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In this paper, vibration analysis of irregular-closed-cell foam plates is performed. A cell volume distribution coefficient is introduced to modify the original Gibson-Ashby equations of effective Young??s modulus of foam materials. A Burr distribution is imported to describe the cell volume distribution situation. Three Burr distribution parameters are obtained and related to the cell volume range and the diversity. Based on the plate theory and the effective modulus theory, the natural frequency of foam plates is calculated with the change of the cell volume distribution parameters. The relationship between the frequencies and the cell volumes are derived. The scale factor of the average cell size is introduced and proved to be an important factor to the performance of the foam plate. The result is shown by the existing theory of size effects. It is determined that the cell volume distribution has an impact on the natural frequency of the plate structure based on the cell volume range, the diversity, and the average size, and the impact can lead to optimization of the synthesis procedure.  相似文献   
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Thermal buckling analysis of truss-core sandwich plates   总被引:1,自引:0,他引:1  
Truss-core sandwich plates have received much attention in virtue of the high values of strength-to-weight and stifness-to-weight as well as the great ability of impulseresistance recently. It is necessary to study the stability of sandwich panels under the influence of the thermal load. However, the sandwich plates are such complex threedimensional(3D) systems that direct analytical solutions do not exist, and the finite element method(FEM) cannot represent the relationship between structural parameters and mechanical properties well. In this paper, an equivalent homogeneous continuous plate is idealized by obtaining the efective bending and transverse shear stifness based on the characteristics of periodically distributed unit cells. The first order shear deformation theory for plates is used to derive the stability equation. The buckling temperature of a simply supported sandwich plate is given and verified by the FEM. The efect of related parameters on mechanical properties is investigated. The geometric parameters of the unit cell are optimized to attain the maximum buckling temperature. It is shown that the optimized sandwich plate can improve the resistance to thermal buckling significantly.  相似文献   
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主要研究了不规则几何结构多孔材料制备的板材的振动分析.基于Gibson-Ashby等效模量计算,引入了分布因子加以改进原有的理论.对于材料的孔洞分布情况,提出了Burr分布的概率密度拟合,获得了Burr分布的3个自变量参数并用实际的孔洞几何参数进行了比对与描述.基于平板振动理论和等效模量理论,计算出了随着孔洞分布情况变化下的平板固有振动频率,并分析了孔洞尺寸与频率间的关系.之后引入了尺度因子来量化描述平均孔洞尺寸对多孔平板的频率影响.结论证明了改进的等效理论能够有效地体现孔洞的分布对平板力学性能的改变,论述了孔洞尺寸范围,孔洞离散度以及平均孔洞尺寸对多孔方板结构固有频率的影响.这种影响将会对多孔材料结构的优化设计起指导作用.  相似文献   
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轻质点阵结构在高温工作环境下易产生失稳破坏,因此,研究其在热载荷条件下的稳定性是极为重要的。本文采用有限元数值计算和实验方法研究了轻质点阵夹芯板在热载荷作用下的稳定性问题。通过与点阵夹芯板的单向压力失稳形式相比较发现:点阵夹芯板的单向压力失稳和热载荷作用失稳的形式并不完全一致;而且,面板厚度及其与夹芯杆件的粘接程度对点阵夹芯板的稳定性有着重要的影响。此外,本文针对将温度变化等效为热应力这一等效模型的适用性进行了讨论,发现等效均匀化理论只适用于面板较厚且产生整体失稳的情况。  相似文献   
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