A Numerical Investigation of Blast Loading and Clearing on Small Targets

Rigby, S.E.; Tyas, A.; Bennett, Terry; Fay, Stephen; Clarke, Steve; Warren, James A.

doi:10.1260/2041-4196.5.3.253

Cited by 55 publications

(51 citation statements)

References 18 publications

(34 reference statements)

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“…However, in Figure 3 it is possible to support that the impulses could be estimated with confidence, knowing that ProsAir overestimates the impulse and LS-DYNA underestimates it. These results are in accordance with others in terms of LS-DYNA and Air3D (similar to ProsAir) behavior (Huang et al, 2012;Rigby et al, 2014;Trajkovski et al, 2014). Figure 1).…”

Section: Source: Authorssupporting

confidence: 92%

“…As the data is required by volume, knowing the TNT equivalent and the density of the TNT introduced into the model (Table 1), the explosive volume (m 3 ) was calculated. The chosen meshing technique was the butterfly one, in order to ensure the good spherical shape of the shock wave as other authors suggest (Lapoujade et al, 2010 andRigby et al, 2014). The necessary data for the EOS used in this case, the traditional Jones-Wilkins-Lee (Lee et al, 1973), are shown in Table 1.…”

Section: Ls-dyna Modelling Processmentioning

confidence: 99%

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Application of grid convergence index to shock wave validated with LS-DYNA and ProsAir

et al. 2020

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The discretization error is not always calculated, even though it is essential for the studies of computational solid mechanics. However, it is well known that an error committed by the mesh used can be as large as the measured variable, which greatly invalidates the results obtained. The grid convergence index (GCI) method makes possible to determine on a solid basis, the order of convergence and the asymptotic solution. This method seems to be a suitable estimator despite further research is needed in the context of blast situations and finite element (FE) calculations. For this purpose, field trials were performed consisting in the detonation of a spherical hanging load of homemade explosive. The pressure generated by the shock wave was measured in different positions at two distances. With these data, a TNT equivalent has been obtained and used to calculate the shock propagation with the solvers LS-DYNA and ProsAir. This work aims to verify the GCI method by comparing its results with field data along with the simulations carried out. The comparison also seeks to validate the methodology used to obtain the TNT equivalent.This research shows that the GCI gives good results for both solvers despite the complexity of the physical problem. Besides, LS-DYNA displays better correlation with the experimental data than the ProsAir results, with an error of less than 10% in all values. RESUMENLa estimación del error de discretización no siempre se calcula, aunque es algo fundamental para el estudio de la mecánica computacional de los sólidos. Sin embargo, es bien sabido que el error cometido por la malla utilizada puede ser del mismo orden que la variable medida, lo que llega a invalidar los resultados obtenidos. El método del ındice de convergencia de la malla (GCI) permite determinar sobre una base sólida el orden de convergencia y la solución asintótica, por lo que parece ser un buen estimador, a pesar de que es necesario seguir investigando en el contexto de las situaciones de ondas de choque (explosivos) y de los cálculos de elementos finitos (FE). Para este fin, se realizaron pruebas de campo consistentes en la detonación de una carga esférica colgada de explosivo casero. La presión generada por la onda de choque se midió en diferentes posiciones a dos distancias. Con estos datos, se obtuvo un equivalente de TNT que se utilizó para calcular la propagación del choque con los programas LS-DYNA y ProsAir. Este trabajo pretende verificar el método GCI comparando sus resultados con los datos de campo junto con las simulaciones realizadas. También, la comparación busca validar la metodologıa empleada para la obtención del equivalente TNT.La investigación muestra que el GCI da buenos resultados para ambos programas a pesar de la complejidad del problema fısico. Además, el LS-DYNA produce una mejor correlación con los datos experimentales que los aportados por el ProsAir, con todos los valores por debajo del 10 % de error.Palabras clave: ındice de convergencia de malla (GCI), equivalente de TNT, LS-DYNA, ProsAir.How to ...

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Section: Source: Authorssupporting

confidence: 92%

Section: Ls-dyna Modelling Processmentioning

confidence: 99%

Application of grid convergence index to shock wave validated with LS-DYNA and ProsAir

et al. 2020

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“…A 100 mm thick steel target plate is underslung from the soffits of the horizontal beams and acts as a nominally rigid boundary to reflect the shock wave and detonation products impinging on the target after detonation of an explosive some distance beneath the centre of the plate. The plate is 1.4 m in diameter to negate the effect of blast wave clearing around the target edge [47].…”

Section: Experimental Setup 'Characterisation Of Blast Loading' Apparmentioning

confidence: 99%

Experimental Measurement of Specific Impulse Distribution and Transient Deformation of Plates Subjected to Near-Field Explosive Blasts

et al. 2018

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The shock wave generated from a high explosive detonation can cause significant damage to any objects that it encounters, particularly those objects located close to the source of the explosion. Understanding blast wave development and accurately quantifying its effect on structural systems remains a considerable challenge to the scientific community. This paper presents a comprehensive experimental study into the loading acting on, and subsequent deformation of, targets subjected to nearfield explosive detonations. Two experimental test series were conducted at the University of Sheffield (UoS), UK, and the University of Cape Town (UCT), South Africa, where blast load distributions using Hopkinson pressure bars and dynamic target deflections using digital image correlation were measured respectively. It is shown through conservation of momentum and Hopkinson-Cranz scaling that initial plate velocity profiles are directly proportional to the imparted impulse distribution, and that spatial variations in loading as a result of surface instabilities in the expanding detonation product cloud are significant enough to influence the transient displacement profile of a blast loaded plate.

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“…Hence for these tests the clearing effects would have ceased relatively early on during the positive phase and no 'overshoot' early negative pressures would have been observed. This has recently been investigated by Rigby, Tyas, Bennett, Fay, Clarke & Warren (2014), where a series of numerical analyses were conducted to evaluate the cleared pressure-time history acting on rigid targets of decreasing size. The work showed that if the target was ∼250 times smaller than the distance from the blast to the target, then the clearing predictions could be reasonably well predicted by the Norris methodology.…”

Section: Literature Clearing Predictionsmentioning

confidence: 99%

Approach to Developing Design Charts for Quantifying the Influence of Blast Wave Clearing on Target Deformation

et al. 2017

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If a structural component is located close to the free edge of a building, clearing of the blast wave around the target edge may significantly influence the temporal characteristics of the applied pressure. Because of this, traditional analysis methods assuming a linear decaying load may not be valid, particularly if the blast event imparts a relatively large impulse from the negative phase.Treatment of this phenomenon is brief in the literature, and its influence is usually neglected. This article presents an approach to quantifying the influence of clearing on target deformation, through rigorous analysis of elastic-perfectly-plastic equivalent single-degree-of-freedom (SDOF) systems. The cleared load is evaluated for structural components situated at various distances from the free edge of a reflecting surface using the Hudson acoustic approximation. The results from the SDOF analyses are then used to draw up design charts for determination of the likely influence clearing may have on the design of blast resistant structural components. Four regions are identified: areas where clearing is beneficial; has no effect; is acting adversely; or highly adversely. The method presented herein provides clear demarcation of these regions.

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A Numerical Investigation of Blast Loading and Clearing on Small Targets

Cited by 55 publications

References 18 publications

Application of grid convergence index to shock wave validated with LS-DYNA and ProsAir

Application of grid convergence index to shock wave validated with LS-DYNA and ProsAir

Experimental Measurement of Specific Impulse Distribution and Transient Deformation of Plates Subjected to Near-Field Explosive Blasts

Approach to Developing Design Charts for Quantifying the Influence of Blast Wave Clearing on Target Deformation

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