QUANTIFYING J-R CURVE USING DIGITAL IMAGE CORRELATION

CHEN CHENG

Publication

QUANTIFYING J-R CURVE USING DIGITAL IMAGE CORRELATION

CHEN CHENG

Abstract

This thesis presents a non-contact digital image correlation (DIC) approach to measure the J-integral resistance (J-R) curve under quasi-static and dynamic loadings. The DIC-based J quantification deploys specified contours and domains while the amount of crack extension derives from the displacement and strain fields on the specimen free surface. The numerical analyses verify the DIC algorithm and investigate the effects of side grooves and strain rates on the proposed DIC method. This thesis establishes a fundamental relationship to correlate the through-thickness averaged J values from DIC-measured free-surface J results, which is evidenced through theoretical and experimental validations. The single edge notched bend (SEB) and the drop-weight tearing tests (DWTT) are further carried out under different loading rates to investigate the strain rate effects on the material performance. The DIC results demonstrate enhanced fracture resistance under increased strain rates for metallic materials.