Non-local phenomenological damage-mechanics-based modeling of the Drop-Weight Tear Test

We modify the Xue-Wierzbicki damage mechanics model to include strain rate effects, implement it in an explicit finite element code and use it to model the dynamic response and failure of X70 pipe steel in the Drop-Weight Tear Test (DWTT). The damage evolution depends on Lode angle, hydrostatic pressure, and strain rate. Strength of the steel is assumed to depend on strain hardening, strain rate and thermal softening. To mitigate the expected mesh dependence of results, we use the non-local integral formulation due to Bazant and Pijaudier-Cabot. A highlight of the computational results is the ability to model the fracture mode transition between impact and static loading: slant fracture for impact loading and flat fracture for static loading of the DWTT specimen. Furthermore, the measured experimental force-displacement curves are in excellent agreement with the computed curves. We estimate the Crack Tip Opening Angle and compare with experimental measurements. Our results also provide insight into the influence of the Lode-angle-dependent damage evolution on modeling slant fracture. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.