Yutaka Yoshitake

Vibration Quenching and Electricity Generation by Dynamic Absorber Composed of Generator with Tow Slots and Horizontal Pendulum (1st Report, Quenching of Vortex-Induced Vibration)

This paper deals with the quenching problem of vortex-induced vibrations and generation of electricity by dynamic absorber composed of generator with two slots and horizontal pendulum. The experiment was made on the quenching problem of the vortex-induced vibration of single-degree-of-freedom system by using this device. Moreover, the numerical analysis was also carried out by using the Runge-Kutta-Gill method. As a result, the followings were made clear. (1) The optimal tuning condition of natural frequency of this device was derived. (2) The vortex-induced vibration was well quenched for the wide range of wind velocity by choosing its optimal tuning condition of natural frequency. (3) By using the tuned device, the amplitude of the main system is quenched to 2.5% in experiment and to 16% in numerical calculation. (4) The condition of maximum generation of electricity was not equal to that of minimum vibration amplitude of the main system. (5) Quantity of generation of electricity by this device was less than that by the device with Hula-Hoop.

Self-excited vibration of a circular plate subjected to frictional forces exerted in two regions on its outer circumference (A case of a circular plate subjected to distributed frictional forces without the effect of internal resonances)

This paper deals with the self-excited vibration of a Mindlin circular plate subjected to distributed frictional forces as a function of relative slip velocity in two regions on its outer circumference. However, the effect of the internal resonances is not considered here. It is derived from the averaging method that there exist two stable steady-state solutions of single mode with different spatial location with respect to two frictional regions. The stable solutions become, in general, unstable as the distributed regions widen, but, on the other hand, the stable self-excited vibrations due to the distributed frictions occur anew. However, within a certain length of the distributed regions, the self-excited vibration characteristic has the same tendency as the one due to the concentrated frictional forces at two points, which was dealt with in the previous paper.