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Optimizing the Structure of a New Magnesium Transmission Housing Using the Fe Method
Published June 16, 1998 by Verlag Des Verein Deutscher Ingenieure GmbH in Germany
Event: Vehicle Transmissions 1998
For the development of transmissions for high-performance vehicles a lot of criteria have to be considered. The paper presents the step-by-step improvement of the stiffness and strength of a new Audi magnesium transmission case for passenger car engines of the upper power range by using the finite element method and the simulation of operating strength. The analyses and tests were realized in a cooperation of Audi AG and the Technologie Zentrum Steyr TZS of the Steyr Daimler Puch AG- Antriebstechnik.
The FE model of the transmission consists of all cases, covers, bolts, bearings, shafts and gears. It is connected to an engine model. The stiffness of the roller bearings is determined by an iterative procedure, which considers the deformation behavior of the transmission cases and shafts. The total model is used to compute the stresses and deformations for the forward and back gears.
The flange area is excited by the engine''s vibrations. Therefore, the eigenfrequencies are determined and, if necessary, increased to uncritical values. In practice this means usually that considerable design modifications are required.
The strains in the flange area of the transmission/engine were measured in a vehicle during driving condition. Basing on the measurements, a loading cycle was derived which was used for the laboratory test as well as for the fatigue simulation. The damage calculation considers the interaction of the multiaxial loads.