环向缠绕气瓶金属内胆表面裂纹的应力强度因子计算

Calculation of Stress Intensity Factor for the Surface Crack in the Metallic Liner of Hoop-wrapped Cylinder

本文利用弹塑性理论对环向缠绕气瓶自紧及服役工况进行应力分析,推导得出不同工况下,气瓶的复合材料和内胆的应力、应变计算公式,并展开讨论。以金属内胆应力计算公式为基础,借鉴平板椭圆形表面裂纹应力强度因子公式,给出了金属内胆表面椭圆形裂纹应力强度因子的计算方法。通过算例表明,内胆裂纹的应力强度因子除与裂纹几何参量、气瓶内压相关,还与气瓶制造时自紧工艺相关,同一气瓶设计,最小、最大自紧引起的应力强度因子相差36%。

By using the elastic-plastic theory, the stress and strain formulas of the hoop-wrapped cylinder are deduced for the auto-frettage and service conditions. Base on the results, the formula for calculating the stress intensity factor for the surface crack in the metallic liner is introduced. The calculation results show that the stress intensity factor of the metallic liner is related to the crack geometry, the internal pressure and the self-tightening pressure when the cylinder is manufactured. For the same design, there is a 36% difference of the stress intensity factor caused by the auto-frettage process.