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The effect of matrix properties on reinforcement in short alumina fibre-aluminium metal matrix composites
of various investigators. The conclusion was that, compared with other tests such as the asymmetric four-point bend test, the Iosipeseu was the most practical technique currently available for testing composite materials. Effective thermal conductivity with interfaciai thermal barrier resistance Hasselman, D.P.H. and Johnson, L.F.Journalof Composite Materials Vo121 (June 1987) pp 508-515 Expressions for the effect of an interfacial thermal barrier resistance on the thermal conductivity of composites with a dilute concentration or spherical or cylindrical dispersed phase have been derived by modifying the original Rayleigh and Maxwell theories. For a given composite system and dispersed phase geometry, the effective thermal conductivity was found to depend on the volume fraction of the dispersed phase and size of dispersoids. This is in contrast to composites with no thermal barrier resistance. Effect of the automation of advanced composite fabrication process on part cost Krolewski, S. and Gutowski SAMPE Quarterly Vo118 No I (October 1986) pp 43-51 An economic model which was developed to assess the effect of automation on the cost of components and also to aid in the design of new automation methods by suggesting areas of improvement is discussed. Simple examples using the model are reported. The model compares the cost of manufacturing a fiat laminate using manual labour with that of using automated methods. The results suggest that m a n y current methods of producing advanced composites by automation, with the exception of filament winding and pultrusion, are not costeffective. A further suggestion is made that this need not be so if methods and materials are specifically designed for components made from composite materials throughout the whole process.
Elevated temperature testing of protective coatings on filament wound composite cylinders Foral, ILF., McGee, J.M. and Wolterman, D.J. SAMPE Quarterly Vol 18 No 3 (April 1987) pp 46-52 An experimental procedure developed to evaluate the thermal effectiveness of protective coatings on composite cylinders at elevated temperatures is described. The coated cylinders were tested in the transient 650°C environment produced in an electric resistance furnace. Test specimens, fabrication and test procedures and test results are described. The behaviour of five coatings, all of which performed effectively under the test conditions, is discussed. Fracture toughness and fatigue crack propagation of single fibre-bundle reinforced model composites Krey, J., Friedrich, K. and Schwalbe, K.H. Journal of Materials Science Letters Vol 6 No 7 (July 1987) pp 851-856 Compact tension samples, made with bundles of glass, aramid and carbon fibres parallel to the loading direction in polycarbonate and epoxy matrices, are used in this study. An increase of several orders of magnitude in fatigue lifetime is found for composites compared with the matrix materials, due to crack branching and arrest at the fibre bundle. A stress intensity factor model is used to characterize the effect of single bundles on toughness. The lower reinforcing effect on the
COMPOSITES
. JANUARY
1988
polycarbonate matrix is explained by the poor interfacial bond, the plastic deformation of the ductile matrix at the crack tip. Optimization of design allowables for composite structures Munjal, A.K, SAMPE Quarterly Vol 18 No 2 (January 1987) pp 18-27 In this paper the problems which are unique to designing structures in composite materials are discussed. The factors affecting design allowables which are discussed in some detail include: materials, material characterization, processing, tooling, quality control, method of fabrication, and service life degradation, Properties of composites Fan, T.C. and Knapp, J. SAMPE Quarterly Vo118 No 4 (July 1987) pp 16-19 An energy criterion is used to derive an approximate formula for the prediction of composite strength in general, the composite being defined as a matrix with some reinforcement. The formula is shown to be applicable to the uniaxial strength of composites. Selected materials issues associated with space station Leger, L, Visentine, J. and Santos-Mason, B. SAMPE Quarterly Vol 18 No 2 (January 1987) pp 48-54 Methods of protecting candidate materials for use in the construction of a Space Station from the damaging effects of atomic oxygen are discussed. The coating of graphite/epoxy with A1 foil which has been found to have some merit is mentioned inter alia.
Static, dynamic and buckling formulation of a symmetrically laminated plate finite element for a micro-computer Chen, A,T. and Yang, T.Y. Journal of Composite Materials 1Iol21 (May 1987) pp 441-453 An 18 degrees of freedom, triangular plate finite element is formulated in bending with anisotropic symmetrically laminated composite materials. The associated numerical procedures and microcomputer program for static, free vibration and buckling analysis are presented. The results are compared with previous beam element formulations. Both methods were found to be efficient for microcomputers. Stress-strain curve of fibrous composites Laws, V. Journal of Materials Science Letters Vol 6 No 6 (June 1987) pp 675-678 The effect of fibre length and orientation is taken into account in the present model to predict the stress/strain curve of composites containing short, non-aligned fibres. The strains at the end of the multiple matrix cracking region of the curve and at failure are predicted. Symmetric three directional optimal laminate design Park, WJ., Journal of Composite Materials Vo121 (June 1987) pp 532-535 The optimal designing of three-directional symmetric laminates under various in-plane single loading conditions is considered using a first ply failure criterion, and ply orientation angles and ply thicknesses as design variables. The computation of the optimization problem is performed using a box complex method.
