Towards a Digital Virtual Twin for Heterogeneous Thermomechanical Experiments

ABSTRACT The combination of digital image correlation with infrared thermography (DIC‐IRT) in heterogeneous thermomechanical tests enables the simultaneous measurement of temperature and deformation fields and can be used to identify thermomechanical constitutive parameters using inverse identification methods. However, two major challenges remain. The first is the quantification of experimental uncertainties on identification results. The second is the design of optimal test configurations that allow a single heterogeneous DIC‐IRT experiment to be reliably exploited for the inverse identification of unknown constitutive parameters. To address the first challenge, this paper presents the first developments towards a digital virtual twin (DVT) able to simulate heterogeneous thermomechanical tests integrating DIC‐IRT. The proposed methodology relies on virtual image deformation, which mimics kinematic field measurements with DIC. To include thermal field measurements, a numerical measurement chain is added to simulate the acquisition of infrared images and the spatial synchronization with kinematic data. Based on this approach, a metrological study has enabled the characterization of parameters required to reproduce the experimental uncertainties in the measurement chain. The DVT was then used to simulate a thermomechanical test, which consists of a thick steel sample subjected to heterogeneous thermal strain and temperature fields. The test is designed to identify the thermal expansion coefficient and thermophysical properties from a single experiment using finite element model updating (FEMU). By processing virtual DIC‐IRT data with FEMU, the confidence intervals on the identified parameters were predicted based on random and systematic errors in DIC‐IRT measurements. Finally, the main limitation hampering the use of the proposed DVT for optimizing the design of heterogeneous thermomechanical tests is discussed, along with potential strategies to overcome it.