Use of Sound "PHONONS' in the modelling and Optimisation of automotive acoustic systems in 3D

Automotive manufacturers demand components with an ever higher acoustic performance combined with lower environmental impact, tuned to the emerging EV market, and are pressured into reducing lead times and prototype investment. Consequently, there is a desire for enhanced simulation techniques, utilizing advanced methods. The three-dimensional aspect of many palliative treatments can be shown to afford significant benefits to their acoustic performance, both in their transmission loss and random incidence absorption characteristics. Virtual system engineering enables construction fundamentals to be created in CAD, but often acoustic treatments are chosen based on flat sample performance or simple power balance models. These do not tell the complete story. Current acoustic simulation techniques such as SEA, may present the model in a 3D environment to aid in visualization but, solving is done on a 2D matrix basis, and does not account easily for diffusion and refractive interaction caused by the complex shape of the component under investigation. BEM and FEM techniques are 3D based simulations but have a host of limitations due to mesh density and available processing power. Constructing models of individual palliatives such as wheel arch liners, dash insulations or carpets using such techniques may be of academic interest but of restricted use in the pressured world of component design and manufacture. It is not helped by the need to furnish the model with accurate, validated, material performance data. A modelling procedure was required that could import component CAD from the product design team and rapidly create an acoustic model that could accurately predict its performance in both a transmission loss suite and associated random incidence "Alpha cabin" absorption test. Thus, short circuit the need for at least one if not more prototype test phases or enable quotations for new business to be formulated with a higher degree of clarity. Subsequently to export results from this model into a range of "full vehicle" modelling environments or compare to prototype test results. After considerable research the authors created and validated a toolbox approach using a combination of open-source code together with bespoke modifications and defined processing procedures.