Crack initiation and propagation from geometric microdefects: Experiment and transition fatigue behavior. Issue 9 (10th May 2021)

• Record Type: Journal Article
• Authors: Tang, Keke; Du, Zhaojun; Ferro, Paolo; Berto, Filippo
• Is Part Of: Fatigue & fracture of engineering materials & structures. Volume 44:Issue 9(2021)
• Page Start: 2323
• Page End: 2336
• Publication Date: 2021-05-10
• Subjects: geometric microdefect -- grain size variation -- multiscale model -- short fatigue crack initiation and propagation -- transition factor; Materials -- Fatigue -- Periodicals; Fracture mechanics -- Periodicals; 620.1123
• DOI: 10.1111/ffe.13492
• Languages: English
• ISSNs: 8756-758X

Abstract

Abstract: The present work aims to study short fatigue crack initiation and propagation induced by geometric microdefects. An empirical approach is used to evaluate the microstructural influences on crack growth behavior. Small fatigue crack test on titanium alloy Ti‐6Al‐4V is performed to investigate the crack induced from a geometric microdefect. Analyses on crack initiation and fracture are respectively performed to study the microstructural influences on the stages of initiation and fracture. Subsequently, an empirical multiscale model is employed to predict the short fatigue crack propagation of alloys underlining the transition features. Grain size variation is adopted to reflect the main microstructural contribution to the short crack propagation. An alpha factor is defined to demonstrate the transition interim from microstructurally short crack to physically short crack stages. Furthermore, a relationship between transition factor and grain size is correlated. The results indicate that the value of transition factor tends to decrease with the augment of average grain size. The empirical approach is validated through a variety of fatigue experimental data of alloys including Ti‐6Al‐4V, 2024‐T3, and GH4169.