Friction Lap Joining Of Aluminum Alloy To Resin-based Composites

Lightweight has become a significant developing direction in aerospace,rail transportation and other fields because of its advantages such as reducing fuel consumption,improving efficiency and consuming costs.The dissimilar joining of aluminum alloy and the resin-based composite has attracted great attention because it can meet the demand of lightweight considerably.However,due to the huge property difference between the two materials,it is difficult to obtain a high-quality joint.The existing joining technology is limited in process and it is difficult to attain the high strength joining.In addition,there is also an increasing demand for the joining of continuous fiber resin matrix composites.Therefore,the continuous carbon fiber reinforced composites(CFRTP)and 5052aluminum(5052Al)alloy are utilized as the research objects,Friction lap joint(FLJ),a variant of friction stir welding(FSW),is employed to explore the joining process,joining mechanism and mechanical properties of metal and composites.The different enhancing methods are utilized to improve joint strength.The surface of 5052 Al was rough and porous by laser processing treatment.A strong FLJ joint of CFRTP and 5052 Al was achieved via the laser processing treatment.The tensile shear force increased from 2.85 k N to 4.13 k N,with an increasing rate of 45%.The bonding mechanism was mainly mechanical interlocking and chemical bonding between laser processing 5052 Al and CFRTP.The surface state of 5052 Al was changed by laser processing,and the force between 5052 Al and CFRTP was increased by chemical bonding,the defects were reduced and the joint strength was improved.The joint strength of CFRTP and 5052 Al increased obviously via the aluminum surface silane coupling treatment.The tensile shear force was improved from 2.85 k N to 6.83 k N,with an increasing rate of 140%.The joining of 5052 Al to CFRTP was achieved in the silane coupling layer assisted by covalent chemical bonding and hydrogen bonding.The silane coupling treatment makes the formation of chemical bonding more easily,resulting in a decrease of defects and the increase of interface joining tight.The combination of FLJ with silane coupling treatment for the joining of plastic-based materials to metal shows a considerable advantage.A hybrid welding method combined riveting with friction lap joining was proposed to achieve a high-quality joint of 5052 aluminum alloy and resin-based composites.In the condition of high strength and light-weight,the tensile displacement of the joint before failure was 212% higher than that of the traditional riveting.This was a comprehensive result of the improvement of stress concentration,the increase of the joining area,the increase of the tightness of the interface and the shear resistance of the rivet.Mechanical interlocking and chemical bonding were the main joining mechanisms of hybrid welding.Hybrid welding made that the joints not only had the high strength of riveting but also had the characteristics of large joining area and uniform stress distribution of friction lap joining which further improved the reliability of the joint.Therefore,the hybrid welding of riveting and friction lap joining has great potential in obtaining a reliable dissimilar metal/resinbased composite joint.