Observations of Stick-Slip Friction in Velcro®
Observations of Stick-Slip Friction in Velcro®
复制标题
DOI：
10.1007/s11249-014-0397-x
复制
发表时间：
2014-11-01
影响因子：
3.2
通讯作者：
Angiolillo, Paul J.
中科院分区：
文献类型：
--
作者：
Mariani, Lisa M.;Esposito, Cara M.;Angiolillo, Paul J.
摩擦，特别是粘滑摩擦，发生在每一个长度尺度上，从纳米级的原子力显微镜尖端的运动到地壳构造板块的运动。即使这种普遍性，似乎仍然存在突出的基本问题，特别是在摩擦运动通常随系统的机械参数而变化的方式上。在这项研究中，通过改变驱动速度、施加载荷和表观接触面积等典型参数，探索了魔术贴（R）钩环系统在剪切中的摩擦动力学。结果表明，在Velcro（R）中，最大静摩擦力和平均动摩擦力均随表观接触面积（钩数）线性变化，此外，在动力学状态下，粘滑动力学是明显的。令人惊讶的是，平均动摩擦力在近2.5个数量级上与速度无关（类似于2 x 10（-4）至6 x 10（-2）m/s）。摩擦力随施加载荷的幂律变化，最大静摩擦力和动摩擦力的指数分别为0.28和0.24。此外，粘滑摩擦演变为更平滑的滑动，如由接触面积控制的，由动摩擦的扩展的减小和归一化到平均动摩擦时的平均动摩擦的波动的扩展来证明;这些减小遵循关于接触面积增加的幂律行为，其指数分别约为-0.3和-0.8。最后，我们注意到摩擦系数mu（s）和mu（k）并不随所施加的载荷而恒定，而是随着幂律行为而单调减小，指数接近-0.8。现象学上，这个系统表现出有趣的物理，在某些情况下，它遵循经典的阿蒙顿-库仑（AC）的行为，并在其他人在于形成鲜明对比，并希望将有助于在干燥表面的摩擦行为的理解。
Friction, and in particular stick-slip friction, occurs on every length scale, from the movement of atomic force microscope tips at the nanoscale to the movement of tectonic plates of the Earth's crust. Even with this ubiquity, there still appears to be outstanding fundamental questions, especially on the way that frictional motion varies generally with the mechanical parameters of a system. In this study, the frictional dynamics of the hook-and-loop system of Velcro (R) in shear is explored by varying the typical parameters of driving velocity, applied load, and apparent contact area. It is demonstrated that in Velcro (R) both the maximum static frictional force and the average kinetic frictional force vary linearly with apparent contact area (hook number), and moreover, in the kinetic regime, stick-slip dynamics are evident. Surprisingly, the average kinetic friction force is independent of velocity over nearly two-and-a-half orders of magnitude (similar to 2 x 10(-4) to similar to 6 x 10(-2) m/s). The frictional force varies as a power law on the applied load with an exponent of 0.28 and 0.24 for the maximum static and kinetic frictional forces, respectively. Furthermore, the evolution of stick-slip friction to more smooth sliding, as controlled by contact area, is demonstrated by both a decrease in the spread of the kinetic friction and the spread of the fluctuations of the average kinetic friction when normalized to the average kinetic friction; these decreases follow power-law behaviors with respect to the increasing contact area with exponents of approximately -0.3 and -0.8, respectively. Lastly, we note that the coefficients of friction mu(s) and mu(k) are not constant with applied load but rather decrease monotonically with power-law behavior with an exponent of nearly -0.8. Phenomenologically, this system exhibits interesting physics whereby in some instances it follows classical Amontons-Coulomb (AC) behavior and in others lies in stark contrast and hopefully will assist in the understanding of the friction behavior in dry surfaces.