Uncertainty Analysis of Dynamic Rupture Measurements Obtained Through Ultrahigh-Speed Digital Image Correlation

Background The full-field behavior of dynamic shear cracks, with their highly transient features, has recently been quantified by employing Digital Image Correlation (DIC) coupled with ultrahigh-speed photography (at 1-2 million frames/sec). The use of ultrahigh-speed DIC has enabled the observation of complex structures associated with the evolution of the dynamic shear fractures under controlled laboratory conditions, providing a detailed description of their distinctive full-field kinematic features. This has allowed to identify, for instance, the spatiotemporal characteristics of sub-Rayleigh and intersonic shear ruptures, and to measure the evolution of dynamic friction during rupture propagation of frictional shear ruptures. Objective Capturing such highly transient phenomena represents a challenging metrological process influenced by both ultra-fast imaging procedures and DIC analysis parameters. However, the effect of these parameters on the quantification of the rupture features has not been assessed yet. Here, a simulated experiment framework is presented and employed to evaluate the uncertainties associated with ultrahigh-speed DIC measurements. Methods Finite element simulations replicate laboratory experiments of dynamic ruptures spontaneously propagating along frictional interfaces. Experimental images of the specimen acquired with an ultrahigh-speed camera are numerically deformed by the displacement fields obtained from the numerical simulations and are analyzed using the same DIC analysis procedure as in the laboratory experiments. Results The displacement, particle velocity, and strain fields obtained from the DIC analysis are compared with the ground-truth fields of the numerical simulations, correlating the measurement resolution with the physical length scale of the propagating Mode II rupture. In addition, the full-field data are employed to estimate the capability of the ultrahigh-speed DIC setup to infer the dynamic friction evolution. Conclusions This methodology allows us to quantify the accuracy of the ultrahigh-speed DIC measurements in resolving the complex spatiotemporal structures of dynamic shear ruptures, focusing on the impact of the key correlation parameters.