Simulation of the thermal profile of a mushy metallic sample during tensile tests

Strain measurement is a major challenge in tensile tests performed in a mushy state. While non-contact technique devices like the laser speckle extensometer remain the most reliable facility for this type of measurement, these devices are often not readily available. So the strain measurement is usually performed by determining the length of the ‘‘hot zone’’ of the sample. This is possible with the help of the thermal profile associated with the sample under heating. The purpose of our work is to develop a numerical model to predict the thermal profile of a A356 aluminum alloy sample at high temperature, taking into account the device geometry and characteristics. We simulate the joule heating effect using the FE software Abaqus. Our model takes into account the grips of a Gleeble machine, the thermal contact conductance and electrical contact resistance at the grip-sample interfaces, as well as the convection heat transfer on the free surfaces of the system. These thermo-physical properties have been determined by fitting the experimental thermal profile obtained at 545°C. The model was then used to simulate the temperature profile on the sample at higher temperatures (when the sample is in the mushy state). The thermal profile predicted by our model is in excellent agreement with the profile obtained experimentally.