Numerical investigation of constraint effects on ductile fracture in tensile specimens

• Published in: Journal of the Brazilian Society of Mechanical Sciences and Engineering 2004-06, Vol.26 (2), p.190-199
• Main Author: Ruggieri, C.
• Format: Article
• Language: English
• Subjects: ENGINEERING, MECHANICAL
• ISSN: 1678-5878; 1806-3691
• DOI: 10.1590/S1678-58782004000200011

This study explores the capabilities of a computational cell framework into a 3-D setting to model ductile fracture behavior in tensile specimens. The cell methodology provides a convenient approach for ductile crack extension suitable for large scale numerical analyses which includes a damage criterion and a microstructural length scale over which damage occurs. Laboratory testing of a high strength structural steel provides the experimental stress-strain data for round bar and circumferentially notched tensile specimens to calibrate the cell model parameters for the material. The present work applies the cell methodology using two damage criterion to describe ductile fracture in tensile specimens: (1) the Gurson-Tvergaard (GT) constitutive model for the softening of material and (2) the stress-modified, critical strain (SMCS) criterion for void coalescence. The present work first applies the cell methodology to investigate effects of constraint (stress triaxiality) on ductile crack initiation of notched tensile specimens. An application also follows to determine the dependence of ductility on stress triaxiality for the tested steel. These exploratory 3-D studies using computational cells clearly demonstrate its capability to predict the strong effects of constraint on measured stress-strain response for tensile specimens.