Effect of Geometrical Configuration and Strain Rate on Aluminum Alloy 5083 and S550 Steel Characterized by Digital Image Correlation.

This manuscript proposes a non-contact approach to characterize geometrical configuration and strain rate effects using digital image correlation (DIC). The non-contact DIC technique allows more robust and accurate material property assessment than conventional in-contact gauges, especially under dynamic loading conditions. This study first demonstrates DIC-based strain measuring accuracy in quasi-static coupon tests with two geometrical configurations. In comparison to the conventional method, DIC measures a wider range of strain up to the final fracture while eliminating geometric constraints typically imposed on test specimens. This study further extends the DIC measurement in dynamic material property tests, i.e., the split-Hopkinson bar test. The direct strain measurement by DIC presents enhanced accuracy compared to the conventional method, as the latter overestimates the strain results from remotely installed strain gauges. The deformation analysis explains the discrepancy in strain measurement at different sensor locations. The strain rate effects on the stress-strain curve and fracture strain are evaluated on two materials, i.e., aluminum alloy 5083 and S550 steel. The proposed DIC approach enables more convenient and robust measurement of strains, which facilitates the material property evaluation under various geometrical configurations and strain rates.