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

高密度雪冰对冰摩擦及压缩特性实验研究

基本信息

批准号：
14390002
负责人：
ARAKAWA Masahiko
金额：
$ 6.46万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

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

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拖曳力的影响。在密度低于400 kg/m^3时，测量了压痕所产生的拖曳力。然而，高密度雪（> 400 kg/m^3）中产生的拖曳力现在对于雪崩的雪屑、道路上的压缩雪和结冰的卫星很重要。为此，我们进行了压痕试验，以阐明高密度雪的力学行为，并测量了冰颗粒流产生的拖曳力，以研究冰摩擦系数与雪拖曳力之间的关系。在-10℃、不同深度、流速为0.5 ~ 500 mm/s的条件下，用圆柱体测量了雪的拖曳力。因此，我们已经发现，阻力随流速的增加而减小。但是，在-50℃下进行的试验中没有发现相同的速度依赖性：它是一个常数。的速度依赖性的d ...更多信息 -10℃时的摩擦力可以用冰摩擦系数的速度依赖性来解释。冰的摩擦系数随着流速的增加而减小，这是由于边界处的摩擦融化减小了摩擦。通过使用杆穿透高密度雪来进行压缩测量。变形分为塑性变形和破坏变形。在塑性型变形中，应力和应变速率之间的关系是非线性的，因此，这种变形不是牛顿的，而是由幂律表示的。这表明，除了在低密度雪中起作用的颗粒重排外，冰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，两种变形类型之间的临界穿透速度分别为0.33-0.83、0.83-1.67和1.67-3.33 mm/。随着密度的增加，功率逐渐增大，接近3，相当于穿透冰层所需的功率。少