The classical guitar is a popular string instrument in which the sound results from a coupled mechanical process. The oscillation of the plucked strings is transferred through the bridge to the body, which acts as an amplifier to radiate the sound. In this contribution, a procedure to create a numerical finite element (FE) model of a classical guitar with the help of experimental data is presented. The geometry of the guitar is reverse-engineered from computed tomography scans to a very high level of detail, and care is taken in including all necessary physical influences. All of the five different types of wood used in the guitar are modeled with their corresponding orthotropic material characteristics, and the fluid-structure interaction between the guitar body and the enclosed air is taken into account by discretizing the air volume inside the guitar with FEs in addition to the discretization of the structural parts. Besides the numerical model, an experimental setup is proposed to identify the modal parameters of a guitar. The procedure concludes with determining reasonable material properties for the numerical model using experimental data. The quality of the resulting model is demonstrated by comparing the numerically calculated and experimentally identified modal parameters.

Contact modeling is an active research area in the field of multibody dynamics. Despite the important research effort, two main challenging issues, namely accuracy and speed, are not yet jointly solved. One main issue remains the lack of model order reduction schemes capable to efficiently treat systems where multiple, a priori unknown, input-output locations are present. This work first analyzes the importance of including the necessary residual attachment modes by numerical simulation of two gears meshing in an ad-hoc flexible multibody model. Given the large number of residual attachment modes needed, the methodology named static modes switching is extended and successfully applied to improve efficiency. The method proposes an on line selection of residual attachment modes for accurate local deformation prediction. The applicability to impact problems is discussed through numerical experiments and the automatic selection strategy is based purely on geometrical information. Results show that the method can be applied to gear meshing simulation, obtaining a high level of accuracy while preserving computational efficiency. Comparisons are made between modally reduced models, full nonlinear finite element and the proposed strategy

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