In this paper, the extended higher-order sandwich plate's theory (EHSAPT) is used to analyze the free vibration of the sandwich plate with compressible core and different boundary conditions in contact with fluid. First-order shear deformation theory is adopted for the top and bottom face sheets, while the in-plane and transverse displacements of the core are considered to be cubic and quadratic functions of the transverse coordinate, respectively. A single series is considered with two-variable orthogonal polynomials as a set of admissible functions satisfying the boundary conditions. Besides, the fluid is considered to be irrotational, inviscid and incompressible. By taking into account the boundary conditions and compatibility conditions, the fluid velocity potential is acquired. The natural frequencies of the system are calculated by the Rayleigh-Ritz method. An excellent accuracy is obtained between the results in the available literature and the present method. Finally, the effects of various parameters including boundary conditions, side-to-thickness ratio, thickness of the core to thickness of the face sheets ratio, face sheet to core flexural modulus ratio, dimensions of the container, and aspect ratios on the natural frequencies of the sandwich plate are presented and discussed in detail.

本文采用扩展的高阶夹心板理论（EHSAPT）来分析具有可压缩核心和不同边界条件的夹心板与流体接触的自由振动。顶面板和底面板采用一阶剪切变形理论，而芯的平面内和横向位移分别被认为是横向坐标的三次函数和二次函数。具有两个变量的正交多项式的单个序列被视为满足边界条件的一组允许函数。此外，流体被认为是不可旋转的，无粘性的和不可压缩的。通过考虑边界条件和相容性条件，获得了流体速度势。系统的固有频率是通过瑞利-里兹方法计算的。在可获得的文献中的结果与本方法之间获得了极好的精度。最后，各种参数对固有频率的影响包括边界条件，侧面厚度比，芯层厚度与面板厚度之比，面板层与芯层挠曲模量比，容器尺寸以及长宽比对固有频率的影响介绍并详细讨论了夹心板的结构。