首先，采用碳纤维增强树脂基复合材料（CFRP）与Al制备不同搭接长度双搭接胶接试验件，利用万能试验机进行拉伸试验，获得载荷-位移曲线和胶接接头失效形貌。然后，依据试验数据，基于连续损伤力学模型和3D Hashin失效判据模拟CFRP层合板损伤与演化，使用内聚力模型模拟胶层和基体损伤，获得CFRP层间应力分布与截面应力分布曲线。最后，在此基础上分析不同搭接长度下双搭接接头载荷-位移曲线与接头破坏模式，研究CFRP内部铺层应力分布对失效形貌影响，探究不同搭接长度下双搭接接头破坏机制。结果表明：搭接长度由20 mm增加至40 mm时，胶接接头力学性能显著提高；搭接长度大于40 mm后，搭接长度对力学性能的影响逐渐减弱。拉伸载荷导致90°纤维附近基体的1和2方向应力较大，产生应力集中，接头发生剪切与剥离破坏。双搭接接头失效过程为一侧发生剪切与剥离破坏，接头转变为单搭接结构，之后瞬间发生失稳，较大的剥离力使接头另一侧发生破坏。
Carbon Fiber Reinforced Plastics (CFRP) and aluminum alloys were used to prepare the double-lap bonding samples with different overlap lengths. First, a universal testing machine was used to perform tensile tests to obtain the load-displacement curves and failure morphologies of the bonding joints. On this basis, based on the continuous damage mechanics model and the 3D Hashin failure criterion, the damage and evolution of CFRP laminates are simulated, and the cohesion zone model is used to simulate the damage of the adhesive layer and the matrix, and CFRP interlayer stress field distribution and cross-sectional stress field distribution curve are obtained. Finally, the load-displacement curves and failure modes of the double lap joints with different overlap lengths were analyzed, influence of stress distribution of the composite material on the failure morphology was studied, and the failure mechanism of the joints was explored. The results show that when the overlap length increases from 20 mm to 40 mm, the mechanical properties of the adhesive joints improved significantly with the increase of the overlap length; when the overlap length was over 40 mm, its effect gradually decreased. The tensile load leads to larger stress values in the 1 and 2 directions of the matrix near the 90° fiber, and thus stress concentration and shear and peer failure of the joint. The double lap joint is failed when the one side of the joint is subject to shear and peel forces, and the joint becomes unstable instantly as the peeling force causes the failure of the other side of the joint.
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