Ductile Fracture Analysis of High-strength Steel Bars Using Micromechanical GTN Model

Recent studies on the mechanics of materials have shown that the ductile fracture is signi cantly a ected by the stress invariants among progressive plastic deformation. In this paper the micro-mechanical Gurson-Tvergaard- Needleman (GTN) model is utilized to investigate the fracture behavior of high-strength steel AISI 4340 under various stress triaxialities. Experimental tensile tests were conducted on the smooth and notched round-bar specimens to evaluate the e ect of the stress triaxiality on the fracture initiation. Subsequently, nite element (FE) simulations were implemented using Abaqus/Explicit via the user subroutine VUMAT. The comparison between the simulations and experimental results indicate the best accuracy of the GTN micromechanical model to appraise the ductile fracture initiation. Furthermore, the results demonstrate the signi cant e ect of the stress triaxiality value on the start of the ductile rupture.