变幅载荷下材料的疲劳裂纹扩展行为

FATIGUE CRACK PROPAGATION BEHAVIORS OF STRUCTURAL MATERIALS UNDER VARIABLE AMPLITUDE LOADING

本文对在北京航空材料所和西德宇航院材料所进行的有关在变幅载荷下几种飞机结构材料的疲劳裂纹扩展行为及其寿命预测方法进行了评述。文中报道了铝和钛合金在不同类型超载下的迟滞效应与扩展机制,对7475-T7351铝合金在系统变化高、低载和卸载的序列下的裂纹扩展试验结果也进行了阐述。最后对寿命预测模型,线性累积法、恒Sop模型和改进后模型的预测结果与实测数据进行了对比和讨论。

Investigationsn the crack propagation behavior and its life prediction methods under variable amplitude loading histories, condueted in BIAM and DFVLR, is presented. The mechanism of fatigue crack growth retardation effect for Al and Ti alloys under various modes and sequence of overloads was descrided. Test with systematically varied sequence of high load, low load and underload for a 7475-T735 Al alloy were perfomed and the crack propagaton behavior was studied. Fractographic analyses were conducted to obtain a detail view of the crack growth increments per cyele. The results of the application of a linear accumulation method, a constant Sop model and a modified model proposed by the authors for life prediction under variable amplitude loading are discussed.