Browsing by Keyword "Magnesium alloy"
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Item Experimental and numerical study of electromagnetic forming of AZ31B magnesium alloy sheet(2009-05) Ulacia, I.; Hurtado, I.; Imbert, J.; Salisbury, C. P.; Worswick, M. J.; Arroyo, A.; PROMETALWrought magnesium alloys are interesting materials for automotive and aeronautical industries due to their low density in comparison to steel and aluminium alloys, making them ideal candidates when designing a lower weight vehicle. However, due to their hexagonal closepacked (hep) crystal structure, magnesium alloys exhibit low formability at room temperature. For that reason, in this study a high velocity forming process, electromagnetic forming (EMF), was used to study the formability of AZ31B magnesium alloy sheet at high strain rates. In the first stage of this work, specimens of AZ31B magnesium alloy sheet have been characterised by uniaxial tensile tests at quasi-static and dynamic strain rates at room temperature. The influence of the strain rate is outlined and the parameters of Johnson-Cook constitutive material model were fit to experimental results. In the second stage, sheets of AZ31B magnesium alloy have been biaxially deformed by electromagnetic forming process using different coil and die configurations. Deformation values measured from electromagnetically formed parts are compared to the ones achieved by conventional forming technologies. Finally, numerical study using an alternative method for computing the electromagnetic fields in the EMF process simulation, a combination of Finite Element Method (FEM) for conductor parts and Boundary Element Method (BEM) for insulators, is shown.Item Numerical Simulation of the Upward Continuous Casting of Magnesium Alloys(2005-11) Landaberea, Aitor; Pedrós, Pablo; Anglada, Eva; Garmendia, Iñaki; CIRMETALThe continuous casting of magnesium alloys in vertical upward direction is a novel technology which can be employed for the production of semi-finished materials circumventing the main disadvantages of using conventional casting processes since the risks of burning and explosion are practically eliminated. The present investigation deals with the simulation of the upward continuous casting of round billets of magnesium alloys. The equations for the flow field with heat transfer are numerically solved by a finite volume method and the solidification is accounted via an enthalpy-porosity formulation where the mushy region is modeled as a pseudo porous medium. The obtained temperature distribution is then used as input for a thermo mechanical analysis to determine the stress field in the billet during the casting process. Several configurations have been simulated and comparison of computed results with available experimental data is provided.