Extended damping models for vibration data analysis

A simple 3 degree of freedom spring-mass-damper system has been used to investigate the response of structural systems when the damping mechanisms are more general than viscous or hysteretic damping. The damping forces in the dashpots were assumed proportional to a general power of the relative velocity, which led to a system of equations having a frequency dependent damping matrix. The numerical results obtained from this study seem to agree with the trends in the mobility measurements made on helicopter-like structures by other investigators. The analysis also led to a formulation for the modal series equation for such structures, which admits damping models more general than viscous or hysteretic.