Relevant bibliographies by topics / Air blast loads

Academic literature on the topic 'Air blast loads'

Author: Grafiati
Published: 11 March 2023

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Journal articles on the topic "Air blast loads"

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Dobrociński, Stanisław, and Leszek Flis. "Numerical Simulations of Blast Loads from Near-Field Ground Explosions in Air." Studia Geotechnica et Mechanica 37, no. 4 (December 1, 2015): 11–18. http://dx.doi.org/10.1515/sgem-2015-0040.

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Abstract Numerical simulations of air blast loading in the near-field acting on the ground have been performed. A simplified blast model based on empirical blast loading data representing spherical and hemispherical explosive shapes has been simulated. Conwep is an implementation of the empirical blast models presented by Kingery and Bulmash, which is also implemented in the commercial code LS-DYNA based on work done by Rahnders-Pehrson and Bannister. This makes it possible to simulate blast loads acting on structures representing spherical and hemispherical explosive shapes of TNT with reasonable computational effort as an alternative to the SPH and Eulerian model. The CPU time for the simplified blast model is however considerably shorter and may still be useful in time consuming concept studies. Reasonable numerical results using reasonable model sizes can be achieved not only for modelling near-field explosions in air but most areas of geotechnical. Calculation was compared with blast SPH and Eulerian model.
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Ngo, Tuan, Priyan Mendis, A. Gupta, and J. Ramsay. "Blast Loading and Blast Effects on Structures – An Overview." Electronic Journal of Structural Engineering, no. 1 (January 1, 2007): 76–91. http://dx.doi.org/10.56748/ejse.671.

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The use of vehicle bombs to attack city centers has been a feature of campaigns by terrorist organizations around the world. A bomb explosion within or immediately nearby a building can cause catastrophic damage on the building's external and internal structural frames, collapsing of walls, blowing out of large expanses of windows, and shutting down of critical life-safety systems. Loss of life and injuries to occupants can result from many causes, including direct blast-effects, structural collapse, debris impact, fire, and smoke.The indirect effects can combine to inhibit or prevent timely evacuation, thereby contributing to additional casualties. In addition, major catastrophes resulting from gas-chemical explosions result in large dynamic loads, greater than the original design loads, of many structures. Due to the threat from such extreme loading conditions, efforts have been made during the past three decades to develop methods of structural analysis and design to resist blast loads. The analysis and design of structures subjected to blast loads require a detailed understanding of blast phenomena and the dynamic response of various structural elements. This paper presents a comprehensive overview of the effects of explosion on structures. An explanation of the nature of explosions and the mechanism of blast waves in free air is given. This paper also introduces different methods to estimate blast loads and structural response.
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Mohottige, Nimasha Weerasingha, Chengqing Wu, and Hong Hao. "Characteristics of Free Air Blast Loading Due to Simultaneously Detonated Multiple Charges." International Journal of Structural Stability and Dynamics 14, no. 04 (April 2, 2014): 1450002. http://dx.doi.org/10.1142/s0219455414500023.

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Extensive research has been conducted to investigate the characteristics of blast load due to single charge explosion, including numerical simulations and experimental blast tests in both unconfined and confined environments. Further, available guidelines for blast resistant design such as UFC-3-340-02 (2008) and ASCE 59-11 (2011) provide details to predict blast loads on a structure subjected to single charge explosion. However, blast load characteristics due to multiple charge explosions are poorly discussed in available literature. In this paper, commercially available Hydrocode, AUTODYN is calibrated for single charge explosions. Based on a comparison between numerical simulation and UFC prediction, correction factors for peak reflected pressure and positive reflected impulse as a function of charge weight, scaled distance and mesh size of the numerical model are proposed to minimize the errors in simulations. The calibrated AUTODYN model is then used to conduct parametric studies to investigate the effects of charge weight, scaled distance, number of charges and distance between the charges on the characteristics of free air blast load due to simultaneous detonated multiple charges. Numerical simulation results are used to derive analytical formulas for predictions of peak reflected pressure ratio and positive reflected impulse ratio between single and multiple explosions. The discussion is made on characteristics of free air blast load due to simultaneous detonated multiple charges.
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Hao, Yifei, Hong Hao, Yanchao Shi, Zhongqi Wang, and Ruiqing Zong. "Field Testing of Fence Type Blast Wall for Blast Load Mitigation." International Journal of Structural Stability and Dynamics 17, no. 09 (October 23, 2017): 1750099. http://dx.doi.org/10.1142/s0219455417500997.

