抄録
The friction force between sheets decreases by applying an ultrasonic vibration on the top of the stack of sheets.Previous studies have shown that the major factor of friction-force-decrease is the levitation of the vibrated sheet.It is anticipated that the levitation factor is an acoustic radiation force or an aerodynamic force which is caused by the vibration.However,the direct cause of the levitation is not clearly understood.In this study,we have investigated levitation height and waveform with varying sheet shape,the vibrating position and air-permeability of the sheet.As the result of the experiment,non-air permeable sheet was not levitated when the vibrator was placed at the edge of the sheet.If the influence of acoustic radiation force is dominant,non-air permeable sheet will levitate by the inflow of the air from the edge of the sheet.These results suggested that the inflow of the air from the vibrating position,which is compressed by the ultrasonic vibration,caused the levitation.
