MULTISCALE STRAIN LOCALIZATION MODELING IN THE GURSON-TVERGAARD-NEEDLEMAN PLASTICITY MODEL

The modeling of strain localization requires the use of different scales to describe the evolution of the material of the overall structure and the material inside the localized region. Focusing on the Gurson-Tvergaard-Needleman material we develop a multiscale formulation that uses strong discontinuity modes to model the development of a localization zone and the material degradation and void growth inside it. We present a strong discontinuity mode formulation able to capture the band kinematics that consists of a combination of sliding and opening modes. Then we derive an heuristic inter-scale factor to set a proper connection between the localized and the continuum scales. This approach describes the evolution of the accumulated plastic strain and the void content inside and outside the localization band. The localization scale evolution is effectively controlled by the proposed heuristic rule. To illustrate on the formulation capabilities, a test case is presented and the behavior of the inter-scale connection factor is analyzed. The resulting formulation does not require a specific mesh refinement to model strain localization, provides mesh independent results and can be calibrated using experimental results.