Residual Stress Analysis Of Autofrettage Tube And Its Effect On Crack Damage

The gun barrel adopts autofrettage technology to produce residual stress in the inner wall of barrel,and use the residual stress to improve the bearing capacity of barrel,reduce the weight of barrel and improve the stress of barrel.Stable residual stress plays a positive role in improving the strength and fatigue life of the barrel,inhibiting the crack propagation and improving the safety of the barrel.In this paper,based on the elastic-plastic theory of thick wall cylinder,the residual stress distribution of barrel under different autofrettage and different Bauschinger effect coefficient are calculated.The autofrettage stress state of barrel is simulated by finite element software.The direct coupling method of thermal pressure coupling is used to simulate the autofrettage stress state of barrel According to the shooting situation of the barrel,the variation law of the residual stress of the barrel with the number of projectiles is analyzed,and the influence on the strength of the barrel is further analyzed.The barrel is modeled by using the three-dimensional modeling software,and based on the extended finite element method,the cracks are prefabricated on the inner wall of the barrel,and the working load is applied to analyze the stress intensity factor of the crack tip and the crack propagation.The result of research shows that the larger the autofrettage is,the larger the residual stress of the inner wall is;the residual stress has a restraining effect on the crack growth;the residual stress in the autofrettage barrel decreases with the increase of the number of projectiles,and the decrease of residual stress leads to the crack growth,that is,the crack gradually expands with the increase of the number of projectiles.