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Sample records for fabric reinforced composites

  1. Elastic properties of woven fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Ramnath, V.

    1985-01-01

    An analytical model for the realistic representation of a woven fabric reinforced composite is presented in this paper. The approach uses a variable cross-section geometric model in order to achieve geometric compatibility at the yarn cross-over regions. Admissible displacement and stress fields are used to determine bounds on the fabric elastic properties. The approach adopted enables the determination of the complete three-dimensional woven fabric composite properties. The in-plane fabric properties obtained through this approach have been compared with results obtained from other approaches existing in the literature. Also, comparisons made with available experimental data indicate good agreement.

  2. Fabrication of tungsten wire reinforced nickel-base alloy composites

    NASA Technical Reports Server (NTRS)

    Brentnall, W. D.; Toth, I. J.

    1974-01-01

    Fabrication methods for tungsten fiber reinforced nickel-base superalloy composites were investigated. Three matrix alloys in pre-alloyed powder or rolled sheet form were evaluated in terms of fabricability into composite monotape and multi-ply forms. The utility of monotapes for fabricating more complex shapes was demonstrated. Preliminary 1093C (2000F) stress rupture tests indicated that efficient utilization of fiber strength was achieved in composites fabricated by diffusion bonding processes. The fabrication of thermal fatigue specimens is also described.

  3. Finite element analysis of the stiffness of fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Foye, R. L.

    1992-01-01

    The objective of this work is the prediction of all three dimensional elastic moduli of textile fabric reinforced composites. The analysis is general enough for use with complex reinforcing geometries and capable of subsequent improvements. It places no restrictions on fabric microgeometry except that the unit cell be determinate and rectangular. The unit cell is divided into rectangular subcells in which the reinforcing geometries are easier to define and analyze. The analysis, based on inhomogeneous finite elements, is applied to a variety of weave, braid, and knit reinforced composites. Some of these predictions are correlated to test data.

  4. Processes for fabricating composite reinforced material

    DOEpatents

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2015-11-24

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  5. Fabricating fiber-reinforced composite posts.

    PubMed

    Manhart, Jürgen

    2011-03-01

    Endodontic posts do not increase the strength of the remaining tooth structure in endodontically treated teeth. On the contrary, depending on the post design employed (tapered versus parallel-sided), the root can be weakened relative to the amount of tooth removed during preparation. In many cases, if there has been a high degree of damage to the clinical crown, conservative preparation for an anatomic tapered (biomimetic) post with the incorporation of a ferrule on solid tooth structure is necessary to protect the reaming root structure as well as for the long-term retention of the composite resin core and the definitive restoration. Adhesively luted endodontic posts reinforced with glass or quartz fiber lead to better homogeneous tension distribution when loaded than rigid metal or zirconium oxide ceramic posts. Fiber-reinforced posts also possess advantageous optical properties over metal or metal oxide post systems. The clinician should realize that there are admittedly substantial differences in the mechanical loading capacity of the different fiber-reinforced endodontic posts and should be aware of such differences in order to research and select a suitable post system for use.

  6. Analysis of woven fabrics for reinforced composite materials

    NASA Technical Reports Server (NTRS)

    Dow, Norris F.; Ramnath, V.; Rosen, B. Walter

    1987-01-01

    The use of woven fabrics as reinforcements for composites is considered. Methods of analysis of properties are reviewed and extended, with particular attention paid to three-dimensional constructions having through-the-thickness reinforcements. Methodology developed is used parametrically to evaluate the performance potential of a wide variety of reinforcement constructions including hybrids. Comparisons are made of predicted and measured properties of representative composites having biaxial and triaxial woven, and laminated tape lay-up reinforcements. Overall results are incorporated in advanced weave designs.

  7. Composition and method for making polyimide resin-reinforced fabric

    NASA Technical Reports Server (NTRS)

    Serafini, T. T.; Delvigs, P. (Inventor)

    1981-01-01

    A composition for making polyimide resin reinforced fibers or fabric is discussed. The composition includes a polyfunctional ester, a polyfunctional amine, and an end capping agent. The composition is impregnated into fibers or fabric and heated to form prepreg material. The tack retention characteristics of this prepreg material are improved by incorporating into the composition a liquid olefinic material compatible with the other ingredients of the composition. The prepreg material is heated at a higher temperature to effect formation of the polyimide resin and the monomeric additive is incorporated in the polyimide polymer structure.

  8. Fabrication Routes for Continuous Fiber-Reinforced Ceramic Composites (CFCC)

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.; Bansal, Narottam P.

    1998-01-01

    The primary approaches used for fabrication of continuous fiber-reinforced ceramic composite (CFCC) components have been reviewed. The CFCC fabrication issues related to fiber, interface, and matrix have been analyzed. The capabilities, advantages and limitations of the five matrix-infiltration routes have been compared and discussed. Today, the best fabrication route for the CFCC end-user is not clear and compromises need to be made depending on the details of the CFCC application. However, with time, this problem should be reduced as research continues to develop advanced CFCC constituents and fabrication routes.

  9. Fabrication Routes for Continuous Fiber-Reinforced Ceramic Composites (CFCC)

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.; Bansal, Narottam P.

    1998-01-01

    The primary approaches used for fabrication of continuous fiber-reinforced ceramic composite (CFCC) components have been reviewed. The CFCC fabrication issues related to fiber, interface, and matrix have been analyzed. The capabilities. advantages and limitations of the five matrix-infiltration routes have been compared and discussed. Today. the best fabrication route for the CFCC end-user is not clear and compromises need to be made depending on the details of the CFCC application. However, with time, this problem should be reduced as research continues to develop advanced CFCC constituents and fabrication routes.

  10. 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.

  11. Determining micro- and macro- geometry of fabric and fabric reinforced composites

    NASA Astrophysics Data System (ADS)

    Huang, Lejian

    Textile composites are made from textile fabric and resin. Depending on the weaving pattern, composite reinforcements can be characterized into two groups: uniform fabric and near-net shape fabric. Uniform fabric can be treated as an assembly of its smallest repeating pattern also called a unit cell; the latter is a single component with complex structure. Due to advantages of cost savings and inherent toughness, near-net shape fabric has gained great success in composite industries, for application such as turbine blades. Mechanical properties of textile composites are mainly determined by the geometry of the composite reinforcements. The study of a composite needs a computational tool to link fabric micro- and macro-geometry with the textile weaving process and composite manufacturing process. A textile fabric consists of a number of yarns or tows, and each yarn is a bundle of fibers. In this research, a fiber-level approach known as the digital element approach (DEA) is adopted to model the micro- and macro-geometry of fabric and fabric reinforced composites. This approach determines fabric geometry based on textile weaving mechanics. A solver with a dynamic explicit algorithm is employed in the DEA. In modeling a uniform fabric, the topology of the fabric unit cell is first established based on the weaving pattern, followed by yarn discretization. An explicit algorithm with a periodic boundary condition is then employed during the simulation. After its detailed geometry is obtained, the unit cell is then assembled to yield a fabric micro-geometry. Fabric micro-geometry can be expressed at both fiber- and yarn-levels. In modeling a near-net shape fabric component, all theories used in simulating the uniform fabric are kept except the periodic boundary condition. Since simulating the entire component at the fiber-level requires a large amount of time and memory, parallel program is used during the simulation. In modeling a net-shape composite, a dynamic molding

  12. Apparatus and process for freeform fabrication of composite reinforcement preforms

    NASA Technical Reports Server (NTRS)

    Yang, Junsheng (Inventor); Wu, Liangwei (Inventor); Liu, Junhai (Inventor); Jang, Bor Z. (Inventor)

    2001-01-01

    A solid freeform fabrication process and apparatus for making a three-dimensional reinforcement shape. The process comprises the steps of (1) operating a multiple-channel material deposition device for dispensing a liquid adhesive composition and selected reinforcement materials at predetermined proportions onto a work surface; (2) during the material deposition process, moving the deposition device and the work surface relative to each other in an X-Y plane defined by first and second directions and in a Z direction orthogonal to the X-Y plane so that the materials are deposited to form a first layer of the shape; (3) repeating these steps to deposit multiple layers for forming a three-dimensional preform shape; and (4) periodically hardening the adhesive to rigidize individual layers of the preform. These steps are preferably executed under the control of a computer system by taking additional steps of (5) creating a geometry of the shape on the computer with the geometry including a plurality of segments defining the preform shape and each segment being preferably coded with a reinforcement composition defining a specific proportion of different reinforcement materials; (6) generating programmed signals corresponding to each of the segments in a predetermined sequence; and (7) moving the deposition device and the work surface relative to each other in response to these programmed signals. Preferably, the system is also operated to generate a support structure for any un-supported feature of the 3-D preform shape.

  13. Formability Analysis of Bamboo Fabric Reinforced Poly (Lactic) Acid Composites.

    PubMed

    M R, Nurul Fazita; Jayaraman, Krishnan; Bhattacharyya, Debes

    2016-07-02

    Poly (lactic) acid (PLA) composites have made their way into various applications that may require thermoforming to produce 3D shapes. Wrinkles are common in many forming processes and identification of the forming parameters to prevent them in the useful part of the mechanical component is a key consideration. Better prediction of such defects helps to significantly reduce the time required for a tooling design process. The purpose of the experiment discussed here is to investigate the effects of different test parameters on the occurrence of deformations during sheet forming of double curvature shapes with bamboo fabric reinforced-PLA composites. The results demonstrated that the domes formed using hot tooling conditions were better in quality than those formed using cold tooling conditions. Wrinkles were more profound in the warp direction of the composite domes compared to the weft direction. Grid Strain Analysis (GSA) identifies the regions of severe deformation and provides useful information regarding the optimisation of processing parameters.

  14. Formability Analysis of Bamboo Fabric Reinforced Poly (Lactic) Acid Composites

    PubMed Central

    M. R., Nurul Fazita; Jayaraman, Krishnan; Bhattacharyya, Debes

    2016-01-01

    Poly (lactic) acid (PLA) composites have made their way into various applications that may require thermoforming to produce 3D shapes. Wrinkles are common in many forming processes and identification of the forming parameters to prevent them in the useful part of the mechanical component is a key consideration. Better prediction of such defects helps to significantly reduce the time required for a tooling design process. The purpose of the experiment discussed here is to investigate the effects of different test parameters on the occurrence of deformations during sheet forming of double curvature shapes with bamboo fabric reinforced-PLA composites. The results demonstrated that the domes formed using hot tooling conditions were better in quality than those formed using cold tooling conditions. Wrinkles were more profound in the warp direction of the composite domes compared to the weft direction. Grid Strain Analysis (GSA) identifies the regions of severe deformation and provides useful information regarding the optimisation of processing parameters. PMID:28773662

  15. Continuous unidirectional fiber reinforced composites: Fabrication and testing

    NASA Technical Reports Server (NTRS)

    Weber, M. D.; Spiegel, F. X.; West, Harvey A.

    1994-01-01

    The study of the anisotropic mechanical properties of an inexpensively fabricated composite with continuous unidirectional fibers and a clear matrix was investigated. A method has been developed to fabricate these composites with aluminum fibers and a polymer matrix. These composites clearly demonstrate the properties of unidirectional composites and cost less than five dollars each to fabricate.

  16. Improved inhomogeneous finite elements for fabric reinforced composite mechanics analysis

    NASA Technical Reports Server (NTRS)

    Foye, R. L.

    1992-01-01

    There is a need to do routine stress/failure analysis of fabric reinforced composite microstructures to provide additional confidence in critical applications and guide materials development. Conventional methods of 3-D stress analysis are time consuming to set up, run and interpret. A need exists for simpler methods of modeling these structures and analyzing the models. The principal difficulty is the discrete element mesh generation problem. Inhomogeneous finite elements are worth investigating for application to these problems because they eliminate the mesh generation problem. However, there are penalties associated with these elements. Their convergence rates can be slow compared to homogeneous elements. Also, there is no accepted method for obtaining detailed stresses in the constituent materials of each element. This paper shows that the convergence rate can be significantly improved by a simple device which substitutes homogeneous elements for the inhomogeneous ones. The device is shown to work well in simple one and two dimensional problems. However, demonstration of the application to more complex two and three dimensional problems remains to be done. Work is also progressing toward more realistic fabric microstructural geometries.

  17. Fabrication of fiber-reinforced composites by chemical vapor infiltration

    SciTech Connect

    Besmann, T.M.; McLaughlin, J.C.; Probst, K.J.; Anderson, T.J.; Starr, T.L.

    1997-12-01

    Silicon carbide-based heat exchanger tubes are of interest to energy production and conversion systems due to their excellent high temperature properties. Fiber-reinforced SiC is of particular importance for these applications since it is substantially tougher than monolithic SiC, and therefore more damage and thermal shock tolerant. This paper reviews a program to develop a scaled-up system for the chemical vapor infiltration of tubular shapes of fiber-reinforced SiC. The efforts include producing a unique furnace design, extensive process and system modeling, and experimental efforts to demonstrate tube fabrication.

  18. Fabrication of fiber-reinforced composites by chemical vapor infiltration

    SciTech Connect

    Besmann, T.M.; Matlin, W.M.; Stinton, D.P.; Liaw, P.K.

    1996-06-01

    Processing equipment for the infiltration of fiber-reinforced composite tubes is being designed that incorporates improvements over the equipment used to infiltrate disks. A computer-controlled machine-man interface is being developed to allow for total control of all processing variables. Additionally, several improvements are being made to the furnace that will reduce the complexity and cost of the process. These improvements include the incorporation of free standing preforms, cast mandrels, and simpler graphite heating elements.

  19. Fabrication of fiber-reinforced composites by chemical vapor infiltration

    SciTech Connect

    Besmann, T.M.; Stinton, D.P.; Matlin, W.M.; Liaw, P.K.

    1996-08-01

    Processing equipment for the infiltration of fiber-reinforced composite tubes is being designed that incorporates improvements over the equipment used to infiltrate disks. A computer-controlled machine-man interface is being developed to allow for total control of all processing variables. Additionally, several improvements are being made to the furnace that will reduce the complexity and cost of the process. These improvements include the incorporation of free standing preforms, cast mandrels, and simpler graphite heating elements.

  20. Calculation of the relative uniformity coefficient on the green composites reinforced with cotton and hemp fabric

    NASA Astrophysics Data System (ADS)

    Baciu, Florin; Hadǎr, Anton; Sava, Mihaela; Marinel, Stǎnescu Marius; Bolcu, Dumitru

    2016-06-01

    In this paper it is studied the influence of discontinuities on elastic and mechanical properties of green composite materials (reinforced with fabric of cotton or hemp). In addition, it is studied the way variations of the volume f the reinforcement influences the elasticity modulus and the tensile strength for the studied composite materials. In order to appreciate the difference in properties between different areas of the composite material, and also the dimensions of the defective areas, we have introduced a relative uniformity coefficient with which the mechanical behavior of the studied composite is compared with a reference composite. To validate the theoretical results we have obtained we made some experiments, using green composites reinforced with fabric, with different imperfection introduced special by cutting the fabric.

  1. A Fully Contained Resin Infusion Process for Fiber-Reinforced Polymer Composite Fabrication and Repair

    DTIC Science & Technology

    2013-01-01

    Assisted Resin Transfer Molding ( VARTM ) process is applicable for fiber-reinforced polymer (FRP) composite fabrication and repair. However, VARTM in...scenario is a fully enclosed VARTM system that limits the need for laboratory or manufacturing equipment. The Bladder-Bag VARTM (BBVARTM) technique...composite fabrication, VARTM , composite repair, in-field repair 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER

  2. Tensile and Flexural Properties of Cement Composites Reinforced with Flax Nonwoven Fabrics.

    PubMed

    Claramunt, Josep; Ventura, Heura; Fernández-Carrasco, Lucía J; Ardanuy, Mònica

    2017-02-22

    The aim of this study is to develop a process to produce high-performance cement-based composites reinforced with flax nonwoven fabrics, analyzing the influence of the fabric structure-thickness and entanglement-on mechanical behavior under flexural and tensile loadings. For this purpose, composite with flax nonwoven fabrics with different thicknesses were first prepared and their cement infiltration was evaluated with backscattered electron (BSE) images. The nonwoven fabrics with the optimized thickness were then subjected to a water treatment to improve their stability to humid environments and the fiber-matrix adhesion. For a fixed thickness, the effect of the nonwoven entanglement on the mechanical behavior was evaluated under flexural and direct tension tests. The obtained results indicate that the flax nonwoven fabric reinforcement leads to cement composites with substantial enhancement of ductility.

  3. Tensile and Flexural Properties of Cement Composites Reinforced with Flax Nonwoven Fabrics

    PubMed Central

    Claramunt, Josep; Ventura, Heura; Fernández-Carrasco, Lucía J; Ardanuy, Mònica

    2017-01-01

    The aim of this study is to develop a process to produce high-performance cement-based composites reinforced with flax nonwoven fabrics, analyzing the influence of the fabric structure—thickness and entanglement—on mechanical behavior under flexural and tensile loadings. For this purpose, composite with flax nonwoven fabrics with different thicknesses were first prepared and their cement infiltration was evaluated with backscattered electron (BSE) images. The nonwoven fabrics with the optimized thickness were then subjected to a water treatment to improve their stability to humid environments and the fiber-matrix adhesion. For a fixed thickness, the effect of the nonwoven entanglement on the mechanical behavior was evaluated under flexural and direct tension tests. The obtained results indicate that the flax nonwoven fabric reinforcement leads to cement composites with substantial enhancement of ductility. PMID:28772573

  4. Fabrication and characterization of carbon nanotube reinforced magnesium matrix composites

    NASA Astrophysics Data System (ADS)

    Mindivan, Harun; Efe, Arife; Kosatepe, A. Hadi; Kayali, E. Sabri

    2014-11-01

    In the present investigation, Mg chips are recycled to produce Mg-6 wt.% Al reinforced with 0.5, 1, 2 and 4 wt.% nanosized CNTs by mechanical ball milling, cold pressing and subsequently hot extrusion process without sintering step. The microstructure, mechanical properties and corrosion behavior of Mg/Al without CNT (base alloy) and composites were evaluated. The distribution of CNTs was analyzed using a Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectroscopy (EDS) analyzer and a Wavelength Dispersive X-Ray Fluorescence spectrometer (WDXRF). Microstructural analysis revealed that the CNTs on the Mg chips were present throughout the extrusion direction and the uniform distribution of CNTs at the chip surface decreased with increase in the CNT content. The results of the mechanical and corrosion test showed that small addition of CNTs (0.5 wt.%) evidently improved the hardness and corrosion resistance of the composite by comparing with the base alloy, while increase in the CNT weight fraction in the initial mixture resulted in a significant decrease of hardness, compression strength, wear rate and corrosion resistance.

  5. Hemp reinforced composites: surface treatment, manufacturing method and fabric type effects

    SciTech Connect

    Cicala, G.; Cristaldi, G.; Recca, G.

    2010-06-02

    Hemp mats and weaved fabrics were used as received and after surface treatment as reinforcement for composites. Mercerization and amino silane surface treatments improved fibre/matrix adhesion and, as results, the mechanical properties of the composites were also improved. However, if surface treatment was too severe degradation of the mechanical properties of the single fibre was observed and this resulted in a reinforcing efficiency loss. Weaved fabrics obtained from twisted fibres in unidirectional and 0/90 deg. architecture were used. The use of weaved fabrics lead to high improvements of composite mechanical properties despite the absence of fibre's surface treatment. The specimens manufactured by LRTM (Light Resin Transfer Moulding) showed enhanced mechanical properties compared to specimens made by hand lay up. Mechanical models were also used to predict the mechanical properties of the composites.

  6. Hemp reinforced composites: surface treatment, manufacturing method and fabric type effects

    NASA Astrophysics Data System (ADS)

    Cicalạ, G.; Cristaldi, G.; Recca, G.

    2010-06-01

    Hemp mats and weaved fabrics were used as received and after surface treatment as reinforcement for composites. Mercerization and amino silane surface treatments improved fibre/matrix adhesion and, as results, the mechanical properties of the composites were also improved. However, if surface treatment was too severe degradation of the mechanical properties of the single fibre was observed and this resulted in a reinforcing efficiency loss. Weaved fabrics obtained from twisted fibres in unidirectional and 0/90° architecture were used. The use of weaved fabrics lead to high improvements of composite mechanical properties despite the absence of fibre's surface treatment. The specimens manufactured by LRTM (Light Resin Transfer Moulding) showed enhanced mechanical properties compared to specimens made by hand lay up. Mechanical models were also used to predict the mechanical properties of the composites.

  7. Influence of the Geometric Parameters on the Mechanical Behaviour of Fabric Reinforced Composite Laminates

    NASA Astrophysics Data System (ADS)

    Axinte, Andrei; Taranu, Nicolae; Bejan, Liliana

    2016-10-01

    A polymer fabric reinforced composite is a high performance material, which combines strength of the fibres with the flexibility and ductility of the matrix. For a better drapeability, the tows of fibres are interleaved, resulting the woven fabric, used as reinforcement. The complex geometric shape of the fabric is of paramount importance in establishing the deformability of the textile reinforced composite laminates. In this paper, an approach based on Classical Lamination Theory ( CLT), combined with Finite Element Methods ( FEM), using Failure Analysis and Internal Load Redistribution, is utilised, in order to compare the behaviour of the material under specific loads. The main goal is to analyse the deformability of certain types of textile reinforced composite laminates, using carbon fibre satin as reinforcement and epoxy resin as matrix. This is accomplished by studying the variation of the in-plane strains, given the fluctuation of several geometric parameters, namely the width of the reinforcing tow, the gap between two consecutive tows, the angle of laminae in a multi-layered configuration and the tows fibre volume fraction.

  8. Effect of fabricated density and bamboo species on physical-mechanical properties of bamboo fiber bundle reinforced composites

    Treesearch

    Jiulong Xie; Jinqiu Qi; Tingxing Hu; Cornelis F. De Hoop; Chung Yun Hse; Todd F. Shupe

    2016-01-01

    Bamboo stems were subjected to a mechanical treatment process for the extraction of bamboo fiber bundles. The fiber bundles were used as reinforcement for the fabrication of high-performance composites with phenolic resins as matrix. The influence of fabricated density and bamboo species on physical–mechanical properties of bamboo fiber bundle reinforced composites (...

  9. Fracture resistance of CAD/CAM-fabricated fiber-reinforced composite denture retainers.

    PubMed

    Nagata, Kohji; Wakabayashi, Noriyuki; Takahashi, Hidekazu; Vallittu, Pekka K; Lassila, Lippo V J

    2013-01-01

    The purpose of this study was to evaluate the fracture resistance of computer-aided design/computer-assisted manufacture (CAD/CAM)-fabricated fiber-reinforced composite (FRC) denture retainers. Distal extension dentures incorporating two telescopic retainers and two molar pontics, with or without fiberglass, were fabricated by CAD/CAM or by the conventional polymerization method. The dentures were subjected to a vertical load on the second molar pontic until fracture. Within each manufacturing method, embedment of the FRC increased the mean final fracture load, suggesting the reinforcing effect of fiberglass. The polymerized dentures with FRC showed greater mean final fracture load than the CAD/CAM dentures with FRC.

  10. Friction and Wear Behavior of Carbon Fabric-Reinforced Epoxy Composites

    NASA Astrophysics Data System (ADS)

    Şahin, Y.; De Baets, Patrick

    2017-02-01

    Besides intrinsic material properties, weight/energy savings and wear performance play an important role in the selection of materials for any engineering application. The tribological behavior of carbon fabric-reinforced epoxy composites produced by molding technique was investigated using a reciprocating pin-on-plate configuration. It was shown that the wear rate considerably decreased (by a factor of approx. 8) with the introduction of the reinforcing carbon fabric into the epoxy matrix. It was observed that the wear rate of the tested composites increased with an increase in normal load. Moreover, the coefficient of friction for epoxy/steel and composites/steel tribo-pairs was also determined and decreased with increasing load. By means of scanning electron microscopy of the wear tracks, different wear mechanisms such as matrix wear, matrix fatigue and cracking, matrix debris formation for neat epoxy together with fabric/fiber thinning, fabric breakage and fabric/matrix debonding for the reinforced epoxy could be distinguished.

  11. Mechanical Properties of Sisal/Coir Fiber Reinforced Hybrid Composites Fabricated by Cold Pressing Method

    NASA Astrophysics Data System (ADS)

    Akash; Sreenivasa Rao, K. V.; Venkatesha Gupta, N. S.; kumar, D. S. Arun

    2016-09-01

    Bio-composites have less density and are environmental friendly materials that require less energy during production and subsequent machining. This paper reports the mechanical and water absorption properties of sodium hydroxide (NaOH) treated sisal and coir fiber reinforced epoxy resin thermo set hybrid composites. The hybrid composites were prepared by traditional cold pressing method at room temperature with applied pressure of 410.4 kg/cm2 for 3 hours pressurization time. The mechanical properties were characterized according to ASTM standards. Hybrid composites with 40wt% of sisal and coir fiber were found to possess higher tensile strength of 48.2MPa and flexural strength of 76.68 MPa among the fabricated hybrid composite specimens. Absorption of water increases with increasing fiber volume. The experimental result also show that the sisal and coir fibers are promising reinforcement for use in low cost bio-composites which have high strength to weight ratio.

  12. The role of rapid solidification processing in the fabrication of fiber reinforced metal matrix composites

    NASA Technical Reports Server (NTRS)

    Locci, Ivan E.; Noebe, Ronald D.

    1989-01-01

    Advanced composite processing techniques for fiber reinforced metal matrix composites require the flexibility to meet several widespread objectives. The development of uniquely desired matrix microstructures and uniformly arrayed fiber spacing with sufficient bonding between fiber and matrix to transmit load between them without degradation to the fiber or matrix are the minimum requirements necessary of any fabrication process. For most applications these criteria can be met by fabricating composite monotapes which are then consolidated into composite panels or more complicated components such as fiber reinforced turbine blades. Regardless of the end component, composite monotapes are the building blocks from which near net shape composite structures can be formed. The most common methods for forming composite monotapes are the powder cloth, foil/fiber, plasma spray, and arc spray processes. These practices, however, employ rapid solidification techniques in processing of the composite matrix phase. Consequently, rapid solidification processes play a vital and yet generally overlooked role in composite fabrication. The future potential of rapid solidification processing is discussed.

  13. Analysis of woven and braided fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Naik, Rajiv A.

    1994-01-01

    A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell, was developed to predict overall, three dimensional, thermal and mechanical properties. This analytical technique was implemented in a user-friendly, personal computer-based, windows compatible code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain, 5-harness satin, and 8-harness satin weave composites along with 2-D braided and 2x2, 2-D triaxial braided composites. The calculated overall stiffnesses correlated well with available 3-D finite element results and test data for both the woven and the braided composites. Parametric studies were performed to investigate the effects of yarn size on the yarn crimp and the overall thermal and mechanical constants for plain weave composites. The effects of braid angle were investigated for the 2-D braided composites. Finally, the effects of fiber volume fraction on the yarn undulations and the thermal and mechanical properties of 2x2, 2-D triaxial braided composites were also investigated.

  14. Optimisation of Fabric Reinforced Polymer Composites Using a Variant of Genetic Algorithm

    NASA Astrophysics Data System (ADS)

    Axinte, Andrei; Taranu, Nicolae; Bejan, Liliana; Hudisteanu, Iuliana

    2017-03-01

    Fabric reinforced polymeric composites are high performance materials with a rather complex fabric geometry. Therefore, modelling this type of material is a cumbersome task, especially when an efficient use is targeted. One of the most important issue of its design process is the optimisation of the individual laminae and of the laminated structure as a whole. In order to do that, a parametric model of the material has been defined, emphasising the many geometric variables needed to be correlated in the complex process of optimisation. The input parameters involved in this work, include: widths or heights of the tows and the laminate stacking sequence, which are discrete variables, while the gaps between adjacent tows and the height of the neat matrix are continuous variables. This work is one of the first attempts of using a Genetic Algorithm (GA) to optimise the geometrical parameters of satin reinforced multi-layer composites. Given the mixed type of the input parameters involved, an original software called SOMGA (Satin Optimisation with a Modified Genetic Algorithm) has been conceived and utilised in this work. The main goal is to find the best possible solution to the problem of designing a composite material which is able to withstand to a given set of external, in-plane, loads. The optimisation process has been performed using a fitness function which can analyse and compare mechanical behaviour of different fabric reinforced composites, the results being correlated with the ultimate strains, which demonstrate the efficiency of the composite structure.

  15. Failure analysis of woven and braided fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Naik, Rajiv A.

    1994-01-01

    A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell was developed to predict overall, three dimensional, thermal and mechanical properties, damage initiation and progression, and strength. This analytical technique was implemented in a user-friendly, personal computer-based, menu-driven code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain weave and 2x2, 2-D triaxial braided composites. The calculated tension, compression, and shear strengths correlated well with available test data for both woven and braided composites. Parametric studies were performed on both woven and braided architectures to investigate the effects of parameters such as yarn size, yarn spacing, yarn crimp, braid angle, and overall fiber volume fraction on the strength properties of the textile composite.

  16. Failure analysis of woven and braided fabric reinforced composites

    SciTech Connect

    Naik, R.A.

    1994-09-01

    A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell was developed to predict overall, three dimensional, thermal and mechanical properties, damage initiation and progression, and strength. This analytical technique was implemented in a user-friendly, personal computer-based, menu-driven code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain weave and 2x2, 2-D triaxial braided composites. The calculated tension, compression, and shear strengths correlated well with available test data for both woven and braided composites. Parametric studies were performed on both woven and braided architectures to investigate the effects of parameters such as yarn size, yarn spacing, yarn crimp, braid angle, and overall fiber volume fraction on the strength properties of the textile composite.

  17. Multi-scale modeling of fiber and fabric reinforced cement based composites

    NASA Astrophysics Data System (ADS)

    Soranakom, Chote

    With an increased use of fiber reinforced concrete in structural applications, proper characterization techniques and development of design guides are needed. This dissertation presents a multi-scale modeling approach for fiber and fabric reinforced cement-based composites. A micromechanics-based model of the yarn pullout mechanism due to the failure of the interfacial zone is presented. The effect of mechanical anchorage of transverse yarns is simulated using nonlinear spring elements. The yarn pullout mechanism was used in a meso-scale modeling approach to simulate the yarn bridging force in the crack evolution process. The tensile stress-strain response of a tension specimen that experiences distributed cracking can be simulated using a generalized finite difference approach. The stiffness degradation, tension stiffening, crack spacing evolution, and crack width characteristics of cement composites can be derived using matrix, interface and fiber properties. The theoretical models developed for fabric reinforced cement composites were then extended to cover other types of fiber reinforced concrete such as shotcrete, glass fiber reinforced concrete (GFRC), steel fiber reinforced concrete (SFRC), ferrocement and other conventional composite systems. The uniaxial tensile stress-strain response was used to formulate a generalized parametric closed-form solution for predicting flexural behavior of various composites at the macro-structural level. The flexural behaviors of these composites were modeled in a unified manner by means of a moment-curvature relationship based on the uniaxial material models. A variety of theoretical models were developed to address the various mechanisms including: an analytical yarn pullout model; a nonlinear finite difference fabric pullout model; a nonlinear finite difference tension model; closed-form solutions for strain-softening materials; closed-form solutions for strain-softening/hardening materials; and closed-form solutions for

  18. Fabrication Of Carbon-Boron Reinforced Dry Polymer Matrix Composite Tape

    NASA Technical Reports Server (NTRS)

    Belvin, Harry L.; Cano, Roberto J.; Treasure, Monte; Shahood, Thomas W.

    1999-01-01

    Future generation aerospace vehicles will require specialized hybrid material forms for component structure fabrication. For this reason, high temperature composite prepregs in both dry and wet forms are being developed at NASA Langley Research Center (LaRC). In an attempt to improve compressive properties of carbon fiber reinforced composites, a hybrid carbon-boron tape was developed and used to fabricate composite laminates which were subsequently cut into flexural and compression specimens and tested. The hybrid material, given the designation HYCARB, was fabricated by modifying a previously developed process for the manufacture of dry polymer matrix composite (PMC) tape at LaRC. In this work, boron fibers were processed with IM7/LaRC(TradeMark)IAX poly(amide acid) solution-coated prepreg to form a dry hybrid tape for Automated Tow Placement (ATP). Boron fibers were encapsulated between two (2) layers of reduced volatile, low fiber areal weight poly(amide acid) solution-coated prepreg. The hybrid prepreg was then fully imidized and consolidated into a dry tape suitable for ATP. The fabrication of a hybrid boron material form for tow placement aids in the reduction of the overall manufacturing cost of boron reinforced composites, while realizing the improved compression strengths. Composite specimens were press-molded from the hybrid material and exhibited excellent mechanical properties.

  19. Micromechanics Fatigue Damage Analysis Modeling for Fabric Reinforced Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Xue, D.; Shi, Y.

    2013-01-01

    A micromechanics analysis modeling method was developed to analyze the damage progression and fatigue failure of fabric reinforced composite structures, especially for the brittle ceramic matrix material composites. A repeating unit cell concept of fabric reinforced composites was used to represent the global composite structure. The thermal and mechanical properties of the repeating unit cell were considered as the same as those of the global composite structure. The three-phase micromechanics, the shear-lag, and the continuum fracture mechanics models were integrated with a statistical model in the repeating unit cell to predict the progressive damages and fatigue life of the composite structures. The global structure failure was defined as the loss of loading capability of the repeating unit cell, which depends on the stiffness reduction due to material slice failures and nonlinear material properties in the repeating unit cell. The present methodology is demonstrated with the analysis results evaluated through the experimental test performed with carbon fiber reinforced silicon carbide matrix plain weave composite specimens.

  20. Effect of S-glass fabric on the mechanical characteristics of a hybrid carbon/aramid fabric reinforced epoxy composites

    NASA Astrophysics Data System (ADS)

    Alsaadi, Mohamad; Erkliğ, Ahmet; Alrawi, Humam

    2017-05-01

    The aim of this study is to investigate the hybridization effects of intraply carbon/aramid fabric layers with S-glass fabric layers on the tensile and flexural behavior of asymmetric and symmetric arrangements of hybrid composite laminates. The results revealed that the replacement of some carbon/aramid fiber layers with S-glass fiber layers in the composite laminate can provide enhancements in tensile strain, tensile modulus and flexural properties while the tensile strength results were slightly degraded. Three-point bending test results indicated a significant improvement in flexural properties when S-glass fibers employed in compressive side across the depth of composite laminates. The maximum increment in tensile modulus, flexural modulus and flexural strength of hybrid composite laminates were 19.7%, 50.0% and 42.3%, respectively compared to carbon/aramid fiber reinforced epoxy composite.

  1. Low Cost Fabrication of Silicon Carbide Based Ceramics and Fiber Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Singh, M.; Levine, S. R.

    1995-01-01

    A low cost processing technique called reaction forming for the fabrication of near-net and complex shaped components of silicon carbide based ceramics and composites is presented. This process consists of the production of a microporous carbon preform and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture with very good control of pore volume and pore size thereby yielding materials with tailorable microstructure and composition. Mechanical properties (elastic modulus, flexural strength, and fracture toughness) of reaction-formed silicon carbide ceramics are presented. This processing approach is suitable for various kinds of reinforcements such as whiskers, particulates, fibers (tows, weaves, and filaments), and 3-D architectures. This approach has also been used to fabricate continuous silicon carbide fiber reinforced ceramic composites (CFCC's) with silicon carbide based matrices. Strong and tough composites with tailorable matrix microstructure and composition have been obtained. Microstructure and thermomechanical properties of a silicon carbide (SCS-6) fiber reinforced reaction-formed silicon carbide matrix composites are discussed.

  2. Fabrication of fibre reinforced nickel aluminide matrix composites by reactive processing

    SciTech Connect

    Downing, M.; Horsfall, I.

    1994-12-31

    This paper describes the fabrication by reactive processing of short, and continuous, alumina fibre reinforced nickel aluminide matrix composites. The fibre is introduced into the aluminide system to increase toughness and high temperature strength. The short fibre reinforced nickel aluminide is formed by squeeze casting a porous preform containing nickel powder and SAFFIL fibre with an aluminium or aluminium alloy melt. The continuous fibre reinforced nickel aluminide is formed by squeeze casting a jig containing nickel coated ALMAX fibre. The short fibre reinforced composite (containing 10% and 20% volume fibre) reacted during infiltration with an aluminium melt to form a single phase intermetallic. Using an aluminium-copper melt the intermetallic formation was inhibited and a multi-phase composite was obtained. A preliminary study into reactive processing of this system by utilising a hot isostatic pressing (HIP) cycle is presented. HIP was required to prevent the formation of porosity due to an imbalance in the diffusive mobility of the various components. It was found that HIP was only effective on canned samples, the preferred encapsulation material being glass. The continuous fibre reinforced composite did not react to an intermetallic phase when infiltrated with an aluminum melt. Use of an aluminum-copper melt resulted in partial nickel-melt reaction producing various nickel-aluminum (-copper) phases. HIP was then used to form a two phase intermetallic matrix with no evidence of fibre damage.

  3. Mechanical properties of waste paper/jute fabric reinforced polyester resin matrix hybrid composites.

    PubMed

    Das, Sekhar

    2017-09-15

    Hybrid composites were prepared with jute fabric and un-shredded newspaper in polyester resin matrix. The experiment was designed 1:2 weights ratio jute and unshredded newspaper to have 42 (w/w)% fibre content hybrid composites and two different sequences jute/paper/jute and paper/jute/paper of waste newspaper and jute fabric arrangement. Reinforcing material is characterized by chemically, X-ray diffraction methods, Fourier transform infrared spectroscopy and tensile testing. The tensile, flexural and interlaminar shear strength and fracture surface morphology of composites were evaluated and compared. It was found that tensile and flexural properties of the hybrid composite are higher than that of pure paper-based composite but less than pure woven jute composite. The hybridization effect of woven jute fabric and layering pattern effect on mechanical properties of newspaper/woven jute fabric hybrid composites were studied. The test results of composites were analyzed by one-way ANOVA (α=0.05), it showed significant differences among the groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Analysis of knitted fabric reinforced flexible composites and applications in thermoforming

    NASA Astrophysics Data System (ADS)

    Bekisli, Burak

    In this study, large deformation behavior of knitted fabric reinforced composites is investigated. In order to fully utilize the unique stretchability of knitted fabric reinforcements, elastomeric materials are used as the matrix material, resulting in "flexible composites" capable of reaching several hundred percent stretch before failing. These non-traditional composites are ideal candidates for many engineering applications where large deformation is desired, including energy/impact absorption and novel forming processes. A multi-level nonlinear finite element (FE) procedure is developed to analyze the deformation behavior of plain weft-knitted fabrics and the composites derived from these materials. The hierarchy of the model is composed of a 3D unit cell analysis (micro/meso-scale) and a 2D global analysis (macro scale). Using results from different numerical experiments performed in the micro/meso scale, a mechanical behavior database of knit fabric geometries is constructed, both for the uniaxial and biaxial stretch cases. Through an optimization procedure, these results are used to determine the mechanical properties of nonlinear truss elements needed for modeling in the macro scale. A hexagonal honeycomb structure, which closely resembles the knit fabric architecture, is formed using these nonlinear trusses. This truss structure is then used to efficiently model a large number of loops generally found in a fabric. Results from uniaxial experimental measurements are presented for knitted fabrics to validate the FE model. Appropriate hyperelastic material models are determined for the elastomeric matrix, using a curve fit to experimental data. Examples of raw fabric and composite deformation simulations in the global scale are presented in this study. Two types of composites are studied experimentally and numerically: (1) knitted fabric embedded in an elastomeric medium, and (2) the sandwich type composites with elastomeric skins and fabric core. The strain

  5. Fabrication and evaluation of mechanical properties of alkaline treated sisal/hemp fiber reinforced hybrid composite

    NASA Astrophysics Data System (ADS)

    Venkatesha Gupta, N. S.; Akash; Sreenivasa Rao, K. V.; kumar, D. S. Arun

    2016-09-01

    Fiber reinforced polymer composite have acquired a dominant place in variety of applications because of higher specific strength and modulus, the plant based natural fiber are partially replacing currently used synthetic fiber as reinforcement for polymer composites. In this research work going to develop a new material which posses a strength to weight ratio that for exceed any of the present material. The hybrid composite sisal/hemp reinforced with epoxy matrix has been developed by compression moulding technique according to ASTM standards. Sodium hydroxide (NAOH) was used as alkali for treating the fibers. The amount of reinforcement was varied from 10% to 50% in steps of 10%. Prepared specimens were examined for mechanical properties such as tensile strength, flexural strength, and hardness. Hybrid composite with 40wt% sisal/hemp fiber were found to posses higher strength (tensile strength = 53.13Mpa and flexural strength = 82.07Mpa) among the fabricated hybrid composite specimens. Hardness value increases with increasing the fiber volume. Morphological examinations are carried out to analyze the interfacial characteristics, internal structure and fractured surfaces by using scanning electron microscope.

  6. Fabrication and Characterization of Squeezed Cast Aluminum Matrix Composites Containing Boride Reinforcements

    NASA Astrophysics Data System (ADS)

    Olaya-Luengas, L.; Estremera-Pérez, E.; Muñoz, L.; Suárez, O. M.

    2010-12-01

    Aluminum alloys containing 2 and 4 wt.% copper reinforced with aluminum dodecaborides were successfully fabricated by squeeze casting employing pressures up to 62 MPa. The distribution of reinforcements throughout the composites was quantified, whereas the effect of pressure on the composites density and hardness was determined. In addition, the reinforcement chemical stability was examined using high-temperature x-ray diffraction which permitted to confirm the formation of AlB2 phase a result of AlB12 decomposition. The pressure effect on the squeezed composites was investigated by optical microscopy, Vickers microhardness testing, superficial Rockwell hardness testing, and differential thermal analysis. At the highest applied pressures, the castings density increased when the shrinkage porosity was practically eliminated. The composite superficial hardness improved by increasing the applied squeeze. The indirect squeeze cast technique caused Al2Cu phase segregation to upper regions of the specimens, while conversely, the AlB12 reinforcements segregated preferentially at lower regions of the casting.

  7. Fabrication and Characterization of Carbon Nanofiber Reinforced Shape Memory Epoxy (CNFR-SME) Composites

    NASA Astrophysics Data System (ADS)

    Wang, Jiuyang

    Shape memory polymers have a wide range of applications due to their ability to mechanically change shapes upon external stimulus, while their achievable composite counterparts prove even more versatile. An overview of literature on shape memory materials, fillers and composites was provided to pave a foundation for the materials used in the current study and their inherent benefits. This study details carbon nanofiber and composite fabrication and contrasts their material properties. In the first section, the morphology and surface chemistry of electrospun-poly(acrylonitrile)-based carbon nanofiber webs were tailored through various fabrication methods and impregnated with a shape memory epoxy. The morphologies, chemical compositions, thermal stabilities and electrical resistivities of the carbon nanofibers and composites were then characterized. In the second section, an overview of thermal, mechanical and shape memory characterization techniques for shape memory polymers and their composites was provided. Thermal and mechanical properties in addition to the kinetic and dynamic shape memory performances of neat epoxy and carbon nanofiber/epoxy composites were characterized. The various carbon nanofiber web modifications proved to have notable influence on their respective composite performances. The results from these two sections lead to an enhanced understanding of these carbon nanofiber reinforced shape memory epoxy composites and provided insight for future studies to tune these composites at will.

  8. High-rate fabrication methods for carbon fiber-reinforced composites

    SciTech Connect

    Fanter, D.L.; Strandburg, Del.B.; Dry, A.C.

    1996-12-31

    Carbon fiber reinforced composites (CFRCs) were developed for highly weight-critical aerospace applications. During the 25-year history of CFRCs, reduced costs of carbon fiber and fabrication methods have broadened the applications of CFRCs. Improved fabrication methods coupled with continued cost reductions of carbon fiber are enabling the next application areas of CFRC applications: civil construction and transportation. Carbon fiber-reinforced concrete provides increased strength and earthquake resistance to civil structures. Transportation applications, driven by new mandates for fuel economy and air quality, represent a huge market for strong, light CFRCs. Both of these new CFRC application areas are dependent upon the development of high-rate, low-cost fabrication methods to meet the demands for rapid, economical construction of large structures. This paper reports the development of two high-rate fabrication methods for producing economical structural composites for civil construction and transportation. Carbon-epoxy tubes for composite-confined concrete civil structures were formed by filament winding large, 320,000 filament, carbon fiber strands. This large-strand filament-winding method builds CFRC structures at rates of over 200 pounds of carbon fiber per hour, Continuous Resin Transfer Molding (CRTM{trademark}) produces constant cross-section composite beams from woven or stitched fiber preforms, fiber tows, and injected resin. Composite channels produced by CRTM{trademark} are being evaluated as replacement for steel channel sections commonly used in truck frame rails. These composite beams represent a weight savings of up to 400 lbs per truck -- a savings that translates directly into payload.

  9. Numerically design the injection process parameters of parts fabricated with ramie fiber reinforced green composites

    NASA Astrophysics Data System (ADS)

    Chen, L. P.; He, L. P.; Chen, D. C.; Lu, G.; Li, W. J.; Yuan, J. M.

    2017-01-01

    The warpage deformation plays an important role on the performance of automobile interior components fabricated with natural fiber reinforced composites. The present work investigated the influence of process parameters on the warpage behavior of A pillar trim made of ramie fiber (RF) reinforced polypropylene (PP) composites (RF/PP) via numerical simulation with orthogonal experiment method and range analysis. The results indicated that fiber addition and packing pressure were the most important factors affecting warpage. The A pillar trim can achieved the minimum warpage value as of 2.124 mm under the optimum parameters. The optimal process parameters are: 70% percent of the default value of injection pressure for the packing pressure, 20 wt% for the fiber addition, 185 °C for the melt °C for the mold temperature, 7 s for the filling time and 17 s for the packing time.

  10. RC beams shear-strengthened with fabric-reinforced-cementitious-matrix (FRCM) composite

    NASA Astrophysics Data System (ADS)

    Loreto, Giovanni; Babaeidarabad, Saman; Leardini, Lorenzo; Nanni, Antonio

    2015-12-01

    The interest in retrofit/rehabilitation of existing concrete structures has increased due to degradation and/or introduction of more stringent design requirements. Among the externally-bonded strengthening systems fiber-reinforced polymers is the most widely known technology. Despite its effectiveness as a material system, the presence of an organic binder has some drawbacks that could be addressed by using in its place a cementitious binder as in fabric-reinforced cementitious matrix (FRCM) systems. The purpose of this paper is to evaluate the behavior of reinforced concrete (RC) beams strengthened in shear with U-wraps made of FRCM. An extensive experimental program was undertaken in order to understand and characterize this composite when used as a strengthening system. The laboratory results demonstrate the technical viability of FRCM for shear strengthening of RC beams. Based on the experimental and analytical results, FRCM increases shear strength but not proportionally to the number of fabric plies installed. On the other hand, FRCM failure modes are related with a high consistency to the amount of external reinforcement applied. Design considerations based on the algorithms proposed by ACI guidelines are also provided.

  11. Damage and fracture in fabric-reinforced composites under quasi-static and dynamic bending

    NASA Astrophysics Data System (ADS)

    Ullah, H.; Harland, A. R.; Silberschmidt, V. V.

    2013-07-01

    Fabric-reinforced polymer composites used in sports products can be exposed to different in-service conditions such as large deformations caused by quasi-static and dynamic loading. Composite materials subjected to such bending loads can demonstrate various damage modes - matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution in composites affects both their in-service properties and performance that can deteriorate with time. Such behaviour needs adequate means of analysis and investigation, the main approaches being experimental characterisation and non-destructive examination of internal damage in composite laminates. This research deals with a deformation behaviour and damage in carbon fabric-reinforced polymer (CFRP) laminates caused by quasi-static and dynamic bending. Experimental tests were carried out to characterise the behaviour of a CFRP material under large-deflection bending, first in quasi-static and then in dynamic conditions. Izod-type impact bending tests were performed on un-notched specimens of CFRP using a Resil impactor to assess the transient response and energy absorbing capability of the material. X-ray micro computed tomography (micro-CT) was used to analyse various damage modes in the tested specimens. X-ray tomographs revealed that through-thickness matrix cracking, inter-ply and intra-ply delamination such as tow debonding, and fabric fracture were the prominent damage modes both in quasi-static and dynamic test specimens. However, the inter-ply damage was localised at impact location in dynamically tested specimens, whereas in the quasi-static specimens, it spread almost over the entire interface.

  12. Solid Freeform Fabrication of Continuous Fiber Reinforced Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, R.; Walish, J.; Fox, M.; Rigali, M.; Sutaria, M.; Gillespie, John W., Jr.; Yarlagadda, Shridhar; Effinger, Mike

    2000-01-01

    For propulsion related applications, materials must be able to demonstrate excellent ablation and oxidation resistance at temperature approaching 3500'C, adequate load bearing capabilities, non-catastrophic failure modes, and ability to withstand transient thermal shock. A potential list of propulsion-material property requirements includes, low density, high elastic modulus, low thermal-expansion coefficient, high thermal conductivity, excellent erosion and oxidation/corrosion resistance, and flaw-insensitivity. In many cases, they will also need to be able to be joined, survive thermal cycling and multi-axial stress states, and for reusable applications, the materials must maintain the above attributes after prolonged exposure to extremely harsh chemical environments. The final and possibly most important attribute for these materials are the need to be lower cost and readily available in large quantities. Recently, Advanced Ceramics Research, Inc. (ACR) has developed low cost, flexible- manufacturing processes for Zr & Hf-based carbon fiber reinforced composites, materials with good oxidation and ablation resistance up to 3500 C. This process, called Continuous Composite Co-extrusion (C(sup 3)), incorporates carbon fibers to fabricate 'in-situ' carbide and boride-matrix/carbon fiber composites. This is a variation of ACR's manufacturing process for low-cost structural ceramic materials called Fibrous Monoliths With carbon fiber reinforcements. Fibrous Monolithic materials have a distinct fibrous texture, consist of intertwined cells of a primary phase, separated by cell boundaries of a tailored secondary phase and show very high fracture energies, damage tolerance, and graceful failure. Since they are monolithic powder based composites-, they can be manufactured by conventional powder processing techniques using inexpensive raw materials. This combination of high performance and low cost is a breakthrough that could enable wider application of ceramics in high

  13. Solid Free-Form Fabrication of Continuous Fiber Reinforced Composites for Propulsion Application

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, R.; Walish, J.; Fox, M.; Rigali, M.; Sutaria, M.; Gillespie, John W., Jr.; Yarlagadda, Shridhar; Effinger, Mike; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    For propulsion related applications, materials must be able to demonstrate excellent ablation and oxidation resistance at temperature approaching 3500 C, adequate load bearing capabilities, non-catastrophic failure modes, and ability to withstand transient thermal shock. A potential list of propulsion-material property requirements includes, low density, high elastic modulus, low thermal-expansion coefficient, high thermal conductivity, excellent erosion and oxidation/corrosion resistance, and flaw-insensitivity. In many cases, they will also need to be able to be joined, survive thermal cycling and multi-axial stress states, and for reusable applications, the materials must maintain the above attributes after prolonged exposure to extremely harsh chemical environments. The final and possibly most important attribute for these materials are the need to be lower cost and readily available in large quantities. Recently, Advanced Ceramics Research, Inc. (ACR) has developed low cost, flexible-manufacturing processes for Zr & Hf-based carbon fiber reinforced composites, materials with good oxidation and ablation resistance up to 3500 C. This process, called Continuous Composite Co-extrusion (C(sup 3)), incorporates carbon fibers to fabricate 'in-situ' carbide and boride-matrix/carbon fiber composites. M is a variation of ACR's manufacturing process for low-cost structural ceramic materials called Fibrous Monoliths with carbon fiber reinforcements. Fibrous Monolithic materials have a distinct fibrous texture, consist of intertwined cells of a primary phase, separated by cell boundaries of a tailored secondary phase and show very high fracture energies, damage tolerance, and graceful failure. Since they are monolithic powder based composites; they can be manufactured by conventional powder processing techniques using inexpensive raw materials. This combination of high performance and low cost is a breakthrough that could enable wider application of ceramics in high

  14. Solid Freeform Fabrication of Continuous Fiber Reinforced Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, R.; Walish, J.; Fox, M.; Rigali, M.; Sutaria, M.; Gillespie, John W., Jr.; Yarlagadda, Shridhar; Effinger, Mike

    2000-01-01

    For propulsion related applications, materials must be able to demonstrate excellent ablation and oxidation resistance at temperature approaching 3500'C, adequate load bearing capabilities, non-catastrophic failure modes, and ability to withstand transient thermal shock. A potential list of propulsion-material property requirements includes, low density, high elastic modulus, low thermal-expansion coefficient, high thermal conductivity, excellent erosion and oxidation/corrosion resistance, and flaw-insensitivity. In many cases, they will also need to be able to be joined, survive thermal cycling and multi-axial stress states, and for reusable applications, the materials must maintain the above attributes after prolonged exposure to extremely harsh chemical environments. The final and possibly most important attribute for these materials are the need to be lower cost and readily available in large quantities. Recently, Advanced Ceramics Research, Inc. (ACR) has developed low cost, flexible- manufacturing processes for Zr & Hf-based carbon fiber reinforced composites, materials with good oxidation and ablation resistance up to 3500 C. This process, called Continuous Composite Co-extrusion (C(sup 3)), incorporates carbon fibers to fabricate 'in-situ' carbide and boride-matrix/carbon fiber composites. This is a variation of ACR's manufacturing process for low-cost structural ceramic materials called Fibrous Monoliths With carbon fiber reinforcements. Fibrous Monolithic materials have a distinct fibrous texture, consist of intertwined cells of a primary phase, separated by cell boundaries of a tailored secondary phase and show very high fracture energies, damage tolerance, and graceful failure. Since they are monolithic powder based composites-, they can be manufactured by conventional powder processing techniques using inexpensive raw materials. This combination of high performance and low cost is a breakthrough that could enable wider application of ceramics in high

  15. Solid Free-Form Fabrication of Continuous Fiber Reinforced Composites for Propulsion Application

    NASA Technical Reports Server (NTRS)

    Vaidyanathan, R.; Walish, J.; Fox, M.; Rigali, M.; Sutaria, M.; Gillespie, John W., Jr.; Yarlagadda, Shridhar; Effinger, Mike; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    For propulsion related applications, materials must be able to demonstrate excellent ablation and oxidation resistance at temperature approaching 3500 C, adequate load bearing capabilities, non-catastrophic failure modes, and ability to withstand transient thermal shock. A potential list of propulsion-material property requirements includes, low density, high elastic modulus, low thermal-expansion coefficient, high thermal conductivity, excellent erosion and oxidation/corrosion resistance, and flaw-insensitivity. In many cases, they will also need to be able to be joined, survive thermal cycling and multi-axial stress states, and for reusable applications, the materials must maintain the above attributes after prolonged exposure to extremely harsh chemical environments. The final and possibly most important attribute for these materials are the need to be lower cost and readily available in large quantities. Recently, Advanced Ceramics Research, Inc. (ACR) has developed low cost, flexible-manufacturing processes for Zr & Hf-based carbon fiber reinforced composites, materials with good oxidation and ablation resistance up to 3500 C. This process, called Continuous Composite Co-extrusion (C(sup 3)), incorporates carbon fibers to fabricate 'in-situ' carbide and boride-matrix/carbon fiber composites. M is a variation of ACR's manufacturing process for low-cost structural ceramic materials called Fibrous Monoliths with carbon fiber reinforcements. Fibrous Monolithic materials have a distinct fibrous texture, consist of intertwined cells of a primary phase, separated by cell boundaries of a tailored secondary phase and show very high fracture energies, damage tolerance, and graceful failure. Since they are monolithic powder based composites; they can be manufactured by conventional powder processing techniques using inexpensive raw materials. This combination of high performance and low cost is a breakthrough that could enable wider application of ceramics in high

  16. Mg-Zn based composites reinforced with bioactive glass (45S5) fabricated via powder metallurgy

    NASA Astrophysics Data System (ADS)

    Ab llah, N.; Jamaludin, S. B.; Daud, Z. C.; Zaludin, M. A. F.

    2016-07-01

    Metallic implants are shifting from bio-inert to bioactive and biodegradable materials. These changes are made in order to improve the stress shielding effect and bio-compatibility and also avoid the second surgery procedure. Second surgery procedure is required if the patient experienced infection and implant loosening. An implant is predicted to be well for 15 to 20 years inside patient body. Currently, magnesium alloys are found to be the new biomaterials because of their properties close to the human bones and also able to degrade in the human body. In this work, magnesium-zinc based composites reinforced with different content (5, 15, 20 wt. %) of bioactive glass (45S5) were fabricated through powder metallurgy technique. The composites were sintered at 450˚C. Density and porosity of the composites were determined using the gas pycnometer. Microstructure of the composites was observed using an optical microscope. In-vitro bioactivity behavior was evaluated in the simulated body fluid (SBF) for 7 days. Fourier Transform Infrared (FTIR) was used to characterize the apatite forming on the samples surface. The microstructure of the composite showed that the pore segregated near the grain boundaries and bioglass clustering was observed with increasing content of bioglass. The true density of the composites increased with the increasing content of bioglass and the highest value of porosity was indicated by the Mg-Zn reinforced with 20 wt.% of bioglass. The addition of bio-glass to the Mg-Zn has also induced the formation of apatite layer after soaking in SBF solution.

