Kharazi et al. [1] have used spring simulation technique to analyse the buckling of the laminates including the bend-twist coupling effects with multiple embedded delaminations. In this study, the minimization of the total potential energy of the system has been used to obtain the buckling load. Kharazi and Ovesy [2] have investigated the compressive behaviour of composite laminates, i.e. bucking and post buckling behaviour, with a single through the width delamination by developing an analytical method based on the Rayleigh-Ritz approximation technique in the context of classical laminated plate theory (CLPT). This method can handle both local buckling of the delaminated sublaminate and global buckling of the whole plate.

In the current paper, the compressive behaviour of composite laminates with multiple through-the-width delaminations is investigated analytically. The analytical method is based on the first order shear deformation theory (FSDT) and its formulation is developed on the basis of the Rayleigh-Ritz approximation technique to analyze the bucking and post-buckling behaviour of delaminated laminates. The delaminated plates are divided in different regions and the continuity conditions at the divided regions boundaries are considered. For this purpose the assumed inplane and out of plane displacement functions and assumed rotation functions are considered in such a way that they satisfy the boundary conditions and continuity conditions in the divided regions boundaries. In addition, in the case of multiple delaminations, the contact phenomenon is considered in this study. For modelling the contact between different delaminated sublaminates, the spring distribution is considered in the contact area between delaminated sublaminates. The distributed springs have constant stiffness and they are frictionless.

The method can handle both local buckling of the delaminated sublaminates and global buckling of the whole plate. Some interesting results are obtained and compared with those achieved by the application of the finite element (FE) method of analysis. It is seen that the buckling loads of the plates with two delaminations are decreased by increasing the delaminations length. It is also seen that the mode of post-buckling and the corresponding load-carrying capacity strongly depend on the delaminations length and depth. The agreement between the results of the current FSDT analysis and those from the FE analysis is very good.

1

M. Kharazi, H.R. Ovesy and S.A.M. GhannadPour, "The Buckling of Laminates Including Bending-Twisting Coupling Effects with Multiple Delaminations Using Spring Simulation", in Proceedings of the Eighth International Conference on Computational Structures Technology, B.H.V. Topping, G. Montero and R. Montenegro, (Editors), Civil-Comp Press, Stirlingshire, United Kingdom, paper 270, 2006. doi:10.4203/ccp.83.270

2

M. Kharazi and H.R. Ovesy, "Postbuckling behavior of composite plates with through-the-width delaminations", Accepted for Publication in the International Journal of Thin-Walled Structure. doi:10.1016/j.tws.2008.01.005

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £145 +P&P)