对于复杂载荷作用下的船舶及海洋工程结构物,至今仍没有一个统一的疲劳寿命预报模型能够很好地解释载荷次序效应的影响.单峰过载下的疲劳裂纹扩展问题是研究变幅载荷疲劳问题的基础,伴随单峰过载将出现疲劳裂纹扩展迟滞现象.课题组所提出的广义疲劳裂纹扩展模型能够定量地预报出过载迟滞这一现象,通过确定过载参数β的大小,能够有效地衡量出过载迟滞的程度.在此基础上,文章将广义的疲劳裂纹扩展模型进行了进一步的修正,通过引入一个幂指数项,使得模型能够更好地反映出过载后疲劳裂纹扩展速率由迟滞的最低点逐渐恢复到过载前的水平.文中将课题组所发展的广义疲劳裂纹扩展率模型应用于实际的单峰过载疲劳问题中,并引用铝合金D16Cz的单峰过载试验数据与模型预报结果进行了比较,结果发现,经修正的广义疲劳裂纹扩展模型能够更好地反映出单峰过载后的疲劳裂纹扩展情况.%For Marine structures such as ships and offshore platforms there is still no uniform model on the fatigue life prediction considering the load sequence effect. In this paper, the general fatigue crack growth model developed in author's group is employed to study the single overload fatigue problem. The experimental data of the aluminium alloy D16Cz is adopted for this study. Prediction results show that the general model can qualitatively predict the overload retardation phenomenon; the overload parameter β is efficient in evaluating the overload retardation.This general model is further developed by introducing a power item to predict the crack growth rate during the period of crack growth recovering to the level before overload from retardation.The general fatigue crack growth model is applied to the single overload fatigue problem and the predicted results are com-pared with the experimental data of an alluminimun alloy D16Cz.
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