A simplified method for calculating surface stress of thick walled cylinder based on numerical calculation method

The maximum compound stress in the thick wall cylinder is usually the key factor that causes the thick wall cylinder to crack. The existing calculation method for stress–strain under thermo-mechanical impact in thick wall cylinder is suitable for stress analysis in the thermo-elastic range. However, the compound stress of the thick wall cylinder under the thermoplastic condition cannot be well analyzed. In this paper, a method to calculate the compound stress of the thick wall cylinder under the effect of thermal–mechanical impact is proposed, based on the finite difference method and the ideal elastic–plastic model and the Mises yield criterion. This method solves the problem of the compound stress calculation to the tube wall under the thermoplastic condition, which change as a result of the combined effect of thermo-mechanical impact. The compound stress in the wall close to the bore surface at different times during shooting is calculated, taking the firing process of a gun as an example. The calculation results well explain the cause of the formation of the crack and the distribution characteristics of the crack in the bore surface.