| Structural bonding technology has been widely used with the emergence of the connection problem of different materials and the concept of lightweight.Traditional connection methods,such as welding and riveting,have various shortcomings in practical application: welding will cause defects on the component surface;riveting will cause stress concentration.The appearance of structural bonding technology overcomes the limitations of traditional connection methods such as welding and riveting,so it is gradually applied to different fields.In the practical application of structural bonding technology,it is often limited by the structure size and environmental conditions.The mechanical properties of the adhesive will be affected by the width of the adhesive layer and different environmental conditions.The adhesive will be aged in the long-term hygrothermal environment,and eventually the bonding structure will fail.Therefore,in order to make the bonding technology more effective in different fields,it is necessary to study the influence of different adhesive width and complex environmental conditions on the mechanical properties of the adhesive.Based on the above reasons,the main contents of this paper include:1.The mode I loading experiment was carried out on the double cantilever beam specimens with the width of 5 mm,6 mm and 25 mm.The data were processed by the compliance method,and the load displacement curve,R curve and adhesive mode I fracture energy of the specimens with different width were obtained.Firstly,the mode I fracture energy was compared with the mode I fracture energy obtained by consulting the literature,which proved the accuracy of the experimental process.After that,the results of different width DCB specimens were compared.Finally,the failure mode of the specimen is mixed failure by observing the failure surface of the specimen.2.According to the follow-up research plan and the water absorption curve of double cantilever beam adhesive layer with different width,the DCB specimen with width of 5 mm was selected for aging test.After that,mode I loading test was carried out on the specimens before and after aging.The data were processed by the compliance method,and the results of mode I fracture energy of the adhesive before and after aging were obtained and compared.3.Through the method of finite element simulation,the material parameters were defined to establish a two-dimensional double cantilever beam model.The loading process of DCB specimens with different width and before and after hygrothermal aging is simulated.The R curve and mode I fracture energy of simulation were compared with the experimental results.It was found that the peak load of the double cantilever beam decreased with the decrease of the adhesive layer width and the influence of hygrothermal environment.However,the mode I fracture energy of the adhesive only decreased due to the influence of the hygrothermal environment,and it doesn't change due to the change of the adhesive layer width.The simulation results showed that the mode I fracture energy of adhesive obtained by simulation and experiment was in good agreement.Through the establishment of two-dimensional DCB model,it could accurately simulate the mode I loading process of DCB specimen,and verify the accuracy of the finite element model.The research results of this paper could provide help for the application of structural bonding technology in the future,and provide reference for the width design and working environment selection of adhesives. |
PDF Full Text Request