Integrated Virtual Approach for the Optimization of Vehicle Sound Packages 2009-26-0053
Generally all OEMs have a distinctive approach in designing their sound packages. Considering the complexity and combination involved in this process, there is no general valid scheme, although there tend to be some common blocks. Also as automotive manufacturers face strong demands to cut CO2 levels there is a trend to reduce prototypes and introduce limitations on weight of sound controlling materials. The supplier of the sound package must therefore be able to support the OEMs in taking design decisions early, quickly and based just on drawings, or even just on sketches in the concept phase.
A proposed way forward in designing fast and cost-effective sound packages is by skillfully combining target setting, material characterization measurements, virtual prototyping and optimization tools.
The solution should not only be acoustically effective, but also lightweight and cheap. Material characterization is dictated by design methodologies that allow accurate and efficient physical representation of not only damping material, in terms of their mechanical properties, but as well of porous materials in terms of their acoustic absorption and transmission properties. At material and component level, for medium and high frequencies, a transfer matrix approach using Biot's equations can be used to calculate the above-mentioned performances for multi-layered trim parts. At a vehicle level it well assessed the usage of Finite Elements (FE) to analyze the structure borne noise performance at low frequency; this practice can be enriched by the implementation of damping and porous models to reproduce trimmed bodies. On the other hand SEA is used for air borne noise analysis at medium and high frequencies to support in the target cascading and achievement process. It is shown here how the material characterization, modeling and simulation can be united with optimization procedures (e.g.: Genetic Algorithms) to define the optimal combination of vehicle panel shape, damping material distribution, and layout of sound absorbing multi layered trim parts.