METAL MATRICES The characterisation of boron-aluminium composite in the non-linear range as an orthotropic elastic-plastic material Kenaga, D., Doyle, J.F. and Sun, C.T.Journalof Composite Materials Vo121 (June 1987) pp 516531 The authors have characterized a boron/ a l u m i n i u m composite using off-axis uniaxial testing, showing that it behaves as an orthotropic elastic-plastic material. A formulation of anisotropic elasto-plasticity is proposed with a method for determining material properties. The results of the experimental characterization are also presented. Deformation into wires of cast aluminium-nickelgraphite particulate composites Rohatgi, P.IC, Suroppa, M.K., Modi, O.P. and Yegneswaran, A.H. Zeitschrift fftr Metallkunde Vol 78 No 7 (July 1987) pp 513-515 Cast AI-3 Ni-3 graphite composites were drawn into 0.5 m m diameter wires by a combination of processes including forging at 700 IC hot rolling, annealing, and cold rolling, swaging and then wire drawing. The coarse granular graphites originally present were aligned along the deformation direction, with the aspect ratio having increased from 1 to 2 before working to as high as 100 as a result of deformation. The coarse NiAI 3 platelets were broken into small particles. The tensile strength of the wire drawn composite was found to increase from 86 MPa in the as-cast condition to 271 MPa after deformation. The effect of matrix properties on reinforcement in short alumina fibre-aluminium metal matrix composites Friend, C.M. Journal of Materials Science Vo122 (1987) pp 3005-3010 The effect of the alloy matrix on room temperature strengthening in delta-aluminareinforced aluminium alloys was investigated. By modifying a simple rule of mixtures expression to take into account the random orientation and discontinuous nature of the reinforcement, the observation that the extent of fibre strengthening is dependent on the type of alloy matrix is explained. High temperature interfacial studies in alumiuium-stainless steel composites Tiwari, S.N., Tiwari, A.N. and Gopinathan, V. Journal of Materials Science 1Iol 22 (1987) pp 2680-2684 The effects of elevated temperatures (up to 823 K for periods of up to 24 hours) on the interfacial shear strength of a single wire aluminium/stainless steel composite were investigated. It was found that annealing at 500 K for 24 hours led only to a slight decrease in interfacial shear strength at the annealing temperature. During high temperature exposure an interfacial compound layer was produced and precipitation of intermetallics occurred. The post-exposure interfacial shear strength at room temperature was found to be inversely proportional to the square root of the interfacial compound layer thickness. Interfacial shear strength was independent of wire diameter. Material damping in aluminium and metal-matrix composites Crawley, E,F. and Van Schoor, M.C. Journal of Composite Materials Vo121 (June 1987) 553-568
77
Elevated temperature testing of protective coatings on filament wound composite cylinders Foral, ILF., McGee, J.M. and Wolterman, D.J. SAMPE Quarterly Vol 18 No 3 (April 1987) pp 46-52 An experimental procedure developed to evaluate the thermal effectiveness of protective coatings on composite cylinders at elevated temperatures is described. The coated cylinders were tested in the transient 650°C environment produced in an electric resistance furnace. Test specimens, fabrication and test procedures and test results are described. The behaviour of five coatings, all of which performed effectively under the test conditions, is discussed. Fracture toughness and fatigue crack propagation of single fibre-bundle reinforced model composites Krey, J., Friedrich, K. and Schwalbe, K.H. Journal of Materials Science Letters Vol 6 No 7 (July 1987) pp 851-856 Compact tension samples, made with bundles of glass, aramid and carbon fibres parallel to the loading direction in polycarbonate and epoxy matrices, are used in this study. An increase of several orders of magnitude in fatigue lifetime is found for composites compared with the matrix materials, due to crack branching and arrest at the fibre bundle. A stress intensity factor model is used to characterize the effect of single bundles on toughness. The lower reinforcing effect on the
COMPOSITES
. JANUARY
1988
polycarbonate matrix is explained by the poor interfacial bond, the plastic deformation of the ductile matrix at the crack tip. Optimization of design allowables for composite structures Munjal, A.K, SAMPE Quarterly Vol 18 No 2 (January 1987) pp 18-27 In this paper the problems which are unique to designing structures in composite materials are discussed. The factors affecting design allowables which are discussed in some detail include: materials, material characterization, processing, tooling, quality control, method of fabrication, and service life degradation, Properties of composites Fan, T.C. and Knapp, J. SAMPE Quarterly Vo118 No 4 (July 1987) pp 16-19 An energy criterion is used to derive an approximate formula for the prediction of composite strength in general, the composite being defined as a matrix with some reinforcement. The formula is shown to be applicable to the uniaxial strength of composites. Selected materials issues associated with space station Leger, L, Visentine, J. and Santos-Mason, B. SAMPE Quarterly Vol 18 No 2 (January 1987) pp 48-54 Methods of protecting candidate materials for use in the construction of a Space Station from the damaging effects of atomic oxygen are discussed. The coating of graphite/epoxy with A1 foil which has been found to have some merit is mentioned inter alia.
