13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Analyses of dynamic response and sound radiation of sandwich plate subjected to acoustic excitation under thermal environment Yuan Liu, Yueming Li* State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, China *Corresponding author: liyueming@mail.xjtu.edu.cn Abstract 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. Keywords Sandwich plate, Thermal environment, Acoustic excitation, Dynamic response 1. Introduction Sandwich plates are extensively used in the thermal protection system, which is utilized to protect the structure from the damage caused by the high temperature resulting from aerodynamic heating. During the course of the flight, the sandwich plate is exposed to high temperature and harsh mechanical, acoustic excitation. In order to use them efficiently, a good understanding of the dynamic and acoustic characteristics of the sandwich plate under such situation is necessary. Vibro-acoustic problems of the structures under thermal environment are of great concern. N. Ganesan et al [1, 2] have analyzed vibration and sound radiation characteristics of composite plates under thermal environment numerically. Li et al [3-5] have carried out vibro-acoustic analyses for structures under thermal environment, including the broadband vibro-acoustic response based on hybrid FE-SEA [3], the influence of thermal stress with numerical method [4], and analytical solution for the dynamic and acoustic characteristics of an isotropic plate in thermal environments using classical plate theory [5]. Although a lot of vibro-acoustic problems under thermal environment have been analyzed, few studies can be found for sandwich plates, especially, lack of theoretical investigations. The aim of this paper is to analyze the vibration and acoustic characteristics of a sandwich plate subjected to an acoustic excitation under thermal environment. Based on the equivalent non-classical theory, this study considers the effects of the shear deformation and the rotational inertia but ignores the compressional deformation. The coupling between the plate and the acoustic medium is taken into account. The influences caused by the thermal environment and the incident angle of the plane wave on the sandwich plates are deeply discussed in the present study. 2. Fundamental formulations A sandwich plate with dimensions of 1 2 (2 ) a b h h × × + is considered here, as shown in Fig. 1. The plate consists of two isotropic materials for facings and core respectively. The subscripts in the parameter expressions identify the specific materials, 1 for those of facings and 2 for those of core.
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