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To protect structures from external explosions, solid protective barriers have been demonstrated by experimental and numerical studies to be able to effectively mitigate blast loads on structures behind them. However, to protect against blast loads, barriers normally need to be designed to have high structural resistance and ductility. This often requires bulky and heavy protective barriers which are not only highly costly but also often not appropriate for application in downtown areas as they are not friendly to city planning or appearance. Fence type blast wall consisting of structural columns was recently proposed and its effectiveness in mitigating blast loads was investigated through numerical simulations. It was found that the wave–fence interaction and interference of waves significantly reduced the wave energy when the blast wave passed through the fence blast wall. To further investigate the effectiveness and applicability of fence type blast wall as a highly potential technology for structural protection in an urban area, field tests have been conducted and results are reported in this paper. Columns with circular and triangular cross-sections were adopted to build fence blast walls. In addition, a masonry wall was also constructed as solid barrier for comparison. Hemispherical TNT explosive weighing 1.0 kg with different stand-off distances was detonated on the ground to generate the blast load. Blast overpressures in free air, behind the fence blast wall and behind the masonry wall were recorded by pressure sensors. The effectiveness of the fence blast wall in reducing blast wave and protecting structures was demonstrated by the test data.
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Anas, S. M., Mehtab Alam, and Mohammad Umair. "Air-blast and ground shockwave parameters, shallow underground blasting, on the ground and buried shallow underground blast-resistant shelters: A review." International Journal of Protective Structures 13, no. 1 (October 7, 2021): 99–139. http://dx.doi.org/10.1177/20414196211048910.

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Weak political systems and poor governance in certain developing countries are found to have a war-like environment where structures are being targeted by blasts and bombs. Industrial blasts due to frail know-how and mishandlings are also quite common. Recent accidental explosions like that occurred at the Beirut Port, Lebanon (August 2020); ammunition depot in the outskirt of the Ryazan City of Russia (November 2020) are of concern for the safety of adjacent building infrastructure and their users. Such intense loading events cause damage to certain elements of a structure which may result in disproportionate or progressive collapse. It necessitates a clear understanding of the phenomenon of the blast and extreme loads induced out of it, and response of the target structure under such loadings. In this study, the state of research on air-blast and ground shockwave parameters, shallow underground blasting, and on the ground and buried shallow blast-resistant shelters are presented. The phenomenon of the self-Mach-reflection of the explosion, loading parameters and empirical blast models available in the open literature followed by the damage criteria for the buildings subjected to the underground blasting and available peak particle velocity (PPV) prediction models have been discussed. To make the application of advanced materials such as fibrous concrete, ultra-high performance concrete, FRP composites, etc., it is important to comprehend the existing blast/shock-resistant shelters and their response under such loading. The shelters are primarily designed by incorporating features of the materials like high degree of deformability/ductility, use of the shock-isolation panels and the mechanism for controlling crack formations. Finally, conclusions and recommendations for future studies are summarised. This paper presents prospects to engineers, town planners, researchers, policymakers and members of the core drafting sectional committees to understand the phenomenon of the blast and extreme loads induced out of it.
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Akhlaghi, Ebrahim. "Numerical Simulation of Air Shock Wave Propagation Effects in Reinforced Concrete Columns." Journal of Modeling and Optimization 12, no. 1 (June 15, 2020): 12–22. http://dx.doi.org/10.32732/jmo.2020.12.1.12.

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Reinforced concrete has been shown to be a desirable material of choice in blast resistant structures due to its availability, relatively low cost, and its inherent ability to absorb energy produced by explosions. Most research work investigating the behaviour of reinforced concrete columns to blast loading have concentrated on their response to planar loading from far-field explosions. Limited amount of work is available on the effects of near-field explosion on the behaviour of reinforced concrete columns. This study is aimed to investigate effects of explosive loads on RC column by using ALE method. Commercial finite element package, LS-DYNA is used to simulate the behavior of blast wave on RC columns. Numerical simulation is validated against experimental work done in literature. The experience gained from this research provides valuable information for the development of the finite element modeling of real blast load effects on RC columns.
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Chirica, Ionel, and Elena Felicia Beznea. "Structural Solutions for Ship Hull Plates Strengthening, under Blast Loads." Key Engineering Materials 601 (March 2014): 76–79. http://dx.doi.org/10.4028/www.scientific.net/kem.601.76.

