A detailed comparison of two material models for concrete in the dynamic loading regime, RHT and HPG

Abstract

Throughout the last decades, great attention has been given to model the dynamic behaviour of concrete. As such, numerous material models have been conceived in hydrocodes to describe the complex behaviour of this composite material subjected to large deformations leading to damage and failure. Concrete shows, for instance, strain rate dependency as well as hydrostatic pressure dependency. This article focuses on the comparison of two material models conceived for such purpose. These are the RHT model (RHT - Riedel, Hiermaier, Thoma) developed at the Fraunhofer Ernst-Mach-Institut and the HPG (HPG - Hartmann, Pietzsch, Gebbeken) model developed at the University of the Bundeswehr Munich, both of which have been proven to be successful in a variety of scenarios. They are macro-level models, i.e., they regard concrete as a homogeneous material. Both models incorporate the traditional splitting in hydrocodes of the hydrostatic and the deviatoric response. On the one hand, both material models have three pressure-dependent limit surfaces in the stress space to characterise concrete strength. These are the elastic limit surface, the failure surface and the residual strength surface, the latter being related to a damage model. Strain rate effects are inherent in the models. On the other hand, both material models use the p–α formulation in the Mie–Grüneisen equation of state. The parameters of this equation are, however, differently calculated. A final comparison of these two models is done by conducting numerical simulations where the RHT and the HPG models are used as material models. The scenario is a contact detonation as an example of a high strain rate problem. Such an in-depth and detailed comparison has not been done to date. It aims to help the user decide which material model to choose as well as to provide ideas for future development in the field of material modelling.