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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%。
In order to deal with the strength and damage of the composite headless bolt connection structure, a comparative experimental study was conducted on the compressive strength between the two kinds of thick composite laminates and the countersunk head bolt connection structure. The experimental results show that increasing the thickness of the laminate will result in the decrease of the extrusion strength of the connection structure, but the descending proportion of the connection structure of the head connection is smaller than the connection structure of the nose connection. The strength and damage failure of the composite plate sinking head connection structure were analyzed by numerical simulation method. A non-linear in-plane continuous damage and three-dimensional hybrid failure model is proposed. The model takes into account the nonlinear shear characteristics of the composite matrix and improves the criterion of failure of fiber damage. It effectively solves the problem that the connection structure of the headstock in the numerical simulation is difficult to converge problem. The comparative analysis shows that the numerical calculation results of the countersunk head connection structure are in good agreement with the experimental results, and the maximum calculation error of ultimate strength is 8.62%.