Prediction of shock waves over a sound-absorbing area

Vedy, Eric; Eerden, F. van der

doi:10.3397/1.2839247

Cited by 3 publications

(4 citation statements)

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“…Although such a model has been developed for the above ground propagation it assumes the ground to be semi-infinite and rigid-porous [48,49]. To deal with the more complex problems posed by ground layering and elasticity, a (linear) Fast Field Program for Layered Air Ground Systems (FFLAGS), developed originally for continuous sound sources [30], has been extended to enable predictions of acoustic and seismic pulses from explosions in a refracting atmosphere above layered porous and elastic ground.…”

Section: Modeling Ground Vibration Waveforms Produced By Explosionsmentioning

confidence: 99%

Ground vibrations produced by surface and near-surface explosions

et al. 2013

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a b s t r a c tMeasurements of seismic signatures produced by airborne, near-surface detonations of explosive charges over a variety of ground types show two distinct ground vibration arrivals. In all cases, the earlier arrival (precursor), has a time of arrival consistent with a predominantly underground path and coupling of blast sound to the ground close to the source and is always much smaller than the later vibration, the time of arrival of which is consistent with coupling from the air blast arrival at the receiver. The ratio of the seismic particle velocity to the acoustic pressure at the surface for the air-coupled seismic wave is constant with respect to distance and maximum pressure at a given location, but varies from site to site, with values usually between 1 and 13 lm s A numerical code enabling calculations of the fields due to an impulsive source above a layered poroelastic ground is described. Predictions of the air pressure spectrum above ground and the vertical and radial components of solid particle velocity near the ground surface are found to compare tolerably well with the measured spectra and waveforms of acoustic and seismic pulses at about 100 m range in seismically-hard and -soft soils and with a snow cover present. The predicted seismic responses in 'soft' soil confirm that the existence of a near-surface S-wave speed less than that in air is responsible for the observed 'ringing', i.e. a long low-frequency wavetrain associated with coupling to the dispersive Rayleigh wave. The predicted seismic pulses in the presence of the shallow snow cover explain the observed phenomenon whereby a high frequency ground vibration is modulated by a lower frequency layer resonance.An empirical equation relating ground vibration from explosions to distance predicts that the commonly-used vibrational damage peak velocity criterion of 12 or 25 mm s À1 will be exceeded when the peak positive pressure exceeds 480 Pa (147.6 dB) or 1 kPa (154.0 dB), respectively. Either of these levels is much higher than the current U.S. Army overpressure damage criterion of 159 Pa (138 dB). Thus in most situations damage from blast overpressure will occur long before damaging levels of ground vibration are reached, so it is likely that civilian perceptions of vibration are produced by coupling from the airblast.Published by Elsevier Ltd.

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Section: Modeling Ground Vibration Waveforms Produced By Explosionsmentioning

confidence: 99%

Ground vibrations produced by surface and near-surface explosions

et al. 2013

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“…The linear and free-field waves maintained their asymmetric form with positive portions larger than negative portions. Figure 7(b) shows the corresponding complex spectra of the sound exposure level determined by integration of the square of the instantaneous sound pressures as a function of frequency that were obtained from the Fourier transforms of the nonlinear and linear waveforms in Figure 7(a), see also [5]. The process illustrated in Figure 7 preserved the phase information of the starting blast waveforms as well as the effects of interactions between direct and reflected waves.…”

Section: Npe-pe Couplingmentioning

confidence: 96%

“…In the PE region, information about the frequency spectrum of a waveform is required and hence a waveform has to be converted to a spectrum of the sound exposure level of the blast sound wave. Predictions by the FCT method of the waveforms of blast shock waves propagating over a soundabsorbing surface and comparisons with measured waveforms are given in [5].…”

Section: Introductionmentioning

confidence: 99%

Propagation of shock waves from source to receiver

Eerden¹,

Vedy²

2005

Noise Control Eng. J.

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This paper describes a 3-stage technique to model the propagation to the far field of nonlinear shock waves produced by high-energy explosive sources. The stages are: (1) a 3-dimensional unsteady Euler method for the strong shock near the source, including a Flux-Corrected-Transport (FCT) method, (2) the Nonlinear Progressive-wave Equation (NPE) procedure for the degeneration of the shock into a linear acoustical wave, and (3) the Parabolic Equation (PE) method for propagation to the far field. Comparisons of calculated data with a linear analytical method are shown. © 2005 Institute of Noise Control Engineering.

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“…The reason for this is probably due to the difficulties of the problem, resulting from the intensive energy and low frequencies and the limit of means which can be used [17]. In existing studies of developing effective mitigating means for a particular noise, we find that Attenborough et al have made a significant investigation both from theory and experiment, based on the design of sound-absorbing surfaces [17][18][19][20][21]. In their studies, the nonlinearity of the noise as a shock wave near the muzzle [22,23] is avoided by making use of an effective sound-pressure emission spectrum based on measurements, and the sound pressure at far zones is calculated from this emission spectrum with a linear model.…”

Section: Introductionmentioning

confidence: 99%

A study for sound wave scattering by corrugated ground with complex trench structures

Tong

Ting

Chew

et al. 2009

Waves in Random and Complex Media

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Several trench structures in corrugated ground are investigated for the possibility of mitigating gun blast noise by numerical simulations. The blast noise usually includes large explosive energy with nonlinearity in the near field and exhibits a very lowfrequency spectrum. In this study, the linearity approximation for the noise is taken because the nonlinearity of the wave reaching the scatterer is not serious for many proved guns and the low-frequency characteristic is concentrated. The structures are designed based on the surface impedance design approach proposed in our previous work and arbitrary three-dimensional (3D) geometries within a truncated ground are now assumed. The acoustic characteristic of the structures is evaluated by using a fast numerical solver. The solver employs the multilevel fast multipole algorithm (MLFMA) as an accelerator and can solve very large acoustic wave scattering problems with millions of unknowns on workstations within several days. This tool allows us to truncate the ground as large as needed for accurate modeling. Four structures are mainly considered in the design, namely, concentric trenches, sectorial trapezoidal trenches, interlaced arc trenches and parabolic reflectors. Some of them may have a sloped inner wall or tilted surface as a means of adjustment. Numerical simulations show that the concentric trench design has a very good mitigation behavior for linear and continuous noise sources and the structure is further studied for mitigating real-world gun blast noise.

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Prediction of shock waves over a sound-absorbing area

Cited by 3 publications

References 0 publications

Ground vibrations produced by surface and near-surface explosions

Ground vibrations produced by surface and near-surface explosions

Propagation of shock waves from source to receiver

A study for sound wave scattering by corrugated ground with complex trench structures

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