层合板螺栓连接结构疲劳寿命预测

Fatigue life prediction of laminated bolted joint structures

为了准确预测复合材料连接结构损伤的产生和扩展,基于单向板疲劳性能预测层合板螺栓连接结构疲劳寿命。用T300/BMP-316单向板试验数据对正则化疲劳寿命与剩余强度的参数进行拟合;在复合材料基体主控失效判据基础上增加纤维失效和分层失效判据,改进基于断裂韧性的失效准则判定损伤的产生和扩展;采用二级载荷疲劳寿命等效实现损伤的非线性累积,再对相应的损伤进行材料性能退化。预测结果与试验对比表明:对不同几何参数层合板连接结构的对数寿命预测与试验误差在5%以内,对不同应力水平下层合板连接结构的对数寿命预测与试验误差在10%以内,最终破坏模式及损伤区域的预测与试验结果吻合良好。

In order to accurately predict the onset and progression of composite structures fatigue damage, a method on the basis of unidirectional laminates fatigue property is used to predict the fatigue life of laminated bolted joint structures. The primary task is fitting the parameter of normalized life model and residual strength by T300/BMP-316 laminates test data. An improved fracture toughness-based failure criterions are used to determine fatigue damage onset and propagation, while fiber and delamination failure criterion is added to matrix-dominated failure rule. A two-state load equivalent model is introduced to accumulate damage nonlinear before material property degradation. The error between predicted logarithm fatigue life and test results of different laminated composite structures is within 5 % and the error at different stress levels is within 10 % ; the failure mode and failure region are shown to correlate well with test results.