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The paper presents selected results of a study concerning the protective capacity of ship hull plates, made out of layered composite plates. A scenario to evaluate the behaviour of the ship structure plate under blast loading is presented. The nonlinear analysis on a 3-D FEM model by using composite elements was performed. The methodology for the blast pressure charging and the mechanism of the blast wave in free air are given. The space pressure variation is determined by using Friedlander exponential decay equation. According to the methods used in this paper an individual pressure-time history to each element based on its distance from the blast is assigned. The dynamic response of the composite plate is shown.
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Clough, Laurence G., and Simon K. Clubley. "Steel column response to thermal and long duration blast loads inside an air blast tunnel." Structure and Infrastructure Engineering 15, no. 11 (July 11, 2019): 1510–28. http://dx.doi.org/10.1080/15732479.2019.1635627.

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DENG, RONG-BING, and XIAN-LONG JIN. "THREE-DIMENSIONAL SIMULATION OF CONDENSED EXPLOSIVE-INDUCED FLOW PROPAGATION AND INTERACTION WITH GLASS CURTAIN WALL." Modern Physics Letters B 24, no. 09 (April 10, 2010): 833–48. http://dx.doi.org/10.1142/s0217984910022895.

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In order to carry out blast response of curtain wall, the first step is to understand the complex flow of the air blasts around the structures and predict the blast loads acting on the structures. But in earlier studies related to blast resistant design of glass curtain wall, blast flow induced by condensed explosive is not taken into account due to expensively computational resources required. Based on high performance computing, this paper presents a new three-dimensional numerical simulation method of condensed explosive-induced flow propagation and impact on a complex glass curtain wall, where the fluid is represented by solving Navier–Stokes equations with a multimaterial arbitrary Lagrangian–Eulerian (ALE) formulation. In particular, the whole analytical model consists of condensed explosive, air, detailed curtain wall system, and ground, which comprehensively represents the real fluid–structure interaction environment. Final calculation has been performed on the Dawning 4000A supercomputer based on the domain decomposition method. The flow mechanisms of blast wave rounding curtain wall is visualized and the simulated pressure history of gauge is in good agreement with the experimental result which validates this method. The present method is shown to be a useful tool for blast resistance design of curtain wall in the future.
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Lee, Chang-Yull, Jin-Young Jung, and Se-Min Jeong. "Active Vibration Suppression of Stiffened Composite Panels with Piezoelectric Materials under Blast Loads." Applied Sciences 10, no. 1 (January 4, 2020): 387. http://dx.doi.org/10.3390/app10010387.

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Transient responses of stiffened panels with piezoelectric sensors and actuators are studied under normal blast loads. The air vehicles could be exposed to blast pulses generated by an explosion or shock-wave disturbances. Thus, active vibration suppression of the vehicles is important under blast loadings. The structural model is designed as a laminated composite panel with lead zirconate titanate (PZT) piezoceramic layers embedded on both top and bottom surfaces. A uniformly distributed blast load is assumed over the whole of the panel surface. The first-order shear deformation theory of plate is adopted, and the extended Hamilton’s principle is applied to derive the equations of motions. The numerical model is verified by the comparison with previous data. Using linear quadratic regulator (LQR) control algorithm, vibration characteristics and dynamic responses are compared. As piezoelectric patches are attached on the whole of the surface, the effect of the stiffener’s location is studied. Furthermore, the influences of the patch’s positions are also investigated through subjection to the blast wave. From various results, in order to get the best control performances, the research aims to find the optimum position of sensor and actuator pairs that is most effective under blast load environments.
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Dissertations / Theses on the topic "Air blast loads"

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Emmanuelli, Gustavo. "An Assessment of State Equations of Air for Modeling a Blast Load Simulator." Thesis, Mississippi State University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10979719.

