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Laminated composites containing an elliptical opening II. Experiment and model modification
Iiterature survey I
re survey
Prepared by M. E. Adams, L. Boniface, M. C. Hi/land 7. Nensi
CARBON MA TRICES
GENERAL
The evaluation of two-dimensional carboncarbon composite material by dynamic mechanical analysis Biddle, R. A. and Johnson III, W. J. Composites Science and Technology Vol 29 No 4 (1987)pp 239-255 Carbon-carbon samples made from a carbon fibre cloth densified with either a pitch-based or CVD matrix were examined using dynamic mechanical analysis. The method is shown to be non-destructive for the sample analysed. The technique defined differences in the mechanical properties of samples of the same material formed into conic sections and fiat panels, with an orientation effect found in the former. Differences between the pitch and CVD matrices were also shown. Details of the experimental technique and assumptions made during calculation of the mechanical properties are discussed.
The effect of fibre characteristics on the morphology and performance of semicrystalline thermoplastic composites Turner, R. M. and Cogswell, F. N. SAMPE Journal Vo123 No I (January~February 1987) pp 40-44) The feasibility of impregnating a range of fibres with PEEK for use in composite materials is discussed. Fibres investigated include quartz, glass (E, R and S), aramid, and carbon (HS, IM, HM and UHM). Mechanical properties of resultant composites are also reported.
CERAMIC MA TRICES Effects of pull-out on the mechanical properties of ceramic-matrix composites Thouless, M. D. and Evans, A. G. Acta Metallurgica Vo126 No 3 (1988) pp 517-522 Using weakest-link statistics, the influence of fibre pull-out on the mechanical properties of fibre-reinforced ceramics where the fibres are weakly bonded was studied. A relationship between stress and displacement for matrix cracks was derived. Using this relationship, the effects of variables such as fibre strength, interracial shear resistance, fibre diameter and fibre strength variability were elucidated. Tensile performance of carbon fibrereinforced glass Nardone, V. C. and Prewo, K. M. Journal of Materials Science Vol 23 No 1 (1988) pp 168-180 The tensile stress-strain behaviour of various unidirectional and angle-ply carbon fibrereinforced borosilicate glass specimens were studied under static and cyclic loading conditions. The stress-strain curve for a 0° coupon was found to be linear until the onset of matrix microcracking, which produced a knee in the curve and a positive component in the transverse strain. For 10° and 30° off-axis coupons, the longitudinal stressstrain curves were linear until fracture. In the case of multiaxially reinforced composites, positive transverse strain accumulation was found to be less pronounced or totally lacking although the stress-strain curves were highly non-linear.
328
Fibre-matrix bond strength studies of glass, ceramic, and metal matrix composites Grande, D. H., MandeU, J. F. and Hong, K. C. C. Journal of Materials Science Vo123 No 1 (1988) pp 311-328 An experimental technique, based on a microbonding test method, is described which is used to determine the in-situ fibre-matrix bond strength in typical asprocessed polymer, ceramic and metal matrix composites. The debonding processes were modelled using finite element analysis. It was found that very high bond strengths cause weak, brittle composite behaviour in longitudinal tension and flexure. Reducing bond strength increased strength and toughness. Increasing bond strength increased composite interlaminar shear strength and residual stresses can have a strong effect on the measured bond strength. Free and forced non-linear dynamics of composite shell structures Wu, Y. C., Yong, T. Y. and Saigal, S. Journal of Composite Materials Vol 21 (October 1987) pp 898-909 A 48 degree of freedom Kirchhoff-Love curved shell element is applied to the free and forced non-linear dynamic respons e of laminated composite shells of general form. A numerical study of the effect of number and orientation of lamina is undertaken. A good correlation which existing alternative solutions is obtained. Laminated composites containing an elliptical opening I. Approximate stress analyses and fracture models Tan, S. C. Journal of Composite Materials Vol 21 (October 1987) pp 925-948 A simple closed form solution is derived for the notched strength of orthotropic laminates with an elliptical opening, under uniaxial normal loads, using approximate stress analyses. The solution is found to have excellent accuracy when compared to the exact elasticity solution. Laminated composites containing an elliptical opening I1. Experiment and model modification
