Adhesive Bond Properties Study Of Aluminum Alloy For Automobile Body

Adhesive bonding is an efficient and reliable joint technology.It has good material adaptability and excellent mechanical properties and can be used to solve the joint problems of aluminum alloy materials for automobile bodies.In this paper,the bonding process of 5182 aluminum alloys will be studied from three aspects: surface treatment analysis,process parameter testing,and joint internal stress analysis.The main research contents are as follows:Firstly,the strength distribution of joint which was polished by different surface treatment was studied.The influence of sandpaper size and grinding method on the key parameters such as micro surface area and surface free energy were investigated.The results shown that,compared with the non-polished adherend,the grinding process increased the surface roughness and microscopic surface area of the base metal,strengthened the mechanical bite between the adhesive and the base metal,and increased the joint strength.Increased sandpaper size would improve the surface free energy and reduce the micro surface area.the optimal joint would appear when the adherend was polished by medium size sandpaper.Secondly,the mechanical properties of joints with different joint parameters were tested,and the effects of overlap length and adhesive thickness on joint mechanical properties were explored.The results showed that increased adhesive thickness would increase the bending stress at the end of the joint,thereby reducing the strength of the joint.Aluminum alloy adhesive joints had a limit load,the value of which was close to the yield load of the base metal.At the same time,there was a critical length.When the overlap length was less than the critical length,the joint could increase its strength significantly by increasing overlap length.When the overlap length approached or exceeded the critical length,the joint strength would reach the limit load.And the joint could not significantly increase its strength by increasing overlap length.At this time,the middle part of the joint could be designed as a glue-free zone,which provided a basis for the composite joint technology.At the same time,the residual rubber distribution coefficient ? was defined to quickly determine whether the overlap length reached a critical length.Finally,the FEM was used to analyze the internal stress distribution of the joints,and the influence of joint parameters on stress concentration was explored.The results showed that the internal stress of the adhesive joint concentrates at both ends of the joint,and the internal stress of joint middle part was small.Increased adhesive thickness would increase the stress concentration,and increased overlap length would reduce the stress concentration.For joints exceeding the critical length,the stress in joint middle part was close to 0.When the middle part adhesive layer is removed,the stress concentration of the joint was little affected.