  17. Influence of constituent properties and geometric form on behavior of woven fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Pipes, R. B.; Wilson, D. W.

    1984-01-01

    Th potential for woven fabric composite forms to increase the interlaminar strength and toughness properties of laminated composite septems is studied. Experimental and analytical studies were performed on a z-axis fabric.

  18. Load bearing capacity of fiber-reinforced and unreinforced composite resin CAD/CAM-fabricated fixed dental prostheses.

    PubMed

    Başaran, Emine Göncü; Ayna, Emrah; Vallittu, Pekka K; Lassila, Lippo V J

    2013-02-01

    It is unclear if fiber-reinforced fixed dental prostheses can be fabricated with physical properties that make them suitable for definitive prostheses. The purpose of this study was to compare the load bearing capacity of fiber-reinforced and unreinforced computer-aided design/computer-aided manufacturing (CAD/CAM) fabricated fixed dental prostheses. Fixed dental prostheses were fabricated with CAD/CAM from 3 experimental fiber-reinforced composite resin blocks, 1 experimental composite resin block, and 1 commercially available composite resin block. The experimental fiber-reinforced composite resin was prepared by mixing dimethacrylate resin with filler particles of BaO silicate and E-glass fiber. Different ratios of resin, filler, and fiber were used to fabricate specimens measuring 15.5 × 19 × 39 mm, which were allocated to 5 different groups (n=8) and statically loaded until final fracture. Statistical analyses were calculated according to final fracture values. A 1-way ANOVA and the Tukey post hoc multiple comparison test were used (α=.05). All groups showed significantly different load-bearing capacities (P<.001). Experimental randomly oriented fiber-reinforced composite resin blocks revealed the highest load-bearing capacity (2163 ±246 N), whereas commercial composite resin blocks showed the lowest (1290 ±172 N). Fixed partial dental prostheses consisting of experimental fiber-reinforced composite resin blocks showed higher load-bearing capacities than did unreinforced composite resin blocks. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  19. Long-Term Isothermal Aging Effects on Carbon Fabric-Reinforced PMR-15 Composites: Compression Strength

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; Roberts, Gary D.; Kamvouris, John E.

    1996-01-01

    A study was conducted to determine the effects of long-term isothermal thermo-oxidative aging on the compressive properties of T-650-35 fabric reinforced PMR-15 composites. The temperatures that were studied were 204, 260, 288, 316, and 343 C. Specimens of different geometries were evaluated. Cut edge-to-surface ratios of 0.03 to 0.89 were fabricated and aged. Aging times extended to a period in excess of 15,000 hours for the lower temperature runs. The unaged and aged specimens were tested in compression in accordance with ASTM D-695. Both thin and thick (plasma) specimens were tested. Three specimens were tested at each time/temperature/geometry condition. The failure modes appeared to be initiated by fiber kinking with longitudinal, interlaminar splitting. In general, it appears that the thermo-oxidative degradation of the compression strength of the composite material may occur by both thermal (time-dependent) and oxidative (weight-loss) mechanisms. Both mechanisms appear to be specimen-thickness dependent.

  20. Fabrication of Glass Fiber Reinforced Composites Based on Bio-Oil Phenol Formaldehyde Resin

    PubMed Central

    Cui, Yong; Chang, Jianmin; Wang, Wenliang

    2016-01-01

    In this study, bio-oil from fast pyrolysis of renewable biomass was added by the mass of phenol to synthesize bio-oil phenol formaldehyde (BPF) resins, which were used to fabricate glass fiber (GF) reinforced BPF resin (GF/BPF) composites. The properties of the BPF resin and the GF/BPF composites prepared were tested. The functional groups and thermal property of BPF resin were thoroughly investigated by Fourier transform infrared (FTIR) spectra and dynamic thermomechanical analysis (DMA). Results indicated that the addition of 20% bio-oil exhibited favorable adaptability for enhancing the stiffness and heat resistance of phenol formaldehyde (PF) resin. Besides, high-performance GF/BPF composites could be successfully prepared with the BPF resin based on hand lay-up process. The interface characteristics of GF/BPF composites were determined by the analysis of dynamic wettability (DW) and scanning electron microscopy (SEM). It exhibited that GF could be well wetted and embedded in the BPF resin with the bio-oil addition of 20%. PMID:28774009

  1. Approximating the stress field within the unit cell of a fabric reinforced composite using replacement elements

    NASA Technical Reports Server (NTRS)

    Foye, R. L.

    1993-01-01

    This report concerns the prediction of the elastic moduli and the internal stresses within the unit cell of a fabric reinforced composite. In the proposed analysis no restrictions or assumptions are necessary concerning yarn or tow cross-sectional shapes or paths through the unit cell but the unit cell itself must be a right hexagonal parallelepiped. All the unit cell dimensions are assumed to be small with respect to the thickness of the composite structure that it models. The finite element analysis of a unit cell is usually complicated by the mesh generation problems and the non-standard, adjacent-cell boundary conditions. This analysis avoids these problems through the use of preprogrammed boundary conditions and replacement materials (or elements). With replacement elements it is not necessary to match all the constitutional material interfaces with finite element boundaries. Simple brick-shaped elements can be used to model the unit cell structure. The analysis predicts the elastic constants and the average stresses within each constituent material of each brick element. The application and results of this analysis are demonstrated through several example problems which include a number of composite microstructures.

  2. Thermal expansion properties of carbon nanotube/silicon carbide particle-reinforced magnesium composites fabricated by squeeze infiltration

    NASA Astrophysics Data System (ADS)

    Cho, Dae Hyun; Nam, Ji Hoon; Lee, Byoung Woo; Yim, Si On; Park, Ik Min

    2016-03-01

    In this study, hybrid composites of AZ91 Mg alloy reinforced with carbon nanotubes (CNTs) and silicon carbide particles (SiCps) were successfully fabricated by the squeeze infiltration method. For this fabrication, hybrid preforms of CNTs (5, 10, and 15 vol%) and SiCps (30 vol%) were produced by vacuum suction from slurry mix containing organic and inorganic binders. Hybrid CNT+SiCp/AZ91 Mg composites were fabricated by squeeze infiltration, and the melt infiltrated well between the reinforcements during squeeze infiltration to produce a hybrid MMC with virtually no pores. Their microstructural and thermal expansion properties were evaluated The resulting CNT+SiCp/AZ91 Mg hybrid composites were found to exhibit a significant decrease in their coefficients of thermal expansion with an increase in the CNT volume fraction, owing to the near-zero thermal expansion of the CNTs and the CTE mismatch between them and the AZ91 Mg matrix.

  3. The elastic and inelastic behavior of woven graphite fabric reinforced polyimide composites

    NASA Astrophysics Data System (ADS)

    Searles, Kevin H.

    In many aerospace and conventional engineering applications, load-bearing composite structures are designed with the intent of being subjected to uniaxial stresses that are predominantly tensile or compressive. However, it is likely that biaxial and possibly triaxial states of stress will exist throughout the in-service life of the structure or component. The existing paradigm suggests that unidirectional tape materials are superior under uniaxial conditions since the vast majority of fibers lie in-plane and can be aligned to the loading axis. This may be true, but not without detriment to impact performance, interlaminar strength, strain to failure and complexity of part geometry. In circumstances where a sufficient balance of these properties is required, composites based on woven fabric reinforcements become attractive choices. In this thesis, the micro- and mesoscale elastic behavior of composites based on 8HS woven graphite fabric architectures and polyimide matrices is studied analytically and numerically. An analytical model is proposed to predict the composite elastic constants and is verified using numerical strain energy methods of equivalence. The model shows good agreement with the experiments and numerical strain energy equivalence. Lamina stresses generated numerically from in-plane shear loading show substantial shear and transverse normal stress concentrations in the transverse undulated tow which potentially leads to intralaminar damage. The macroscale inelastic behavior of the same composites is also studied experimentally and numerically. On an experimental basis, the biaxial and modified biaxial Iosipescu test methods are employed to study the weaker-mode shear and biaxial failure properties at room and elevated temperatures. On a numerical basis, the macroscale inelastic shear behavior of the composites is studied. Structural nonlinearities and material nonlinearities are identified and resolved. In terms of specimen-to-fixture interactions

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

    PubMed

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

    2016-05-01

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

  5. Fabrication and mechanical characterization of graphene oxide-reinforced poly (acrylic acid)/gelatin composite hydrogels

    NASA Astrophysics Data System (ADS)

    Faghihi, Shahab; Gheysour, Mahsa; Karimi, Alireza; Salarian, Reza

    2014-02-01

    Hydrogels have found many practical uses in drug release, wound dressing, and tissue engineering. However, their applications are restricted due to their weak mechanical properties. The role of graphene oxide nanosheets (GONS) as reinforcement agent in poly (acrylic acid) (PAA)/Gelatin (Gel) composite hydrogels is investigated. Composite hydrogels are synthesized by thermal initiated redox polymerization method. Samples are then prepared with 20 and 40 wt. % of PAA, an increasing amount of GONS (0.1, 0.2, and 0.3 wt. %), and a constant amount of Gel. Subsequently, cylindrical hydrogel samples are subjected to a series of compression tests in order to measure their elastic modulus, maximum stress and strain. The results exhibit that the addition of GONS increases the Young's modulus and maximum stress of hydrogels significantly as compared with control (0.0 wt. % GONS). The highest Young's modulus is observed for hydrogel with GO (0.2 wt. %)/PAA (20 wt. %), whereas the highest maximum stress is detected for GO (0.2 wt. %)/PAA (40 wt. %) specimen. The addition of higher amounts of GONS leads to a decrease in the maximum stress of the hydrogel GO (0.3 wt. %)/PAA (40 wt. %). No significant differences are detected for the maximum strain among the hydrogel samples, as the amount of GONS increased. These results suggest that the application of GONS could be used to improve mechanical properties of hydrogel materials. This study may provide an alternative for the fabrication of low-cost graphene/polymer composites with enhanced mechanical properties beneficial for tissue engineering applications.

  6. Fabrications of Pva Coated NANO-B4C Reinforced Hdpe Composites

    NASA Astrophysics Data System (ADS)

    Uhm, Young Rang; Kim, Jaewoo; Jung, Jinwoo; Rhee, Chang Kyu

    Nano-B4C powder whose surface was coated with polyvinylalcohol (PVA) was prepared by using a ball milling mechanical activation process. As-prepared powders exhibit the structure of PVA layer on the surface of nano-sized B4C and the size of the produced core/shell structured nano-B4C/PVA particles was in the range of 50 to 200 nm. The sheets of the HDPE composite reinforced by the nano- and micro-B4C fillers were fabricated by hot pressing following the melt mixing process respectively. The structures of prepared nano-B4C/PVA powders and the degree of particles dispersion in HDPE were observed by means of X-ray diffraction as well as the SEM/TEM images. It was found that the dispersion of the core/shell structured nano-B4C/PVA fillers in HDPE was more homogeneous than the surface-untreated micro-B4C fillers in HDPE.

  7. Mechanical properties and fabrication of small boat using woven glass/sugar palm fibres reinforced unsaturated polyester hybrid composite

    NASA Astrophysics Data System (ADS)

    Misri, S.; Leman, Z.; Sapuan, S. M.; Ishak, M. R.

    2010-05-01

    In recent years, sugar palm fibre has been found to have great potential to be used as fibre reinforcement in polymer matrix composites. This research investigates the mechanical properties of woven glass/sugar palm fibres reinforced unsaturated polyester hybrid composite. The composite specimens made of different layer of fibres such as strand mat, natural and hand woven of sugar palm fibres. The composites were fabricated using a compression moulding technique. The tensile and impact test was carried out in accordance to ASTM 5083 and ASTM D256 standard. The fibre glass boat is a familiar material used in boat industry. A lot of research on fabrication process such as lay-up, vacuum infusion mould and resin transfer mould has been conducted. Hybrid material of sugar palm fibre and fibre glass was used in fabricating the boat. This research investigates the method selection for fabrication of small boat application of natural fibre composites. The composite specimens made of different layer of fibres; woven glass fibre, strand mat, natural and hand woven of woven sugar palm fibres were prepared. The small boat were fabricated using a compression moulding and lay up technique. The results of the experiment showed that the tensile strength, tensile modulus, elongation at break value and impact strength were higher than the natural woven sugar palm fibre. The best method for fabricating the small boat was compression moulding technique. As a general conclusion, the usage of glass fibre had improved the tensile properties sugar palm fibre composites and compression moulding technique is suitable to be used in making a small boat application of natural fibre composites.

  8. Comparison between viscous elastic plastic behaviour of the composites reinforced with plain glass fabric and chopped strand mat

    NASA Astrophysics Data System (ADS)

    Stanciu, M. D.; Harapu, A.; Teodorescu Drăghicescu, H.; Curtu, I.; Savin, A.

    2016-08-01

    Composite structures are used mainly two types of reinforcement materials: woven glass fabric and the chopped strand mat, each contributing either to increase the resistance of the composite whole or in isotropic distribution of stresses. This paper presents a comparison of the visco-elastic characteristics of composites reinforced with glass fabric and the chopped strand mat and the breaking mode of the two types of the composite. The first type of samples contain three layers of chopped strand mat known as MAT with density of 450g/m2 and 225g/m2) and the second type is composed of four layers of woven glass fabric type RT500 (density of 500g/m2). Both specimens were cut in accordance with EN ISO 527-2 SR. Characteristic curve of the two types of specimens highlights visco-elastic-plastic behavior which largely depends on the type of reinforcement used as the matrix resin is the same in both cases (orthophthalic polyester resin). Breaking mode of those types of specimens were observed and analyzed by electronic microscope.

  9. Self-reinforced composites of hydroxyapatite-coated PLLA fibers: fabrication and mechanical characterization.

    PubMed

    Charles, Lyndon F; Kramer, Erica R; Shaw, Montgomery T; Olson, James R; Wei, Mei

    2013-01-01

    Self-reinforced composites (SRCs) are materials where both the matrix and fiber-reinforcing phase are made up of the same polymer. Improved bonding can be achieved with self-reinforced composites compared to traditional dual-polymer, fiber-reinforced composites owing to the identical chemistry of the components in SRCs. Bonding between the fiber and matrix phase is an important factor in applications where mechanical stability is required, such as in the field of bone repair. In this study, we prepared bioabsorbable poly(L-lactic acid)/hydroxyapatite (PLLA/HA) self-reinforced composites via a three-step process that includes surface etching of the fiber, the deposition of the HA coating onto the PLLA fibers through immersion in simulated body fluid (SBF), and hot compaction molding. Although coated with a layer of HA, self-reinforced composites were successfully generated by hot compaction. The effects of compaction time (15 and 30 min), compaction temperature (140, 150, 155, 160, 165, and 170 °C), and HA wt% (0, 5, 10, and 15 wt%) on flexural mechanical properties were studied. Mechanical test results indicated that in unfilled (no HA) PLLA SRCs, compaction time and temperature increased the flexural modulus of the composites tested. Based on the results obtained for unfilled composites, a single compaction time and temperature condition of 15 min and 170 °C were selected to study the effect of HA loading on the composite mechanical properties. HA was successfully loaded onto the fibers at 0, 5, 10, and 15 wt% before hot compaction and was found to significantly increase flexural modulus (P=0.0001). Modulus values ranged from 8.3 GPa±0.5 (0 wt% HA) to 9.7 GPa±0.6 (15 wt% HA). Microscopy results suggest that the HA in these composites forms a nodular-like structure along the fibers, which allows polymer-polymer contact yet prevents longitudinal shear. The procedure used successfully generated composites with flexural moduli near the lower range of bone that may

  10. Effect of Sericin on Mechanical Behavior of Composite Material Reinforced by Silk Woven Fabric

    NASA Astrophysics Data System (ADS)

    Kimura, Teruo; Ino, Haruhiro; Hanada, Koji; Katori, Sigetaka

    Recent, attention has been given to shift from glass fibers and carbon fibers to natural fibers for FRP composites for the goal of protecting the environment. This paper concerned with the application of silk fabric for composite materials. Polypropylene (PP) was used for the matrix material and the silk fabric composites were molded using a compression molding method. Especially, the effect of sericin on mechanical behaviors of composite materials was discussed. Good adhesion between silk and PP was obtained by removing the sericin existing around the fibroin. The tensile modulus of composite decreased with decreasing the sericin because of the flexibility of silk fibers without sericin. In particular, the higher Izod impact value was obtained for the composites containing the silk fibers without sericin.

  11. Fabrication of SiC particulate reinforced polyester matrix composite and investigation

    NASA Astrophysics Data System (ADS)

    Selvam, R.; Ravi, S.; Raja, R.

    2017-05-01

    Polymer composite provokes a new alternative material to engineering and domestic application. Polymeric nano composite have been intensively investigated due to the performance improvement when a small amount of nano sized particulates are added to matrix. The distinguished properties of SiC particulates influence to make a polymeric composite. This composite material has many application such as mechanical, automobile, marine, appliances and packaging. The composite material is fabricated in deferent weight ratio and it is characterized to understand the mechanical behavior, which was studied by various testing method under external load.

  12. Investigation and modeling of the elastic-plastic fracture behavior of continuous woven fabric-reinforced ceramic composites

    SciTech Connect

    Kahl, W.K.

    1997-03-01

    The paper describes a study which attempted to extrapolate meaningful elastic-plastic fracture toughness data from flexure tests of a chemical vapor-infiltrated SiC/Nicalon fiber-reinforced ceramic matrix composite. Fibers in the fabricated composites were pre-coated with pyrolytic carbon to varying thicknesses. In the tests, crack length was not measured and the study employed an estimate procedure, previously used successfully for ductile metals, to derive J-R curve information. Results are presented in normalized load vs. normalized displacements and comparative J{sub Ic} behavior as a function of fiber precoating thickness.

  13. Carbon Nanotubes Reinforced Composites for Biomedical Applications

    PubMed Central

    Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia

    2014-01-01

    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo. PMID:24707488

  14. Carbon nanotubes reinforced composites for biomedical applications.

    PubMed

    Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia

    2014-01-01

    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo.

  15. Multi-Scaled Modeling the Mechanical Properties of Tubular Composites Reinforced with Innovated 3D Weft Knitted Spacer Fabrics

    NASA Astrophysics Data System (ADS)

    Omrani, Elahe; Hasani, Hossein; Dibajian, Sayed Houssain

    2017-06-01

    Textile composites of 3D integrated spacer configurations have been recently focused by several researchers all over the world. In the present study, newly-designed tubular composites reinforced with 3D spacer weft knitted fabrics were considered and the effects of their structural parameters on some applicable mechanical properties were investigated. For this purpose, two different samples of 3D spacer weft knitted textile types in tubular form were produced on an electronic flat knitting machine, using glass/nylon hybrid yarns. Thermoset tubular-shaped composite parts were manufactured via vacuum infusion molding process using epoxy resin. The mechanical properties of the produced knitted composites in term of external static and internal hydrostatic pressures were evaluated. Resistance of the produced composites against the external static and internal hydrostatic pressures was numerically simulated using multi-scale modeling method. The finding revealed that there is acceptable correlation between experimental and theoretical results.

  16. Braided reinforced composite rods for the internal reinforcement of concrete

    NASA Astrophysics Data System (ADS)

    Gonilho Pereira, C.; Fangueiro, R.; Jalali, S.; Araujo, M.; Marques, P.

    2008-05-01

    This paper reports on the development of braided reinforced composite rods as a substitute for the steel reinforcement in concrete. The research work aims at understanding the mechanical behaviour of core-reinforced braided fabrics and braided reinforced composite rods, namely concerning the influence of the braiding angle, the type of core reinforcement fibre, and preloading and postloading conditions. The core-reinforced braided fabrics were made from polyester fibres for producing braided structures, and E-glass, carbon, HT polyethylene, and sisal fibres were used for the core reinforcement. The braided reinforced composite rods were obtained by impregnating the core-reinforced braided fabric with a vinyl ester resin. The preloading of the core-reinforced braided fabrics and the postloading of the braided reinforced composite rods were performed in three and two stages, respectively. The results of tensile tests carried out on different samples of core-reinforced braided fabrics are presented and discussed. The tensile and bending properties of the braided reinforced composite rods have been evaluated, and the results obtained are presented, discussed, and compared with those of conventional materials, such as steel.

  17. Optimized process parameters for fabricating metal particles reinforced 5083 Al composite by friction stir processing

    PubMed Central

    Bauri, Ranjit; Yadav, Devinder; Shyam Kumar, C.N.; Janaki Ram, G.D.

    2015-01-01

    Metal matrix composites (MMCs) exhibit improved strength but suffer from low ductility. Metal particles reinforcement can be an alternative to retain the ductility in MMCs (Bauri and Yadav, 2010; Thakur and Gupta, 2007) [1,2]. However, processing such composites by conventional routes is difficult. The data presented here relates to friction stir processing (FSP) that was used to process metal particles reinforced aluminum matrix composites. The data is the processing parameters, rotation and traverse speeds, which were optimized to incorporate Ni particles. A wide range of parameters covering tool rotation speeds from 1000 rpm to 1800 rpm and a range of traverse speeds from 6 mm/min to 24 mm/min were explored in order to get a defect free stir zone and uniform distribution of particles. The right combination of rotation and traverse speed was found from these experiments. Both as-received coarse particles (70 μm) and ball-milled finer particles (10 μm) were incorporated in the Al matrix using the optimized parameters. PMID:26566541

  18. Optimized process parameters for fabricating metal particles reinforced 5083 Al composite by friction stir processing.

    PubMed

    Bauri, Ranjit; Yadav, Devinder; Shyam Kumar, C N; Janaki Ram, G D

    2015-12-01

    Metal matrix composites (MMCs) exhibit improved strength but suffer from low ductility. Metal particles reinforcement can be an alternative to retain the ductility in MMCs (Bauri and Yadav, 2010; Thakur and Gupta, 2007) [1,2]. However, processing such composites by conventional routes is difficult. The data presented here relates to friction stir processing (FSP) that was used to process metal particles reinforced aluminum matrix composites. The data is the processing parameters, rotation and traverse speeds, which were optimized to incorporate Ni particles. A wide range of parameters covering tool rotation speeds from 1000 rpm to 1800 rpm and a range of traverse speeds from 6 mm/min to 24 mm/min were explored in order to get a defect free stir zone and uniform distribution of particles. The right combination of rotation and traverse speed was found from these experiments. Both as-received coarse particles (70 μm) and ball-milled finer particles (10 μm) were incorporated in the Al matrix using the optimized parameters.

  19. Thickness and Reinforcement Fiber Content Control in Composites by Vacuum-Assisted Resin Transfer Molding Fabrication Processes

    DTIC Science & Technology

    2005-06-01

    cut fabrics, 3-rigid spacers , 4-release fabric and transfer medium, 5-fill line, and 6-vacuum line. .........................3 Figure 2. The basic...reinforcement fibers. Legend: 1-cut fabrics, 2-transfer medium over release fabrics, 3-rigid spacers , 4-rigid cover plate, 5-fill line, 6-vacuum line, and 7...fabrics, 2-transfer medium over release fabrics, 3-rigid spacers , 4-rigid cover plate, 5-fill line, 6-vacuum line, and 7-rigid bottom plate

  20. Fabrication of single crystalline diamond reinforced aluminum matrix composite by powder metallurgy route

    NASA Astrophysics Data System (ADS)

    Kwon, Hansang; Leparoux, Marc; Heintz, Jean-Marc; Silvain, Jean-François; Kawasaki, Akira

    2011-10-01

    We have successfully fabricated highly densified aluminum (Al)-diamond composite materials by a simple hot press method. The thermal conductivity of the Al-diamond composite materials was measured. These materials had different types, sizes and fractions of diamond. These obtained values were discussed based on theoretically calculated values. The thermal conductivity of the composite materials, measured by Laser-Flash method, was found to have slightly increased compared to that of pure bulk Al. The obtained microstructures of the composite materials showed a lot of cleavage existing in the interface between the Al matrix and the diamond particles, which led to the low increment of the thermal conductivity. Moreover, Al-diamond bulk materials with different sintering temperatures in solid state, liquid phase, and transient region between solid and liquid of Al, have been synthesized.

  1. Penetration of carbon-fabric-reinforced composites by edge cracks during thermal aging

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; Kamvouris, John E.

    1994-01-01

    Thermo-oxidative stability (TOS) test results are significantly influenced by the formation and growth or presence of interlaminar and interlaminar cracks in the cut edges of all carbon-fiber-crosslinked high-temperature polymer matrix composites(exp 1-5) (i.e., unidirectional, crossplied, angle-plied, and fabric composites). The thermo-oxidative degradation of these composites is heavily dependent on the surface area that is exposed to the harmful environment and on the surface-to-volume ratio of the structure under study. Since the growth of cracks and voids on the composite surfaces significantly increases the exposed surface areas, it is imperative that the interaction between the aging process and the formation of new surface area as the aging time progresses be understood.

  2. Fabric orientation effects on the monotonic and fatigue behavior of continuous fiber-reinforced ceramic-matrix composites (CFCCs)

    NASA Astrophysics Data System (ADS)

    Miriyala, Narendernath

    Fabric orientation effects on the monotonic and fatigue behavior of two commercially available continuous fiber-reinforced ceramic-matrix composites (CFCCs) were investigated by performing flexure tests at room temperature in air, and at 1,000sp°C in an argon environment. The two CFCCs used in the study were: (i) a Nicalon woven-fabric reinforced alumina (Alsb2Osb3) matrix composite fabricated by the directed metal oxidation (DIMOX) process, and (ii) a Nicalon woven-fabric reinforced silicon carbide (SiC) matrix composite fabricated by an isothermal chemical vapor infiltration (ICVI) process. Specimens of square cross-section (3 mm x 3 mm of Nicalon/Alsb2Osb3 and 2 mm x 2 mm of Nicalon/SiC) were subjected to four-point bending loads to perform the monotonic and fatigue tests at room and elevated temperatures. The specimen configurations were designated as edge-on and transverse, depending on whether the load was applied parallel or perpendicular to the fabric plies, respectively. The monotonic and fatigue behavior of the Nicalon/Alsb2Osb3 composite was remarkably affected by the fabric orientation at room and elevated temperatures. The ultimate flexural strength (UFS) was significantly higher in the edge-on orientation, as compared to that in the transverse orientation, at RT and 1,000sp°C. Also, the stress at which the samples survived one million load cycles was higher in the edge-on orientation, relative to that in the transverse orientation, particularly at RT. Under monotonic and fatigue loadings, the samples tested in the edge-on orientation failed by specimen severance into two pieces, while the transversely oriented samples failed by specimen collapse. Due to the interlaminar weakness of the material, delamination cracks propagated in the transversely oriented samples, and the specimens failed by a complex combination of tensile, compressive and shear stresses. In contrast, the specimens tested in the edge-on orientation failed in a predominantly tensile

  3. Hybrid composite laminates reinforced with Kevlar/carbon/glass woven fabrics for ballistic impact testing.

    PubMed

    Randjbaran, Elias; Zahari, Rizal; Jalil, Nawal Aswan Abdul; Majid, Dayang Laila Abang Abdul

    2014-01-01

    Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

  4. Hybrid Composite Laminates Reinforced with Kevlar/Carbon/Glass Woven Fabrics for Ballistic Impact Testing

    PubMed Central

    Randjbaran, Elias; Zahari, Rizal; Abdul Jalil, Nawal Aswan; Abang Abdul Majid, Dayang Laila

    2014-01-01

    Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers. PMID:24955400

  5. Fabrication and characterization of nanoclay modified PMR type polyimide composites reinforced with 3D woven basalt fabric

    NASA Astrophysics Data System (ADS)

    Xie, Jianfei; Qiu, Yiping

    2009-07-01

    Nanoclay modified PMR type polyimide composites were prepared from 3D orthogonal woven basalt fiber performs and nanoclay modified polyimide matrix resin, which derived from methylene dianiline (MDA), dimethyl ester of 3,3',4,4'- oxydiphthalic acid (ODPE), monomethyl ester of cis-5-norbornene-endo-2,3-dicarboxylic acid (NE) and nanoclay. The Na+-montmorillonite was organically treated using a 1:1 molar ratio mixture of dodecylamine (C12) and MDA. The rheological properties of neat B-stage PMR polyimide and 2% clay modified B-stage PMR polyimide were investigated. Based on the results obtained from the rheological tests, a two step compression molding process can be established for the composites. In the first step, the 3D fabric preforms were impregnated with polyimide resin in a vacuum oven and heated up for degassing the volatiles and by-products. In the second step, composites were compressed. The internal structure of the composites was observed by a microscope. Incorporation of 2% clay showed an improvement in the Tg and stiffness of the PMR polyimide. The resulting composites exhibited high thermal stability and good mechanical properties.

  6. Fabrication and fracture toughness properties of carbon nanotube-reinforced cement composite

    NASA Astrophysics Data System (ADS)

    Luo, J. L.; Duan, Z.; Xian, G.; Li, Q.; Zhao, T.

    2011-03-01

    Multi-walled carbon nanotube (MWNT) reinforced cement composites (MWFRCs) were prepared with surfactant dispersion, ultrasonic treatment, and subsequently high-speed shear mixing processes. These MWFRCs were characterized in the fracture toughness property with single edge notch bend method. As found, the addition of nanotubes improves the stress-intensity factor (KIC), critical crack mouth opening displacement (δC) and flexural strength (σs) of the cured nanocomposite, significantly. The maximal enhancement arrives up to 56.4%, 119.4%, and 54.8%, compared to the baseline, respectively. These achievements are mainly attributed to the superior pulling-out effect of dispersed and tough MWNT fiber upon the notched cracks. Incorporation of acid-treated MWNT balances the σs, KIC, and δC values. Additional nanophase carbon black mixed into the above MWFRC further increases the corresponding fracture toughness, while additional short carbon fiber shows a negative effect.

  7. On processing development for fabrication of fiber reinforced composite, part 2

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung; Hou, Gene J. W.; Sheen, Jeen S.

    1989-01-01

    Fiber-reinforced composite laminates are used in many aerospace and automobile applications. The magnitudes and durations of the cure temperature and the cure pressure applied during the curing process have significant consequences for the performance of the finished product. The objective of this study is to exploit the potential of applying the optimization technique to the cure cycle design. Using the compression molding of a filled polyester sheet molding compound (SMC) as an example, a unified Computer Aided Design (CAD) methodology, consisting of three uncoupled modules, (i.e., optimization, analysis and sensitivity calculations), is developed to systematically generate optimal cure cycle designs. Various optimization formulations for the cure cycle design are investigated. The uniformities in the distributions of the temperature and the degree with those resulting from conventional isothermal processing conditions with pre-warmed platens. Recommendations with regards to further research in the computerization of the cure cycle design are also addressed.

  8. Fabrication of in-situ grown graphene reinforced Cu matrix composites

    PubMed Central

    Chen, Yakun; Zhang, Xiang; Liu, Enzuo; He, Chunnian; Shi, Chunsheng; Li, Jiajun; Nash, Philip; Zhao, Naiqin

    2016-01-01

    Graphene/Cu composites were fabricated through a graphene in-situ grown approach, which involved ball-milling of Cu powders with PMMA as solid carbon source, in-situ growth of graphene on flaky Cu powders and vacuum hot-press sintering. SEM and TEM characterization results indicated that graphene in-situ grown on Cu powders guaranteed a homogeneous dispersion and a good combination between graphene and Cu matrix, as well as the intact structure of graphene, which was beneficial to its strengthening effect. The yield strength of 244 MPa and tensile strength of 274 MPa were achieved in the composite with 0.95 wt.% graphene, which were separately 177% and 27.4% enhancement over pure Cu. Strengthening effect of in-situ grown graphene in the matrix was contributed to load transfer and dislocation strengthening. PMID:26763313

  9. The development, fabrication, and material characterization of polypropylene composites reinforced with carbon nanofiber and hydroxyapatite nanorod hybrid fillers

    PubMed Central

    Liao, Cheng Zhu; Wong, Hoi Man; Yeung, Kelvin Wai Kwok; Tjong, Sie Chin

    2014-01-01

    This study focuses on the design, fabrication, microstructural and property characterization, and biocompatibility evaluation of polypropylene (PP) reinforced with carbon nanofiber (CNF) and hydroxyapatite nanorod (HANR) fillers. The purpose is to develop advanced PP/CNF–HANR hybrids with good mechanical behavior, thermal stability, and excellent biocompatibility for use as craniofacial implants in orthopedics. Several material-examination techniques, including X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, tensile tests, and impact measurement are used to characterize the microstructural, mechanical, and thermal properties of the hybrids. Furthermore, osteoblastic cell cultivation and colorimetric assay are also employed for assessing their viability on the composites. The CNF and HANR filler hybridization yields an improvement in Young’s modulus, impact strength, thermal stability, and biocompatibility of PP. The PP/2% CNF–20% HANR hybrid composite is found to exhibit the highest elastic modulus, tensile strength, thermal stability, and biocompatibility. PMID:24648729

  10. The development, fabrication, and material characterization of polypropylene composites reinforced with carbon nanofiber and hydroxyapatite nanorod hybrid fillers.

    PubMed

    Liao, Cheng Zhu; Wong, Hoi Man; Yeung, Kelvin Wai Kwok; Tjong, Sie Chin

    2014-01-01

    This study focuses on the design, fabrication, microstructural and property characterization, and biocompatibility evaluation of polypropylene (PP) reinforced with carbon nanofiber (CNF) and hydroxyapatite nanorod (HANR) fillers. The purpose is to develop advanced PP/CNF-HANR hybrids with good mechanical behavior, thermal stability, and excellent biocompatibility for use as craniofacial implants in orthopedics. Several material-examination techniques, including X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, tensile tests, and impact measurement are used to characterize the microstructural, mechanical, and thermal properties of the hybrids. Furthermore, osteoblastic cell cultivation and colorimetric assay are also employed for assessing their viability on the composites. The CNF and HANR filler hybridization yields an improvement in Young's modulus, impact strength, thermal stability, and biocompatibility of PP. The PP/2% CNF-20% HANR hybrid composite is found to exhibit the highest elastic modulus, tensile strength, thermal stability, and biocompatibility.

  11. Fabrication of protective-coated SiC reinforced tungsten matrix composites with reduced reaction phases by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Umer, Malik Adeel; Lee, Dongju; Waseem, Owais Ahmed; Ryu, Ho Jin; Hong, Soon Hyung

    2016-05-01

    SiC reinforced tungsten matrix composites were fabricated via the spark plasma sintering process. In order to prevent an interfacial reaction between the SiC and tungsten during sintering, TiOx coated SiC particles were synthesized by a solution-based process. TiOx layer coated SiC particles were treated in high temperature nitriding conditions or annealed in a high temperature vacuum to form TiN or TiC coated SiC particles, respectively. The TiC layers coated on SiC particles successfully prevented tungsten from reacting with SiC; hence the proposed process resulted in successful fabrication of the SiC/W composites. The mechanical properties such as compressive strength and flexural strength of the composites were measured. Additionally, the effect of SiC on the high temperature oxidative ablation of tungsten was also investigated. The addition of SiC resulted in an improved oxidative ablation resistance of the tungsten-based composites.

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

    USDA-ARS?s Scientific Manuscript database

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

  13. Zrb2 nanoparticle cluster reinforced Al matrix composites fabricated by direct melt reaction

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenya; Yang, Rui; Liu, Menglu; Yue, Yamei; Tang, Zhenming; Meng, Mingai; Jiao, Lei

    2017-01-01

    In this work, ZrB2 nanoparticle cluster reinforced 6061Al composites were synthesized by direct melt reaction between halide salts (KBF4 and K2ZrF6) and Al. The experimental results revealed that the formation of Type III cluster (>60 µm, grain interior) depended on ZrB2 addition levels (>2 vol. %), whilst Type I (˜5 µm, grain interior) and II (5˜60 µm, grain/ interdendritic boundaries) were always present. The optimum tensile strength and elongation obtained in 2vol. % ZrB2/6061Al composite were substantially improved to approximately 1.52 and 2.75 times those of the 6061Al alloy. The enhanced strength was attributed to a combination effect of grain refinement (Type II cluster) and Orowan/CTE strengthening (Type I cluster). On the other hand, the impressive ductility increase was also ascribed to the presence of toughened clusters (Type I and II) that introduced the plastic slip bands and equiaxed dimples.

  14. 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.

  15. Composite Intersection Reinforcement

    NASA Technical Reports Server (NTRS)

    Misciagna, David T. (Inventor); Fuhrer, Jessica J. (Inventor); Funk, Robert S. (Inventor); Tolotta, William S. (Inventor)

    2013-01-01

    An assembly and method for manufacturing a composite reinforcement for unitizing a structure are provided. According to one embodiment, the assembly includes a base having a plurality of pins extending outwardly therefrom to define a structure about which a composite fiber is wound to define a composite reinforcement preform. The assembly also includes a plurality of mandrels positioned adjacent to the base and at least a portion of the composite reinforcement preform, and a cap that is positioned over at least a portion of the plurality of mandrels. The cap is configured to engage each of the mandrels to support the mandrels and the composite reinforcement preform during a curing process to form the composite reinforcement.

  16. Composite intersection reinforcement

    NASA Technical Reports Server (NTRS)

    Misciagna, David T. (Inventor); Fuhrer, Jessica J. (Inventor); Funk, Robert S. (Inventor); Tolotta, William S. (Inventor)

    2010-01-01

    An assembly and method for manufacturing a composite reinforcement for unitizing a structure are provided. According to one embodiment, the assembly includes a base having a plurality of pins extending outwardly therefrom to define a structure about which a composite fiber is wound to define a composite reinforcement preform. The assembly also includes a plurality of mandrels positioned adjacent to the base and at least a portion of the composite reinforcement preform, and a cap that is positioned over at least a portion of the plurality of mandrels. The cap is configured to engage each of the mandrels to support the mandrels and the composite reinforcement preform during a curing process to form the composite reinforcement.

  17. Continuous carbon nanotube reinforced composites.

    PubMed

    Ci, L; Suhr, J; Pushparaj, V; Zhang, X; Ajayan, P M

    2008-09-01

    Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.

  18. Fiber Coatings for the Fabrication of Graphite-Reinforced Magnesium Composites,

    DTIC Science & Technology

    1986-05-15

    either T300, P55, or P100 graphite fibers in pure magnesium, magnesium - 1% silicon, and magnesium alloy AZ91 have been fabricated. Preliminary...or PIO0 fibers in either pure Mg, Mg-l% Si, or Mg alloy AZ91 (Mg-9%AI-I%Zn). Wires of each of these fibers in each of these matrices typically show

  19. Fabrication of carbon nanofiber-reinforced aluminum matrix composites assisted by aluminum coating formed on nanofiber surface by in situ chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ogawa, Fumio; Masuda, Chitoshi

    2015-01-01

    The van der Waals agglomeration of carbon nanofibers (CNFs) and the weight difference and poor wettability between CNFs and aluminum hinder the fabrication of dense CNF-reinforced aluminum matrix composites with superior properties. In this study, to improve this situation, CNFs were coated with aluminum by a simple and low-cost in situ chemical vapor deposition (in situ CVD). Iodine was used to accelerate the transport of aluminum atoms. The coating layer formed by the in situ CVD was characterized using scanning electron microscopy, transmission electron microscopy, x-ray diffraction, Fourier transform-infrared spectroscopy, and x-ray photoelectron spectroscopy. The results confirmed that the CNFs were successfully coated with aluminum. The composites were fabricated to investigate the effect of the aluminum coating formed on the CNFs. The dispersion of CNFs, density, Vickers micro-hardness and thermal conductivity of the composites fabricated by powder metallurgy were improved. Pressure-less infiltration experiments were conducted to fabricate composites by casting. The results demonstrated that the wettability and infiltration were dramatically improved by the aluminum coating layer on CNFs. The aluminum coating formed by the in situ CVD technique was proved to be effective for the fabrication of CNF-reinforced aluminum matrix composites.

  20. A Fundamental Study of a New Fabrication Technique for Fiber Reinforced Aluminum Matrix Composites.

    DTIC Science & Technology

    1980-04-20

    addition of discontinuous fibers to partially solid slurries and completely liquid matrices was investigated. In the first phase of the program...produceg y the slurry process. D 1473 em-fOm OF v Nov s is OBSOLETE SECURITY CLASSIFICATION OF THIS PAGE (Ohm Date Entered) ~/ CURITV CLASSIFICATION OF...TABLE OF CONTENTS Page I. INTRODUCTION. .. .. .... ...... . .... ..... .... II. FABRICATION USING METAL SLURRIE -INTERFACE INTERACTIONS .. .. ... 2 IlI

  1. Alumina-Reinforced Zirconia Composites

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Bansal, Narottam P.

    2003-01-01

    Alumina-reinforced zirconia composites, used as electrolyte materials for solid oxide fuel cells, were fabricated by hot pressing 10 mol percent yttria-stabilized zirconia (10-YSZ) reinforced with two different forms of alumina particulates and platelets each containing 0 to 30 mol percent alumina. Major mechanical and physical properties of both particulate and platelet composites including flexure strength, fracture toughness, slow crack growth, elastic modulus, density, Vickers microhardness, thermal conductivity, and microstructures were determined as a function of alumina content either at 25 C or at both 25 and 1000 C. Flexure strength and fracture toughness at 1000 C were maximized with 30 particulate and 30 mol percent platelet composites, respectively, while resistance to slow crack growth at 1000 C in air was greater for 30 mol percent platelet composite than for 30 mol percent particulate composites.

  2. Effect of fiber surface on flexural strength in carbon fabric reinforced epoxy composites

    NASA Astrophysics Data System (ADS)

    Brocks, Thatiane; Cioffi, Maria Odila Hilário; Voorwald, Herman Jacobus Cornelis

    2013-06-01

    The effect of carbon fiber surface characteristics on flexural properties of structural composites is studied in this work. Two types of intermediate modulus carbon fibers were used: T800HB and IM7. Results revealed that higher mechanical properties are linked with higher interfacial adhesion. Morphologies and chemical compositions of commercial carbon fibers (CF) were characterized by Fourier Transformed Infra Red (FTIR) and Scanning Electronic Microscopy (SEM). Comparing the results, the T800HB apparently has more roughness, since the IM7 seems to be recovered for a polymeric film. On other hand, the IM7 one shows higher interactivity with epoxy resin system Cycom 890 RTM. Composites produced with Resin Transfer Molding (RTM) were tested on a flexural trial. Interfacial adhesion difference was showed with SEM and Dynamic Mechanical Analyses (DMA), justifying the higher flexural behavior of composites made with IM7 fibers.

  3. Carbon nanofiber reinforced aluminum matrix composite fabricated by combined process of spark plasma sintering and hot extrusion.

    PubMed

    Kwon, Hansang; Kurita, Hiroki; Leparoux, Marc; Kawasaki, Akira

    2011-05-01

    Spark plasma sintering and hot extrusion processes have been employed for fabricating carbon nanofiber (CNF)-aluminum (Al) matrix bulk materials. The Al powder and the CNFs were mixed in a mixing medium of natural rubber. The CNFs were well dispersed onto the Al particles. After removal of the natural rubber, the Al-CNF mixture powders were highly densified. From the microstructural viewpoint, the composite materials were observed by optical, field-emission scanning electron, and high-resolution transmission electron microscopies. The CNFs were found to be located on every grain boundary and aligned with the extrusion direction of the Al-CNF bulk materials. Some Al carbides (Al4C3) were also observed at the surface of the CNFs. This carbide was created by a reaction between the Al and the disordered CNF. The CNFs and the formation of Al4C3 play an important role in the enhancement of the mechanical properties of the Al-CNF bulk material. The CNFs can also be used for engineering reinforcement of other matrix materials such as ceramics, polymers and more complex matrices.

  4. Fabrication and mechanical properties of multiwalled carbon nanotube/nanonickel reinforced epoxy resin composites

    NASA Astrophysics Data System (ADS)

    Zhang, Xiwen; Zhao, Dongyu; Luan, Dongxue; Bi, Changlong

    2016-12-01

    Nanonickel is supported on the surface of the multiwalled carbon nanotubes (MWCNTs), forming the multiwalled carbon nanotubes/nanonickel composites (MWCNTs/Ni). By using the emulsifying machine dispersing MWCNTs/Ni evenly among epoxy resin, which is prepared into epoxy resin/multiwalled carbon nanotubes/nanonickel (EP/MWCNTs/Ni) composite materials. Additionally, the observed strong interfacial interaction between MWCNTs and the epoxy resin matrix is responsible for the enhanced mechanical properties based on the analysis from scanning electron microscope. Experimental results based on the analysis from dynamic mechanical analysis (DMA) indicate a significant improvement in the glass transition temperature (Tg) by around 20 °C upon the addition of 1.5 wt% MWCNTs/Ni to the epoxy matrix. The tensile strength and the impact strength of the composites can improve around 64.8 and 176.7% compared with that of cured pure epoxy and improve with increasing MWCNTs/Ni content up to 1.3 wt%. Finally, the excellent mechanics capability of EP/MWCNTs/Ni nanocomposites will provide enormous opportunities for aerospace applications where conductive adhesive or high-performance polymer materials are necessary.

  5. Focused ion beam preparation techniques dedicated for the fabrication of TEM lamellae of fibre-reinforced composites.

    PubMed

    Mucha, Herbert; Kato, Takeharu; Arai, Shigeo; Saka, Hiroyasu; Kuroda, Kotaro; Wielage, Bernhard

    2005-01-01

    Two Focused Ion Beam based transmission electron microscopy (TEM) thin film preparation techniques are introduced. One is dedicated to the preparation of single fibres, the other to fibre/matrix interfaces of fibre reinforced composites. Due to their thin film quality, reliability and predictable processing times both techniques are suited for routine applications in material science like TEM studies of fibre microtextures and fibre/matrix interfaces. Exemplarily they are applied to Carbon Fibres and Carbon Fibre reinforced Carbon Matrix Composites (C/C). The achieved preparation standard in both cases is substantiated by TEM investigations.

  6. Using In situ Dynamic Cultures to Rapidly Biofabricate Fabric-Reinforced Composites of Chitosan/Bacterial Nanocellulose for Antibacterial Wound Dressings

    PubMed Central

    Zhang, Peng; Chen, Lin; Zhang, Qingsong; Hong, Feng F.

    2016-01-01

    Bacterial nano-cellulose (BNC) is considered to possess incredible potential in biomedical applications due to its innate unrivaled nano-fibrillar structure and versatile properties. However, its use is largely restricted by inefficient production and by insufficient strength when it is in a highly swollen state. In this study, a fabric skeleton reinforced chitosan (CS)/BNC hydrogel with high mechanical reliability and antibacterial activity was fabricated by using an efficient dynamic culture that could reserve the nano-fibrillar structure. By adding CS in culture media to 0.25–0.75% (w/v) during bacterial cultivation, the CS/BNC composite hydrogel was biosynthesized in situ on a rotating drum composed of fabrics. With the proposed method, BNC biosynthesis became less sensitive to the adverse antibacterial effects of CS and the production time of the composite hydrogel with desirable thickness could be halved from 10 to 5 days as compared to the conventional static cultures. Although, its concentration was low in the medium, CS accounted for more than 38% of the CS/BNC dry weight. FE-SEM observation confirmed conservation of the nano-fibrillar networks and covering of CS on BNC. ATR-FTIR showed a decrease in the degree of intra-molecular hydrogen bonding and water absorption capacity was improved after compositing with CS. The fabric-reinforced CS/BNC composite exhibited bacteriostatic properties against Escherichia coli and Staphylococcus aureus and significantly improved mechanical properties as compared to the BNC sheets from static culture. In summary, the fabric-reinforced CS/BNC composite constitutes a desired candidate for advanced wound dressings. From another perspective, coating of BNC or CS/BNC could upgrade the conventional wound dressings made of cotton gauze to reduce pain during wound healing, especially for burn patients. PMID:26973634

  7. Microstructural characterization of fiber-reinforced composites

    SciTech Connect

    Summerscales, J.

    1998-12-31

    In the past 50 years, great progress has been made in developing artificial fiber-reinforced composite materials, generally using filaments with microscopic diameters. An array of reinforcement forms can be used in commercial applications--with the microstructure being a critical factor in realizing the required properties in a material. This book comprehensively examines the application of advanced microstructural characterization techniques to fiber-reinforced composites. Its contents include: (1) flexible textile composite microstructure; (2) 3-D confocal microscopy of glass fiber-reinforced composites; (3) geometric modeling of yarn and fiber assemblies; (4) characterization of yarn shape in woven fabric composites; (5) quantitative microstructural analysis for continuous fiber composites; (6) electron microscopy of polymer composites; (7) micromechanics of reinforcement using laser raman spectroscopy; and (8) acoustic microscopy of ceramic fiber composites.

  8. Effects of Post-Fabrication Processing on the Tensile Properties of Centrifugally Cast SiC Particulate Reinforced Aluminum Composites

    DTIC Science & Technology

    1993-09-01

    number) A centrifugally cast A356 aluminum -matrix composite reinforced with silicon carbide (SiC) particles was themo-mechanically processed by rolling and...Advisor Alan G. Fox, Second Reader Matthewn Department of Mechanical Engineering ii ABSTRACT A centrifugally cast A356 aluminum -matrix composite...used in this research, was commercial grade A356 Aluminum alloy. The material was supplied by Naval Surface Warefare Center, White Oak. The material

  9. Post-failure Analysis and Fractography of In-plane Tension-Tested Tufted Carbon Fabric-Reinforced Epoxy Composite Laminates

    NASA Astrophysics Data System (ADS)

    Masa, Suresh Kumar; Mallya, Ambresha Basappa; Dhanapal, Karuppanan; Ramachandra, Ranganath Vemulapad; Kishore

    2015-04-01

    Tufted and plain unidirectional carbon fabric-reinforced epoxy composite laminates were fabricated by vacuum-enhanced resin infusion technology and subjected to in-plane tensile tests with a view to study the changes in mechanical properties and failure responses. Owing to the presence of tufts in the laminates, both the tensile strength and modulus decrease by ~38 and ~20%, respectively, vis- à- vis the values recorded for plain composites. The fracture features point to the fact that though both the composites fail in brittle manner, they, however, exhibit differing fiber pull out lengths. Further, it was noticed that for the tufted ones, crack originates in the vicinity of tuft thread, spreads through the composite in a brittle manner, and results in a display of shorter fiber pull out lengths. These observations and other results are discussed in this paper.

  10. Self reinforcing polymer composites

    SciTech Connect

    Kenig, S.

    1993-12-31

    In the advent of liquid crystalline polymers (LCPs), self reinforcing polymer composites comprising a polymer matrix and an LCP reinforcement, have become a reality. The so called self reinforcement is due to the LCPs orientability characteristics resulting from their rigid molecular backbone and anisotropy structure in the fluid state. Orientation development takes place during melt processing of the LCP composite blends where shear as well as elongational flows occur prior to consolidation to the solid state. By proper flow control anisotropy develops and in-situ composites are obtained. Polymer composites comprising self-reinforcement by LCPs during processing induced flow, were analyzed and studied with respect to their orientation development and resultant mechanical properties. The analysis commenced with the hydrodynamics of immiscible fluids in shear and elongational flows. Based on the analysis, orientation and morphology development in capillary extrusion was studied, using a variety of thermoplastic polymer matrices like amorphous and crystalline polyamides, polycarbonate and polyester in conjunction of a naphthalene based thermotropic LCP. Based on the flow-morphology relationship the amorphous polyamide/LCP composite was further investigated as it exhibited enhanced properties. Laminated composites based on LCP/amorphous polyamide were developed composed of unidirectional extruded and drawn sheets that were subsequently compression molded. Unidirectional, +45/{minus}45 and quasi-isotropic laminates were prepared and analyzed as to their microstructure and mechanical properties.

  11. Alloying Behavior and Properties of Al-Based Composites Reinforced with Al85Fe15 Metallic Glass Particles Fabricated by Mechanical Alloying and Hot Pressing Consolidation

    NASA Astrophysics Data System (ADS)

    Zhang, Lanxiang; Yang, LiKun; Leng, Jinfeng; Wang, Tongyang; Wang, Yan

    2017-04-01

    In this study, Al85Fe15 metallic glass particles with high onset crystallization temperature (1209 K) were synthesized by a mechanical alloying method. High-quality 6061Al-based composites reinforced with Al85Fe15 metallic glass particles were fabricated by a vacuum hot-pressing sintering technique. The glass particles with flake-like shape are distributed uniformly in the Al matrix. The bulk composites possess high relative density, excellent hardness and strength. The microhardness values of the Al-based bulk composites with the additions of 20 vol.% and 30 vol.% Al85Fe15 particles are 204 MPa and 248 MPa, respectively, which are much higher than that of 6061Al (61 MPa). The compressive yield strength of the 30 vol.% glass-reinforced composite is 478 MPa, which is enhanced by 273% compared with 6061Al. The amorphous characteristic and homogeneous dispersion of glass particles account for the excellent mechanical properties of the Al-based composites. In addition, the corrosion behavior of Al-based composites in a seawater solution has been investigated by electrochemical polarization measurements. Compared to 6061Al, the 30 vol.% glass-reinforced composite shows the lower corrosion/passive current density and larger passive region, indicating the greatly enhanced corrosion resistance.

  12. Alloying Behavior and Properties of Al-Based Composites Reinforced with Al85Fe15 Metallic Glass Particles Fabricated by Mechanical Alloying and Hot Pressing Consolidation

    NASA Astrophysics Data System (ADS)

    Zhang, Lanxiang; Yang, LiKun; Leng, Jinfeng; Wang, Tongyang; Wang, Yan

    2017-01-01

    In this study, Al85Fe15 metallic glass particles with high onset crystallization temperature (1209 K) were synthesized by a mechanical alloying method. High-quality 6061Al-based composites reinforced with Al85Fe15 metallic glass particles were fabricated by a vacuum hot-pressing sintering technique. The glass particles with flake-like shape are distributed uniformly in the Al matrix. The bulk composites possess high relative density, excellent hardness and strength. The microhardness values of the Al-based bulk composites with the additions of 20 vol.% and 30 vol.% Al85Fe15 particles are 204 MPa and 248 MPa, respectively, which are much higher than that of 6061Al (61 MPa). The compressive yield strength of the 30 vol.% glass-reinforced composite is 478 MPa, which is enhanced by 273% compared with 6061Al. The amorphous characteristic and homogeneous dispersion of glass particles account for the excellent mechanical properties of the Al-based composites. In addition, the corrosion behavior of Al-based composites in a seawater solution has been investigated by electrochemical polarization measurements. Compared to 6061Al, the 30 vol.% glass-reinforced composite shows the lower corrosion/passive current density and larger passive region, indicating the greatly enhanced corrosion resistance.

  13. Kevlar reinforced neoprene composites

    NASA Technical Reports Server (NTRS)

    Penn, B. G.; Daniels, J. G.; White, W. T.; Thompson, L. M.; Clemons, L. M.

    1985-01-01

    Kevlar/neoprene composites were prepared by two techniques. One method involved the fabrication of a composite from a rubber prepreg prepared by coating Kevlar with viscous neoprene solution and then allowing the solvent to evaporate (solution impregnation technique). The second method involved heating a stack of Kevlar/neoprene sheets at a temperature sufficient to cause polymer flow (melt flow technique). There was no significant difference in the breaking strength and percent elongation for samples obtained by the two methods; however the shear strength obtained for samples fabricated by the solution impregnation technique (275 psi) was significantly higher than that found for the melt flow fabricated samples (110 psi).

  14. Kevlar reinforced neoprene composites

    NASA Technical Reports Server (NTRS)

    Penn, B. G.; Daniels, J. G.; White, W. T.; Thompson, L. M.; Clemons, L. M.

    1985-01-01

    Kevlar/neoprene composites were prepared by two techniques. One method involved the fabrication of a composite from a rubber prepreg prepared by coating Kevlar with viscous neoprene solution and then allowing the solvent to evaporate (solution impregnation technique). The second method involved heating a stack of Kevlar/neoprene sheets at a temperature sufficient to cause polymer flow (melt flow technique). There was no significant difference in the breaking strength and percent elongation for samples obtained by the two methods; however the shear strength obtained for samples fabricated by the solution impregnation technique (275 psi) was significantly higher than that found for the melt flow fabricated samples (110 psi).

