LINEAR DAMPING MODELS FOR STRUCTURAL VIBRATION

Abstract Linear damping models for structural vibration are examined: first the familiar dissipation-matrix model, then the general linear model. In both cases, an approximation of small damping is used to obtain simple expressions for damped natural frequencies, complex mode shapes, and transfer functions. Results for transfer functions can be expressed in the form of very direct extensions of the familiar expression for the undamped case. This allows a detailed discussion of the implications of the various damping models for the interpretation of measured transfer functions, especially in the context of experimental modal analysis. In the case of a dissipation-matrix model, it would be possible in principle to determine all the model parameters from measurements. In the case of the general model, however, there is a fundamental ambiguity which prevents full determination of the model from measurements on a single structure.