Date of Award

3-1993

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

Kirk A. Mathews, PhD

Abstract

This study investigated the effectiveness of foam linings in mitigating shock waves in tunnels. A polyurethane foam liner of varying density, crush strength and thickness was modeled inside a 1 meter radius tunnel and an explosion of 1.25 kg of plastic explosive was simulated. Using CTH, an Eulerian- Lagrangian hydrodynamics code from Sandia National Laboratories, the overpressures were computed and compared graphically to determine the effect of varying each foam parameter. The walls of the tunnel consisted of a perfectly reflecting boundary, and in some cases, a foam liner. Low density foam provided the most shock attenuation. with a 20 cm thick layer of 90% void (0. 1265 g/cm3) foam reducing the shock overpressure by 70% at 50 meters. The effects of foam thickness on the shock pressure varied with the distance from the explosion. The thicker foams raised the initial pressure near the explosion due to constriction of the tunnel area. However, the thicker layers reduced the shock faster. Varying the crush strength of the foam from 1 atm to 3 atm overpressure did not affect its ability to mitigate shock propagation in the tunnel. The results of this study strongly suggest that foam can mitigate shock waves significantly.

AFIT Designator

AFIT-GNE-ENP-93M-2

DTIC Accession Number

ADA262491

Comments

The author's Vita page is omitted.

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