Porous material modelling in the automotive industry is gaining more importance due to the ever increasing need for reducing the weight of the car body. This trend towards weight reduction makes it all the more important to optimize acoustic treatments. Extensive research has been done on understanding the physical behaviour of porous materials and their applications. However, when it comes to design, efficient predictive tools are needed in order to allow industrial applications to be performed at a reasonable costs, i.e. time and computation resources. During the product development cycle for the computations with trim body, a good correlation can be found between the measurements and the simulations in the low frequency region. But there is more effort needed in understanding the physical behaviour of trim components when coupled with structural parts, to improve prediction accuracy in the mid frequency region. Finite element techniques are widely used in computing trimmed vehicle bodies but modelling of poroelastic materials frequently requires refined meshes. This implies an increased amount of resources needed to solve the problem, both in terms of computational time and memory allocation. As a consequence, the computational costs increase substantially when a fully trimmed car body is analysed and compared to a body-in-white structure. This paper discusses one particular aspect in the modelling of trimmed vehicle bodies, namely the coupling conditions along the surfaces where the trim and the sheet metal are interfacing. These conditions are known to vary for a number of reasons, mostly production related, and bring in sources of variation among similar car bodies leading to a higher degree of uncertainty in the NVH behaviour, potentially affecting the possibilities of optimizing the overall system performance. In this paper, an investigation of the interfacial boundary conditions in general and the partially bonded and partially un-bonded coupling conditions in particular, will be discussed. The sensitivity to variations in the contact, both area and location will be illustrated, in order to increase the level of understanding in the modelling of the trim components, when compared by numerical simulations on a CAE model and a simplified test set-up.
Finite element formulation and implementation of poroelastic materials in an unbonded case
2012
11 Seiten, 19 Bilder, 3 Tabellen, 15 Quellen
Aufsatz (Konferenz)
Englisch
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