Search Results

Porous materials are extensively used in the construction of automotive sound package parts, due to their intrinsic capability of dissipating energy through different mechanisms. The issue related to the optimization of sound package parts (in terms of weight, cost, performances) has led to the need of models suitable for the analysis of porous materials' dynamical behavior and for this, along the years, several analytical and numerical models were proposed, all based on the system of equations initially developed by Biot. In particular, since about 10 years, FE implementations of Biot's system of equations have been available in commercial software programs but their application to sound package parts has been limited to a few isolated cases. This is due, partially at least, to the difficulty of smoothly integrating this type of analyses into the virtual NVH vehicle development.

As the legislation for pass-by noise (PBN) has recently become more stringent, car manufacturers face again a challenging task to reach the new SPL objective (70dB(A)). A good design of the engine bay is therefore required to sufficiently attenuate the noise coming from sources as the engine and the intake. This involves proper design of the engine bay's panels including apertures, and a good selection of the type and location of acoustic treatments. For a given engine bay design, the PBN SPL results can be obtained with a PBN test or by an equivalent simulation. Using simulation models it is possible to create the perfect test environment virtually and moreover to obtain acoustic results for a large number of designs upfront of any actual testing or prototype.

Typically, in the automotive industry, the design of the body damping treatment package with respect to NVH targets is carried out in such a way to achieve panel mobility targets, within given weight and cost constraints. Vibration mobility reduction can be efficiently achieved thanks to dedicated CAE FE tools, which can take into account the properties of damping composites, and also, which can provide their optimal location on the body structure, for a minimal added mass and a maximized efficiency. This need has led to the development of different numerical design and optimization strategies, all based on the modeling of the damping composites by mean of equivalent shell representations, which is a versatile solution for the full vehicle simulation with various damping layouts.

The present work explains an innovative design methodology that allows efficient optimizations of vehicle body panels and treatments towards shorter development time and improved vehicle Noise and Vibration Harshness (NVH) characteristics. This tool named GOLD (Genetic Optimization for Lighter Damping), internally developed by Rieter Automotive, can be embedded into vehicle Computer Aided Engineering (CAE) design flow and can be then used in providing design and platform component sharing guidance information before prototype vehicles are available. GOLD is able to detect the optimal design of vehicle panel shape and damping packages with respect to NVH targets, by means of vibro-acoustic simulations. The core of this tool are the Genetic algorithms (GAs) which are heuristic methods which have been already successfully used, in several research fields, to solve search and optimization problems with a very large number of variables.