Limits...
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

Comparison of overpressure waveforms measured on a helmeted head (12).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4389725&req=5

Figure 8: Comparison of overpressure waveforms measured on a helmeted head (12).

Mentions: To demonstrate the effect of this angular dependency, we include Figure 8, which compares the overpressure waveforms at several positions around a helmeted head in a conical expansion shock tube (12). The peak measured overpressure is greater at the 30° angle than it is at the head on position. The peak overpressure load then decreases rapidly as the shock engulfs the head. The positive duration of the load is nearly 2.5 ms. To calculate the acceleration of the head, the assumption is that the load is vertically uniform, and that each gauge record represents some fraction of the exposed surface area. The impulsive load is calculated by integrating the overpressure waveforms over the positive duration. However, without a clear understanding of the mechanics of injury, the validity of these assumptions cannot be ascertained.


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)

Comparison of overpressure waveforms measured on a helmeted head (12).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: Comparison of overpressure waveforms measured on a helmeted head (12).
Mentions: To demonstrate the effect of this angular dependency, we include Figure 8, which compares the overpressure waveforms at several positions around a helmeted head in a conical expansion shock tube (12). The peak measured overpressure is greater at the 30° angle than it is at the head on position. The peak overpressure load then decreases rapidly as the shock engulfs the head. The positive duration of the load is nearly 2.5 ms. To calculate the acceleration of the head, the assumption is that the load is vertically uniform, and that each gauge record represents some fraction of the exposed surface area. The impulsive load is calculated by integrating the overpressure waveforms over the positive duration. However, without a clear understanding of the mechanics of injury, the validity of these assumptions cannot be ascertained.

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