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Combined vibration, thermal, and acoustic environments cause significant changes in the free and forced response characteristics of spacecraft metallic, ceramic, and carbon thermal protection systems, exhaust wash structures in fixed wing aircraft, and ground vehicle components exposed to blast loading. When structural components become damaged, the effects of combined loads are even more apparent on the structural response. A new combined vibration‐acoustic‐thermal apparatus designed to simultaneously expose specimens up to 4' by 4' with 10 g vibration up to either 100 Hz or 1 inch displacement vibrations, 140 dB acoustic pressures, and >400 °F temperatures will first be described in this paper. Then observations from experiments conducted on a sandwich metallic panel exposed to thermal loads will be described. Modal impact and active sensor data will be utilized to extract frequency response function models that change as a function of the loading. These frequency response models indicate significant ch...

A vibration‐based health monitoring technique is implemented to detect simulated damage in a sandwich metallic honeycomb under combined acoustic and thermal loading. Two types of damage are introduced into a gamma titanium aluminide panel; simulated oxidation damage in the form of a local mass addition and simulated bolt damage with a change in bolt torque. An active sensing approach is used to measure frequency response functions between a piezo‐stack actuator with force measurement and high‐frequency accelerometers. The measured frequency response function matrix is then used to estimate the virtual force due to damage. Temperatures up to 300 °F and sound pressures up to 110 dB are considered. It is shown that the measurement of damage changes with combined loading. For example, temperature changes cause bolt damage to be more apparent in the virtual force due to the effects of temperature on the attachment boundary conditions and to the temperature gradient across the panel causing global bending. Similarly, acoustic loading is shown to enhance the detection of simulated mass damage due to larger motions produced on the panel.