Application of digital image correlation to the investigation of crack closure following overloads

作者：D. Nowell, P.F.P. de Matos · 发表于：Procedia Engineering · 年份：2010 · DOI：10.1016/j.proeng.2010.03.112 · 被引用次数：51 · 研究领域：Fatigue and fracture mechanics、Non-Destructive Testing Techniques、Ultrasonics and Acoustic Wave Propagation

This paper describes a set of fatigue experiments carried out on 6082 Aluminium CCT specimens. Crack propagation rates and crack opening loads were measured before and after a single overload in an otherwise constant amplitude loading sequence. Crack retardation was observed after the overload, and this was more significant in thin (3 mm) specimens than in thick (25 mm) specimens of otherwise similar geometry. Digital image correlation and conventional strain gauges were used to monitor crack closure, and it was found that surface closure levels were similar in the two thicknesses of specimen. However, the thick specimens showed lower closure levels as detected by the strain gauges. This observation is consistent with the lower levels of crack retardation observed. A plane stress strip-yield model of crack closure was employed to simulate the experimental loading cycle and this showed qualitatively similar behaviour to that observed on the surface of the specimens.