The aim of this project was to use the Finite Element Method (FEM) to design and manufacture the soundboard of a nylon-string guitar from sandwich-structured composites, with reference to an existing wooden soundboard, and to evaluate the accuracy of the numerical models of the wooden soundboard, the brace-less composite top plate and the braced composite soundboard by means of experimental modal analysis.
The modal behaviour of the existing wooden soundboard was studied through experimental modal analysis and numerical simulation. Using FEM, the e↵ects of varying certain physical, geometric and elastic properties of the materials used in the soundboard were determined on its natural frequencies under free and hinged Boundary Conditions (BCs). The composite soundboard that was determined to have natural frequencies relatively similar to those of the wooden soundboard under hinged BCs, and could be built from commercially available materials was constructed. To verify the results predicted numerically, experimental modal analyses were performed on the brace-less composite top plate and the braced composite soundboard under free BCs.
The experimental natural frequencies and mode-shapes of the constructed brace-less top plate were found to match those predicted by the simulation in the frequency range below 200 [Hz], while slightly diverging in the higher frequency range. The experimental results for the braced composite soundboard were also found to be relatively similar to the numerically predicted values, with most mode-shapes matching, and some di↵erences in the mode-frequencies, mostly in the low and mid-frequency ranges. Overall, a reasonable agreement was achieved between the numerical and the experimental results
Music Technology Area, Department of Music Research
Schulich School of Music
Finite Element Design and Manufacturing of a Nylon-String Guitar