Numerical Study of the Crack-Front Constraint for SENT Specimens of X80 Pipeline Steel

Abstract

This work presents a numerical study of crack-front constraint for SENT specimens of X80 pipeline steel, to examine geometry effect on the correlation of crack-front stress field and constraint. An average measure of constraint over crack-front Am was employed to characterize the crack-front constraint. SENT specimens with varying geometries (different crack depth to specimen width ratio, a/W, and different specimen width and thickness, W/B) were analyzed by Gurson-Tvergaard-Needleman model (GTN model). Results showed that the stress triaxiality Am can characterize the crack-front constraint of X80 pipeline steel very well. The level of the Am-△a curve rises with the decrease of crack depth, and increases first and then decreases with the increase of SENT specimen thickness.