Stereo-DIC measurements of thermal gradient effects on the vibratory response of metals

Thermomechanical problems have been much less studied than their room temperature counterparts as challenges arise both with metrology and with interpretation of results. This effort aims to shrink this knowledge gap by investigating the influence of thermal effects on the high frequency vibratory response of metals. The present study concentrates on how an inhomogeneous temperature field (max. 600 °C) affects the vibratory response, and specifically mode shapes and resonant frequencies, of a vibrating plate. A plate made of a nickel-based superalloy, Hastelloy X, was heated by induction heating and the temperature distribution was estimated by measuring the out-of-plane curvature resulting form heating. Harmonic vibratory loading at frequencies exceeding 1 kHz was applied using a programmable shaker. Stereo-vision digital image correlation (stereo-DIC) was used to obtain a full-field representation of the vibrating plate. An image decomposition analysis technique based on Tchebichef polynomials was used to compare room and high temperature mode shapes. Results indicate that there is a small influence of temperature on resonant frequencies, even though mode shapes remain similar between room and high temperature vibration.