A Geometric Phase-Field Model for Hydrogen-Enhanced Decohesion in Porous Ductile Metals

Abstract

Abstract. A finite strain, multi-field model for hydrogen embrittlement in porous ductile metals is presented, based on a geometric phase-field approach applied on the Gurson–Tvergaard–Needleman model. The hydrogen-enhanced decohesion mechanism is incorporated by augmenting the damage-driving force with a Rankine-type, hydrogen-dependent term governed by the maximum principal stress. This allows the model to capture both ductile and brittle fracture modes, as well as the transition between them. The phase-field formulation introduces an intrinsic length scale that regularizes the solution and eliminates mesh dependency. To address volumetric locking, a mixed finite element formulation with pressure variation is employed. The model successfully captures key experimental observations, including the strain-rate dependence of tensile failure, the transition from internal to surface fracture with increasing deformation rate, and the significant reduction in fracture toughness under hydrogen exposure.