Frictional heating as an estimator of modal damping and structural degradation: a vibrothermographic approach

This research presents a novel vibrothermographic approach for estimating changes in modal damping and health conditions of vibrating structures using measured temperature increases caused by frictional heat generation. In this article, the theoretical background supporting this method is firstly presented. A metal frame structure connected by bolted joints, which possessed moderate damping that could be manually adjusted by altering the bolt torque in the joints representing different tightness levels and structural health conditions, was studied experimentally so that the changes of dynamic behaviours and the structural degradation could be investigated. Through modal analyses and vibrothermographic tests with six different bolt load levels, the robustness of this method was demonstrated. In the concluding sections of the article, the significance of the observations made in this research is summarised, and the potential of this approach for further development is discussed.