The energy parameter B for strong blast waves

Jones, Donald L.

doi:10.6028/nbs.tn.155

Cited by 9 publications

(6 citation statements)

References 1 publication

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“…Here, P0 is the ambient pressure; B is a geometry-dependent parameter [37]; γ is the ratio of the specific heat at constant pressure to that at constant volume (γ = 1.4 for diatomic perfect gases.…”

Section: Shock Wave Overpressures (Swos)mentioning

confidence: 99%

Numerical estimations of lightning-induced mechanical damage in carbon/epoxy composites using shock wave overpressure and equivalent air blast overpressure

Lee¹,

Lacy

Pittman

et al. 2019

Composite Structures

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A new approach is proposed for predicting lightning-induced mechanical damage using the shock wave overpressure (SWO) due to lightning arc channel expansion and also its equivalent air blast overpressure (ABO) due to an explosion of chemical potential energy in AS4/3506 carbon/epoxy laminates. The SWOs and equivalent ABOs associated with 124, 247, and 494 kA peak lightning currents were considered. Dynamic responses of the composite laminates due to both the SWOs and ABOs were similar to each other. The spatial variations in the peak compressive and tensile midplane displacements evaluated near the laminate center showed that mechanical damage tended to be symmetric about the laminate midplane. Hashin's four different damage criteria were implemented to predict fiber/matrix failures. The predicted failure index distributions in the carbon/epoxy plies were nearly identical for both SWOs and ABOs. Except for matrix tension failure predicted at the 494 kA peak current, all damage failure indices increased as the peak current increased, but were smaller than unity, implying no mechanical damage initiation due to lightning strike. These FE results suggest that lightning SWO may not cause significant mechanical damage and it may be possible to interchangeably use either SWO or ABO to predict lightning-induced mechanical damage.

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Section: Shock Wave Overpressures (Swos)mentioning

confidence: 99%

Numerical estimations of lightning-induced mechanical damage in carbon/epoxy composites using shock wave overpressure and equivalent air blast overpressure

Lee¹,

Lacy

Pittman

et al. 2019

Composite Structures

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“…The negligible real gas effects on the trajectory may be qualitatively understood by noting that •, appears as a product with the energy constant B (see ,equation I below). B varies in an inverse manner with •, [Jones, 1962b]; thus, the product By varies slowly regardless of changes in 7-Neglect of radiation is effectively a reduction in the energy coupled Eo, since radiation from the shock itself is negligible unless the shock is very strong [Gilmore, 1955]. Thus, under the conditions stated above, the lightning discharge should closely resemble the classical blast wave source.…”

Section: T•eory A•d Equationsmentioning

confidence: 99%

Shock wave from a lightning discharge

Jones¹,

Goyer²,

Plooster³

1968

J. Geophys. Res.

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A theoretical model of the shock wave from a lightning discharge ranging from the strong blast wave region out to the acoustic limit is given for the first time. The trajectory and overpressure of the strong shock wave are described by the well‐known equations for cylindrical blast waves. In the intermediate shock strength region (1.1 < M < 3.3), the shock trajectory is given by the ‘correct limit’ equation of Vlases and Jones. We derive an additional ‘correct limit’ equation for overpressure that is valid out to the acoustic limit. The correct limit equations predict a much slower decay of the intermediate shock wave; thus, the shock wave is much stronger at large distances from the discharge than was previously believed. Consequently, the range of action of the lightning discharge via its shock wave, as it affects the shattering and freezing of supercooled hydrometeors, may be large.

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“…where r --aot/Ro; ao is the speed of sound in the undisturbed medium; t is the time of arrival at the position R; Ro is a characteristic radius [ (25/4) (1/By) (E/p,)],/8; E is the energy deposited' in the shocked gas; p, is the ambient pressure; y, the specific heat ratio, is 5/3; B is 3.08 [Jones, 1962]; and X is the reduced shock radius R/Ro. The energy integral B should be calculated for assumptions other than those given above in (c) and (d).…”

Section: 61x5/2) '/5--1] (1)mentioning

confidence: 99%