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Sample records for matrix composites irradiated

  1. Thermal response model of polymer matrix composites under laser irradiating

    NASA Astrophysics Data System (ADS)

    Peng, Guo-liang; Zhang, Xiang-hua; Du, Tai-jiao

    2015-05-01

    A numerical study is conducted to determine which model could be used to compute temperature fields of polymer matrix composites under laser irradiating. By using the local thermal non-equilibrium model, solid and gas temperature on surfaces of materials with different volume convection coefficients have been computed and compared under different heat flux. The results show that the assumption of local thermal equilibrium is not reasonable until the heat flux applied to composites is low enough and the volume convection coefficient is big enough. And the gas may be not important for solid temperature when the volume convection coefficient is small.

  2. Effect of γ irradiation on the properties of basalt fiber reinforced epoxy resin matrix composite

    NASA Astrophysics Data System (ADS)

    Li, Ran; Gu, Yizhuo; Yang, Zhongjia; Li, Min; Wang, Shaokai; Zhang, Zuoguang

    2015-11-01

    Gamma-ray (γ-ray) irradiation is a crucial reason for the aging in materials used for nuclear industry. Due to high specific strength and stiffness, light weight and good corrosion resistance, fiber reinforced composites are regarded as an alternative of traditional materials used on nuclear facilities. In this study, basalt fiber (BF)/AG80 epoxy composite laminates were fabricated by autoclave process and treated with 60Co gamma irradiation dose up to 2.0 MGy. Irradiation induced polymer chain scission and oxidation of AG80 resin were detected from physical and chemical analysis. The experimental results show that the tensile and flexural performances of irradiated BF/AG80 composite maintain stable and have a low amplitude attenuation respectively, and the interlaminar shear strength has increased from irradiation dose of 0-1.5 MGy. Furthermore, the comparison between the studied BF composite and reported polymer and composite materials was done for evaluating the γ resistance property of BF composite.

  3. Hybrid matrix fiber composites

    DOEpatents

    Deteresa, Steven J.; Lyon, Richard E.; Groves, Scott E.

    2003-07-15

    Hybrid matrix fiber composites having enhanced compressive performance as well as enhanced stiffness, toughness and durability suitable for compression-critical applications. The methods for producing the fiber composites using matrix hybridization. The hybrid matrix fiber composites include two chemically or physically bonded matrix materials, whereas the first matrix materials are used to impregnate multi-filament fibers formed into ribbons and the second matrix material is placed around and between the fiber ribbons that are impregnated with the first matrix material and both matrix materials are cured and solidified.

  4. Metal matrix composite structures

    SciTech Connect

    Krivov, G.A.; Beletsky, V.M.; Gribkov, A.N.

    1993-12-31

    High strength-weight properties, stiffness and fatigue resistance characteristics together with low sensitivity to stress concentration make metal matrix composites (MMC) rather promising for their use in structures. Metal matrix composites consist of a matrix (aluminum, magnesium, titanium and their alloys are the most frequently used) and reinforcers (carbon and boron fibers, high-strength steel wire, silicon carbide whiskers, etc.). This work considers various types of MMC and their applications in structures. The methods of structure production from metal matrix CM of aluminum-boron system with the help of machining, deformation, part joining by welding and riveting are given.

  5. Aluminum Metal Matrix Composites

    SciTech Connect

    Hunt, Warren; Herling, Darrell R.

    2004-02-01

    Metal matrix composites comprise a relatively wide range of materials defined by the metal matrix, reinforcement type, and reinforcement geometry. In the area of the matrix, most metallic systems have been explored for use in metal matrix composites, including Al, Be, Mg, Ti, Fe, Ni, Co, and Ag. By far, the largest usage is in aluminum matrix composites. From a reinforcement perspective, the materials used are typically ceramics since they provide a very desirable combination of stiffness, strength, and relatively low density. Candidate reinforcement materials include SiC, Al2O3, B4C, TiC, TiB2, graphite, and a number of other ceramics. In addition, there has been work on metallic materials as reinforcements, notably W and steel fibers. The morphology of the reinforcement material is another variable of importance in metal matrix composites. The three major classes of reinforcement morphology are continuous fiber, chopped fiber or whisker, and particulate. Typically, the selection of the reinforcement morphology is determined by the desired property/cost combination. Generally, continuous fiber reinforced MMCs provide the highest properties in the direction of the fiber orientation but are the most expensive. Chopped fiber and whisker reinforced materials can produce significant property improvements in the plane or direction of their orientation, at somewhat lower cost. Particulates provide a comparatively more moderate but isotropic increase in properties and are typically available at the lowest cost. By adding to the three variables of metallic matrix, reinforcement material, and reinforcement morphology the further options of reinforcement volume fraction, orientation, and matrix alloy composition and heat treatment, it is apparent that there is a very wide range of available material combinations and resultant properties. This paper will focus on how MMCs have been applied in specific application areas.

  6. Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Mortensen, Andreas; Llorca, Javier

    2010-08-01

    In metal matrix composites, a metal is combined with another, often nonmetallic, phase to produce a novel material having attractive engineering attributes of its own. A subject of much research in the 1980s and 1990s, this class of materials has, in the past decade, increased significantly in variety. Copper matrix composites, layered composites, high-conductivity composites, nanoscale composites, microcellular metals, and bio-derived composites have been added to a palette that, ten years ago, mostly comprised ceramic fiber- or particle-reinforced light metals together with some well-established engineering materials, such as WC-Co cermets. At the same time, research on composites such as particle-reinforced aluminum, aided by novel techniques such as large-cell 3-D finite element simulation or computed X-ray microtomography, has served as a potent vehicle for the elucidation of the mechanics of high-contrast two-phase elastoplastic materials, with implications that range well beyond metal matrix composites.

  7. Hybridized polymer matrix composites

    NASA Technical Reports Server (NTRS)

    House, E. E.; Hoggatt, J. T.; Symonds, W. A.

    1980-01-01

    The extent to which graphite fibers are released from resin matrix composites that are exposed to fire and impact conditions was determined. Laboratory simulations of those conditions that could exist in the event of an aircraft crash and burn situation were evaluated. The effectiveness of various hybridizing concepts in preventing this release of graphite fibers were also evaluated. The baseline (i.e., unhybridized) laminates examined were prepared from commercially available graphite/epoxy, graphite/polyimide, and graphite/phenolic materials. Hybridizing concepts investigated included resin fillers, laminate coatings, resin blending, and mechanical interlocking of the graphite reinforcement. The baseline and hybridized laminates' mechanical properties, before and after isothermal and humidity aging, were also compared. It was found that a small amount of graphite fiber was released from the graphite/epoxy laminates during the burn and impact conditions used in this program. However, the extent to which the fibers were released is not considered a severe enough problem to preclude the use of graphite reinforced composites in civil aircraft structure. It also was found that several hybrid concepts eliminated this fiber release. Isothermal and humidity aging did not appear to alter the fiber release tendencies.

  8. Carbon Nanotube Aluminum Matrix Composites

    DTIC Science & Technology

    2010-08-01

    replacement of air space with the polymer matrix. A similar affinity is not known to exist between CNTs and aluminum , where the wetting angle between...Carbon Nanotube Aluminum Matrix Composites by Brent J. Carey, Jerome T. Tzeng, and Shashi Karna ARL-TR-5252 August 2010...Nanotube Aluminum Matrix Composites Brent J. Carey, Jerome T. Tzeng, and Shashi Karna Weapons and Materials Research Directorate, ARL

  9. Micromechanics for ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Chamis, C. C.

    1991-01-01

    The fiber substructuring concepts and the micromechanics equations that are embedded in the Ceramic Matrix Composite Analyzer (CEMCAN) computer code are described as well as the code itself, its current features and capabilities, and some examples to demonstrate the code's versatility. The methodology is equally applicable to metal matrix and polymer matrix composites. The prediction of ply mechanical and thermal properties agree very well with the existing models in the Integrated Composite Analyzer and the Ceramic Matrix Composite Analyzer, lending credence to the fiber substructuring approach. Fiber substructuring can capture greater local detail than conventional unit-cell-based micromechanical theories. It offers promise in simulating complex aspects of micromechanics in ceramic matrix composites.

  10. Recycling of aluminum matrix composites

    SciTech Connect

    Nishida, Yoshinori; Izawa, Norihisa; Kuramasu, Yukio

    1999-03-01

    Separation of matrix metals in composites was tried on alumina short fiber-reinforced aluminum and 6061 alloy composites and SiC whisker-reinforced 6061 alloy composite for recycling. It is possible to separate molten matrix metals from fibers in the composites using fluxes that are used for melt treatment to remove inclusions. About 50 vol pct of the matrix metals was separated from the alumina short fiber-reinforced composites. The separation ratio of the matrix from the SiC whisker-reinforced 6061 alloy composite was low and about 20 vol pct. The separation mechanism was discussed thermodynamically using interface free energies. Since the flux/fiber interface energy is smaller than the aluminum/fiber interface energy, the replacement of aluminum with fluxes in composites takes place easily. Gases released by the decomposition of fluxes act an important role in pushing out the molten matrix metal from the composite. The role was confirmed by the great amount cavity formed in the composite after the matrix metal flowed out.

  11. Titanium matrix composites: Mechanical behavior

    SciTech Connect

    Mall, S.; Nicholas, T.

    1997-12-31

    Because of their unique mix of properties and behavior in high-performance applications, Titanium Matrix Composites are presently the focus of special research and development activity. This new book presents a review of current technology on the mechanical behavior of these materials. Each chapter was prepared specifically for this new book by one or more specialists in this subject. This book is divided into the following chapters: (1) Introduction; (2) Monotonic Response; (3) Micromechanical Theories for Inelastic Fibrous Composite Materials; (4) Interfaces in Metal Matrix Composites; (5) Fatigue Failure Mechanisms in TMCs; (6) Fatigue and Thermomechanical Fatigue Life Prediction; (7) Creep Behavior of Fiber Reinforced Titanium Matrix Composites; (8) Fatigue Crack Growth; (9) Notch Strength of Titanium Matrix Composites; and (10) Micromechanical Analysis and Modeling.

  12. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1990-01-01

    Compositions of matter consisting of matrix matrials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  13. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, J.J.; Honnell, R.E.; Gibbs, W.S.

    1991-12-03

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions are disclosed. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms. 3 figures.

  14. Molybdenum disilicide alloy matrix composite

    DOEpatents

    Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

    1991-01-01

    Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

  15. Molybdenum disilicide matrix composite

    DOEpatents

    Petrovic, John J.; Carter, David H.; Gac, Frank D.

    1990-01-01

    A composition consisting of an intermetallic compound, molybdenum disilicide, which is reinforced with VS silicon carbide whiskers dispersed throughout it and a method of making the reinforced composition. Use of the reinforcing material increases fracture toughness at low temperatures and strength at high temperatures, as compared to pure molybdenum disilicide.

  16. Molybdenum disilicide matrix composite

    DOEpatents

    Petrovic, John J.; Carter, David H.; Gac, Frank D.

    1991-01-01

    A composition consisting of an intermetallic compound, molybdenum disilicide, which is reinforced with VS silicon carbide whiskers dispersed throughout it and a method of making the reinforced composition. Use of the reinforcing material increases fracture toughness at low temperatures and strength at high temperatures, as compared to pure molybdenum disilicide.

  17. High Temperature Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    1985-01-01

    These are the proceedings of the High Temperature Polymer Matrix Composites Conference held at the NASA Lewis Research Center on March 16 to 18, 1983. The purpose of the conference is to provide scientists and engineers working in the field of high temperature polymer matrix composites an opportunity to review, exchange, and assess the latest developments in this rapidly expanding area of materials technology. Technical papers are presented in the following areas: (1) matrix development; (2) adhesive development; (3) characterization; (4) environmental effects; and (5) applications.

  18. High temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Serafini, Tito T. (Editor)

    1987-01-01

    These are the proceedings of the High Temperature Polymer Matrix Composites Conference held at the NASA Lewis Research Center on March 16 to 18, 1983. The purpose of the conference is to provide scientists and engineers working in the field of high temperature polymer matrix composites an opportunity to review, exchange, and assess the latest developments in this rapidly expanding area of materials technology. Technical papers are presented in the following areas: (1) matrix development; (2) adhesive development; (3) Characterization; (4) environmental effects; and (5) applications.

  19. Hybridized polymer matrix composite

    NASA Technical Reports Server (NTRS)

    Stern, B. A.; Visser, T.

    1981-01-01

    Under certain conditions of combined fire and impact, graphite fibers are released to the atmosphere by graphite fiber composites. The retention of graphite fibers in these situations is investigated. Hybrid combinations of graphite tape and cloth, glass cloth, and resin additives are studied with resin systems. Polyimide resins form the most resistant composites and resins based on simple novolac epoxies the least resistant of those tested. Great improvement in the containment of the fibers is obtained in using graphite/glass hybrids, and nearly complete prevention of individual fiber release is made possible by the use of resin additives.

  20. Ceramic matrix composite article and process of fabricating a ceramic matrix composite article

    SciTech Connect

    Cairo, Ronald Robert; DiMascio, Paul Stephen; Parolini, Jason Robert

    2016-01-12

    A ceramic matrix composite article and a process of fabricating a ceramic matrix composite are disclosed. The ceramic matrix composite article includes a matrix distribution pattern formed by a manifold and ceramic matrix composite plies laid up on the matrix distribution pattern, includes the manifold, or a combination thereof. The manifold includes one or more matrix distribution channels operably connected to a delivery interface, the delivery interface configured for providing matrix material to one or more of the ceramic matrix composite plies. The process includes providing the manifold, forming the matrix distribution pattern by transporting the matrix material through the manifold, and contacting the ceramic matrix composite plies with the matrix material.

  1. Curing of epoxy matrix composite in stratosphere

    NASA Astrophysics Data System (ADS)

    Kondyurin, Alexey; Kondyurina, Irina; Bilek, Marcela

    Large structures for habitats, greenhouses, space bases, space factories are needed for next stage of space exploitation. A new approach enabling large-size constructions in space relies on the use of the polymerization technology of fiber-filled composites with a curable polymer matrix applied in the free space environment. The polymerisation process is proposed for the material exposed to high vacuum, dramatic temperature changes, space plasma, sun irradiation and atomic oxygen (in low Earth orbit), micrometeorite fluence, electric charging and microgravitation. The stratospheric flight experiments are directed to an investigation of the curing polymer matrix under the stratospheric conditions on. The unique combination of low atmospheric pressure, high intensity UV radiation including short wavelength UV and diurnal temperature variations associated with solar irradiation strongly influences the chemical processes in polymeric materials. The first flight experiment with uncured composites was a part of the NASA scientific balloon flight program realised at the NASA stratospheric balloon station in Alice Springs, Australia. A flight cassette installed on payload was lifted with a “zero-pressure” stratospheric balloon filled with Helium. Columbia Scientific Balloon Facility (CSBF) provided the launch, flight telemetry and landing of the balloon and payload. A cassette of uncured composite materials with an epoxy resin matrix was exposed 3 days in the stratosphere (40 km altitude). The second flight experiment was realised in South Australia in 2012, when the cassette was exposed in 27 km altitude. An analysis of the chemical structure of the composites showed, that the space irradiations are responsible for crosslinking of the uncured polymers exposed in the stratosphere. The first prepreg in the world was cured successfully in stratosphere. The investigations were supported by Alexander von Humboldt Foundation, NASA and RFBR (12-08-00970) grants.

  2. Hybridized polymer matrix composites

    NASA Technical Reports Server (NTRS)

    London, A.

    1981-01-01

    Design approaches and materials are described from which are fabricated pyrostatic graphite/epoxy (Gr/Ep) laminates that show improved retention of graphite particulates when subjected to burning. Sixteen hybridized plus two standard Gr/Ep laminates were designed, fabricated, and tested in an effort to eliminate the release of carbon (graphite) fiber particles from burned/burning, mechanically disturbed samples. The term pyrostatic is defined as meaning mechanically intact in the presence of fire. Graphite particulate retentive laminates were constructed whose constituent materials, cost of fabrication, and physical and mechanical properties were not significantly different from existing Gr/Ep composites. All but one laminate (a Celion graphite/bis-maleimide polyimide) were based on an off-the-shelf Gr/Ep, the AS-1/3501-5A system. Of the 16 candidates studied, four thin (10-ply) and four thick (50-ply) hybridized composites are recommended.

  3. Sapphire reinforced alumina matrix composites

    NASA Technical Reports Server (NTRS)

    Jaskowiak, Martha H.; Setlock, John A.

    1994-01-01

    Unidirectionally reinforced A1203 matrix composites have been fabricated by hot pressing. Approximately 30 volume % of either coated or uncoated sapphire fiber was used as reinforcement. Unstabilized ZrO2 was applied as the fiber coating. Composite mechanical behavior was analyzed both after fabrication and after additional heat treatment. The results of composite tensile tests were correlated with fiber-matrix interfacial shear strengths determined from fiber push-out tests. Substantially higher strength and greater fiber pull-out were observed for the coated fiber composites for all processing conditions studied. The coated fiber composites retained up to 95% and 87% of their as-fabricated strength when heat treated at 14000C for 8 or 24 hours, respectively. Electron microscopy analysis of the fracture surfaces revealed extensive fiber pull-out both before and after heat treatment.

  4. Hybridized polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Henshaw, J.

    1983-01-01

    Methods of improving the fire resistance of graphite epoxy composite laminates were investigated with the objective of reducing the volume of loose graphite fibers disseminated into the airstream as the result of a high intensity aircraft fuel fire. Improvements were sought by modifying the standard graphite epoxy systems without significantly negating their structural effectiveness. The modifications consisted primarily of an addition of a third constituent material such as glass fibers, glass flakes, carbon black in a glassy resin. These additions were designed to encourage coalescense of the graphite fibers and thereby reduce their aerodynamic float characteristics. A total of 38 fire tests were conducted on thin (1.0 mm) and thick (6.0 mm) hybrid panels.

  5. Corrosion of Titanium Matrix Composites

    SciTech Connect

    Covino, B.S., Jr.; Alman, D.E.

    2002-09-22

    The corrosion behavior of unalloyed Ti and titanium matrix composites containing up to 20 vol% of TiC or TiB{sub 2} was determined in deaerated 2 wt% HCl at 50, 70, and 90 degrees C. Corrosion rates were calculated from corrosion currents determined by extrapolation of the tafel slopes. All curves exhibited active-passive behavior but no transpassive region. Corrosion rates for Ti + TiC composites were similar to those for unalloyed Ti except at 90 degrees C where the composites were slightly higher. Corrosion rates for Ti + TiB{sub 2} composites were generally higher than those for unalloyed Ti and increased with higher concentrations of TiB{sub 2}. XRD and SEM-EDS analyses showed that the TiC reinforcement did not react with the Ti matrix during fabrication while the TiB{sub 2} reacted to form a TiB phase.

  6. The effect of neutron irradiation on the mechanical properties of C/SiC composites

    SciTech Connect

    Shih, Chunghao; Katoh, Yutai; Snead, Lance Lewis; Steinbeck, John

    2013-01-01

    The effects of neutron irradiation to 3.5 and 9.5 dpa at 730 C on a 2D plain woven carbon fiber reinforced polymer derived SiC matrix composite are presented. For both fluences, the irradiation caused in-plane contraction and trans-plane expansion. Irradiation also caused substantial reduction in composite flexural strength (54%) and increase in flexural tangent modulus (+85%). The extents of dimensional/ mechanical property changes were greater for the higher fluence irradiated samples. Those changes suggest the instability of the polymer derived SiC matrix following irradiation. The nature of the mechanical property changes suggest increased clamping stress between the fiber and the matrix. The composite property changes are explained in terms of irradiation effects on composite constituents and are compared with carbon fiber reinforced carbon matrix composite as a reference material.

  7. The effect of neutron irradiation on the mechanical properties of C/SiC composites

    NASA Astrophysics Data System (ADS)

    Shih, Chunghao; Katoh, Yutai; Snead, Lance L.; Steinbeck, John

    2013-08-01

    The effects of neutron irradiation to 3.5 and 9.5 dpa at 730 °C on a 2D plain woven carbon fiber reinforced polymer derived SiC matrix composite are presented. For both fluences, the irradiation caused in-plane contraction and trans-plane expansion. Irradiation also caused substantial reduction in composite flexural strength (-54%) and increase in flexural tangent modulus (+85%). The extents of dimensional/mechanical property changes were greater for the higher fluence irradiated samples. Those changes suggest the instability of the polymer derived SiC matrix following irradiation. The nature of the mechanical property changes suggest increased clamping stress between the fiber and the matrix. The composite property changes are explained in terms of irradiation effects on composite constituents and are compared with carbon fiber reinforced carbon matrix composite as a reference material.

  8. High temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    1987-01-01

    With the increased emphasis on high performance aircraft the need for lightweight, thermal/oxidatively stable materials is growing. Because of their ease of fabrication, high specific strength, and ability to be tailored chemically to produce a variety of mechanical and physical properties, polymers and polymer matrix composites present themselves as attractive materials for a number of aeropropulsion applications. In the early 1970s researchers at the NASA Lewis Research Center developed a highly processable, thermally stable (600 F) polyimide, PMR-15. Since that time, PMR-15 has become commercially available and has found use in military aircraft, in particular, the F-404 engine for the Navy's F/A-18 strike fighter. The NASA Lewis'contributions to high temperature polymer matrix composite research will be discussed as well as current and future directions.

  9. Metal Matrix Composites Directionally Solidified

    NASA Astrophysics Data System (ADS)

    Ares, Alicia Esther; Schvezov, Carlos Enrique

    The present work is focus on studying the dendritic solidification of metal matrix composites, MMCs, (using zinc-aluminum, ZA, alloys as matrix and the addition of SiC and Al2O3 particles). The compounds were obtained by as-cast solidification, under continuous stirring and in a second stage were directionally solidified in order to obtain different dendritic growth (columnar, equiaxed and columnar-to-equiaxed transition (CET)). The results in MMCs were compared with those obtained in directional solidification of ZA alloys, primarily with regard to structural parameters. The size and evolution of microstructure, according to the size of the MMCs particles and the variation of the thermal parameters was analyzing. In general it was found that the size of the microstructure (secondary dendritic spacing) decreases with the increase of particles in the matrix. When cooling rate increases, particle size decreases, and a higher cooling rate causes finer and more homogeneous dendrites Also, the segregation which was found in the matrix of the composites was significantly less than in the case of ZA alloys.

  10. Characterization of Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Daniel, I. M.; Chun, H. J.; Karalekas, D.

    1994-01-01

    Experimental methods were developed, adapted, and applied to the characterization of a metal matrix composite system, namely, silicon carbide/aluminim (SCS-2/6061 Al), and its constituents. The silicon carbide fiber was characterized by determining its modulus, strength, and coefficient of thermal expansion. The aluminum matrix was characterized thermomechanically up to 399 C (750 F) at two strain rates. The unidirectional SiC/Al composite was characterized mechanically under longitudinal, transverse, and in-plane shear loading up to 399 C (750 F). Isothermal and non-isothermal creep behavior was also measured. The applicability of a proposed set of multifactor thermoviscoplastic nonlinear constitutive relations and a computer code was investigated. Agreement between predictions and experimental results was shown in a few cases. The elastoplastic thermomechanical behavior of the composite was also described by a number of new analytical models developed or adapted for the material system studied. These models include the rule of mixtures, composite cylinder model with various thermoelastoplastic analyses and a model based on average field theory. In most cases satisfactory agreement was demonstrated between analytical predictions and experimental results for the cases of stress-strain behavior and thermal deformation behavior at different temperatures. In addition, some models yielded detailed three-dimensional stress distributions in the constituents within the composite.

  11. Metal-matrix composites: Status and prospects

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Applications of metal matrix composites for air frames and jet engine components are discussed. The current state of the art in primary and secondary fabrication is presented. The present and projected costs were analyzed to determine the cost effectiveness of metal matrix composites. The various types of metal matrix composites and their characteristics are described.

  12. Irradiation effects on the mechanical properties of composite organic insulators

    SciTech Connect

    Egusa, S.; Kirk, M.A.; Birtcher, R.C.; Hagiwara, M.; Kawanishi, S.

    1983-01-01

    Four kinds of cloth-filled organic composites (filler: glass or carbon fiber; matrix: epoxy or polymide resin) were irradiated with 2-MeV electrons at room temperature, and were examined with regard to the mechanical properties. Following irradiation, the Young's (tensile) modulus of these composites remains practically unchanged even after irradiation up to 15,000 Mrad. The shear modulus and the ultimate strength, on the other hand, begin to decrease after the absorbed dose reaches about 2000 Mrad for the glass/epoxy composite and about 5000 approx. 10,000 Mrad for the other composites. This result is ascribed to the decrease in the capacity of load transfer from the matrix to the fiber due to the radiation-induced debonding at the interface. As to the fracture behavior, the propagation energy increases from the beginning of irradiation. This result is attributed to the radiation-induced decrease in the bonding energy at the interface. The same study was made also for these composites and an alumina fiber-epoxy composite irradiated with fast neutrons at room temperature and 5/sup 0/K. 7 figures, 1 table.

  13. Enterphase Integrity of Neutron Irradiated SiC Composites

    SciTech Connect

    Lara-Curzio, E.; Snead, L.L.

    1999-11-30

    SiC/SiC composites were fabricated from Hi-Nicalon{trademark} fibers with carbon, porous SiC and multilayer SiC interphases. These materials were then irradiated in the High Flux Beam Reactor with fast neutrons at 260 and 900-1060 degrees C to a dose of 1.1X10{sup 25} n/m{sup 2} corresponding to 1.1 displacements per atom (dpa). Results are presented for bend strength of both non-irradiated and irradiated materials. Within the interphases studied the multilayer SiC interphase material showed the least degradation (8-20%) in ultimate bend stress, while porous SiC underwent the greatest degradation ({approximately}35%). The Fiber matrix interphases are studied with TEM for both nonirradiated and irradiated materials. While no irradiation induced microstructural evolution of the interphase was observed, debonding of the interphase from the fiber was observed for all cases. This debonding is attributed to tensile stresses developed at the interface due to densification of the Hi-Nicalon{trademark} fiber. Residual stress analysis of the fiber matrix interface indicates that the irradiation-induced densification of Hi-Nicalon{trademark} and the volumetric expansion of the CVD SiC matrix cause tensile stresses well in excess of those which can be withstood by these, or any other viable SiC composite interphase.

  14. Ceramic matrix and resin matrix composites: A comparison

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.

    1987-01-01

    The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.

  15. Evaluation of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Okelly, K. P.

    1971-01-01

    The results of an evaluation of candidate metal-matrix composite materials for shuttle space radiators mounted to external structure are presented. The evaluation was specifically applicable to considerations of the manufacturing and properties of a potential space radiator. Two candidates, boron/aluminum and graphite/aluminum were obtained or made in various forms and tested in sufficient depth to allow selection of one of the two for future scale-up programs. The effort accomplished on this program verified that aluminum reinforced with boron was within the state-of-the-art in industry and possessed properties usable in the external skin areas available for shuttle radiators where re-entry temperatures will not exceed 800 F. It further demonstrated that graphite/aluminum has an apparently attractive future for space applications but requires extension development prior to scale-up.

  16. Thermoplastic matrix composite processing model

    NASA Technical Reports Server (NTRS)

    Dara, P. H.; Loos, A. C.

    1985-01-01

    The effects the processing parameters pressure, temperature, and time have on the quality of continuous graphite fiber reinforced thermoplastic matrix composites were quantitatively accessed by defining the extent to which intimate contact and bond formation has occurred at successive ply interfaces. Two models are presented predicting the extents to which the ply interfaces have achieved intimate contact and cohesive strength. The models are based on experimental observation of compression molded laminates and neat resin conditions, respectively. Identified as the mechanism explaining the phenomenon by which the plies bond to themselves is the theory of autohesion (or self diffusion). Theoretical predictions from the Reptation Theory between autohesive strength and contact time are used to explain the effects of the processing parameters on the observed experimental strengths. The application of a time-temperature relationship for autohesive strength predictions is evaluated. A viscoelastic compression molding model of a tow was developed to explain the phenomenon by which the prepreg ply interfaces develop intimate contact.

  17. Electron beam irradiation of dental composites.

    PubMed

    Behr, Michael; Rosentritt, Martin; Faltermeier, Andreas; Handel, Gerhard

    2005-09-01

    Electron beam irradiation can be used to influence the mechanical properties of polymers. It was the aim of this study to investigate whether dental composites can benefit from irradiation in order to achieve increased fracture toughness, work of fracture, hardness or less wear. Two hundred rectangular specimens of five veneering composites were electron beam irradiated with 25, 100 and 200 kGy using an electron accelerator of 10 MeV. Fracture toughness, work of fracture, Vickers hardness, color changes and three-medium wear were measured and compared with non-irradiated specimens. Visible color changes (DeltaE>3) were observed with all composites and with all dose rates. Fracture toughness, work of fracture, Vickers hardness and resistance against wear increased significantly with few exceptions. Composites with a simple curing process needed higher dose rates while systems with a more complex curing procedure should be irradiated with lower dose rates. Electron beam irradiation can significantly change the mechanical properties of dental composites. However, color changes can limit the use of irradiation for dentistry.

  18. Microstructure of Matrix in UHTC Composites

    NASA Technical Reports Server (NTRS)

    Johnson, Sylvia; Stackpoole, Margaret; Gusman, Michael I.; Chavez-Garia Jose; Doxtad, Evan

    2011-01-01

    Approaches to controlling the microstructure of Ultra High Temperature Ceramics (UHTCs) are described.. One matrix material has been infiltrated into carbon weaves to make composite materials. The microstructure of these composites is described.

  19. Multiscale Modeling of Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Mital, Subodh K.; Pineda, Evan J.; Arnold, Steven M.

    2015-01-01

    Results of multiscale modeling simulations of the nonlinear response of SiC/SiC ceramic matrix composites are reported, wherein the microstructure of the ceramic matrix is captured. This micro scale architecture, which contains free Si material as well as the SiC ceramic, is responsible for residual stresses that play an important role in the subsequent thermo-mechanical behavior of the SiC/SiC composite. Using the novel Multiscale Generalized Method of Cells recursive micromechanics theory, the microstructure of the matrix, as well as the microstructure of the composite (fiber and matrix) can be captured.

  20. Fracture surfaces of irradiated composites

    NASA Technical Reports Server (NTRS)

    Milkovich, Scott M.; Sykes, George F., Jr.; Herakovich, Carl T.

    1987-01-01

    Electron microscopy was used to analyze the fracture surfaces of T300/934 graphite/epoxy unidirectional off-axis tensile coupons which were subjected to 1.0-MeV electron radiation at a rate of 50 Mrad/h for a total dose of 10 Grad. Fracture surfaces from irradiated and nonirradiated specimens tested at 116 K, room temperature, and 394 K were analyzed to assess the influence of radiation and temperature on the mode of failure and variations in constituent material as a function of environmental exposure. Micrographs of fracture surfaces indicate that irradiated specimens are more brittle than nonirradiated specimens at low temperatures. However, at elevated temperatures the irradiated specimens exhibit significantly more plasticity than nonirradiated specimens.

  1. THERMAL DIFFUSIVITY/CONDUCTIVITY OF IRRADIATED HI-NICALON (Trademark) 2D-SICf/SIC COMPOSITE

    SciTech Connect

    Youngblood, Gerald E.; Senor, David J.; Jones, Russell H.

    2003-06-15

    The H2L model was used to critically assess degradation within the individual fiber, fiber coating and matrix components for irradiated 2D-SiCf/SiC composite made with an ICVI-SiC matrix and Hi-Nicalon (Trademark) fabric. The composites were made with either a 1.044-micron (“thick”) or a 0.110-micron (“thin”) PyC fiber coating and were irradiated in the HFIR reactor as part of the JUPITER 12J (355 degrees C, 7.1 dpa-SiC) or 14J (330 and 800 degrees C, 5.8 and 7.2 dpa-SiC, respectively) series. Laser flash diffusivity measurements were made on representative samples before and after irradiation and after various annealing treatments. The ratio of the transverse thermal conductivity after to before irradiation K(sub-irr)/K(sub-zero) determined at the irradiation temperatures and predicted by the H2L model were: 0.18, 0.23 and 0.29 for the 330, 355 and 800 degrees C irradiations, respectively. Thermal diffusivity measurements in air, argon, helium and vacuum indicated that physical separation of the fiber/matrix interface was minimal after the irradiations, but was significant after annealing irradiated composites to 1200 degrees C. These results suggest that during irradiation to 6 dpa or more radial swelling of the PyC interface would compensate for the radial shrinkage of the Hi-Nicalon (Trademark) fiber and the SiC matrix swelling. The fiber shrinkage is due to irradiation-induced grain-growth and recrystallization and the matrix swelling is due to accumulation of irradiation-induced point defects. However, when the irradiation induced swelling in the matrix and fiber coating components was removed by recombination of point defects during high temperature annealing there was significant fiber/matrix separation.

  2. High-temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    1990-01-01

    Polymers research at the NASA Lewis Research Center has produced high-temperature, easily processable resin systems, such as PMR-15. In addition, the Polymers Branch has investigated ways to improve the mechanical properties of polymers and the microcracking resistance of polymer matrix composites in response to industry need for new and improved aeropropulsion materials. Current and future research in the Polymers Branch is aimed at advancing the upper use temperature of polymer matrix composites to 700 F and beyond by developing new resins, by examining the use of fiber reinforcements other than graphite, and by developing coatings for polymer matrix composites to increase their oxidation resistance.

  3. Metal matrix composites microfracture: Computational simulation

    NASA Technical Reports Server (NTRS)

    Mital, Subodh K.; Caruso, John J.; Chamis, Christos C.

    1990-01-01

    Fiber/matrix fracture and fiber-matrix interface debonding in a metal matrix composite (MMC) are computationally simulated. These simulations are part of a research activity to develop computational methods for microfracture, microfracture propagation and fracture toughness of the metal matrix composites. The three-dimensional finite element model used in the simulation consists of a group of nine unidirectional fibers in three by three unit cell array of SiC/Ti15 metal matrix composite with a fiber volume ration of 0.35. This computational procedure is used to predict the fracture process and establish the hierarchy of fracture modes based on strain energy release rate. It is also used to predict stress redistribution to surrounding matrix-fibers due to initial and progressive fracture of fiber/matrix and due to debonding of fiber-matrix interface. Microfracture results for various loading cases such as longitudinal, transverse, shear and bending are presented and discussed. Step-by-step procedures are outlined to evaluate composite microfracture for a given composite system.

  4. Metal matrix composites microfracture - Computational simulation

    NASA Technical Reports Server (NTRS)

    Mital, S. K.; Caruso, J. J.; Chamis, C. C.

    1990-01-01

    Fiber/matrix fracture and fiber-matrix interface debonding in a metal matrix composite (MMC) are computationally simulated. These simulations are part of a research activity to develop computational methods for microfracture, microfracture propagation and fracture toughness of the metal matrix composites. The three-dimensional finite element model used in the simulation consists of a group of nine unidirectional fibers in three by three unit cell array of SiC/Ti15 metal matrix composite with a fiber volume ration of 0.35. This computational procedure is used to predict the fracture process and establish the hierarchy of fracture modes based on strain energy release rate. It is also used to predict stress redistribution to surrounding matrix-fibers due to initial and progressive fracture of fiber/matrix and due to debonding of fiber-matrix interface. Microfracture results for various loading cases such as longitudinal, transverse, shear and bending are presented and discussed. Step-by-step procedures are outlined to evaluate composite microfracture for a given composite system.

  5. Effects of. gamma. irradiation on cartilage matrix calcification

    SciTech Connect

    Nijweide, P.J.; Burger, E.H.; van Delft, J.L.; Kawilarange-de Haas, E.W.M.; Wassenaar, A.M.; Mellink, J.H.

    1980-10-01

    The effect of ..gamma.. irradiation on cartilage matrix calcification was studied in vitro. Metatarsal bones of 14- to 17-day-old embryonic mice were dissected and cultured under various conditions. Prior to culture, half of the metatarsal bones received absorbed doses of 1.0 to 30.0 Gy ..gamma.. radiation. Their paired counterparts served as controls. Irradiation inhibited longitudinal growth and calcification of the cartilage matrix during culture. In addition, a number of histological changes were noted. The inhibition of matrix calcification appeared to be due to an inhibition of the intracellular calcium accumulation. The formation of extracellular calcification foci and the growth of the calcified area already present at the moment of explanation were not inhibited during culture.

  6. Processing of magnesia pyrochlore composites for inert matrix materials

    NASA Astrophysics Data System (ADS)

    Yates, S. J.; Xu, P.; Wang, J.; Tulenko, J. S.; Nino, J. C.

    2007-05-01

    Inert matrix (IM) materials for nuclear fuel in light water reactors must meet several critical requirements that include high temperature stability, good irradiation behaviour, high thermal conductivity, and hot water corrosion resistance. MgO possesses all of the necessary requirements for an ideal IM candidate, except hot water corrosion resistance. A composite approach is being investigated in order to improve the corrosion resistance of MgO, while simultaneously taking advantage of the high thermal conductivity of MgO and its ability to be reprocessed in nitric acid. MgO-pyrochlore composite compositions are fabricated based on neutronic property simulations for assessment as potential IM materials. The selected pyrochlore compositions are synthesized by both sol gel and solid state processing, and how composite processing affects the microstructure will be discussed. Among the multiple composite processing approaches investigated, ball milling produces the most homogeneous and consistent microstructures.

  7. Celsian Glass-Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Dicarlo, James A.

    1996-01-01

    Glass-ceramic matrix reinforced fiber composite materials developed for use in low dielectric applications, such as radomes. Materials strong and tough, exhibit low dielectric properties, and endure high temperatures.

  8. Micromechanical Modeling of Woven Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Pindera, Marek-Jerzy

    1997-01-01

    This report presents the results of an extensive micromechanical modeling effort for woven metal matrix composites. The model is employed to predict the mechanical response of 8-harness (8H) satin weave carbon/copper (C/Cu) composites. Experimental mechanical results for this novel high thermal conductivity material were recently reported by Bednarcyk et al. along with preliminary model results. The micromechanics model developed herein is based on an embedded approach. A micromechanics model for the local (micro-scale) behavior of the woven composite, the original method of cells (Aboudi), is embedded in a global (macro-scale) micromechanics model (the three-dimensional generalized method of cells (GMC-3D) (Aboudi). This approach allows representation of true repeating unit cells for woven metal matrix composites via GMC-3D, and representation of local effects, such as matrix plasticity, yarn porosity, and imperfect fiber-matrix bonding. In addition, the equations of GMC-3D were reformulated to significantly reduce the number of unknown quantities that characterize the deformation fields at the microlevel in order to make possible the analysis of actual microstructures of woven composites. The resulting micromechanical model (WCGMC) provides an intermediate level of geometric representation, versatility, and computational efficiency with respect to previous analytical and numerical models for woven composites, but surpasses all previous modeling work by allowing the mechanical response of a woven metal matrix composite, with an elastoplastic matrix, to be examined for the first time. WCGMC is employed to examine the effects of composite microstructure, porosity, residual stresses, and imperfect fiber-matrix bonding on the predicted mechanical response of 8H satin C/Cu. The previously reported experimental results are summarized, and the model predictions are compared to monotonic and cyclic tensile and shear test data. By considering appropriate levels of porosity

  9. Polymer Matrix Composite Material Oxygen Compatibility

    NASA Technical Reports Server (NTRS)

    Owens, Tom

    2001-01-01

    Carbon fiber/polymer matrix composite materials look promising as a material to construct liquid oxygen (LOX) tanks. Based on mechanical impact tests the risk will be greater than aluminum, however, the risk can probably be managed to an acceptable level. Proper tank design and operation can minimize risk. A risk assessment (hazard analysis) will be used to determine the overall acceptability for using polymer matrix composite materials.

  10. Ceramic Matrix Composites Performances Under High Gamma Radiation Doses

    NASA Astrophysics Data System (ADS)

    Cemmi, A.; Baccaro, S.; Fiore, S.; Gislon, P.; Serra, E.; Fassina, S.; Ferrari, E.; Ghisolfi, E.

    2014-06-01

    Ceramic matrix composites reinforced by continuous ceramic fibers (CMCs) represent a class of advanced materials developed for applications in automotive, aerospace, nuclear fusion reactors and in other specific systems for harsh environments. In the present work, the silicon carbide/silicon carbide (SiCf/SiC) composites, manufactured by Chemical Vapour Infiltration process at FN S.p.A. plant, have been evaluated in term of gamma radiation hardness at three different absorbed doses (up to around 3MGy). Samples behavior has been investigated before and after irradiation by means of mechanical tests (flexural strength) and by surface and structural analyses (X-ray diffraction, SEM, FTIR-ATR, EPR).

  11. Interfacial reactions in titanium-matrix composites

    SciTech Connect

    Yang, J.M.; Jeng, S.M. )

    1989-11-01

    A study of the interfacial reaction characteristics of SiC fiber-reinforced titanium aluminide and disordered titanium alloy composites has determined that the matrix alloy compositions affect the microstructure and the distribution of the reaction products, as well as the growth kinetics of the reaction zones. The interfacial reaction products in the ordered titanium aluminide composite are more complicated than those in the disordered titanium-alloy composite. The activation energy of the interfacial reaction in the ordered titanium aluminide composite is also higher than that in the disordered titanium alloy composite. Designing an optimum interface is necessary to enhance the reliability and service life at elevated temperatures. 16 refs.

  12. METCAN-PC - METAL MATRIX COMPOSITE ANALYZER

    NASA Technical Reports Server (NTRS)

    Murthy, P. L.

    1994-01-01

    High temperature metal matrix composites offer great potential for use in advanced aerospace structural applications. The realization of this potential however, requires concurrent developments in (1) a technology base for fabricating high temperature metal matrix composite structural components, (2) experimental techniques for measuring their thermal and mechanical characteristics, and (3) computational methods to predict their behavior. METCAN (METal matrix Composite ANalyzer) is a computer program developed to predict this behavior. METCAN can be used to computationally simulate the non-linear behavior of high temperature metal matrix composites (HT-MMC), thus allowing the potential payoff for the specific application to be assessed. It provides a comprehensive analysis of composite thermal and mechanical performance. METCAN treats material nonlinearity at the constituent (fiber, matrix, and interphase) level, where the behavior of each constituent is modeled accounting for time-temperature-stress dependence. The composite properties are synthesized from the constituent instantaneous properties by making use of composite micromechanics and macromechanics. Factors which affect the behavior of the composite properties include the fabrication process variables, the fiber and matrix properties, the bonding between the fiber and matrix and/or the properties of the interphase between the fiber and matrix. The METCAN simulation is performed as point-wise analysis and produces composite properties which are readily incorporated into a finite element code to perform a global structural analysis. After the global structural analysis is performed, METCAN decomposes the composite properties back into the localized response at the various levels of the simulation. At this point the constituent properties are updated and the next iteration in the analysis is initiated. This cyclic procedure is referred to as the integrated approach to metal matrix composite analysis. METCAN

  13. METCAN-PC - METAL MATRIX COMPOSITE ANALYZER

    NASA Technical Reports Server (NTRS)

    Murthy, P. L.

    1994-01-01

    High temperature metal matrix composites offer great potential for use in advanced aerospace structural applications. The realization of this potential however, requires concurrent developments in (1) a technology base for fabricating high temperature metal matrix composite structural components, (2) experimental techniques for measuring their thermal and mechanical characteristics, and (3) computational methods to predict their behavior. METCAN (METal matrix Composite ANalyzer) is a computer program developed to predict this behavior. METCAN can be used to computationally simulate the non-linear behavior of high temperature metal matrix composites (HT-MMC), thus allowing the potential payoff for the specific application to be assessed. It provides a comprehensive analysis of composite thermal and mechanical performance. METCAN treats material nonlinearity at the constituent (fiber, matrix, and interphase) level, where the behavior of each constituent is modeled accounting for time-temperature-stress dependence. The composite properties are synthesized from the constituent instantaneous properties by making use of composite micromechanics and macromechanics. Factors which affect the behavior of the composite properties include the fabrication process variables, the fiber and matrix properties, the bonding between the fiber and matrix and/or the properties of the interphase between the fiber and matrix. The METCAN simulation is performed as point-wise analysis and produces composite properties which are readily incorporated into a finite element code to perform a global structural analysis. After the global structural analysis is performed, METCAN decomposes the composite properties back into the localized response at the various levels of the simulation. At this point the constituent properties are updated and the next iteration in the analysis is initiated. This cyclic procedure is referred to as the integrated approach to metal matrix composite analysis. METCAN

  14. Diamond-Reinforced Matrix Composites

    DTIC Science & Technology

    1993-05-10

    stainless steel retorts and evacuated to a level 17 of -40 mTorr. Samples were HIPped to full density at 600"C at 18 30 Ksi for 30 minutes. These...composite bulk 12 materials and composite coatings) having high strength and 13 stiffness. These articles can be used, for example, in dental 14 materials...fabricated using standard powder metallurgy 8 techniques. The materials used to synthesize the DRCs were -230 9 mesh , 1100 aluminum powder and 30 jim

  15. Fracture toughness testing of polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Grady, Joseph E.

    1992-01-01

    The experimental techniques and associated data analysis methods used to measure the resistance to interlaminar fracture, or 'fracture toughness', of polymer matrix composite materials are described. A review in the use of energy techniques to characterize fracture behavior in elastic solids is given. An overview is presented of the types of approaches employed in the design of delamination-resistant composite materials.

  16. Tough high performance composite matrix

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor); Johnston, Norman J. (Inventor)

    1994-01-01

    This invention is a semi-interpentrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide. Provided is an improved high temperature matrix resin which is capable of performing in the 200 to 300 C range. This resin has significantly improved toughness and microcracking resistance, excellent processability, mechanical performance, and moisture and solvent resistances.

  17. 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.

  18. Research on graphite reinforced glass matrix composites

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.; Prewo, K. M.

    1977-01-01

    The results of research for the origination of graphite-fiber reinforced glass matrix composites are presented. The method selected to form the composites consisted of pulling the graphite fiber through a slurry containing powdered glass, winding up the graphite fiber and the glass it picks up on a drum, drying, cutting into segments, loading the tape segment into a graphite die, and hot pressing. During the course of the work, composites were made with a variety of graphite fibers in a glass matrix.

  19. Nanophosphor composite scintillators comprising a polymer matrix

    DOEpatents

    Muenchausen, Ross Edward; Mckigney, Edward Allen; Gilbertson, Robert David

    2010-11-16

    An improved nanophosphor composite comprises surface modified nanophosphor particles in a solid matrix. The nanophosphor particle surface is modified with an organic ligand, or by covalently bonding a polymeric or polymeric precursor material. The surface modified nanophosphor particle is essentially charge neutral, thereby preventing agglomeration of the nanophosphor particles during formation of the composite material. The improved nanophosphor composite may be used in any conventional scintillator application, including in a radiation detector.

  20. Research on graphite reinforced glass matrix composites

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Thompson, E. R.

    1981-01-01

    A broad group of fibers and matrices were combined to create a wide range of composite properties. Primary material fabrication procedures were developed which readily permit the fabrication of flat plate and shaped composites. Composite mechanical properties were measured under a wide range of test conditions. Tensile, flexure mechanical fatigue, thermal fatigue, fracture toughness, and fatigue crack growth resistance were evaluated. Selected fiber-matrix combinations were shown to maintain their strength at up to 1300 K when tested in an inert atmosphere. Composite high temperature mechanical properties were shown to be limited primarily by the oxidation resistance of the graphite fibers. Composite thermal dimensional stability was measured and found to be excellent.

  1. Matrix cracking in brittle-matrix composites with tailored interfaces

    SciTech Connect

    Danchaivijit, S.; Chao, L.Y.; Shetty, D.K.

    1995-10-01

    Matrix cracking from controlled through cracks with bridging filaments was studied in a model unidirectional composite of SiC filaments in an epoxy-bonded alumina matrix. An unbonded, frictional interface was produced by moderating the curing shrinkage of the epoxy with the alumina filler and coating the filaments with a releasing agent. Uniaxial tension test specimens (2.5 x 25 x 125 mm) with filament-bridged through cracks were fabricated by a novel two-step casting technique involving casting, precracking and joining of cracked and uncracked sections. Distinct matrix-cracking stresses, corresponding to the extension of the filament-bridged cracks, were measured in uniaxial tension tests using a high-sensitivity extensometer. The crack-length dependence of the matrix-cracking stress was found to be in good agreement with the prediction of a fracture-mechanics analysis that employed a new crack-closure force-crack-opening displacement relation in the calculation of the stress intensity for fiber-bridged cracks. The prediction was based on independent experimental measurements of the matrix fracture toughness (K{sub cm}), the interfacial sliding friction stress ({tau}) and the residual stress in the matrix ({sigma}{sub m}{sup I}). The matrix-cracking stress for crack lengths (2a) greater than 3 mm was independent of the crack length and agreed with the prediction of the steady-state theory of Budiansky, Hutchinson and Evans. Tests on specimens without the deliberately introduced cracks indicated a matrix-cracking stress significantly higher than the steady-state stress.

  2. Optimum interface properties for metal matrix composites

    NASA Technical Reports Server (NTRS)

    Ghosn, Louis J.; Lerch, Bradley A.

    1989-01-01

    Due to the thermal expansion coefficient mismatch (CTE) between the fiber and the matrix, high residual sresses exist in metal matrix composite systems upon cool down from processing temperature to room temperature. An interface material can be placed between the fiber and the matrix to reduce the high tensile residual stresses in the matrix. A computer program was written to minimize the residual stress in the matrix subject to the interface material properties. The decision variables are the interface modulus, thickness and thermal expansion coefficient. The properties of the interface material are optimized such that the average distortion energy in the matrix and the interface is minimized. As a result, the only active variable is the thermal expansion coefficient. The optimum modulus of the interface is always the minimum allowable value and the interface thickness is always the maximum allowable value, independent of the fiber/matrix system. The optimum interface thermal expansion coefficient is always between the values of the fiber and the matrix. Using this analysis, a survey of materials was conducted for use as fiber coatings in some specific composite systems.

  3. Fiber-matrix interfaces in ceramic composites

    SciTech Connect

    Besmann, T.M.; Stinton, D.P.; Kupp, E.R.; Shanmugham, S.; Liaw, P.K.

    1996-12-31

    The mechanical properties of ceramic matrix composites (CMCs) are governed by the relationships between the matrix, the interface material, and the fibers. In non-oxide matrix systems compliant pyrolytic carbon and BN have been demonstrated to be effective interface materials, allowing for absorption of mismatch stresses between fiber and matrix and offering a poorly bonded interface for crack deflection. The resulting materials have demonstrated remarkable strain/damage tolerance together with high strength. Carbon or BN, however, suffer from oxidative loss in many service environments, and thus there is a major search for oxidation resistant alternatives. This paper reviews the issues related to developing a stable and effective interface material for non-oxide matrix CMCs.

  4. Polymer Matrix Composites for Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    2003-01-01

    The Access-to-Space study identified the requirement for lightweight structures to achieve orbit with a single-stage vehicle. Thus a task was undertaken to examine the use of polymer matrix composites for propulsion components. It was determined that the effort of this task would be to extend previous efforts with polymer matrix composite feedlines and demonstrate the feasibility of manufacturing large diameter feedlines with a complex shape and integral flanges, (i.e. all one piece with a 90 deg bend), and assess their performance under a cryogenic atmosphere.

  5. Thermophysical and Electrical Properties of Metal Matrix Composites

    DTIC Science & Technology

    1979-12-01

    de if necessary and identify by block number) Aluminum matrix composiles, aluminum alloy matrix composites, copper matrix composites, electrical...the various com- posites of aluminum and aluminum alloy mar-tices, copper matrix, lead matrix, magnesium matrix, nickel and nickel alloy matrices...titanium and titanium alloy matrices, tungsten matrix, and zinc matrix. Most of the data are for aluminum DD j JAN 73 1473 EDITION OF I NOV6 S IS

  6. Tensile properties of ceramic matrix fiber composites

    SciTech Connect

    Shin, D.W.; Auh, K.H.; Tanaka, Hidehiko

    1995-11-01

    The mechanical properties of various 2D ceramic matrix fiber composites were characterized by tension testing, using the gripping and alignment techniques developed in this work. The woven fabric composites used for the test had the basic combinations of Al{sub 2}O{sub 3} fabric/Al{sub 2}O{sub 3}, SiC fabric/SiC, and SiC monofilament uniweave fabric/SiC. Tension testing was performed with strain gauge and acoustic emission instrumentation to identify the first-matrix cracking stress and assure a valid alignment. The peak tensile stresses of these laminate composites were about one-third of the flexural strengths. The SiC monofilament uniweave fabric (14 vol%)/SiC composites showed a relatively high peak stress of 370 MPa in tension testing.

  7. Plastic matrix composites with continuous fiber reinforcement

    SciTech Connect

    1991-09-19

    Most plastic resins are not suitable for structural applications. Although many resins are extremely tough, most lack strength, stiffness, and deform under load with time. By mixing strong, stiff, fibrous materials into the plastic matrix, a variety of structural composite materials can be formed. The properties of these composites can be tailored by fiber selection, orientation, and other factors to suit specific applications. The advantages and disadvantages of fiberglass, carbon-graphite, aramid (Kevlar 49), and boron fibers are summarized.

  8. Processable polyimide adhesive and matrix composite resin

    NASA Technical Reports Server (NTRS)

    Pratt, J. Richard (Inventor); St.clair, Terry L. (Inventor); Progar, Donald J. (Inventor)

    1990-01-01

    A high temperature polyimide composition prepared by reacting 4,4'-isophthaloyldiphthalic anhydride with metaphenylenediamine is employed to prepare matrix resins, adhesives, films, coatings, moldings, and laminates, especially those showing enhanced flow with retention of mechanical and adhesive properties. It can be used in the aerospace industry, for example, in joining metals to metals or metals to composite structures. One area of application is in the manufacture of lighter and stronger aircraft and spacecraft structures.

  9. Magnetic Properties of Nanoparticle Matrix Composites

    DTIC Science & Technology

    2015-06-02

    decahedral and icosahedral. In each case spin isomers have been studied. The Fe3Pt-FePt nanoparticle-matrix composites have been studied by considering a...been optimized for each composition of Fe-Pt and their spin isomers have been studied to find the magnetic moments of the lowest energy structures... isomers may lie close in energy. We have used the results of the calculations on small clusters as a guide to understand the atomic structures and

  10. Research on graphite reinforced glass matrix composites

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Thompson, E. R.

    1980-01-01

    High levels of mechanical performance in tension, flexure, fatigue, and creep loading situations of graphite fiber reinforced glass matrix composites are discussed. At test temperatures of up to 813 K it was found that the major limiting factor was the oxidative instability of the reinforcing graphite fibers. Particular points to note include the following: (1) a wide variety of graphite fibers were found to be comparable with the glass matrix composite fabrication process; (2) choice of fiber, to a large extent, controlled resultant composite performance; (3) composite fatigue performance was found to be excellent at both 300 K and 703 K; (4) composite creep and stress rupture at temperatures of up to 813 K was limited by the oxidative stability of the fiber; (5) exceptionally low values of composite thermal expansion coefficient were attributable to the dimensional stability of both matrix and fiber; and (6) component fabricability was demonstrated through the hot pressing of hot sections and brazing using glass and metal joining phases.

  11. Development of Matrix Microstructures in UHTC Composites

    NASA Technical Reports Server (NTRS)

    Johnson, Sylvia; Stackpoole, Margaret; Gusman, Michael

    2012-01-01

    One of the major issues hindering the use of ultra high temperature ceramics for aerospace applications is low fracture toughness. There is considerable interest in developing fiber-reinforced composites to improve fracture toughness. Considerable knowledge has been gained in controlling and improving the microstructure of monolithic UHTCs, and this paper addresses the question of transferring that knowledge to composites. Some model composites have been made and the microstructures of the matrix developed has been explored and compared to the microstructure of monolithic materials in the hafnium diboride/silicon carbide family. Both 2D and 3D weaves have been impregnated and processed.

  12. Metal matrix composites for aircraft propulsion systems

    NASA Technical Reports Server (NTRS)

    Signorelli, R. A.

    1975-01-01

    Studies of advanced aircraft propulsion systems have indicated that performance gains and operating costs are possible through the application of metal matrix composites. Compressor fan blades and turbine blades have been identified as components with high payoff potential as a result of these studies. This paper will present the current status of development of five candidate materials for such applications. Boron fiber/aluminum, boron fiber/titanium, and silicon carbide fiber/titanium composites are considered for lightweight compressor fan blades. Directionally solidified eutectic superalloy and tungsten wire/superalloy composites are considered for application to turbine blades for use temperatures to 1100 C (2000 F).

  13. Thermoforming of thermoplastic matrix composites. Part I

    SciTech Connect

    Harper, R.C.

