scholarly journals On models of blast overpressure effects to the thorax

2020 ◽  
Vol 2 (12) ◽  
Author(s):  
Alexander Stottmeister ◽  
Malte von Ramin ◽  
Johannes M. Schneider
Keyword(s):  
Shock Wave ◽  
Free Field ◽  
Viscoelastic Behavior ◽  
Harmonic Oscillators ◽  
Blast Overpressure ◽  
Lung Injuries ◽  
Time Histories ◽  
Physical Response ◽  
Blast Wave Propagation ◽  
The Individual

AbstractShock waves from explosions can cause lethal injuries to humans. Current state-of the-art models for pressure induced lung injuries were typically empirically derived and are only valid for detonations in free-field conditions. In built-up environments, though, pressure–time histories differ significantly from this idealization and not all explosions exhibit detonation characteristics. Hence, those approaches cannot be deployed. However, the actual correlation between dynamic shock wave characteristics and gradual degree of injury have yet to be fully described. In an attempt to characterize the physical response of the human body to complex shock-wave effects, viscoelastic models were developed in the past (Axelsson and Yelverton, in J Trauma Acute Care Surg 40, 31S–37S, 1996; Stuhmiller et al., in J Biomech. 10.1016/0021-9290(95)00039-9, 1996). We discuss those existing modeling approaches especially in view of their viscoelastic behavior and point out drawbacks regarding their response to standard stimuli. Further, we suggest to fully acknowledge the experimentally anticipated viscoelastic behavior of the effective thorax models by using a newly formulated standard model for viscoelastic solids instead of damped harmonic oscillators. Concerning injury assessment, we discuss the individual injury criteria proposed along with existing models pointing out desirable improvements with respect to complex blast situations, e.g. the necessity to account for repeated exposure (criteria with time-memory), and further adaption with respect to nonlinear gas dynamics inside the lung. Finally, we present an improved modeling approach for complex blast overpressure effects to the thorax with few parameters that is more suitable for the characteristics of complex blast wave propagation than other current models.

scholarly journals Effects of Explosion Shock Waves on Lung Injuries in Rabbits

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yanlong Sun ◽  
Xinming Qian ◽  
Chi-Min Shu ◽  
Ziyuan Li ◽  
Mengqi Yuan ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Free Field ◽  
Damage Mechanism ◽  
Injury Mechanism ◽  
Severe Injury ◽  
Severe Injuries ◽  
Lung Injuries ◽  
Test Points ◽  
Hematoxylin Eosin

The purpose of this study was to explore the damage effects and injury mechanism of free-field explosion shock waves on rabbit lungs. Six free-field explosion experiments, each with 500 g trinitrotoluene (TNT), were conducted as the shock wave overpressure acting on the rabbits was measured. The peak overpressure of the shock wave was 533, 390, 249, 102, and 69 kPa at the respective test points. Damage to the rabbit lungs caused by shock wave overpressure was investigated through observation, anatomical analysis, and hematoxylin-eosin (HE) staining processing. The shock wave overpressure of 69–102 kPa caused mild-to-moderate injury; the shock wave overpressure of 102–249 kPa caused moderate injury; the shock wave overpressure of 249–390 kPa resulted in moderate-to-severe injury; and the shock wave overpressure of 390–533 kPa caused severe injury to the rabbit. Mild, moderate, and severe injuries destroyed some, most, or all alveolar structures, correspondingly, as well as producing partial cell apoptosis. The overpressure damage mechanism primarily involves the collapse and rupture of pulmonary alveolus in the lung tissue. As a novel attempt, the investigation provided here may serve to improve the current shock wave injury mechanism.