  15. Comparison of Graphite Fabric Reinforced PMR-15 and Avimid N Composites After Long Term Isothermal Aging at Various Temperatures

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; McCorkle, Linda; Ingrahm, Linda

    1998-01-01

    Extensive effort is currently being expended to demonstrate the feasibility of using high-performance, polymer-matrix composites as engine structural materials over the expected operating lifetime of the aircraft, which can extend from 18,000 to 30,000 hr. The goal is to develop light-weight, high-strength, and high-modulus materials for use in higher temperature sections of advanced 21 st century aircraft propulsion systems. To accomplish this goal, it is necessary to pursue the development of thermal and mechanical durability models for graphite-fiber-reinforced, polymer-matrix composites. Numerous investigations have been reported regarding the thermo-oxidative stability (TOS) of the polyimide PMR-15 (1-5). A significant amount of this work has been directed at edge and geometry effects, reinforcement fiber influences, and empirical modeling of high-temperature weight loss behavior. It is yet to be determined if the information obtained from the PMR-15 composite tests is applicable to other polyimide-matrix composites. The condensation-curing polymer Avimid N is another advanced composite material often considered for structural applications at high temperatures. Avimid N has better thermo-oxidative stability than PMR-15 (6), but the latter is more easily processed. The most comprehensive study of the thermo-oxidative stability of Avimid N neat resin and composites at 371 (infinity)C is found in Salin and Seferis (7). The purposes of the work described herein were to compare the thermal aging behavior of these two matrix polymers and to determine the reasons for and the consequences of the difference in thermal durability. These results might be of some use in improving future polymer development through the incorporation of the desirable characteristics of both polyimides.

  16. Mechanical and in vitro performance of apatite-wollastonite glass ceramic reinforced hydroxyapatite composite fabricated by 3D-printing.

    PubMed

    Suwanprateeb, J; Sanngam, R; Suvannapruk, W; Panyathanmaporn, T

    2009-06-01

    In situ hydroxyapatite/apatite-wollastonite glass ceramic composite was fabricated by a three dimensional printing (3DP) technique and characterized. It was found that the as-fabricated mean green strength of the composite was 1.27 MPa which was sufficient for general handling. After varying sintering temperatures (1050-1300 degrees C) and times (1-10 h), it was found that sintering at 1300 degrees C for 3 h gave the greatest flexural modulus and strength, 34.10 GPa and 76.82 MPa respectively. This was associated with a decrease in porosity and increase in densification ability of the composite resulting from liquid phase sintering. Bioactivity tested by soaking in simulated body fluid (SBF) and In Vitro toxicity studies showed that 3DP hydroxyapatite/A-W glass ceramic composite was non-toxic and bioactive. A new calcium phosphate layer was observed on the surface of the composite after soaking in SBF for only 1 day while osteoblast cells were able to attach and attain normal morphology on the surface of the composite.

  17. Design and fabrication of carbon fibers with needle-like nano-HA coating to reinforce granular nano-HA composites.

    PubMed

    Wang, Xudong; Zhao, Xueni; Zhang, Li; Wang, Wanying; Zhang, Jing; He, Fuzhen; Yang, Jianjun

    2017-08-01

    Carbon fibers (CFs) with needle-like nano-hydroxyapatite (nHA) coating were first used as reinforcing materials named nHA-CFs to improve the mechanical properties of pure HA. A powder mixture containing nHA-CFs and granular nano-HA (gHA) was directly sintered by hot pressing at appropriate sintering pressure and temperature. A three-phase nHA-CFs/gHA composite was designed, fabricated, and used as an artificial bone. Results show that the bending strengths of the nHA-CFs/gHA composite are approximately 41.1% and 59.2% higher than those of CFs/gHA composite and pure HA, respectively. The possible reinforcing mechanism of nHA-CFs in the composite is also proposed at the end. When nHA-CFs are applied for preparation of nHA-CFs/gHA composites, the internal stress on its phase boundary with gHA matrix generated during cooling of sintered is significantly reduced due to the presence of the nHA coatings. It infers that nHA coatings on CFs might act as a bridge to control the forming of interfacial gaps between the gHA matrix and the CFs effectively. Our work provides additional insights into the feasibility of nHA-CFs/gHA composites as load-bearing implant materials in clinical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Boron Nitride Nanotubes-Reinforced Glass Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam; Hurst, Janet B.; Choi, Sung R.

    2005-01-01

    Boron nitride nanotubes of significant lengths were synthesized by reaction of boron with nitrogen. Barium calcium aluminosilicate glass composites reinforced with 4 weight percent of BN nanotubes were fabricated by hot pressing. Ambient-temperature flexure strength and fracture toughness of the glass-BN nanotube composites were determined. The strength and fracture toughness of the composite were higher by as much as 90 and 35 percent, respectively, than those of the unreinforced glass. Microscopic examination of the composite fracture surfaces showed pullout of the BN nanotubes. The preliminary results on the processing and improvement in mechanical properties of BN nanotube reinforced glass matrix composites are being reported here for the first time.

  19. Kevlar reinforced neoprene composites

    SciTech Connect

    Penn, B.G.; Daniels, J.G.; White, W.T.; Thompson, L.M.; Clemons, L.M.

    1985-04-01

    Kevlar/neoprene composites were prepared by two techniques. One method involved the fabrication of a composite from a rubber prepreg prepared by coating kevlar with viscous neoprene solution and then allowing the solvent to evaporate (solution impregnation technique). The second method involved heating a stack of kevlar/neoprene sheets at a temperature sufficient to cause polymer flow (melt flow technique). There was no significant difference in the breaking strength and percent elongation for samples obtained by the two methods; however the shear strength obtained for samples fabricated by the solution impregnation technique (275 psi) was significantly higher than that found for the melt flow fabricated samples (110 psi). 1 reference, 2 tables.

  20. Nanostructured composite reinforced material

    DOEpatents

    Seals, Roland D [Oak Ridge, TN; Ripley, Edward B [Knoxville, TN; Ludtka, Gerard M [Oak Ridge, TN

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  1. Long-term Isothermal Aging Effects on Weight Loss, Compression Properties, and Dimensions of T650-35 Fabric-reinforced PMR-15 Composites-data

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; Tsuji, Luis; Kamvouris, John; Roberts, Gary D.

    2003-01-01

    A cooperative program was conducted with the General Electric Aircraft Engines plant in Evendale, Ohio, to study the effects of long-term isothermal aging at elevated temperatures on compression and thermal durability properties of T650 35 fabric-reinforced PMR 15 composites. This degradation study was conducted over an approximate time period of 3 1/2 yr. The aging temperatures were 204, 260, 288, 316, and 343 C. Specimens of different dimensions were evaluated. Specimens with ratios of the cut edge to total surface area of 0.03 to 0.89 were fabricated and aged. The aged and unaged specimens were tested in compression as specified in Test Method for Compressive Properties of Rigid Plastics (ASTM D695M). Thickness changes, degraded surface layer growth, weight loss, and failure modes were monitored and recorded. All property changes were thickness dependent.

  2. Opportunities and challenges for textile reinforced composites

    NASA Astrophysics Data System (ADS)

    Pastore, Christopher M.

    2000-03-01

    For several decades researchers have been interested in textile processes for the production of composite reinforcement. These technologies have offered several promises: reduced fabrication costs, 3-D multiaxial reinforcement, and damage tolerance. Despite these advantages, textile composites have not reached the level of implementation of laminated composites. In this paper, the opportunities provided by textile reinforced composites and the challenges that limit their implementation will be discussed in detail. Textile composites refer to a family of processes: weaving, braiding, knitting, and hybrids thereof. The various families of textiles will be defined and the basics of fabric formation for each family will be detailed. In particular, the strengths and weaknesses of each manufacturing technique will be addressed to provide a view of the applicability of each technology. This will include some guidance on shape formation capability, property ranges, size limitations, and estimates of cost to produce. Potential applications for these materials will be presented. Among the limitations on the application of textile reinforced composites is the lack of adequate modeling capabilities for these materials. Textile composites have rather large unit cell structures and are highly inhomogeneous throughout their volumes. These features provide benefits in manufacturing, but require novel modeling techniques to correctly understand the mechanical behavior. A review of analytical techniques applied to textile composites will be presented along with a discussion of the benefits and weaknesses of each of these methods. The enabling technologies needed to further the implementation of textile composites in structural applications will be discussed.

  3. The fabrication and tribological behavior of epoxy composites modified by the three-dimensional polyurethane sponge reinforced with dopamine functionalized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Wang, Huaiyuan; Sun, Liyuan; Wang, Enqun; Zhu, Yixing; Zhu, Yanji

    2016-01-01

    Three-dimensional (3D) interpenetrating network structure epoxy composites were fabricated based on the modified carbon nanotube (CNT) reinforced flexible polyurethane (PU) sponge. CNTs were first functionalized with polydopamine (PDA) as revealed by TEM imaging, which is formed via the oxidative self-polymerization of dopamine. Then the functionalized CNTs (CNT-PDA) were successfully anchored on the skeleton surfaces of sponge, forming a continuous 3D carbon network. The interfacial interaction between modified PU sponge and epoxy (EP) matrix was significantly enhanced due to the covalent linkage of PDA. Improvement in the thermal stability of CNT-PDA/PU3D/EP composites was observed by TG analysis and related to the CNTs anchored on the skeleton of sponge. The tribological properties of pure EP, PU3D/EP and CNT-PDA/PU3D/EP composites were comparatively investigated in terms of different loads and velocities. Results demonstrated that CNT-PDA/PU3D/EP composites exhibited the best tribological performance owing to the strong interfacial interaction and the 3D carbon network structure. In particular, the wear resistance of CNT-PDA/PU3D/EP composites was 6.2 times and 3 times higher than those of pure EP and PU3D/EP composites under the applied load of 1.6 MPa, respectively.

  4. Develop and demonstrate manufacturing processes for fabricating graphite filament reinforced polymide (Gr/PI) composite structural elements

    NASA Technical Reports Server (NTRS)

    Chase, V. A.; Harrison, E. S.

    1985-01-01

    A study was conducted to assess the merits of using graphite/polyimide, NR-150B2 resin, for structural applications on advanced space launch vehicles. The program was divided into two phases: (1) Fabrication Process Development; and (2) Demonstration Components. The first phase of the program involved the selection of a graphite fiber, quality assurance of the NR-150B2 polyimide resin, and the quality assurance of the graphite/polyimide prepreg. In the second phase of the program, a limited number of components were fabricated before the NR-150B2 resin system was removed from the market by the supplier, Du Pont. The advancement of the NR-150B2 polyimide resin binder was found to vary significantly based on previous time and temperature history during the prepregging operation. Strength retention at 316C (600F) was found to be 50% that of room temperature strength. However, the composite would retain its initial strength after 200 hours exposure at 316C (600F). Basic chemistry studies are required for determining NR-150B2 resin binder quality assurance parameters. Graphite fibers are available that can withstand high temperature cure and postcure cycles.

  5. Micromechanics for particulate reinforced composites

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Goldberg, Robert K.; Mital, Subodh K.

    1996-01-01

    A set of micromechanics equations for the analysis of particulate reinforced composites is developed using the mechanics of materials approach. Simplified equations are used to compute homogenized or equivalent thermal and mechanical properties of particulate reinforced composites in terms of the properties of the constituent materials. The microstress equations are also presented here to decompose the applied stresses on the overall composite to the microstresses in the constituent materials. The properties of a 'generic' particulate composite as well as those of a particle reinforced metal matrix composite are predicted and compared with other theories as well as some experimental data. The micromechanics predictions are in excellent agreement with the measured values.

  6. Mechanical, physical and tribological characterization of nano-cellulose fibers reinforced bio-epoxy composites: An attempt to fabricate and scale the 'Green' composite.

    PubMed

    Barari, Bamdad; Omrani, Emad; Dorri Moghadam, Afsaneh; Menezes, Pradeep L; Pillai, Krishna M; Rohatgi, Pradeep K

    2016-08-20

    The development of bio-based composites is essential in order to protect the environment while enhancing energy efficiencies. In the present investigation, the plant-derived cellulose nano-fibers (CNFs)/bio-based epoxy composites were manufactured using the Liquid Composite Molding (LCM) process. More specifically, the CNFs with and without chemical modification were utilized in the composites. The curing kinetics of the prepared composites was studied using both the isothermal and dynamic Differential Scanning Calorimetry (DSC) methods. The microstructure as well as the mechanical and tribological properties were investigated on the cured composites in order to understand the structure-property correlations of the composites. The results indicated that the manufactured composites showed improved mechanical and tribological properties when compared to the pure epoxy samples. Furthermore, the chemically modified CNFs reinforced composites outperformed the untreated composites. The surface modification of the fibers improved the curing of the resin by reducing the activation energy, and led to an improvement in the mechanical properties. The CNFs/bio-based epoxy composites form uniform tribo-layer during sliding which minimizes the direct contact between surfaces, thus reducing both the friction and wear of the composites. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Fabrication of Nano-SiC Particulate Reinforced Mg-8Al-1Sn Composites by Powder Metallurgy Combined with Hot Extrusion

    NASA Astrophysics Data System (ADS)

    Li, Chuan-Peng; Wang, Zhi-Guo; Wang, Hui-Yuan; Zhu, Xian; Wu, Min; Jiang, Qi-Chuan

    2016-11-01

    Nano-SiC particulates (n-SiCp) reinforced Mg-8Al-1Sn (AT81) composites with different volume fractions (0, 0.25, 0.5 and 1.0 vol.%) were fabricated by powder metallurgy process (P/M) combined with hot extrusion. The mechanical properties of the composite increased as the n-SiCp content increased until the n-SiCp content exceeded 0.5 vol.%, at which point they began to decrease. For this reason, the 0.5 vol.% n-SiCp/AT81 composite was considered optimal. The 0.2% offset yield strength (YS), ultimate tensile strength (UTS) and elongation (ɛ) of 0.5 vol.% n-SiCp/AT81 composites increased from 175, 318 MPa and 4.5% to 239, 381 MPa and 8.3%, respectively, compared to AT81. Both, the strength and plasticity of the 0.5 vol.% n-SiCp/AT81 composites were improved as well. The improvement in mechanical properties can be attributed to the progressively refined matrix grain size, relatively uniform distribution of n-SiCP and the well-bonded interfaces between n-SiCp and the matrix.

  8. Analysis of Graphite-Reinforced Cementitious Composites

    NASA Technical Reports Server (NTRS)

    Vaughan, R. E.

    2002-01-01

    Strategically embedding graphite meshes in a compliant cementitious matrix produces a composite material with relatively high tension and compressive properties as compared to steel-reinforced structures fabricated from a standard concrete mix. Although these composite systems are somewhat similar, the methods used to analyze steel-reinforced composites often fail to characterize the behavior of their more advanced graphite-reinforced counterparts. This Technical Memorandum describes some of the analytical methods being developed to determine the deflections and stresses in graphite-reinforced cementitious composites. It is initially demonstrated that the standard transform section method fails to provide accurate results when the elastic moduli ratio exceeds 20. An alternate approach is formulated by using the rule of mixtures to determine a set of effective material properties for the composite. Tensile tests are conducted on composite samples to verify this approach. When the effective material properties are used to characterize the deflections of composite beams subjected to pure bending, an excellent agreement is obtained. Laminated composite plate theory is investigated as a means for analyzing even more complex composites, consisting of multiple graphite layers oriented in different directions. In this case, composite beams are analyzed using the laminated composite plate theory with material properties established from tensile tests. Then, finite element modeling is used to verify the results. Considering the complexity of the samples, a very good agreement is obtained.

  9. Interlocked fabric and laminated fabric Kevlar 49/epoxy composites

    SciTech Connect

    Guess, T.R.; Reedy, E.D. Jr.

    1988-01-01

    The mechanical behavior of a novel interlocked fabric reinforced Kevlar 49/epoxy composite has been measured and compared to those of a laminated Kevlar 49 fabric composite (which served as a reference material). Both composites were 5.0 mm thick, contained the same 50% in-plane fiber volume fraction and were fabricated in a similar manner using the same Dow DER 332 epoxy, Jeffamine T403-hardened resin system. The reference material (Material 1) was reinforced with seven plies of Dupont style 1033 Kevlar 49 fabric. A photomicrograph of a section polished parallel to one of the fiber directions is shown. The interlocked fabric was designed and woven for Sandia National Laboratories by Albany International Research Co., Dedham, MA. The main design criterion was to duplicate a sewn through-the-thickness fabric used in preliminary studies. The interlocked fabric composite (Material 2) contains roughly 4% by volume of through-the-thickness fiber reinforcement for the purpose of improving interlaminar strength. A photomicrograph of a section showing the warp-aligned binder yarns interlocking the six fabric plies together is shown. 2 refs., 8 figs.

  10. Cure Cycle Design Methodology for Fabricating Reactive Resin Matrix Fiber Reinforced Composites: A Protocol for Producing Void-free Quality Laminates

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung

    2014-01-01

    For the fabrication of resin matrix fiber reinforced composite laminates, a workable cure cycle (i.e., temperature and pressure profiles as a function of processing time) is needed and is critical for achieving void-free laminate consolidation. Design of such a cure cycle is not trivial, especially when dealing with reactive matrix resins. An empirical "trial and error" approach has been used as common practice in the composite industry. Such an approach is not only costly, but also ineffective at establishing the optimal processing conditions for a specific resin/fiber composite system. In this report, a rational "processing science" based approach is established, and a universal cure cycle design protocol is proposed. Following this protocol, a workable and optimal cure cycle can be readily and rationally designed for most reactive resin systems in a cost effective way. This design protocol has been validated through experimental studies of several reactive polyimide composites for a wide spectrum of usage that has been documented in the previous publications.

  11. 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.

  12. Bilayer oxidized regenerated cellulose/poly ε-caprolactone knitted fabric-reinforced composite for use as an artificial dural substitute.

    PubMed

    Suwanprateeb, Jintamai; Luangwattanawilai, Ticomporn; Theeranattapong, Thunyanun; Suvannapruk, Waraporn; Chumnanvej, Sorayouth; Hemstapat, Warinkarn

    2016-07-01

    A novel bilayer knitted fabric-reinforced composite for potentially being used as a dural substitute was developed by solution infiltration of oxidized regenerated cellulose knitted fabric (ORC) with poly ε-caprolactone (PCL) solution at various concentrations ranging 10-40 g/100 mL. It was found that the density of all formulations did not differ significantly and was lower than that of the human dura. Microstructure of the samples typically comprised a bilayer structure having a nonporous PCL layer on one side and the ORC/PCL composite layer on another side. Tensile modulus and strength of the samples initially decreased with increasing PCL solution concentration for up to 20 g/100 mL and re-increased again with further increasing PCL solution concentration. Strain at break of all formulations were not significantly different. Watertight test revealed that all composites could prevent leakage at the pressure within the normal range of intracranial pressure. In vitro degradation study revealed that the weight loss percentage and change in tensile properties of all samples displayed biphasic profile comprising an initially rapid decrease and followed by a gradual decrease with incubation times afterward. Micro and macro porous channels were observed to be in situ generated in the composite layer by ORC dissolution and PCL resorption during degradation while nonporous layer remained relatively unchanged. The degradation rate was found to decrease with increasing PCL solution concentration. In vitro biocompatibility using alamar blue assay on selected samples showed that fibroblasts could attach and proliferate well at all incubation periods.

  13. 3-D textile reinforcements in composite materials

    SciTech Connect

    Miravete, A.

    1999-11-01

    Laminated composite materials have been used in structural applications since the 1960s. However, their high cost and inability to accommodate fibers in the laminate`s thickness direction greatly reduce their damage tolerance and impact resistance. The second generation of materials--3-D textile reinforced composites--offers significant cost reduction, and by incorporating reinforcement in the thickness direction, dramatically increases damage tolerance and impact resistance. However, methods for predicting mechanical properties of 3-D textile reinforced composite materials tend to be more complex. These materials also have disadvantages--particularly in regard to crimps in the yarns--that require more research. Textile preforms, micro- and macromechanical modeling, manufacturing processes, and characterization all need further development. As researchers overcome these problems, this new generation of composites will emerge as a highly competitive family of materials. This book provides a state-of-the-art account of this promising technology. In it, top experts describe the manufacturing processes, highlight the advantages, identify the main applications, analyze methods for predicting mechanical properties, and detail various reinforcement strategies, including grid structure, knitted fabric composites, and the braiding technique. Armed with the information in this book, readers will be prepared to better exploit the advantages of 3-D textile reinforced composites, overcome its disadvantages, and contribute to the further development of the technology.

  14. Fabrication of an r-Al2Ti intermetallic matrix composite reinforced with α-Al2O3 ceramic by discontinuous mechanical milling for thermite reaction

    NASA Astrophysics Data System (ADS)

    Mosleh, A.; Ehteshamzadeh, M.; Taherzadeh Mousavian, R.

    2014-10-01

    In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite (IMC) reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling (DMM) instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks for γ-TiAl as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.

  15. Formability of tufted 3-dimensional composite reinforcement

    NASA Astrophysics Data System (ADS)

    Liu, Ling Shan; Wang, Peng; Legrand, Xavier; Soulat, Damien

    2016-10-01

    In the aerospace industry, more and more complex preform for composite parts are needed. Traditionally, laminated reinforcement is largely used as the method. The development of tufting technology has now advanced to a stage whereby it can be employed to produce the 3D textile composite reinforcements. Because the tufting technology is user-friendly, in this study, the tufting parameters (tufting density, tufting length, tufting yarn orientations…) are varied, in order to improve the understanding of formability of the tufted 3D fabric during manufacturing, in particular the influence of the tufting yarns, the present work is performed to analyse the preforming behaviours of tufted 3D reinforcement in the hemispherical stamping process. The preforming behaviours are also compared with the ones of the multilayered forming. Interply sliding and winkling phenomenon during forming are fully influenced by tufting yarns on the material draw-in, by the orientations of tufting yarn, …

  16. Fiber reinforced composite resin systems.

    PubMed

    Giordano, R

    2000-01-01

    The Targis/Vectris and Sculpture/FibreKor systems were devised to create a translucent maximally reinforced resin framework for fabrication of crowns, bridges, inlays, and onlays. These materials are esthetic, have translucency similar to castable glass-ceramics such as OPC and Empress, and have fits that are reported to be acceptable in clinical and laboratory trials. These restorations rely on proper bonding to the remaining tooth structure; therefore, careful attention to detail must be paid to this part of the procedure. Cementation procedures should involve silane treatment of the cleaned abraded internal restoration surface, application of bonding agent to the restoration as well as the etched/primed tooth, and finally use of a composite resin. Each manufacturer has a recommended system which has been tested for success with its resin system. These fiber reinforced resins are somewhat different than classical composites, so not all cementation systems will necessarily work with them. Polishing of the restoration can be accomplished using diamond or alumina impregnated rubber wheels followed by diamond paste. The glass fibers can pose a health risk. They are small enough to be inhaled and deposited in the lungs, resulting in a silicosis-type problem. Therefore, if fibers are exposed and ground on, it is extremely important to wear a mask. Also, the fibers can be a skin irritant, so gloves also should be worn. If the fibers become exposed intraorally, they can cause gingival inflammation and may attract plaque. The fibers should be covered with additional composite resin. If this cannot be accomplished, the restoration should be replaced. The bulk of these restorations are formed using a particulate filled resin, similar in structure to conventional composite resins. Therefore, concerns as to wear resistance, color stability, excessive expansion/contraction, and sensitivity remain until these materials are proven in long-term clinical trials. They do hold the

  17. Selection of polymer binders and fabrication of SiC fiber-reinforced reaction-bonded silicon nitride matrix composites

    NASA Technical Reports Server (NTRS)

    Haggerty, John S.; Lightfoot, A.; Sigalovsky, J.

    1993-01-01

    The topics discussed include the following: effects of solvent and polymer exposures on nitriding kinetics of high purity Si powders and on resulting phase distributions; effects of solvent and polymer exposures on Si Surface Chemistry; effects of solvent and polymeric exposures on nitriding kinetics; and fabrication of flexural test samples.

  18. Composite monolayer fabrication by an arc-spray process

    NASA Technical Reports Server (NTRS)

    Westfall, Leonard J.

    1988-01-01

    A single layer (monotape) technique for fabricating complex high-temperature tungsten-fiber-reinforced superalloy composites is proposed. The fabrication of sheets of arc-sprayed monotape 38 cm wide and 122 cm long has been demonstrated. Composites fabricated using the method are shown to have equal tensile strength and a cleaner matrix than composites fabricated from powder metal cloth monotapes, and the present technique is less expensive than the powder metal fabrication techniques.

  19. Nanocellulose reinforcement of Transparent Composites

    Treesearch

    Joshua Steele; Hong Dong; James F. Snyder; Josh A. Orlicki; Richard S. Reiner; Alan W. Rudie

    2012-01-01

    In this work, we evaluate the impact of nanocellulose reinforcement on transparent composite properties. Due to the small diameter, high modulus, and high strength of cellulose nanocrystals, transparent composites that utilize these materials should show improvement in bulk mechanical performances without a corresponding reduction in optical properties. In this study...

  20. Weaving multi-layer fabrics for reinforcement of engineering components

    NASA Technical Reports Server (NTRS)

    Hill, B. J.; Mcilhagger, R.; Mclaughlin, P.

    1993-01-01

    The performance of interlinked, multi-layer fabrics and near net shape preforms for engineering applications, woven on a 48 shaft dobby loom using glass, aramid, and carbon continuous filament yarns is assessed. The interlinking was formed using the warp yarns. Two basic types of structure were used. The first used a single warp beam and hence each of the warp yarns followed a similar path to form four layer interlinked reinforcements and preforms. In the second two warp beams were used, one for the interlinking yarns which pass from the top to the bottom layer through-the-thickness of the fabric and vice versa, and the other to provide 'straight' yarns in the body of the structure to carry the axial loading. Fabrics up to 15mm in thickness were constructed with varying amounts of through-the-thickness reinforcement. Tapered T and I sections were also woven, with the shaping produced by progressive removal of ends during construction. These fabrics and preforms were impregnated with resin and cured to form composite samples for testing. Using these two basic types of construction, the influence of reinforcement construction and the proportion and type of interlinking yarn on the performance of the composite was assessed.

  1. A Method for Out-of-autoclave Fabrication of High Fiber Volume Fraction Fiber Reinforced Polymer Composites

    DTIC Science & Technology

    2012-07-01

    Infusion Processes Such as VARTM , VAP, and Compression RTM . SAMPE Proceedings, 38 th ISTC, Texas, 2006. 21. Li, W.; Krehl, J.; Gillespie, J.; Heider...increasing the fiber-volume fraction by vacuum-assisted resin transfer molding ( VARTM ) in order to produce composite structures with aerospace-grade...processed composites. Using a combination of viscosity control, ARL- based VARTM techniques, and a pressure control system, we increased the fiber-volume

  2. Fiber reinforced PMR polyimide composites

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    Commercially obtained PMR-15 polyimide prepregs with S-glass and graphite fiber reinforcements were evaluated along with in-house prepared glass and graphite cloth PMR 2 materials. A novel autoclave approach was conceived and used to demonstrate that both the PMR systems respond to 1.4 MPa (200 psi) autoclave pressures to produce void free composites equivalent to die molded laminates. Isothermal gravimetric analysis and subsequent mechanical property tests indicated that the PMR 2 system was significantly superior in thermo-oxidative stability, and that S-glass reinforcements may contribute to the accelerated degradation of composites at 316 C (600 F) when compared to graphite fiber reinforced composites. Fully reversed bending fatigue experiments were conducted with a type of fixture unused for organic matrix composites. These studies indicated that the graphite fiber composites were clearly superior in fatigue resistance to the glass fiber reinforced material and that PMR matrix composite systems yield performance of the same order as composite materials employing other families of matrices.

  3. Fabrication of Al matrix composite reinforced with submicrometer-sized Al2O3 particles formed by combustion reaction between HEMM Al and V2O5 composite particles during sintering

    NASA Astrophysics Data System (ADS)

    Woo, Kee Do; Kim, Jae Hwang; Kwon, Eui Pyo; Moon, Min Seok; Lee, Hyun Bom; Sato, Tatsuo; Liu, Zhiguang

    2010-04-01

    To fabricate an Al-V matrix composite reinforced with submicron-sized Al2O3 and AlxVy (Al3V, Al10V) phases, high energy mechanical milling (HEMM) and sintering were employed. By increasing the milling time, the size of mechanically milled powder was significantly reduced. In this study, the average powder size of 59 μm for Al, and 178 μm for V2O5 decreased with the formation of a new product, Al-Al2O3-AlxVy, with a size range from 1.3 μm to 2.6 μm formed by the in-situ combustion reaction during sintering of HEM milled Al and V2O5 composite powders. The in-situ reaction between Al and V2O5 during the HEMM and sintering transformed the Al2O3 and AlxVy (Al3V, Al10V) phases. Most of the reduced V reacted with excess the Al to form AlxVy (Al3V, Al10V) with very little V dissolved into Al matrix. By increasing the milling time and weight percentage of V2O5, the hardness of the Al-Al2O3-AlxVy composite sintered at 1173 K increased. The composite fabricated with the HEMM Al-20wt.%V2O5 composite powder and sintering at 1173 K for 2 h had the highest hardness.

  4. Mechanical response of composite materials with through-the-thickness reinforcement

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Dickinson, Larry C.

    1992-01-01

    An experimental investigation was conducted to identify the key geometrical parameters and quantify their influence on the mechanical response of through-the-thickness (TTT) reinforced composite materials. Composite laminates with TTT reinforcement fibers were fabricated using different TTT reinforcement materials and reinforcement methods and laminates were also fabricated of similar construction but without TTT reinforcement fibers. Coupon specimens were machined from these laminates and were destructively tested. TTT reinforcement yarns enhance damage tolerance and improve interlaminar strength. Thick-layer composites with TTT reinforcement yarns have equal or superior mechanical properties to thin-layer composites without TTT reinforcement yarns. A significant potential exists for fabrication cost reduction by using thick-layer composites with TTT reinforcement yarns. Removal of the surface loop of the TTT reinforcement improves compression strength. Stitching provides somewhat higher mechanical properties than integral weaving.

  5. Fabrication and evaluation of thin layer PVDF composites using MWCNT reinforcement: Mechanical, electrical and enhanced electromagnetic interference shielding properties

    NASA Astrophysics Data System (ADS)

    Bhaskara Rao, B. V.; Kale, Nikita; Kothavale, B. S.; Kale, S. N.

    2016-06-01

    Radar X-band electromagnetic interference shielding (EMS) is one of the prime requirements for any air vehicle coating; with limitations on the balance between strength and thickness of the EMS material. Nanocomposite of multiwalled-carbon-nanotubes (MWCNT) has been homogeneously integrated (0 - 9 wt%) with polymer, poly (vinylidene fluoride, PVDF) to yield 300 micron film. The PVDF + 9 wt% MWCNT sample of density 1.41 g/cm3 show specific shielding effectiveness (SSE) of 17.7 dB/(g/cm3) (99.6% EMS), with maintained hardness and improved conductivity. With multilayer stacking (900 microns) of these films of density 1.37 g/cm3, the sample showed increase in SSE to 23.3 dB/(g/cm3) (99.93% EMS). Uniform dispersion of MWCNTs in the PVDF matrix gives rise to increased conductivity in the sample beyond 5 wt% MWCNT reinforcement. The results are correlated to the hardness, reflection loss, absorption loss, percolation threshold, permittivity and the conductivity data. An extremely thin film with maximum EMS property is hence proposed.

  6. Scalable Fabrication of Natural-Fiber Reinforced Composites with Electromagnetic Interference Shielding Properties by Incorporating Powdered Activated Carbon.

    PubMed

    Xia, Changlei; Zhang, Shifeng; Ren, Han; Shi, Sheldon Q; Zhang, Hualiang; Cai, Liping; Li, Jianzhang

    2015-12-25

    Kenaf fiber-polyester composites incorporated with powdered activated carbon (PAC) were prepared using the vacuum-assisted resin transfer molding (VARTM) process. The product demonstrates the electromagnetic interference (EMI) shielding function. The kenaf fibers were retted in a pressured reactor to remove the lignin and extractives in the fiber. The PAC was loaded into the freshly retted fibers in water. The PAC loading effectiveness was determined using the Brunauer-Emmett-Teller (BET) specific surface area analysis. A higher BET value was obtained with a higher PAC loading. The transmission energies of the composites were measured by exposing the samples to the irradiation of electromagnetic waves with a variable frequency from 8 GHz to 12 GHz. As the PAC content increased from 0% to 10.0%, 20.5% and 28.9%, the EMI shielding effectiveness increased from 41.4% to 76.0%, 87.9% and 93.0%, respectively. Additionally, the EMI absorption increased from 21.2% to 31.7%, 44.7% and 64.0%, respectively. The ratio of EMI absorption/shielding of the composite at 28.9% of PAC loading was increased significantly by 37.1% as compared with the control sample. It was indicated that the incorporation of PAC into the composites was very effective for absorbing electromagnetic waves, which resulted in a decrease in secondary electromagnetic pollution.

  7. Scalable Fabrication of Natural-Fiber Reinforced Composites with Electromagnetic Interference Shielding Properties by Incorporating Powdered Activated Carbon

    PubMed Central

    Xia, Changlei; Zhang, Shifeng; Ren, Han; Shi, Sheldon Q.; Zhang, Hualiang; Cai, Liping; Li, Jianzhang

    2015-01-01

    Kenaf fiber—polyester composites incorporated with powdered activated carbon (PAC) were prepared using the vacuum-assisted resin transfer molding (VARTM) process. The product demonstrates the electromagnetic interference (EMI) shielding function. The kenaf fibers were retted in a pressured reactor to remove the lignin and extractives in the fiber. The PAC was loaded into the freshly retted fibers in water. The PAC loading effectiveness was determined using the Brunauer-Emmett-Teller (BET) specific surface area analysis. A higher BET value was obtained with a higher PAC loading. The transmission energies of the composites were measured by exposing the samples to the irradiation of electromagnetic waves with a variable frequency from 8 GHz to 12 GHz. As the PAC content increased from 0% to 10.0%, 20.5% and 28.9%, the EMI shielding effectiveness increased from 41.4% to 76.0%, 87.9% and 93.0%, respectively. Additionally, the EMI absorption increased from 21.2% to 31.7%, 44.7% and 64.0%, respectively. The ratio of EMI absorption/shielding of the composite at 28.9% of PAC loading was increased significantly by 37.1% as compared with the control sample. It was indicated that the incorporation of PAC into the composites was very effective for absorbing electromagnetic waves, which resulted in a decrease in secondary electromagnetic pollution. PMID:28787808

  8. Fabrication of aluminum-carbon composites

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1973-01-01

    A screening, optimization, and evaluation program is reported of unidirectional carbon-aluminum composites. During the screening phase both large diameter monofilament and small diameter multifilament reinforcements were utilized to determine optimum precursor tape making and consolidation techniques. Difficulty was encountered in impregnating and consolidating the multifiber reinforcements. Large diameter monofilament reinforcement was found easier to fabricate into composites and was selected to carry into the optimization phase in which the hot pressing parameters were refined and the size of the fabricated panels was scaled up. After process optimization the mechanical properties of the carbon-aluminum composites were characterized in tension, stress-rupture and creep, mechanical fatigue, thermal fatigue, thermal aging, thermal expansion, and impact.

  9. 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.

  10. Fabrication and Evaluation of Graphite Fiber-Reinforced Polyimide Composite Tube Forms Using Modified Resin Transfer Molding

    NASA Technical Reports Server (NTRS)

    Exum, Daniel B.; Ilias, S.; Avva, V. S.; Sadler, Bob

    1997-01-01

    The techniques necessary for the fabrication of a complex three-dimensional tubular form using a PMR-type resin have been developed to allow for the construction of several tubes with good physical and mechanical properties. Employing established resin transfer molding practices, the relatively non-hazardous AMB-21 in acetone formulation was used to successfully impregnate four layers of AS4 braided graphite fiber preform previously loaded around an aluminum cylindrical core in an enclosed mold cavity. Using heat and vacuum, the solvent was evaporated to form a prepreg followed by a partial imidization and removal of condensation products. The aluminum core was replaced by a silicone rubber bladder and the cure cycle continued to the final stage of 550 F with a bladder internal pressure of 200 lbs/sq in while simultaneously applying a strong vacuum to the prepreg for removal of any additional imidization products. A combination of several modifications to the standard resin transfer molding methodology enabled the mold to 'breathe', allowing the imidization products a pathway for escape. AMB-21 resin was chosen because of the carcinogenic nature of the primary commercial polyimide PMR-15. The AMB-21 resin was formulated using commercially available monomers or monomer precursors and dissolved in a mixture of methyl alcohol and acetone. The viscosity of the resulting monomer solution was checked by use of a Brookfield rheometer and adjusted by adding acetone to an easily pumpable viscosity of about 600 cP. In addition, several types of chromatographic and thermal analyses were of the braids, and excess handling of the preforms broke some of the microscopic fibers, needlessly decreasing the strength of the finished part. In addition, three dimensional braided preforms with fibers along the length of the tube will be significantly stronger in tension than the braided preforms used in this study.

  11. The properties of 5-D braided reinforced organic silicon composites

    SciTech Connect

    Xiao, L.; Li, J.; Dong, F.

    1994-12-31

    A study of the mechanical properties of braided reinforced composites is presented. Three braided structures 1 * 1, 1 * 2, 1 * 3 braids with and without axially layed-in yarns have been adopted. It is found that the different braided structures greatly affect the tensile strength , flexural strength and modulus of braided fabric reinforced composites; 1 * 1 4-D braided composite has the highest tensile and flexural strengths. The fiber fraction volume and surface geometries of braids changed greatly corresponding to the braiding process chosen. By laying in non-braiding yarns in the longitudinal direction, the tensile, and flexural strengths of 5-D braided reinforced composite increase.

  12. Diamond-Dispersed Fiber-Reinforced Composite for Superior Friction and Wear Properties in Extreme Environments and Method for Fabricating the Same

    NASA Technical Reports Server (NTRS)

    Street, Kenneth (Inventor); Voronov, Oleg A (Inventor); Kear, Bernard H (Inventor)

    2017-01-01

    Systems, methods, and articles of manufacture related to composite materials are discussed herein. These materials can be based on a mixture of diamond particles with a matrix and fibers or fabrics. The matrix can be formed into the composite material through optional pressurization and via heat treatment. These materials display exceptionally low friction coefficient and superior wear resistance in extreme environments.

  13. Continuous fiber-reinforced titanium aluminide composites

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Brindley, P. K.; Froes, F. H.

    1991-01-01

    An account is given of the fabrication techniques, microstructural characteristics, and mechanical behavior of a lightweight, high service temperature SiC-reinforced alpha-2 Ti-14Al-21Nb intermetallic-matrix composite. Fabrication techniques under investigation to improve the low-temperature ductility and environmental resistance of this material system, while reducing manufacturing costs to competitive levels, encompass powder-cloth processing, foil-fiber-foil processing, and thermal-spray processing. Attention is given to composite microstructure problems associated with fiber distribution and fiber-matrix interfaces, as well as with mismatches of thermal-expansion coefficient; major improvements are noted to be required in tensile properties, thermal cycling effects, mechanical damage, creep, and environmental effects.

  14. Continuous fiber-reinforced titanium aluminide composites

    NASA Technical Reports Server (NTRS)

    Mackay, R. A.; Brindley, P. K.; Froes, F. H.

    1991-01-01

    An account is given of the fabrication techniques, microstructural characteristics, and mechanical behavior of a lightweight, high service temperature SiC-reinforced alpha-2 Ti-14Al-21Nb intermetallic-matrix composite. Fabrication techniques under investigation to improve the low-temperature ductility and environmental resistance of this material system, while reducing manufacturing costs to competitive levels, encompass powder-cloth processing, foil-fiber-foil processing, and thermal-spray processing. Attention is given to composite microstructure problems associated with fiber distribution and fiber-matrix interfaces, as well as with mismatches of thermal-expansion coefficient; major improvements are noted to be required in tensile properties, thermal cycling effects, mechanical damage, creep, and environmental effects.

  15. SiC Fiber-Reinforced Celsian Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    2003-01-01

    Celsian is a promising matrix material for fiber-reinforced composites for high temperature structural applications. Processing and fabrication of small diameter multifilament silicon carbide tow reinforced celsian matrix composites are described. Mechanical and microstructural properties of these composites at ambient and elevated temperatures are presented. Effects of high-temperature exposures in air on the mechanical behavior of these composites are also given. The composites show mechanical integrity up to 1100 C but degrade at higher temperatures in oxidizing atmospheres. A model has been proposed for the degradation of these composites in oxidizing atmospheres at high temperatures.

  16. Process for the fabrication of ceramic fiber reinforced titanium aluminide

    SciTech Connect

    Horsfall, I.; Cundy, S.J.

    1992-10-01

    This paper describes initial work on a novel process for the production of titanium aluminide matrix composites reinforced with short alumina fibers. The processing route involves an adaption of existing metal matrix composite (MMC) fabrication technology used to produce hybrid particulate/short fiber composites. A preform is produced which contains alumina fibers and titanium metal powder with a fiber content of around 10 percent by volume and approximately 50 percent porosity. This preform is then infiltrated with pure aluminum by a squeeze casting process to produce a fully dense composite of titanium powder and alumina fibers in a metallic aluminum matrix. The composite is then heat treated in a hot isostatic press to react the aluminum and titanium to produce a titanium aluminide matrix. 9 refs.

  17. 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

  18. Machining fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Komanduri, Ranga

    1993-04-01

    Compared to high tool wear and high costs of tooling of fiber-reinforced composites (FRCs), noncontact material-removal processes offer attractive alternative. Noncontact machining methods can also minimize dust, noise, and extensive plastic deformation and consequent heat generation associated with conventional machining of FRCs, espacially those with an epoxy matrix. The paper describes the principles involved in and the details of machining of FRCs by laser machining, water jet-cutting and abrasive water jet-cutting, and electrical discharge machining of composites, as well as the limitations of each method.

  19. Fusion bonding of carbon fabric reinforced polyphenylene sulphide

    NASA Astrophysics Data System (ADS)

    de Baere, I.; van Paepegem, W.; Degrieck, J.

    2010-06-01

    In recent years, there is a growing interest in joining techniques for thermoplastic composites as an alternative to adhesive bonding. In this manuscript, a fusion bonding process called hot-tool welding is investigated for this purpose and the used material is a carbon fabric reinforced polyphenylene sulphide. The quality of the welds is experimentally assessed using a short three-point bending setup, which has an interesting distribution of interlaminar shear stresses. It can be concluded that although the hot-tool welding process shows high short-beam strengths, it has some drawbacks. Therefore, a design of an infrared welding setup is presented.

  20. 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.

  1. 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.

  2. 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.

  3. Peptide Nanotube Reinforced Polymers: A System for Tunable, Composite Materials

    DTIC Science & Technology

    2015-11-30

    mechanical reinforcement of polymeric materials used in the fabrication of implantable medical devices. Our results show that the high aspect ratio... polymers like poly-D,L-lactic acid (PDLLA), a common polymer used in resorbable load bearing 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13...Approved for Public Release; Distribution Unlimited Final Report: Peptide nanotube reinforced polymers : A system for tunable, composite materials The

  4. Preliminary evaluation of fiber composite reinforcement of truck frame rails

    NASA Technical Reports Server (NTRS)

    Faddoul, J. R.

    1977-01-01

    The use of graphite fiber/resin matrix composite to effectively reinforce a standard steel truck frame rail is studied. A preliminary design was made and it was determined that the reinforcement weight could be reduced by a factor of 10 when compared to a steel reinforcement. A section of a 1/3 scale reinforced rail was fabricated to demonstrate low cost manufacturing techniques. The scale rail section was then tested and increased stiffness was confirmed. No evidence of composite fatigue was found after 500,000 cycles to a fiber stress of 34,000 psi. The test specimen failed in bending in a static test at a load 50 percent greater than that predicted for a non-reinforced rail.

  5. FIBER-REINFORCED METALLIC COMPOSITE MATERIALS.

    DTIC Science & Technology

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

  6. Development of Flax Fibre based Textile Reinforcements for Composite Applications

    NASA Astrophysics Data System (ADS)

    Goutianos, S.; Peijs, T.; Nystrom, B.; Skrifvars, M.

    2006-07-01

    Most developments in the area of natural fibre reinforced composites have focused on random discontinuous fibre composite systems. The development of continuous fibre reinforced composites is, however, essential for manufacturing materials, which can be used in load-bearing/structural applications. The current work aims to develop high-performance natural fibre composite systems for structural applications using continuous textile reinforcements like UD-tapes or woven fabrics. One of the main problems in this case is the optimisation of the yarn to be used to manufacture the textile reinforcement. Low twisted yarns display a very low strength when tested dry in air and therefore they cannot be used in processes such as pultrusion or textile manufacturing routes. On the other hand, by increasing the level of twist, a degradation of the mechanical properties is observed in impregnated yarns (e.g., unidirectional composites) similar to off-axis composites. Therefore, an optimum twist should be used to balance processability and mechanical properties. Subsequently, different types of fabrics (i.e., biaxial plain weaves, unidirectional fabrics and non-crimp fabrics) were produced and evaluated as reinforcement in composites manufactured by well established manufacturing techniques such as hand lay-up, vacuum infusion, pultrusion and resin transfer moulding (RTM). Clearly, as expected, the developed materials cannot directly compete in terms of strength with glass fibre composites. However, they are clearly able to compete with these materials in terms of stiffness, especially if the low density of flax is taken into account. Their properties are however very favourable when compared with non-woven glass composites.

  7. A facile one-pot fabrication of polyphosphazene microsphere/carbon fiber hybrid reinforcement and its effect on the interfacial adhesion of epoxy composites

    NASA Astrophysics Data System (ADS)

    Chen, Xiang; Xu, Haibing; Liu, Dong; Yan, Chun; Zhu, Yingdan

    2017-07-01

    Introducing nanoscale reinforcements into the interface between carbon fiber (CF) and resin is an effective approach to improve the interfacial adhesion of CF composites. In this paper, a facile one-pot polymerization process provides a rapid and efficient method for preparing polyphosphazene microspheres/CF hybrid reinforcement using hexachlorocyclotriphosphazene (HCCP) and bis(4-hydroxyphenyl) sulfone (BPS) as monomers. By the in situ polymerization modification, HCCP and BPS were successfully cross-linked and deposited on the CF surface. Scanning electron microscope and atomic force microscopy images show that poly(cyclotriphosphazene-co-4,4‧-sulfonyldiphonel) microspheres were introduced onto the CF surfaces and the surface roughness of fibers is enhanced obviously. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirm that the polymerization between HCCP and BPS has been successfully carried out. The surface modification can significantly increase the fiber roughness, polarity, wettability and surface energy, thus improving the interfacial shear strength of CF/epoxy composites. Meanwhile, the single fiber tensile strength of CF also shows an increase after modification.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  9. Designing with figer-reinforced plastics (planar random composites)

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1982-01-01

    The use of composite mechanics to predict the hygrothermomechanical behavior of planar random composites (PRC) is reviewed and described. These composites are usually made from chopped fiber reinforced resins (thermoplastics or thermosets). The hygrothermomechanical behavior includes mechanical properties, physical properties, thermal properties, fracture toughness, creep and creep rupture. Properties are presented in graphical form with sample calculations to illustrate their use. Concepts such as directional reinforcement and strip hybrids are described. Typical data that can be used for preliminary design for various PRCs are included. Several resins and molding compounds used to make PRCs are described briefly. Pertinent references are cited that cover analysis and design methods, materials, data, fabrication procedures and applications.

  10. Laser-surface-alloyed carbon nanotubes reinforced hydroxyapatite composite coatings

    SciTech Connect

    Chen Yao; Gan Cuihua; Zhang Tainua; Yu Gang; Bai Pucun; Kaplan, Alexander

    2005-06-20

    Carbon-nanotube (CNT)-reinforced hydroxyapatite composite coatings have been fabricated by laser surface alloying. Microstructural observation using high-resolution transmission electron microscopy showed that a large amount of CNTs remained with their original tubular morphology, even though some CNTs reacted with titanium element in the substrate during laser irradiation. Additionally, measurements on the elastic modulus and hardness of the composite coatings indicated that the mechanical properties were affected by the amount of CNTs in the starting precursor materials. Therefore, CNT-reinforced hydroxyapatite composite is a promising coating material for high-load-bearing metal implants.

  11. Laser-surface-alloyed carbon nanotubes reinforced hydroxyapatite composite coatings

    NASA Astrophysics Data System (ADS)

    Chen, Yao; Gan, Cuihua; Zhang, Tainua; Yu, Gang; Bai, Pucun; Kaplan, Alexander

    2005-06-01

    Carbon-nanotube (CNT)-reinforced hydroxyapatite composite coatings have been fabricated by laser surface alloying. Microstructural observation using high-resolution transmission electron microscopy showed that a large amount of CNTs remained with their original tubular morphology, even though some CNTs reacted with titanium element in the substrate during laser irradiation. Additionally, measurements on the elastic modulus and hardness of the composite coatings indicated that the mechanical properties were affected by the amount of CNTs in the starting precursor materials. Therefore, CNT-reinforced hydroxyapatite composite is a promising coating material for high-load-bearing metal implants.

  12. Processing and characterization of redmud reinforced polypropylene composites

    NASA Astrophysics Data System (ADS)

    Shanmugavel, R.; Jayamani, M.; Nagarajan, R.; Irullappasamy, S.; Cardona, F.; Sultan, M. T. H.

    2016-10-01

    In this work, the redmud reinforced polypropylene composites were fabricated by compression molding setup. The effects of the redmud content on the mechanical, melting and crystalline behavior of the composites was investigated. The melting and crystalline behavior of the composites were investigated using Digital Scanning Calorimeter. The test results show that hardness of the composites increases with increasing redmud content while incorporation of redmud content decreases tensile and impact strength of the composites. It is determined that the addition of redmud on the polypropylene does not affect the crystalline behavior of the composites.

  13. Fabrication of graphite/polyimide composite structures.

    NASA Technical Reports Server (NTRS)

    Varlas, M.

    1972-01-01

    Selection of graphite/polyimide composite as a prime candidate for high-temperature structural applications involving long-duration temperature environments of 400 to 600 F. A variety of complex graphite/polyimide components has been fabricated, using a match-metal die approach developed for making fiber-reinforced resin composites. Parts produced include sections of a missile adapter skin flange, skin frame section, and I-beam and hat-section stringers, as well as unidirectional (0 deg) and plus or minus 45 deg oriented graphite/polyimide tubes in one-, two-, and six-inch diameters.

  14. Automated Fabrication Technologies for High Performance Polymer Composites

    NASA Technical Reports Server (NTRS)

    Shuart , M. J.; Johnston, N. J.; Dexter, H. B.; Marchello, J. M.; Grenoble, R. W.

    1998-01-01

    New fabrication technologies are being exploited for building high graphite-fiber-reinforced composite structure. Stitched fiber preforms and resin film infusion have been successfully demonstrated for large, composite wing structures. Other automatic processes being developed include automated placement of tacky, drapable epoxy towpreg, automated heated head placement of consolidated ribbon/tape, and vacuum-assisted resin transfer molding. These methods have the potential to yield low cost high performance structures by fabricating composite structures to net shape out-of-autoclave.

  15. Recent progress in NASA Langley textile reinforced composites program

    NASA Technical Reports Server (NTRS)

    Dexter, H. Benson; Harris, Charles E.; Johnston, Norman J.

    1992-01-01

    The NASA LaRC is conducting and sponsoring research to explore the benefits of textile reinforced composites for civil transport aircraft primary structures. The objective of this program is to develop and demonstrate the potential of affordable textile reinforced composite materials to meet design properties and damage tolerance requirements of advanced aircraft structural concepts. In addition to in-house research, the program was recently expanded to include major participation by the aircraft industry and aerospace textile companies. The major program elements include development of textile preforms, processing science, mechanics of materials, experimental characterization of materials, and development and evaluation of textile reinforced composite structural elements and subcomponents. The NASA Langley in-house focus is as follows: development of a science-based understanding of resin transfer molding (RTM), development of powder-coated towpreg processes, analysis methodology, and development of a performance database on textile reinforced composites. The focus of the textile industry participation is on development of multidirectional, damage-tolerant preforms, and the aircraft industry participation is in the areas of design, fabrication and testing of textile reinforced composite structural elements and subcomponents. Textile processes such as 3D weaving, 2D and 3D braiding, and knitting/stitching are being compared with conventional laminated tape processes for improved damage tolerance. Through-the-thickness reinforcements offer significant damage tolerance improvements. However, these gains must be weighed against potential loss in in-plane properties such as strength and stiffness. Analytical trade studies are underway to establish design guidelines for the application of textile material forms to meet specific loading requirements. Fabrication and testing of large structural components are required to establish the full potential of textile reinforced

  16. 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.

  17. Investigation on mechanical properties of basalt composite fabrics (experiment study)

    NASA Astrophysics Data System (ADS)

    Talebi Mazraehshahi, H.; Zamani, H.

    2010-06-01

    To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced and mechanical behaviors of this material investigated from view point of testing. For this study two type of fabric with different thickness used. Comparison between this composite reinforcement with popular reinforcement as carbon, glass, kevlar performed. To determine mechanical properties of epoxy based basalt fabric following test procedure performed : 1). Tensile testing according to ASTM D3039 in 0° and 90° direction to find ultimate strength in tension and shear, modulus of elasticity, elangation and ultimate strain. 2). Compression testing according to EN 2850 ultimate compression strength and maximum deformation under compression loading. 3). Shear testing according to ASTM D3518-94 to find in plane shear response of polymer matrix composites materials. 4). Predict flexural properties of sandwich construction which manufactured from basalt facing with PVC foam core according to ASTM C393-94. Material strength properties must be based on enough tests of material to meet the test procedure specifications [1]. For this reason six specimens were manufactured for testing and the tests were performed on them using an INSTRON machine model 5582. In the study, the effect of percent of resin in basalt reinforced composite was investigated. Also the weights of the ballast based composites with different percent of resin were measured with conventional composites. As the weight is an important parameter in aerospace industry when the designer wants to replace one material with

  18. 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.

  19. Translucency of glass-fibre-reinforced composite materials.

    PubMed

    Nakamura, T; Tanaka, H; Kawamura, Y; Wakabayashi, K

    2004-08-01

    summary The purpose of this study was to examine the translucency of glass-fibre-reinforced composite framework materials. Vectris and FibreKor, as well as an experimental material, were the glass-fibre-reinforced framework materials used. Targis, Sculpture and Estenia were the types of particulate filler composites veneered onto frameworks. Specimens were fabricated from each material, 0.5 and 1.0 mm thick. In addition, laminate specimens, 1.5 mm thick, were fabricated. The translucency of each specimen was evaluated by determining its contrast ratio. The laminate specimens were examined for colour differences. The experimental framework material was more translucent than the enamel composite when it was not coloured, and was nearly as translucent as the dentine composite when coloured. The commercial tooth-coloured framework materials were nearly as translucent as the dentine composite. It was found that it was possible to reproduce the same colour as the veneering dentine composite, when the framework thickness was 0.5 mm, except in the case of FibreKor. Within the limitations of this study, tooth-coloured, glass-fibre-reinforced framework materials are nearly as translucent as the veneering dentine composite, but these materials affect the colour of the prosthesis if the thickness of the framework material is increased beyond a certain point. Copyright 2004 Blackwell Publishing Ltd.

  20. Mechanical Properties of Nonwoven Reinforced Thermoplastic Polyurethane Composites

    PubMed Central

    Tausif, Muhammad; Pliakas, Achilles; O’Haire, Tom; Goswami, Parikshit; Russell, Stephen J.

    2017-01-01

    Reinforcement of flexible fibre reinforced plastic (FRP) composites with standard textile fibres is a potential low cost solution to less critical loading applications. The mechanical behaviour of FRPs based on mechanically bonded nonwoven preforms composed of either low or high modulus fibres in a thermoplastic polyurethane (TPU) matrix were compared following compression moulding. Nonwoven preform fibre compositions were selected from lyocell, polyethylene terephthalate (PET), polyamide (PA) as well as para-aramid fibres (polyphenylene terephthalamide; PPTA). Reinforcement with standard fibres manifold improved the tensile modulus and strength of the reinforced composites and the relationship between fibre, fabric and composite’s mechanical properties was studied. The linear density of fibres and the punch density, a key process variable used to consolidate the nonwoven preform, were varied to study the influence on resulting FRP mechanical properties. In summary, increasing the strength and degree of consolidation of nonwoven preforms did not translate to an increase in the strength of resulting fibre reinforced TPU-composites. The TPU composite strength was mainly dependent upon constituent fibre stress-strain behaviour and fibre segment orientation distribution. PMID:28772977

  1. Fiber reinforced composites orthodontic retainers.

    PubMed

    Lucchese, A; Manuelli, M; Bassani, L; Albertini, P; Matarese, G; Perillo, L; Gastaldi, G; Gherlone, E F

    2015-12-01

    Retention is the phase of orthodontic treatment that attempts to hold teeth in their corrected positions after orthodontic therapy is completed. The aim of this study was to consider fiber-reinforced composites (FRC) as a possible alternative to conventional multistranded stainless steel wire for retention through SEM analysis. Two different FRC orthodontic retainers were investigated, i.e. Everstick® (Stick Tech Ltd, Turku, Finland) (type A, 24 samples), with a diameter of 0.76 mm made of glass fibers and a Young's modulus of elasticity of 28 gpa, and Ribbond® (Ribbond, Inc., Seattle, Washington, WA, USA) (type B, 24 samples), with ultra high molecular weight and with an high Young's modulus of elasticity by polyethylene fibers cold treated with plasma gas. Six groups were created: control groups A1 and B1, composed by 8 type A and 8 type B samples without impregnation and only with fluid resin before curing; groups A2 and B2, composed respectively by 8 type A and 8 type B samples impregnated with fluid resin Heliobond for 6 seconds; groups A3 and B3, composed respectively by 8 type A and 8 type B samples impregnated with fluid resin Heliobond for 6 minutes before curing. Cross- and lengthwise SEM analysis of the sectioned samples made showed that fiber without impregnation with fluid resin, before curing, showed interwoven and straight directed cylindrical fibers. The SEM analysis denoted that the two types of fiber shows structural characteristics differing in dimension, number, diameter and orientation of FRC without a preliminary treatment through impregnation of the fibers with fluid resin. An impregnation time of 6 seconds could considerably reduced voids, crazes and microcracks of the fibers, making them more resistant to the other oral and bacterial agents. A larger time of impregnation (6 minutes), with fluid resin before hardening, further enhances the morphological characteristics of the FRC.

