On the nonlinear oscillation of internal sliding friction in particulate matter

Abstract

Experiments are designed to explore the sliding friction that the particulate material bears in the movement when the detecting rod goes vertically through the material contained in a round tube. The research result shows that the sliding friction makes nonlinear oscillations about an average value when the depth of the particulate pile with 2 mm particulate diameter is greater than 0.5 to 2 times the diameter of the container. When the detecting rod goes up with the uniform velocity of less than 2×10-3 m/s, the average value of the sliding friction is 0.2 to 0.5 times greater than the maximum static friction F0 and the value fluctuates within the range from F0 to 2F0. When the frequency is lower than 1.35 Hz, the intensity of various frequencies goes down exponentially with increasing frequency. The average period T of the main frequency is inversely proportional to the velocity v of the detecting rode.