Analyse par elements finis des contraintes dans les assemblages par frettage.

摘要

The objective of this paper is to study the fatigue stress concentration for shrink fit assembly subject to a rotating bending load. With this assembly technique a shaft is inserted inside a roller whose inner diameter is smaller than the outer diameter of the shaft. By heating the roller and / or cooling the shaft, it is possible to assemble both parts effortlessly. To help the design, the finite element method can be used to evaluate the factor of stress concentration generated during the assembly. Several modeling techniques will be presented as axisymmetric modeling, 3D modeling with and without contact elements and a comparison with the analytical method. The singularity at the edge of this contact between the shaft and the roller makes modeling more difficult because it prevents the convergence of the results. The analysis method presented overcomes this problem in order to obtain convergent results. The results show that the use of a radius at the edge of the inner diameter of the roller reduces the fatigue life of the assembly. On the other hand, the addition of a groove on the face of the roller increases it. In order to validate the results obtained by the finite element method, two test benches were built to conduct fatigue tests in order to compare experiments to the analysis. The first test bench shows premature wear of bearings which forced to end the testing campaign. The second test bench shows good results, but the lack of setup repeatability and the limited number of tests have not yielded conclusive results. Although the two test benches were unable to give the desired results, some modifications are presented in order to improve performance.