Authors: Simone Fratti, Günther Pessl - BMW Motoren GmbH, Austria
With a decennial tradition in optimization, BMW has developed and standardized many optimization procedures in all fields of simulation like CFD, FEM, Multibody and Structural Dynamics when creating a new high performance Diesel engine.
Nevertheless, the achievement of the best solution in terms of air-born noise, cost and weight reduction is actually an open issue and generally highly time consuming. Hence, the presented work focuses on the problems correlated to noise reduction and particularly deals with automatic modifications of component features like structural ribs, which are widespreadly used in order to increase the stiffness and consequently modify the acoustic behavior of the whole engine. A modeFRONTIER workflow that automatically modifies position and dimensions of the ribs on an engine will be presented. It couples the ANSA pre-processor used for the direct morphing of features with the Nastran solver calculating the component’s frequency response.
By using this workflow and strategy it was possible to reduce the noise caused by the vibration of the component, maintaining at the same time the component’s weight within an acceptable range.