Exact and approximate linear and nonlinear initial flexural failure analysis of fibre-reinforced laminated rectangular mindlin plates was considered in [2]. In this initial flexural failure analysis the following failure criteria were used: (a) maximum stress, (b) maximum strain, (c) Tsai-Hill, (d) Hoffman, (e) Tsai-Wu, and (f) maximum stress (independent). They developed an exact small deflection failure analysis and an approximate small and large deflection failure analyses. The same type of analyses were carried out in [3] where similar failure criteria were used for the same type of plates. Unlike what was predicted in [3] that Tsai-Hill failure criterion is not suitable for the initial flexural failure analysis of laminated rectangular plates. Turvey and Osman [2], unlike Reddy and Pandey [3], concluded that the Tsai-Hill criterion predicts failure pressures and locations, which are in agreement with other failure criteria.

With the conclusions of Reference [2], in the present work, Tsai-Hill failure criterion is used to predict the first-ply failure in flexure. The loading is a uniform pressure, with clamped edge constraints. Small and large finite-difference Dynamic Relaxation (DR) iterative method is developed but only small deflection analysis is carried out to compute first-ply failure pressures and deflections.

Shear deformations are taken into account but normal stresses are disregarded. Plate governing equations include: five equilibrium equations, strain/displacement, curvature/ displacement and stress resultants/strain and curvature and stress couples/strain and curvature equations. The equilibrium equations are transformed into DR format and the finite-difference discretization technique is used to prepare the plate governing equations in a form suitable for developing computer software.

Finally, a computer program is developed to generate the numerical results. In order to validate the computer program results, elastic small and large deflection results for isotropic plates are generated and compared with the corresponding values reported in [4]. The correlation were very satisfactory, consequently, new results were obtained which include first-ply failure pressures, deflections and radial and circumferential stress couples for different types of plates. The type of plates considered are 60, 90, 150 and 180 degrees sector angles, all with four layers symmetric [90/0] s glass/epoxy materials.

1

Salehi, M., Shakeri, M., and Khorsandi, A., "Small Deflection Analysis of Fibre-Reinforced Laminated Sector Mindlin Plates", Presented at the 4th International Conference on Computational Structures Technology, Edinburgh, Scotland, 18th � 20th August, pp. 199-208, 1998.

2

Turvey, G.J. and Osman, M.Y., "Exact and Approximate Linear and Nonlinear Initial Failure Analysis of Laminated Mindlin Plates in Flexure", Lancaster University, Bailrigg, Lancaster, LA1, 4YR, UK, 1994.

3

Reddy, J.N. and Pandey, A.C., "A First-Ply Failure Analysis of Composite Laminates", Computers and Structures, 25(3), pp. 371-393, 1987. doi:10.1016/0045-7949(87)90130-1

4

Salehi, M. and Shahidi, A., "Large Deflection Analysis of Elastic Sector Mindlin Plates", Vol. 52, No. 5, pp. 987-998, (1994). doi:10.1016/0045-7949(94)90083-3

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