Static, dynamic and buckling formulation of a symmetrically laminated plate finite element for a micro-computer Chen, A,T. and Yang, T.Y. Journal of Composite Materials 1Iol21 (May 1987) pp 441-453 An 18 degrees of freedom, triangular plate finite element is formulated in bending with anisotropic symmetrically laminated composite materials. The associated numerical procedures and microcomputer program for static, free vibration and buckling analysis are presented. The results are compared with previous beam element formulations. Both methods were found to be efficient for microcomputers. Stress-strain curve of fibrous composites Laws, V. Journal of Materials Science Letters Vol 6 No 6 (June 1987) pp 675-678 The effect of fibre length and orientation is taken into account in the present model to predict the stress/strain curve of composites containing short, non-aligned fibres. The strains at the end of the multiple matrix cracking region of the curve and at failure are predicted. Symmetric three directional optimal laminate design Park, WJ., Journal of Composite Materials Vo121 (June 1987) pp 532-535 The optimal designing of three-directional symmetric laminates under various in-plane single loading conditions is considered using a first ply failure criterion, and ply orientation angles and ply thicknesses as design variables. The computation of the optimization problem is performed using a box complex method.
METAL MATRICES The characterisation of boron-aluminium composite in the non-linear range as an orthotropic elastic-plastic material Kenaga, D., Doyle, J.F. and Sun, C.T.Journalof Composite Materials Vo121 (June 1987) pp 516531 The authors have characterized a boron/ a l u m i n i u m composite using off-axis uniaxial testing, showing that it behaves as an orthotropic elastic-plastic material. A formulation of anisotropic elasto-plasticity is proposed with a method for determining material properties. The results of the experimental characterization are also presented. Deformation into wires of cast aluminium-nickelgraphite particulate composites Rohatgi, P.IC, Suroppa, M.K., Modi, O.P. and Yegneswaran, A.H. Zeitschrift fftr Metallkunde Vol 78 No 7 (July 1987) pp 513-515 Cast AI-3 Ni-3 graphite composites were drawn into 0.5 m m diameter wires by a combination of processes including forging at 700 IC hot rolling, annealing, and cold rolling, swaging and then wire drawing. The coarse granular graphites originally present were aligned along the deformation direction, with the aspect ratio having increased from 1 to 2 before working to as high as 100 as a result of deformation. The coarse NiAI 3 platelets were broken into small particles. The tensile strength of the wire drawn composite was found to increase from 86 MPa in the as-cast condition to 271 MPa after deformation. The effect of matrix properties on reinforcement in short alumina fibre-aluminium metal matrix composites Friend, C.M. Journal of Materials Science Vo122 (1987) pp 3005-3010 The effect of the alloy matrix on room temperature strengthening in delta-aluminareinforced aluminium alloys was investigated. By modifying a simple rule of mixtures expression to take into account the random orientation and discontinuous nature of the reinforcement, the observation that the extent of fibre strengthening is dependent on the type of alloy matrix is explained. High temperature interfacial studies in alumiuium-stainless steel composites Tiwari, S.N., Tiwari, A.N. and Gopinathan, V. Journal of Materials Science 1Iol 22 (1987) pp 2680-2684 The effects of elevated temperatures (up to 823 K for periods of up to 24 hours) on the interfacial shear strength of a single wire aluminium/stainless steel composite were investigated. It was found that annealing at 500 K for 24 hours led only to a slight decrease in interfacial shear strength at the annealing temperature. During high temperature exposure an interfacial compound layer was produced and precipitation of intermetallics occurred. The post-exposure interfacial shear strength at room temperature was found to be inversely proportional to the square root of the interfacial compound layer thickness. Interfacial shear strength was independent of wire diameter. Material damping in aluminium and metal-matrix composites Crawley, E,F. and Van Schoor, M.C. Journal of Composite Materials Vo121 (June 1987) 553-568
77