301 stainless steel are covered; design parameters and performance efficiencies for each configuration are compared at ambient and cryogenic temperature for an operating pressure range of 690 to 2760 N/sq cm (1000 to 4000 psi). Design variables are presented as a function of metal shell operating to sizing (proof) stress ratios for use with fracture mechanics data generated under a separate task of this program.

  1. Synthesis of carbon fibers and activated carbon fibers from coal liquids

    SciTech Connect

    Fei, Y.Q.; Derbyshire, F.; Jagtoyen, M.; Kimber, G.

    1994-12-31

    The production and application of low-cost, general purpose carbon fibers and activated fibers are emerging technologies with exciting potential, although at present their cost is too high to find widespread use. Production and R and D have been limited and to data, only a small range of precursors has been studied: petroleum pitches, coal extracts and coal tar pitches. Both processing costs and the properties of the fiber products are dependent on the nature of the starting material. Commercial precursors have been limited to the pitches produced from high temperature pyrolysis or cracking processes and are similar in composition and molecular structure. Suitable coal-based precursors can be produced with a wide range of composition, and at moderate cost, by methods such as low temperature carbonization, solvent extraction, hydropyrolysis and mild coal liquefaction. It is of interest to investigate the synthesis of carbon fibers and activated carbon fibers from precursors of different origins to elucidate the influence of precursor materials on fiber formation and processing, and their structure and properties. It is also of practical importance to understand the relationships between the type of starting materials (for example, coals) and the processing methods, and the properties of fiber precursors that can be produced from them. In the present study, the authors describe the synthesis of carbon fibers and activated carbon fibers from the products of the first stage of coal liquefaction.

  2. Effect of Reinforcement Architecture on Fracture of Selectively Reinforced Metallic Compact Tension Specimens

    NASA Technical Reports Server (NTRS)

    Abada, Christopher H.; Farley, Gary L.; Hyer, Michael W.

    2006-01-01

    A computer-based parametric study of the effect of reinforcement architectures on fracture response of aluminum compact-tension (CT) specimens is performed. Eleven different reinforcement architectures consisting of rectangular and triangular cross-section reinforcements were evaluated. Reinforced specimens produced between 13 and 28 percent higher fracture load than achieved with the non-reinforced case. Reinforcements with blunt leading edges (rectangular reinforcements) exhibited superior performance relative to the triangular reinforcements with sharp leading edges. Relative to the rectangular reinforcements, the most important architectural feature was reinforcement thickness. At failure, the reinforcements carried between 58 and 85 percent of the load applied to the specimen, suggesting that there is considerable load transfer between the base material and the reinforcement.

  3. Designing the Structure of Carbon Fibers for Optimal Mechanical Properties

    SciTech Connect

    Ozcan, Soydan; Vautard, Frederic; Naskar, Amit K

    2014-01-01

    Carbon fiber manufacturing follows generic processing steps: formation of thermoplastic fibers, stabilization, and carbonization. The final structures and end properties of the carbon fiber can differ significantly depending on the precursor chemistry and the associated processing sciences. Polyacrylonitrile (PAN) and mesophase pitch are the predominant precursors used in the production of carbon fibers. PAN-based carbon fibers consist of nanocrystalline graphitic domains typically 1.5 5 nm in size surrounded by amorphous carbon; in contrast, pitch-based carbon fibers are 10 50 nm crystallites with the graphitic (002) planes mostly aligned parallel to the fiber axis. It has been seen that the skin core structure of PAN-based carbon fibers plays a significant role in their mechanical properties. Designing a more homogenous carbon fiber microstructure by controlling the starting polymer and process parameters results in a different set of tensile strengths and elastic moduli. In this study the microstructural defect distribution (0.1 200 nm), measured by small-angle X-ray scattering, was shown to be directly related to the tensile strength of the carbon fibers. Here the formation of carbon structures from various polymer precursors is reviewed. Such a comprehensive understanding offers the opportunity to design carbon fiber microstructures with improved properties and to ultimately create new types of carbon fibers from alternative precursors at reduced cost.

  4. Carbon fiber production at low temperatures from polyacrylonitrile

    NASA Technical Reports Server (NTRS)

    Cagliostro, D. E.

    1980-01-01

    Recent safety considerations have sought to lower the electrical conductivity of carbon fibers. Carbon fibers produced from polyacrylonitrile at low carbonization temperatures (600-900 C) possess low electrical conductivity but do not possess adequate strength. Low-temperature processes are described which improve fiber strength but do not increase electrical conductivity substantially. The processes result in a carbon fiber with nearly twice the tensile strength compared to the old process. Process development and its effect on fiber properties are reported.

  5. Electrochemical capacitors utilizing low surface area carbon fiber

    SciTech Connect

    Lipka, S.M.

    1997-12-01

    The performance of electrochemical capacitors containing different commercial carbon fibers is reviewed. High specific capacitances (ca. 300 F/g) are obtained with low surface area carbon fiber (<1 m2/g) using a proprietary activation process. Capacitance is primarily achieved through pseudocapacitance resulting from surface functional groups. The performance of these devices is dependent on the type of carbon fiber, its carbon content, aspect ratio and microstructure. These devices can achieve high cycle life (ca. 100k) without significant loss in capacitance.

  6. Carbon Fiber Foam Composites and Methods for Making the Same

    NASA Technical Reports Server (NTRS)

    Leseman, Zayd Chad (Inventor); Atwater, Mark Andrew (Inventor); Phillips, Jonathan (Inventor)

    2014-01-01

    Exemplary embodiments provide methods and apparatus of forming fibrous carbon foams (FCFs). In one embodiment, FCFs can be formed by flowing a fuel rich gas mixture over a catalytic material and components to be encapsulated in a mold to form composite carbon fibers, each composite carbon fiber having a carbon phase grown to encapsulate the component in situ. The composite carbon fibers can be intertwined with one another to form FCFs having a geometry according to the mold.

  7. A novel surface modification of carbon fiber for high-performance thermoplastic polyurethane composites

    NASA Astrophysics Data System (ADS)

    Zhang, Yuanyuan; Zhang, Yizhen; Liu, Yuan; Wang, Xinling; Yang, Bin

    2016-09-01

    Properties of carbon fiber (CF) reinforced composites depend largely on the interfacial bonding strength between fiber and the matrix. In the present work, CF was grafted by 4,4‧-diphenylmethane diisocyanate (MDI) molecules after electrochemical oxidation treatment. The existence of functional groups introduced to the fiber surface and the changes of surface roughness were confirmed by FTIR, AFM, XPS, SEM and Raman spectroscopy. To evaluate the possible applications of this surface modification of carbon fiber, we examined the mechanical properties as well as the friction and wear performance of pristine CF and MDI-CF reinforced thermoplastic polyurethane (TPU) composites with 5-30 wt.% fiber contents, and found that the mechanical properties of TPU composites were all significantly improved. It is remarkable that when fiber content was 30 wt.%, the tensile strength of TPU/MDI-CF was increased by 99.3%, which was greater than TPU/CF (53.2%), and the friction loss of TPU/MDI-CF was decreased by 49.09%. The results of DMA and SEM analysis indicated the positive effects of MDI modification on the interfacial bonding between fibers and matrix. We believed that this simple and effective method could be used to the development of surface modified carbon fiber for high-performance TPU.

  8. A novel carbon fiber based porous carbon monolith

    SciTech Connect

    Burchell, T.D.; Klett, J.W.; Weaver, C.E.

    1995-06-01

    A novel porous carbon material based on carbon fibers has been developed. The material, when activated, develops a significant micro- or mesopore volume dependent upon the carbon fiber type utilized (isotropic pitch or polyacrylonitrile). The materials will find applications in the field of fluid separations or as a catalyst support. Here, the manufacture and characterization of our porous carbon monoliths are described. A novel adsorbent carbon composite material has been developed comprising carbon fibers and a binder. The material, called carbon fiber composite molecular sieve (CFCMS), was developed through a joint research program between Oak Ridge National Laboratory (ORNL) and the University of Kentucky, Center for Applied Energy Research (UKCAER).

  9. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, Toni L.

    1992-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  10. Creep behavior of tungsten fiber reinforced niobium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grobstein, T. L.

    1989-01-01

    Tungsten fiber reinforced niobium metal matrix composites were evaluated for use in space nuclear power conversion systems. The composite panels were fabricated using the arc-spray monotape technique at the NASA Lewis Research Center. The creep behavior of W/Nb composite material was determined at 1400 and 1500 K in vacuum over a wide range of applied loads. The time to reach 1 percent strain, the time to rupture, and the minimum creep rate were measured. The W/Nb composites exceeded the properties of monolithic niobium alloys significantly even when compared on a strength to density basis. The effect of fiber orientation on the creep strength also was evaluated. Kirkendall void formation was observed at the fiber/matrix interface; the void distribution differed depending on the fiber orientation relative to the stress axis. A relationship was found between the fiber orientation and the creep strength.

  11. Thermomechanical fatigue cracking in fiber reinforced metal-matrix composites

    NASA Astrophysics Data System (ADS)

    Bao, G.; McMeeking, R. M.

    1995-09-01

    A theoretical model is developed for thermomechanical fatigue cracking in fiber reinforced metal-matrix composites. Interfacial debonding is assumed to occur readily, allowing fibers to slide relative to the matrix resisted by a uniform shear stress. The fibers therefore bridge any matrix crack which develops. The crack bridging traction law is obtained, including the effect of thermal expansion mismatch between the fiber and the matrix and a temperature dependence of the frictional shear stress. Any combination of thermal and mechanical cycling is considered as long as the slip zone along the fiber increases in length monotonically during each increment of cycling. However, for clarity, the results are presented in terms of in-phase and out-of-phase cycling of the thermal and mechanical loads at the same frequency. For each case, the stress distributions in the bridging zone as well as the stress intensity factors at the crack tip are computed for relevant regimes of the thermal and mechanical loading conditions. Predictions are made of the matrix fatigue crack growth under combined thermal and mechanical loading conditions. It is found that when the thermal expansion coefficient of the fiber is less than that of the matrix, a significant increase in the crack growth rate results in out-of-phase thermomechanical fatigue. On the other hand, there is decreased tendency for fibers to fail in this case. For in-phase thermomechanical fatigue, the crack growth rate is reduced but the stress in the fiber is larger than that due to mechanical loading alone, resulting in an increased tendency for fiber failure. The implications for life prediction for fiber reinforced metal-matrix composites are discussed.

  12. Mechanical Properties, Surface Structure, and Morphology of Carbon Fibers Pre-heated for Liquid Aluminum Infiltration

    NASA Astrophysics Data System (ADS)

    Kachold, Franziska S.; Kozera, Rafal; Singer, Robert F.; Boczkowska, Anna

    2016-04-01

    To efficiently produce carbon fiber-reinforced aluminum on a large scale, we developed a special high-pressure die casting process. Pre-heating of the fibers is crucial for successful infiltration. In this paper, the influence of heating carried out in industrial conditions on the mechanical properties of the fibers was investigated. Therefore, polyacrylonitrile-based high-tensile carbon fiber textiles were heated by infrared emitters in an argon-rich atmosphere to temperatures between 450 and 1400 °C. Single fiber tensile tests revealed a decrease in tensile strength and strain at fracture. Young's modulus was not affected. Scanning electron microscopy identified cavities on the fiber surface as the reason for the decrease in mechanical properties. They were caused by the attack of atmospheric oxygen. The atomic structure of the fibers did not change at any temperature, as x-ray diffraction confirmed. Based on these data, the pre-heating for the casting process can be optimized.

  13. Design and construction of a carbon fiber gondola for the SPIDER balloon-borne telescope

    NASA Astrophysics Data System (ADS)

    Soler, J. D.; Ade, P. A. R.; Amiri, M.; Benton, S. J.; Bock, J. J.; Bond, J. R.; Bryan, S. A.; Chiang, C.; Contaldi, C. C.; Crill, B. P.; Doré, O. P.; Farhang, M.; Filippini, Jeffrey P.; Fissel, L. M.; Fraisse, A. A.; Gambrel, A. E.; Gandilo, N. N.; Golwala, S.; Gudmundsson, J. E.; Halpern, M.; Hasselfield, M.; Hilton, G. C.; Holmes, W. A.; Hristov, V. V.; Irwin, K. D.; Jones, W. C.; Kermish, Z. K.; Kuo, C.-L.; MacTavish, C. J.; Mason, P. V.; Megerian, K. G.; Moncelsi, L.; Morford, T.; Nagy, J. M.; Netterfield, C. B.; Rahlin, A. S.; Reintsema, C. D.; Ruhl, J. E.; Runyan, M. C.; Shariff, J. A.; Trangsrud, A.; Tucker, C.; Tucker, R. S.; Turner, A. D.; Weber, A. C.; Wiebe, D. V.; Young, E. Y.

    2014-07-01

    We introduce the light-weight carbon fiber and aluminum gondola designed for the Spider balloon-borne telescope. Spider is designed to measure the polarization of the Cosmic Microwave Background radiation with unprecedented sensitivity and control of systematics in search of the imprint of inflation: a period of exponential expansion in the early Universe. The requirements of this balloon-borne instrument put tight constrains on the mass budget of the payload. The Spider gondola is designed to house the experiment and guarantee its operational and structural integrity during its balloon-borne flight, while using less than 10% of the total mass of the payload. We present a construction method for the gondola based on carbon fiber reinforced polymer tubes with aluminum inserts and aluminum multi-tube joints. We describe the validation of the model through Finite Element Analysis and mechanical tests.

  14. Carbon fiber behavior in an enclosed volume

    NASA Technical Reports Server (NTRS)

    Harvey, M. C.

    1979-01-01

    Tests were performed to evaluate the behavior of single carbon fibers existing in an enclosed space such as a room of a building. Three general phenomena were explored: the concentration decay rate of a fiber-charged room, the degree of uniform mixing of fibers within a room, and the effects of fibers being redisseminated off deposition surfaces within a room. The results were required in understanding the ratio of total indoor fiber exposure to total outdoor fiber exposure, a quantity essential to risk analysis. Results indicate that decay rate is predictable within acceptable limits and that homogeneous mixing can always be assumed. Some factors of redissemination are identified and effects discussed.