Shock waves in microchannels

2013 ◽  
Vol 724 ◽  
pp. 259-283 ◽  
Author(s):  
G. Mirshekari ◽  
M. Brouillette ◽  
J. Giordano ◽  
C. Hébert ◽  
J.-D. Parisse ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
Large Scale ◽  
Numerical Models ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Navier Stokes ◽  
Shock Attenuation ◽  
Pressure Time ◽  
Time Histories

AbstractA fully instrumented microscale shock tube, believed to be the smallest to date, has been fabricated and tested. This facility is used to study the transmission of a shock wave, produced in a large (37 mm) shock tube, into a 34 $\mathrm{\mu} \mathrm{m} $ hydraulic diameter and 2 mm long microchannel. Pressure microsensors of a novel design, with gigahertz bandwidth, are used to obtain pressure–time histories of the microchannel shock wave at five axial stations. In all cases the transmitted shock wave is found to be weaker than the incident shock wave, and is observed to decay both in pressure and velocity as it propagates down the microchannel. These results are compared with various analytical and numerical models, and the best agreement is obtained with a Navier–Stokes computational fluid dynamics computation, which assumes a no-slip isothermal wall boundary condition; good agreement is also obtained with a simple shock tube laminar boundary layer model. It is also found that the flow developing within the microchannel is highly dependent on conditions at the microchannel entrance, which control the mass flux entering into the device. Regardless of the micrometre dimensions of the present facility, shock wave propagation in a microchannel of that scale exhibits a behaviour similar to that observed in large-scale facilities operated at low pressures, and the shock attenuation can be explained in terms of accepted laminar boundary models.

scholarly journals Shock-Wave Studies Of Ice Under Uniaxial Strain Conditions

1984 ◽  
Vol 30 (105) ◽  
pp. 235-240 ◽  
Author(s):  
Donald B. Larson
Keyword(s):  
Shock Wave ◽  
Wave Velocity ◽  
Particle Velocity ◽  
Uniaxial Strain ◽  
Mixed Phase ◽  
Stable Form ◽  
Static Compression ◽  
Compression Cycle ◽  
Stress Levels ◽  
Time Histories

AbstractShock-wave studies of ice under uniaxial strain conditions have been conducted at stress levels up to 3.6 GPa. A light-gas gun accelerated the flat-faced projectile used to impact the ice-containing targets. The ice samples were initially at ambient pressure and at temperatures of –10 ± 2° C. Gages were implaced at different distances in the ice along the path of the shock wave to measure particle velocity time histories inside the ice samples. The recorded time histories of particle velocity show a precursor wave with an average wave velocity of 3.7 km/s and an average particle velocity amplitude of 0.06 km/s. This wave is travelling at a wave velocity approximately 10% greater than longitudinal sound speed and is believed to originate because of the onset of melting of ice I.The particle velocity data from these experiments were converted to stresses and volumes using Lagrangian gage analysis and the assumption of a simple non-steady wave. This conversion provides a complete compression cycle (which includes both loading and unloading paths) for comparison with static measurements. All experiments show the onset of melting at 0.15 to 0.2 GPa. Experiments with maximum stress states between 0.2 and 0.5 GPa yield results which suggest that a mixed phase of ice I and liquid water exists at these conditions. For maximum loading stresses between 0.6 and 1.7 GPa the experimental results suggest that the final state is predominately ice VI. In these experiments the specific volume upon compression is changed from 1.09 m3/Mg to approximately 0.76 m3/Mg, which represents compaction of approximately 30%. The unloading paths determined from these experiments indicate that ice VI remains in a “frozen” or metastable state during most of the unloading process. This hysteresis in the compression cycle gives rise to a large “loss” of shock-wave energy to the transformation process. At stress levels above 2.2 GPa, ice VII should be the stable form for water according to static compression measurements. Experimental data at 2.4 and 3.6 GPa suggest that ice VII may be formed but these results indicate a mixed phase of ice VI and ice VII rather than complete transformation to ice VII.

