A Hydrocode Material Model for Concrete

Abstract

In order to predict the behavior of concrete structures under impulsive loading it is not only essential to be able to model the dynamic strength and other strain rate dependent properties of the material, but also to describe realistically the damage and the softening process of the material. Various material models representing different phenomena of the response of concrete to high dynamic loads have already been developed. However, concrete modeling, especially damage modeling, is still far from completion. This paper presents an enhanced material model (HPG) for the simulation of concrete subjected to high dynamic loads. It combines existing approaches from different material models and new formulations for the dynamic strength increase, damage and degradation. The model is based on static material behavior and extends it to the high dynamic range. The formulations for yield surface, plastic hardening and strain rate dependency are presented and the damage and degradation models are explained in detail. The model was implemented in the commercial hydrocode Autodyn and validated both by contact detonation and large caliber impact tests.

A comparison of numerical modelling strategies in contact detonation scenarios with concrete targets

“…The first strategy is the common approach to model contact detonation problems used, for instance, in [28][29][30][31]. This classical approach models fluids in an Eulerian mesh and solids in a Lagrangian mesh.…”

“…The erosion strain limit is commonly defined by experience [31] and it is usually taken above 1.5 [12]. A disadvantage of this unphysical numerical technique is that mass and energy of eroded elements are lost.…”

“…Other material models (e.g. [22]) define a different damage variable which combines both sources of damage.…”

“…This approach was proposed in [31] for their own developed material model, where the damage variable is computed differently. This approach is not employed in the present contribution (using the RHT material model) since the outcome of such procedure depends critically on the chosen threshold.…”

“…As such, numerous material models have been conceived in hydrocodes to describe the behaviour of concrete subjected to high deformations, damage, and failure (e.g. [17][18][19][20][21][22]). A material model for concrete which was especially designed for the high dynamic loading regime and implemented in ANSYS Autodyn is the RHT material model [19,23,24].…”