提出了一个对传统线性疲劳累积损伤理论的修正方案，使低于疲劳极限的应力对疲劳损伤有一定贡献且呈非线性减少。实际零件的分级程序载荷试验表明，该理论对估算低应力级占有绝大多数循环次数的谱载荷下零件寿命是有效的 A modified scheme of traditional linear fatigue cumulative damage theory is proposed, in which stress below the fatigue limit contributes to the fatigue damage and decreases nonlinearly. The fractional program load tests of the actual parts show that this theory is effective for estimating part life under spectral loading, which accounts for the vast majority of cycles at low stress levels