Probabilistic Fracture Mechanics Analysis to Critical Crack Size of Autofrettaged Gun Barrel
Chen Aijun,Cha Zichu
(School of Science, Nanjing University of Science and Technology, Nanjing 210094 )

Abstract: Based on probabilistic fracture mechanics theory and Monte Carlo simulation, a reliability analysis method for critical crack size of autofrettaged gun barrel is proposed, where the form of fatigue cracks in bore of autofrettaged gun barrel are considered as semi-elliptical cracks, and the stress intensity factors at the tip of crack are considered the sum of SIF under internal pressure and autofrettaged residual stress. The autofrettaged residual stress solution is suitable for gun barrel made of steel with strain hardening and bauschinger effect. The stress intensity factor under the autofrettaged residual stress is calculated with weight function method. According to fracture criterion, critical crack size of autofrettaged gun barrel is calculated. An evaluated example shows that lognormal distribution is the optimum for the sample of critical crack size, critical crack size of autofrettaged gun barrel under the conditions of differ ent reliablities and confidences are given.
Keywords: critical crack size, probabilistic fracture mechanics, autofrettaged gun barrel, monte carlo simulation, reliability.