Design for NVH: Topology optimization of an engine bracket support

Noise Vibration and Harshness (NVH) issues are proven to be the main drivers for customer dissatisfaction in the latest years. This work relies on the framework of Design For X (DFX), specifically, Design for NVH. Main goal of this work was to perform a Topology Optimization (TO) of an engine bracket based on its vibrational behavior, in order to reduce the vibrations transmitted from the engine to the chassis and, consequently, improving the comfort for passengers. In particular, the target function was defined with the aim of increasing the first natural frequency of the bracket, whereas the bracket mass reduction was considered as a constraint function for the TO process. The vibrational characterization of the bracket was based on Frequency Response Function (FRF) analyses which, conducted via FEM (Finite Element Method), allowed to identify the resonant frequencies of the different bracket configurations built up during the TO. The FEM models included the cylinder head, with the related engine bracket support under optimization; the latter is connected to the bracket on which the simulation load was applied. The TO turned out to be effective in lowering the mass of engine bracket support of nearly 20% and, at the same time, increasing the first natural frequency of nearly 10%, this latter result was sufficient to guarantee an improvement of the comfort for passengers.