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When an explosive detonates above ground, air is principally the only material involved in the transmission of shock waves that can result in damage. Hydrodynamic codes that simulate these explosions use equations of state (EOSs) for modeling the behavior of air at these high-pressure, high-velocity conditions. An investigation is made into the effect that the EOS selection for air has on the calculated overpressure-time waveforms of a blast event. Specifically, the ideal gas, Doan-Nickel, and SESAME EOSs in the SHAMRC code were used to reproduce experiments conducted at the Blast Load Simulator (BLS), a large-scale shock tube operated by the U.S. Army Engineer Research and Development Center, that consisted of subjecting an instrumented rigid box at three angles of orientation inside the BLS to a blast environment. Numerical comparisons were made against experimentally-derived confidence intervals using peak values and several error metrics, and an attempt was made to rank the EOS based on performance. Issues were noted with the duration of decay from maximum pressure to negative phase that resulted in a general underprediction of the integrated impulse regardless of EOS, while the largest errors were noted for gages on faces at 45 to 90 degrees from the initial flow direction. Although no significant differences were noticed in the pressure histories from different EOSs, the ideal gas consistently ranked last in terms of the error metrics considered and simultaneously required the least computing resources. Similarly, the Doan-Nickel EOS slightly performed better than SESAME while requiring additional wallclock time. The study showed that the Doan-Nickel and SESAME EOSs can produce blast signatures with less errors and more matches in peak pressure and impulse than the ideal gas EOS at the expense of more computational requirements.

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Bedon, Chiara. "Problemi di stabilità negli elementi in vetro strutturale e studio innovativo di facciate in vetro-acciaio sottoposte a carico da esplosione." Doctoral thesis, Università degli studi di Trieste, 2012. http://hdl.handle.net/10077/7403.

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2010/2011
Recentemente, la richiesta architettonica sempre più spinta di trasparenza e luminosità ha favorito la diffusione nell’edilizia del vetro come materiale da costruzione. Sebbene si tratti di un materiale ancora poco conosciuto rispetto ad altri materiali convenzionali, il vetro trova, infatti, ampia applicazione nelle realizzazioni strutturali più innovative. Anche se le soluzioni architettoniche proposte trovano ampio consenso, spesso la difficoltà principale consiste nel dimensionare adeguatamente tali elementi e nel preservarne l’integrità da eventuali fenomeni di instabilità. Con riferimento a questo tema, nella presente tesi vengono proposte alcune significative formulazioni analitiche per la verifica di stabilità di elementi in vetro monolitico, stratificato o vetro-camera, con particolare attenzione per il comportamento di travi compresse, travi inflesse, pannelli sottoposti a compressione nel piano o taglio nel piano. Allo stesso tempo, viene studiato il comportamento di facciate in vetro-acciaio sottoposte a carico da esplosione, con riferimento specifico a due tipologie di facciata note come facciate continue a lastre indipendenti, controventate da un sistema di cavi pretesi, e facciate a pannelli, nelle quali le lastre di vetro sono sostenute da un telaio metallico di supporto. Per ciascuna tipologia di facciata, vengono evidenziate le criticità dovute a carichi da esplosione di varia intensità mediante opportuni modelli numerici. Inoltre, viene analizzato l’effetto di eventuali dispositivi in grado di mitigarne le componenti principali assorbendo e/o dissipando parte dell’energia d’ingresso associata all’evento esplosivo.
Recently, due to aesthetic and architectural requirements of transparency and lightness, the use of glass as a structural material showed a strong increase. Although its load carrying behavior is actually not well-known, glass finds large application in modern and innovative buildings. Nevertheless, the main difficulties are related to the proper design of these structural elements and in the preservation of their integrity, avoiding possible buckling phenomena. In this context, this Doctoral Thesis proposes a series of interesting analytical formulations suitable for the buckling verification of monolithic, laminated, insulated structural glass element, with particular attention for the load carrying behavior of beams in compression or in bending, as well as for the buckling response of glass panels subjected to in-plane compression or shear. At the same time, the Thesis focuses also on the dynamic behavior of two different typologies of steel-glass façades subjected to air blast loads, whit particular attention to the analysis of cable-supported façades and conventional curtain walls, in which a metallic frame supports the glass panels. In both the circumstances, accurate numerical simulations are performed to highlight the criticalities of similar structural systems, in presence of high-level or medium / low-level air blast loads. Finally, the structural benefits of possible devices able to mitigate the effects of explosions in the main components of these façades, by partly storing / dissipating the incoming energy, are investigated numerically and analytically.
XXIV Ciclo
1983
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Book chapters on the topic "Air blast loads"

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Kinney, Gilbert Ford, and Kenneth Judson Graham. "Dynamic Blast Loads." In Explosive Shocks in Air, 161–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-86682-1_10.

