Session: FSI-02-06 Selected Topics in FSI

Paper Number: 105861

105861 - Dynamic Stability of a Plate Supported by Air Pressure (Analysis of Two Degree-of-Freedom Coupled System of Translational and Rotational Motions) 

In recent years, air floating systems are used in a manufacturing floor to transport a glass plate. The plate is supported by air pressure and the system has characteristics such as low noise and low power. However, it was reported that sometimes self-excited vibration occurs to a plate supported by air pressure. The self-excited vibration causes decrease in productivity and noise problem. In order to avoid quality defects, it is important to clarify the dynamic stability and instability mechanism of the self-excited vibration. However, few studies have demonstrated the dynamic stability of self-excited vibration, and these studies assumed only translational mode. In the actual conveying process, the plate has rotational degrees of freedom in addition to the translational mode, so it is necessary to clarify the vibration characteristics the two degree-of-freedom coupled system of translational and rotational motions.

This paper presents a stability analysis and exciting mechanism of coupled vibration of translation and rotation of a plate supported by air pressure. In the stability analysis, characteristic equations regarding vibration of the system are obtained by arranging the basic equation of gap flow and the equation of motion. The instability conditions are calculated by using Routh-Hurwitz stability criterion to characteristic equations. The stability of the plate is affected by the air flow rate, the mass of the plate, the volume of chamber supplying air. we clarified those influences on the instability conditions of the self-excited vibration. Furthermore, instability mechanism of the self-excited vibration is obtained by calculating work acting on the plate.

Following major results are obtained: (1) When the chamber volume is large, the critical flow rate decreases with low weight plate, but increases with high weight plate. (2) Positive work done due to the compressibility of the air in the chamber contributes significantly to the generation of self-excited vibration. However, when the system has only rotational degrees of freedom, the compressibility of the air in the chamber does not contribute to the excitation, and work done due to the restrictor at the gap entrance acts as the excitation force.

Presenting Author: Masakazu Takeda Aoyama Gakuin University

Presenting Author Biography: Masakazu Takeda is an assistant professor in the department of mechanical engineering at Aoyama Gakuin University in Japan. He is interested in fluid structure interaction, especially self-excited vibrations.

Authors:

Masakazu Takeda Aoyama Gakuin University
Takahiro Suda Aoyama Gakuin University
Yoshiki Sugawara Aoyama Gakuin University
Masahiro Watanabae Aoyama Gakuin University