Experimental and numerical study of the effect of splits on specimen compliance and Δa results

Abstract

Fracture toughness testing of materials with delaminations perpendicular to the main crack (splits) is complex due to unclear effects on specimen compliance. This study examines how split morphology influences compliance and crack extension measurements using the unloading compliance method. Experiments on DH36 and X70 steels, combined with numerical simulations, CT scans, SEM, and confocal microscopy, revealed that splits within the thickness (TL) plane have negligible impact on compliance. However, deviations from the TL plane significantly increase compliance, leading to crack growth in J-R curves. These findings contradict existing compliance hypotheses for split specimens.