Strength Analyses and Optimal Designs of Hybrid Sanwich Circulat Cylindrical Shells

为了优化设计混杂复合材料夹层圆柱壳，本文分析了两种情况.分析了双面正交各向异性和厚度不同的混杂FRP夹层圆柱壳在轴压作用下的屈曲问题，在软芯夹层圆柱壳剪切刚度较低的特殊情况下，给出了轴对称模态屈曲载荷的显式表达式。为了验证上述分析，对三种可用于低温液体容器的内表面为铝、外表面为缠绕或铝、芯部为聚氨酯的复合夹层圆筒进行了实验研究。研究发现，核心区的屈曲发生在剪切模式下，其值与分析预测的值几乎相同。2.用有限元法分析了纤维缠绕玻璃钢圆柱壳在四点弯曲载荷作用下的屈曲。用线性增量法分析了纤维缠绕圆柱的非线性特性，如载荷与挠度的关系。为了验证上述分析，对纤维缠绕玻璃钢圆柱体进行了实验研究。结果发现，最大弯曲载荷与有限元预测的屈曲载荷吻合良好。

In order to design optimal hybrid composite sandwich circular cylindrical shells, two cases were analysed in this report.1. The buckling of hybrid FRP sandwich circular cylindrical shells under axial compression was analysed, which had both faces with different orthotropies and thickness.In a particular case of sandwich cylinders with soft core having low shear rigidity , an explicit expression for buckling load with axially symmetric mode could be presented. In order to verify the above analyses, experiments were carried out on the three kinds of hybrid sandwich cylinders which have aluminum inner face, filament-wound or aluminum outer face and polyurethane formed core, which would be useful for the low-temperature liquid container. It was found that the buckling took place in shear mode in core with almost the same values as predicted in the analyses.2. The buckling of the filament wound GFRP circular cylindrical shells under the four points bending load was analysed by FEM. The linear incremental method also was used to obtain the non-linear behavior of the filament wound circular cylinders,for example the relation of loads and deflections. In order to verify the above analysis , the experiment was carried out on the filament wound GFRP circular cylinder. It was found that the maximum bending load was in good agreement with the buckling load as predicted by FEM.