基于非协调广义部分混合元的层合板边界效应分析

Analysis of laminates free-edge effect based on noncompatible generalized partial mixed elements

  • 摘要: 就层合板的自由边界效应分析而言,采用位移实体单元获得的结果通常无法保证面外应力满足层间的连续要求,并且表面的面外应力值与实际状态不符,数值结果精确性低。本文基于非协调广义混合变分原理,提出了非协调广义部分混合元,对不同铺层的层合板模型进行了自由边界效应分析。利用非协调广义部分混合元可同时引入位移和应力边界条件、同时求解位移和面外应力的特点,使用较少的计算成本,获得了自由边界处更精确的面外应力结果。实例证明,在网格较稀疏的情况下,非协调广义部分混合元有效地捕捉了面外应力在自由边界附近的高应力梯度特性,同时有关奇异性的精确度明显优于文献的结果。

     

    Abstract: For the analysis of free-edge effect of laminates, the out-plane stresses obtained by displacement solid finite element usually cannot guarantee the requirement of continuity between layers, and the out-plane stress values on the surface are not exactly same with the actual values, so the accuracy of numerical results of displacement finite element method is low. Based on the noncompatible generalized mixed variational principle, noncompatible generalized partial mixed element had been proposed, and had been used for the analysis of the free-edge effect of different ply laminates. By using the characteristics of the noncompatible generalized partial mixed element, which could introduce the boundary conditions of displacement and stress at the same time, solve the displacement and out of plane stress at the same time, the more accurate out-plane stress results at the free-edge are obtained with less computational cost. The numerical example shows that with sparser mesh, the noncompatible generalized partial mixed element predicts the high stress gradient of out-plane stresses near the free-edge accurately. At the same time, the accuracy of singularity is better than the literature results.

     

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