Thermo-mechanical finite element simulation of synchronizers with carbon friction linings under extreme loads

Synchronizers of manual and dual clutch transmissions face a huge variety of load parameters in practical application. Former research focused on the effects of engagements with usual medium to high loads. Latest practical experience shows that significant, different damaging effects occur, if extreme loads are applied to synchronizers especially with carbon friction linings. Extreme loads are closely linked to abuse by the drivers. Within a research project three synchronizers were experimentally investigated under extreme loads that led to total fail of the synchronizer system within 1. . . 20 cycles. The major damaging effects are plastic compressive deformation of the steel cone and wear of the carbon lining on the blocker ring. It is assumed that thermal stresses lead to compressive flow of the steel due to extreme temperature gradients and reduced yield strength by likewise extreme temperatures. The points covered in this thesis are: Further development of an existing parametric finite element model in ANSYS/APDL for the simulation of synchronizers with respect to thermo-mechanical interaction. The mesh has to be redefined to fit the requirements of extreme temperature and stress gradients remaining a parametric mesh. Set up post processing methods using MATLAB. • Determination of reference temperatures and stresses using the FE model at the experimental tests to verify the assumption of compressive flow within the steel cone. • Identify effects of synchronizer design, i.e. cone angle difference, and material parameters on the local distribution of surface temperature and contact pressure. II • Development of a quantitative correlation between simulation and experimental results with respect to plastic deformation of the steel cone and reduction of wear gap. • Transformation of the found correlation from simulation output into specific external load parameters such as surface pressure, sliding velocity and friction loss for the prediction of damaging effects without complex FE simulation. • Parametric studies on the effect of wall thickness of the steel cone.