Dynamic Model of Pivoting Friction and Experimental Evidence

WANG Chen, ZHANG Hongjian, WANG Xiaojun, et al

ACTA Scientiarum Naturalium Universitatis Pekinensis - - Contents -

1. Beijing Institute of Aerospace Systems Engineering, Beijing 100076; 2. China Academy of Launch Vehicle Technology, Beijing 100076; 3. State Key Laboratory for Turbulence and Complex Systems, Peking University, Beijing 100871; 4. State Key Laboratory of Nonlinear Mechanics, Chinese Academy of Sciences, Beijing 100090; 5. School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049; † Corresponding authors, E-mail: zhanghj@pku.edu.cn (ZHANG Hongjian), wangxj99@139.com (WANG Xiaojun)

Abstract An experimental apparatus was designed to test the pivoting friction moment of annular friction disc under either constant normal force and variable normal force. The experimental results demonstrated the applicability of the classical pivoting friction model under the continuous variable normal contact force, and showed that the rotary velocity affects the properties of the pivoting friction. By considering the Stribeck effect of the local friction at a contact point, a theoretical model was proposed for the pivoting friction. Good agreement between proposed theoretical and experimental results sheds light on the physical mechanism underlying the pivoting friction. Key words pivoting friction; annular friction disc; Stribeck effect

[8]等 将这些摩擦阻力矩归结为3个方向的转动摩阻(rotation friction), 包括两个切向方向的滚动摩阻(rolling friction)以及一个法向方向的自旋摩阻(pivoting friction)。在航天器的设计中, 卫星太阳能帆板、折叠翼舵等部件展开到预定位置时, 会对与之相连的结构产生一定的冲击, 可以设计摩擦阻尼器[9]来降低冲击作用。欧洲空间臂(European Robotic Arm, ERA)等大型空间机械臂[10]的关节中都设计了

Zhuravlev[11]基于Hertz接触理论和恒定摩擦系数的假设, 得到自旋摩阻的理论模型, 但该模型并没有得到有效的实验验证。Karapetyan[12]针对均质球体与平面接触的情形, 推导了自旋摩阻模型。Houpert[13]对滚珠丝杠副摩擦力矩中的自旋摩阻进行研究, 认为自旋摩阻与滚珠和滚道间的法向力成

[14] [15]正比。 Voyenli 等 和 Goyal 等 基于 Amontoncoulomb摩擦模型,研究水平面上运动圆盘受到的阻力矩的情况, 得到自旋摩阻的理论表达式。Farkas等[16]和Halsey[17]基于圆盘接触面上均匀法向应力分布和恒定摩擦系数的假设, 推导自旋摩阻模型, 并很好地解释了圆盘的旋转运动与质心平动总是在同一时刻停止的现象。Weidman等[18]对这一现象进行理论和实验研究, 证明Voyenli等[14]、farkas等[16]以及Halsey[17]的自旋摩阻模型对任意初始平动速度和旋转角速度条件下的圆盘和圆环运动均适用。

1 实验设计

2实验结果与分析2.1变法向力实验

2.2 恒定法向力实验

3 自旋摩阻模型

Coulomb摩擦系数 处处相等。取环形接触面上宽度为dr的一个环形, 该环形半径为r, 设法向力为Fn,则接触面上各点法向接触应力为

4 结论

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1. 基座, 2. 伺服电机, 3. 减速器, 4. 输入扭矩传感器, 5. 转轴, 6. 摩擦片系统, 7. 角度传感器, 8. 扭矩输出平台, 9.输出扭矩传感器。下同图 3实验平台原理Fig. 3 Sketch of the experimental apparatus