同轴单搭接接头破坏过程研究

Research on Fracture Procedure of Coaxial Single Lap Joints

在实验所得结果之基础上研究了预偏角对单搭接胶接接头破坏机制的影响，用弹塑性有限元法模型得到了不同裂纹长度时接头整体和胶层中心等效应力沿裂纹尖端的分布，并研究了外栽大小、裂纹长度对应力强度因子的影响。结果表明，同轴接头和标准接头的破坏均从胶层界面开始，但同轴接头以形成较多小裂纹为主，而标准接头中裂纹沿着胶层向中部扩展，最终导致破坏；随裂纹长度的增加，接头上等效应力渐增，胶层中心峰值应力也增大，裂纹尖端的应力远高于其他部位；当裂纹扩展到临界尺寸时，接头会迅速破坏。

The effect of preformed angle on the fracture mechanism of both coaxial joint and off-axial joint paper is studied based on the test results. The effects of crack length in adhesive layer on the equivalent stress distributed in the mid-bondline and whole joints are investigated using an elastic-plastic finite element analysis （FEA）. The effects of the crack length and the value of external load on the stress intensity factor are also studied. The results obtained show that the cracks all originated from the hondline interface in both coaxial and of^axial joint. A lot of small cracks form along the interface of the coaxial joint while the crack develops from the interface toward mid-bondline in the off-axial joint. The equivalent stress in whole joint and the mid-bondline increased when the cracks lengths and external load increase and the stress near the crack tip is much higher than that in the rest zone. The single lap joint fails when the crack length reaches to the critical size.