  2. Influence of fabrication on mechanical properties of SiC-whisker-reinforced alumina

    SciTech Connect

    DeArellano-Lopez, A.R.; Dominguez-Rodriguez, A. . Dept. Materia Condensada); Goretta, K.C.; Routbort, J.L. )

    1991-10-01

    Samples of SiC-whisker-reinforced Al{sub 2}O{sub 3} composites obtained from three different sources have been crept in compression at 1400{degrees}C using both constant load (CL) and constant strain rate (CSR). Macroscopic results indicate some difference in behavior due to fabrication. TEM is used to support this hypothesis. 10 refs., 3 figs.

  3. Load-bearing capacity of fiber reinforced fixed composite bridges.

    PubMed

    Göncü Başaran, Emine; Ayna, Emrah; Üçtaşli, Sadullah; Vallittu, Pekka K; Lassila, Lippo V J

    2013-01-01

    The aim of this study was to evaluate the reinforcing effect of differently oriented fibers on the load-bearing capacity of three-unit fixed dental prostheses (FDPs). Forty-eight composite FDPs were fabricated. Specimens were divided into eight groups (n = 6/group; codes 1-8). Groups 1 and 5 were plain restorative composites (Grandio and Z100) without fiber reinforcement, groups 2 and 6 were reinforced with a continuous unidirectional fiber substructure, groups 3 and 7 were reinforced with a continuous bidirectional fiber and groups 4 and 8 were reinforced with a continuous bidirectional fiber substructure and continuous unidirectional fiber. FDPs were polymerized incrementally with a handheld light curing unit for 40 s and statically loaded until final fracture. Kruskal-Wallis analysis revealed that all groups had significantly different load-bearing capacities. Group 4 showed the highest mean load-bearing capacity and Group 7 the lowest. The results of this study suggest that continuous unidirectional fiber increased the mechanical properties of composite FDPs and bidirectional reinforcement slowed crack propagation on abutments.

  4. Cost effective production techniques for continuous fiber reinforced ceramic matrix composites

    SciTech Connect

    Vogel, W.D.; Spelz, U.

    1995-09-01

    Cost effective techniques for fabrication of continuous fibre reinforced ceramic matrix composites like filament winding, prepreg technique and resin transfer moulding are reported. The advantages and disadvantages of the three different manufacture routes are given and examples are shown.

  5. 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

  6. Studies on natural fiber reinforced polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Patel, R. H.; Kapatel, P. M.; Machchhar, A. D.; Kapatel, Y. A.

    2016-05-01

    Natural fiber reinforced composites show increasing importance in day to days applications because of their low cost, lightweight, easy availability, non-toxicity, biodegradability and environment friendly nature. But these fibers are hydrophilic in nature. Thus they have very low reactivity and poor compatibility with polymers. To overcome these limitations chemical modifications of the fibers have been carried out. Therefore, in the present work jute fibers have chemically modified by treating with sodium hydroxide (NaOH) solutions. These treated jute fibers have been used to fabricate jute fiber reinforced epoxy composites. Mechanical properties like tensile strength, flexural strength and impact strength have been found out. Alkali treated composites show better properties compare to untreated composites.

  7. Fatigue behavior of SiC reinforced titanium composites

    NASA Technical Reports Server (NTRS)

    Bhatt, R. T.; Grimes, H. H.

    1979-01-01

    The low cycle axial fatigue properties of 25 and 44 fiber volume percent SiC/Ti(6Al-4V) composites were measured at room temperature and at 650 deg C. The S-N curves for the composites showed no anticipated improvement over bulk matrix behavior at room temperature. Although axial and transverse tensile strength results suggest a degradation in SiC fiber strength during composite fabrication, it appears that the poor fatigue life of the composites was caused by a reduced fatigue resistance of the reinforced Ti(6Al-4V) matrix. The reduced matrix behavior was due, to the presence of flawed and fractured fibers created near the specimen surfaces by preparation techniques and to the large residual tensile stresses that can exist in fiber reinforced matrices. The effects of fatigue testing at high temperature are discussed.

  8. Industry to Education Technical Transfer Program & Composite Materials. Composite Materials Course. Fabrication I Course. Fabrication II Course. Composite Materials Testing Course. Final Report.

    ERIC Educational Resources Information Center

    Massuda, Rachel

    These four reports provide details of projects to design and implement courses to be offered as requirements for the associate degree program in composites and reinforced plastics technology. The reports describe project activities that led to development of curricula for four courses: composite materials, composite materials fabrication I,…

  9. Bioinspired Composites with Spatial and Orientational Control of Reinforcement

    NASA Astrophysics Data System (ADS)

    Demiroers, Ahmet; Studart, Andre; Complex Materials Team

    Living organisms combine soft and hard components to fabricate composite materials with out-standing mechanical properties. The optimum design and assembly of the anisotropic components reinforce the material in specific directions against multidirectional external loads. Although nature does it quite readily, it is still a challenge for material scientists to control the orientation and position of the colloidal components in a matrix. Here, we use external electric and magnetic fields to achieve positional and orientational control over colloid-polymer composites to fabricate mechanically robust materials to capture some of the essential features of natural systems. We first investigated the assembly of spherical micron-sized colloids using dielectrophoresis, as these particles provided an easily accessible and instructive length scale for performing initial experiments. We used dielectrophoresis for spatial control of reinforcing anisotropic components and magnetic fields to provide control over the orientation of these reinforcing constituents. The obtained composites with different orientational and spatial reinforcement showed enhanced mechanical properties, such as wear resistance, which exhibits similarities to tooth enamel. SNSF Ambizione Grant PZ00P2_148040.

  10. Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application. Phase 2: summary report: Shear web component fabrication

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.; Smith, D. D.; Zimmerman, D. K.

    1973-01-01

    The fabrication of two shear web test elements and three large scale shear web test components are reported. In addition, the fabrication of test fixtures for the elements and components is described. The center-loaded beam test fixtures were configured to have a test side and a dummy or permanent side. The test fixtures were fabricated from standard extruded aluminum sections and plates and were designed to be reuseable.

  11. Carbon Fiber Reinforced Ceramic Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Shivakumar, Kunigal; Argade, Shyam

    2003-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Oshima, Akihiro; Udagawa, Akira; Tanaka, Shigeru

    2001-07-01

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

  13. Mechanical Behaviour of Alumina Silicon Carbide Reinforced Particulate Reinforced Metal Matrix Composite

    NASA Astrophysics Data System (ADS)

    Raghu Ram, K. S.; Sweanney Bandi, Sharon Rose; Sivarama Krishna, Ch.

    2017-08-01

    The present study was aimed at evaluating the effect of hardness and impact strength of Aluminum Al2O3SiC particulate reinforced Composites. These AMCs with multiple reinforcement (hybrid MMCs) are finding increased applications in aerospace, automobile, space, underwater and transportation applications. An effort is made to enhance the Hardness, flexural strength and Impact properties of AMCs by reinforcing Aluminum matrix with Varying Proportion of small particles of Al2O3SiC by stir casting method. Aluminum alloy matrix varying proportions of Al2O3SiC particulates were fabricated. The microstructure, hardness and impact strength properties of the fabricated AMCs were analyzed. The optical microstructure study revealed the homogeneous dispersion of Al2O3SiC particles in the matrix. Based on the results obtained from the Hardness and Impact of the metal matrix composites it is observed that, the hardness and impact strength increases with increase in the amount of reinforcement content.

  14. Ceramic whisker reinforcement of dental resin composites.

    PubMed

    Xu, H H; Martin, T A; Antonucci, J M; Eichmiller, F C

    1999-02-01

    Resin composites currently available are not suitable for use as large stress-bearing posterior restorations involving cusps due to their tendencies toward excessive fracture and wear. The glass fillers in composites provide only limited reinforcement because of the brittleness and low strength of glass. The aim of the present study was to reinforce dental resins with ceramic single-crystalline whiskers of elongated shapes that possess extremely high strength. A novel method was developed that consisted of fusing silicate glass particles onto the surfaces of individual whiskers for a two-fold benefit: (1) to facilitate silanization regardless of whisker composition; and (2) to enhance whisker retention in the matrix by providing rougher whisker surfaces. Silicon nitride whiskers, with an average diameter of 0.4 microm and length of 5 microm, were coated by the fusion of silica particles 0.04 microm in size to the whisker surface at temperatures ranging from 650 degrees C to 1000 degrees C. The coated whiskers were silanized and manually blended with resins by spatulation. Flexural, fracture toughness, and indentation tests were carried out for evaluation of the properties of the whisker-reinforced composites in comparison with conventional composites. A two-fold increase in strength and toughness was achieved in the whisker-reinforced composite, together with a substantially enhanced resistance to contact damage and microcracking. The highest flexural strength (195+/-8 MPa) and fracture toughness (2.1+/-0.3 MPa x m(1/2)) occurred in a composite reinforced with a whisker-silica mixture at whisker:silica mass ratio of 2:1 fused at 800 degrees C. To conclude, the strength, toughness, and contact damage resistance of dental resin composites can be substantially improved by reinforcement with fillers of ceramic whiskers fused with silica glass particles.

  15. Whisker-reinforced ceramic composites for heat engine components

    NASA Technical Reports Server (NTRS)

    Duffy, Stephen F.

    1988-01-01

    Much work was undertaken to develop techniques of incorporating SiC whiskers into either a Si3N4 or SiC matrix. The result was the fabrication of ceramic composites with ever-increasing fracture toughness and strength. To complement this research effort, the fracture behavior of whisker-reinforced ceramics is studied so as to develop methodologies for the analysis of structural components fabricated from this toughened material. The results, outlined herein, focus on the following areas: the use of micromechanics to predict thermoelastic properties, theoretical aspects of fracture behavior, and reliability analysis.

  16. Continuous-fiber preform reinforcement of dental resin composite restorations.

    PubMed

    Xu, H H K; Schumacher, G E; Eichmiller, F C; Peterson, R C; Antonucci, J M; Mueller, H J

    2003-09-01

    Direct-filling resin composites are used in relatively small restorations and are not recommended for large restorations with severe occlusal-stresses. The aim of this study was to reinforce composites with fiber preforms, and to investigate the effects of layer thickness and configurations on composite properties. It was hypothesized that fiber preforms would significantly increase the composite's flexural strength, work-of-fracture (toughness) and elastic modulus. Glass fibers were silanized, impregnated with a resin, cured, and cut to form inserts for tooth cavity restorations. Also fabricated were three groups of specimens of 2mm x 2mm x 25 mm: a fiber preform rod in the center of a hybrid composite; a thin fiber layer on the tensile side of the specimens; and a thin fiber layer sandwiched in between layers of a hybrid composite. These specimens were tested in three-point flexure to measure strength, work-of-fracture and modulus. Optical and scanning electron microscopy were used to examine the restorations and the fiber distributions. Microscopic examinations of insert-filled tooth cavities showed that the fibers were relatively uniform in distribution within the preform, and the inserts were well bonded with the surrounding hybrid composite. Specimens consisting of a fiber preform rod in the center of a hybrid composite had a flexural strength (mean (SD); n=6) of 313 (19)MPa, significantly higher than 120 (16)MPa of the hybrid composite without fibers (Tukey's at family confidence of 0.95). The work-of-fracture was increased by nearly seven times, and the modulus was doubled, due to fiber preform reinforcement. Similar improvements were obtained for the other two groups of specimens. Substantial improvements in flexural strength, toughness and stiffness were achieved for dental resin composites reinforced with fiber preforms. The method of embedding a fiber preform insert imparts superior reinforcement to restorations and should improve the performance of

  17. Mullite-whisker reinforced molybdenum disilicide composites

    NASA Astrophysics Data System (ADS)

    McFayden, Andre Anthony

    Molybdenum disilicide (MoSisb2) is a potential high temperature structural material. The use of such materials may raise the operating temperatures of heat engines and therefore their efficiencies, leading to fuel savings. Molybdenum disilicide has good oxidation resistance to 1650sp°C and high temperature strength to about 1000sp°C. This work was an attempt to improve the poor room temperature toughness and high temperature creep resistance of this material. Mullite was used as a reinforcement in the form of whiskers. Whiskers may increase the toughness of a matrix by extrinsic mechanisms, while mullite has intrinsically high creep resistance. Mechanical property predictions were made for the proposed composite material. The toughening mechanisms examined were crack bridging, pullout, crack deflection and microcracking. For the bridging model alone, a doubling of the fracture toughness was expected for a 40 percent mullite whisker volume. The creep models examined were the isostress, isostrain, shear-lag and self-consistent scheme. The shear-lag model predicted a factor of five decrease in the creep rate compared to pure MoSisb2. Composites of MoSisb2 containing 0, 20 and 40 volume percent of mullite were fabricated by means of a powder processing route. This involved mixing powders of the component materials, followed by hot-pressing and hot isostatic pressing to form a composite body. Both equi-axed particles and elongated whiskers of mullite were used. The mullite whisker size, powder mixing time, and glass content of the initial MoSisb2 powder were also varied. The resulting materials were subjected to mechanical testing. At room temperature, indentation testing was used to determine the toughness and modulus of the composites. Indented beams were subjected to four-point bending until failure to determine the toughness. The maximum fracture toughness measured was 1.7 MPasurdm, compared to 1.6 MPasurdm for the matrix, with very little variation with

  18. Nondestructive testing of externally reinforced structures for seismic retrofitting using flax fiber reinforced polymer (FFRP) composites

    NASA Astrophysics Data System (ADS)

    Ibarra-Castanedo, C.; Sfarra, S.; Paoletti, D.; Bendada, A.; Maldague, X.

    2013-05-01

    Natural fibers constitute an interesting alternative to synthetic fibers, e.g. glass and carbon, for the production of composites due to their environmental and economic advantages. The strength of natural fiber composites is on average lower compared to their synthetic counterparts. Nevertheless, natural fibers such as flax, among other bast fibers (jute, kenaf, ramie and hemp), are serious candidates for seismic retrofitting applications given that their mechanical properties are more suitable for dynamic loads. Strengthening of structures is performed by impregnating flax fiber reinforced polymers (FFRP) fabrics with epoxy resin and applying them to the component of interest, increasing in this way the load and deformation capacities of the building, while preserving its stiffness and dynamic properties. The reinforced areas are however prompt to debonding if the fabrics are not mounted properly. Nondestructive testing is therefore required to verify that the fabric is uniformly installed and that there are no air gaps or foreign materials that could instigate debonding. In this work, the use of active infrared thermography was investigated for the assessment of (1) a laboratory specimen reinforced with FFRP and containing several artificial defects; and (2) an actual FFRP retrofitted masonry wall in the Faculty of Engineering of the University of L'Aquila (Italy) that was seriously affected by the 2009 earthquake. Thermographic data was processed by advanced signal processing techniques, and post-processed by computing the watershed lines to locate suspected areas. Results coming from the academic specimen were compared to digital speckle photography and holographic interferometry images.

  19. Composite Grids for Reinforcement of Concrete Structures.

    DTIC Science & Technology

    1998-06-01

    spiral deformation to provide a good bond between reinforcement and concrete. Research conducted by Larralde et al. (1989) investigated the...the stiffness of the steel-reinforced beams. Larralde and Zervai (1991) took a different approach by comparing the flexural behavior of FRP grating...Cincinnati, OH, Jan 30- Feb 1,1995. Session 21C. Larralde , AM. and Zerva, A., (1991). "Load/deflection Performance of FRP Grating-Concrete Composites

  20. Three-dimensional printing fiber reinforced hydrogel composites.

    PubMed

    Bakarich, Shannon E; Gorkin, Robert; in het Panhuis, Marc; Spinks, Geoffrey M

    2014-09-24

    An additive manufacturing process that combines digital modeling and 3D printing was used to prepare fiber reinforced hydrogels in a single-step process. The composite materials were fabricated by selectively pattering a combination of alginate/acrylamide gel precursor solution and an epoxy based UV-curable adhesive (Emax 904 Gel-SC) with an extrusion printer. UV irradiation was used to cure the two inks into a single composite material. Spatial control of fiber distribution within the digital models allowed for the fabrication of a series of materials with a spectrum of swelling behavior and mechanical properties with physical characteristics ranging from soft and wet to hard and dry. A comparison with the "rule of mixtures" was used to show that the swollen composite materials adhere to standard composite theory. A prototype meniscus cartilage was prepared to illustrate the potential application in bioengineering.

  1. Coupled heating/forming optimization of knitted reinforced composites

    NASA Astrophysics Data System (ADS)

    Pancrace, Johann

    The feasibility of knitted fabric reinforcement for highly flexible composites has been investigated for the thermoforming process. The composite sheets were made through compression molding before being shaped. We used thermoplastic elastomers as matrices: Thermoplastic Elastomers and Thermoplastic Olefins. The knit reinforcement was provided by jersey knitted fabrics of polyester fibers. We first introduced the fundamentals involved in the study. The manufacturing is presented through compression molding and thermoforming. The latter is a two-step process: IR heating and plug/pressure assisted deformations. For the IR heating phase, several material properties have been characterized: the emissivity of matrices, absorption, reflection and transmission of radiations in the composite structure have been studied. We particularly paid attention to the reflection on the composite surfaces. The non-reflected or useful radiations leading to the heating are quantified and simulated for three emitter-composite configurations. It has been found that the emitter temperatures and the angle of incidence have significant roles in the IR heating phase. Thermal properties such as calorific capacity and thermal conductivity of the composites were also presented. Thermograms were carried out with an IR camera. Equipment and Thermogram acquisitions were both presented. Optimization of emitters was performed for a three emitter system. The objective function method has been illustrated. Regarding mechanical purposes, the characterizations of the matrices, reinforcements and flexible composites have been carried out. The studied loadings were uniaxial traction, pure shear and biaxial inflation. For the uniaxial extension, both the reinforcement and the composite were found highly anisotropic regarding the orientation of the loading toward the coursewise of the fabric. The resulting strains and stresses to rupture are also found anisotropic. However, for pure shear loading we observed

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  4. Flammabilities Of Graphite-Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.

    1990-01-01

    Report describes tests and comparisons of flammabilities, thermal properties, and selected mechanical properties of composite materials made of epoxy and other matrices reinforced by graphite fibers. Composites also compared with baseline epoxy/fiberglass composite. Considers such properties as limiting oxygen index, smoke evolution, products of thermal degradation, total heat release, heat-release rate, loss of mass, spread of flames, resistance to ignition, and thermal stability.

  5. Carbon Nanomaterials as Reinforcements for Composites

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, S. L.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Carbon nanomaterials including fellerenes, nanotubes (CNT) and nanofibers have been proposed for many applications. One of applications is to use the carbon nanomaterials as reinforcements for composites, especially for polymer matrices. Carbon nanotubes is a good reinforcement for lightweight composite applications due to its low mass density and high Young's modulus. Two obscures need to overcome for carbon nanotubes as reinforcements in composites, which are large quantity production and functioning the nanotubes. This presentation will discuss the carbon nanotube growth by chemical vapor deposition. In order to reduce the cost of producing carbon nanotubes as well as preventing the sliding problems, carbon nanotubes were also synthesized on carbon fibers. The synthesis process and characterization results of nanotubes and nanotubes/fibers will be discussed in the presentation.

  6. Room-Temperature and High-Temperature Tensile Mechanical Properties of TA15 Titanium Alloy and TiB Whisker-Reinforced TA15 Matrix Composites Fabricated by Vacuum Hot-Pressing Sintering

    PubMed Central

    Feng, Yangju; Zhang, Wencong; Zeng, Li; Cui, Guorong; Chen, Wenzhen

    2017-01-01

    In this paper, the microstructure, the room-temperature and high-temperature tensile mechanical properties of monolithic TA15 alloy and TiB whisker-reinforced TA15 titanium matrix composites (TiBw/TA15) fabricated by vacuum hot-pressing sintering were investigated. The microstructure results showed that there were no obvious differences in the microstructure between monolithic TA15 alloy and TiBw/TA15 composites, except whether or not the grain boundaries contained TiBw. After sintering, the matrix microstructure presented a typical Widmanstätten structure and the size of primary β grain was consistent with the size of spherical TA15 titanium metallic powders. This result demonstrated that TiBw was not the only factor limiting grain coarsening of the primary β grain. Moreover, the grain coarsening of α colonies was obvious, and high-angle grain boundaries (HAGBs) were distributed within the primary β grain. In addition, TiBw played an important role in the microstructure evolution. In the composites, TiBw were randomly distributed in the matrix and surrounded by a large number of low-angle grain boundaries (LAGBs). Globularization of α phase occurred prior, near the TiBw region, because TiBw provided the nucleation site for the equiaxed α phase. The room-temperature and high-temperature tensile results showed that TiBw distributed at the primary β grain boundaries can strengthen the grain boundary, but reduce the connectivity of the matrix. Therefore, compared to the monolithic TA15 alloy fabricated by the same process, the tensile strength of the composites increased, and the tensile elongation decreased. Moreover, with the addition of TiBw, the fracture mechanism was changed to a mixture of brittle fracture and ductile failure (composites) from ductile failure (monolithic TA15 alloy). The fracture surfaces of TiBw/TA15 composites were the grain boundaries of the primary β grain where the majority of TiB whiskers distributed, i.e., the surfaces of the

  7. Room-Temperature and High-Temperature Tensile Mechanical Properties of TA15 Titanium Alloy and TiB Whisker-Reinforced TA15 Matrix Composites Fabricated by Vacuum Hot-Pressing Sintering.

    PubMed

    Feng, Yangju; Zhang, Wencong; Zeng, Li; Cui, Guorong; Chen, Wenzhen

    2017-04-18

    In this paper, the microstructure, the room-temperature and high-temperature tensile mechanical properties of monolithic TA15 alloy and TiB whisker-reinforced TA15 titanium matrix composites (TiBw/TA15) fabricated by vacuum hot-pressing sintering were investigated. The microstructure results showed that there were no obvious differences in the microstructure between monolithic TA15 alloy and TiBw/TA15 composites, except whether or not the grain boundaries contained TiBw. After sintering, the matrix microstructure presented a typical Widmanstätten structure and the size of primary β grain was consistent with the size of spherical TA15 titanium metallic powders. This result demonstrated that TiBw was not the only factor limiting grain coarsening of the primary β grain. Moreover, the grain coarsening of α colonies was obvious, and high-angle grain boundaries (HAGBs) were distributed within the primary β grain. In addition, TiBw played an important role in the microstructure evolution. In the composites, TiBw were randomly distributed in the matrix and surrounded by a large number of low-angle grain boundaries (LAGBs). Globularization of α phase occurred prior, near the TiBw region, because TiBw provided the nucleation site for the equiaxed α phase. The room-temperature and high-temperature tensile results showed that TiBw distributed at the primary β grain boundaries can strengthen the grain boundary, but reduce the connectivity of the matrix. Therefore, compared to the monolithic TA15 alloy fabricated by the same process, the tensile strength of the composites increased, and the tensile elongation decreased. Moreover, with the addition of TiBw, the fracture mechanism was changed to a mixture of brittle fracture and ductile failure (composites) from ductile failure (monolithic TA15 alloy). The fracture surfaces of TiBw/TA15 composites were the grain boundaries of the primary β grain where the majority of TiB whiskers distributed, i.e., the surfaces of the

  8. Simulation of the Manufacturing of Non-Crimp Fabric-Reinforced Composite Wind Turbine Blades to Predict the Formation of Wave Defects

    NASA Astrophysics Data System (ADS)

    Fetfatsidis, K. A.; Sherwood, J. A.

    2011-05-01

    NCFs (Non-Crimp Fabrics) are commonly used in the design of wind turbine blades and other complex systems due to their ability to conform to complex shapes without the wrinkling that is typically experienced with woven fabrics or prepreg tapes. In the current research, a form of vacuum assisted resin transfer molding known as SCRIMP® is used to manufacture wind turbine blades. Often, during the compacting of the fabric layers by the vacuum pressure, several plies may bunch together out-of-plane and form wave defects. When the resin is infused, the areas beneath the waves become resin rich and can compromise the structural integrity of the blade. A reliable simulation tool is valuable to help predict where waves and other defects may appear as a result of the manufacturing process. Forming simulations often focus on the in-plane shearing and tensile behavior of fabrics and do not necessarily consider the bending stiffness of the fabrics, which is important to predict the formation of wrinkles and/or waves. This study incorporates experimentally determined in-plane shearing, tensile, and bending stiffness information of NCFs into a finite element model (ABAQUS/Explicit) of a 9-meter wind turbine blade to investigate the mechanical behaviors that can lead to the formation of waves as a result of the manufacturing process.

  9. Simulation of the Manufacturing of Non-Crimp Fabric-Reinforced Composite Wind Turbine Blades to Predict the Formation of Wave Defects

    SciTech Connect

    Fetfatsidis, K. A.; Sherwood, J. A.

    2011-05-04

    NCFs (Non-Crimp Fabrics) are commonly used in the design of wind turbine blades and other complex systems due to their ability to conform to complex shapes without the wrinkling that is typically experienced with woven fabrics or prepreg tapes. In the current research, a form of vacuum assisted resin transfer molding known as SCRIMP registered is used to manufacture wind turbine blades. Often, during the compacting of the fabric layers by the vacuum pressure, several plies may bunch together out-of-plane and form wave defects. When the resin is infused, the areas beneath the waves become resin rich and can compromise the structural integrity of the blade. A reliable simulation tool is valuable to help predict where waves and other defects may appear as a result of the manufacturing process. Forming simulations often focus on the in-plane shearing and tensile behavior of fabrics and do not necessarily consider the bending stiffness of the fabrics, which is important to predict the formation of wrinkles and/or waves. This study incorporates experimentally determined in-plane shearing, tensile, and bending stiffness information of NCFs into a finite element model (ABAQUS/Explicit) of a 9-meter wind turbine blade to investigate the mechanical behaviors that can lead to the formation of waves as a result of the manufacturing process.

  10. Buckling of Fiber Reinforced Composite Plates with Nanofiber Reinforced Matrices

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Murthy, Pappu L. N.

    2010-01-01

    Anisotropic composite plates were evaluated with nanofiber reinforced matrices (NFRM). The nanofiber reinforcement volumes ratio in the matrix was 0.01. The plate dimensions were 20 by 10 by 1.0 in. (508 by 254 by 25.4 mm). Seven different loading condition cases were evaluated: three for uniaxial loading, three for pairs of combined loading, and one with three combined loadings. The anisotropy arose from the unidirectional plates having been at 30 from the structural axis. The anisotropy had a full 6 by 6 rigidities matrix which were satisfied and solved by a Galerkin buckling algorithm. The buckling results showed that the NFRM plates buckled at about twice those with conventional matrix.

  11. Initial evaluation of continuous fiber reinforced NiAl composites

    NASA Technical Reports Server (NTRS)

    Noebe, R. D.; Bowman, R. R.; Eldridge, J. I.

    1990-01-01

    NiAl is being evaluated as a potential matrix material as part of an overall program to develop and understand high-temperature structural composites. Currently, continuous fiber composites have been fabricated by the powder cloth technique incorporating either W(218) or single crystal Al2O3 fibers as reinforcements in both binary NiAl and a solute strengthened NiAl(.05 at. pct Zr) matrix. Initial evaluation of these composite systems have included: fiber push-out testing to measure matrix/fiber bond strengths, bend testing to determine strength as a function of temperature and composite structure, and thermal cycling to establish the effect of matrix and fiber properties on composite life. The effect of matrix/fiber bond strength and matrix strength on several composite properties will be discussed.

  12. Initial evaluation of continuous fiber reinforced NiAl composites

    NASA Technical Reports Server (NTRS)

    Noebe, R. D.; Bowman, R. R.; Eldridge, J. I.

    1990-01-01

    NiAl is being evaluated as a potential matrix material as part of an overall program to develop and understand high-temperature structural composites. Currently, continuous fiber composites have been fabricated by the powder cloth technique incorporating either W(218) or single crystal Al2O3 fibers as reinforcements in both binary NiAl and a solute strengthened NiAl(.05 at. pct Zr) matrix. Initial evaluation of these composite systems have included: fiber push-out testing to measure matrix/fiber bond strengths, bend testing to determine strength as a function of temperature and composite structure, and thermal cycling to establish the effect of matrix and fiber properties on composite life. The effect of matrix/fiber bond strength and matrix strength on several composite properties will be discussed.

  13. 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.

  14. 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.

  15. 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.

  16. Development and clinical applications of a light-polymerized fiber-reinforced composite.

    PubMed

    Freilich, M A; Karmaker, A C; Burstone, C J; Goldberg, A J

    1998-09-01

    After 0 years of intermittent reports in the literature, the use of fiber reinforcement is just now experiencing rapid expansion in dentistry. This article describes the development and use of a continuous, unidirectional fiber reinforced composite as a framework for the fabrication of fixed prostheses. By using various matrix materials and fibers, a number of fiber-reinforced composite formulations were evaluated with the goal of creating a system with optimized mechanical properties and handling characteristics. Fiber-reinforced composite based on a light polymerized BIS-GMA matrix has been used clinically to make 2-phase prostheses comprised of an internal glass fiber-reinforced composite substructure covered by a particulate composite. The clinical and laboratory procedures required for the fabrication and use of reinforced composite fixed prostheses are described for laboratory-fabricated complete or partial coverage fixed prosthesis and chairside prosthesis. Although additional clinical experience is needed, fiber-reinforced composite materials can be used to make metal-free prostheses with excellent esthetic qualities.

  17. Method of fabricating composite structures

    NASA Technical Reports Server (NTRS)

    Sigur, W. A. (Inventor)

    1990-01-01

    A method of fabricating structures formed from composite materials by positioning the structure about a high coefficient of thermal expansion material, wrapping a graphite fiber overwrap about the structure, and thereafter heating the assembly to expand the high coefficient of thermal expansion material to forcibly compress the composite structure against the restraint provided by the graphite overwrap. The high coefficient of thermal expansion material is disposed about a mandrel with a release system therebetween, and with a release system between the material having the high coefficient of thermal expansion and the composite material, and between the graphite fibers and the composite structure. The heating may occur by inducing heat into the assembly by a magnetic field created by coils disposed about the assembly through which alternating current flows. The method permits structures to be formed without the use of an autoclave.

  18. Fiber Reinforced Composite Cores and Panels

    NASA Technical Reports Server (NTRS)

    Day, Stephen W. (Inventor); Campbell, G. Scott (Inventor); Tilton, Danny E. (Inventor); Stoll, Frederick (Inventor); Sheppard, Michael (Inventor); Banerjee, Robin (Inventor)

    2013-01-01

    A fiber reinforced core panel is formed from strips of plastics foam helically wound with layers of rovings to form webs which may extend in a wave pattern or may intersect transverse webs. Hollow tubes may replace foam strips. Axial rovings cooperate with overlying helically wound rovings to form a beam or a column. Wound roving patterns may vary along strips for structural efficiency. Wound strips may alternate with spaced strips, and spacers between the strips enhance web buckling strength. Continuously wound rovings between spaced strips permit folding to form panels with reinforced edges. Continuously wound strips are helically wrapped to form annular structures, and composite panels may combine both thermoset and thermoplastic resins. Continuously wound strips or strip sections may be continuously fed either longitudinally or laterally into molding apparatus which may receive skin materials to form reinforced composite panels.

  19. Multifunctional composites using reinforced laminae with carbon-nanotube forests

    NASA Astrophysics Data System (ADS)

    Veedu, Vinod P.; Cao, Anyuan; Li, Xuesong; Ma, Kougen; Soldano, Caterina; Kar, Swastik; Ajayan, Pulickel M.; Ghasemi-Nejhad, Mehrdad N.

    2006-06-01

    Traditional fibre-reinforced composite materials with excellent in-plane properties fare poorly when out-of-plane through-thickness properties are important. Composite architectures with fibres designed orthogonal to the two-dimensional (2D) layout in traditional composites could alleviate this weakness in the transverse direction, but all of the efforts so far have only produced limited success. Here, we unveil an approach to the 3D composite challenge, without altering the 2D stack design, on the basis of the concept of interlaminar carbon-nanotube forests that would provide enhanced multifunctional properties along the thickness direction. The carbon-nanotube forests allow the fastening of adjacent plies in the 3D composite. We grow multiwalled carbon nanotubes on the surface of micro-fibre fabric cloth layouts, normal to the fibre lengths, resulting in a 3D effect between plies under loading. These nanotube-coated fabric cloths serve as building blocks for the multilayered 3D composites, with the nanotube forests providing much-needed interlaminar strength and toughness under various loading conditions. For the fabricated 3D composites with nanotube forests, we demonstrate remarkable improvements in the interlaminar fracture toughness, hardness, delamination resistance, in-plane mechanical properties, damping, thermoelastic behaviour, and thermal and electrical conductivities making these structures truly multifunctional.

  20. Failure criterion of glass fabric reinforced plastic laminates

    NASA Technical Reports Server (NTRS)

    Haga, O.; Hayashi, N.; Kasuya, K.

    1986-01-01

    Failure criteria are derived for several modes of failure (in unaxial tensile or compressive loading, or biaxial combined tensile-compressive loading) in the case of closely woven plain fabric, coarsely-woven plain fabric, or roving glass cloth reinforcements. The shear strength in the interaction formula is replaced by an equation dealing with tensile or compressive strength in the direction making a 45 degree angle with one of the anisotropic axes, for the uniaxial failure criteria. The interaction formula is useful as the failure criterion in combined tension-compression biaxial failure for the case of closely woven plain fabric laminates, but poor agreement is obtained in the case of coarsely woven fabric laminates.

  1. Fiber-reinforced ceramic composites made by chemical vapor infiltration

    SciTech Connect

    Caputo, A.J.; Lowden, R.A.; Stinton, D.P.

    1985-01-01

    A process was developed for the fabrication of ceramic-fiber-reinforced ceramic-matrix composites by chemical vapor infiltration. The ceramic composites were prepared by making fibrous preforms from multiple layers of SiC cloth and forming the silicon-carbide matrix for each component specimen by infiltrating the fibrous preform by a chemical vapor deposition process. A major goal of the work was achieved when infiltration was accomplished in hours instead of weeks by combining the thermal-gradient and forced-gas-flow techniques. Composites that possessed moderate flexural strength and high strain to failure were produced. In addition, the strength of the composites decreased gradually after the maximum strength was obtained, demonstrating that the composites had the desired high toughness and avoided the typical brittle behavior of monolithic ceramics.

  2. Mechanical properties of bone-shaped-short-fiber reinforced composites

    SciTech Connect

    Zhu, Y.T.; Valdez, J.A.; Beyerlein, I.J.; Zhou, S.J.; Liu, C.; Stout, M.G.; Butt, D.P.; Lowe, T.C.

    1999-04-23

    Short-fiber composites usually have low strength and toughness relative to continuous fiber composites, an intrinsic problem caused by discontinuities at fiber ends and interfacial debonding. In this work a model polyethylene bone-shaped-short (BSS) fiber-reinforced polyester-matrix composite was fabricated to prove that fiber morphology, instead of interfacial strength, solves this problem. Experimental tensile and fracture toughness test results show that BSS fibers can bridge matrix cracks more effectively, and consume many times more energy when pulled out, than conventional straight short (CSS) fibers. This leads to both higher strength and fracture toughness for the BSS-fiber composites. A computational model was developed to simulate crack propagation in both BSS- and CSS-fiber composites, accounting for stress concentrations, interface debonding, and fiber pull-put. Model predictions were validated by experimental results and will be useful in optimizing BSS-fiber morphology and other material system parameters.

  3. Dynamic Mechanical Behavior of Nickel-Aluminum Reinforced Epoxy Composites

    NASA Astrophysics Data System (ADS)

    Martin, M.; Hanagud, S.; Thadhani, N. N.

    2006-07-01

    Epoxy-based composites reinforced with micron-sized Ni and micron or nano-sized Al powders were fabricated by casting/curing. The mechanical behavior of the composites was evaluated using elastic and plastic property measurements performed on rod-shaped samples. Dynamic reverse Taylor anvil-on-rod impact tests gave qualitative and quantitative information about the transient deformation and failure response of the composites. The composite containing 20wt% epoxy and nano-sized Al powder showed the most superior mechanical properties in terms of elastic modulus, static compressive strength, and dynamic incremental areal and axial strains, as compared to the other cast materials. The results illustrate that nano-sized Al particles alter the deformation response of the composite and provide significant enhancement to the strength by dispersing in the epoxy and generating a nano Al-containing epoxy matrix with embedded Ni particles.

  4. Evaluation of capillary reinforced composites

    NASA Technical Reports Server (NTRS)

    Cahill, J. E.; Halase, J. F.; South, W. K.; Stoffer, L. J.

    1985-01-01

    Anti-icing of the inlet of jet engines is generally performed with high pressure heated air that is directed forward from the compressor through a series of pipes to various manifolds located near the structures to be anti-iced. From these manifolds, the air is directed to all flowpath surfaces that may be susceptible to ice formation. There the anti-icing function may be performed by either heat conduction or film heating. Unfortunately, the prospect of utilizing lighweight, high strength composites for inlet structures of jet engines has been frustrated by the low transverse thermal conductivity of such materials. It was the objective of this program to develop an advanced materials and design concept for anti-icing composite structures. The concept that was evaluated used capillary glass tubes embedded on the surface of a composite structure with heated air ducted through the tubes. An analytical computer program was developed to predict the anti-icing performance of such tubes and a test program was conducted to demonstrate actual performance of this system. Test data and analytical code results were in excellent agreement. Both indicate feasibility of using capillary tubes for surface heating as a means for composite engine structures to combat ice accumulation.

  5. Novel Dental Composites Reinforced with Zirconia-Silica Ceramic Nanofibers

    PubMed Central

    Guo, Guangqing; Fan, Yuwei; Zhang, Jian-Feng; Hagan, Joseph; Xu, Xiaoming

    2011-01-01

    Objective To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers. Methods Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.0, and 7.5 wt% ZS or ZYS nanofibers replacing glass particle filler) were prepared by blending 29 wt% dental resin monomers, 70 wt% filler, and 1.0 wt% initiator, and polymerized by either heat or dental curing light. Flexural strength (FS), flexural modulus (FM), energy at break (EAB), and fracture toughness (FT) were tested after the specimens were stored in 37 °C deionized water for 24 h, 3 months, or 6 months. Degree of conversion (DC) of monomers in composites was measured using Fourier transformed near-infrared (FT-NIR) spectroscopy. Fractured surfaces were observed by field-emission scanning electron microscope (FE-SEM). The data were analyzed using ANOVA with Tukey’s Honestly Significant Differences test used for post hoc analysis. Results Reinforcement of dental composites with ZS or ZYS nanofibers (2.5% or 5.0%) can significantly increase the FS, FM and EAB of dental composites over the control. Further increase the content of ZS nanofiber (7.5%), however, decreases these properties (although they are still higher than those of the control). Addition of nanofibers did not decrease the long-term mechanical properties of these composites. All ZS reinforced composites (containing 2.5%, 5.0% and 7.5% ZS nanofibers) exhibit significantly higher fracture toughness than the control. The DC of the composites decreases with ZS nanofiber content. Significance Incorporation of ceramic nanofibers in dental composites can significantly improve their mechanical properties and fracture toughness and thus may extend their service life. PMID:22153326

  6. Novel dental composites reinforced with zirconia-silica ceramic nanofibers.

    PubMed

    Guo, Guangqing; Fan, Yuwei; Zhang, Jian-Feng; Hagan, Joseph L; Xu, Xiaoming

    2012-04-01

    To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers. Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.0, and 7.5 wt% ZS or ZYS nanofibers replacing glass particle filler) were prepared by blending 29 wt% dental resin monomers, 70 wt% filler, and 1.0 wt% initiator, and polymerized by either heat or dental curing light. Flexural strength (FS), flexural modulus (FM), energy at break (EAB), and fracture toughness (FT) were tested after the specimens were stored in 37°C deionized water for 24h, 3 months, or 6 months. Degree of conversion (DC) of monomers in composites was measured using Fourier transformed near-infrared (FT-NIR) spectroscopy. Fractured surfaces were observed by field-emission scanning electron microscope (FE-SEM). The data were analyzed using ANOVA with Tukey's Honestly Significant Differences test used for post hoc analysis. Reinforcement of dental composites with ZS or ZYS nanofibers (2.5% or 5.0%) can significantly increase the FS, FM and EAB of dental composites over the control. Further increase the content of ZS nanofiber (7.5%), however, decreases these properties (although they are still higher than those of the control). Addition of nanofibers did not decrease the long-term mechanical properties of these composites. All ZS reinforced composites (containing 2.5%, 5.0% and 7.5% ZS nanofibers) exhibit significantly higher fracture toughness than the control. The DC of the composites decreases with ZS nanofiber content. Incorporation of ceramic nanofibers in dental composites can significantly improve their mechanical properties and fracture toughness and thus may extend their service life. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Analysis of Graphite Reinforced Cementitious Composites

    NASA Technical Reports Server (NTRS)

    Vaughan, Robert E.; Gilbert, John A.; Spanyer, Karen (Technical Monitor)

    2001-01-01

    This paper describes analytical methods that can be used to determine the deflections and stresses in highly compliant graphite-reinforced cementitious composites. It is demonstrated that the standard transform section fails to provide accurate results when the elastic modulus ratio exceeds 20. So an alternate approach is formulated by using the rule of mixtures to determine a set of effective material properties for the composite. Tensile tests are conducted on composite samples to verify this approach; and, when the effective material properties are used to characterize the deflections of composite beams subject to pure bending, an excellent agreement is obtained. Laminated composite plate theory is also investigated as a means for analyzing even more complex composites, consisting of multiple graphite layers oriented in different directions. In this case, composite beams are analyzed by incorporating material properties established from tensile tests. Finite element modeling is used to verity the results and, considering the complexity of the samples, a very good agreement is obtained.

  8. Reinforcing masonry walls with composite materials

    NASA Astrophysics Data System (ADS)

    Jai, John Chia-Han

    1999-10-01

    In this investigation, a procedure is developed for determining the effectiveness of composite materials in retrofitting masonry buildings to reduce seismic damage. The reinforcement considered is a thin layer of fiber-reinforced composite applied to the wall in a wallpaper-like fashion. Models were developed which predicts the behavior of masonry walls reinforced in such a fashion and subjected to static, in-plane normal and shear loads. Solid walls, as well as walls with openings (such as windows and doors), were considered. The models estimate the load-deflection characteristic of the wall, the load set at which the wall fails, and the deflection of the wall at the instant of failure. The models were verified by tests performed with walls constructed of clay bricks and mortar, and with walls made of wood bricks. In these tests, the load versus deflection, the failure load, and the failure deflection were measured. Reasonable agreements were found between the values calculated by the models and the data. Parametric studies were also performed. The results of these studies indicate that composite reinforcement applied in a wallpaper-like fashion may increase substantially the load carrying capacities of masonry walls.

  9. Research Update for: A Method for Out-of-autoclave Fabrication of High Fiber Volume Fraction Fiber Reinforced Polymer Composites (ARL-TR-6057)

    DTIC Science & Technology

    2012-10-01

    2 Figure 2. Tensile modulus of samples evaluated using ASTM D 3039 ...American Society for Testing and Materials ( ASTM ) standards D 3039 (Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials...The mean increase in tensile modulus is approximately 10.0%. Figure 2. Tensile modulus of samples evaluated using ASTM D 3039 . The tendency for

  10. 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.

  11. Fabrication of a biocomposite reinforced with hydrophilic eggshell proteins

    NASA Astrophysics Data System (ADS)

    Kim, Geun Hyung; Min, Taijin; Park, Su A.; Doo Kim, Wan; Koh, Young Ho

    2007-12-01

    Soluble eggshell proteins were used as a reinforcing material of electrospun micro/nanofibers for tissue engineering. A biocomposite composed of poly(ɛ-caprolactone) (PCL) micro/nanofibers and soluble eggshell protein was fabricated with a two-step fabrication method, which is an electrospinning process followed by an air-spraying process. To achieve a stable electrospinning process, we used an auxiliary cylindrical electrode connected with a spinning nozzle. PCL biocomposite was characterized in water contact angle and mechanical properties as well as cell proliferation for its application as a tissue engineering material. It showed an improved hydrophilic characteristic compared with that of a micro/nanofiber web generated from a pure PCL solution using a typical electrospinning process. Moreover, the fabricated biocomposite had good mechanical properties compared to a typical electrospun micro/nanofiber mat. The fabricated biocomposite made human dermal fibroblasts grow better than pure PCL. From the results, the reinforced polymeric micro/nanofiber scaffold can be easily achieved with these modified processes.

  12. Fabrication of a biocomposite reinforced with hydrophilic eggshell proteins.

    PubMed

    Kim, GeunHyung; Min, Taijin; Park, Su A; Kim, Wan Doo; Koh, Young Ho

    2007-12-01

    Soluble eggshell proteins were used as a reinforcing material of electrospun micro/nanofibers for tissue engineering. A biocomposite composed of poly(epsilon-caprolactone) (PCL) micro/nanofibers and soluble eggshell protein was fabricated with a two-step fabrication method, which is an electrospinning process followed by an air-spraying process. To achieve a stable electrospinning process, we used an auxiliary cylindrical electrode connected with a spinning nozzle. PCL biocomposite was characterized in water contact angle and mechanical properties as well as cell proliferation for its application as a tissue engineering material. It showed an improved hydrophilic characteristic compared with that of a micro/nanofiber web generated from a pure PCL solution using a typical electrospinning process. Moreover, the fabricated biocomposite had good mechanical properties compared to a typical electrospun micro/nanofiber mat. The fabricated biocomposite made human dermal fibroblasts grow better than pure PCL. From the results, the reinforced polymeric micro/nanofiber scaffold can be easily achieved with these modified processes.

  13. 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.

  14. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  16. Machining of fiber-reinforced composite laminates

    NASA Astrophysics Data System (ADS)

    Won, Myong-Shik

    As fiber-reinforced composite laminates are becoming considerably popular in a wide range of applications, the necessity for machining such materials is increasing rapidly. Due to their microscopical inhomogeneity, anisotropy, and highly abrasive nature, composite laminates exhibit some peculiar types of machining damage. Consequently, the machining of composite laminates requires a different approach from that used for metals and offers a challenge from both an academic and application point of view. In the present work, the drilling of composite laminated plates and the edge trimming of tubular composite laminates were investigated through theoretical analyses and their experimental verification. First, a drilling process model using linear elastic fracture mechanics and classical plate bending theory was developed to predict the critical thrust value responsible for the onset of delamination during the drilling of composite laminates with pre-drilled pilot holes. Experiments using stepped drills, which can utilize the effectiveness of such pilot holes, were conducted on composite laminates. Reasonably good agreement was found between the results of the process model and the tests. Second, the development of a model-based intelligent control strategy for the efficient drilling of composite laminates was explored by experiments and analyses. In this investigation, mathematical models were created to relate the drilling forces to cutting parameters and to identify the different process stages. These models predicted the degree of thrust force regulation to prevent delamination. Third, the edge trimming of thin-walled tubular composite laminates was modeled and analyzed for estimating the critical cutting force at the initiation of longitudinal cracking. A series of full-scale edge trimming tests were conducted on tubular composite specimens to assess the current approach and to obtain basic machining data for various composite laminates. The present study provides

  17. Fabrication of TiC-Reinforced Composites by Vacuum Arc Melting: TiC Mode of Reprecipitation in Different Molten Metals and Alloys

    NASA Astrophysics Data System (ADS)

    Karantzalis, A. E.; Arni, Z.; Tsirka, K.; Evangelou, A.; Lekatou, A.; Dracopoulos, V.

    2016-08-01

    TiC crystals were developed and grown through a melt dissolution and reprecipitation mechanism, in different alloy matrices (pure Fe, 316L, Fe-22 at.%Al, Ni-25at.%Al, and pure Co) through the use of Vacuum Arc Melting (VAM) process. The TiC surfaces exhibit a characteristic faceted mode of growth which is explained in terms of classic nucleation and crystal growth theories and is related with the well-known Jackson factor of crystal growth. Different morphologies of the finally solidified TiC grains are observed (dendritic, radially grown, isolated blocky crystals, particle clusters), the establishment of which may be most likely related with solidification progress, cooling rate, and melt compositional considerations. An initial, rough and qualitative phase identification shows a variety of compounds, and the attempts to define specific phase crystallographic-orientational relationships led to rather random results.

  18. Impact behavior of hydroxyapatite reinforced polyethylene composites.

    PubMed

    Zhang, Y; Tanner, K E

    2003-01-01

    Hydroxyapatite particulate reinforced high density polyethylene composite (HA-HDPE) has been developed as a bone replacement material. The impact behavior of the composites at 37 degrees C has been investigated using an instrumented falling weight impact testing machine. The fracture surfaces were examined using SEM and the fracture mechanisms are discussed. It was found that the fracture toughness of HA-HDPE composites increased with HDPE molecular weight, but decreased with increasing HA volume fraction. Examination of fracture surfaces revealed weak filler/matrix interfaces which can debond easily to enable crack initiation and propagation. Increasing HA volume fraction increases the interface area, and more cracks can form and develop, thus decreasing the impact resistance of the composites. Another important factor for the impact behavior of the composites is the matrix. At higher molecular weight, HDPE is able to sustain more plastic deformation and dissipates more impact energy, hence improving the impact property.

  19. Interfacial stresses in shape memory alloy-reinforced composites

    NASA Astrophysics Data System (ADS)

    Hiremath, S. R.; Prajapati, Maulik; Rakesh, S.; Roy Mahapatra, D.

    2014-03-01

    Debonding of Shape Memory Alloy (SMA) wires in SMA reinforced polymer matrix composites is a complex phenomenon compared to other fabric fiber debonding in similar matrix composites. This paper focuses on experimental study and analytical correlation of stress required for debonding of thermal SMA actuator wire reinforced composites. Fiber pull-out tests are carried out on thermal SMA actuator at parent state to understand the effect of stress induced detwinned martensites. An ASTM standard is followed as benchmark method for fiber pull-out test. Debonding stress is derived with the help of non-local shear-lag theory applied to elasto-plastic interface. Furthermore, experimental investigations are carried out to study the effect of Laser shot peening on SMA surface to improve the interfacial strength. Variation in debonding stress due to length of SMA wire reinforced in epoxy are investigated for non-peened and peened SMA wires. Experimental results of interfacial strength variation due to various L/d ratio for non-peened and peened SMA actuator wires in epoxy matrix are discussed.

  20. Fiber Reinforced Composite Materials Used for Tankage

    NASA Technical Reports Server (NTRS)

    Cunningham, Christy

    2005-01-01

    The Nonmetallic Materials and Processes Group is presently working on several projects to optimize cost while providing effect materials for the space program. One factor that must be considered is that these materials must meet certain weight requirements. Composites contribute greatly to this effort. Through the use of composites the cost of launching payloads into orbit will be reduced to one-tenth of the current cost. This research project involved composites used for aluminum pressure vessels. These tanks are used to store cryogenic liquids during flight. The tanks need some type of reinforcement. Steel was considered, but added too much weight. As a result, fiber was chosen. Presently, only carbon fibers with epoxy resin are wrapped around the vessels as a primary source of reinforcement. Carbon fibers are lightweight, yet high strength. The carbon fibers are wet wound onto the pressure vessels. This was done using the ENTEC Filament Winding Machine. It was thought that an additional layer of fiber would aid in reinforcement as well as containment and impact reduction. Kevlar was selected because it is light weight, but five times stronger that steel. This is the same fiber that is used to make bullet-proof vests trampolines, and tennis rackets.

  1. Design and fabrication of a boron reinforced intertank skirt

    NASA Technical Reports Server (NTRS)

    Henshaw, J.; Roy, P. A.; Pylypetz, P.

    1974-01-01

    Analytical and experimental studies were performed to evaluate the structural efficiency of a boron reinforced shell, where the medium of reinforcement consists of hollow aluminum extrusions infiltrated with boron epoxy. Studies were completed for the design of a one-half scale minimum weight shell using boron reinforced stringers and boron reinforced rings. Parametric and iterative studies were completed for the design of minimum weight stringers, rings, shells without rings and shells with rings. Computer studies were completed for the final evaluation of a minimum weight shell using highly buckled minimum gage skin. The detail design is described of a practical minimum weight test shell which demonstrates a weight savings of 30% as compared to an all aluminum longitudinal stiffened shell. Sub-element tests were conducted on representative segments of the compression surface at maximum stress and also on segments of the load transfer joint. A 10 foot long, 77 inch diameter shell was fabricated from the design and delivered for further testing.

  2. Scaling effects of defects in fiber-reinforced composites

    NASA Technical Reports Server (NTRS)

    Wang, A. S. D.

    1994-01-01

    Material defects may be introduced willingly or unwillingly during material manufacturing and structural component fabrication stages. Their presence in the material plays a dominant role in determining the material's strength and the associate failure mechanisms. In the sense that the size and the number of defects may increase with the volume of the material, the effect of dimensional scaling may manifest itself in the dependence of material strength on volume. Or, alternatively, there may exist a scaling effect of material defects. In fiber-reinforced composites, manufacturing or fabrication defects may come in several forms: matrix voids, matrix microcracks, fiber misalignment, broken fibers, or interface disbonds, just to mention a few. These are interacting and competing defects in the sense that one type of defect may become dominant under one stress condition and another type of defect may become dominant under a different stress condition. This happens because the fiber reinforcement network, together with the distribution of defects, constitutes the prime microstructure of the composite, and there exist continued interactions between the evolving microstructure and the distribution of defects. In the process, the scaling effects of defects are complicated by this interaction. In this presentation, the scaling effects of defects in fiber-reinforced composites will be briefly discussed with the introduction of the concept of effective defects. It is then shown with the aid of some actual experimental and analysis results that the scaling effects are very much present, but they are regulated by the characteristic dimension of the composite microstructure due to the aforementioned microstructure-defect interaction effect.

  3. Titanium reinforced boron-polyimide composite

    NASA Technical Reports Server (NTRS)

    Clark, G. A.; Clayton, K. I.

    1969-01-01

    Processing techniques for boron polyimide prepreg were developed whereby composites could be molded under vacuum bag pressure only. A post-cure cycle was developed which resulted in no loss in room temperature mechanical properties of the composite at any time during up to 16 hours at 650 F. A design utilizing laminated titanium foil was developed to achieve a smooth transition of load from the titanium attachment points into the boron-reinforced body of the structure. The box beam test article was subjected to combined bending and torsional loads while exposed to 650 F. Loads were applied incrementally until failure occurred at 83% design limit load.

  4. Creep deformation characteristics of ductile discontinuous fiber reinforced composites

    SciTech Connect

    Biner, S.B.

    1993-10-01

    Role of material parameters and geometric parameters of ductile reinforcing phase on the creep deformation behavior of 20% discontinuously reinforced composite was numerically investigated including debonding and pull-out mechanisms. Results indicate that for rigidly bonded interfaces, the creep rate of the composite is not significantly influenced by the material properties and geometric parameters of the ductile reinforcing phase due to development of large hydrostatic stress and constrained deformation in the reinforcement. For debonding interfaces, the geometric parameters of the reinforcing phase are important; however, event with very weak interfacial behavior low composite creep rates can be achieved by suitable selection of the geometric parameters of the ductile reinforcing phase.

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

    PubMed

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

    2007-03-27

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

  6. Reinforcing of Cement Composites by Estabragh Fibres

    NASA Astrophysics Data System (ADS)

    Merati, A. A.

    2014-04-01

    The influence of Estabragh fibres has been studied to improve the performance characteristics of the reinforced cement composites. The concrete shrinkage was evaluated by counting the number of cracks and measuring the width of cracks on the surface of concrete specimens. Although, the Estabragh fibres lose their strength in an alkali environment of cement composites, but, the ability of Estabragh fibres to bridge on the micro cracks in the concrete matrix causes to decrease the width of the cracks on the surface of the concrete samples in comparison with the plain concrete. However, considering the mechanical properties of specimens such as bending strength and impact resistance, the specimens with 0.25 % of Estabragh fibre performed better in all respects compared to the physical and mechanical properties of reinforced cement composite of concrete. Consequently, by adding 0.25 % of Estabragh fibres to the cement composite of concrete, a remarkable improvement in physical and mechanical properties of fibre-containing cement composite is achieved.