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Maazoun, Azer. "New Technique to Protect RC Slabs Against Explosions Using CFRP as Externally Bonded Reinforcement." In Critical Energy Infrastructure Protection. IOS Press, 2022. http://dx.doi.org/10.3233/nicsp220010.

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One of today’s state-of-the-art techniques for strengthening of reinforced concrete structural elements is the use of Carbon Fiber Reinforced Polymer (CFRP) composite strips as Externally Bonded Reinforcement (EBR). This is justified for quasi-static loads by the high strength, light weight, and excellent durability characteristics of CFRP EBR in combination with their ease of application. This paper deals with the performance of the technique for blast loads. This paper investigates the usefulness of CFRP EBR to improve the flexural resistance capacity of reinforced concrete hollow core slabs (RCHCS) under blast loads. In order to achieve this objective, three simply supported RCHCS with a compression layer were subjected to an explosion test. The obtained experimental results of the RCHCS without and with EBR are presented and discussed with the aim of evaluating the influence of EBR on the blast response of the RCHCS. A numerical analysis is also carried out using the finite element software LS-DYNA to complement the experimental results.
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Langdon, Genevieve S., Christopher J. von Klemperer, Gregory Sinclair, and Ismail Ghoor. "Influence of Curvature and Load Direction on the Air-Blast Response of Singly Curved Glass Fiber Reinforced Epoxy Laminate and Sandwich Panels." In Explosion Blast Response of Composites, 133–60. Elsevier, 2017. http://dx.doi.org/10.1016/b978-0-08-102092-0.00006-6.

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von Klemperer, C. J., G. S. Langdon, G. Sinclair, and I. Ghoor. "Comparison of curved GFRE foam sandwich panels response to close-proximity air-blast loading: Influence of curvature and load direction." In Advances in Engineering Materials, Structures and Systems: Innovations, Mechanics and Applications, 779–83. CRC Press, 2019. http://dx.doi.org/10.1201/9780429426506-135.

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Conference papers on the topic "Air blast loads"

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Zhang, Timothy G., Sikhanda S. Satapathy, Amy M. Dagro, and Philip J. McKee. "Numerical Study of Head/Helmet Interaction due to Blast Loading." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63015.

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Recent wars have heightened the need to better protect dismounted soldiers against emerging blast and ballistic threats. Traumatic Brain Injury (TBI) due to blast and ballistic loading has been a subject of many recent studies. In this paper, we report a numerical study to understand the effects of load transmitted through a combat helmet and pad system to the head and eventually to the brain during a blast event. The ALE module in LS-DYNA was used to model the interactions between fluid (air) and the structure (helmet/head assembly). The geometry model for the head was generated from the MRI scan of a human head. For computational simplicity, four major components of the head are modeled: skin, bone, cerebrospinal fluid (CSF) and brain. A spherical shape blast wave was generated by using a spherical shell air zone surrounding the helmet/head structure. A numerical evaluation of boundary conditions and numerical algorithm to capture the wave transmission was carried out first in a simpler geometry. The ConWep function was used to apply blast pressure to the 3D model. The blast pressure amplitude was found to reduce as it propagated through the foam pads, indicating the latter’s utility in mitigating blast effects. It is also shown that the blast loads are only partially transmitted to the head. In the calculation where foam pads were not used, the pressure in the skin was found to be higher due to the underwash effect in the gap between the helmet and skin, which amplified the blast pressure.
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Kim, Jeong-Ho, Linhui Zhang, Jefferson T. Wright, Rainer Hebert, and Arun Shukla. "Dynamic Response of Corrugated Sandwich Plates Under Shock Tube Loading." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63522.

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This paper addresses three-dimensional dynamic finite element analysis and validations for strain-rate dependent elastic-plastic sandwich steel plate with various corrugated core arrangements subjected to dynamic air pressure loads. The sandwich steel plate consists of top and bottom flat substrates of Steel 1018 and corrugated core layers of Steel 1008. The developed model is validated with a set of shock tube experiments. Various corrugated core arrangements are taken into consideration for optimizing core design parameters in order to maximize mitigation of blast load effects onto the structure.
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Tan, X. Gary, and Amit Bagchi. "Computational Analysis for Validation of Blast Induced Traumatic Brain Injury and Protection of Combat Helmet." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87689.

