Feasibility Study On The Forming Of AZ31 Magnesium Alloy Assisted By Magnetorheological Elastomer Support Mould

High strength metal sheets such as AZ31 magnesium alloy at room temperature or hot forming prone to rupture and forming limit shortage,seriously restricting its application in the important transport equipment structure thin-walled and lightweight,and unsupported or supported passive damping device damping force can not adapt to the change in the drawing force during the drawing delay,seriously reducing its forming performance.Therefore,it is proposed to use magnetorheological elastomer with variable stiffness and variable damping characteristics to design a support mould located inside the die to assist the sheet forming at the lower end of the sheet to reduce the flow stress of the material and improve the plasticity to enhance the sheet forming performance.Firstly,to study the deep drawing process of magnesium alloy sheet cylindrical parts,to analyze the stress state of the lower end of the magnetorheological elastomer supporting sheet assisted deep drawing,to establish the material flow stress model,and to reveal the influence of material flow on the wall thickness of the sheet.Secondly,to study the change of magnetocompressible elastic modulus under the shear mode of operation,to establish a macro-state visco-elastic model of magnetorheological elastomer,and to reveal the effect of magnetic induction intensity on magneto-compressible elastic modulus.Then,the response process of magnetorheological elastomer is elucidated,the support mould of magnetorheological elastomer is defined,the real stress-strain of AZ31 magnesium alloy is studied and calculated,and the magnetorheological elastomer suitable for the support mould is prepared using rubberbased composite micro-nano ferromagnetic particles and normal mechanical experiments are conducted to reveal the effect of current on the normal force.In addition,from the perspective of simulation and experimental corroboration,the numerical simulation and experiment of deep-drawing of common AZ31 magnesium alloy sheet cylindrical parts,the control results prove that the numerical simulation method of using the material intrinsic model is scientifically feasible.At the same time,the analysis of sheet stress,thinning rate and thickness distribution cloud,study proves that the magnetorheological elastomer support mould can improve the sheet forming performance in terms of reducing the material flow stress.Then,a mechanical model of the magnetorheological elastomer support mould is established and the transfer function characteristics are studied and analyzed to prove that the appropriate equivalent stiffness and high equivalent damping coefficient can effectively reduce the vibration amplitude of the system and thus make the system more stable and faster in response.Finally,the flexible system control idea of semi-active closed-loop control of flexible support force with real-time feedback of subsequent punching pressure is proposed.