  7. Laser Processing of Discontinuously Reinforced Aluminum Composites

    DTIC Science & Technology

    1994-03-01

    have attractive potential as engineering materials due to the combination of good mechanical properties and relatively low cost, howeve utilization of...are attractive materials because they combine good mechanical properties , the ability to be formed by standard metalworking techniques, and lower...the constituent materials, fabrication procedures, and secondary processing on the mechanical properties . Early DRA composites used standard wrought

  8. A study on the crushing behavior of basalt fiber reinforced composite structures

    NASA Astrophysics Data System (ADS)

    Pandian, A.; Veerasimman, A. P.; Vairavan, M.; Francisco, C.; Sultan, M. T. H.

    2016-10-01

    The crushing behavior and energy absorption capacity of basalt fiber reinforced hollow square structure composites are studied under axial compression. Using the hand layup technique, basalt fiber reinforced composites were fabricated using general purpose (GP) polyester resin with the help of wooden square shaped mould of varying height (100 mm, 150 mm and 200 mm). For comparison, similar specimens of glass fiber reinforced polymer composites were also fabricated and tested. Axial compression load is applied over the top end of the specimen with cross head speed as 2 mm/min using Universal Testing Machine (UTM). From the experimental results, the load-deformation characteristics of both glass fiber and basalt fiber composites were investigated. Crashworthiness and mode of collapse for the composites were determined from load-deformation curve, and they were then compared to each other in terms of their crushing behaviors.

  9. Modelling the effect of reinforcement deformation on the filling phase during liquid composite moulding

    SciTech Connect

    Long, A.C.; Rudd, C.D.; Blanchard, P.J.; Smith, P.; Chan, A.W.

    1997-12-31

    In recent years a number of researchers have developed simulations of the filling phase during liquid composite moulding (LCM). These rely on an accurate knowledge of the reinforcement permeability, which is usually determined experimentally using a simple flow experiment based on roll-stock reinforcement samples. However this neglects the effects of reinforcement deformation, which may result in a highly nonuniform distribution of fibre orientations and volume fractions. This paper attempts to account for these variations by integrating fabric drape modelling and LCM flow simulation software packages. Using this approach, the effects of reinforcement deformation on the filling phase are demonstrated on a generic component geometry using alternative injection strategies.

  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. Mechanics of platelet-reinforced composites assembled using mechanical and magnetic stimuli.

    PubMed

    Libanori, Rafael; Erb, Randall M; Studart, André R

    2013-11-13

    Current fabrication technologies of structural composites based on the infiltration of fiber weaves with a polymeric resin offer good control over the orientation of long reinforcing fibers but remain too cumbersome and slow to enable cost-effective manufacturing. The development of processing routes that allow for fine control of the reinforcement orientation and that are also compatible with fast polymer processing technologies remains a major challenge. In this paper, we show that bulk platelet-reinforced composites with tailored reinforcement architectures and mechanical properties can be fabricated through the directed-assembly of inorganic platelets using combined magnetic and mechanical stimuli. The mechanical performance and fracture behavior of the resulting composites under compression and bending can be deliberately tuned by assembling the platelets into designed microstructures. By combining high alignment degree and volume fractions of reinforcement up to 27 vol %, we fabricated platelet-reinforced composites that can potentially be made with cost-effective polymer processing routes while still exhibiting properties that are comparable to those of state-of-the-art glass-fiber composites.

  12. Fabrication technique of SMA/CFRP smart composites

    NASA Astrophysics Data System (ADS)

    Xu, Ya; Otsuka, Kazuhiro; Toyama, Nobuyuki; Yoshida, Hitoshi; Nagai, Hideki; Oishi, Ryutaro; Kikushima, Yoshihiro; Yuse, Kaori; Akimune, Yoshio; Kishi, Teruo

    2003-03-01

    In recent years, pre-strained TiNi shape memory alloys (SMA) have been used for fabricating smart structure with carbon fibers reinforced plastics (CFRP). However, since the curing temperature of CFRP is higher than the reverse transformation temperatures of TiNi SMA, special fixture jigs have to be used for keeping the pre-strain during fabrication, which restricted its practical application. We have developed a new method to control the transformation temperatures of SMA by proper thermo-mechanical treatments and composition adjustment, which is suitable to fabricate SMA/CFRP smart composite with a curing temperature of 130C. Furthermore, we tried to develop a new fabrication technique which is also suitable to fabricate SMA/CFRP smart composite with a curing temperature of 180C. It was found that by using cold drawn ultra-thin TiNi wires, TiNi/CFRP composites with a curing temperature of 180C could be fabricated without special fixture jigs. The damage suppression effect by embedded ultra-thin wires in the smart composite was confirmed.

  13. As-Fabricated Reinforced Carbon/Carbon Characterized

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Calomino, Anthony M.; Webster, Neal

    2004-01-01

    Reinforced carbon/carbon (RCC) is a critical material for the space shuttle orbiter. It is used on the wing leading edge and the nose cap, where maximum temperatures are reached on reentry. The existing leading-edge system is a single-plate RCC composite construction with a wall thickness of approximately 1/4 in., making it a prime reliant protection scheme for vehicle operation.

  14. 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.

  15. Fabrication and Structure Characterization of Alumina-Aluminum Interpenetrating Phase Composites

    NASA Astrophysics Data System (ADS)

    Dolata, Anna J.

    2016-08-01

    Alumina-Aluminum composites with interpenetrating networks structure belong to advanced materials with potentially better properties when compared with composites reinforced by particles or fibers. The paper presents the experimental results of fabrication and structure characterization of Al matrix composites locally reinforced via Al2O3 ceramic foam. The composites were obtained using centrifugal infiltration of porous ceramics by liquid aluminum alloy. Both scanning electron microscopy (SEM + EDS) and x-ray tomography were used to determine the structure of foams and composites especially in reinforced areas. The quality of castings, degree of pore filling in ceramic foams by Al alloy, and microstructure in area of interface were assessed.

  16. Flexural behavior of a glass fiber reinforced wood fiber composite

    SciTech Connect

    Smulski, S.J.

    1985-01-01

    The static and dynamic flexural properties of a wood fiber matrix internally reinforced with continuous glass fibers were investigated. When modeled as sandwich composite, the static flexural modulus of elasticity (MOE) of glass fiber reinforced hardboard could be successfully predicted from the static flexural MOE of the wood fiber matrix, and the tensile MOE and effective volume fraction of the glass fiber reinforcement. Under the same assumption, the composite modulus of rupture (MOR) was a function of the reinforcement tensile MOE and effective volume fraction, and the matrix stress at failure. The composite MOR was predicted on this basis with limited success. The static flexural modulus of elasticity, dynamic modulus of elasticity, and modulus of rupture of glass fiber reinforced hardboard increased with increasing effective reinforcement volume fraction. The logarithmic decrement of the composite decreased with increasing effective reinforcement volume fraction. The short-term flexural creep behavior of glass fiber reinforced hardboard was accurately described by a 4-element linear viscoelastic model.

  17. An anisotropic constitutive model with biaxial-tension coupling for woven composite reinforcements

    NASA Astrophysics Data System (ADS)

    Yao, Yuan; Huang, Xiaoshuang; Peng, Xiongqi; Gong, Youkun

    2016-10-01

    Based on fiber reinforced continuum mechanics theory, an anisotropic hyperelastic constitutive model with biaxial tension coupling for woven composite reinforcements is developed. Experimental data from literature are used to identify material parameters in the constitutive model for a specific balanced plain woven fabric. The developed model is validated by comparing numerical results with experimental biaxial tension data under different stretch ratios and picture-frame shear data, demonstrating that the developed constitutive model is highly suitable to characterize the highly non-linear and strongly anisotropic mechanical behaviors of woven composite reinforcements under large deformation.

  18. Impact and dynamic mechanical thermal properties of textile silk reinforced epoxy resin composites

    NASA Astrophysics Data System (ADS)

    Yang, K.; Guan, J.

    2016-07-01

    Silk fabric reinforced epoxy resin composites (SFRPs) were prepared using simple techniques of hand lay-up, hot-press and vacuum treatment, and a series of volume fractions of silk reinforcements were achieved. The impact properties and dynamic mechanical properties of SFRPs were investigated using a pendulum impact testing method and dynamic mechanical thermal analysis (DMTA). The results suggest that silk reinforcement could greatly enhance the mechanical performances of SFRPs. The impact strength reached a maximum of 71 kJ/m2 for 60%-silk SFRP, which demonstrated a potential of silk composites for defence and impact- resistant materials.

  19. Modified glass fibre reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Cao, Yumei

    A high ratio of strength to density and relatively low-cost are some of the significant features of glass fibre reinforced polymer composites (GFRPCs) that made them one of the most rapidly developed materials in recent years. They are widely used as the material of construction in the areas of aerospace, marine and everyday life, such as airplane, helicopter, boat, canoe, fishing rod, racket, etc. Traditionally, researchers tried to raise the mechanical properties and keep a high strength/weight ratio using all or some of the following methods: increasing the volume fraction of the fibre; using different polymeric matrix material; or changing the curing conditions. In recent years, some new techniques and processing methods were developed to further improve the mechanical properties of glass fibre (GF) reinforced polymer composite. For example, by modifying the surface condition of the GF, both the interface strength between the GF and the polymer matrix and the shear strength of the final composite can be significantly increased. Also, by prestressing the fibre during the curing process of the composite, the tensile, flexural and the impact properties of the composite can be greatly improved. In this research project, a new method of preparing GFRPCs, which combined several traditional and modern techniques together, was developed. This new method includes modification of the surface of the GF with silica particles, application of different levels of prestressing on the GF during the curing process, and the change of the fibre volume fraction and curing conditions in different sets of experiments. The results of the new processing were tested by the three-point bend test, the short beam shear test and the impact test to determine the new set of properties so formed in the composite material. Scanning electronic microscopy (SEM) was used to study the fracture surface of the new materials after the mechanical tests were performed. By taking advantages of the

  20. Tungsten fiber reinforced FeCrAlY - A first generation composite turbine blade material

    NASA Technical Reports Server (NTRS)

    Petrasek, D. W.; Winsa, E. A.; Westfall, L. J.; Signorelli, R. A.

    1979-01-01

    General and composite turbine blade material requirements are examined to identify a specific tungsten fiber reinforced superalloy (TFRS) having, in addition to strength, the desired combination of other material properties needed in turbine blades. Experimental data indicated that a thoriated tungsten fiber reinforced FeCrAlY matrix composite should have the stress-rupture, creep, tensile, fatigue, and impact strengths required for turbine blades operating from 1250 to 1370 K. Fabrication and design concepts are developed to demonstrate the feasibility of fabricating a hollow TFRS turbine blade at reasonable cost.

  1. Design, Construction, and Analysis of Fabric-Reinforced Embankment Test Section at Pinto Pass, Mobile, Alabama.

    DTIC Science & Technology

    1981-10-01

    AD-A 07 556 ARM ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG--ETC F/G 13/13 DESIGN CONSTRUCTION AND ANALYSIS OF FABRIC-REINFORCED EMBANKM--ETC(U...AND ANALYSIS OF ~FABRIC-REINFORCED EMBANKMENT TEST if SECTION AT PINTO PASS, MOBILE, ALABAMA Lr: by Jack Fowler Geoechnical Laboratory I U. S. Army...AND ANALYSIS OF FABRIC- REINFORCED EMBANKMENT TEST SECTION AT PINTO PASS, MOBILE, ALABAMA 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(e) 1. CONTRACT

  2. Nacre-mimetic bulk lamellar composites reinforced with high aspect ratio glass flakes.

    PubMed

    Guner, Selen N Gurbuz; Dericioglu, Arcan F

    2016-12-05

    Nacre-mimetic epoxy matrix composites reinforced with readily available micron-sized high aspect ratio C-glass flakes were fabricated by a relatively simple, single-step, scalable, time, cost and man-power effective processing strategy: hot-press assisted slip casting (HASC). HASC enables the fabrication of preferentially oriented two-dimensional inorganic reinforcement-polymer matrix bulk lamellar composites with a micro-scale structure resembling the brick-and-mortar architecture of nacre. By applying the micro-scale design guideline found in nacre and optimizing the relative volume fractions of the reinforcement and the matrix as well as by anchoring the brick-and-mortar architecture, and tailoring the interface between reinforcements and the matrix via silane coupling agents, strong, stiff and tough bio-inspired nacre-mimetic bulk composites were fabricated. As a result of high shear stress transfer lengths and effective stress transfer at the interface achieved through surface functionalization of the reinforcements, fabricated bulk composites exhibited enhanced mechanical performance as compared to neat epoxy. Furthermore, governed flake pull-out mode along with a highly torturous crack path, which resulted from extensive deflection and meandering of the advancing crack around well-aligned high aspect ratio C-glass flakes, have led to high work-of-fracture values similar to nacre.

  3. Composite structural materials. [fiber reinforced composites for aircraft structures

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberly, S. E.

    1981-01-01

    Physical properties of fiber reinforced composites; structural concepts and analysis; manufacturing; reliability; and life prediction are subjects of research conducted to determine the long term integrity of composite aircraft structures under conditions pertinent to service use. Progress is reported in (1) characterizing homogeneity in composite materials; (2) developing methods for analyzing composite materials; (3) studying fatigue in composite materials; (4) determining the temperature and moisture effects on the mechanical properties of laminates; (5) numerically analyzing moisture effects; (6) numerically analyzing the micromechanics of composite fracture; (7) constructing the 727 elevator attachment rib; (8) developing the L-1011 engine drag strut (CAPCOMP 2 program); (9) analyzing mechanical joints in composites; (10) developing computer software; and (11) processing science and technology, with emphasis on the sailplane project.

  4. Mechanical property characterization of polymeric composites reinforced by continuous microfibers

    NASA Astrophysics Data System (ADS)

    Zubayar, Ali

    Innumerable experimental works have been conducted to study the effect of polymerization on the potential properties of the composites. Experimental techniques are employed to understand the effects of various fibers, their volume fractions and matrix properties in polymer composites. However, these experiments require fabrication of various composites which are time consuming and cost prohibitive. Advances in computational micromechanics allow us to study the various polymer based composites by using finite element simulations. The mechanical properties of continuous fiber composite strands are directional. In traditional continuous fiber laminated composites, all fibers lie in the same plane. This provides very desirable increases in the in-plane mechanical properties, but little in the transverse mechanical properties. The effect of different fiber/matrix combinations with various orientations is also available. Overall mechanical properties of different micro continuous fiber reinforced composites with orthogonal geometry are still unavailable in the contemporary research field. In this research, the mechanical properties of advanced polymeric composite reinforced by continuous micro fiber will be characterized based on analytical investigation and FE computational modeling. Initially, we have chosen IM7/PEEK, Carbon Fiber/Nylon 6, and Carbon Fiber/Epoxy as three different case study materials for analysis. To obtain the equivalent properties of the micro-hetero structures, a concept of micro-scale representative volume elements (RVEs) is introduced. Five types of micro scale RVEs (3 square and 2 hexagonal) containing a continuous micro fiber in the polymer matrix were designed. Uniaxial tensile, lateral expansion and transverse shear tests on each RVE were designed and conducted by the finite element computer modeling software ANSYS. The formulae based on elasticity theory were derived for extracting the equivalent mechanical properties (Young's moduli, shear

  5. Space fabrication demonstration system composite beam cap fabricator

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A detailed design for a prototype, composite beam cap fabricator was established. Inputs to this design included functional tests and system operating requirements. All required materials were procured, detail parts were fabricated, and one composite beam cap forming machine was assembled. The machine was demonstrated as a stand-alone system. Two 12-foot-long beam cap members were fabricated from laminates graphite/polysulfane or an equivalent material. One of these members, which as structurally tested in axial compression, failed at 490 pounds.

  6. Hydroxyapatite reinforced inherent RGD containing silk fibroin composite scaffolds: Promising platform for bone tissue engineering.

    PubMed

    Behera, Sibaram; Naskar, Deboki; Sapru, Sunaina; Bhattacharjee, Promita; Dey, Tuli; Ghosh, Ananta K; Mandal, Mahitosh; Kundu, Subhas C

    2017-03-08

    Replacement and repair of ectopic bone defects and traumatized bone tissues are done using porous scaffolds and composites. The prerequisites for such scaffolds include high mechanical strength, osseoconductivity and cytocompatibility. The present work is designed to address such requirements by fabricating a reinforced cytocompatible scaffold. Biocompatible silk protein fibroin collected from tropical non-mulberry tasar silkworm (Antheraea mylitta) is used to fabricate fibroin-hydroxyapatite (HAp) nanocomposite particles using chemical precipitation method. In situ reinforcement of fibroin-HAp nanocomposite and external deposition of HAp particles on fibroin scaffold is carried out for comparative evaluations of bio-physical and biochemical characteristics. HAp deposited fibroin scaffolds provide greater mechanical strength and cytocompatibility, when compared with fibroin-HAp nanoparticles reinforced fibroin scaffolds. Minimal immune responses of both types of composite scaffolds are observed using osteoblast-macrophage co-culture model. Nanocomposite reinforced fibroin scaffold can be tailored further to accommodate different requirements depending on bone type or bone regeneration period.

  7. Nano polypeptide particles reinforced polymer composite fibers.

    PubMed

    Li, Jiashen; Li, Yi; Zhang, Jing; Li, Gang; Liu, Xuan; Li, Zhi; Liu, Xuqing; Han, Yanxia; Zhao, Zheng

    2015-02-25

    Because of the intensified competition of land resources for growing food and natural textile fibers, there is an urgent need to reuse and recycle the consumed/wasted natural fibers as regenerated green materials. Although polypeptide was extracted from wool by alkaline hydrolysis, the size of the polypeptide fragments could be reduced to nanoscale. The wool polypeptide particles were fragile and could be crushed down to nano size again and dispersed evenly among polymer matrix under melt extrusion condition. The nano polypeptide particles could reinforce antiultraviolet capability, moisture regain, and mechanical properties of the polymer-polypeptide composite fibers.

  8. A study on flammability and moisture absorption behavior of sisal/coir fiber reinforced hybrid composites

    NASA Astrophysics Data System (ADS)

    Akash; Girisha, K. G.; Venkatesha Gupta, N. S.; Sreenivas Rao, K. V.

    2017-04-01

    Cellulosic fiber reinforced Polymer Matrix Composites (PMC’s) are more frequently applied in construction industry and transportation, in which their flammability and water absorption behaviors are important. Fire resistance of cellulosic fiber reinforced composites is important parameter that often limits the application of composites in a given area. This work presents experimental results of a fire retardant behavior and moisture absorption behavior of different weight percentage (10, 20, 30, 40 and 50 wt. %) of sisal/coir fiber reinforced epoxy resin hybrid composites. Traditional cold pressing method was used to fabricate hybrid composites. Flammability behavior of the hybrid composite was studied by using vertical and horizontal burning rates as per standard UL-94. Addition of the cellulosic fiber increases the flammability since natural fiber supports fire. It proves as a bad flame retardant due to the generation of a surface layer during pyrolysis of the cellulosic fiber which exhibits poor fire retardant nature. This layer acts as supporter of fire, which spreads the heat from being transferred to the un-pyrolised material. The speed of flame is much faster in vertical burning position compared to horizontal burning position due to preheating of the specimen. Moisture absorption of sisal/coir fiber reinforced epoxy resin hybrid composites are studied according to ISO 62:1999 standard procedure. Absorption of moisture increases with increasing in the reinforcement weight percentage of cellulosic fiber in fabricated hybrid composite.

  9. Starch composites reinforced by bamboo cellulosic crystals.

    PubMed

    Liu, Dagang; Zhong, Tuhua; Chang, Peter R; Li, Kaifu; Wu, Qinglin

    2010-04-01

    Using a method of combined HNO(3)-KClO(3) treatment and sulfuric acid hydrolysis, bamboo cellulose crystals (BCCs) were prepared and used to reinforce glycerol plasticized starch. The structure and morphology of BCCs were investigated using X-ray diffraction, electron microscopy, and solid-state (13)C NMR. Results showed that BCCs were of typical cellulose I structure, and the morphology was dependent on its concentration in the suspension. BCC of 50-100 nm were assembled into leaf nervations at low concentration (i.e. 0.1 wt.% of solids), but congregated into a micro-sized "flower" geometry at high concentration (i.e. 10.0 wt.% of solids). Tensile strength and Young's modulus of the starch/BCC composite films (SBC) were enhanced by the incorporation of the crystals due to reinforcement of BCCs and reduction of water uptake. BCCs at the optimal 8% loading level exhibited a higher reinforcing efficiency for plasticized starch plastic than any other loading level.

  10. Nanostructured metal composites reinforced with fullerenes

    NASA Astrophysics Data System (ADS)

    Robles-Hernández, Francisco C.; Calderon, H. A.

    2010-02-01

    This work presents the results of the characterization of nanostructured Al or Fe matrix composites reinforced with fullerenes. The fullerene used is a mix of 15 wt%C60, 5 wt.%C70, and 80 wt.% soot that is the product of the primary synthesis of C60. The composites were produced by mechanical alloying and sintered by spark plasma sintering (SPS). It was found that in both composites, C60 withstands mechanical alloying, and acts as a control agent, reducing the agglomeration of the particles. In both composite systems the as-mechanically alloyed powders as well as the SPS sintered products are nanostructured. During the SPS process the effect of the metal (Al or Fe) matrix with the fullerene is different for each composite. For instance, Al reacts with all the carbon in the fullerene mix and forms Al4C3; on the contrary, in the Fe-fullerene composite, Fe sponsors the synthesis of C60 during the SPS process. The synthesis of the C60 is presumably assisted by the catalytic nature of Fe and the electric field generated during the SPS sintering process.

  11. Short fiber-reinforced cementitious composites manufactured by extrusion technology

    NASA Astrophysics Data System (ADS)

    Mu, Bin

    The use of short fibers in the cement-based composites is more preferable due to the simplicity and economic nature in fabrication. The short fiber-reinforced cementitious composite (SFRCC) manufactured by the extrusion method show a great improvement in both strength and toughness as compared to the fiber-reinforced composites made by traditional casting methods. This improvement can be attributed to the achievement of low porosity and good interfacial bond in SFRCC under high shear and compressive stress during the extrusion process. In the present study, products of cylinders, sheets, pipes and honeycomb panels incorporating various mineral admixtures such as slag, silica fume, and metakaolin have been manufactured by the extrusion technology. Two kinds of short fibers, ductile polyvinyl alcohol (PVA) fibers and stronger but less ductile glass fibers, were used as the reinforcement in the products. After the specimens were extruded, tension, bending and impact tests were performed to study the mechanical properties of these products. The rheology test was performed for each mix to determine its viscoelastic properties. In addition, X-ray diffraction (XRD) and scanning electronic microscopy (SEM) technology were employed to get an insight view of the mechanism. A freezing and thawing experiment (ASTM C666) was also carried to investigate the durability of the specimens. Based on these experimental results, the reinforcing behaviors of these two short fibers were investigated. The enhancing effects of silica fume and metakaolin on the extrudates were compared and discussed. Finally, the optimum amount of silica fume and slag was proposed. Since the key point for a successful extrusion is the properly designed rheology which controls both internal and external flow properties of extrudate, a nonlinear viscoelastic model was applied to investigate the rheological behavior of a movable fresh cementitious composite in an extruder channel. The velocity profile of the

  12. 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.

  13. Synthesis And Characterization Of Reduced Size Ferrite Reinforced Polymer Composites

    SciTech Connect

    Borah, Subasit; Bhattacharyya, Nidhi S.

    2008-04-24

    Small sized Co{sub 1-x}Ni{sub x}Fe{sub 2}O{sub 4} ferrite particles are synthesized by chemical route. The precursor materials are annealed at 400, 600 and 800 C. The crystallographic structure and phases of the samples are characterized by X-ray diffraction (XRD). The annealed ferrite samples crystallized into cubic spinel structure. Transmission Electron Microscopy (TEM) micrographs show that the average particle size of the samples are <20 nm. Particulate magneto-polymer composite materials are fabricated by reinforcing low density polyethylene (LDPE) matrix with the ferrite samples. The B-H loop study conducted at 10 kHz on the toroid shaped composite samples shows reduction in magnetic losses with decrease in size of the filler sample. Magnetic losses are detrimental for applications of ferrite at high powers. The reduction in magnetic loss shows a possible application of Co-Ni ferrites at high microwave power levels.

  14. Ceramic composites reinforced with modified silicon carbide whiskers

    DOEpatents

    Tiegs, Terry N.; Lindemer, Terrence B.

    1990-01-01

    Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

  15. 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.

  16. 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.

  17. Fabrication of composite spray powders using reaction synthesis

    SciTech Connect

    Shaw, K.G.; McCoy, K.P.; Trogolo, J.A.

    1994-12-31

    Intermetallic composite powders including up to 30 volume percent ceramic reinforcing phase have been fabricated without using binders by reaction synthesis. The mechanics of the process are discussed as related to the necessary reaction ignition condition. A detailed mechanism of the reaction and incorporation of the reinforcing phase is presented based on electron microscopy and thermodynamic calculations. The structure of NiAl-Al{sub 2}O{sub 3} composite powders and plasma sprayed coatings are reported. it is shown that uniform lamellar intermetallic composites with sub-micrometer features may be formed by spraying these powders using a single gun geometry. These materials may be useful in the formation of functionally gradient intermetallic-ceramic structures.

  18. Woven glass fabric reinforced laminates based on polyolefin wastes: Thermal, mechanical and dynamic-mechanical properties

    NASA Astrophysics Data System (ADS)

    Russo, Pietro; Acierno, Domenico; Simeoli, Giorgio; Lopresto, Valentina

    2014-05-01

    Potentialities of polyolefin wastes in place of virgin polypropylene to produce composite laminates have been investigated. Plaques reinforced with a woven glass fabric were prepared by film-stacking technique and systematically analyzed in terms of thermal, mechanical and dynamic-mechanical properties. In case of PP matrices, the use of a typical compatibilizer to improve the adhesion at the interface has been considered. Thermal properties emphasized the chemical nature of plastic wastes. About mechanical properties, static tests showed an increase of flexural parameters for compatibilized systems due to the coupling effect between grafted maleic anhydride and silane groups on the surface of the glass fabric. These effects, maximized for composites based on car bumper wastes, is perfectly reflected in terms of storage modulus and damping ability of products as determined by single-cantilever bending dynamic tests.

  19. Fiber-reinforced composite fixed dental prostheses with various pontics.

    PubMed

    Perea, Leila; Matinlinna, Jukka P; Tolvanen, Mimmi; Lassila, Lippo V; Vallittu, Pekka K

    2014-04-01

    To evaluate the load-bearing capacities of fiber-reinforced composite (FRC) fixed dental prostheses (FDP) with pontics of various materials and thicknesses. Inlay preparations for retaining FDPs were made in a polymer phantom model. Seventy-two FDPs with frameworks made of continuous unidirectional glass fibers (everStick C&B) were fabricated. Three different pontic materials were used: glass ceramics, polymer denture teeth, and composite resin. The FDPs were divided into 3 categories based on the occlusal thicknesses of the pontics (2.5 mm, 3.2 mm, and 4.0 mm). The framework's vertical positioning varied respectively. Each pontic material category contained 3 groups (n = 8/group). In group 1, pontics were fabricated conventionally with composite resin (G-ӕnial, GC) with one additional transversal fiber reinforcement. In group 2, the pontics were polymer denture teeth (Heraeus- Kulzer). Group 3 had an IPS-Empress CAD pontic (Ivoclar Vivadent) milled using a Cerec CAD/CAM unit. Groups 1 and 2 served as controls. Each FDP was statically loaded from the pontic until initial fracture (IF) and final fracture (FF). Initial-fracture data were collected from the load-deflection graph. ANOVA indicated statistically significant differences between the materials and occlusal thicknesses (p < 0.001). Quadratic analysis demonstrated the highest correlation between the thickness of the pontic and IF and FF values with ceramic pontics (IF: p < 0.001; R2 = 0.880; FF: p < 0.001; R2 = 0.953). By increasing the occlusal thickness of the pontic, the load-bearing capacity of the FRC FDPs may be increased. The highest load-bearing capacity was obtained with 4.0 mm thickness in the ceramic pontic. However, with thinner pontics, polymer denture teeth and composite pontics resulted in higher load-bearing values.

  20. High elastic modulus nanopowder reinforced resin composites for dental applications

    NASA Astrophysics Data System (ADS)

    Wang, Yijun

    2007-12-01

    Dental restorations account for more than $3 billion dollars a year on the market. Among them, all-ceramic dental crowns draw more and more attention and their popularity has risen because of their superior aesthetics and biocompatibility. However, their relatively high failure rate and labor-intensive fabrication procedure still limit their application. In this thesis, a new family of high elastic modulus nanopowder reinforced resin composites and their mechanical properties are studied. Materials with higher elastic modulus, such as alumina and diamond, are used to replace the routine filler material, silica, in dental resin composites to achieve the desired properties. This class of composites is developed to serve (1) as a high stiffness support to all-ceramic crowns and (2) as a means of joining independently fabricated crown core and veneer layers. Most of the work focuses on nano-sized Al2O3 (average particle size 47 nm) reinforcement in a polymeric matrix with 50:50 Bisphenol A glycidyl methacrylate (Bis-GMA): triethylene glycol dimethacrylate (TEGDMA) monomers. Surfactants, silanizing agents and primers are examined to obtain higher filler levels and enhance the bonding between filler and matrix. Silane agents work best. The elastic modulus of a 57.5 vol% alumina/resin composite is 31.5 GPa compared to current commercial resin composites with elastic modulus <15 GPa. Chemical additives can also effectively raise the hardness to as much as 1.34 GPa. Besides>alumina, diamond/resin composites are studied. An elastic modulus of about 45 GPa is obtained for a 57 vol% diamond/resin composite. Our results indicate that with a generally monodispersed nano-sized high modulus filler, relatively high elastic modulus resin-based composite cements are possible. Time-dependent behavior of our resin composites is also investigated. This is valuable for understanding the behavior of our material and possible fatigue testing in the future. Our results indicate that with

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

  2. Preparation and properties of cellulose nanocrystals reinforced collagen composite films.

    PubMed

    Li, Weichang; Guo, Rui; Lan, Yong; Zhang, Yi; Xue, Wei; Zhang, Yuanming

    2014-04-01

    Collagen films have been widely used in the field of biomedical engineering. However, the poor mechanical properties of collagen have limited its application. Here, rod-like cellulose nanocrystals (CNCs) were fabricated and used to reinforce collagen films. A series of collagen/CNCs films were prepared by collagen solution with CNCs suspensions homogeneously dispersed at CNCs: collagen weight ratios of 1, 3, 5, 7, and 10. The morphology of the resulting films was analyzed by scanning electron microscopy (SEM), the enhancement of the thermomechanical properties of the collagen/CNCs composites were demonstrated by thermal gravimetric analysis (TGA) and mechanical testing. Among the CNCs contents used, a loading of 7 wt % led to the maximum mechanical properties for the collagen/CNCs composite films. In addition, in vitro cell culture studies revealed that the CNCs have no negative effect on the cell morphology, viability, and proliferation and possess good biocompatibility. We conclude that the incorporation of CNCs is a simple and promising way to reinforce collagen films without impairing biocompatibility. This study demonstrates that the composite films show good potential for use in the field of skin tissue engineering. Copyright © 2013 Wiley Periodicals, Inc.

  3. Dynamic Mechanical Behavior of Nickel-Aluminum Reinforced Epoxy Composites

    NASA Astrophysics Data System (ADS)

    Martin, Morgana; Hanagud, Sathyanaraya; Thadhani, Naresh

    2005-07-01

    Epoxy-based composites reinforced with a mixture of micron-sized Ni and micron or nano-sized Al powders were fabricated as bulk materials by cast/curing. The structural/mechanical behavior of these materials was evaluated using elastic and plastic property measurements via static and dynamic compression tests performed on rod shaped samples. Reverse Taylor anvil-on-rod impact tests combined with velocity interferometry gave qualitative and quantitative information about the transient deformation and failure response of the composites. The material containing 20wt% epoxy and nano-sized Al powder showed the most superior mechanical properties in terms of elastic modulus, and static and dynamic compressive strength, and strain before fracture, as compared to the other reinforced cast materials. The results illustrate that nano-sized Al particles provide significant enhancement to strength of epoxy composites by dispersing in the epoxy and generating a nano-Al containing epoxy matrix with embedded Ni particles. Funding for this research was provided by AFOSR/MURI Grant No. F49620-02-1-0382.

  4. Reinforced cementitous composite with in situ shrinking microfibers

    NASA Astrophysics Data System (ADS)

    Kim, Eric S.; Lee, Jason K.; Lee, Patrick C.; Huston, Dryver R.; Tan, Ting; Al-Ghamdi, Saleh

    2017-03-01

    This paper describes an innovative fiber reinforcement technology for cementitious composite structures that employs in situ shrinking microfibers to provide supplemental strength-enhancing compressive stresses. Reinforced concrete is one of the most commonly used structural materials in construction industry, primarily due to its cost, durability, ability to be easily fabricated into a variety of shapes on site, and locally abundant raw material availability almost everywhere. Unlike incumbent passive reinforcing microfiber technology, in situ shrinking microfibers that respond to an in situ stimulus such as heat, pH, or moisture variations can induce pre-compression to matrix and create additional resistance from external loads, creating stronger composite structures. In this paper, heat-activated-shrinking (HAS) microfibers made from polyolefin, and pH-activated-shrinking (pHAS) microfibers made from chitosan powder were used to study effects of shrinking microfiber reinforcing in concrete. Shrinking ratios and tensile strengths of both microfibers were measured. Cementitious specimens with active shrinking microfibers, passive non shrinking fibers, as well as control samples were made. Mechanical properties of the samples were compared with compression and three-point bending tests. The optimum microfiber weight percentages for HAS microfibers were 0.5 wt% in compression tests, and 1.0 wt% in three-point bending tests. For pHAS microfibers, the optimum weight percentages were 0.5 wt% in three-point bending tests. Compared to heat passive microfibers specimens, 45% increase in the maximum compression strengths, and 124% increase in the maximum bending strengths were achieved at the optimum weight percentages of HAS microfibers. In addition, with 0.5 wt% of pHAS microfibers, 145% increase in the maximum bending strengths of three-point bending tests resulted compared to pH passive microfibers specimens.

  5. Fuselage structure using advanced technology fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Robinson, R. K.; Tomlinson, H. M. (Inventor)

    1982-01-01

    A fuselage structure is described in which the skin is comprised of layers of a matrix fiber reinforced composite, with the stringers reinforced with the same composite material. The high strength to weight ratio of the composite, particularly at elevated temperatures, and its high modulus of elasticity, makes it desirable for use in airplane structures.

  6. Damage Detection in Composite Interfaces through Carbon Nanotube Reinforcement

    DTIC Science & Technology

    2010-02-12

    63 iv B. RESISTANCE MEASUREMENTS FOR CARBON FIBER COMPOSITES WITH AND WITHOUT...CNT REINFORCEMENT ......................................64 C. CRITICAL STRAIN ENERGY RELEASE RATES FOR CARBON FIBER COMPOSITES WITH AND WITHOUT CNT...68 G. PHASE V RESISTANCE TESTING FOR CARBON FIBER COMPOSITES WITH CNT REINFORCEMENT

  7. Interface characteristics of nanorope reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Ahmed, Khondaker S.; Keng, Ang K.

    2013-09-01

    A shear-lag model is proposed to obtain interface characteristics of nanorope reinforced polymer composites using representative volume element (RVE) concept. In the axisymmetric RVE, the nanorope is modelled as a closed-packed cylindrical lattice consisting seven single-walled carbon nanotubes. In the model, rope is considered to be perfectly bonded with the polymer resin where the nanotubes are assumed to be chemically non-bonded with each other in the rope system. Since, nanotubes are considered to be non-bonded in the nanorope there must exist a van der Waals interaction in terms of Lennard-Jones potential. A separate model is also proposed to determine the cohesive stress caused by this interaction. Closed form analytical solutions are derived for stress components of rope, resin and individual carbon nanotubes in the rope system. Parametric study has also been conducted to investigate the influences of key composite factors involved at both perfectly bonded and non-bonded interfaces.

  8. Fibre reinforced composites in aircraft construction

    NASA Astrophysics Data System (ADS)

    Soutis, C.

    2005-02-01

    Fibrous composites have found applications in aircraft from the first flight of the Wright Brothers’ Flyer 1, in North Carolina on December 17, 1903, to the plethora of uses now enjoyed by them on both military and civil aircrafts, in addition to more exotic applications on unmanned aerial vehicles (UAVs), space launchers and satellites. Their growing use has risen from their high specific strength and stiffness, when compared to the more conventional materials, and the ability to shape and tailor their structure to produce more aerodynamically efficient structural configurations. In this paper, a review of recent advances using composites in modern aircraft construction is presented and it is argued that fibre reinforced polymers, especially carbon fibre reinforced plastics (CFRP) can and will in the future contribute more than 50% of the structural mass of an aircraft. However, affordability is the key to survival in aerospace manufacturing, whether civil or military, and therefore effort should be devoted to analysis and computational simulation of the manufacturing and assembly process as well as the simulation of the performance of the structure, since they are intimately connected.

  9. Trans-Laminar-Reinforced (TLR) Composites

    NASA Technical Reports Server (NTRS)

    Hinders, Mark; Dickinson, Larry

    1997-01-01

    A Trans-Laminar-Reinforced (TLR) composite is defined as composite laminate with up to five percent volume of fibrous reinforcement oriented in a 'trans-laminar' fashion in the through-thickness direction. The TLR can be continuous threads as in 'stitched laminates', or it can be discontinuous rods or pins as in 'Z-Fiber(TM) materials. It has been repeatedly documented in the literature that adding TLR to an otherwise two dimensional laminate results in the following advantages: substantially improved compression-after-impact response; considerably increased fracture toughness in mode 1 (double cantilever beam) and mode 2 (end notch flexure); and severely restricted size and growth of impact damage and edge delamination. TLR has also been used to eliminate catastrophic stiffener disbonding in stiffened structures. TLR directly supports the 'Achilles heel' of laminated composites, that is delamination. As little as one percent volume of TLR significantly alters the mechanical response of laminates. The objective of this work was to characterize the effects of TLR on the in-plane and inter-laminar mechanical response of undamaged composite laminates. Detailed finite element models of 'unit cells', or representative volumes, were used to study the effects of adding TLR on the elastic constants; the in-plane strength; and the initiation of delamination. Parameters investigated included TLR material, TLR volume fraction, TLR diameter, TLR through-thickness angle, ply stacking sequence, and the microstructural features of pure resin regions and curved in-plane fibers. The work was limited to the linear response of undamaged material with at least one ply interface. An inter-laminar dominated problem of practical interest, a flanged skin in bending, was also modeled.

  10. Fiber-Reinforced Polymer Composite Materials Systems to Enhance Reinforced Concrete Structures

    DTIC Science & Technology

    1998-02-01

    and low temperature evaluation of FRP performance. Field demonstrations included evaluation of carbon fiber reinforced polymer tendons for post...glass fiber reinforced polymer cables as tie back tension members, and a test fixture was designed and fabricated to evaluate post stressing tendon

  11. 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.

  12. Effects of Fiber Coating Composition on Mechanical Behavior of Silicon Carbide Fiber-Reinforced Celsian Composites

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Elderidge, Jeffrey I.

    1998-01-01

    Celsian matrix composites reinforced with Hi-Nicalon fibers, precoated with a dual layer of BN/SiC by chemical vapor deposition in two separate batches, were fabricated. Mechanical properties of the composites were measured in three-point flexure. Despite supposedly identical processing, the composite panels fabricated with fibers coated in two batches exhibited substantially different mechanical behavior. The first matrix cracking stresses (sigma(sub mc)) of the composites reinforced with fibers coated in batch 1 and batch 2 were 436 and 122 MPa, respectively. This large difference in sigma(sub mc) was attributed to differences in fiber sliding stresses(tau(sub friction)), 121.2+/-48.7 and 10.4+/-3.1 MPa, respectively, for the two composites as determined by the fiber push-in method. Such a large difference in values of tau(sub friction) for the two composites was found to be due to the difference in the compositions of the interface coatings. Scanning Auger microprobe analysis revealed the presence of carbon layers between the fiber and BN, and also between the BN and SiC coatings in the composite showing lower tau(sub friction). This resulted in lower sigma(sub mc) in agreement with the ACK theory. The ultimate strengths of the two composites, 904 and 759 MPa, depended mainly on the fiber volume fraction and were not significantly effected by tau(sub friction) values, as expected. The poor reproducibility of the fiber coating composition between the two batches was judged to be the primary source of the large differences in performance of the two composites.

  13. 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.

  14. 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.

  15. Method of Fabricating Chopped-Fiber Composite Piston

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    A three-dimensional piston molding is fabricated from a mixture of chopped, carbon tow filaments of variable length, which are prepregged with carbonaceous organic resins and/or pitches and molded by conventional molding processes into a near net shape, to form a carbon-fiber reinforced organic-matrix composite part. Continuous reinforcement in the form of carbon-carbon composite tapes or pieces of fabric can be also laid in the mold before or during the charging of the mold with the chopped-fiber mixture, to enhance the strength in the crown and wrist-pin areas. The molded chopped-fiber reinforced organic-matrix composite parts are then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. These pyrolized parts are then densified by reimpregnation with resins or pitches, which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston molds are machined to final piston dimensions, and piston ring grooves are added. To prevent oxidation and/or to seal the piston surface or near surface, the chopped-fiber piston is coated with ceramic and/or metallic sealants: and/or coated with a catalyst.

  16. Well-aligned cellulose nanofiber-reinforced polyvinyl alcohol composite film: Mechanical and optical properties.

    PubMed

    Cai, Jie; Chen, Jingyao; Zhang, Qian; Lei, Miao; He, Jingren; Xiao, Anhong; Ma, Chengjie; Li, Sha; Xiong, Hanguo

    2016-04-20

    Uniaxially aligned cellulose nanofibers (CNFs), which are fabricated by electrospinning of cellulose acetate derived from bamboo cellulose (B-CA) followed by deacetylation, were used as reinforcements to make optically transparent composite films. We examined the effects of B-CA concentration and electrospinning parameters (e.g. spinning distance, and collection speed) on fiber morphology and orientation, which act on mechanical-to-optical properties of the CNFs-reinforced composites. Consequently, the resultant composite film exhibits high visible-light transmittance even with high fiber content, as well as improved mechanical properties. The understanding obtained from this study may facilitate the development of novel nanofibrous materials for various optical uses.

  17. Extrinsic toughening of discontinuously reinforced aluminum composites

    NASA Astrophysics Data System (ADS)

    Ellis, Lisa Yost

    Discontinuously reinforced aluminum (DRA) composites can exhibit desirable specific stiffness and strength properties as compared to monolithic aluminum alloys. Unfortunately, the addition of ceramic particulates to the aluminum matrix results in decreased fracture resistance. In this dissertation, DRA composites containing discrete regions of unreinforced aluminum (where these unreinforced aluminum regions are subsequently referred to as 'ductile phase' regions or DP regions) were studied with the objective of enhancing damage tolerance compared to the conventional DRA composite. The effects of 'ductile phase' size, shape and mechanical properties as well as the SiCp reinforcement distribution on crack initiation and growth were examined. The incorporation of properly selected DP regions can result in increased crack growth resistance of the DRA composite under monotonic loading conditions. In such cases, stable crack propagation (i.e. R-curve behavior) was observed in contrast to the behavior of the conventional DRA composite which failed catastrophically at about 20 MPasurdm. Increased size and ductility of the 'ductile phase' resulted in improved toughness over the range tested. For instance, materials with small DP regions (10-60 mum in thickness) did not show improvements in fracture toughness compared to the conventional composites while those materials containing large DP regions (80-400 mum in thickness) demonstrated stable crack propagation at elevated levels of stress intensity. The details of the R-curve as well as the dominant toughening mechanisms were also affected by test geometry (i.e. crack arrestor vs. crack divider). In the crack arrestor orientation, toughening was associated primarily with the renucleation of the crack across the DP regions, provided the DP regions possessed sufficient ductility. Apparent stress intensities of 30-50 MPasurdm resulted. In the crack divider orientation, rising R-curves resulted from the bridging action of

  18. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    NASA Technical Reports Server (NTRS)

    Cox, Sarah B.; Lui, Donovan; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, which allows a shape to be formed prior to the cure, and is then pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Basalt fibers are used for the reinforcement in the composite system. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material.

  19. Design and Fabrication of E-Glass /carbon/graphite epoxy hybrid composite leaf spring

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, T.; Raja, M.; Jothi Prakash, V. M.; Gnanavel, C.

    2017-03-01

    The Automobile Industry has shown increase interest for replacement of steel leaf spring with that of composite leaf spring. Substituting composite materials for conventional metallic materials has many advantages because of higher specific stiffness, strength and fatigue resistance etc. This work deals with the replacement of conventional steel leaf spring with a hybrid Composite leaf spring using E -Glass/Carbon/Graphite/Epoxy. The hybrid composite is obtained by introducing more than one fiber in the reinforcement phase. The hybrid composite is fabricated by the vacuum bag technique. The result shows that introduction of carbon and graphite fiber in the reinforcement phase increases the stiffness of the composite.

  20. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    NASA Astrophysics Data System (ADS)

    McCool, Raurí; Murphy, Adrian; Wilson, Ryan; Jiang, Zhenyu; Price, Mark

    2011-05-01

    The introduction of new materials, particularly for aerospace products, is not a simple, quick or cheap task. New materials require extensive and expensive qualification and must meet challenging strength, stiffness, durability, manufacturing, inspection and maintenance requirements. Growth in industry acceptance for fibre reinforced thermoplastic composite systems requires the determination of whole life attributes including both part processing and processed part performance data. For thermoplastic composite materials the interactions between the processing parameters, in-service structural performance and end of life recyclability are potentially interrelated. Given the large number and range of parameters and the complexity of the potential relationships, understanding for whole life design must be developed in a systematic building block approach. To assess and demonstrate such an approach this article documents initial coupon level thermoforming trials for a commercially available fibre reinforced thermoplastic laminate, identifying the key interactions between processing and whole life performance characteristics. To examine the role of the thermoforming process parameters on the whole life performance characteristics of the formed part requires a series of manufacturing trials combined with a series of characterisation tests on the manufacturing trial output. Using a full factorial test programme and considering all possible process parameters over a range of potential magnitudes would result in a very large number of manufacturing trials and accompanying characterisation tests. Such an approach would clearly be expensive and require significant time to complete, therefore failing to address the key requirement for a future design methodology capable of rapidly generating design knowledge for new materials and processes. In this work the role of mould tool temperature and blank forming temperature on the thermoforming of a commercially available

  1. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    SciTech Connect

    McCool, Rauri; Murphy, Adrian; Wilson, Ryan; Jiang Zhenyu; Price, Mark

    2011-05-04

    The introduction of new materials, particularly for aerospace products, is not a simple, quick or cheap task. New materials require extensive and expensive qualification and must meet challenging strength, stiffness, durability, manufacturing, inspection and maintenance requirements. Growth in industry acceptance for fibre reinforced thermoplastic composite systems requires the determination of whole life attributes including both part processing and processed part performance data. For thermoplastic composite materials the interactions between the processing parameters, in-service structural performance and end of life recyclability are potentially interrelated. Given the large number and range of parameters and the complexity of the potential relationships, understanding for whole life design must be developed in a systematic building block approach. To assess and demonstrate such an approach this article documents initial coupon level thermoforming trials for a commercially available fibre reinforced thermoplastic laminate, identifying the key interactions between processing and whole life performance characteristics. To examine the role of the thermoforming process parameters on the whole life performance characteristics of the formed part requires a series of manufacturing trials combined with a series of characterisation tests on the manufacturing trial output. Using a full factorial test programme and considering all possible process parameters over a range of potential magnitudes would result in a very large number of manufacturing trials and accompanying characterisation tests. Such an approach would clearly be expensive and require significant time to complete, therefore failing to address the key requirement for a future design methodology capable of rapidly generating design knowledge for new materials and processes. In this work the role of mould tool temperature and blank forming temperature on the thermoforming of a commercially available

  2. Thermal cycling of tungsten-fibre-reinforced superalloy composites

    NASA Technical Reports Server (NTRS)

    Wetherhold, Robert C.; Westfall, Leonard J.

    1988-01-01

    The thermal cycling of a tungsten-fiber-reinforced superalloy (TFRS) composite is typical of its application in high-temperature engine environments. The mismatch in thermal expansion coefficients between fiber and matrix causes substantial longitudinal (0 deg) stresses in the composite, which can produce inelastic damage-producing matrix strains. The case of thermal fatigue is explored as a "worst case" of the possible matrix damage, in comparison with specimens which are also mechanically loaded in tension. The thermally generated cyclic stresses and the attendant matrix plasticity may be estimated using a nonlinear finite-element program, by proposing a physical analog to the micromechanics equations. A damage metric for the matrix is proposed using the Coffin-Manson criterion, which metric can facilitate comparisons of damage among different candidate materials, and also comparisons for a given material subjected to different temperature cycles. An experimental program was carried out for thermal cycling of a 37 vol pct TFRS composite to different maximum temperatures. The results confirm the prediction that thermal cycling produces matrix degradation and composite strength reduction, which become more pronounced with increasing maximum cyclic temperature. The strength of the fiber is shown to be identical for the as-fabricated and thermally cycled specimens, suggesting that the reduction in composite strength is due to the loss of matrix contribution and also to notching effects of the matrix voids on the fiber.

  3. 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.

  4. Tribological behaviour of unidirectional carbon fibre-reinforced epoxy composites

    NASA Astrophysics Data System (ADS)

    Şahin, Y.; De Baets, P.

    2017-02-01

    Tribological behaviour of unidirectional carbon fibre-reinforced epoxy composites containing 42wt.% (CU42) and 52wt.% (CU52) carbon fibres fabricated by moulding technique was investigated on a pin-on-flat plate configuration. It is the first time to measure static and dynamic coefficient of frictions and wear rates of epoxy composites under heavy loading conditions. Microstructures of composites were examined by scanning electron microscopy (SEM). The experimental results indicated the carbon fiber improved the tribological properties of thermoset epoxy by reducing wear rate, but increased the coefficient of friction. At higher load, average wear rates were about 10.8x10-5 mm3/N.m for composites while it was about 38.20x10-5 mm3/N.m for epoxy resin. The wear rate decreased with decreasing load while friction coefficient increased with decreasing load. Moreover, friction coefficient of composites of CU42 tested at 90 N load was measured to be in the range 0.35 and 0.13 for static and dynamic component, respectively.

  5. Improved Mechanical Properties of Various Fabric-Reinforced Geocomposite at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Samal, Sneha; Phan Thanh, Nhan; Petríková, Iva; Marvalová, Bohadana

    2015-07-01

    This article signifies the improved performance of the various types of fabric reinforcement of geopolymer as a function of physical, thermal, mechanical, and heat-resistant properties at elevated temperatures. Geopolymer mixed with designed Si:Al ratios of 15.6 were synthesized using three different types of fabric reinforcement such as carbon, E-glass, and basalt fibers. Heat testing was conducted on 3-mm-thick panels with 15 × 90 mm surface exposure region. The strength of carbon-based geocomposite increased toward a higher temperature. The basalt-reinforced geocomposite strength decreased due to the catastrophic failure in matrix region. The poor bridging effect and dissolution of fabric was observed in the E-glass-reinforced geocomposite. At an elevated temperature, fiber bridging was observed in carbon fabric-reinforced geopolymer matrix. Among all the fabrics, carbon proved to be suitable candidate for the high-temperature applications in thermal barrier coatings and fire-resistant panels.

  6. Improvement in mechanical properties of glass fiber fabric/PVC composites with chopped glass fibers and coupling agent

    NASA Astrophysics Data System (ADS)

    Lee, Jaewoong; Park, Su Bin; Lee, Joon Seok; Kim, Jong Won

    2017-07-01

    Glass fiber reinforced polyvinylchloride (PVC) composite is used widely because of its low price, chemical resistance, and dimensional stability, but most are short fiber reinforced PVC composites. Fabric reinforced composite have undulated regions, which is the only region without fiber, due to the characteristics of the weave construction, and it limits increasing the mechanical properties. Therefore, in this study, to increase the mechanical properties, the undulated regions of the glass fiber fabric/PVC composite were filled with a silane coupling agent treated chopped fiber. The physical properties, dynamic mechanical thermal properties, and mechanical properties of the prepared composite were observed. The critical fiber aspect ratio of the chopped fiber is different for each mechanical property. This shows that the fabric-reinforced composite of chopped fibers affect each of the mechanical properties differently. In addition, the silane coupling treatment increases the compatibility of the composite components, improving the mechanical properties.

  7. Feasibility and Manufacturing Considerations of Hemp Textile Fabric Utilized in Pre-Impregnated Composites

    NASA Astrophysics Data System (ADS)

    Osusky, Gregory

    This study investigates the fabrication and mechanical properties of semicontinuous, hemp fiber reinforced thermoset composites. This research determines if off-the-shelf refined woven hemp fabric is suitable as composite reinforcement using resin pre-impregnated method. Industrial hemp was chosen for its low cost, low resource input as a crop, supply chain from raw product to refined textile and biodegradability potential. Detail is placed on specimen fabrication considerations. Lab testing of tension and compression is conducted and optimization considerations are examined. The resulting composite is limited in mechanical properties as tested. This research shows it is possible to use woven hemp reinforcement in pre-impregnated processed composites, but optimization in mechanical properties is required to make the process commercially practical outside niche markets.

  8. [Fiber-reinforced composite in fixed prosthodontics].

    PubMed

    Pilo, R; Abu Rass, Z; Shmidt, A

    2010-07-01

    Fiber reinforced composite (FRC) is composed of resin matrix and fibers filler. Common types of fibers: polyethylene, carbon and glass. Fibers can be continuous and aligned, discontinuous and aligned, discontinuous and randomly oriented. The architecture of the fibers is unidirectional, woven or braided. The two main types are: dry fibers or impregnated. Inclusion of fibers to resin composite increased its average flexural strength in 100-200 MPa. FRC can be utilized by the dentist in direct approach (splinting, temporary winged bridge) or indirect approach (laboratory made fixed partial denture). Laboratory fixed partial denture (FPD) is made from FRC substructure and Hybrid/Microfill particulate composite veneer. Main indications: interim temporary FPD or FPD in cases of questionable abutment teeth, in aesthetic cases where All Ceram FPD is not feasible. Retention is attained by adhesive cementation to minimally prepared teeth or to conventionally prepared teeth; other options are inlay-onlay bridges or hybrid bridges. Contraindications are: poor hygiene, inability to control humidity, parafunction habits, and more than two pontics. Survival rate of FRC FPD over 5 years is 75%, lower compared to porcelain fused to metal FPD which is 95%. Main reasons for failure are: fracture of framework and delamination of the veneer. Part of the failures is repairable.

  9. Processing and characterization of natural fiber reinforced thermoplastic composites using micro-braiding technique

    NASA Astrophysics Data System (ADS)

    Kobayashi, Satoshi; Ogihara, Shinji

    In the present study, we investigate fatigue properties of green composites. A hemp fiber yarn reinforced poly(lactic acid) composite was selected as a green composite. Unidirectional (UD) and textile (Textile) composites were fabricated using micro-braiding technique. Fatigue tests results indicated that fatigue damages in UD composites was splitting which occurred just before the final fracture, while matrix crack and debonding between matrix and fiber yarn occurred and accumulated stably in Textile composites. These results were consistent with modulus reduction and acoustic emission measurement during fatigue tests.

  10. Wear Performance of A356 Matrix Composites Reinforced with Different Types of Reinforcing Particles

    NASA Astrophysics Data System (ADS)

    Akbari, Mostafa; Shojaeefard, Mohammad Hasan; Asadi, Parviz; Khalkhali, Abolfazl

    2017-09-01

    To improve the wear resistance of Al-Si alloys, different types of reinforcing particles such as SiC, TiC, ZrO2, and B4C were used to produce matrix composites by friction stir processing (FSP). First, microstructural properties of different locations of stir zone (SZ) in the FSPed specimens such as advancing side, retreating side, shoulder-affected area, and pin-affected area were investigated. The results demonstrate that Si particles size is not the same in different SZ subdomains. SEM investigation was performed in order to investigate the particles distribution in different areas of the SZ as well as bonding quality between particles and metal matrix. Hardness and wear tests were carried out to determine mechanical and wear properties of the composites. The pin-on-disk wear tests were performed at room temperature, with the normal applied loads of 5, 10, and 20 N and sliding speed of 1 and 2 m/s. All fabricated composites show higher resistance in wear than A356 alloy. Wear test results show, by increasing the normal load and sliding velocity, the wear loss weight of all composites increased gradually.

  11. Fabrication and evaluation of low fiber content alumina fiber/aluminum composites

    NASA Technical Reports Server (NTRS)

    Hack, J. E.; Strempek, G. C.

