An analysis of plastic shock waves in snow

An analysis of plastic shock waves in snow PDF

Author: Robert L. Brown

Publisher:

Published: 1979

Total Pages: 23

ISBN-13:

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An analytical study of the propagation of shock waves in snow was carried out to evaluate the response of medium density snow to high rates of loading. One solution was developed for steady shock waves; this resulted in calculation of pressure jump, density jump and stress wave speed. Correlation with available experimental data was found to be good. Nonsteady shock waves were also considered in order to evaluate wave attenuation rates in snow. Very few data were available to compare with the analytical results, so no definite conclusions on the part of the study could be made. The results show, however, that shock waves that produce plastic deformation attenuate at extremely high rates and that differences in pressure between two waves are quickly eliminated within a short distance. Calculations were also made to evaluate the effect of wave frequency on attenuation rates. The results show that, for plastic waves, frequency is not a predominant factor for determining attenuation rates. (Author).

Gas Gun Experiments to Determine Shock Wave Behavior in Snow: Methods and Data

Gas Gun Experiments to Determine Shock Wave Behavior in Snow: Methods and Data PDF

Author:

Publisher:

Published: 1993

Total Pages: 149

ISBN-13:

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A laboratory study of the behavior of snow under shock wave loading and unloading conditions was conducted using a 200-mm-diameter gas gun to generate loading waves in snow samples with initial densities of 100 to 520 kg m-3 at temperatures of -2 to -23 deg C. Stress levels were 2 to 40 MPa. The response of snow to shock wave loading was measured as a function of distance from the impact plane using embedded stress gauges. Large impedance differences between snow and the stress gauges produced complex stress histories. A finite element model, along with a simple analytical model of the experiment, was used to interpret the stress histories. Snow deformation was not affected by initial temperature, but was found to be rate dependent. The initial density of the snow determined its pressure-deformation path. The pressure needed to compact snow to a specific final density increases with decreasing initial density. The release moduli increased nonlinearly from 50 MPa at a snow pressure of about 15 MPa to 2700 MPa at a snow pressure of about 40 MPa ... Attenuation, Porous ice, Shock wave propagation in snow, Experimental methods, Shock waves, Snow.

Shock Wave Studies of Snow

Shock Wave Studies of Snow PDF

Author:

Publisher:

Published: 1991

Total Pages: 5

ISBN-13:

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Shock-wave studies of snow have been conducted at stress levels of up to 40 MPa. Analysis of embedded gauges and shock-reverberation techniques were used to determine shock pressure-density data for snow with initial densities ranging from 100 kg m−3 to 520 kg m−3 and temperatures ranging from -2°C to -23°C. Shock velocities ranged from about 170 m s−1 (for low density snow) to about 280 m s−1 (for high density snow). At constant density and impact velocities, but varying temperatures, there was no variation in shock velocity. This indicates that the internal energy and any temperature dependent strength of ice bonds do not measurably affect shock propagation in snow over the temperature and pressure range of our tests. Our results also indicate that snow is a highly rate sensitive material. 9 refs., 4 figs.

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