复合材料中厚板沉头连接结构强度与损伤失效

Strength and damage evolution of mid-thick composite laminates with countersunk bolt joints

  • 摘要: 针对复合材料沉头螺栓连接结构的强度与损伤问题,开展了两种厚度复合材料层合板凸头与沉头螺栓连接结构挤压强度对比试验研究。试验结果表明,增加层合板厚度会引起连接结构挤压强度下降,但沉头连接结构下降比例小于凸头连接结构。通过数值模拟方法对复合材料中厚板沉头连接结构的强度及损伤失效进行分析。提出一种非线性面内连续损伤与三维混合失效模型,模型考虑了复合材料基体剪切非线性特征并改进了纤维损伤失效判据,有效解决了数值模拟中沉头复合材料连接结构难于收敛的问题。对比分析表明:沉头连接结构的数值计算结果与试验结果吻合良好,极限强度最大计算误差8.62%。

     

    Abstract: Comparison analysis on bearing strength of two thickness composite laminates with countersunk bolt joint or protruding bolt joint was conducted using experimental method to deal with the strength and damage evolution of mid-thick composite laminates with countersunk bolt joints. The results provide sufficient evidence that the decrease of bearing strength caused by the laminates thickness increase of countersunk bolt is less than that of protruding bolt connection structure. To investigate the damage evolution and failure strength of countersunk bolt joint, a new continuum damage failure model with the combination of continuum damage evolution and 3D mixed failure criterions was proposed. The model takes the advantages of consideration of matrix shear nonlinearity, using the improved fiber failure criterion and improvement in the convergence of the composite structure. The predicted results agree well with the experimental results and the deviation of the failure strength is no more than 8.62%.

     

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