    1980-01-01

    The mechanical fabrication of low volume percent fiber, polycrystalline alumina fiber reinforced aluminum composites was accomplished. Wire preform material was prepared by liquid-metal infiltration of alumina fiber bundles. The wires were subsequently encapsulated with aluminum foil and fabricated into bulk composite material by hot-drawing. Extensive mechanical, thermal and chemical testing was conducted on preform and bulk material to develop a process and material data base. In addition, a preliminary investigation of mechanical forming of bulk alumina fiber reinforced aluminum composite material was conducted.

  12. Trans-laminar-reinforced (TLR) composites

    NASA Astrophysics Data System (ADS)

    Dickinson, Larry Charles

    1997-11-01

    A Trans-Laminar-Reinforced (TLR) composite is defined as composite laminate with up to five percent volume of fibrous reinforcement oriented in a "trans-laminar" fashion in the through-thickness direction. The TLR can be continuous threads as in "stitched laminates", or it can be discontinuous rods or pins as in "Z-FiberspTM" materials. Adding TLR to an otherwise two dimensional laminate results in the following advantages: substantially improved compression-after-impact response; considerably increased fracture toughness in mode I (double cantilever beam) and mode II (end notch flexure); and severely restricted size and growth of impact damage and edge delamination. TLR has also been used to eliminate catastrophic stiffener disbonding in stiffened structures. As little as one percent volume of TLR significantly alters the mechanical response of laminates. The objective of this work was to characterize the effects of TLR on the in-plane and inter-laminar mechanical response of undamaged composite laminates. Detailed finite element models were made of "unit cells," or representative volumes, and an inter-laminar dominated problem of practical interest. The work was limited to the linear response of undamaged material with at least one ply interface. Adding a few percent TLR had a small negative effect on the in-plane extensional and shear moduli, Esbx, Esby and Gsbxy, but had a large positive effect (up to 60 percent) on the thickness direction extensional modulus, Esbz. The out-of-plane shear moduli, Gsbxz and Gsbyz, were significantly affected only with the use of a TLR with a shear modulus an order of magnitude greater than that of the composite lamina. A simple stiffness averaging method for calculating the elastic constants was found to compare closely with the finite element results, with the greatest difference being found in the inter-laminar shear moduli, Gsbxz and Gsbyz. Delamination initiation was studied with a strength of materials approach in the unit

  13. Low Velocity Impact Behavior of Basalt Fiber-Reinforced Polymer Composites

    NASA Astrophysics Data System (ADS)

    Shishevan, Farzin Azimpour; Akbulut, Hamid; Mohtadi-Bonab, M. A.

    2017-06-01

    In this research, we studied low velocity impact response of homogenous basalt fiber-reinforced polymer (BFRP) composites and then compared the impact key parameters with carbon fiber-reinforced polymer (CFRP) homogenous composites. BFRPs and CFRPs were fabricated by vacuum-assisted resin transfer molding (VARTM) method. Fabricated composites included 60% fiber and 40% epoxy matrix. Basalt and carbon fibers used as reinforcement materials were weaved in 2/2 twill textile tip in the structures of BFRP and CFRP composites. We also utilized the energy profile method to determine penetration and perforation threshold energies. The low velocity impact tests were carried out in 30, 60, 80, 100, 120 and 160 J energy magnitudes, and impact response of BFRPs was investigated by related force-deflection, force-time, deflection-time and absorbed energy-time graphics. The related impact key parameters such as maximum contact force, absorbed energy, deflection and duration time were compared with CFRPs for various impact energy levels. As a result, due to the higher toughness of basalt fibers, a better low velocity impact performance of BFRP than that of CFRP was observed. The effects of fabrication parameters, such as curing process, were studied on the low velocity impact behavior of BFRP. The results of tested new fabricated materials show that the change of fabrication process and curing conditions improves the impact behavior of BFRPs up to 13%.

  14. Thermal Analysis of Filler Reinforced Polymeric Composites

    NASA Astrophysics Data System (ADS)

    Ghadge, Mahesh Devidas

    compared with that predicted by mean field theories. At low volume fractions the FEM and mean field theory results are matching. However, at high volume fractions, the results obtained by the two methods are not in agreement. This is due to the fact that mean field theory do not consider the particle interactions happening at higher volume fractions. The present analysis can be used to tailor the thermal properties of ESBR for required thermal conductivity for a wide range of applications such as racing tires, electronic gadgets or aeronautical components. In addition, the proposed FEM models can be used to design and optimize the properties of new composite materials providing more insight into the thermal conductivity of composite polymers and aid in understanding heat transfer mechanism of reinforced polymers.

  15. Method to fabricate layered material compositions

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu

    2004-11-02

    A new class of processes suited to the fabrication of layered material compositions is disclosed. Layered material compositions are typically three-dimensional structures which can be decomposed into a stack of structured layers. The best known examples are the photonic lattices. The present invention combines the characteristic features of photolithography and chemical-mechanical polishing to permit the direct and facile fabrication of, e.g., photonic lattices having photonic bandgaps in the 0.1-20.mu. spectral range.

  16. Method to fabricate layered material compositions

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu

    2002-01-01

    A new class of processes suited to the fabrication of layered material compositions is disclosed. Layered material compositions are typically three-dimensional structures which can be decomposed into a stack of structured layers. The best known examples are the photonic lattices. The present invention combines the characteristic features of photolithography and chemical-mechanical polishing to permit the direct and facile fabrication of, e.g., photonic lattices having photonic bandgaps in the 0.1-20.mu. spectral range.

  17. Hardness and wear resistance of carbon nanotube reinforced aluminum-copper matrix composites.

    PubMed

    Nam, Dong Hoon; Kim, Jae Hwang; Cha, Seung Il; Jung, Seung Il; Lee, Jong Kook; Park, Hoon Mo; Park, Hyun Dal; Hong, Hyung

    2014-12-01

    Recently, carbon nanotubes (CNTs) have been attracted to reinforcement of composite materials due to their extraordinary mechanical, thermal and electrical properties. Many researchers have attempted to develop CNT reinforced metal composites with various fabrication methods and have shown possibilities for structural and functional applications. Among them, CNT reinforced Al matrix composites have become very attractive due to their huge structural application in industry. In this study, CNT reinforced Al-Cu matrix composites with a microstructure of homogeneous dispersion of CNTs in the Al-Cu matrix are investigated. The CNT/Al-Cu composites are fabricated by mixing of CNT/Cu composite powders and Al powders by high energy ball mill process followed by hot extrusion process. The hardness and wear resistance of the CNT/Al-Cu composites are enhanced by 1.4 and 3 times, respectively, compared to those values for the Al-Cu matrix. This remarkable enhancement mainly originates from the homogeneous dispersion of CNTs in Al-Cu matrix and self-lubricant effect of CNTs.

  18. 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.

  19. Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologi

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologies Project - Preliminary Manufacturing Demonstration Articles for Ares V Payload Shroud Barrel Acreage Structure

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  1. Composite fabrication via resin transfer molding technology

    SciTech Connect

    Jamison, G.M.; Domeier, L.A.

    1996-04-01

    The IMPReS (Integrated Modeling and Processing of Resin-based Structures) Program was funded in FY95 to consolidate, evaluate and enhance Sandia`s capabilities in the design and fabrication of composite structures. A key driver of this and related programs was the need for more agile product development processes and for model based design and fabrication tools across all of Sandia`s material technologies. A team of polymer, composite and modeling personnel was assembled to benchmark Sandia`s existing expertise in this area relative to industrial and academic programs and to initiate the tasks required to meet Sandia`s future needs. RTM (Resin Transfer Molding) was selected as the focus composite fabrication technology due to its versatility and growing use in industry. Modeling efforts focused on the prediction of composite mechanical properties and failure/damage mechanisms and also on the uncured resin flow processes typical of RTM. Appropriate molds and test composites were fabricated and model validation studies begun. This report summarizes and archives the modeling and fabrication studies carried out under IMPReS and evaluates the status of composite technology within Sandia. It should provide a complete and convenient baseline for future composite technology efforts within Sandia.

  2. Experimental data on the properties of natural fiber particle reinforced polymer composite material.

    PubMed

    Chandramohan, D; Presin Kumar, A John

    2017-08-01

    This paper presents an experimental study on the development of polymer bio-composites. The powdered coconut shell, walnut shells and Rice husk are used as reinforcements with bio epoxy resin to form hybrid composite specimens. The fiber compositions in each specimen are 1:1 while the resin and hardener composition 10:1 respectively. The fabricated composites were tested as per ASTM standards to evaluate mechanical properties such as tensile strength, flexural strength, shear strength and impact strength are evaluated in both with moisture and without moisture. The result of test shows that hybrid composite has far better properties than single fibre glass reinforced composite under mechanical loads. However it is found that the incorporation of walnut shell and coconut shell fibre can improve the properties.

  3. Processing and characterization of continuous fiber-reinforced glass and glass-ceramic matrix composites

    SciTech Connect

    Wang, Shaio-Wen.

    1990-01-01

    An investigation of the processing and mechanical behavior, particularly damage evolution and failure mechanisms, of continuous fiber reinforced glass and glass-ceramic composites was conducted. The processing effort utilized a slurry infiltration/hot pressing technique to fabricate carbon fiber reinforced borosilicate glass and Nicalon SiC fiber reinforced borosilicate glass composites. A slurry infiltration prepregging setup was designed and successfully operated. Processing parameters including slurry composition, binder burnout cycle and hot pressing schedule were systematically studied and optimized. Mechanical behavior studies were conducted on Nicalon SiC/Calcium Aluminosilicate (CAS) composites. The nature and the strength of the fiber/matrix interface was first characterized using a variety of fiber indentation test methods and transmission electron microscopy.

  4. Reinforcement of flowable dental composites with titanium dioxide nanotubes.

    PubMed

    Dafar, Manal O; Grol, Matthew W; Canham, Peter B; Dixon, S Jeffrey; Rizkalla, Amin S

    2016-06-01

    Flowable dental composites are used as restorative materials due to their excellent esthetics and rheology. However, they suffer from inferior mechanical properties compared to conventional composites. The aim of this study was to reinforce a flowable dental composite with TiO2 nanotubes (n-TiO2) and to assess the effect of n-TiO2 surface modifications on the mechanical properties of the reinforced composite. n-TiO2 were synthesized using an alkaline hydrothermal process and then functionalized with silane or methacrylic acid (MA). Nanotubes were characterized by scanning and transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Commercially available flowable composite (Filtek™ Supreme Ultra Flowable Restorative, 3M ESPE) was reinforced with varying amounts of nanotubes (0-5wt%). Flowability of the resulting composites was evaluated using a Gillmore needle method. Dynamic Young's modulus (E) was measured using an ultrasonic technique. Fracture toughness (KIc) was assessed using a notchless triangular prism and radiopacity was quantified. Viability of NIH/3T3 fibroblasts was evaluated following incubation on composite specimens for 24h. Electron microscopy revealed a tubular morphology of n-TiO2. All reinforced composites exhibited significantly greater values of E than unreinforced composite. Composites reinforced with 3wt% n-TiO2 functionalized with MA exhibited the greatest values of E and KIc. Cytotoxicity assays revealed that reinforced composites were biocompatible. Taken together, flowable composites reinforced with n-TiO2 exhibited mechanical properties superior to those of unreinforced composite, with minimal effects on flowability and radiopacity. n-TiO2-reinforced flowable composites are promising materials for use in dental restorations. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  5. Ballistic Strength of Multi-Layer Fabric System with Through-The-Thickness Reinforcement

    DTIC Science & Technology

    2013-04-12

    impact, multi-layer fabric , through-the-thickness reinforcement, 2-D woven fabric , barbed needle punch process, TexTech core matrix technology, uniform...micro-geometry of fabrics fabricated using TexTech needle - punching technology. A hybrid mesh model has been developed which produces results close to...accomplished, we have established the capacity to (1) simulate the fabrication procedure of needle - punching the through-the-thickness fibers into

  6. Nanographene reinforced carbon/carbon composites

    NASA Astrophysics Data System (ADS)

    Bansal, Dhruv

    Carbon/Carbon Composites (CCC) are made of carbon reinforcement in carbon matrix and have high thermal stability and fatigue resistance. CCC are used in nose cones, heat shields and disc brakes of aircrafts due to their exceptional mechanical properties at high temperature. The manufacturing process of CCC involves a carbonization stage in which unwanted elements, except carbon, are eliminated from the polymer precursor. Carbonization results in the formation of voids and cracks due to the thermal mismatch between the reinforcement and the matrix and expulsion of volatiles from the polymer matrix. Thermal cracks and voids decrease the density and mechanical properties of the manufactured CCC. In this work, Nanographene Platelets (NGP) were explored as nanofillers to fill the voids/cracks and reduce thermal shrinkage in CCC. They were first compared with Vapor Grown Carbon Nanofibers (VGCNF) by dispersion of different concentrations (0.5wt%, 1.5wt%, 3wt%) in resole-type phenolic resin and were characterized to explore their effect on rheology, heat of reaction and wetting behavior. The dispersions were then cured to form nanocomposites and were characterized for morphology, flexure and thermal properties. Finally, NGP were introduced into the carbon/carboncomposites in two stages, first by spraying in different concentrations (0.5wt%, 1.5wt%, 3wt%, 5wt %) during the prepreg formation and later during densification by directly mixing in the corresponding densification mix. The manufactured NGP reinforced CCC were characterized for microstructure, porosity, bulk density and mechanical properties (Flexure and ILSS) which were further cross-checked by non-destructive techniques (vibration and ultrasonic). In this study, it was further found that at low concentration (≤ 1.5 wt%) NGP were more effective in increasing the heat of reaction and in decreasing the viscosity of the phenolic resin. The decrease in viscosity led to better wetting properties of NGP / phenolic

  7. Carbon fiber reinforced thermoplastic composites for future automotive applications

    NASA Astrophysics Data System (ADS)

    Friedrich, K.

    2016-05-01

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

  8. Free form fabrication of thermoplastic composites

    SciTech Connect

    Kaufman, S.G.; Spletzer, B.L.; Guess, T.R.

    1998-02-01

    This report describes the results of composites fabrication research sponsored by the Laboratory Directed Research and Development (LDRD) program at Sandia National Laboratories. They have developed, prototyped, and demonstrated the feasibility of a novel robotic technique for rapid fabrication of composite structures. Its chief innovation is that, unlike all other available fabrication methods, it does not require a mold. Instead, the structure is built patch by patch, using a rapidly reconfigurable forming surface, and a robot to position the evolving part. Both of these components are programmable, so only the control software needs to be changed to produce a new shape. Hence it should be possible to automatically program the system to produce a shape directly from an electronic model of it. It is therefore likely that the method will enable faster and less expensive fabrication of composites.

  9. Nondestructive characterization of woven fabric ceramic composites

    SciTech Connect

    Hsu, D.K.; Saini, V.; Liaw, P.K.; Yu, N.; Miriyala, N.; McHargue, C.J.; Snead, L.L.; Lowden, R.A.

    1995-10-01

    Woven fabric ceramic composites fabricated by the chemical vapor infiltration method are susceptible to high void content and inhomogeneity. The condition of such materials may be characterized nondestructively with ultrasonic methods. In this work, longitudinal and shear waves were used in the quantitative determination of elastic constants of Nicalon{trademark}/SiC composites as a function of volume percent of porosity. Elastic stiffness constants were obtained for both the in-plane and out-of-plane directions with respect to fiber fabric. The effect of porosity on the modulus of woven fabric composites was also modeled and compared to the measured results. Scan images based on the amplitude and time-of-flight of radio frequency (RF) ultrasonic pulses were used for evaluating the material homogeneity for the purpose of optimizing the manufacturing process and for correlation with the mechanical testing results.

  10. A Study of Strength Transfer from tow to Textile Composite Using Different Reinforcement Architectures

    NASA Astrophysics Data System (ADS)

    Cristian, Irina; Nauman, Saad; Boussu, Francois; Koncar, Vladan

    2012-06-01

    The paper proposes an experimental and analytical approach of designing composites with the predetermined ultimate strength, reinforced with warp interlock fabrics. In order to better understand the phenomena of transfer of tensile properties from a tow to the composite, intermediate phases of composite manufacturing have also been taken into account and tensile properties of tows taken from the loom and the woven reinforcements have also been tested. Process of transfer of mechanical properties of raw materials to the final product (composite) depends on various structural factors. Here the influence of weave structure, which ultimately influences crimp has been studied. A strength transfer coefficient has been proposed which helps in estimating the influence of architectural parameters on 3D woven composites. 3 woven interlock reinforcements were woven to form composites. The coefficients of strength transfer were calculated for these three variants. The structural parameters were kept the same for these three reinforcements except for the weave structure. In was found that the phenomenon of strength transfer from tow to composite is negatively influenced by the crimp. In general the strength transfer coefficients have higher values for dry reinforcements and afterwards due to resin impregnation the values drop.

  11. Styrene-terminated polysulfone oligomers as matrix material for graphite reinforced composites: An initial study

    NASA Technical Reports Server (NTRS)

    Garcia, Dana; Bowles, Kenneth J.; Vannucci, Raymond D.

    1987-01-01

    Styrene terminated polysulfone oligomers are part of an oligomeric class of compounds with end groups capable of thermal polymerization. These materials can be used as matrices for graphite reinforced composites. The initial evaluation of styrene terminated polysulfone oligomer based composites are summarized in terms of fabrication methods, and mechanical and environmental properties. In addition, a description and evaluation is provided of the NASA/Industry Fellowship Program for Technology Transfer.

  12. Processing and Evaluation of 3D-Reinforced Needled Composite Laminate

    DTIC Science & Technology

    2012-09-01

    This report documents the fabrication and test of a woven glass /epoxy composite laminate that was reinforced in the through- thickness direction with...the in-plane strength of woven glass materials. Because the processing parameters were arbitrarily chosen, these experiments should be considered as...delamination resistance of composite laminates. The tufting process uses a hollow needle to insert glass or carbon threads comprised of typically

  13. Composites Reinforced in Three Dimensions by Using Low Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Erb, Randall M.; Libanori, Rafael; Rothfuchs, Nuria; Studart, André R.

    2012-01-01

    The orientation and distribution of reinforcing particles in artificial composites are key to enable effective reinforcement of the material in mechanically loaded directions, but remain poor if compared to the distinctive architectures present in natural structural composites such as teeth, bone, and seashells. We show that micrometer-sized reinforcing particles coated with minimal concentrations of superparamagnetic nanoparticles (0.01 to 1 volume percent) can be controlled by using ultralow magnetic fields (1 to 10 milliteslas) to produce synthetic composites with tuned three-dimensional orientation and distribution of reinforcements. A variety of structures can be achieved with this simple method, leading to composites with tailored local reinforcement, wear resistance, and shape memory effects.

  14. Development and fabrication of bismaleimide-graphite composites

    NASA Technical Reports Server (NTRS)

    Stenzenberger, H.; Herzog, M.; Roemer, W.; Scheiblich, R.

    1979-01-01

    The successful fabrication of high temperature resistant composites depends mainly on the processability of the resin binder matrix. For two new bismaleimide type resins the processing of graphite fabric prepregs to composites is described. One resin coded M 751 has to be processed from N-Methylpyrrolidone, the other resin evaluated is a so-called hot melt solvent-less system. Commercial T300/3000 Graphite fabrics were used as reinforcement. The M 751 - Resin is a press grade material and laminates are therefore moulded in high pressure conditions (400 N/sq cm). The solvent-less resin system H 795 is an autoclave grade material and can be cured at 40 N/sq cm. The cure cycles for both the press grade and the autoclave grade material (Fiberite W 143 fabric prepregs) are provided and the mechanical properties of laminates at low (23 C) and high (232 C) temperatures were measured. For comparison, the neat resin flexural properties are also presented. The water absorption for the neat resins and the graphite fabric laminates after a 1000 hour period was evaluated.

  15. Mechanical characterization of glass fiber (woven roving/chopped strand mat E-glass fiber) reinforced polyester composites

    NASA Astrophysics Data System (ADS)

    Bhaskar, V. Vijaya; Srinivas, Kolla

    2017-07-01

    Polymer reinforced composites have been replacing most of the engineering material and their applications become more and more day by day. Polymer composites have been analyzing from past thirty five years for their betterment for adapting more applications. This paper aims at the mechanical properties of polyester reinforced with glass fiber composites. The glass fiber is reinforced with polyester in two forms viz Woven Rovings (WRG) and Chopped Strand Mat (CSMG) E-glass fibers. The composites are fabricated by hand lay-up technique and the composites are cut as per ASTM Standard sizes for corresponding tests like flexural, compression and impact tests, so that flexural strength, compression strength, impact strength and inter laminar shear stress(ILSS) of polymer matrix composites are analyzed. From the tests and further calculations, the polyester composites reinforced with Chopped Strand Mat glass fiber have shown better performance against flexural load, compression load and impact load than that of Woven Roving glass fiber.

  16. Analysis of stress-strain, fracture and ductility behavior of aluminum matrix composites containing discontinuous silicon carbide reinforcement

    NASA Technical Reports Server (NTRS)

    Mcdanels, D. L.

    1984-01-01

    Mechanical properties and stress-strain behavior for several types of commercially fabricated aluminum matrix composites, containing up to 40 vol % discontinuous SiC whisker, nodule, or particulate reinforcement were evaluated. It was found that the elastic modulus of the composites was isotropic, to be independent of type of reinforcement, and to be controlled solely by the volume percentage of SiC reinforcement present. The yield/tensile strengths and ductility were controlled primarily by the matrix alloy and temper condition. Ductility decreased with increasing reinforcement content, however, the fracture strains observed were higher than those reported in the literature for this type of composite. This increase in fracture strain is attributed to cleaner matrix powder and increased mechanical working during fabrication. Conventional aluminum and titanium structural alloys were compared and have shown that the properties of these low cost, lightweight composites have good potential for application to aerospace structures.

  17. Toughening reinforced epoxy composites with brominated polymeric additives

    NASA Technical Reports Server (NTRS)

    Nir, Z.; Gilwee, W. J., Jr. (Inventor)

    1985-01-01

    Cured polyfunctional epoxy resins including tris (hydroxyphenyl) methane triglycidyl ether are toughened by addition of polybrominated polymeric additives having an EE below 1500 to the pre-cure composition. Carboxy terminated butadiene acrylonitrile rubber is optionally present in the precure mixture as such or as a pre-formed copolymer with other reactants. Reinforced composites, particularly carbon reinforced composites, of these resins are disclosed and shown to have improved toughness.

  18. Toughening reinforced epoxy composites with brominated polymeric additives

    NASA Technical Reports Server (NTRS)

    Nir, Z. (Inventor); Gilwee, W. J., Jr. (Inventor)

    1985-01-01

    Cured polyfunctional epoxy resins including tris(hydroxyphenyl)methane triglycidyl ether are toughened by addition of polybrominated polymeric additives having an EE below 1500 to the pre-cure composition. Carboxy-terminated butadiene-acrylonitrile rubber is optionally present in the pre-cure mixture as such or as a pre-formed copolymer with other reactants. Reinforced composites, particularly carbon-reinforced composites, of these resins are disclosed and shown to have improved toughness.

  19. Nondestructive Evaluation of Fiber Reinforced Composites. A State-of-the-Art Survey. Volume 1. NDE of Graphite Fiber-Reinforced Plastic Composites. Part 1. Radiography and Ultrasonics

    DTIC Science & Technology

    1982-03-01

    composites (Ref. 1) and by the can be large, and secondary operations can be mini- Army on glass fiber reinforced composites (Ref. 2). This mized. Composites...structural characteristics of ceramic materials, and updates of carbon/carbon com- composites. posites and glass fiber reinforced composites. Because of...the large amount of literature available on graphite While glass fiber reinforced plastic composites fiber reinforced composites, this particular volume

  20. Reinforcement stresses during deformation of sphere- and particulate-reinforced Al-matrix composites

    SciTech Connect

    Justice, I.; Poza, P.; Martinez, J.L.; Llorca, J.

    1996-02-01

    Recent experimental results showed that reinforcement fracture is very often the dominant damage mechanism during ambient temperature deformation of discontinuously reinforced Al-matrix composites (DRAC). The reinforcements are broken by cracks perpendicular to the loading axis, and the fraction of broken reinforcements increases during plastic deformation as the load transferred from the matrix to the ceramic particulates increases. This process continues until a criteria fraction of broken reinforcements is reached, and then fracture takes place suddenly by a ductile mechanism involving localized necking of the intervoid matrix. The rate of reinforcement fracture depends on the strength of the ceramic reinforcements and on the stresses acting on them, and the modeling of the processes of damage accumulation in DRAC requires the knowledge of both. In particular, the stresses acting on the reinforcements during monotonic tensile deformation are a function of the applied strain, of the matrix and reinforcement properties, and of the volume fraction and shape of the ceramic reinforcements. A parametrical study is presented in this article of the influence of these factors on the stress acting on the reinforcements. The numerical results covered the whole range of matrix strengths which are typical in DRAC and were fitted to simple analytical expressions to facilitate their use by other researchers.

  1. Lightweight optical telescope structures fabricated from CFRP composites

    NASA Astrophysics Data System (ADS)

    Martin, Robert N.; Romeo, Robert C.

    2007-09-01

    CFRP (carbon fiber reinforced plastic) is an attractive material for fabrication of optical systems. The stiffness-to-weight ratio of CFRP is high, the coefficient of thermal expansion is low, the structure thermalizes rapidly, and many of the structural properties can be tailored to the application. We have used CFRP and CFRP-aluminum sandwich panels extensively in the structures of astronomical, optical telescopes up to 1.5m diameter aperture. In designing the optical structures, we have chosen some key fabrication techniques with CFRP that take advantage of the mechanical properties. This paper discusses the design and fabrication of 2 major telescope projects. The 1m ULTRA telescope has both the optics and the OTA fabricated from CFRP. This telescope has been recently installed at the SDSU Mt. Laguna Observatory near San Diego. A 1.4m telescope for the Naval Research Lab is being designed and fabricated at CMA. The optics, OTA, and the mount are all being fabricated using CFRP composites. The result is a lightweight structure which can be moved or deployed as necessary.

  2. Reinforced polypropylene composites: effects of chemical compositions and particle size.

    PubMed

    Ashori, Alireza; Nourbakhsh, Amir

    2010-04-01

    In this work, the effects of wood species, particle sizes and hot-water treatment on some physical and mechanical properties of wood-plastic composites were studied. Composites of thermoplastic reinforced with oak (Quercus castaneifolia) and pine (Pinus eldarica) wood were prepared. Polypropylene (PP) and maleic anhydride grafted polypropylene (MAPP) were used as the polymer matrix and coupling agent, respectively. The results showed that pine fiber had significant effect on the mechanical properties considered in this study. This effect is explained by the higher fiber length and aspect ratio of pine compared to the oak fiber. The hot-water treated (extractive-free) samples, in both wood species, improved the tensile, flexural and impact properties, but increased the water absorption for 24h. This work clearly showed that lignocellulosic materials in both forms of fiber and flour could be effectively used as reinforcing elements in PP matrix. Furthermore, extractives have marked effects on the mechanical and physical properties. Copyright 2009 Elsevier Ltd. All rights reserved.

  3. Hybrid Composites Based on Carbon Fiber/Carbon Nanofilament Reinforcement

    PubMed Central

    Tehrani, Mehran; Yari Boroujeni, Ayoub; Luhrs, Claudia; Phillips, Jonathan; Al-Haik, Marwan S.

    2014-01-01

    Carbon nanofilament and nanotubes (CNTs) have shown promise for enhancing the mechanical properties of fiber-reinforced composites (FRPs) and imparting multi-functionalities to them. While direct mixing of carbon nanofilaments with the polymer matrix in FRPs has several drawbacks, a high volume of uniform nanofilaments can be directly grown on fiber surfaces prior to composite fabrication. This study demonstrates the ability to create carbon nanofilaments on the surface of carbon fibers employing a synthesis method, graphitic structures by design (GSD), in which carbon structures are grown from fuel mixtures using nickel particles as the catalyst. The synthesis technique is proven feasible to grow nanofilament structures—from ethylene mixtures at 550 °C—on commercial polyacrylonitrile (PAN)-based carbon fibers. Raman spectroscopy and electron microscopy were employed to characterize the surface-grown carbon species. For comparison purposes, a catalytic chemical vapor deposition (CCVD) technique was also utilized to grow multiwall CNTs (MWCNTs) on carbon fiber yarns. The mechanical characterization showed that composites using the GSD-grown carbon nanofilaments outperform those using the CCVD-grown CNTs in terms of stiffness and tensile strength. The results suggest that further optimization of the GSD growth time, patterning and thermal shield coating of the carbon fibers is required to fully materialize the potential benefits of the GSD technique. PMID:28788671

  4. Hybrid Composites Based on Carbon Fiber/Carbon Nanofilament Reinforcement.

    PubMed

    Tehrani, Mehran; Yari Boroujeni, Ayoub; Luhrs, Claudia; Phillips, Jonathan; Al-Haik, Marwan S

    2014-05-28

    Carbon nanofilament and nanotubes (CNTs) have shown promise for enhancing the mechanical properties of fiber-reinforced composites (FRPs) and imparting multi-functionalities to them. While direct mixing of carbon nanofilaments with the polymer matrix in FRPs has several drawbacks, a high volume of uniform nanofilaments can be directly grown on fiber surfaces prior to composite fabrication. This study demonstrates the ability to create carbon nanofilaments on the surface of carbon fibers employing a synthesis method, graphitic structures by design (GSD), in which carbon structures are grown from fuel mixtures using nickel particles as the catalyst. The synthesis technique is proven feasible to grow nanofilament structures-from ethylene mixtures at 550 °C-on commercial polyacrylonitrile (PAN)-based carbon fibers. Raman spectroscopy and electron microscopy were employed to characterize the surface-grown carbon species. For comparison purposes, a catalytic chemical vapor deposition (CCVD) technique was also utilized to grow multiwall CNTs (MWCNTs) on carbon fiber yarns. The mechanical characterization showed that composites using the GSD-grown carbon nanofilaments outperform those using the CCVD-grown CNTs in terms of stiffness and tensile strength. The results suggest that further optimization of the GSD growth time, patterning and thermal shield coating of the carbon fibers is required to fully materialize the potential benefits of the GSD technique.

  5. Controle de la fabrication des composites par injection sur renforts

    NASA Astrophysics Data System (ADS)

    Lebel, Francois

    Liquid Composite Molding (LCM) is an increasingly used class of processes to manufacture high performance composites. A multiscale study is presented in this thesis in order to better understand the fundamental physics of impregnation and air entrapment phenomena in dual scale fibrous reinforcements and thus propose practical solutions for process control engineers. First of all, an experimental setup is developed to study the saturation of fibrous reinforcements, at the macroscopic scale, during the Resin Transfer Molding (RTM). This setup is used to determine some key parameters of the part filling step and industrial post-filling strategies (mold bleeding and consolidation) that control the impregnation quality of fibrous reinforcements. These key parameters are identified using three series of experiments. These parameters are the flow front velocity, the inlet mold pressure and the bleeding flow rate. The analyses in these three series of experiments are based on an ASTM standard procedure for void content determination in the composite parts by carbonization (also called loss on ignition (LOI)). These three series of experiments have related a posteriori the key parameters of LCM processes to phenomena of void formation, migration and dissolution in composite parts made of E-glass non crimp fabric (NCF) and vinyl ester resin. The second part of this thesis aims to investigate, at the mesoscopic and microscopic scale, the impregnation mechanisms of fibrous reinforcements during LCM processes. This analysis focuses more specifically on wicking phenomenon in fiber tows and in fibrous laminates, namely here stacks of non crimp fabric plies. This experimental study is carried out to better understand the physics which explain that the impregnation velocity is one of the key parameters that control the quality of composite parts manufactured by LCM processes. This analysis also aims to identify the structural features of fiber tows and fibrous reinforcements that

  6. Liquid composite molding-processing and characterization of fiber-reinforced composites modified with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Zeiler, R.; Khalid, U.; Kuttner, C.; Kothmann, M.; Dijkstra, D. J.; Fery, A.; Altstädt, V.

    2014-05-01

    The increasing demand in fiber-reinforced plastics (FRPs) necessitates economic processing of high quality, like the vacuum-assisted resin transfer molding (VARTM) process. FRPs exhibit excellent in-plane properties but weaknesses in off-plane direction. The addition of nanofillers into the resinous matrix phase embodies a promising approach due to benefits of the nano-scaled size of the filler, especially its high surface and interface areas. Carbon nanotubes (CNTs) are preferable candidates for resin modification in regard of their excellent mechanical properties and high aspect ratios. However, especially the high aspect ratios give rise to withholding or filtering by fibrous fabrics during the impregnation process, i.e. length dependent withholding of tubes (short tubes pass through the fabric, while long tubes are restrained) and a decrease in the local CNT content in the laminate along the flow path can occur. In this study, hybrid composites containing endless glass fiber reinforcement and surface functionalized CNTs dispersed in the matrix phase were produced by VARTM. New methodologies for the quantification of the filtering of CNTs were developed and applied to test laminates. As a first step, a method to analyze the CNT length distribution before and after injection was established for thermosetting composites to characterize length dependent withholding of nanotubes. The used glass fiber fabric showed no perceptible length dependent retaining of CNTs. Afterward, the resulting test laminates were examined by Raman spectroscopy and compared to reference samples of known CNT content. This Raman based technique was developed further to assess the quality of the impregnation process and to quantitatively follow the local CNT content along the injection flow in cured composites. A local decline in CNT content of approx. 20% was observed. These methodologies allow for the quality control of the filler content and size-distribution in CNT based hybrid

  7. Silicon carbide reinforced silicon carbide composite

    NASA Technical Reports Server (NTRS)

    Lau, Sai-Kwing (Inventor); Calandra, Salvatore J. (Inventor); Ohnsorg, Roger W. (Inventor)

    2001-01-01

    This invention relates to a process comprising the steps of: a) providing a fiber preform comprising a non-oxide ceramic fiber with at least one coating, the coating comprising a coating element selected from the group consisting of carbon, nitrogen, aluminum and titanium, and the fiber having a degradation temperature of between 1400.degree. C. and 1450.degree. C., b) impregnating the preform with a slurry comprising silicon carbide particles and between 0.1 wt % and 3 wt % added carbon c) providing a cover mix comprising: i) an alloy comprising a metallic infiltrant and the coating element, and ii) a resin, d) placing the cover mix on at least a portion of the surface of the porous silicon carbide body, e) heating the cover mix to a temperature between 1410.degree. C. and 1450.degree. C. to melt the alloy, and f) infiltrating the fiber preform with the melted alloy for a time period of between 15 minutes and 240 minutes, to produce a ceramic fiber reinforced ceramic composite.

  8. An ideal reinforcement for structural composites

    SciTech Connect

    Kevorkijan, V.M.

    1997-12-01

    Different criteria and accumulated data lead to the conclusion that discontinuously reinforced metal-matrix composites (DR MMCs) will become an engineering material of general use. At the end of 1970s, the automobile and transport industries had a strong interest in and high expectations for DR-MMCs because of their superior specific strength and rigidity when compared with conventional aluminum alloys. After two decades of development, the first DR-MMC application, an engine connecting-rod, is ready to market. Major applications in the automobile industry, such as brake rotors and drive shafts, are now in the later stages of development, and other engineering applications are well advanced. DR-MMC technology is now recognized worldwide, and research groups are able to introduce remarkable applications of these materials to the market. Three main problems must be solved to facilitate the expanding application of DR-MMCs with light-metal-alloy matrices. They are: (1) superior cost performances; (2) active implementation of environmental concerns; (3) improved ductility. The immediate solution of these problems is impossible. However, many researchers and managers firmly believe that solutions will be found if the same amount of energy is devoted to solving these problems as has been expended during the past two decades of DR-MMCs R and D.

  9. Effective reinforcement in carbon nanotube-polymer composites.

    PubMed

    Wang, W; Ciselli, P; Kuznetsov, E; Peijs, T; Barber, A H

    2008-05-13

    Carbon nanotubes have mechanical properties that are far in excess of conventional fibrous materials used in engineering polymer composites. Effective reinforcement of polymers using carbon nanotubes is difficult due to poor dispersion and alignment of the nanotubes along the same axis as the applied force during composite loading. This paper reviews the mechanical properties of carbon nanotubes and their polymer composites to highlight how many previously prepared composites do not effectively use the excellent mechanical behaviour of the reinforcement. Nanomechanical tests using atomic force microscopy are carried out on simple uniaxially aligned carbon nanotube-reinforced polyvinyl alcohol (PVA) fibres prepared using electrospinning processes. Dispersion of the carbon nanotubes within the polymer is achieved using a surfactant. Young's modulus of these simple composites is shown to approach theoretically predicted values, indicating that the carbon nanotubes are effective reinforcements. However, the use of dispersant is also shown to lower Young's modulus of the electrospun PVA fibres.

  10. Precipitation Sequence of a SiC Particle Reinforced Al-Mg-Si Alloy Composite

    NASA Astrophysics Data System (ADS)

    Shen, Rujuan; Wang, Yihan; Guo, Baisong; Song, Min

    2016-11-01

    In this study, the precipitation sequence of a 5 vol.% SiC particles reinforced Al-1.12 wt.%Mg-0.77 wt.%Si alloy composite fabricated by traditional powder metallurgy method was investigated by transmission electron microscopy and hardness measurements. The results indicated that the addition of SiC reinforcements not only suppresses the initial aging stage but also influences the subsequent precipitates. The precipitation sequence of the composite aged at 175 °C can be described as: Guinier-Preston (G.P.) zone → β″ → β' → B', which was confirmed by high-resolution transmission electron microscopy. This work might provide the guidance for the design and fabrication of hardenable automobile body sheet by Al-based composites with enhanced mechanical properties.

  11. [Fiber reinforced composite posts: literature review].

    PubMed

    Frydman, G; Levatovsky, S; Pilo, R

    2013-07-01

    FRC (Fiber-reinforced composite) posts have been used since the beginning of the 90s with the introduction of carbon fiber posts. Fiber posts are widely used to restore endodontically treated teeth that have insufficient coronal tooth structure. Many in vitro and in vivo studies have shown the advantage of using FRC over prefabricated and cast metal post especially indicated in narrow root canals which are prone to vertically root fracture. The most frequent failure of FRC is debonding of a post at the resin cement/dentin interface. Bonding to dentin may be achieved by using etch-and-rinse and self-etch adhesives. The bond strength formed by self-adhesive cements is noticeably lower in comparison to the bond strength formed with resin cements applied in combination with etch-and-rinse adhesives. In an attempt to maximize resin bonding to fiber posts, several surface treatments have been suggested. Sandblasting with alumina particles results in an increased surface roughness and surface area without affecting the integrity of the post as long as it is applied by 50 microm alumina particles at 2.5 bars for maximally 5 seconds at a distance of 30 mm. The efficiency of post salinization is controversial and its contribution to the retention is of minor importance. Hydrofluoric acid has recently been proposed for etching glass fiber posts but this technique produced substantial damage to the glass fibers and affected the integrity of the post. Delayed cementation of fiber post (at least 24h post endodontic treatment) resulted in higher retentive strengths in comparison to immediate cementation and the best results were obtained when the luting agent was brought into the post space with lentulo spirals or specific syringes. The resin cement film thickness also influences the pullout strengths of fiber-reinforced posts .The highest bond strength values were obtained when the cement layer oversized the post spaces but not larger than 0.3 mm. The use of core build

  12. Strengthening behavior of chopped multi-walled carbon nanotube reinforced aluminum matrix composites

    SciTech Connect

    Shin, S.E.; Bae, D.H.

    2013-09-15

    Strengthening behavior of the aluminum composites reinforced with chopped multi-walled carbon nanotubes (MWCNTs) or aluminum carbide formed during annealing at 500 °C has been investigated. The composites were fabricated by hot-rolling the powders which were ball-milled under various conditions. During the early annealing process, aluminum atoms can cluster inside the tube due to the diffusional flow of aluminum atoms into the tube, providing an increase of the strength of the composite. Further annealing induces the formation of the aluminum carbide phase, leading to an overall drop in the strength of the composites. While the strength of the composites can be evaluated according to the rule of mixture, a particle spacing effect can be additionally imparted on the strength of the composites reinforced with the chopped MWCNTs or the corresponding carbides since the reinforcing agents are smaller than the submicron matrix grains. - Highlights: • Strengthening behavior of chopped CNT reinforced Al-based composites is investigated. • Chopped CNTs have influenced the strength and microstructures of the composites. • Chopped CNTs are created under Ar- 3% H2 atmosphere during mechanical milling. • Strength can be evaluated by the rule of the mixture and a particle spacing effect.

  13. 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

  14. Mirrors fabricated with slightly oxidized C/C composites

    NASA Astrophysics Data System (ADS)

    Wang, Yongjie; Xu, Liang; Ding, Jiaoteng; Xie, Yongjie; Ma, Zhen

    2016-10-01

    Up to now, traditional materials, such as glass, metal and SiC ceramic, gradually begin to be unsatisfied development of the future mirrors. Designable carbon fiber reinforced composites became optimized material for large aperture lightweight mirrors. Carbon/carbon composites exhibit low thermal expansion and no moisture-absorption expansion problem, therefore, they get particular attention in the space reflector field. Ni was always employed as optical layer in the mirror, however, the coating behaved poor bond with substrate and often peeled off during optical processing. In order to solve this problem, slight oxidation was carried on the C/C composites before Ni plated. The Ni coating exhibited stronger coherence and better finish performance. Finally, a 100mm diameter plane mirror was successful fabricated.

  15. Fabrication and Characterization of SMA Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.; Lach, Cynthia L.; Cano, Robert J.

    2001-01-01

    Results from an effort to fabrication shape memory alloy hybrid composite (SMAHC) test specimens and characterize the material system are presented in this study. The SMAHC specimens are conventional composite structures with an embedded SMA constituent. The fabrication and characterization work was undertaken to better understand the mechanics of the material system, address fabrication issues cited in the literature, and provide specimens for experimental validation of a recently developed thermomechanical model for SMAHC structures. Processes and hardware developed for fabrication of the SMAHC specimens are described. Fabrication of a SMA14C laminate with quasi-isotropic lamination and ribbon-type Nitinol actuators embedded in the 0' layers is presented. Beam specimens are machined from the laminate and are the focus of recent work, but the processes and hardware are readily extensible to more practical structures. Results of thermomechanical property testing on the composite matrix and Nitinol ribbon are presented. Test results from the Nitinol include stress-strain behavior, modulus versus temperature. and constrained recovery stress versus temperature and thermal cycle. Complex thermomechanical behaviors of the Nitinol and composite matrix are demonstrated, which have significant implications for modeling of SMAHC structures.

  16. Experimental Comparison of Different Carbon Fiber Composites in Reinforcement Layouts for Wooden Beams of Historical Buildings.

    PubMed

    Rescalvo, Francisco J; Valverde-Palacios, Ignacio; Suarez, Elisabet; Gallego, Antolino

    2017-09-21

    This paper offers a detailed, quantitative and exhaustive experimental comparison in terms of mechanical properties of three different layouts of carbon composite materials (CFRP) used to strengthen existing old timber beams highly affected by diverse natural defects and biological attacks, testing the use of pultruded laminate attached on the tension side of the element (LR), CFRP fabrics totally U-shape wrapping the timber element (UR), and the combined use of both reinforcement solutions (UR-P). Moreover, unidirectional and bidirectional fabrics were considered and compared. Timber elements used for the experimental program were extracted from a recent rehabilitation of the roof of the current Faculty of Law building, University of Granada (Spain), catalogued as a historical edifice. Experimental results from bending tests show that in all cases reinforcement provides a clear improvement in terms of bending capacity and stiffness as compared with the control specimens (without reinforcement). However, improvements in terms of ductility differ considerably depending on the kind of layout.

  17. Fabrication of Composite Material Using Gettou Fiber by Injection Molding

    NASA Astrophysics Data System (ADS)

    Setsuda, Roy; Fukumoto, Isao; Kanda, Yasuyuki

    This study investigated the mechanical properties of composite using gettou (shell ginger) fiber as reinforcement fabricated from injection molding. Gettou fiber is a natural fiber made from gettou, a subtropical plant that is largely abundant in Okinawa, Japan. We used the stem part of gettou plant and made the gettou fiber by crushing the stem. The composite using gettou fiber contributed to low shrinkage ratio, high bending strength and high flexural modulus. The mechanical strength of composite using long gettou fiber showed higher value than composite using short gettou fiber. Next, because gettou is particularly known for its anti-mold characteristic, we investigated the characteristic in gettou plastic composite. The composite was tested against two molds: aspergillius niger and penicillium funiculosum. The 60% gettou fiber plastic composite was found to satisfy the JISZ2801 criterion. Finally, in order to predict the flexural modulus of composite using gettou fiber by Halpin-Tsai equation, the tensile elastic modulus of single gettou fiber was measured. The tendency of the experimental results of composite using gettou fiber was in good agreement with Halpin-Tsai equation.

  18. Fabrication of angleply carbon-aluminum composites

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1974-01-01

    A study was conducted to fabricate and test angleply composite consisting of NASA-Hough carbon base monofilament in a matrix of 2024 aluminum. The effect of fabrication variables on the tensile properties was determined, and an optimum set of conditions was established. The size of the composite panels was successfully scaled up, and the material was tested to measure tensile behavior as a function of temperature, stress-rupture and creep characteristics at two elevated temperatures, bending fatigue behavior, resistance to thermal cycling, and Izod impact response.

  19. Combustion Joining for Composite Fabrication

    DTIC Science & Technology

    2009-10-25

    oxidation with every landing A380 -rejected take off test C-C brakes UNCLASSIFIED Joining C-Based Materials • Difficult task – Carbon cannot be welded ...Limiting case: reactive sintering • Materials to be joined also heated to Tig (not just the reactive media) • For most systems, Tig ~ Tmp of least...thin layer of desired reaction composition between two disks of the material to be welded Preheat to the ignition temperature. After initiation, a

  20. Development of Ceramic Fibers for Reinforcement in Composite Materials

    NASA Technical Reports Server (NTRS)

    Gates, L. E.; Lent, W. E.; Teague, W. T.

    1961-01-01

    the. testing apparatus for single fiber tensile strength increased the precision. of tests conducted on nine fibers. The highest mean tensile strength, a value of 295,000 pounds per square inch, was obtained with R-141 fibers. Treatment of R-74 fibers with anhydrous Linde A-1100 silane finish improved its mean fiber tensile strength by 25 percent. The lapse of time after fiber formation had no measurable effect on tensile strength. A static heating test conducted with various high melting fibers indicated that Fiberfrax and R-108 underwent no significant changes in bulk volume or resiliency on exposure to 2750 degrees Fahrenheit (1510 degrees Centigrade) in an oxidizing atmosphere. For fiber-resin composition fabrication, ten fiber materials were selected on the bases of high fiber yield, fusion temperature, and type of composition. Fiberfrax, a commercial ceramic fiber, was included for comparison. A new, more effective method of removing pellets from blown fibers was developed. The de-pelletized fibers were treated with a silane finish and felted into ten-inch diameter felts prior to resin impregnation. Composites containing 30 percent by weight of CTL 91-LD phenolic resin were molded under high pressure from the impregnated felts and post-cured to achieve optimum properties. Flexural strength, flexural modules of elasticity, and punch shear strength tests were conducted on the composite specimens. The highest average flexural strength obtained was 19,958 pounds per square inch with the R-74-fiber-resin composite. This compares very favorably with the military specification of 13,000 pounds per square inch flexural strength for randomly oriented fiber reinforced composites. The highest punch shear strength (11,509 pounds per square inch) was obtained with the R-89 fiber-resin composite. The effects of anhydrous fiber finishes on composite strength were not clearly indicated. Plasma arc tests at a heat flux of 550 British Thermal Units per square foot per second on

  1. Multi-Scale CNT-Based Reinforcing Polymer Matrix Composites for Lightweight Structures

    NASA Technical Reports Server (NTRS)

    Eberly, Daniel; Ou, Runqing; Karcz, Adam; Skandan, Ganesh; Mather, Patrick; Rodriguez, Erika

    2013-01-01

    Reinforcing critical areas in carbon polymer matrix composites (PMCs), also known as fiber reinforced composites (FRCs), is advantageous for structural durability. Since carbon nanotubes (CNTs) have extremely high tensile strength, they can be used as a functional additive to enhance the mechanical properties of FRCs. However, CNTs are not readily dispersible in the polymer matrix, which leads to lower than theoretically predicted improvement in mechanical, thermal, and electrical properties of CNT composites. The inability to align CNTs in a polymer matrix is also a known issue. The feasibility of incorporating aligned CNTs into an FRC was demonstrated using a novel, yet commercially viable nanofiber approach, termed NRMs (nanofiber-reinforcing mats). The NRM concept of reinforcement allows for a convenient and safe means of incorporating CNTs into FRC structural components specifically where they are needed during the fabrication process. NRMs, fabricated through a novel and scalable process, were incorporated into FRC test panels using layup and vacuum bagging techniques, where alternating layers of the NRM and carbon prepreg were used to form the reinforced FRC structure. Control FRC test panel coupons were also fabricated in the same manner, but comprised of only carbon prepreg. The FRC coupons were machined to size and tested for flexural, tensile, and compression properties. This effort demonstrated that FRC structures can be fabricated using the NRM concept, with an increased average load at break during flexural testing versus that of the control. The NASA applications for the developed technologies are for lightweight structures for in-space and launch vehicles. In addition, the developed technologies would find use in NASA aerospace applications such as rockets, aircraft, aircraft/spacecraft propulsion systems, and supporting facilities. The reinforcing aspect of the technology will allow for more efficient joining of fiber composite parts, thus offering

  2. NDE Elastic Properties of Fiber-Reinforced Composite Materials

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.

    1995-01-01

    Fiber-reinforced composites are increasingly replacing metallic alloys as structural materials for primary components of fracture-critical structures. This trend is a result of the growing understanding of material behavior and recognition of the desirable properties of composites. A research program was conducted on NDE methods for determining the elastic properties of composites.

  3. Tensile Properties of Epoxy Composites Reinforced with Continuous PALF Fibers

    NASA Astrophysics Data System (ADS)

    Glória, Gabriel O.; Altoé, Giulio R.; Moraes, Ygor M.; Loyola, Rômulo L.; Margem, Frederico M.; Monteiro, Sergio N.

    The tensile properties of DGEBA/TETA epoxy matrix composites reinforced with different amounts of PALF fibers were evaluated. Composites reinforced with up to 30% in volume of long, continuous and aligned PALF fibers were tested in an Instron machine at room temperature. The fracture was analyzed by SEM. This one revealed a weak fiber/matrix interface, which could be responsible for the performance of some properties. The results showed significant changes in the mechanical properties with the amount of PALF fibers.

  4. A mechanism responsible for reducing compression strength of through-the-thickness reinforced composite material

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.

    1992-01-01

    A study was conducted to identify one of the mechanisms that contributes to the reduced compression strength of composite materials with through-the-thickness (TTT) reinforcements. In this study a series of thick (0/90) laminates with stitched and integrally woven TTT reinforcements were fabricated and statically tested. In both the stitching and weaving process a surface loop of TTT reinforcement yarn is created between successive TTT penetrations. It was shown that the surface loop of the TTT reinforcement 'kinked' the in-plane fibers in such a manner that they were made ineffective in carrying compressive load. The improvement in strength by removal of the surface loop and 'kinked' in-plane fibers was between 7 and 35 percent.

  5. Simulation of a Novel Joining Process for Fiber-Reinforced Thermoplastic Composites and Metallic Components

    NASA Astrophysics Data System (ADS)

    Gude, M.; Freund, A.; Vogel, C.; Kupfer, R.

    2017-01-01

    In this study, a new joining technology to produce hybrid structures with continuous-fiber-reinforced thermoplastics and metallic components is presented adapting the concept of classical clinching for thermoplastic composites. To demonstrate the capability of the thermoclinching process, prototypic joints were manufactured using an experimental joining installation developed. Nondestructive and destructive analyses of the thermoclinched joints showed that a relocation of the reinforcement into the neck and head area of the joining zone could be achieved. For a first estimation of the maximum load-carrying capacity of the joints, single-lap specimens with both reinforced and nonreinforced thermoplastics were manufactured and tested, revealing up to 50% higher failure loads of the reinforced joints. To understand the local material configuration and to achieve a defined and adjustable fabric structure in the head area of the joint, further analyses with regard to material- and tool-side conditions of the joining zone are necessary.

  6. Production of Banana Fiber Yarns for Technical Textile Reinforced Composites

    PubMed Central

    Ortega, Zaida; Morón, Moisés; Monzón, Mario D.; Badalló, Pere; Paz, Rubén

    2016-01-01

    Natural fibers have been used as an alternative to synthetic ones for their greener character; banana fibers have the advantage of coming from an agricultural residue. Fibers have been extracted by mechanical means from banana tree pseudostems, as a strategy to valorize banana crops residues. To increase the mechanical properties of the composite, technical textiles can be used as reinforcement, instead of short fibers. To do so, fibers must be spun and woven. The aim of this paper is to show the viability of using banana fibers to obtain a yarn suitable to be woven, after an enzymatic treatment, which is more environmentally friendly. Extracted long fibers are cut to 50 mm length and then immersed into an enzymatic bath for their refining. Conditions of enzymatic treatment have been optimized to produce a textile grade of banana fibers, which have then been characterized. The optimum treating conditions were found with the use of Biopectinase K (100% related to fiber weight) at 45 °C, pH 4.5 for 6 h, with bath renewal after three hours. The first spinning trials show that these fibers are suitable to be used for the production of yarns. The next step is the weaving process to obtain a technical fabric for composites production. PMID:28773490

  7. Production of Banana Fiber Yarns for Technical Textile Reinforced Composites.

    PubMed

    Ortega, Zaida; Morón, Moisés; Monzón, Mario D; Badalló, Pere; Paz, Rubén

    2016-05-13

    Natural fibers have been used as an alternative to synthetic ones for their greener character; banana fibers have the advantage of coming from an agricultural residue. Fibers have been extracted by mechanical means from banana tree pseudostems, as a strategy to valorize banana crops residues. To increase the mechanical properties of the composite, technical textiles can be used as reinforcement, instead of short fibers. To do so, fibers must be spun and woven. The aim of this paper is to show the viability of using banana fibers to obtain a yarn suitable to be woven, after an enzymatic treatment, which is more environmentally friendly. Extracted long fibers are cut to 50 mm length and then immersed into an enzymatic bath for their refining. Conditions of enzymatic treatment have been optimized to produce a textile grade of banana fibers, which have then been characterized. The optimum treating conditions were found with the use of Biopectinase K (100% related to fiber weight) at 45 °C, pH 4.5 for 6 h, with bath renewal after three hours. The first spinning trials show that these fibers are suitable to be used for the production of yarns. The next step is the weaving process to obtain a technical fabric for composites production.

  8. Fabrication and spin tests of composite flywheels

    NASA Astrophysics Data System (ADS)

    Hamamoto, A.; Inutake, T.; Kogai, K.

    Energy storage flywheels consisting of carbon fiber epoxy composite rims and aluminum or carbon fabric cloth epoxy composite hubs were designed, fabricated and tested. The composite rims were 38O mm in outer diameter and 300 mm in inner diameter with a thickness of 25 mm. The test rotor with a aluminum hub was spun to maximum peripheral speed of 982 m/s on burst test. This corresponds to an energy density, based upon total rotor weight, of approximately 71 Wh/kg. Another rotor, made use of a four rims configuration, was tested to 800 m/s successfully with no damage and no dynamic problem. The energy stored in the rotor is more than 500 Wh and the energy density is about 55 Wh/kg at that speed. The rotor with a composite hub was tested to the peripheral speed of 820 m/s. It was restricted by rotor dynamic problems.

  9. Fracture and fatigue of discontinuously reinforced copper/tungsten composites

    NASA Technical Reports Server (NTRS)

    Harris, B.; Ramani, S. V.

    1975-01-01

    The strength, toughness and resistance to cyclic crack propagation of composites consisting of copper reinforced with short tungsten wires of various lengths have been studied and the results compared with the behavior of continuously reinforced composites manufactured by the same method, i.e., by vacuum hot-pressing. It has been found that whereas the resistance to fatigue crack growth of continuously reinforced composites is very similar to that of continuous Al/stainless steel composites reported elsewhere, the addition of short fibers completely changes the mode of fracture, and no direct comparisons are possible. In effect, short fibers inhibit single crack growth by causing plastic flow to be distributed rather than localized, and although these composites are much less strong than continuous fiber composites, they nevertheless have much greater fatigue resistance.

  10. Fracture and fatigue of discontinuously reinforced copper/tungsten composites

    NASA Technical Reports Server (NTRS)

    Harris, B.; Ramani, S. V.

