Investigation On The Laser Shock Adhesive-Clinching (LSAC) Of Cu/Al Foils

With the rapid development of modern industry,the concept of lightweight design is attracting more and more attention.Mixed use of multi-material is an important and effective way of structure lightweighting and material properties compound.In the field of sheet joining,chemical adhesive bonding characterized by adhesion and bonding,and clinching based on plastic deformation principle,have become the main multi-material mixing methods,due to their easily joining of dissimilar materials with different melting points and different bonding properties,and showing increasingly irreplaceability.The Laser Shock Adhesive-Clinching(LSAC)technology is to make embedded interlock structure with pre-gummed double layer foils through plastic deformation by laser shock forming technique,then obtain high quality adhesive-clinched hybrid joints,which has significant advantages in the field of microscale metal foil joining and dissimilar foil joining.In this paper,by combining experimental research and numerical simulation,the forming criterion of hybrid joints,the effect of adhesive layer,the joining strength and failure process of hybrid joining between double layer foils and perforated stainless steel sheet,and the mechanical behaviors of joint under loads are systematically studied,the main contents of this paper are as follows:(1)Investigation of hybrid joint formation criterion.The cross section characteristics of the foil adhesive-clinched hybrid joint are observed,materials flowing behavior during joint forming is analyzed,the effect of various process parameters on LSAC forming effect is investigated,forming mechanism and defects of the hybrid joint are revealed.The addition of adhesive makes the distribution of loads on metal foils more uniform,but it is also easy to cause"adhesive pocket" at the undercut,effect the forming of interlock structure;(2)Investigation of the adhesive layer effect in the forming process.The behavior and effect of adhesives during LSAC process are analyzed;the mechanical response of uncoated and coated double layer foil under laser shock load is contrasted by numerical simulation and the effect of adhesive on foil forming is analyzed;the effects of adhesive viscosity and coating thickness on foil adhesive-clinched hybrid joint forming are investigated.The addition of adhesive prevents the formation of gaps caused by the foil impact,meanwhile it can absorb instantaneous load and release it smoothly,so that cause the high-frequency vibration of the whole structure,reduce the forming resistance of foil;(3)Investigation of hybrid joint strength and failure process.The anti-shearing and pealing ability of single clinched joint,single bonded joint and adhesive-clinched hybrid joint is contrasted and analyzed;the effect of process parameter and adhesive state on the joining strength of hybrid joint are investigated;the failure process and damage modes of hybrid joints during shearing and pealing tests are analyzed.The anti-shearing and pealing abilities of hybrid joint are quite improved contrasting to the two single joint;in shearing test,the adhesive bonding of hybrid joint fails first,then follows the clinching;while the adhesive bonding failure occurs during the whole pealing test,and the clinching fails in the middle of the test.LSAC fits with the purpose of lightweight design,provides a new way for the mixed use of multi-material,realize the adhesive-clinched hybrid joining of similar or dissimilar foil,solve the gap between two foils in the laser shock clinched joint and the joining strength has increased significantly contrasting to single joining method,which has a broad application prospect in the microscale manufacturing and other fields.