潜水器在下潜过程中其耐压结构大部分区域处于压缩应力状态，所受压力随潜深的改变而改变，将有可能导致耐压球壳发生疲劳破坏，而压-压载荷下的疲劳问题与常规疲劳分析有着很大的不同，因此研究结构的压-压疲劳寿命具有重要意义。本文基于断裂力学理论，采用改进的McEvily裂纹扩展速率模型，预测压缩循环载荷下的深海结构物疲劳寿命。采用有限元方法建立结构模型，研究了裂纹尖端区域有限元单元尺寸的影响，采用多载荷步分析结合节点释放技术计算得到了压缩循环载荷下沿着裂纹扩展平面的残余拉应力和应力强度因子，结合改进的McEvily模型计算得到裂纹扩展寿命曲线。最后，以承受单向循环压缩载荷的双边裂纹板为例，阐述了本文的计算方法，并将计算结果与试验结果进行对比，结果表明本文的压缩疲劳寿命分析方法可行、有效，可为相关承受循环压缩载荷下的结构疲劳寿命评估提供参考。
In the diving process, most parts of the submersible suffer from compressive stress. The pressure changes with the changeable diving depth, which will likely lead to fatigue damage of the spherical shell. It is very necessary to study the fatigue problem under the cyclic compressive loading because it is quite different from the conventional fatigue analysis in mainly tensile stress state. Based on the theory of fracture mechanics, the extended McEvily crack growth rate model is adopted to predict the fatigue life of deep sea structures under compressive cyclic loading. Firstly, with the finite element method, the structure is simulated and the influence of finite element size in the crack tip region is investigated. Secondly, the multi-step analysis combined with the node release technique is used to calculate the residual tensile stress and stress intensity factor along the crack plane under cyclic compressive loading. Then, the crack growth life curve is obtained by the extended McEvily model. Finally, taking a two sided cracked plate under unidirectional cyclic compression for example to illustrate the calculation method and make a comparison between the calculation results and the experiment data. It turns out that the method is feasible and effective, which can provide references for the fatigue life evaluation of structures under cyclic compressive loading.
2018,40(12): 57-63 收稿日期：2017-10-27
DOI：10.3404/j.issn.1672-7649.2018.12.012
分类号：U661.43
基金项目：江苏省自然科学基金（BK20150468）
作者简介：许斐然(1992-),男,硕士研究生,研究方向为船舶与海洋结构物疲劳寿命分析
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