STABILITY OF ROTATION OF A MOTOR DRIVEN SHAFT ABOVE THE CRITICAL SPEED

✍ Scribed by J. Zajaeczkowski

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 195 KB
• Volume: 209
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.1997.1288

✦ Synopsis

The paper is concerned with the problem of stability of a shaft driven by an electric motor. The behaviour of the system is explained by considering the motion on the energy surface. It is found that for the shaft with one end free to move axially, the energy surface has a minimum below the critical speed and a maximum above the critical speed. At resonance the energy surface is a slope plane. As the consequence of the shape of the energy surface, the motion above the critical speed is unstable and the speed of the shaft decreases to the critical value. For the shaft with ends kept a fixed distance apart, the local maximum on the energy surface is surrounded by an inclined concavity having a saddle and a global minimum. The local maximum and the saddle represent the states of unstable dynamic equilibrium. The global minimum represents the state in which the motion of the shaft above the critical speed is stable. The behaviour of the system disturbed from the unstable equilibrium states is demonstrated graphically.