Research on Crack Propagation Law of Rifle in Gun Barrel Under Cyclic Impact Load

After several rounds of cyclic firing, obvious cracks appear in the rifling area of the gun barrel, especially at the edges of the male line, where there are many corner cracks distributed. The crack propagation has a significant impact on the barrel life. Therefore, it is necessary to study the law of corner crack propagation for mastering the mechanism of the influence on the barrel life. According to the endoscope observation of the barrel with different firing counts, the corner cracks at the edges of the barrel’s male line germinated earlier. A finite element model for crack propagation was established considering the single and coupling effects of impact loads such as bore pressure, belt crush friction, and temperature, for the initial angular cracks at the edges of the male line. The degree of influence of different load factors on crack growth was obtained, and the main causes of crack growth were identified. Under the coupling action, as the crack propagates, the stress intensity factor first increases and then decreases, and is smaller than the fracture toughness of the material. This provides theoretical support for revealing the mechanism of crack propagation.