    1992-03-01

    Long-fiber-reinforced polymer matrix composites find widespread use in a variety of commercial applications requiring properties that cannot be provided by unreinforced plastics or other common materials of construction. However, thermosetting matrix resins have long been plagued by production processes that are slow and difficult to automate. This has limited the use of long-fiber-reinforced composites to relatively low productivity applications in which higher production costs can be justified. Unreinforced thermoplastics, by their very nature, can easily be made into sheet form and processed into a variety of formed shapes by various pressure assisted thermoforming means. It is possible to incorporate various types of fiber reinforcement to suit the end use of the thermoformed shape. Recently developed thermoplastic resins can also sometimes correct physical property deficiencies in a thermoset matrix composite. Many forms of thermoplastic composite material now exist that meet all the requirements of present day automotive and aerospace parts. Some of these are presently in production, while others are still in the development stage. This opens the possibility that long-fiber-reinforced thermoplastics might break the barrier that has long limited the applications for fiber-reinforced composites. 37 refs., 8 figs., 5 tabs.

  14. Modifications in stromal extracellular matrix of aged corneas can be induced by ultraviolet A irradiation

    PubMed Central

    Gendron, Sébastien P; Rochette, Patrick J

    2015-01-01

    With age, structural and functional changes can be observed in human cornea. Some studies have shown a loss of corneal transparency and an increase in turbidity associated with aging. These changes are caused by modifications in the composition and arrangement of extracellular matrix in the corneal stroma. In human skin, it is well documented that exposure to solar radiation, and mainly to the UVA wavelengths, leads to phenotypes of photoaging characterized by alteration in extracellular matrix of the dermis. Although the cornea is also exposed to solar radiation, the extracellular matrix modifications observed in aging corneas have been mainly attributed to chronological aging and not to solar exposure. To ascertain the real implication of UVA exposure in extracellular matrix changes observed with age in human cornea, we have developed a model of photoaging by chronically exposing corneal stroma keratocytes with a precise UVA irradiation protocol. Using this model, we have analyzed UVA-induced transcriptomic and proteomic changes in corneal stroma. Our results show that cumulative UVA exposure causes changes in extracellular matrix that are found in corneal stromas of aged individuals, suggesting that solar exposure catalyzes corneal aging. Indeed, we observe a downregulation of collagen and proteoglycan gene expression and a reduction in proteoglycan production and secretion in response to cumulative UVA exposure. This study provides the first evidence that chronic ocular exposure to sunlight affects extracellular matrix composition and thus plays a role in corneal changes observed with age. PMID:25728164

  15. CMH-17 Volume 5 Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Andrulonis, Rachael; Kiser, J. Douglas; David, Kaia E.; Davies, Curtis; Ashforth, Cindy

    2017-01-01

    A wide range of issues must be addressed during the process of certifying CMC (ceramic matrix composite) components for use in commercial aircraft. The Composite Materials Handbook-17, Volume 5, Revision A on ceramic matrix composites has just been revised to help support FAA certification of CMCs for elevated temperature applications. The handbook supports the development and use of CMCs through publishing and maintaining proven, reliable engineering information and standards that have been thoroughly reviewed. Volume 5 contains detailed sections describing CMC materials processing, design analysis guidelines, testing procedures, and data analysis and acceptance. A review of the content of this latest revision will be presented along with a description of how CMH-17, Volume 5 could be used by the FAA (Federal Aviation Administration) and others in the future.

  16. Inelastic deformation of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Lissenden, C. J.; Herakovich, C. T.; Pindera, M-J.

    1993-01-01

    A theoretical model capable of predicting the thermomechanical response of continuously reinforced metal matrix composite laminates subjected to multiaxial loading was developed. A micromechanical model is used in conjunction with nonlinear lamination theory to determine inelastic laminae response. Matrix viscoplasticity, residual stresses, and damage to the fiber/matrix interfacial zone are explicitly included in the model. The representative cell of the micromechanical model is considered to be in a state of generalized plane strain, enabling a quasi two-dimensional analysis to be performed. Constant strain finite elements are formulated with elastic-viscoplastic constitutive equations. Interfacial debonding is incorporated into the model through interface elements based on the interfacial debonding theory originally presented by Needleman, and modified by Tvergaard. Nonlinear interfacial constitutive equations relate interfacial tractions to displacement discontinuities at the interface. Theoretical predictions are compared with the results of an experimental program conducted on silicon carbide/titanium (SiC/Ti) unidirectional, (O4), and angle-ply, (+34)(sub s), tubular specimens. Multiaxial loading included increments of axial tension, compression, torque, and internal pressure. Loadings were chosen in an effort to distinguish inelastic deformation due to damage from matrix plasticity and separate time-dependent effects from time-independent effects. Results show that fiber/matrix debonding is nonuniform throughout the composite and is a major factor in the effective response. Also, significant creep behavior occurs at relatively low applied stress levels at room temperature.

  17. Thermal stress effects in intermetallic matrix composites

    NASA Technical Reports Server (NTRS)

    Wright, P. K.; Sensmeier, M. D.; Kupperman, D. S.; Wadley, H. N. G.

    1993-01-01

    Intermetallic matrix composites develop residual stresses from the large thermal expansion mismatch (delta-alpha) between the fibers and matrix. This work was undertaken to: establish improved techniques to measure these thermal stresses in IMC's; determine residual stresses in a variety of IMC systems by experiments and modeling; and, determine the effect of residual stresses on selected mechanical properties of an IMC. X ray diffraction (XRD), neutron diffraction (ND), synchrotron XRD (SXRD), and ultrasonics (US) techniques for measuring thermal stresses in IMC were examined and ND was selected as the most promising technique. ND was demonstrated on a variety of IMC systems encompassing Ti- and Ni-base matrices, SiC, W, and Al2O3 fibers, and different fiber fractions (Vf). Experimental results on these systems agreed with predictions of a concentric cylinder model. In SiC/Ti-base systems, little yielding was found and stresses were controlled primarily by delta-alpha and Vf. In Ni-base matrix systems, yield strength of the matrix and Vf controlled stress levels. The longitudinal residual stresses in SCS-6/Ti-24Al-llNb composite were modified by thermomechanical processing. Increasing residual stress decreased ultimate tensile strength in agreement with model predictions. Fiber pushout strength showed an unexpected inverse correlation with residual stress. In-plane shear yield strength showed no dependence on residual stress. Higher levels of residual tension led to higher fatigue crack growth rates, as suggested by matrix mean stress effects.

  18. Thermal shock resistance of ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Carper, D. M.; Nied, H. F.

    1993-01-01

    The experimental and analytical investigation of the thermal shock phenomena in ceramic matrix composites is detailed. The composite systems examined were oxide-based, consisting of an aluminosilicate matrix with either polycrystalline aluminosilicate or single crystal alumina fiber reinforcement. The program was divided into three technical tasks; baseline mechanical properties, thermal shock modeling, and thermal shock testing. The analytical investigation focused on the development of simple expressions for transient thermal stresses induced during thermal shock. The effect of various material parameters, including thermal conductivity, elastic modulus, and thermal expansion, were examined analytically for their effect on thermal shock performance. Using a simple maximum stress criteria for each constituent, it was observed that fiber fracture would occur only at the most extreme thermal shock conditions and that matrix fracture, splitting parallel to the reinforcing fiber, was to be expected for most practical cases. Thermal shock resistance for the two material systems was determined experimentally by subjecting plates to sudden changes in temperature on one surface while maintaining the opposite surface at a constant temperature. This temperature change was varied in severity (magnitude) and in number of shocks applied to a given sample. The results showed that for the most severe conditions examined that only surface matrix fracture was present with no observable fiber fracture. The impact of this damage on material performance was limited to the matrix dominated properties only. Specifically, compression strength was observed to decrease by as much as 50 percent from the measured baseline.

  19. Unified Viscoplastic Behavior of Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Arnold, S. M.; Robinson, D. N.; Bartolotta, P. A.

    1992-01-01

    The need for unified constitutive models was recognized more than a decade ago in the results of phenomenological tests on monolithic metals that exhibited strong creep-plasticity interaction. Recently, metallic alloys have been combined to form high-temperature ductile/ductile composite materials, raising the natural question of whether these metallic composites exhibit the same phenomenological features as their monolithic constituents. This question is addressed in the context of a limited, yet definite (to illustrate creep/plasticity interaction) set of experimental data on the model metal matrix composite (MMC) system W/Kanthal. Furthermore, it is demonstrated that a unified viscoplastic representation, extended for unidirectional composites and correlated to W/Kanthal, can accurately predict the observed longitudinal composite creep/plasticity interaction response and strain rate dependency. Finally, the predicted influence of fiber orientation on the creep response of W/Kanthal is illustrated.

  20. Microwave Irradiation Effect on the Dispersion and Thermal Stability of RGO Nanosheets within a Polystyrene Matrix.

    PubMed

    Alsharaeh, Edreese H; Othman, Ali A; Aldosari, Mohammad A

    2014-07-18

    Polystyrene-reduced graphene oxide (PSTY/RGO) composites were prepared via the in situ bulk polymerization method using two different preparation techniques. The general approach is to use microwave irradiation (MWI) to enhance the exfoliation and the dispersion of RGO nanosheets within the PSTY matrix. In the first approach, a mixture of GO and styrene monomers (STY) were polymerized using a bulk polymerization method facilitated by microwave irradiation (MWI) to obtain R-(GO-PSTY) composites. In the second approach, a mixture of RGO and STY monomers were polymerized using a bulk polymerization method to obtain RGO-(PSTY) composites. The two composites were characterized by FTIR, ¹H-NMR, XRD, SEM, HRTEM, TGA and DSC. The results indicate that the composite obtained using the first approach, which involved MWI, had a better morphology and dispersion with enhanced thermal stability, compared with the composites prepared without MWI. Moreover, DSC results showed that the Tg value of the composites after loading the RGO significantly increased by 24.6 °C compared to the neat polystyrene.

  1. Hybrid Ceramic Matrix Fibrous Composites: an Overview

    NASA Astrophysics Data System (ADS)

    Naslain, R.

    2011-10-01

    Ceramic-Matrix Composites (CMCs) consist of a ceramic fiber architecture in a ceramic matrix, bonded together through a thin interphase. The present contribution is limited to non-oxide CMCs. Their constituents being oxidation-prone, they are protected by external coatings. We state here that CMCs display a hybrid feature, when at least one of their components is not homogeneous from a chemical or microstructural standpoint. Hybrid fiber architectures are used to tailor the mechanical or thermal CMC-properties whereas hybrid interphases, matrices and coatings to improve CMC resistance to aggressive environments.

  2. Ceramic Matrix Composite (CMC) Materials Development

    NASA Technical Reports Server (NTRS)

    DiCarlo, James

    2001-01-01

    Under the former NASA EPM Program, much initial progress was made in identifying constituent materials and processes for SiC/SiC ceramic composite hot-section components. This presentation discusses the performance benefits of these approaches and elaborates on further constituent and property improvements made under NASA UEET. These include specific treatments at NASA that significantly improve the creep and environmental resistance of the Sylramic(TM) Sic fiber as well as the thermal conductivity and creep resistance of the CVI Sic matrix. Also discussed are recent findings concerning the beneficial effects of certain 2D-fabric architectures and carbon between the BN interphase coating and Sic matrix.

  3. Ceramic Matrix Composite (CMC) Materials Characterization

    NASA Technical Reports Server (NTRS)

    Calomino, Anthony

    2001-01-01

    Under the former NASA EPM Program, much initial progress was made in identifying constituent materials and processes for SiC/SiC ceramic composite hot-section components. This presentation discusses the performance benefits of these approaches and elaborates on further constituent and property improvements made under NASA UEET. These include specific treatments at NASA that significantly improve the creep and environmental resistance of the Sylramic(TM) SiC fiber as well as the thermal conductivity and creep resistance of the CVI Sic matrix. Also discussed are recent findings concerning the beneficial effects of certain 2D-fabric architectures and carbon between the BN interphase coating and Sic matrix.

  4. Ceramic Matrix Composite (CMC) Materials Development

    NASA Technical Reports Server (NTRS)

    DiCarlo, James

    2001-01-01

    Under the former NASA EPM Program, much initial progress was made in identifying constituent materials and processes for SiC/SiC ceramic composite hot-section components. This presentation discusses the performance benefits of these approaches and elaborates on further constituent and property improvements made under NASA UEET. These include specific treatments at NASA that significantly improve the creep and environmental resistance of the Sylramic(TM) Sic fiber as well as the thermal conductivity and creep resistance of the CVI Sic matrix. Also discussed are recent findings concerning the beneficial effects of certain 2D-fabric architectures and carbon between the BN interphase coating and Sic matrix.

  5. Ceramic Matrix Composite (CMC) Materials Characterization

    NASA Technical Reports Server (NTRS)

    Calomino, Anthony

    2001-01-01

    Under the former NASA EPM Program, much initial progress was made in identifying constituent materials and processes for SiC/SiC ceramic composite hot-section components. This presentation discusses the performance benefits of these approaches and elaborates on further constituent and property improvements made under NASA UEET. These include specific treatments at NASA that significantly improve the creep and environmental resistance of the Sylramic(TM) SiC fiber as well as the thermal conductivity and creep resistance of the CVI Sic matrix. Also discussed are recent findings concerning the beneficial effects of certain 2D-fabric architectures and carbon between the BN interphase coating and Sic matrix.

  6. Plasma Joining of Metal Matrix Composites.

    DTIC Science & Technology

    1988-02-25

    effect, which may be preceded by Al4C3 formation, is apparently suppressed in matrix alloys containing reactive metal additions. All observations are...continuously by diffusion into the bulk of the liquid Al matrix, and the Al4C3 (s) formed is not a barrier for Si, Al and C transport. Assume a composite...0.104 versus 0.226), since Al4C3 is less stable at higher temperatures. It is also interesting to see that the F values for the same t values are

  7. A Review of Irradiation Effects on Organic-Matrix Insulation

    SciTech Connect

    Simon, N.J.

    1993-06-01

    This review assesses the data base on epoxy and polyimide matrix insulation to determine whether organic electric insulation systems can be used in the toroidal field (TF) magnets of next generation fusion devices such as ITER* and TPX*. Owing to the difficulties of testing insulation under fusion reactor conditions, there is a considerable mismatch between the ITER requirements and the data that are currently available. For example, nearly all of the high-dose (5 x 10{sup 7} to 10{sup 8} Gy) data obtained on epoxy and polyimide matrix insulation employed gamma irradiation, electron irradiation, or reactor irradiation with a fast neutron fluence far below 10{sup 23}/m{sup 2}, the fluence expected for the insulation at the TF magnets, as set forth in ITER conceptual design documents. Also, the neutron spectrum did not contain a very high energy (E {ge} 5 MeV) component. Such data underestimate the actual damage that would be obtained with the neutron fluence and spectrum expected at a TF magnet. Experiments on a polyimide (Kapton) indicate that gamma or electron doses or mixed gamma and neutron reactor doses would have to be downgraded by a factor of up to ten to simulate fusion neutron doses. Even when neutrons did constitute a significant portion of the total dose, B-containing E-glass reinforcement was often used; therefore, excess damage from the {sup 10}B + n {yields} {sup 7}Li + {alpha} reaction occurred near the glass-epoxy interface. This problem can easily be avoided by substituting B-free glass (R, S, or T types).

  8. Ceramic matrix composite behavior -- Computational simulation

    SciTech Connect

    Chamis, C.C.; Murthy, P.L.N.; Mital, S.K.

    1996-10-01

    Development of analytical modeling and computational capabilities for the prediction of high temperature ceramic matrix composite behavior has been an ongoing research activity at NASA-Lewis Research Center. These research activities have resulted in the development of micromechanics based methodologies to evaluate different aspects of ceramic matrix composite behavior. The basis of the approach is micromechanics together with a unique fiber substructuring concept. In this new concept the conventional unit cell (the smallest representative volume element of the composite) of micromechanics approach has been modified by substructuring the unit cell into several slices and developing the micromechanics based equations at the slice level. Main advantage of this technique is that it can provide a much greater detail in the response of composite behavior as compared to a conventional micromechanics based analysis and still maintains a very high computational efficiency. This methodology has recently been extended to model plain weave ceramic composites. The objective of the present paper is to describe the important features of the modeling and simulation and illustrate with select examples of laminated as well as woven composites.

  9. Properties of five toughened matrix composite materials

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Dow, Marvin B.

    1992-01-01

    The use of toughened matrix composite materials offers an attractive solution to the problem of poor damage tolerance associated with advanced composite materials. In this study, the unidirectional laminate strengths and moduli, notched (open-hole) and unnotched tension and compression properties of quasi-isotropic laminates, and compression-after-impact strengths of five carbon fiber/toughened matrix composites, IM7/E7T1-2, IM7/X1845, G40-800X/5255-3, IM7/5255-3, and IM7/5260 have been evaluated. The compression-after-impact (CAI) strengths were determined primarily by impacting quasi-isotropic laminates with the NASA Langley air gun. A few CAI tests were also made with a drop-weight impactor. For a given impact energy, compression after impact strengths were determined to be dependent on impactor velocity. Properties and strengths for the five materials tested are compared with NASA data on other toughened matrix materials (IM7/8551-7, IM6/1808I, IM7/F655, and T800/F3900). This investigation found that all five materials were stronger and more impact damage tolerant than more brittle carbon/epoxy composite materials currently used in aircraft structures.

  10. High temperature insulation for ceramic matrix composites

    DOEpatents

    Merrill, Gary B.; Morrison, Jay Alan

    2004-01-13

    A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substrates are also provided.

  11. High temperature insulation for ceramic matrix composites

    DOEpatents

    Merrill, Gary B.; Morrison, Jay Alan

    2001-01-01

    A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composition comprises a plurality of hollow oxide-based spheres of various dimensions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substrates are also provided.

  12. High temperature insulation for ceramic matrix composites

    DOEpatents

    Merrill, Gary B.; Morrison, Jay Alan

    2000-01-01

    A ceramic composition is provided to insulate ceramic matrix composites under high temperature, high heat flux environments. The composite comprises a plurality of hollow oxide-based spheres of varios dimentions, a phosphate binder, and at least one oxide filler powder, whereby the phosphate binder partially fills gaps between the spheres and the filler powders. The spheres are situated in the phosphate binder and the filler powders such that each sphere is in contact with at least one other sphere. The spheres may be any combination of Mullite spheres, Alumina spheres, or stabilized Zirconia spheres. The filler powder may be any combination of Alumina, Mullite, Ceria, or Hafnia. Preferably, the phosphate binder is Aluminum Ortho-Phosphate. A method of manufacturing the ceramic insulating composition and its application to CMC substates are also provided.

  13. Advanced ceramic matrix composites for TPS

    NASA Technical Reports Server (NTRS)

    Rasky, Daniel J.

    1992-01-01

    Recent advances in ceramic matrix composite (CMC) technology provide considerable opportunity for application to future aircraft thermal protection system (TPS), providing materials with higher temperature capability, lower weight, and higher strength and stiffness than traditional materials. The Thermal Protection Material Branch at NASA Ames Research Center has been making significant progress in the development, characterization, and entry simulation (arc-jet) testing of new CMC's. This protection gives a general overview of the Ames Thermal Protection Materials Branch research activities, followed by more detailed descriptions of recent advances in very-high temperature Zr and Hf based ceramics, high temperature, high strength SiC matrix composites, and some activities in polymer precursors and ceramic coating processing. The presentation closes with a brief comparison of maximum heat flux capabilities of advanced TPS materials.

  14. 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.

  15. Ceramic Matrix Composites for Rotorcraft Engines

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.

    2011-01-01

    Ceramic matrix composite (CMC) components are being developed for turbine engine applications. Compared to metallic components, the CMC components offer benefits of higher temperature capability and less cooling requirements which correlates to improved efficiency and reduced emissions. This presentation discusses a technology develop effort for overcoming challenges in fabricating a CMC vane for the high pressure turbine. The areas of technology development include small component fabrication, ceramic joining and integration, material and component testing and characterization, and design and analysis of concept components.

  16. Technology Base Enhancement Program. Metal Matrix Composites

    DTIC Science & Technology

    1993-08-30

    DWA, Advanced Composites Materials Corporation (ACMC), Textron, 3M, Alcoa, Lanxide, and Ceramics Kingston Ceramiques (CKC). Table EX-l presents mnore...100% T&E ff43-4ZO~O Table EX-1. Domestic MMC Supply Capabilities -iv- I The MMC marketplace can be broken down into two distinct areas: continuously...between continuous and discontinuous MMCs are found in Table EX-2. - Property improvements Over Matrix by ɚX = Usualy Not or Neo Net Shape = improved

  17. Thermal expansion measurements of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Tompkins, Stephen S.; Dries, Gregory A.

    1988-01-01

    The laser-interferometric-dilatometer system currently operational at NASA-Langley is described. The system, designed to characterize metal matrix composites, features high precision, automated data acquisition, and the ability to test a wide variety of specimen geometries over temperature ranges within 80-422 K. The paper presents typical thermal-expansion measurement data for a Gr/Al rod; Gr/Al and Gr/Mg unidirectional laminates; and a Gr/Mg (+ or -8)s laminate.

  18. Ceramic Matrix Composite Vane Subelement Burst Testing

    NASA Technical Reports Server (NTRS)

    Brewer, David N.; Verrilli, Michael; Calomino, Anthony

    2006-01-01

    Burst tests were performed on Ceramic Matrix Composite (CMC) vane specimens, manufactured by two vendors, under the Ultra Efficient Engine Technology (UEET) project. Burst specimens were machined from the ends of 76mm long vane sub-elements blanks and from High Pressure Burner Rig (HPBR) tested specimens. The results of burst tests will be used to compare virgin specimens with specimens that have had an Environmental Barrier Coating (EBC) applied, both HPBR tested and untested, as well as a comparison between vendors.

  19. Method of producing a hybrid matrix fiber composite

    DOEpatents

    Deteresa, Steven J.; Lyon, Richard E.; Groves, Scott E.

    2006-03-28

    Hybrid matrix fiber composites having enhanced compressive performance as well as enhanced stiffness, toughness and durability suitable for compression-critical applications. The methods for producing the fiber composites using matrix hybridization. The hybrid matrix fiber composites comprised of two chemically or physically bonded matrix materials, whereas the first matrix materials are used to impregnate multi-filament fibers formed into ribbons and the second matrix material is placed around and between the fiber ribbons that are impregnated with the first matrix material and both matrix materials are cured and solidified.

  20. Program For Analysis Of Metal-Matrix Composites

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Mital, S. K.

    1994-01-01

    METCAN (METal matrix Composite ANalyzer) is computer program used to simulate computationally nonlinear behavior of high-temperature metal-matrix composite structural components in specific applications, providing comprehensive analyses of thermal and mechanical performances. Written in FORTRAN 77.

  1. Probabilistic Modeling of Ceramic Matrix Composite Strength

    NASA Technical Reports Server (NTRS)

    Shan, Ashwin R.; Murthy, Pappu L. N.; Mital, Subodh K.; Bhatt, Ramakrishna T.

    1998-01-01

    Uncertainties associated with the primitive random variables such as manufacturing process (processing temperature, fiber volume ratio, void volume ratio), constituent properties (fiber, matrix and interface), and geometric parameters (ply thickness, interphase thickness) have been simulated to quantify the scatter in the first matrix cracking strength (FMCS) and the ultimate tensile strength of SCS-6/RBSN (SiC fiber (SCS-6) reinforced reaction-bonded silicon nitride composite) ceramic matrix composite laminate at room temperature. Cumulative probability distribution function for the FMCS and ultimate tensile strength at room temperature (RT) of (0)(sub 8), (0(sub 2)/90(sub 2), and (+/-45(sub 2))(sub S) laminates have been simulated and the sensitivity of primitive variables to the respective strengths have been quantified. Computationally predicted scatter of the strengths for a uniaxial laminate have been compared with those from limited experimental data. Also the experimental procedure used in the tests has been described briefly. Results show a very good agreement between the computational simulation and the experimental data. Dominating failure modes in (0)(sub 8), (0/90)(sub s) and (+/-45)(sub S) laminates have been identified. Results indicate that the first matrix cracking strength for the (0)(sub S), and (0/90)(sub S) laminates is sensitive to the thermal properties, modulus and strengths of both the fiber and matrix whereas the ultimate tensile strength is sensitive to the fiber strength and the fiber volume ratio. In the case of a (+/-45)(sub S), laminate, both the FMCS and the ultimate tensile strengths have a small scatter range and are sensitive to the fiber tensile strength as well as the fiber volume ratio.

  2. Creep of plain weave polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Gupta, Abhishek

    Polymer matrix composites are increasingly used in various industrial sectors to reduce structural weight and improve performance. Woven (also known as textile) composites are one class of polymer matrix composites with increasing market share mostly due to their lightweight, their flexibility to form into desired shape, their mechanical properties and toughness. Due to the viscoelasticity of the polymer matrix, time-dependent degradation in modulus (creep) and strength (creep rupture) are two of the major mechanical properties required by engineers to design a structure reliably when using these materials. Unfortunately, creep and creep rupture of woven composites have received little attention by the research community and thus, there is a dire need to generate additional knowledge and prediction models, given the increasing market share of woven composites in load bearing structural applications. Currently, available creep models are limited in scope and have not been validated for any loading orientation and time period beyond the experimental time window. In this thesis, an analytical creep model, namely the Modified Equivalent Laminate Model (MELM), was developed to predict tensile creep of plain weave composites for any orientation of the load with respect to the orientation of the fill and warp fibers, using creep of unidirectional composites. The ability of the model to predict creep for any orientation of the load is a "first" in this area. The model was validated using an extensive experimental involving the tensile creep of plain weave composites under varying loading orientation and service conditions. Plain weave epoxy (F263)/ carbon fiber (T300) composite, currently used in aerospace applications, was procured as fabrics from Hexcel Corporation. Creep tests were conducted under two loading conditions: on-axis loading (0°) and off-axis loading (45°). Constant load creep, in the temperature range of 80-240°C and stress range of 1-70% UTS of the

  3. Ceramic matrix composites by microwave assisted CVI

    SciTech Connect

    Currier, R.P.; Devlin, D.J.

    1993-05-01

    Chemical vapor infiltration (CVI) processes for producing continuously reinforced ceramic composites are reviewed. The potential advantages of microwave assisted CVI are noted. Recent numerical studies of microwave assisted CVI are then reviewed. These studies predict inverted thermal gradients in fibrous ceramic preforms subjected to microwave radiation and suggest processing strategies for achieving uniformly dense composites. Comparisons are made to experimental results obtained using silicon based composite systems. The importance of microwave-material interactions is stressed. In particular, emphasis is placed on the role played by the relative ability of fiber and matrix to dissipate microwave energy. Results suggest that microwave induced inverted gradients can in fact be exploited using the CVI technique to promote inside-out densification.

  4. Ceramic matrix composites by microwave assisted CVI

    SciTech Connect

    Currier, R.P.; Devlin, D.J.

    1993-01-01

    Chemical vapor infiltration (CVI) processes for producing continuously reinforced ceramic composites are reviewed. The potential advantages of microwave assisted CVI are noted. Recent numerical studies of microwave assisted CVI are then reviewed. These studies predict inverted thermal gradients in fibrous ceramic preforms subjected to microwave radiation and suggest processing strategies for achieving uniformly dense composites. Comparisons are made to experimental results obtained using silicon based composite systems. The importance of microwave-material interactions is stressed. In particular, emphasis is placed on the role played by the relative ability of fiber and matrix to dissipate microwave energy. Results suggest that microwave induced inverted gradients can in fact be exploited using the CVI technique to promote inside-out densification.

  5. Polymer Matrix Composite Lines and Ducts

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.

    2001-01-01

    Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, a task was undertaken to assess the feasibility of making cryogenic feedlines with integral flanges from polymer matrix composite materials. An additional level of complexity was added by having the feedlines be elbow shaped. Four materials, each with a unique manufacturing method, were chosen for this program. Feedlines were to be made by hand layup (HLU) with standard autoclave cure, HLU with electron beam cure, solvent-assisted resin transfer molding (SARTM), and thermoplastic tape laying (TTL). A test matrix of fill and drain cycles with both liquid nitrogen and liquid helium, along with a heat up to 250 F, was planned for each of the feedlines. A pressurization to failure was performed on any feedlines that passed the cryogenic cycling testing. A damage tolerance subtask was also undertaken in this study. The effects of foreign object impact to the materials used was assessed by cross-sectional examination and by permeability after impact testing. At the end of the program, the manufacture of the electron beam-cured feedlines never came to fruition. All of the TTL feedlines leaked heavily before any cryogenic testing, all of the SARTM feedlines leaked heavily after one cryogenic cycle. Thus, only the HLU with autoclave cure feedlines underwent the complete test matrix. They passed the cyclic testing and were pressurized to failure.

  6. Integrated Modeling of Polymer Composites Under High Energy Laser Irradiation

    DTIC Science & Technology

    2015-10-30

    the SThM measurements deviates from standard procedures for neat resin and prepreg composites . Individual carbon fibers are suspended or draped across...AFRL-RX-WP-TR-2016-0071 INTEGRATED MODELING OF POLYMER COMPOSITES UNDER HIGH ENERGY LASER IRRADIATION Brent Volk, Gregory Ehlert...DAVIS, Chief Composite Materials and Processing Section Composite Materials and Processing Section Composite Branch

  7. Reliability analysis of ceramic matrix composite laminates

    NASA Technical Reports Server (NTRS)

    Thomas, David J.; Wetherhold, Robert C.

    1991-01-01

    At a macroscopic level, a composite lamina may be considered as a homogeneous orthotropic solid whose directional strengths are random variables. Incorporation of these random variable strengths into failure models, either interactive or non-interactive, allows for the evaluation of the lamina reliability under a given stress state. Using a non-interactive criterion for demonstration purposes, laminate reliabilities are calculated assuming previously established load sharing rules for the redistribution of load as the failure of laminae occur. The matrix cracking predicted by ACK theory is modeled to allow a loss of stiffness in the fiber direction. The subsequent failure in the fiber direction is controlled by a modified bundle theory. Results using this modified bundle model are compared with previous models which did not permit separate consideration of matrix cracking, as well as to results obtained from experimental data.

  8. Cooled Ceramic Matrix Composite Propulsion Structures Demonstrated

    NASA Technical Reports Server (NTRS)

    Jaskowiak, Martha H.; Dickens, Kevin W.

    2005-01-01

    NASA's Next Generation Launch Technology (NGLT) Program has successfully demonstrated cooled ceramic matrix composite (CMC) technology in a scramjet engine test. This demonstration represented the world s largest cooled nonmetallic matrix composite panel fabricated for a scramjet engine and the first cooled nonmetallic composite to be tested in a scramjet facility. Lightweight, high-temperature, actively cooled structures have been identified as a key technology for enabling reliable and low-cost space access. Tradeoff studies have shown this to be the case for a variety of launch platforms, including rockets and hypersonic cruise vehicles. Actively cooled carbon and CMC structures may meet high-performance goals at significantly lower weight, while improving safety by operating with a higher margin between the design temperature and material upper-use temperature. Studies have shown that using actively cooled CMCs can reduce the weight of the cooled flow-path component from 4.5 to 1.6 lb/sq ft and the weight of the propulsion system s cooled surface area by more than 50 percent. This weight savings enables advanced concepts, increased payload, and increased range. The ability of the cooled CMC flow-path components to operate over 1000 F hotter than the state-of-the-art metallic concept adds system design flexibility to space-access vehicle concepts. Other potential system-level benefits include smaller fuel pumps, lower part count, lower cost, and increased operating margin.

  9. Shock wave profiles in polymer matrix composite

    NASA Astrophysics Data System (ADS)

    Boteler, J. Michael; Rajendran, A. M.; Grove, David

    2000-04-01

    The promise of lightweight armor which is also structurally robust is of particular importance to the Army for future combat vehicles. Fiber reinforced organic matrix composites such as Polymer Matrix Composite (PMC) are being considered for this purpose due to their lower density and promising dynamic response. The work discussed here extends the prior work of Boteler who studied the delamination strength of PMC and Dandekar and Beaulieu who investigated the compressive and tensile strengths of PMC. In a series of shock wave experiments, the wave profile was examined as a function of propagation distance in PMC. Uniaxial strain was achieved by symmetric plate impact in the ARL 102 mm bore single-stage light gas gun. Embedded polyvinylidene flouride (PVDF) stress-rate gauges provided a stress history at three unique locations in the PMC and particle velocity history was recorded with VISAR. All stress data was compared to a Lagrangian hydrocode (EPIC) employing a model to describe the viscoelastic response of the composite material in one-dimension. The experimental stress histories displayed attenuation and loading properties in good agreement with model predictions. However, the unloading was observed to be markedly different than the hydrocode simulations. These results are discussed.

  10. Metal-Matrix/Hollow-Ceramic-Sphere Composites

    NASA Technical Reports Server (NTRS)

    Baker, Dean M.

    2011-01-01

    A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

  11. METal matrix composite ANalyzer (METCAN): Theoretical manual

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Chamis, C. C.

    1993-01-01

    This manuscript is intended to be a companion volume to the 'METCAN User's Manual' and the 'METAN Demonstration Manual.' The primary purpose of the manual is to give details pertaining to micromechanics and macromechanics equations of high temperature metal matrix composites that are programmed in the METCAN computer code. The subroutines which contain the programmed equations are also mentioned in order to facilitate any future changes or modifications that the user may intend to incorporate in the code. Assumptions and derivations leading to the micromechanics equations are briefly mentioned.

  12. Corrosion of Graphite Aluminum Metal Matrix Composites

    DTIC Science & Technology

    1991-02-01

    Fig. 11 is the Pourbaix potentential-pH equilibrium diagram . As can be seen Zn(OH)2 will break down as the alkalinity of the solution becomes...04 - - -[ -1,4 1.4 -. t 123 4 , 8 0 I t 12 13 14 Fig. 11 The pH-potential equilibrium Pourbaix diagram for the system zinc-water, at 25C. [Ref.: M...AD-A234 322 (23 CORROSION OF GRAPHITE ALUMINUM METAL MATRIX COMPOSITES Q APR 0 4199 1 by M.A. Buonanno, R.M. Latanision, L.H. Hihara and J.F. Chiang

  13. Metal Matrix Composite Materials for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Jones, C. S. (Technical Monitor)

    2001-01-01

    Metal matrix composites (MMC) are attractive materials for aerospace applications because of their high specific strength, high specific stiffness, and lower thermal expansion coefficient. They are affordable since complex parts can be produced by low cost casting process. As a result there are many commercial and Department of Defense applications of MMCs today. This seminar will give an overview of MMCs and their state-of-the-art technology assessment. Topics to be covered are types of MMCs, fabrication methods, product forms, applications, and material selection issues for design and manufacture. Some examples of current and future aerospace applications will also be presented and discussed.

  14. Ceramic Matrix Composites (CMC) Life Prediction Development

    NASA Technical Reports Server (NTRS)

    Levine, Stanley R.; Verrilli, Michael J.; Thomas, David J.; Halbig, Michael C.; Calomino, Anthony M.; Ellis, John R.; Opila, Elizabeth J.

    1990-01-01

    Advanced launch systems will very likely incorporate fiber reinforced ceramic matrix composites (CMC) in critical propulsion and airframe components. The use of CMC will save weight, increase operating margin, safety and performance, and improve reuse capability. For reusable and single mission use, accurate life prediction is critical to success. The tools to accomplish this are immature and not oriented toward the behavior of carbon fiber reinforced silicon carbide (C/SiC), the primary system of interest for many applications. This paper describes an approach and progress made to satisfy the need to develop an integrated life prediction system that addresses mechanical durability and environmental degradation.

  15. Evaluation of Damage Tolerance of Advanced SiC/SiC Composites after Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Ozawa, Kazumi; Katoh, Yutai; Nozawa, Takashi; Hinoki, Tatsuya; Snead, Lance L.

    2011-10-01

    Silicon carbide composites (SiC/SiC) are attractive candidate materials for structural and functional components in fusion energy systems. The effect of neutron irradiation on damage tolerance of the nuclear grade SiC/SiC composites (plain woven Hi-Nicalon™ Type-S reinforced CVI matrix composites multilayer interphase and unidirectional Tyranno™-SA3 reinforced NITE matrix with carbon mono-layer interphase) was evaluated by means of miniaturized single-edged notched beam test. No significant changes in crack extension behavior and in the load-loadpoint displacement characteristics such as the peak load and hysteresis loop width were observed after irradiation to 5.9 × 1025 n/m2 (E > 0.1 MeV) at 800°C and to 5.8 × 1025 n/m2 at 1300°C. By applying a global energy balance analysis based on non-linear fracture mechanics, the energy release rate for these composite materials was found to be unchanged by irradiation with a value of 3±2 kJ/m2. This has led to the conclusion that, for these fairly aggressive irradiation conditions, the effect of neutron irradiation on the fracture resistance of these composites appears insignificant.

  16. Research on Graphite Reinforced Glass Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.; Prewo, K. M.

    1977-01-01

    This report contains the results obtained in the first twelve months of research under NASA Langley Contract NAS1-14346 for the origination of graphite-fiber reinforced glass matrix composites. Included in the report is a summary of the research by other investigators in this area. The method selected to form the composites consisted of pulling the graphite fiber through a slurry containing powdered glass, winding up the graphite fiber and the glass it picks up on a drum, drying, cutting into segments, loading the tape segment into a graphite die, and hot pressing. During the course of the work, composites were made with a variety of graphite fibers in a C.G.W. 7740 (Pyrex) glass matrix. The graphite fibers used included Hercules HMS, Hercules HTS, Thornel 300S, and Celanese DG-102 and, of these, the Hercules HMS and Celanese DG-102 graphite fibers in C.G.W. 7740 gave the most interesting but widely different results. Hercules HMS fiber in C.G.W. 7740 glass (Pyrex) showed an average four-point flexural strength of 848 MPa or 127,300 psi. As the test temperature was raised from room temperature to 560 C in argon or vacuum, the strength was higher by 50 percent. However, in air, similar tests at 560 C gave a severe loss in strength. These composites also have good thermal cycle properties in argon or vacuum, greatly increased toughness compared to glass, and no loss in strength in a 100 cycle fatigue test. Celanese DG-102 fiber in C.G.W. 7740 glass (Pyrex) had a much lower flexural strength but did not suffer any loss in this strength when samples were heated to 560 C in air for 4 hrs.

  17. Graphite fiber reinforced glass matrix composites for aerospace applications

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Bacon, J. F.; Dicus, D. L.

    1979-01-01

    The graphite fiber reinforced glass matrix composite system is described. Although this composite is not yet a mature material, it possesses low density, attractive mechanical properties at elevated temperatures, and good environmental stability. Properties are reported for a borosilicate glass matrix unidirectionally reinforced with 60 volume percent HMS graphite fiber. The flexural strength and fatigue characteristics at room and elevated temperature, resistance to thermal cycling and continuous high temperature oxidation, and thermal expansion characteristics of the composite are reported. The properties of this new composite are compared to those of advanced resin and metal matrix composites showing that graphite fiber reinforced glass matrix composites are attractive for aerospace applications.

  18. Graphite fiber reinforced glass matrix composites for aerospace applications

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Bacon, J. F.; Dicus, D. L.

    1979-01-01

    The graphite fiber reinforced glass matrix composite system is described. Although this composite is not yet a mature material, it possesses low density, attractive mechanical properties at elevated temperatures, and good environmental stability. Properties are reported for a borosilicate glass matrix unidirectionally reinforced with 60 volume percent HMS graphite fiber. The flexural strength and fatigue characteristics at room and elevated temperature, resistance to thermal cycling and continuous high temperature oxidation, and thermal expansion characteristics of the composite are reported. The properties of this new composite are compared to those of advanced resin and metal matrix composites showing that graphite fiber reinforced glass matrix composites are attractive for aerospace applications.

  19. Fiber reinforced thermoplastic resin matrix composites

    NASA Technical Reports Server (NTRS)

    Jones, Robert J. (Inventor); Chang, Glenn E. C. (Inventor)

    1989-01-01

    Polyimide polymer composites having a combination of enhanced thermal and mechanical properties even when subjected to service temperatures as high as 700.degree. F. are described. They comprise (a) from 10 to 50 parts by weight of a thermoplastic polyimide resin prepared from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and (b) from 90 to 50 parts by weight of continuous reinforcing fibers, the total of (a) and (b) being 100 parts by weight. Composites based on polyimide resin formed from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and pyromellitic dianhydride and continuous carbon fibers retained at least about 50% of their room temperature shear strength after exposure to 700.degree. F. for a period of 16 hours in flowing air. Preferably, the thermoplastic polyimide resin is formed in situ in the composite material by thermal imidization of a corresponding amide-acid polymer prepared from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. It is also preferred to initially size the continuous reinforcing fibers with up to about one percent by weight of an amide-acid polymer prepared from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. In this way imidization at a suitable elevated temperature results in the in-situ formation of a substantially homogeneous thermoplastic matrix of the polyimide resin tightly and intimately bonded to the continuous fibers. The resultant composites tend to have optimum thermo-mechanical properties.

  20. Molecular dynamics simulation of irradiation damage of SiC/Gra/SiC composites

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Song, Huai-Zhi; Mao, Fei; Wang, Cheng-Jun; Wang, Dong-Qi; Zhang, Feng-Shou

    2017-09-01

    Silicon carbide fiber-reinforced silicon carbide matrix composites have been investigated for their use as structural materials for advanced nuclear reactor. Although quite a number of researches have been devoted to probe the effects of irradiation on various properties of the composites, there is little known about the atomistic mechanism for irradiation resistance. In this study, a two-temperature model has been used to investigate the irradiation damage of SiC/Gra/SiC composites, which includes three parts and two SiC/C interfaces, two single crystal cubic silicon carbide on two sides and a few graphene sheets in the middle part. By simulating 100 keV displacement cascades, we find that the number of defects in the reinforcement is larger than that in the matrix, which indicates the damage in the reinforcement is more serious than that in the matrix. Moreover, we explicitly investigate the damage behavior of the interphase graphene layers and find that some atoms in one graphene sheet form many new chemical bonds with atoms in another one, which leads to the transition from sp2 to sp3 hybridization. The newly formed chemical bonds link the different graphene layers and make graphene-like electronic structure more ;diamond-like;, enhancing the irradiation resistance of the matrix.

  1. Aluminum-Alloy-Matrix/Alumina-Reinforcement Composites

    NASA Technical Reports Server (NTRS)

    Kashalikar, Uday; Rozenoyer, Boris

    2004-01-01

    Isotropic composites of aluminum-alloy matrices reinforced with particulate alumina have been developed as lightweight, high-specific-strength, less-expensive alternatives to nickel-base and ferrous superalloys. These composites feature a specific gravity of about 3.45 grams per cubic centimeter and specific strengths of about 200 MPa/(grams per cubic centimeter). The room-temperature tensile strength is 100 ksi (689 MPa) and stiffness is 30 Msi (206 GPa). At 500 F (260 C), these composites have shown 80 percent retention in strength and 95 percent retention in stiffness. These materials also have excellent fatigue tolerance and tribological properties. They can be fabricated in net (or nearly net) sizes and shapes to make housings, pistons, valves, and ducts in turbomachinery, and to make structural components of such diverse systems as diesel engines, automotive brake systems, and power-generation, mining, and oil-drilling equipment. Separately, incorporation of these metal matrix composites within aluminum gravity castings for localized reinforcement has been demonstrated. A composite part of this type can be fabricated in a pressure infiltration casting process. The process begins with the placement of a mold with alumina particulate preform of net or nearly net size and shape in a crucible in a vacuum furnace. A charge of the alloy is placed in the crucible with the preform. The interior of the furnace is evacuated, then the furnace heaters are turned on to heat the alloy above its liquidus temperature. Next, the interior of the furnace is filled with argon gas at a pressure about 900 psi (approximately equal to 6.2 MPa) to force the molten alloy to infiltrate the preform. Once infiltrated, the entire contents of the crucible can be allowed to cool in place, and the composite part recovered from the mold.

  2. Characterization of Hybrid CNT Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Grimsley, Brian W.; Cano, Roberto J.; Kinney, Megan C.; Pressley, James; Sauti, Godfrey; Czabaj, Michael W.; Kim, Jae-Woo; Siochi, Emilie J.

    2015-01-01

    Carbon nanotubes (CNTs) have been studied extensively since their discovery and demonstrated at the nanoscale superior mechanical, electrical and thermal properties in comparison to micro and macro scale properties of conventional engineering materials. This combination of properties suggests their potential to enhance multi-functionality of composites in regions of primary structures on aerospace vehicles where lightweight materials with improved thermal and electrical conductivity are desirable. In this study, hybrid multifunctional polymer matrix composites were fabricated by interleaving layers of CNT sheets into Hexcel® IM7/8552 prepreg, a well-characterized toughened epoxy carbon fiber reinforced polymer (CFRP) composite. The resin content of these interleaved CNT sheets, as well as ply stacking location were varied to determine the effects on the electrical, thermal, and mechanical performance of the composites. The direct-current electrical conductivity of the hybrid CNT composites was characterized by in-line and Montgomery four-probe methods. For [0](sub 20) laminates containing a single layer of CNT sheet between each ply of IM7/8552, in-plane electrical conductivity of the hybrid laminate increased significantly, while in-plane thermal conductivity increased only slightly in comparison to the control IM7/8552 laminates. Photo-microscopy and short beam shear (SBS) strength tests were used to characterize the consolidation quality of the fabricated laminates. Hybrid panels fabricated without any pretreatment of the CNT sheets resulted in a SBS strength reduction of 70 percent. Aligning the tubes and pre-infusing the CNT sheets with resin significantly improved the SBS strength of the hybrid composite To determine the cause of this performance reduction, Mode I and Mode II fracture toughness of the CNT sheet to CFRP interface was characterized by double cantilever beam (DCB) and end notch flexure (ENF) testing, respectively. Results are compared to the

  3. Pendulum impact resistance of tungsten fiber/metal matrix composites.

    NASA Technical Reports Server (NTRS)

    Winsa, E. A.; Petrasek, D. W.

    1972-01-01

    The impact properties of copper, copper-10 nickel, and a superalloy matrix reinforced with tungsten fibers were studied. In most cases the following increased composite impact strength: increased fiber or matrix toughness, decreased fiber-matrix reaction, increased test temperature, hot working and heat treatment. Notch sensitivity was reduced by increasing fiber or matrix toughness. The effect of fiber content depended on the relative toughness of the fibers and matrix. Above 530 K a 60 volume per cent superalloy matrix composite had a greater impact strength than a turbine blade superalloy, whereas below 530 K a hot worked 56 volume per cent composite had a greater impact strength than the superalloy.

  4. Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites

    SciTech Connect

    Newsome G, Snead L, Hinoki T, Katoh Y, Peters D

    2007-03-26

    The effects of fast neutron irradiation on SiC and SiC composites have been studied. The materials used were chemical vapor deposition (CVD) SiC and SiC/SiC composites reinforced with either Hi-Nicalon{trademark} Type-S, Hi-Nicalon{trademark} or Sylramic{trademark} fibers fabricated by chemical vapor infiltration. Statistically significant numbers of flexural samples were irradiated up to 4.6 x 10{sup 25} n/m{sup 2} (E>0.1 MeV) at 300, 500 and 800 C in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Dimensions and weights of the flexural bars were measured before and after the neutron irradiation. Mechanical properties were evaluated by four point flexural testing. Volume increase was seen for all bend bars following neutron irradiation. Magnitude of swelling depended on irradiation temperature and material, while it was nearly independent of irradiation fluence over the fluence range studied. Flexural strength of CVD SiC increased following irradiation depending on irradiation temperature. Over the temperature range studied, no significant degradation in mechanical properties was seen for composites fabricated with Hi-Nicalon{trademark} Type-S, while composites reinforced with Hi-Nicalon{trademark} or Sylramic fibers showed significant degradation. The effects of irradiation on the Weibull failure statistics are also presented suggesting a reduction in the Weibull modulus upon irradiation. The cause of this potential reduction is not known.

  5. Advanced Measurements of Silicon Carbide Ceramic Matrix Composites

    SciTech Connect

    Farhad Farzbod; Stephen J. Reese; Zilong Hua; Marat Khafizov; David H. Hurley

    2012-08-01

    Silicon carbide (SiC) is being considered as a fuel cladding material for accident tolerant fuel under the Light Water Reactor Sustainability (LWRS) Program sponsored by the Nuclear Energy Division of the Department of Energy. Silicon carbide has many potential advantages over traditional zirconium based cladding systems. These include high melting point, low susceptibility to corrosion, and low degradation of mechanical properties under neutron irradiation. In addition, ceramic matrix composites (CMCs) made from SiC have high mechanical toughness enabling these materials to withstand thermal and mechanical shock loading. However, many of the fundamental mechanical and thermal properties of SiC CMCs depend strongly on the fabrication process. As a result, extrapolating current materials science databases for these materials to nuclear applications is not possible. The “Advanced Measurements” work package under the LWRS fuels pathway is tasked with the development of measurement techniques that can characterize fundamental thermal and mechanical properties of SiC CMCs. An emphasis is being placed on development of characterization tools that can used for examination of fresh as well as irradiated samples. The work discuss in this report can be divided into two broad categories. The first involves the development of laser ultrasonic techniques to measure the elastic and yield properties and the second involves the development of laser-based techniques to measurement thermal transport properties. Emphasis has been placed on understanding the anisotropic and heterogeneous nature of SiC CMCs in regards to thermal and mechanical properties. The material properties characterized within this work package will be used as validation of advanced materials physics models of SiC CMCs developed under the LWRS fuels pathway. In addition, it is envisioned that similar measurement techniques can be used to provide process control and quality assurance as well as measurement of

  6. High-strain composites and dual-matrix composite structures

    NASA Astrophysics Data System (ADS)

    Maqueda Jimenez, Ignacio

    another finite element model that simulated a homogenized rod under axial compression. A statistical representation of the fiber angles was implemented in the model. The presence of fiber angles increased the longitudinal shear stiffness of the material, resulting in a higher strength in compression. The simulations showed a large increase of the strength in compression for lower values of the standard deviation of the fiber angle, and a slight decrease of strength in compression for lower values of the mean fiber angle. The strength observed in the experiments was achieved with the minimum local angle standard deviation observed in the CFRS rods, whereas the shear stiffness measured in torsion tests was achieved with the overall fiber angle distribution observed in the CFRS rods. High strain composites exhibit good bending capabilities, but they tend to be soft out-of-plane. To achieve a higher out-of-plane stiffness, the concept of dual-matrix composites is introduced. Dual-matrix composites are foldable composites which are soft in the crease regions and stiff elsewhere. Previous attempts to fabricate continuous dual-matrix fiber composite shells had limited performance due to excessive resin flow and matrix mixing. An alternative method, presented in this thesis uses UV-cure silicone and fiberglass to avoid these problems. Preliminary experiments on the effect of folding on the out-of-plane stiffness are presented. An application to a conical log-periodic antenna for CubeSats is proposed, using origami-inspired stowing schemes, that allow a conical dual-matrix composite shell to reach very high compaction ratios.

  7. Composite Materials With Uncured Epoxy Matrix Exposed in Stratosphere During NASA Stratospheric Balloon Flight

    NASA Technical Reports Server (NTRS)

    Kondyurin, Alexey; Kondyurina, Irina; Bilek, Marcela; de Groh, Kim K.

    2013-01-01

    A cassette of uncured composite materials with epoxy resin matrixes was exposed in the stratosphere (40 km altitude) over three days. Temperature variations of -76 to 32.5C and pressure up to 2.1 torr were recorded during flight. An analysis of the chemical structure of the composites showed, that the polymer matrix exposed in the stratosphere becomes crosslinked, while the ground control materials react by way of polymerization reaction of epoxy groups. The space irradiations are considered to be responsible for crosslinking of the uncured polymers exposed in the stratosphere. The composites were cured on Earth after landing. Analysis of the cured composites showed that the polymer matrix remains active under stratospheric conditions. The results can be used for predicting curing processes of polymer composites in a free space environment during an orbital space flight.

  8. Surface integrity of solvent-challenged ormocer-matrix composite.

    PubMed

    Cavalcante, Larissa Maria; Schneider, Luis Felipe J; Silikas, Nick; Watts, David C

    2011-02-01

    To investigate the surface integrity of solvent-challenged ormocer-matrix composites, photoactivated by different light exposure modes, through surface-hardness measurements at different periods of time; and to compare such behavior with dimethacrylate-based materials. One hundred percent ormocer-based matrix (experimental ormocer (ORM)), a commercial mixed dimethacrylate-ormocer-based matrix (Admira (ADR)) and two commercial dimethacrylate-based matrix composites (experimental controls, (Grandio (GRD) and Premise (PRE)) were evaluated. Disk specimens (4 mm × 2 mm) were prepared from each material and light-activated using either a standard (S) or soft-start (SS) light exposure protocol with an LED-curing unit. Top, irradiated surface Knoop hardness (KHN) was measured within the following experimental groups (n=5): Group 1: immediately after exposure; Group 2: after dry and dark storage, Group 3: after storage in distilled water, and Group 4: immersion in absolute ethanol. Hardness of Groups 2-4 were measured after 7 days storage. Immediate hardness values were submitted to Student's t-tests separately for each material. Hardness values after treatments were submitted to two-way ANOVA and Tukey's post hoc test to compare values among different storage media and light exposure mode protocols. Comparisons among materials were described using percentage of hardness change. Statistical testing was performed at a pre-set alpha of 0.05. Immediate hardness values were not affected by the light exposure mode, regardless of the material. In general, exposure mode did not significantly affect hardness after 7 days storage, regardless of storage media or material. After 7 days dry storage, hardness values increased for all materials relative to immediate testing, and decreased after water and ethanol storage, with ethanol showing the greatest effect. The experimental ormocer-based material had the lowest percentage hardness change and thus proved more resistant to solvent

  9. Intelligent processing for metal matrix composites

    NASA Astrophysics Data System (ADS)

    Backman, D. G.; Russell, E. S.; Wei, D. Y.; Pang, Y.

    Intelligent processing of materials (IPM) is a powerful processing concept which requires integration of process knowledge, analytical models, process sensors, and expert system based control technology. An IPM system to manufacture metal matrix composites (MMC) using inductively coupled plasma deposition is under development. Process knowledge is contained in a reduced-order process simulator, consisting of thermal, fluid flow, solid mechanics, and material kinetics models. A working deposit thermal model has been developed, while the solid mechanics and material kinetics models are under development. Future directions for IPM development are discussed, including integration with related MMC processing operations, and establishment of a control system in which expert system based control is used to replicate operator decision-making.

  10. Ceramic - Matrix Composites for Extreme Applications

    NASA Astrophysics Data System (ADS)

    Ortona, A.; Gaia, D.; Maiola, G.; Capelari, T.; Mannarino, L.; Pin, F.; Ghisolfi, E.

    2008-06-01

    Hi-tech systems whose components operate in working conditions characterised by a chemically aggressive environment and elevated temperatures (above 1000°C) are ever more numerous. If metallic materials are not suitably protected and cooled under these conditions, they operate at the limit of their capacity and therefore the integrity of the component can not be guaranteed. Their cooling may furthermore constitute considerable complications in terms of their design. Ceramic materials are a category of materials that bears such extreme working conditions well. However, these materials are actually scarcely used due to their fragility. This limit is overcome by Ceramic Matrix Composites materials (CMCs). All the technologies introduced in this study are developed at FN S.P.A.

  11. Metal Matrix Composites for Rocket Engine Applications

    NASA Technical Reports Server (NTRS)

    McDonald, Kathleen R.; Wooten, John R.

    2000-01-01

    This document is from a presentation about the applications of Metal Matrix Composites (MMC) in rocket engines. Both NASA and the Air Force have goals which would reduce the costs and the weight of launching spacecraft. Charts show the engine weight distribution for both reuseable and expendable engine components. The presentation reviews the operating requirements for several components of the rocket engines. The next slide reviews the potential benefits of MMCs in general and in use as materials for Advanced Pressure Casting. The next slide reviews the drawbacks of MMCs. The reusable turbopump housing is selected to review for potential MMC application. The presentation reviews solutions for reusable turbopump materials, pointing out some of the issues. It also reviews the development of some of the materials.

  12. Fracture toughness testing of polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Grady, Joseph E.

    1992-01-01

    A review of the interlaminar fracture indicates that a standard specimen geometry is needed to obtain consistent fracture toughness measurements in polymer matrix composites. In general, the variability of measured toughness values increases as the toughness of the material increases. This variability could be caused by incorrect sizing of test specimens and/or inconsistent data reduction procedures. A standard data reduction procedure is therefore needed as well, particularly for the tougher materials. Little work has been reported on the effects of fiber orientation, fiber architecture, fiber surface treatment or interlaminar fracture toughness, and the mechanisms by which the fibers increase fracture toughness are not well understood. The little data that is available indicates that woven fiber reinforcement and fiber sizings can significantly increase interlaminar fracture toughness.

