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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

Calculated (red) and measured (blue) overpressure impulse as a function of angle (12).
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Figure 10: Calculated (red) and measured (blue) overpressure impulse as a function of angle (12).

Mentions: However, the peak overpressure indicates only a part of the blast load. Figure 10 compares the measured and calculated overpressure impulse at the same positions around the head. It is the impulse that determines the momentum transfer to the test subject. The comparison illustrates the potential difference in overpressure impulse loading between free field blast and a shock tube. Note that the calculated peak overpressure is in good agreement with the experimental data in Figure 9, but the impulses differ significantly due to the differences in the source loading. Also note that the impulse does not correlate with the peak overpressure in either the test data or the simulation. These differences are a result of the blockage in the shock tube, which will have a small effect on the peak overpressure, but can cause significant decreases in the dynamic loads to the sides and back of test objects as previously discussed, resulting in skewed dynamic pressure impulse exposures.


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)

Calculated (red) and measured (blue) overpressure impulse as a function of angle (12).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 10: Calculated (red) and measured (blue) overpressure impulse as a function of angle (12).
Mentions: However, the peak overpressure indicates only a part of the blast load. Figure 10 compares the measured and calculated overpressure impulse at the same positions around the head. It is the impulse that determines the momentum transfer to the test subject. The comparison illustrates the potential difference in overpressure impulse loading between free field blast and a shock tube. Note that the calculated peak overpressure is in good agreement with the experimental data in Figure 9, but the impulses differ significantly due to the differences in the source loading. Also note that the impulse does not correlate with the peak overpressure in either the test data or the simulation. These differences are a result of the blockage in the shock tube, which will have a small effect on the peak overpressure, but can cause significant decreases in the dynamic loads to the sides and back of test objects as previously discussed, resulting in skewed dynamic pressure impulse exposures.

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