Building a suited reduced modal basis for updating 3D acoustic models with the constitutive law error method

We have recently reported the possibility of developing an updating technique for acoustic finite element models based on the constitutive law error proposed by P. Ladevèze and co-workers in structural dynamics. Like with every updating technique, we are confronted with and interested in reducing the computational time. The main idea of this paper consists in building a reduced modal basis made of two contributions: static modes complete a truncated modal basis corresponding to the frequency range of computation. The static modes are associated to the system excitation (for instance a normal velocity boundary condition), but also to the system damping and to the reference measurements.Updating acoustic models using the reduced modal basis shows a significant CPU-time saving with respect to the full non reduced system with an acceptable accuracy.