  15. Carbon fibers: Thermochemical recovery from advanced composite materials and activation to an adsorbent

    NASA Astrophysics Data System (ADS)

    Staley, Todd Andrew

    This research addresses an expanding waste disposal problem brought about by the increasing use of advanced composite materials, and the lack of technically and environmentally viable recycling methods for these materials. A thermochemical treatment process was developed and optimized for the recycling of advanced composite materials. Counter-current gasification was employed for the treatment of carbon fiber reinforced-epoxy resin composite wastes. These materials were treated, allowing the reclamation of the material's valuable components. As expected in gasification, the organic portion of the waste was thermochemically converted to a combustible gas with small amounts of organic compounds that were identified by GC/MS. These compounds were expected based on data in the literature. The composites contain 70% fiber reinforcement, and gasification yielded approximately 70% recovered fibers, representing nearly complete recovery of fibers from the waste. Through SEM and mechanical testing, the recovered carbon fibers were found to be structurally and mechanically intact, and amenable to re-use in a variety of applications, some of which were identified and tested. In addition, an application was developed for the carbon fiber component of the waste, as an activated carbon fiber adsorbent for the treatment of wastewaters. This novel class of adsorbent was found to have adsorption rates, for various organic molecules, up to a factor of ten times those of commercial granular activated carbon, and adsorption capacities similar to conventional activated carbons. Overall, the research addresses an existing environmental waste problem, employing a thermochemical technique to recycle and reclaim the waste. Components of the reclaimed waste material are then employed, after further modification, to address other existing and potential environmental waste problems.

  16. Effect of sign-variable thermocycling on the mechanical properties of carbon-fiber plastics with various layups

    NASA Astrophysics Data System (ADS)

    Khitrov, V. V.; Mungalov, D. D.; Sukhanov, A. V.; Lapotkin, V. A.

    1993-01-01

    An economic method for the ST of carbon-fiber-reinforced plastics is proposed in this study. It is established as a result of investigations of the mechanical properties of carbon-fiber-reinforced plastics with different layups, which are subjected to ST in the range to 100 cycles, that in the majority of cases, the number and duration of thermal cycles has no effect on the stiffness and strength in tension, compression, bending, and shear. The effect of number of thermal cycles was manifested only on the stiffness in tension and bending and also on the tensile, compressive, and bending strengths of the material with the obliquely reinforced structure loaded in the direction of the diagonal. It is permissible to use the dynamic method to assess variations in the stiffness of a material subjected to ST.

  17. Multifunctional Carbon Fiber Ionization Mass Spectrometry.

    PubMed

    Wu, Meng-Xi; Wang, Hao-Yang; Zhang, Jun-Ting; Guo, Yin-Long

    2016-10-04

    A carbon fiber ionization (CFI) technique was developed for the mass spectrometric analysis of various organic compounds with different polarities. The design of the CFI technique was based on the good compatibility and dispersion of samples and solutions in different solvents on carbon fiber. As a fast, convenient, and versatile ionization method, CFI-MS is especially efficient for analyzing many low/nonpolar organic compounds, such as polycyclic aromatic hydrocarbons, long-chain aliphatic aldehydes, sensitive steroids, terpenoids, and organometallic compounds. Some of these compounds may not be well-analyzed by electrospray ionization or electron ionization mass spectrometry. On the basis of our experimental results, the major ion formation mechanism of CFI-MS was suggested to involve desorption in a steam-distillation-like process, and then, ionization occurred mainly via corona discharge under high voltage. CFI-MS could not only work alone but also be coupled with separation techniques. It works well when coupled with supercritical fluid chromatography (SFC) as well as in the analysis of exhaled human air. The high flexibility and versatility of CFI-MS has extended its applications in many areas, such as fast chemical screening, clinical testing, and forensic analysis.

  18. An overview of long fiber reinforced thermoplastics

    SciTech Connect

    Bockstedt, R.J.; Skarlupka, R.J.

    1995-12-01

    Long fiber reinforced thermoplastics (LFRTP) are a class of injection molding materials that extend the physical property envelope of thermoplastics polymers. These materials are manufactured by pulling continuous fiber tows through a thermoplastic polymer melt in a specialized processing die. The strands are subsequently cooled and chopped into pellets of equal length. LFRTP materials are available in virtually every common thermoplastic resin with glass, aramid, stainless steel, or carbon fiber reinforcement at levels up to 60% by weight. Unlike short fiber reinforced thermoplastics manufactured by conventional screw compounding processes, LFRTP exhibit simultaneous improvements in both flexural modulus and impact resistance. Improvements in load transfer, creep resistance at elevated temperatures, and dimensional stability can also be attributed to the long fiber network formed in the molded part. This unique combination of properties makes LFRTP the material of choice for replacement of metal structural assemblies in many automotive, industrial, consumer and recreational applications.

  19. Application of composites to the selective reinforcement of metallic aerospace structures

    NASA Technical Reports Server (NTRS)

    Brooks, W. A., Jr.; Mathauser, E. E.; Pride, R. A.

    1973-01-01

    The use of composite materials to selectively reinforce metallic structures provides a low-cost way to reduce weight and a means of minimizing the risks usually associated with the introduction of new materials. An overview is presented of the NASA Langley Research Center programs to identify the advantages and to develop the potential of the selective reinforcement approach to the use of composites. These programs have shown that selective reinforcement provides excellent strength and stiffness improvements to metallic structures. Significant weight savings can be obtained in a cost effective manner. Flight service programs which have been initiated to validate further the merits of selective reinforcement are described.

  20. A novel carbon fiber based porous carbon monolith

    SciTech Connect

    Burchell, T.D.; Klett, J.W.; Weaver, C.E.

    1995-07-01

    A novel porous carbon material based on carbon fibers has been developed. The material, when activated, develops a significant micro- or mesopore volume dependent upon the carbon fiber type utilized (isotropic pitch or polyacrylonitrile). The materials will find applications in the field of fluid separations or as a catalyst support. Here, the manufacture and characterization of our porous carbon monoliths are described.

  1. Carbon-fiber low-voltage electron guns

    SciTech Connect

    Drori, R.; Jerby, E.

    1995-12-31

    Carbon-fiber cathodes am used in cold electron-guns in our laboratory. They operate in low-voltage (< 10 kV) free-electron maser and cyclotron-resonance maser experiments. The paper presents I-V characteristics of various carbon-fiber electron-guns and show results of the corresponding maser experiments.

  2. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites.

    PubMed

    Wang, Z; Georgarakis, K; Nakayama, K S; Li, Y; Tsarkov, A A; Xie, G; Dudina, D; Louzguine-Luzgin, D V; Yavari, A R

    2016-04-12

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

  3. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-04-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses.

  4. Microstructure and mechanical behavior of metallic glass fiber-reinforced Al alloy matrix composites

    PubMed Central

    Wang, Z.; Georgarakis, K.; Nakayama, K. S.; Li, Y.; Tsarkov, A. A.; Xie, G.; Dudina, D.; Louzguine-Luzgin, D. V.; Yavari, A. R.

    2016-01-01

    Metallic glass-reinforced metal matrix composites are an emerging class of composite materials. The metallic nature and the high mechanical strength of the reinforcing phase offers unique possibilities for improving the engineering performance of composites. Understanding the structure at the amorphous/crystalline interfaces and the deformation behavior of these composites is of vital importance for their further development and potential application. In the present work, Zr-based metallic glass fibers have been introduced in Al7075 alloy (Al-Zn-Mg-Cu) matrices using spark plasma sintering (SPS) producing composites with low porosity. The addition of metallic glass reinforcements in the Al-based matrix significantly improves the mechanical behavior of the composites in compression. High-resolution TEM observations at the interface reveal the formation of a thin interdiffusion layer able to provide good bonding between the reinforcing phase and the Al-based matrix. The deformation behavior of the composites was studied, indicating that local plastic deformation occurred in the matrix near the glassy reinforcements followed by the initiation and propagation of cracks mainly through the matrix. The reinforcing phase is seen to inhibit the plastic deformation and retard the crack propagation. The findings offer new insights into the mechanical behavior of metal matrix composites reinforced with metallic glasses. PMID:27067824

  5. Preliminary experimental study of a carbon fiber array cathode

    NASA Astrophysics Data System (ADS)

    Li, An-kun; Fan, Yu-wei

    2016-08-01

    The preliminary experimental results of a carbon fiber array cathode for the magnetically insulated transmission line oscillator (MILO) operations are reported. When the diode voltage and diode current were 480 kV and 44 kA, respectively, high-power microwaves with a peak power of about 3 GW and a pulse duration of about 60 ns were obtained in a MILO device with the carbon fiber array cathode. The preliminary experimental results show that the shot-to-shot reproducibility of the diode current and the microwave power is stable until 700 shots. No obvious damage or deterioration can be observed in the carbon fiber surface morphology after 700 shots. Moreover, the cathode performance has no observable deterioration after 700 shots. In conclusion, the maintain-free lifetime of the carbon fiber array cathode is more than 700 shots. In this way, this carbon fiber array cathode offers a potential replacement for the existing velvet cathode.

  6. Influence of Expanding Monomer on Carbon Fiber Reinforced Epoxy Composites

    DTIC Science & Technology

    1990-06-01

    copolymerize. Embedded single filament tensile test results were compared for samples containing DGEBA -epoxy cured with m-phenylene (mPDA) wi_% those for...stage before the DNSOC begins to copolymerize. Embedded single filament tensile test results were compared for samples containing DGEBA -epoxy cured...Dr. Piggott incorporated DNSOC into DGEBA (the diglycidyl ether of bisphenol A) type epoxies and found that epoxy susceptibility to water was reduced

  7. KuDGR- Dual Gridded Carbon Fiber Reinforced Plastic Reflector

    NASA Astrophysics Data System (ADS)

    Ihle, Alexander; Reichmann, O.; Lori, M.; Nathrath, N.; Pereira, C.; Linke, S.; Rinous, P.

    2014-06-01

    In the frame of an ESA-funded TRP activity HPS GmbH, together with INVENT GmbH and INEGI, has developed an advanced concept for dual gridded reflectors. The target frequency band is the Ku-band requiring high in-orbit thermo-elastic stability. It is a follow-on of the previous KaDGR [1] activity. The concept concerns the polarisation grid of the front and rear reflector. The grids are connected by a full CFRP monolithic peripheral ring. The demonstrator has an overall diameter of 1.4 x 1.2 m and a weight of only 4.23 kg. The design of this concept allows for smaller and larger reflectors.In the following we will present the results of the different development steps and current status of the TRP activity.

  8. Microstructure/Property Relationships for Carbon Fiber Reinforced Aluminum Alloys.

    DTIC Science & Technology

    1985-07-25

    hypodermic syringe and blunted needle . After mounting the fiber, the card containing the fiber is inserted into the test fixture (figure 2). The edges... theory suggesting that this may not necessarily be the case [211. They showed that a weak interface may, 14 in fact, lead to improved composite properties...agree, at least in principle , with Ochai and Murakami’s theory and composites produced from Cornie’s fibers proved to be quite strong longitudinally

  9. Efficient Nondestructive Evaluation of Prototype Carbon Fiber Reinforced Structures

    NASA Technical Reports Server (NTRS)

    Russell, Samuel S.; Walker, James L.; Workman, Gary; Thom, Robert (Technical Monitor)

    2002-01-01

    Thermography inspection is an optic based technology that can reduce the time and cost required to inspect propellant tanks or aero structures fabricated from composite materials. Usually areas identified as suspect in the thermography inspection are examined with ultrasonic methods to better define depth, orientation and the nature of the anomaly. This combination of nondestructive evaluation techniques results in a rapid and comprehensive inspection of composite structures. Examples of application of this inspection philosophy to prototype will be presented. Methods organizing the inspection and evaluating the results will be considered.

  10. Deformation Behavior during Processing in Carbon Fiber Reinforced Plastics

    NASA Astrophysics Data System (ADS)

    Ogihara, Shinji; Kobayashi, Satoshi

    In this study, we manufacture the device for measuring the friction between the prepreg curing process and subjected to pull-out tests with it The prepreg used in this study is a unidirectional carbon/epoxy, produced by TORAY designation of T700SC/2592.When creating specimens 4-ply prepregs are prepared and laminated. The 2-ply prepregs in the middle are shifted 50mm. In order to measure the friction between the prepreg during the cure process, we simulate the environment in the autoclave in the device, and we experiment in pull-out test. Test environment simulating temperature and pressure. The speed of displacement should be calculated by coefficient of thermal expansions (CTE). By calculation, 0.05mm/min gives the order of magnitude of displacement speed. In this study, 3 pull-out speeds are used: 0.01, 0.05 and 0.1mm/min. The specimen was heated by a couple of heaters, and we controlled the heaters with a temperature controller along the curing conditions of the prepreg. We put pressure using 4 bolts. Two strain gages were put on the bolt. We can understand the load applied to the specimen from the strain of the bolt. Pressure was adjusted the tightness of the bolt according to curing conditions. By using such a device, the pull-out test performed by tensile testing machine while adding temperature and pressure. During the 5 hours, we perform experiments while recording the load and stroke. The shear stress determined from the load and the stroke, and evaluated.

  11. Waste polyvinylchloride derived pitch as a precursor to develop carbon fibers and activated carbon fibers.

    PubMed

    Qiao, W M; Yoon, S H; Mochida, I; Yang, J H

    2007-01-01

    Polyvinylchloride (PVC) was successfully recycled through the solvent extraction from waste pipe with an extraction yield of ca. 86%. The extracted PVC was pyrolyzed by a two-stage process (260 and 410 degrees C) to obtain free-chlorine PVC based pitch through an effective removal of chlorine from PVC during the heat-treatment. As-prepared pitch (softening point: 220 degrees C) was spun, stabilized, carbonized into carbon fibers (CFs), and further activated into activated carbon fibers (ACFs) in a flow of CO2. As-prepared CFs show comparable mechanical properties to commercial CFs, whose maximum tensile strength and modulus are 862 MPa and 62 GPa, respectively. The resultant ACFs exhibit a high surface area of 1200 m2/g, narrow pore size distribution and a low oxygen content of 3%. The study provides an effective insight to recycle PVC from waste PVC and develop a carbon precursor for high performance carbon materials such as CFs and ACFs.

