Numerical simulation for studying constraint effect on ductile fracture initiation using complete Gurson model

Abstract

Ductile fracture initiation in high-strength low alloyed welded steel joints is predicted using micromechanical complete Gurson model (CGM). The crack tip constraint and variation of stress triaxiality in ligament are considered on single-edge notch bend SE(B) and compact tension C(T) specimens, including the effect of strength mismatching and different weld metal width. According to the analysis of stress triaxiality in front of the crack tip, transferability of fracture initiation parameter was studied. As a result of the analyses on specimens, fracture initiation parameter determined by using CGM can be transferred from one geometry to another if their triaxial conditions are found to be similar.

Nastanak žilavog loma u zavarenim spojevima niskolegiranog čelika povišene čvrstoće je predviđen primenom mikromehaničkog kompletnog Gursonovog modela (CGM). Ograničeno deformisanje oko vrha prsline (eng. 'constraint') i promena troosnosti napona u ligamentu su razmatrani na epruvetama za savijanje u tri tačke SE(B) i na kompaktnim epruvetama za zatezanje C(T), uzimajući u obzir uticaj razlike u mehaničkim osobinama (eng. 'mismatch') i širine metala šava. Analizirana je prenosivost parametra koji odgovara nastanku prsline, u zavisnosti od troosnosti napona ispred njenog vrha i zaključeno je da se dobijene vrednosti korišćenog parametra mogu koristiti za obe geometrije razmatrane u radu.