The Deformation Of Welded 6063 Aluminium Alloy T-joints In Thin-walled Rectangular Hollow Section As Well As FEM Simulation

Aluminum alloy space frame is of crucial interesting for producing the light-weight automobile,which can reduce the fuel consumption and environmental pollution.The aluminum and its alloys can be used to manufacture the light-weight automobile due to their low density,well plasticity and high specific strength.Body space frame connected mainly by thin-wall hollow T-joint which only welded one side.The complicated mechanical heterogeneity of joint HAZ affects the deformation of frame in vehicle collision.It is necessary to investigate the deformation behavior of thin-wall hollow T-joint,and provide the basis for the joints of vehicle collision model.The 6063 Al-alloy single side T-joint and thin-wall hollow were investigated by combining mechanical test and finite element simulation based on the above issue as follows.In order to reduce welding defects on the mechanical properties of joint,following measures has been adopted:a)putting copper boards under the T type joint,b)putting copper bushing pipe in rectangle pipe and guiding arc board beside the welding seam before welding thin-wall hollow T-joints.Combining other suitable welding process parameters,good welded joints can be manufactured for mechanics test.The welded joint was divided into the welding seam zone,the dissolution zone,the over aging zone and base metal zone.Through the double-hole micro-shear test to measure T-joint district width and local mechanical properties,provided the basis for modeling material of T-joints finite element simulation.From the thin-wall hollow T-joint intercepted small T-joint,the small T-joint and biaxial tension test and clamping fixture were designed.Using the finite element simulation to determine the sample size and cable stayed angle,then the whole test was completed.The results show that the method can be used to evaluate the failure mode and deformation of single-side T-joint under different loading conditions,meanwhile,the accuracy of the small T-joint model was verified.Then T-joint was undivided and assigned the uniform material properties based on the precise model,and the equivalent model was established through the calculation to simplify T-joint materials modeling.Two kinds of T-joints were welded with thin-wall rectangular hollow section of 6063 Al-alloy,and their responses of load and deformation were measured in the bending and compression tests,and then analyzed their limit strength.By adopting finite element models, limit strength and deformation process of the T-joints were studied.The results show that stepped T-joint at bending load had no peak point on the response curve of load and deformation,but full-width T-joint at bending and compression load generates integral yield and then maximizes load.The load of overall joint yield was used to design limit load-carrying capacity of Al-alloy T-joints in thin-walled rectangular hollow section.And the softening in the welds and HAZ had much influence on the strength of the joints.