液压自紧炮身(半精加工)的应力与强度

The Stress and Strength of the Hydraulically Autofretted Gun Barrel (Semi-Finished)

本文研究的对象是开端液压自紧圆筒(Ni-Cr钢)。用考虑材料应变硬化的最简单解法计算加压过程中圆筒的应力分布及内压-外表面应变关系。将材料单向拉伸-压缩曲线中的鲍兴格效应线性化;以圆筒塑性区中的切向应变代替相当应变,求卸压过程应力变化及内压-外表面应变关系的解。进而可由加压与卸压两个过程应力分布的代数和求残余应力。由于上述近似计算,所以这种解是最简单的。文中用试验和理论分析验证了这种近似的合理性,并用自紧过程内压-外表面应变的实际测定和自紧圆筒残余应力的测定证明这种理论解有相当满意的准确性。在上述残余应力理论分析的基础上,本文初步探讨了液压自紧炮身强度设计和自紧工艺参数设计的有关问题。

The object of this study is the open-end, hydraulically-autofretted, thickwalled cylinders(Ni-Cr steels). The simplest solution which considers strainhardening of material is used to calculate the stress distribution of the cylinders and internal pressure-external strain relations during loading. The Bauschinger effect curve in the uniaxial tension-compression test of the material is approached by linear-hardening. The equivalent strain in the cylinder plastic region is replaced by the circumferential strain. Then the stress variation and internal pressure-external strain relation during unloading are solved and the residual stress is predicted from the algebraic sum of stress distribution during loading and unloading. These solutions are simple as the above-mentioned approximations are applied. The rationality of these approximations is verified by the test and theoretical analysis in this paper and the real determinations of the internal pressure-external strain relation and the autofretted cylinder residual stress have proved that the accuracy these theoretical solutions possess is considerably satisfactory.Based on the theoretical analysis of the residual stress, the strength design of the hydraulically-autofretted gun barrel and the design of the process parameters in autofrettage are preliminarily explored.