缺陷对单搭胶接接头力学性能的影响

Effect of defects in the adhesive layer on strength of adhesively bonded single-lap composites joints

通过单向拉伸试验对比分析了两种接头的破坏模式及载荷-位移曲线,研究了T700/TDE85复合材料单向层合板单搭接胶层内缺陷对接头破坏行为的影响。试验结果表明,接头破坏的主导模式为界面破坏,胶层中微小缺陷对接头强度的影响不大。为研究接头的失效机制,采用有限元方法对两种接头失效进行数值分析,模拟了接头搭接区界面剥离应力及剪切应力分布情况,并分析了缺陷位置变化及面积变化对接头强度的影响。结果表明,随着缺陷位置距接头搭接区自由端部越近,接头强度越小,且缺陷位置距接头搭接区自由端部2.5mm以内,缺陷对接头强度影响较大;接头强度随缺陷面积的增大而减小,并且缺陷面积占搭接区面积的比率在4.4%以内,缺陷对接头强度的影响较小;数值计算结果与实验结果吻合较好。

The tests on T700/TDE85 unidirectional laminates single-lap joints （SLJ） with defect and no defect in the adhesive layer under the uniaxial tensile loading were performed. Two different types of joints were designed and analyzed. According to the experimental results, failure modes of two kinds of joints were characterized and load-displacement curves were compared. It is appeared that interfacial failure is the major failure mode and the joint strength is slightly affected by defects with the small size in the adhesive layer. For investigating failure mechanism of joints, a finite element simulation was carried out to analyze the failure behavior and the peel/shear stress fields along the adhesive layer interface for the joints. It is found that the joint strength decreases with the decreasing length of defect location from the overlap end, and effect of length of defect location from the overlap end within 2.5 mm on the joint strength is more greatly. In addition, the joint strength decreases with the increasing of defect area, and area fraction of defect along the overlap zone within 4.4% has a little influence on the joint strength. The computational results are in good agreement with the experimental results.