Thermal and Mechanical Responses of Particulate Composite Plates Under Direct Excitation

The thermal and mechanical near-resonant responses of particulate composite plates formed from hydroxyl-terminated polybutadiene (HTPB) binder and varying volume ratios of NH₄CL crystals (50, 65, 75%) are investigated. Each plate is mounted and forced with three levels of band-limited, white noise excitation (10–1000 Hz at 1.00, 1.86 and 2.44 g RMS). The mechanical response of each plate is recorded via scanning laser Doppler vibrometry. The plates are then excited at a single resonant frequency and the thermal response is recorded via infrared thermography. Comparisons are made between the mechanical mode shapes of each plate and spatial temperature distributions, with correlation seen between stress/strain and heat generation. The effects of the various crystal/binder ratios on both the thermal and mechanical responses are discussed. Results are also compared to numerical simulations. The observed thermomechanical effects help render an improved understanding of the thermomechanics of plastic-bonded composites, an essential step in support of the development of new technologies for the vapor-based detection of hidden explosives.