Crack tip fields characterisation on non-planar surfaces employing a differential geometry approach and 3D digital image correlationexperimental and numerical study

Abstract

In this thesis, a novel methodology for crack tip fields characterisation on non-planar and developable surfaces under plane stress conditions is developed. This methodology, which used differential geometry to modify originals flats crack tip field models, has been validated using 3D displacements fields measured via 3D digital image correlation in hollow cylindrical specimens. Two materials were tested under fatigue loading, a stainless steel and an aluminium alloy. In addition, a robust and easily automatable methodology for crack tip parameters determination was developed. Moreover, finite element analysis was employed to provide those data that cannot be measured using digital image correlation. The proposed methodology allows high accurate results to be obtained well in terms of KI and the surrounding elastic field.