  12. Quasi-Static Indentation Analysis of Carbon-Fiber Laminates.

    SciTech Connect

    Briggs, Timothy; English, Shawn Allen; Nelson, Stacy Michelle

    2015-12-01

    A series of quasi - static indentation experiments are conducted on carbon fiber reinforced polymer laminates with a systematic variation of thicknesses and fixture boundary conditions. Different deformation mechanisms and their resulting damage mechanisms are activated b y changing the thickn ess and boundary conditions. The quasi - static indentation experiments have been shown to achieve damage mechanisms similar to impact and penetration, however without strain rate effects. The low rate allows for the detailed analysis on the load response. Moreover, interrupted tests allow for the incremental analysis of various damage mechanisms and pr ogressions. The experimentally tested specimens are non - destructively evaluated (NDE) with optical imaging, ultrasonics and computed tomography. The load displacement responses and the NDE are then utilized in numerical simulations for the purpose of model validation and vetting. The accompanying numerical simulation work serves two purposes. First, the results further reveal the time sequence of events and the meaning behind load dro ps not clear from NDE . Second, the simulations demonstrate insufficiencies in the code and can then direct future efforts for development.

  13. Pitch-based short carbon fiber. Final report

    SciTech Connect

    Lin, S.S.

    1991-12-01

    Short carbon fiber manufactured from coal tar pitch by Osaka Gas Co. is examined by chemical composition analysis, X-ray powder diffraction, optical microscope, and electron spectroscopic techniques. The present analytical results are compared with the data obtainable from other sources. Owing to the low cost of the short fiber, it is recommended that the fiber could be used for a wide variety of reinforcement applications such as, cement/concrete mixtures, polymer composites, and high temperature materials. Processing includes the mechanical separation of mesophase microbeads of three to 30 micron diameters from crude coal tar during three heat treatment stages. The mesophases obtained are then subjected to solvent extraction, hydrogenation, and polymerization to yield isotropic and anisotropic pitches suitable for melt spinning. The short fiber is fabricated from isotropic pitch by the rotary gas jet method, and the process yields a higher quality fiber as compared to other melt spinning methods. The most important feature is that this process is highly cost effective.

  14. Predicting Mechanical Properties of Metal Matrix Syntactic Foams Reinforced with Ceramic Spheres

    DTIC Science & Technology

    2012-01-01

    reinforced with Al2O3 spheres of various sizes, size ranges, and wall thickness to sphere diameter ratios show good agreement. Introduction Metal matrix...treatments reinforced with Al2O3 spheres of various sizes, size ranges, and wall thickness to sphere diameter ratios show good agreement. 15. SUBJECT...longitudinally and not laterally (i.e. no barreling: ) until all hollow reinforcements are crushed. Assuming the wall thickness of the hollow

  15. Carbon fiber electrode for redox flow battery

    SciTech Connect

    Inoue, M.; Tsuzuki, Y.; Iizuka, Y.; Shimada, M.

    1987-03-01

    Advanced secondary batteries have been developed as electrical energy storage systems for use in electrical utility load-levelling and stand-alone photovoltaic installations. Among them, the redox flow system based on aqueous iron and chromium redox couple is one of the most advanced. An important key to its feasibility is electrode fabrication. Woven and non-woven fabrics of carbon fibers have been used as thin but three dimensional electrodes of the redox flow system in view of their electric conductivity, chemical stability, and economy. One of the electrochemical problems of iron-chromium redox battery related to the electrode is the slow reaction rate of reduction and oxidation of chromium complex ion. As the electron transfer rate of chromium complex ion is lower than that of iron ion, the voltaic efficiency of the battery tends to decrease.

  16. Friction and wear of rare earths modified carbon fibers filled PTFE composite under dry sliding condition

    NASA Astrophysics Data System (ADS)

    Qian-qian, Shangguan; Xian-hua, Cheng

    2007-09-01

    Carbon fibers (CF) were surface treated with air-oxidation and rare earths (RE), respectively. The friction and wear properties of polytetrafluoroethylene (PTFE) composites filled with differently surface treated carbon fibers, sliding against GCr15 steel under dry sliding condition, were investigated on a block-on-ring M-2000 tribometer. Experimental results revealed that RE treatment largely reduced the friction and wear of CF reinforced PTFE (CF/PTFE) composites. The RE treated composite exhibited the lowest friction and wear under dry sliding. Scanning electron microscopy (SEM) investigation of worn surfaces and transfer films of CF/PTFE composites showed that RE treated CF/PTFE composites had the smoothest worn surface under given load and sliding speed, and a continuous and uniform transfer film formed on the counterface. X-ray photoelectron spectroscopy (XPS) study of carbon fiber surface showed that the oxygen concentration was obviously increased after RE treatment, and more carboxyl groups were introduced onto CF surfaces after RE treatment. The increase in the amount of oxygen-containing groups increased the interfacial adhesion between CF and PTFE matrix, and accordingly increased the tribological properties of the composite.

  17. Piezo-Electrochemical Energy Harvesting with Lithium-Intercalating Carbon Fibers.

    PubMed

    Jacques, Eric; Lindbergh, Göran; Zenkert, Dan; Leijonmarck, Simon; Kjell, Maria Hellqvist

    2015-07-01

    The mechanical and electrochemical properties are coupled through a piezo-electrochemical effect in Li-intercalated carbon fibers. It is demonstrated that this piezo-electrochemical effect makes it possible to harvest electrical energy from mechanical work. Continuous polyacrylonitrile-based carbon fibers that can work both as electrodes for Li-ion batteries and structural reinforcement for composites materials are used in this study. Applying a tensile force to carbon fiber bundles used as Li-intercalating electrodes results in a response of the electrode potential of a few millivolts which allows, at low current densities, lithiation at higher electrode potential than delithiation. More electrical energy is thereby released from the cell at discharge than provided at charge, harvesting energy from the mechanical work of the applied force. The measured harvested specific electrical power is in the order of 1 μW/g for current densities in the order of 1 mA/g, but this has a potential of being increased significantly.

  18. Tensile and fatigue behavior of Al-based metal matrix composites reinforced with continuous carbon or alumina fibers: Part I. Quasi-unidirectional composites

    NASA Astrophysics Data System (ADS)

    Jacquesson, M.; Girard, A.; Vidal-Sétif, M.-H.; Valle, R.

    2004-10-01

    The thermomechanical (dilatometric, tensile, and fatigue) behavior of Al-based metal matrix composites (MMCs) is investigated. These composites are reinforced by quasi-unidirectional (quasi-UD) woven fabric preforms with 90 pct of continuous fibers in the longitudinal direction and 10 pct in the transverse direction. The two composite systems investigated feature a highly ductile matrix (AU2: Al-2Cu wt pct) with a strongly bonded fiber-matrix interface (N610 alumina fibers) and an alloyed, high-strength matrix (A357: Al-7Si-0.6Mg wt pct) with a weak fiber-matrix interface (K139 carbon fibers). Microstructural investigation of the tested specimens has permitted identification of the specific characteristics of these composites: undulation of the longitudinal bundles, presence of the straight transverse bundles, interply shearing, and role of brittle phases. Moreover, simple semiquantitative models ( e.g., interply shearing) have enabled explanation of the specific mechanical behavior of these quasi-UD composites, which exhibit high tensile and fatigue strengths, as compared with the corresponding pure UD composites. Knowledge of the specific characteristics and mechanical behavior of these quasi-UD composites will facilitate the further investigation of the (0, ±45, 90 deg) quasi-UD laminates (Part II). At a more theoretical viewpoint, the specific geometry and behavior of these quasi-UD composites allows exacerbation of fatigue mechanisms, even more intense than in “model” composites.

  19. Solidification of particle-reinforced metal-matrix composites

    NASA Astrophysics Data System (ADS)

    Hanumanth, G. S.; Irons, G. A.

    1996-08-01

    The solidification behavior of ceramic particle-reinforced metal-matrix composites (MMCs) is different from that of the bare matrix, not only because of the presence of the ceramic particles, but also due to their redistribution in the melt that results in nonhomogeneous thermophysical properties. The MMCs comprised of 10-to 15-μm SiC particles of varying volume fractions, dispersed uniformly in a modified aluminum A356 alloy by the melt stirring technique, were solidified unidirectionally in a thermocouple-instrumented cylindrical steel mold. The cooling rates were continually monitored by measuring temperatures at different depths in the melt, and the solidified MMCs were sectioned into disks and chemically analyzed for SiC volume fraction. The results point out that the cooling rate increased with increasing volume fraction of SiC particles. A small increase in the bulk SiC volume fraction of the cast MMC was observed due to particle settling during solidification. A one-dimensional enthalpy model of MMC solidification was formulated, wherein particle settling occurring in the solidifying matrix was coupled to the enthalpy equation by means of the Richardson-Zaki hindered settling correlation. A comparative study of simulations with experiments suggested that the thermal response of SiC particles used in this study was similar to that of single crystals, and their presence increased the effective thermal conductivity of the composite.

  20. Durability-Based Design Properties of Reference Crossply Carbon-Fiber Composite

    SciTech Connect

    Corum, J.M.

    2001-04-16

    This report provides recommended durability-based design properties and criteria for a crossply carbon-fiber composite for possible automotive structural applications. Although the composite utilized aerospace-grade carbon-fiber reinforcement, it was made by a rapid-molding process suitable for high-volume automotive use. The material is the first in a planned progression of candidate composites to be characterized as part of an Oak Ridge National Laboratory project entitled Durability of Carbon-Fiber Composites. The overall goal of the project, which is sponsored by the U.S. Department of Energy's Office of Advanced Automotive Technologies and is closely coordinated with the Advanced Composites Consortium, is to develop durability-driven design data and criteria to assure the long-term integrity of carbon-fiber-based composite systems for automotive structural applications. The composite addressed in this report is a ({+-}45{degree})3S crossply consisting of continuous Thornel T300 fibers in a Baydur 420 IMR urethane matrix. This composite is highly anisotropic with two dominant fiber orientations--0/90{degree} and {+-}45{degree}. Properties and models were developed for both orientations. This document is in two parts. Part 1 provides design data and correlations, while Part 2 provides the underlying experimental data and models. The durability issues addressed include the effects of short-time, cyclic, and sustained loadings; temperature; fluid environments; and low-energy impacts (e.g., tool drops and kickups of roadway debris) on deformation, strength, and stiffness. Guidance for design analysis, time-independent and time-dependent allowable stresses, rules for cyclic loadings, and damage-tolerance design guidance are provided.

  1. LOW COST PRODUCTION OF CARBON FIBERS FROM LIGNIN MATERIALS

    SciTech Connect

    Gallego, Nidia C; Baker, Darren A; Baker, Frederick S

    2009-01-01

    The DOE Vehicle Technologies-funded work at ORNL is directed to the development of processes for the low cost production of carbon fibers. The objective of the project is to develop more energy-efficient, cost-effective processes for production of carbon fibers for use in composite materials for vehicles, which would substantially reduce vehicle weight, increase vehicle fuel economy, and result in lower CO2 emissions. Carbon fibers have the potential for substantial weight saving in vehicles because of their remarkable high strength, high modulus, and low density. However, carbon fibers are currently too expensive for large scale automotive use, which necessitates a large reduction in the cost of commercial grade fiber from about $20/lb to $5-7/lb. Lignin, a renewable resource material, has significant potential as a precursor material for low cost carbon fiber production. In this paper we report on progress to demonstrate the melt-spinning of precursor fibers from various lignin sources, the subsequent processing of the lignin precursor fibers into carbon fibers, and carbon fiber properties.

  2. Carbon nanotubes on carbon fibers: Synthesis, structures and properties

    NASA Astrophysics Data System (ADS)

    Zhang, Qiuhong

    The interface between carbon fibers (CFs) and the resin matrix in traditional high performance composites is characterized by a large discontinuity in mechanical, electrical, and thermal properties which can cause inefficient energy transfer. Due to the exceptional properties of carbon nanotubes (CNTs), their growth at the surface of carbon fibers is a promising approach to controlling interfacial interactions and achieving the enhanced bulk properties. However, the reactive conditions used to grow carbon nanotubes also have the potential to introduce defects that can degrade the mechanical properties of the carbon fiber (CF) substrate. In this study, using thermal chemical vapor deposition (CVD) method, high density multi-wall carbon nanotubes have been successfully synthesized directly on PAN-based CF surface without significantly compromising tensile properties. The influence of CVD growth conditions on the single CF tensile properties and carbon nanotube (CNT) morphology was investigated. The experimental results revealed that under high temperature growth conditions, the tensile strength of CF was greatly decreased at the beginning of CNT growth process with the largest decrease observed for sized CFs. However, the tensile strength of unsized CFs with CNT was approximately the same as the initial CF at lower growth temperature. The interfacial shear strength of CNT coated CF (CNT/CF) in epoxy was studied by means of the single-fiber fragmentation test. Results of the test indicate an improvement in interfacial shear strength with the addition of a CNT coating. This improvement can most likely be attributed to an increase in the interphase yield strength as well as an improvement in interfacial adhesion due to the presence of the nanotubes. CNT/CF also offers promise as stress and strain sensors in CF reinforced composite materials. This study investigates fundamental mechanical and electrical properties of CNT/CF using nanoindentation method by designed

  3. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2000-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  4. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2001-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  5. Electronic equipment vulnerability to fire released carbon fibers

    NASA Technical Reports Server (NTRS)

    Pride, R. A.; Mchatton, A. D.; Musselman, K. A.

    1980-01-01

    The vulnerability of electronic equipment to damage by carbon fibers released from burning aircraft type structural composite materials was investigated. Tests were conducted on commercially available stereo power amplifiers which showed that the equipment was damaged by fire released carbon fibers but not by the composite resin residue, soot and products of combustion of the fuel associated with burning the carbon fiber composites. Results indicate that the failure rates of the equipment exposed to the fire released fiber were consistent with predictions based on tests using virgin fibers.

  6. Surface characterization of LDEF carbon fiber/polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Grammer, Holly L.; Wightman, James P.; Young, Philip R.; Slemp, Wayne S.

    1995-01-01

    XPS (x-ray photoelectron spectroscopy) and SEM (scanning electron microscopy) analysis of both carbon fiber/epoxy matrix and carbon fiber/polysulfone matrix composites revealed significant changes in the surface composition as a result of exposure to low-earth orbit. The carbon 1s curve fit XPS analysis in conjunction with the SEM photomicrographs revealed significant erosion of the polymer matrix resins by atomic oxygen to expose the carbon fibers of the composite samples. This erosion effect on the composites was seen after 10 months in orbit and was even more obvious after 69 months.

