The relative importance of crack closure and residual stresses on fatigue crack growth (FCG), which is controversial, is studied here. FCG is predicted numerically in CT specimens of Ti-6Al-4V alloy submitted to single overloads, assuming that crack tip plastic strain is the driving force. The numerical procedure, which includes the effects of crack tip blunting, material hardening, crack closure and partial crack closure, was found to be very robust and to give correct trends. The high strength material studied showed relatively small overload affected zones (<0.5 mm), which is even more pronounced under plane strain conditions. The comparison of numerical results with and without contact of crack flanks showed that crack closure is responsible for the effect of overloads on FCG rate behaviour, while the effect of residual stresses is not relevant for the material studied. The transient behaviour obtained after an overload is unattainable without considering the contact of the crack flanks.

这里研究了裂纹闭合和残余应力对疲劳裂纹扩展 (FCG) 的相对重要性，这是有争议的。假设裂纹尖端塑性应变是驱动力，在承受单一过载的 Ti-6Al-4V 合金 CT 试样中，FCG 是数值预测的。数值程序，包括裂纹尖端钝化、材料硬化、裂纹闭合和部分裂纹闭合的影响，被发现非常稳健并给出了正确的趋势。所研究的高强度材料显示出相对较小的过载影响区 (<0.5 mm)，这在平面应变条件下更为明显。有和没有裂纹侧面接触的数值结果的比较表明，裂纹闭合是过载对 FCG 速率行为影响的原因，而残余应力的影响与所研究的材料无关。如果不考虑裂纹侧面的接触，则无法获得过载后的瞬态行为。