A STUDY ON THE IMPROVEMENT OF THE SIMULATION ACCURACY OF DUCTILE FRACTURE MODEL FOR STRUCTURAL STEELS UNDER HIGH STRESS TRIAXIALITY

Abstract

 This study is based on the previous three-stage and two-parameter ductile fracture model proposed by our research group, the equivalent plastic displacement at element failure during simulations is obtained by notched specimen tests, and an improved ductile fracture model is presented considering the effect of high stress triaxiality during both the plastic stage and the softening stage. The relationship between the plastic displacement at element failure and a nonuniform ratio (nonuniform ratio is the ratio of the average value of stress triaxiality of notch tip and center) is determined by a series of tests and analyses. Detailed finite element analyses that employ the improved ductile fracture model are show to predict ductile fracture behavior under high stress triaxiality with good accuracy across the mesh sizes, notch radii, and notch degree in terms of ductile crack initiation point, ultimate load point and load-displacement curve.