  7. Modelling of Indirect Laser-induced Thin-film Ablation of Epoxy for Local Exposing of Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Emonts, Michael; Fischer, Kai; Schmitt, Stefan; Schares, Richard Ludwig

    Laser radiation is used as enabling technology for intrinsic joining of high-strength CFRP laminates and fiber-reinforced thermoplastic injection moulding compounds by exposure of surface-near carbon fibers. Short-pulsed NIR laser sources represent an acceptable compromise with respect to ablation performance, remote process capability by use of compact 3D scanner and the capability for closed-loop process control. However, using such a laser source means also minimizing heat-affected zones (HAZ). Based on literature research about laser ablation of thin metal films, heat flow at CFRP and thermo-mechanical behavior in FRP by pyrolysis, an analytical model was generated for thin-film ablation of cured epoxy resins at the surface of CFRP laminates by lift-off of resin chips. A comparison between simulation and experimental results confirms the capability of the model to predict the exposure area and the HAZ with deviations below 15%. Threshold fluences for the HAZ (>1 J/cm2) and the resin ablation (>3 J/cm2) have been confirmed.

  8. Graphene quantum dots derived from carbon fibers.

    PubMed

    Peng, Juan; Gao, Wei; Gupta, Bipin Kumar; Liu, Zheng; Romero-Aburto, Rebeca; Ge, Liehui; Song, Li; Alemany, Lawrence B; Zhan, Xiaobo; Gao, Guanhui; Vithayathil, Sajna Antony; Kaipparettu, Benny Abraham; Marti, Angel A; Hayashi, Takuya; Zhu, Jun-Jie; Ajayan, Pulickel M

    2012-02-08

    Graphene quantum dots (GQDs), which are edge-bound nanometer-size graphene pieces, have fascinating optical and electronic properties. These have been synthesized either by nanolithography or from starting materials such as graphene oxide (GO) by the chemical breakdown of their extended planar structure, both of which are multistep tedious processes. Here, we report that during the acid treatment and chemical exfoliation of traditional pitch-based carbon fibers, that are both cheap and commercially available, the stacked graphitic submicrometer domains of the fibers are easily broken down, leading to the creation of GQDs with different size distribution in scalable amounts. The as-produced GQDs, in the size range of 1-4 nm, show two-dimensional morphology, most of which present zigzag edge structure, and are 1-3 atomic layers thick. The photoluminescence of the GQDs can be tailored through varying the size of the GQDs by changing process parameters. Due to the luminescence stability, nanosecond lifetime, biocompatibility, low toxicity, and high water solubility, these GQDs are demonstrated to be excellent probes for high contrast bioimaging and biosensing applications.

  9. Carbon Fibers from Chicken Feather Keratin

    NASA Astrophysics Data System (ADS)

    Miller, Melissa E.; Wool, Richard

    2006-03-01

    As the availability of synthetic and fossil-fuel based resources is becoming limited, bio-based materials offer an environmentally friendly alternative. Chicken feathers remain a huge agricultural waste. The feathers are comprised of approximately 97% keratin, but are currently used only to enrich animal feed. However, this usage is becoming a problem with the spread of diseases such as Bovine Spongiform Encephalopathy, commonly called ``Mad Cow Disease.'' The hollow, microcrystalline, oriented keratin feather fibers offer a novel, low cost approach to producing carbon fibers through controlled pyrolysis. Carbonized feather fibers (CFF) were prepared by first heating to 225 ^oC (below the melting point)in N2 for 26 hours to crosslink and stabilize the fiber structure; then carbonization occurred by increasing the temperature to 450 ^oC for two more hours. The resulting CFF were hollow, stiff and strong and had an affine 80% weight loss, which is near the theoretical value for the C-content of keratin. Initial studies showed that a composite with the CFF and an epoxidized soybean oil (AESO) gave an improved fiber modulus ECFF of order 13.5--66.1 GPa. With continued research, the goals are to increase the stiffness of the feathers to 100 GPa, while increasing the strength in the range of 5-10 GPa.

  10. Oxygen Reactivity of a Carbon Fiber Composite

    SciTech Connect

    Marshall, Theron Devol; Pawelko, Robert James; Anderl, Robert Andrew; Smolik, Galen Richard

    2002-09-01

    Carbon Fiber Composites (CFCs) are often suggested as armor material for the first wall of a fusion plasma chamber due to carbon's low atomic number, high thermal conductivity, and high melting point. However, carbon is chemically reactive in air and will react with ingress air during a Loss of Vacuum Accident and release tritium fuel that has been retained in the carbon. Tritium mobilization and carbon monoxide generation via CFC oxidation are both safety concerns. This paper discusses chemical reactivity experiments that were performed using the state-of-the-art 3-dimensional NB31 CFC produced by SNECMA and a laminar reaction gas of Ar–21 vol% O2. Oxidation reaction rates were measured for CFC temperatures of 525, 600, 700, 800, 900, and 1000 °C and a 100 standard cubic centimeters per minute (sccm) Ar–O2 flow rate. Experiments were also performed at CFC temperatures of 700 and 1000 °C and a 1000 sccm Ar–O2 flow rate. Mass spectral analyses of the exhaust reaction gas suggested that carbon monoxide was the primary reaction at the CFC surface and carbon dioxide was readily produced in the exiting reaction gas. The measured reaction rates compare well with the literature and were used to produce a CFC oxidation curve that is recommended for use in fusion safety analyses.

  11. Activated Carbon Fibers For Gas Storage

    SciTech Connect

    Burchell, Timothy D; Contescu, Cristian I; Gallego, Nidia C

    2017-01-01

    The advantages of Activated Carbon Fibers (ACF) over Granular Activated Carbon (GAC) are reviewed and their relationship to ACF structure and texture are discussed. These advantages make ACF very attractive for gas storage applications. Both adsorbed natural gas (ANG) and hydrogen gas adsorption performance are discussed. The predicted and actual structure and performance of lignin-derived ACF is reviewed. The manufacture and performance of ACF derived monolith for potential automotive natural gas (NG) storage applications is reported Future trends for ACF for gas storage are considered to be positive. The recent improvements in NG extraction coupled with the widespread availability of NG wells means a relatively inexpensive and abundant NG supply in the foreseeable future. This has rekindled interest in NG powered vehicles. The advantages and benefit of ANG compared to compressed NG offer the promise of accelerated use of ANG as a commuter vehicle fuel. It is to be hoped the current cost hurdle of ACF can be overcome opening ANG applications that take advantage of the favorable properties of ACF versus GAC. Lastly, suggestions are made regarding the direction of future work.

  12. Carbon-fiber composite molecular sieves for gas separation

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.; Fei, Y.Q.

    1995-08-01

    The progress of research in the development of novel, rigid, monolithic adsorbent carbon fiber composites is described. Carbon fiber composites are produced at ORNL and activated at the CAER using steam or CO{sub 2} under different conditions, with the aims of producing a uniform degree of activation through the material, and of closely controlling pore structure and adsorptive properties The principal focus of the work to date has been to produce materials with narrow porosity for use in gas separations.

  13. Chronic in vivo stability assessment of carbon fiber microelectrode arrays

    NASA Astrophysics Data System (ADS)

    Patel, Paras R.; Zhang, Huanan; Robbins, Matthew T.; Nofar, Justin B.; Marshall, Shaun P.; Kobylarek, Michael J.; Kozai, Takashi D. Y.; Kotov, Nicholas A.; Chestek, Cynthia A.

    2016-12-01

    Objective. Individual carbon fiber microelectrodes can record unit activity in both acute and semi-chronic (∼1 month) implants. Additionally, new methods have been developed to insert a 16 channel array of carbon fiber microelectrodes. Before assessing the in vivo long-term viability of these arrays, accelerated soak tests were carried out to determine the most stable site coating material. Next, a multi-animal, multi-month, chronic implantation study was carried out with carbon fiber microelectrode arrays and silicon electrodes. Approach. Carbon fibers were first functionalized with one of two different formulations of PEDOT and subjected to accelerated aging in a heated water bath. After determining the best PEDOT formula to use, carbon fiber arrays were chronically implanted in rat motor cortex. Some rodents were also implanted with a single silicon electrode, while others received both. At the end of the study a subset of animals were perfused and the brain tissue sliced. Tissue sections were stained for astrocytes, microglia, and neurons. The local reactive responses were assessed using qualitative and quantitative methods. Main results. Electrophysiology recordings showed the carbon fibers detecting unit activity for at least 3 months with average amplitudes of ∼200 μV. Histology analysis showed the carbon fiber arrays with a minimal to non-existent glial scarring response with no adverse effects on neuronal density. Silicon electrodes showed large glial scarring that impacted neuronal counts. Significance. This study has validated the use of carbon fiber microelectrode arrays as a chronic neural recording technology. These electrodes have demonstrated the ability to detect single units with high amplitude over 3 months, and show the potential to record for even longer periods. In addition, the minimal reactive response should hold stable indefinitely, as any response by the immune system may reach a steady state after 12 weeks.

  14. Carbon fiber enhanced bioelectricity generation in soil microbial fuel cells.

    PubMed

    Li, Xiaojing; Wang, Xin; Zhao, Qian; Wan, Lili; Li, Yongtao; Zhou, Qixing

    2016-11-15

    The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation of organics contaminated soil. However, the electricity production and the remediation efficiency of soil MFC are seriously limited by the tremendous internal resistance of soil. Conductive carbon fiber was mixed with petroleum hydrocarbons contaminated soil and significantly enhanced the performance of soil MFC. The maximum current density, the maximum power density and the accumulated charge output of MFC mixed carbon fiber (MC) were 10, 22 and 16 times as high as those of closed circuit control due to the carbon fiber productively assisted the anode to collect the electron. The internal resistance of MC reduced by 58%, 83% of which owed to the charge transfer resistance, resulting in a high efficiency of electron transfer from soil to anode. The degradation rates of total petroleum hydrocarbons enhanced by 100% and 329% compared to closed and opened circuit controls without the carbon fiber respectively. The effective range of remediation and the bioelectricity recovery was extended from 6 to 20cm with the same area of air-cathode. The mixed carbon fiber apparently enhanced the bioelectricity generation and the remediation efficiency of soil MFC by means of promoting the electron transfer rate from soil to anode. The use of conductively functional materials (e.g. carbon fiber) is very meaningful for the remediation and bioelectricity recovery in the bioelectrochemical remediation.

  15. Dimensional accuracy and stability of polymethyl methacrylate reinforced with metal wire or with continuous glass fiber.

    PubMed

    Vallittu, P K

    1996-06-01

    The aim of this study was to determine the dimensional accuracy and stability of denture base polymethyl methacrylate (PMMA), which was reinforced in various ways. Autopolymerizing PMMA and heat-cured PMMA were reinforced either with semicircular steel wire or with a prefabricated experimental reinforcement made of continuous E-glass fiber. Control specimens had no reinforcement. The width of each U-shaped test specimen was measured with a digital micrometer under a light microscope immediately after the test specimen was cured and when stored in water for 1, 2, 7, and 14 days. The results revealed that both the type of PMMA and the type of reinforcement affected the dimensional accuracy of the test specimens, especially after 7 and 14 days in water storage (p < 0.001). The greatest dimensional accuracy was found with the unreinforced test specimen made from autopolymerizing PMMA and with test specimens reinforced with the metal wire made from heat-cured PMMA. In terms of the width of the test specimens, the lowest dimensional accuracy was found in unreinforced and glass fiber reinforced specimens made from heat-cured PMMA. Storage in water did not affect the stability of the width (p > 0.1). The results suggest that the polymerization shrinkage of PMMA causes lower dimensional accuracy of the test specimens reinforced with glass fiber. This should be considered when glass-fiber reinforcement is used clinically.

  16. Formation and chemical reactivity of carbon fibers prepared by defluorination of graphite fluoride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1994-01-01

    Defluorination of graphite fluoride (CFX) by heating to temperatures of 250 to 450 C in chemically reactive environments was studied. This is a new and possibly inexpensive process to produce new carbon-based materials. For example, CF 0.68 fibers, made from P-100 carbon fibers, can be defluorinated in BrH2C-CH = CH-CH2Br (1,4-dibromo-2butene) heated to 370 C, and graphitized to produce fibers with an unusually high modulus and a graphite layer structure that is healed and cross-linked. Conversely, a sulfur-doped, visibly soft carbon fiber was produced by defluorinating CF 0.9 fibers, made from P-25, in sulfur (S) vapor at 370 C and then heating to 660 C in nitrogen (N2). Furthermore, defluorination of the CF 0.68 fibers in bromine (Br2) produced fragile, structurally damaged carbon fibers. Heating these fragile fibers to 1100 C in N2 caused further structural damage, whereas heating to 150 C in bromoform (CHBr3) and then to 1100 C in N2 healed the structural defects. The defluorination product of CFX, tentatively called activated graphite, has the composition and molecular structure of graphite, but is chemically more reactive. Activated graphite is a scavenger of manganese (Mn), and can be intercalated with magnesium (Mg). Also, it can easily collect large amounts of an alloy made from copper (Cu) and type 304 stainless steel to form a composite. Finally, there are indications that activated graphite can wet metals or ceramics, thereby forming stronger composites with them than the pristine carbon fibers can form.

  17. Experimental and numerical investigation of concrete structures with metal and non-metal reinforcement at impulse loadings

    NASA Astrophysics Data System (ADS)

    Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.; Kudyakov, K. L.

    2016-11-01

    Manufacturing durable and high-strength concrete structures has always been a relevant objective. Therefore special attention has been paid to non-metallic composite reinforcement. This paper considers experimental and numerical studies of nature of fracture and crack formation in concrete beams with rod composite reinforcement. Fiber glass rods, 6 mm in diameter, have been used as composite reinforcement. Concrete elements have been tested under dynamic load using special pile driver. The obtained results include patterns of fracture and crack formation, maximum load value and maximum element deflection. Comparative analysis of numerical and experimental studies has been held.

  18. Pyrolysis as a way to close a CFRC life cycle: Carbon fibers recovery and their use as feedstock for a new composite production

    NASA Astrophysics Data System (ADS)

    Giorgini, Loris; Benelli, Tiziana; Mazzocchetti, Laura; Leonardi, Chiara; Zattini, Giorgio; Minak, Giangiacomo; Dolcini, Enrico; Tosi, Cristian; Montanari, Ivan

    2014-05-01

    Pyrolysis is shown to be an efficient method for recycling carbon fiber composites in the form of both uncured prepregs scraps or as cured end-of-life objects. The pyrolytic process leads to different products in three physical states of matter. The gaseous fraction, called syngas, can be used as energy feedstock in the process itself. The oil fraction can be used as fuel or chemical feedstock. The solid residue contains substantially unharmed carbon fibers that can be isolated and recovered for the production of new composite materials, thus closing the life cycle of the composite in a "cradle to cradle" approach. All the pyrolysis outputs were thoroughly analyzed and characterized in terms of composition for oil and gas fraction and surface characteristics of the fibers. In particular, it is of paramount importance to correlate the aspect and properties of the fibers obtained with different composite feedstock and operational conditions, that can be significantly different, with the reinforcing performance in the newly produced Recycled Carbon Fibers Reinforced Polymers. Present results have been obtained on a pyrolysis pilot plant that offers the possibility of treating up to 70kg of materials, thus leading to a significant amount of products to be tested in the further composites production, focused mainly on chopped carbon fiber reinforcement.

