Showing papers on "Composite number published in 1984"

Composite Materials Handbook

Abstract: An updated edition of this compilation of data on metal and resin matrix composites which now includes complete information on all new composite forms, fibres and resins introduced since the publication of the first edition.

Constitutive Theory for Strongly Anisotropic Solids

Abstract: We shall discuss a number of problems concerned with stress and deformation analysis of fibre-reinforced composite, and other strongly anisotropic, materials. The kind of composite material in mind is one in which a matrix material is reinforced by strong stiff fibres which are systematically arranged in the matrix. The fibres are considered to be long compared to their diameters and the fibre spacings, and to be quite densely distributed, so that the fibres form a substantial proportion (typically about 50% by volume) of the composite. There are many such composite materials now in use or under development; examples are carbon fibre reinforced epoxy resins, boron fibre reinforced aluminium, and nylon or steel reinforced rubber which is used in tyres, hosepipes and belts.

Creep rupture of a silicon carbide reinforced aluminum composite

Abstract: The microstructure, texture, and whisker orientations in 6061 Al-20 wt pct SiC whisker composites have been examined using transmission electron microscopy and X-ray diffraction. Tension creep tests of the composite material have also been conducted in the temperature range 505 to 644 K (450 to 700 F). The steady state creep rate of the composite depends strongly on the temperature and applied stress. The stress exponent for the steady state creep rate of the composite is approximately 20.5 and remains essentially constant within the range of test temperatures. The activation energy is calculated to be 390 kJ/mol, nearly three times as high as the activation energy for self-diffusion of aluminum. No threshold stress was observed. Fracture surface examination using scanning electron microscopy shows that the composite fails by coalescence of voids in the aluminum matrix which originate at the aluminum-SiC interface. It is demonstrated that SiC paniculate composites are less creep resistant than SiC whisker composites.

Prediction and Measurement of the Vibrational Damping Parameters of Carbon and Glass Fibre-Reinforced Plastics Plates:

Abstract: The objective of this investigation is to predict the natural frequency and specific damping capacity of laminated composite plates in various modes of vibration by using the finite element method.

Composite polycrystalline diamond

Abstract: A composite material is described which includes a mixture of individual diamond crystals and pieces of precemented carbide. The mixture is heated and pressurized to create intercrystalline bonds between the diamond crystals and chemical bonds between the diamond crystals and the precemented carbide pieces. The resulting composite polycrystalline diamond body exhibits excellent wear characteristics and impact resistance.

Composite low surface energy liner of perfluoropolyether

Abstract: Composite low surface energy liner provided by an inner layer of insoluble polymer made from a polymerizable, film-forming monomer and an outer layer of insoluble polymer made from a polymerizable perfluoropolyether monomer copolymerizable with said film-forming monomer, which layers are in-situ polymerized. The composite low surface energy liner is especially useful as a low-adhesion backsize coating in a pressure-sensitive adhesive tape.

Composite core coated microparticles and process of preparing same

Abstract: A process for preparing coated microparticles, which process comprises preparing a solvent solution of an active ingredient to be encapsulated and a film-forming polymer, removing the solvent to provide a dry, composite, uniform admixture of the active ingredient and the polymer material, reducing the composite admixture to a defined smaller particle size distribution, coating the reduced composite core particles in a fluidized bed, with a uniform defined wall thickness of the same or substantially the same film-forming polymer material to provide composite core coated microparticles.

Fibre reinforced composites

Abstract: A fibre reinforced composite comprises one or more layers of unidirectional non-woven fibres alternated with one or more layers of woven fibres, preferably in a satin, embedded in a plastics matrix.

Textural and Microstructural Changes in Corn Starch as a Function of Extrusion Variables

Abstract: The effect of extrusion variables (temperature, feed moisture and screw speed) on the expansion, breaking strength and microstructure of starch extrudates was studied using response surface methodology. For expansion the most significant variable was found to be feed moisture which bore an inverse relation to the expansion response. All the extrusion variables studied were significantly related to expansion and accounted for 95.7% of the total variation. Screw speed and feed moisture were the most significant variables for breaking strength, all three variables accounting for 89.7% of the total break strength variation. Microstructure of the extrudates could be related to the extrusion variables, the expansion and breaking strength responses. The porosity of the extrudates increased with decreasing moisture, with a concomitant increase in expansion and a decrease in breaking strength. Regression equations generated from composite rotatable response surface design experiments could be used to accurately predict the responses studied.

Seismic Response of Composite Shear Connections

Abstract: Four different failure modes, stud shearing, concrete pullout, rib shearing and rib punching are described for metal deck stud shear connections. Equations for predicting the strengths associated with those failures are derived. Behavioral comparisons are made between companion specimens subjected to monotonic and reversed cyclic loading. It is shown that the type of failure greatly influences the strength, ductility and reversed cyclic loading response. The benefits of using larger stud‐spadngs, staggering of the studs, larger rib widths and ribs parallel to the direction of applied shear are demonstrated.

