Finite Element Implementation of an Elastoplastic Constitutive Equation in the Presence of Hydrogen

Abstract

Hydrogen-enhanced localized plastiticity (HELP) is recognized as a viable mechanism of hydrogen embrittlement. A possible way by which the HELP mechanism can bring about macroscopic material failure is through hydrogeninduced cracking. In this work, according to the HELP theory, a constitutive formulation for elastoplasticity model in the presence of hydrogen is presented. To model the local phenomena associated with hydrogen, the local flow stress is considered decreasing with the increasing of hydrogen concentration. Following the previous work, a new module in the open source code ADVENTURE-Solid has been developed by the authors through considering the effect of hydrogen on material softening in microscale, which equips the open source code ADVENTURE-Solid software for studying hydrogen-plasticity interactions. We then combine the ADVENTURE-Solid with an in-house advection diffusion finite element program, to analyze a transient hydrogen diffusion-elastoplastic coupling problem ahead of a crack tip. To validate the new module in the ADVENTURESolid, a set of numerical test cases are presented and discussed. Obtained results show good agreement with previous results.