Dual assembly of substructures and the FBS method: Application to the dynamic testing of a guitar

Dynamic substructuring techniques allow to assemble the dynamic response measured for subcomponents (in terms of frequency response function) and to build the experimental dynamic model for the complete system. The most straightforward and commonly used approach is the Frequency Based Substructuring techniques. Although the theory underlying the method is well understood, experimental substructuring techniques usually fail to provide accurate global models due for instance to the high sensitivity of the accuracy of the model to measurement errors and to the difficulty in measuring rotational degrees of freedom on the interfaces. In this paper we will show that, at least for simple structures, the Frequency Based Substructuring approach leads to accurate models if clean measurements are done. Also we discuss the case study of a substructuring exercise performed on a guitar that allowed to better understand the interaction between the wooden instrument (body and fret board) and the strings.