Experimental and numerical investigations of a single-layer reticulated dome subjected to external blast loading

2018 ◽  
Vol 176 ◽  
pp. 103-114 ◽  
Author(s):  
Xudong Zhi ◽  
Shaobo Qi ◽  
Feng Fan ◽  
Ximei Zhai
Keyword(s):  
Single Layer ◽  
Blast Loading ◽  
Numerical Investigations ◽  
External Blast Loading

Experimental and numerical investigations of laminated glass subjected to blast loading

2012 ◽  
Vol 39 (1) ◽  
pp. 42-50 ◽  
Author(s):  
Martin Larcher ◽  
George Solomos ◽  
Folco Casadei ◽  
Norbert Gebbeken
Keyword(s):  
Blast Loading ◽  
Laminated Glass ◽  
Numerical Investigations

Effect of Helmet Pads on the Load Transfer to Head Under Blast Loadings

2014 ◽  
Author(s):  
Timothy G. Zhang ◽  
Sikhanda S. Satapathy
Keyword(s):  
Load Transfer ◽  
Numerical Study ◽  
Single Layer ◽  
Blast Loading ◽  
Performance Criterion ◽  
Ballistic Performance ◽  
Commercial Code ◽  
Head Assembly ◽  
Computational Simplicity ◽  
Blast Loadings

Recent wars have highlighted the need to better protect dismounted soldiers against emerging blast and ballistic threats. Current helmets are designed to meet ballistic performance criterion. Therefore, ballistic performance of helmets has received a lot of attention in the literature. However, blast load transfer/mitigation has not been well understood for the helmet/foam pads. The pads between the helmet and head can not only absorb energy, but also produce more comfort to the head. The gap between the helmet and head due to the pads helps prevent or delay the contact between helmet shell and the head. However, the gap between the helmet shell and the head can produce underwash effect, where the pressure can be magnified under blast loading. In this paper, we report a numerical study to investigate the effects of foam pads on the load transmitted to the head under blast loading. The ALE module in the commercial code, LS-DYNA was used to model the interactions between fluid (air) and the structure (helmet/head assembly). The ConWep function was used to apply blast loading to the air surrounding the helmet/head. Since we mainly focus on the load transfer to the head, four major components of the head were modeled: skin, bone, cerebrospinal fluid (CSF) and brain. The foam pads in fielded helmets are made of a soft and a hard layer. We used a single layer with the averaged property to model both of those layers for computational simplicity. Sliding contact was defined between the foam pads and the helmet. A parametric study was carried out to understand the effects of material parameters and thickness of the foam pads.

Using Explicit Finite Element Analysis to Simulate the Structural Damage Associated With an Internal Detonation in a Heat Exchanger

2014 ◽  
Author(s):  
Phillip E. Prueter
Keyword(s):  
Finite Element ◽  
Heat Exchanger ◽  
Structural Damage ◽  
Real Life ◽  
Blast Loading ◽  
Process Equipment ◽  
Computational Techniques ◽  
Explicit Finite Element ◽  
Blast Analysis ◽  
External Blast Loading

Developing the realistic blast loading associated with an internal detonation occurring within a pressure vessel or heat exchanger is challenging. Unlike evaluation of external blast loading on structures due to far-field explosions, where typical overpressure-time histories can be reasonably defined based on empirical data, investigating confined detonations presents additional complications. The subsequent impulsive peak reflected overpressure from confined detonations acting on a structure can be extremely high due to the close proximity of the blast source to the vessel wall or pressure boundary. This establishes the possibility of significant structural damage for process equipment subjected to an internal detonation, even for relatively modest amounts of concentrated explosive products. This paper discusses the underlying theory of blast analysis and examines the practical application of non-linear, finite element based, explicit computational techniques for simulating the load acting on a structure due to internal and external blasts. The investigation of a recent, real-life industry failure of a heat exchanger due to a suspected internal detonation is discussed. Explicit, three-dimensional blast analysis is performed on the heat exchanger in question, and an internal detonation is simulated to reasonably replicate the considerable damage actually observed in the field. This analysis permits the determination of an approximate amount of concentrated product that caused the accidental explosion; that is, the plausible equivalent amount of explosives is back-calculated based on the predicted damage to the finite element model of the equipment in question. Computational iterations of varying charge amounts are performed and the predicted amount of permanent damage is documented so sensitivity to the hypothesized charge amount can be quantified. Furthermore, explicit blast analysis of nearby equipment is performed. In this investigation, computational results for both the heat exchanger (subjected to internal blast loading) and surrounding equipment (subjected to external blast loading) are in good agreement with the measured plastic deformations and failure modes that were actually observed in the field. Commentary on the likely detonation event that caused the significant damage observed is provided. Additionally, an advanced finite element failure criterion that is driven by plastic yielding is employed where portions of the computational model are removed from the simulation once a user-defined strain threshold is reached. This approach facilitates simulation of the gross heat exchanger pressure boundary failure actually observed in this case. The explicit finite element based analyses discussed in this study reasonably predict the structural response and damage characteristics corresponding to a recent, real-life industry failure.

scholarly journals Modelling and Dynamic Response of Steel Reticulated Shell under Blast Loading

2013 ◽  
Vol 20 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Ximei Zhai ◽  
Yonghui Wang
Keyword(s):  
Finite Element ◽  
Single Layer ◽  
Blast Loading ◽  
Element Model ◽  
Dynamic Responses ◽  
Empirical Formulas ◽  
Structural Dynamic ◽  
Explicit Finite Element ◽  
Long Span ◽  
Tnt Equivalent

Explicit finite element programme LS-DYNA was used to simulate a long-span steel reticulated shell under blast loading to investigate the structural dynamic responses in this paper. The elaborate finite element model of the Kiewitt-8 single-layer reticulated shell with span of 40 m subjected to central blast loading was established and all the process from the detonation of the explosive charge to the demolition, including the propagation of the blast wave and its interaction with structure was reproduced. The peak overpressure from the numerical analysis was compared with empirical formulas to verify the credibility and applicability of numerical simulation for blast loading. The dynamic responses of the structure under blast loading with different TNT equivalent weights of explosive and rise-span ratios were obtained. In addition, the response types of Kiewitt-8 single-layer reticulated shell subjected to central explosive blast loading were defined.

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