Koko, A; Sheen, B; Green, C; Dunne, F (2026) In situ elucidation of fracture mechanisms governing crack transition to plasticity arrest. International Journal of Mechanical Sciences, 321. 111668 ISSN 00207403

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Abstract

Crack arrest in ductile alloys plays a critical role in damage-tolerant design for aerospace and structural applications, yet the transition from microstructure-sensitive short cracks to load-controlled long cracks remains poorly understood. Here, we present an in-situ, high-resolution experimental study of crack propagation in cold-worked AA-5052 aluminium alloy using scanning electron microscopy digital image correlation (SEM-DIC) and electron backscatter diffraction. Local mode I and II stress intensity factors, and the J-integral, were extracted from DIC-measured displacement fields and correlated with the crack interaction with microstructural features. We find that the crack grows at low-stress intensity and propagates through plastically deformed regions until reaching a critical J-integral, where crack growth ceases and a blunted crack tip form, marking a transition from elastically-driven microstructure-sensitive crack propagation to plasticity-dominated crack arrest. Our findings establish a mechanistic criterion for crack arrest in ductile alloys and provide a new framework for designing materials with intrinsic resistance to fracture.

Item Type:	Article
Keywords:	Fracture mechanics; Elastoplastic deformation; Crack propagation; Process zone evolution; Energy release rate; SEM-based digital image correlation
Subjects:	Advanced Materials > Metals and Alloys
Identification number/DOI:	10.1016/j.ijmecsci.2026.111668
Last Modified:	17 Sep 2026 13:53
URI:	https://eprintspublications.npl.co.uk/id/eprint/10535