Abstract

The goal of this study was to quantify the contributions of multiple damping types acting on guitar strings for each mode over a wide frequency range so that design variables could be identified to one day create frequency based damping in guitar strings. Structural dynamic testing was used to obtain the time-response of a vibrating string in open air and in a vacuum. From this signal, each harmonic was filtered and the decay envelope was curve-fitted with a function that was a linear summation of decay functions. From the curve-fits, the damping coefficients for aerodynamic, friction, and material damping were calculated and used in the equation of motion for a single degree-of-freedom spring-mass-damper system.

The curve-fit and the spring-mass-damper model were primarily sensitive to the aerodynamic damping parameter, which allowed the other damping parameters to take on a wide range of values, some of which contradicted the laws of physics. The curve-fit and model response was more representative of mathematical convenience rather than physical relevance, as both were influenced by the summation effect of the multiple damping functions. This method shows promise in its analytical simplicity; however, future areas of study are outlined so that this method may be further refined before being used in industry.

Keywords

Acoustics, Structural Dynamics, Damping, Damping Mechanisms, Curve-Fitting, Signal Processing

Date of this Version

6-15-2011

Department

Mechanical Engineering Technology

Department Head

Vahid Motevalli

Month of Graduation

August

Year of Graduation

2011

Degree

Master of Science

Head of Graduate Program

Gary Bertoline

Advisor 1 or Chair of Committee

Richard M. French

Committee Member 1

Nancy L. Denton

Committee Member 2

Nicholas J. Giordano