颗粒物质内部滑动摩擦力的非线性振动现象

On the nonlinear oscillation of internal sliding friction in particulate matter

实验研究了探测棒竖直穿过圆筒中颗粒物质运动时所受的滑动摩擦阻力.研究发现,厚度为容器直径的0·5到2倍之间,粒径为2mm的颗粒堆,对探测棒的滑动摩擦力在一个平均水平上随时间作非线性振动.当探测棒以小于2×10-3m/s的匀速率上升时,滑动摩擦力平均水平超过初始最大静摩擦力F0的0·2到0·5倍,变化范围可从F0到2F0.频率低于1·35Hz时,各种频率成分的强度随频率增加按幂函数方式衰减,其主要部分的平均周期T与探测棒运动速率v成反比关系.

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 Fo and the value fluctuates within the range from F0 to 2 F0 . 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.