Vibration and acoustic radiation characteristics analysis of composite laminated plate in hygrothermal environments

The vibration and acoustic radiation characteristics of an orthotropic composite laminated plate excited by a harmonic concentrated force in hygrothermal environments are studied. Taking the effects of hygrothermal stress and additional mass effect into account, we derive the natural frequency formulations of four-edge simply-supported laminated panel based on the first-order shear deformation theory and mode superposition approach. The sound radiation formulations for the panel are obtained by using Rayleigh integral. Furthermore, the equivalent coefficients of thermal expansion of the panel in the hygrothermal environment are obtained according to the equivalence of hygrothermal expansion and thermal expansion. Numerical simulations are carried out with the finite element method to verify the analytical solutions. It is observed that the natural frequencies decrease with the increase of moisture content and temperature due to the effect of hygrothermal stress. The orthotropic lamina is more sensitive to hygrothermal effect than the laminated plate. Meanwhile, the peaks of dynamic response, Sound Pressure Level (SPL), sound power and acoustic radiation efficiency curves of the panel generally shift towards lower frequencies; and the acoustic radiation efficiency decreases with the elevation of temperature and moisture content, and this phenomenon is more evident in the low frequency region.