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The progressive failure analysis of laminated composite plates under transverse static loading has been carried out in linear and elastic range. The laminated composite plate has been modeled using eight noded isoparametric plate bending elements. The first order shear deformation theory has been applied and a shear correction factor is used. After the failure of the weakest ply, the stiffness is reduced by either fiber failure or matrix failure. The stiffness of failed lamina has been totally discarded and other existing laminae are considered to remain unchanged after the weakest ply failure. The strength of the laminate at the same point is evaluated again to see if the laminate can carry additional load. This ply-by-ply analysis progresses until the ultimate strength of the laminate is reached. The results in terms of first-ply failure load obtained in the present investigation have been compared with those available in published literature. A parametric study has been done on the progressive failure analysis.

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The effect of fluid on the natural frequencies of a vertical rectangular lock gate is investigated. The fluid is assumed to be inviscid and incompressible having an irrotational flow field. The far boundary of fluid domain is truncated near the lock gate structure by solving the Laplace equation using Fourier half range cosine series expansion. The formulation of lock gate structure is governed using Mindlin’s plate theory. The coupled interaction between the fluid domain and the lock gate structure is established using finite element method (FEM) and a computer code is written using FORTRAN. Convergence study and validation of the formulation are carried out to minimise the computational error. The natural frequencies of lock gate coupled with and without fluid are determined for undisturbed and linearised free surface conditions. By varying extent of fluid domain, the effect on the natural frequencies of lock gate is evaluated. The results of natural frequencies obtained may be useful to the designer when the reservoir lock gate structure is exposed to the natural disasters.

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