Composite material bonded by an amorphous metal, and preparation thereof

Abstract: A composite material bonded by an amorphous metal. In one embodiment, a bonded piece is bonded to a substrate by a layer of amorphous metal interposed between the piece and the substrate. In another embodiment, a bonded composite material is formed with pieces of a second phase distributed throughout the volume of an amorphous matrix. In both embodiments, the second component of the composite is preferably a very hard material of low ductility, so that the composite material is useful in tooling applications. The solid composite material is formed by solid state processing, wherein the pieces are placed in contact and then consolidated at a temperature which does not exceed the crystallization temperature of the amorphous metal.

Thermoplastic interleafed resin matrix composites with improved impact strength and toughness

Abstract: High-performance fiber resin matrix composites are disclosed which are comprised of a first layer comprising reinforcing filaments coated with a thermosetting resin composition and a discrete second layer of a thermoplastic resin. When the composite layers are matched to provide certain minimum strength and elongation properties, composites of unusually high impact strength and resistance to impact damage are achieved which retain their high performance properties over a range of temperatures and environmental exposures.

Improved rigorous bounds on the effective elastic moduli of a composite material

Abstract: A new method for deriving rigorous bounds on the effective elastic constants of a composite material is presented and used to derive a number of known as well as some new bounds. The new approach is based on a presentation of those constants as a sum of simple poles. The locations and strengths of the poles are treated as variational parameters, while different kinds of available information are translated into constraints on these parameters. Our new results include an extension of the range of validity of the Hashin-Shtrikman bounds to the case of composites made of isotropic materials but with an arbitrary microgeometry. We also use information on the effective elastic constants of one composite in order to obtain improved bounds on the effective elastic constants of another composite with the same or a similar microgeometry.

The Initial Gap Around Large Composite Restorations in vitro: The Effect of Etching Enamel Walls:

Abstract: Composite resin restorations in cavities are generally associated with the development of a contraction gap during the first minutes after insertion. Enamel-Bond-Concise composite restorations were placed on both approximal sides of extracted pre-molars. The cervical walls of all cavities extended beyond the enamel-cement junction. The enamel walls of one of the cavities in each tooth were acid-etched. The contraction gap was kept air-filled and open at the margin through the use of a special technique. Enamel Bond resin with a fluorescent additive was applied to occlusal and cervical margins of the restorations.The fluorescent resin was "passively" drawn into the gap. In unetched cavities, resin penetrated both cervical and occlusal gaps and some areas of the gap at the axial wall. In cavities with etched enamel, the penetration occurred only at the cervical wall. The distance of penetration from the cervical margin varied from 1 to 6.5 mm, and the width of the contraction gap filled with the fluorescent...

Factors Affecting Moisture Absorption in Polymer Composites Part II: Influence of External Factors:

Abstract: The influence of external factors like relative humidity (0) and ambient temperature (T) on the moisture absorption behaviour of permeable (Jute-Epoxy) and impermeable (Glass-Epoxy and Graphite-Epoxy) types of composites were reported. The respective equilibrium moisture contents (Mm and Mm) increased exponentially with relative humidity. The diffusion coefficients of both type of composites (D~'and D,) increased with ambient temperature and could be represented by an Arrhenius relationship. The permeable composite showed a higher exponential power on the relative humidity term than the impermeable composite (2.64 for Jute composite as compared to 2.0 reported by Shen and Springer for a graphite composite) and a lower activation energy for diffusion (0.9 x 101 cal. mole-' for the jute composite as compared to 4.429 x 103 cal. mole-1 obtained for a glass composite). These trends were attributed to the fibre permeability leading to different diffusion barriers in such composites.

Low thermal expansion resin material and composite shaped article

Abstract: A resin material comprising a polyimide having as chemical structural unit at least one aromatic ring which can rotate around its molecular axis but has no flexibility at another direction, said polyimide being oriented at least at a uniaxial direction, has a low thermal expansion coefficient and can be shaped together with an inorganic material into one body to give a composite shaped article.

Composite and durable forming model with permeability

Abstract: Proposed models are used for forming into destined shapes liquid, slurry, soft, sheet or lump materials, and are provided with endurance for many times of use and excellent permeability. A basic feature is that aggregates are ferrous or non-ferrous metallic grains and ceramic grains, to which a binder contained in evaporating or consumable substance is added and kneaded, and sintered. The mode has a close hardened layer scattered with metallic oxides on at least a shell. The hardened layer has fine air vents in its thickness. The whole body of a model is 5 to 60% of porosity and more than 100 Kg/cm2 of compression strength.