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Current understanding of blast wave transmission and mechanism of primary traumatic brain injury (TBI) and the role of helmet is incomplete thus limiting the development of protection and therapeutic measures. Combat helmets are usually designed based on costly and time consuming laboratory tests, firing range, and forensic data. Until now advanced medical imaging and computational modeling tools have not been adequately utilized in the design and optimization of combat helmets. The goal of this work is to develop high fidelity computational tools, representative virtual human head and combat helmet models that could help in the design of next generation helmets with improved blast and ballistic protection. We explore different helmet configurations to investigate blast induced brain biomechanics and understand the protection role of helmet by utilizing an integrated experimental and computational method. By employing the coupled Eulerian-Lagrangian fluid structure interaction (FSI) approach we solved the dynamic problem of helmet and head under the blast exposure. Experimental shock tube tests of the head surrogate provide benchmark quality data and were used for the validation of computational models. The full-scale computational NRL head-neck model with a combat helmet provides physical quantities such as acceleration, pressure, strain, and energy to blast loads thus provides a more complete understanding of the conditions that may contribute to TBI. This paper discusses possible pathways of blast energy transmission to the brain and the effectiveness of helmet systems at blast loads. The existing high-fidelity image-based finite element (FE) head model was applied to investigate the influence of helmet configuration, suspension pads, and shell material stiffness. The two-phase flow model was developed to simulate the helium-air shock wave interaction with the helmeted head in the shock tube. The main contribution was the elucidation of blast wave brain injury pathways, including wave focusing in ocular cavities and the back of head under the helmet, the effect of neck, and the frequency spectrum entering the brain through the helmet and head. The suspension material was seen to significantly affect the ICP results and energy transmission. These findings can be used to design next generation helmets including helmet shape, suspension system, and eye protection.
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Berg, Vanessa, Jerome H. Stofleth, Dale S. Preece, and Venner Saul. "Analysis of Dynamic Loading of a Simple Structure to a Blast Wave." In ASME 2002 Pressure Vessels and Piping Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/pvp2002-1148.

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An object in the path of a blast wave generated by an explosion will experience a certain level of structural damage. The degree of destruction seen in a structure from a explosive blast wave is effected by three main parameters, (1) the force applied to the structure, (2) how long the force is acting on the structure, and (3) the specific geometric and material properties of the structure, or architectural surety. Structures capable of large lateral loads can be used for defense against explosions (terrorist threats). However, in order to fully predict the architectural surety of a structure, further investigation of the interaction of explosive blast waves with structures is required. The purpose of our analysis is to determine the efficiency of coupling energy from a blast wave to a simple structure. We performed some explosives tests and computer simulations to provide this analysis. In our experiments, the structures consisted of several free hanging steel plates at various distances from an explosion. The blast wave was generated by a sphere of TNT. We used a standard model to calculate the overpressure incident on this plates, we then calculated the shock energy coupled to the plates, we measured the overpressure at points near the plates (for calibration), we measured the effects of the blast wave on the plates (measured their displacement due to the blast), and we performed computer code calculations to predict the effect of the blast wave on the plates. The computational code Autodyn is currently being used at Sandia National Laboratories for various impact and blast loading problems. The code contains several simulation methods, including ALE (Arbitrary Langrangian Eulerian) simulation. Because explosive blast in air involves both expanding gases as well as solid/solid impacts, ALE codes typically provide better predictive capabilities.
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Reinauer, G. A., and M. Peszynski. "Weight Reduction in a Marine Gas Turbine Inlet." In ASME 1985 International Gas Turbine Conference and Exhibit. American Society of Mechanical Engineers, 1985. http://dx.doi.org/10.1115/85-gt-75.

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Major design changes to the Propulsion Gas Turbine Air Inlet on the US Navy’s CG47 Class Guided Missile Cruisers have resulted in significant superstructure weight savings. The majority of weight reduction resulted from use of finite element analysis (FEA) computer modeling techniques applied to structural optimization. FEA models of the forward and aft deckhouses provided the necessary capability to analyze each structure’s response to loads simulating a nuclear air blast, shock, and vibration. Integration of the moisture separator housings into each deckhouse structure allowed improved structural stability and additional weight reductions. FEA modeling and a redesign of the major inlet system 32% lighter than inlets installed onearly ships of this class. The first of the lightweight deckhouses has been installed on the CG52 Cruiser.
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Karpanan, Kumarswamy, and Brendan O’Toole. "Experimental and Numerical Analysis of Structures With Bolted Joints Subjected to High Impact Load: Part 2." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63068.

