Thermal post buckling analysis of laminated composite plates by the finite element method

Problems of dynamic buckling of antisymmetric rectangular laminates Birman, V. Composites Structures Vo112 No 1 (1989) pp 1-15 Dynamic buckling of asymmetrically laminated angle ply rectangular plates due to axial loads proportional to time and axial step loads is considered. The non linear response of initially imperfect plates is determined from the numerical solution of the governing differential equation. In the case of Step loading this equation can be solved analytically. In the particular problem of the perfect plate the solution of the linear problem yields the condition of dynamic buckling. The paper also addresses the problem in the behaviour of an imperfect plate initially loaded by axial static stresses. The static response is determined first and the motion of the plate is superimposed on the static displacements in the second phase of the solution. Short holding time effect on fatigue behaviour of unnotched graphite/epoxy laminates (--+45°)2, Lee, J.R. and De Chanrentenay, F.X. Journal o f Composite Materials Vol 23 No 9 (1989) pp 912-922 The effect of a fatigue-creep interaction on unnotched graphite/epoxy + 45 ° laminates was investigated in terms of fatigue life. The samples were fatigued with a frequency of 2 Hz followed by 150 seconds at peak load repeatedly to produce a fatigue-creep interaction. Loading levels from 60% to 85% of the ultimate stress of the uniaxially loaded specimen were used. It was determined that the maximum loads and loading histories were the controlling factors for the fatigue under this loading regime. A study on the effect of bending-twisting coupling on buckling strength Grenestedt, J.L. Composite Structures Vo112 No 4 (1989) pp 271-290 The neglect of bending twisting coupling stiffnesses, can lead to the derivation of simple closed form expressions. But these 'orthotropic' expressions give nonconservative approximations for the buckling load. This paper describes the use of a perturbation approach in conjunction with the orthotropic expressions. This procedure requires less computations than in finite difference or finite element calculations. The perturbation approach was also used to derive an optimization algorithm based on the simple orthotropic expressions for the optimal layup when bending-twisting coupling is present. Thermal post buckling analysis of laminated composite plates by the finite element method Chen, Lien-Wen, and Chen, Lei-Yi, Composite Structures Vol 12 No 4 (1989) pp 257-270 In this paper the thermal post buckling behaviour of composite laminated plates subjected to a non-uniform temperature field is investigated by the finite element method. The results of the computations reveal that the thermal post buckling behaviour of composite laminated plates is influenced by lamination angle, plate aspect ratio, modulus ratio and the number of layers. Thermoelastic assessment of damage growth in composites Jones, R., Heller, M., Lombardo, D., Dunn, S., Paul, J. and Saunders, D. Composite Structures Vo112 No 4 (1989) pp 291-314

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This paper examines, experimentally and numerically, the use of thermal emission measurements as a means of assessing the severity of damage and monitoring damage growth in composite materials. The thermal emission profile reflects the interaction of load, geometry, material and damage in a non-destructive fashion. This technique represents a possible method for the scaling of test data, obtained from coupon tests, to tests on full scale structures. Three-dimensional analysis of a postbuckled embedded delamination Whitcomb, J.D. Journal o f Composite Materials Vol23 No 9 (1989) pp 862-889 In this paper delamination growth was considered, initialized by local buckling of a delaminated group of plates. The growth of delamination was assumed to be determined by the strain-energy release rates which were subsequently calculated using a geometrically non-linear, three-dimensional, finite element analysis. The effectiveness of the analysis was evaluated, a limited parametric study was carried out and a number of conclusions from this discussed. Three-dimensional stress analysis of composite structures using isodyne techniques Pindera, J.T. Polymer Composites Vo110 No 5 (1989) pp 270-284 The stresses in laminated plates which are commonly assumed to be two-dimensional are known to be three-dimensional in the region of notches, edges or material inhomogeneities. Classical photoelastic stress analysis is inadequate to accurately describe the stress states in these regions. In this paper isodyne techniques both analytical and experimental (optical) were used to analyse a composite structure. They were shown to be more accurate and efficient than standard stress analysis techniques. Time-dependent response of Aramid-EpoxyAluminium sheet (ARALL) laminates Pindera, M.J., Williams, T.G. and Macheret, Y. Polymer Composites Vo110 No 5 (1989)pp 328-336 This paper examines the time dependent response of an aramid-epoxy-aluminium sheet laminate, ARALL-4 under conditions of creep loading. The creep response was primarily controlled by the creep response of the aluminium layer and its magnitude was found to depend upon both the applied stress and the residual stress state in the aluminium. An analytical model was developed based on classical laminate theory which gave good predictions of the observed non-linear creep response of the laminate. Vibrations of orthotropic triangular plates Malhotra, S.K., Ganesan, N., Veluswami, M.A. Composite Structures Vol 12 No 1 (1989) pp 17-25 This paper describes the effect of fibre orientation and boundary conditions on vibration behaviour of thin orthotropic triangular plates by using a three-noded, triangular plate finite element. Isosceles triangles with three different included angles are analysed.