The Strain Dependence of Rubber Viscoelasticity. II. The Influence of Carbon Black

1962 ◽  
Vol 35 (4) ◽  
pp. 918-926 ◽  
Author(s):  
P. Mason
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Particle Diameter ◽  
Viscoelastic Behavior ◽  
Spherical Particles ◽  
Rubber Compound ◽  
Similar Treatment ◽  
Linear Relations ◽  
The Individual ◽  
Individual Particles

Abstract In Part I of this series it was shown how variations in the dynamic Young's modulus with extension could be represented by linear relations for gum rubbers in the region of 0 to 100% extension. The present work uses a similar treatment to examine how the viscoelastic behavior of natural rubber within this extension region is affected by the incorporation of two carbon blacks of widely differing colloidal activity. One of these materials, MT black, consists substantially of spherical particles with a mean diameter of about 0.4 microns: electron microscopy of cut surfaces of the black-rubber compound showed that the individual particles were well-dispersed. The finer material, HAF black, has a mean particle diameter of about 0.04 microns but exists in the rubber compound in a flocculated condition with aggregates up to about 0.3 microns in diameter. The rubber containing the coarse, MT black yielded linear strain relations enabling a direct comparison to be made with the behavior of the gum: the HAF material did not give linear relations for either the dynamic or the equilibrium Young's modulus. To facilitate discussion of this behavior it is desirable to set out more explicitly than in Part I the model underlying the analysis.

Research of Elastomeric Protective Layers Subjected to Blast Wave

2011 ◽  
Vol 82 ◽  
pp. 680-685
Author(s):  
Jerzy Malachowski ◽  
Tadeusz Niezgoda
Keyword(s):  
Shock Wave ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Blast Wave ◽  
Shape Effect ◽  
Element Analysis ◽  
Protective Layers ◽  
Lagrange Formulation ◽  
Explosive Materials ◽  
Blast Wave Propagation

The paper is based on non–linear finite element analysis of the blast wave effects on structures, caused by the detonation of explosive materials. Dynamic response of a structure with and without elastomeric layers subjected to the shock wave produced by the detonation of high explosive materials is presented in this paper. Coupled Euler and Lagrange formulation are used in the finite element analysis of such problems to accurately represent the detonation phenomenon. Research related to blast wave propagation is not only aimed at its effect on structures but also on developing new concepts of protective panels. The research carried out on various structures (such as multi–layer panels) has been performed to find out the most efficient protection against a detonation wave. Tests of multi-layer protective panels ability to absorb the explosion energy were also conducted under field conditions and confirmed in numerical studies. The application of structural protective layers made of elastomeric material significantly reduced the blast wave thanks to dissipation capabilities. Additionally, the shape effect of structural steel elements (streamlined profile) during the interaction process with a shock wave has been also confirmed.

Evaluation of Intracranial Pressure Response in Rats Exposed to Complex Shock Waves

2012 ◽  
Author(s):  
Alessandra Dal Cengio Leonardi ◽  
Nickolas Keane ◽  
Cynthia Bir ◽  
Pamela VandeVord
Keyword(s):  
Intracranial Pressure ◽  
Shock Waves ◽  
Blast Wave ◽  
Preliminary Investigation ◽  
Free Field ◽  
Three Dimensional ◽  
Head Orientation ◽  
Reflected Shock ◽  
Complex Wave ◽  
The Individual

Studies on blast neurotrauma have focused on investigating the effects of exposure to free-field blast representing the simplest form of blast threat scenario without considering any reflecting surfaces. However, in reality personnel are often located within enclosures or nearby reflecting walls causing a complex blast environment, that is, involving shock reflections and/or compound waves from different directions. In fact, when a blast wave interacts with nearby structures, reflected shock waves are generated and complex three-dimensional shock waves are formed. Complex shock wave overpressure-time traces are significantly different from free-field profiles because reflections can cause super-positioning of shock waves resulting in increased pressure magnitudes and multiple pressure peaks. Very importantly, the shocks arrive from different directions which would invoke a different biomechanical response than a one-dimensional exposure. It has been reported that in complex wave environments, the extent of the injuries becomes a function of the location related to the surrounding structures rather than a function of the distance from the center of the explosion, as it is for free-field conditions (Yelverton et al. 1993; Mayorga 1997; Stuhmiller 1997). Furthermore, the resulting injuries when the individual is in confined spaces are noted to be more severe (Yelverton et al. 1993; Leibovici et al. 1996). The purpose of this study was to design a complex wave testing system and perform a preliminary investigation of the intracranial pressure (ICP) response of rats exposed to a complex blast wave environment. Furthermore, we explored the effects of head orientation in the same environment.

