This paper addresses the mechanistic drivers of short fatigue crack growth using theory, computational crystal plasticity and experimental test and characterisation. The asymptotic theory shows that the crack tip stored energy density is non-singular and finite and can be related to stress intensity, but unlike the latter, it depends on the crystal Burgers vector and intrinsic slip strength. The computational methods allow the stored energy to be calculated accurately at crack tips and show that good agreement is obtained for static cracks with the theory. The experiments allow the crack tip stored energy to be measured, demonstrating intimate microstructural sensitivity, direct correlation with experimental crack growth variations and good quantitative agreement with both asymptotic theory and computational modelling. Hence a new microstructurally-sensitive fracture mechanics has been presented in the context of short cracks within crystalline materials.

本文使用理论，计算晶体可塑性以及实验测试和表征来探讨短疲劳裂纹扩展的机械驱动力。渐近理论表明，裂纹尖端存储的能量密度不是奇异且有限的，并且可能与应力强度有关，但与后者不同，它取决于晶体Burgers向量和固有滑动强度。该计算方法允许在裂纹尖端精确地计算出存储的能量，并且表明该理论与静态裂纹具有良好的一致性。实验允许测量裂纹尖端的储能，证明了紧密的微观结构敏感性，与实验裂纹扩展变化的直接相关性以及与渐近理论和计算模型的良好定量一致性。