Numerical Simulation And Experimental Verification Of Joule Effect In Gleeble Thermo-Mechanical Simulating Tests

The numerical simulation of the Gleeble dynamic test is usually carried out with the definition of homogeneous temperature in the specimen. But in fact, joule effect will lead to an internal temperature gradient, which will affect the mechanical behavior of the material. In this research, in order to refine the numerical simulation of dynamic tests on Gleeble through considering the Joule effect, a model of thermal-electric coupling for hat-shaped specimen was constructed with Abaqus.The coupled thermal-electrical simulation of hat-shaped specimen was constructed. The definition of the electrical charge and the influence of boundary conditions were discussed.Modeling in Abaqus was verified using a simplified rectangular sample by comparison with results from experimental test performed on a Gleeble machine.The heating step of a hat-shaped specimen on the thermo-mechanical machine Gleeble was simulated for the temperature distribution. The results showed that the temperature distribution was not uniform when the current was cut off and dynamic test started. The temperature difference reached 200K and a temperature gradient of 14K/mm existed in the shear zone. The simulation results obtained can be imported to the mechanical simulation step as predefined temperature field, which can reflect the impact of the internal temperature distribution on material's mechanical behavior.In addition, an extended analysis was specially focused on the prediction of the phase transition temperature when the resistance curve was calculated during validation tests on the Gleeble. The curve of resistivity was calculated by Gleeble experimental data and the phase transition temperature was obtained by the singular point, which was verified by radial thermal expansion tests. This methode is particularly relevant for the materials that are not subject to important variations in volume such as titanium alloy. It is also interesting for evaluating phase transition temperatures under different thermal cycling conditions. Moreover it can be used to study the effects of current on phase transition and the conducting mechanisms.