CTOA of an Extending Crack In a Ductile Material

Abstract

A CTOA resistance curve for mild steel was used to predict rapid crack propagation in a rupturing, subscale and full scale pressurized pipes. A CTOA resistance curve, which has a steady state value of 6°, for 0.8-mm thick 2024-T3 aluminum was also used to propagate cracks in elastic-plastic finite element (FE) models of the fracture specimens and specimens with simulated multiple site damage (MSD). The CTOA of curved crack growth in this thin 2024-T3 scattered between 4° to 8° but the resultant CTOD, which is the vector sum of the mode-I COD and the mode-II crack sliding displacement (CSD), remained a constant 0.16 mm. The CTOA of a rapidly propagating crack in 1.6-mm thick, 7075-T6 SEN specimens increased from 4.5° at a low crack velocity to a constant 7° at a higher and the terminal crack velocity.