随机载荷作用下的疲劳裂纹扩展

船舶等许多工程结构在服役过程中的受载荷历程是一个随机过程.而变幅载荷下的载荷相互作用对疲劳裂纹扩展寿命将产生显著的影响.因此研究随机载荷作用下的裂纹扩展及定量计算对船舶结构的疲劳寿命预测的可靠性是十分重要的.该文提出了一个基于有效应力强度因子,以应力比和裂纹尖端塑性区尺寸为主要参数的随机载荷作用下疲劳寿命预测模型.该模型用于预测几种载荷谱作用下的裂纹扩展试验,结果表明预测结构和实验结果符合得很好.

Fatigue Crack Growth under Random Loading

Many engineering structures such as ship structures are subjected to random loading in service.The load cycle interactions can have a very significant effect on fatigue crack growth under variable amplitude loading.Study of fatigue crack growth law and fatigue life calculation methods under random loading is very important for the reliable life prediction of ship structures.In this paper,a fatigue life prediction model under random loading,taking the stress ratio and the plastic size near crack tip as main parameters in calculation of effective stress intensity factor range,was proposed.Several cases of fatigue crack growth tests under various spectral loadings were predicted by the present model.The results show that the predicted results are in good agreement with the test data.