Nomex蜂窝芯静态压缩屈曲与后屈曲分析

基于自动铺丝工艺,为获得良好的蜂窝夹层结构自动铺放成型质量,建立了Nomex蜂窝芯在压辊压力下的屈曲、后屈曲和破坏整个失效过程的数值分析方法。采用线性屈曲分析法(特征值分析法)对蜂窝单元进行屈曲分析,得到一阶屈曲模态、屈曲特征值及屈曲载荷;引入初始结构几何缺陷,采用非线性屈曲分析法(弧长法)对Nomex蜂窝单元后屈曲行为进行分析,输出参考点RP-1的载荷-位移曲线,得到弧长法计算的屈曲载荷以及极限载荷值。通过对比试验结果与两种屈曲分析法得到:对于分析临界屈曲载荷,特征值法较弧长法更精确;而弧长法可以更好模拟结构的后屈曲行为,计算结果与试验数据基本吻合,为Nomex蜂窝夹心结构自动铺放成型过程中铺放压力的选取提供参考。

Buckling and Post-Buckling of Nomex Honeycomb Cores Under Compression

In order to obtain a good honeycomb sandwich structure automatic placement quality, based on the automated fiber placement a numerical method for buckling, post-buckling and failure of Nomex honeycomb cores under compression load are established. The linear buckling method (eigenvalue method) is used to analyze buckling of honeycomb cell and the first-order buckling mode, the buckling eigenvalue and load are obtained. The initial geometrical defects are introduced, and non-linear buckling method (arc length method) is used to analyze the post-buckling behavior of Nomex honeycomb cell. According to the load-displacement curve of RP-1, the buckling load and the limit load of the arc length method are obtained. Contrasting the data of the finite element bucking analysis and experiment, some conclusions can be obtained: The eigenvalue method is more accurate than the arc length method in buckling analysis, but the arc length method can simulate post-buckling behavior better. The calculated results are basically consistent with the experimental data. A reference is provided for selecting the placement pressure in the process of automatic placement of Nomex honeycomb sandwich structure.