Tech Briefs

Characterizing the mechanical properties of snow and their impact on vehicle performance could improve vehicle winter mobility modeling.

The U.S. Engineer Research and Development Center (ERDC) Military Engineering Program on Remote Assessment of Infrastructure for Ensured Maneuver (RAFTER) Boreal Aspects of Ensured Maneuver (BAEM) identifies the need for modeling over-snow vehicle performance, as many factors related to vehicle setup and land surface condition contribute to vehicle efficiency. Accurately estimating snow macromechanical characteristics—such as elastic modulus, stiffness, and strength—is critical for understanding how effectively a vehicle will travel over snow-covered terrain.

Vehicle instrumentation data (inertial measurement units and vehicle telemetry) and observations of the snowpack (both satellite and ground-based) are necessary to improve the modeled estimates of winter vehicle performance. Currently, performance index is driven by snow depth and bulk snow density alone.

The snow characterization research effort deploys a capability jointly developed by the ERDC Cold Regions Research and Engineering Laboratory (CRREL) and the Swiss Federal Institute for Snow and Avalanche Research (SLF) two decades ago—the SnowMicroPenetrometer (SMP). This research used an SMP with a force sensor range of 0–500 N to measure hard, vehicle-compacted snow and processed or groomed snow roads. Median values of the high-resolution snow structural profiles from the SMP are linearly related to Rammsonde (ram), shear strength test vane, and Light Weight Deflectometer (LWD) by correlating values over the depth range of each independent in situ measurement. Statistically significant correlation shows the value of the SMP as a tool for future mobility studies in different snow types. By also understanding results that lack significant correlations, we gain insight for improving the SMP hardware, the penetration theory used, and the micro-to-macro scaling laws.

Winter vehicle mobility studies by CRREL have evaluated vehicle setup and snow condition; however, the SMP has not previously been applied to a mobility study. This work is the first winter vehicle mobility study to examine the usefulness of the SMP for research on military vehicle efficiency.

Characterizing the snow mechanical properties and their impact on vehicle mobility is challenging and requires varied field instruments and specialists with a wide range of expertise. Four instruments were used to characterize snow for the BAEM project—the SMP, ram, shear vane, and LWD—and assesses required load-cell ranges of the SMP for its application to hard, vehicle-compacted snow. The microphysical parameters estimated from SMP measurements were correlated to those from a suite of instruments designed or tested to measure snow mechanical properties. The results of this study aim to bridge micro-to-macro snow physics with the ultimate intent to infer snow structure from satellite imagery for use as initial and boundary conditions for vehicle mobility models.

This work was done by Tate G. Meehan, Hans-Peter Marshall, Elias J. Deeb, and Sally A. Shoop for the Army Engineer Research and Development Center. ERDC-0008

This Brief includes a Technical Support Package (TSP).

SnowMicroPenetrometer Applications for Winter Vehicle Mobility (reference ERDC-0008) is currently available for download from the TSP library.

Please Login at the top of the page to download.