Abstract
The aim of this work is to model and characterize green anode paste compaction behavior. For this purpose, a nonlinear viscoplastic constitutive law for compressible materials, based on the finite strain theory and the thermodynamic framework, was used. An experimental study was carried out to characterize axial and radial behaviors of the anode paste. To this end, simple compaction tests using a thin steel instrumented mold were performed at a temperature of 150 °C. Results of these experiments brought out the nonlinear mechanical behavior of the anode paste. Furthermore, they showed the importance of its radial behavior. The constitutive law was implemented in Abaqus software through the user’s material subroutine VUMAT for explicit dynamic analysis. An inverse analysis procedure for material parameters identification showed that the model predicts compaction tests results with a good agreement. In order to assess the constitutive law predictive potential in situations involving density gradients, compaction tests using complex geometries such as slots and stub holes were carried out. Finite element simulation results showed the ability of the model to successfully predict density profiles measured by the X-ray tomography.
Highlights
The Hall–Héroult process, used for aluminum production, is characterized by several complex multiphysical phenomena such as thermo-electromechanical, electrochemical, and magneto-hydrodynamic problems
The material parameter η(IIIFp ) represents the viscosity of the whole anode paste, which evolves during the compaction process
In order to characterize the mechanical behavior of the anode paste, an experimental study based on compaction tests using a flexible mold wall was carried out at 150 ◦ C
Summary
The Hall–Héroult process, used for aluminum production, is characterized by several complex multiphysical phenomena such as thermo-electromechanical, electrochemical, and magneto-hydrodynamic problems. In [3], the vibrocompaction of the anode was experimentally studied at laboratory scale and a dynamic model taking into account the anode’s stiffness evolution was proposed In these two works the rheological behavior of the anode was not investigated. The authors investigated only the anode axial behavior since a rigid mold was used in their experimental study From another standpoint, the anode paste’s composition is similar to materials like asphalt mixtures and ramming pastes. This work aims to investigate anode paste’s axial and radial behaviors during the compaction process To this end, an experimental study using a steel thin-walled mold was carried out at 150 ◦ C. Finite element simulation predictions for compaction tests with complex geometries, are compared to experimental trends
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