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Fig. 1 End/external view of a failed carbon/epoxy cylinder tested at NSWC, Carderock, MD with partially developed kink band and ensuing longitudinally propagated kink–crack
From the author’s introduction:
“The use of advanced laminated composite materials in deep submersible applications has received much attention in recent decades [1]. The material used in such applications must necessarily be thick-sectioned and must resist large hydrostatic pressures. The laminated shell-type structures thus fabricated must be designed to resist catastrophic collapse caused by global (structural) buckling. The deformation and failure behaviours (e.g. buckling/post-buckling, shear crippling, mode II fracture, etc.) of these laminates are of great concern to designers and operators alike. Of primary interest is the sensitivity of the response of a thick composite ring or cylindrical shell to thickness shear, fibre misalignments, as well as to geometrical defects such as modal imperfections, e.g. out-of-roundness.”
FROM:
Reaz A. Chaudhuri, “Effects of thickness and fibre misalignment on compression fracture in cross=ply (very) long cylindrical shells under external pressure”, Proceedings of the Royal Society A, Mathematical, Physical and Engineering Sciences, Vol. 471, No. 2180, August 2015, DOI: 10.1098/rspa.2015.0147
ABSTRACT: Combined effects of modal imperfections, transverse shear/normal deformation with/without reduced transverse shear modulus, GLT (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.
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