Dynamic crack propagation in elastoplastic thin-walled structures: Modelling and validation

Artikel i vetenskaplig tidskrift, 2013

In this paper, a method to analyse and predict crack propagation in thin-walled structures subjected to large plastic deformations when loaded at high strain rates—such as impact and/or blast—has been proposed. To represent the crack propagation independently of the finite element discretisation, an extended finite element method based shell formulation has been employed. More precisely, an underlying 7-parameter shell model formulation with extensible directors has been extended by locally introducing an additional displacement field, representing the displacement discontinuity independently of the mesh. Of special concern in the paper has been to find a proper balance between, level of detail and accuracy when representing the physics of the problem and, on the other hand, computational efficiency and robustness. To promote computational efficiency, an explicit time step scheme has been employed, which however has been discovered to generate unphysical oscillations in the response upon crack propagation. Therefore, special focus has been placed to investigate these oscillations as well as to find proper remedies. The paper is concluded with three numerical examples to verify and validate the proposed model.Copyright © 2013 John Wiley & Sons, Ltd.