考虑残余应力效应的深潜器耐压壳体疲劳研究

本文考虑焊接残余应力的影响,给出包含裂纹萌生和裂纹扩展全过程的载人深潜器耐压球壳疲劳寿命预报方法,分别基于局部应力-应变法和能计及负应力比效应的裂纹扩展单一曲线模型预报了耐压球壳的工艺疲劳寿命和使用疲劳寿命,研究焊接残余应力大小对球壳疲劳寿命的影响。结果表明,忽略拉伸残余应力的影响将导致疲劳寿命预测结果偏于危险;耐压球壳整体受压时,拉伸残余应力使得球壳局部区域承受拉-压循环载荷,计算使用疲劳寿命过程中须考虑其影响;降低拉伸残余应力可有效提高耐压球壳的疲劳寿命。

Fatigue analysis of spherical shell considering residual stress

In this paper, fatigue analysis is carried out considering welding residual stress for spherical shell of manned submersible based on local stress-strain method and unique curve model which could take negative stress ratio into account, and the influence of welding residual stress is discussed. Results show that fatigue life prediction result will be insecure if the influence of tensile residual stress was omitted. Tensile residual stress makes spherical shell under pressure suffer tensile-compressive cyclic load, thus must be taken into consideration when predicting fatigue life of spherical shell using crack propagation method. Fatigue life could be improved significantly by reducing tensile residual stress.