Aalto University School of Engineering, Finland.
Aalto University School of Engineering, Finland.
J Biomech. 2021 Mar 30;118:110273. doi: 10.1016/j.jbiomech.2021.110273. Epub 2021 Jan 29.
The 16-station, computer-controlled RandomPOD wear test device was re-designed into a friction measurement device, Friction RandomPOD. The motion was implemented by a servo-electric x-y-stage and the load was proportional-pneumatic. The direction of sliding, velocity (v), acceleration, and the magnitude of the load (L) varied randomly and continuously. The nominal contact pressure p varied between 0 and 2.4 MPa and v between 0 and 40 mm/s. In the first version of the device, the frictional force components were continuously measured by two miniature load cells in two perpendicular directions. In the second version, the measurement was done with a three-axial, commercial load cell. The resultant frictional force was divided by the instantaneous load in order to obtain the coefficient of friction (μ) at a frequency of 200 Hz. Due to the light and accurate design of the device, vibrations were absent in the measured signals although the measurements were most dynamic. Hence no filtering was needed. Serum lubricated polyethylene/CoCr tests revealed non-symmetric distributions of μ, friction power P, and μ vs. pv.
16 站、计算机控制的 RandomPOD 磨损测试设备被重新设计成摩擦测量设备，即 Friction RandomPOD。运动由伺服电动 x-y 平台实现，负载为比例气动。滑动方向、速度 (v)、加速度和负载 (L) 的大小随机且连续变化。名义接触压力 p 在 0 到 2.4 MPa 之间变化，v 在 0 到 40 mm/s 之间变化。在该设备的第一个版本中，两个微型负载单元在两个垂直方向上连续测量摩擦力分量。在第二个版本中，使用三轴商用负载单元进行测量。为了获得 200 Hz 时的摩擦系数 (μ)，将瞬时负载除以合成摩擦力。由于设备的轻巧和精确设计，尽管测量非常动态，但在测量信号中没有出现振动，因此无需滤波。血清润滑的聚乙烯/CoCr 测试显示出 μ、摩擦功率 P 和 μ 与 pv 的非对称分布。