Tan, S. C. Journal of Composite Materials Vo121 (October 1987) pp 949-968 A modified model based on the extended point stress and average stress fracture criteria is presented. The model expresses the characteristic length as a function of the opening length and aspect ratio and is able to predict the notch strength of orthotropic laminates with circular or elliptical holes or cracks. The predictions agreed well with experimental data. Modelling clamp-up effects in composite bolted joints Smith, P. A., Ashby, M. F. and Pascoe, K. J. Journal of Composite Materials Vol 21 (October 1987) pp 878-897 A model is presented to predict the bearing stress at the onset of failure in composite bolted joints which incorporates the effects of bolt clamp-up. The model is developed by obtaining expressions for the total clamping pressure and proposing failure criteria for local bearing failure and local tension failure as a function of bolt clamp-up. The effect of varying the coefficient of friction (~t) between the washer and the laminate and washer diameter are predicted and it was found that the bearing stress at failure onset increased with increasing p. at a given clamp-up pressure and with increasing washer size and clamp-up pressure. The model is found to predict the experimental trends reasonably well. The modelling of pressure distribution in resin transfer moulding Gauvin, R., Chibani, M. and Lafontaine, P. Journal of Reinforced Plastics and Composites Vol 6 No 4 (October 1987) pp 367-377 A simplified model is presented to predict mould cavity pressure distribution which is an important parameter in determining product quality in the RTM process. A computer simulation of the cavity filling process is performed, taking into account the effect on the model of parameters such as glass density, surface density of reinforcement and the number of layers mat. The permeability of the reinforcement is evaluated and preliminary results of the model are presented for glass mats. The paraboloidal failure surface of initially anisotropic elastic solids Theocaris, P. S. and Philippidis, T. P. Journal of Reinforced Plastics and Composites Vol 6 No 4 (October 1987) pp 378-395 A failure criterion for orthotropic materials is obtained by generalization of the elliptic paraboloidal yielding condition for isotropic materials. The effect of strength properties of highly anisotropic materials on the dimensions of the failure surface are evaluated u s i n g as examples oriented PP, PC and Kevlar 49.
COMPOSITES. JULY 1988
re survey
Prepared by M. E. Adams, L. Boniface, M. C. Hi/land 7. Nensi
CARBON MA TRICES
GENERAL
The evaluation of two-dimensional carboncarbon composite material by dynamic mechanical analysis Biddle, R. A. and Johnson III, W. J. Composites Science and Technology Vol 29 No 4 (1987)pp 239-255 Carbon-carbon samples made from a carbon fibre cloth densified with either a pitch-based or CVD matrix were examined using dynamic mechanical analysis. The method is shown to be non-destructive for the sample analysed. The technique defined differences in the mechanical properties of samples of the same material formed into conic sections and fiat panels, with an orientation effect found in the former. Differences between the pitch and CVD matrices were also shown. Details of the experimental technique and assumptions made during calculation of the mechanical properties are discussed.
The effect of fibre characteristics on the morphology and performance of semicrystalline thermoplastic composites Turner, R. M. and Cogswell, F. N. SAMPE Journal Vo123 No I (January~February 1987) pp 40-44) The feasibility of impregnating a range of fibres with PEEK for use in composite materials is discussed. Fibres investigated include quartz, glass (E, R and S), aramid, and carbon (HS, IM, HM and UHM). Mechanical properties of resultant composites are also reported.
CERAMIC MA TRICES Effects of pull-out on the mechanical properties of ceramic-matrix composites Thouless, M. D. and Evans, A. G. Acta Metallurgica Vo126 No 3 (1988) pp 517-522 Using weakest-link statistics, the influence of fibre pull-out on the mechanical properties of fibre-reinforced ceramics where the fibres are weakly bonded was studied. A relationship between stress and displacement for matrix cracks was derived. Using this relationship, the effects of variables such as fibre strength, interracial shear resistance, fibre diameter and fibre strength variability were elucidated. Tensile performance of carbon fibrereinforced glass Nardone, V. C. and Prewo, K. M. Journal of Materials Science Vol 23 No 1 (1988) pp 168-180 The tensile stress-strain behaviour of various unidirectional and angle-ply carbon fibrereinforced borosilicate glass specimens were studied under static and cyclic loading conditions. The stress-strain curve for a 0° coupon was found to be linear until the onset of matrix microcracking, which produced a knee in the curve and a positive component in the transverse strain. For 10° and 30° off-axis coupons, the longitudinal stressstrain curves were linear until fracture. In the case of multiaxially reinforced composites, positive transverse strain accumulation was found to be less pronounced or totally lacking although the stress-strain curves were highly non-linear.
