Nils-Erik Hörlin

Vibro-acoustic modelling of anisotropic porous elastic materials: A preliminary study of the influence of anisotropy on the predicted performancein a multi-layer arrangement.

During the recent years considerable efforts have been spent on developing numerical models and performing the necessary characterisation of elastic, dynamic and acoustic properties of porous mater ...

Component mode synthesis using undeformed interface coupling modes to connect soft and stiff substructures

Classical component mode synthesis methods for reduction are usually limited by the size and compatibility of the coupling interfaces. A component mode synthesis approach with constrained coupling interfaces is presented for vibro-acoustic modelling. The coupling interfaces are constrained to six displacement degrees of freedom. These degrees of freedom represent rigid interface translations and rotations respectively, retaining an undeformed interface shape. This formulation is proposed for structures with coupling between softer and stiffer substructures in which the displacement is chiefly governed by the stiffer substructure. Such may be the case for the rubber-bushing/linking arm assembly in a vehicle suspension system. The presented approach has the potential to significantly reduce the modelling size of such structures, compared with classical component mode synthesis which would be limited by the modelling size of the interfaces. The approach also eliminates problems of nonconforming meshes in the interfaces since only translation directions, rotation axes and the rotation point need to be common for the coupled substructures. Simulation results show that the approach can be used for modelling of systems that resemble a vehicle suspension. It is shown for a test case that adequate engineering accuracy can be achieved when the stiffness properties of the connecting parts are within the expected range of rubber connected to steel.

Influence of Surface Porosity on the Radiated Sound From Multilayer Automotive Trim Components

Lightweight porous automotive acoustic multilayer trim components have been traditionally specified in terms of sound absorption and sound transmission loss performance targets. These targets are valid for airborne noise excitation only, in the medium to high frequency ranges. Unfortunately, this neglects the fact that in real-world vehicle applications, these components are also subjected to low-medium frequency structural vibration inputs from the mechanical components of the vehicle, which is typically an acoustic sound radiation problem.