Buckling analysis of delaminated laminates with consideration of contact in buckling mode

This paper concerns the buckling load analysis of laminates with a pre-exis ting delamination, using the finite element method based on the Mindlin pla te theory. To deal with the contact problem in the buckling mode, an effect ive algorithm is presented. In this method, an iterative updating process b ased on the first-order sensitivity analysis and the quadratic programming technique is proposed to compute the fictitious forces in contacting areas at first. These fictitious forces are then transferred into the stiffness p arameters of some artificial springs. The original stiffness matrix of syst em can be modified, using these artificial springs. Finally, the penetratio n between two delaminated layers in the buckling mode can be prevented effe ctively. Numerical examples show that this method is very efficient to solv e the contact problem in eigenvalue analysis from the viewpoint of its accu racy, stability and convergence speed. The effects of contact and delaminat ion size on the buckling load analysis are also investigated. Copyright (C) 1999 John Wiley & Sons, Ltd.