A numerical modelling framework for simulating rate-dependent delamination along polyurea/steel interfaces under Mode–I loading conditions

Abstract

Polyurea coated structures have drawn significant attention from researchers across the globe for various applications such as waterproof roofing, vibration control, and protection from impact and blast threats. Despite widespread studies on the rate-dependent nature of polyurea and its bulk deformation response, there are very few works which study the delamination in polyurea coated structures and the associated rate sensitivity. The present work is aimed at two objectives: (i) to develop a suitable rate-dependent traction–separation model that fits an existing experimental dataset from literature related to rate-dependent delamination of polyurea/steel interface and, (ii) to develop a simple, robust numerical modelling framework to simulate the rate-dependent delamination process in a double–cantilever beam experiment found in the same literature source. Fulfilling the first objective resulted in identifying the important parameters in a traction–separation relation and their rate-dependency. A non-zero traction at zero crack opening displacement is one of the striking features of the experimental data and the proposed model takes that into account. As part of the second objective, a numerical modelling involving separate constitutive equations for the bulk and interface regions of the polyurea adhesive has been proposed. The interface is modelled as a rate-dependent linear elastic plastic material while the bulk is considered as hyperelastic material using two parameter Mooney–Rivlin strain energy function. This model was implemented in LS-DYNA. The proposed approach could reproduce the fracture mechanisms of the dynamic delamination process reported in the literature and helped in understanding the interaction between the bulk and the interface during the delamination at different strain rates. This approach could be a potential alternative to the cohesive zone method, easing the complexity of simulations involving dynamic delamination in commercial packages.