蜂窝壁缺失所致应力集中分析

蜂窝或胞壁缺失是蜂窝夹层结构缺陷形式的一种，由于蜂窝（壁）的缺失，导致蜂窝芯子的连续性被破坏，并产生应力集中。本文从蜂窝细观尺度出发，通过数值解析与有限元模拟相结合的方式对缺陷周围胞壁正应力进行分析，首先，通过有限元模拟得到胞壁的拉应力结果，结果表明，应力集中带状区上的胞壁标准化拉应力沿横向符合近似卡方概率密度函数的分布形式；存在一个临界位置使蜂窝壁拉应力分布曲线出现反转。其次，对蜂窝缺陷最大拉应力处的壁内弯矩值与胞壁缺失个数的关系进行了推导。最后，给出了预估弯曲应力的公式，并分析了缺陷形状对预估公式参数的影响。

Stress concentration analysis of honeycomb with missing cell walls

A kind of defect with some of the cell walls missing in a honeycomb structure causes the loss of continuum of the honeycomb, and thus results in the stress concentration around the defect tip. Combined with the finite element and the analytic methods, this paper analyzed the normal stresses distribution on the cell wall at the defect tip in meso-scale. The finite element results of the tensile stress of the cell walls are obtained first. The results shows that the x-directional stress distribution in the stress concentration strip area fits the probability distribution function of the quasi chi square distribution. There exists a band zone in which the normal stress is much higher than the rest of areas. The distribution of the normal stress of cell walls conform the in the band; there also exists a critical position at which the variation trend of distribution function inverses; secondly, the relation between moments of cell wall and the number of the missing walls is analytically researched. At last. a prediction equation of the bending stress is developed and the influence of defect shape on formula is analyzed.