Abstract Tests are used to verify the hypothesis “the fatigue crack growth (FCG) driving force is the effective stress intensity factor range ΔKeff″. The tests are performed measuring FCG rates in steel and aluminum C(T) and DC(T) specimens under fixed {ΔK, Kmax} loading conditions and during FCG delays induced by single overloads. Crack-opening loads Pop are redundantly measured along the crack path in all tests, using independent near and far field strain-gages, as well as Digital Image Correlation (DIC) techniques. Finally, elastoplastic strain loops within the reverse plastic zone ahead of crack tips are measured using a stereo microscope DIC system.

中文翻译：

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挑战“ΔK 是疲劳裂纹扩展的驱动力”假设

摘要 通过试验验证了“疲劳裂纹扩展（FCG）驱动力是有效应力强度因子范围ΔKeff”的假设。这些测试是在固定 {ΔK, Kmax} 负载条件下以及在由单个过载引起的 FCG 延迟期间测量钢和铝 C(T) 和 DC(T) 试样的 FCG 速率进行的。在所有测试中，使用独立的近场和远场应变计以及数字图像相关 (DIC) 技术，沿裂纹路径冗余测量开裂载荷 Pop。最后，使用立体显微镜 DIC 系统测量裂纹尖端前反向塑性区内的弹塑性应变环。