  19. [Raman spectra of carbon fibers during electrochemical treatment].

    PubMed

    Zhang, Min; Zhu, Bo; Wang, Cheng-guo; Wei, Han-xing

    2010-01-01

    Laser Raman spectroscopy was employed to characterize the microstructure variations of polyacrylonitrile-based carbon fibers during electrochemical treatment, and the characteristics of first-order Raman spectra of carbon fibers with different treatment time were investigated in the present paper. The results indicate that the Raman spectra of the carbon fibers can be fitted into four bands, named as D (or D1) band, G band, D2 band and D3 band, respectively. The Raman parameters to characterize surface microstructure variations of carbon fibers mainly include R(I(D2)) / I(G), area ratio of D band and G band), I(D2) / I(G) (area ratio of D2 band and G band), I(D3) / I(G) (area ratio of D3 band and G band), and I(D(S))/ I(G) (area ratio of all the disordered structure and G band). The peak separation between D band and G band becomes large after electrochemical treatment. R increases, which indicates that the surface disordered degree of carbon fibers increases. I(D3) / I(G) increases, which is caused by organic molecules, fragments or functional groups; decreases which is caused by the break of the aliphatic structures. With increasing treatment time, I(D(S)) / I(G) increases continuously, and the change trend of l(D(S)) / I(G) is consistent with that of R value, which can be used to comprehensively explain the variation of the surface structure of carbon fibers. So, the variety rules of the structure of carbon fibers can be investigated by laser Raman spectroscopy during electrochemical treatment.

  20. Fracture Analysis of Particulate Reinforced Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Min, James B.; Cornie, James A.

    2013-01-01

    A fracture analysis of highly loaded particulate reinforced composites was performed using laser moire interferometry to measure the displacements within the plastic zone at the tip of an advancing crack. Ten castings were made of five different particulate reinforcement-aluminum alloy combinations. Each casting included net-shape specimens which were used for the evaluation of fracture toughness, tensile properties, and flexure properties resulting in an extensive materials properties data. Measured fracture toughness range from 14.1 MPa for an alumina reinforced 356 aluminum alloy to 23.9 MPa for a silicon carbide reinforced 2214 aluminum alloy. For the combination of these K(sub Ic) values and the measured tensile strengths, the compact tension specimens were too thin to yield true plane strain K(sub Ic) values. All materials exhibited brittle behavior characterized by very small tensile ductility suggesting that successful application of these materials requires that the design stresses be below the elastic limit. Probabilistic design principles similar to those used with ceramics are recommended when using these materials. Such principles would include the use of experimentally determined design allowables. In the absence of thorough testing, a design allowable stress of 60 percent of the measured ultimate tensile stress is recommended.

  1. EFFECTS OF TEMPERATURE AND ENVIRONMENT ON MECHANICAL PROPERTIES OF TWO CONTINUOUS CARBON-FIBER AUTOMOTIVE STRUCTURAL COMPOSITES

    SciTech Connect

    Ruggles-Wrenn, M.B.

    2003-10-06

    The Durability of Carbon-Fiber Composites Project was established at Oak Ridge National Laboratory (ORNL) by the U.S. Department of Energy to develop experimentally based, durability-driven design guidelines to assure the long-term (15-year) structural integrity of carbon-fiber-based composite systems for automotive structural applications. The project addressed characterization and modeling the durability of a progression of carbon-reinforced thermoset materials, each of which has the same urethane matrix. The primary purpose of this report is to provide the individual specimen test data. Basic mechanical property testing and results for a reference [{+-}45{sup o}]{sub 3S} crossply composite and a quasi-isotropic, [0/90{sup o}/{+-}45{sup o}]{sub S} version of the reference crossply are provided. The matrix and individual {+-}45{sup o} stitch-bonded mats are the same in both cases. Although the composite utilized aerospace-grade carbon-fiber reinforcement, it was made by a rapid-molding process suitable for high-volume automotive use. Behavioral trends, effects of temperature and environment, and corresponding design knockdown factors are established for both materials. The reference crossply is highly anisotropic with two dominant fiber orientations--0/90{sup o} and {+-}45{sup o}. Therefore properties were developed for both orientations.

  2. High Temperature Interactions of Metallic Matrices with Ceramic Reinforcements

    DTIC Science & Technology

    1990-12-31

    temperatura range were extensive; various metal silicides, metalIcarbides, ternary metal-slilcon-carbides, and unreacted carbon were formed as layered...Couples 3.2.1 Preparation of SiC Ceramic: The polycrystalline SiC substrates, designated as Hexoloy, were obtained from the Carborundum Corporation ...and was received from Engelhard Corporation . The metal pieces were cut into a similar size to that of the SiC, mechanically ground with #600 SiC papers

  3. A LASER INTERFERENCE-BASED SURFACE TREATMENT OF AL AND CARBON FIBER POLYMER COMPOSITES FOR ENHANCED BONDING

    SciTech Connect

    Sabau, Adrian S; Warren, Charles David; ERDMAN III, DONALD L; Daniel, Claus; Skszek, Timothy; Caruso-Dailey, Mary M.

    2016-01-01

    Due to its increased use in the automotive and aerospace industries, joining of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) to metals demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using a new laser based technique, in which the laser interference power profile was created by splitting the beam and guiding those beams to the sample surface by overlapping each other with defined angles to each other. Results were presented for the overlap shear testing of single-lap joints made with Al 5182 and CFPC specimens whose surfaces prepared by (a) surface abrasion and solvent cleaning; and (b) laser-interference structured surfaces by rastering with a 4 mm laser beam at approximately 3.5 W power. CFPC specimens of T700S carbon fiber, Prepreg T70 epoxy, 4 or 5 ply thick, 0/90o plaques were used. Adhesive DP810 was used to bond Al and CFPC. The bondline was 0.25mm and the bond length was consistent among all joints produced. First, the effect of the laser speed on the joint performance was evaluated by laser-interference structure Al and CFPC surfaces with a beam angle of 3o and laser beam speeds of 3, 5, and 10 mm/s. For this sensitivity study, 3 joint specimens were used per each joint type. Based on the results for minimum, maximum, and mean values for the shear lap strength and maximum load for all the 9 joint types, two joint types were selected for further evaluations. Six additional joint specimens were prepared for these two joint types in order to obtain better statistics and the shear test data was presented for the range, mean, and standard deviation. The results for the single-lap shear tests obtained for six joint specimens, indicate that the shear lap strength, maximum load, and displacement at maximum load for those joints made with laser-interference structured surfaces were increased by approximately 14.8%, 16%, and 100

  4. Mechanical behavior of laminated carbon fiber composites under pin loading and affecting factors on the bearing strength

    NASA Astrophysics Data System (ADS)

    Maikuma, Hironori; Kubomura, Kenji

    1992-07-01

    Results are presented on measurements of the bearing strength of four pitch-based and two PAN-based carbon-fiber composite materials of (0 deg/ +,- 45 deg/ 90 deg)3s laminate specimens. The bearing strength was correlated with the mechanical properties of longitudinal reinforcing fibers, and with observations of microstructural damage. It was found that, in both the high tensile and high modulus carbon-fiber composite materials, the full bearing strength develops when the edge to distance ratio equals to or is larger than 3.0, and the side distance ratio is equal to or is larger than 4.0. As the fiber strain to failure becomes higher and also as the longitudinal compressive strength of unidirectional composites becames higher, the bearing strength becomes higher. No corrrelation was found between the tensile strength of the fiber and the bearing strength.

  5. A process to recover carbon fibers from polymer-matrix composites in end-of-life vehicles

    NASA Astrophysics Data System (ADS)

    Jody, Bassam J.; Pomykala, Joseph A.; Daniels, Edward J.; Greminger, Jessica L.

    2004-08-01

    Because of their high strength-to-weight ratios, carbon-fiber-reinforced polymer-matrix composite (PMC) materials are being evaluated for use in the automotive industry. The major barriers to their widespread use are their relatively high cost and the uncertainty about whether they can be recycled. A process to recover carbon fibers from obsolete PMC materials has been developed at Argonne National Laboratory. The process was tested using PMC samples made with different thermoset or thermoplastic substrates. For most mixtures of PMCs, the process can be energy self-sufficient using the polymer substrate as an energy source. An evaluation of the recovered samples found that the fibers appear to have retained good properties and characteristics and are suitable for short fiber applications. This paper describes the process and the characteristics and properties of the recovered fibers.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  7. Fracture detection in concrete by glass fiber cloth reinforced plastics

    NASA Astrophysics Data System (ADS)

    Shin, Soon-Gi; Lee, Sung-Riong

    2006-04-01

    Two types of carbon (carbon fiber and carbon powder) and a glass cloth were used as conductive phases and a reinforcing fiber, respectively, in polymer rods. The carbon powder was used for fabricating electrically conductive carbon powder-glass fiber reinforced plastic (CP-GFRP) rods. The carbon fiber tows and the CP-GFRP rods were adhered to mortar specimens using epoxy resin and glass fiber cloth. On bending, the electrical resistance of the carbon fiber tow attached to the mortar specimen increased greatly after crack generation, and that of the CP-GFRP rod increased after the early stages of deflection in the mortar. Therefore, the CP-GFRP rod is superior to the carbon fiber tow in detecting fractures. Also, by reinforcing with a glass fiber cloth reinforced plastic, the strength of the mortar specimens became more than twice as strong as that of the unreinforced mortar.

  8. Evaluation of a metal fuselage frame selectively reinforced with filamentary composites for space shuttle application

    NASA Technical Reports Server (NTRS)

    Oken, S.; Skoumal, D. E.; Straayer, J. W.

    1974-01-01

    The development of metal structures reinforced with filamentary composites as a weight saving feature of the space shuttle components is discussed. A frame was selected for study that was representative of the type of construction used in the bulk frames of the orbiter vehicle. Theoretical and experimental investigations were conducted. Component tests were performed to evaluate the critical details used in the designs and to provide credibility to the weight saving results. A model frame was constructed of the reinforced metal material to provide a final evaluation of the construction under realistic load conditions.

  9. Lightweight Materials for Automotive Application: An Assessment of Material Production Data for Magnesium and Carbon Fiber

    SciTech Connect

    Johnson, M. C.; Sullivan, J. L.

    2014-09-01

    The use of lightweight materials in vehicle components, also known as “lightweighting,” can result in automobile weight reduction, which improves vehicle fuel economy and generally its environmental footprint. Materials often used for vehicle lightweighting include aluminum, magnesium, and polymers reinforced with either glass or carbon fiber. However, because alternative materials typically used for vehicle lightweighting require more energy to make on a per part basis than the material being replaced (often steel or iron), the fuel efficiency improvement induced by a weight reduction is partially offset by an increased energy for the vehicle material production. To adequately quantify this tradeoff, reliable and current values for life-cycle production energy are needed for both conventional and alternative materials. Our focus here is on the production of two such alternative materials: magnesium and carbon fibers. Both these materials are low density solids with good structural properties. These properties have enabled their use in applications where weight is an issue, not only for automobiles but also for aerospace applications. This report addresses the predominant production methods for these materials and includes a tabulation of available material and energy input data necessary to make them. The life cycle inventory (LCI) information presented herein represents a process chain analysis (PCA) approach to life cycle assessment (LCA) and is intended for evaluation as updated materials production data for magnesium and carbon fiber for inclusion into the Greenhouse gases, Regulated Emissions, and Energy use in Transportation model (GREET2_2012). The summary life-cycle metrics used to characterize the cradle-to-gate environmental performance of these materials are the cumulative energy demand (CED) and greenhouse gas emissions (GHG) per kilogram of material.

  10. Hybrid carbon fiber/carbon nanotube composites for structural damping applications.

    PubMed

    Tehrani, M; Safdari, M; Boroujeni, A Y; Razavi, Z; Case, S W; Dahmen, K; Garmestani, H; Al-Haik, M S

    2013-04-19

    Carbon nanotubes (CNTs) were grown on the surface of carbon fibers utilizing a relatively low temperature synthesis technique; graphitic structures by design (GSD). To probe the effects of the synthesis protocols on the mechanical properties, other samples with surface grown CNTs were prepared using catalytic chemical vapor deposition (CCVD). The woven graphite fabrics were thermally shielded with a thin film of SiO2 and CNTs were grown on top of this film. Raman spectroscopy and electron microscopy revealed the grown species to be multi-walled carbon nanotubes (MWCNTs). The damping performance of the hybrid CNT-carbon fiber-reinforced epoxy composite was examined using dynamic mechanical analysis (DMA). Mechanical testing confirmed that the degradations in the strength and stiffness as a result of the GSD process are far less than those encountered through using the CCVD technique and yet are negligible compared to the reference samples. The DMA results indicated that, despite the minimal degradation in the storage modulus, the loss tangent (damping) for the hybrid composites utilizing GSD-grown MWCNTs improved by 56% compared to the reference samples (based on raw carbon fibers with no surface treatment or surface grown carbon nanotubes) over the frequency range 1-60 Hz. These results indicated that the energy dissipation in the GSD-grown MWCNTs composite can be primarily attributed to the frictional sliding at the nanotube/epoxy interface and to a lesser extent to the stiff thermal shielding SiO2 film on the fiber/matrix interface.

  11. Durability-Based Design Criteria for a Quasi-Isotropic Carbon-Fiber Automotive Composite

    SciTech Connect

    Corum, J.M.

