超高压容器典型裂纹自由表面处应力强度因子的计算方法改进OA

The stress intensity factor at the free surface is a core calculation parameter in the typical crack propagation and life prediction process of ultra-high-pressure vessels.Based on the segmented linear interpola-tion method,an improved method based on high-order polynomial fitting calculation was proposed.With blind bottom cracks as an example,stress data under different collected data volumes were fitted by means of poly-nomials of different orders;The stress intensity factors at the free surface of different cracks was calculated with this method,and the effects of polynomial orders and data amounts on the calculation results were ex-plored;At different crack depth to length ratios,the differences between this method and the recommended lin-ear interpolation method in previous literatures and the finite element method,were compared and analyzed.The results indicate that,as the polynomial order increases,the calculation results show a gradually approac-hing and converging trend.The minimum relative error of the calculation results for conventional cubic and high-order polynomial fitting is about-30%;As the collected data amount continues to increase,the calcula-tion results gradually converge towards a stable value.Comparison of calculation results between the cases with less and more data shows that,the maximum relative error can reach about 11%.This method,with its calcula-tion results,is basically consistent with the linear interpolation method in the previous literatures and the finite element method,and is suitable for dynamic crack propagation and life prediction processes.