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Blast Testing Issues and TBI: Experimental Models That Lead to Wrong Conclusions.

Needham CE, Ritzel D, Rule GT, Wiri S, Young L - Front Neurol (2015)

Bottom Line: This basic understanding must include the differences and interrelationships of static pressure, dynamic pressure, reflected pressure, and total or stagnation pressure in transient shockwave flows, how they relate to loading of objects, and how they are properly measured.This paper provides guidance regarding proper experimental methods and offers insights into the implications of improperly designed and executed tests.Through application of computational methods, useful data can be extracted from well-documented historical tests, and future work can be conducted in a way to maximize the effectiveness and use of valuable biological test data.

View Article: PubMed Central - PubMed

Affiliation: Southwest Division, Applied Research Associates, Inc. , Albuquerque, NM , USA.

ABSTRACT
Over the past several years, we have noticed an increase in the number of blast injury studies published in peer-reviewed biomedical journals that have utilized improperly conceived experiments. Data from these studies will lead to false conclusions and more confusion than advancement in the understanding of blast injury, particularly blast neurotrauma. Computational methods to properly characterize the blast environment have been available for decades. These methods, combined with a basic understanding of blast wave phenomena, enable researchers to extract useful information from well-documented experiments. This basic understanding must include the differences and interrelationships of static pressure, dynamic pressure, reflected pressure, and total or stagnation pressure in transient shockwave flows, how they relate to loading of objects, and how they are properly measured. However, it is critical that the research community effectively overcomes the confusion that has been compounded by a misunderstanding of the differences between the loading produced by a free field explosive blast and loading produced by a conventional shock tube. The principles of blast scaling have been well established for decades and when properly applied will do much to repair these problems. This paper provides guidance regarding proper experimental methods and offers insights into the implications of improperly designed and executed tests. Through application of computational methods, useful data can be extracted from well-documented historical tests, and future work can be conducted in a way to maximize the effectiveness and use of valuable biological test data.

No MeSH data available.


Related in: MedlinePlus

Dynamic pressure impulse as a function of distance from the tube exit and lateral distance from the center line.
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Figure 5: Dynamic pressure impulse as a function of distance from the tube exit and lateral distance from the center line.

Mentions: Because there is a sudden expansion of the shock at the end of the shock tube, rarefaction waves move into the flow from the edge of the tube. This introduces significant non-uniformities to the flow and reduces the useful area in which experiments can be made. To show the variation of the dynamic pressure impulse as a function of position in the exit jet, we include Figure 5. The peak dynamic impulse as a function of distance from the tube exit and the lateral distance across the tube is shown. The peak overpressure measured on the center line at 1.5 tube diameters from the exit is about 70 kPa. The plot covers only the central half of the 20 m diameter of the tube; variations beyond half the radius of the tube (from the center line) are too great to be used in any experiment. Large gradients in the flow are caused by expansion waves initiated at the edge of the end of the tube. These results are characteristic of any shock tube. Therefore, exit jets from shock tubes cannot be used to generate blast waves simulating free field detonations.


Blast Testing Issues and TBI: Experimental Models That Lead to Wrong Conclusions.

Needham CE, Ritzel D, Rule GT, Wiri S, Young L - Front Neurol (2015)

Dynamic pressure impulse as a function of distance from the tube exit and lateral distance from the center line.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4389725&req=5

Figure 5: Dynamic pressure impulse as a function of distance from the tube exit and lateral distance from the center line.
Mentions: Because there is a sudden expansion of the shock at the end of the shock tube, rarefaction waves move into the flow from the edge of the tube. This introduces significant non-uniformities to the flow and reduces the useful area in which experiments can be made. To show the variation of the dynamic pressure impulse as a function of position in the exit jet, we include Figure 5. The peak dynamic impulse as a function of distance from the tube exit and the lateral distance across the tube is shown. The peak overpressure measured on the center line at 1.5 tube diameters from the exit is about 70 kPa. The plot covers only the central half of the 20 m diameter of the tube; variations beyond half the radius of the tube (from the center line) are too great to be used in any experiment. Large gradients in the flow are caused by expansion waves initiated at the edge of the end of the tube. These results are characteristic of any shock tube. Therefore, exit jets from shock tubes cannot be used to generate blast waves simulating free field detonations.

Bottom Line: This basic understanding must include the differences and interrelationships of static pressure, dynamic pressure, reflected pressure, and total or stagnation pressure in transient shockwave flows, how they relate to loading of objects, and how they are properly measured.This paper provides guidance regarding proper experimental methods and offers insights into the implications of improperly designed and executed tests.Through application of computational methods, useful data can be extracted from well-documented historical tests, and future work can be conducted in a way to maximize the effectiveness and use of valuable biological test data.

View Article: PubMed Central - PubMed

Affiliation: Southwest Division, Applied Research Associates, Inc. , Albuquerque, NM , USA.

ABSTRACT
Over the past several years, we have noticed an increase in the number of blast injury studies published in peer-reviewed biomedical journals that have utilized improperly conceived experiments. Data from these studies will lead to false conclusions and more confusion than advancement in the understanding of blast injury, particularly blast neurotrauma. Computational methods to properly characterize the blast environment have been available for decades. These methods, combined with a basic understanding of blast wave phenomena, enable researchers to extract useful information from well-documented experiments. This basic understanding must include the differences and interrelationships of static pressure, dynamic pressure, reflected pressure, and total or stagnation pressure in transient shockwave flows, how they relate to loading of objects, and how they are properly measured. However, it is critical that the research community effectively overcomes the confusion that has been compounded by a misunderstanding of the differences between the loading produced by a free field explosive blast and loading produced by a conventional shock tube. The principles of blast scaling have been well established for decades and when properly applied will do much to repair these problems. This paper provides guidance regarding proper experimental methods and offers insights into the implications of improperly designed and executed tests. Through application of computational methods, useful data can be extracted from well-documented historical tests, and future work can be conducted in a way to maximize the effectiveness and use of valuable biological test data.

No MeSH data available.


Related in: MedlinePlus