Temperature effects on Digital Twins: Finite Element Model Updating of a Scaled Jacket Foundation

Various interpretations of the digital twin concept exist in practice and the scientific communities, with most of them sharing a common foundation: a base finite element (FE) model and a model updating procedure that uses data from the concerned real-world or physical structure. Commonly, the applied model updating method aims to align the dynamic properties, such as natural frequencies, modal damping ratios, or mode shape values, with those from the actual structure, using underlying numerical minimization schemes. The present study investigates the ability of a digital twin to capture the influence of environmental changes on a jacket-type offshore wind turbine foundation. For a real-world offshore structure, a few important operational conditions may be the variations in temperature, wave height, wind speed, or rotor state. In particular, it remains unclear how changes in the modal parameters of a jacket foundation due to temperature changes affect the model-updating parameters of the corresponding FE model. In this study, we examine how model-updating parameters vary with temperature. An excessive amount of data is collected through experimental modal analysis in an indoor laboratory environment with naturally varying temperatures. The data are then divided into a number of experiments, for which the modal parameters are obtained. Each set of modal parameters is then used to update the FE model. The results comprise distributions of the model-updating parameters as a function of temperature, demonstrating the influence of temperature changes on a jacket-type foundation, the uncertainty in the model-updating parameters, and the digital twin's ability to capture the associated changes in the governing dynamic parameters.