Abstract
Application of electric current pulses during plastic deformation changes the mechanical behavior owing to the electro-plastic effect. The effect of electric current pulses on the Al5052 alloy is investigated in this study. In order to demonstrate the advantages of passing electric current pulses through a metal sheet during the forming process, a uniaxial tensile test with an electric current pulse was carried out using a self-designed device; this device can apply a 2-kA electric current pulse to the specimen for a short period (>100ms). The electric current increases the temperature of the specimen due to Joule heating. It is, therefore, necessary to decouple the thermal effect from the overall behavior to understand only the contribution of electric current in the mechanical behavior. Firstly, an electro-thermo-mechanical finite element study of an electrically assisted uniaxial tensile test of Al5052 alloy is performed to isolate the thermal effect. The simulated results yielded the thermal effect due to the electric current. By comparing the experimental and simulated results, the contribution of electric current is decoupled from that of thermal effect. The electric current-dependent material model is implemented into the commercial FEM code LS-DYNA using user-defined material(UMAT) subroutine. The electric current-dependent material model was used to simulate the electro-mechanical finite element analysis of the high-speed forming of an aluminum sheet with electric current pulse. Simulation results were compared with experimental results at several applied electric currents to evaluate the accuracy of the UMAT. The present work can be utilized to develop simpler constitutive models for the mechanical behavior of metals subjected to a pulsed electric current.
Highlights
The demand for high strength steels and aluminum alloys is increasing in the automotive industry to improve the efficiency of the fuel and performance
Change of flow stressexperiments of Al5052 alloy sheet subjected to singleThrough current pulse this studies, the following conclusions were obtained
5.ofConclusions uniaxial tensile state was analyzed through experiments and numerical simulations
Summary
The demand for high strength steels and aluminum alloys is increasing in the automotive industry to improve the efficiency of the fuel and performance These materials pose difficulties in industrial utilization because of their limited formability, e.g., increase in forming load, reduction in die life and occurrence of spring back after the forming process, in an environment of typical room temperature. It is popular as hot stamping, forming at an elevated temperature can improve formability (e.g., decrease in forming load and removal of spring back). An improved forming process for aluminum alloys and ultra-high strength steels is required.
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