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Military vehicles sustain damaging high impacts and shock loadings due to mine blasts, projectile impacts, and frontal or rear crashes. In all these cases, the vehicle structure and the bolts used in the structure may experience high impact loads. These loads may yield or damage the structure and the bolts. Only a limited amount of published literature describes the proper method for measuring and analyzing transient shock propagation across bolted connections for high-impact loading. Understanding, modeling, and simulating the vehicle response to these impact loadings is critical to designing better vehicle components. This will also help isolate critical components such as electronics and personnel from the shock. This paper provides a detailed experimental setup and procedure for analyzing high-impact loading on structures with bolted joint connections. An air gun was used to fire an aluminum slug at high velocities on to a bolted structure to induce medium- and high-impact loading. Two structural configurations were evaluated: a hat section bolted to a flat plate, and two hat sections bolted together. Finite element models were created to simulate the damage and shock propagation phenomena during impact. Simulation predictions from detailed 3D solid element models and 2D shell element models were compared to experimental results, including shape deformation and accelerometer data at specific locations. A load cell recording impact force was also used for validation of the simulation. The simplified FE model developed for the bolted joint structure in this report reduced the computational time by one order and can be practically implemented in the full vehicle FE model for crash or blast analysis.
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Karpanan, Kumarswamy, and Brendan O’Toole. "Experimental and Numerical Analysis of Structures With Bolted Joints Subjected to Low Impact Load: Part 1." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63711.

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Bolted joints are the most common type of fastener in army vehicles and play a very important role in maintaining the structural integrity of combat vehicles. In combat, these vehicles may be subjected to various kinds of shock loading, such as initiated by a mine blast, projectile impact, or frontal crash. This study analyzes the transient behavior of structures with bolted joints subjected to impact or shock loads using experimental methods and Finite Element Analysis (FEA). Factors such as damping that affect the bolted joint structures for shock loading are studied. Only a limited amount of published literature describes the proper method for analyzing transient shock propagation across bolted connections for high-impact loading. The initial case study focused on a simple cantilever beam with a bolted lap joint subjected to relatively low levels of impact force. The second case study used a flat plate bolted to a hat-section. These simple configurations are representative of structures found in many military ground vehicles that can be subjected to transient impact and blast loads. These structures were subjected to low-impact loading (non-destructive) using impact hammers and high-impact loading (destructive) using an air gun. The responses were measured using accelerometers. LS-DYNA FE solver was used to simulate the shock propagation in the bolted structures. For all the bolted structures, the modal analysis was performed both experimentally and numerically. The results are in excellent agreement for the lower modes and exhibit a small deviation in the higher modes. Secondly, the time history responses of experimental and FE analysis are compared. This is a two-part paper. In this first paper, a simplified bolted connection (bolted cantilever beam) is used for studying the low-impact shock propagation.
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8

Sotudeh-Chafi, M., N. Abolfathi, A. Nick, V. Dirisala, G. Karami, and M. Ziejewski. "A Multi-Scale Finite Element Model for Shock Wave-Induced Axonal Brain Injury." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192342.

