The opening stress and the life of crack growth is calculated and compared with the test results and the experience formula . the feasibility of the newman theory of opening stress used in the high strength steel is validated . then through the slice synthesis method , the three dimension surface crack of the weld joint of cone - cylinder is decomposed into many plane through cracks 本文将基于裂纹闭合现象建立的带状屈服模型，用在平面贯穿裂纹中，计算此时的裂纹张开应力和疲劳裂纹扩展寿命，与试验结果和经验公式比较，验证newman裂纹张开应力理论在高强钢中的可行性；然后，用切片合成法，把潜艇结构凸锥柱结合壳焊缝处的三维表面裂纹分解成平面贯穿裂纹，用带状屈服模型的理论来分析平面贯穿裂纹，得到裂纹沿深度方向的扩展速率，进而得到潜艇结构的疲劳寿命。
