This paper was produced for the 2019 NAFEMS World Congress in Quebec Canada
The NVH (Noise Vibration Harshness) behaviour of injection-moulded thermoplastic parts (e.g. automotive interior components like instrument panels, centre consoles or glove boxes) can be influenced by changing the material itself and its microstructure orientation. In order to reduce the costs and efforts of real sampling with different materials and conducting laboratory tests with different fillers, fibres and process parameters, the structure-borne sound behaviour of components can be simulated in the early stages of product development using CAE software. Based on the coupling of process simulation with structural simulation an integrative method for the NVH simulation of thermoplastic parts with anisotropic microstructure will be developed and verified for polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) material within this paper, by using the CAE software tools Moldflow, Digimat, Abaqus and Actran in combination with Matlab.
For NVH simulation it is necessary to get different parameters of the thermoplastic material. Besides density, modulus of elasticity and Poisson’s ratio, it is also important to investigate the viscoelastic material parameters for the modelling of the damping behaviour. Viscoelastic material parameters are determined by a dynamic mechanical analysis (DMA), which also the frequency- and temperature-dependent mechanical dissipation factor is calculated from. The dissipation factor and the density have a high influence on the sound pressure level in the lower frequency range. In addition to the viscoelastic and the isotropic material parameters, the anisotropy also has a significant influence on the acoustic behaviour of moulded parts due to orientations of fibres, fillers or foam structures. Such anisotropies can be influenced by various process parameters and can also be simulated with an integrative NVH simulation. Basically, this integrative NVH simulation approach also offers the opportunity to develop new materials digitally. Ad interim, an iterative material development could take place virtually, followed by a real compounding and sampling of moulded parts. Further these new materials could improve the NVH quality of products and components.
|Date||18th June 2019|