钛合金-芳纶纤维复合材料单搭接胶接接头渐进破坏分析

Progressive Failure Analysis of Titanium Alloy-Aramid Fiber Composite Single Lap Bonded Joints

采用芳纶纤维复合材料与钛合金制备单搭接胶接连接实验件。利用万能实验机、DIC、应变采集系统等手段,对胶接接头的极限载荷、应变场、应变分布和破坏模式进行表征,分析了拉伸载荷下胶接接头的应变分布规律和复合材料层合板刚度折减规律,探究了异质材料单搭接胶接接头的破坏过程。结果表明,胶接接头破坏模式为搭接接头两端胶层界面破坏,中间部位复合材料层间破坏。接头破坏过程为渐进破坏,受载时复合材料端头产生较大的剪切应变,裂纹在此处萌生,并不断向钛合金端头扩展,扩展部位复合材料层合板刚度不断折减,直到搭接面积过小胶层突然发生界面破坏。

A series of specimens were fabricated by using a single lap adhesive connection of aramid fiber composite mate-rial with titanium alloy,and the ultimate load,stress field strain distribution and failure mode of the bonded joints were characterized with a universal testing machine,DIC and strain acquisition system.The strain distribution of bonded joints under tensile load and the stiffness reduction law of composite laminates were analyzed.Moreover,the failure process of single lap adhesive joints of dissimilar materials was also studied.The results indicated that the failure modes of bonded joints were ascribed to the adhesive interfacial failure at the two ends of overlap region and the composite delamination failure in the middle part.When the joint was under the load,the composite end was subject to the large shear strain,which led to the cracks occurring at the composite end and then continuously expanding to the metal end.The entire fail-ure process of the joint belongs to a progressive failure.The stiffness of composite was continuously reduced with the propagation of cracks until the adhesive failure suddenly took place due to the small area.