  13. Biodegradable magnesium-hydroxyapatite metal matrix composites.

    PubMed

    Witte, Frank; Feyerabend, Frank; Maier, Petra; Fischer, Jens; Störmer, Michael; Blawert, Carsten; Dietzel, Wolfgang; Hort, Norbert

    2007-04-01

    Recent studies indicate that there is a high demand to design magnesium alloys with adjustable corrosion rates and suitable mechanical properties. An approach to this challenge might be the application of metal matrix composite (MMC) based on magnesium alloys. In this study, a MMC made of magnesium alloy AZ91D as a matrix and hydroxyapatite (HA) particles as reinforcements have been investigated in vitro for mechanical, corrosive and cytocompatible properties. The mechanical properties of the MMC-HA were adjustable by the choice of HA particle size and distribution. Corrosion tests revealed that HA particles stabilised the corrosion rate and exhibited more uniform corrosion attack in artificial sea water and cell solutions. The phase identification showed that all samples contained hcp-Mg, Mg(17)Al(12), and HA before and after immersion. After immersion in artificial sea water CaCO3 was found on MMC-HA surfaces, while no formation of CaCO3 was found after immersion in cell solutions with and without proteins. Co-cultivation of MMC-HA with human bone derived cells (HBDC), cells of an osteoblasts lineage (MG-63) and cells of a macrophage lineage (RAW264.7) revealed that RAW264.7, MG-63 and HBDC adhere, proliferate and survive on the corroding surfaces of MMC-HA. In summary, biodegradable MMC-HA are cytocompatible biomaterials with adjustable mechanical and corrosive properties.

  14. Gamma irradiation assisted fungal degradation of the polypropylene/biomass composites

    NASA Astrophysics Data System (ADS)

    Butnaru, Elena; Darie-Niţă, Raluca Nicoleta; Zaharescu, Traian; Balaeş, Tiberius; Tănase, Cătălin; Hitruc, Gabriela; Doroftei, Florica; Vasile, Cornelia

    2016-08-01

    White-rot fungus Bjerkandera adusta has been tested for its ability to degrade some biocomposites materials based on polypropylene and biomass (Eucalyptus globulus, pine cones, and Brassica rapa). γ-irradiation was applied to initiate the degradation of relatively inert polypropylene matrix. The degradation process has been studied by scanning electron microscopy, atomic force microscopy, infrared spectroscopy, contact angle measurements, rheological and chemiluminescence tests. These analyses showed that the polypropylene/biomass composites properties are worsen under the action of the selected microorganism. The formation of cracks and scrap particles over the entire matrix surface and the decrease of the complex viscosity values, as well as the dynamic moduli of gamma irradiated PP/biomass composite and exposed to Bjerkandera adusta fungus, indicate fungal efficiency in composite degradation.

  15. Development of Damped Metal Matrix Composites for Advanced Structural Applications

    DTIC Science & Technology

    1990-04-01

    DTIP FiLE COPY Applied Research Laboratory (Dto 00 CD Technical Report NO DEVELOPMENT OF DAMPED METAL MATRIX COMPOSITES FOR ADVANCED STRUCTURAL...DEVELOPMENT OF DAMPED METAL MATRIX COMPOSITES FOR ADVANCED STRUCTURAL APPLICATIONS by Clark A. Updike Ram B. Bhagat Technical Report No. TR 90-004 April 1990... Metal Matrix Composites for Advanced Structural Applications 12 PERSONAL AUTHOR(S) C.A. Updike, R. Bhagat 1 3a TYPE OF REPORT 13b TIME COVERED 14. DATE

  16. Characterizing damage in ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Gyekenyesi, Andrew L.; Baker, Christopher; Morscher, Gregory

    2014-04-01

    With the upcoming implementation of ceramic matrix composites (CMCs) within aerospace systems (e.g., aviation turbine engines), an in-depth understanding of the failure process due to mechanical loads is required. This includes developing a basic understanding of the complex, multi-mechanism failure process as well as the associated nondestructive evaluation (NDE) techniques that are capable of recognizing and quantifying the damage. Various NDE techniques have been successfully utilized for assessing the damage state of woven CMCs, in particular, consisting of silicon carbide fibers and silicon carbide matrices (SiC/SiC). The multiple NDE techniques, studied by the authors of this paper, included acousto-ultrasonics, modal acoustic emissions, electrical resistance, impedance based structural health monitoring, pulsed thermography as well as thermoelastic stress analysis. The observed damage within the composites was introduced using multiple experimental tactics including uniaxial tensile tests, creep tests, and most recently, ballistic impact. This paper offers a brief review and summary of results for each of the applied NDE tools.

  17. Method of forming a ceramic matrix composite and a ceramic matrix component

    DOEpatents

    de Diego, Peter; Zhang, James

    2017-05-30

    A method of forming a ceramic matrix composite component includes providing a formed ceramic member having a cavity, filling at least a portion of the cavity with a ceramic foam. The ceramic foam is deposited on a barrier layer covering at least one internal passage of the cavity. The method includes processing the formed ceramic member and ceramic foam to obtain a ceramic matrix composite component. Also provided is a method of forming a ceramic matrix composite blade and a ceramic matrix composite component.

  18. Enhanced release of bone morphogenetic proteins from demineralized bone matrix by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Sung, Nak-Yun; Choi, Jong-il

    2015-06-01

    Gamma irradiation is a useful method for sterilizing demineralized bone matrix (DBM), but its effect on the osteoinductivity of DBM is still controversial. In this study, the osteoinductive activity of gamma-irradiated DBM was examined using a mouse myoblastic cell line (C2C12). DBM was extracted from adult bovine bone and was irradiated at a dose of 25 kGy using a 60cobalt gamma-irradiator. Cell proliferation with DBM was not affected by gamma-irradiation, but alkaline phosphatase and osteocalcin productions were significantly increased in C2C12 cell groups treated with gamma-irradiated DBM. It was reasoned that bone morphogenetic proteins were more efficiently released from gamma-irradiated DBM than from the non-irradiated control. This result suggests the effectiveness of radiation sterilization of bone implants

  19. The behaviour under irradiation of molybdenum matrix for inert matrix fuel containing americium oxide (CerMet concept)

    NASA Astrophysics Data System (ADS)

    D'Agata, E.; Knol, S.; Fedorov, A. V.; Fernandez, A.; Somers, J.; Klaassen, F.

    2015-10-01

    Americium is a strong contributor to the long term radiotoxicity of high activity nuclear waste. Transmutation by irradiation in nuclear reactors or Accelerator Driven System (ADS, subcritical reactors dedicated to transmutation) of long-lived nuclides like 241Am is therefore an option for the reduction of radiotoxicity of waste packages to be stored in a repository. In order to safely burn americium in a fast reactor or ADS, it must be incorporated in a matrix that could be metallic (CerMet target) or ceramic (CerCer target). One of the most promising matrix to incorporate Am is molybdenum. In order to address the issues (swelling, stability under irradiation, gas retention and release) of using Mo as matrix to transmute Am, two irradiation experiments have been conducted recently at the High Flux Reactor (HFR) in Petten (The Netherland) namely HELIOS and BODEX. The BODEX experiment is a separate effect test, where the molybdenum behaviour is studied without the presence of fission products using 10B to ;produce; helium, the HELIOS experiment included a more representative fuel target with the presence of Am and fission product. This paper covers the results of Post Irradiation Examination (PIE) of the two irradiation experiments mentioned above where molybdenum behaviour has been deeply investigated as possible matrix to transmute americium (CerMet fuel target). The behaviour of molybdenum looks satisfying at operating temperature but at high temperature (above 1000 °C) more investigation should be performed.

  20. Microstructure formation during solidification of metal matrix composites

    SciTech Connect

    Rohatgi, P.K.

    1993-01-01

    The second symposium on solidification of metal matrix composites was organized at the TMS-ASM Materials Week in Chicago, in November 1992, to discuss the important issues in solidification of composites. In this collection of ten papers; several aspects of solidification of composites including nucleation, growth, heat flow, particle pushing, interface stability and segregation during solidification of metal matrix composites are discussed. Individual papers have been processed separately for inclusion in the appropriate data bases.

  1. Formation of long-range ordered quantum dots arrays in amorphous matrix by ion beam irradiation

    SciTech Connect

    Buljan, M.; Bogdanovic-Radovic, I.; Karlusic, M.; Desnica, U. V.; Radic, N.; Dubcek, P.; Drazic, G.; Salamon, K.; Bernstorff, S.; Holy, V.

    2009-08-10

    We demonstrate the production of a well ordered three-dimensional array of Ge quantum dots in amorphous silica matrix. The ordering is achieved by ion beam irradiation and annealing of a multilayer film. Structural analysis shows that quantum dots nucleate along the direction of the ion beam used for irradiation, while the mutual distance of the quantum dots is determined by the diffusion properties of the multilayer material rather than the distances between traces of ions that are used for irradiation.

  2. INTEGRATED COI S200 - Hi-NiCalon FIBER WITH AN S200 MATRIX (POLYMER MATRIX COMPOSITE - PMC) / AETB 1

    NASA Technical Reports Server (NTRS)

    2003-01-01

    INTEGRATED COI S200 - Hi-NiCalon FIBER WITH AN S200 MATRIX (POLYMER MATRIX COMPOSITE - PMC) / AETB 16 (FOAM CORE) / CARBON REINFORCED CYANOESTER (CERAMIC MATRIX COMPOSITE - CMC) HOT STRUCTURE, PANEL 884-1: SAMPLE 1

  3. INTEGRATED COI S200 - Hi-NiCalon FIBER WITH AN S200 MATRIX (POLYMER MATRIX COMPOSITE - PMC) / AETB 1

    NASA Technical Reports Server (NTRS)

    2003-01-01

    INTEGRATED COI S200 - Hi-NiCalon FIBER WITH AN S200 MATRIX (POLYMER MATRIX COMPOSITE - PMC) / AETB 16 (FOAM CORE) / CARBON REINFORCED CYANOESTER (CERAMIC MATRIX COMPOSITE - CMC) HOT STRUCTURE, PANEL 884-1: SAMPLE 3

  4. Advanced composites: Environmental effects on selected resin matrix materials

    NASA Technical Reports Server (NTRS)

    Welhart, E. K.

    1976-01-01

    The effects that expected space flight environment has upon the mechanical properties of epoxy and polyimide matrix composites were analyzed. Environmental phenomena covered water immersion, high temperature aging, humidity, lightning strike, galvanic action, electromagnetic interference, thermal shock, rain and sand erosion, and thermal/vacuum outgassing. The technology state-of-the-art for graphite and boron reinforced epoxy and polyimide matrix materials is summarized to determine the relative merit of using composites in the space shuttle program. Resin matrix composites generally are affected to some degree by natural environmental phenomena with polyimide resin matrix materials less affected than epoxies.

  5. High Dose Neutron Irradiation of Hi-Nicalon Type S Silicon Carbide Composites, Part 2. Mechanical and Physical Properties

    SciTech Connect

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao Phillip; Ozawa, Kazumi; Koyanagi, Takaaki; Porter, Wallace D; Snead, Lance Lewis

    2015-01-07

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573–1073 K. Likewise, the material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating the irradiation temperature, but only to a limited extent. Moreover, the observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.

  6. Parametric Study Of A Ceramic-Fiber/Metal-Matrix Composite

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Hopkins, D. A.; Chamis, C. C.

    1992-01-01

    Report describes computer-model parametric study of effects of degradation of constituent materials upon mechanical properties of ceramic-fiber/metal-matrix composite material. Contributes to understanding of weakening effects of large changes in temperature and mechanical stresses in fabrication and use. Concerned mainly with influences of in situ fiber and matrix properties upon behavior of composite. Particular attention given to influence of in situ matrix strength and influence of interphase degradation.

  7. 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.

  8. Inelastic behavior of beta-21S composite matrix material

    SciTech Connect

    Schoeppner, G.; French, M.

    1995-12-31

    Creep test data for the {beta} 21S composite matrix material is analyzed using renewal theory. The results show that the data can be modeled by very few parameters and that time-varying load effects can be predicted by simple generalization of the theory. The understanding of the high temperature inelastic behavior of composite matrix materials is an important factor in identifying the limitations and damage evolution in composite structures. In particular, metal matrix composites which are typically used in elevated-temperature environments, require an understanding of the strain-rate sensitivity and time dependent behavior of the material.

  9. Modeling the Stress Strain Behavior of Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.

    2006-01-01

    Woven SiC fiber reinforced SiC matrix composites represent one of the most mature composite systems to date. Future components fabricated out of these woven ceramic matrix composites are expected to vary in shape, curvature, architecture, and thickness. The design of future components using woven ceramic matrix composites necessitates a modeling approach that can account for these variations which are physically controlled by local constituent contents and architecture. Research over the years supported primarily by NASA Glenn Research Center has led to the development of simple mechanistic-based models that can describe the entire stress-strain curve for composite systems fabricated with chemical vapor infiltrated matrices and melt-infiltrated matrices for a wide range of constituent content and architecture. Several examples will be presented that demonstrate the approach to modeling which incorporates a thorough understanding of the stress-dependent matrix cracking properties of the composite system.

  10. Tungsten fiber reinforced copper matrix composites: A review

    NASA Technical Reports Server (NTRS)

    Mcdanels, David L.

    1989-01-01

    Tungsten fiber reinforced copper matrix (W/Cu) composites have served as an ideal model system with which to analyze the properties of metal matrix composites. A series of research programs were conducted to investigate the stress-strain behavior of W/Cu composites; the effect of fiber content on the strength, modulus, and conductivity of W/Cu composites; and the effect of alloying elements on the behavior of tungsten wire and of W/Cu composites. Later programs investigated the stress-rupture, creep, and impact behavior of these composites at elevated temperatures. Analysis of the results of these programs as allows prediction of the effects of fiber properties, matrix properties, and fiber content on the properties of W/Cu composites. These analyses form the basis for the rule-of-mixtures prediction of composite properties which was universally adopted as the criteria for measuring composite efficiency. In addition, the analyses allows extrapolation of potential properties of other metal matrix composites and are used to select candidate fibers and matrices for development of tungsten fiber reinforced superalloy composite materials for high temperature aircraft and rocket engine turbine applications. The W/Cu composite efforts are summarized, some of the results obtained are described, and an update is provided on more recent work using W/Cu composites as high strength, high thermal conductivity composite materials for high heat flux, elevated temperature applications.

  11. Evaluation of waterjet-machined metal matrix composite tensile specimens

    SciTech Connect

    Lavender, C.A.; Smith, M.T.

    1986-04-01

    Four magnesium/boron carbide metal matrix composite (MMC) tensile specimens fabricated using the waterjet machining method were evaluated in order to determine the effects of the waterjet material removal process on the composite material surface structure and properties. These results were then compared with data from material conventionally machined. Results showed that while waterjet cutting produces a rough surface finish and does not meet specified dimensional tolerances, the technique appears to be suitable for sectioning and rough machining of metal matrix composites.

  12. Fabrication and characterization of AZ91/CNT magnesium matrix composites

    NASA Astrophysics Data System (ADS)

    Park, Yong-Ha; Park, Yong-Ho; Park, Ik-Min; Oak, Jeong-jung; Kimura, Hisamichi; Cho, Kyung-Mox

    2008-12-01

    Carbon Nano Tube (CNT) reinforced AZ91 metal matrix composites (MMC) were fabricated by the squeeze infiltrated method. Properties of magnesium alloys have been improved by impurity reduction, surface treatment and alloy design, and thus the usage for the magnesium alloys has been extended recently. However there still remain barriers for the adaption of magnesium alloys for engineering materials. In this study, we report light-weight, high strength heat resistant magnesium matrix composites. Microstructural study and tensile test were performed for the squeeze infiltrated magnesium matrix composites. The wear properties were characterized and the possibility for the application to automotive power train and engine parts was investigated. It was found that the squeeze infiltration technique is a proper method to fabricate magnesium matrix composites reducing casting defects such as pores and matrix/reinforcement interface separation etc. Improved tensile and mechanical properties were obtained with CNT reinforcing magnesium alloys

  13. Detecting Cracks in Ceramic Matrix Composites by Electrical Resistance

    NASA Technical Reports Server (NTRS)

    Smith, Craig; Gyekenyesi, Andrew

    2011-01-01

    The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90o fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

  14. Detecting Damage in Ceramic Matrix Composites Using Electrical Resistance

    NASA Technical Reports Server (NTRS)

    Smith, Craig E.; Gyekenyesi, Andrew

    2011-01-01

    The majority of damage in SiC/SiC ceramic matrix composites subjected to monotonic tensile loads is in the form of distributed matrix cracks. These cracks initiate near stress concentrations, such as 90 deg fiber tows or large matrix pores and continue to accumulate with additional stress until matrix crack saturation is achieved. Such damage is difficult to detect with conventional nondestructive evaluation techniques (immersion ultrasonics, x-ray, etc.). Monitoring a specimen.s electrical resistance change provides an indirect approach for monitoring matrix crack density. Sylramic-iBN fiber- reinforced SiC composites with a melt infiltrated (MI) matrix were tensile tested at room temperature. Results showed an increase in resistance of more than 500% prior to fracture, which can be detected either in situ or post-damage. A relationship between resistance change and matrix crack density was also determined.

  15. Probabilistic micromechanics of woven ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Goldsmith, Marlana

    Woven ceramic matrix composites are a special class of composite materials that are of current interest for harsh thermo-structural conditions such as those encountered by hypersonic vehicle systems and turbine engine components. Testing of the materials is expensive, especially as materials are constantly redesigned. Randomness in the tow architecture, as well as the randomly shaped and spaced voids that are produced as a result of the manufacturing process, are features that contribute to variability in stiffness and strength. The goal of the research is to lay a foundation in which characteristics of the geometry can be translated into material properties. The research first includes quantifying the architectural variability based on 2D micrographs of a 5 harness satin CVI (Chemical Vapor Infiltration) SiC/SiC composite. The architectural variability is applied to a 2D representative volume element (RVE) in order to evaluate which aspects of the architecture are important to model in order to capture the variability found in the cross sections. Tow width, tow spacing, and tow volume fraction were found to have some effect on the variability, but voids were found to have a large influence on transverse stiffness, and a separate study was conducted to determine which characteristics of the voids are most critical to model. It was found that the projected area of the void perpendicular to the transverse direction and the number of voids modeled had a significant influence on the stiffness. The effect of varying architecture on the variability of in-plane tensile strength was also studied using the Brittle Cracking Model for Concrete in the commercial finite element software, Abaqus. A maximum stress criterion is used to evaluate failure, and the stiffness of failed elements is gradually degraded such that the energy required to open a crack (fracture energy) is dissipated during this degradation process. While the varying architecture did not create variability in

  16. Mechanical Properties of Continuous Fiber Reinforced Zirconium Diboride Matrix Composites

    NASA Technical Reports Server (NTRS)

    Stuffle, Kevin; Creegan, Peter; Nowell, Steven; Bull, Jeffrey D.; Rasky, Daniel J. (Technical Monitor)

    1995-01-01

    Continuous fiber reinforced zirconium diboride matrix composites, SCS-9a-(RBSiCZrB2)matrix, are being developed for leading edge, rocket nozzle and turbine engine applications. Recently, the composite materials have been characterized for tensile properties to 1250 C, the highest temperature tested. The tensile properties are fiber dominated as the matrix is microcracked on fabrication, but favorable failure characteristic are observed. Compression and shear mechanical testing results will be reported if completed. The effects of fiber volume fraction and matrix density on mechanical properties will be discussed. The target applications of the materials will be discussed. Specific testing being performed towards qualification for these applications will be included.

  17. Mechanical Properties of Continuous Fiber Reinforced Zirconium Diboride Matrix Composites

    NASA Technical Reports Server (NTRS)

    Stuffle, Kevin; Creegan, Peter; Nowell, Steven; Bull, Jeffrey D.; Rasky, Daniel J. (Technical Monitor)

    1995-01-01

    Continuous fiber reinforced zirconium diboride matrix composites, SCS-9a-(RBSiCZrB2)matrix, are being developed for leading edge, rocket nozzle and turbine engine applications. Recently, the composite materials have been characterized for tensile properties to 1250 C, the highest temperature tested. The tensile properties are fiber dominated as the matrix is microcracked on fabrication, but favorable failure characteristic are observed. Compression and shear mechanical testing results will be reported if completed. The effects of fiber volume fraction and matrix density on mechanical properties will be discussed. The target applications of the materials will be discussed. Specific testing being performed towards qualification for these applications will be included.

  18. Gamma-irradiation of coumarins in a polystyrene matrix

    NASA Astrophysics Data System (ADS)

    Pla-Dalmau, Anna; Foster, G. William; Zhang, Ge

    1996-10-01

    Polystyrene samples doped with commercially available coumarin derivatives were prepared and tested as wavelength shifters for plastic scintillation applications. Radiation damage studies were performed utilizing a 60Co source. Transmittance and light yield measurements were recorded before and after irradiation (100 kGy), and after annealing of the samples. All samples experienced losses in transmittance and light yield as a result of radiation-induced damage to the polymer and in some cases, the dopant. None of the coumarins examined in this study outperformed the commonly-used green wavelength shifter, K-27, after irradiation.

  19. Development of a reaction-sintered silicon carbide matrix composite

    NASA Astrophysics Data System (ADS)

    Sayano, A.; Sutoh, C.; Suyama, S.; Itoh, Y.; Nakagawa, S.

    SiC matrix composites reinforced with continuous SiC-based fibres using reaction sintering (RS) for matrix processing were produced and their mechanical and physical properties were studied. Mechanical behaviour of SiCf/SiC (RS) composites in tension and in flexure exhibits improved toughness and a non-catastrophic failure due to fibre crack bridging and pullout from the matrix, and the composites exhibit high thermal conductivity, high Young's modulus and reduced porosity. Moreover, SiCf/SiC (RS) composites showed improved thermal shock resistance in comparison to monolithic RS-SiC. SiC matrix processing by RS leads to reduced production times and lower costs when compared with other methods such as polymer impregnation and pyrolysis (PIP) or chemical vapour infiltration (CVI). Composite prototypes were also produced for feasibility demonstration, and it was verified that the method could be applied to produce large parts and complex shapes.

  20. Continuous fiber ceramic matrix composites for heat engine components

    NASA Technical Reports Server (NTRS)

    Tripp, David E.

    1988-01-01

    High strength at elevated temperatures, low density, resistance to wear, and abundance of nonstrategic raw materials make structural ceramics attractive for advanced heat engine applications. Unfortunately, ceramics have a low fracture toughness and fail catastrophically because of overload, impact, and contact stresses. Ceramic matrix composites provide the means to achieve improved fracture toughness while retaining desirable characteristics, such as high strength and low density. Materials scientists and engineers are trying to develop the ideal fibers and matrices to achieve the optimum ceramic matrix composite properties. A need exists for the development of failure models for the design of ceramic matrix composite heat engine components. Phenomenological failure models are currently the most frequently used in industry, but they are deterministic and do not adequately describe ceramic matrix composite behavior. Semi-empirical models were proposed, which relate the failure of notched composite laminates to the stress a characteristic distance away from the notch. Shear lag models describe composite failure modes at the micromechanics level. The enhanced matrix cracking stress occurs at the same applied stress level predicted by the two models of steady state cracking. Finally, statistical models take into consideration the distribution in composite failure strength. The intent is to develop these models into computer algorithms for the failure analysis of ceramic matrix composites under monotonically increasing loads. The algorithms will be included in a postprocessor to general purpose finite element programs.

  1. Preparation of pinewood/polymer/composites using gamma irradiation

    NASA Astrophysics Data System (ADS)

    Ajji, Zaki

    2006-09-01

    Wood/polymer composites (WPC) have been prepared from pinewood with different compounds using gamma irradiation: butyl acrylate, butyl methacrylate, styrene, acrylamide, acrylonitrile, and unsaturated polyester styrene resin. The polymer loading was determined with respect to the compound concentration and the irradiation dose. The polymer loading increases generally with increase in the monomer or polymer concentration. Tensile and compression strength have been improved in the four cases, but no improvement was observed using unsaturated polyester styrene resin or acrylamide.

  2. Post-Irradiation Polymerization of a Silorane Composite

    DTIC Science & Technology

    2013-04-26

    Post-Irradiation Polymerization of a Silorane Composite A THESIS Presented to the Faculty of The Air Force Postgraduate Dental School...Oral Biology By Bryan Michael Wilson, BS, MS, DDS Dunn Dental Clinic JBSA-Lackland, TX 26 Apr 2013 2 ii Poet-Irradiation...Postgraduate Dental School (AFPDS) 4. Phone: 210-671-9822 5. Type of clearance: _Paper _Article_ Book _x_Poster _Presentation _Other 6. Title: Post

  3. Effects of neutron irradiation on microstructure and mechanical properties of carbon/carbon composites

    NASA Astrophysics Data System (ADS)

    Hamada, K.; Sato, S.; Kohyama, A.

    1994-09-01

    As an important part of the national R&D program to high performance and low cost {C}/{C} composite materials, a new manufacturing method of {C}/{C} composite with densified matrix without conventional densification process has been successfully developed. In this study, neutron irradiation effects on mechanical properties of the innovative {C}/{C} composites were examined. Materials used were one- and two-directionally reinforced composites with mesophase-pitch based carbon fibers as reinforcement and the mixture of green coke and phenolic resin as matrix precursor. Neutron irradiation was performed to 1.3 × 10 21 and 1.5 × 10 22 n/m 2 ( E > 1 MeV) at about 350 K. Mechanical properties were measured by bend tests. Flexural and shear strength were increased with increasing neutron fluence. On the contrary, fracture strain showed quite a little dependence on neutron fluence. Flexural modulus at near 0 strain was increased with increasing fluence. Stress stiffening at near 0 strain was suppressed with irradiation, while modulus drop was observed at high strain region and decreased with increasing neutron fluence. These results were interpreted in terms of microstructural change.

  4. Review of fracture and fatigue in ceramic matrix composites

    SciTech Connect

    Birman, V.; Byrd, L.W.

    2000-06-01

    A review of recent developments and state-of-the-art in research and understanding of damage and fatigue of ceramic matrix composites is presented. Both laminated as well as woven configurations are considered. The work on the effects of high temperature on fracture and fatigue of ceramic matrix composites is emphasized, because these materials are usually designed to operate in hostile environments. Based on a detailed discussion of the mechanisms of failure, the problems that have to be addressed for a successful implementation of ceramic matrix composites in design and practical operational structures are outlined. This review article includes 317 references.

  5. CMCs for the long run. [ceramic-matrix composites

    NASA Technical Reports Server (NTRS)

    Dicarlo, James A.

    1989-01-01

    The structural and environmental requirements for ceramic matrix composites (CMCs) are most demanding in aerospace applications involving human transport; this need for extreme reliability has led to intensive investigations of criteria for high CMC integrity. The ideal properties of a fiber-reinforced CMC have been found to depend on the use of high aspect ratio fibers capable of maximum strength retention during fabrication, uniform fiber infiltration by the matrix material, high matrix oxidation resistance in elevated temperature applications, and a fiber/matrix interface that accommodates debonding in the presence of matrix cracks.

  6. Nanophosphor composite scintillator with a liquid matrix

    DOEpatents

    McKigney, Edward Allen; Burrell, Anthony Keiran; Bennett, Bryan L.; Cooke, David Wayne; Ott, Kevin Curtis; Bacrania, Minesh Kantilal; Del Sesto, Rico Emilio; Gilbertson, Robert David; Muenchausen, Ross Edward; McCleskey, Thomas Mark

    2010-03-16

    An improved nanophosphor scintillator liquid comprises nanophosphor particles in a liquid matrix. The nanophosphor particles are optionally surface modified with an organic ligand. The surface modified nanophosphor particle is essentially surface charge neutral, thereby preventing agglomeration of the nanophosphor particles during dispersion in a liquid scintillator matrix. The improved nanophosphor scintillator liquid may be used in any conventional liquid scintillator application, including in a radiation detector.

  7. Pseudomonas biofilm matrix composition and niche biology

    PubMed Central

    Mann, Ethan E.; Wozniak, Daniel J.

    2014-01-01

    Biofilms are a predominant form of growth for bacteria in the environment and in the clinic. Critical for biofilm development are adherence, proliferation, and dispersion phases. Each of these stages includes reinforcement by, or modulation of, the extracellular matrix. Pseudomonas aeruginosa has been a model organism for the study of biofilm formation. Additionally, other Pseudomonas species utilize biofilm formation during plant colonization and environmental persistence. Pseudomonads produce several biofilm matrix molecules, including polysaccharides, nucleic acids, and proteins. Accessory matrix components shown to aid biofilm formation and adaptability under varying conditions are also produced by pseudomonads. Adaptation facilitated by biofilm formation allows for selection of genetic variants with unique and distinguishable colony morphology. Examples include rugose small-colony variants and wrinkly spreaders (WS), which over produce Psl/Pel or cellulose, respectively, and mucoid bacteria that over produce alginate. The well-documented emergence of these variants suggests that pseudomonads take advantage of matrix-building subpopulations conferring specific benefits for the entire population. This review will focus on various polysaccharides as well as additional Pseudomonas biofilm matrix components. Discussions will center on structure–function relationships, regulation, and the role of individual matrix molecules in niche biology. PMID:22212072

  8. Failure Mechanisms for Ceramic Matrix Textile Composites at High Temperature

    SciTech Connect

    Cox, Brian

    1999-03-01

    OAK B188 Failure Mechanisms for Ceramic Matrix Textile Composites at High Temperature. This summary refers to work done in approximately the twelve months to the present in our contract ''Failure Mechanisms for Ceramic Matrix Textile Composites at High Temperature,'' which commenced in August, 1997. Our activities have consisted mainly of measurements of creep-controlled crack growth in ceramic matrix composites (CMCS) at high temperature; imaging of deformation fields in textile CMCS; the assessment of mechanisms of damage in textile composites, especially those with through-thickness reinforcement; the formulation of models of delamination crack growth under fatigue in textile composites; analytical models of the bridging traction law for creeping fibers in a CMC at high temperature; and an analytical model of a bridging fiber tow in a textile composite.

  9. Fiber-matrix interfacial adhesion in natural fiber composites

    NASA Astrophysics Data System (ADS)

    Tran, L. Q. N.; Yuan, X. W.; Bhattacharyya, D.; Fuentes, C.; van Vuure, A. W.; Verpoest, I.

    2015-04-01

    The interface between natural fibers and thermoplastic matrices is studied, in which fiber-matrix wetting analysis and interfacial adhesion are investigated to obtain a systematic understanding of the interface. In wetting analysis, the surface energies of the fibers and the matrices are estimated using their contact angles in test liquids. Work of adhesion is calculated for each composite system. For the interface tests, transverse three point bending tests (3PBT) on unidirectional (UD) composites are performed to measure interfacial strength. X-ray photoelectron spectroscopy (XPS) characterization on the fibers is also carried out to obtain more information about the surface chemistry of the fibers. UD composites are examined to explore the correlation between the fiber-matrix interface and the final properties of the composites. The results suggest that the higher interfacial adhesion of the treated fiber composites compared to untreated fiber composites can be attributed to higher fiber-matrix physico-chemical interaction corresponding with the work of adhesion.

  10. Isothermal and nonisothermal fatigue behavior of a metal matrix composite

    NASA Technical Reports Server (NTRS)

    Gabb, T. P.; Gayda, J.; Mackay, R. A.

    1990-01-01

    The isothermal and nonisothermal fatigue resistance of a metal matrix composite (MMC) consisting of Ti-15V-3Cr-3Al-3Sn (Ti-15-3) matrix reinforced by 33 vol pct continuous SiC fibers was investigated. The fibers were nominally oriented parallel to the specimen axis. Isothermal fatigue tests were performed in air at 300 and 550 C. The MMC had good isothermal fatigue resistance at low cyclic stress, with fatigue cracks initiating from fiber-matrix interfaces and foil laminations. At high cyclic stresses, stress relaxation in the matrix reduced isothermal composite fatigue resistance at 550 C. Nonisothermal fatigue loading substantially degraded composite fatigue resistnce. This degradation was produced by a thermomechanical fatigue damage mechanism associated with the fiber-matrix interfaces.

  11. Thermal and mechanical behavior of metal matrix and ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Kennedy, John M. (Editor); Moeller, Helen H. (Editor); Johnson, W. S. (Editor)

    1990-01-01

    The present conference discusses local stresses in metal-matrix composites (MMCs) subjected to thermal and mechanical loads, the computational simulation of high-temperature MMCs' cyclic behavior, an analysis of a ceramic-matrix composite (CMC) flexure specimen, and a plasticity analysis of fibrous composite laminates under thermomechanical loads. Also discussed are a comparison of methods for determining the fiber-matrix interface frictional stresses of CMCs, the monotonic and cyclic behavior of an SiC/calcium aluminosilicate CMC, the mechanical and thermal properties of an SiC particle-reinforced Al alloy MMC, the temperature-dependent tensile and shear response of a graphite-reinforced 6061 Al-alloy MMC, the fiber/matrix interface bonding strength of MMCs, and fatigue crack growth in an Al2O3 short fiber-reinforced Al-2Mg matrix MMC.

  12. Thermal and mechanical behavior of metal matrix and ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Kennedy, John M. (Editor); Moeller, Helen H. (Editor); Johnson, W. S. (Editor)

    1990-01-01

    The present conference discusses local stresses in metal-matrix composites (MMCs) subjected to thermal and mechanical loads, the computational simulation of high-temperature MMCs' cyclic behavior, an analysis of a ceramic-matrix composite (CMC) flexure specimen, and a plasticity analysis of fibrous composite laminates under thermomechanical loads. Also discussed are a comparison of methods for determining the fiber-matrix interface frictional stresses of CMCs, the monotonic and cyclic behavior of an SiC/calcium aluminosilicate CMC, the mechanical and thermal properties of an SiC particle-reinforced Al alloy MMC, the temperature-dependent tensile and shear response of a graphite-reinforced 6061 Al-alloy MMC, the fiber/matrix interface bonding strength of MMCs, and fatigue crack growth in an Al2O3 short fiber-reinforced Al-2Mg matrix MMC.

  13. Exact Dynamic Stiffness Matrix for Composite Timoshenko Beams with Applications

    NASA Astrophysics Data System (ADS)

    Bannerjee, J. R.; Williams, F. W.

    1996-07-01

    In this paper, an exact dynamic stiffness matrix is presented for a composite beam. It includes the effects of shear deformation and rotatory inertia: i.e., it is for a composite Timoshenko beam. The theory accounts for the (material) coupling between the bending and torsional deformations which usually occurs for such beams due to the anisotropic nature of fibrous composites. An explicit analytical expression for each of the elements of the dynamic stiffness matrix is derived by rigorous use of the symbolic computing package REDUCE. It is proved that the use of such expressions leads to substantial savings in computer time when compared with the matrix inversion method. The use of this dynamic stiffness matrix to investigate the free vibration characteristics of composite beams (with or without the effects of shear deformation and/or rotatory inertia included) is demonstrated by applying the Wittrick-Williams algorithm. Numerical results for which comparative results are available in the literature are discussed.

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

    PubMed

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

    2014-01-01

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

  15. Modeling of 3-D Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Sullivan, Roy M.; Mital, Subodh K.

    2003-01-01

    Three different approaches are being pursued at the NASA Glenn Research Center to predict the nanostructural behavior of three-dimensional woven ceramic matrix composites. These are: a micromechanics-based approach using W-CEMCAN (Woven Ceramic Matrix Composite Analyzer), a laminate analogy method and a structural frame approach (based on the finite element method). All three techniques are applied to predict the thermomechanical properties of a three-dimensional woven angle interlock C/SiC composite. The properties are predicted for room temperature and 1100 C and the predicted properties are compared to measurements. General observations regarding the three approaches for three-dimensional composite modeling are discussed.

  16. High temperature metal matrix composites for future aerospace systems

    NASA Technical Reports Server (NTRS)

    Stephens, Joseph R.

    1987-01-01

    Research was conducted on metal matrix composites and intermetallic matrix composites to understand their behavior under anticipated future operating conditions envisioned for aerospace power and propulsion systems of the 21st century. Extremes in environmental conditions, high temperature, long operating lives, and cyclic conditions dictate that the test evaluations not only include laboratory testing, but simulated flight conditions. The various processing techniques employed to fabricate composites are discussed along with the basic research underway to understand the behavior of high temperature composites, and the relationship of this research to future aerospace systems.

  17. Modified Process For Formation Of Silicon Carbide Matrix Composites

    NASA Technical Reports Server (NTRS)

    Behrendt, Donald R.; Singh, Mrityunjay

    1996-01-01

    Modified version of process for making SiC-fiber/SiC-matrix composite material reduces damage to SiC (SCS-6) fibers and to carbon-rich coatings on fibers. Modification consists of addition of second polymer-infiltration-and-pyrolysis step to increase carbon content of porous matrix before infiltration with liquid silicon or silicon alloy.

  18. Modified Process For Formation Of Silicon Carbide Matrix Composites

    NASA Technical Reports Server (NTRS)

    Behrendt, Donald R.; Singh, Mrityunjay

    1996-01-01

    Modified version of process for making SiC-fiber/SiC-matrix composite material reduces damage to SiC (SCS-6) fibers and to carbon-rich coatings on fibers. Modification consists of addition of second polymer-infiltration-and-pyrolysis step to increase carbon content of porous matrix before infiltration with liquid silicon or silicon alloy.

  19. Steel-SiC Metal Matrix Composite Development

    SciTech Connect

    Smith, Don D.

    2005-07-17

    The goal of this project is to develop a method for fabricating SiC-reinforced high-strength steel. We are developing a metal-matrix composite (MMC) in which SiC fibers are be embedded within a metal matrix of steel, with adequate interfacial bonding to deliver the full benefit of the tensile strength of the SiC fibers in the composite.

  20. Thermally-driven microfracture in high temperature metal matrix composites

    NASA Technical Reports Server (NTRS)

    Mital, Subodh K.; Chamis, Christos C.

    1991-01-01

    Microfracture (fiber/matrix fracture, interphase debonding and interply delamination) in high temperature metal matrix composites (HTMMC), subjected to thermal loading, is computationally simulated. Both unidirectional and crossply SiC/Ti15 composites are evaluated for microfracture driven by thermal loads, using multicell finite element models. Results indicate that under thermal loads alone, microfracture propagation is not as sensitive as it is under mechanical loads.

  1. Damage Precursor Detection in Polymer Matrix Composites Using Novel Smart Composite Particles

    DTIC Science & Technology

    2016-09-20

    AFRL-AFOSR-VA-TR-2016-0328 Damage Precursor Detection in Polymer Matrix Composites Using Novel Smart Composite Particles Aditi Chattopadhyay ARIZONA...Matrix Composites Using Novel Smart Composite Particles 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-12-1-0331 5c.  PROGRAM ELEMENT NUMBER 61102F 6...under compressive loading. The smart material based polymer system was used to construct glass fiver reinforced composites to investigate the performance

  2. Irradiation effects in tungsten-copper laminate composite

    SciTech Connect

    Garrison, L. M.; Katoh, Yutai; Snead, Lance L.; Byun, Thak Sang; Reiser, Jens; Rieth, Michael

    2016-09-19

    Tungsten-copper laminate composite has shown promise as a structural plasma-facing component as compared to tungsten rod or plate. The present study evaluated the tungsten-copper composite after irradiation in the High Flux Isotope Reactor (HFIR) at temperatures of 410–780 °C and fast neutron fluences of 0.02–9.0 × 1025 n/m2, E > 0.1 MeV, 0.0039–1.76 displacements per atom (dpa) in tungsten. Tensile tests were performed on the composites, and the fracture surfaces were analyzed with scanning electron microscopy. Before irradiation, the tungsten layers had brittle cleavage failure, but the overall composite had 15.5% elongation at 22 °C. After only 0.0039 dpa this was reduced to 7.7% elongation, and no ductility was observed after 0.2 dpa at all irradiation temperatures when tensile tested at 22 °C. In conclusion, tor elevated temperature tensile tests after irradiation, the composite only had ductile failure at temperatures where the tungsten was delaminating or ductile.

  3. Irradiation effects in tungsten-copper laminate composite

    DOE PAGES

    Garrison, L. M.; Katoh, Yutai; Snead, Lance L.; ...

    2016-09-19

    Tungsten-copper laminate composite has shown promise as a structural plasma-facing component as compared to tungsten rod or plate. The present study evaluated the tungsten-copper composite after irradiation in the High Flux Isotope Reactor (HFIR) at temperatures of 410–780 °C and fast neutron fluences of 0.02–9.0 × 1025 n/m2, E > 0.1 MeV, 0.0039–1.76 displacements per atom (dpa) in tungsten. Tensile tests were performed on the composites, and the fracture surfaces were analyzed with scanning electron microscopy. Before irradiation, the tungsten layers had brittle cleavage failure, but the overall composite had 15.5% elongation at 22 °C. After only 0.0039 dpa thismore » was reduced to 7.7% elongation, and no ductility was observed after 0.2 dpa at all irradiation temperatures when tensile tested at 22 °C. In conclusion, tor elevated temperature tensile tests after irradiation, the composite only had ductile failure at temperatures where the tungsten was delaminating or ductile.« less

  4. Irradiation effects in tungsten-copper laminate composite

    SciTech Connect

    Garrison, L. M.; Katoh, Y.; Snead, L. L.; Byun, T. S.; Reiser, J.; Rieth, M.

    2016-12-01

    Tungsten-copper laminate composite has shown promise as a structural plasma-facing component as compared to tungsten rod or plate. The present study evaluated the tungsten-copper composite after irradiation in the High Flux Isotope Reactor (HFIR) at temperatures of 410-780°C and fast neutron fluences of 0.02-9.0×1025 n/m2, E>0.1 MeV, 0.0039-1.76 displacements per atom (dpa) in tungsten. Tensile tests were performed on the composites, and the fracture surfaces were analyzed with scanning electron microscopy. Before irradiation, the tungsten layers had brittle cleavage failure, but the overall composite had 15.5% elongation at 22°C. After only 0.0039 dpa this was reduced to 7.7% elongation, and no ductility was observed after 0.2 dpa at all irradiation temperatures when tensile tested at 22°C. For elevated temperature tensile tests after irradiation, the composite only had ductile failure at temperatures where the tungsten was delaminating or ductile.

  5. Irradiation effects in tungsten-copper laminate composite

    NASA Astrophysics Data System (ADS)

    Garrison, L. M.; Katoh, Y.; Snead, L. L.; Byun, T. S.; Reiser, J.; Rieth, M.

    2016-12-01

    Tungsten-copper laminate composite has shown promise as a structural plasma-facing component as compared to tungsten rod or plate. The present study evaluated the tungsten-copper composite after irradiation in the High Flux Isotope Reactor (HFIR) at temperatures of 410-780 °C and fast neutron fluences of 0.02-9.0 × 1025 n/m2, E > 0.1 MeV, 0.0039-1.76 displacements per atom (dpa) in tungsten. Tensile tests were performed on the composites, and the fracture surfaces were analyzed with scanning electron microscopy. Before irradiation, the tungsten layers had brittle cleavage failure, but the overall composite had 15.5% elongation at 22 °C. After only 0.0039 dpa this was reduced to 7.7% elongation, and no ductility was observed after 0.2 dpa at all irradiation temperatures when tensile tested at 22 °C. For elevated temperature tensile tests after irradiation, the composite only had ductile failure at temperatures where the tungsten was delaminating or ductile.

  6. Irradiation effects in tungsten-copper laminate composite

    SciTech Connect

    Garrison, L. M.; Katoh, Yutai; Snead, Lance L.; Byun, Thak Sang; Reiser, Jens; Rieth, Michael

    2016-09-19

    Tungsten-copper laminate composite has shown promise as a structural plasma-facing component as compared to tungsten rod or plate. The present study evaluated the tungsten-copper composite after irradiation in the High Flux Isotope Reactor (HFIR) at temperatures of 410–780 °C and fast neutron fluences of 0.02–9.0 × 1025 n/m2, E > 0.1 MeV, 0.0039–1.76 displacements per atom (dpa) in tungsten. Tensile tests were performed on the composites, and the fracture surfaces were analyzed with scanning electron microscopy. Before irradiation, the tungsten layers had brittle cleavage failure, but the overall composite had 15.5% elongation at 22 °C. After only 0.0039 dpa this was reduced to 7.7% elongation, and no ductility was observed after 0.2 dpa at all irradiation temperatures when tensile tested at 22 °C. In conclusion, tor elevated temperature tensile tests after irradiation, the composite only had ductile failure at temperatures where the tungsten was delaminating or ductile.

  7. Diffusion analysis for two-phase metal-matrix composite

    NASA Technical Reports Server (NTRS)

    Tenney, D. R.

    1976-01-01

    Diffusion controlled filament matrix interaction in a metal matrix composite, where the filaments and matrix comprise a two phase binary alloy system, was mathematically modeled. The problem of a diffusion controlled, two phase moving interface by means of a one dimensional, variable grid, finite difference technique was analyzed. Concentration dependent diffusion coefficients and equilibrium solubility limits were used, and the change in filament diameter and compositional changes in the matrix were calculated as a function of exposure time at elevated temperatures. With the tungsten nickel (W-Ni) system as a model composite system, unidirectional composites containing from 0.06 to 0.44 initial filament volume fraction were modeled. Compositional changes in the matrix were calculated by superposition of the contributions from neighboring filaments. Alternate methods for determining compositional changes between first and second nearest neighbor filaments were also considered. The results show the relative importance of filament volume fraction, filament diameter, exposure temperature, and exposure time as they affect the rate and extent of filament matrix interaction.

  8. Analysis of thermal mechanical fatigue in titanium matrix composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. Steven; Mirdamadi, Massoud

    1993-01-01

    Titanium metal matrix composites are being evaluated for structural applications on advanced hypersonic vehicles. These composites are reinforced with ceramic fibers such as silicon carbide, SCS-6. This combination of matrix and fiber results in a high stiffness, high strength composite that has good retention of properties even at elevated temperatures. However, significant thermal stresses are developed within the composite between the fiber and the matrix due to the difference in their respective coefficients of thermal expansion. In addition to the internal stresses that are generated due to thermal cycling, the overall laminate will be subjected to considerable mechanical loads during the thermal cycling. In order to develop life prediction methodology, one must be able to predict the stresses and strains that occur in the composite's constituents during the complex loading. Thus the purpose is to describe such an analytical tool, VISCOPLY.

  9. Analysis of thermal mechanical fatigue in titanium matrix composites

    NASA Astrophysics Data System (ADS)

    Johnson, W. Steven; Mirdamadi, Massoud

    1993-10-01

    Titanium metal matrix composites are being evaluated for structural applications on advanced hypersonic vehicles. These composites are reinforced with ceramic fibers such as silicon carbide, SCS-6. This combination of matrix and fiber results in a high stiffness, high strength composite that has good retention of properties even at elevated temperatures. However, significant thermal stresses are developed within the composite between the fiber and the matrix due to the difference in their respective coefficients of thermal expansion. In addition to the internal stresses that are generated due to thermal cycling, the overall laminate will be subjected to considerable mechanical loads during the thermal cycling. In order to develop life prediction methodology, one must be able to predict the stresses and strains that occur in the composite's constituents during the complex loading. Thus the purpose is to describe such an analytical tool, VISCOPLY.

  10. Irradiation-induced composition patterns in binary solid solutions

    SciTech Connect

    Dubey, Santosh; El-Azab, Anter

    2013-09-28

    A theoretical/computational model for the irradiation-driven compositional instabilities in binary solid solutions has been developed. The model is suitable for investigating the behavior of structural alloys and metallic nuclear fuels in a reactor environment as well as the response of alloy thin films to ion beam irradiation. The model is based on a set of reaction-diffusion equations for the dynamics of vacancies, interstitials, and lattice atoms under irradiation. The dynamics of these species includes the stochastic generation of defects by collision cascades as well as the defect reactions and diffusion. The atomic fluxes in this model are derived based on the transitions of lattice defects. The set of reaction-diffusion equations are stiff, hence a stiffly stable method, also known as the Gear method, has been used to numerically approximate the equations. For the Cu-Au alloy in the solid solution regime, the model results demonstrate the formation of compositional patterns under high-temperature particle irradiation, with Fourier space properties (Fourier spectrum, average wavelength, and wavevector) depending on the cascade damage characteristics, average composition, and irradiation temperature.

  11. Light weight polymer matrix composite material

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J. (Inventor); Lowell, Carl E. (Inventor)

    1991-01-01

    A graphite fiber reinforced polymer matrix is layed up, cured, and thermally aged at about 750.degree. F. in the presence of an inert gas. The heat treatment improves the structural integrity and alters the electrical conductivity of the materials. In the preferred embodiment PMR-15 polyimides and Celion-6000 graphite fibers are used.

  12. Light weight polymer matrix composite material

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J. (Inventor); Lowell, Carl E. (Inventor)

    1988-01-01

    A graphite fiber reinforced polymer matrix is layed up, cured, and thermally aged at about 750 F in the presence of an inert gas. The heat treatment improves the structural integrity and alters the electrical conductivity of the materials. In the preferred embodiment PMR-15 polyimides and Celion-6000 graphite fibers are used.

  13. Research on graphite reinforced glass matrix composites

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.; Prewo, K. M.; Thompson, E. R.

    1978-01-01

    A composite that can be used at temperatures up to 875 K with mechanical properties equal or superior to graphite fiber reinforced epoxy composites is presented. The composite system consist of graphite fiber, uniaxially or biaxially, reinforced borosilicate glass. The mechanical and thermal properties of such a graphite fiber reinforced glass composite are described, and the system is shown to offer promise as a high performance structural material. Specific properties that were measured were: a modified borosilicate glass uniaxially reinforced by Hercules HMS graphite fiber has a three-point flexural strength of 1030 MPa, a four-point flexural strength of 964 MPa, an elastic modulus of 199 GPa and a failure strain of 0.0052. The preparation and properties of similar composites with Hercules HTS, Celanese DG-102, Thornel 300 and Thornel Pitch graphite fibers are also described.

  14. Calorimetric study of extracellular tissue matrix degradation and instability after gamma irradiation.

    PubMed

    Sun, Wendell Q; Leung, Patrick

    2008-07-01

    Native extracellular tissue matrix (ECM) is increasingly used for tissue repair and regeneration. The kinetics of gamma irradiation damage on human dermis ECM was studied by differential scanning calorimetry (DSC). Dermis ECM was irradiated at a low-dose rate of 0.23 kGy h(-1) in order to study the progression of ECM damage as the gamma dose increased from 0 to 32 kGy. The study showed that the effect of gamma irradiation above 2 kGy was predominantly peptide chain scission. As the gamma dose increased, the stability of irradiated ECM decreased further, and multiple ECM domains of different stability were detected. Even a moderate gamma dose (7-12 kGy) could decrease the onset denaturation temperature of ECM to below body temperature. DSC analysis also showed partial and spontaneous protein denaturation in gamma-irradiated, rehydrated ECM at 37 degrees C. In vitro rehydration tests confirmed that a significant fraction of the irradiated ECM disintegrated into minute ECM fragments at 37 degrees C, although the irradiated ECM appeared to be normal at 4 degrees C and room temperature. DSC data were correlated well to effects of gamma irradiation on ECM microstructure, mechanical property and in vitro cell response reported earlier by us. A model was presented to describe the kinetics of gamma-irradiation-induced alterations of tissue ECM properties.

  15. Precipitation hardening of a novel aluminum matrix composite

    SciTech Connect

    Suarez, Oscar Marcelo

    2002-09-15

    Deterioration of properties in cast aluminum matrix composites (AMCs) due to matrix/reinforcement chemical reactions is absent when AlB{sub 2} particles are used as reinforcements. This communication reports the fabrication of a heat-treatable AMC reinforced with borides. Final hardness values can be adjusted by solution and precipitation, which harden the composite. Evolution of the microstructure is concisely presented as observed by secondary electron microscopy. Precipitation hardening of the aluminum matrix, observed by microhardness measurements, has been corroborated by differential thermal analysis.

  16. Fatigue of continuous fiber reinforced titanium matrix composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1991-01-01

    Several lay-ups of SCS-6/Ti-15-3 composites were investigated. Static and fatigue tests were conducted for both notched and unnotched specimens at room and elevated temperatures. Test results indicated that the stress in the 0 fibers is the controlling factor in fatigue life. The static and fatigue strength of these materials is shown to be dependent on the level of residual stresses and the fiber/ matrix interfacial strength. Fatigue tests of notched specimens showed that cracks can initiate and grow many fiber spacings in the matrix material without breaking fibers. These matrix cracks can significantly reduce the residual strength of notched composite.

  17. Comparison Of Models Of Metal-Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bigelow, C. A.; Johnson, W. S.; Naik, R. A.

    1994-01-01

    Report presents comparative review of four mathematical models of micromechanical behaviors of fiber/metal-matrix composite materials. Models differ in various details, all based on properties of fiber and matrix constituent materials, all involve square arrays of fibers continuous and parallel and all assume complete bonding between constituents. Computer programs implementing models used to predict properties and stress-vs.-strain behaviors of unidirectional- and cross-ply laminated composites made of boron fibers in aluminum matrices and silicon carbide fibers in titanium matrices. Stresses in fiber and matrix constituent materials also predicted.

  18. Stable Boron Nitride Interphases for Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.

    1999-01-01

    Ceramic matrix composites (CMC's) require strong fibers for good toughness and weak interphases so that cracks which are formed in the matrix debond and deflect around the fibers. If the fibers are strongly bonded to the matrix, CMC's behave like monolithic ceramics (e.g., a ceramic coffee cup), and when subjected to mechanical loads that induce cracking, such CMC's fail catastrophically. Since CMC's are being developed for high temperature corrosive environments such as the combustor liner for advanced High Speed Civil Transport aircraft, the interphases need to be able to withstand the environment when the matrix cracks.

  19. Experimental investigations on mechanical behavior of aluminium metal matrix composites

    NASA Astrophysics Data System (ADS)

    Rajesh, A. M.; Kaleemulla, Mohammed

    2016-09-01

    Today we are widely using aluminium based metal matrix composite for structural, aerospace, marine and automobile applications for its light weight, high strength and low production cost. The purpose of designing metal matrix composite is to add the desirable attributes of metals and ceramics to the base metal. In this study we developed aluminium metal matrix hybrid composite by reinforced Aluminium7075 alloy with silicon carbide (SiC) and aluminium oxide (alumina) by method of stir casting. This technique is less expensive and very effective. The Hardness test and Wear test were performed on the specimens which are prepared by stir casting techniques. The result reveals that the addition of silicon carbide and alumina particles in aluminium matrix improves the mechanical properties.

  20. Strain Rate Dependent Modeling of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1999-01-01

    A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. Strain rate dependent inelastic constitutive equations have been developed to model the polymer matrix, and have been incorporated into a micromechanics approach to analyze polymer matrix composites. The Hashin failure criterion has been implemented within the micromechanics results to predict ply failure strengths. The deformation model has been implemented within LS-DYNA, a commercially available transient dynamic finite element code. The deformation response and ply failure stresses for the representative polymer matrix composite AS4/PEEK have been predicted for a variety of fiber orientations and strain rates. The predicted results compare favorably to experimentally obtained values.

  1. Mechanics of Matrix Cracking in Brittle-Matrix Fibre-Reinforced Composites

    NASA Astrophysics Data System (ADS)

    McCartney, L. N.

    1987-02-01

    Energy-balance calculations for a continuum model of cracking in a uniaxially fibre-reinforced composite having a brittle matrix are presented. It is assumed that the fibres are strong enough to remain intact when the matrix cracks across the entire cross section of the composite. By equating the energy availability for the cracking of continuum and discrete fibre models it is shown how the crack boundary condition relating fibre stress to crack opening must be selected. It is confirmed that the Griffith fracture criterion is valid for matrix cracking in composites. By considering the energy balance of long cracks it is shown that the limiting value of the stress intensity factor is independent of crack length and that it predicts a matrix-cracking strain that is consistent with the known result. An improved numerical method is described for solving a crack problem arising from the study of the cracking of brittle-matrix composites. Numerical results of high accuracy are obtained, which show how the cracking stress is related to the size of a pre-existing defect. Of special significance is the prediction of the correct threshold stress (i.e. matrix-cracking stress) below which matrix cracking is impossible no matter how large the pre-existing defect.

  2. Fatigue damage criteria - Matrix, fibers and interfaces of continuous fiber reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1988-01-01

    Continuous fiber reinforced metal matrix composites (MMC) are projected for use in high temperature, stiffness critical parts that will be subjected to cyclic loadings. Depending on the relative fatigue behavior of the fiber and matrix, and the interface properties, the failure modes of MMC can be grouped into four catagories: (1) matrix dominated, (2) fiber dominated, (3) self-similar damage growth, and (4) fiber/matrix interfacial failures. These four types of damage are discussed and illustrated by examples. The emphasis is on the fatigue of unnotched laminates.

  3. Fe and O EELS Studies of Ion Irradiated Murchison CM2 Carbonaceous Chondrite Matrix

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Christofferson, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.

