Curve fitting free-vibration time response for estimation of structural dynamic parameters

Plucking a string on a guitar, violin, or harpsichord not only produces a pleasant sound but also displays the instrument's "acoustical personality." Similarly, plucking a structure or other mechanical system, then analyzing the subsequent free vibration, can reveal the system's "dynamical personality." Here, Hallauer et al discuss a type of analysis in which a mathematical model is curve fitted directly to the free-vibration time-response data. They present examples of analyzing experimental free-vibration data by means of MATLAB, a popular, general-purpose system of software. They describe the application of this curve fitting approach to two different types of testing and analysis: estimation for a 1-DOF mass-spring system of both the nonlinear kinetic Coulomb friction and the coexisting linear viscous damping; and experimental modal analysis of multiple-DOF systems, specifically, modal parameter estimation based on multiple, simultaneously recorded free-vibration time responses.