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导致加载序列作用的加载历史极大地影响着变幅加载下的疲劳裂纹扩展行为。本研究完成了一个恒幅及简单变幅加载历程下的探索性试验研究计划,以进一步了解序列影响并提供一个评价和改进现有裂纹扩展预测方法的基础。本研究的第一部分是进行宽范围应力比下的恒幅裂纹扩展试验。试验结果以及试验期间断口型态的转变可以在有效应力强度因子范围△Keff 的基础上来表示。第二部分是进行系统变化高载、低载以及卸载的简单序列下的裂纹扩展试验,测量裂纹扩展行为。最后提出关于预测模型的进一步发展的一般性看法。
The loading history leading to the loading sequence greatly influences the fatigue crack growth behavior under luffing loading. This study completed an exploratory pilot project under constant amplitude and simple luffing loading to further understand the sequence impact and provide a basis for evaluating and improving existing crack propagation prediction methods. The first part of this study is a constant amplitude crack propagation test at a wide range of stress ratios. The results of the test and the change in fracture pattern during the test can be expressed on the basis of the effective stress intensity factor, Δ Keff. The second part is the crack propagation test under the simple sequence of system change high load, low load and unload to measure the crack propagation behavior. Finally, a general view is given on the further development of the forecasting model.