This paper developed a fatigue crack growth model considering the effects of load interaction and low-velocity impact (LVI) damage. Fatigue crack growth (FCG) accumulative method was established to assess crack growth life of aluminium-alloy thin-sheets with LVI damage under spectrum loading. To validate the proposed model, LVI tests of 7075-T62 aluminium-alloy thin-sheets were conducted, followed by post-impact constant amplitude tension–tension and block spectrum loading FCG tests. Experimental results indicate that there are two competing mechanisms for the effect of LVI damage on the subsequent FCG behaviour of aluminium-alloy thin-sheets. One is the retardation effect on the crack growth rate from the dented plastic zone caused by LVI, and the other is the acceleration effect from the stress concentration due to impact-induced geometric changes. The new FCG model achieves a good agreement with FCG results of post-impact aluminium-alloy thin-sheets and can capture the LVI damage effect, opening an avenue to predict FCG life of aluminium-alloy thin-sheets with LVI damage.

本文开发了一种考虑载荷相互作用和低速冲击 (LVI) 损伤影响的疲劳裂纹扩展模型。建立了疲劳裂纹扩展（FCG）累积法来评估光谱载荷下LVI损伤铝合金薄板的裂纹扩展寿命。为了验证所提出的模型，进行了 7075-T62 铝合金薄板的 LVI 测试，然后进行了冲击后恒幅张力-张力和块谱加载 FCG 测试。实验结果表明，LVI 损伤对铝合金薄板后续 FCG 行为的影响有两种相互竞争的机制。一是LVI引起的凹陷塑性区对裂纹扩展速率的延缓作用，另一个是由于冲击引起的几何变化引起的应力集中的加速效应。新的 FCG 模型与冲击后铝合金薄板的 FCG 结果吻合良好，可以捕捉 LVI 损伤效应，为预测具有 LVI 损伤的铝合金薄板的 FCG 寿命开辟了途径。