    2015-01-01

    Introduction: The physical and chemical response of hydrated carbonaceous chondrite materials to space weathering processes is poorly understood. Improving this understanding is a key part of establishing how regoliths on primitive carbonaceous asteroids respond to space weathering processes, knowledge that supports future sample return missions (Hayabusa 2 and OSIRISREx) that are targeting objects of this type. We previously reported on He+ irradiation of Murchison matrix and showed that the irradiation resulted in amorphization of the matrix phyllosilicates, loss of OH, and surface vesiculation. Here, we report electron energy-loss spectroscopy (EELS) measurements of the irradiated material with emphasis on the Fe and O speciation. Sample and Methods: A polished thin section of the Murchison CM2 carbonaceous chondrite was irradiated with 4 kilovolts He(+) (normal incidence) to a total dose of 1 x 10(exp 18) He(+) per square centimeter. We extracted thin sections from both irradiated and unirradiated regions in matrix using focused ion beam (FIB) techniques with electron beam deposition for the protective carbon strap to minimize surface damage artifacts from the FIB milling. The FIB sections were analyzed using a JEOL 2500SE scanning and transmission electron microscope (STEM) equipped with a Gatan Tridiem imaging filter. EELS spectra were collected from 50 nanometer diameter regions with an energy resolution of 0.7 electronvolts FWHM at the zero loss. EELS spectra were collected at low electron doses to minimize possible artifacts from electron-beam irradiation damage. Results and Discussion: Fe L (sub 2,3) EELS spectra from matrix phyllosilicates in CM chondrites show mixed Fe(2+)/Fe(3+) oxidation states with Fe(3+)/Sigma Fe approximately 0.5. Fe L(sub 2,3) spectra from the irradiated/ amorphized matrix phyllosilicates show higher Fe(2+)/Fe(3+) ratios compared to spectra obtained from pristine material at depths beyond the implantation/amorphization layer. We

  4. SLPMC- Self Lubricating Polymer Matrix Composites

    NASA Astrophysics Data System (ADS)

    Macho, C.; Merstallinger, A.; Brodowski-Hanemann, G.; Palladino, M.; Pambaguian, L.

    2013-09-01

    The paper is surveying the current state of knowledge and results of the ESA-project "SLPMC" on a polymer composite based on PTFE. The two targets of this project are to investigate lubrication mechanisms in PTFE-based composites under tribological conditions relevant to space applications (air, nitrogen, vacuum). Secondly, to develop a new composite to fulfill future needs by space applications. Hence, in the frame of this project several new composites based on PTFE and hard fillers were defined, procured and tested on material level. Results are compared to reference materials being currently use.This paper focuses on tribological results derived by pin-on-disc tests. (Later on testing on ball bearing and plain bearing are foreseen.) The influences of parameters like load, speed, atmosphere and temperature are discussed and compared to other already known materials.

  5. Properties of Organic Matrix Short Fiber Composites

    DTIC Science & Technology

    1982-02-01

    reinforced SMC composites ( Owens Corning Fiberglas System) ............... ........................ ... 37 4 Schematic of process used to manufacture XMC...71 Vi F, viii. TLST OF TABLES TABLEPAE 1 Material formulations and densitius of SMC materials (PPG-PPG Industries, OFC- Owens Corning Fiberglas) (refs...Composite Materials, 14 (April 1980) , 142-154. 16 ,. Table 1. Material formulations and densities of SMC materials. (PPG-PPG Industries, OFC- Owens

  6. Joining and fabrication of metal-matrix composite materials

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Wiant, H. R.; Bales, T. T.

    1975-01-01

    Manufacturing technology associated with developing fabrication processes to incorporate metal-matrix composites into flight hardware is studied. The joining of composite to itself and to titanium by innovative brazing, diffusion bonding, and adhesive bonding is examined. The effects of the fabrication processes on the material properties and their influence on the design of YF-12 wing panels are discussed.

  7. A tough high performance composite matrix

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor); Johnston, Norman J. (Inventor)

    1992-01-01

    This invention is a semi-interpenetrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide. An improved high temperature matrix resin is provided which is capable of performing in the 200 to 300 C range. This resin has significantly improved toughness and microcracking resistance, excellent processability, mechanical performance and moisture and solvent resistances.

  8. Metal matrix composite structural panel construction

    NASA Technical Reports Server (NTRS)

    Mcwithey, R. R.; Royster, D. M. (Inventor); Bales, T. T.

    1983-01-01

    Lightweight capped honeycomb stiffeners for use in fabricating metal or metal/matrix exterior structural panels on aerospace type vehicles and the process for fabricating same are disclosed. The stiffener stringers are formed in sheets, cut to the desired width and length and brazed in spaced relationship to a skin with the honeycomb material serving directly as the required lightweight stiffeners and not requiring separate metal encasement for the exposed honeycomb cells.

  9. Plasma Joining of Metal Matrix Composites.

    DTIC Science & Technology

    1986-02-01

    Al4C3 . 4~ 3* The reaction under consideration is: 3 SiC (s) + 4 Al (1) AI4 C3 (s) + 3 Si (dissolved in liquid Al) (1) The equilibrium activity of Si...matrix to form Al4C3 . Loss of SiC by such reaction is about 10% at 2300 K for in-plasma residence time of 10 second, if the rate limiting factor is the

  10. Organic polymeric matrix resins for composites

    SciTech Connect

    Arnold-McKenna, C.A.

    1993-12-31

    This talk will highlight the basic chemistry of important representative polymeric matrices for composites and discuss some composite applications, particularly for advanced composites. The advanced composites market is primarily within the aerospace industry, with recreational, industrial, and automotive applications accounting for the remainder. As the large military component of the aerospace market declines, however, penetration into more cost-sensitive markets such as automotive and building and construction is important. Polymers that are used for composite applications may be either thermosetting or thermoplastic, and each offers advantages and disadvantages. Widespread use of thermoplastics, however, requires processability improvements. A major research thrust for thermosetting resins is to improve toughness; an important approach involves the incorporation of functionalized and non-functionalized thermoplastic additives, such as poly(arylene ether)s. A wide variety of technologies for polymeric composites are being explored in federal laboratories and the private sector. Some applications of these technologies include advanced aircraft, missiles, and spacecraft ; wind turbines; light-weight, tough aircraft and automobile structures; waste storage filter containers; and dental restorations and implants.

  11. Finite element analysis of metal matrix composite blade

    NASA Astrophysics Data System (ADS)

    Isai Thamizh, R.; Velmurugan, R.; Jayagandhan, R.

    2016-10-01

    In this work, compressor rotor blade of a gas turbine engine has been analyzed for stress, maximum displacement and natural frequency using ANSYS software for determining its failure strength by simulating the actual service conditions. Static stress analysis and modal analysis have been carried out using Ti-6Al-4V alloy, which is currently used in compressor blade. The results are compared with those obtained using Ti matrix composites reinforced with SiC. The advantages of using metal matrix composites in the gas turbine compressor blades are investigated. From the analyses carried out, it seems that composite rotor blades have lesser mass, lesser tip displacement and lower maximum stress values.

  12. Advanced composites: Fabrication processes for selected resin matrix materials

    NASA Technical Reports Server (NTRS)

    Welhart, E. K.

    1976-01-01

    This design note is based on present state of the art for epoxy and polyimide matrix composite fabrication technology. Boron/epoxy and polyimide and graphite/epoxy and polyimide structural parts can be successfully fabricated. Fabrication cycles for polyimide matrix composites have been shortened to near epoxy cycle times. Nondestructive testing has proven useful in detecting defects and anomalies in composite structure elements. Fabrication methods and tooling materials are discussed along with the advantages and disadvantages of different tooling materials. Types of honeycomb core, material costs and fabrication methods are shown in table form for comparison. Fabrication limits based on tooling size, pressure capabilities and various machining operations are also discussed.

  13. On incompressibility of a matrix in naturally occurring composites

    NASA Astrophysics Data System (ADS)

    Gorbatikh, Larissa; Pingle, Pawan

    2007-12-01

    The work illustrates that a soft matrix, which has the Poisson ratio close to 0.5 and is reinforced with a rigid-line inclusion, possesses an interesting behavior at the inclusion/matrix interface. It experiences a hydrostatic stress state and behaves as an incompressible fluid under longitudinal and transverse loads. The stress singularities are eliminated ahead of the inclusion tips, and when interface defects are formed, their effect on the composite compliance is minimal. These observations have far reaching applications when one is interested in mechanisms of multifunctional property improvement of composites (such as toughness and stiffness) learned from naturally occurring composites.

  14. Advanced Ceramic Matrix Composites with Multifunctional and Hybrid Structures

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay; Morscher, Gregory N.

    2004-01-01

    Ceramic matrix composites are leading candidate materials for a number of applications in aeronautics, space, energy, and nuclear industries. Potential composite applications differ in their requirements for thickness. For example, many space applications such as "nozzle ramps" or "heat exchangers" require very thin (< 1 mm) structures whereas turbine blades would require very thick parts (> or = 1 cm). Little is known about the effect of thickness on stress-strain behavior or the elevated temperature tensile properties controlled by oxidation diffusion. In this study, composites consisting of woven Hi-Nicalon (trademark) fibers a carbon interphase and CVI SiC matrix were fabricated with different numbers of plies and thicknesses. The effect of thickness on matrix crack formation, matrix crack growth and diffusion kinetics will be discussed. In another approach, hybrid fiber-lay up concepts have been utilized to "alloy" desirable properties of different fiber types for mechanical properties, thermal stress management, and oxidation resistance. Such an approach has potential for the C(sub I)-SiC and SiC(sub f)-SiC composite systems. CVI SiC matrix composites with different stacking sequences of woven C fiber (T300) layers and woven SiC fiber (Hi-Nicalon (trademark)) layers were fabricated. The results will be compared to standard C fiber reinforced CVI SiC matrix and Hi-Nicalon reinforced CVI SiC matrix composites. In addition, shear properties of these composites at different temperatures will also be presented. Other design and implementation issues will be discussed along with advantages and benefits of using these materials for various components in high temperature applications.

  15. Graphene scavenges free radicals to synergistically enhance structural properties in a gamma-irradiated polyethylene composite through enhanced interfacial interactions.

    PubMed

    Kolanthai, Elayaraja; Bose, Suryasarathi; Bhagyashree, K S; Bhat, S V; Asokan, K; Kanjilal, D; Chatterjee, Kaushik

    2015-09-21

    A unique strategy for scavenging free radicals in situ on exposure to gamma irradiation in polyethylene (PE) nanocomposites is presented. Blends of ultra-high molecular weight PE and linear low-density PE (PEB) and their nanocomposites with graphene (GPEB) were prepared by melt mixing to develop materials for biomedical implants. The effect of gamma irradiation on the microstructure and mechanical properties was systematically investigated. The neat blend and the nanocomposite were subjected to gamma-ray irradiation in order to improve the interfacial adhesion between PE and graphene sheets. Structural and thermal characterization revealed that irradiation induced crosslinking and increased the crystallinity of the polymer blend. The presence of graphene further enhanced the crystallinity via crosslinks between the polymer matrix and the filler on irradiation. Graphene was found to scavenge free radicals as confirmed by electron paramagnetic resonance spectroscopy. Irradiation of graphene-containing polymer composites resulted in the largest increase in modulus and hardness compared to either irradiation or addition of graphene to PEB alone. This study provides new insight into the role of graphene in polymer matrices during irradiation and suggests that irradiated graphene-polymer composites could emerge as promising materials for use as articulating surfaces in biomedical implants.

  16. Thermal fatigue of ceramic fiber glass matrix composites

    SciTech Connect

    Zawada, L.P.; Wetherhold, R.C.

    1989-10-01

    The thermal fatigue (TF) of ceramic matrix composites (CMC) introduces stresses within the composite due to the inevitable thermal expansion mismatch of fiber and matrix; this will affect the lifetime and dimensional stability of the composite. A Nicalon/glass composite has been subjected to rapid, controlled TF from 250-700 C and 250-800 C under no load and dead load conditions in order to illustrate a variety of elastic and inelastic cyclic strain conditions. After TF, the surfaces of the composites were characterized using SEM for evidence of thermal damage and microcracking. The composites were then tested for flexural modulus and strength. Results from the mechanical properties tests are present and correlated with observed thermal degradation. 7 refs.

  17. Fiber shape effects on metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Brown, H. C.; Lee, H.-J.

    1992-01-01

    The effects of different fiber shapes on the behavior of metal matrix composites is computationally simulated. A three-dimensional finite element model consisting of a group of nine unidirectional fibers in a three by three unit cell array of a SiC/Ti-15-3 metal matrix composite is used in the analysis. The model is employed to represent five fiber shapes that include a circle, an ellipse, a kidney, and two different cross shapes. The distribution of stresses and the composite material properties, such as moduli, coefficients of thermal expansion, and Poisson's ratios, are obtained from the finite element analysis using the various fiber shapes. Comparisons of these results are used to determine the sensitivity of the composite behavior to the different fiber shapes. In general, fiber dominated properties are not affected by fiber geometry and matrix dominated properties are only moderately affected.

  18. Fiber shape effects on metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Brown, H. C.; Lee, H.-J.

    1992-01-01

    The effects of different fiber shapes on the behavior of metal matrix composites is computationally simulated. A three-dimensional finite element model consisting of a group of nine unidirectional fibers in a three by three unit cell array of a SiC/Ti-15-3 metal matrix composite is used in the analysis. The model is employed to represent five fiber shapes that include a circle, an ellipse, a kidney, and two different cross shapes. The distribution of stresses and the composite material properties, such as moduli, coefficients of thermal expansion, and Poisson's ratios, are obtained from the finite element analysis using the various fiber shapes. Comparisons of these results are used to determine the sensitivity of the composite behavior to the different fiber shapes. In general, fiber dominated properties are not affected by fiber geometry and matrix dominated properties are only moderately affected.

  19. Damage evolution in uniaxial silicon carbide fiber-reinforced titanium matrix composites

    NASA Astrophysics Data System (ADS)

    Hanan, Jay Clarke

    Fiber fractures initiate damage zones ultimately determining the strength and lifetime of metal matrix composites (MMCs). The evolution of damage in a MMC comprising a row of unidirectional SiC fibers (32 vol.%) surrounded by a Ti matrix was examined using X-ray microdiffraction (gym beam size) and macrodiffraction (mm beam size). A comparison of high-energy X-ray diffraction (XRD) techniques including a powerful two-dimensional XRD method capable of obtaining powder averaged strains from a small number of grains is presented (HEmuXRD2). Using macrodiffraction, the bulk residual strain in the composite was determined against a true strain-free reference. In addition, the bulk in situ response of both the fiber reinforcement and the matrix to tensile stress was observed and compared to a three-dimensional finite element model. Using microdiffraction, multiple strain maps including both phases were collected in situ before, during, and after the application of tensile stress, providing an unprecedented detailed picture of the micromechanical behavior in the laminate metal matrix composite. Finally, the elastic axial strains were compared to predictions from a modified shear lag model, which unlike other shear lag models, considers the elastic response of both constituents. The strains showed excellent correlation with the model. The results confirmed, for the first time, both the need and validity of this new model specifically developed for large scale multifracture and damage evolution simulations of metal matrix composites. The results also provided unprecedented insight for the model, revealing the necessity of incorporating such factors as plasticity of the matrix, residual stress in the composite, and selection of the load sharing parameter. The irradiation of a small number of grains provided strain measurements comparable to a continuum mechanical state in the material. Along the fiber axes, thermal residual stresses of 740 MPa (fibers) and +350 MPa (matrix

  20. Characterization the microstructure and defects of matrix graphite irradiated with Xe ions

    NASA Astrophysics Data System (ADS)

    Xu, H. X.; Lin, J.; Li, J. J.; Zhu, Z. Y.; Zeng, G. L.; Liu, J. D.; Gu, B. C.; Liu, B.

    2017-09-01

    The matrix graphite of pebble fuel elements was irradiated with 1 MeV Xe ions at room temperature to fluences of 5.8 × 1014 ions/cm2 and 2.9 × 1015 ions/cm2, respectively. The microstructure and defects of matrix graphite samples were characterized by using scanning electron microscopy (SEM), Raman spectroscopy and slow positron beam techniques. The SEM result reveals that hundred-nanometer sized pores appear at the surface after irradiation and the density of pore increases with fluence. Raman results show that D peak (1350 cm-1) and G peak (1580 cm-1) are broadened after irradiation. In addition, the G peak position shifts from 1580 cm-1 to 1560 cm-1 with the linewidth increases from 21 cm-1 to 132 cm-1, corresponding to the increase in bond-angle disorder as the matrix graphite transforms from microcrystalline to amorphous carbon(a-C). The slow positron beam study shows that the defects-trapped positron S parameter increases with fluence, suggesting that the vacancy-type defects concentration or size of open volume defects increases. The analysis of Raman and slow positron beam consistently conclude that the reason for the phase transition after irradiation is the increase in irradiation-induced vacancy defects accompanied by the overlap of disordered regions.

  1. Probabilistic Thermomechanical Fatigue of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    1997-01-01

    Traditional computational approaches for predicting the life and long-term behavior of materials rely on empirical data and are neither generic nor unique in nature. Also, those approaches are not easy to implement in a design procedure in an effective, integrated manner. The focus of ongoing research at the NASA Lewis Research Center has been to develop advanced integrated computational methods and related computer codes for a complete reliability-based assessment of composite structures. These methods - which account for uncertainties in all the constituent properties, fabrication process variables, and loads to predict probabilistic micromechanics, ply, laminate, and structural responses - have already been implemented in the Integrated Probabilistic Assessment of Composite Structures (IPACS) computer code. The main objective of this evaluation is to illustrate the effectiveness of the methodology to predict the long-term behavior of composites under combined mechanical and thermal cyclic loading conditions.

  2. Corrosion Resistance of Metal Matrix Composites.

    DTIC Science & Technology

    1992-10-01

    fibers was found to reduce the corrosion rate by a factor of twenty in NaC1 solutions. Al4C3 hydrolysis was not observed on the time scale of the...on the anodic polarization behavior of the G/Al MMCs with A14C3 contents measured by gas chromatography. 2.1.1 Al4C3 at the Fiber-Matrix Interface The...and Al4C3 content were not as significant in affecting the passive current density as was the type of graphite fiber used in processing the

  3. Cement Paste Matrix Composite Materials Center.

    DTIC Science & Technology

    1987-10-01

    not being fully funded. The projects are: The Effect of Chemical Doping and Phase Transformations on Microstructural Development of Dicalcium Silicate...Ceramics Alumina phosphate cements S. Granick* MSE -Ceramics Polymer-solid interfaces J. Homeny* MSE+-Ceramics Fracture of composites R. J. Kirkpatrick

  4. Ballistic penetration response of intermetallic matrix composites

    SciTech Connect

    Kumar, K.S.; DiPietro, M.S. )

    1995-03-01

    Titanium aluminides and their composites exhibit about the same density as alumina, are tougher and can be produced by conventional casting and powder metallurgy techniques; further, they can be ground and machined more easily than alumina and lend themselves to better microstructural manipulation via heat treatments. Graded composite tiles with a high refractory reinforcement content on the outside and a lower amount on the inside may provide the desired abrasion resistance and toughness to effectively stop an incoming projectile. Likewise, alternating layers of hard and soft materials (e.g. Ti foils and TiAl) suitably graded in their spacings can serve as an effective armor tile. Testing of these materials gave the following conclusions: (1) Titanium aluminide composites are comparable to alumina in ballistic penetration resistance (for BS-41 and M-61 AP threats, and from the work of Chin and Woolsey, to long-rod penetrators) with perhaps improved resistance to shattering. (2) Incorporation of a residual compressive stress in the titanium aluminide composite tile significantly improved its penetration resistance. This concept could be utilized to decrease the required minimum tile thickness and hence, overall system weight.

  5. Building up graphene-based conductive polymer composite thin films using reduced graphene oxide prepared by γ-ray irradiation.

    PubMed

    Xie, Siyuan; Zhang, Bowu; Wang, Chunlei; Wang, Ziqiang; Li, Linfan; Li, Jingye

    2013-01-01

    In this paper, reduced graphene oxide (RGO) was prepared by means of γ -ray irradiation of graphene oxide (GO) in a water/ethanol mix solution, and we investigated the influence of reaction parameters, including ethanol concentration, absorbed dose, and dose rate during the irradiation. Due to the good dispersibility of the RGO in the mix solution, we built up flexible and conductive composite films based on the RGO and polymeric matrix through facile vacuum filtration and polymer coating. The electrical and optical properties of the obtained composite films were tested, showing good electrical conductivity with visible transmittance but strong ultraviolet absorbance.

  6. Building up Graphene-Based Conductive Polymer Composite Thin Films Using Reduced Graphene Oxide Prepared by γ-Ray Irradiation

    PubMed Central

    Xie, Siyuan; Zhang, Bowu; Wang, Chunlei; Wang, Ziqiang; Li, Linfan; Li, Jingye

    2013-01-01

    In this paper, reduced graphene oxide (RGO) was prepared by means of γ-ray irradiation of graphene oxide (GO) in a water/ethanol mix solution, and we investigated the influence of reaction parameters, including ethanol concentration, absorbed dose, and dose rate during the irradiation. Due to the good dispersibility of the RGO in the mix solution, we built up flexible and conductive composite films based on the RGO and polymeric matrix through facile vacuum filtration and polymer coating. The electrical and optical properties of the obtained composite films were tested, showing good electrical conductivity with visible transmittance but strong ultraviolet absorbance. PMID:24170985

  7. Transverse fracture and fiber/matrix interface characteristics of hybrid ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Haug, Stephen Berry

    Ceramic Matrix Composites (CMCs) represent an attractive class of engineering materials for use in high temperature, high wear and corrosive environments. Much effort has been made to ascertain and improve the strength and fracture characteristics of these materials. Approaches that have received a significant amount of attention include enhancing a ceramic material's mechanical properties through the use of continuous fiber reinforcement; fine, randomly dispersed discontinuous fiber (or whisker) reinforcement; and a hybrid combination of both continuous and discontinuous fibers. This dissertation addresses two important aspects of determining and improving the strength and toughness of CMCs and is comprised of three research papers that have been prepared for journal publication. The first paper, "Transverse Fracture Toughness of Unidirectional Continuous Fiber and Hybrid Ceramic Matrix Composites" provides the results of three-point chevron-notched-beam fracture toughness testing and demonstrates a significant improvement in transverse fracture toughness can be obtained through the use of hybrid fiber reinforcements. The second paper, "A Tensile Testing Method for Ceramic Matrix Composites" presents a novel approach to testing small brittle material specimens using conventional testing equipment with minimal specialized fixture components. The third paper, "Fiber/Matrix Interface Properties of Hybrid Ceramic Matrix Composites", presents a method of determining the characteristics of the fiber/matrix interface of a continuous fiber reinforced CMC and a related hybrid CMC reinforced by both continuous fibers and finely dispersed whiskers using a multiple fiber pullout technique.

  8. Time-dependent deformation of titanium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Bigelow, C. A.; Bahei-El-din, Y. A.; Mirdamadi, M.

    1995-01-01

    A three-dimensional finite element program called VISCOPAC was developed and used to conduct a micromechanics analysis of titanium metal matrix composites. The VISCOPAC program uses a modified Eisenberg-Yen thermo-viscoplastic constitutive model to predict matrix behavior under thermomechanical fatigue loading. The analysis incorporated temperature-dependent elastic properties in the fiber and temperature-dependent viscoplastic properties in the matrix. The material model was described and the necessary material constants were determined experimentally. Fiber-matrix interfacial behavior was analyzed using a discrete fiber-matrix model. The thermal residual stresses due to the fabrication cycle were predicted with a failed interface, The failed interface resulted in lower thermal residual stresses in the matrix and fiber. Stresses due to a uniform transverse load were calculated at two temperatures, room temperature and an elevated temperature of 650 C. At both temperatures, a large stress concentration was calculated when the interface had failed. The results indicate the importance of accuracy accounting for fiber-matrix interface failure and the need for a micromechanics-based analytical technique to understand and predict the behavior of titanium metal matrix composites.

  9. Acoustic emission as a screening tool for ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Ojard, Greg; Goberman, Dan; Holowczak, John

    2017-02-01

    Ceramic matrix composites are composite materials with ceramic fibers in a high temperature matrix of ceramic or glass-ceramic. This emerging class of materials is viewed as enabling for efficiency improvements in many energy conversion systems. The key controlling property of ceramic matrix composites is a relatively weak interface between the matrix and the fiber that aids crack deflection and fiber pullout resulting in greatly increased toughness over monolithic ceramics. United Technologies Research Center has been investigating glass-ceramic composite systems as a tool to understand processing effects on material performance related to the performance of the weak interface. Changes in the interface have been shown to affect the mechanical performance observed in flexural testing and subsequent microstructural investigations have confirmed the performance (or lack thereof) of the interface coating. Recently, the addition of acoustic emission testing during flexural testing has aided the understanding of the characteristics of the interface and its performance. The acoustic emission onset stress changes with strength and toughness and this could be a quality tool in screening the material before further development and use. The results of testing and analysis will be shown and additional material from other ceramic matrix composite systems may be included to show trends.

  10. Modeling the Mechanical Behavior of Ceramic Matrix Composite Materials

    NASA Technical Reports Server (NTRS)

    Jordan, William

    1998-01-01

    Ceramic matrix composites are ceramic materials, such as SiC, that have been reinforced by high strength fibers, such as carbon. Designers are interested in using ceramic matrix composites because they have the capability of withstanding significant loads while at relatively high temperatures (in excess of 1,000 C). Ceramic matrix composites retain the ceramic materials ability to withstand high temperatures, but also possess a much greater ductility and toughness. Their high strength and medium toughness is what makes them of so much interest to the aerospace community. This work concentrated on two different tasks. The first task was to do an extensive literature search into the mechanical behavior of ceramic matrix composite materials. This report contains the results of this task. The second task was to use this understanding to help interpret the ceramic matrix composite mechanical test results that had already been obtained by NASA. Since the specific details of these test results are subject to the International Traffic in Arms Regulations (ITAR), they are reported in a separate document (Jordan, 1997).

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  12. Effects of electron irradiation in space environment on thermal and mechanical properties of carbon fiber/bismaleimide composite

    NASA Astrophysics Data System (ADS)

    Yu, Qi; Chen, Ping; Gao, Yu; Ma, Keming; Lu, Chun; Xiong, Xuhai

    2014-10-01

    The effects of electron irradiation in simulated space environment on thermal and mechanical properties of high performance carbon fiber/bismaleimide composites were investigated. The dynamic mechanical properties of the composites exposed to different fluences of electron irradiation were evaluated by Dynamic mechanical analysis (DMA). Thermogravimetric analysis was applied to investigate the changes in thermal stability of the resin matrix after exposure to electron irradiation. The changes in mechanical properties of the composites were evaluated by flexural strength and interlaminar shear strength (ILSS). The results indicated that electron irradiation in high vacuum had an impact on thermal and mechanical properties of CF/BMI composites, which depends on irradiation fluence. At lower irradiation fluences less than 5 × 1015 cm-2, the dynamic storage modulus, cross-linking degree, thermal stability and mechanical properties that were determined by a competing effect between chain scission and cross-linking process, decreased firstly and then increased. While at higher fluences beyond 5 × 1015 cm-2, the chain scission process was dominant and thus led to the degradation in thermal and mechanical properties of the composites.

  13. Fourier transform infrared spectroscopy investigation of native tissue matrix modifications using a gamma irradiation process.

    PubMed

    Shah, Neha B; Wolkers, Willem F; Morrissey, Michael; Sun, Wendell Q; Bischof, John C

    2009-03-01

    In this study, Fourier transform infrared spectroscopy (FTIR) was used to evaluate the effects of a gamma irradiation process on AlloDerm, an implantable tissue device derived from human cadaver skin. Inspection of protein amide bands of dried tissue matrix revealed little difference in overall protein secondary structure between gamma-treated and control tissue matrices, although effects of gamma irradiation became apparent after rehydration. The temperature at which protein denaturation began decreased significantly, from 62.4 degrees C +/- 1.0 degrees C in the nonsterilized control tissue matrix to 53.4 degrees C +/- 1.2 degrees C, 48.7 degrees C +/- 0.3 degrees C, and 46.7 degrees C +/- 0.1 degrees C for 5-, 14- and 20-kGy gamma-treated AlloDerm samples, respectively (p < 0.05). Differences were particularly significant in the details of the tissue matrix denaturation profile, which consisted of multiple transitions. The solvent accessibility of tissue matrix was studied by following the rate of protein proton exchange in heavy water (D(2)O), which was evident from the appearance of the amide-II' band as a function of time to D(2)O exposure. In control tissue matrix, a rapid hydrogen/deuterium exchange was observed, with 50% exchange in 30 min, whereas the gamma-treated tissue matrix exhibited a much slower exchange, reaching the 50% exchange level after more than 2 h. The data indicate significant alterations of extracellular milieu in the tissue matrix after the gamma irradiation process. This study shows that FTIR is a valuable tool for studying protein stability and interactions in complex biological scaffolds such as extracellular tissue matrix.

  14. Residual stresses in polymer matrix composite laminates

    NASA Technical Reports Server (NTRS)

    Hahn, H. T.

    1976-01-01

    Residual stresses in composites are induced during fabrication and by environmental exposure. The theory formulated can describe the shrinkage commonly observed after a thermal expansion test. Comparison between the analysis and experimental data for laminates of various material systems indicates that the residual stress-free temperature can be lower than the curing temperature, depending on the curing process. Effects of residual stresses on ply failure including the acoustic emission characteristics are discussed.

  15. Structure and thermophysical properties of aluminum-matrix composites

    NASA Astrophysics Data System (ADS)

    Pugacheva, N. B.; Michurov, N. S.; Senaeva, E. I.; Bykova, T. M.

    2016-11-01

    The microstructure and thermophysical properties of aluminum-matrix composites have been studied, in which a granulated Al-Zn-Mg-Cu alloy has been used as the matrix, and SiC particles taken in the amounts of 10, 20, and 30 vol % have bee used as the filler. It has been shown that, with an increase in the amount of the filler, the temperatures of the solidus and liquidus of the composites and the values of the thermal expansion coefficient and density increase, whereas the heat capacity, thermal conductivity, and thermal diffusivity decrease. The heat capacity of the composite depends on the amount of the filler: upon heating from 25 to 500°C, the heat capacity of the composite with 10 vol % SiC increases by only 16%, while that of the composite with 20 vol % SiC increases by 19%; and, at 39 vol % SiC, it increases by 36%.

  16. Brazing of sheet composite materials with aluminium matrix

    NASA Astrophysics Data System (ADS)

    Khorunov, V. F.; Kuchuk-Iatsenko, V. S.; Dykhno, I. S.; Kasatkina, N. V.

    The technique of brazing composite sheets with an aluminum matrix is investigated for Al matrices with either stainless steel or boron fibers. Brazing is compared to other joining techniques, and the relationship between heating and pressure levels is studied by characterizing the joint qualities microscopically. Solder composition is similarly analyzed, and brazing recommendations are given for ranges of joint sizes. Calculations of the temperature fields for the brazing of these composite materials yield specific-heat input data. Optimal brazing modes thus derived for the Al-matrix composites yield joints free of the intermetallide phases that degrade the performance of brazed structures. The tensile strength of the optimized joints is shown to be good relative to the strength of the original composites with Al matrices.

  17. Effective thermal conductivity of composites with fibre-matrix debonding

    NASA Technical Reports Server (NTRS)

    Fadale, T. D.; Taya, M.

    1991-01-01

    Debonding of the fiber-matrix interface is a major cause for the degradation of the mechanical properties and the loss of thermal conductivity of fiber-reinforced composites. This paper discusses two analytical approaches for modeling the thermal conduction problem of composites. One is based on the concept of modeling the thermal barrier by an equivalent heat transfer coefficient at the fiber-matrix interface, as described by Hasselman and Johnson (1987) and Benveniste and Miloh (1986). The other approach, suggested by Hatta and Taya (1986), is by treating a composite with debonded interface as a coated-fiber composite. The major advantage of the latter aproach is that the thickness of the fiber coating can be realistically modeled depending upon the extent of degradation of the composite with the thermal conductivity of the coating as that of air.

  18. Improving Turbine Performance with Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.

    2007-01-01

    Under the new NASA Fundamental Aeronautics Program, efforts are on-going within the Supersonics Project aimed at the implementation of advanced SiC/SiC ceramic composites into hot section components of future gas turbine engines. Due to recent NASA advancements in SiC-based fibers and matrices, these composites are lighter and capable of much higher service temperatures than current metallic superalloys, which in turn will allow the engines to operate at higher efficiencies and reduced emissions. This presentation briefly reviews studies within Task 6.3.3 that are primarily aimed at developing physics-based concepts, tools, and process/property models for micro- and macro-structural design, fabrication, and lifing of SiC/SiC turbine components in general and airfoils in particular. Particular emphasis is currently being placed on understanding and modeling (1) creep effects on residual stress development within the component, (2) fiber architecture effects on key composite properties such as design strength, and (3) preform formation processes so that the optimum architectures can be implemented into complex-shaped components, such as turbine vanes and blades.

  19. Flexible matrix composite laminated disk/ring flywheel

    NASA Technical Reports Server (NTRS)

    Gupta, B. P.; Hannibal, A. J.

    1984-01-01

    An energy storage flywheel consisting of a quasi-isotropic composite disk overwrapped by a circumferentially wound ring made of carbon fiber and a elastometric matrix is proposed. Through analysis it was demonstrated that with an elastomeric matrix to relieve the radial stresses, a laminated disk/ring flywheel can be designed to store a least 80.3 Wh/kg or about 68% more than previous disk/ring designs. at the same time the simple construction is preserved.

  20. Considerations concerning fatigue life of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Radhakrishnan, V. M.; Bartolotta, Paul A.

    1993-01-01

    Since metal matrix composites (MMC) are composed from two very distinct materials each having their own physical and mechanical properties, it is feasible that the fatigue resistance depends on the strength of the weaker constituent. Based on this assumption, isothermal fatigue lives of several MMC's were analyzed utilizing a fatigue life diagram approach. For each MMC, the fatigue life diagram was quantified using the mechanical properties of its constituents. The fatigue life regions controlled by fiber fracture and matrix were also quantitatively defined.

  1. Interfacial studies in fiber-reinforced thermoplastic-matrix composites

    SciTech Connect

    Brady, R.L.

    1989-01-01

    The major theme of this dissertation is structure/property relationships in fiber-reinforced thermoplastic-matrix composites. Effort has been focused on the interface: interfacial crystallization and fiber/matrix adhesion. Included are investigations on interfacial nucleation and morphology, measurement of fiber/matrix adhesion, effects of interfacial adsorption and crystallization on fiber/matrix adhesion, and composites reinforced with thermotropic liquid crystal copolyester fibers. Crystallization of a copolyester and polybutylene terephthalate with glass, carbon, or aramid fibers has been studied with regard to interfacial morphology. Techniques employed included hot-stage optical microscopy and differential scanning calorimetry. Nucleation by the fibers was found to be a general phenomenon. Morphology could be varied by changing the cooling rate. In order to better monitor fiber /matrix adhesion, a buckled plate test has been developed. The test measures transverse toughness as the parameter characterizing interfacial adhesion in unidirectional, continuous-fiber composites. The test is simple to perform yet has advantages over other interfacial evaluation techniques. The buckled plate test was found to be a sensitive measure of fiber/matrix adhesion. The buckled plate test has been used along with the transverse tensile test to examine how interfacial adsorption and crystallization affect fiber/matrix adhesion in polycarbonate/carbon fiber composites. Adsorption was found to be of primary importance in developing adhesion, while crystallization is a secondary effect. The toughness data have been fit successfully for annealing time and temperature dependence. The dependence of adsorption and transverse toughness on matrix molecular weight was found to be large, with higher molecular weights adsorbing more effectively.

  2. Dry sliding wear of heat treated hybrid metal matrix composites

    NASA Astrophysics Data System (ADS)

    Naveed, Mohammed; Khan, A. R. Anwar

    2016-09-01

    In recent years, there has been an ever-increasing demand for enhancing mechanical properties of Aluminum Matrix Composites (AMCs), which are finding wide applications in the field of aerospace, automobile, defence etc,. Among all available aluminium alloys, Al6061 is extensively used owing to its excellent wear resistance and ease of processing. Newer techniques of improving the hardness and wear resistance of Al6061 by dispersing an appropriate mixture of hard ceramic powder and whiskers in the aluminium alloy are gaining popularity. The conventional aluminium based composites possess only one type of reinforcements. Addition of hard reinforcements such as silicon carbide, alumina, titanium carbide, improves hardness, strength and wear resistance of the composites. However, these composites possessing hard reinforcement do posses several problems during their machining operation. AMCs reinforced with particles of Gr have been reported to be possessing better wear characteristics owing to the reduced wear because of formation of a thin layer of Gr particles, which prevents metal to metal contact of the sliding surfaces. Further, heat treatment has a profound influence on mechanical properties of heat treatable aluminium alloys and its composites. For a solutionising temperature of 5500C, solutionising duration of 1hr, ageing temperature of 1750C, quenching media and ageing duration significantly alters mechanical properties of both aluminium alloy and its composites. In the light of the above, the present paper aims at developing aluminium based hybrid metal matrix composites containing both silicon carbide and graphite and characterize their mechanical properties by subjecting it to heat treatment. Results indicate that increase of graphite content increases wear resistance of hybrid composites reinforced with constant SiC reinforcement. Further heat treatment has a profound influence on the wear resistance of the matrix alloy as well as its hybrid composites

  3. High power x-ray welding of metal-matrix composites

    DOEpatents

    Rosenberg, Richard A.; Goeppner, George A.; Noonan, John R.; Farrell, William J.; Ma, Qing

    1999-01-01

    A method for joining metal-matrix composites (MMCs) by using high power x-rays as a volumetric heat source is provided. The method involves directing an x-ray to the weld line between two adjacent MMCs materials to create an irradiated region or melt zone. The x-rays have a power density greater than about 10.sup.4 watts/cm.sup.2 and provide the volumetric heat required to join the MMC materials. Importantly, the reinforcing material of the metal-matrix composites remains uniformly distributed in the melt zone, and the strength of the MMCs are not diminished. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys.

  4. High power X-ray welding of metal-matrix composites

    SciTech Connect

    Rosenberg, Richard A.; Goeppner, George A.; Noonan, John R.; Farrell, William J.; Ma, Qing

    1997-12-01

    A method for joining metal-matrix composites (MMCs) by using high power x-rays as a volumetric heat source is provided. The method involves directing an x-ray to the weld line between two adjacent MMCs materials to create an irradiated region or melt zone. The x-rays have a power density greater than about 10{sup 4} watts/cm{sup 2} and provide the volumetric heat required to join the MMC materials. Importantly, the reinforcing material of the metal-matrix composites remains uniformly distributed in the melt zone, and the strength of the MMCs are not diminished. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys.

  5. Modeling of the flexural behavior of ceramic-matrix composites

    NASA Technical Reports Server (NTRS)

    Kuo, Wen-Shyong; Chou, Tsu-Wei

    1990-01-01

    This paper examines the effects of matrix cracking and fiber breakage on the flexural behavior of ceramic composite beams. A model has been proposed to represent the damage evolution of the beam, of which the matrix fracture strain is smaller than that of the fibers. Close form solutions of the critical loads for the initiation of matrix cracking and fiber breakage in the tension side of the beam have been found. The effects of thermal residual stresses and fiber/matrix debonding have been taken into account. The initial deviation of the load-deflection curve from linearity is due to matrix cracking, while fiber breakages are responsible for the drop in the load carrying capacity of the beam. The proportional limit as well as the nonlinear behavior of the beam deflection have been identified. The growth of the damaged zone has also been predicted. A three-point bending case is given as a numerical example.

  6. 11 kGy gamma irradiated demineralized bone matrix enhances osteoclast activity.

    PubMed

    Wong, May Y W; Yu, Yan; Yang, Jia-Lin; Woolford, Tracey; Morgan, David A F; Walsh, William R

    2014-07-01

    Demineralized bone matrix (DBM) allografts are widely used in orthopaedic clinics. However, the biological impact on its osteoinductivity after its sterilization process by gamma irradiation is not well studied. Furthermore, little is known about the relationship between residual calcium levels on osteoinductivity. We hypothesize that low-dose gamma irradiation retains the osteoinducitivity properties of DBM and causes ectopic bone formation. A randomised animal trial was performed to compare tissue and molecular responses of low-dose (11 kGy) gamma irradiated and non-irradiated human DBM at 6 weeks post-intramuscular implantation using an athymic rat model. In addition, we correlated residual calcium levels and bone formation in gamma irradiated DBM. A modified haematoxylin and eosin stain identified ectopic bony capsules at all implanted sites with no significant difference on the amount of new bone formed between the groups. Statistically significantly lower ratio of alkaline phosphatase expression over tartrate-resistant acid phosphatase and/or cathepsin K expressions was found between the groups. This study found that low-dose gamma irradiated DBM, which provides a sterility assurance level of 10(-6) for bone allografts, retained osteoinductivity but exhibited significantly enhanced osteoclastic activity. Furthermore, this is the first study to find a positive correlation between residual calcium levels and bone formation in gamma irradiated DBM.

  7. Metal matrix composite micromechanics: In-situ behavior influence on composite properties

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Hopkins, D. A.; Chamis, C. C.

    1989-01-01

    Recent efforts in computational mechanics methods for simulating the nonlinear behavior of metal matrix composites have culminated in the implementation of the Metal Matrix Composite Analyzer (METCAN) computer code. In METCAN material nonlinearity is treated at the constituent (fiber, matrix, and interphase) level where the current material model describes a time-temperature-stress dependency of the constituent properties in a material behavior space. The composite properties are synthesized from the constituent instantaneous properties by virtue of composite micromechanics and macromechanics models. The behavior of metal matrix composites depends on fabrication process variables, in situ fiber and matrix properties, bonding between the fiber and matrix, and/or the properties of an interphase between the fiber and matrix. Specifically, the influence of in situ matrix strength and the interphase degradation on the unidirectional composite stress-strain behavior is examined. These types of studies provide insight into micromechanical behavior that may be helpful in resolving discrepancies between experimentally observed composite behavior and predicted response.

  8. Designing Cure Cycles for Matrix/Fiber Composite Parts

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung

    2006-01-01

    A methodology has been devised for designing cure cycles to be used in the fabrication of matrix/fiber composite parts (including laminated parts). As used here, cure cycles signifies schedules of elevated temperature and pressure as functions of time, chosen to obtain desired rates of chemical conversion of initially chemically reactive matrix materials and to consolidate the matrix and fiber materials into dense solids. Heretofore, cure cycles have been designed following an empirical, trial-and-error approach, which cannot be relied upon to yield optimum results. In contrast, the present methodology makes it possible to design an optimum or nearly optimum cure cycle for a specific application. Proper design of a cure cycle is critical for achieving consolidation of a reactive matrix/fiber layup into a void-free laminate. A cure cycle for a composite containing a reactive resin matrix usually consists of a two-stage ramp-and-hold temperature profile. The temperature and the duration of the hold for each stage are unique for a given composite material. The first, lower-temperature ramp-and hold stage is called the B stage in composite- fabrication terminology. At this stage, pressure is not applied, and volatiles (solvents and reaction by-products) are free to escape. The second, higher-temperature stage is for final forced consolidation.

  9. In situ strengths of matrix in a composite

    NASA Astrophysics Data System (ADS)

    Huang, Zheng-Ming; Xin, Li-Min

    2017-02-01

    A major obstacle to achieving reasonable strength prediction of a composite only from its constituent information is in the determination of in situ strengths of the matrix. One can measure only the original strengths of the pure matrix, on the basis of which the predicted transverse strengths of a unidirectional (UD) composite are far from reality. It is impossible to reliably measure matrix in situ strengths. This paper focuses on the correlation between in situ and original strengths. Stress concentrations in a matrix owing to the introduction of fibers are attributed to the strength variation. Once stress concentration factors (SCFs) are obtained, the matrix in situ strengths are assigned as the original counterparts divided by them. Such an SCF cannot be defined following a classical approach. All of the relevant issues associated with determining it are systematically addressed in this paper. Analytical expressions for SCFs under transverse tension, transverse compression, and transverse shear are derived. Closed-form and compact formulas for all of the uniaxial strengths of a UD composite are first presented in this paper. Their application to strength predictions of a number of typical UD composites demonstrates the correctness of these formulas.

  10. Experimental design and analysis for irradiation of SiC/SiC composite tubes under a prototypic high heat flux

    DOE PAGES

    Petrie, Christian M.; Koyanagi, Takaaki; McDuffee, Joel L.; ...

    2017-05-04

    The purpose of this work is to design an irradiation vehicle for testing silicon carbide (SiC) fiber-reinforced SiC matrix composite cladding materials under conditions representative of a light water reactor in order to validate thermo-mechanical models of stress states in these materials due to irradiation swelling and differential thermal expansion. The design allows for a constant tube outer surface temperature in the range of 300–350 °C under a representative high heat flux (~0.66 MW/m2) during one cycle of irradiation in an un-instrumented “rabbit” capsule in the High Flux Isotope Reactor. An engineered aluminum foil was developed to absorb the expansionmore » of the cladding tubes, due to irradiation swelling, without changing the thermal resistance of the gap between the cladding and irradiation capsule. Finite-element analyses of the capsule were performed, and the models used to calculate thermal contact resistance were validated by out-of-pile testing and post-irradiation examination of the foils and passive SiC thermometry. Six irradiated cladding tubes (both monoliths and composites) were irradiated and subsequently disassembled in a hot cell. The calculated temperatures of passive SiC thermometry inside the capsules showed good agreement with temperatures measured post-irradiation, with two calculated temperatures falling within 10 °C of experimental measurements. Furthermore, the success of this design could lead to new opportunities for irradiation applications with materials that suffer from irradiation swelling, creep, or other dimensional changes that can affect the specimen temperature during irradiation.« less

  11. Experimental design and analysis for irradiation of SiC/SiC composite tubes under a prototypic high heat flux

    NASA Astrophysics Data System (ADS)

    Petrie, Christian M.; Koyanagi, Takaaki; McDuffee, Joel L.; Deck, Christian P.; Katoh, Yutai; Terrani, Kurt A.

    2017-08-01

    The purpose of this work is to design an irradiation vehicle for testing silicon carbide (SiC) fiber-reinforced SiC matrix composite cladding materials under conditions representative of a light water reactor in order to validate thermo-mechanical models of stress states in these materials due to irradiation swelling and differential thermal expansion. The design allows for a constant tube outer surface temperature in the range of 300-350 °C under a representative high heat flux (∼0.66 MW/m2) during one cycle of irradiation in an un-instrumented ;rabbit; capsule in the High Flux Isotope Reactor. An engineered aluminum foil was developed to absorb the expansion of the cladding tubes, due to irradiation swelling, without changing the thermal resistance of the gap between the cladding and irradiation capsule. Finite-element analyses of the capsule were performed, and the models used to calculate thermal contact resistance were validated by out-of-pile testing and post-irradiation examination of the foils and passive SiC thermometry. Six irradiated cladding tubes (both monoliths and composites) were irradiated and subsequently disassembled in a hot cell. The calculated temperatures of passive SiC thermometry inside the capsules showed good agreement with temperatures measured post-irradiation, with two calculated temperatures falling within 10 °C of experimental measurements. The success of this design could lead to new opportunities for irradiation applications with materials that suffer from irradiation swelling, creep, or other dimensional changes that can affect the specimen temperature during irradiation.

  12. Preparing polymeric matrix composites using an aqueous slurry technique

    NASA Technical Reports Server (NTRS)

    Johnston, Norman J. (Inventor); Towell, Timothy W. (Inventor)

    1993-01-01

    An aqueous process was developed to prepare a consolidated composite laminate from an aqueous slurry. An aqueous poly(amic acid) surfactant solution was prepared by dissolving a poly(amic acid) powder in an aqueous ammonia solution. A polymeric powder was added to this solution to form a slurry. The slurry was deposited on carbon fiber to form a prepreg which was dried and stacked to form a composite laminate. The composite laminate was consolidated using pressure and was heated to form the polymeric matrix. The resulting composite laminate exhibited high fracture toughness and excellent consolidation.

  13. Light-weight, high-performance metal matrix composites

    NASA Technical Reports Server (NTRS)

    Rack, H. J.

    1988-01-01

    Recent years have seen the development of a wide range of light-weight, high-performance aluminum powder metallurgy composites that combine both standard (6061 and 2124) and specialty matrix compositions (Al-Mg-Cu-Li and Al-Fe-Ce) with a wide variety of discontinuous reinforcements (Al2O3, B4C, and SiC). This paper reviews the fabrication and damage tolerance performance of these light-weight, high-performance composites. Particular attention is given to developing a general framework for understanding the interrelationship existing between microstructure, thermomechanical processing and ductility/fracture toughness behavior in these composite systems.

  14. Progressive delamination in polymer matrix composite laminates: A new approach

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Murthy, P. L. N.; Minnetyan, L.

    1992-01-01

    A new approach independent of stress intensity factors and fracture toughness parameters has been developed and is described for the computational simulation of progressive delamination in polymer matrix composite laminates. The damage stages are quantified based on physics via composite mechanics while the degradation of the laminate behavior is quantified via the finite element method. The approach accounts for all types of composite behavior, laminate configuration, load conditions, and delamination processes starting from damage initiation, to unstable propagation, and to laminate fracture. Results of laminate fracture in composite beams, panels, plates, and shells are presented to demonstrate the effectiveness and versatility of this new approach.

  15. Transformation Superplasticity of Intermetallic and Ceramic Matrix Composites

    DTIC Science & Technology

    2000-07-14

    Ti6Al4V -TiC, Ti6Al4V -TiB and Fe-TiC), intermetallic matrix composites (NiAl-ZrO2), ceramics (Bi2O3) and ceramic matrix composites (zirconia-based system...than when held at a constant equivalent temperature . Furthermore, theoretical modeling was performed using both analytical closed- form solution...ceramic systems (bismuth oxide and zirconia), first numerical model (finite-element), new continuum model (at high stresses), first demonstration of

  16. Metal matrix composites from dynamic consolidation of powder mixtures

    SciTech Connect

    Korth, G.E.; Williamson, R.L.; Rabin, B.H.

    1989-01-01

    Mixtures of 2124 aluminum alloy and silicon carbide powders were dynamically consolidated using explosives. This process results in a fully dense product and has the potential of becoming an economical method of producing metal matrix composites, especially where undesirable reactions would normally occur between the metal and ceramic reinforcement. With the correct processing parameters, the aluminum powder plastically deforms to form a continuous matrix with minimum interaction with SiC. Microstructure and mechanical properties of the composite are presented. Numerical simulations were performed to better understand the consolidation process and determine test parameters difficult to obtain by experimentation. 7 refs., 3 figs., 2 tabs.

  17. Acousto-ultrasonic decay in metal matrix composite panels

    NASA Astrophysics Data System (ADS)

    Kautz, Harold E.

    1995-08-01

    Acousto-ultrasonic (A-U) decay rates (UD) were measured in metal matrix composite (MMC) panels. The MMC panels had fiber architectures and cross-sectional thicknesses corresponding to those designed for aerospace turbine engine structures. The wavelength-to-thickness ratio produced by the combination of experimental frequency setting conditions and specimen geometry was found to be a key parameter for identifying optimum conditions for UD measurements. The ratio was shown to be a useful rule of thumb when applied to ceramic matrix composites (CMC)s and monolithic thermo-plastics.

  18. Ductility of a continuous fiber reinforced aluminum matrix composite

    NASA Technical Reports Server (NTRS)

    Jansson, S.; Leckie, Frederick A.

    1991-01-01

    The transverse properties of an aluminum alloy metal matrix composite reinforced by continuous alumina fibers have been investigated. The composite is subjected to both mechanical and cyclic thermal loading. The ductility can vary by an order of magnitude according to the operating conditions. For high mechanical and low thermal loading the ductility is small, for low mechanical and high thermal loading the ductility is an order of magnitude higher. Experiments on a beam in bending confirm that the ductility is strongly dependent on the loading conditions. The observations suggest a means of utilizing the inherent ductility of the matrix.

  19. Acousto-ultrasonic decay in metal matrix composite panels

    NASA Technical Reports Server (NTRS)

    Kautz, Harold E.

    1995-01-01

    Acousto-ultrasonic (A-U) decay rates (UD) were measured in metal matrix composite (MMC) panels. The MMC panels had fiber architectures and cross-sectional thicknesses corresponding to those designed for aerospace turbine engine structures. The wavelength-to-thickness ratio produced by the combination of experimental frequency setting conditions and specimen geometry was found to be a key parameter for identifying optimum conditions for UD measurements. The ratio was shown to be a useful rule of thumb when applied to ceramic matrix composites (CMC)s and monolithic thermo-plastics.

  20. Chronic UVB-irradiation actuates perpetuated dermal matrix remodeling in female mice: Protective role of estrogen

    PubMed Central

    Röck, Katharina; Joosse, Simon Andreas; Müller, Julia; Heinisch, Nina; Fuchs, Nicola; Meusch, Michael; Zipper, Petra; Reifenberger, Julia; Pantel, Klaus; Fischer, Jens Walter

    2016-01-01

    Chronic UVB-exposure and declined estradiol production after menopause represent important factors leading to extrinsic and intrinsic aging, respectively. Remodeling of the extracellular matrix (ECM) plays a crucial role in both responses. Whether the dermal ECM is able to recover after cessation of UVB-irradiation in dependence of estradiol is not known, however of relevance when regarding possible treatment options. Therefore, the endogenous sex hormone production was depleted by ovariectomy in female mice. Half of the mice received estradiol substitution. Mice were UVB-irradiated for 20 weeks and afterwards kept for 10 weeks without irradiation. The collagen-, hyaluronan- and proteoglycan- (versican, biglycan, lumican) matrix, collagen cleavage products and functional skin parameters were analyzed. The intrinsic aging process was characterized by increased collagen fragmentation and accumulation of biglycan. Chronic UVB-irradiation additionally augmented the lumican, versican and hyaluronan content of the dermis. In the absence of further UVB-irradiation the degradation of collagen and accumulation of biglycan in the extrinsically aged group was perpetuated in an excessive matter. Whereas estradiol increased the proteoglycan content, it reversed the effects of the perpetuated extrinsic response on collagen degradation. Suspension of the intrinsic pathway might therefore be sufficient to antagonize UVB-evoked long-term damage to the dermal ECM. PMID:27460287

  1. Fabrication of Fiber-Reinforced Celsian Matrix Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Setlock, John A.

    2000-01-01

    A method has been developed for the fabrication of small diameter, multifilament tow fiber reinforced ceramic matrix composites. Its application has been successfully demonstrated for the Hi-Nicalon/celsian system. Strong and tough celsian matrix composites, reinforced with BN/SiC-coated Hi-Nicalon fibers, have been fabricated by infiltrating the fiber tows with the matrix slurry, winding the tows on a drum, cutting and stacking of the prepreg tapes in the desired orientation, and hot pressing. The monoclinic celsian phase in the matrix was produced in situ, during hot pressing, from the 0.75BaO-0.25SrO-Al2O3-2SiO2 mixed precursor synthesized by solid state reaction from metal oxides. Hot pressing resulted in almost fully dense fiber-reinforced composites. The unidirectional composites having approx. 42 vol% of fibers exhibited graceful failure with extensive fiber pullout in three-point bend tests at room temperature. Values of yield stress and strain were 435 +/- 35 MPa and 0.27 +/- 0.01 percent, respectively, and ultimate strengths of 900 +/- 60 MPa were observed. The Young's modulus of the composites was measured to be 165 +/- 5 GPa.

  2. Composite Matrix Regenerator for Stirling Engines

    NASA Technical Reports Server (NTRS)

    Knowles, Timothy R.

    1997-01-01

    This project concerns the design, fabrication and testing of carbon regenerators for use in Stirling power convertors. Radial fiber design with nonmetallic components offers a number of potential advantages over conventional steel regenerators: reduced conduction and pressure drop losses, and the capability for higher temperature, higher frequency operation. Diverse composite fabrication methods are explored and lessons learned are summarized. A pulsed single-blow test rig has been developed that has been used for generating thermal effectiveness data for different flow velocities. Carbon regenerators have been fabricated by carbon vapor infiltration of electroflocked preforms. Performance data in a small Stirling engine are obtained. Prototype regenerators designed for the BP-1000 power convertor were fabricated and delivered to NASA-Lewis.

