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Accession Number:
ADA230180
Title:
Estimates of Shock Wave Attenuation in Snow
Descriptive Note:
Special rept.
Corporate Author:
COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
Report Date:
1990-10-01
Pagination or Media Count:
21.0
Abstract:
A simple momentum model, assuming that snow compacts to its final density at negligible stress, is used to estimate shock wave attenuation in snow. Four shock loading situations are examined a one-dimensional pressure impulse of finite duration and instantaneously applied pressure impulses for one-dimensional, cylindrical and spherical shock geometries. Calculations show that while a finite duration impulse is being applied, the shock pressure in snow is determined by the impulse pressure-time profile. After the pressure impulse has been applied, the one-dimensional shock pressure decay is the same as for an instantaneously applied pressure impulse and is proportional to the inverse square of the shock propagation distance. Hence, finite-duration pressure impulses delay the onset of shock attenuation in snow. This can result in more pressure attenuation near a shock source, where the positive phase duration of the shock is short, compared to shock waves farther from a source. Cylindrical waves have a maximum decay that is proportional to the inverse of the propagation radius to the fourth power 1Rto the fourth power, and spherical waves have a maximum decay that is proportional to 1R to the sixth power. Amplitude decay for cylindrical and spherical shock waves can vary from R-40-2, when R-R0R0 where R0 is the interior radius over which a pressure impulse per unit area is applied, to their maximum decay.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
