The failure analysis of the star-separator of an aircraft cannon

• The failure of the star-separator is the result of low-cycle fatigue phenomenon.
• The crack was initiated at the multi origin points on the surface layer.
• The propagation of the crack occurs under the influence of contact stress state.

This paper analyzes the causes of fracture of the double pipe aerial cannon stellate star-separator, which occurred during the fighting plane mission. The linear finite element method (FEM) is used to determine the stresses that the star-shaped star-separator is subjected to during the grenade belts withdrawal and introduction into the bearing tube during gun action and under finite load, which resulted in high strains concentration of the star-separator’s parts pulling the gun belt links.Therefore, in this paper we are particularly focusing on the static and dynamic behavior and the fatigue behavior of the star-separator which is an integral part of the cannon fire shutter mechanism used for the belt’s withdrawal. In this study, the techniques such as numerical analysis, hardness measurement and fractographic examination were used. The testing results showed that the peel and longitudinal cracks started from the low-cycle fatigue and wear of the surface material in the thinnest area of the star-separator tooth, but without influence of the stress load.