Effects of thickness and fibre misalignment on compression fracture in cross-ply (very) long cylindrical shells under external pressure

Abstract

Combined effects of modal imperfections, transverse shear/normal deformation with/without reduced transverse shear modulus, G LT (caused by distributed fibre misalignments), on emergence of interlaminar shear crippling type instability modes, related to localization (onset of deformation softening), delocalization (onset of deformation hardening) and propagation of mode II compression fracture/damage, in thick imperfect cross-ply very long cylindrical shells (plane strain rings) under applied hydrostatic pressure, are investigated. Of special interest is the question: what are the geometric and/or material parameters that induce localized and delocalized states in imperfect cross-ply (very) long cylindrical shells under hydrostatic compression simultaneously, and what would be the consequences of such occurrences? The primary accomplishment is the (hitherto unavailable) computation of the layer-wise mode II stress intensity factor, energy release rate and kink–crack bandwidth, under hydrostatic compression, from a nonlinear finite-element analysis, using Maxwell's construction and Griffith's energy balance approach. Additionally, the shear crippling angles in the layers are determined using an analysis, pertaining to the elastic inextensional deformation of the compressed (plane strain) ring. Numerical results include effects of (i) thickness-induced transverse shear/normal deformation and (ii) uniformly distributed fibre misalignments, on localization and delocalization, and consequently on compression fracture/damage characteristics of thick imperfect cross-ply very long cylindrical shells.