Modelling of the non-axisymmetric bulging of elastoplastic shells of revolution under combined axisymmetric loadings

A method for the numerical investigation of the non-linear unsteady non-axisymmetric bulging of elasto-plastic shells of revolution under complex combined axisymmetric loadings and large subcritical strains is presented. The method enables the limit states and stability of the deformation processes of shells of revolution relative to axisymmetric and non-axisymmetric forms to be evaluated over a broad range of loading rates from quasistatic to dynamic. Its efficiency is substantiated by theoretical calculations and an experimental analysis of the stability of elastoplastic deformation processes of tubular metal samples during combined loadings by tension, internal pressure and torsion. The investigations performed show that preliminary loading alters the initial geometry of the shell and produces deformation anisotropy with great strengthening of the material in the direction of the principal axis of deformation. Torsion of an unloaded shell results in complex loading, which is especially apparent in the initial instant of application of the load and does not have an appreciable influence on the critical parameters of the non-axisymmetric loss of stability. (C) 2017 (C) 2018 Elsevier Ltd. All rights reserved.