Vibration and acoustic responses of composite and sandwich panels under thermal environment

Experiments were performed to investigate the vibration and acoustic response characteristics of a clamped rectangular aluminum plate in thermal environments. Modal tests were carried out to study the influence of thermal environment on natural vibration. With the increment of structural temperature, natural frequencies of the plate decrease obviously. Mode shape interchange was observed for the modes with frequencies very close to each other. The thermally induced softening effect has unequal influences on the plate along the two in-plane directions. Numerical methods were also employed to study the experimental phenomena. Calculated results indicated that the initial deflection has a great influence on the natural vibration of the heated plate. Even a slight curvature can reduce the thermally induced softening effect obviously. Dynamic response tests were carried out under acoustic and mechanical excitations, and the measured results indicate that the variation in damping determines the response amplitudes at resonant peaks in the test.

Dynamic and acoustic response of a clamped rectangular plate in thermal environments: experiment and numerical simulation.

This work presents an investigation of vibration and acoustic response characters of a clamped rectangular thin plate in thermal environments. The general form of governing equation of plate flexural vibration with considering thermal loads is established, and the influence of uniform temperature change on response characters is studied in detail. A set of double sinusoidal mode shape functions for fully clamped boundaries is used to describe the displacement distribution. The governing equation is solved with Fourier series expansion to discuss the natural vibration and dynamic responses of a clamped plate in thermal environments. Accordingly, acoustic radiation characteristics are obtained based on Rayleigh integral. Results show that natural frequencies decrease with the increment of plate temperature, and the first natural frequency is much more sensitive to thermal environment changes. Response curves of plate vibration and radiated sound power shift toward lower frequency range, and the response amp...

Solutions of dynamic and acoustic responses of a clamped rectangular plate in thermal environments

Buckling and vibro-acoustic response of the clamped composite laminated plate in thermal environment

Vibration and sound radiation analysis of temperature-dependent porous functionally graded material plates with general boundary conditions

In this paper, we focus on the vibration and acoustic response of a rectangular sandwich plate which is subjected to a concentrated harmonic force under thermal environment. The critical buckling temperature is obtained to decide the thermal load. The natural frequencies and modes as well as dynamic responses are acquired by using the analytical formulations based on equivalent non-classical theory, in which the effects of shear deformation and rotational inertia are taken into account. The rise of thermal load decreases the natural frequencies and moves response peaks to the low-frequency range. The specific features of sandwich plates with different formations are discussed subsequently. As the thickness ratio of facing to core increases, the natural frequencies are enlarged, and the response peaks float to the high-frequency region. Raising the Young's modulus of the core can cause the similar trends. The accuracy of the theoretical method is verified by comparing its results with those computed by the FEM/BEM.

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Vibration and Acoustic Response of Rectangular Sandwich Plate under Thermal Environment

Experiments were carried out for a clamped rectangular aluminum plate to study the dynamic and acoustic behaviors in both pre- and post-buckling ranges under thermal loads. Plate temperature was elevated from ambient value to the level above the theoretical critical buckling temperature of the plate. In the whole test temperature range, the measured frequencies decreased to the minimum values in sequence, and then turned to increase as temperature rose. The softening effect of thermal stresses played the leading role in the decreasing stage and the stiffening effect of thermal buckling deflection became the major influence factor in the increasing stage. The later one could drive the temperature equilibrium point of the heated plate to move towards lower temperature range. All the frequencies would not drop to zero due to the inherent initial deflection which provides additional stiffness to the plate. Dynamic responses state two variation trends in different temperature ranges, shifting toward the lower frequency range and closing up in the mid-frequency range. The characters of spectrum responses changed gradually as the temperature was elevated. Numerical simulations gave predictions with same variation trend as the test results.

Experimental and numerical investigations on dynamic and acoustic responses of a thermal post-buckled plate

In this paper, the dynamic response and sound radiation of sandwich plate subjected to an acoustic excitation under thermal environment are analyzed. The thermal environment is a uniform temperature load. Thermal stress is considered as the membrane force in the plate, while the change of the material property due to the thermal load is ignored. The acoustic excitation applied on the sandwich plate is assumed to be a plane wave. Coupling of the structural vibration and acoustic medium is considered. The equivalent non-classical theory, which takes the effects of rotational inertia and shear deformation into account, is utilized to get the analytical solutions. The effects caused by thermal environment and acoustic excitation are discussed. It is found that the rise of thermal load decreases the natural frequencies and moves response peaks to the low-frequency range. The acoustic excitation doesn’t influence the natural characteristics of the sandwich plate, but the incident angle is relative to the number of evident peaks on the response curve. The comparisons of the analytical results and those computed by VA one show the accuracy of the theoretical method.

Yuan Liu

Papers

Vibration and Acoustic Response of Rectangular Sandwich Plate under Thermal Environment

Experimental and numerical investigations on dynamic and acoustic responses of a thermal post-buckled plate

Analyses of dynamic response and sound radiation of sandwich plate subjected to acoustic excitation under thermal environment