MATERIAL FAILURE MODELLING IN METALS AT HIGH STRAIN RATES

<p>To account for the physical mechanisms of failure, the concept of thermal activation of damage and failure has been adopted as basis for this material model development. This basic assumption makes the proposed approach compatible with the Mechanical Threshold Stress (MTS) model, which was used as the strength part of the proposed constitutive model. The developments were incorporated into public domain DYNA3D. In order to validate the model, a series of FE simulations of plate impact experiments were performed for OFHC Cu. The numerical analysis results clearly demonstrate the ability of the model to predict the spall process and experimentally observed tensile damage and failure. The model allows simulation of high strain rate deformation processes and dynamic failure in tension for wide range of temperatures. The model is able to reproduce typical longitudinal stress reloading observed in plate impact tests, which is caused by the creation of the internal free surface. Plate impact tests used for model validation were performed on a single-stage gas gun. Longitudinal stresses were measured with stress gauges.</p>