The Influences Of Laser Surface Treatment On The Bonding Interface Of Metal/Composites

Fiber reinforced polymer(FRP)has attracted researcher’s attention because of the advantages of high specific strength,high specific modulus and anti-fatigue.It can be bonded with metal to form a new material.This new material,which can provide full play to the excellent properties of composites and metals,has higher damage tolerance and fatigue limit.It has become one of the main materials for aircraft manufacturing.In addition,the bonding method of composites and metals can also be applied to the strengthening and repairing of large machinery and structures.It can significantly improve the load capacity of the structure.The bonding between composites and metals belongs to heterogeneous materials bonding that the properties of the two bonded materials are quite different.The bonding layer is easily damage and the whole bonding structure will be destroyed.The bonding strength can be improved by modifying the metal surface properties,which plays a positive role in ensuring the reliability of metal / composite bonding structure.The research status and theories were comprehensively reviewed on the heterogeneous materials bonding.The aluminum alloy surface was treated by laser to obtain the different surface morphologies by changing laser treatment parameters.Then,the single lap specimens that were prepared by co-curing process were completed by tensile test.The relationship between laser power,scanning rate,spot spacing and bonding strength was studied.Secondly,the process of laser surface treatment was simulated by laser theory model,heat transfer equation and boundary condition using COMSOL software.The temperature field distribution was obtained by laser surface treatment process.The surface roughness was taken as the evaluation parameter.The influences of different scanning rate and spot spacing on the surface topography were analyzed.Finally,the unit cell models of bonding layer were established by the simulated surface profile.The bonding strength was calculated by the stress analysis of unit cell..The results showed that the laser surface treatment would form a regular morphology on the surface of aluminum alloy,which could increase the bonding area and enhance the mechanical bonding.Hence,the damage of the bonding area could change from interface damage to mixed damage that lead to the increasing of bonding strength.It was found that the laser spot spacing and spot diameter should be equal to improve the bonding strength,and meanwhile a high scanning rate should be used within a reasonable range.