Conception et fabrication d’un banc d’essai pour la mesure du coefficient de friction à haute température des alliages d’aluminium

Abstract

With the aim of making motor vehicles lighter and better, new aluminum forming processes are being developed. This study focuses on those that exploit the superplasticity properties of the AA8053 alloy (processes called SPF for SuperPlastic Forming). They allow very high deformation rates, making it possible to manufacture body parts with complex geometries that cannot be obtained by traditional forming methods. In order to optimize these processes and increase their productivity, the industry often uses finite element simulations. In order to be representative of the reality, these simulations require various parameters to be filled in, in particular the coefficient of friction (COF) between the aluminum of the formed part (which is covered with a layer of solid lubricant, boron nitride in this study) and the steel of the die. A review of the literature has shown that there is very little information on the behaviour of the COF under the conditions of interest. Even more so as it also showed that there is no reference value, but that COF is highly dependent on the test conditions. Moreover, no conventional method is defined to measure this quantity in a framework that reproduces the temperature, pressure and contact conditions found in SPF processes. A test bench was therefore specifically designed during this project. It is a unique machine that allows measurements to be made under conditions never tested before, and has great potential for exploring the field of friction and lubrication at high temperatures. It has made it possible to carry out a qualitative and quantitative study on COF according to the different parameters that have been identified as having the most influence on its value, temperature, contact pressure, speed and sliding distance. The analysis of the results showed a strong correlation between COF and the temperature and sliding distance variables. The other two parameters have a more moderate influence, but depending on the conditions can be significant and play a major role in the optimization of an SPF process.

Date	30 Mar 2021
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Mohammad Jahazi (Supervisor) & Hakim A. Bouzid (Co-supervisor)