12. Parametric Analysis of the Expansion Process Based on System Equivalent Model Mixing

Accurate determination of the high-resolution dynamic response is a crucial step for the dynamic properties characterization in the development phase of a modern product. The conventional experimental procedure for the identification of the structure’s dynamic properties is an experimental modal analysis, where a high spatial resolution can be obtained by imposing a large number of response and excitation points at a structure. To avoid time-consuming experimental testing, measurements involving only a limited number of points at the structure can be expanded to the unmeasured points through model-based expansion techniques. They rely on the introduction of a numerical model, presenting the basics of the expansion. Recently, an expansion method called System Equivalent Model Mixing (SEMM) was proposed where a numerical DoF set is used to extend an experimental model consisting only of a limited number of measurement points. Using the dynamic substructuring approach, the equivalent experimental and numerical models are coupled so that the hybrid model inherits the dynamic properties of both. Although the method has been well adopted, there is still no comprehensive phenomenological analysis to determine the influence of the method’s parameters on the consistency of the hybrid model and thus on the accuracy of the expansion process.

This paper addresses the issue by evaluating the accuracy of the SEMM expansion process, focusing on the influence of the regularity of the so-called equivalent numerical model. The introduction of quasi-equivalent numerical models into SEMM is analysed here, which can differ not only with respect to the mass and stiffness properties but also in terms of the geometry and boundary conditions. The parametric study was carried out on a real component of a household appliance, and the most influential parameters in terms of accuracy of the SEMM expansion process were identified.