  3. Influence of whole body irradiation and local shielding on matrix-induced endochondral bone differentiation

    SciTech Connect

    Wientroub, S.; Weiss, J.F.; Catravas, G.N.; Reddi, A.H. )

    1990-01-01

    Subcutaneous implantation of demineralized bone matrix into allogeneic rats induces endochondral bone formation. We have investigated the effects of irradiation on the sequelae of the interaction of collagenous matrix and mesenchymal cells and on cartilage and bone differentiation. Rats were irradiated in a vertical direction with a midline dose of 850 rad. Radiation entered the rats ventrally while a small area of the upper thorax was locally shielded. After irradiation, bone matrix was implanted in shielded and nonshielded sites, and the implants were studied at various stages. On day 3, (3H)thymidine incorporation, an index of cell proliferation, was inhibited by 70% in the nonshielded sites compared to nonirradiated control rats. The degree of inhibition (35%) was less pronounced in shielded sites. Furthermore, there was recovery of cell proliferation in the shielded sites as opposed to the nonshielded contralateral site. A similar pattern was observed on day 7 as assessed by 35SO4 incorporation into proteoglycans during chondrogenesis. Bone formation and mineralization were quantified on day 11 by alkaline phosphatase activity and 45Ca incorporation. In nonshielded sites, there was a 73% inhibition of alkaline phosphatase activity. In conclusion, radiation impaired progenitor cell proliferation which resulted in decreased cartilage and bone differentiation. These findings imply that local mesenchymal cells proliferate and differentiate into bone in response to implanted collagenous matrix.

  4. Tailoring the bending stiffness of elastomeric dual-matrix composites

    NASA Astrophysics Data System (ADS)

    Platt, David Lewis

    Aircraft structural design is becoming increasingly oriented towards multifunctional structures, which are capable of supporting large loads while exhibiting additional functional capabilities; morphing is an example. Composite materials provide the perfect testbed for such morphing technologies. Dual-matrix composites are being investigated by a number of researchers, primarily for use in deployable structures. This work investigates a more load-intensive application in aircraft cabin interiors. A morphing composite meal-tray table prototype is fabricated and tested. The macromechanics of dual-matrix laminates are investigated, with the focus being the tailoring of the bending stiffness of such laminates. The cross-section anticlastic deflections of +/-45 degree layups, due to high Poisson ratios, are shown to increase the bending stiffness of the laminate, resulting from an increased second moment of area. A predictive model for bending stiffness is constructed, compared with FEA and experiments, and its limitations in predicting woven-fabric composite behaviour are discussed.

  5. Mechanical Properties of Particulate Reinforced Aluminium Alloy Matrix Composite

    SciTech Connect

    Sayuti, M.; Sulaiman, S.; Baharudin, B. T. H. T.; Arifin, M. K. A.; Suraya, S.; Vijayaram, T. R.

    2011-01-17

    This paper discusses the mechanical properties of Titanium Carbide (TiC) particulate reinforced aluminium-silicon alloy matrix composite. TiC particulate reinforced LM6 alloy matrix composites were fabricated by carbon dioxide sand molding process with different particulate weight fraction. Tensile strength, hardness and microstructure studies were conducted to determine the maximum load, tensile strength, modulus of elasticity and fracture surface analysis have been performed to characterize the morphological aspects of the test samples after tensile testing. Hardness values are measured for the TiC reinforced LM6 alloy composites and it has been found that it gradually increases with increased addition of the reinforcement phase. The tensile strength of the composites increased with the increase percentage of TiC particulate.

  6. 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.

  7. 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.

  8. Rate Dependent Deformation and Strength Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1999-01-01

    A research program is being undertaken to develop rate dependent deformation and failure models for the analysis of polymer matrix composite materials. In previous work in this program, strain-rate dependent inelastic constitutive equations used to analyze polymers have been implemented into a mechanics of materials based composite micromechanics method. In the current work, modifications to the micromechanics model have been implemented to improve the calculation of the effective inelastic strain. Additionally, modifications to the polymer constitutive model are discussed in which pressure dependence is incorporated into the equations in order to improve the calculation of constituent and composite shear stresses. The Hashin failure criterion is implemented into the analysis method to allow for the calculation of ply level failure stresses. The deformation response and failure stresses for two representative uniaxial polymer matrix composites, IM7/977-2 and AS4-PEEK, are predicted for varying strain rates and fiber orientations. The predicted results compare favorably to experimentally obtained values.

  9. High Strain Rate Behavior of Polymer Matrix Composites Analyzed

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.

    2001-01-01

    Procedures for modeling the high-speed impact of composite materials are needed for designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. To characterize and validate material models that could be used in the design of impactresistant engine cases, researchers must obtain material data over a wide variety of strain rates. An experimental program has been carried out through a university grant with the Ohio State University to obtain deformation data for a representative polymer matrix composite for strain rates ranging from quasi-static to high rates of several hundred per second. This information has been used to characterize and validate a constitutive model that was developed at the NASA Glenn Research Center.

  10. Mechanical Properties of Particulate Reinforced Aluminium Alloy Matrix Composite

    NASA Astrophysics Data System (ADS)

    Sayuti, M.; Sulaiman, S.; Baharudin, B. T. H. T.; Arifin, M. K. A.; Suraya, S.; Vijayaram, T. R.

    2011-01-01

    This paper discusses the mechanical properties of Titanium Carbide (TiC) particulate reinforced aluminium-silicon alloy matrix composite. TiC particulate reinforced LM6 alloy matrix composites were fabricated by carbon dioxide sand molding process with different particulate weight fraction. Tensile strength, hardness and microstructure studies were conducted to determine the maximum load, tensile strength, modulus of elasticity and fracture surface analysis have been performed to characterize the morphological aspects of the test samples after tensile testing. Hardness values are measured for the TiC reinforced LM6 alloy composites and it has been found that it gradually increases with increased addition of the reinforcement phase. The tensile strength of the composites increased with the increase percentage of TiC particulate.

  11. Modeling of crack bridging in a unidirectional metal matrix composite

    NASA Technical Reports Server (NTRS)

    Ghosn, Louis J.; Kantzos, Pete; Telesman, Jack

    1992-01-01

    The effective fatigue crack driving force and crack opening profiles were determined analytically for fatigue tested unidirectional composite specimens exhibiting fiber bridging. The crack closure pressure due to bridging was modeled using two approaches: the fiber pressure model and the shear lag model. For both closure models, the Bueckner weight function method and the finite element method were used to calculate crack opening displacements and the crack driving force. The predicted near crack tip opening profile agreed well with the experimentally measured profiles for single edge notch SCS-6/Ti-15-3 metal matrix composite specimens. The numerically determined effective crack driving force, Delta K(eff), was calculated using both models to correlate the measure crack growth rate in the composite. The calculated Delta K(eff) from both models accounted for the crack bridging by showing a good agreement between the measured fatigue crack growth rates of the bridged composite and that of unreinforced, unbridged titanium matrix alloy specimens.

  12. Design Studies for a Multiple Application Thermal Reactor for Irradiation Experiments (MATRIX)

    SciTech Connect

    Pope, Michael A.; Gougar, Hans D.; Ryskamp, J. M.

    2015-03-01

    The Advanced Test Reactor (ATR) is a high power density test reactor specializing in fuel and materials irradiation. For more than 45 years, the ATR has provided irradiations of materials and fuels testing along with radioisotope production. Should unforeseen circumstances lead to the decommissioning of ATR, the U.S. Government would be left without a large-scale materials irradiation capability to meet the needs of its nuclear energy and naval reactor missions. In anticipation of this possibility, work was performed under the Laboratory Directed Research and Development (LDRD) program to investigate test reactor concepts that could satisfy the current missions of the ATR along with an expanded set of secondary missions. A survey was conducted in order to catalogue the anticipated needs of potential customers. Then, concepts were evaluated to fill the role for this reactor, dubbed the Multi-Application Thermal Reactor Irradiation eXperiments (MATRIX). The baseline MATRIX design is expected to be capable of longer cycle lengths than ATR given a particular batch scheme. The volume of test space in In-Pile-Tubes (IPTs) is larger in MATRIX than in ATR with comparable magnitude of neutron flux. Furthermore, MATRIX has more locations of greater volume having high fast neutron flux than ATR. From the analyses performed in this work, it appears that the lead MATRIX design can be designed to meet the anticipated needs of the ATR replacement reactor. However, this design is quite immature, and therefore any requirements currently met must be re-evaluated as the design is developed further.

  13. Synthesis of dental matrix proteins and viability of odontoblast-like cells irradiated with blue LED.

    PubMed

    Alonso, Juliana Rosa Luiz; Turrioni, Ana Paula Silveira; Basso, Fernanda Gonçalves; de Souza Costa, Carlos Alberto; Hebling, Josimeri

    2016-04-01

    To evaluate the effect of irradiation with light-emitting diode (LED; 455 nm) on the viability and synthesis of dentin matrix proteins by odontoblast-like cells, MDPC-23 cells were cultivated (10(4) cells/cm(2)) in 24-well culture plates. After 12 h incubation in Dulbecco's modified Eagle's medium (DMEM), the cells were submitted to nutritional restriction by means of reducing the concentration of fetal bovine serum (FBS) for an additional 12 h. Cells were irradiated one single time with one of the following energy densities (EDs): 0.5, 2, 4, 10, or 15 J/cm(2) and irradiance fixed at 20 mW/cm(2). Non-irradiated cells served as control. After 72 h, cells were evaluated with regard to viability (methylthiazol tetrazolium technique (MTT)), mineralization nodule (MN) formation, total protein (TP) production, alkaline phosphatase activity (ALP), and collagen synthesis (Sircol), n = 8. The data were submitted to Kruskal-Wallis and Mann-Whitney tests (p > 0.05). There was no statistical difference between the viability of cells irradiated or not (control), for all the EDs. However, an increase in TP was observed for all the EDs when compared with the control group. A reduced ALP activity was seen in all irradiated groups, except for the ED of 0.5 J/cm(2), which did not differ from the control. There was no difference between the irradiated groups and control regarding collagen synthesis, with the exception of the ED of 10 J/cm(2), which inhibited this cell function. Significant reduction in MN occurred only for the EDs of 0.5 and 2 J/cm(2). The single irradiation with blue LED (455 nm), irradiance of 20 mW/cm(2), and energy densities ranging from 0.5 to 15 J/cm(2) exerted no effective biostimulatory capacity on odontoblast-like cells.

  14. USE OF COMBUSTION SYNTHESIS IN PREPARING CERAMIC-MATRIX AND METAL-MATRIX COMPOSITE POWDERS

    SciTech Connect

    Weil, K. Scott; Hardy, John S.

    2005-03-01

    A standard combustion-based approach typically used to synthesize nanosize oxide powders has been modified to prepare composite oxide-metal powders for subsequent densification via sintering or hot-pressing into ceramic- or metal-matrix composites. Copper and cerium nitrate salts were dissolved in the appropriate ratio in water and combined with glycine, then heated to cause autoignition. The ratio of glycine-to-total nitrate concentration was found to have the largest effect on the composition, agglomerate size, crystallite size, and dispersivity of phases in the powder product. After consolidation and sintering under reducing conditions, the resulting composite compact consists of a well-dispersed mixture of sub-micron size reinforcement particles in a fine-grained matrix.

  15. Ceramic fiber reinforced glass-ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P. (Inventor)

    1993-01-01

    A slurry of BSAS glass powders is cast into tapes which are cut to predetermined sizes. Mats of continuous chemical vapor deposition (CVD)-SiC fibers are alternately stacked with these matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite which is heated to burn out organic constituents. The remaining interim material is then hot-pressed to form a BSAS glass-ceramic fiber-reinforced composite.

  16. Fiber/matrix adhesion in graphite/PEKK composites

    NASA Technical Reports Server (NTRS)

    Bucher, R. A.; Hinkley, J. A.

    1992-01-01

    Experiments with poly ether ketone ketone (PEKK) resin and AS-4, IM-7, and G30-500 fibers showed excellent correlation between resin/fiber contact angle and composite transverse flexural strength as measures of resin/fiber interfacial strength. Both tests indicate the strongest interface for G30-500/PEKK followed by IM-7/PEKK and AS-4/PEKK. Also discussed are fiber effects on interlaminar fracture and on the in situ crystallization of the matrix during composite fabrication.

  17. Recycling of ceramic particulate reinforced aluminium metal matrix composites

    SciTech Connect

    Sharma, S.C.; Murthy, C.S.C.; Kamath, R.; Vinai Babu, B.R.; Satish, B.M.; Girish, B.M.

    1995-12-31

    The aluminum matrix composites with ceramic dispersoids can be separated by the density difference concept. In the proposed work, composite scrap is recycled using an oil fired furnace. The scrap is melted in the furnace and temperature is maintained below 740 degree centigrade. Because of the density difference the lighter dispersoids will float and heavier dispersoids will settle down. The clean melt is separated be removing the floating and settled dispersoids, and then filtering using ceramic filters.

  18. Fiber/matrix adhesion in graphite/PEKK composites

    NASA Technical Reports Server (NTRS)

    Bucher, R. A.; Hinkley, J. A.

    1992-01-01

    Experiments with poly ether ketone ketone (PEKK) resin and AS-4, IM-7, and G30-500 fibers showed excellent correlation between resin/fiber contact angle and composite transverse flexural strength as measures of resin/fiber interfacial strength. Both tests indicate the strongest interface for G30-500/PEKK followed by IM-7/PEKK and AS-4/PEKK. Also discussed are fiber effects on interlaminar fracture and on the in situ crystallization of the matrix during composite fabrication.

  19. Novel Ceramic Matrix Composites for Deep Submergence Pressure Vessel Applications

    DTIC Science & Technology

    1991-10-01

    ceramics and ceramic matrix applications have been fabricated by the composites. DIMOX "M directed metal oxidation process. These SiC/A12 0 3 composite...MATERIALS The versatility of the DIMOX TM directed CYLINDER FABRICATION metal oxidation process allows for the incorporation of a wide range of...preform materials, served to demonstrate the applicability of This unique ability permits individual the DIMOX T M directed metal oxidation material

  20. 3-D woven, mullite matrix, composite filter

    SciTech Connect

    Lane, J.E.; Painter, C.J.; Radford, K.C. LeCostaouec, J.F.

    1995-12-01

    Westinghouse, with Techniweave as a major subcontractor, is conducting a three-phase program aimed at providing advanced candle filters for a 1996 pilot scale demonstration in one of the two hot gas filter systems at Southern Company Service`s Wilsonville PSD Facility. The Base Program (Phases I and II) objective is to develop and demonstrate the suitability of the Westinghouse/Techniweave next generation composite candle filter for use in Pressurized Fluidized Bed Combustion (PFBC) and/or Integrated Gasification Combined Cycle (IGCC) power generation systems. The Optional Task (Phase M, Task 5) objective is to fabricate, inspect and ship to Wilsonville Hot gas particulate filters are key components for the successful commercializaion of advanced coal-based power-generation systems such as Pressurized Fluidized-bed Combustion (PFBC), including second-generation PFBC, and Integrated Gasification Combined Cycles (IGCC). Current generation monolithic ceramic filters are subject to catastrophic failure because they have very low resistance to crack propagation. To overcome this problem, a damage-tolerant ceramic filter element is needed.

  1. Thermosetting Polymer-Matrix Composites for Strucutral Repair Applications

    SciTech Connect

    Goertzen, William Kirby

    2007-12-01

    Several classes of thermosetting polymer matrix composites were evaluated for use in structural repair applications. Initial work involved the characterization and evaluation of woven carbon fiber/epoxy matrix composites for structural pipeline repair. Cyanate ester resins were evaluated as a replacement for epoxy in composites for high-temperature pipe repair applications, and as the basis for adhesives for resin infusion repair of high-temperature composite materials. Carbon fiber/cyanate ester matrix composites and fumed silica/cyanate ester nanocomposites were evaluated for their thermal, mechanical, viscoelastic, and rheological properties as they relate to their structure, chemistry, and processing characteristics. The bisphenol E cyanate ester under investigation possesses a high glass transition temperature, excellent mechanical properties, and unique ambient temperature processability. The incorporate of fumed silica served to enhance the mechanical and rheological properties of the polymer and reduce thermal expansion without sacrificing glass transition or drastically altering curing kinetics. Characterization of the composites included dynamic mechanical analysis, thermomechanical analysis, differential scanning calorimetry, thermogravimetric analysis, rheological and rheokinetic evaluation, and transmission electron microscopy.

  2. Polymer precursors for ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Litt, M. H.; Kumar, K.

    1986-01-01

    The synthesis and characterization of a polycyclohexasilane is reported. Because of its cyclic structure, it is anticipated that this polymer might serve as a precursor to SIC having a high char yield with little rearrangement to form small, volatile cyclic silanes, and, as such, would be of interest as a precursor to SiC composite matrices and fibers, or as a binder in ceramic processing. Several approaches to the synthesis of a bifunctional cyclic monomer were attempted; the most successful of these was metal coupling of PhMeSiCl2 and Me2SiCl2. The procedure gives six-membered ring compounds with all degrees of phenyl substitution, from none to hexaphenyl. The compounds with from 0-2 groups were isolated and characterized. The fraction with degree of phenyl substitution equal to 2, a mixture of cis and trans 1,2-; 1,3-; and 1,4 isomers, was isolated in 32 percent yield. Pure 1,4 diphenyldecamethylcyclohexasilane was isolated from the mixed diphenyl compounds and characterized. Diphenyldecamethylcyclohexasilanes were dephenylated to dichlorodecamethylcyclohexasilanes by treating with H2SO4.NH4Cl in benzene. The latter were purified and polymerized by reacting with sodium in toluene. The polymers were characterized by HPGPC, elemental analysis, proton NMR, and IR. Thermogravimetric analyses were carried out on the polymers. As the yield of residual SiC was low, polymers were heat treated to increase the residual char yield. As high as 51.52 percent residual char yield was obtained in one case.

  3. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 1; Matrix Constitutive Equations

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites.

  4. High dose neutron irradiations of Hi-Nicalon Type S silicon carbide composites, Part 1: Microstructural evaluations

    SciTech Connect

    Perez-Bergquist, Alex G.; Nozawa, Takashi; Shih, Chunghao Phillip; Leonard, Keith J.; Snead, Lance Lewis; Katoh, Yutai

    2014-07-01

    Over the past decade, significant progress has been made in the development of silicon carbide (SiC) composites, composed of near-stoichiometric SiC fibers embedded in a crystalline SiC matrix, to the point that such materials can now be considered nuclear grade. Recent neutron irradiation studies of Hi-Nicalon Type S SiC composites showed excellent radiation response at damage levels of 30-40 dpa at temperatures of 300-800 °C. However, more recent studies of these same fiber composites irradiated to damage levels of >70 dpa at similar temperatures showed a marked decrease in ultimate flexural strength, particularly at 300 °C. Here, electron microscopy is used to analyze the microstructural evolution of these irradiated composites in order to investigate the cause of the degradation. While minimal changes were observed in Hi-Nicalon Type S SiC composites irradiated at 800 °C, substantial microstructural evolution is observed in those irradiated at 300° C. Furthermore, carbonaceous particles in the fibers grew by 25% compared to the virgin case, and severe cracking occurred at interphase layers.

  5. High dose neutron irradiations of Hi-Nicalon Type S silicon carbide composites, Part 1: Microstructural evaluations

    DOE PAGES

    Perez-Bergquist, Alex G.; Nozawa, Takashi; Shih, Chunghao Phillip; ...

    2014-07-01

    Over the past decade, significant progress has been made in the development of silicon carbide (SiC) composites, composed of near-stoichiometric SiC fibers embedded in a crystalline SiC matrix, to the point that such materials can now be considered nuclear grade. Recent neutron irradiation studies of Hi-Nicalon Type S SiC composites showed excellent radiation response at damage levels of 30-40 dpa at temperatures of 300-800 °C. However, more recent studies of these same fiber composites irradiated to damage levels of >70 dpa at similar temperatures showed a marked decrease in ultimate flexural strength, particularly at 300 °C. Here, electron microscopy ismore » used to analyze the microstructural evolution of these irradiated composites in order to investigate the cause of the degradation. While minimal changes were observed in Hi-Nicalon Type S SiC composites irradiated at 800 °C, substantial microstructural evolution is observed in those irradiated at 300° C. Furthermore, carbonaceous particles in the fibers grew by 25% compared to the virgin case, and severe cracking occurred at interphase layers.« less

  6. 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.

  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. 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.

  9. Metal matrix composites: History, status, factors and future

    NASA Astrophysics Data System (ADS)

    Cyriac, Ajith James

    The history, status, and future of metal matrix composites are presented by evaluating the progression of available literature through time. The trends that existed and issues that still prevail are discussed and a prediction of the future for MMCs is presented. The factors that govern the performance of metal matrix composites are also discussed. In many developed countries and in several developing countries there exists continued interest in MMCs. Researchers tried numerous combinations of matrices and reinforcements since work strictly on MMCs began in the 1950s. This led to developments for aerospace and defense applications, but resultant commercial applications were limited. The introduction of ceramic whiskers as reinforcement and the development of 'in-situ' eutectics in the 1960s aided high temperature applications in aircraft engines. In the late 1970s the automobile industries started to take MMCs seriously. In the last 20 years, MMCs evolved from laboratories to a class of materials with numerous applications and commercial markets. After the collapse of the Berlin Wall, prevailing order in the world changed drastically. This effect was evident in the progression of metal matrix composites. The internet connected the world like never before and tremendous information was available for researchers around the world. Globalization and the internet resulted in the transformation of the world to a more level playing field, and this effect is evident in the nature and source of research on metal matrix composites happening around the world.

  10. Key Issues for Aerospace Applications of Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Clinton, R. G., Jr.; Levine, S. R.

    1998-01-01

    Ceramic matrix composites (CMC) offer significant advantages for future aerospace applications including turbine engine and liquid rocket engine components, thermal protection systems, and "hot structures". Key characteristics which establish ceramic matrix composites as attractive and often enabling choices are strength retention at high temperatures and reduced weight relative to currently used metallics. However, due to the immaturity of this class of materials which is further compounded by the lack of experience with CMC's in the aerospace industry, there are significant challenges involved in the development and implementation of ceramic matrix composites into aerospace systems. Some of the more critical challenges are attachment and load transfer methodologies; manufacturing techniques, particularly scale up to large and thick section components; operational environment resistance; damage tolerance; durability; repair techniques; reproducibility; database availability; and the lack of validated design and analysis tools. The presentation will examine the technical issues confronting the application of ceramic matrix composites to aerospace systems and identify the key material systems having potential for substantial payoff relative to the primary requirements of light weight and reduced cost for future systems. Current programs and future research opportunities will be described in the presentation which will focus on materials and processes issues.

  11. Stress Corrosion Cracking in Polymer Matrix Glass Fiber Composites

    NASA Astrophysics Data System (ADS)

    Kosak, Jonathan

    With the use of Polymer Matrix Glass Fiber Composites ever expanding, understanding conditions that lead to failure before expected service life is of increasing importance. Stress Corrosion Cracking (SCC) has proven to be one such example of conditions found in use in high voltage transmission line applications that leads to brittle fracture of polymer matrix composites. SCC has been proven to be the result of acid buildup on the lines due to corona discharges and water buildup. This acid leaches minerals from the fibers, leading to fracture at low loads and service life. In order to combat this problem, efforts are being made to determine which composites have greater resistance to SCC. This study was used to create a methodology to monitor for damage during SCC and classify damage by mechanism type (matrix cracking and fiber breaking) by using 4-point SCC bend testing, 3-point bend testing, a forward predictive model, unique post processing techniques, and microscopy. This would allow a classification in composite resistance to SCC as well as create a methodology for future research in this field. Concluding this study, only matrix cracking was able to be fully classified, however, a methodology was developed for future experimentation.

  12. Arc spray fabrication of metal matrix composite monotape

    NASA Technical Reports Server (NTRS)

    Westfall, L. J. (Inventor)

    1985-01-01

    Arc metal spraying is used to spray liquid metal onto an array of high strength fibers that were previously wound onto a large drum contained inside a controlled atmosphere chamber. This chamber is first evacuated to remove gaseous contaminants and then backfilled with a neutral gas up to atmospheric pressure. This process is used to produce a large size metal matrix composite monotape.

  13. Key Issues for Aerospace Applications of Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Clinton, R. G., Jr.; Levine, S. R.

    1998-01-01

    Ceramic matrix composites (CMC) offer significant advantages for future aerospace applications including turbine engine and liquid rocket engine components, thermal protection systems, and "hot structures". Key characteristics which establish ceramic matrix composites as attractive and often enabling choices are strength retention at high temperatures and reduced weight relative to currently used metallics. However, due to the immaturity of this class of materials which is further compounded by the lack of experience with CMC's in the aerospace industry, there are significant challenges involved in the development and implementation of ceramic matrix composites into aerospace systems. Some of the more critical challenges are attachment and load transfer methodologies; manufacturing techniques, particularly scale up to large and thick section components; operational environment resistance; damage tolerance; durability; repair techniques; reproducibility; database availability; and the lack of validated design and analysis tools. The presentation will examine the technical issues confronting the application of ceramic matrix composites to aerospace systems and identify the key material systems having potential for substantial payoff relative to the primary requirements of light weight and reduced cost for future systems. Current programs and future research opportunities will be described in the presentation which will focus on materials and processes issues.

  14. Matrix-dominated mechanical properties of a fiber composite lamina

    SciTech Connect

    Lyon, R.E.; Schumann, D.L.; DeTeresa, S.J.

    1992-05-18

    Matrix-dominated mechanical properties of unidirectional fiber composite laminae were determined from hoop-wound tube specimens and cylindrical rods fabricated from both wet-filament winding and prepreg material systems. Longitudinal shear modulus and strength as well as transverse Young's modulus, transverse tensile strength, and transverse compressive strength were obtained from a thin-walled tube specimen using a new fixturing design. Lamina properties are presented for several carbon fiber/epoxy composite materials. Longitudinal shear moduli were measured for both tubes and rods in torsion. Results obtained in the linear-elastic regimes above and below the glass transition temperature (Tg) of the matrix phase were compared with micromechanics predictions. Although agreement between predicted and measured shear moduli was reasonable below Tg, large discrepancies were observed when the matrix phase was elastomeric.

  15. Matrix-dominated mechanical properties of a fiber composite lamina

    SciTech Connect

    Lyon, R.E.; Schumann, D.L.; DeTeresa, S.J.

    1992-05-18

    Matrix-dominated mechanical properties of unidirectional fiber composite laminae were determined from hoop-wound tube specimens and cylindrical rods fabricated from both wet-filament winding and prepreg material systems. Longitudinal shear modulus and strength as well as transverse Young`s modulus, transverse tensile strength, and transverse compressive strength were obtained from a thin-walled tube specimen using a new fixturing design. Lamina properties are presented for several carbon fiber/epoxy composite materials. Longitudinal shear moduli were measured for both tubes and rods in torsion. Results obtained in the linear-elastic regimes above and below the glass transition temperature (Tg) of the matrix phase were compared with micromechanics predictions. Although agreement between predicted and measured shear moduli was reasonable below Tg, large discrepancies were observed when the matrix phase was elastomeric.

  16. Corrosion behavior of a particulate metal-matrix composite

    SciTech Connect

    Bertolini, L.; Brunella, M.F.; Candiani, S.

    1999-04-01

    The corrosion behavior of a particulate-reinforced metal-matrix composite (MMC) with an Al 6061-T6 (UNS A96061, Al-Mg-Si) matrix and 10 vol% alumina (Al{sub 2}O{sub 3}) particles was studied. The material was tested in different extrusion and forging conditions. Potentiodynamic polarization tests were carried out in aerated and deaerated sodium chloride (NaCl) solutions with concentrations from 0.06 N up to saturation to study pitting corrosion initiation. Three-month immersion tests were performed in aerated solutions. Results showed pitting corrosion initiated in aerated solutions, even for the lower chloride concentration. No significant influence of Al{sub 2}O{sub 3} particles on corrosion susceptibility of the matrix was observed. However, corrosion attacks occurred preferentially in the vicinity of the reinforcing particles. Extrusion or forging treatment did not affect corrosion behavior of the composite material significantly.

  17. Thermo-mechanical response predictions for metal matrix composite laminates

    NASA Technical Reports Server (NTRS)

    Aboudi, J.; Hidde, J. S.; Herakovich, C. T.

    1991-01-01

    An analytical micromechanical model is employed for prediction of the stress-strain response of metal matrix composite laminates subjected to thermomechanical loading. The predicted behavior of laminates is based upon knowledge of the thermomechanical response of the transversely isotropic, elastic fibers and the elastic-viscoplastic, work-hardening matrix. The method is applied to study the behavior of silicon carbide/titanium metal matrix composite laminates. The response of laminates is compared with that of unidirectional lamina. The results demonstrate the effect of cooling from a stress-free temperature and the mismatch of thermal and mechanical properties of the constituent phases on the laminate's subsequent mechanical response. Typical results are presented for a variety of laminates subjected to monotonic tension, monotonic shear and cyclic tensile/compressive loadings.

  18. Metal matrix composite fuel for space radioisotope energy sources

    NASA Astrophysics Data System (ADS)

    Williams, H. R.; Ning, H.; Reece, M. J.; Ambrosi, R. M.; Bannister, N. P.; Stephenson, K.

    2013-02-01

    Radioisotope fuels produce heat that can be used for spacecraft thermal control or converted to electricity. They must retain integrity in the event of destruction or atmospheric entry of the parent spacecraft. Addition of a metal matrix to the actinide oxide could yield a more robust fuel form. Neodymium (III) oxide (Nd2O3) - niobium metal matrix composites were produced using Spark Plasma Sintering; Nd2O3 is a non-radioactive surrogate for americium (III) oxide (Am2O3). Two compositions, 70 and 50 wt% Nd2O3, were mechanically tested under equibiaxial (ring-on-ring) flexure according to ASTM C1499. The addition of the niobium matrix increased the mean flexural strength by a factor of about 2 compared to typical ceramic nuclear fuels, and significantly increased the Weibull modulus to over 20. These improved mechanical properties could result in reduced fuel dispersion in severe accidents and improved safety of space radioisotope power systems.

  19. Organic matrix composition and ultrastructure of eggshell: a comparative study.

    PubMed

    Panheleux, M; Bain, M; Fernandez, M S; Morales, I; Gautron, J; Arias, J L; Solomon, S E; Hincke, M; Nys, Y

    1999-05-01

    1. The avian eggshell is a biomineralised composite ceramic consisting of calcium carbonate embedded in an organic matrix. Matrix components are supposed to be involved in the control of mineralisation, crystallographic texture and biomechanical properties of eggshell. 2. The structure and eggshell matrix composition of various domesticated bird species were compared to gain insight into the universality of the eggshell mineralisation process. 3. The SDS-PAGE profiles of soluble eggshell matrix were specific within groups of birds (a: laying hen, breeder hen, quail, pheasant and possibly turkey; b: guinea fowl; c: duck and goose) but some of the protein bands were common to all groups. 4. Analogies between species were confirmed by Western blotting using hen protein antibodies. Ovocleidin-17 (OC-17) and ovalbumin were revealed in all species (except quail for OC-17). Lysozyme was present only in hen eggshell. Another egg white protein: ovotransferrin showed a positive signal in hens, turkey and quail. Osteopontin was observed in laying and breeder hens and quail. 5. Different proteoglycans were localised to discrete regions within the eggshell. Dermatan sulphate was observed within the matrix of the calcified shell of all species except quail which contained chondroitin-6-sulfate. Keratan sulphate was observed in mammillary bodies of breeder and laying hen, quail, pheasant and turkey while chondroitin sulphate was also present in guinea fowl and duck. 6. The general structural organisation of the different avian eggshells was similar but specific differences were observed in the ultrastructure of the mammillary layer. Species of the same taxonomic family could be grouped according to their structural analogies: breeder hen, turkey and pheasant resembled that of the domestic fowl. Guinea fowl was unique. Goose and duck were quite similar with large and confluent mammillary bodies. 7. Some matrix components are therefore common to eggshells of various species but

  20. Proposed framework for thermomechanical life modeling of metal matrix composites

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Lerch, Bradley A.; Saltsman, James F.

    1993-01-01

    The framework of a mechanics of materials model is proposed for thermomechanical fatigue (TMF) life prediction of unidirectional, continuous-fiber metal matrix composites (MMC's). Axially loaded MMC test samples are analyzed as structural components whose fatigue lives are governed by local stress-strain conditions resulting from combined interactions of the matrix, interfacial layer, and fiber constituents. The metallic matrix is identified as the vehicle for tracking fatigue crack initiation and propagation. The proposed framework has three major elements. First, TMF flow and failure characteristics of in situ matrix material are approximated from tests of unreinforced matrix material, and matrix TMF life prediction equations are numerically calibrated. The macrocrack initiation fatigue life of the matrix material is divided into microcrack initiation and microcrack propagation phases. Second, the influencing factors created by the presence of fibers and interfaces are analyzed, characterized, and documented in equation form. Some of the influences act on the microcrack initiation portion of the matrix fatigue life, others on the microcrack propagation life, while some affect both. Influencing factors include coefficient of thermal expansion mismatch strains, residual (mean) stresses, multiaxial stress states, off-axis fibers, internal stress concentrations, multiple initiation sites, nonuniform fiber spacing, fiber debonding, interfacial layers and cracking, fractured fibers, fiber deflections of crack fronts, fiber bridging of matrix cracks, and internal oxidation along internal interfaces. Equations exist for some, but not all, of the currently identified influencing factors. The third element is the inclusion of overriding influences such as maximum tensile strain limits of brittle fibers that could cause local fractures and ensuing catastrophic failure of surrounding matrix material. Some experimental data exist for assessing the plausibility of the proposed

  1. Characterization and control of the fiber-matrix interface in ceramic matrix composites

    SciTech Connect

    Lowden, R.A.

    1989-03-01

    Fiber-reinforced SiC composites fabricated by thermal-gradient forced-flow chemical-vapor infiltration (FCVI) have exhibited both composite (toughened) and brittle behavior during mechanical property evaluation. Detailed analysis of the fiber-matrix interface revealed that a silica layer on the surface of Nicalon Si-C-O fibers tightly bonds the fiber to the matrix. The strongly bonded fiber and matrix, combined with the reduction in the strength of the fibers that occurs during processing, resulted in the observed brittle behavior. The mechanical behavior of Nicalon/SiC composites has been improved by applying thin coatings (silicon carbide, boron, boron nitride, molybdenum, carbon) to the fibers, prior to densification, to control the interfacial bond. Varying degrees of bonding have been achieved with different coating materials and film thicknesses. Fiber-matrix bond strengths have been quantitatively evaluated using an indentation method and a simple tensile test. The effects of bonding and friction on the mechanical behavior of this composite system have been investigated. 167 refs., 59 figs., 18 tabs.

  2. Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

    PubMed Central

    Jenkins, R. Brian; Joyce, Peter; Mechtel, Deborah

    2017-01-01

    Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay. PMID:28134815

  3. Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors.

    PubMed

    Jenkins, R Brian; Joyce, Peter; Mechtel, Deborah

    2017-01-27

    Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initial tests are conducted on polymer matrix composites reinforced with either carbon or glass fiber with a single optical fiber embedded into each specimen. As many as three sensors in each optical fiber measure the temporal and spatial thermal response of the composite to high energy radiation incident on the surface. Additional tests use a 2 × 2 × 3 array of 12 sensors embedded in a carbon fiber/epoxy composite to simultaneously measure temperature variations at locations on the composite surface and through the thickness. Results indicate that FBGs can be used to rapidly detect temperature gradients in a composite and their location, even for a direct strike of laser radiation on a sensor, when high temperatures can cause a non-uniform thermal response and FBG decay.

  4. Coffee grounds as filler for pectin: Green composites with competitive performances dependent on the UV irradiation.

    PubMed

    Cataldo, Vincenzo Alessandro; Cavallaro, Giuseppe; Lazzara, Giuseppe; Milioto, Stefana; Parisi, Filippo

    2017-08-15

    Novel composite bioplastics were successfully prepared by filling pectin matrix with treated coffee grounds. The amount of coffee dispersed into the pectin was changed within a wide filler range. The morphology of the pectin/coffee hybrid films was studied by microscopic techniques in order to investigate their mesoscopic structure as well as the sizes distribution of the particles dispersed into the matrix. The micrographs showed that the coffee grounds are uniformly dispersed within the polymeric matrix. The morphological characteristics of the biocomposite films were correlated to their properties, such as wettability, water uptake, thermal behavior and mechanical performances. Dynamic mechanical test were conducted as a function of the humidity conditions. As a general result, a worsening of the mechanical performances was induced by the addition of the coffee grounds into the pectin. An additional UV curing treatment was conducted on the pectin/coffee films with the aim to improve their tensile and viscoelastic features. The cured films showed promising and tunable properties that are dependent on both the filler content and the UV irradiation. In particular, the presence of single coffee particles into the pectin matrix renders the UV curing treatment effective in the enhancement of the elasticity as well as the traction resistance, whereas the cured composite films containing coffee clusters showed only more elastic characteristics. With this study, we fabricated pectin/coffee bioplastics with controlled behavior appealing for specific application within the food packaging. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Graphite fiber textile preform/copper matrix composites

    NASA Technical Reports Server (NTRS)

    Filatovs, G. J.

    1993-01-01

    This project has the objective of exploring the use of graphite fiber textile preform/copper matrix composites in spacecraft heat transmitting and radiating components. The preforms are to be fabricated by braiding of tows and when infiltrated with copper will result in a 3-D reinforced, near net shape composite with improved specific properties such as lower density and higher stiffness. It is anticipated that the use of textile technology will result in a more robust preform and consequently better final composite; it is hard to anticipate what performance tradeoffs will result, and these will be explored through testing and characterization.

  6. A comparison of fiber effects on polymer matrix composite oxidation

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.

    1991-01-01

    A number of thermo-oxidative stability studies addressing the effects of fiber reinforcement on composite thermal stability and influence of geometry on the results of aging studies were performed at NASA-Lewis. The information presented herein, a compilation of some results from these studies, shows the influence of the reinforcement fibers on the oxidative degradation of various PMR-15 composites. Reinforcement of graphite and ceramics were studied and three composite oxidation mechanisms were observed. One was a dominant attack of the reinforcement fiber, the second was the aggressive oxidation of the matrix material, and the third was interfacial degradation.

  7. Dual-nanoparticulate-reinforced aluminum matrix composite materials

    NASA Astrophysics Data System (ADS)

    Kwon, Hansang; Cho, Seungchan; Leparoux, Marc; Kawasaki, Akira

    2012-06-01

    Aluminum (Al) matrix composite materials reinforced with carbon nanotubes (CNT) and silicon carbide nanoparticles (nano-SiC) were fabricated by mechanical ball milling, followed by hot-pressing. Nano-SiC was used as an active mixing agent for dispersing the CNTs in the Al powder. The hardness of the produced composites was dramatically increased, up to eight times higher than bulk pure Al, by increasing the amount of nano-SiC particles. A small quantity of aluminum carbide (Al4C3) was observed by TEM analysis and quantified using x-ray diffraction. The composite with the highest hardness values contained some nanosized Al4C3. Along with the CNT and the nano-SiC, Al4C3 also seemed to play a role in the enhanced hardness of the composites. The high energy milling process seems to lead to a homogeneous dispersion of the high aspect ratio CNTs, and of the nearly spherical nano-SiC particles in the Al matrix. This powder metallurgical approach could also be applied to other nanoreinforced composites, such as ceramics or complex matrix materials.

  8. Microstructural Preparation and Examination of Polymer-Matrix Composites

    NASA Technical Reports Server (NTRS)

    Elban, Wayne L.; Rutzebeck, Maddy M.; Small, Ryan A.; Walsh, Adam M.

    1996-01-01

    Adapting procedures widely used in the metallographic characterization of metals and alloys, the microstructural preparation and examination of three polymer-matrix composites (PMC's) is described. The materials investigated contained either hollow ceramic filler particles or woven, continuous carbon/graphite fibers. Since the two particulate composites were considered to be isotropic, only one sample orientation was prepared. For the fiber composite, both longitudinal and planar orientations were studied. Once prepared, the samples were examined using reflected light microscopy. A number of microstructural features were evaluated qualitatively, including porosity and cracks, filler-matrix interfacial bonding, filler particle characteristics (shape, size, size distribution, and loading variation) and fiber characteristics (orientation, packing variation, and discontinuities).

  9. Microstructural Preparation and Examination of Polymer-Matrix Composites

    NASA Technical Reports Server (NTRS)

    Elban, Wayne L.; Rutzebeck, Maddy M.; Small, Ryan A.; Walsh, Adam M.

    1996-01-01

    Adapting procedures widely used in the metallographic characterization of metals and alloys, the microstructural preparation and examination of three polymer-matrix composites (PMC's) is described. The materials investigated contained either hollow ceramic filler particles or woven, continuous carbon/graphite fibers. Since the two particulate composites were considered to be isotropic, only one sample orientation was prepared. For the fiber composite, both longitudinal and planar orientations were studied. Once prepared, the samples were examined using reflected light microscopy. A number of microstructural features were evaluated qualitatively, including porosity and cracks, filler-matrix interfacial bonding, filler particle characteristics (shape, size, size distribution, and loading variation) and fiber characteristics (orientation, packing variation, and discontinuities).

  10. 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.

  11. 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.

  12. 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.

  13. Update on CMH-17 Volume 5 Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Andrulonis, Rachael; Kiser, J. Douglas; David, Kaia E.; Davies, Curtis R.; Ashforth, Cindy

    2017-01-01

    A wide range of issues must be addressed during the process of certifying CMC (ceramic matrix composite) components for use in commercial aircraft. The Composite Materials Handbook-17, Volume 5, Revision A on ceramic matrix composites has just been revised to help support FAA certification of CMCs for elevated temperature applications. The handbook supports the development and use of CMCs through publishing and maintaining proven, reliable engineering information and standards that have been thoroughly reviewed. Volume 5 contains detailed sections describing CMC materialsprocessing design, analysisguidelines, testing procedures, and data analysis and acceptance. A review of the content of this latest revision will be presented along with a description of how CMH-17, Volume 5 could be used by the FAA (Federal Aviation Administration) and others in the future.

  14. Effects of ArF excimer laser irradiation of dentin on the tensile bonding strength to composite resin.

    PubMed

    Sano, Kazunobu; Tonami, Ken-Ichi; Ichinose, Shizuko; Araki, Kouji

    2012-02-01

    The purpose of the study was to evaluate the effects of argon fluoride (ArF) excimer laser irradiation on the tensile bonding strength (TBS) of dentin to composite resin. Dental lasers use a photothermal process, which potentially entails risk of tissue damage caused by heat affecting the bond strength of resins. The ArF excimer laser functions by a photochemical process in which the energy of photons directly cuts covalent bonds in molecules without generating heat. Twenty extracted human molars were sectioned perpendicularly to the tooth axis to expose a flat dentin surface. The surfaces were treated with various combinations of ArF excimer laser irradiation, primer treatment, and bonding treatment. After composite resin was built up on the treated dentin surface, specimens with a 1×1 mm bonding interface were prepared and subjected to TBS tests. Treated dentin surfaces were also observed using transmission electron microscopy (TEM). Specimens that underwent laser irradiation followed by bonding treatment had a TBS that did not differ significantly from that of specimens that received conventional treatment, with or without priming. TEM observations showed sectioned and dispersed collagen matrix in the hybrid layer after laser irradiation, priming, and bonding, but no hybrid layer after laser irradiation and bonding at the treated dentin surface. The TBS of conditioning with ArF excimer laser irradiation was identical to that with conventional treatment when bonding was used. The bonding mechanism with the ArF irradiation differed from that of conventional bonding depending upon dentin hybridization.

  15. Mechanical properties of SiC composites neutron irradiated under light water reactor relevant temperature and dose conditions

    NASA Astrophysics Data System (ADS)

    Koyanagi, Takaaki; Katoh, Yutai

    2017-10-01

    Silicon carbide (SiC) fiber-reinforced SiC matrix (SiC/SiC) composites are being actively investigated for use in accident-tolerant core structures of light water reactors (LWRs). Owing to the limited number of irradiation studies previously conducted at LWR-coolant temperature, this study examined SiC/SiC composites following neutron irradiation at 230-340 °C to 2.0 and 11.8 dpa in the High Flux Isotope Reactor. The investigated materials were chemical vapor infiltrated (CVI) SiC/SiC composites with three different reinforcement fibers. The fiber materials were monolayer pyrolytic carbon (PyC) -coated Hi-Nicalon™ Type-S (HNS), Tyranno™ SA3 (SA3), and SCS-Ultra™ (SCS) SiC fibers. The irradiation resistance of these composites was investigated based on flexural behavior, dynamic Young's modulus, swelling, and microstructures. There was no notable mechanical properties degradation of the irradiated HNS and SA3 SiC/SiC composites except for reduction of the Young's moduli by up to 18%. The microstructural stability of these composites supported the absence of degradation. In addition, no progressive swelling from 2.0 to 11.8 dpa was confirmed for these composites. On the other hand, the SCS composite showed significant mechanical degradation associated with cracking within the fiber. This study determined that SiC/SiC composites with HNS or SA3 SiC/SiC fibers, a PyC interphase, and a CVI SiC matrix retain their properties beyond the lifetime dose for LWR fuel cladding at the relevant temperature.

  16. Mechanical properties of SiC composites neutron irradiated under light water reactor relevant temperature and dose conditions

    DOE PAGES

    Koyanagi, Takaaki; Katoh, Yutai

    2017-07-04

    Silicon carbide (SiC) fiber–reinforced SiC matrix (SiC/SiC) composites are being actively investigated for use in accident-tolerant core structures of light water reactors (LWRs). Owing to the limited number of irradiation studies previously conducted at LWR-coolant temperature, this paper examined SiC/SiC composites following neutron irradiation at 230–340 °C to 2.0 and 11.8 dpa in the High Flux Isotope Reactor. The investigated materials were chemical vapor infiltrated (CVI) SiC/SiC composites with three different reinforcement fibers. The fiber materials were monolayer pyrolytic carbon (PyC) -coated Hi-Nicalon™ Type-S (HNS), Tyranno™ SA3 (SA3), and SCS-Ultra™ (SCS) SiC fibers. The irradiation resistance of these composites wasmore » investigated based on flexural behavior, dynamic Young's modulus, swelling, and microstructures. There was no notable mechanical properties degradation of the irradiated HNS and SA3 SiC/SiC composites except for reduction of the Young's moduli by up to 18%. The microstructural stability of these composites supported the absence of degradation. In addition, no progressive swelling from 2.0 to 11.8 dpa was confirmed for these composites. On the other hand, the SCS composite showed significant mechanical degradation associated with cracking within the fiber. Finally, this study determined that SiC/SiC composites with HNS or SA3 SiC/SiC fibers, a PyC interphase, and a CVI SiC matrix retain their properties beyond the lifetime dose for LWR fuel cladding at the relevant temperature.« less

  17. Cellular Magnesium Matrix Foam Composites for Mechanical Damping Applications

    NASA Astrophysics Data System (ADS)

    Shunmugasamy, Vasanth Chakravarthy; Mansoor, Bilal; Gupta, Nikhil

    2016-01-01

    The damping characteristics of metal alloys and metal matrix composites are relevant to the automotive, aerospace, and marine structures. Use of lightweight materials can help in increasing payload capacity and in decreasing fuel consumption. Lightweight composite materials possessing high damping capabilities that can be designed as structural members can greatly benefit in addressing these needs. In this context, the damping properties of lightweight metals such as aluminum and magnesium and their respective composites have been studied in the existing literature. This review focuses on analyzing the damping properties of aluminum and magnesium alloys and their cellular composites. The damping properties of various lightweight alloys and composites are compared on the basis of their density to understand the potential for weight saving in structural applications. Magnesium alloys are observed to possess better damping properties in comparison to aluminum. However, aluminum matrix syntactic foams reinforced with silicon carbide hollow particles possess a damping capacity and density comparable to magnesium alloy. By using the data presented in the study, composites with specific compositions and properties can be selected for a given application. In addition, the comparison of the results helps in identifying the areas where attention needs to be focused to address the future needs.

  18. Stochastic-Strength-Based Damage Simulation Tool for Ceramic Matrix and Polymer Matrix Composite Structures

    NASA Technical Reports Server (NTRS)

    Nemeth, Noel N.; Bednarcyk, Brett A.; Pineda, Evan J.; Walton, Owen J.; Arnold, Steven M.

    2016-01-01

    Stochastic-based, discrete-event progressive damage simulations of ceramic-matrix composite and polymer matrix composite material structures have been enabled through the development of a unique multiscale modeling tool. This effort involves coupling three independently developed software programs: (1) the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC), (2) the Ceramics Analysis and Reliability Evaluation of Structures Life Prediction Program (CARES/ Life), and (3) the Abaqus finite element analysis (FEA) program. MAC/GMC contributes multiscale modeling capabilities and micromechanics relations to determine stresses and deformations at the microscale of the composite material repeating unit cell (RUC). CARES/Life contributes statistical multiaxial failure criteria that can be applied to the individual brittle-material constituents of the RUC. Abaqus is used at the global scale to model the overall composite structure. An Abaqus user-defined material (UMAT) interface, referred to here as "FEAMAC/CARES," was developed that enables MAC/GMC and CARES/Life to operate seamlessly with the Abaqus FEA code. For each FEAMAC/CARES simulation trial, the stochastic nature of brittle material strength results in random, discrete damage events, which incrementally progress and lead to ultimate structural failure. This report describes the FEAMAC/CARES methodology and discusses examples that illustrate the performance of the tool. A comprehensive example problem, simulating the progressive damage of laminated ceramic matrix composites under various off-axis loading conditions and including a double notched tensile specimen geometry, is described in a separate report.

  19. Fibre-matrix bond strength studies of glass, ceramic, and metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grande, D. H.; Mandell, J. F.; Hong, K. C. C.

    1988-01-01

    An indentation test technique for compressively loading the ends of individual fibers to produce debonding has been applied to metal, glass, and glass-ceramic matrix composites; bond strength values at debond initiation are calculated using a finite-element model. Results are correlated with composite longitudinal and interlaminar shear behavior for carbon and Nicalon fiber-reinforced glasses and glass-ceramics including the effects of matrix modifications, processing conditions, and high-temperature oxidation embrittlement. The data indicate that significant bonding to improve off-axis and shear properties can be tolerated before the longitudinal behavior becomes brittle. Residual stress and other mechanical bonding effects are important, but improved analyses and multiaxial interfacial failure criteria are needed to adequately interpret bond strength data in terms of composite performance.

  20. Fibre-matrix bond strength studies of glass, ceramic, and metal matrix composites

    NASA Technical Reports Server (NTRS)

    Grande, D. H.; Mandell, J. F.; Hong, K. C. C.

    1988-01-01

    An indentation test technique for compressively loading the ends of individual fibers to produce debonding has been applied to metal, glass, and glass-ceramic matrix composites; bond strength values at debond initiation are calculated using a finite-element model. Results are correlated with composite longitudinal and interlaminar shear behavior for carbon and Nicalon fiber-reinforced glasses and glass-ceramics including the effects of matrix modifications, processing conditions, and high-temperature oxidation embrittlement. The data indicate that significant bonding to improve off-axis and shear properties can be tolerated before the longitudinal behavior becomes brittle. Residual stress and other mechanical bonding effects are important, but improved analyses and multiaxial interfacial failure criteria are needed to adequately interpret bond strength data in terms of composite performance.

  1. Electron Beam-Cure Polymer Matrix Composites: Processing and Properties

    NASA Technical Reports Server (NTRS)

    Wrenn, G.; Frame, B.; Jensen, B.; Nettles, A.

    2001-01-01

    Researchers from NASA and Oak Ridge National Laboratory are evaluating a series of electron beam curable composites for application in reusable launch vehicle airframe and propulsion systems. Objectives are to develop electron beam curable composites that are useful at cryogenic to elevated temperatures (-217 C to 200 C), validate key mechanical properties of these composites, and demonstrate cost-saving fabrication methods at the subcomponent level. Electron beam curing of polymer matrix composites is an enabling capability for production of aerospace structures in a non-autoclave process. Payoffs of this technology will be fabrication of composite structures at room temperature, reduced tooling cost and cure time, and improvements in component durability. This presentation covers the results of material property evaluations for electron beam-cured composites made with either unidirectional tape or woven fabric architectures. Resin systems have been evaluated for performance in ambient, cryogenic, and elevated temperature conditions. Results for electron beam composites and similar composites cured in conventional processes are reviewed for comparison. Fabrication demonstrations were also performed for electron beam-cured composite airframe and propulsion piping subcomponents. These parts have been built to validate manufacturing methods with electron beam composite materials, to evaluate electron beam curing processing parameters, and to demonstrate lightweight, low-cost tooling options.

  2. Inelastic response of metal matrix composites under biaxial loading

    NASA Technical Reports Server (NTRS)

    Lissenden, C. J.; Mirzadeh, F.; Pindera, M.-J.; Herakovich, C. T.

    1991-01-01

    Theoretical predictions and experimental results were obtained for inelastic response of unidirectional and angle ply composite tubes subjected to axial and torsional loading. The composite material consist of silicon carbide fibers in a titanium alloy matrix. This material is known to be susceptible to fiber matrix interfacial damage. A method to distinguish between matrix yielding and fiber matrix interfacial damage is suggested. Biaxial tests were conducted on the two different layup configurations using an MTS Axial/Torsional load frame with a PC based data acquisition system. The experimentally determined elastic moduli of the SiC/Ti system are compared with those predicted by a micromechanics model. The test results indicate that fiber matrix interfacial damage occurs at relatively low load levels and is a local phenomenon. The micromechanics model used is the method of cells originally proposed by Aboudi. Finite element models using the ABACUS finite element program were used to study end effects and fixture specimen interactions. The results to date have shown good correlation between theory and experiment for response prior to damage initiation.

  3. Thermal expansion behavior of LDEF metal matrix composites

    NASA Technical Reports Server (NTRS)

    Le, Tuyen D.; Steckel, Gary L.

    1993-01-01

    The thermal expansion behavior of Long Duration Exposure Facility (LDEF) metal matrix composite materials was studied by (1) analyzing the flight data that was recorded on orbit to determine the effects of orbital time and heating/cooling rates on the performance of the composite materials, and (2) characterizing and comparing the thermal expansion behavior of post-flight LDEF and lab-control samples. The flight data revealed that structures in space are subjected to nonuniform temperature distributions, and thermal conductivity of a material is an important factor in establishing a uniform temperature distribution and avoiding thermal distortion. The flight and laboratory data showed that both Gr/Al and Gr/Mg composites were stabilized after prolonged thermal cycling on orbit. However, Gr/Al composites showed more stable thermal expansion behavior than Gr/Mg composites and offer advantages for space structures particularly where very tight thermal stability requirements in addition to high material performance must be met.

  4. Titanium matrix composite thermomechanical fatigue analysis method development

    NASA Astrophysics Data System (ADS)

    Ball, Dale Leray

    1998-12-01

    The results of complementary experimental and analytical investigations of thermomechanical fatigue of both unidirectional and crossply titanium matrix composite laminates are presented. Experimental results are given for both isothermal and thermomechanical fatigue tests which were based on simple, constant amplitude mechanical and thermal loading profiles. The discussion of analytical methods includes the development of titanium matrix composite laminate constitutive relationships, the development of damage models and the integration of both into a thermomechanical fatigue analysis algorithm. The technical approach begins with a micro-mechanical formulation of lamina response. Material behavior at the ply level is based on a mechanics of materials approach using thermo-elastic fibers and an thermo-elasto-viscoplastic matrix. The effects of several types of distributed damage are included in the material constitutive relationships at the ply level in the manner of continuum damage mechanics. The modified ply constitutive relationships are then used in an otherwise unmodified classical lamination theory treatment of laminate response. Finally, simple models for damage progression are utilized in an analytical framework which recalculates response and increments damage sizes at every load point in an applied thermal/mechanical load history. The model is used for the prediction of isothermal fatigue and thermomechanical fatigue life of unnotched, unidirectional [0°]4 and crossply [0°/90°]s titanium matrix composite laminates. The results of corresponding isothermal and thermomechanical fatigue tests are presented in detail and the correlation between experimental and analytical results is established in certain cases.

  5. Modeling for Matrix Multicracking Evolution of Cross-ply Ceramic-Matrix Composites Using Energy Balance Approach

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    The matrix multicracking evolution of cross-ply ceramic-matrix composites (CMCs) has been investigated using energy balance approach. The multicracking of cross-ply CMCs was classified into five modes, i.e., (1) mode 1: transverse multicracking; (2) mode 2: transverse multicracking and matrix multicracking with perfect fiber/matrix interface bonding; (3) mode 3: transverse multicracking and matrix multicracking with fiber/matrix interface debonding; (4) mode 4: matrix multicracking with perfect fiber/matrix interface bonding; and (5) mode 5: matrix multicracking with fiber/matrix interface debonding. The stress distributions of four cracking modes, i.e., mode 1, mode 2, mode 3 and mode 5, are analysed using shear-lag model. The matrix multicracking evolution of mode 1, mode 2, mode 3 and mode 5, has been determined using energy balance approach. The effects of ply thickness and fiber volume fraction on matrix multicracking evolution of cross-ply CMCs have been investigated.