    2002-04-17

    This report provides recommended durability-based design properties and criteria for a quasi-isotropic carbon-fiber composite for possible automotive structural applications. The composite, which was made by a rapid molding process suitable for high-volume automotive applications, consisted of continuous Thornel T300 fibers (6K tow) in a Baydur 420 IMR urethane matrix. The reinforcement was in the form of four {+-}45{sup o} stitch-bonded mats in the following layup: [0/90{sup o}/{+-}45{sup o}]{sub S}. This material is the second in a progression of three candidate thermoset composites to be characterized and modeled as part of an Oak Ridge National Laboratory project entitled Durability of Carbon-Fiber Composites. The overall goal of the project, which is sponsored by the U.S. Department of Energy's Office of Advanced Automotive Technologies and is closely coordinated with the industry Automotive Composites Consortium, is to develop durability-driven design data and criteria to assure the long-term integrity of carbon-fiber-based composite systems for large automotive structural components. This document is in two parts. Part I provides the design criteria, and Part 2 provides the underlying experimental data and models. The durability issues addressed include the effects on deformation, strength, and stiffness of cyclic and sustained loads, operating temperature, automotive fluid environments, and low-energy impacts (e.g., tool drops and kickups of roadway debris). Guidance is provided for design analysis, time-dependent allowable stresses, rules for cyclic loadings, and damage tolerance design guidance, including the effects of holes. Chapter 6 provides a brief summary of the design criteria.

  12. Method of making metal matrix composites reinforced with ceramic particulates

    DOEpatents

    Cornie, James A.; Kattamis, Theodoulos; Chambers, Brent V.; Bond, Bruce E.; Varela, Raul H.

    1989-01-01

    Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys.

  13. Method of making metal matrix composites reinforced with ceramic particulates

    DOEpatents

    Cornie, J.A.; Kattamis, T.; Chambers, B.V.; Bond, B.E.; Varela, R.H.

    1989-08-01

    Composite materials and methods for making such materials are disclosed in which dispersed ceramic particles are at chemical equilibrium with a base metal matrix, thereby permitting such materials to be remelted and subsequently cast or otherwise processed to form net weight parts and other finished (or semi-finished) articles while maintaining the microstructure and mechanical properties (e.g. wear resistance or hardness) of the original composite. The composite materials of the present invention are composed of ceramic particles in a base metal matrix. The ceramics are preferably carbides of titanium, zirconium, tungsten, molybdenum or other refractory metals. The base metal can be iron, nickel, cobalt, chromium or other high temperature metal and alloys thereof. For ferrous matrices, alloys suitable for use as the base metal include cast iron, carbon steels, stainless steels and iron-based superalloys. 2 figs.

  14. Seamless metal-clad fiber-reinforced organic matrix composite structures and process for their manufacture

    NASA Technical Reports Server (NTRS)

    Bluck, Raymond M. (Inventor); Bush, Harold G. (Inventor); Johnson, Robert R. (Inventor)

    1990-01-01

    A metallic outer sleeve is provided which is capable of enveloping a hollow metallic inner member having continuous reinforcing fibers attached to the distal end thereof. The inner member is then introduced into outer sleeve until inner member is completely enveloped by outer sleeve. A liquid matrix member is then injected into space between inner member and outer sleeve. A pressurized heat transfer medium is flowed through the inside of inner member, thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. thereby forming a fiber reinforced matrix composite material. The wall thicknesses of both inner member and outer sleeve are then reduced to the appropriate size by chemical etching, to adjust the thermal expansion coefficient of the metal-clad composite structure to the desired value. The novelty of this invention resides in the development of a efficient method of producing seamless metal clad fiber reinforced organic matrix composite structures.

  15. The application of carbon fiber resistancein monitoring of curing

    NASA Astrophysics Data System (ADS)

    Sun, X. Y.; Zhang, B. M.; Zong, Yang

    2009-07-01

    Thermal residual stress in resin matrix composite due to the different coefficient of thermal expansion (CTE). The CTE of carbon fiber is lower than resin matrix. Based on mechanics, rising temperature will induce tensile stress, cooling down will induce compress in fiber. There exists expanding and shrinkage during curing process of epoxy. In single fiber composite system, they play different roles, present with tensile and compress stress on fiber. This paper deals with the relationship of the carbon fiber resistance with strain and temperature. The effect of expanding and shrinkage on residual stress is got by the fiber resistant measurement. Resistance variety curve of the experiment shows the chemical process during resin solidification. The shear stress between fiber and matrix existing during temperature load can also measured by the same method. The carbon fiber's resistant can be used as sensor to monitor and control the curing process. This is a simple and effective method to research the curing process.

  16. Fabrication optimisation of carbon fiber electrode with Taguchi method.

    PubMed

    Cheng, Ching-Ching; Young, Ming-Shing; Chuang, Chang-Lin; Chang, Ching-Chang

    2003-07-01

    In this study, we describe an optimised procedure for fabricating carbon fiber electrodes using Taguchi quality engineering method (TQEM). The preliminary results show a S/N ratio improvement from 22 to 30 db (decibel). The optimised parameter was tested by using a glass micropipette (0.3 mm outer/2.5 mm inner length of carbon fiber) dipped into PBS solution under 2.9 V triangle-wave electrochemical processing for 15 s, followed by coating treatment of micropipette on 2.6 V DC for 45 s in 5% Nafion solution. It is thus shown that Taguchi process optimisation can improve cost, manufacture time and quality of carbon fiber electrodes.

  17. Autonomic healing of carbon fiber/epoxy interfaces.

    PubMed

    Jones, Amanda R; Cintora, Alicia; White, Scott R; Sottos, Nancy R

    2014-05-14

    A maximum of 91% recovery of interfacial shear strength (IFSS) is achieved for carbon fiber/epoxy interfaces functionalized with capsules containing reactive epoxy resin and ethyl phenyl acetate (EPA). We find a binder is necessary to improve the retention of capsules on the carbon fiber surface. Two different methods for applying the binder to the carbon fiber surface are investigated. Healing efficiency is assessed by recovery of IFSS of a single functionalized fiber embedded in a microdroplet of epoxy. Debonding of the fiber/matrix interface ruptures the capsules, releasing resin and EPA solvent into the crack plane. The solvent swells the matrix, initiating transport of residual amine functionality from the matrix for further curing with the epoxy resin delivered to the crack plane. The two binder protocols produce comparable results, both yielding higher recovery of IFSS than samples prepared without a binder.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  19. Simulation of a Novel Joining Process for Fiber-Reinforced Thermoplastic Composites and Metallic Components

    NASA Astrophysics Data System (ADS)

    Gude, M.; Freund, A.; Vogel, C.; Kupfer, R.

    2017-01-01

    In this study, a new joining technology to produce hybrid structures with continuous-fiber-reinforced thermoplastics and metallic components is presented adapting the concept of classical clinching for thermoplastic composites. To demonstrate the capability of the thermoclinching process, prototypic joints were manufactured using an experimental joining installation developed. Nondestructive and destructive analyses of the thermoclinched joints showed that a relocation of the reinforcement into the neck and head area of the joining zone could be achieved. For a first estimation of the maximum load-carrying capacity of the joints, single-lap specimens with both reinforced and nonreinforced thermoplastics were manufactured and tested, revealing up to 50% higher failure loads of the reinforced joints. To understand the local material configuration and to achieve a defined and adjustable fabric structure in the head area of the joint, further analyses with regard to material- and tool-side conditions of the joining zone are necessary.

  20. The PAU camera carbon fiber cryostat and filter interchange system

    NASA Astrophysics Data System (ADS)

    Lopez, Luis; Padilla, Cristóbal; Cardiel-Sas, Laia; Ballester, Otger; Grañena, Ferràn; Majà, Ester; Castander, Francisco J.

    2016-08-01

    This paper describes the engineering and mechanical considerations in the design and construction of a carbon fiber containment vessel for a photometric camera. The camera is intended for installation on the 4 m William Herschel Telescope, located in Palma, Spain. The scientific objective of the camera system is to measure red-shifts of a large sample of galaxies using the photometric technique. The paper is broken down into sections, divided by the principal engineering challenges of the project; the carbon fiber vacuum vessel, the cooling systems and the precision movement systems.

  1. Review and developments of dissemination models for airborne carbon fibers

    NASA Technical Reports Server (NTRS)

    Elber, W.

    1980-01-01

    Dissemination prediction models were reviewed to determine their applicability to a risk assessment for airborne carbon fibers. The review showed that the Gaussian prediction models using partial reflection at the ground agreed very closely with a more elaborate diffusion analysis developed for the study. For distances beyond 10,000 m the Gaussian models predicted a slower fall-off in exposure levels than the diffusion models. This resulting level of conservatism was preferred for the carbon fiber risk assessment. The results also showed that the perfect vertical-mixing models developed herein agreed very closely with the diffusion analysis for all except the most stable atmospheric conditions.

  2. Mechanical Properties of Heat-treated Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Effinger, Michael R.; Patel, Bhavesh; Koenig, John; Cuneo, Jaques; Neveux, Michael G.; Demos, Chrystoph G.

    2004-01-01

    Carbon fibers are selected for ceramic matrix composites (CMC) are based on their as-fabricated properties or on "that is what we have always done" technical culture while citing cost and availability when there are others with similar cost and availability. However, the information is not available for proper selection of carbon fibers since heat-treated properties are not known for the fibers on the market currently. Heat-treating changes the fiber's properties. Therefore, an effort was undertaken to establish fiber properties on 19 different types of fibers from six different manufactures for both PAN and pitch fibers. Heat-treating has been done at three different temperatures.

  3. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S.

    2010-06-01

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  4. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S

    2013-02-19

    A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

  5. Surface and interface properties of carbon fiber composites under cyclical aging

    NASA Astrophysics Data System (ADS)

    Lv, Xinying; Wang, Rongguo; Liu, Wenbo; Jiang, Long

    2011-10-01

    Carbon fiber-reinforced BMI composites have been subjected to combination accelerated aging comprising a hygrothermal process, a thermal-oxidative process, and a freezing process in order to simulate their responses under complicated service environments. This cyclical condition, including the freezing process, has not been investigated by other researchers so far. The effects of this combination accelerated aging on the mechanical properties have been characterized by FTIR, SEM/EDXA, XRD, and moisture-uptake determination. The results indicated that combination accelerated aging had great effects on the mechanical properties of the composite, the network structure of the BMI matrix, and the moisture uptake by the composite. After a third cycle of accelerated aging, moisture reached the center layer of the composite and as a result led to an obvious decrease in ILSS due to deterioration of the carbon fiber-BMI interface. Sufficient moisture absorption on the composite surface made the network structure of the BMI matrix more open, which facilitated stress relaxation and the creation of micro-cracks, with a consequent obvious decrease in flexural strength. With increasing number of combined-action accelerated aging cycles, ever more moisture was absorbed during each hygrothermal process due to the plasticizing effect of water, and micro-cracks propagated as a result of internal stresses caused by the hygrothermal process, the thermal-oxidative process, and the freezing process of each cycle. XRD analysis indicated that moisture penetrated through the amorphous region of the BMI matrix.

  6. Properties of Multifunctional Hybrid Carbon Nanotube/Carbon Fiber Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Kang, Jin Ho; Grimsley, Brian W.; Ratcliffe, James G.; Siochi, Emilie J.

    2016-01-01

    For aircraft primary structures, carbon fiber reinforced polymer (CFRP) composites possess many advantages over conventional aluminum alloys due to their light weight, higher strength- and stiffness-to-weight ratios, and low life-cycle maintenance costs. However, the relatively low electrical and thermal conductivities of CFRP composites fail to provide structural safety in certain operational conditions such as lightning strikes. Carbon nanotubes (CNT) offer the potential to enhance the multi-functionality of composites with improved thermal and electrical conductivity. In this study, hybrid CNT/carbon fiber (CF) polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel® IM7/8852 prepreg. Resin concentrations from 1 wt% to 50 wt% were used to infuse the CNT sheets prior to composite fabrication. The interlaminar properties of the resulting hybrid composites were characterized by mode I and II fracture toughness testing. Fractographical analysis was performed to study the effect of resin concentration. In addition, multi-directional physical properties like thermal conductivity of the orthotropic hybrid polymer composite were evaluated.

  7. In Situ Exfoliated, Edge-Rich, Oxygen-Functionalized Graphene from Carbon Fibers for Oxygen Electrocatalysis.

    PubMed

    Liu, Zhijuan; Zhao, Zhenghang; Wang, Yanyong; Dou, Shuo; Yan, Dafeng; Liu, Dongdong; Xia, Zhenhai; Wang, Shuangyin

    2017-03-09

    Metal-free electrocatalysts have been extensively developed to replace noble metal Pt and RuO2 catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in fuel cells or metal-air batteries. These electrocatalysts are usually deposited on a 3D conductive support (e.g., carbon paper or carbon cloth (CC)) to facilitate mass and electron transport. For practical applications, it is desirable to create in situ catalysts on the carbon fiber support to simplify the fabrication process for catalytic electrodes. In this study, the first example of in situ exfoliated, edge-rich, oxygen-functionalized graphene on the surface of carbon fibers using Ar plasma treatment is successfully prepared. Compared to pristine CC, the plasma-etched carbon cloth (P-CC) has a higher specific surface area and an increased number of active sites for OER and ORR. P-CC also displays good intrinsic electron conductivity and excellent mass transport. Theoretical studies show that P-CC has a low overpotential that is comparable to Pt-based catalysts, as a result of both defects and oxygen doping. This study provides a simple and effective approach for producing highly active in situ catalysts on a carbon support for OER and ORR.

  8. Elasto-plastic analysis of interface layers for fiber reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Doghri, I.; Leckie, F. A.

    1991-01-01

    The mismatch in coefficients of thermal expansion (CTE) of fiber and matrix in metal matrix composites reinforced with ceramic fibers induces high thermal stresses in the matrix. Elasto-plastic analyses - with different degrees of simplification and modelization - show that an interface layer with a sufficiently high CTE can reduce the tensile hoop stress in the matrix substantially.

  9. Acoustic characterization of void distributions across carbon-fiber composite layers

    NASA Astrophysics Data System (ADS)

    Tayong, Rostand B.; Smith, Robert A.; Pinfield, Valerie J.

