The experimental validation of fracture mechanics methods is underway, with collaboration between Oxford and Stellenbosch Universities and using state-of-the-art X-ray tomography equipment at Manchester Uni to perform in-situ tests on ‘ideal’ cracks. In our study, ‘ideal’ refers to EDM (Electrical Discharge Machined) notches. These are preferred due to the more controllable shape.
A key simplification used to characterise cracks under complex loading is to consider the crack behaviour in three fundamental modes: opening (Mode I), in-plane shearing (Mode II) and out-of-plane tearing (Mode III), as illustrated below.
The experimental setup allows us to measure surface and subsurface deformations of all three modes from a single curved and inclined crack front, where lab tomography reconstructions (Manchester University) have been used to obtain images of the volume (and marker particles in the material) in-situ. Strain maps around the notch tips will be studied using digital volume correlation.