AXISYMMETRICAL AND ASYMMETRIC POSTBUCKLING RESPONSE AND ENERGY-RELEASE RATE OF DELAMINATED CIRCULAR FILM

A delaminated circular film is treated as a thin circular plate clampe d to the substrate at the boundary of the delaminated zone, The axisym metric postbuckling response for the large deflections of the film und er the action of in-plane compression has been investigated by using a power series method to solve the Karman nonlinear equations for the a xisymmetric deformations of circular plates. The problem of the asymme tric bifurcation-buckling of the film from the axisymmetric large-defl ection equilibrium state has been investigated by using Fourier series and power series simultaneously to solve the Karman nonlinear equatio ns for the asymmetric deformations of circular plates. The energy rele ase rate related to the two stages of the buckling deformation has bee n calculated, and it is found that the energy release rate correspondi ng to the stage of the asymmetric postbuckling deformation is much hig her than that of the axisymmetric postbuckling stage. (C) 1998 Elsevie r Science Ltd. All rights reserved.