不锈钢管道抗冲击分析应力折减因子研究

Research on Shock Stress Reduction Factor in Shock Stress Evaluation of Stainless Steel Piping

为分析不锈钢管道抗冲击弹塑性设计时应力折减因子的保守裕量,采用自重、内压以及冲击载荷,并运用不同的载荷放大因子及线弹性和弹塑性两种计算方法,分别得到了3种载荷独立作用下不锈钢管道的名义弹性应力和实际塑性应变。通过比较分析结果,发现规范中对冲击载荷引起的应力折减因子取为0.25较为保守,提出冲击载荷的应力折减因子取0.2既能满足规范保守性要求又能降低评定标准的过度保守性。

To study the over conservative margin of shock stress reduction factor in stainless steel piping designed by elasto-plastic rules, a method is used by carrying out elastic and elasto-plastic calculations for stainless steel piping with scaled three kinds of independent loads of gravity, pressure and shock loads, respectively, to obtain nominal stress and actual total strain for manifesting shock load's less damage effect on stainless steel piping. Comparative analysis results show that shock stress reduction factor 0.25 stipulated in shock codes is of conservative margin, and a new value of 0.2 is proposed for elasto-plastic design. Conclusion is that a new shock stress reduction factor of 0.2 by elasto-plastic design can not only meet the code requirements of conservatism but also reduce the over conservative margin in shock stress evaluation.