Updating 3D acoustic models with the Constitutive Law Error method.A two-step approach for absorbing material characterization

In the global framework of improving vibro-acoustic numerical simulations together with the need to diminish the prototyping stages, getting more accurate acoustic models becomes increasingly important for many industries such as automotive companies, for instance. One way to achieve greater accuracy in numerically simulated pressure fields is to make use of parametric updating techniques enabling the tuning of the vibro-acoustic model parameters inside physically meaningful boundaries.

The improved model is re-used in the future, allowing more accurate results within reduced simulation times. The updating technique used in this paper is based on the theory of P. Ladevèze [

1

], and follows from recent works on the constitutive law error method (CLE) applied to acoustics [

2

]. The updating process focuses on the improvement of the acoustic damping matrix related to the absorbing properties of acoustic materials covering the borders of the acoustic domain. The present part of the paper proposes a 2-step optimization process. It will be shown that this 2-step updating method presents many advantages, especially by diminishing the computation time and allowing the frequency interpolation of the absorbing properties of the materials outside the studied frequency range.

While previous works addressed purely numerical setups without experimental data, this study aims at comparing 3D measured pressure fields with numerically updated ones. The test-case is the TRICARMO setup engineered by the LMS company in Leuven, Belgium. The TRICARMO setup is a simplified car cabin with rigid (concrete) walls and car seats inside. Initially roughly described seat material properties are tuned by running the updating simulation process using a library of acoustic absorbing material models.