Experimental study on ice-on-ice friction and compressive properties of high-density snow

冰的摩擦系数随温度和相对速度的变化而变化。因此，我们研究了摩擦系数对雪阻力的影响。压痕所产生的阻力在密度400kg/m^3以下进行了测量。然而，高密度雪（>400kg/m^3）中产生的阻力现在对于雪崩的雪碎片，道路上的压缩雪和结冰的卫星很重要。因此，我们通过压痕试验来阐明高密度雪的力学行为，并测量冰颗粒流产生的阻力，研究冰摩擦系数与雪阻力的关系。在-10℃条件下，在0.5 ~ 500mm/s的流速范围内，采用不同深度的气缸组测量雪阻力。因此，我们发现阻力随流速的增加而减小。但是，在-50℃下进行的测试中没有发现同样的速度依赖关系，它是一个常数。在-10℃时，d…More rag力的速度依赖关系可以用冰摩擦系数的速度依赖关系来解释。冰的摩擦系数随着速度的增加而减小，这是由于边界处的摩擦融化减少了摩擦力。压缩测量是用一根棒子穿透高密度的雪进行的。变形分为塑性变形和破坏变形两种类型。在塑性变形中，应力和应变率之间的关系是非线性的，因此，这种变形不是牛顿式的，而是用幂律表示的。这表明，除了在低密度雪中进行的颗粒重排外，冰颗粒的塑性变形和破坏也很重要。当雪密度为550、640和730 kg/m^3时，两种变形类型的临界穿透速度分别为0.33 ~ 0.83、0.83 ~ 1.67和1.67 ~ 3.33 mm/。能量随密度增加而增加，接近3，这与穿透冰所需的能量相对应。少

Friction coefficient of ice changes with the temperature and the relative velocity. So, we have studied the effect of friction coefficient on the snow drag force. The drag force exerted by indentation has been measured below the density of 400kg/m^3. However, the drag force generated in the high-density snow (>400kg/m^3) is now important for the snow debris of avalanche, compressed snow on the road, and icy satellites. Therefore, we made indentation tests to clarify the mechanical behavior of the high-density snow and measured the drag force generated by ice granular flow to study the relationship between the ice friction coefficient and the snow drag force. Snow drag force was measured by using cylinder set in a various depth at -10℃ for the flow speed from 0.5 to 500mm/s. Thus, we have found that the drag force decreased with increasing the flow velocity. But, the same velocity dependence was not found in the test conducted at -50℃: it was a constant. The velocity dependence of the d … More rag force at -10℃ could be explained by the velocity dependence of the ice friction coefficient. The ice friction coefficient decreases with increasing the velocity because of the frictional melting at the boundary to reduce the friction. Compression measurements were conducted by using a rod to penetrate high-density snow. Two types of deformation were recognized plastic-type and destructive-type deformations. In the plastic-type deformation, the relation between the stress and strain rates was nonlinear, hence, this deformation is not Newtonian and is expressed by a power law. This suggests that in addition to the particle rearrangement operative in low-density snow, plastic-type deformation and destruction of ice particles are also important. The critical penetration speeds between the two deformation types were 0.33-0.83, 0.83-1.67, and 1.67-3.33 mm/ for snow densities of 550, 640, and 730 kg/m^3, respectively. The power increased with density and approached 3, which correspond to that required for penetrating ice. Less