Secondary buckling and failure behaviors of composite sandwich panels with weak and strong cores under in-plane shear loading

摘要

The secondary buckling and failure behaviors of composite sandwich panels (CSPs) subjected to in-plane shear loading are studied via a self-developed quasi-conforming finite element method. The influences of key material and geometry parameters on postbuckling and failure behaviors are investigated. Numerical results show that (1) postbuckling failure is dominated by the ratio of two strengths, i.e. the through-thickness shear strength of the core and the transverse tensile strength of the lamina. In addition, two constant thresholds for this strength ratio exist in the relationship between the load bearing capacity of CSPs and the ratio, which can be used to define "weak" or "strong" core and the status of postbuckling load bearing capacity (PLBC); (2) local failures of the core and face sheets (FSs) can lead to a drastic decrease in the local stiffness of CSPs, a singularity of the tangent stiffness matrix and the occurrence of secondary bucklings of CSPs; (3) secondary bifurcation identification, branch switching and convergence improvement are all necessary to obtain reasonable paths during the path-following. (C) 2019 Elsevier Masson SAS. All rights reserved.