METAL MA TRICES Damping behaviour of mechanically alloyed aluminium and aluminium matrix composites

Bhagat, R.B., Amateau, M.F. and Smith, E.C. International Journal o f Powder Metallurgy Vol25 No 4 (1989) pp 311-316 An investigation is carried out to measure and evaluate the damping of a representative mechanically alloyed metal and a representative particulate composite. Thus a commercial mechanically alloyed AI-Mg alloy and a SiC particulate reinforced Al-Cu alloy are tested and compared to 6061 Al. The logarithmic decrement of freely decaying resonance oscillations in clamped-flee cantilever beam specimens is determined. Peak damping capacity of the SiC-particulate reinforced A1-Cu alloy composite is 2.43 times and 2.83 times the damping capacity of the mechanically alloyed A1-Mg alloy and 6061 Al respectively at the same resonance frequency. The damping peak is seen to be unique to the aluminium matrix composite and a mechanism is proposed to explain the large energy dissipation. Damping behaviour of planar random carbon fibre reinforced 6061 AI matrix composites fabricated by high-pressure infiltration casting Bhagat, R.B., Amateau, M.F. and Smith, C. Journal of Composites Technology and Research Vo111 No 3 (1989) pp 113-116 The damping properties of carbon fibre reinforced aluminium matrix composites were considered in this paper. Cantilever beam specimens were vibrated at resonant frequencies in the first three modes of flexure vibration. The damping capacity was reported as a loss factor up to a resonant frequency of 13 kHz for volume fractions between 0.10 and 0.36 of carbon fibre. Two damping peaks were found in the frequency range 850-4700 Hz. Their frequency was not sensitive to volume fraction. The damping capacity of the composite was concluded to be over a magnitude higher than that of the aluminium matrix alone. Dry sliding wear of sintered 6061 aluminium alloy-graphite particle composite Jha, A.K., Prasad, S.V. and Upadhyaya, G.S. Tribology International Vol 22 No 5 (1989) pp 321-327 The wear behaviour of a sintered 6061 (AlMg-Si) aluminium alloy-graphite composite was studied under conditions of dry sliding wear. The graphite was present as dispersed particles within the aluminium alloy. Interconnected porosity was present in the composite, this was found to increase with the volume fraction of graphite. Wear experiments were carried out using a pin on disc method to evaluate the effects of sliding speed, sliding distance, applied pressure and amount of graphite. Wear rates were found to increase with increasing amounts of graphite and no graphite film was observed on the worn surfaces. This anomalous behaviour was attributed to increased porosity in the sintered composite. A material model for the finite element analysis of metal matrix composites Wu, J.F., Shephard, M.S., Dvorak, G.J. and Bahei-el-Din, Y.A. Composites Science and Technology Vol35 No 4 (1989) pp 347-366 The micromechanical nonlinear behaviour of the matrix material in continuous fibre reinforced composites is evaluated by applying a finite element based procedure. A periodic hexagonal array of elastic fibres embedded in an elastic-plastic matrix material is used as a