Vibration and acoustic response of an orthotropic composite laminated plate in a hygroscopic environment

Abstract

This paper is a study of the vibration and acoustic response characteristics of orthotropic laminated composite plate with simple supported boundary conditions excited by a harmonic concentrated force in a hygroscopic environment. First the natural vibration of the plate with the in-plane forces induced by hygroscopic stress is obtained analytically. Secondly, the sound pressure distribution of the plate at the far field is obtained using the Rayleigh integral. Furthermore, the sound radiation efficiency is deduced. Third, different ratios of elastic modulus in material principal directions are set to research the effects of increasing stiffness of the orthotropic plate on the vibration and acoustic radiation characteristics. Finally, to verify the theoretical solution, numerical simulations are also carried out with commercial finite software. It is found that the natural frequencies decrease with the increase of the moisture content and the first two order modes interconvert at high moisture content. The dynamic response and sound pressure level float to lower frequencies with elevated moisture content. Acoustic radiation efficiency generally floats to the low frequencies and decreases with an increase of moisture content. The dynamic and acoustic responses reduce and the coincidence frequency decreases with the enhanced stiffness.