328
Fibre-matrix bond strength studies of glass, ceramic, and metal matrix composites Grande, D. H., MandeU, J. F. and Hong, K. C. C. Journal of Materials Science Vo123 No 1 (1988) pp 311-328 An experimental technique, based on a microbonding test method, is described which is used to determine the in-situ fibre-matrix bond strength in typical asprocessed polymer, ceramic and metal matrix composites. The debonding processes were modelled using finite element analysis. It was found that very high bond strengths cause weak, brittle composite behaviour in longitudinal tension and flexure. Reducing bond strength increased strength and toughness. Increasing bond strength increased composite interlaminar shear strength and residual stresses can have a strong effect on the measured bond strength. Free and forced non-linear dynamics of composite shell structures Wu, Y. C., Yong, T. Y. and Saigal, S. Journal of Composite Materials Vol 21 (October 1987) pp 898-909 A 48 degree of freedom Kirchhoff-Love curved shell element is applied to the free and forced non-linear dynamic respons e of laminated composite shells of general form. A numerical study of the effect of number and orientation of lamina is undertaken. A good correlation which existing alternative solutions is obtained. Laminated composites containing an elliptical opening I. Approximate stress analyses and fracture models Tan, S. C. Journal of Composite Materials Vol 21 (October 1987) pp 925-948 A simple closed form solution is derived for the notched strength of orthotropic laminates with an elliptical opening, under uniaxial normal loads, using approximate stress analyses. The solution is found to have excellent accuracy when compared to the exact elasticity solution. Laminated composites containing an elliptical opening I1. Experiment and model modification
Tan, S. C. Journal of Composite Materials Vo121 (October 1987) pp 949-968 A modified model based on the extended point stress and average stress fracture criteria is presented. The model expresses the characteristic length as a function of the opening length and aspect ratio and is able to predict the notch strength of orthotropic laminates with circular or elliptical holes or cracks. The predictions agreed well with experimental data. Modelling clamp-up effects in composite bolted joints Smith, P. A., Ashby, M. F. and Pascoe, K. J. Journal of Composite Materials Vol 21 (October 1987) pp 878-897 A model is presented to predict the bearing stress at the onset of failure in composite bolted joints which incorporates the effects of bolt clamp-up. The model is developed by obtaining expressions for the total clamping pressure and proposing failure criteria for local bearing failure and local tension failure as a function of bolt clamp-up. The effect of varying the coefficient of friction (~t) between the washer and the laminate and washer diameter are predicted and it was found that the bearing stress at failure onset increased with increasing p. at a given clamp-up pressure and with increasing washer size and clamp-up pressure. The model is found to predict the experimental trends reasonably well. The modelling of pressure distribution in resin transfer moulding Gauvin, R., Chibani, M. and Lafontaine, P. Journal of Reinforced Plastics and Composites Vol 6 No 4 (October 1987) pp 367-377 A simplified model is presented to predict mould cavity pressure distribution which is an important parameter in determining product quality in the RTM process. A computer simulation of the cavity filling process is performed, taking into account the effect on the model of parameters such as glass density, surface density of reinforcement and the number of layers mat. The permeability of the reinforcement is evaluated and preliminary results of the model are presented for glass mats. The paraboloidal failure surface of initially anisotropic elastic solids Theocaris, P. S. and Philippidis, T. P. Journal of Reinforced Plastics and Composites Vol 6 No 4 (October 1987) pp 378-395 A failure criterion for orthotropic materials is obtained by generalization of the elliptic paraboloidal yielding condition for isotropic materials. The effect of strength properties of highly anisotropic materials on the dimensions of the failure surface are evaluated u s i n g as examples oriented PP, PC and Kevlar 49.
COMPOSITES. JULY 1988