Strength of intermingled hybrid composites

Abstract: This paper first treats the stress concentrations in an intermingled hybrid composite. An eigenvector expansion method is used to solve the governing equations of shear-lag analyses. Two effects on...

In situ roofing composite and method

Abstract: The invention comprises a built-up roof material that has a composite membrane that is formed and affixed to the roof substrate in a single step. The membrane comprises a sheet of heat-resistant, non-woven polyester sandwiched between layers of asphalt. The upper asphalt layer is caused to flow through the polyester and meld with the lower layer of asphalt to form a homogeneous composite.

Sintered silicon carbide/graphite/carbon composite ceramic body having ultrafine grain microstructure

Abstract: Sintered silicon carbide/graphite/carbon composite ceramic body having a homogeneous fine grain microstructure with at least 50 percent of its silicon carbide grains having a size not exceeding about 8 microns and an aspect ratio less than about 3, with graphite grains having an average size not exceeding that of the silicon carbide grains microns uniformly dispersed throughout the matrix of silicon carbide and having a density of at least 75 percent of theoretical can be made by firing of a shaped green body having a density of at least about 45 percent of theoretical, the shaped green body containing graphite of fine particle size, a sintering aid selected from the group consisting of aluminum, beryllium or boron or compounds containing any one or more of these or a mixture of any of the foregoing elements or compounds, silicon carbide having a surface area of from about 5 to about 100 square meters/gram and, optionally, a temporary binder at a sintering temperature of from about 1900° C. to about 2300° C. in an inert atmosphere or vacuum. The process for making such pressureless-sintered composite bodies is relatively undemanding of exact temperature/time control during sintering. Contain embodiments of such composite sintered bodies may electrical-discharge machined.

Method for the formation of composite articles comprised of thermotropic liquid crystalline polymers and articles produced thereby

Abstract: A method for the production of composite articles by pultrusion is provided wherein the articles comprise thermotropic liquid crystalline polymers and reinforcing fibers. The liquid crystalline polymers employed exhibit physical characteristics such that the negative slope of a dynamic viscosity-frequency curve (as defined) is less than about 0.35. The use of polymers having such rheological characteristics enables a composite material to be produced by pultrusion in which the polymer is uniformly dispersed among the reinforcing fibers.

Transducer comprising composite electrical materials

Abstract: A simplified method for fabricating composite transducers by bonding together plates of active and passive materials to form a laminated block. The active material is preferably a piezoelectric ceramic. Thereafter, a series of cuts are made in the laminated block to obtain a composite plate wherein regions of active material are separated from one another by regions of passive material. The method provides composite transducers having fine structures which can be produced without the difficulty of assembling many small rods or sawing deep, narrow grooves.

Composite fusible interlining fabric and method

Abstract: The composite fusible interlining fabric is formed of a layer of nonwoven fabric, a layer of fibrous material positioned against the reverse or rear side of the layer of nonwoven fabric, stitch yarn knit through the layer of nonwoven fabric and the layer of fibrous material and securing them together, and a coating of thermoactive adhesive material on the front or face side of the layer of nonwoven fabric. The layer of nonwoven fabric provides a smooth surface for the coating of thermoactive adhesive material. Additionally, the layer of nonwoven fabric of closely compacted fibers provides a barrier or shield to prevent strike back of the adhesive coating material when the composite interlining fabric is fused to the base or garment fabric.

Interlaminar Fracture of Random Short-Fiber SMC Composite

Abstract: In the experimental phase of the present study of the interlaminar fracture behavior of a randomly oriented short fiber sheet molding compound (SMC) composite, the double cantilever beam fracture test is used to evaluate the mode I interlaminar fracture toughness of different composite thicknesses. In the analytical phase of this work, a geometrically nonlinear analysis is introduced in order to account for large deflections and nonlinear load deflection curves in the evaluation of interlaminar fracture toughness. For the SMC-R50 material studied, interlaminar toughness is an order of magnitude higher than that of unreinforced neat resin, due to unusual damage mechanisms ahead of the crack tip, together with significant fiber bridging across crack surfaces. Composite thickness effects on interlaminar fracture are noted to be appreciable, and a detailed discussion is given on the influence of SMC microstructure.

Fiber-reinforced composites

Abstract: There is disclosed a fiber-reinforced composite having a high degree of fracture toughness and being composed of a glass-ceramic matrix reinforced with silicon carbide or graphite type fibers, the predominant crystal phase of the matrix glass-ceramic being canasite, and/or agrellite, and/or fedorite.

Fiber reinforced glass/glass-ceramic mirror blanks

Abstract: This invention relates to the production of mirror blanks comprising a low expansion graphite or SiC fiber reinforced glass-ceramic composite substrate with a surface facing of a glass or glass-ceramic bonded thereto having an expansion closely matching that of the composite.