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DIC-based Full-Field Calibration using LS-OPT®: An Update

This paper extends a 2017 study on full-field calibration using Digital Image Correlation (DIC) and the Finite Element Method to identify parameters of a material model developed for elastoplasticity. DIC is an optical method which provides full-field displacement or strain measurements for mechanical tests of materials and structures. It can be combined with the corresponding fields obtained from a Finite Element Analysis to identify constitutive properties. The methodology, which involves the solution of an inverse problem, consists mainly of two new core features namely (i) multi-point histories and (ii) suitable curve similarity measures. Multi-point histories are response curves which are evaluated at multiple spatial locations and extracted from simulations and experimental data. To improve on the previously used Euclidean curve distance measure, the Discrete Fréchet (DF), Dynamic Time Warping (DTW) and Partial Curve Mapping (PCM) measures were developed and validated for multi-point histories. An interface to a commercial DIC package, as well as two text-based generic interfaces, was also developed. A tensile test example was used to validate and demonstrate the methodology based on the DIC measurement of spatial point-wise strains. The example validated the code but revealed potential problem areas, such as solution stability, requiring further investigation.