    1975-01-01

    The strength, toughness and resistance to cyclic crack propagation of composites consisting of copper reinforced with short tungsten wires of various lengths have been studied and the results compared with the behavior of continuously reinforced composites manufactured by the same method, i.e., by vacuum hot-pressing. It has been found that whereas the resistance to fatigue crack growth of continuously reinforced composites is very similar to that of continuous Al/stainless steel composites reported elsewhere, the addition of short fibers completely changes the mode of fracture, and no direct comparisons are possible. In effect, short fibers inhibit single crack growth by causing plastic flow to be distributed rather than localized, and although these composites are much less strong than continuous fiber composites, they nevertheless have much greater fatigue resistance.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  12. Reinforcing effect of glass fiber-reinforced composite reinforcement on flexural strength at proportional limit of a repaired denture base resin

    PubMed Central

    Yoshida, Kaneyoshi; Takahashi, Yutaka; Hamanaka, Ippei; Kawaguchi, Tomohiro; Sasaki, Hirono; Shimizu, Hiroshi

    2015-01-01

    Abstract Objective: This study evaluated the reinforcing effect of glass fiber-reinforced composite (FRC) reinforcement on flexural strength at the proportional limit (FS-PL) of a repaired denture base resin. Materials and methods: Repaired denture base resins reinforced with metal and with FRC reinforcement, and that without reinforcement were tested. The ultimate flexural strength, the FS-PL and the elastic modulus of repaired denture base resins were tested. The joint efficiency (times) of the repaired denture base resins on the intact denture base resin was evaluated. Results: The repaired denture base resins reinforced with metal reinforcement and with FRC reinforcement had significantly higher ultimate flexural strength than the repaired denture base resin without reinforcement (p < 0.05) and were not significantly different from each other (p > 0.05). The FS-PL of a repaired denture base resin reinforced with the FRC reinforcement was similar to that with the metal reinforcement (p > 0.05), and these were significantly higher than the FS-PL of a repaired denture base resin without reinforcement (p < 0.05). The elastic modulus of the repaired denture base resin reinforced with the FRC reinforcement was significantly lower than that with metal reinforcement (p < 0.05) and was significantly higher than that without reinforcement (p < 0.05). The joint efficiency of the FRC reinforced specimen was 0.98. Conclusion: The FRC reinforcement had a reinforcing effect on the FS-PL of a repaired denture base resin. PMID:28642906

  13. CAD for 4-step braided fabric composites

    SciTech Connect

    Pandey, R.; Hahn, H.T.

    1994-12-31

    A general framework is provided to predict thermoelastic properties of three dimensional 4-step braided fabric composites. Three key steps involved are (1) the development of a CAD model for yarn architecture, (2) the extraction of a unit cell (3) the prediction of the thermoelastic properties based on micromechanics. Main features of each step are summarized and experimental correlations are provided in the paper.

  14. Present State of the Art of Composite Fabric Forming: Geometrical and Mechanical Approaches

    PubMed Central

    Cherouat, Abel; Borouchaki, Houman

    2009-01-01

    Continuous fibre reinforced composites are now firmly established engineering materials for the manufacture of components in the automotive and aerospace industries. In this respect, composite fabrics provide flexibility in the design manufacture. The ability to define the ply shapes and material orientation has allowed engineers to optimize the composite properties of the parts. The formulation of new numerical models for the simulation of the composite forming processes must allow for reduction in the delay in manufacturing and an optimization of costs in an integrated design approach. We propose two approaches to simulate the deformation of woven fabrics: geometrical and mechanical approaches.

  15. Fabrication of commercial-scale fiber-reinforced hot-gas filters by chemical vapor deposition

    SciTech Connect

    White, L.R. . New Products Dept.)

    1992-11-01

    Goal was to fabricate a filter for removing particulates from hot gases; principal applications would be in advanced utility processes such as pressurized fluidized bed combustion or coal gasification combined cycle systems. Filters were made in two steps: make a ceramic fiber preform and coat it with SiC by chemical vapor infiltration (CVD). The most promising construction was felt/filament wound. Light, tough ceramic composite filters can be made; reinforcement by continuous fibers is needed to avoid brittleness. Direct metal to filter contact does not damage the top which simplifies installation. However, much of the filter surface of felt/filament wound structures is closed over by the CVD coating, and the surface is rough and subject to delamination. Recommendations are given for improving the filters.

  16. Microstructures of Nanotubes Reinforced Alumina Fabricated by Two Fast-Sintering Methods

    NASA Astrophysics Data System (ADS)

    Huang, L. W.; Fu, Z. Y.; Wang, H.; Lee, S. W.; Niihara, K.

    2011-03-01

    Spark plasma sintering (SPS) and Self-propagating High-temperature Synthesis/ quick pressing (SHS/QP) methods were used to fabricate nanotubes reinforced alumina. The difference in microstructure was discussed. In the SHS/QP process, the maximum densification temperature is 1660°C and the heating rate is about 1600°C /min. The whole densification process in SHS/QP is very short, which is much beneficial to protect the nanotubes and restrain the growing of grains. The fracture toughness of the sample prepared by SHS/QP is up to 4.9MPam½ for 1mass% CNTs/Al2O3 composites, which shows excellent toughening effects of nanotubes.

  17. Development of Al- and Cu-based nanocomposites reinforced by graphene nanoplatelets: Fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Saboori, Abdollah; Pavese, Matteo; Badini, Claudio; Fino, Paolo

    2017-06-01

    Aluminum and copper matrix nanocomposites reinforced by graphene nanoplatelets (GNPs) were successfully fabricated by a wet mixing method followed by conventional powder metallurgy. The uniform dispersion of GNPs within the metal matrices showed that the wet mixing method has a great potential to be used as a mixing technique. However, by increasing the GNPs content, GNPs agglomeration was more visible. DSC and XRD of Al/GNPs nanocomposites showed that no new phase formed below the melting point of Al. Microstructural observations in both nanocomposites reveal the evident grain refinement effect as a consequence of GNPs addition. The interfacial bonding evaluation shows a poor interfacial bonding between GNPs and Al, while the interfacial bonding between Cu and GNPs is strong enough to improve the properties of the Cu/GNPs nanocomposites. In both composites, the coefficient of thermal expansion decreases as a function of GNPs while, their hardness is improved by increasing the GNPs content as well as their elastic modulus.

  18. Fabrication of commercial-scale fiber-reinforced hot-gas filters by chemical vapor deposition

    SciTech Connect

    White, L.R.

    1992-11-01

    Goal was to fabricate a filter for removing particulates from hot gases; principal applications would be in advanced utility processes such as pressurized fluidized bed combustion or coal gasification combined cycle systems. Filters were made in two steps: make a ceramic fiber preform and coat it with SiC by chemical vapor infiltration (CVD). The most promising construction was felt/filament wound. Light, tough ceramic composite filters can be made; reinforcement by continuous fibers is needed to avoid brittleness. Direct metal to filter contact does not damage the top which simplifies installation. However, much of the filter surface of felt/filament wound structures is closed over by the CVD coating, and the surface is rough and subject to delamination. Recommendations are given for improving the filters.

  19. Investigations on Void Formation in Composite Molding Processes and Structural Damping in Fiber-Reinforced Composites with Nanoscale Reinforcements

    NASA Astrophysics Data System (ADS)

    DeValve, Caleb Joshua

    Fiber-reinforced composites (FRCs) offer a stronger and lighter weight alternative to traditional materials used in engineering components such as wind turbine blades and rotorcraft structures. Composites for these applications are often fabricated using liquid molding techniques, such as injection molding or resin transfer molding. One significant issue during these processing methods is void formation due to incomplete wet-out of the resin within the fiber preform, resulting in discontinuous material properties and localized failure zones in the material. A fundamental understanding of the resin evolution during processing is essential to designing processing conditions for void-free filling, which is the first objective of the dissertation. Secondly, FRCs used in rotorcraft experience severe vibrational loads during service, and improved damping characteristics of the composite structure are desirable. To this end, a second goal is to explore the use of matrix-embedded nanoscale reinforcements to augment the inherent damping capabilities in FRCs. The first objective is addressed through a computational modeling and simulation of the infiltrating dual-scale resin flow through the micro-architectures of woven fibrous preforms, accounting for the capillary effects within the fiber bundles. An analytical model is developed for the longitudinal permeability of flow through fibrous bundles and applied to simulations which provide detailed predictions of local air entrapment locations as the resin permeates the preform. Generalized design plots are presented for predicting the void content and processing time in terms of the Capillary and Reynolds Numbers governing the molding process. The second portion of the research investigates the damping enhancement provided to FRCs in static and rotational configurations by different types and weight fractions of matrix-embedded carbon nanotubes (CNTs) in high fiber volume fraction composites. The damping is measured using

  20. Recent progress in NASA Langley Research Center textile reinforced composites program

    NASA Technical Reports Server (NTRS)

    Dexter, H. Benson; Harris, Charles E.; Johnston, Norman J.

    1992-01-01

    Research was conducted to explore the benefits of textile reinforced composites for transport aircraft primary structures. The objective is to develop and demonstrate the potential of affordable textile reinforced composite materials to meet design properties and damage tolerance requirements of advanced aircraft structural concepts. Some program elements include development of textile preforms, processing science, mechanics of materials, experimental characterization of materials, and development and evaluation of textile reinforced composite structural elements and subcomponents. Textile 3-D weaving, 3-D braiding, and knitting and/or stitching are being compared with conventional laminated tape processes for improved damage tolerance. Through-the-thickness reinforcements offer significant damage tolerance improvements. However, these gains must be weighted against potential loss in in-plane properties such as strength and stiffness. Analytical trade studies are underway to establish design guidelines for the application of textile material forms to meet specific loading requirements. Fabrication and testing of large structural parts are required to establish the potential of textile reinforced composite materials.

  1. Designing bioinspired composite reinforcement architectures via 3D magnetic printing

    PubMed Central

    Martin, Joshua J.; Fiore, Brad E.; Erb, Randall M.

    2015-01-01

    Discontinuous fibre composites represent a class of materials that are strong, lightweight and have remarkable fracture toughness. These advantages partially explain the abundance and variety of discontinuous fibre composites that have evolved in the natural world. Many natural structures out-perform the conventional synthetic counterparts due, in part, to the more elaborate reinforcement architectures that occur in natural composites. Here we present an additive manufacturing approach that combines real-time colloidal assembly with existing additive manufacturing technologies to create highly programmable discontinuous fibre composites. This technology, termed as ‘3D magnetic printing', has enabled us to recreate complex bioinspired reinforcement architectures that deliver enhanced material performance compared with monolithic structures. Further, we demonstrate that we can now design and evolve elaborate reinforcement architectures that are not found in nature, demonstrating a high level of possible customization in discontinuous fibre composites with arbitrary geometries. PMID:26494282

  2. Designing bioinspired composite reinforcement architectures via 3D magnetic printing

    NASA Astrophysics Data System (ADS)

    Martin, Joshua J.; Fiore, Brad E.; Erb, Randall M.

    2015-10-01

    Discontinuous fibre composites represent a class of materials that are strong, lightweight and have remarkable fracture toughness. These advantages partially explain the abundance and variety of discontinuous fibre composites that have evolved in the natural world. Many natural structures out-perform the conventional synthetic counterparts due, in part, to the more elaborate reinforcement architectures that occur in natural composites. Here we present an additive manufacturing approach that combines real-time colloidal assembly with existing additive manufacturing technologies to create highly programmable discontinuous fibre composites. This technology, termed as `3D magnetic printing', has enabled us to recreate complex bioinspired reinforcement architectures that deliver enhanced material performance compared with monolithic structures. Further, we demonstrate that we can now design and evolve elaborate reinforcement architectures that are not found in nature, demonstrating a high level of possible customization in discontinuous fibre composites with arbitrary geometries.

  3. Carbon Fiber Reinforced Ceramic Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  4. Carbon Fiber Reinforced Ceramic Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  5. Finite strain formulation of viscoelastic damage model for simulation of fabric reinforced polymers under dynamic loading

    NASA Astrophysics Data System (ADS)

    Treutenaere, S.; Lauro, F.; Bennani, B.; Matsumoto, T.; Mottola, E.

    2015-09-01

    The use of fabric reinforced polymers in the automotive industry is growing significantly. The high specific stiffness and strength, the ease of shaping as well as the great impact performance of these materials widely encourage their diffusion. The present model increases the predictability of explicit finite element analysis and push the boundaries of the ongoing phenomenological model. Carbon fibre composites made up various preforms were tested by applying different mechanical load up to dynamic loading. This experimental campaign highlighted the physical mechanisms affecting the initial mechanical properties, namely intra- and interlaminar matrix damage, viscoelasticty and fibre failure. The intralaminar behaviour model is based on the explicit formulation of the matrix damage model developed by the ONERA as the given damage formulation correlates with the experimental observation. Coupling with a Maxwell-Wiechert model, the viscoelasticity is included without losing the direct explicit formulation. Additionally, the model is formulated under a total Lagrangian scheme in order to maintain consistency for finite strain. Thus, the material frame-indifference as well as anisotropy are ensured. This allows reorientation of fibres to be taken into account particularly for in-plane shear loading. Moreover, fall within the framework of the total Lagrangian scheme greatly makes the parameter identification easier, as based on the initial configuration. This intralaminar model thus relies upon a physical description of the behaviour of fabric composites and the numerical simulations show a good correlation with the experimental results.

  6. Fabrication and EM shielding properties of electrospining PANi/MWCNT/PEO fibrous membrane and its composite

    NASA Astrophysics Data System (ADS)

    Zhang, Zhichun; Jiang, Xueyong; Liu, Yanju; Leng, Jinsong

    2012-04-01

    In this paper, Polyaniline-based fibrous membranes were fabricated with multi-walled carbon nanotubes and polyethylene oxide (PEO) by the electrospinning method. And then PANi/PEO/MWCNT fibrous membranes reinforced epoxy based nanocomposite was then fabricated. The morphology and electrical properties of PANi /MWCNT /PEO fibrous membrane was characterized by scanning electron microscope (SEM). The morphologies of the membranes indicate that the electrospining method can fabricate well nano structures fibrous membrane. The EM properties of the composite reinforced with the electrospining fibrous membrane were measured by vector network analyzer. The results show that the permittivity real, image parts and permeability real part of the composite increase by filling with PANI/PEO and PANI/CNT/PEO membrane. The EM shielding and absorb performance is base on the dielectric dissipation. And different membranes made of different materials show different EM parameter, and different EM shielding performance, which can be used to the EM shielding and stealth material design and fabrication.

  7. Method for fabricating laminated uranium composites

    DOEpatents

    Chapman, L.R.

    1983-08-03

    The present invention is directed to a process for fabricating laminated composites of uranium or uranium alloys and at least one other metal or alloy. The laminated composites are fabricated by forming a casting of the molten uranium with the other metal or alloy which is selectively positioned in the casting and then hot-rolling the casting into a laminated plate in or around which the casting components are metallurgically bonded to one another to form the composite. The process of the present invention provides strong metallurgical bonds between the laminate components primarily since the bond disrupting surface oxides on the uranium or uranium alloy float to the surface of the casting to effectively remove the oxides from the bonding surfaces of the components.

  8. Fabrication of latex rubber reinforced with micellar nanoparticle as an interface modifier

    USDA-ARS?s Scientific Manuscript database

    Reinforced latex rubbers were fabricated by incorporating small amount of nanoparticles as interface modifier. The rubbers were fabricated in a compression mold at 130°C. The incorporated nanoparticles were prepared from wheat protein (gliadin) and ethyl cyanoacrylate (ECA). These nanoparticles were...

  9. Low Temperature Thermal Conductivity of Woven Fabric Glass Fibre Composites

    NASA Astrophysics Data System (ADS)

    Kanagaraj, S.; Pattanayak, S.

    2004-06-01

    Fibre reinforced composites are replacing conventional materials due to its compatible and superior properties at low temperatures. Transverse thermal conductivity of plain fabric E-glass/Epoxy composites with the fibre concentrations of 32.5%, 35.2%, 39.2% and 48.9% has been studied in a GM-refrigerator based experimental setup using guarded hotplate technique. Experiments are carried out with the sets of stability criteria. This paper presents the investigation of the influence of the fibre concentration and temperature on the thermal conductivity of fabric composites from 30 K to 300K. It is observed from the experimental results that thermal conductivity increases with the increase of temperature and also with fibre concentration with different rate in different temperature range. The series model has been used to predict the thermal conductivity and compared with the experimental results. It is observed that below the crossover temperature of the composites, which varies from 150-225K depending upon their fibre concentration, the experimental results are within 10% with that of predicted values. The possible causes of variation are analyzed. The physical phenomenon behind the temperature dependence of thermal conductivity is discussed in detail.

  10. Low Temperature Thermal Conductivity of Woven Fabric Glass Fibre Composites

    SciTech Connect

    Kanagaraj, S.; Pattanayak, S.

    2004-06-28

    Fibre reinforced composites are replacing conventional materials due to its compatible and superior properties at low temperatures. Transverse thermal conductivity of plain fabric E-glass/Epoxy composites with the fibre concentrations of 32.5%, 35.2%, 39.2% and 48.9% has been studied in a GM-refrigerator based experimental setup using guarded hotplate technique. Experiments are carried out with the sets of stability criteria. This paper presents the investigation of the influence of the fibre concentration and temperature on the thermal conductivity of fabric composites from 30 K to 300K. It is observed from the experimental results that thermal conductivity increases with the increase of temperature and also with fibre concentration with different rate in different temperature range. The series model has been used to predict the thermal conductivity and compared with the experimental results. It is observed that below the crossover temperature of the composites, which varies from 150-225K depending upon their fibre concentration, the experimental results are within 10% with that of predicted values. The possible causes of variation are analyzed. The physical phenomenon behind the temperature dependence of thermal conductivity is discussed in detail.

  11. Early Damage Detection in Composites during Fabrication and Mechanical Testing

    PubMed Central

    Chandarana, Neha; Sanchez, Daniel Martinez; Soutis, Constantinos; Gresil, Matthieu

    2017-01-01

    Fully integrated monitoring systems have shown promise in improving confidence in composite materials while reducing lifecycle costs. A distributed optical fibre sensor is embedded in a fibre reinforced composite laminate, to give three sensing regions at different levels through-the-thickness of the plate. This study follows the resin infusion process during fabrication of the composite, monitoring the development of strain in-situ and in real time, and to gain better understanding of the resin rheology during curing. Piezoelectric wafer active sensors and electrical strain gauges are bonded to the plate after fabrication. This is followed by progressive loading/unloading cycles of mechanical four point bending. The strain values obtained from the optical fibre are in good agreement with strain data collected by surface mounted strain gauges, while the sensing regions clearly indicate the development of compressive, neutral, and tensile strain. Acoustic emission event detection suggests the formation of matrix (resin) cracks, with measured damage event amplitudes in agreement with values reported in published literature on the subject. The Felicity ratio for each subsequent loading cycle is calculated to track the progression of damage in the material. The methodology developed here can be used to follow the full life cycle of a composite structure, from manufacture to end-of-life. PMID:28773048

  12. Novel processes for near net-shaped fabrication of monolithic and reinforced oxide ceramics

    NASA Astrophysics Data System (ADS)

    Kumar, Pragati

    Mg reinforced Alsb2Osb3 composites were fabricated by pressureless infiltration of molten Mg into porous Alsb2Osb3 preforms. Such pressureless infiltration is thought to be driven by a displacement reaction that was observed to occur at interfaces between liquid Mg and solid Alsb2Osb3. The feasibility of fabricating near net-shaped, monolithic, MgAlsb2Osb4 spinel bodies by the oxidation of the solid Mg-Alsb2Osb3-bearing composites was demonstrated. By controlling the preform porosity and the infiltration conditions, Mg-Alsb2Osb3-bearing composite bodies could be produced with the proper overall stoichiometry for spinel. The Mg/Alsb2Osb3 composites could be machined into complex shapes. Oxidation of the Mg in the shaped composite was conducted in pure, flowing oxygen at 430{-}700sp°C. Post-oxidation annealing at 1200sp°C then allowed for complete conversion of MgO-Alsb2Osb3 bearing body into MgAlsb2Osb4 spinel. A final sintering treatment in flowing Ar at 1700sp°C yielded spinel specimens with densities ≥92%. The sintered spinel bodies retained the Mg-Alsb2Osb3-bearing precursor shape and dimensions (to within 0.63%). The fabrication of spinel-matrix composites is also discussed. In addition, a novel approach is presented for the fabrication of dense, shaped ceramic/metal composites by a novel class of displacement reactions. This approach differs from other oxidation-based processes for fabricating near net-shaped oxide/metal composites (e.g. DIMOX, Csp4) in that a reaction-induced volume expansion is used to compensate for the porosity within a preform, so as to yield a dense composite with a high ceramic content. In the present case, a displacement reaction between liquid Mg and solid Alsb2Osb3 was used to produce composites of MgO and Mg-bearing metal. Porous, shaped Alsb2Osb3 preforms were placed in contact with a Mg(l) bath at 1000sp°C. The liquid Mg completely infiltrated and consumed the Alsb2Osb3 preform by the following net reaction:$3Mg(l) + Alsb2

  13. Method for Forming Fiber Reinforced Composite Bodies with Graded Composition and Stress Zones

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay (Inventor); Levine, Stanley R. (Inventor); Smialek, James A. (Inventor)

    1999-01-01

    A near-net, complex shaped ceramic fiber reinforced silicon carbide based composite bodies with graded compositions and stress zones is disclosed. To provide the composite a fiber preform is first fabricated and an interphase is applied by chemical vapor infiltration, sol-gel or polymer processes. This first body is further infiltrated with a polymer mixture containing carbon, and/or silicon carbide, and additional oxide, carbide, or nitride phases forming a second body. One side of the second body is spray coated or infiltrated with slurries containing high thermal expansion and oxidation resistant. crack sealant phases and the other side of this second body is coated with low expansion phase materials to form a third body. This third body consisting of porous carbonaceous matrix surrounding the previously applied interphase materials, is then infiltrated with molten silicon or molten silicon-refractory metal alloys to form a fourth body. The resulting fourth body comprises dense composites consisting of fibers with the desired interphase which are surrounded by silicon carbide and other second phases materials at the outer and inner surfaces comprising material of silicon, germanium, refractory metal suicides, borides, carbides, oxides, and combinations thereof The resulting composite fourth body has different compositional patterns from one side to the other.

  14. Mechanical properties of fiber reinforced lightweight concrete composites

    SciTech Connect

    Perez-Pena, M. ); Mobasher, B. )

    1994-01-01

    Hybrid composites with variable strength/toughness properties can be manufactured using combinations of brittle or ductile mesh in addition to brittle and ductile matrix reinforcements. The bending and tensile properties of thin sheet fiber cement composites made from these mixtures were investigated. Composites consisted of a woven mesh of either polyvinyl chloride (PVC) coated E-glass or polypropylene (PP) fibers for the surface reinforcement. In addition, chopped polypropylene, acrylic, nylon, and alkali-resistant (AR) glass fibers were used for the core reinforcement. It is shown that by controlling fiber contents, types, and combinations, design objectives such as strength, stiffness and toughness, can be achieved. Superior post-cracking behavior was measured for composites reinforced both with glass mesh and PP mesh. Load carrying capacity of PP mesh composites can be increased with the use of 1% or higher chopped PP fibers. Glass mesh composites with short AR glass fibers as matrix reinforcement indicate an increased matrix cracking strength and modulus of rupture. Combinations of PP mesh/short AR glass did not show a substantial improvement in the matrix ultimate strength. An increased nylon fiber surface area resulted in improved post peak response.

  15. Multilayered Glass Fibre-reinforced Composites In Rotational Moulding

    NASA Astrophysics Data System (ADS)

    Chang, W. C.; Harkin-Jones, E.; Kearns, M.; McCourt, M.

    2011-05-01

    The potential of multiple layer fibre-reinforced mouldings is of growing interest to the rotational moulding industry because of their cost/performance ratio. The particular problem that arises when using reinforcements in this process relate to the fact that the process is low shear and good mixing of resin and reinforcement is not optimum under those conditions. There is also a problem of the larger/heavier reinforcing agents segregating out of the powder to lay up on the inner part surface. In this study, short glass fibres were incorporated and distributed into a polymer matrix to produce fibre-reinforced polymer composites using the rotational moulding process and characterised in terms of morphology and mechanical properties.

  16. Multilayered Glass Fibre-reinforced Composites In Rotational Moulding

    SciTech Connect

    Chang, W. C.; Harkin-Jones, E.; Kearns, M.; McCourt, M.

    2011-05-04

    The potential of multiple layer fibre-reinforced mouldings is of growing interest to the rotational moulding industry because of their cost/performance ratio. The particular problem that arises when using reinforcements in this process relate to the fact that the process is low shear and good mixing of resin and reinforcement is not optimum under those conditions. There is also a problem of the larger/heavier reinforcing agents segregating out of the powder to lay up on the inner part surface. In this study, short glass fibres were incorporated and distributed into a polymer matrix to produce fibre-reinforced polymer composites using the rotational moulding process and characterised in terms of morphology and mechanical properties.

  17. Mechanical properties of woven glass fiber-reinforced composites.

    PubMed

    Kanie, Takahito; Arikawa, Hiroyuki; Fujii, Koichi; Ban, Seiji

    2006-06-01

    The aim of this investigation was to measure the flexural and compressive strengths and the corresponding moduli of cylindrical composite specimens reinforced with woven glass fiber. Test specimens were made by light-curing urethane dimethacrylate oligomer with woven glass fiber of 0.18-mm standard thickness. Tests were conducted using four reinforcement methods and two specimen diameters. Flexural strength and modulus of woven glass fiber-reinforced specimens were significantly greater than those without woven glass fiber (p < 0.01). Likewise, compressive strength of reinforced specimens was significantly greater than those without woven glass fiber (p < 0.01), except for specimens reinforced with woven glass fiber oriented at a tilt direction in the texture (p > 0.05). In terms of comparison between the two specimen diameters, no statistically significant differences in flexural strength and compressive strength (p > 0.05) were observed.

  18. Design and reinforcement: vertically aligned carbon nanotube-based sandwich composites.

    PubMed

    Zeng, You; Ci, Lijie; Carey, Brent J; Vajtai, Robert; Ajayan, Pulickel M

    2010-11-23

    Carbon nanotube (CNT) reinforcement of polymer composites has not yielded optimum results in that the composite properties are typically compromised by poor dispersion and random orientation of CNTs in polymers. Given the short lengths available for nanotubes, opportunities lie in incorporating CNTs with other structural reinforcements such as carbon fibers (CFs) to achieve improvement over existing composite designs. Growth of vertically aligned CNTs (VACNTs) offers new avenues for designing high-performance composites by integrating CFs and nanotubes into layered 3D architectures. To obtain composites with high rigidity and damping, we have designed and fabricated VACNT-based sandwich composites from simply stacking the freestanding VACNTs and CF fabrics and infiltrating with epoxy matrix. Comparing with the CF/epoxy laminates, the VACNT-based sandwich composites exhibit higher flexural rigidity and damping, which is achieved due to the effective integration of the VACNTs as an interfacial layer between the CF stacks. Furthermore, the lighter weight of these VACNT-based sandwich composites offers advantages in aerospace and transportation applications.

  19. An Assessment of Self-Healing Fiber Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Smith, Joseph G., Jr.

    2012-01-01

    Several reviews and books have been written concerning self-healing polymers over the last few years. These have focused primarily on the types of self-healing materials being studied, with minor emphasis given to composite properties. The purpose of this review is to assess the self-healing ability of these materials when utilized in fiber reinforced composites

  20. Coir fiber reinforced polypropylene composite panel for automotive interior applications

    Treesearch

    Nadir Ayrilmis; Songklod Jarusombuti; Vallayuth Fueangvivat; Piyawade Bauchongkol; Robert H. White

    2011-01-01

    In this study, physical, mechanical, and flammability properties of coconut fiber reinforced polypropylene (PP) composite panels were evaluated. Four levels of the coir fiber content (40, 50, 60, and 70 % based on the composition by weight) were mixed with the PP powder and a coupling agent, 3 wt % maleic anhydride grafted PP (MAPP) powder. The water resistance and the...

  1. Interfacial reactions in SiC{sub p}/Al composite fabricated by pressureless infiltration

    SciTech Connect

    Lee, K.B.; Kwon, H.

    1997-04-15

    Metal matrix composites (MMCs) reinforced by ceramic phases have been fabricated by various techniques including powder metallurgy, casting, etc. Recently Lanxide corporation developed the DIMOX and PRIMEX processes for fabricating ceramic- and metal-matrix composites, respectively. The PRIMEX process is an innovative technique for fabricating MMCs by the spontaneous infiltration of molten AL alloy containing Mg into a ceramic filler or preform under nitrogen atmosphere in pressureless state without the aid of vacuum or externally applied pressure. Although there were many patents on MMC fabrication by the above pressureless infiltration technique, however, few works on the resulting microstructures and their effects on mechanical properties were reported. Thus, in this study, the effects on interfacial reactions occurring during the fabrication of SiC{sub p}AL composite by the pressureless infiltration technique on microstructures and hardness have been investigated.

  2. Composite reinforced propellant tanks. [space shuttles

    NASA Technical Reports Server (NTRS)

    Brown, L. D.; Martin, M. J.; Aleck, B. J.; Landes, R.

    1975-01-01

    Design studies involving weight and cost were carried out for several structural concepts applicable to space shuttle disposable tankage. An effective design, a honeycomb stabilized pressure vessel, was chosen. A test model was designed and fabricated.

  3. Fatigue strengths of particulate filler composites reinforced with fibers.

    PubMed

    Bae, Ji-Myung; Kim, Kyoung-Nam; Hattori, Masayuki; Hasegawa, Koji; Yoshinari, Masao; Kawada, Eiji; Oda, Yutaka

    2004-06-01

    The aim of this study was to evaluate the dynamic fatigue strengths at 10(5) cycles and the strains of particulate filler composite resins with and without reinforcing fibers. An UHMWPE (Ribbond), a polyaromatic polyamide fiber (Fibreflex), and three glass fibers (GlasSpan, FibreKor, Vectris Frame) were used to reinforce the particulate filler composite resins. The fatigue properties were measured in three-point bending mode using a servohydraulic universal testing machine at a frequency of 5 Hz, until failure occurred or 10(5) cycles had been completed. The fatigue strengths at 10(5) cycles were determined by the staircase method. The fractured aspects of specimens were evaluated by an optical and scanning electron microscope. The fatigue strengths of particulate filler composite resins were 49-57 MPa, and those of fiber-reinforced were 90-209 MPa. Unidirectional glass fibers showed higher reinforcing effects on the fatigue strengths of composite resins. The strain of UHMWPE-reinforced composite was largest.

  4. Analysis of stress-strain, fracture, and ductility behavior of aluminum maxtrix composites containing discontinuous silicon carbide reinforcement

    NASA Technical Reports Server (NTRS)

    Mcdanels, D. L.

    1985-01-01

    Mechanical properties and stress-strain behavior were evaluated for several types of commercially fabricated aluminum matrix composites, containing up to 40 vol pct discontinuous SiC whisker, nodule, or particulate reinforcement. The elastic modulus of the composites was found to be isotropic, to be independent of type of reinforcement, and to be controlled solely by the volume percentage of SiC reinforcement present. The yield/tensile strengths and ductility were controlled primarily by the matrix alloy and temper condition. Type and orientation of reinforcement had some effect on the strengths of composites, but only for those in which the whisker reinforcement was highly oriented. Ductility decreased with increasing reinforcement content; however, the fracture strains observed were higher than those reported in the literature for this type of composite. This increase in fracture strain was probably attributable to cleaner matrix powder, better mixing, and increased mechanical working during fabrication. Comparison of properties with conventional aluminum and titanium structural alloys showed that the properties of the low-cost, lightweight composites demonstrated very good potential for application to aerospace structures.

  5. Analysis of stress-strain, fracture, and ductility behavior of aluminum maxtrix composites containing discontinuous silicon carbide reinforcement

    NASA Technical Reports Server (NTRS)

    Mcdanels, D. L.

    1985-01-01

    Mechanical properties and stress-strain behavior were evaluated for several types of commercially fabricated aluminum matrix composites, containing up to 40 vol pct discontinuous SiC whisker, nodule, or particulate reinforcement. The elastic modulus of the composites was found to be isotropic, to be independent of type of reinforcement, and to be controlled solely by the volume percentage of SiC reinforcement present. The yield/tensile strengths and ductility were controlled primarily by the matrix alloy and temper condition. Type and orientation of reinforcement had some effect on the strengths of composites, but only for those in which the whisker reinforcement was highly oriented. Ductility decreased with increasing reinforcement content; however, the fracture strains observed were higher than those reported in the literature for this type of composite. This increase in fracture strain was probably attributable to cleaner matrix powder, better mixing, and increased mechanical working during fabrication. Comparison of properties with conventional aluminum and titanium structural alloys showed that the properties of the low-cost, lightweight composites demonstrated very good potential for application to aerospace structures.

  6. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 1: Concept development and feasibility

    NASA Technical Reports Server (NTRS)

    Oken, S.; June, R. R.

    1971-01-01

    The analytical and experimental investigations are described in the first phase of a program to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites. The interactions resulting from combining the two types of materials into single assemblies as well as their ability to function structurally were studied. The combinations studied were boron-epoxy reinforced aluminum, boron-epoxy reinforced titanium, and boron-polyimide reinforced titanium. The concepts used unidirectional composites as reinforcement in the primary loading direction and metal for carrying the transverse loads as well as its portion of the primary load. The program established that several realistic concepts could be fabricated, that these concepts could perform to a level that would result in significant weight savings, and that there are means for predicting their capability within a reasonable degree of accuracy. This program also encountered problems related to the application of polyimide systems that resulted in their relatively poor and variable performance.

  7. Transverse isotropic modeling of the ballistic response of glass reinforced plastic composites

    SciTech Connect

    Taylor, P.A.

    1997-12-31

    The use of glass reinforced plastic (GRP) composites is gaining significant attention in the DoD community for use in armor applications. These materials typically possess a laminate structure consisting of up to 100 plies, each of which is constructed of a glass woven roving fabric that reinforces a plastic matrix material. Current DoD attention is focused on a high strength, S-2 glass cross-weave (0/90) fabric reinforcing a polyester matrix material that forms each ply of laminate structure consisting anywhere from 20 to 70 plies. The resulting structure displays a material anisotropy that is, to a reasonable approximation, transversely isotropic. When subjected to impact and penetration from a metal fragment projectile, the GRP displays damage and failure in an anisotropic manner due to various mechanisms such as matrix cracking, fiber fracture and pull-out, and fiber-matrix debonding. In this presentation, the author will describe the modeling effort to simulate the ballistic response of the GRP material described above using the transversely isotropic (TI) constitutive model which has been implemented in the shock physics code, CTH. The results of this effort suggest that the model is able to describe the delamination behavior of the material but has some difficulty capturing the in-plane (i.e., transverse) response of the laminate due to its cross-weave fabric reinforcement pattern which causes a departure from transverse isotropy.

  8. Novel soft magnetic composites fabricated by electrodeposition

    NASA Astrophysics Data System (ADS)

    Yu, R. H.; Ren, L.; Basu, S.; Unruh, K. M.; Parvizi-Majidi, A.; Xiao, John Q.

    2000-05-01

    Soft magnetic composites have been fabricated by electrodepositing FeNi and FeCo onto W fibers with a diameter of 20 and 100 μm. Structural and compositional characterizations indicate that FeNi and FeCo-based composites are of fcc and bcc structure, respectively. The mechanical strengths are significantly improved depending on the volume fraction of W fibers. To further improve the mechanical properties of these composites, we have codeposited soft magnets and Al2O3 powders, resulting in an increase in Vickers hardness of more than 100%. Magnetic measurements show that as-deposited fibers are not magnetically soft. After proper thermal annealing, the samples exhibit excellent soft magnetic properties.

  9. High Tc superconductors - Composite wire fabrication

    NASA Astrophysics Data System (ADS)

    Jin, S.; Sherwood, R. C.; van Dover, R. B.; Tiefel, T. H.; Johnson, D. W., Jr.

    1987-07-01

    The fabrication of fine-wire, composite superconductors consisting of a high-conductivity normal metal shell, such as Ag or Cu/Ni/Au, and a superconducting core of Ba2YCu3O oxide is described. The functions of the normal metal shell and the importance of using the proper diffusion barrier metals are discussed. A resistivity-temperature curve for the composite wire Ag/Ba2YCu3O7 is examined, and the compound inside the finished wire is analyzed using X-ray diffraction. It is observed that the zero-field critical current density of the wire at 77 K is about 175 A/sq cm and the superconducting core is continuous and retains phase composition after wire drawing and heat treatment. The supplying of oxygen to the core of the long wire during heat treatments is studied. The data reveal that it is possible to process ceramic superconductors into a desirable composite wire form.

  10. Composite Properties of RTM370 Polyimide Fabricated by Vacuum Assisted Resin Transfer Molding (VARTM)

    NASA Technical Reports Server (NTRS)

    Chuang, Kathy C.; Criss, James M.; Mintz, Eric A.; Shonkwiler, Brian; McCorkle, Linda S.

    2011-01-01

    RTM370 imide resin based on 2,3,3?,4?-biphenyl dianhydride (a-BPDA), 3,4'-oxydianinline (3,4'-ODA) with the 4-phenylethynylphthalic (PEPA) endcap has been shown to exhibit a high cured T(sub g) (370 C) and low melt viscosity (10-30 poise) at 280 C with a pot-life of 1-2 h. Previously, RTM370 resin has been successfully fabricated into composites reinforced with T650-35 carbon fabrics by resin transfer molding (RTM). RTM370 composites exhibit excellent mechanical properties up to 327?C (620?F), and outstanding property retention after aging at 288?C (550?F) for 1000 h. In this work, RTM370 composites were fabricated by vacuum assisted resin transfer molding (VARTM), using vacuum bags on a steel plate. The mechanical properties of RTM370 composites fabricated by VARTM are compared to those prepared by RTM.

  11. Fabrication, characterization, and modeling of microvascular composites

    NASA Astrophysics Data System (ADS)

    Ryan, Thomas J.

    Composite laminates of glass fiber and epoxy pre-preg were fabricated with microvascular channels. The channels were created using polylactic acid (PLA) filament that evaporates at a temperature of 392 °F (200 °C) above the resin cure temperature of 250 °F (121 °C). After the composite is cured, the panel was removed from the oven and allowed to cool to room temperature. The panel is then reheated to 392 °F to vaporize the filament, leaving a cylindrical channel. A microvascular channel can be used for withdrawing heat, damage detection and self-healing. However, increasing the temperatures of the laminate above the cure temperature of the resin causes excess cross linking, potentially decreasing the mechanical properties. Tensile and flexural mechanical tests were performed on composite specimens and tensile tests were performed on neat resin specimens. A three-dimensional finite element model (FEM) was developed to study the progressive deformation and damage mechanics under tensile loading. The load carrying capacity of the microvascular composite was shown to decrease by 40% from a standard composite material. This paper will present the details of the fabrication, characterization and modeling techniques that were used in this study.

  12. Bio-composites fabricated by sandwiching sisal fibers with polypropylene (PP)

    SciTech Connect

    Sosiati, H.; Nahyudin, A. Fauzi, I. Wijayanti, D. A.; Triyana, K.

    2016-04-19

    Sisal fibers reinforced polypropylene (PP) composites were successfully fabricated using sandwiching sisal fibers with PP sheets. The ratio of fiber and polymer matrix was 50:50 (wt. %). Untreated short and long sisal fibers, and alkali treated short sisal fibers in 6% NaOH at 100°C for 1 and 3 h were used as reinforcement or fillers. A small amount (3 wt. %) of maleic anhydride grafted polypropylene (MAPP) was added as a coupling agent. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were used to characterize the surface morphology and chemical composition of the fibers, respectively. Flexural test of sisal/PP composites was done according to ASTM D 790-02. The results showed that flexural strength of untreated long fiber reinforced composite is much higher than that of the untreated and alkali treated short fibers reinforced composites with and without the addition of MAPP. Alkalization related to fiber surface modification, fiber length/fiber orientation and a composite fabrication technique are important factors in contributing to the fiber distribution within the matrix, the bonding between the fiber and the matrix and the enhancement of flexural strength of the bio-composite.

  13. Bio-composites fabricated by sandwiching sisal fibers with polypropylene (PP)

    NASA Astrophysics Data System (ADS)

    Sosiati, H.; Nahyudin, A.; Fauzi, I.; Wijayanti, D. A.; Triyana, K.

    2016-04-01

    Sisal fibers reinforced polypropylene (PP) composites were successfully fabricated using sandwiching sisal fibers with PP sheets. The ratio of fiber and polymer matrix was 50:50 (wt. %). Untreated short and long sisal fibers, and alkali treated short sisal fibers in 6% NaOH at 100°C for 1 and 3 h were used as reinforcement or fillers. A small amount (3 wt. %) of maleic anhydride grafted polypropylene (MAPP) was added as a coupling agent. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were used to characterize the surface morphology and chemical composition of the fibers, respectively. Flexural test of sisal/PP composites was done according to ASTM D 790-02. The results showed that flexural strength of untreated long fiber reinforced composite is much higher than that of the untreated and alkali treated short fibers reinforced composites with and without the addition of MAPP. Alkalization related to fiber surface modification, fiber length/fiber orientation and a composite fabrication technique are important factors in contributing to the fiber distribution within the matrix, the bonding between the fiber and the matrix and the enhancement of flexural strength of the bio-composite.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  15. Fiber-reinforced Composite for Chairside Replacement of Anterior Teeth: A Case Report

    PubMed Central

    Garoushi, S; Vallittu, PK; Lassila, LVJ

    2008-01-01

    A variety of therapeutic modalities, from implant to conventional Maryland prosthesis, can be used for the replacement of a missing anterior tooth. Whenever a minimal tooth reduction is preferred, a fiber reinforced composite (FRC) prosthesis could be a good alternative to conventional prosthetic techniques, chiefly as temporary restoration before making a final decision on the treatment. The purpose of this case report is to describe the clinical procedure of fabricating anterior chairside FRC prosthesis with pre-impregnated unidirectional E-glass fibers and veneered particulate filler composite. Fiber-reinforced composite in combination with adhesive technology appears to be a promising treatment option for replacing missing teeth. However, further and long-term clinical investigation will be required to provide additional information on the survival of directly-bonded anterior fixed prosthesis made with FRC systems. PMID:21499473

  16. Network model for thermal conductivities of unidirectional fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Peng, Chaoyi; Zhang, Weihua

    2014-12-01

    An empirical network model has been developed to predict the in-plane thermal conductivities along arbitrary directions for unidirectional fiber-reinforced composites lamina. Measurements of thermal conductivities along different orientations were carried out. Good agreement was observed between values predicted by the network model and the experimental data; compared with the established analytical models, the newly proposed network model could give values with higher precision. Therefore, this network model is helpful to get a wider and more comprehensive understanding of heat transmission characteristics of fiber-reinforced composites and can be utilized as guidance to design and fabricate laminated composites with specific directional or specific locational thermal conductivities for structures that simultaneously perform mechanical and thermal functions, i.e. multifunctional structures (MFS).

  17. [The effect of glass fiber volume content on the flexural property of fiber-reinforced composite].

    PubMed

    Yang, Jie; Xie, Hai-feng; Song, Xin; Liu, Mei; Zhang, Fei-min

    2016-02-01

    To investigate the effect of glass fiber volume content on the flexural property of fiber-reinforced composite. METHODS: The specimens of composite were fabricated with 4 different glass fiber volume contents by changing roving winded number of strands dipped in resin matrix, and the mechanical properties were tested by 3-point flexural test in order to determine the optimal fiber volume content. The data was analyzed statistically with SPSS20.0 software package. Self-made fiber-reinforced composites with the glass fiber volume content percentage of 60.4% achieved the maximal flexural strength and the maximal elastic modulus. As the glass fiber content in matrix of composite material is increased in certain range, the flexural strength and the elastic modulus can be improved,then reaches the peak. However, the flexural property decreases rather than rises when the fiber content is more than 60.4%.

  18. 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.

  19. Investigation of mechanical properties of aluminium reinforced glass fibre polymer composites

    NASA Astrophysics Data System (ADS)

    Kumar, G. B. Veeresh; Pramod, R.

    2017-07-01

    This paper presents the recent work about reinforcing E-glass into Aluminium foil to attain high strength to weight ratio. Aluminium is corrosion resistant, light in weight and ductile, also when alloyed through other metals deliver the greater strengths as desirable for high-tech applications. The density of pure Aluminium is 2.7 g cm3. Electrical grade glass formally known as E-glass, is by far the most used fiber in reinforced plastic composites. It is a high strength material with light weight compared to steel and corrosive resistant. The matrix and reinforcement is bonded with a resin, named Araldite Ly556, which has density at 25 °C, 1.15-1.20 g cm3. Thus gives a good binding structure. In the present work, Aluminium, E-Glass and Epoxy are combined to fabricate a laminate by Hand-Lay process. Hand-lay is the oldest and simplest method used for producing reinforced plastic laminates. The fabricated metal matrix composites are tested for their mechanical properties. The metal laminate is found to render high strength, hardness, flexural strength and increased wear resistance. Further theoretical simulations was carried out to validate the experimental results.

  20. Process of Making Boron-Fiber Reinforced Composite Tape

    NASA Technical Reports Server (NTRS)

    Belvin, Harry L. (Inventor); Cano, Roberto J. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    2002-01-01

    The invention is an apparatus and method for producing a hybrid boron reinforced polymer matrix composition from powder pre-impregnated fiber tow bundles and a linear array of boron fibers. The boron fibers are applied onto the powder pre-impregnated fiber tow bundles and then are processed within a processing component having an impregnation bar assembly. After passing through variable-dimension forming nip-rollers, the powder pre-impregnated fiber tow bundles with the boron fibers become a hybrid boron reinforced polymer matrix composite tape. A driving mechanism pulls the powder pre-impregnated fiber tow bundles with boron fibers through the processing line of the apparatus and a take-up spool collects the formed hybrid boron-fiber reinforced polymer matrix composite tape.

  1. Thermal shock behavior of fiber-reinforced composites

    SciTech Connect

    Wang, H.; Singh, R.N.; Beecher, S.C.; Dinwiddie, R.B.

    1995-02-01

    The thermal shock behavior of three types of continuous fiber-reinforced ceramic composites (Nextel{trademark} or Nicalon{trademark} fiber-reinforced chemical vapor infiltrated or polymer-derived SiC matrix composites) was studied using the water quench technique. The thermal shock induced damage was characterized by both destructive and nondestructive techniques. As compared with monolithic ceramics, the continuous fiber-reinforced ceramic composites were capable of preventing catastrophic failure caused by thermal shock and were able to retain a significant portion of their original strength at {Delta}{Tau} = 1000{degrees}C. The nondestructive techniques involved measuring the thermal diffusivity by the flash technique and determining the Young`s modulus by the dynamic resonance method. It has been demonstrated that these nondestructive techniques can detect damage induced by thermal shock and are more sensitive in detecting damage in the early stage than the conventional destructive technique of measuring the retained strength.

  2. Process of Making Boron-Fiber Reinforced Composite Tape

    NASA Technical Reports Server (NTRS)

    Belvin, Harry L. (Inventor); Cano, Roberto J. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    2002-01-01

    The invention is an apparatus and method for producing a hybrid boron reinforced polymer matrix composition from powder pre-impregnated fiber tow bundles and a linear array of boron fibers. The boron fibers are applied onto the powder pre-impregnated fiber tow bundles and then are processed within a processing component having an impregnation bar assembly. After passing through variable-dimension forming nip-rollers, the powder pre-impregnated fiber tow bundles with the boron fibers become a hybrid boron reinforced polymer matrix composite tape. A driving mechanism pulls the powder pre-impregnated fiber tow bundles with boron fibers through the processing line of the apparatus and a take-up spool collects the formed hybrid boron-fiber reinforced polymer matrix composite tape.

  3. Wet-Lay Process - A Novel Approach to Scalable Fabrication of Tissue Scaffolds and Reinforcement Membranes

    NASA Astrophysics Data System (ADS)

    Wood, Andrew

    Fibrous materials received a great deal of interest in the fields of tissue engineering and regenerative medicine due to the beneficial cell-interactions and tunable properties for various biomedical applications. These materials are highly advantageous as they provide a large surface area for cellular attachment, proliferation, high porosity values for cellular in-growth, and the ability to modify the membrane to achieve desired responses to both mechanical loading as well as environmental stimuli. A prominent method currently used to fabricate such membranes is electrospinning which uses electrostatic forces to produce fibers on the range of nanometers giving them high morphological saliency to the native extra cellular matrix (ECM). These fibers are also advantageous mechanically with strength and flexibility due to their larger aspect ratio when compared to larger diameter micro/macro fibers. While this spinning technique has many advantages and has seen the most quantity of research in recent years, it does have its own set of drawbacks. Among them is the use cytotoxic solvents during processing which must be fully removed before implantation. In addition, since the fiber produced have smaller diameters, the resulting average pore-size of the scaffold is decreased which in turn hinders cellular penetration into the bulk scaffold. In this work, we have proposed and characterized a novel method called wet-lay process for the rapid fabrication of fibrous membranes for tissue scaffolds. Wet-laying is a method common to textiles and paper industry but unexplored for tissue scaffolds. Short fibers are first suspended in an aqueous bath and homogeneously dispersed using shear force. After draining away the aqueous solution, a nonwoven fibro-porous membrane is deposited onto the draining screen. The implementation of wet-laid membranes into weak hydrogel matrices has shown a reinforcement effect for the composite. Further analyses were carried out to determine the

  4. Freeform extrusion fabrication of titanium fiber reinforced 13-93 bioactive glass scaffolds.

    PubMed

    Thomas, Albin; Kolan, Krishna C R; Leu, Ming C; Hilmas, Gregory E

    2017-05-01

    Although implants made with bioactive glass have shown promising results for bone repair, their application in repairing load-bearing long bone is limited due to their poor mechanical properties in comparison to human bone. This work investigates the freeform extrusion fabrication of bioactive silicate 13-93 glass scaffolds reinforced with titanium (Ti) fibers. A composite paste prepared with 13-93 glass and Ti fibers (~16µm in diameter and lengths varying from ~200µm to ~2 mm) was extruded through a nozzle to fabricate scaffolds (0-90° filament orientation pattern) on a heated plate. The sintered scaffolds measured pore sizes ranging from 400 to 800µm and a porosity of ~50%. Scaffolds with 0.4vol% Ti fibers measured fracture toughness of ~0.8MPam(1/2) and a flexural strength of ~15MPa. 13-93 glass scaffolds without Ti fibers had a toughness of ~0.5MPam(1/2) and a strength of ~10MPa. The addition of Ti fibers increased the fracture toughness of the scaffolds by ~70% and flexural strength by ~40%. The scaffolds' biocompatibility and their degradation in mechanical properties in vitro were assessed by immersing the scaffolds in a simulated body fluid over a period of one to four weeks.

  5. Fabrication of Flexible Piezoelectric PZT/Fabric Composite

    PubMed Central

    Chen, Caifeng; Hong, Daiwei; Wang, Andong; Ni, Chaoying

    2013-01-01

    Flexible piezoelectric PZT/fabric composite material is pliable and tough in nature which is in a lack of traditional PZT patches. It has great application prospect in improving the sensitivity of sensor/actuator made by piezoelectric materials especially when they are used for curved surfaces or complicated conditions. In this paper, glass fiber cloth was adopted as carrier to grow PZT piezoelectric crystal particles by hydrothermal method, and the optimum conditions were studied. The results showed that the soft glass fiber cloth was an ideal kind of carrier. A large number of cubic-shaped PZT nanocrystallines grew firmly in the carrier with a dense and uniform distribution. The best hydrothermal condition was found to be pH 13, reaction time 24 h, and reaction temperature 200°C. PMID:24348194

  6. Effects of short glass fibers on the mechanical properties of glass fiber fabric/PVC composites

    NASA Astrophysics Data System (ADS)

    Park, Su Bin; Lee, Joon Seok; Kim, Jong Won

    2017-03-01

    Fiber-reinforced composites using glass fiber and polyvinylchloride (PVC) have been used widely as architectural materials, electrical applications, automotive sector, and packing materials because of their reasonable price, chemical resistance, and dimensional stability. On the other hand, most of the composites are short fiber-reinforced PVC composites. In particular, in the case of fabric reinforced composites, undulated regions exist where there is only resin due to the characteristics of the weave construction, which causes a decrease in strength. In this paper, PVC was reinforced with chopped glass fibers with different lengths and contents to produce glass fiber fabric/PVC composites. The physical properties of the composites, such as thickness, density, volume fraction (V f), and void content (V c) were identified. The mechanical properties, including tensile strength, flexural strength, and interlaminar shear strength (ILSS) were also identified. A cross section of the composites was observed by scanning electron microscopy. Compared to the fabric reinforced composite without chopped glass fiber, the tensile strength was increased by 3.90% (from 316.15 MPa to 328.48 MPa at 5 wt.% chopped fibers with 3 mm length), flexural strength was increased by 7.15% (from 87.07 MPa to 93.30 MPa at 10 wt.% chopped fibers with 2 mm length), and ILSS was increased by 8.71% (from 7.34 MPa to 7.98 MPa at 10 wt.% chopped fibers with 1 mm length). Therefore, the critical fiber aspect ratio of chopped fiber works differently on each of the three mechanical properties.

  7. Manufacturing of SiCp Reinforced Magnesium Composite Tubes by Hot Extrusion Processes

    NASA Astrophysics Data System (ADS)

    Hwang, Yeong-Maw; Huang, Song-Jeng; Huang, Yu-San

    2011-05-01

    Magnesium alloys have higher specific strength compared with other metals, such as aluminum, copper and steel. Nevertheless, their ductility is still not good for further metal forming and their strength is not large enough for real structure applications. The aim of this paper is to develop magnesium alloy composite tubes reinforced with SiC particulates by the stir-casting method and hot extrusion processes. At first, AZ61/SiCp composite ingots reinforced with 5 wt% SiC particulates are fabricated by the melt-stirring technique. Then, finite element simulations are conducted to analyze the plastic flow of magnesium alloy AZ61 within the die and the temperature distribution of the products. AZ61/SiCp composite tubes are manufactured by hot extrusion using a specially designed die-set for obtaining uniform thickness distribution tubes. Finally, the mechanical properties of the reinforced AZ61/SiCp composite and Mg alloy AZ61 tubes are compared with those of the billets to manifest the advantages of extrusion processes and reinforcement of SiC particulates. The microstructures of the billet and extruded tubes are also observed. Through the improvement of the strength of the tube product, its life cycle can be extended and the energy consumption can be reduced, and eventually the environmental sustainability is achieved.

  8. Manufacturing of SiCp Reinforced Magnesium Composite Tubes by Hot Extrusion Processes

    SciTech Connect

    Hwang, Yeong-Maw; Huang, Song-Jeng; Huang, Yu-San

    2011-05-04

    Magnesium alloys have higher specific strength compared with other metals, such as aluminum, copper and steel. Nevertheless, their ductility is still not good for further metal forming and their strength is not large enough for real structure applications. The aim of this paper is to develop magnesium alloy composite tubes reinforced with SiC particulates by the stir-casting method and hot extrusion processes. At first, AZ61/SiCp composite ingots reinforced with 5 wt% SiC particulates are fabricated by the melt-stirring technique. Then, finite element simulations are conducted to analyze the plastic flow of magnesium alloy AZ61 within the die and the temperature distribution of the products. AZ61/SiCp composite tubes are manufactured by hot extrusion using a specially designed die-set for obtaining uniform thickness distribution tubes. Finally, the mechanical properties of the reinforced AZ61/SiCp composite and Mg alloy AZ61 tubes are compared with those of the billets to manifest the advantages of extrusion processes and reinforcement of SiC particulates. The microstructures of the billet and extruded tubes are also observed. Through the improvement of the strength of the tube product, its life cycle can be extended and the energy consumption can be reduced, and eventually the environmental sustainability is achieved.

  9. Novel layer-by-layer procedure for making nylon-6 nanofiber reinforced high strength, tough, and transparent thermoplastic polyurethane composites.

    PubMed

    Jiang, Shaohua; Duan, Gaigai; Hou, Haoqing; Greiner, Andreas; Agarwal, Seema

    2012-08-01

    We highlight a novel composite fabrication method based on solution casting, electrospinning, and film stacking for preparing highly transparent nylon-6 nanofiber reinforced thermoplastic polyurethane (TPU) composite films. The procedure is simple and can be extended to the other thermoplastics. The morphology of fiber/matrix interface and the properties of composite films were also investigated. The method led to a significant reinforcement in mechanical properties of TPU like tensile strength, E modulus, strain, and toughness just using very small amounts of nylon fibers (about 0.4-1.7 wt %; 150-300 nm diameter). The enhanced mechanical properties were achieved without sacrificing optical properties like transparency of TPU.

  10. Hypervelocity Impact Experiments on Epoxy/Ultra-High Molecular Weight Polyethylene Composite Panels Reinforced with Nanotubes

    NASA Technical Reports Server (NTRS)

    Khatiwada, Suman; Laughman, Jay W.; Armada, Carlos A.; Christiansen, Eric L.; Barrera, Enrique V.

