Micro/Nanocrack Propagation and Fatigue Strength Analysis of Gun Barrel

Micro/nanocrack propagation and fatigue strength have a very important effect on metals used in a wide variety of applications, such as household electrical appliances, automobile engine, aerospace propeller, and munitions. In this paper, to analyze the rule of gun barrel micro/nanocrack propagation and the mechanism of fatigue failure, we simplified the gun as thick-walled pressure vessel, established the barrel fatigue analysis model under the impact force of bore pressure, calculated the transverse/longitudinal micro/nanocrack propagation caused by initial defect point and the corresponding fatigue strength of barrel, which were validated by finite element analysis. The results show that the fatigue danger zone of the barrel mainly distributes in the fore and aft ends of barrel, which affects the micro/nanocrack propagation rate and barrel life. The propagation rate of a longitudinal micro/nanocrack in the radial direction is faster than that of the axial direction, and that of an initial micro/nanocrack in the transverse is slower than a micro/nanocrack in the longitudinal direction. Therefore, the process control of initial defects in the fatigue danger zone, especially the composite strengthening of material properties to control the longitudinal initial micro/nanocracks and to alleviate the radial propagation rate of barrel micro/nanocracks, is the way to improve the fatigue life of the barrel. The model also provides a basis for analyzing the cause and mechanism of barrel bulging.