Blast-Sound-Absorbing Surfaces. A Joint Project of the ERDC and the Netherlands Ministry of Defense
Abstract
This research investigated methods of absorbing blast sound, including the development of analytical theories, numerical simulations, laboratory experiments, and a field trial. Prior to this research, no theory existed for the design of sound-absorbing surfaces at low frequencies in a highly non-linear shock environment. The work includes developments of (1) a theory for the non-linear response of rigid-porous materials to high amplitude sound, allowing for a linear variation of flow resistivity with flow velocity (Forchheimer's non-linearity); (2) a time-domain non-linear theory that assumes low frequencies, semi-infinite media, and weak shocks and gives explicit results for incident triangular shock waveforms; (3) an alternative time-domain formulation that enables predictions for a finite layer but requires numerical integration; and (4) a further non-linear theory that predicts the response of multiple rigid-porous layers to continuous high-intensity sound. Numerical work has been carried out to predict the surface impedance of a porous and elastic layer subject to continuous high-intensity sound and including Forchheimer' s non-linearity. Measurements have been made on the propagation constant, characteristic impedance, and reflection coefficients for finite-amplitude, low-frequency continuous sound waves incident on porous concrete, porous aluminum, sand, gravel stones, perforated panels, and open-cell polymer foams. In addition, shock tube systems based on membrane rupture have been used to look at the acoustic shock response of materials. Finally, the far-field propagation is modeled using parabolic equation method. A full-scale field test using high explosives was conducted at Ft. Drum, NY. The primary purpose was to test predictions of the blast reflection from and attenuation into a porous medium, and a secondary objective was to test the effect of plowing the ground surface over a larger area.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2004
- Accession Number
- ADA427530
Entities
People
- Alan Cummings
- Erik Salomons
- Keith Attenborough
- Paul Schomer
- Piyush Dutta
Organizations
- Engineer Research and Development Center