On the effectiveness of ventilation to mitigate the damage of spherical membrane vessels subjected to internal detonations

2020 ◽  
Vol 11 (3) ◽  
pp. 319-339
Author(s):  
Francisco Hernandez ◽  
Xihong Zhang ◽  
Hong Hao
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
High Frequency ◽  
Arrival Time ◽  
Time Lag ◽  
Reflected Shock Wave ◽  
High Explosives ◽  
Element Analysis ◽  
Blast Overpressure ◽  
Reflected Shock

This article conducts a comparative study on the effectiveness of ventilation to mitigate blasting effects on spherical chambers subjected to internal detonations of high explosives through finite element analysis using the software package AUTODYN. Numerical simulations show that ventilation is ineffective in mitigating the damage of spherical chambers subjected to internal high explosives explosions because the chamber response is mainly described by high-frequency membrane modes. Openings do not reduce the chamber response despite they can reduce the blast overpressure after the chamber reaches its peak response. Worse still, openings lead to stress concentration, which weakens the structure. Therefore, small openings may reduce the capacity of the chamber to resist internal explosions. In addition, because large shock waves impose the chamber to respond to a reverberation frequency associated with the re-reflected shock wave pulses, secondary re-reflected shock waves can govern the chamber response, and plastic/elastic resonance can occur to the chamber. Simulations show that the time lag between the first and the second shock wave ranges from 3 to 7 times the arrival time of the first shock wave, implying that the current simplified design approach should be revised. The response of chambers subjected to eccentric detonations is also studied. Results show that due to asymmetric explosions, other membrane modes may govern the chamber response and causes localized damage, implying that ventilation is also ineffective to mitigate the damage of spherical chambers subjected to eccentric detonations.

scholarly journals Anthropomorphic Blast Test Device for Primary Blast Injury Risk Assessment

2020 ◽  
Vol 185 (Supplement_1) ◽  
pp. 227-233
Author(s):  
Yun Hsu ◽  
Kevin Ho ◽  
Philemon Chan
Keyword(s):  
Risk Assessment ◽  
Lung Injury ◽  
Open Field ◽  
Injury Risk ◽  
Health Hazard ◽  
Field Tests ◽  
Blast Injury ◽  
Test Device ◽  
Blast Overpressure ◽  
Lung Injuries

Abstract Introduction Blast overpressure health hazard assessment is required prior to fielding of weapon systems that produce blast overpressures that pose risk of auditory and nonauditory blast lung injuries. The anthropomorphic blast test device (ABTD) offers a single device solution for collection of both auditory and nonauditory data from a single blast at anthropometrically correct locations for injury risk assessment. It also allows for better replication of personnel positioning during weapons firings. The ABTD is an update of the blast test device (BTD), the current Army standard for collection of thoracic blast loading data. Validation testing of the ABTD is required to ensure that lung injury model validated using BTD collected test data and sheep subjects is still applicable when the ABTD is used. Methods Open field validation blast tests were conducted with BTD and ABTD placed at matching locations. Tests at seven blast strength levels were completed spanning the range of overpressures for occupational testing. Results The two devices produced very similar values for lung injury dose over all blast levels and orientations. Conclusion The ABTD was validated successfully for open field tests. For occupational blast injury assessments, ABTD can be used in place of the BTD and provide enhanced capabilities.

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