SnowMicroPenetrometer applications for winter vehicle mobility

Abstract

The U.S. Army Cold Regions Research and Engineering Laboratory provides technical support to military forces, one area being vehicle mobility modeling over snow. Many factors control vehicle performance, including the vehicle specifications and the land surface conditions. However, estimating snow macromechanical properties-such as elastic modulus, stiffness, and strength-is critical for understanding how effectively a vehicle will travel over snow-covered terrain. Vehicle instrumentation data and observations of the snow pack are necessary to improve the estimates of winter vehicle performance. Currently, snow depth and bulk snow density alone drive the available mobility performance index.This research deployed a SnowMicroPenetrometer (SMP) to measure hard, vehicle-compacted snow and groomed snow roads. Microstructural and micromechanical properties derived from the SMP data analysis were correlated to the Rammsonde penetrometer hardness, an established snow instrument, and to the shear-strength test vane and Light Weight Deflectometer, which are common in soil and aggregate layer assurance methods in road construction. Correlating these tools requires a new theory for inverting SMP signals for micromechanical properties that relaxes the assumption of low-density snow. Additionally, a scaling law appropriate to this type of hard snow is required to relate the SMP observations of the microscale and the macroscale properties.

Assessment of field methods for measuring mechanical properties of snow

“…The increased dynamic force range comes at a cost in force resolution as the instrument's discrete quantization levels were not increased when the sensor capacity was increased. Meehan et al (2019aMeehan et al ( , 2019b document and analyze the SMP, its use, and results. While this instrument worked very well in the soft snow conditions it was designed for, future experiments would benefit from an SMP that could measure larger forces as many of the groomed surfaces were too hard for this instrument even with the larger force sensor.…”