铝锂合金/FM94胶接接头内聚力模型参数识别

为了正确预测铝锂合金/FM94胶接接头的强度与失效特征，采用ABAQUS软件建立胶接接头的内聚力仿真模型. 针对内聚力模型关键参数的确定问题，利用材料力学和断裂力学相关理论推导I、II型断裂失效形式下断裂能的计算公式；通过实验测定FM94胶接铝锂合金标准双悬臂梁（I型失效）和三点弯曲试样（II型失效）的力-位移曲线，计算并确定不同失效模式下的内聚力模型参数；采用三角形内聚力理论模型和所确定的模型参数进行双悬臂梁标准试样、三点弯曲标准试样及单搭接接头的强度与断裂失效过程的数值仿真. 结果表明：仿真结果与实验数据较一致，在不同加载速率下断裂载荷最大误差为4.4%，断裂位移最大误差为3.8%，验证内聚力模型参数确定方法合理，模型参数正确.

Parameter identification of cohesive zone model for Al-Li alloy/FM94 bonded joints

The cohesive zone model of the bonded joint was established by ABAQUS software, in order to correctly predict the strength and failure characteristics of Al-Li alloy/FM94 bonded joints. The calculation formulas of the fracture energy under the failure modes of type I and II were deduced based on material mechanics and fracture mechanics, aiming at the identification of the key parameters of the cohesive zone model. The force-displacement curves of FM94 bonded Al-Li alloy standard double cantilever beam (type I failure) and three-point bending specimen (type II failure) were measured experimentally, and the cohesive zone model parameters under different failure modes were calculated and determined. The numerical simulations of the strength and fracture failure process of the double cantilever beam standard specimen, the three-point bending standard specimen and the single lap joint were carried out by using triangular cohesive theory model and the determined model parameters. Results show that the simulation results are in good agreement with the experimental data, and the maximum errors of fracture load and fracture displacement at different loading rates are 4.4% and 3.8%, respectively. It is verified that the cohesive zone model parameters are reasonable and the model parameters are correct.