Wednesday, February 13, 2013
Eppes, Milanovic and DePanfilo Publish in the Academic Journal of Science
The paper, "Resonance Modes in an Acoustic Guitar," presents the results of a finite element analysis of the eigen-modes of a Collings guitar, a well-known design developed and custom manufactured by Jim Collings. A method to predict resonance patterns based on its physical shape and wood composition is described. Discreet modes, known as eigen-frequencies, denote where the amplitude responses of the acoustic chamber are the largest. Each mode represents a solution to an equation classically described as Helmholtz resonance. A three-dimensional model using COMSOL Multiphysics for the geometry size/shape, a spruce soundboard and mahogany side/back walls is the basis for the research. The analysis focuses on the lower end of the dynamic range from 200Hz to 1,000Hz in which surface deformation, both total and normal to the surface, are examined. In addition, node and anti-node structures in the area where the bridge attaches to the top plate are explored.