A COMPARATIVE ANALYSIS OF TWO APPROACHES TO NONLOCAL DUCTILE DAMAGE MODELING

A new nonlocal version of Gurson-Tvergaard-Needleman model is presented, which includes a new scheme of delocalization of constitutive relations. The delocalization scheme has the effect of trapping the damage, which makes it possible to increase the accuracy of modeling the processes of destruction and to avoid excessive diffusion of material damage. As an alternative approach, a nonlocal thermodynamically consistent model of damage accumulation developed earlier is considered. For both models, efficient schemes of integrating constitutive relations are presented. Using the problem of the destruction of a strip with a hole as an example, the results obtained by both models are compared. Despite the fact that the models under consideration are based on fundamentally different hypotheses, the predicted integral characteristics and distributions of plastic strains coincide with high accuracy. The coincidence of the predictions by two different models greatly complicates the choice of model hypotheses based on integral characteristics. It is established, however, that for the two models there is a significant discrepancy in the predictions of the local evolution of the porosity of the material. Thus, in the presence of reliable experimental data on local material damage, this effect can be used as the basis for new protocols for selecting and calibrating models.

Automated summary

This paper presents a new nonlocal version of the Gurson-Tvergaard-Needleman model, which increases modeling accuracy by trapping damage and introduces efficient schemes for integrating constitutive relations. Despite the high accuracy in predicting integral characteristics and plastic strain distributions in both models, there is a significant discrepancy in predicting the local evolution of material porosity.