  6. 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.

  7. Characterization of selected LDEF polymer matrix resin composite materials

    NASA Technical Reports Server (NTRS)

    Young, Philip R.; Slemp, Wayne S.; Witte, William G., Jr.; Shen, James Y.

    1991-01-01

    The characterization of selected graphite fiber reinforced epoxy (934 and 5208) and polysulfone (P1700) matrix resin composite materials which received 5 years and 10 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. Resin loss and a decrease in mechanical performance as well as dramatic visual effects were observed. However, chemical characterization including infrared, thermal, and selected solution property measurements showed that the molecular structure of the polymeric matrix had not changed significantly in response to this exposure. The potential effect of a silicon-containing molecular contamination of these specimens is addressed.

  8. Nonlinear laminate analysis for metal matrix fiber composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1981-01-01

    A nonlinear laminate analysis is described for predicting the mechanical behavior (stress-strain relationships) of angleplied laminates in which the matrix is strained nonlinearly by both the residual stress and the mechanical load and in which additional nonlinearities are induced due to progressive fiber fractures and ply relative rotations. The nonlinear laminate analysis (NLA) is based on linear composite mechanics and a piece wise linear laminate analysis to handle the nonlinear responses. Results obtained by using this nonlinear analysis on boron fiber/aluminum matrix angleplied laminates agree well with experimental data. The results shown illustrate the in situ ply stress-strain behavior and synergistic strength enhancement.

  9. Evaluation of 2D ceramic matrix composites in aeroconvective environments

    NASA Technical Reports Server (NTRS)

    Riccitiello, Salvatore R.; Love, Wendell L.; Balter-Peterson, Aliza

    1992-01-01

    An evaluation is conducted of a novel ceramic-matrix composite (CMC) material system for use in the aeroconvective-heating environments encountered by the nose caps and wing leading edges of such aerospace vehicles as the Space Shuttle, during orbit-insertion and reentry from LEO. These CMCs are composed of an SiC matrix that is reinforced with Nicalon, Nextel, or carbon refractory fibers in a 2D architecture. The test program conducted for the 2D CMCs gave attention to their subsurface oxidation.

  10. Properties of particle phases for metal-matrix-composite design.

    PubMed

    Baron, C; Springer, H

    2017-06-01

    Successful metallurgical design of metal-matrix-composites relies on the knowledge of the intrinsic property profiles of the metal matrix and especially the compounds employed for particles, whiskers or fibres. In this work we compiled the key properties melting point, bulk modulus, shear modulus, Young׳s modulus, density, hardness, Poisson׳s ratio and structure/space group from the widespread literature data for the most relevant compound types, i.e. borides, carbo-borides, carbides, oxides, nitrides and intermetallic phases.

  11. Simulation of Fatigue Behavior of High Temperature Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Tong, Mike T.; Singhal, Suren N.; Chamis, Christos C.; Murthy, Pappu L. N.

    1996-01-01

    A generalized relatively new approach is described for the computational simulation of fatigue behavior of high temperature metal matrix composites (HT-MMCs). This theory is embedded in a specialty-purpose computer code. The effectiveness of the computer code to predict the fatigue behavior of HT-MMCs is demonstrated by applying it to a silicon-fiber/titanium-matrix HT-MMC. Comparative results are shown for mechanical fatigue, thermal fatigue, thermomechanical (in-phase and out-of-phase) fatigue, as well as the effects of oxidizing environments on fatigue life. These results show that the new approach reproduces available experimental data remarkably well.

  12. Multiphase matrix polymers for carbon-fiber composites

    SciTech Connect

    Bascom, W.D.; Gweon, S.Y.; Grande, D.

    1993-12-31

    The effect of different matrix polymers on the impact resistance of carbon-fiber-reinforced polymers is reviewed. These polymers include unmodified, tetrafunctional epoxies, elastomer-modified epoxies, epoxies plasticized with low levels of thermoplastics, thermoplastics, and thermoplastic-modified thermosets (TMT). The results of some recent work on the impact resistance of TMT matrix composites is discussed. The TMTs were of two types: Thermoplastic particles interlayered between plies and co-continuous interpenetrating network polymers. Suppression of interlaminar longitudinal cracking was found to correlate with improved resistance to impact damage. 17 refs., 17 figs., 4 tabs.

  13. Characterization of selected LDEF polymer matrix resin composite materials

    NASA Technical Reports Server (NTRS)

    Young, Philip R.; Slemp, Wayne S.; Witte, William G., Jr.; Shen, James Y.

    1991-01-01

    The characterization of selected graphite fiber reinforced epoxy (934 and 5208) and polysulfone (P1700) matrix resin composite materials which received 5 years and 10 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. Resin loss and a decrease in mechanical performance as well as dramatic visual effects were observed. However, chemical characterization including infrared, thermal, and selected solution property measurements showed that the molecular structure of the polymeric matrix had not changed significantly in response to this exposure. The potential effect of a silicon-containing molecular contamination of these specimens is addressed.

  14. Matrix cracking of fiber-reinforced ceramic composites in shear

    NASA Astrophysics Data System (ADS)

    Rajan, Varun P.; Zok, Frank W.

    2014-12-01

    The mechanics of cracking in fiber-reinforced ceramic matrix composites (CMCs) under general loadings remains incomplete. The present paper addresses one outstanding aspect of this problem: the development of matrix cracks in unidirectional plies under shear loading. To this end, we develop a model based on potential energy differences upstream and downstream of a fully bridged steady-state matrix crack. Through a combination of analytical solutions and finite element simulations of the constituent stresses before and after cracking, we identify the dominant stress components that drive crack growth. We show that, when the axial slip lengths are much larger than the fiber diameter and when interfacial slip precedes cracking, the shear stresses in the constituents are largely unaffected by the presence of the crack; the changes that do occur are confined to a 'core' region within a distance of about one fiber diameter from the crack plane. Instead, the driving force for crack growth derives mainly from the axial stresses-tensile in the fibers and compressive in the matrix-that arise upon cracking. These stresses are well-approximated by solutions based on shear-lag analysis. Combining these solutions with the governing equation for crack growth yields an analytical estimate of the critical shear stress for matrix cracking. An analogous approach is used in deriving the critical stresses needed for matrix cracking under arbitrary in-plane loadings. The applicability of these results to cross-ply CMC laminates is briefly discussed.

  15. Corrosion protection of aluminum metal-matrix composites

    SciTech Connect

    Greene, H.J.; Mansfeld, F.

    1997-12-01

    Corrosion protection of aluminum metal-matrix composites (MMC) by anodizing treatments was investigated. Electrochemical behavior of MMC without protection also was investigated. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements were used to characterize the properties of protective surface layers. Materials studied were Al 6061/SiC, alloy A356/SiC, Al 2009/SiC, Al 2014/Al{sub 2}O{sub 3} and Al 6061/Al{sub 2}O{sub 3} with various reinforcement concentrations. The MMC had similar corrosion (E{sub corr}) and pitting (E{sub pit}) potentials as the matrix alloy. The cathodic current density for oxygen reduction in 0.5% N sodium chloride increased for Al 6061/SiC MMC with reinforcement concentration, which was attributed to electrochemically active interfaces between the matrix and the reinforcement particles. Anodizing and hot-water sealing were less effective for MMC than for the matrix aluminum alloys. The reinforcement particles produced a more porous structure of the anodized layer for MMC. Improved results were noted for dichromate sealing, where chromium (Cr{sup 6+}) in the pores of the outer oxide acted as an inhibitor. The effectiveness of corrosion protection methods decreased with increasing reinforcement concentration and was a function of the matrix alloy but not of the reinforcement material. The observed reduction in corrosion protection was believed to result from corrosion-susceptible interfaces formed between the reinforcement particles and the matrix.

  16. Organic matrix composite protective coatings for space applications

    NASA Technical Reports Server (NTRS)

    Dursch, Harry W.; George, Pete

    1995-01-01

    Successful use of composites in low earth orbit (LEO) depends on their ability to survive long-term exposure to atomic oxygen (AO), ultraviolet radiation, charged particle radiation, thermal cycling, and micrometeoroid and space debris. The AO environment is especially severe for unprotected organic matrix composites surfaces in LEO. Ram facing unprotected graphite/epoxy flown on the 69-month Long Duration Exposure Facility (LDEF) mission lost up to one ply of thickness (5 mils) resulting in decreased mechanical properties. The expected AO fluence of the 30 year Space Station Alpha mission is approximately 20 times that seen on LDEF. This exposure would result in significant material loss of unprotected ram facing organic matrix composites. Several protective coatings for composites were flown on LDEF including anodized aluminum, vacuum deposited coatings, a variety of thermal control coatings, metalized Teflon, and leafing aluminum. Results from the testing and analysis of the coated and uncoated composite specimens flown on LDEF's leading and trailing edges provide the baseline for determining the effectiveness of protectively coated composites in LEO. In addition to LDEF results, results from shuttle flight experiments and ground based testing will be discussed.

  17. Shock Interaction Studies on Glass Fibre Reinforced Epoxy Matrix Composites

    NASA Astrophysics Data System (ADS)

    Reddy, K. P. J.; Jagadeesh, G.; Jayaram, V.; Reddy, B. Harinath; Madhu, V.; Reddy, C. Jaya Rami

    Glass fibre reinforced polymer matrix composites are being extensively used for structural applications both in civil and defense sectors, owing to their high specific strength, stiffness and good energy absorbing capability. Understanding the dynamic response of these composites on shock loading is very essential for effective design of structures resistant to blast loads. In the present study, E- glass/epoxy composite laminate has been fabricated and evaluated for their mechanical properties such as tensile strength, flexural strength and inter laminar shear strength (ILSS). Further, dynamic response of E-glass laminates is presently studied by shock loading. When E-glass composite subjected to peak shock reflected pressure of 7.2 MPa and estimated temperature of about 14000 K for short duration, it underwent surface discolorations and charring of epoxy matrix. Post test analysis of the composite sample was carried out to study the damage analysis using Scanning Electron Microscope (SEM), changes in thermal properties of composites using Dynamic Mechanical Analyzer (DMA) and Thermo-Gravimetric Analyzer (TGA). The results of these investigations are discussed in this paper.

  18. Prediction of high temperature metal matrix composite ply properties

    NASA Technical Reports Server (NTRS)

    Caruso, J. J.; Chamis, C. C.

    1988-01-01

    The application of the finite element method (superelement technique) in conjunction with basic concepts from mechanics of materials theory is demonstrated to predict the thermomechanical behavior of high temperature metal matrix composites (HTMMC). The simulated behavior is used as a basis to establish characteristic properties of a unidirectional composite idealized an as equivalent homogeneous material. The ply properties predicted include: thermal properties (thermal conductivities and thermal expansion coefficients) and mechanical properties (moduli and Poisson's ratio). These properties are compared with those predicted by a simplified, analytical composite micromechanics model. The predictive capabilities of the finite element method and the simplified model are illustrated through the simulation of the thermomechanical behavior of a P100-graphite/copper unidirectional composite at room temperature and near matrix melting temperature. The advantage of the finite element analysis approach is its ability to more precisely represent the composite local geometry and hence capture the subtle effects that are dependent on this. The closed form micromechanics model does a good job at representing the average behavior of the constituents to predict composite behavior.

  19. Glass matrix composites from coal flyash and waste glass

    SciTech Connect

    Boccaccini, A.R.; Buecker, M.; Bossert, J.; Marszalek, K.

    1997-12-31

    Glass matrix composites have been fabricated from waste materials by means of powder technology. Flyash from coal power stations and waste glass, residue of float glass production, were used. Commercial alumina platelets were employed as the reinforcing component. For flyash contents up to 20% by weight nearly fully dense compacts could be fabricated by using relatively low sintering temperatures (650 C). For higher flyash contents the densification was hindered due to the presence of crystalline particles in the as-received flyash, which jeopardized the viscous flow densification mechanism. The addition of alumina platelets resulted in better mechanical properties of the composites than those of the unreinforced matrix, despite a residual porosity present. Young`s modulus, modulus of rupture, hardness and fracture toughness increase with platelet volume fraction. The low brittleness index of the composites suggests that the materials have good machinability. A qualitative analysis of the wear behavior showed that the composite containing 20% by volume platelet addition has a higher wear resistance than the unreinforced matrix. Overall, the results indicate that the materials may compete with conventional glasses and glass-ceramics in technical applications.

  20. Rapid Prototyping of Continuous Fiber Reinforced Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, R.; Green, C.; Phillips, T.; Cipriani, R.; Yarlagadda, S.; Gillespie, J. W., Jr.; Effinger, M.; Cooper, K. C.

    2003-01-01

    For ceramics to be used as structural components in high temperature applications, their fracture toughness is improved by embedding continuous ceramic fibers. Ceramic matrix composite (CMC) materials allow increasing the overall operating temperature, raising the temperature safety margins, avoiding the need for cooling, and improving the damping capacity, while reducing the weight at the same time. They also need to be reliable and available in large quantities as well. In this paper, an innovative rapid prototyping technique to fabricate continuous fiber reinforced ceramic matrix composites is described. The process is simple, robust and will be widely applicable to a number of high temperature material systems. This technique was originally developed at the University of Delaware Center for Composite Materials (UD-CCM) for rapid fabrication of polymer matrix composites by a technique called automated tow placement or ATP. The results of mechanical properties and microstructural characterization are presented, together with examples of complex shapes and parts. It is believed that the process will be able to create complex shaped parts at an order of magnitude lower cost than current chemical vapor infiltration (CVI) and polymer impregnation and pyrolysis (PIP) processes.

  1. Rapid Prototyping of Continuous Fiber Reinforced Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, R.; Green, C.; Phillips, T.; Cipriani, R.; Yarlagadda, S.; Gillespie, J.; Effinger, M.; Cooper, K. C.; Gordon, Gail (Technical Monitor)

    2002-01-01

    For ceramics to be used as structural components in high temperature applications, their fracture toughness is improved by embedding continuous ceramic fibers. Ceramic matrix composite (CMC) materials allow increasing the overall operating temperature, raising the temperature safety margins, avoiding the need for cooling, and improving the damping capacity, while reducing the weight at the same time. They also need to be reliable and available in large quantities as well. In this paper, an innovative rapid prototyping technique to fabricate continuous fiber reinforced ceramic matrix composites is described. The process is simple, robust and will be widely applicable to a number of high temperature material systems. This technique was originally developed at the University of Delaware Center for Composite Materials (UD-CCM) for rapid fabrication of polymer matrix composites by a technique called automated tow placement or ATP. The results of mechanical properties and microstructural characterization are presented, together with examples of complex shapes and parts. It is believed that the process will be able to create complex shaped parts at an order of magnitude lower cost than current CVI and PIP processes.

  2. A honeycomb composite of mollusca shell matrix and calcium alginate.

    PubMed

    You, Hua-jian; Li, Jin; Zhou, Chan; Liu, Bin; Zhang, Yao-guang

    2016-03-01

    A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205-496% and 417-586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  3. Effects of Fiber/Matrix Interface and its Composition on Mechanical Properties of Hi Nicalon/Celsian Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Eldridge, Jeffrey I.

    1998-01-01

    Fiber-reinforced ceramic matrix composites (CMC) are prospective candidate materials for high temperature structural applications in aerospace, energy conservation, power generation, nuclear, petrochemical, and other industries. At NASA Lewis, we are investigating celsian matrix composites reinforced with various types of silicon carbide fibers. The objective of the present study was to investigate the effects of fiber/matrix interface and its composition on the mechanical properties of silicon carbide (Hi-Nicalon) fiber-reinforced celsian matrix composites.

  4. Effects of Fiber/Matrix Interface and its Composition on Mechanical Properties of Hi Nicalon/Celsian Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Eldridge, Jeffrey I.

    1998-01-01

    Fiber-reinforced ceramic matrix composites (CMC) are prospective candidate materials for high temperature structural applications in aerospace, energy conservation, power generation, nuclear, petrochemical, and other industries. At NASA Lewis, we are investigating celsian matrix composites reinforced with various types of silicon carbide fibers. The objective of the present study was to investigate the effects of fiber/matrix interface and its composition on the mechanical properties of silicon carbide (Hi-Nicalon) fiber-reinforced celsian matrix composites.

  5. Formation and Characterization of Au/TiO{sub 2} NanoComposite by Laser Irradiation

    SciTech Connect

    Motamedi, Asma; Hajiesmaeilbaigi, Fereshteh

    2011-12-26

    Nanosized noble metal particles and dielectric matrix composite materials have attracted extensive attention due to their large third-order nonlinear susceptibility and ultrafast response properties, and have great potential for applications in optical devices. In this study, composite Au/TiO{sub 2} nanoparticles were synthesized by laser irradiation. Characterization of the composite particles by means of UV-Vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and atomic force microscopy (AFM) was carried out. We have successfully produced composite Au/TiO{sub 2} nanoparticles by laser ablation of metal gold plate in TiO{sub 2} sol. The red shift of 30 nm in the surface plasmon band of Au is found due to the refractive index of TiO{sub 2}. The surrounding TiO{sub 2} matrix is amorphous, but upon heat treatment becomes a crystalline oxide. Various morphologies of particles are visible, including circular, hexagonal and triangular projection; circular and thus spherical particles being the most common, which were confirm by the TEM images. A large size distribution of particles is visible in TEM images; the average grain size was measured 35 nm, which was confirmed by X-ray diffraction studies.

  6. Prediction of thermal conductivity for irradiated SiC/SiC composites by informing continuum models with molecular dynamics data

    NASA Astrophysics Data System (ADS)

    Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.

    2014-05-01

    This article proposes a new method to estimate the thermal conductivity of SiC/SiC composites subjected to neutron irradiation. The modeling method bridges different scales from the atomic scale to the scale of a 2D SiC/SiC composite. First, it computes the irradiation-induced point defects in perfect crystalline SiC using molecular dynamics (MD) simulations to compute the defect thermal resistance as a function of vacancy concentration and irradiation dose. The concept of defect thermal resistance is explored explicitly in the MD data using vacancy concentrations and thermal conductivity decrements due to phonon scattering. Point defect-induced swelling for chemical vapor deposited (CVD) SiC as a function of irradiation dose is approximated by scaling the corresponding MD results for perfect crystal β-SiC to experimental data for CVD-SiC at various temperatures. The computed thermal defect resistance, thermal conductivity as a function of grain size, and definition of defect thermal resistance are used to compute the thermal conductivities of CVD-SiC, isothermal chemical vapor infiltrated (ICVI) SiC and nearly-stoichiometric SiC fibers. The computed fiber and ICVI-SiC matrix thermal conductivities are then used as input for an Eshelby-Mori-Tanaka approach to compute the thermal conductivities of 2D SiC/SiC composites subjected to neutron irradiation within the same irradiation doses. Predicted thermal conductivities for an irradiated Tyranno-SA/ICVI-SiC composite are found to be comparable to available experimental data for a similar composite ICVI-processed with these fibers.

  7. Prediction of Thermal Conductivity for Irradiated SiC/SiC Composites by Informing Continuum Models with Molecular Dynamics Data

    SciTech Connect

    Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.

    2014-05-01

    This article proposes a new method to estimate the thermal conductivity of SiC/SiC composites subjected to neutron irradiation. The modeling method bridges different scales from the atomic scale to the scale of a 2D SiC/SiC composite. First, it studies the irradiation-induced point defects in perfect crystalline SiC using molecular dynamics (MD) simulations to compute the defect thermal resistance as a function of vacancy concentration and irradiation dose. The concept of defect thermal resistance is explored explicitly in the MD data using vacancy concentrations and thermal conductivity decrements due to phonon scattering. Point defect-induced swelling for chemical vapor deposited (CVD) SiC as a function of irradiation dose is approximated by scaling the corresponding MD results for perfect crystal β-SiC to experimental data for CVD-SiC at various temperatures. The computed thermal defect resistance, thermal conductivity as a function of grain size, and definition of defect thermal resistance are used to compute the thermal conductivities of CVD-SiC, isothermal chemical vapor infiltrated (ICVI) SiC and nearly-stoichiometric SiC fibers. The computed fiber and ICVI-SiC matrix thermal conductivities are then used as input for an Eshelby-Mori-Tanaka approach to compute the thermal conductivities of 2D SiC/SiC composites subjected to neutron irradiation within the same irradiation doses. Predicted thermal conductivities for an irradiated Tyranno-SA/ICVI-SiC composite are found to be comparable to available experimental data for a similar composite ICVI-processed with these fibers.

  8. Modeling the Effect of Multiple Matrix Cracking Modes on Cyclic Hysteresis Loops of 2D Woven Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-08-01

    In this paper, the effect of multiple matrix cracking modes on cyclic loading/unloading hysteresis loops of 2D woven ceramic-matrix composites (CMCs) has been investigated. The interface slip between fibers and the matrix existed in matrix cracking mode 3 and mode 5, in which matrix cracking and interface debonding occurred in longitudinal yarns, are considered as the major reason for hysteresis loops of 2D woven CMCs. The effects of fiber volume content, peak stress, matrix crack spacing, interface properties, matrix cracking mode proportion and interface wear on interface slip and hysteresis loops have been analyzed. The cyclic loading/unloading hysteresis loops of 2D woven SiC/SiC composite corresponding to different peak stresses have been predicted using the present analysis. It was found that the damage parameter, i.e., the proportion of matrix cracking mode 3 in the entire cracking modes of the composite, increases with increasing peak stress.

  9. Matrix cracking in laminated composites under monotonic and cyclic loadings

    NASA Technical Reports Server (NTRS)

    Allen, David H.; Lee, Jong-Won

    1991-01-01

    An analytical model based on the internal state variable (ISV) concept and the strain energy method is proposed for characterizing the monotonic and cyclic response of laminated composites containing matrix cracks. A modified constitution is formulated for angle-ply laminates under general in-plane mechanical loading and constant temperature change. A monotonic matrix cracking criterion is developed for predicting the crack density in cross-ply laminates as a function of the applied laminate axial stress. An initial formulation for a cyclic matrix cracking criterion for cross-ply laminates is also discussed. For the monotonic loading case, a number of experimental data and well-known models are compared with the present study for validating the practical applicability of the ISV approach.

  10. Load redistribution considerations in the fracture of ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Thomas, David J.; Wetherhold, Robert C.

    1992-01-01

    Using a macroscopic viewpoint, composite laminae are homogeneous orthotropic solids whose directional strengths are random variables. Incorporation of these random variable strengths into failure models, either interactive or noninteractive, allows for the evaluation of the lamina reliability under a given stress state. Using a noninteractive criterion for demonstration purposes, laminate reliabilities are calculated assuming previously established load sharing rules for the redistribution of load as the failure of laminae occur. The matrix cracking predicted by ACK theory is modeled to allow a loss of stiffness in the fiber direction. The subsequent failure in the fiber direction is controlled by a modified bundle theory. Results are compared with previous models which did not permit separate consideration of matrix cracking, as well as to results obtained from experimental data. The effects of variations from the ideal physical geometry which is normally used to depict the matrix cracking are also studied.

  11. Matrix cracking in laminated composites under monotonic and cyclic loadings

    NASA Technical Reports Server (NTRS)

    Allen, David H.; Lee, Jong-Won

    1991-01-01

    An analytical model based on the internal state variable (ISV) concept and the strain energy method is proposed for characterizing the monotonic and cyclic response of laminated composites containing matrix cracks. A modified constitution is formulated for angle-ply laminates under general in-plane mechanical loading and constant temperature change. A monotonic matrix cracking criterion is developed for predicting the crack density in cross-ply laminates as a function of the applied laminate axial stress. An initial formulation for a cyclic matrix cracking criterion for cross-ply laminates is also discussed. For the monotonic loading case, a number of experimental data and well-known models are compared with the present study for validating the practical applicability of the ISV approach.

  12. Immunohistochemical evidence of rapid extracellular matrix remodeling after iron-particle irradiation of mouse mammary gland

    NASA Technical Reports Server (NTRS)

    Ehrhart, E. J.; Gillette, E. L.; Barcellos-Hoff, M. H.; Chaterjee, A. (Principal Investigator)

    1996-01-01

    High-LET radiation has unique physical and biological properties compared to sparsely ionizing radiation. Recent studies demonstrate that sparsely ionizing radiation rapidly alters the pattern of extracellular matrix expression in several tissues, but little is known about the effect of heavy-ion radiation. This study investigates densely ionizing radiation-induced changes in extracellular matrix localization in the mammary glands of adult female BALB/c mice after whole-body irradiation with 0.8 Gy 600 MeV iron particles. The basement membrane and interstitial extracellular matrix proteins of the mammary gland stroma were mapped with respect to time postirradiation using immunofluorescence. Collagen III was induced in the adipose stroma within 1 day, continued to increase through day 9 and was resolved by day 14. Immunoreactive tenascin was induced in the epithelium by day 1, was evident at the epithelial-stromal interface by day 5-9 and persisted as a condensed layer beneath the basement membrane through day 14. These findings parallel similar changes induced by gamma irradiation but demonstrate different onset and chronicity. In contrast, the integrity of epithelial basement membrane, which was unaffected by sparsely ionizing radiation, was disrupted by iron-particle irradiation. Laminin immunoreactivity was mildly irregular at 1 h postirradiation and showed discontinuities and thickening from days 1 to 9. Continuity was restored by day 14. Thus high-LET radiation, like sparsely ionizing radiation, induces rapid-remodeling of the stromal extracellular matrix but also appears to alter the integrity of the epithelial basement membrane, which is an important regulator of epithelial cell proliferation and differentiation.

  13. Immunohistochemical evidence of rapid extracellular matrix remodeling after iron-particle irradiation of mouse mammary gland

    SciTech Connect

    Ehrhart, E.J.; Gillette, E.L.; Barcellos-Hoff, M.H.

    1996-02-01

    High-LET radiation has unique physical and biological properties compared to sparsely ionizing radiation. Recent studies demonstrate that sparsely ionizing radiation rapidly alters the pattern of extracellular matrix expression in several tissues, but little is known about the effect of heavy-ion radiation. This study investigates densely ionizing radiation-induced changes in extracellular matrix localization in the mammary glands of adult female BALB/c mice after whole-body irradiation with 0.8 Gy 600 MeV iron particles. The basement membrane and interstitial extracellular matrix proteins of the mammary gland stroma were mapped with respect to time postirradiation using immunofluorescence. Collagen III was induced in the adipose stroma within 1 day, continued to increase through day 9 and was resolved by day 14. Immunoreactive tenascin was induced in the epithelium by day 1, was evident at the epithelial-stromal interface by day 5-9 and persisted as a condensed layer beneath the basement membrane through day 14. These findings parallel similar changes induced by {gamma} irradiation but demonstrate different onset and chronicity. In contrast, the integrity of epithelial basement membrane, which was unaffected by sparsely ionizing radiation, was disrupted by iron-particle irradiation. Laminin inummoreactivity was mildly irregular at 1 h postirradiation and showed discontinuities and thickening from days 1 to 9. Continuity was restored by day 14. Thus high-LET radiation, like sparsely ionizing radiation, induces rapid remodeling of the stromal extracellular matrix but also appears to alter the integrity of the epithelial basement membrane, which is an important regulator of epithelial cell proliferation and differentiation. 40 refs., 3 figs.

  14. Immunohistochemical evidence of rapid extracellular matrix remodeling after iron-particle irradiation of mouse mammary gland

    NASA Technical Reports Server (NTRS)

    Ehrhart, E. J.; Gillette, E. L.; Barcellos-Hoff, M. H.; Chaterjee, A. (Principal Investigator)

    1996-01-01

    High-LET radiation has unique physical and biological properties compared to sparsely ionizing radiation. Recent studies demonstrate that sparsely ionizing radiation rapidly alters the pattern of extracellular matrix expression in several tissues, but little is known about the effect of heavy-ion radiation. This study investigates densely ionizing radiation-induced changes in extracellular matrix localization in the mammary glands of adult female BALB/c mice after whole-body irradiation with 0.8 Gy 600 MeV iron particles. The basement membrane and interstitial extracellular matrix proteins of the mammary gland stroma were mapped with respect to time postirradiation using immunofluorescence. Collagen III was induced in the adipose stroma within 1 day, continued to increase through day 9 and was resolved by day 14. Immunoreactive tenascin was induced in the epithelium by day 1, was evident at the epithelial-stromal interface by day 5-9 and persisted as a condensed layer beneath the basement membrane through day 14. These findings parallel similar changes induced by gamma irradiation but demonstrate different onset and chronicity. In contrast, the integrity of epithelial basement membrane, which was unaffected by sparsely ionizing radiation, was disrupted by iron-particle irradiation. Laminin immunoreactivity was mildly irregular at 1 h postirradiation and showed discontinuities and thickening from days 1 to 9. Continuity was restored by day 14. Thus high-LET radiation, like sparsely ionizing radiation, induces rapid-remodeling of the stromal extracellular matrix but also appears to alter the integrity of the epithelial basement membrane, which is an important regulator of epithelial cell proliferation and differentiation.

  15. Inorganic Polymer Matrix Composite Strength Related to Interface Condition

    PubMed Central

    Radford, Donald W.; Grabher, Andrew; Bridge, John

    2009-01-01

    Resin transfer molding of an inorganic polymer binder was successfully demonstrated in the preparation of ceramic fiber reinforced engine exhaust valves. Unfortunately, in the preliminary processing trials, the resulting composite valves were too brittle for in-engine evaluation. To address this limited toughness, the effectiveness of a modified fiber-matrix interface is investigated through the use of carbon as a model material fiber coating. After sequential heat treatments composites molded from uncoated and carbon-coated fibers are compared using room temperature 3-point bend testing. Carbon-coated Nextel fiber reinforced geopolymer composites demonstrated a 50% improvement in strength, versus that of the uncoated fiber reinforced composites, after the 250 °C postcure.

  16. Fillers for improved graphite fiber retention by polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Sheppard, C. H.; Simpson, F. H.; House, E. E., Jr.

    1980-01-01

    This program was designed to develop technology for fabrication of graphite/epoxy composites containing selected boron and boron-containing fillers, determine the effects of the fillers on physical and mechanical properties of composites, and evaluate the effectiveness of the boron fillers for fiber retention when the composites are exposed to fire conditions followed by impact. Fillers evaluated were crystalline and amorphous boron, boron carbide, and aluminum boride. The fillers were evaluated by mixing with Narmco 5208 resin matrix at quantities up to 5%. Graphite composites were fabricated and evaluated with respect to their mechanical properties, resistance to humidity, and burning characteristics. Also, the mechanism by which the fillers prevented fiber release was studied.

  17. Surface modification of ceramic matrix composites induced by laser treatment

    NASA Astrophysics Data System (ADS)

    Costil, S.; Lukat, S.; Langlade, C.; Coddet, C.

    2008-12-01

    Ceramics or ceramic composites present many advantages (hardness, chemical resistance, low density, etc.) which induce some more and more important applications particularly from the industrial point of view. The evolution of technology can also be beneficial to enlarge their global application areas. This is particularly the aim of this work which consists in applying a laser beam on the ceramic in order to clean its surface. A Nd:YAG laser has been used to study the basic mechanism roughening the surface of silicon carbide composite (ceramic matrix composite (CMC)). Investigations on different surfaces (two chemical compositions) show a strong influence of the nature of the material on the development of a characteristic conic structure. Microscopic studies (SEM) and elementary analyses (EDS and RMS) demonstrated the formation of a regular cone-like structure with a kinetic and a chemical modification specific to each material.

  18. Screening of metal matrix composites using ultrasonic C-scans

    SciTech Connect

    Johnson, W.S.

    1989-01-01

    Ultrasonic C-scans can be used to find some types of defects in continuous fiber-reinforced metal matrix composites such as boron/aluminum composites. These defects are related to the fatigue behavior and fracture location of each inspected specimen. The C-scan technique determined the relative amount of defects in boron/aluminum composites. The defects were primarily identified as gaps in the fiber spacing. Those specimens with higher defect densities had shorter fatigue lives, lower fatigue endurance limits, and greater reductions in the elastic unloading modulus (that is, stiffness) because of fatigue cycling. This type of data could be used to set accept/reject levels for a composite panel based on C-scan indications. 8 refs.

  19. Progressive fracture of polymer matrix composite structures: A new approach

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Murthy, P. L. N.; Minnetyan, L.

    1992-01-01

    A new approach independent of stress intensity factors and fracture toughness parameters has been developed and is described for the computational simulation of progressive fracture of polymer matrix composite structures. The damage stages are quantified based on physics via composite mechanics while the degradation of the structural behavior is quantified via the finite element method. The approach account for all types of composite behavior, structures, load conditions, and fracture processes starting from damage initiation, to unstable propagation and to global structural collapse. Results of structural fracture in composite beams, panels, plates, and shells are presented to demonstrate the effectiveness and versatility of this new approach. Parameters and guidelines are identified which can be used as criteria for structural fracture, inspection intervals, and retirement for cause. Generalization to structures made of monolithic metallic materials are outlined and lessons learned in undertaking the development of new approaches, in general, are summarized.

  20. Oxidation and Corrosion of Ceramics and Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Opila, Elizabeth J.; Lee, Kang N.

    2000-01-01

    Ceramics and ceramic matrix composites are candidates for numerous applications in high temperature environments with aggressive gases and possible corrosive deposits. There is a growing realization that high temperature oxidation and corrosion issues must be considered. There are many facets to these studies, which have been extensively covered in some recent reviews. The focus of this paper is on current research, over the past two years. In the authors' view, the most important oxidation and corrosion studies have focused on four major areas during this time frame. These are; (I) Oxidation of precursor-based ceramics; (II) Studies of the interphase material in ceramic matrix composites; (III) Water vapor interactions with ceramics, particularly in combustion environments; and (IV) Development of refractory oxide coatings for silicon-based ceramics. In this paper, we shall explore the most current work in each of these areas.

  1. Characterization of interlaminar shear strength of ceramic matrix composites

    SciTech Connect

    Fang, N.J.J.; Tsuwei Chou . Dept. of Mechanical Engineering)

    1993-10-01

    The interlaminar shear strengths of three ceramic matrix composites have been characterized using a double-notch shear (DNS) test. The material systems investigated are plain woven C/SiC, plain woven SiC/SiC, and cross-plied SiC/calcium aluminosilicate-II. The use of the double-notch shear test for measuring the interlaminar shear strength of ceramic matrix composites is evaluated first. Numerical stress analyses are performed to investigate the effect of DNS specimen length, notch distance, and specimen supporting jig on the stress distribution in the expected fracture plane and the interlaminar shear strength. The numerical findings are then compared with an analytical model proposed elsewhere and correlated with the experimental results. The validity of this test technique has been established.

  2. Thermal expansion behavior of LDEF metal matrix composites

    NASA Technical Reports Server (NTRS)

    Le, T. D.; Steckel, G. L.

    1992-01-01

    The effects of the space environment on the thermal expansion stability of metal matrix composites (graphite/Al and graphite/Mg) will be presented. A sample from each category of metal matrix composites mounted on the leading and trailing edge was chosen for analysis of the temperature-time-thermal strain histories. Typical thermal expansion curves over the same range of temperature were selected at the beginning, mid, and end of the recording duration. The thermal expansion of selected post-flight LDEF samples were measured over the same range of temperature in the laboratory using a Michelson laser interferometer. The thermal strains were monitored concurrently with a laser interferometer and a mounted strain gage.

  3. Method of thermal strain hysteresis reduction in metal matrix composites

    NASA Technical Reports Server (NTRS)

    Dries, Gregory A. (Inventor); Tompkins, Stephen S. (Inventor)

    1987-01-01

    A method is disclosed for treating graphite reinforced metal matrix composites so as to eliminate thermal strain hysteresis and impart dimensional stability through a large thermal cycle. The method is applied to the composite post fabrication and is effective on metal matrix materials using graphite fibers manufactured by both the hot roll bonding and diffusion bonding techniques. The method consists of first heat treating the material in a solution anneal oven followed by a water quench and then subjecting the material to a cryogenic treatment in a cryogenic oven. This heat treatment and cryogenic stress reflief is effective in imparting a dimensional stability and reduced thermal strain hysteresis in the material over a -250.degree. F. to +250.degree. F. thermal cycle.

  4. Isothermal fatigue mechanisms in Ti-based metal matrix composites

    NASA Technical Reports Server (NTRS)

    Majumdar, Bhaskar S.; Newaz, Golam M.

    1993-01-01

    Stress-controlled isothermal fatigue experiments were performed at room temperature (RT) and 548 C (in argon) on (0)8 SCS6/Ti 15-3 metal matrix composites (MMC's) with 15 and 41 volume percent SCS6 (SiC) fibers. The primary objectives were to evaluate the mechanical responses, and to obtain a clear understanding of the damage mechanisms leading to failure of the MMC's. The mechanical data indicated that strain ranges attained fairly constant values in the stress-controlled experiments at both RT and 538 C, and remained so for more than 85 percent of life. The fatigue data for MMC's with different volume fraction fibers showed that MMC life was controlled by the imposed strain range rather than the stress range. At RT, and at low and intermediate strain ranges, the dominant fatigue mechanism was matrix fatigue, and this was confirmed metallurgically from fractographic evidence as well as from observations of channel type dislocation structures in the matrix of fatigued MMC specimens. Reaction-zone cracks acted as important crack initiating sites at RT, with their role being to facilitate slip band formation and consequent matrix crack initiation through classical fatigue mechanisms. MMC life agreed with matrix life at the lower strain ranges, but was smaller than matrix life at higher strain ranges. Unlike the case of monotonic deformation, debonding damage was another major damage mechanism during fatigue at RT, and it increased for higher strain ranges. At high strain ranges at RT, fractography and metallography showed an absence of matrix cracks, but long lengths of debonds in the outer layers of the SCS6 fibers. Such debonding and consequent rubbing during fatigue is believed to have caused fiber damage and their failure at high strain ranges. Thus, whereas life was matrix dominated at low and intermediate strain ranges, it was fiber dominated at high strain ranges. At 538 C, the mean stain constantly increased (ratchetting) with the number of cycles. At high

  5. Glass matrix composites. I - Graphite fiber reinforced glass

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Bacon, J. F.

    1978-01-01

    An experimental program is described in which graphite fibers of Hercules HMS and HTS, Thornel 300, and Celanese DG-12 were used to reinforce, both uniaxially and biaxially, borosilicate pyrex glass. Composite flexural strength distribution, strength as a function of test temperature, fracture toughness and oxidative stability were determined and shown to be primarily a function of fiber type and the quality of fiber-matrix bond formed during composite fabrication. It is demonstrated that the graphite fiber reinforced glass system offers unique possibilities as a high performance structural material.

  6. Pillared smectite clay coatings for ceramic-matrix composites

    SciTech Connect

    Jagota, S.; Harmer, M.A.; Lemon, M.F.; Jagota, A.; McCarron, E.M. III.

    1995-08-01

    This paper describes a novel route for the low-temperature formation of mullite, from pillared smectite clay precursors, for use as fiber coatings in ceramic-matrix composites. In particular, alumina-pillared bentonite converts in part to mullite at the unusually low temperature of about 800 C. The clay precursors display excellent film-forming capability and have been coated onto silicon carbide fibers. Mechanical tests on composites of the coated fibers and a borosilicate glass demonstrate their success as debond coatings, suggesting that this approach is a viable and simple route to oxide coatings for fibers.

  7. High-temperature testing of glass/ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Mandell, John F.; Grande, Dodd H.; Dannemann, Kathryn A.

    1989-01-01

    Recent advances in ceramic and other high-temperature composites have created a need for test methods that can be used at 1000 C and above. Present test methods usually require adhesively bonded tabs that cannot be used at high temperatures. This paper discusses some of the difficulties with high-temperature test development and describes several promising test methods. Stress-strain data are given for Nicalon ceramic fiber reinforced glass and glass-ceramic matrix composites tested in air at temperatures up to 1000 C.

  8. Emerging Applications of Ceramic and Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, Divya; Ramolina, Dheeyana; Sandou, Sherleena

    2012-07-01

    Almost 500 papers were presented during the 43 sessions of the 27th Annual Cocoa Beach Conference & Exposition on Advanced Ceramics & Composites, which was organized by the Engineering Ceramics Division of the American Ceramic Society and sponsored by several federal agencies: NASA Glenn Research Center, the Army Research Office, the Department of Energy, and the Air Force Office of Scientific Research. Many of these papers focused on composites, both ceramic and metal matrix, and discussed mechanical behavior, design, fibers/interfaces, processing, and applications. Potential applications under development include components for armor, nuclear energy, and automobiles. A few of these applications have reached commercialization.

  9. High-temperature testing of glass/ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Mandell, John F.; Grande, Dodd H.; Dannemann, Kathryn A.

    1989-01-01

    Recent advances in ceramic and other high-temperature composites have created a need for test methods that can be used at 1000 C and above. Present test methods usually require adhesively bonded tabs that cannot be used at high temperatures. This paper discusses some of the difficulties with high-temperature test development and describes several promising test methods. Stress-strain data are given for Nicalon ceramic fiber reinforced glass and glass-ceramic matrix composites tested in air at temperatures up to 1000 C.

  10. Processing of thermoplastic matrix-carbon fiber composites

    SciTech Connect

    Adams, M.E.

    1992-01-01

    The effect of processing on the adhesion of AS-4 graphite fibers to polycarbonate, polyetherimide and polyester is examined. The adhesion is quantified using single fiber composite specimens. The specimens are carefully fabricated with different levels of applied pressure and cooling rate. It is found experimentally that both pressure and cooling rate can affect adhesion of the graphite fibers to the thermoplastic matrix materials. In general, adhesion is improved with higher pressures and slower cooling rates. Residual stress in a model composite is calculated and compared to the differences in adhesion with different processing histories. The results of the theory agree qualitatively with the experimental results.

  11. Fatigue in selectively fiber-reinforced titanium matrix composites

    NASA Astrophysics Data System (ADS)

    Ramamurty, U.

    1999-08-01

    Many applications of the Ti alloy matrix composites (TMCs) reinforced with SiC fibers are expected to use the selective reinforcement concept in order to optimize the processing and increase the cost-effectiveness. In this work, unnotched fatigue behavior of a Ti-6Al-4V matrix selectively reinforced with SCS-6 SiC fibers has been examined. Experiments have been conducted on two different model panels. Results show that the fatigue life of the selectively reinforced composites is far inferior to that of the all-TMC panel. The fatigue life decreases with the decreasing effective fiber volume fraction. Suppression of multiple matrix cracking in the selectively reinforced panels was identified as the reason for their lack of fatigue resistance. Fatigue endurance limit as a function of the clad thickness was calculated using the modified Smith-Watson-Topper (SWT) parameter and the effective fiber volume fraction approach. The regime over which multiple matrix cracking occurs is identified using the bridging fiber fracture criterion. A fatigue failure map for the selectively reinforced TMCs is constructed on the basis of the observed damage mechanisms. Possible applications of such maps are discussed.

  12. Electron Beam Curing of Polymer Matrix Composites - CRADA Final Report

    SciTech Connect

    Janke, C. J.; Howell, Dave; Norris, Robert E.

    1997-05-01

    The major cost driver in manufacturing polymer matrix composite (PMC) parts and structures, and one of the elements having the greatest effect on their quality and performance, is the standard thermal cure process. Thermal curing of PMCs requires long cure times and high energy consumption, creates residual thermal stresses in the part, produces volatile toxic by-products, and requires expensive tooling that is tolerant of the high cure temperatures.

  13. Interface Characteristics and the Mechanical Properties of Metal Matrix Composites.

    DTIC Science & Technology

    1987-09-28

    oxide were identified to most probably be y - A120 3 or the MgAI20 4 type spinel. Details are given in Appendix K. Summary -. The research reported ...Zecas aT Austit. INTERFACE CHARACTERISTICS AND THE MECHANICAL PROPERTIES OF METAL MATRIX COMPOSITES UTCMSE-87-3 Office of Naval Research Technical Report ...THIS PAGE (When Date Entered) READ INSTRUCTIONSREPORT DOCUMENTATION PAGE I RE COSPLETIOR~BEFORE MPLETING FORM VI REPORT NUMBER 2. GOVT ACCESSION NO., 3

  14. Thermal-vacuum response of polymer matrix composites in space

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.; Matthews, R.

    1993-01-01

    This report describes a thermal-vacuum outgassing model and test protocol for predicting outgassing times and dimensional changes for polymer matrix composites. Experimental results derived from 'control' samples are used to provide the basis for analytical predictions to compare with the outgassing response of Long Duration Exposure Facility (LDEF) flight samples. Coefficient of thermal expansion (CTE) data are also presented. In addition, an example is given illustrating the dimensional change of a 'zero' CTE laminate due to moisture outgassing.

  15. Anisotropic Damage Mechanics Modeling in Metal Matrix Composites

    DTIC Science & Technology

    1993-05-15

    conducted on a titanium aluminide SiC-reinforced metal matrix composite. Center-cracked plates with laminate layups of (0/90) and (±45). were tested...Kattan, P. I., "Finite Strain Plasticity and Damage in Constitutive Modeling of Metals with Spin Tensors," Applied Mechanics Reviews, Vol. 45, No. 3...34Contractors Meeting on Mechanics of Materials," Dayton, Ohio, October 1991. Voyiadjis, G. Z., and Kattan, P. I., "Finite Strain Plasticity and Damage in

  16. Interface Character of Aluminum-Graphite Metal Matrix Composites.

    DTIC Science & Technology

    1980-12-23

    dt 01 , 1 hdf f - -1, -nl~ he results of the research described in this annual report can be summarized in terms of the experimental approaches used...Aluminum-Graphite Metal Matrix Composites The results of the research described in this annual report can be summarized in terms of the experimental... terms of the chemical state at the interface. 4. Transmission eloctron microscopy (TEM) measurement 2 of the phases present in the interface. 5. The

  17. Magnesium Matrix Composite Foams-Density, Mechanical Properties, and Applications

    DTIC Science & Technology

    2012-07-24

    known that the effect of particle-matrix interfacial bonding is much less significant under compression compared to under tension [33,34]. One of the...parameter). Some syntactic foam composites are found to have less than 0.4 g/cc density in Figure 9. These data points belong to foams that contain...syntactic foams containing porosity only inside hollow particles. The yield strength values for various types of MMSFs, including aluminum, titanium , and

  18. Tensile and compressive test results for metal matrix composites

    NASA Technical Reports Server (NTRS)

    Shuart, M. J.; Herakovich, C. T.

    1977-01-01

    Experimental results of the mechanical behavior of two metal matrix composite systems at room temperature are presented. Ultimate stress, ultimate strain, Poisson's ratio, and initial Young's Modulus are documented for BORSIC/Aluminum in uniaxial tension and Boron/Aluminum in uniaxial tension and compression. Poisson's ratio is used for nonlinear stress-strain behavior. A comparison of compression results for B/Al as obtained from sandwich beam compression specimens and IITRI coupon compression specimens is presented.

  19. Durability and Damage Development in Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Haque, A.; Rahman, M.; Tyson, O. Z.; Jeelani, S.; Verrilli, Michael J. (Technical Monitor)

    2001-01-01

    Damage development in woven SiC/SiNC ceramic matrix composites (CMC's) under tensile and cyclic loading both at room and elevated temperatures have been investigated for the exhaust nozzle of high-efficient turbine engines. The ultimate strength, failure strain, proportional limit and modulus data at a temperature range of 23 to 1250 C are generated. The tensile strength of SiC/SiNC woven composites have been observed to increase with increased temperatures up to 1000 C. The stress/strain plot shows a pseudo-yield point at 25 percent of the failure strain (epsilon(sub r)) which indicates damage initiation in the form of matrix cracking. The evolution of damage beyond 0.25 epsilon(sub f), both at room and elevated temperature comprises multiple matrix cracking, interfacial debonding, and fiber pullout. Although the nature of the stress/strain plot shows damage-tolerant behavior under static loading both at room and elevated temperature, the life expectancy of SiC/SiNC composites degrades significantly under cyclic loading at elevated temperature. This is mostly due to the interactions of fatigue damage caused by the mechanically induced plastic strain and the damage developed by the creep strain. The in situ damage evolutions are monitored by acoustic event parameters, ultrasonic C-scan and stiffness degradation. Rate equations for modulus degradation and fatigue life prediction of ceramic matrix composites both at room and elevated temperatures are developed. These rate equations are observed to show reasonable agreement with experimental results.

  20. Engineering Interfaces in Metal Matrix Composites (Volume 3)

    DTIC Science & Technology

    1988-06-10

    interface, particularly at areas where the interface has been weakened by particulate contamination. The high pressures that result cause the film to...pure aluminum matrix by pressure infiltration. Miniature tensile specimens of the SiC coated AGR/ composite were tested in-situ in the high voltage...minimizing their weaknesses. The points of particular interest are the attainment of high stiffness and strength under both monotonic and cyclic loading

  1. Detection of Incipient Thermal Damage in Polymer Matrix Composites (Preprint)

    DTIC Science & Technology

    2007-02-01

    Polymer matrix composite mechanical properties have been shown to decrease significantly with the presence of thermal damage. For aerospace applications, this type of damage typically occurs as a result of exposure to elevated temperatures from localized heating, such as lightning strikes, exhaust wash, or improper maintenance/repair procedures. Mechanical testing has shown that this type of damage, known as incipient damage, is present even when no visible damage is observable and can cause significant reduction in mechanical properties. Incipient damage is not

  2. Mechanical Properties of 3-D ceramic matrix composites

    SciTech Connect

    Moore, E.H.; Folsom, C.A.; Keller, K.A.; Mah, T.

    1995-12-01

    The mullite-alumina system has been investigated with the goal of fabricating ceramic matrix composites (CMC) for use in turbine engine exhaust components over a range of temperatures from below ambient to 1200{degrees}C. Turbine engine components of interest include flaps and seals, and liners. These CMC are expected to be strong, tough, near-net fabricable and able to retain these properties over their entire range of use.

  3. Metal-Matrix Composite Parts With Metal Inserts

    NASA Technical Reports Server (NTRS)

    Majkowski, T.; Kashalikar, U.

    1995-01-01

    Developmental fabrication process produces metal-matrix composite (MMC) parts with integral metal inserts. With inserts, MMC parts readily joined to similar parts by use of brazing, welding, or mechanical fasteners. Process conceived to make strong, lightweight components of structures erected in outer space. Also useful on Earth, in such automotive parts as rocker arms, cylinder liners, and pistons. Potential industrial applications include parts subjected to high stresses at high temperatures, as in power-generation, mining, and oil-drilling equipment.

  4. Cure shrinkage effects in epoxy and polycyanate matrix composites

    SciTech Connect

    Spellman, G.P.

    1995-12-22

    A relatively new advanced composite matrix, polycyanate ester, was evaluated for cure shrinkage. The chemical cure shrinkage of composites is difficult to model but a number of clever experimental techniques are available to the investigator. In this work the method of curing a prepreg layup on top of a previously cured laminate of identical ply composition is utilized. The polymeric matrices used in advanced composites have been primarily epoxies and therefore a common system of this type, Fiberite 3501-6, was used as a base case material. Three polycyanate matrix systems were selected for the study. These are: Fiberite 954-2A, YLA RS-3, and Bryte Technology BTCy-1. The first three of these systems were unidirectional prepreg with carbon fiber reinforcement. The Bryte Technology material was reinforced with E-glass fabric. The technique used to evaluate cure shrinkage results in distortion of the flatness of an otherwise symmetric laminate. The first laminate is cured in a conventional fashion. An identical layup is cured on this first laminate. During the second cure all constituents are exposed to the same thermal cycles. However, only the new portion of the laminate will experience volumetric changes associate with matrix cure. The additional strain of cure shrinkage results in an unsymmetric distribution of residual stresses and an associated warpage of the laminate. The baseline material, Fiberite 3501-6, exhibited cure shrinkage that was in accordance with expectations. Cure strains were {minus}4.5E-04. The YLA RS-3 material had cure strains somewhat lower at {minus}3.2E-04. The Fiberite 954-2A cure strain was {minus}1.5E-04 that is 70% lower than the baseline material. The glass fabric material with the Bryte BTCy-1 matrix did not result in meaningful results because the processing methods were not fully compatible with the material.

  5. Fiber Matrix Interface Effects in Failure of Ceramic Matrix Fiber Composites

    DTIC Science & Technology

    1989-01-01

    FUNDINGISPONSORING ORGANIZATION 8b. OFFICE SYMBOL 9- PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER Scientific Officer If Applicable/ Office of Naval Research...Consequently, a major objective of continuing research on ceramic matrix composites is the identification of interphases that are both stable at high...approaches are readily applicable when Gic and t are small. The former method is most insightful when used with a nanoindenter system, whereupon T can be

  6. High Dose Neutron Irradiation of Hi-Nicalon Type S Silicon Carbide Composites, Part 2. Mechanical and Physical Properties

    DOE PAGES

    Katoh, Yutai; Nozawa, Takashi; Shih, Chunghao Phillip; ...

    2015-01-07

    Nuclear-grade silicon carbide (SiC) composite material was examined for mechanical and thermophysical properties following high-dose neutron irradiation in the High Flux Isotope Reactor at a temperature range of 573–1073 K. Likewise, the material was chemical vapor-infiltrated SiC-matrix composite with a two-dimensional satin weave Hi-Nicalon Type S SiC fiber reinforcement and a multilayered pyrocarbon/SiC interphase. Moderate (1073 K) to very severe (573 K) degradation in mechanical properties was found after irradiation to >70 dpa, whereas no evidence was found for progressive evolution in swelling and thermal conductivity. The swelling was found to recover upon annealing beyond the irradiation temperature, indicating themore » irradiation temperature, but only to a limited extent. Moreover, the observed strength degradation is attributed primarily to fiber damage for all irradiation temperatures, particularly a combination of severe fiber degradation and likely interphase damage at relatively low irradiation temperatures.« less

  7. High Temperature Mechanical Characterization of Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John Z.

    1998-01-01

    A high temperature mechanical characterization laboratory has been assembled at NASA Lewis Research Center. One contribution of this work is to test ceramic matrix composite specimens in tension in environmental extremes. Two high temperature tensile testing systems were assembled. The systems were assembled based on the performance and experience of other laboratories and meeting projected service conditions for the materials in question. The systems use frames with an electric actuator and a center screw. A PC based data acquisition and analysis system is used to collect and analyze the data. Mechanical extensometers are used to measure specimen strain. Thermocouples, placed near the specimen, are used to measure the specimen gage section temperature. The system for testing in air has a resistance element furnace with molybdenum disilicide elements and pneumatic grips with water cooling attached to hydraulic alignment devices. The system for testing in an inert gas has a graphite resistance element furnace in a chamber with rigidly mounted, water cooled, hydraulically actuated grips. Unidirectional SiC fiber reinforced reaction bonded Si3N4 and triaxially woven, two dimensional, SiC fiber reinforced enhanced SiC composites were tested in unidirectional tension. Theories for predicting the Young's modulus, modulus near the ultimate strength, first matrix cracking stress, and ultimate strength were applied and evaluated for suitability in predicting the mechanical behavior of SiC/RBSN and enhanced SiC/SiC composites. The SiC/RBSN composite exhibited pseudo tough behavior (increased area under the stress/strain curve) from 22 C to 1500 C. The rule of mixtures provides a good estimate of the Young's modulus of the SiC/RBSN composite using the constituent properties from room temperature to 1440 C for short term static tensile tests in air or nitrogen. The rule of mixtures significantly overestimates the secondary modulus near the ultimate strength. The ACK theory

  8. Rims, Matrix and the Bulk Compositions of Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

    Alexander, C. M. O'd.

