A comparative study and ABAQUS implementation of conventional and localizing gradient enhanced damage models

The conventional gradient models based on continuum damage mechanics are found to exhibit inconsistencies in terms of damage initiation and growth. With the decrease in non-local interactions, localizing gradient damage model describes the failure phenomena in a physically meaningful manner. In the present study, both conventional and localizing gradient damage models are implemented in the commercial finite element package ABAQUS through user subroutines. The motivation behind the implementation is the popularity and computational efficiency of the ABAQUS. It is demonstrated through various numerical examples that the localizing gradient damage model is more effective and efficient than the conventional gradient damage model. A detailed stress oscillation study is carried out to provide more insight on the localizing gradient damage model. A new approach is proposed for an implicit representation of initial notch/crack in the gradient damage models. The enhanced capability of the present implementation is demonstrated by solving the problems with complicated geometry under complex loading. A detailed description of the working of the user subroutines (UEL and UMAT) and other associated activities is elucidated. The source codes of the present implementation are provided for better understanding and further development. •Enhanced capability, effectiveness and efficiency of the localizing gradient damage model is demonstrated.•A detailed description of the working of subroutines files UEL and UMAT in ABAQUS is presented.•A detailed stress oscillation study is performed for in-depth understanding of the localizing gradient damage model.•Implicit representation of initial crack is implemented and validated with the explicit representation.•Capability of the present implementation to model complicated geometries is demonstrated.