    2016-02-01

    Carbon Fiber Reinforced Polymer (CFRP) composites are often used as aircraft structural components, mostly due to their superior mechanical properties. In order to improve the efficiency of these structures, it is important to detect and characterize any defects occurring during the manufacturing process, removing the need to mitigate the risk of defects through increased thicknesses of structure. Such defects include porosity, which is well-known to reduce the mechanical performance of composite structures, particularly the inter-laminar shear strength. Previous work by the authors has considered the determination of porosity distributions in a fiber-metal laminate structure [1]. This paper investigates the use of wave-propagation modeling to invert the ultrasonic response and characterize the void distribution within the plies of a CFRP structure. Finite Element (FE) simulations are used to simulate the ultrasonic response of a porous composite laminate to a typical transducer signal. This simulated response is then applied as input data to an inversion method to calculate the distribution of porosity across the layers. The inversion method is a multi-dimensional optimization utilizing an analytical model based on a normal-incidence plane-wave recursive method and appropriate mixture rules to estimate the acoustical properties of the structure, including the effects of plies and porosity. The effect of porosity is defined through an effective wave-number obtained from a scattering model description. Although a single-scattering approach is applied in this initial study, the limitations of the method in terms of the considered porous layer, percentage porosity and void radius are discussed in relation to single- and multiple-scattering methods. A comparison between the properties of the modeled structure and the void distribution obtained from the inversion is discussed. This work supports the general study of the use of ultrasound methods with inversion to

  10. Electrospun FeS2@Carbon Fiber Electrode as a High Energy Density Cathode for Rechargeable Lithium Batteries.

    PubMed

    Zhu, Yujie; Fan, Xiulin; Suo, Liumin; Luo, Chao; Gao, Tao; Wang, Chunsheng

    2016-01-26

    In this study, an FeS2@carbon fiber electrode is developed with FeS2 nanoparticles either embedded in or attached to carbon fibers by using an electrospinning method. By applying this binder-free, metal-current-collector-free FeS2@carbon fiber electrode, both the redox reaction and capacity decay mechanisms for the Li-FeS2 system are revealed by changing the electrolyte (conventional carbonate electrolyte and a "solvent-in-salt"-type Li-S battery electrolyte) and working voltage ranges (1.0-3.0 V and 1.5-3.0 V vs Li/Li(+)). The FeS2@carbon fiber electrode shows stable cycling performance in both the conventional carbonate electrolyte and the solvent-in-salt-type Li-S battery electrolyte in the voltage range of 1.5-3.0 V. Electrochemical tests in the solvent-in-salt-type Li-S battery electrolyte indicate that the Li-FeS2 system becomes a hybrid of the Li-S cell and Li-iron sulfide cell after the initial cycle. Based on the understanding on the capacity decay mechanisms, the cycling stability of the Li-FeS2 system in the voltage range of 1.0-3.0 V is then significantly enhanced by coating the FeS2@carbon fiber electrode with a thin layer of Al2O3. The Al2O3-coated electrode demonstrates excellent cycling performance with high discharge energy densities at both the material level (∼1300 Wh/kg-FeS2) and the electrode level (∼1000 Wh/kg-FeS2 electrode).

  11. An In Vitro Comparative Evaluation of Fracture Resistance of Custom Made, Metal, Glass Fiber Reinforced and Carbon Reinforced Posts in Endodontically Treated Teeth

    PubMed Central

    Sonkesriya, Subhash; Olekar, Santosh T; Saravanan, V; Somasunderam, P; Chauhan, Rashmi Singh; Chaurasia, Vishwajit Rampratap

    2015-01-01

    Background: Posts are used to enhance crown buildup in pulpless teeth with destructed crown portion. Different types of post are used in endodontically treated teeth. The aim of the present in vitro study was to evaluate fracture resistance of custom made, metal, glass fiber reinforced and carbon reinforced posts in endodontically treated teeth. Materials and Methods: An in vitro study was carried out on extracted 40 human maxillary central incisor teeth, which was divided into four groups with 10 samples in each group with custom made, metal post, glass fiber reinforced, and carbon reinforced posts. The samples were decoronated at cemento-enamel junction and endodontically treated. Post space was prepared and selected posts were cemented. The composite cores were prepared at the height of 5 mm and samples mounted on acrylic blocks. Later fracture resistance to the compressive force of samples was measured using Universal Testing Machine. Results: The maximum resistance to the compressive force was observed in carbon reinforced and glass fiber reinforced posts compared others which is statistically significant (P > 0.001) and least was seen in custom fabricated post. Conclusion: It is concluded that carbon reinforced fiber post and glass fiber posts showed good fracture resistance compared to custom made and metal posts. PMID:26028904

  12. Dissemination, resuspension, and filtration of carbon fibers. [aircraft fires

    NASA Technical Reports Server (NTRS)

    Elber, W.

    1980-01-01

    Carbon fiber transport was studied using mathematical models established for other pollution problems. It was demonstrated that resuspension is not a major factor contributing to the risk. Filtration and fragmentation tests revealed that fiber fragmentation shifts the fiber spectrum to shorter mean lengths in high velocity air handling systems.

  13. Laser Treatment, Bonding Potential Road to Success for Carbon Fiber

    SciTech Connect

    Sabau, Adrian

    2016-05-19

    Joining carbon fiber composites and aluminum for lightweight cars and other multi-material high-end products could become less expensive and the joints more robust because of a new method that harnesses a laser’s power and precision.

  14. Adsorption Properties of Lignin-derived Activated Carbon Fibers (LACF)

    SciTech Connect

    Contescu, Cristian I.; Gallego, Nidia C.; Thibaud-Erkey, Catherine; Karra, Reddy

    2016-04-01

    The object of this CRADA project between Oak Ridge National Laboratory (ORNL) and United Technologies Research Center (UTRC) is the characterization of lignin-derived activated carbon fibers (LACF) and determination of their adsorption properties for volatile organic compounds (VOC). Carbon fibers from lignin raw materials were manufactured at Oak Ridge National Laboratory (ORNL) using the technology previously developed at ORNL. These fibers were physically activated at ORNL using various activation conditions, and their surface area and pore-size distribution were characterized by gas adsorption. Based on these properties, ORNL did down-select five differently activated LACF materials that were delivered to UTRC for measurement of VOC adsorption properties. UTRC used standard techniques based on breakthrough curves to measure and determine the adsorption properties of indoor air pollutants (IAP) - namely formaldehyde and carbon dioxide - and to verify the extent of saturated fiber regenerability by thermal treatments. The results are summarized as follows: (1) ORNL demonstrated that physical activation of lignin-derived carbon fibers can be tailored to obtain LACF with surface areas and pore size distributions matching the properties of activated carbon fibers obtained from more expensive, fossil-fuel precursors; (2) UTRC investigated the LACF potential for use in air cleaning applications currently pursued by UTRC, such as building ventilation, and demonstrated their regenerability for CO2 and formaldehyde, (3) Both partners agree that LACF have potential for possible use in air cleaning applications.

  15. Clean Energy Manufacturing Analysis Center. 2015 Research Highlights -- Carbon Fiber

    SciTech Connect

    Das, Sujit

    2016-03-01

    CEMAC has conducted four major studies on the manufacturing of clean energy technologies. Three of these focused on the end product: solar photovoltaic modules, wind turbines, and automotive lithium-ion batteries. The fourth area focused on a key material for manufacturing clean energy technologies, carbon fiber.

  16. Amperometric Carbon Fiber Nitrite Microsensor for In Situ Biofilm Monitoring

    EPA Science Inventory

    A highly selective needle type solid state amperometric nitrite microsensor based on direct nitrite oxidation on carbon fiber was developed using a simplified fabrication method. The microsensor’s tip diameter was approximately 7 µm, providing a high spatial resolution of at lea...

  17. Nonrespirability of Carbon Fibers in Rats from Repeated Inhalation Exposure

    DTIC Science & Technology

    1990-09-01

    They thank Erica R. Riley, Physics Division, CRDEC, for her SEM analysis of the generated material and Dr. Lucas Brennecke, Pathology Associates, for... Ballantyne , B., and Clary, J.J., "Subchronic Inhalation Toxicology of Carbon Fibers," J., Vol. 28, pp 373-376 (1986). 15. Guide for th,’ Care and Use

  18. Capacitive Measurement Of Coating Thickness On Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Eftekhari, Abe; Chapman, John J.

    1994-01-01

    Technique for gauging coating thickness during prepreg processing of carbon fibers developed. Technique based on measurement of capacitance of cylindrical condenser through which bundle of prepregged fibers passed axially. Empirical results indicate capacitance linearly related to thickness of polymer coat on fibers in bundle. Capacitive transducer used successfully to measure thickness of polymer coats on several test bundles of fibers under static conditions.

  19. Process for preparing tapes from thermoplastic polymers and carbon fibers

    NASA Technical Reports Server (NTRS)

    Chung, Tai-Shung (Inventor); Furst, Howard (Inventor); Gurion, Zev (Inventor); McMahon, Paul E. (Inventor); Orwoll, Richard D. (Inventor); Palangio, Daniel (Inventor)

    1986-01-01

    The instant invention involves a process for use in preparing tapes or rovings, which are formed from a thermoplastic material used to impregnate longitudinally extended bundles of carbon fibers. The process involves the steps of (a) gas spreading a tow of carbon fibers; (b) feeding the spread tow into a crosshead die; (c) impregnating the tow in the die with a thermoplastic polymer; (d) withdrawing the impregnated tow from the die; and (e) gas cooling the impregnated tow with a jet of air. The crosshead die useful in the instant invention includes a horizontally extended, carbon fiber bundle inlet channel, means for providing melted polymer under pressure to the die, means for dividing the polymeric material flowing into the die into an upper flow channel and a lower flow channel disposed above and below the moving carbon fiber bundle, means for applying the thermoplastic material from both the upper and lower channels to the fiber bundle, and means for withdrawing the resulting tape from the die.

  20. Nitric oxide determination by amperometric carbon fiber microelectrode.

    PubMed

    Katrlík, Jaroslav; Zálesáková, Pavlína

    2002-05-15

    Nitric oxide (NO) amperometric microsensor was prepared by the modification of bare carbon fiber electrode by Nafion and cellulose acetate (CA). Detection limit, response time, reproducibility and influence of some possible interferences (nitrite, nitrate, arginine) were tested and evaluated. This sensor was used for in vitro determination of NO release from fresh porcine aorta induced by calcium ionophore A23187 (CI).

  1. Laser Treatment, Bonding Potential Road to Success for Carbon Fiber

    ScienceCinema

    Sabau, Adrian

    2016-07-12

    Joining carbon fiber composites and aluminum for lightweight cars and other multi-material high-end products could become less expensive and the joints more robust because of a new method that harnesses a laser’s power and precision.

  2. Approach to the assessment of the hazard. [fire released carbon fiber electrical effects

    NASA Technical Reports Server (NTRS)

    Huston, R. J.

    1980-01-01

    An overview of the carbon fiber hazard assessment is presented. The potential risk to the civil sector associated with the accidental release of carbon fibers from aircraft having composite structures was assessed along with the need for protection of civil aircraft from carbon fibers.

  3. 21 CFR 878.3500 - Polytetrafluoroethylene with carbon fibers composite implant material.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Polytetrafluoroethylene with carbon fibers... Prosthetic Devices § 878.3500 Polytetrafluoroethylene with carbon fibers composite implant material. (a) Identification. A polytetrafluoroethylene with carbon fibers composite implant material is a porous...

  4. 21 CFR 878.3500 - Polytetrafluoroethylene with carbon fibers composite implant material.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Polytetrafluoroethylene with carbon fibers... Prosthetic Devices § 878.3500 Polytetrafluoroethylene with carbon fibers composite implant material. (a) Identification. A polytetrafluoroethylene with carbon fibers composite implant material is a porous...

  5. 21 CFR 878.3500 - Polytetrafluoroethylene with carbon fibers composite implant material.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Polytetrafluoroethylene with carbon fibers... Prosthetic Devices § 878.3500 Polytetrafluoroethylene with carbon fibers composite implant material. (a) Identification. A polytetrafluoroethylene with carbon fibers composite implant material is a porous...

  6. Damage mechanisms characterization of carbon fiber/epoxy composite laminates by both electrical resistance measurements and acoustic emission analysis

    SciTech Connect

    Ceysson, O.; Salvia, M.; Vincent, L.

    1996-04-15

    Carbon fiber reinforced plastics (CFRP) offer high specific mechanical properties (performance vs weight ratio). Since carbon fibers are electrical conductors ({rho} = 2.10{sup {minus}5} {Omega}.m), the measurement of the variations of electrical resistance appears to be a valuable technique for damage detection. In the case of CFRP samples, conductivity is not isotropic but depends on the orientation of the carbon fibers. The electrical conduction of (0{degree}) unidirectional (UD) CFRP parallel to the fibers is due to the current flow along the fibers. This can be modeled using the parallel resistance approach. In this present work, the variation of the electrical conductivity can be taken as an indicator of the evolution of various types of damage in classical longitudinal UD but also in ({+-} 45{degree}) CFRP laminates. By comparison with a more classical non-destructive technique such as Acoustic Emission, it has been shown that it is possible that the electrical resistance measurement allows one to monitor in-situ the evolution of various internal damage nucleation and growth in CFRP such as fiber fractures, intraply matrix cracks and interply delaminations.

  7. High Interlaminar Shear Strength Enhancement of Carbon Fiber/Epoxy Composite through Fiber- and Matrix-Anchored Carbon Nanotube Networks.

    PubMed

    Wang, Yilei; Raman Pillai, Suresh Kumar; Che, Jianfei; Chan-Park, Mary B

    2017-03-15

    To improve the interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composite, networks of multiwalled carbon nanotubes (MWNTs) were grown on micron-sized carbon fibers and single-walled carbon nanotubes (SWNTs) were dispersed into the epoxy matrix so that these two types of carbon nanotubes entangle at the carbon fiber (CF)/epoxy matrix interface. The MWNTs on the CF fiber (CF-MWNTs) were grown by chemical vapor deposition (CVD), while the single-walled carbon nanotubes (SWNTs) were finely dispersed in the epoxy matrix precursor with the aid of a dispersing agent polyimide-graft-bisphenol A diglyceryl acrylate (PI-BDA) copolymer. Using vacuum assisted resin transfer molding, the SWNT-laden epoxy matrix precursor was forced into intimate contact with the "hairy" surface of the CF-MWNT fiber. The tube density and the average tube length of the MWNT layer on CF was controlled by the CVD growth time. The ILSS of the CF-MWNT/epoxy resin composite was examined using the short beam shear test. With addition of MWNTs onto the CF surface as well as SWNTs into the epoxy matrix, the ILSS of CF/epoxy resin composite was 47.59 ± 2.26 MPa, which represented a ∼103% increase compared with the composite made with pristine CF and pristine epoxy matrix (without any SWNT filler). FESEM established that the enhanced composite did not fail at the CF/epoxy matrix interface.

