Brandl S., Hauer I., Priebsch H., Bartosch T., Volkwein S.

To predict and analyse the acoustical behaviour of complex structures at higher frequencies the field of deterministic analyses methods like FEM or BEM has to be left. In this paper the energy based statistical approach called Statistical Energy Analysis (SEA) is used. To optimize acoustic packages of vehicles a definition of interior equipment (trim) in SEA models is required. One possibility is to use absorption, damping and insertion loss as parameters for the modelling of each trim part. Using this definition all different trim parts can be described through the same type of parameters, which is a big advantage of this rather abstract approach. In defining optimal acoustic packages for vehicles, engineers face many problems. Definition of acoustic packages is extremely time critical and changes of the geometry of the vehicle have to be avoided in the development process. Furthermore, acoustic packages are limited by weight and cost requirements. Having knowledge about areas, where a change of trim behaviour has a large influence on the SPL in the passenger compartment, is extremely helpful during defining acoustical packages. To provide this information a method using a mathematical sensitivity analysis had been developed. This method computes influences of trim parameters (absorption, damping and insertion loss) of different trim parts on the SPL. A detailed description of this method and its mathematical background will be given in this paper. Through principle examples the developed method will be illustrated and verification will be done using a full vehicle model. Definition of a mathematical optimization, which is based on this method, will be a scope of future work.