Simulation And Experiment Study On Electrically Assisted Incremental Forming Process For Thin-walled Al-Li Alloy

2060 Al-Li alloy is a new kind of Al-Li-Cu alloy which has a lower density,high specific strength and elasticity modulus.As a light-weight material,it exhibits high potential in aerospace industry.However,2060-T8 Al-Li alloy exhibits relatively high resistance of deformation and poor plasticity at ambient temperature,which restricts forming complex parts by traditional cold-forming.In order to solve this problem,an electrically assisted incremental forming process,which combines the advantages of the electroplastic effect(EPE)induced by pulse current and the incremental forming,was proposed in this paper.The EPE could reduce the resistance force and the incremental forming would remarkably improve the forming limit of materials.In this research,the influence of pulse current on 2060-T8 Al-Li alloy,the establishing of material constitutive equation under pulse current condition,the finite element model and experiment of electrically assisted incremental forming process were studied.The main work of this paper includes the following contents:In order to study the influence of pulse current on 2060-T8 Al-Li alloy,the uniaxial tensile tests of specimens at different temperatures and current parameters were carried out.The tensile properties of material from ambient temperature to 200~℃ were obtained.Based on the tensile test results,a material constitutive equation was established which can describe the material behavior of 2060-T8 Al-Li alloy under pulse current condition well.An "electro-thermal-structure" multi-field coupling FE model for electrically assisted incremental forming was established by the finite element software ABAQUS.The user defined subroutine was developed to acquire the current density of nodes in the workpiece so that the yield stress consists of the pure EPE can be updated.The experimental plateform of electrically assisted incremental forming process was designed and built.The profile and wall thickness distribution of workpieces at ambient temperature and different current density condition were studied.The reliability of simulation model was verified by comparing with the experimental results.