  8. Fabrication and Characterization of Novel Fe-Ni Alloy Coated Carbon Fibers for High-Performance Shielding Materials

    NASA Astrophysics Data System (ADS)

    He, Fang; Li, Junjiao; Chen, Liang; Chen, Lixia; Huang, Yuan

    2015-03-01

    Novel Fe-Ni alloy coated carbon fibers (Fe-Ni-CFs) were prepared via two-step electrodeposition with an initial synthesis of Fe coatings on the activated carbon fibers and followed by the co-deposition of Fe and Ni. The effect of annealing treatment on structure and properties of Fe-Ni-CFs was studied through SEM, TEM, XRD and VSM. The results indicated that the Fe-Ni alloy coatings with the thickness of only 0.25 um are highly wrapped on the surface of carbon fibers. The un-annealed coatings showed high saturation magnetization values with 52 dB from 300-1200 MHz, which mainly due to Fe content (18.4 wt.%) of the coatings meets the requirements of high magnetic perm-alloy. The surface quality, crystallinity and conductivity of the Fe-Ni-CFs were obviously improved despite of the reduction of the saturation magnetization resulted from the bigger grains after annealing. Based on the above aspects, annealing at 400∘C was preferred for the Fe-Ni-CFs to obtain good comprehensive performance. Importantly, the Fe-Ni-CFs filled ABS resin composites showed better Electromagnetic Interference shielding effectiveness than the CFs reinforced ABS composites.

  9. Use of Carbon Fiber Composite Molecular Sieves for Air Separation

    SciTech Connect

    Baker, Frederick S; Contescu, Cristian I; Gallego, Nidia C; Burchell, Timothy D

    2005-09-01

    A novel adsorbent material, 'carbon fiber composite molecular sieve' (CFCMS), has been developed by the Oak Ridge National Laboratory. Its features include high surface area, large pore volume, and a rigid, permeable carbon structure that exhibits significant electrical conductivity. The unique combination of high adsorptive capacity, permeability, good mechanical properties, and electrical conductivity represents an enabling technology for the development of novel gas separation and purification systems. In this context, it is proposed that a fast-cycle air separation process that exploits a kinetic separation of oxygen and nitrogen should be possible using a CFCMS material coupled with electrical swing adsorption (ESA). The adsorption of O{sub 2}, N{sub 2}, and CO{sub 2} on activated carbon fibers was investigated using static and dynamic techniques. Molecular sieving effects in the activated carbon fiber were highlighted by the adsorption of CO{sub 2}, a more sensitive probe molecule for the presence of microporosity in adsorbents. The kinetic studies revealed that O2 was more rapidly adsorbed on the carbon fiber than N{sub 2}, and with higher uptake under equilibrium conditions, providing the fiber contained a high proportion of very narrow micropores. The work indicated that CFCMS is capable of separating O{sub 2} and N{sub 2} from air on the basis of the different diffusion rates of the two molecules in the micropore network of the activated carbon fibers comprising the composite material. In response to recent enquires from several potential users of CFCMS materials, attention has been given to the development of a viable continuous process for the commercial production of CFCMS material. As part of this effort, work was implemented on characterizing the performance of lignin-based activated carbon fiber, a potentially lower cost fiber than the pitch-based fibers used for CFCMS production to date. Similarly, to address engineering issues, measurements were

  10. Tribological properties of metal-matrix composite materials reinforced by superelastic hard carbon particles

    NASA Astrophysics Data System (ADS)

    Ushakova, I. N.; Drozdova, E. I.; Chernogorova, O. P.; Blinov, V. M.; Ekimov, E. A.

    2016-05-01

    Metal-matrix composite materials (CMs) are synthesized from a mixture of a metal powder (Ti, Fe, Co, Ni, Cu, Al-based alloy) and fullerenes (10 wt %). The thermobaric synthesis conditions (700-1000°C, 5-8 GPa) ensure the collapse of fullerene molecules and their transformation into superelastic carbon phase particles with an indentation hardness H IT = 10-37 GPa, an elastic modulus E IT = 60-260 GPa, and an elastic recovery of >80% upon indentation. After reinforcing by superelastic hard carbon, the friction coefficient of CM decreases by a factor of 2-4 as compared to the friction coefficient of the matrix metal, and the abrasive wear resistance increases by a factor of 4-200. Superelastic hard carbon particles are a unique reinforcing material for an increase in the wear resistance and a simultaneous decrease in the friction coefficient of CM.

  11. Application of composites to the selective reinforcement of metallic aerospace structures. [application of structural design criteria for weight reduction

    NASA Technical Reports Server (NTRS)

    Brooks, W. A., Jr.; Mathauser, E. E.; Pride, R. A.

    1972-01-01

    The use of composite materials to selectively reinforce metallic structures provides a low-cost way to reduce weight and a means of minimizing the risks usually associated with the introduction of new materials. An overview is presented of the NASA Langley Research Center programs to identify the advantages and to develop the potential of the selective reinforcement approach to the use of composites. These programs have shown that selective reinforcement provides excellent strength and stiffness improvements to metallic structures. Significant weight savings can be obtained in a cost effective manner. Flight service programs which have been initiated to validate further the merits of selective reinforcement are described.

  12. The dynamic response of carbon fiber-filled polymer composites

    NASA Astrophysics Data System (ADS)

    Dattelbaum, D. M.; Gustavsen, R. L.; Sheffield, S. A.; Stahl, D. B.; Scharff, R. J.; Rigg, P. A.; Furmanski, J.; Orler, E. B.; Patterson, B.; Coe, J. D.

    2012-08-01

    The dynamic (shock) responses of two carbon fiber-filled polymer composites have been quantified using gas gun-driven plate impact experimentation. The first composite is a filament-wound, highly unidirectional carbon fiber-filled epoxy with a high degree of porosity. The second composite is a chopped carbon fiber- and graphite-filled phenolic resin with little-to-no porosity. Hugoniot data are presented for the carbon fiber-epoxy (CE) composite to 18.6 GPa in the through-thickness direction, in which the shock propagates normal to the fibers. The data are best represented by a linear Rankine-Hugoniot fit: Us = 2.87 + 1.17 ×up(ρ0 = 1.536g/cm3). The shock wave structures were found to be highly heterogeneous, both due to the anisotropic nature of the fiber-epoxy microstructure, and the high degree of void volume. Plate impact experiments were also performed on a carbon fiber-filled phenolic (CP) composite to much higher shock input pressures, exceeding the reactants-to-products transition common to polymers. The CP was found to be stiffer than the filament-wound CE in the unreacted Hugoniot regime, and transformed to products near the shock-driven reaction threshold on the principal Hugoniot previously shown for the phenolic binder itself. [19] On-going research is focused on interrogating the direction-dependent dyanamic response and dynamic failure strength (spall) for the CE composite in the TT and 0∘ (fiber) directions.

  13. Reinforcement of metal with liquid-exfoliated inorganic nano-platelets

    NASA Astrophysics Data System (ADS)

    May, Peter; Khan, Umar; Coleman, Jonathan N.

    2013-10-01

    We have prepared metal matrix composites of a pewter alloy filled with liquid-exfoliated Molybdenum Telluride (MoTe2) nano-platelets. The combination of MoTe2 and pewter was chosen due to their near-identical densities, thus reducing the scope for buoyancy-induced separation during melt mixing. The addition of nanofiller results in a doubling of the Young's modulus, Y, for a volume fraction, Vf, of <1% MoTe2, corresponding to a reinforcement of dY/dVf = 110 GPa. We find that this degree of reinforcement to be reasonably consistent with that predicted by a simplified version of Halpin-Tsai theory.

  14. Design synthesis of a boron/epoxy reinforced metal shear web.

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.

    1972-01-01

    An advanced composite shear web design concept has been developed for the Space Shuttle Orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad, boron/epoxy plate with vertical boron/epoxy reinforced stiffeners. Baseline composite and titanium shear resistant designs are compared; the composite concept is 28% lighter than the titanium web. Element test results show the metal cladding effectively reinforces critical composite load transfer and fastener hole areas making the composite web concept practical for other shear structure applications.-

  15. Quantitative validation of carbon-fiber laminate low velocity impact simulations

    DOE PAGES

    English, Shawn A.; Briggs, Timothy M.; Nelson, Stacy M.

    2015-09-26

    Simulations of low velocity impact with a flat cylindrical indenter upon a carbon fiber fabric reinforced polymer laminate are rigorously validated. Comparison of the impact energy absorption between the model and experiment is used as the validation metric. Additionally, non-destructive evaluation, including ultrasonic scans and three-dimensional computed tomography, provide qualitative validation of the models. The simulations include delamination, matrix cracks and fiber breaks. An orthotropic damage and failure constitutive model, capable of predicting progressive damage and failure, is developed in conjunction and described. An ensemble of simulations incorporating model parameter uncertainties is used to predict a response distribution which ismore » then compared to experimental output using appropriate statistical methods. Lastly, the model form errors are exposed and corrected for use in an additional blind validation analysis. The result is a quantifiable confidence in material characterization and model physics when simulating low velocity impact in structures of interest.« less

  16. Quantitative validation of carbon-fiber laminate low velocity impact simulations

    SciTech Connect

    English, Shawn A.; Briggs, Timothy M.; Nelson, Stacy M.

    2015-09-26

    Simulations of low velocity impact with a flat cylindrical indenter upon a carbon fiber fabric reinforced polymer laminate are rigorously validated. Comparison of the impact energy absorption between the model and experiment is used as the validation metric. Additionally, non-destructive evaluation, including ultrasonic scans and three-dimensional computed tomography, provide qualitative validation of the models. The simulations include delamination, matrix cracks and fiber breaks. An orthotropic damage and failure constitutive model, capable of predicting progressive damage and failure, is developed in conjunction and described. An ensemble of simulations incorporating model parameter uncertainties is used to predict a response distribution which is then compared to experimental output using appropriate statistical methods. Lastly, the model form errors are exposed and corrected for use in an additional blind validation analysis. The result is a quantifiable confidence in material characterization and model physics when simulating low velocity impact in structures of interest.

  17. Thermo-oxidative degradation assessment in quasi-isotropic carbon fiber/epoxy composites

    NASA Astrophysics Data System (ADS)

    Daily, Connor; Barnard, Dan J.; Jones, Roger W.; McClelland, John F.; Bowler, Nicola

    2015-03-01

    Components made from polymer matrix composites (PMCs) are finding increasing use in armored vehicles for the purpose of weight savings and fuel efficiency. Often times, these PMC components are installed next to engines, or in other high-temperature environments within the vehicle. The present work investigates the change in surface chemistry and its correlation with changes in the interlaminar shear strength (ILSS) due to accelerated thermo-oxidative aging of a quasi-isotropic carbon fiber reinforced epoxy laminate. Samples are aged isothermally at various temperatures whose selection is guided by degradation steps revealed by thermo-gravimetric analysis. Fourier transform infrared (FTIR) photoacoustic spectroscopy is utilized to identify the chemical changes due to aging, and compression-test results reveal a non-linear decrease in ILSS with increasing aging temperature. A correlation between the FTIR and ILSS data sets suggests that nondestructive FTIR techniques may be used for assessing ILSS of PMCs.

  18. Experimental determinations of the eigenmodes for composite bars made with carbon and Kevlar-carbon fibers

    NASA Astrophysics Data System (ADS)

    Miriţoiu, C. M.; Stănescu, M. M.; Burada, C. O.; Bolcu, D.; Roşca, V.

    2015-11-01

    For modal identification, the single-point excitation method has been widely used in modal tests and it consists in applying a force in a given point and recording the vibratory structure response in all interest points, including the excitation point. There will be presented the experimental recordings for the studied bars (with Kevlar-carbon or carbon fibers), the frequency response function in Cartesian and polar coordinates. By using the frequency response functions we determine the eigenparameters for each bar. We present the final panel of the eigenmodes (with the damping factors, eigenfrequencies and critical damping) for each considered bar. Using the eigenfrequency of the first determined eigenmode, the bars stiffness has been determined. The presented bars can be used in practical engineering for: car or bus body parts, planes body parts, bullet-proof vests, reinforcements for sandwich beams, and so on.

  19. Durability of Continuous Fiber Reinforced Metal Matrix Composites

    DTIC Science & Technology

    1987-10-01

    Wright-Patterson Air Force Base, Ohio, under contract F33615-83-C-3219, Project 2401, Work Unit 24010167, "Durability of Continuous Fiber Metal...determine the range of fatigue failure modes found by previous investigators. Testing performed under MCAIR IRAD had previously shown that failure modes... under tension loading. The fatigue sensitivity is the ratio of net stress in a notched specimen to that in an unnotched specimen at a given life

  20. NDT and SHM of Carbon Fiber Composites using Linear Drive MWM-Arrays

    NASA Technical Reports Server (NTRS)

    Washabaugh, Andrew; Martin, Christopher; Lyons, Robert; Grundy, David; Goldfine, Neil; Russell, Richard; Wincheski, Russell

    2012-01-01

    Carbon fiber composites are used in a wide range of structural applications due to their excellent specific strength and stiffness. However, the anisotropic mechanical and electrical properties associated with the fibers within each composite layer present challenges, and opportunities, for Nondestructive Testing (NDT) methods used to characterize and assess the structure condition. This includes composite condition after manufacture (such as fiber orientation and density, porosity, delamination, and bond strength) and during usage (such as damage from impact, fiber breakage, thermal exposure or applied stress). Ultrasonic and thermographic methods can address some of these challenges, but eddy current methods provide an alternative method for composite structures that contain a conducting material, such as carbon fibers or a metallic liner. This presentation reviews recent advances in the development of eddy current sensors and arrays for carbon fiber composite NDT and Structural Health Monitoring (SHM) applications. The focus is on eddy current sensor constructs with linear drive windings, such as MWM -Arrays, that induce currents primarily within the linear fibers of the composite. By combining this type of sensor construct with micromechanical models that relate composite constituent properties to measurable sensor responses, insight is obtained into the volumetric distribution of electrical properties within the composite and the associated manufacturing, damage, or strain conditions. With knowledge of the fiber layup, this MWM-Array technology is able to detect damage and strain/stress as a function of depth and fiber orientation. This work has been funded by NASA, NA V AIR and the Army for applications ranging from composite overwrapped pressure vessels (COPVs) to aircraft structures and rotorcraft blades. This presentation will specifically present background on the MWM-Array technology, results from the micromechanical modeling effort, and results from