Analysis Of Stress State On Autofrettaged Barrel Of Small Caliber Artillery

The barrel autofrettage technology is to make the barrel produce the corresponding residual stress by exerting certain pressure in the bore of barrel,Which can improve the barrel's stress situation in the use process and prolong the service life of the barrel.Most of the existing studies on autofrettaged barrel are aimed at large caliber gun barrel and simplify the barrel into a thick-walled cylinder model,ignoring the factors of rifling and chromium plating,and the effects of impact load on barrel and the crack on inner stress of barrel are also ignored.In view of the above problems,this paper taking a small caliber gun barrel as the research object,compares the theoretical calculation with the finite element simulation,and simulates the process of rifling and chromium plating.The main research contents are as follows:(1)For a new gun steel,the autofrettage pressure and residual stress of autofrettaged barrel are calculated by theoretical calculation and simulated by numerical simulation.The model independence is verified by numerical simulation.The differences and causes between theoretical calculation and numerical simulation in autofrettage process are analyzed and compared.(2)The influence of processing of barrel bore on the residual stress of autofrettage is analyzed by simulation of autofrettaged barrel including rifling and coating processing.In addition,the influence of different autofrettage processing sequence on the residual stress of barrel is studied by finite element simulation.(3)By analyzing the thermal-pressure coupling impact load of barrel during launching,the autofrettaged barrel was simulated through thermal-pressure coupling numerical simulation at maximum bore pressure surface.And the stress state and residual stress variation law of autofrettaged barrel at different positions during single and continuous launching were analyzed.(4)The extended finite element method is used to simulate the different pre-fabricated cracks at the interface between steel and chromium in autofrettaged barrel.The J-integral variation of cracks,the influence of autofrettage degree on J-integral of cracks,the effect of cracks on the residual stress and the trend of crack propagation are analyzed.