| In recent years,with the development of lightweight vehicles,the use of new industrial materials in the automotive field has become more and more extensive,and the bonding technology has become the main technical means for the connection of emerging materials.Therefore,the research on structural adhesives is important in the connection of automotive structures.This work is mainly based on structural adhesives,simulating the post-curing temperature conditions and the high temperature and high humidity environment to assess the Mode II fracture energy of the structural adhesive.Then,Abaqus software was used to simulate the actual environment to achieve an effective prediction of the Mode II fracture energy of structural adhesives.In this work,the following three aspects were mainly carried out:1.Numerical simulation of failure behavior of adhesive layer based on CZM.In this part,the mechanical properties and failure behavior of the copper/epoxy adhesive/ferrite bonded structure under shear crushing load were analyzed by testing and numerical simulation methods.The adhesive was first tested by preparing standard test specimens(dumbbell specimens,Arcan test specimens),then the finite element model was established according to the CZM parameters measured by the test,and Finally,through the failure interface observation of the bonded structure,verified that the failure mode of the adhesive layer under the shear crushing load is cohesive failure;and the results of comparative experiments and simulations verify that the CZM is appropriate in the adhesive layer simulation process.This establishes a theoretical basis for the subsequent CZM to simulate the failure behavior of the adhesive layer.2.Analysis of the effect of post-cure curing for the Mode II fracture energy of structural adhesives.First,three post-cure temperatures and cure duration were selected to simulate the environmental conditions of actual industrial manufacturing.Quasi-static tests were performed on the ENF samples that exposed to different post-cure conditions to evaluate the performance of Araldite~?2015 adhesives.Then using finite element model(FEM)to simulated loading process of ENF specimen Finally,a parameter identification method is proposed to determine the optimal CZM parameters of the adhesive after curing at various temperatures,and compares it with the experimental result to prove the validity of the established numerical evaluation method.3.Analysis of the influence of hygrothermal environment on Mode II fracture energy of structural adhesives.Firstly,the theoretical moisture diffusion process of the adhesive layer is analyzed by the single Fickian model to determine the aging time of experiment and simulation.Then,the two aging environments(50 ~oC distilled water,50 ~oC 5%NaCl solution)are simulated by the constant temperature water tank to accelerating the aging process of the prepared adhesive ENF specimens,and then the Mode II fracture energy was obtained by a three-point bending test.Finally,Abaqus software and custom user subroutine were used to simulate the aging process of ENF specimens,and the accuracy of water diffusion during finite element simulation was verified by comparing analytical and numerical simulation results,and the comparison of the load-displacement curves of the experimental and simulation verified the accuracy of the loading process of the finite element model. |
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