Postbuckling of delaminated thin-walled composite columns subjected to compression

Abstract

Susceptibility to delamination is one of the major weaknesses of many advanced laminated composite structures. An integral element of research on composite structures is the analysis of the phenomenon accompanying with delamination formation. The sources of their formation should be already sought at the manufacturing stage when the delamination can occur due to the incorrectly selected autoclaving process parameters as well as their initiation can be initiated by the low velocity impacts , affecting also the local degradation of the stiffness of the material. Laminated fibre-reinforced composites made of high strength fibres in a relatively weak matrix material are susceptible to delamination (i.e. separation of the layers) . The physical quantities describing the initiation of delamination is the stress intensity factor or energy release fracture toughness. In comparison to the widely used isotropic materials i.e. steel or aluminium, the energy release rates of laminates are almost one hundred times smaller which confirms their relative propensity to delaminate .