    1995-09-01

    It has long been thought that chondrule rims and interchondrule matrix are amongst the most primitive materials in chondrites. Indeed, they are known to contain presolar grains [1]. However, most of the components in rims and matrix are Solar System in origin and may include nebular condensates [2], chondrule condensates [3] and chondrule fragments [4]. Discerning the relative importance of these possible sources has proved problematical. Both rims and matrix do contain chondrule fragments and the concentration of chondrule glass in the matrix could explain the general Al-enrichment of matrix in many UOCs [4], but in other meteorites, such as the CO3 ALHA 77307 [5], chondrule fragments are only a minor constituent. TEM observations show that rims and matrix do not contain significant amounts of equilibrium condensates. In the UOCs and CO3s, the rims and matrix appear to be composed of amorphous material, mineral fragments (mostly chondrule minerals) and secondary minerals that grew in the solid state, probably during metamorphism [2,4,5]. These and other observations prompted Brearley et al. [2] to suggest that rims and matrix formed from amorphous nebular condensates rather than crystalline condensates or chondrule glass. More recently it has been suggested that rims are composed, at least partially, of material that was volatilized during chondrule formation which then recondensed onto chondrules during cooling. Rims, but not matrix, in UOCs show correlated enrichments in FeO, Si, Mn and other moderately volatile elements compared to refractory elements like Al or Ti [3]. The abundances of Fe, Si etc. in rims range from matrix-like to highly enriched. The lack of enrichments in matrix suggests that, if volatilization occurred during chondrule formation, recondensation was confined mainly to chondrule rims. The fine-grained matrix, with its large surface area, was presumably not present during recondensation. Although, since matrix-like compositions form one

  9. Ultrafine-grained Aluminm and Boron Carbide Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Vogt, Rustin

    Cryomilling is a processing technique used to generate homogenously distributed boron carbide (B4C) particulate reinforcement within an ultrafine-grained aluminum matrix. The motivation behind characterizing a composite consisting of cryomilled aluminum B4C metal matrix composite is to design and develop a high-strength, lightweight aluminum composite for structural and high strain rate applications. Cryomilled Al 5083 and B4C powders were synthesized into bulk composite by various thermomechanical processing methods to form plate and extruded geometries. The effects of processing method on microstructure and mechanical behavior for the final consolidated composite were investigated. Cryomilling for extended periods of time in liquid nitrogen has shown to increase strength and thermal stability. The effects associated with cryomilling with stearic acid additions (as a process-control agent) on the degassing behavior of Al powders is investigated and results show that the liberation of compounds associated with stearic acid were suppressed in cryomilled Al powders. The effect of thermal expansion mismatch strain on strengthening due to geometrically necessary dislocations resulting from quenching is investigated and found not to occur in bulk cryomilled Al 5083 and B 4C composites. Previous cryomilled Al 5083 and B4C composites have exhibited ultrahigh strength associated with considerable strain-to-failure (>14 pct.) at high strain rates (>103/s) during mechanical testing, but only limited strain-to-failure (˜0.75 pct.) at quasi-static strain rates (10-3/s). The increased strain to failure at high strain rates is attributed to micro-flaw developments, including kinking, extensive axial splitting, and grain growth were observed after high strain rate deformation, and the significance of these mechanisms is considered.

  10. 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.

  11. Matrix cracking initiation stress in fiber-reinforced ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Kangutkar, Pramod Balkrishna

    1991-05-01

    One of the important design parameters in CMC's in the Matrix Cracking Initiation Stress (MCIS) which corresponds to the stress at which first matrix cracks are observed. Above the MCIS, the fibers will be exposed to the oxidizing environment which may degrade the mechanical property of the fibers and thus of the composite. In this thesis a systematic study to explore the effects of matrix toughness and inherent strength, fiber diameter, stiffness and volume fraction, temperature and interfacial bonding on the MCIS was carried out. Composites were fabricated using three different matrices--borosilicate glass, aluminosilicate glass and polycrystalline zirconium silicate (or zircon), and two different reinforcing fibers--an SiC monofilament (140 micron diameter) and an SiC yarn (16 micron diameter). In-situ observations during 3-point bend test inside the SEM indicate that matrix cracking is a local phenomenon and occurs first in the matrix between widest spaced fibers. In all composites the MCIS was found to increase with fiber additions and scaled with the monolithic strength. The relative increase in MCIS over the monolithic strength with fiber volume fraction, however, was found to depend strongly on the a(sub 0)/S ratio, where a(sub 0) is the inherent unreinforced matrix flaw size and S is the inter-fiber spacing. For small ratios, the effect of fiber additions on enhancing MCIS are minimal. As the ratio approaches unity, the role of the fibers in constraining the inherent flaw increases, thereby increasing the MCIS. Thermal residual stresses were also seen to play an important role in determining the MCIS; systems with compressive residual stresses in the matrix show higher MCIS at room temperature than at a higher temperature. In systems such as the 7740/Nicalon, which had negligible thermal stresses, MCIS showed minimal changes on testing at 520 C. Several theoretical models were reviewed and the predictions were compared to the experimental results. It was

  12. Three-Dimensional FIB/EBSD Characterization of Irradiated HfAl3-Al Composite

    SciTech Connect

    Hua, Zilong; Guillen, Donna Post; Harris, William; Ban, Heng

    2016-09-01

    A thermal neutron absorbing material, comprised of 28.4 vol% HfAl3 in an Al matrix, was developed to serve as a conductively cooled thermal neutron filter to enable fast flux materials and fuels testing in a pressurized water reactor. In order to observe the microstructural change of the HfAl3-Al composite due to neutron irradiation, an EBSD-FIB characterization approach is developed and presented in this paper. Using the focused ion beam (FIB), the sample was fabricated to 25µm × 25µm × 20 µm and mounted on the grid. A series of operations were carried out repetitively on the sample top surface to prepare it for scanning electron microscopy (SEM). First, a ~100-nm layer was removed by high voltage FIB milling. Then, several cleaning passes were performed on the newly exposed surface using low voltage FIB milling to improve the SEM image quality. Last, the surface was scanned by Electron Backscattering Diffraction (EBSD) to obtain the two-dimensional image. After 50 to 100 two-dimensional images were collected, the images were stacked to reconstruct a three-dimensional model using DREAM.3D software. Two such reconstructed three-dimensional models were obtained from samples of the original and post-irradiation HfAl3-Al composite respectively, from which the most significant microstructural change caused by neutron irradiation apparently is the size reduction of both HfAl3 and Al grains. The possible reason is the thermal expansion and related thermal strain from the thermal neutron absorption. This technique can be applied to three-dimensional microstructure characterization of irradiated materials.

  13. Summary of the U.S. specimen matrix for the HFIR 13J varying temperature irradiation capsule

    SciTech Connect

    Zinkle, S.J.

    1998-03-01

    The US specimen matrix for the collaborative DOE/Monbusho HFIR 13J varying temperature irradiation capsule contains two ceramics and 29 different metals, including vanadium alloys, ferritic/martensitic steels, pure iron, austenitic stainless steels, nickel alloys, and copper alloys. This experiment is designed to provide fundamental information on the effects of brief low-temperature excursions on the tensile properties and microstructural evolution of a wide range of materials irradiated at nominal temperatures of 350 and 500 C to a dose of {approximately}5 dpa. A total of 340 miniature sheet tensile specimens and 274 TEM disks are included in the US-supplied matrix for the irradiation capsule.

  14. Metallurgical Characterization of the Interfaces and the Damping Mechanisms in Metal Matrix Composites.

    DTIC Science & Technology

    2014-09-26

    in Metal Matrix Composites Contract No. N00014-84-C-0413 Submitted to Dr. Steve G. Fishman Office of Naval Research Mohan S. Misra Program Manager...Mechanisms in Metal Matrix Composites." 2.0 INTRODUCTION Metal matrix composites are candidate structural materials for space applications. Large structures...damping capacity of the structural material is a significant parameter. If metal matrix composites are to be used for space structures; their

  15. High temperature resin matrix composites for aerospace structures

    NASA Technical Reports Server (NTRS)

    Davis, J. G., Jr.

    1980-01-01

    Accomplishments and the outlook for graphite-polyimide composite structures are briefly outlined. Laminates, skin-stiffened and honeycomb sandwich panels, chopped fiber moldings, and structural components were fabricated with Celion/LARC-160 and Celion/PMR-15 composite materials. Interlaminar shear and flexure strength data obtained on as-fabricated specimens and specimens that were exposed for 125 hours at 589 K indicate that epoxy sized and polyimide sized Celion graphite fibers exhibit essentially the same behavior in a PMR-15 matrix composite. Analyses and tests of graphite-polyimide compression and shear panels indicate that utilization in moderately loaded applications offers the potential for achieving a 30 to 50 percent reduction in structural mass compared to conventional aluminum panels. Data on effects of moisture, temperature, thermal cycling, and shuttle fluids on mechanical properties indicate that both LARC-160 and PMR-15 are suitable matrix materials for a graphite-polyimide aft body flap. No technical road blocks to building a graphite-polyimide composite aft body flap are identified.

  16. Fillers for improved graphite fiber retention by polymer matrix composites

    NASA Technical Reports Server (NTRS)

    House, E. E.; Sheppard, C. H.

    1981-01-01

    The results of a program designed to determine the extent to which elemental boron and boron containing fillers added to the matrix resin of graphite/epoxy composites prevent the release of graphite fibers when the composites are exposed to fire and impact conditions are described. The fillers evaluated were boron, boron carbide and aluminum boride. The conditions evaluated were laboratory simulations of those that could exist in the event of an aircraft crash and burn situation. The baseline (i.e., unfilled) laminates evaluated were prepared from commercially available graphite/epoxy. The baseline and filled laminates' mechanical properties, before and after isothermal and humidity aging, also were compared. It was found that a small amount of graphite fiber was released from the baseline graphite/epoxy laminates during the burn and impact conditions used in this program. However, the extent to which the fibers were released is not considered a severe enough problem to preclude the use of graphite reinforced composites in civil aircraft structure. It also was found that the addition of boron and boron containing fillers to the resin matrix eliminated this fiber release. Mechanical properties of laminates containing the boron and boron containing fillers were lower than those of the baseline laminates. These property degradations for two systems: boron (5 micron) at 2.5 percent filler loading, and boron (5 micron) at 5.0 percent filler loading do not appear severe enough to preclude their use in structural composite applications.

  17. Assessment of hyaline cartilage matrix composition using near infrared spectroscopy.

    PubMed

    Palukuru, Uday P; McGoverin, Cushla M; Pleshko, Nancy

    2014-09-01

    Changes in the composition of the extracellular matrix (ECM) are characteristic of injury or disease in cartilage tissue. Various imaging modalities and biochemical techniques have been used to assess the changes in cartilage tissue but lack adequate sensitivity, or in the case of biochemical techniques, result in destruction of the sample. Fourier transform near infrared (FT-NIR) spectroscopy has shown promise for the study of cartilage composition. In the current study NIR spectroscopy was used to identify the contributions of individual components of cartilage in the NIR spectra by assessment of the major cartilage components, collagen and chondroitin sulfate, in pure component mixtures. The NIR spectra were obtained using homogenous pellets made by dilution with potassium bromide. A partial least squares (PLS) model was calculated to predict composition in bovine cartilage samples. Characteristic absorbance peaks between 4000 and 5000 cm(-1) could be attributed to components of cartilage, i.e. collagen and chondroitin sulfate. Prediction of the amount of collagen and chondroitin sulfate in tissues was possible within 8% (w/dw) of values obtained by gold standard biochemical assessment. These results support the use of NIR spectroscopy for in vitro and in vivo applications to assess matrix composition of cartilage tissues, especially when tissue destruction should be avoided. Copyright © 2014. Published by Elsevier B.V.

  18. Modeling of crack bridging in a unidirectional metal matrix composite

    NASA Technical Reports Server (NTRS)

    Ghosn, Louis J.; Kantzos, Pete; Telesman, Jack

    1991-01-01

    The effective fatigue crack driving force and crack opening profiles were determined analytically for fatigue tested unidirectional composite specimens exhibiting fiber bridging. The crack closure pressure due to bridging was modeled using two approaches; the fiber pressure model and the shear lag model. For both closure models, the Bueckner weight function method and the finite element method were used to calculate crack opening displacements and the crack driving force. The predicted near crack tip opening profile agreed well with the experimentally measured profiles for single edge notch SCS-6/Ti-15-3 metal matrix composite specimens. The numerically determined effective crack driving force, Delta K(sup eff), was calculated using both models to correlate the measure crack growth rate in the composite. The calculated Delta K(sup eff) from both models accounted for the crack bridging by showing a good agreement between the measured fatigue crack growth rates of the bridged composite and that of unreinforced, unbridged titanium matrix alloy specimens.

  19. Composite impact strength improvement through a fiber/matrix interphase

    NASA Technical Reports Server (NTRS)

    Cavano, P. J.; Winters, W. E.

    1975-01-01

    Research was conducted to improve the impact strength and toughness of fiber/resin composites by means of a fiber coating interphase. Graphite fiber/epoxy resin composites were fabricated with four different fiber coating systems introduced in a matrix-fiber interphase. Two graphite fibers, a high strength and a high modulus type, were studied with the following coating systems: chemical vapor deposited boron, electroless nickel, a polyamide-imide resin and a thermoplastic polysulfone resin. Evaluation methods included the following tests: Izod, flexure, shear fracture toughness, longitudinal and transverse tensile, and transverse and longitudinal compression. No desirable changes could be effected with the high strength fiber, but significant improvements in impact performance were observed with the polyamide-imide resin coated high modulus fiber with no loss in composite modulus.

  20. Synthesis and characterization of a new high entropy composite matrix

    NASA Astrophysics Data System (ADS)

    Popescu, G.; Matara, M. A.; Csaki, I.; Popescu, C. A.; Truşcă, R.

    2016-06-01

    Even if high entropy alloys were not reported in a scientific journal till 2003, these new alloys have been investigated since 1995 due to their high temperature properties. In the last years the synthesis of these alloys has been widely investigated. Thus, the present work has been carried out to produce a high entropy composite using an equiatomic AlCrFeMnNi high entropy alloy (HEA) matrix and graphite particles (Gr) as reinforcing material. The high entropy composite was obtained by powder metallurgy route using a planetary ball mill. The mechanically alloyed mixture was investigated by scanning electron microscopy (SEM). Microstructural investigation realized by SEM revealed the homogenous structure of the composite, with multiple phases and decreasing particles size, mostly reaching nanometric scale.

  1. The mechanical behavior of a hybrid metal matrix composite

    NASA Astrophysics Data System (ADS)

    Zok, F.; Jansson, S.; Evans, A. G.; Nardone, V.

    1991-09-01

    The mechanical behavior of a unidirectionally reinforced hybrid metal matrix composite in two different states has been studied: one with a “weakly bonded” interface and the other with a “strong” interface. Similarities and contrasts in mechanical behavior have been related to the properties of the interface. The longitudinal tensile strength and the crack growth initiation resistance are found to be insensitive to the condition of the interface. However, the material with the “weak” interface exhibits extensive debonding, resulting in a steeply increasing resistance curve and a large work of rupture. Furthermore, the weak interface reduces the transverse and torsional strength of the composite. This study illustrates how the tailoring of interfacial properties can improve the mechanical performance of composites for certain structural applications.

  2. Probabilistic Evaluation of Bolted Joints in Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Minnetyan, L.

    1997-01-01

    Computational methods are described to probabilistically simulate fracture in bolted composite structures. Progressive fracture is simulated via an innovative approach independent of stress intensity factors and fracture toughness. The effect on structure damage of design variable uncertainties is quantified. The Fast Probability Integrator is used to assess the scatter in the composite structure response before and after damage. Sensitivity of the response to design variables is evaluated. The methods are demonstrated for bolted joint polymer matrix composite panels under end loads. The effects of fabrication process are included in the simulation of damage in the bolted panel. The results show that the most effective way to reduce the end displacement at fracture is to control the load and ply thickness.

  3. Matrix resin effects in composite delamination - Mode I fracture aspects

    NASA Technical Reports Server (NTRS)

    Hunston, Donald L.; Moulton, Richard J.; Johnston, Norman J.; Bascom, Willard D.

    1987-01-01

    A number of thermoset, toughened thermoset, and thermoplastic resin matrix systems were characterized for Mode I critical strain energy release rates, and their composites were tested for interlaminar critical strain energy release rates using the double cantilever beam method. A clear correlation is found between the two sets of data. With brittle resins, the interlaminar critical strain energy release rates are somewhat larger than the neat resin values due to a full transfer of the neat resin toughness to the composite and toughening mechanisms associated with crack growth. With tougher matrices, the higher critical strain energy release rates are only partially transferred to the composites, presumably because the fibers restrict the crack-tip deformation zones.

  4. Fiber shape effects on metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Brown, H. C.; Lee, H.-J.; Chamis, C. C.

    1992-01-01

    The effects of different fiber shapes on the behavior of a SiC/Ti-15 metal matrix composite is computationally simulated. A three-dimensional finite element model consisting of a group of nine unidirectional fibers is used in the analysis. The model is employed to represent five different fiber shapes: a circle, an ellipse, a kidney, and two different cross shapes. The distribution of microstresses and the composite material properties, such as moduli, coefficients of thermal expansion, and Poisson's ratios, are obtained from the finite element analysis for the various fiber shapes. Comparisons of these results are used to determine the sensitivity of the composite behavior to the different fiber shapes and assess their potential benefits. No clear benefits result from different fiber shapes though there are some increases/decreases in isolated properties.

  5. Acousto-ultrasonic evaluation of ceramic matrix composite materials

    NASA Technical Reports Server (NTRS)

    Dosreis, Henrique L. M.

    1991-01-01

    Acousto-ultrasonic nondestructive evaluation of ceramic composite specimens with a lithium-alumino-silicate glass matrix reinforced with unidirectional silicon carbide (NICALON) fibers was conducted to evaluate their reserve of strength. Ceramic composite specimens with different amount of damage were prepared by four-point cyclic fatigue loading of the specimens at 500 C for a different number of cycles. The reserve of strength of the specimens was measured as the maximum bending stress recorded during four-pointed bending test with the load monotonically increased until failure occurs. It was observed that the reserve of strength did not correlate with the number of fatigue cycles. However, it was also observed that higher values of the stress wave factor measurements correspond to higher values of the reserve of strength test data. Therefore, these results show that the acousto-ultrasonic approach has the potential of being used to monitor damage and to estimate the reserve of strength of ceramic composites.

  6. Corrosion control of cement-matrix and aluminum-matrix composites

    NASA Astrophysics Data System (ADS)

    Hou, Jiangyuan

    Corrosion control of composite materials, particularly aluminum-matrix and cement-matrix composites, was addressed by surface treatment, composite formulation and cathodic protection. Surface treatment methods studied include anodization in the case of aluminum-matrix composites and oxidation treatment (using water) in the case of steel rebar for reinforcing concrete. The effects of reinforcement species (aluminum nitride (AIN) versus silicon carbide (SiC) particles) in the aluminum-matrix composites and of admixtures (carbon fibers, silica fume, latex and methylcellulose) in concrete on the corrosion resistance of composites were addressed. Moreover, the effect of admixtures in concrete and of admixtures in mortar overlay (as anode on concrete) on the efficiency of cathodic protection of steel reinforced concrete was studied. For SiC particle filled aluminum, anodization was performed successfully in an acid electrolyte, as for most aluminum alloys. However, for AlN particle filled aluminum, anodization needs to be performed in an alkaline (0.7 N NaOH) electrolyte instead. The concentration of NaOH in the electrolyte was critical. It was found that both silica fume and latex improved the corrosion resistance of rebar in concrete in both Ca(OH)sb2 and NaCl solutions, mainly because these admixtures decreased the water absorptivity. Silica fume was more effective than latex. Methylcellulose improved the corrosion resistance of rebar in concrete a little in Ca(OH)sb2 solution. Carbon fibers decreased the corrosion resistance of rebar in concrete, but this effect could be made up for by either silica fume or latex, such that silica fume was more effective than latex. Surface treatment in the form of water immersion for two days was found to improve the corrosion resistance of rebar in concrete. This treatment resulted in a thin uniform layer of black iron oxide (containing Fesp{2+}) on the entire rebar surface except on the cross-sectional surface. Prior to the

  7. In situ characterization of metal matrix composites processing

    NASA Astrophysics Data System (ADS)

    Munger, Gareth Torrey

    1999-11-01

    The high temperatures and pressures used for the processing of fiber reinforced metal matrix composites (MMC's) can result in the bending and fracture of fibers, and the development of residual stresses in both the fibers and surrounding metal matrix. These phenomena adversely affect the properties of MMC's. Methods for their nondestructive measurement are therefore needed both to better understand the process induced damage mechanisms and to ensure that composites are not placed into service with unacceptable fiber damage and/or residual stresses. A fiber optic luminescence approach based upon the frequency shift of the R lines emission of doped sapphire fibers was used to determine the residual stresses in both Ti/Al2O3 and Ti/SiC composites. To investigate the significance of the creep relaxation effects, residual stresses were measured for sapphire fibers embedded in Ti-6Al-4V plates that had been cooled at different rates. The compressive stresses in the fiber are consistent with the coefficients of thermal expansion (CTE) of sapphire being less than Ti-6Al-4V. A multiple concentric cylinder model was used to predict the residual stress state. The model results confirmed that the creep relaxation was induced responsible for the lower stress in the slowly cooled samples and suggest that cooling rate is important to control during processing. To test the notion of the use of a sapphire fiber as a 'witness to' the stress state in an MMC, a sapphire fiber was inserted into a Ti-6Al-4V coated SIGMA (SiC) fiber bundle prior to its consolidation. A generalized method of cells (GMC) model was used to develop a relationship between the stress state within the sapphire witness fiber and that of the surrounding Ti-6Al-4V matrix and the SIGMA fibers. Fiber fracture during the hot isostatic processing (HIP) consolidation of titanium matrix composite was measured using an in-situ acoustic emission approach. For process cycles in which pressure was applied prior to

  8. Aspects of fabrication aluminium matrix heterophase composites by suspension method

    NASA Astrophysics Data System (ADS)

    Dolata, A. J.; Dyzia, M.

    2012-05-01

    Composites with an aluminium alloy matrix (AlMMC) exhibit several advantageous properties such as good strength, stiffness, low density, resistance and dimensional stability to elevated temperatures, good thermal expansion coefficient and particularly high resistance to friction wear. Therefore such composites are more and more used in modern engineering constructions. Composites reinforced with hard ceramic particles (Al2O3, SiC) are gradually being implemented into production in automotive or aircraft industries. Another application of AlMMC is in the electronics industry, where the dimensional stability and capacity to absorb and remove heat is used in radiators. However the main problems are still: a reduction of production costs, developing methods of composite material tests and final product quality assessment, standardisation, development of recycling and mechanical processing methods. AlMMC production technologies, based on liquid-phase methods, and the shaping of products by casting methods, belong to the cheapest production methods. Application of a suspension method for the production of composites with heterophase reinforcement may turn out to be a new material and technological solution. The article presents the material and technological aspects of the transfer procedures for the production of composite suspensions from laboratory scale to a semi-industrial scale.

  9. Potential of Organic Matrix Composites for Liquid Oxygen Tank

    NASA Technical Reports Server (NTRS)

    Davis, Samuel E.; Herald, Stephen D.; Stolzfus, Joel M.; Engel, Carl D.; Bohlen, James W.; Palm, Tod; Robinson, Michael J.

    2005-01-01

    Composite materials are being considered for the tankage of cryogenic propellants in access to space because of potentially lower structural weights. A major hurdle for composites is an inherent concern about the safety of using flammable structural materials in contact with liquid and gaseous oxygen. A hazards analysis approach addresses a series of specific concerns that must be addressed based upon test data. Under the 2nd Generation Reusable Launch Vehicle contracts, testing was begun for a variety of organic matrix composite materials both to aid in the selection of materials and to provide needed test data to support hazards analyses. The work has continued at NASA MSFC and the NASA WSTF to provide information on the potential for using composite materials in oxygen systems. Appropriate methods for oxygen compatibility testing of structural materials and data for a range of composite materials from impact, friction, flammability and electrostatic discharge testing are presented. Remaining concerns and conclusions about composite tank structures, and recommendations for additional testing are discussed. Requirements for system specific hazards analysis are identified.

  10. Material and structural studies of metal and polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Signorelli, R. A.; Serafini, T. T.; Johns, R. H.

    1973-01-01

    Fiber-reinforced composites and design analysis methods for these materials are being developed because of the vast potential of composites for decreasing weight and/or increasing use temperature capability in aerospace systems. These composites have potential for use in airbreathing engine components as well as aeronautical and space vehicle structures. Refractory wire-superalloy composites for use up to 2200 F or more and metal-matrix composites for lower temperature applications such as aerospace structures and turbojet fan and compressor blades are under investigation and are discussed. The development of a number of resin systems, including the polyimides and polyphenylquinoxalines, is described and their potential for use at temperatures approaching 315 C (600 F) is indicated. Various molecular modifications that improve processability and/or increase thermal and oxidative resistance of the resins are also described. Structural analysis methods are discussed for determining the stresses and deformations in complex composite systems. Consideration is also given to residual stresses resulting from the curing process and to the foreign object damage problem in fan blade applications.

  11. Potential of Organic Matrix Composites for Liquid Oxygen Tank

    NASA Technical Reports Server (NTRS)

    Davis, Samuel E.; Herald, Stephen D.; Stolzfus, Joel M.; Engel, Carl D.; Bohlen, James W.; Palm, Tod; Robinson, Michael J.

    2005-01-01

    Composite materials are being considered for the tankage of cryogenic propellants in access to space because of potentially lower structural weights. A major hurdle for composites is an inherent concern about the safety of using flammable structural materials in contact with liquid and gaseous oxygen. A hazards analysis approach addresses a series of specific concerns that must be addressed based upon test data. Under the 2nd Generation Reusable Launch Vehicle contracts, testing was begun for a variety of organic matrix composite materials both to aid in the selection of materials and to provide needed test data to support hazards analyses. The work has continued at NASA MSFC and the NASA WSTF to provide information on the potential for using composite materials in oxygen systems. Appropriate methods for oxygen compatibility testing of structural materials and data for a range of composite materials from impact, friction, flammability and electrostatic discharge testing are presented. Remaining concerns and conclusions about composite tank structures, and recommendations for additional testing are discussed. Requirements for system specific hazards analysis are identified.

  12. Effect of electron irradiation on P4VP/PTSA complex and P4VP/Phthalocyanine composites

    NASA Astrophysics Data System (ADS)

    Vijayalakshmi Rao, R.; Mohan Rao, P.; Shridhar, M. H.

    2002-03-01

    Effect of electron irradiation on the optical and electrical properties of poly(4vinyl pyridine) (P4VP) complexed with P-toluene sulfonic acid (PTSA) and composites of P4VP with copper phthalocyanine (CuPc) and nickel phthalocyanine (NiPc) have been studied. In the optical spectra of the complex and composites, there is a shift in the absorption peak towards lower energy side and broadening of the peaks in case of composites after irradiation indicating the possibility of unsaturation. The FTIR analysis after irradiation shows the shift of number of peaks towards higher and lower energy sides. Shift in typical major peaks like CN, C-H are interpreted as due to the crosslinking or creation of unsaturated bonds. From electrical studies, it is seen that for lower dose of irradiation (1 kGy) there is no significant change but for higher doses the current conduction increases substantially. The permanent and temporary defects produced in the polymer matrix seems to affect the I/V characteristics of the complex and composites.

  13. Alterations of human acellular tissue matrix by gamma irradiation: histology, biomechanical property, stability, in vitro cell repopulation, and remodeling.

    PubMed

    Gouk, Sok-Siam; Lim, Tit-Meng; Teoh, Swee-Hin; Sun, Wendell Q

    2008-01-01

    AlloDerm, a processed acellular human tissue matrix, is used in a number of surgical applications for tissue repair and regeneration. In the present work, AlloDerm serves as a model system for studying gamma radiation-induced changes in tissue structure and stability as well as the effect of such changes on the cell-matrix interactions, including cell repopulation and matrix remodeling. AlloDerm tissue matrix was treated with 2-30 kGy gamma irradiation at room temperature. Gamma irradiation reduced the swelling of tissue matrix upon rehydration and caused significant structural modifications, including collagen condensation and hole formation in collagen fibres. The tensile strength of AlloDerm increased at low gamma dose but decreased with increasing gamma dosage. The elasticity of irradiated AlloDerm was reduced significantly. Calorimetric study showed that gamma irradiation destabilized the tissue matrix, resulting in greater susceptibility to proteolytic enzyme degradation. Although gamma irradiation did not affect in vitro proliferation of fibroblast cells, it promoted tissue degradation upon cell repopulation and influenced synthesis and deposition of new collagen.

  14. Modal acoustic emission source determination in silicon carbide matrix composites

    NASA Astrophysics Data System (ADS)

    Morscher, G. N.

    2000-05-01

    Modal acoustic emission has been used to monitor damage accumulation in woven silicon carbide (SiC) fiber reinforced SiC matrix composites during tensile testing. There are several potential sources of damage in these systems including transverse matrix cracking, fiber/matrix interphase debonding and sliding, longitudinal cracks in between plies, and fiber breakage. In the past, it has been shown that modal AE is excellent at detecting when damage occurs and subsides, where the damage occurs along the length of the sample, and the loss in material stiffness as a consequence of damage accumulation. The next step is to determine the extent that modal AE can be used to identify specific physical sources. This study will discuss the status of this aim for this composite system. Individual events were analyzed and correlated to specific sources based on the characteristics of the received waveforms, e.g., frequency spectrum and energy, and when the event occurred during the stress-history of the tensile test. Post-test microstructural examination of the test specimens enabled some correlation between specific types of AE events and damage sources.

  15. 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.

  16. Simultaneous Separation of Actinium and Radium Isotopes from a Proton Irradiated Thorium Matrix.

    PubMed

    Mastren, Tara; Radchenko, Valery; Owens, Allison; Copping, Roy; Boll, Rose; Griswold, Justin R; Mirzadeh, Saed; Wyant, Lance E; Brugh, Mark; Engle, Jonathan W; Nortier, Francois M; Birnbaum, Eva R; John, Kevin D; Fassbender, Michael E

    2017-08-15

    A new method has been developed for the isolation of (223,224,225)Ra, in high yield and purity, from a proton irradiated (232)Th matrix. Herein we report an all-aqueous process using multiple solid-supported adsorption steps including a citrate chelation method developed to remove >99.9% of the barium contaminants by activity from the final radium product. A procedure involving the use of three columns in succession was developed, and the separation of (223,224,225)Ra from the thorium matrix was obtained with an overall recovery yield of 91 ± 3%, average radiochemical purity of 99.9%, and production yields that correspond to physical yields based on previously measured excitation functions.

  17. Simultaneous Separation of Actinium and Radium Isotopes from a Proton Irradiated Thorium Matrix

    DOE PAGES

    Mastren, Tara; Radchenko, Valery; Owens, Allison; ...

    2017-08-15

    A new method has been developed for the isolation of 223,224,225Ra, in high yield and purity, from a proton irradiated 232Th matrix. We report an all-aqueous process using multiple solid-supported adsorption steps including a citrate chelation method developed to remove >99.9% of the barium contaminants by activity from the final radium product. Moreover, we developed a procedure involving the use of three columns in succession, and the separation of 223,224,225Ra from the thorium matrix was obtained with an overall recovery yield of 91 ± 3%, average radiochemical purity of 99.9%, and production yields that correspond to physical yields based onmore » previously measured excitation functions.« less

  18. Methodologies for the thermomechanical characterization of continuous-fiber ceramic matrix composites: A review of test methods

    SciTech Connect

    Lara-Curzio, E.; Ferber, M.K.; Jenkins, M.G.

    1994-05-01

    Requirements for thermomechanical characterization of ceramic matrix composite materials are reviewed. Feasibility of adapting existent room temperature test methods for polymer and metal matrix composites to test ceramic matrix composites at room and elevated temperatures is investigated.

  19. Development of a Precipitation-Strengthened Matrix for Non-quenchable Aluminum Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Vo, Nhon Q.; Sorensen, Jim; Klier, Eric M.; Sanaty-Zadeh, Amirreza; Bayansan, Davaadorj; Seidman, David N.; Dunand, David C.

    2016-07-01

    Recent developments in metal matrix composite-encapsulated ceramic armor show promise in lightweight armor technology. The system contains ceramic tiles, such as alumina, sandwiched between unreinforced aluminum or aluminum metal matrix composite (Al-MMC), which has a better toughness compared to the ceramic tiles. The sandwich structures should not be quenched during the fabrication, as the large mismatch in the coefficients of thermal expansion between the ceramic tiles and the unreinforced aluminum or Al-MMC creates internal stresses high enough to fracture the ceramic tiles. However, slow cooling of most commercial alloys creates large precipitates making solute unavailable for the formation of fine precipitates during aging. Here, we develop a non-quenched, high-strength metal matrix utilizing dilute Al-Sc-Zr alloys. We demonstrate that the dilute Al-0.09 Sc-0.045 Zr at.% alloy and the same alloy containing 0-4 vol.% alumina short fibers do not result in precipitation upon slow cooling from a high temperature, and can thereafter be aged to increase their strength. They exhibit a moderate strength, but improved ductility and toughness as compared to common armor aluminum alloys, such as AA5083-H131, making them attractive as armor materials and hybrid armor systems.

  20. Effects of Irradiation on the Microstructure of U-7Mo Dispersion Fuel with Al-2Si Matrix

    SciTech Connect

    Dennis D. Keiser, Jr.; Jan-Fong Jue; Adam B. Robinson; Pavel Medvedev; Jian Gan; Brandon D. Miller; Daniel M. Wachs; Glenn A. Moore; Curtis R. Clark; Mitchell K. Meyer; M. Ross Finlay

    2012-06-01

    The Reduced Enrichment for Research and Test Reactor program is developing low-enriched uranium U-Mo dispersion fuels for application in research and test reactors around the world. As part of this development, fuel plates have been irradiated in the Advanced Test Reactor and then characterized using optical metallography (OM) and scanning electron microscopy (SEM) to determine the as-irradiated microstructure. To demonstrate the irradiation performance of U-7Mo dispersion fuel plates with 2 wt% Si added to the matrix, fuel plates were tested to medium burnups at intermediate fission rates as part of the RERTR-6 experiment. Further testing was performed to higher fission rates as part of the RERTR-7A experiment, and very aggressive testing (high temperature, high fission density, high fission rate) was performed in the RERTR-9A, RERTR-9B and AFIP-1 experiments. As-irradiated microstructures were compared to those observed after fabrication to determine the effects of irradiation on the microstructure. Based on comparison of the microstructural characterization results for each irradiated sample, some general conclusions can be drawn about how the microstructure evolves during irradiation: there is growth of the fuel/matrix interaction layer (FMI), which was present in the samples to some degree after fabrication, during irradiation; Si diffuses from the FMI layer to deeper depths in the U-7Mo particles as the irradiation conditions are made more aggressive; lowering of the Si content in the FMI layer results in an increase in the size of the fission gas bubbles; as the FMI layer grows during irradiation more Si diffuses from the matrix to the FMI layer/matrix interface, and interlinking of fission gas bubbles in the fuel plate microstructure that may indicate breakaway swelling is not observed.

  1. Influence of interphase morphology on adhesion and composite durability in semicrystalline polymer matrix composites

    SciTech Connect

    Clark, R.L. Jr.; Kander, R.G.

    1996-12-31

    The microstructure of the interphase in semicrystalline polymer matrix composites has a dramatic influence on their mechanical properties. Studies have been performed to alter this region and to correlate various interphase morphologies with changes in fiber-matrix adhesion. A reinforced nylon 66 composite, when subjected to specific thermal histories, contains an interphase composed of transcrystallinity. This region has been altered by coating fibers with a diluent, poly(vinyl pyrrolidone), and/or adding the diluent to the matrix material in very small quantities. Interphase morphology was investigated with optical microscopy, and adhesion was measured using a modified fiber pull-out test. It was found that transcrystallinity increases the interfacial shear strength. The effect different interphase morphologies have on the durability of bulk composite samples is currently under investigation.

  2. Thermal Fatigue Limitations of Continuous Fiber Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Halford, Gary R.; Arya, Vinod K.

    1997-01-01

    The potential structural benefits of unidirectional, continuous-fiber, metal matrix composites (MMC's) are legendary. When compared to their monolithic matrices, MMC's possess superior properties such as higher stiffness and tensile strength, and lower coefficient of thermal expansion in the direction of the reinforcing fibers. As an added bonus, the MMC density will be lower if the fibers are less dense than the matrix matErial they replace. The potential has been demonstrated unequivocally both analytically and experimentally, especially at ambient temperatures. Successes prompted heavily-funded National efforts within the United States (USAF and NASA) and elsewhere to extend the promise of MMC's into the temperature regime wherein creep, stress relaxation, oxidation, and thermal fatigue damage mechanisms lurk. This is the very regime for which alternative high-temperature materials are becoming mandatory, since further enhancement of state- of-the-art monolithic alloys is rapidly approaching a point of diminishing returns.

  3. Influence of irradiation on the osteoinductive potential of demineralized bone matrix.

    PubMed

    Wientroub, S; Reddi, A H

    1988-04-01

    Samples of demineralized bone matrix (DBM) were exposed to graduated doses of radiation (1-15 Megarad) (Mrad) utilizing a linear accelerator and then implanted into the thoracic region of Long-Evans rats. Subcutaneous implantation of DBM into allogenic rats induces endochondral bone. In response to matrix implantation, a cascade of events ensues; mesenchymal cell proliferation on day 3 postimplantation, chondrogenesis on day 7, calcification of the cartilagenous matrix and chondrolysis on day 9, and osteogenesis on day 11 resulting in formation of an ossicle containing active hemopoietic tissue. Bone formation was assessed by measuring alkaline phosphatase activity, the rate of mineralization was determined by measuring 45Ca incorporation to bone mineral, and 40Ca content measured the extent of mineralization; acid phosphatase activity was used as a parameter for bone resorption. The dose of radiation (2.5 Mrad) currently used by bone banks for sterilization of bone tissue did not destroy the bone induction properties of DBM. Furthermore, radiation of 3-5 Mrad even enhanced bone induction, insofar as it produced more bone at the same interval of time than was obtained from unirradiated control samples. None of the radiation doses used in these experiments abolished bone induction, although the response induced by matrix irradiated with doses higher than 5 Mrad was delayed.

  4. Analysis of thermomechanical fatigue of unidirectional titanium metal matrix composites

    NASA Technical Reports Server (NTRS)

    Mirdamadi, M.; Johnson, W. S.; Bahei-El-din, Y. A.; Castelli, M. G.

    1991-01-01

    Thermomechanical fatigue (TMF) data was generated for a Ti-15V-3Cr-3Al-3Sn (Ti-15-3) material reinforced with SCS-6 silicon carbide fibers for both in-phase and out-of-phase thermomechanical cycling. Significant differences in failure mechanisms and fatigue life were noted for in-phase and out-of-phase testing. The purpose of the research is to apply a micromechanical model to the analysis of the data. The analysis predicts the stresses in the fiber and the matrix during the thermal and mechanical cycling by calculating both the thermal and mechanical stresses and their rate-dependent behavior. The rate-dependent behavior of the matrix was characterized and was used to calculate the constituent stresses in the composite. The predicted 0 degree fiber stress range was used to explain the composite failure. It was found that for a given condition, temperature, loading frequency, and time at temperature, the 0 degree fiber stress range may control the fatigue life of the unidirectional composite.

  5. Wear and impact resistance of HVOF sprayedceramic matrix composites coating

    NASA Astrophysics Data System (ADS)

    Prawara, B.; Martides, E.; Priyono, B.; Ardy, H.; Rikardo, N.

    2016-02-01

    Ceramic coating has the mechanical properties of high hardness and it is well known for application on wear resistance, but on the other hand the resistance to impact load is low. Therefore its use is limited to applications that have no impact loading. The aim of this research was to obtain ceramic-metallic composite coating which has improved impact resistance compared to conventional ceramic coating. The high impact resistance of ceramic-metallic composite coating is obtained from dispersed metallic alloy phase in ceramic matrix. Ceramic Matrix Composites (CMC) powder with chrome carbide (Cr3C2) base and ceramic-metal NiAl-Al2O3 with various particle sizes as reinforced particle was deposited on mild steel substrate with High Velocity Oxygen Fuel (HVOF) thermal spray coating. Repeated impact test showed that reinforced metallic phase size influenced impact resistance of CMC coating. The ability of CMC coating to absorb impact energy has improved eight times and ten times compared with original Cr3C2 and hard chrome plating respectively. On the other hand the high temperature corrosion resistance of CMC coating showed up to 31 cycles of heating at 800°C and water quenching cooling.

  6. Implementation Challenges for Ceramic Matrix Composites in High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay

    2004-01-01

    Ceramic matrix composites are leading candidate materials for a number of applications in aeronautics, space, energy, electronics, nuclear, and transportation industries. In the aeronautics and space exploration systems, these materials are being considered for applications in hot sections of jet engines such as the combustor liner, nozzle components, nose cones, leading edges of reentry vehicles and space propulsion components. Applications in the energy and environmental industries include radiant heater tubes, heat exchangers, heat recuperators, gas and diesel particulate filters (DPFs), and components for land based turbines for power generation. These materials are also being considered for use in the first wall and blanket components of fusion reactors. There are a number of critical issues and challenges related to successful implementation of composite materials. Fabrication of net and complex shape components with high density and tailorable matrix properties is quite expensive, and even then various desirable properties are not achievable. In this presentation, microstructure and thermomechanical properties of composites fabricated by two techniques (chemical vapor infiltration and melt infiltration), will be presented. In addition, critical need for robust joining and assembly technologies in successful implementation of these systems will be discussed. Other implementation issues will be discussed along with advantages and benefits of using these materials for various components in high temperature applications.

  7. LDEF results for polymer matrix composite experiment AO 180

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.

    1992-01-01

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

  8. LDEF results for polymer matrix composite experiment AO 180

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.

    1992-01-01

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

  9. Multiscale modeling of PVDF matrix carbon fiber composites

    NASA Astrophysics Data System (ADS)

    Greminger, Michael; Haghiashtiani, Ghazaleh

    2017-06-01

    Self-sensing carbon fiber reinforced composites have the potential to enable structural health monitoring that is inherent to the composite material rather than requiring external or embedded sensors. It has been demonstrated that a self-sensing carbon fiber reinforced polymer composite can be created by using the piezoelectric polymer polyvinylidene difluoride (PVDF) as the matrix material and using a Kevlar layer to separate two carbon fiber layers. In this configuration, the electrically conductive carbon fiber layers act as electrodes and the Kevlar layer acts as a dielectric to prevent the electrical shorting of the carbon fiber layers. This composite material has been characterized experimentally for its effective d 33 and d 31 piezoelectric coefficients. However, for design purposes, it is desirable to obtain a predictive model of the effective piezoelectric coefficients for the final smart composite material. Also, the inverse problem can be solved to determine the degree of polarization obtained in the PVDF material during polarization by comparing the effective d 33 and d 31 values obtained in experiment to those predicted by the finite element model. In this study, a multiscale micromechanics and coupled piezoelectric-mechanical finite element modeling approach is introduced to predict the mechanical and piezoelectric performance of a plain weave carbon fiber reinforced PVDF composite. The modeling results show good agreement with the experimental results for the mechanical and electrical properties of the composite. In addition, the degree of polarization of the PVDF component of the composite is predicted using this multiscale modeling approach and shows that there is opportunity to drastically improve the smart composite’s performance by improving the polarization procedure.

  10. Effect of Mercerization and Electron-Beam Irradiation on Mechanical Properties of High Density Polyethylene (HDPE) / Brazil Nut Pod Fiber (BNPF) Bio-Composites

    NASA Astrophysics Data System (ADS)

    Campos, Rejane D.; Sotenko, Maria; Hosur, Mahesh; Jeelani, Shaik; Díaz, Francisco R. V.; Moura, Esperidiana A. B.; Kirwan, Kerry; Seo, Emilia S. M.

    The use of natural fibers with polymeric resins has spread rapidly. In order to improve the mechanical properties of material, in this work, two variables were used: mercerization and electron beam irradiation. This paper describes the preparation and characterization of bio-composites that were prepared in two different routes using green high density polyethylene (HDPE) and Brazil nut pod fiber (BNPF): the first was to irradiate the composite with 150 kGy and the second was to irradiate the matrix with 15 kGy followed by composite preparation. In both cases mercerized and non-mercerized fibers were used. The irradiation process was carried out using a 1.5 MeV electron beam accelerator, at room temperature and in the presence of air. The material was characterized to evaluate the effect of treatment on mechanical properties of material.

  11. Metal matrix coated fiber composites and the methods of manufacturing such composites

    DOEpatents

    Weeks, Jr., Joseph K.; Gensse, Chantal

    1993-01-01

    A fiber coating which allows ceramic or metal fibers to be wetted by molten metals is disclosed. The coating inhibits degradation of the physical properties caused by chemical reaction between the fiber and the coating itself or between the fiber and the metal matrix. The fiber coating preferably includes at least a wetting layer, and in some applications, a wetting layer and a barrier layer between the fiber and the wetting layer. The wetting layer promotes fiber wetting by the metal matrix. The barrier layer inhibits fiber degradation. The fiber coating permits the fibers to be infiltrated with the metal matrix resulting in composites having unique properties not obtainable in pure materials.

  12. Evaluation of Concepts for Mulitiple Application Thermal Reactor for Irradiation eXperiments (MATRIX)

    SciTech Connect

    Michael A. Pope; Hans D. Gougar; John M. Ryskamp

    2013-09-01

    The Advanced Test Reactor (ATR) is a high power density test reactor specializing in fuel and materials irradiation. For more than 45 years, the ATR has provided irradiations of materials and fuels testing along with radioisotope production. Originally operated primarily in support of the Offcie of Naval Reactors (NR), the mission has gradually expanded to cater to other customers, such as the DOE Office of Nuclear Energy (NE), private industry, and universities. Unforeseen circumstances may lead to the decommissioning of ATR, thus leaving the U.S. Government without a large-scale materials irradiation capability to meet the needs of its nuclear energy and naval reactor missions. In anticipation of this possibility, work was performed under the Laboratory Directed Research and Development (LDRD) program to investigate test reactor concepts that could satisfy the current missions of the ATR along with an expanded set of secondary missions. This work can be viewed as an update to a project from the 1990’s called the Broad Application Test Reactor (BATR). In FY 2012, a survey of anticipated customer needs was performed, followed by analysis of the original BATR concepts with fuel changed to low-enriched uranium. Departing from these original BATR designs, four concepts were identified for further analysis in FY2013. The project informally adopted the acronym MATRIX (Multiple-Application Thermal Reactor for Irradiation eXperiments). This report discusses analysis of the four MATRIX concepts along with a number of variations on these main concepts. Designs were evaluated based on their satisfaction of anticipated customer requirements and the “Cylindrical” variant was selected for further analysis of options. This downselection should be considered preliminary and the backup alternatives should include the other three main designs. The baseline Cylindrical MATRIX design is expected to be capable of higher burnup than the ATR (or longer cycle length given a

  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. Double Vacuum Bag Process for Resin Matrix Composite Manufacturing

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung (Inventor); Jensen, Brian J. (Inventor)

    2007-01-01

    A double vacuum bag molding assembly with improved void management and laminate net shape control which provides a double vacuum enviromnent for use in fabricating composites from prepregs containing air and/or volatiles such as reactive resin matrix composites or composites from solvent containing prepregs with non-reactive resins matrices. By using two vacuum environments during the curing process, a vacuum can be drawn during a B-stage of a two-step cycle without placing the composite under significant relative pressure. During the final cure stage, a significant pressure can be applied by releasing the vacuum in one of the two environments. Inner and outer bags are useful for creating the two vacuum environments with a perforated tool intermediate the two. The composite is placed intermediate a tool plate and a caul plate in the first environment with the inner bag and tool plate defining the first environment. The second environment is characterized by the outer bag which is placed over the inner bag and the tool plate.

  15. UV irradiation and desiccation modulate the three-dimensional extracellular matrix of Nostoc commune (Cyanobacteria).

    PubMed

    Wright, Deborah J; Smith, Sue C; Joardar, Vinita; Scherer, Siegfried; Jervis, Jody; Warren, Andrew; Helm, Richard F; Potts, Malcolm

    2005-12-02

    Cyanobacterium Nostoc commune can tolerate the simultaneous stresses of desiccation, UV irradiation, and oxidation. Acidic WspA, of approximately 33.6 kDa, is secreted to the three-dimensional extracellular matrix and accounts for greater than 70% of the total soluble protein. The wspA gene of N. commune strain DRH1 was cloned and found in a single genomic copy, in a monocistronic operon. Transcription of wspA and sodF (superoxide dismutase), and synthesis and secretion of WspA, were induced upon desiccation or UV-A/B irradiation of cells. Recombinant WspA binds the UV-A/B absorbing pigment scytonemin through non-covalent interactions. WspA peptide polymorphism, and heterogeneity of multiple wspA sequences within cells of a single colony, account for distinct WspA isoforms. WspA has no similarity to entries in the sequence databases and wspA, a possible xenolog, is restricted to a subset of strains in the "form species" N. commune characterized through group I intron phylogeny. We hypothesize that WspA plays a central role in the global stress response of N. commune through modulation of the structure and function of the three-dimensional extracellular matrix, particularly the transport, distribution, and/or macromolecular architecture of mycosporine and scytonemin UV-A/B absorbing pigment complexes.

  16. Effect of Matrix Multicracking on the Hysteresis Loops of Carbon-Fiber-Reinforced Cross-Ply Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Li, L. B.

    2017-01-01

    The effect of matrix multicracking on the stress-strain hysteresis loops of cross-ply C/SiC ceramic-matrix composites (CMCs) under cyclic loading/unloading was investigated. When matrix multicracking and fiber/matrix interface debonding occur in the 0° plies, fiber slipping relative to the matrix in the debonded region of interface is the mainly reason for occurrence of the loops. The interfacial slip lengths, i.e., the debonded lengths of interface are determined, with consideration of matrix multicracking in the 90° and 0° plies, by using the fracture mechanics approach. The effects of peak stress, fiber volume content, fiber/matrix interfacial shear stress, and number of cycles on the hysteresis loops are analyzed. The stress-strain hysteresis loops of cross-ply C/SiC composites corresponding to different peak stresses and numbers of cycles are predicted.

  17. Ceramic matrix composites for rocket engine turbine applications

    NASA Technical Reports Server (NTRS)

    Herbell, Thomas P.; Eckel, Andrew J.

    1992-01-01

    A program to establish the potential for introducing fiber reinforced ceramic matrix composites (FRCMC) in future rocket engine turbopumps was instituted in 1987. A brief summary of the overall program (both contract and in-house research) is presented. Tests at NASA Lewis include thermal upshocks in a hydrogen/oxygen test rig capable of generating heating rates up to 2500 C/sec. Post thermal upshock exposure evaluation includes the measurement of residual strength and failure analysis. Test results for monolithic ceramics and several FRCMC are presented. Hydrogen compatibility was assessed by isothermal exposure of monolithic ceramics in high temperature gaseous hydrogen plus water vapor.

  18. Ceramic matrix composites for rocket engine turbine applications

    NASA Technical Reports Server (NTRS)

    Herbell, Thomas P.; Eckel, Andrew J.

    1992-01-01

    A program to establish the potential for introducing fiber reinforced ceramic matrix composites (FRCMC) in future rocket engine turbopumps was instituted in 1987. A brief summary of the overall program (both contract and in-house research) is presented. Tests at NASA Lewis include thermal upshocks in a hydrogen/oxygen test rig capable of generating heating rates up to 2500 C/sec. Post thermal upshock exposure evaluation includes the measurement of residual strength and failure analysis. Test results for monolithic ceramics and several FRCMC are presented. Hydrogen compatibility was assessed by isothermal exposure of monolithic ceramics in high temperature gaseous hydrogen plus water vapor.

  19. Energy absorption mechanisms during crack propagation in metal matrix composites

    NASA Technical Reports Server (NTRS)

    Murphy, D. P.; Adams, D. F.

    1979-01-01

    The stress distributions around individual fibers in a unidirectional boron/aluminum composite material subjected to axial and transverse loadings are being studied utilizing a generalized plane strain finite element analysis. This micromechanics analysis was modified to permit the analysis of longitudinal sections, and also to incorporate crack initiation and propagation. The analysis fully models the elastoplastic response of the aluminum matrix, as well as temperature dependent material properties and thermal stress effects. The micromechanics analysis modifications are described, and numerical results are given for both longitudinal and transverse models loaded into the inelastic range, to first failure. Included are initially cracked fiber models.

  20. Analytical Micromechanics Modeling Technique Developed for Ceramic Matrix Composites Analysis

    NASA Technical Reports Server (NTRS)

    Min, James B.

    2005-01-01

    Ceramic matrix composites (CMCs) promise many advantages for next-generation aerospace propulsion systems. Specifically, carbon-reinforced silicon carbide (C/SiC) CMCs enable higher operational temperatures and provide potential component weight savings by virtue of their high specific strength. These attributes may provide systemwide benefits. Higher operating temperatures lessen or eliminate the need for cooling, thereby reducing both fuel consumption and the complex hardware and plumbing required for heat management. This, in turn, lowers system weight, size, and complexity, while improving efficiency, reliability, and service life, resulting in overall lower operating costs.

  1. Ceramics and ceramic matrix composites - Aerospace potential and status

    NASA Technical Reports Server (NTRS)

    Levine, Stanley R.

    1992-01-01

    Thermostructural ceramics and ceramic-matrix composites are attractive in numerous aerospace applications; the noncatastrophic fracture behavior and flaw-insensitivity of continuous fiber-reinforced CMCs renders them especially desirable. The present development status evaluation notes that, for most highly-loaded high-temperature applications, the requisite fiber-technology base is at present insufficient. In addition to materials processing techniques, the life prediction and NDE methods are immature and require a projection of 15-20 years for the maturity of CMC turbine rotors. More lightly loaded, moderate temperature aircraft engine applications are approaching maturity.

  2. Ceramic Matrix Composites (CMC) Life Prediction Development - 2003

    NASA Technical Reports Server (NTRS)

    Levine, Stanley R.; Calomino, Anthony M.; Verrilli, Michael J.; Thomas, David J.; Halbig, Michael C.; Opila, Elizabeth J.; Ellis, John R.

    2003-01-01

    Accurate life prediction is critical to successful use of ceramic matrix composites (CMCs). The tools to accomplish this are immature and not oriented toward the behavior of carbon fiber reinforced silicon carbide (C/SiC), the primary system of interest for many reusable and single mission launch vehicle propulsion and airframe applications. This paper describes an approach and progress made to satisfy the need to develop an integrated life prediction system that addresses mechanical durability and environmental degradation of C/SiC.

  3. Numerical analysis on thermal drilling of aluminum metal matrix composite

    NASA Astrophysics Data System (ADS)

    Hynes, N. Rajesh Jesudoss; Maheshwaran, M. V.

    2016-05-01

    The work-material deformation is very large and both the tool and workpiece temperatures are high in thermal drilling. Modeling is a necessary tool to understand the material flow, temperatures, stress, and strains, which are difficult to measure experimentally during thermal drilling. The numerical analysis of thermal drilling process of aluminum metal matrix composite has been done in the present work. In this analysis the heat flux of different stages is calculated. The calculated heat flux is applied on the surface of work piece and thermal distribution is predicted in different stages during the thermal drilling process.

  4. Damage tolerance in discontinuously reinforced metal-matrix composites

    SciTech Connect

    Rack, H.J.; Ratnaparkhi, P.

    1988-11-01

    Properly designed discontinuously-reinforced MMCs have been projected by linear-elastic fracture mechanics to be competitive, on both cost and performance bases, with cross-plied graphite-reinforced polymer-matrix composites and continuously-reinforced MMCs. With respect to the latter, discontinuously-reinforced MMCs achieve considerable advantages in virtue of their lower-cost reinforcements and their fabricability by standard metal-working practices. Discontinuously reinforced MMC billets can also be produced through powder-blending and direct-spraying techniques. SiC short fibers, whiskers, and particulates are typical of the discontinuous reinforcements used in 2124 and 6061 aluminum matrices. 18 references.

  5. Pressurized Shell Molds For Metal-Matrix Composites

    NASA Technical Reports Server (NTRS)

    Kashalikar, Uday K.; Lusignea, Richard N.; Cornie, James

    1993-01-01

    Balanced-pressure molds used to make parts in complex shapes from fiber-reinforced metal-matrix composite materials. In single step, molding process makes parts in nearly final shapes; only minor finishing needed. Because molding pressure same on inside and outside, mold does not have to be especially strong and can be made of cheap, nonstructural material like glass or graphite. Fibers do not have to be cut to conform to molds. Method produces parts with high content of continuous fibers. Parts stiff but light in weight, and coefficients of thermal expansion adjusted. Parts resistant to mechanical and thermal fatigue superior to similar parts made by prior fabrication methods.

  6. Thermal-vacuum effects on polymer matrix composite materials

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.; Mabson, G. E.

    1991-01-01

    Results are presented on the thermal-vacuum response of a variety of fiber reinforced polymers matrix composites that comprised the UTIAS experiment on the LDEF satellite. Theoretical temperature-time predictions for this experiment are in excellent agreement with test data. Results also show quite clearly the effect of outgassing in the dimensional changes of these materials and the corresponding coefficients of thermal expansion. Finally, comparison with ground-based simulation tests are presented as well. Use of these data for design purposes are also given.

  7. Squeeze flow and compaction behavior of toughened polyimide matrix composites

    NASA Technical Reports Server (NTRS)

    Lee, Byung Lip; Pater, R.; Soucek, M. D.

    1991-01-01

    The main emphasis was placed upon the squeeze flow and compaction behavior of the Lewis Research Center (LaRC) research project series polyimide matrix composites. The measurement of squeeze film flow behavior was performed by a plastometer which monitors the change of thickness of a prepreg specimen laid between two parallel plates under the specified temperature and pressure history. A critical evaluation of the plastometer data was attempted by examining the morphology of the specimen at various points during the squeeze flow. The effects of crosslinks (Mc) of resin, imidization (B-ataging) condition, and pressure on the squeeze flow behavior were examined. Results are given.

