Aeolian Vibration of a Conductor with a Stockbridge-type Damper

grantor: University of TorontoAn iterative finite-difference scheme is derived to predict the vertical, steady-state, monofrequent, aeolian vibration of a single conductor span with a Stockbridge-type damper attached. This numerical scheme is based on empirical models developed to represent the vortex-induced lift force from the wind as well as the forces of dissipation associated with the conductor self-damping and the damper. The scheme has the capability to account for more than one spatial mode of conductor vibration, travelling-wave effects, conductor flexural rigidity, and damper mass. Experimental data on the energy-dissipation characteristics of a sample Stockbridge-type damper are generated by means of the forced response method. Damper nonlinearities and inadvertent phase shifting are identified as important factors in the measurement of the energy dissipated by the damper. Furthermore, it is shown that the magnitude of the fundamental component of the damping force exerted by the Stockbridge-type damper is a nonlinear function of not only the frequency of vibration, but also the displacement amplitude of the damper clamp. A two-part numerical analysis is performed in which the aforementioned finite-difference scheme is applied to simulate the vertical, steady-state, monofrequent, aeolian vibrations of a typical conductor with and without the sample damper. The computed results are employed to investigate (a) the steady-state form of conductor vibration, (b) the maximum conductor displacement and conductor bending amplitudes near each span end as a function of the vibration frequency and damper location, and (c) the influence of conductor flexural rigidity and damper mass. In addition, results from the finite-difference scheme are compared with solutions from the widely used energy balance method as well as experimental data on conductor vibrations.Ph.D