Thermoelastic effect in modal shapes at high frequencies using infrared thermography

•A methodology for mode shape analysis using infrared thermography is presented.•The required parameters to measure high-frequency thermal variations are described.•TSA has revealed remarkable capabilities to analyse a broad spectrum.•Finite element results validated the experimental resonance thermal fields.•The different causes of signal-to-noise ratio reduction are explained. Infrared thermography is employed by different methodologies and techniques to perform characterisations and evaluations in solids, typically related to fracture mechanics and damage, based on monitoring heat generation or temperature changes. In this study, the limits of the current technology for Thermoelastic Stress Analysis (TSA), usually employed under low-frequency loads, are explored to characterise temperature fields associated to the first stress invariant in mode shapes. Higher frequencies are especially emphasised in this research. Eleven modes of a plate were analysed, reaching frequencies over 2000 Hz. High correlation coefficients were obtained in comparison with the first stress invariant fields of a finite element model, with a detriment as the mode’s order increases. In those cases, this study highlights the combined influence of the specimen response and mode shape stiffness as well as the progressively shorter integration time.