碳纤维/聚醚醚酮单搭接焊接结构的破坏试验及强度预测

Failure experiment and strength prediction of CF/PEEK single lap welded structure

为研究湿热环境下碳纤维/聚醚醚酮(CF/PEEK)单搭接焊接结构的失效形式以及湿热环境对其性能的影响,分别在室温干态环境和湿热环境中进行拉伸剪切试验。同时使用三种不同的内聚力模型对该结构的单搭接剪切强度进行预测。试验结果表明,湿热环境中CF/PEEK单搭接焊接试样出现了与室温干态环境中相同的三种失效模式,分别为界面失效、混合失效和层压板撕裂失效。在试验误差范围内,相比于室温干态环境,湿热环境中发生同样破坏形式的焊接接头的单搭接剪切强度变化不大,但是湿热环境中搭接板端部树脂发生明显的塑性变形,结构刚度平均降低约22%,破坏位移平均增大约88%。数值结果表明,对于预测室温干态环境中仅发生层合板撕裂失效的焊接接头的破坏强度,三种内聚力模型中指数型内聚力模型的强度预测结果与试验结果更为吻合。

In order to study the failure mode of carbon fiber/poly-ether-ether-ketone(CF/PEEK) single lap welded structure in elevated temperature wet condition and the influence of elevated temperature wet condition on its performance,the shear tests were carried out in the room temperature dry condition and the elevated temperature wet condition,respectively.At the same time,three different cohesive force models were used to predict the shear failure load of the structure.The test results show that CF/PEEK single-lap welded specimens in the elevated temperature wet condition show the same three failure modes as those in the room temperature dry condition,namely interface failure,mixed failure and laminate tearing failure.In the range of test error,compared with the room temperature dry condition,the single lap shear strength of welded joints with the same failure mode in elevated temperature wet condition has no obvious change,but the resin at the end of the lap plate has obvious plastic deformation in the elevated temperature wet condition,the average structural stiffness decreases by about 22%,and the average failure displacement increases by about 88%.The numerical results show that the strength prediction results of the exponential cohesive model in the three cohesive models are more consistent with the experimental results for the welded joints with only delamination failure in the room temperature dry condition.