    2012-01-01

    Advanced composites with multi-functional capabilities are of great interest to the designers of aerospace structures. Polymer matrix composites (PMCs) reinforced with high strength fibers provide a lightweight and high strength alternative to metals and metal alloys conventionally used in aerospace architectures. Novel reinforcements such as nanofillers offer potential to improve the mechanical properties and add multi-functionality such as radiation resistance and sensing capabilities to the PMCs. This paper reports the hypervelocity impact (HVI) test results on ultra-high molecular weight polyethylene (UHMWPE) fiber composites reinforced with single-walled carbon nanotubes (SWCNT) and boron nitride nanotubes (BNNT). Woven UHMWPE fabrics, in addition to providing excellent impact properties and high strength, also offer radiation resistance due to inherent high hydrogen content. SWCNT have exceptional mechanical and electrical properties. BNNT (figure 1) have high neutron cross section and good mechanical properties that add multi-functionality to this system. In this project, epoxy based UHMWPE composites containing SWCNT and BNNT are assessed for their use as bumper shields and as intermediate plates in a Whipple Shield for HVI resistance. Three composite systems are prepared to compare against one another: (I) Epoxy/UHMWPE, (II) Epoxy/UHMWPE/SWCNT and (III) Epoxy/UHMWPE/SWCNT/BNNT. Each composite is a 10.0 by 10.0 by 0.11 cm3 panel, consisting of 4 layers of fabrics arranged in cross-ply orientation. Both SWCNT and BNNT are 0.5 weight % of the fabric preform. Hypervelocity impact tests are performed using a two-stage light gas gun at Rice University

  11. Failure behavior of a glass-fiber reinforced thermoplastic composite

    NASA Astrophysics Data System (ADS)

    Liang, Jiaai; Kalyanasundaram, Shankar

    2017-05-01

    In this work, experiments were conducted to stamp form glass-fiber reinforced thermoplastics with different widths of hour-glass shapes. A forming limit diagram (FLD) is established based on the experimental data for this material, depicting strain forming limits at different deformation modes. The material system involved in the study is a glass-fiber reinforced polypropylene composite (TWINTEX®) with a fiber orientation of 0°/90° along the warp and weft directions. In this study, the conventional FLD method is adapted to use on thermoplastic composites and it is found that the major principle strain limit is the highest when the strain ratio is around -0.5.

  12. Evaluation of carbon fiber composites fabricated using ionic liquid based epoxies for cryogenic fluid applications

    NASA Astrophysics Data System (ADS)

    Grugel, R. N.; Hastings, W. C.; Rabenberg, E.; Kaukler, W. F.; Henry, C.

    Utilizing tanks fabricated from fiber reinforced polymeric composites for storing cryogenic fluids such as liquid oxygen and liquid hydrogen is of great interest to NASA as considerable weight savings can be gained. Unfortunately such composites, especially at cryogenic temperatures, develop a mismatch that initiates detrimental delamination and crack growth, which promotes leaking. On-going work with ionic liquid-based epoxies appears promising in mitigating these detrimental effects. Some recent results are presented and discussed.

  13. Tungsten fiber reinforced superalloy composite high temperature component design considerations

    NASA Technical Reports Server (NTRS)

    Winsa, E. A.

    1982-01-01

    Tungsten fiber reinforced superalloy composites (TFRS) are intended for use in high temperature turbine components. Current turbine component design methodology is based on applying the experience, sometimes semiempirical, gained from over 30 years of superalloy component design. Current composite component design capability is generally limited to the methodology for low temperature resin matrix composites. Often the tendency is to treat TFRS as just another superalloy or low temperature composite. However, TFRS behavior is significantly different than that of superalloys, and the high environment adds consideration not common in low temperature composite component design. The methodology used for preliminary design of TFRS components are described. Considerations unique to TFRS are emphasized.

  14. Recycling of asbestos tailings used as reinforcing fillers in polypropylene based composites.

    PubMed

    Zhai, Wensi; Wang, Yao; Deng, Yuan; Gao, Hongli; Lin, Zhen; Li, Mao

    2014-04-15

    In this work, asbestos tailings were recycled and used as reinforcing fillers to enhance the mechanical properties of polypropylene (PP). A silane coupling agent was used to chemically modify the asbestos tailings to increase the compatibility between asbestos tailings and polypropylene matrix. Both raw and chemically treated asbestos tailings with different loading levels (from 3 to 30 wt%) were utilized to fabricate composites. Mechanical properties of these composites have been investigated by dynamic mechanical analysis, tensile test and notched impact test. Results showed that hybridization of asbestos tailings in the composites enhanced the mechanical properties of neat PP evidently, and treated asbestos tailings/PP composites yielded even better mechanical properties compared with those of raw asbestos tailings/PP composites. This recycling method of asbestos tailings not only reduces disposal costs and avoids secondary pollution but also produces a new PP-based composite material with enhanced mechanical properties. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. 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.

  16. Unified micromechanics of damping for unidirectional fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Saravanos, D. A.; Chamis, C. C.

    1989-01-01

    An integrated micromechanics methodology for the prediction of damping capacity in fiber-reinforced polymer matrix unidirectional composites has been developed. Explicit micromechanics equations based on hysteretic damping are presented relating the on-axis damping capacities to the fiber and matrix properties and volume fraction. The damping capacities of unidirectional composites subjected to off-axis loading are synthesized from thermal effect on the damping performance of unidirectional composites due to temperature and moisture variations is also modeled. The damping contributions from interfacial friction between broken fibers and matrix are incorporated. Finally, the temperature rise in continuously vibrating composite plies is estimated. Application examples illustrate the significance of various parameters on the damping performance of unidirectional and off-axis fiber reinforced composites.

  17. Effect of Particle Size on Wear of Particulate Reinforced Aluminum Alloy Composites at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Kumar, Suresh; Pandey, Ratandeep; Panwar, Ranvir Singh; Pandey, O. P.

    2013-11-01

    The present paper describes the effect of particle size on operative wear mechanism in particle reinforced aluminum alloy composites at elevated temperatures. Two composites containing zircon sand particles of 20-32 μm and 106-125 μm were fabricated by stir casting process. The dry sliding wear tests of the developed composites were performed at low and high loads with variation in temperatures from 50 to 300 °C. The transition in wear mode from mild-to-severe was observed with variation in temperature and load. The wear at 200 °C presented entirely different wear behavior from the one at 250 °C. The wear rate of fine size reinforced composite at 200 °C at higher load was substantially lower than that of coarse size reinforced composite. Examination of wear tracks and debris revealed that delamination occurs after run in wear mode followed by formation of smaller size wear debris, transfer of materials from the counter surfaces and mixing of these materials on the contact surfaces. The volume loss was observed to increase with increase in load and temperature. Composite containing bigger size particles exhibit higher loss under similar conditions.

  18. Effect of reinforcement type and porosity on strength of metal matrix composite

    NASA Astrophysics Data System (ADS)

    Kulkarni, S. G.; Lal, Achchhe; Menghani, J. V.

    2016-05-01

    In the present work, experimental investigation and the numerical analysis are carried out for strength analysis of A356 alloy matrix composites reinforced with alumina, fly ash and hybrid particle composites. The combined strengthening effect of load bearing, Hall-Petch, Orowan, coefficient of thermal expansion mismatch and elastic modulus mismatch is studied for predicting accurate uniaxial stress-strain behavior of A356 based alloy matrix composite. The unit cell micromechanical approach and nine noded isoparametric finite element analysis (FEA) is used to investigate the yield failure load by considering material defect of porosity as fabrication errors in particulate composite. The Ramberg-Osgood approach is considered for the linear and nonlinear relationship between stress and strain of A356 based metal matrix composites containing different amounts of fly ash and alumina reinforcing particles. A numerical analysis of material porosity on the stress strain behavior of the composite is performed. The literature and experimental results exhibit the validity of this model and confirm the importance of the fly ash as the cheapest and low density reinforcement obtained as a waste by product in thermal power plants.

  19. Rapid fabrication of ceramic composite tubes using chemical vapor infiltration

    SciTech Connect

    Starr, T.L.; Chiang, D.; Besmann, T.M.; Stinton, D.P.; McLaughlin, J.C.; Matlin, W.M.

    1996-06-01

    Ceramic composite tubes can be fabricated with silicon carbide matrix and Nicalon fiber reinforcement using forced flow-thermal gradient chemical vapor infiltration (FCVI). The process model GTCVI is used to design the equipment configuration and to identify conditions for rapid, uniform densification. The initial injector and mandrel design produced radial and longitudinal temperature gradients too large for uniform densification. Improved designs have been evaluated with the model. The most favorable approach utilizes a free-standing preform and an insulated water-cooled gas injector. Selected process conditions are based on the temperature limit of the fiber, matrix stoichiometry and reagent utilization efficiency. Model runs for a tube 12 inches long, 4 inches OD and 1/4 inch wall thickness show uniform densification in approximately 15 hours.

  20. Method of fabricating composite superconducting wire

    DOEpatents

    Strauss, Bruce P.; Reardon, Paul J.; Remsbottom, Robert H.

    1977-01-01

    An improvement in the method for preparing composite rods of superconducting alloy and normal metal from which multifilament composite superconducting wire is fabricated by bending longitudinally a strip of normal metal around a rod of superconductor alloy and welding the edges to form the composite rod. After the rods have preferably been provided with a hexagonal cross-sectional shape, a plurality of the rods are stacked into a normal metal extrusion can, sealed and worked to reduce the cross-sectional size and form multifilament wire. Diffusion barriers and high-electrical resistance barriers can easily be introduced into the wire by plating or otherwise coating the faces of the normal metal strip with appropriate materials.

  1. Effects of Fiber Reinforcement on Clay Aerogel Composites.

    PubMed

    Finlay, Katherine A; Gawryla, Matthew D; Schiraldi, David A

    2015-08-21

    Novel, low density structures which combine biologically-based fibers with clay aerogels are produced in an environmentally benign manner using water as solvent, and no additional processing chemicals. Three different reinforcing fibers, silk, soy silk, and hemp, are evaluated in combination with poly(vinyl alcohol) matrix polymer combined with montmorillonite clay. The mechanical properties of the aerogels are demonstrated to increase with reinforcing fiber length, in each case limited by a critical fiber length, beyond which mechanical properties decline due to maldistribution of filler, and disruption of the aerogel structure. Rather than the classical model for reinforced composite properties, the chemical compatibility of reinforcing fibers with the polymer/clay matrix dominated mechanical performance, along with the tendencies of the fibers to kink under compression.

  2. Effects of Fiber Reinforcement on Clay Aerogel Composites

    PubMed Central

    Finlay, Katherine A.; Gawryla, Matthew D.; Schiraldi, David A.

    2015-01-01

    Novel, low density structures which combine biologically-based fibers with clay aerogels are produced in an environmentally benign manner using water as solvent, and no additional processing chemicals. Three different reinforcing fibers, silk, soy silk, and hemp, are evaluated in combination with poly(vinyl alcohol) matrix polymer combined with montmorillonite clay. The mechanical properties of the aerogels are demonstrated to increase with reinforcing fiber length, in each case limited by a critical fiber length, beyond which mechanical properties decline due to maldistribution of filler, and disruption of the aerogel structure. Rather than the classical model for reinforced composite properties, the chemical compatibility of reinforcing fibers with the polymer/clay matrix dominated mechanical performance, along with the tendencies of the fibers to kink under compression. PMID:28793515

  3. Thermal expansion of multiwall carbon nanotube reinforced nanocrystalline silver matrix composite

    SciTech Connect

    Sharma, Manjula Sharma, Vimal; Pal, Hemant

    2014-04-24

    Multiwall carbon nanotube reinforced silver matrix composite was fabricated by novel molecular level mixing method, which involves nucleation of Ag ions inside carbon nanotube dispersion at the molecular level. As a result the carbon nanotubes get embedded within the powder rather than on the surfaces. Micro structural characterization by X- ray diffraction and scanning electron microscopy reveals that the nanotubes are homogeneously dispersed and anchored within the matrix. The thermal expansion of the composite with the multiwall nanotube content (0, 1.5 vol%) were investigated and it is found that coefficient of thermal expansion decreases with the addition of multiwall nanotube content and reduce to about 63% to that of pure Ag.

  4. Studies on the Spatial Homogeneity and Flexural Strength of Several sic Fiber-Reinforced Cvi-Sic Matrix Composites

    NASA Astrophysics Data System (ADS)

    Araki, H.; Noda, T.; Yang, W.; Hu, Q. L.; Suzuki, H.; Kohyama, A.

    2003-06-01

    Several SiC/SiC composites with 2D plain-woven Nicalon-CG, Hi-Nicalon, or Tyranno-SA fiber cloths as the reinforcements were fabricated by chemical vapor infiltration (CVI) process. The as-fabricated composites are 120mm in diameter and 3-4mm in thickness. The flexural properties and fracture behaviors were investigated using three-point bending tests and scanning electron microscope (SEM). About 30 bending tests are conducted for each composite for a statistic study on the effect of the density (and the spatial homogeneity) on the flexural strength. The Hi-Nicalon/SiC composite showed an average fracture strength of 665MPa with Weibull modulus of 7.43. Both the composites reinforced with Nicalon-CG and Tyranno-SA fibers showed lower strength coupled with near brittle failure behaviors.

  5. Short Fiber Reinforced Composite: a New Alternative for Direct Onlay Restorations

    PubMed Central

    Garoushi, Sufyan; Mangoush, Enas; Vallittu, Mangoush; Lassila, Lippo

    2013-01-01

    Objectives: To determine the static load-bearing capacity of direct composite onlay restorations made of novel filling composite resin system which combines short fiber-reinforced composite resin (FC) and conventional particulate filler composite resin (PFC). Methods: Three groups of onlay restorations were fabricated (n = 8/group); Group A: made from conventional particulate filler composite resin (Z250, 3M-ESPE, USA, control), Group B: made from short fiber-reinforced composite resin (EverX posterior, StickTeck Ltd, member of GC group, Turku, Finland) as substructure with 1 mm surface layer of PFC, Group C: made from FC composite resin. The specimens were incrementally polymerized with a hand-light curing unit for 80 s before they were statically loaded with two different sizes (3 & 6 mm) of steel ball until fracture. Failure modes were visually examined. Data were analyzed using ANOVA (p = 0.05). Results: ANOVA revealed that onlay restorations made from FC composite resin had statistically significantly higher load-bearing capacity (1733 N) ( p < 0.05) than the control PFC composite resin (1081 N). Onlays made of FC composite resin with a surface layer of PFC gave force values of 1405 N which was statistically higher than control group ( p < 0.05). No statistically significant difference was found in the load-bearing capacity between groups loaded by different ball sizes Significance: Onlay restorations combining base of short fiber reinforced composite resin as substructure and surface layer of conventional composite resin displayed promising performance in high load bearing areas. PMID:24511331

  6. Fiber-reinforced bioactive and bioabsorbable hybrid composites.

    PubMed

    Huttunen, Mikko; Törmälä, Pertti; Godinho, Pedro; Kellomäki, Minna

    2008-09-01

    Bioabsorbable polymeric bone fracture fixation devices have been developed and used clinically in recent decades to replace metallic implants. An advantage of bioabsorbable polymeric devices is that these materials degrade in the body and the degradation products exit via metabolic routes. Additionally, the strength properties of the bioabsorbable polymeric devices decrease as the device degrades, which promotes bone regeneration (according to Wolff's law) as the remodeling bone tissue is progressively loaded. The most extensively studied bioabsorbable polymers are poly-alpha-hydroxy acids. The major limitation of the first generation of bioabsorbable materials and devices was their relatively low mechanical properties and brittle behavior. Therefore, several reinforcing techniques have been used to improve the mechanical properties. These include polymer chain orientation techniques and the use of fiber reinforcements. The latest innovation for bioactive and fiber-reinforced bioabsorbable composites is to use both bioactive and bioresorbable ceramic and bioabsorbable polymeric fiber reinforcement in the same composite structure. This solution of using bioactive and fiber-reinforced bioabsorbable hybrid composites is examined in this study.

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

    SciTech Connect

    Tingley, D.A.; Eng, P.

    1996-12-31

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

  8. Structural health monitoring of an asymmetrical SMA reinforced composite using embedded FBG sensors

    NASA Astrophysics Data System (ADS)

    Ho, Mei-po; Lau, Kin-tak; Au, Ho-yin; Dong, Yu; Tam, Hwa-yaw

    2013-12-01

    Embedded actuator and sensor technology provides accurate structural health monitoring and proper structural response of a structure in any harsh servicing situation. This paper describes the fabrication of a smart composite by embedding shape memory alloy (SMA) wires and fibre Bragg grating (FBG) sensors into a glass fabric reinforced polymeric composite. Mechanical performances of the composite under martensitic and austenitic stages of the SMA wires were studied, and its natural frequencies were also measured accordingly. The result shows that the shift of the natural frequency arises from temperature change, thus changing the mechanical properties of the SMA wires. The changes of strain, stress, curvature, and damping ratio were predicted from an asymmetrical lamination model. It was found that this model demonstrates certain attractive effects, including mechanical properties, the change of shape, and the natural frequency upon activation of the SMA wires.

  9. Railgun Application for High Energy Impact Testing of Nano-Reinforced Kevlar-Based Composite Materials

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Vricella, A.; Pastore, R.; Morles, R. B.; Marchetti, M.

    2013-08-01

    An advanced electromagnetic accelerator, called railgun, has been assembled and tuned in order to perform high energy impact test on layered structures. Different types of layered composite materials have been manufactured and characterized in terms of energy absorbing capability upon impact of metallic bullets fired at high velocity. The composite materials under testing are manufactured by integrating several layers of Kevlar fabric and carbon fiber ply within a polymeric matrix reinforced by carbon nanotubes at 1% of weight percentage. The experimental results show that the railgun-device is a good candidate to perform impact testing of materials in the space debris energy range, and that carbon nanotubes may enhance, when suitably coupled to the composite's matrix, the excellent antiballistic properties of the Kevlar fabrics.

  10. Poly /Diels-Alder/ matrix resins. [high temperature resistant graphite reinforced composites

    NASA Technical Reports Server (NTRS)

    Jones, R. J.; Orell, M. K.; Sheppard, C. H.; Vaughan, R. W.

    1977-01-01

    A poly (Diels-Alder) (PDA) resin approach was investigated as a means to achieve autoclavability of high-temperature resistant resin/fiber composites under mild fabrication conditions. The results of the study were highly promising and program objectives were achieved. Low-void content Type A-S graphite reinforced composites were autoclave fabricated from a PDA resin/fiber prepreg prepared from an acetone:methanol:dioxane varnish. Autoclave conditions were 400 F and 100 psi for up to two hours duration. After postcure at temperatures up to 600 F, the composites demonstrated high initial mechanical properties at temperatures up to 550 F. The results from isothermal aging studies in air for 1000 hours indicated potential for long-term (over 1000 hours) use at 500 F and shorter-term use at 550 F.

  11. Poly /Diels-Alder/ matrix resins. [high temperature resistant graphite reinforced composites

    NASA Technical Reports Server (NTRS)

    Jones, R. J.; Orell, M. K.; Sheppard, C. H.; Vaughan, R. W.

    1977-01-01

    A poly (Diels-Alder) (PDA) resin approach was investigated as a means to achieve autoclavability of high-temperature resistant resin/fiber composites under mild fabrication conditions. The results of the study were highly promising and program objectives were achieved. Low-void content Type A-S graphite reinforced composites were autoclave fabricated from a PDA resin/fiber prepreg prepared from an acetone:methanol:dioxane varnish. Autoclave conditions were 400 F and 100 psi for up to two hours duration. After postcure at temperatures up to 600 F, the composites demonstrated high initial mechanical properties at temperatures up to 550 F. The results from isothermal aging studies in air for 1000 hours indicated potential for long-term (over 1000 hours) use at 500 F and shorter-term use at 550 F.

  12. How to make auxetic fibre reinforced composites

    NASA Astrophysics Data System (ADS)

    Alderson, K. L.; Simkins, V. R.; Coenen, V. L.; Davies, P. J.; Alderson, A.; Evans, K. E.

    2005-03-01

    Auxetic composite materials can be produced either from conventional components via specially designed configurations or from auxetic components. This paper reviews manufacturing methods for both these scenarios. It then looks at the possibility of property enhancements in both low velocity impact and fibre pull out due to the negative Poisson's ratio. Tests revealed that auxetic carbon fibre composites made from commercially available prepreg show evidence of increased resistance to low velocity impact and static indentation with a smaller area of damage. Also, using auxetic fibres in composite materials is shown to produce a higher resistance to fibre pullout.

  13. NATURAL FIBER OR GLASS REINFORCED POLYPROPYLENE COMPOSITES?

    SciTech Connect

    Lorenzi, W.; Di Landro, L.; Casiraghi, A.; Pagano, M. R.

    2008-08-28

    Problems related to the recycle of conventional composite materials are becoming always more relevant for many industrial fields. Natural fiber composites (NFC) have recently gained much attention due to their low cost, environmental gains (eco-compatibility), easy disposal, reduction in volatile organic emissions, and their potential to compete with glass fiber composites (GFC). Interest in natural fibers is not only based over ecological aspects. NFC have good mechanical performances in relation to their low specific weight and low price. A characterization of mechanical properties, dynamic behavior, and moisture absorption is presented.

  14. Natural Fiber or Glass Reinforced Polypropylene Composites?

    NASA Astrophysics Data System (ADS)

    Lorenzi, W.; Di Landro, L.; Casiraghi, A.; Pagano, M. R.

    2008-08-01

    Problems related to the recycle of conventional composite materials are becoming always more relevant for many industrial fields. Natural fiber composites (NFC) have recently gained much attention due to their low cost, environmental gains (eco-compatibility), easy disposal, reduction in volatile organic emissions, and their potential to compete with glass fiber composites (GFC). Interest in natural fibers is not only based over ecological aspects. NFC have good mechanical performances in relation to their low specific weight and low price. A characterization of mechanical properties, dynamic behavior, and moisture absorption is presented.

  15. Fabrication and characterization of regenerated silk scaffolds reinforced with natural silk fibers for bone tissue engineering.

    PubMed

    Mobini, Sahba; Hoyer, Birgit; Solati-Hashjin, Mehran; Lode, Anja; Nosoudi, Nasim; Samadikuchaksaraei, Ali; Gelinsky, Michael

    2013-08-01

    We introduce a novel Bombyx mori silk-based composite material developed for bone tissue engineering. Three-dimensional scaffolds were fabricated by embedding of natural degummed silk fibers in a matrix of regenerated fibroin, followed by freeze-drying. Different ratios of fibers to fibroin were investigated with respect to their influence on mechanical and biological properties. For all scaffold types, an interconnected porous structure suitable for cell penetration was proven by scanning electron microscopy. Compressive tests, carried out in static and cyclic mode under dry as well as wet conditions, revealed a strong impact of fiber reinforcement on compressive modulus and compressive stress. Cell culture experiments with human mesenchymal stem cells demonstrated that the fiber/fibroin composite scaffolds support cell attachment, proliferation, as well as differentiation along the osteoblastic lineage. Considering the excellent mechanical and biological properties, novel fiber/fibroin scaffolds appear to be an interesting structure for prospect studies in bone tissue engineering. Copyright © 2013 Wiley Periodicals, Inc.

  16. Fiber Reinforced Composites for Insulation and Structures

    NASA Technical Reports Server (NTRS)

    Broughton, Roy M., Jr.

    2005-01-01

    The work involves two areas: Composites, optimum fiber placement with initial construction of a pressure vessel, and the general subject of insulation, a continual concern in harsh thermal environments. Insulation

  17. 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.

  18. Mechanical behaviour of A356 alloy reinforced with high strength alloy particulate metallic composites

    NASA Astrophysics Data System (ADS)

    Krishna Mallarapu, Gopi; Kancharla, Praveen Kumar; Rao, J. B.; Bhargava, N. R. M. R.

    2017-08-01

    In the present investigation, work has been carried out to fabricate composites with high strength and good ductility by maximizing a uniform and smooth interface for effective transfer of load, and minimizing reinforcement cracking, agglomerations, and pull outs. A high-strength alloy (ternary) in particulate (HSA(P)) form was used as reinforcement in 356 aluminium. A 356-HSA(P) composite was prepared using the stir casting technique by dispersing an average particle size of 125 µm for reinforcement with various weight fractions varying between 5% and 15%. Secondary processing was done using the hot extrusion process to obtain 14 mm Ø rods (extrusion ratio of 18:1) and homogenized in an industrial furnace for 24 h. A decrease in reinforcement size was observed with increments in particulate content. The hardness of the composites was improved compared to the existing matrix. Mechanical properties such as UTS, yield strength, modulus of elasticity and ductility reveal superior specific properties than that of the alloy.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  20. Tensile Strength of Epoxy Composites Reinforced with Fique Fibers

    NASA Astrophysics Data System (ADS)

    Altoé, Giulio Rodrigues; Netto, Pedro Amoy; Teles, Maria Carolina Andrade; Borges, Luiz Gustavo Xavier; Margem, Frederico Muylaert; Monteiro, Sergio Neves

    Environmentally friendly composites, made from natural fibers, are among the most investigated and applied today. Natural fibers have showed advantages, such as, flexibility and toughness, if compared with synthetic fibers. This work investigates the tensile strength of epoxy composites reinforced with Fique fibers. The Fique fiber was extracted from Fique leaf presents some significant characteristic, but until now only few studies on Fique fiber were performed. Composites reinforced with up to 30% in volume of long, continuous and aligned Fique fibers were tested in an Instron machine at room temperature. The incorporation of Fique fibers increases the tensile strength of the composite. After fracture the specimens were analyzed by a SEM (scanning electron microscope).

  1. 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.

  2. 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.

  3. Laminated sheet composites reinforced with modular filament sheet

    NASA Technical Reports Server (NTRS)

    Reece, O. Y.

    1968-01-01

    Aluminum and magnesium composite sheet laminates reinforced with low density, high strength modular filament sheets are produced by diffusion bonding and explosive bonding. Both processes are accomplished in normal atmosphere and require no special tooling or cleaning other than wire brushing the metal surfaces just prior to laminating.

  4. Elastic/viscoplastic constitutive model for fiber reinforced thermoplastic composites

    NASA Technical Reports Server (NTRS)

    Gates, T. S.; Sun, C. T.

    1991-01-01

    A constitutive model to describe the elastic/viscoplastic behavior of fiber-reinforced thermoplastic composites under plane stress conditions is presented. Formulations are given for quasi-static plasticity and time-dependent viscoplasticity. Experimental procedures required to generate the necessary material constants are explained, and the experimental data is compared to the predicted behavior.

  5. Guided waves characterization of bamboo fibers reinforced composites

    NASA Astrophysics Data System (ADS)

    Marchi, L. De; Marzani, A.; Perelli, A.; Testoni, N.; Speciale, N.

    2012-05-01

    In the present study, an inverse procedure based on ultrasonic guided wave propagation is proposed for the bamboo fibers reinforced composites characterization. The procedure consists of an optimization problem in which the discrepancy between the experimental dispersion curves and those predicted through a numerical formulation is minimized.

  6. Crushing characteristics of continuous fiber-reinforced composite tubes

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Jones, Robert M.

    1992-01-01

    Composite tubes can be reinforced with continuous fibers. When such tubes are subjected to crushing loads, the response is complex and depends on interaction between the different mechanisms that control the crushing process. The modes of crushing and their controlling mechanisms are described. Also, the resulting crushing process and its efficiency are addressed.

  7. Interfacial contributions in lignocellulosic firber-reinforced polyurethane composites

    Treesearch

    Timothy G. Rials; Michael P. Wolcott; John M. Nassar

    2001-01-01

    Whereas lignocellulosic fibers have received considerable attention as a reinforcing agent in thermoplastic composites, their applicability to reactive polymer systems remains of considerable interest. The hydroxyl-rich nature of natural lignocellulosic fibers suggests that they are particularly useful in thermsetting systems such as polyurethanes. To further this...

  8. 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.

  9. Effect of continuous longitudinal glass fiber reinforcement on the cantilever beam strength of particulate filler composites.

    PubMed

    Kim, Sung-Hun; Christopher Watts, David

    2006-11-01

    The objective of this in vitro study was to investigate the effect of continuous longitudinal glass fibers on the bending properties of particulate filler composite resins. Four particulate filler composite resins (Tetric Ceram, Point 4, Z250, P60) and one continuous longitudinal glass fiber material (everStick) as reinforcement were selected. Three groups of beam specimens (5 x 5 x 25 mm) for each material were fabricated. For group I, specimens were not reinforced with fibers and were tested as the control group. For group II, specimens were reinforced with 2 layers of the fiber (6.5 vol%), and for group III with 3 layers (9.8 vol%). The specimens were stored at 37 degrees C for 30 days. One end of the beam specimen (14 mm) was fixed in a device, while the other (11 mm) was left free. Cantilever beam strength was measured using a universal testing machine, loading at a distance of 10 mm from the upright support through a steel ball of 2 mm diameter. The loads and deflection at initial failure and at final failure for each specimen were recorded. The data were statistically analyzed using one-way ANOVA and the multiple comparison Scheffé test (alpha = 0.05). The bending moments of particulate filler composite at final failure, when reinforced with 3 layers of the glass fibers (272.4-325.2 Ncm), were significantly higher than for the composites without fibers. However, the materials reinforced with 3 layers of fibers were not significantly different from the materials reinforced with 2 layers of fibers (234.1-282.6 Ncm). The materials reinforced with 3 layers of fibers exhibited severe deflection at final failure, ranging from 2.8 mm to 3.4 mm. The bending moments of the particulate composites increased linearly with the weight fraction of the fillers, but there was no linear correlation between them when reinforced with fibers. The cantilever beam strength of the particulate filler composites increased significantly when layers of fibers were added and as the

  10. Fiber reinforced composites in prosthodontics – A systematic review

    PubMed Central

    Nayar, Sanjna; Ganesh, R.; Santhosh, S.

    2015-01-01

    Fiber-reinforced composite (FRC), prostheses offer the potential advantages of optimized esthetics, low wear of the opposing dentition and the ability to bond the prosthesis to the abutment teeth, thereby compensating for less-than-optimal abutment tooth retention and resistance form. These prostheses are composed of two types of composite materials: Fiber-composites to build the substructure and hybrid or micro fill particulate composites to create the external veneer surface. This article reviews the various types of FRCs and its mechanical properties. PMID:26015717

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

    NASA Technical Reports Server (NTRS)

    Dumesnil, C. E.

    1973-01-01

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

  12. Tannin-based flax fibre reinforced composites for structural applications in vehicles

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Abhyankar, H.; Nassiopoulos, E.; Njuguna, J.

    2012-09-01

    Innovation is often driven by changes in government policies regulating the industries, especially true in case of the automotive. Except weight savings, the strict EU regulation of 95% recyclable material-made vehicles drives the manufactures and scientists to seek new 'green materials' for structural applications. With handing at two major drawbacks (production cost and safety), ECHOSHELL is supported by EU to develop and optimise structural solutions for superlight electric vehicles by using bio-composites made of high-performance natural fibres and resins, providing enhanced strength and bio-degradability characteristics. Flax reinforced tannin-based composite is selected as one of the candidates and were firstly investigated with different fabric lay-up angles (non-woven flax mat, UD, [0, 90°]4 and [0, +45°, 90°, -45°]2) through authors' work. Some of the obtained results, such as tensile properties and SEM micrographs were shown in this conference paper. The UD flax reinforced composite exhibits the best tensile performance, with tensile strength and modulus of 150 MPa and 9.6 MPa, respectively. It was observed that during tension the oriented-fabric composites showed some delamination process, which are expected to be eliminated through surface treatment (alkali treatment etc.) and nanotechnology, such as the use of nano-fibrils. Failure mechanism of the tested samples were identified through SEM results, indicating that the combination of fibre pull-out, fibre breakage and brittle resins failure mainly contribute to the fracture failure of composites.

  13. 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.

  14. Doubly curved nanofiber-reinforced optically transparent composites

    NASA Astrophysics Data System (ADS)

    Shams, Md. Iftekhar; Yano, Hiroyuki

    2015-11-01

    Doubly curved nanofiber-reinforced optically transparent composites with low thermal expansion of 15 ppm/k are prepared by hot pressing vacuum-filtered Pickering emulsions of hydrophobic acrylic resin monomer, hydrophilic chitin nanofibers and water. The coalescence of acrylic monomer droplets in the emulsion is prevented by the chitin nanofibers network. This transparent composite has 3D shape moldability, making it attractive for optical precision parts.

  15. Doubly curved nanofiber-reinforced optically transparent composites

    PubMed Central

    Shams, Md. Iftekhar; Yano, Hiroyuki

    2015-01-01

    Doubly curved nanofiber-reinforced optically transparent composites with low thermal expansion of 15 ppm/k are prepared by hot pressing vacuum-filtered Pickering emulsions of hydrophobic acrylic resin monomer, hydrophilic chitin nanofibers and water. The coalescence of acrylic monomer droplets in the emulsion is prevented by the chitin nanofibers network. This transparent composite has 3D shape moldability, making it attractive for optical precision parts. PMID:26552990

  16. Determining Fiber Orientation in Graphite-Reinforced Composites

    NASA Technical Reports Server (NTRS)

    Daniels, J. G.; Ledbetter, Frank E., III; Clemon, J. M.; Penn, B. G.; White, W. T.

    1985-01-01

    Orientation of fibers in graphite-fiber-reinforced plastics easily determined with new method. Materials scientists thus ensure that fibers, usually not visible after graphite/plastic composite has been cured, properly oriented in test specimens and test results accurately represent the characteristics of composite. Method based on fact that continuous graphite fibers embeded in cured polymer matrix actually parallel conductors. Thus, resistance measured across laminate is at minimum when probes of ohmmeter connected to opposite ends of fibers.

  17. Structure-processing-property relationships for polymer interphases in fiber reinforced composite materials

    SciTech Connect

    Drzal, L.T.

    1995-12-31

    When polymer matrix composite materials are fabricated, polymers are processed to surround each reinforcing element while they are fluid and then they solidify in intimate contact with the reinforcement surface. For thermoset matrices, chemisorption of constituents, segregation of components. and processing constraints all can influence the resulting structure of the polymer in its solidified state. For thermoplastic matrices, segregation by molecular weight, morphological changes resulting from crystallization or additive segregation can also control the final matrix structure. In addition the surface of the fibers is coated with chemical agents that can also interact with the polymer. Examples will be given to illustrate the effect of the structure of this polymer interphase on adhesion. It will be shown that in some cases if the resulting polymer structure is known, adhesion and composite properties can be predicted.

  18. Ballistic impact behaviour of woven fabric composite: Finite element analysis and experiments

    NASA Astrophysics Data System (ADS)

    Phadnis, V. A.; Pandya, K. S.; Naik, N. K.; Roy, A.; Silberschmidt, V. V.

    2013-07-01

    A mechanical behaviour of plain-weave E-glass fabric/epoxy laminate composite plate exposed to ballistic impact is studied using a finite-element (FE) code Abaqus/Explicit. A ply-level FE model is developed, where a fabric-reinforced ply is modelled as a homogeneous orthotropic elastic material with potential to sustain progressive stiffness degradation due to fiber/matrix cracking, and plastic deformation under shear loading. The model is implemented as a VUMAT user subroutine. Ballistic experiments were carried out to validate the FE model. A parametric study for varying panel thickness is performed to compare impact resistance of the studied composite.

  19. Investigations on composites reinforced with HEA particles

    NASA Astrophysics Data System (ADS)

    Carcea, I.; Chelariu, R.; Asavei, L.; Cimpoeşu, N.; Florea, R. M.

    2017-08-01

    This work reports the results of investigations on the fortification with high entropy alloys particles of aluminium matrix composite materials. The properties of these materials processed by Vortex techniques primarily depend on the matrix and the volume fraction of the constituent phase. The mechanical properties, toughening mechanisms and potential applications are briefly reviewed. Traditional methods were used for the basic characterization of the composite. The microstructure of the composites were investigated by optical and scanning electron microscopy (OM, SEM). SEM analysis was performed in order to observe the microstructural evolution as a function of the HEA particles content and to identify some reasons of the presence of porosity or any irregularities within the metal matrix.

  20. 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

  1. On Healable Polymers and Fiber-Reinforced Composites

    NASA Astrophysics Data System (ADS)

    Nielsen, Christian Eric

    Polymeric materials capable of healing damage would be valuable in structural applications where access for repair is limited. Approaches to creating such materials are reviewed, with the present work focusing on polymers with thermally reversible covalent cross-links. These special cross-links are Diels-Alder (DA) adducts, which can be separated and re-formed, enabling healing of mechanical damage at the molecular level. Several DA-based polymers, including 2MEP4FS, are mechanically and thermally characterized. The polymerization reaction of 2MEP4FS is modeled and the number of established DA adducts is associated with the glass transition temperature of the polymer. The models are applied to concentric cylinder rotational measurements of 2MEP4FS prepolymer at room and elevated temperatures to describe the viscosity as a function of time, temperature, and conversion. Mechanical damage including cracks and scratches are imparted in cured polymer samples and subsequently healed. Damage due to high temperature thermal degradation is observed to not be reversible. The ability to repair damage without flowing polymer chains makes DA-based healable polymers particularly well-suited for crack healing. The double cleavage drilled compression (DCDC) fracture test is investigated as a useful method of creating and incrementally growing cracks in a sample. The effect of sample geometry on the fracture behavior is experimentally and computationally studied. Computational and empirical models are developed to estimate critical stress intensity factors from DCDC results. Glass and carbon fiber-reinforced composites are fabricated with 2MEP4FS as the matrix material. A prepreg process is developed that uses temperature to control the polymerization rate of the monomers and produce homogeneous prepolymer for integration with a layer of unidirectional fiber. Multiple prepreg layers are laminated to form multi-layered cross-ply healable composites, which are characterized in

  2. The assessment of metal fiber reinforced polymeric composites

    NASA Technical Reports Server (NTRS)

    Chung, Wenchiang R.

    1990-01-01

    Because of their low cost, excellent electrical conductivity, high specific strength (strength/density), and high specific modulus (modulus/density) short metal fiber reinforced composites have enjoyed a widespread use in many critical applications such as automotive industry, aircraft manufacturing, national defense, and space technology. However, little data has been found in the study of short metal fibrous composites. Optimum fiber concentration in a resin matrix and fiber aspect ratio (length-to-diameter ratio) are often not available to a user. Stress concentration at short fiber ends is the other concern when the composite is applied to a load-bearing application. Fracture in such composites where the damage will be initiated or accumulated is usually difficult to be determined. An experimental investigation is therefore carefully designed and undertaken to systematically evaluate the mechanical properties as well as electrical properties. Inconel 601 (nickel based) metal fiber with a diameter of eight microns is used to reinforce commercially available thermoset polyester resin. Mechanical testing such as tensile, impact, and flexure tests along with electrical conductivity measurements is conducted to study the feasibility of using such composites. The advantages and limitations of applying chopped metal fiber reinforced polymeric composites are also discussed.

  3. Friction Stir Processing of Particle Reinforced Composite Materials

    PubMed Central

    Gan, Yong X.; Solomon, Daniel; Reinbolt, Michael

    2010-01-01

    The objective of this article is to provide a review of friction stir processing (FSP) technology and its application for microstructure modification of particle reinforced composite materials. The main focus of FSP was on aluminum based alloys and composites. Recently, many researchers have investigated this technology for treating other alloys and materials including stainless steels, magnesium, titanium, and copper. It is shown that FSP technology is very effective in microstructure modification of reinforced metal matrix composite materials. FSP has also been used in the processing and structure modification of polymeric composite materials. Compared with other manufacturing processes, friction stir processing has the advantage of reducing distortion and defects in materials. The layout of this paper is as follows. The friction stir processing technology will be presented first. Then, the application of this technology in manufacturing and structure modification of particle reinforced composite materials will be introduced. Future application of friction stir processing in energy field, for example, for vanadium alloy and composites will be discussed. Finally, the challenges for improving friction stir processing technology will be mentioned.

  4. New generation fiber reinforced polymer composites incorporating carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Soliman, Eslam

    The last five decades observed an increasing use of fiber reinforced polymer (FRP) composites as alternative construction materials for aerospace and infrastructure. The high specific strength of FRP attracted its use as non-corrosive reinforcement. However, FRP materials were characterized with a relatively low ductility and low shear strength compared with steel reinforcement. On the other hand, carbon nanotubes (CNTs) have been introduced in the last decade as a material with minimal defect that is capable of increasing the mechanical properties of polymer matrices. This dissertation reports experimental investigations on the use of multi-walled carbon nanotubes (MWCNTs) to produce a new generation of FRP composites. The experiments showed significant improvements in the flexure properties of the nanocomposite when functionalized MWCNTs were used. In addition, MWCNTs were used to produce FRP composites in order to examine static, dynamic, and creep behavior. The MWCNTs improved the off-axis tension, off-axis flexure, FRP lap shear joint responses. In addition, they reduced the creep of FRP-concrete interface, enhanced the fracture toughness, and altered the impact resistance significantly. In general, the MWCNTs are found to affect the behaviour of the FRP composites when matrix failure dominates the behaviour. The improvement in the mechanical response with the addition of low contents of MWCNTs would benefit many industrial and military applications such as strengthening structures using FRP composites, composite pipelines, aircrafts, and armoured vehicles.

  5. Ageing characteristics of aluminium alloy aluminosilicate discontinuous fiber reinforced composites

    SciTech Connect

    Nath, D.; Singh, V.

    1999-03-05

    Development of continuous fiber reinforced metal matrix composites is aimed at providing high specific strength and stiffness needed for aerospace and some critical high temperature structural applications. Considerable efforts have been made, during the last decade, to improve the strength of age-hardening aluminium alloy matrix composites by suitable heat treatment. It has also been well established that age-hardenable aluminium alloy composites show accelerated ageing behavior because of enhanced dislocation density at the fiber/matrix interface resulting from thermal expansion mismatch between ceramic fiber and the metal matrix. The accelerated ageing of aluminium alloy composites either from dislocation density or the residual stress, as a result of thermal expansion mismatch is dependent on the size of whisker and particulate. Investigations have also been made on the effect of volume fraction of particulate on the ageing behavior of aluminium alloys. The present investigation is concerned with characterization of age-hardening behavior of an Al-Si-Cu-Mg(AA 336) alloy alumino-silicate discontinuous fiber-reinforced composites (referred to as aluminium MMCs in the present text) being developed for automotive pistons. An effort is made to study the effect of volume fraction of the reinforcement on age-hardening behavior of this composite.

  6. Fracture toughness of woven kenaf fibre reinforced composites

    NASA Astrophysics Data System (ADS)

    Ismail, AE; Masran, SH; Jamian, S.; Kamarudin, KA; Mohd Nor, MK; Muhd Nor, NH; Mohd Tobi, AL; Awang, MK

    2016-11-01

    This paper presents the role of fibre orientations on the woven-type kenaf fibre reinforced composites. According to literature survey, lack of information regarding to the fracture toughness of woven kenaf fibre reinforced composites. Fracture toughness tests were performed using ASTM D5045. Four fibre orientations were used such as 0/15/0/-15/0, 0/30/0/-30/0, 0/45/0/-45/0 and 0/90/0/-90/0 and on the other hand virgin polyester and unidirectional fibre reinforced composites were also used for comparisons. Based on the experimental works, woven-typed composites produced lower fracture toughness compared with the unidirectional fiber composite. Fracture toughness obtained from different fibre orientations composites are almost identical however 0/30/0/-30/0 and 0/90/0/-90/0 produced higher toughness relative with others. Fracture mechanisms revealed that as expected the fibres aligned along the stress direction capable to sustain better mechanical deformation and therefore producing higher fracture toughness.

  7. Superior Mechanical Properties of Epoxy Composites Reinforced by 3D Interconnected Graphene Skeleton.

    PubMed

    Ni, Ya; Chen, Lei; Teng, Kunyue; Shi, Jie; Qian, Xiaoming; Xu, Zhiwei; Tian, Xu; Hu, Chuansheng; Ma, Meijun

    2015-06-03

    Epoxy-based composites reinforced by three-dimensional graphene skeleton (3DGS) were fabricated in resin transfer molding method with respect to the difficulty in good dispersion and arrangement of graphene sheets in composites by directly mixing graphene and epoxy. 3DGS was synthesized in the process of self-assembly and reduction with poly(amidoamine) dendrimers. In the formation of 3DGS, graphene sheets were in good dispersion and ordered state, which resulted in exceptional mechanical properties and thermal stability for epoxy composites. For 3DGS/epoxy composites, the tensile and compressive strengths significantly increased by 120.9% and 148.3%, respectively, as well as the glass transition temperature, which increased by a notable 19 °C, unlike the thermal exfoliation graphene/epoxy composites via direct-mixing route, which increased by only 0.20 wt % content of fillers. Relative to the graphene/epoxy composites in direct-mixing method mentioned in literature, the increase in tensile and compressive strengths of 3DGS/epoxy composites was at least twofold and sevenfold, respectively. It can be expected that 3DGS, which comes from preforming graphene sheets orderly and dispersedly, would replace graphene nanosheets in polymer nanocomposite reinforcement and endow composites with unique structure and some unexpected performance.

  8. Thermoforming continuous fiber-reinforced thermoplastic composites

    SciTech Connect

    Wu, Xiang.

    1990-01-01

    In this research the forming process was first decomposed into basic deformation elements with simple geometries, and models were then developed for these elements. A series-parallel model was developed for predicting the upper and lower bounds of composite shear modulus at forming temperature based on the fiber content, fiber distribution, and matrix shear modulus. A shear-flexure model was proposed to describe the initial load-deflection behavior of thermoplastic composites in bending. A ply buckling model was developed which included the contributions from both a surface tension term and a ply buckling term.

  9. Laser Processed TiN Reinforced Ti6Al4V Composite Coatings

    PubMed Central

    Balla, Vamsi Krishna; Bhat, Abhimanyu; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    The purpose of this first generation investigation is to evaluate fabrication, in vitro cytotoxicity, cell-materials interactions and tribological performance of TiN particle reinforced Ti6Al4V composite coatings for potential wear resistant load bearing implant applications. The microstructural analysis of the composites was performed using scanning electron microscope and phase analysis was done with X-ray diffraction. In vitro cell-materials interactions, using human fetal osteoblast cell line, have been assessed on these composite coatings and compared with Ti6Al4V alloy control samples. The tribological performance of the coatings were evaluated, in simulated body fluids, up to 1000 m sliding distance under 10N normal load. The results show that the composite coatings contain distinct TiN particles embedded in α + β phase matrix. The average top surface hardness of Ti6Al4V alloy increased from 394 ± 8 HV to 1138 ± 61 HV with 40 wt.% TiN reinforcement. Among the composite coatings, the coatings reinforced with 40 wt. % TiN exhibited the highest wear resistance of 3.74 × 10-6 mm3/Nm, which is lower than the wear rate, 1.04 × 10-5 mm3/Nm, of laser processed CoCrMo alloy tested under identical experimental conditions. In vitro biocompatibility study showed that these composite coatings were non-toxic and provides superior cell-material interactions compared to Ti6Al4V control, as a result of their high surface energy. In summary, excellent in vitro wear resistance and biocompatibility of present laser processed TiN reinforced Ti6Al4V alloy composite coatings clearly show their potential as wear resistant contact surfaces for load bearing implant applications. PMID:22301169

  10. Processing and microstructure of silicon carbide fiber-reinforced silicon carbide composite by hot-pressing

    NASA Astrophysics Data System (ADS)

    Yoshida, Katsumi; Budiyanto; Imai, Masamitsu; Yano, Toyohiko

    1998-10-01

    Continuous 2D woven fiber-reinforced SiC composites were fabricated by hot-pressing in Ar at 1750°C under a pressure of 40 MPa using Al-B-C or Al 2O 3-Y 2O 3-CaO system as sintering additives. In this study, fracture behavior and microstructure of the composites fabricated by this process were investigated. These composites achieved nearly full density in both cases. In the case of the composite with Al-B-C additives, the load-displacement behavior of the composite with non-coated Hi-Nicalon cloths showed completely brittle fracture, whereas that of the composite with BN-coated Hi-Nicalon cloths showed ductile fracture with a lot of fiber pull-out. On the contrary, in the case of the composite with Al 2O 3-Y 2O 3-CaO additives, the load-displacement behavior of the composite with non-coated Hi-Nicalon cloths showed slight ductile fracture with small tails, whereas that of the composite with BN-coated Hi-Nicalon cloths showed completely brittle fracture.

  11. Composite material fabrication techniques. CRADA final report

    SciTech Connect

    Frame, B J; Paulauskas, F L; Miller, J; Parzych, W

    1996-09-30

    This report describes a low cost method of fabricating components for mockups and training simulators used in the transportation industry. This technology was developed jointly by the Oak Ridge National Laboratory (ORNL) and Metters Industries, Incorporated (MI) as part of a Cooperative Research and Development Agreement (CRADA) ORNL94-0288 sponsored by the Department of Energy (DOE) Office of Economic Impace and Diversity Minority Business Technology Transfer Consortium. The technology involves fabricating component replicas from fiberglass/epoxy composites using a resin transfer molding (RTM) process. The original components are used as masters to fabricate the molds. The molding process yields parts that duplicate the significant dimensional requirements of the original component while still parts that duplicate the significant dimensional requirements of the original component while still providing adequate strength and stiffness for use in training simulators. This technology permits MI to overcome an acute shortage in surplus military hardware available to them for use in manufacturing training simulators. In addition, the cost of the molded fiberglass components is expected to be less than that of procuring the original components from the military.

  12. CODIFICATION OF FIBER REINFORCED COMPOSITE PIPING

    SciTech Connect

    Rawls, G.

    2012-10-10

    The goal of the overall project is to successfully adapt spoolable FRP currently used in the oil industry for use in hydrogen pipelines. The use of FRP materials for hydrogen service will rely on the demonstrated compatibility of these materials for pipeline service environments and operating conditions. The ability of the polymer piping to withstand degradation while in service, and development of the tools and data required for life management are imperative for successful implementation of these materials for hydrogen pipeline. The information and data provided in this report provides the technical basis for the codification for fiber reinforced piping (FRP) for hydrogen service. The DOE has invested in the evaluation of FRP for the delivery for gaseous hydrogen to support the development of a hydrogen infrastructure. The codification plan calls for detailed investigation of the following areas: System design and applicable codes and standards; Service degradation of FRP; Flaw tolerance and flaw detection; Integrity management plan; Leak detection and operational controls evaluation; Repair evaluation. The FRP codification process started with commercially available products that had extensive use in the oil and gas industry. These products have been evaluated to assure that sufficient structural integrity is available for a gaseous hydrogen environment.

  13. Graphite-Reinforced Polycyanate Composites for Space and Missile Applications

    DTIC Science & Technology

    1993-11-01

    ground experiment (pp. E-61). ACTEX I (Advanced Control Technology Experiment) is scheduled for the STEP-3 flight in July 1994. It is fabricated in an...Marietta 3:30 Clementine Panels, etc. G. Krumweide, Composite Optics 3:50 ACTEX , etc. R. Lewis, TRW 4:10 All-Composite Spacecraft, etc. H. Dursch

  14. Molybdenum disilicide composites reinforced with zirconia and silicon carbide

    SciTech Connect

    Petrovic, J.J.

    1992-12-31

    This patent pertains to compositions consisting essentially of molybdenum disilicide, silicon carbide, and a zirconium oxide component. The silicon carbide used in the compositions is in whisker or powder form. The zirconium oxide component is pure zirconia or partially stabilized zirconia or fully stabilized zirconia. Fabrication, fracture toughness, and bend strength are covered.

  15. Composite Reinforcement using Boron Nitride Nanotubes

    DTIC Science & Technology

    2014-05-09

    while retaining the nanotube structure. This project involves the use of computational quantum chemistry to study interactions of aluminium (Al...small clusters of 1–4 metal atoms. The effect of varying the radius of the nanotubes and the size of aluminium and titanium clusters was considered...15. SUBJECT TERMS Boron Nitride Nanotubes, composite materials, Aluminum Alloys , Titanium Alloy , Theoretical Chemistry 16. SECURITY

  16. Fabric geometry distortion during composites processing

    NASA Technical Reports Server (NTRS)

    Chen, Julie

    1994-01-01

    Waviness and tow misalignment are often cited as possible causes of data scatter and lower compression stiffness and strength in textile composites. Strength differences of as much as 40 percent have been seen in composites that appear to have the same basic material and structural properties -- i.e., yarn orientation, yarn size, interlacing geometry. Fabric geometry distortion has been suggested as a possible reason for this discrepancy, but little quantitative data or substantial evidence exists. The focus of this research is to contribute to the present understanding of the causes and effects of geometric distortion in textile composites. The initial part of the study was an attempt to gather qualitative information on a variety of textile structures. Existing and new samples confirmed that structures with a significant direction presence would be more susceptible to distortion due to the compaction process. Thus, uniweaves (fiber vol frac: 54-72 percent) biaxial braids (vf: 34-58 percent) demonstrated very little fabric geometry distortion. In stitched panels, only slight buckling of z-direction stitches was observed, primarily near the surface. In contrast, for structures with high compaction ratios -- e.g., large cylindrical yarns (2.5:1) orpowder towpreg (4:1) -- there were visible distortions where previously smooth and periodic undulations were transformed to abrupt changes in direction. A controlled study of the effect of forming pressure on distortion was conducted on type 162 glass plain weave fabrics. Panels (6 x 6 in) were produced via a resin infusion type setup, but with an EPON 815 epoxy resin. Pressures ranging from hand layup to 200 psi were used (vf: 34-54 percent). Photomicrographs indicated that at pressures up to 50 psi, large changes in thickness were due primarily to resin squeeze out. At higher pressures, when intimate contact was made between the layers, there was some tow flattening and in-plane shifting to optimize nesting. However

  17. Development of Textile Reinforced Composites for Aircraft Structures

    NASA Technical Reports Server (NTRS)

    Dexter, H. Benson

    1998-01-01

    NASA has been a leader in development of composite materials for aircraft applications during the past 25 years. In the early 1980's NASA and others conducted research to improve damage tolerance of composite structures through the use of toughened resins but these resins were not cost-effective. The aircraft industry wanted affordable, robust structures that could withstand the rigors of flight service with minimal damage. The cost and damage tolerance barriers of conventional laminated composites led NASA to focus on new concepts in composites which would incorporate the automated manufacturing methods of the textiles industry and which would incorporate through-the-thickness reinforcements. The NASA Advanced Composites Technology (ACT) Program provided the resources to extensively investigate the application of textile processes to next generation aircraft wing and fuselage structures. This paper discusses advanced textile material forms that have been developed, innovative machine concepts and key technology advancements required for future application of textile reinforced composites in commercial transport aircraft. Multiaxial warp knitting, triaxial braiding and through-the-thickness stitching are the three textile processes that have surfaced as the most promising for further development. Textile reinforced composite structural elements that have been developed in the NASA ACT Program are discussed. Included are braided fuselage frames and window-belt reinforcements, woven/stitched lower fuselage side panels, stitched multiaxial warp knit wing skins, and braided wing stiffeners. In addition, low-cost processing concepts such as resin transfer molding (RTM), resin film infusion (RFI), and vacuum-assisted resin transfer molding (VARTM) are discussed. Process modeling concepts to predict resin flow and cure in textile preforms are also discussed.

  18. AN EMPIRICAL MODEL TO PREDICT STYRENE EMISSIONS FROM FIBER-REINFORCED PLASTICS FABRICATION PROCESSES

    EPA Science Inventory

    Styrene is a designated hazardous air pollutant, per the 1990 Clean Air Act Amendments. It is also a tropospheric ozone precursor. Fiber-reinforced plastics (FRP) fabrication is the primary source of anthropogenic styrene emissions in the United States. This paper describes an em...

  19. Woven silk fabric-reinforced silk nanofibrous scaffolds for regenerating load-bearing soft tissues.

    PubMed

    Han, F; Liu, S; Liu, X; Pei, Y; Bai, S; Zhao, H; Lu, Q; Ma, F; Kaplan, D L; Zhu, H

    2014-02-01

    Although three-dimensional (3-D) porous regenerated silk scaffolds with outstanding biocompatibility, biodegradability and low inflammatory reactions have promising application in different tissue regeneration, the mechanical properties of regenerated scaffolds, especially suture retention strength, must be further improved to satisfy the requirements of clinical applications. This study presents woven silk fabric-reinforced silk nanofibrous scaffolds aimed at dermal tissue engineering. To improve the mechanical properties, silk scaffolds prepared by lyophilization were reinforced with degummed woven silk fabrics. The ultimate tensile strength, elongation at break and suture retention strength of the scaffolds were significantly improved, providing suitable mechanical properties strong enough for clinical applications. The stiffness and degradation behaviors were then further regulated by different after-treatment processes, making the scaffolds more suitable for dermal tissue regeneration. The in vitro cell culture results indicated that these scaffolds maintained their excellent biocompatibility after being reinforced with woven silk fabrics. Without sacrifice of porous structure and biocompatibility, the fabric-reinforced scaffolds with better mechanical properties could facilitate future clinical applications of silk as matrices in skin repair.

  20. AN EMPIRICAL MODEL TO PREDICT STYRENE EMISSIONS FROM FIBER-REINFORCED PLASTICS FABRICATION PROCESSES

    EPA Science Inventory

    Styrene is a designated hazardous air pollutant, per the 1990 Clean Air Act Amendments. It is also a tropospheric ozone precursor. Fiber-reinforced plastics (FRP) fabrication is the primary source of anthropogenic styrene emissions in the United States. This paper describes an em...