  8. Ceramic Matrix Composite Turbine Disk for Rocket Engines

    NASA Technical Reports Server (NTRS)

    Effinger, Mike; Genge, Gary; Kiser, Doug

    2000-01-01

    NASA has recently completed testing of a ceramic matrix composite (CMC), integrally bladed disk (blisk) for rocket engine turbopumps. The turbopump's main function is to bring propellants from the tank to the combustion chamber at optimal pressures, temperatures, and flow rates. Advantages realized by using CMC blisks are increases in safety by increasing temperature margins and decreasing costs by increasing turbopump performance. A multidisciplinary team, involving materials, design, structural analysis, nondestructive inspection government, academia, and industry experts, was formed to accomplish the 4.5 year effort. This article will review some of the background and accomplishments of the CMC Blisk Program relative to the benefits of this technology.

  9. Computational simulation of high temperature metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Chamis, C. C.

    1991-01-01

    Computational procedures were developed for simulating the thermal and mechanical behaviors of high-temperature metal-matrix composites (HT-MMCs) in the following application areas: (1) the behavior of HT-MMCs from micromechanics to laminate, (2) the structural response of HT-MMCs' simple and complex structural components, (3) the HT-MMC microfracture, and (4) the tailoring of HT-MMCs' behavior for optimum specific performances. Representative results are presented from each area of application, illustrating the effectiveness of the computational procedures.

  10. Computational simulation of high temperature metal matrix composite behavior

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Chamis, Christos C.

    1991-01-01

    Computational procedures are described to simulate the thermal and mechanical behavior of high temperature metal matrix composite (HT MMC) in the following four broad areas: (1) behavior of HT MMC from micromechanics to laminate; (2) HT MMC structural response for simple and complex structural components; (3) HT MMC microfracture; and (4) tailoring of HT MMC behavior for optimum specific performance. Representative results from each area are presented to illustrate the effectiveness of the computational simulation procedures. Relevant reports are referenced for extended discussion regarding the specific area.

  11. Simulation of Damage Evolution in Discontinously Reinforced Metal Matrix Composites

    SciTech Connect

    Biner, S.B.; Hu, Shenyang Y.

    2009-08-01

    First, a phase-field model for elastic-plastic solids obeying von Mises yield criterion will be described. Then, this phase-field model will be extended to simulate the damage evolution due to nucleation and growth of voids in ductile matrix for discontinuously reinforced composites. The role of reinforcement morphology and the modulus effects leading to final failure all included in the simulations in an effort to make a parametric investigation. The advantages and disadvantages of such phase-field modeling approach in comparison to well established other continuum methods will be elucidated.

  12. Pressurized Shell Molds For Metal-Matrix Composites

    NASA Technical Reports Server (NTRS)

    Kashalikar, Uday K.; Lusignea, Richard N.; Cornie, James

    1993-01-01

    Balanced-pressure molds used to make parts in complex shapes from fiber-reinforced metal-matrix composite materials. In single step, molding process makes parts in nearly final shapes; only minor finishing needed. Because molding pressure same on inside and outside, mold does not have to be especially strong and can be made of cheap, nonstructural material like glass or graphite. Fibers do not have to be cut to conform to molds. Method produces parts with high content of continuous fibers. Parts stiff but light in weight, and coefficients of thermal expansion adjusted. Parts resistant to mechanical and thermal fatigue superior to similar parts made by prior fabrication methods.

  13. Sol/Gel Processing Techniques for Glass Matrix Composites.

    DTIC Science & Technology

    1987-11-01

    development of a general technique (i.e., Pyrex is less susceptible to devitrification than SiO2 or TiO2 -SiO 2 ). In addition. the properties of these sol / gel ...of a sol / gel process for SIC 2 and SiO2 - TiO2 - together with a data base for their densification - are prerequisite to the successful fabrication of...S~%ad~ 5~ ~ ~ *~~~~;:>;::L-; 1: ’*~~’~ ’S. AFWL-TN-86-59 AFWL-TN- 86-59 00 SOL / GEL PROCESSING TECHNIQUES FOR GLASS MATRIX COMPOSITES 0) C. G

  14. Suitability of gamma irradiated chitosan based membranes as matrix in drug release system.

    PubMed

    Casimiro, M H; Gil, M H; Leal, J P

    2010-08-16

    To test the possibility of obtain a material simultaneously biocompatible and microbiologically safe to be used as wound dressing material and as a matrix for drug release system, membranes with different initial contents in chitosan and 2-hydroxyethyl methacrylate (HEMA) have been prepared by gamma irradiation from a (60)Co source. The antimicrobial activity of obtained membranes against several reference strains was evaluated after inoculation. Sub-lethal gamma radiation doses were also applied in artificially contaminated membranes and the D(values) of microorganisms in use were determined in order to predict which radiation dose could guarantee membranes microbiological safety. In vitro haemolysis tests were also performed using drug loaded membranes irradiated at different doses. Results point out that those membranes naturally exhibit antimicrobial properties. Also show that, over the studied range values, drug loaded irradiated membranes display a non-significant level of haemolysis. These features show that the application of prepared membranes as a transdermal drug release system "ready to use" is viable.

  15. Low Burnup Inert Matrix Fuels Performance: TRANSURANUS Analysis of the Halden IFA-652 First Irradiation Cycle

    SciTech Connect

    Calabrese, R.; Vettraino, F.; Tverberg, T.

    2006-07-01

    The inert matrix fuels are a promising option to reduce-eliminate worldwide plutonium stockpiles by burning it in LWRs. These fuels, where plutonium is hosted in a U-free inert matrix phase, may reach high burning efficiency while preventing new plutonium build-up under irradiation. A specific investigation on CSZ and thoria inert matrices has been developed by ENEA since several years. In-pile testing on the ENEA-conceived innovative fuels is ongoing in the OECD Halden HBWR since June 2000 (IFA-652 experiment). The registered burnup at the end of 2005 is about 38 MWd.kgU{sub eq}{sup -1} vs. 45 MWd.kgU{sub eq}{sup -1} (40 MWd.kgUOX{sub eq}{sup -1}) target. Fuel pins are equipped with fuel temperature thermocouples, internal pressure transducers and fuel stack elongation sensors, with the task of studying thermal conductivity and its degradation with burnup, densification-swelling behaviour and the FGR. In this paper, the response at low burnup (< 7 MWd.kgU{sub eq}{sup -1}) of CSZ-based fuels loaded in IFA-652, is analysed by means of the TRANSURANUS code. To this purpose, a comprehensive modelling of the above mentioned un-irradiated fuels, mainly relying on the thermophysical characterisation performed at the JRC/ITU-Karlsruhe, has been implemented in a custom TRANSURANUS version (TU-IMF). A comparison of the code predictions vs. the experimental data, aimed at evaluating the early-stage under irradiation phenomena, particularly densification and relocation, has been performed. (authors)

  16. Cosmogenic He and Ne in chondrules from clastic matrix and a lithic clast of Murchison: No pre-irradiation by the early sun

    NASA Astrophysics Data System (ADS)

    Riebe, My E. I.; Huber, Liliane; Metzler, Knut; Busemann, Henner; Luginbuehl, Stefanie M.; Meier, Matthias M. M.; Maden, Colin; Wieler, Rainer

    2017-09-01

    Whether or not some meteorites retain a record of irradiation by a large flux of energetic particles from the early sun in the form of excesses of cosmic-ray produced noble gases in individual crystals or single chondrules is a topic of ongoing debate. Here, we present He and Ne isotopic data for individual chondrules in Murchison, a chondritic regolith breccia of the CM group. We separated 27 chondrules from a clastic matrix portion and 26 chondrules from an adjacent single so-called ;primary accretionary rock; (Metzler et al., 1992). All chondrules from the primary rock fragment are expected to share a common irradiation history, whereas chondrules from the clastic matrix were stirred in the regolith independently of each other. All ;primary rock chondrules; and 23 of the ;matrix chondrules; have very similar concentrations of cosmogenic 3He and 21Ne, corresponding to a cosmic-ray exposure age to galactic cosmic rays (GCR) of ∼1.3-1.9 Ma, in the range of Murchison's meteoroid exposure age determined with cosmogenic radionuclides. Four clastic matrix chondrules contain excesses of cosmogenic 3He and 21Ne, corresponding to nominal 4π exposure ages of ∼4-∼29 Ma, with a Ne isotopic composition as expected for production by GCR. If the fraction of excess cosmogenic gas bearing chondrules in the primary rock and clastic matrix were the same, we would expect this result with a statistical probability of only 0.5 - 2.7%. Therefore, the exposure age distributions for Murchison chondrules in primary rock and clastic matrix are very likely different. Such a difference is expected if the excess cosmogenic gas was acquired by some of the matrix chondrules in the regolith, but not if chondrules were irradiated in the solar nebula by the early sun before they accreted on the Murchison parent body. Therefore, Murchison does not provide evidence for irradiation by a high fluence of energetic particles from the early sun. By inference, this statement likely holds for the

  17. Graphite fiber reinforced thermoplastic glass matrix composites for use at 1000 F

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Minford, E. J.

    1985-01-01

    The fabrication and properties of the graphite fiber reinforced glass matrix composite system are described. By reinforcing borosilicate glass with graphite fibers it has been possible to develop a composite whose properties can be compared favorably with resin matrix counterparts. Both high elastic modulus and strength can be obtained and maintained to temperatures of approximately 600 C. In addition, composite dimensional stability is superior to resin or metal matrix systems due to the low thermal expansion behavior of the glass matrix.

  18. Biaxial Yield Surface Investigation of Polymer-Matrix Composites

    PubMed Central

    Ye, Junjie; Qiu, Yuanying; Zhai, Zhi; He, Zhengjia

    2013-01-01

    This article presents a numerical technique for computing the biaxial yield surface of polymer-matrix composites with a given microstructure. Generalized Method of Cells in combination with an Improved Bodner-Partom Viscoplastic model is used to compute the inelastic deformation. The validation of presented model is proved by a fiber Bragg gratings (FBGs) strain test system through uniaxial testing under two different strain rate conditions. On this basis, the manufacturing process thermal residual stress and strain rate effect on the biaxial yield surface of composites are considered. The results show that the effect of thermal residual stress on the biaxial yield response is closely dependent on loading conditions. Moreover, biaxial yield strength tends to increase with the increasing strain rate. PMID:23529150

  19. Development of Metal Matrix Composites for NASA'S Advanced Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2000-01-01

    The state-of-the-art development of several aluminum and copper based Metal Matrix Composites (MMC) for NASA's advanced propulsion systems will be presented. The presentation's goal is to provide an overview of NASA-Marshall Space Flight Center's planned and on-going activities in MMC for advanced liquid rocket engines such as the X-33 vehicle's Aerospike and X-34 Fastrac engine. The focus will be on lightweight and environmental compatibility with oxygen and hydrogen of key MMC materials, within each NASA's new propulsion application, that will provide a high payoff for NASA's reusable launch vehicle systems and space access vehicles. Advanced MMC processing techniques such as plasma spray, centrifugal casting, pressure infiltration casting will be discussed. Development of a novel 3D printing method for low cost production of composite preform, and functional gradient MMC to enhanced rocket engine's dimensional stability will be presented.

  20. Flexural analysis of palm fiber reinforced hybrid polymer matrix composite

    NASA Astrophysics Data System (ADS)

    Venkatachalam, G.; Gautham Shankar, A.; Raghav, Dasarath; Santhosh Kiran, R.; Mahesh, Bhargav; Kumar, Krishna

    2015-07-01

    Uncertainty in availability of fossil fuels in the future and global warming increased the need for more environment friendly materials. In this work, an attempt is made to fabricate a hybrid polymer matrix composite. The blend is a mixture of General Purpose Resin and Cashew Nut Shell Liquid, a natural resin extracted from cashew plant. Palm fiber, which has high strength, is used as reinforcement material. The fiber is treated with alkali (NaOH) solution to increase its strength and adhesiveness. Parametric study of flexure strength is carried out by varying alkali concentration, duration of alkali treatment and fiber volume. Taguchi L9 Orthogonal array is followed in the design of experiments procedure for simplification. With the help of ANOVA technique, regression equations are obtained which gives the level of influence of each parameter on the flexure strength of the composite.

  1. Manufacturing process of a multifunctional composite panel with nanocharged matrix

    NASA Astrophysics Data System (ADS)

    Volponi, R.; Spena, P.; De Nicola, F.; Guadagno, L.; Raimondo, M.; Vietri, U.

    2016-05-01

    This paper proposes an effective manufacturing process developed to overcome drawbacks that can occur using a nanofilled resin as matrix in aeronautical composites. Nanoparticles embedded in epoxy resins impregnating carbon fibers are able to improve a composite with new desired functionalities. As soon as the nanoparticles are dispersed in a resin, the viscosity dizzily rises and usually, the traditional manufacturing processes are not suitable to obtain a good quality of the manufactured panels. An alternative method has been developed starting from the Resin Film Infusion (RFI) process. This method has been firstly tested on several flat panels, and then it has been transferred on a more complex shaped panel with three stringers. In this work, a flame resistant resin based on a tetrafunctional epoxy precursor filled with carbon nanotubes to increase electrical conductivity, has been used for the panel manufacturing.

  2. Fracture and Fatigue Behaviour of Aluminium Matrix Composite Automotive Pistons

    NASA Astrophysics Data System (ADS)

    García-Romero, Ane M.; Egizabal, Pedro; Irisarri, Angel M.

    2010-02-01

    The fracture and fatigue behaviour of prototype automotive pistons produced in an aluminium alloy matrix composite in industrial conditions has been studied. Fracture toughness increased when the testing temperature rose from 20° to 75°C and kept near constant up to 250°C, when a significantly lower value was recorded. A change in the failure operating mechanism, which can explain this trend, was observed by analysing the fracture surfaces in the scanning electron microscope. Room temperature fatigue tests performed with R = 0.1 stress ratio led to an average value of the Paris law exponent higher than those reported in aluminium alloys but low for an industrially produced brittle composite. A higher exponent and a much larger scattering were observed in those fatigue tests carried out under R = 0.5 stress ratio.

  3. Update on CMH-17 Volume 5: Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    David, Kaia; Pierce, Jennifer; Kiser, James; Keith, William P.; Wilson, Gregory S.

    2015-01-01

    CMC components are projected to enter service in commercial aircraft in 2016. A wide range of issues must be addressed prior to certification of this hardware. The Composite Materials Handbook-17, Volume 5 on ceramic matrix composites is being revised to support FAA certification of CMCs for hot structure and other elevated temperature applications. The handbook supports the development and use of CMCs through publishing and maintaining proven, reliable engineering information and standards that have been thoroughly reviewed. Volume 5 will contain detailed sections describing CMC materials processing, design analysis guidelines, testing procedures, and data analysis and acceptance. A review of the status of and plans for two of these areas, which are being addressed by the M and P Working Group and the Testing Working Group, will be presented along with a timeline for the preparation of CMH-17, Volume 5.

  4. Development of Metal Matrix Composites for NASA'S Advanced Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2000-01-01

    The state-of-the-art development of several aluminum and copper based Metal Matrix Composites (MMC) for NASA's advanced propulsion systems will be presented. The presentation's goal is to provide an overview of NASA-Marshall Space Flight Center's planned and on-going activities in MMC for advanced liquid rocket engines such as the X-33 vehicle's Aerospike and X-34 Fastrac engine. The focus will be on lightweight and environmental compatibility with oxygen and hydrogen of key MMC materials, within each NASA's new propulsion application, that will provide a high payoff for NASA's reusable launch vehicle systems and space access vehicles. Advanced MMC processing techniques such as plasma spray, centrifugal casting, pressure infiltration casting will be discussed. Development of a novel 3D printing method for low cost production of composite preform, and functional gradient MMC to enhanced rocket engine's dimensional stability will be presented.

  5. Probabilistic micromechanics and macromechanics of polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Mase, G. T.; Murthy, P. L. N.; Chamis, Christos C.

    1991-01-01

    A probabilistic evaluation of an eight ply graphite-epoxy quasi-isotropic laminate was completed using the Integrated Composite Analyzer (ICAN) in conjunction with Monte Carlo simulation and Fast Probability Integration (FPI) techniques. Probabilistic input included fiber and matrix properties, fiber misalignment, fiber volume ratio, void volume ratio, ply thickness and ply layup angle. Cumulative distribution functions (CDFs) for select laminate properties are given. To reduce the number of simulations, a Fast Probability Integration (FPI) technique was used to generate CDFs for the select properties in the absence of fiber misalignment. These CDFs were compared to a second Monte Carlo simulation done without fiber misalignment effects. It was found that FPI requires fewer simulations to obtain the cumulative distribution functions as opposed to Monte Carlo simulation techniques. Furthermore, FPI provides valuable information regarding the sensitivities of composite properties to the constituent properties, fiber volume ratio and void volume ratio.

  6. Laser Machining of Melt Infiltrated Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Jarmon, D. C.; Ojard, G.; Brewer, D.

    2012-01-01

    As interest grows in considering the use of ceramic matrix composites for critical components, the effects of different machining techniques, and the resulting machined surfaces, on strength need to be understood. This work presents the characterization of a Melt Infiltrated SiC/SiC composite material system machined by different methods. While a range of machining approaches were initially considered, only diamond grinding and laser machining were investigated on a series of tensile coupons. The coupons were tested for residual tensile strength, after a stressed steam exposure cycle. The data clearly differentiated the laser machined coupons as having better capability for the samples tested. These results, along with micro-structural characterization, will be presented.

  7. OC Chondrule, Rim and Matrix Compositions: A Model

    NASA Astrophysics Data System (ADS)

    Alexander, C. M. O'd.

    1996-03-01

    The peak temperatures chondrules experienced, based on their liquidus temperatures, range from 1500 K to 2000 K. At these temperatures and nebular pressures most elements are volatile, but generally the alkali metals and S have been the only major elements considered as such. However, correlated variations in Mg and Al abundances, if they are not due to precursor compositions, require the loss of up to 50% of the SiO2 from some chondrules. The more volatile FeO would have been lost to an even greater extent. Here it is shown that if the material lost from chondrules recondenses onto the fine grained material which survived the chondrule forming process, chondrule rim and matrix compositions can be explained.

  8. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 2; Composite Micromechanical Model

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this second paper of a two part report, a three-dimensional composite micromechanical model is described which allows for the analysis of the rate dependent, nonlinear deformation response of a polymer matrix composite. Strain rate dependent inelastic constitutive equations utilized to model the deformation response of a polymer are implemented within the micromechanics method. The deformation response of two representative laminated carbon fiber reinforced composite materials with varying fiber orientation has been predicted using the described technique. The predicted results compare favorably to both experimental values and the response predicted by the Generalized Method of Cells, a well-established micromechanics analysis method.

  9. Micromechanical analysis of a continuous fiber metal matrix composite including the effects of matrix viscoplasticity and evolving damage

    NASA Astrophysics Data System (ADS)

    Allen, D. H.; Jones, R. H.; Boyd, J. G.

    1994-03-01

    A THERMOMECHANICAL ANALYSIS of a metal matrix continuous fiber composite is performed herein. The analysis includes the effects of matrix inelasticity and interface cracking. Due to these nonlinearities, the analysis is performed computationally using the finite element method. Matrix inelasticity is modeled with a rate dependent viscoplasticity model. Interface fracture is modeled by the use of a nonlinear interface constitutive model. The problem formulation is summarized, and results are given for a typical SiC-Ti composite at elevated temperature. Preliminary results indicate that rate dependent viscoplasticity can be a significant mechanism for dissipating the energy available for interface fracture, thus contributing to improved macroscopic ductility of the composite.

  10. Graphite Fiber Textile Preform/Cooper Matrix Composites

    NASA Technical Reports Server (NTRS)

    Filatovs, George J.

    1998-01-01

    The purpose of this research was to produce a finned tube constructed of a highly conductive braided graphite fiber preform infiltrated with a copper matrix. In addition, the tube was to be fabricated with an integral geometry. The preform was integral in the sense that the tube and the fin could be braided to yield one continuous part. This composite component is a candidate for situations with high heat transmitting and radiation requirements. A proof-of-concept finned tube was braided and infiltrated with a copper matrix proving that a viable process was developed to fabricate the desired component. Braiding of high conductivity carbon fibers required much trial-and-error and development of special procedures. There are many tradeoffs between braidability and fiber conductivity. To understand the properties and structure of the braided finned tube, an geometric model of the braid structure was derived. This derivation set the basis for the research because knowing the tow orientations helped decipher the thermal as well as the mechanical and conduction tendencies. Infiltration of the fibers into a copper matrix was a complex procedure, and was performed by TRA, of Salt Lake City, Utah, using a proprietary process. Several batches were fabricated with a final, high quality batch serving as a confirming proof-of-concept.

  11. Life Modeling and Design Analysis for Ceramic Matrix Composite Materials

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The primary research efforts focused on characterizing and modeling static failure, environmental durability, and creep-rupture behavior of two classes of ceramic matrix composites (CMC), silicon carbide fibers in a silicon carbide matrix (SiC/SiC) and carbon fibers in a silicon carbide matrix (C/SiC). An engineering life prediction model (Probabilistic Residual Strength model) has been developed specifically for CMCs. The model uses residual strength as the damage metric for evaluating remaining life and is posed probabilistically in order to account for the stochastic nature of the material s response. In support of the modeling effort, extensive testing of C/SiC in partial pressures of oxygen has been performed. This includes creep testing, tensile testing, half life and residual tensile strength testing. C/SiC is proposed for airframe and propulsion applications in advanced reusable launch vehicles. Figures 1 and 2 illustrate the models predictive capabilities as well as the manner in which experimental tests are being selected in such a manner as to ensure sufficient data is available to aid in model validation.

  12. Prediction of thermomechanical fatigue lives in metal matrix composites

    NASA Astrophysics Data System (ADS)

    Sehitoglu, Huseyin; Karayaka, Metin

    1992-07-01

    To identify the role of silicon carbide participate reinforcement on high-temperature thermomechanical fatigue behavior of Al 2xxx-T4, experiments have been conducted under thermomechanical out-of-phase and in-phase loading conditions. A general constitutive representation, based on Eshelby’s inclusion theory, is used for the determination of volumetric average stresses and strains under cyclic loading of the metal matrix composite. This constitutive representation is used with a life prediction model, based on the matrix stress-strain behavior, which predicts contributions of fatigue, creep, and environmental damages to failure under both isothermal and thermomechanical fatigue loading. In isothermal fatigue experiments at 200 °C and 300 °C, pure fatigue damage and creep damage are the dominant damage mechanisms in the short-life regime. In the long-life regime, however, the stress levels are too low to induce considerable creep damage; so, oxidation damage becomes dominant. When fatigue damage is dominant, the model predicts a decrease in life, based on strain range, with increasing volume fraction of reinforcement. Based on stress range, improved fatigue lives are predicted with increasing volume fraction of reinforcement. The reinforced alloy exhibits longer lives when compressive hydrostatic stresses in the matrix at the high-temperature end of the cycle reduce the creep damage.

  13. Effect of Fiber Poisson Contraction on Matrix Multicracking Evolution of Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    An analytical methodology has been developed to investigate the effect of fiber Poisson contraction on matrix multicracking evolution of fiber-reinforced ceramic-matrix composites (CMCs). The modified shear-lag model incorporated with the Coulomb friction law is adopted to solve the stress distribution in the interface slip region and intact region of the damaged composite. The critical matrix strain energy criterion which presupposes the existence of an ultimate or critical strain energy limit beyond which the matrix fails has been adopted to describe matrix multicracking of CMCs. As more energy is placed into the composite, matrix fractures and the interface debonding occurs to dissipate the extra energy. The interface debonded length under the process of matrix multicracking is obtained by treating the interface debonding as a particular crack propagation problem along the fiber/matrix interface. The effects of the interfacial frictional coefficient, fiber Poisson ratio, fiber volume fraction, interface debonded energy and cycle number on the interface debonding and matrix multicracking evolution have been analyzed. The theoretical results are compared with experimental data of unidirectional SiC/CAS, SiC/CAS-II and SiC/Borosilicate composites.

  14. Electrical behavior of carbon whisker reinforced elastomer matrix composites

    SciTech Connect

    Chellappa, V.; Chiou, Z.W.; Jang, B.Z.

    1994-12-31

    The electrical and mechanical properties of carbon whisker reinforced thermoplastic elastomer composites were investigated. The reinforcement whisker was made by a catalytic chemical vapor deposition (CCVD) process and the polymer matrix was from a thermoplastic elastomer (TPE, a butadiene-styrene block co-polymer). The electrical resistivity ({rho}) of the CCVD carbon whisker-elastomer composites can be varied by uniaxial deformation (10{sup 1}-10{sup 8}{Omega}-cm) and by changing the temperature (10{sup 1}-10{sup 5}{Omega}-cm). The temperature-resistivity studies indicate, that the resistivity of these composites depend on the physical property of the elastomer. The {rho} vs 1/T curves exhibit two distinct slopes intersected at the T{sub g} of the elastomer (-50{degrees}C). Further uniaxial deformation studies at room temperature (20{degrees}C) demonstrated that the resistivity increased exponentially with the deformation. The dependence of resistivity (or conductivity) of the composites with respect to deformation and temperature was explained on the basis of electron tunnelling induced conduction. CCVD carbon whiskers can be used as a reinforcement (filler) for the elastomer and can also make them electrically conductive.

  15. Intermetallic and titanium matrix composite materials for hypersonic applications

    SciTech Connect

    Berton, B.; Surdon, G.; Colin, C. |

    1995-09-01

    As part of the French Program of Research and Technology for Advanced Hypersonic Propulsion (PREPHA) which was launched in 1992 between Aerospatiale, Dassault Aviation, ONERA, SNECMA and SEP, an important work is specially devoted to the development of titanium and intermetallic composite materials for large airframe structures. At Dassault Aviation, starting from a long experience in Superplastic Forming - Diffusion Bonding (SPF-DB) of titanium parts, the effort is brought on the manufacturing and characterization of composites made from Timet beta 21S or IMI 834 foils and Textron SCS6 fiber fabrics. At `Aersopatiale Espace & Defence`, associated since a long time about intermetallic composite materials with university research laboratories, the principal effort is brought on plasma technology to develop the gamma titanium aluminide TiAl matrix composite reinforced by protected silicon carbide fibers (BP SM 1240 or TEXTRON SCS6). The objective, is to achieve, after 3 years of time, to elaborate a medium size integrally stiffened panel (300 x 600 sq mm).

  16. Modeling Woven Polymer Matrix Composites with MAC/GMC

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M. (Technical Monitor)

    2000-01-01

    NASA's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) is used to predict the elastic properties of plain weave polymer matrix composites (PMCs). The traditional one step three-dimensional homogertization procedure that has been used in conjunction with MAC/GMC for modeling woven composites in the past is inaccurate due to the lack of shear coupling inherent to the model. However, by performing a two step homogenization procedure in which the woven composite repeating unit cell is homogenized independently in the through-thickness direction prior to homogenization in the plane of the weave, MAC/GMC can now accurately model woven PMCs. This two step procedure is outlined and implemented, and predictions are compared with results from the traditional one step approach and other models and experiments from the literature. Full coupling of this two step technique with MAC/ GMC will result in a widely applicable, efficient, and accurate tool for the design and analysis of woven composite materials and structures.

  17. Thermal and destructive interrogation of ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Ojard, Greg; Doza, Douglas; Ouyang, Zhong; Angel, Paul; Smyth, Imelda; Santhosh, Unni; Ahmad, Jalees; Gowayed, Yasser

    2015-03-01

    Ceramic matrix composites are intended for elevated temperature use and their performance at temperature must be clearly understood as insertion efforts are to be realized. Most efforts to understand ceramic matrix composites at temperature are based on their lifetime at temperature under stress based on fatigue or creep testing or residual testing after some combination of temperature, stress and time. While these efforts can be insightful especially based on their mechanical performance, there is no insight into how other properties are changing with thermal exposure. To gain additional insight into oxidation behavior of CMC samples, a series of fatigue and creep samples tested at two different temperatures were non-destructively interrogated after achieving run-out conditions by multiple thermal methods and limited X-ray CT. After non-destructive analysis, residual tensile tests were undertaken at room temperature. The resulting residual properties will be compared against the non-destructive data. Analysis will be done to see if data trends can be determined and correlated to the level and duration of exposure.

  18. Functionally Graded Al Alloy Matrix In-Situ Composites

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Subramaniya Sarma, V.; Murty, B. S.

    2010-01-01

    In the present work, functionally graded (FG) aluminum alloy matrix in-situ composites (FG-AMCs) with TiB2 and TiC reinforcements were synthesized using the horizontal centrifugal casting process. A commercial Al-Si alloy (A356) and an Al-Cu alloy were used as matrices in the present study. The material parameters (such as matrix and reinforcement type) and process parameters (such as mold temperature, mold speed, and melt stirring) were found to influence the gradient in the FG-AMCs. Detailed microstructural analysis of the composites in different processing conditions revealed that the gradients in the reinforcement modify the microstructure and hardness of the Al alloy. The segregated in-situ formed TiB2 and TiC particles change the morphology of Si particles during the solidification of Al-Si alloy. A maximum of 20 vol pct of reinforcement at the surface was achieved by this process in the Al-4Cu-TiB2 system. The stirring of the melt before pouring causes the reinforcement particles to segregate at the periphery of the casting, while in the absence of such stirring, the particles are segregated at the interior of the casting.

  19. Insect phylogenomics: results, problems and the impact of matrix composition

    PubMed Central

    Letsch, Harald O.; Meusemann, Karen; Wipfler, Benjamin; Schütte, Kai; Beutel, Rolf; Misof, Bernhard

    2012-01-01

    In this study, we investigated the relationships among insect orders with a main focus on Polyneoptera (lower Neoptera: roaches, mantids, earwigs, grasshoppers, etc.), and Paraneoptera (thrips, lice, bugs in the wide sense). The relationships between and within these groups of insects are difficult to resolve because only few informative molecular and morphological characters are available. Here, we provide the first phylogenomic expressed sequence tags data (‘EST’: short sub-sequences from a c(opy) DNA sequence encoding for proteins) for stick insects (Phasmatodea) and webspinners (Embioptera) to complete published EST data. As recent EST datasets are characterized by a heterogeneous distribution of available genes across taxa, we use different rationales to optimize the data matrix composition. Our results suggest a monophyletic origin of Polyneoptera and Eumetabola (Paraneoptera + Holometabola). However, we identified artefacts of tree reconstruction (human louse Pediculus humanus assigned to Odonata (damselflies and dragonflies) or Holometabola (insects with a complete metamorphosis); mayfly genus Baetis nested within Neoptera), which were most probably rooted in a data matrix composition bias due to the inclusion of sequence data of entire proteomes. Until entire proteomes are available for each species in phylogenomic analyses, this potential pitfall should be carefully considered. PMID:22628473

  20. Quantifying Effects of Voids in Woven Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldsmith, Marlana B.; Sankar, Bhavani V.; Haftka, Raphael T.; Goldberg, Robert K.

    2013-01-01

    Randomness in woven ceramic matrix composite architecture has been found to cause large variability in stiffness and strength. The inherent voids are an aspect of the architecture that may cause a significant portion of the variability. A study is undertaken to investigate the effects of many voids of random sizes and distributions. Response surface approximations were formulated based on void parameters such as area and length fractions to provide an estimate of the effective stiffness. Obtaining quantitative relationships between the properties of the voids and their effects on stiffness of ceramic matrix composites are of ultimate interest, but the exploratory study presented here starts by first modeling the effects of voids on an isotropic material. Several cases with varying void parameters were modeled which resulted in a large amount of variability of the transverse stiffness and out-of-plane shear stiffness. An investigation into a physical explanation for the stiffness degradation led to the observation that the voids need to be treated as an entity that reduces load bearing capabilities in a space larger than what the void directly occupies through a corrected length fraction or area fraction. This provides explanation as to why void volume fraction is not the only important factor to consider when computing loss of stiffness.

  1. Development of Ceramic Matrix Composite Turbine Blisks for Rocket Engines

    NASA Technical Reports Server (NTRS)

    Effinger, Mike; Genge, Gary; Kiser, J. Douglas; Munafo, Paul M. (Technical Monitor)

    2000-01-01

    Ceramic matrix composite (CMC) integrally bladed turbine disks (blisks) are being considered for use in various advanced propulsion systems for space vehicles. The successful development of this technology can significantly impact National Aeronautics and Space Administration (NASA) space transportation missions, by enabling new efficient systems that can operate at higher temperatures, while reducing costs. Composite blisks comprised of carbon (C) fibers and a silicon carbide (SiC) ceramic matrix were designed, fabricated, characterized, and tested by a multidisciplinary team involving materials, design, structural analysis, turbomachinery, and nondestructive evaluation representatives from government, academia, and industry during a 4.5 year effort led by the NASA Marshall Space Flight Center (MSFC). The testing of several of these blisks, which were developed in the Simplex Turbopump CMC Blisk ]Program for use in rocket engine turbopumps, was recently completed. CMC blisks offer potential advantages in rocket engine turbopumps including increased safety resulting from increased operating temperature margins and greater pump reliability, and decreased costs resulting from improved turbopump performance. The progress that was achieved in that development effort is reviewed, and some of the technology that could be applied to other advanced space transportation propulsion systems is discussed.

  2. Orthorhombic Titanium Matrix Composite Subjected to Simulated Engine Mission Cycles

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P.

    1997-01-01

    Titanium matrix composites (TMC's) are commonly made up of a titanium alloy matrix reinforced by silicon carbide fibers that are oriented parallel to the loading axis. These composites can provide high strength at lower densities than monolithic titanium alloys and superalloys in selected gas turbine engine applications. The use of TMC rings with unidirectional SiC fibers as reinforcing rings within compressor rotors could significantly reduce the weight of these components. In service, these TMC reinforcing rings would be subjected to complex service mission loading cycles, including fatigue and dwell excursions. Orthorhombic titanium aluminide alloys are of particular interest for such TMC applications because their tensile and creep strengths are high in comparison to those of other titanium alloys. The objective of this investigation was to assess, in simulated mission tests at the NASA Lewis Research Center, the durability of a SiC (SCS-6)/Ti-22Al-23Nb (at.%) TMC for compressor ring applications, in cooperation with the Allison Engine Company.

  3. Metal-Matrix Composites Prepared by Paper-Manufacturing Technology

    NASA Astrophysics Data System (ADS)

    Wenzel, Claudia; Aneziris, Christos G.; Pranke, Katja

    2016-01-01

    In this work, metal-matrix composites were prepared via paper-manufacturing technology using metastable austenitic steel powder of type 16-7-3 (Cr-Mn-Ni in wt pct) and magnesia partially stabilized zirconia reinforcing particles. The influence of the process parameters on the paper web formation and the resulting properties of the MMCs were studied and solids retention of >90 wt pct was achieved. During filtration of the aqueous fiber-filler suspension, the steel particles were incorporated in the fiber network, and steel clusters were formed. Calendering had a positive influence on the porosity, bulk density, and tensile strength of the green paper sheets. Within this contribution, the debinding process for the metal-matrix paper sheets was in focus. A debinding rate of 0.5 K/min to 733 K (460 °C) with a dwell time of 90 minutes was sufficient to completely remove cellulose fibers. The sintered composites attained a tensile strength of up to 177 N/mm2 at a total porosity of 66 pct.

  4. Development of Ceramic Matrix Composite Turbine Blisks for Rocket Engines

    NASA Technical Reports Server (NTRS)

    Effinger, Mike; Genge, Gary; Kiser, J. Douglas; Munafo, Paul M. (Technical Monitor)

    2000-01-01

    Ceramic matrix composite (CMC) integrally bladed turbine disks (blisks) are being considered for use in various advanced propulsion systems for space vehicles. The successful development of this technology can significantly impact National Aeronautics and Space Administration (NASA) space transportation missions, by enabling new efficient systems that can operate at higher temperatures, while reducing costs. Composite blisks comprised of carbon (C) fibers and a silicon carbide (SiC) ceramic matrix were designed, fabricated, characterized, and tested by a multidisciplinary team involving materials, design, structural analysis, turbomachinery, and nondestructive evaluation representatives from government, academia, and industry during a 4.5 year effort led by the NASA Marshall Space Flight Center (MSFC). The testing of several of these blisks, which were developed in the Simplex Turbopump CMC Blisk ]Program for use in rocket engine turbopumps, was recently completed. CMC blisks offer potential advantages in rocket engine turbopumps including increased safety resulting from increased operating temperature margins and greater pump reliability, and decreased costs resulting from improved turbopump performance. The progress that was achieved in that development effort is reviewed, and some of the technology that could be applied to other advanced space transportation propulsion systems is discussed.

  5. Combined NDE/finite element technique to study the effects of matrix porosity on the behavior of ceramic matrix composites

    NASA Astrophysics Data System (ADS)

    Abdul-Aziz, Ali; Ghosn, Louis J.; Baaklini, George Y.; Bhatt, Ramakrishna

    2003-08-01

    Ceramic matrix composites are being considered as candidate materials for high temperature aircraft engine components to replace the current high density metal alloys. The current Ceramic Matrix Composites (CMC) are engineered material composed of coated 2D woven high strength fiber tows and melt infiltrated ceramic matrix. Matrix voids are common anomalies generated during the melt infiltration process. The effects of these matrix porosities are usually associated with a reduction in the initial overall composite stiffness, and an increase in the thermal conductivity of the component. Furthermore, the role of the matrix as well as the coating is to protect the fibers from the harsh engine environment. Hence, the current design approach is to limit the design stress level of CMC components to be always below the first matrix cracking stress. In this study, the effects of matrix porosity on the initial component stiffness and the onset of matrix cracking are analyzed using a combined NDE/Finite-Element Technique. The Computed Tomography (CT) is utilized as the NDE technique to characterize the initial matrix porosity's locations and sizes in various CMC test specimens. The Finite Element is utilized to calculate the localized stress field around these pores based on the geometric modeling of the specimen's CT results, using image analysis and geometric modeling software. The same specimen was also scanned after tensile testing to a maximum nominal stress of 150 MPa to depict any growth of the previous observe voids. The post test CT scans depicted an enlargement and some coalescence of the existing voids.

  6. Structural and functional polymer-matrix composites for electromagnetic applications

    NASA Astrophysics Data System (ADS)

    Wu, Junhua

    This dissertation addresses the science and technology of functional and structural polymer-matrix composite materials for electromagnetic applications, which include electromagnetic interference (EMI) shielding and low observability (Stealth). The structural composites are continuous carbon fiber epoxy-matrix composites, which are widely used for airframes. The functional composites are composites with discontinuous fillers and in both bulk and coating forms. Through composite structure variation, attractive electromagnetic properties have been achieved. With no degradation of the tensile strength or modulus, the shielding effectiveness of the structural composites has been improved by enhancing multiple reflections through light activation of the carbon fiber. The multiple reflections loss of the electromagnetic wave increases from 1.1 to 10.2 dB at 1.0 GHz due to the activation. Such a large effect of multiple reflections has not been previously reported in any material. The observability of these composites has been lowered by decreasing the electrical conductivity (and hence decreasing the reflection loss) through carbon fiber coating. The incorporation of mumetal, a magnetic alloy particulate filler (28-40 mum size), in a latex paint has been found to be effective for enhancing the shielding only if the electrical resistivity of the resulting composite coating is below 10 O.cm, as rendered by a conductive particulate filler, such as nickel flake (14-20 mum size). This effectiveness (39 dB at 1.0 GHz) is attributed to the absorption of the electromagnetic wave by the mumetal and the nickel flake, with the high conductivity rendered by the presence of the nickel flake resulting in a relatively high reflection loss of 15.5 dB. Without the nickel flake, the mumetal gives only 3 dB of shielding and 1.5 dB of reflection loss at 1.0 GHz. Nickel powder (0.3-0.5 mum size) has been found to be an effective filler for improving the shielding of polyethersulfone (PES

  7. Hygrothermal modeling and testing of polymers and polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Xu, Weiqun

    2000-10-01

    The dissertation, consisting of four papers, presents the results of the research investigation on environmental effects on polymers and polymer matrix composites. Hygrothermal models were developed that would allow characterization of non-Fickian diffusion coefficients from moisture weight gain data. Hygrothermal testing was also conducted to provide the necessary data for characterizing of model coefficients and model verification. In part 1, a methodology is proposed that would allow characterization of non-Fickian diffusion coefficients from moisture weight gain data for a polymer adhesive below its Tg. Subsequently, these diffusion coefficients are used for predicting moisture concentration profiles through the thickness of a polymer. In part 2, a modeling methodology based on irreversible thermodynamics applied within the framework of composite macro-mechanics is presented, that would allow characterization of non-Fickian diffusion coefficients from moisture weight gain data for laminated composites with distributed uniaxial damage. Comparisons with test data for a 5-harness satin textile composite with uniaxial micro-cracks are provided for model verifications. In part 3, the same modeling methodology based on irreversible thermodynamics is extended to the case of a bi-axially damaged laminate. The model allows characterization of nonFickian diffusion coefficients as well as moisture saturation level from moisture weight gain data for laminates with pre-existing damage. Comparisons with test data for a bi-axially damaged Graphite/Epoxy woven composite are provided for model verifications. Finally, in part 4, hygrothermal tests conducted on AS4/PR500 5HS textile composite laminates are summarized. The objectives of the hygrothermal tests are to determine the diffusivity and maximum moisture content of the laminate.

  8. Centrifugal casting of metal matrix composites. Ph.D. Thesis

    SciTech Connect

    Berger, R.E.

    1994-01-01

    Metal matrix composites (MMCs) have excellent properties and low material costs, but high manufacturing costs. The primary difficulty in manufacturing MMCs is in forming a tight matrix/reinforcement bond. This dissertation investigates improving the matrix/reinforcement bond through the use of high centrifugal forces. High centrifugal forces promote fiber infiltration (or particle submergence), remove gas voids, and resist particle pushing by the solidification front. Several aluminum matrix MMC samples are formed at up to 2,660 g`s. The project involves: (1) design and construction of a rotating crucible capable of a 690 C, 2,600 g-force environment; (2) a finite differences heat transfer model using an unique technique (spreadsheet iteration) which has application to engineering teaching and simple modeling problems; (3) a bubble buoyancy/surface adhesion analysis to predict maximum surface voids or bubble cling in cast materials; (4) a fluid surface tension effects analysis evaluating particle submergence into a melt, and melt infiltration into a porous media such as a fiber form; (5) creation of samples and direct visual measurement of void sizes in agreement with bubble buoyancy/surface adhesion theory; (6) performance of tests and direct evidence supporting the developed particle submergence/porous media infiltration theories; and (7) creation of samples and direct measurement of material strength under subjection to bending stress. The final conclusion is that use of high centrifugal forces in MMC manufacturing has potential, however it is only useful for large diameter fibers or particles (on the order of 200 micron) and relatively high g-forces (on the order of 2,500 g`s).

  9. Monitoring Damage Accumulation in Ceramic Matrix Composites Using Electrical Resistivity

    NASA Technical Reports Server (NTRS)

    Smith, Craig E.; Morscher, Gregory N.; Xia, Zhenhai H.

    2008-01-01

    The electric resistance of woven SiC fiber reinforced SiC matrix composites were measured under tensile loading conditions. The results show that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance. Such self-sensing capability provides the possibility of on-board/in-situ damage detection and accurate life prediction for high-temperature ceramic matrix composites. Woven silicon carbide fiber-reinforced silicon carbide (SiC/SiC) ceramic matrix composites (CMC) possess unique properties such as high thermal conductivity, excellent creep resistance, improved toughness, and good environmental stability (oxidation resistance), making them particularly suitable for hot structure applications. In specific, CMCs could be applied to hot section components of gas turbines [1], aerojet engines [2], thermal protection systems [3], and hot control surfaces [4]. The benefits of implementing these materials include reduced cooling air requirements, lower weight, simpler component design, longer service life, and higher thrust [5]. It has been identified in NASA High Speed Research (HSR) program that the SiC/SiC CMC has the most promise for high temperature, high oxidation applications [6]. One of the critical issues in the successful application of CMCs is on-board or insitu assessment of the damage state and an accurate prediction of the remaining service life of a particular component. This is of great concern, since most CMC components envisioned for aerospace applications will be exposed to harsh environments and play a key role in the vehicle s safety. On-line health monitoring can enable prediction of remaining life; thus resulting in improved safety and reliability of structural components. Monitoring can also allow for appropriate corrections to be made in real time, therefore leading to the prevention of catastrophic failures. Most conventional nondestructive

  10. Effect of Gamma Irradiation on Structural and Biological Properties of a PLGA-PEG-Hydroxyapatite Composite

    PubMed Central

    Shahabi, Sima; Najafi, Farhood; Majdabadi, Abbas; Hooshmand, Tabassom; Haghbin Nazarpak, Masoumeh; Karimi, Batool

    2014-01-01

    Gamma irradiation is able to affect various structural and biological properties of biomaterials In this study, a composite of Hap/PLGA-PEG and their ingredients were submitted to gamma irradiation doses of 25 and 50 KGy. Various properties such as molecular weight (GPC), thermal behavior (DSC), wettability (contact angle), cell viability (MTT assay), and alkaline phosphatase activity were studied for the composites and each of their ingredients. The results showed a decrease in molecular weight of copolymer with no change in the glass transition and melting temperatures after gamma irradiation. In general gamma irradiation can increase the activation energy ΔH of the composites and their ingredients. While gamma irradiation had no effect on the wettability of copolymer samples, there was a significant decrease in contact angle of hydroxyapatite and composites with increase in gamma irradiation dose. This study showed an increase in biocompatibility of hydroxyapatite with gamma irradiation with no significant effect on cell viability in copolymer and composite samples. In spite of the fact that no change occurred in alkaline phosphatase activity of composite samples, results indicated a decrease in alkaline phosphatase activity in irradiated hydroxyapatites. These effects on the properties of PLGA-PEG-hydroxyapatite can enhance the composite application as a biomaterial. PMID:25574485

  11. Synergistic Effects of Temperature and Oxidation on Matrix Cracking in Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2017-06-01

    In this paper, the synergistic effects of temperatrue and oxidation on matrix cracking in fiber-reinforced ceramic-matrix composites (CMCs) has been investigated using energy balance approach. The shear-lag model cooperated with damage models, i.e., the interface oxidation model, interface debonding model, fiber strength degradation model and fiber failure model, has been adopted to analyze microstress field in the composite. The relationships between matrix cracking stress, interface debonding and slipping, fiber fracture, oxidation temperatures and time have been established. The effects of fiber volume fraction, interface properties, fiber strength and oxidation temperatures on the evolution of matrix cracking stress versus oxidation time have been analyzed. The matrix cracking stresses of C/SiC composite with strong and weak interface bonding after unstressed oxidation at an elevated temperature of 700 °C in air condition have been predicted for different oxidation time.

  12. Synergistic Effects of Temperature and Oxidation on Matrix Cracking in Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2016-10-01

    In this paper, the synergistic effects of temperatrue and oxidation on matrix cracking in fiber-reinforced ceramic-matrix composites (CMCs) has been investigated using energy balance approach. The shear-lag model cooperated with damage models, i.e., the interface oxidation model, interface debonding model, fiber strength degradation model and fiber failure model, has been adopted to analyze microstress field in the composite. The relationships between matrix cracking stress, interface debonding and slipping, fiber fracture, oxidation temperatures and time have been established. The effects of fiber volume fraction, interface properties, fiber strength and oxidation temperatures on the evolution of matrix cracking stress versus oxidation time have been analyzed. The matrix cracking stresses of C/SiC composite with strong and weak interface bonding after unstressed oxidation at an elevated temperature of 700 °C in air condition have been predicted for different oxidation time.

  13. Strong, damage tolerant oxide-fiber/oxide matrix composites

    NASA Astrophysics Data System (ADS)

    Bao, Yahua

    Electrophoretic deposition (EPD) is an easy and cost effective method to fabricate fiber-reinforced green composites. Non-conductive Nextel(TM) 720 fibers were successfully coated with a transient, conductive polypyrrole submicron surface layer for use directly as an electrode in EPD processing. However, electric-field shielding limits particle infiltration into the conductive fiber bundles and they mostly deposit on the outer surface of the fiber bundle. When the bundle is large, central cavities exist after deposition. The EPD cell was modified for electrophoretic infiltration deposition (EPID). Non conductive fibers were laid on an electrode and charged particles in an ethanol suspension are driven there through by an electric field, infiltrate and deposit on the electrode to then build up into the fiber preform and fill the voids therein. Dense, uniform, green fiber composites were successfully fabricated via constant current EPID. The EPID process is modeled as capillary electrophoretic infiltration. The process consists of two steps: particle electrophoresis outside the capillaries and electrophoretic infiltration inside the capillaries. Due to the zero net flow of the ethanol across the capillary cross-section, there is no electro-osmotic flow contribution to the deposition rate. Hamaker's law was extended to the EPID process, i.e., the deposition yield is proportional to the electric field inside the capillaries. The total deposition yield is controlled by the slow step of the process, i.e., the rate of electrophoresis in the open suspension outside the capillaries. AlPO4 was proposed as a weak layer between oxide fibers and oxide matrix in fiber-reinforced ceramic matrix composites (CMC's). AlPO 4 nano particles were synthesized by chemical co-precipitation of Al 3+ and HPO42- with urea at 95°C. The solution pH basic region and amorphous AlPO4 precipitated of narrow size distribution with a mean particle size 50nm. Nextel 720 fibers were pretreated with

  14. Effect of preliminary irradiation on the bond strength between a veneering composite and alloy.

    PubMed

    Matsumoto, Yoshifumi; Furuchi, Mika; Oshima, Akiko; Tanoue, Naomi; Koizumi, Hiroyasu; Matsumura, Hideo

    2010-01-01

    The shear bond strength of a veneering composite (Solidex) and silver-palladium-copper-gold alloy (Castwell M.C.12) was evaluated for different duration times and irradiance for preliminary photo-polymerization. A veneering composite was applied onto a cast disk. Preliminary photo irradiation was performed using different duration times or irradiance. After final polymerization, the bond strength and the spectral distribution of each curing unit were determined. Shear bond strength was significantly higher for 90 s (12.4 MPa), than that for 0 s (8.3 MPa). With regard to the effect of irradiance, that from Solidilite (11.4 MPa) was significantly higher than that from Sublite S at 3 cm (8.7 MPa). The irradiance of Hyper LII and Sublite S at 3 cm was higher than Sublite S at 15 cm or Solidilite unit. Long time irradiation and low intensity is effective for preliminary irradiation in order to enhance the bond strength.

  15. 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.

  16. High-strain-rate behavior of metal matrix composites

    NASA Astrophysics Data System (ADS)

    Guden, Mustafa

    Dynamic loading response is an important design parameter, which is critical in severe applications where impact loading occurs, but which has been little investigated to date for MMCs. Those MMCs which have been tested at high strain-rates so far have been diverse in terms of matrix alloy and reinforcement type, size and shape, making comparisons difficult. In this study, four different MMCs, SiC particulate and whisker reinforced, Alsb2Osb3 short and long fiber reinforced, representing currently available MMC groups, have been compression tested at quasi-static and high strain rates ({˜}10sp3\\ ssp{-1}). It has been shown that the strain rate sensitivity of the composite is very similar to that of the corresponding unreinforced alloy for the following composites: SiCsb{p}/2024 Al MMC, SiCsb{w}/2124-T6 Al MMC, Alsb2Osb3 (Saffil) short fiber reinforced Al-1.2wt%Cu in a direction normal to the Planar Random Fiber Plane, and Alsb2Osb3 (FP) long fiber reinforced Al-3wt%Li MMC tested in the transverse direction. In Alsb2Osb3 Saffil short fiber reinforced Al-1.2wt%Cu MMC tested in a direction parallel to the Planar Random Fiber Plane and FP-Alsb2Osb3 long fiber MMC in the longitudinal direction, the strain rate sensitivities of the flow stress or maximum stress were found to be higher than those of the monolithic alloy. The increased strain rate sensitivity in Saffil short fiber reinforced MMC was found to be a combined effect of matrix rate sensitivity and load carried by fiber until about 5% strains. The increased rate sensitivity of FP reinforced MMC in the longitudinal direction was due to the increased fiber buckling stress which scaled with matrix shear stress. Microscopic observations have shown that, in SiC whisker reinforced MMC, the failure was controlled by thermal softening and strain localization at high strain rates. In Saffil reinforced MMC, the reduced fiber fragment size at high strain rates and increased extent of matrix voiding were the dominant

  17. Probabilistic Evaluation of Advanced Ceramic Matrix Composite Structures

    NASA Technical Reports Server (NTRS)

    Abumeri, Galib H.; Chamis, Christos C.

    2003-01-01

    The objective of this report is to summarize the deterministic and probabilistic structural evaluation results of two structures made with advanced ceramic composites (CMC): internally pressurized tube and uniformly loaded flange. The deterministic structural evaluation includes stress, displacement, and buckling analyses. It is carried out using the finite element code MHOST, developed for the 3-D inelastic analysis of structures that are made with advanced materials. The probabilistic evaluation is performed using the integrated probabilistic assessment of composite structures computer code IPACS. The affects of uncertainties in primitive variables related to the material, fabrication process, and loadings on the material property and structural response behavior are quantified. The primitive variables considered are: thermo-mechanical properties of fiber and matrix, fiber and void volume ratios, use temperature, and pressure. The probabilistic structural analysis and probabilistic strength results are used by IPACS to perform reliability and risk evaluation of the two structures. The results will show that the sensitivity information obtained for the two composite structures from the computational simulation can be used to alter the design process to meet desired service requirements. In addition to detailed probabilistic analysis of the two structures, the following were performed specifically on the CMC tube: (1) predicted the failure load and the buckling load, (2) performed coupled non-deterministic multi-disciplinary structural analysis, and (3) demonstrated that probabilistic sensitivities can be used to select a reduced set of design variables for optimization.

  18. Economical Fabrication of Thick-Section Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Babcock, Jason; Ramachandran, Gautham; Williams, Brian; Benander, Robert

    2010-01-01

    A method was developed for producing thick-section [>2 in. (approx.5 cm)], continuous fiber-reinforced ceramic matrix composites (CMCs). Ultramet-modified fiber interface coating and melt infiltration processing, developed previously for thin-section components, were used for the fabrication of CMCs that were an order of magnitude greater in thickness [up to 2.5 in. (approx.6.4 cm)]. Melt processing first involves infiltration of a fiber preform with the desired interface coating, and then with carbon to partially densify the preform. A molten refractory metal is then infiltrated and reacts with the excess carbon to form the carbide matrix without damaging the fiber reinforcement. Infiltration occurs from the inside out as the molten metal fills virtually all the available void space. Densification to <5 vol% porosity is a one-step process requiring no intermediate machining steps. The melt infiltration method requires no external pressure. This prevents over-infiltration of the outer surface plies, which can lead to excessive residual porosity in the center of the part. However, processing of thick-section components required modification of the conventional process conditions, and the means by which the large amount of molten metal is introduced into the fiber preform. Modification of the low-temperature, ultraviolet-enhanced chemical vapor deposition process used to apply interface coatings to the fiber preform was also required to accommodate the high preform thickness. The thick-section CMC processing developed in this work proved to be invaluable for component development, fabrication, and testing in two complementary efforts. In a project for the Army, involving SiC/SiC blisk development, nominally 0.8 in. thick x 8 in. diameter (approx. 2 cm thick x 20 cm diameter) components were successfully infiltrated. Blisk hubs were machined using diamond-embedded cutting tools and successfully spin-tested. Good ply uniformity and extremely low residual porosity (<2

  19. Advanced composite structures. [metal matrix composites - structural design criteria for spacecraft construction materials

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.

  20. Irradiation of skin with visible light induces reactive oxygen species and matrix-degrading enzymes.

    PubMed

    Liebel, Frank; Kaur, Simarna; Ruvolo, Eduardo; Kollias, Nikiforos; Southall, Michael D

    2012-07-01

    Daily skin exposure to solar radiation causes cells to produce reactive oxygen species (ROS), which are a primary factor in skin damage. Although the contribution of the UV component to skin damage has been established, few studies have examined the effects of non-UV solar radiation on skin physiology. Solar radiation comprises <10% of UV, and thus the purpose of this study was to examine the physiological response of skin to visible light (400-700 nm). Irradiation of human skin equivalents with visible light induced production of ROS, proinflammatory cytokines, and matrix metalloproteinase (MMP)-1 expression. Commercially available sunscreens were found to have minimal effects on reducing visible light-induced ROS, suggesting that UVA/UVB sunscreens do not protect the skin from visible light-induced responses. Using clinical models to assess the generation of free radicals from oxidative stress, higher levels of free radical activity were found after visible light exposure. Pretreatment with a photostable UVA/UVB sunscreen containing an antioxidant combination significantly reduced the production of ROS, cytokines, and MMP expression in vitro, and decreased oxidative stress in human subjects after visible light irradiation. Taken together, these findings suggest that other portions of the solar spectrum aside from UV, particularly visible light, may also contribute to signs of premature photoaging in skin.