Lateral Vibrations of an Asymmetrical Shaft Driven by a Universal Joint : 3rd Report, Analyses and Experiments on Forced Vibrations of Horizontal Shaft Caused by Gravity

Abstract

An asymmetrical shaft driven by a universal joint is assembled horizontally, and it is subjected to the action of gravity. In the asymmetrical shaft forced vibrations are excited by the triple effect of gravity, asymmetry, and angular velocity fluctuation. Analyses are made of a simple vibratory system consisting of a driven shaft with no distributed mass and having a concentrated mass at the middle. The simultaneous equations of motion have paremetric excitation terms and a sinusoidal force. The solution to the equations of motion is derived approximately in asymptotic expansion form. Also, a stationary vibration solution is derived from the approximate solution. The results of the analyses show that the shaft system makes resonances at the angular velocities near a half or quarter of the major critical speed. The validity of the analytical results is confirmed by experiments.