Yang Kang, Liu Ziyi, Qi Xin, Li Pengyang, Ji Shude, Liu Peng, Liu Zhipeng
College of Aerospace Engineering, Shenyang Aerospace University, Shenyang, 110136, China.
Design Department, Liaoning General Aviation Academy, Shenyang, 110136, China.
Sci Rep. 2024 Dec 30;14(1):32034. doi: 10.1038/s41598-024-83605-y.
This paper had conducted tensile shear tests on single-lap joints (SLJs)bonded structures of carbon fiber reinforced resin matrix (CFRP) composite laminates with different overlap lengths, overlap widths, overlap model, adherend material, and adhesive layer thicknesses under two environments: room temperature dry state (RTD) and elevated temperature wet state (ETW). The failure modes were observed, and load-displacement curves were obtained. The microscopic morphology of the fracture surface was observed by scanning electron microscope (SEM). At the same time, a finite element simulation model was established to simulate the damage initiation and evolution process between layers and in the adhesive layer, and analyze the distribution laws of peel stress and shear stress in the adhesive layer. Through the combination of test data and simulation results, the influences of geometric parameters, material parameters and environmental parameters on the structure were explored, and the joint failure mechanism was revealed. Finally, the ACO-BP neural network was used to optimize the geometric parameters through test data. The research results showed that the geometric parameters of the structure mainly affect the bearing capacity and failure type. Reducing the overlap length and increasing the overlap width within a certain range can weaken the peeling phenomenon, so that a smaller overlap area has a higher shear strength. The material parameters of the adherend mainly affect the stress distribution law and stress transfer process of the adhesive layer in the overlap area. The joint mainly bore shear stress and peel stress, and shear stress is the main cause of damage initiation. When the types of adherend materials are different, the stress distribution law shows obvious asymmetric offset. The lap model mainly affects the location distribution of the failure area, and the environmental parameters mainly affect the area proportion relationship of various fracture forms in the mixed failure mode.
本文对碳纤维增强树脂基（CFRP）复合层压板单搭接接头（SLJ）粘结结构在室温干燥状态（RTD）和高温潮湿状态（ETW）两种环境下，进行了不同搭接长度、搭接宽度、搭接形式、被粘物材料以及粘结层厚度的拉伸剪切试验。观察了失效模式，获取了载荷 - 位移曲线。通过扫描电子显微镜（SEM）观察了断口表面的微观形貌。同时，建立了有限元模拟模型，模拟层间和粘结层内损伤的起始和演化过程，分析粘结层中剥离应力和剪切应力的分布规律。通过试验数据与模拟结果相结合，探究了几何参数、材料参数和环境参数对结构的影响，揭示了接头失效机理。最后，利用蚁群优化 - 反向传播（ACO - BP）神经网络通过试验数据对几何参数进行优化。研究结果表明，结构的几何参数主要影响承载能力和失效类型。在一定范围内减小搭接长度、增加搭接宽度可减弱剥离现象，使较小的搭接面积具有较高的剪切强度。被粘物的材料参数主要影响搭接区域粘结层的应力分布规律和应力传递过程。接头主要承受剪切应力和剥离应力，剪切应力是损伤起始的主要原因。当被粘物材料类型不同时，应力分布规律呈现明显的不对称偏移。搭接形式主要影响失效区域的位置分布，环境参数主要影响混合失效模式下各种断裂形式的面积比例关系。
