Coupling of component models with mismatching interfaces for an efficient NVH vehicle design

The NVH optimization of new vehicle models can in principle only be carried out in a relatively late stage of the development process, when the geometrical data (CAD) are available and can be used to generate detailed Finite Element (FE) models of the car body. Unfortunately, in this stage of the development process most of the geometrical data are already fixed and countermeasures are limited and expensive. In order to be able to evaluate design concepts in an earlier conceptual stage of the development process existing models of similar predecessor vehicles must be used leading to techniques such as “mesh-morphing” or “concept modelling” (see for instance [1, 2]). Here, a different approach is investigated based on a substructuring technique. In principle the coupling of the component-structures coming from different models would require post-processing in order to obtain compatible interface degrees-of-freedom (DOFs), an operation which in most cases must be carried out manually and is very time consuming. This paper presents a novel substructuring approach that tackles a continuous interface by only considering a small set of coupling DoFs. This approach employs the discretisation of interfaces between structural parts or structural-acoustic domains in terms of pivotal points and patches. In this manner, the requirement of spatial continuity between the models of the separate substructures is no longer needed and subsystems with incompatible interfaces can be coupled. Thus, an efficient vibro-acoustic design optimisation procedure for components shared by different vehicle models, such as the car floor, is enabled. It will be shown that a single car floor model can be successfully coupled with different upper-body structures, even when they have a different location of coupling DoFs.