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Traumatic brain injuries (TBIs) involve a significant portion of human injuries resulting from a wide range of civilian accidents as well as many military scenarios. Axonal damage is one of the most common and important pathologic features of traumatic brain injury. Axons become brittle when exposed to rapid deformations associated with brain trauma. Accordingly, rapid stretch of axons can damage the axonal cytoskeleton, resulting in a loss of elasticity and impairment of axoplasmic transport. Subsequent swelling of the axon occurs in discrete bulb formations or in elongated varicosities that accumulate organelles. Ultimately, swollen axons may become disconnected [1]. The shock waves generated by a blast, subject all the organs in the head to displacement, shearing and tearing forces. The brain is especially vulnerable to these forces — the fronts of compressed air waves cause rapid forward or backward movements of the head, so that the brain rattles against the inside of the skull. This can cause subdural hemorrhage and contusions. The forces exerted on the brain by shock waves are known to damage axons in the affected areas. This axonal damage begins within minutes of injury, and can continue for hours or days following the injury [2]. Shock waves are also known to damage the brain at the subcellular level, but exactly how remains unclear. Kato et al., [3] described the effects of a small controlled explosion on rats’ brain tissue. They found that high pressure shock waves led to contusions and hemorrhage in both cortical and subcortical brain regions. Based on their result, the threshold for shock wave-induced brain injury is speculated to be under 1 MPa. This is the first report to demonstrate the pressure-dependent effect of shock wave on the histological characteristics of brain tissue. An important step in understanding the primary blast injury mechanism due to explosion is to translate the global head loads to the loading conditions, and consequently damage, of the cells at the local level and to project cell level and tissue level injury criteria towards the level of the head. In order to reach this aim, we have developed a multi-scale non-linear finite element modeling to bridge the micro- and macroscopic scales and establish the connection between microstructure and effective behavior of brain tissue to develop acceptable injury threshold. Part of this effort has been focused on measuring the shock waves created from a blast, and studying the response of the brain model of a human head exposed to such an environment. The Arbitrary Lagrangian Eulerian (ALE) and Fluid/Solid Interactions (FSI) formulation have been used to model the brain-blast interactions. Another part has gone into developing a validated fiber-matrix based micro-scale model of a brain tissue to reproduce the effective response and to capturing local details of the tissue’s deformations causing axonal injury. The micro-model of the axon and matrix is characterized by a transversely isotropic viscoelastic material and the material model is formulated for numerical implementation. Model parameters are fit to experimental frequency response of the storage and loss modulus data obtained and determined using a genetic algorithm (GA) optimizing method. The results from macro-scale model are used in the micro-scale brain tissue to study the effective behavior of this tissue under injury-based loadings. The research involves the development of a tool providing a better understanding of the mechanical behavior of the brain tissue against blast loads and a rational multi-scale approach for driving injury criteria.
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9

Barbour, Jason P., and Douglas C. Hittle. "Modeling Phase Change Materials With Conduction Transfer Functions for Passive Solar Applications." In ASME 2003 International Solar Energy Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/isec2003-44073.

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The use of passive solar design in our homes and buildings is one way to offset the ever-increasing dependence on fossil fuels and the resulting pollution to our air, our land, and our waters. A well-designed sunroom has the potential to reduce the annual heating loads by one-third or more. By integrating phase change materials (PCMs) into building elements such as floor tile and wallboard, the benefits of the sunroom can be further enhanced by providing enhanced energy storage. To maximize benefits from PCMs, an engineering analysis tool is needed to provide insight into the most efficient use of this developing technology. Thus far, modeling of the phase change materials has been restricted to finite difference and finite element methods, which are not well suited to inclusion in a comprehensive annual building simulation program such as BLAST or EnergyPlus (BLAST Support Office, 1991; Crawley et al, 2001). Conduction transfer functions (CTFs) have long been used to predict transient heat conduction in such programs (Sowell and Hittle, 1995). Phase changes often do not occur at a single temperature, but do so over a range of temperatures. The phase change energy can be represented by an elevated heat capacity over the temperature range during which the phase change occurs (Kedl, 1991). By calculating an extra set(s) of CTFs for the phase change properties, the CTF method can be extended to include the energy of phase transitions by switching between the two (or more) sets of CTFs. This method can be used to accurately predict the internal and external temperatures of PCM-containing building elements during transient heat conduction. The amount of energy storage and release during a phase transition can also be modeled with this method, although there may be some degree of inaccuracy due to switching between two or more sets of CTFs.
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10

Hinz, Brandon J., Matthew V. Grimm, Karim H. Muci-Ku¨chler, and Shawn M. Walsh. "Comparative Study of the Dynamic Response of Different Materials Subjected to Compressed Gas Blast Loading." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64395.

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Understanding the dynamic response of materials under blast and impact loading is of interest for both military and civilian applications. In the case of blast loading, the mitigation characteristics of materials employed in personal protective equipment (PPE) is of particular importance. Without adequate protection, exposure of the head to blast waves may result in or contribute to brain tissue damage leading to traumatic brain injury (TBI). The development of simple but representative laboratory experiments that can be used to study the mechanical response of different materials and/or material combinations to blast loading could be very useful for the design of PPE such as helmets. This paper presents a basic experimental setup that can be conveniently used to perform such studies using small scale compressed gas blasts. An open end shock tube is employed to generate the blasts used to load flat plate samples placed in a special rigid holder. Acceleration time histories at selected locations in the sample are used to generate data to compare the dynamic response and blast mitigation effectiveness of different specimens. High speed schlieren video is used to correlate the arrival of the shock wave and air flow that follows with the motion of the test sample.
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