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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

Extracts from Goldstein showing the mounting canister for a specimen located near the shock-tube exit. Tracking of the nose of the specimen shows the head made a violent focal impact with the rim of the canister at Point “A,” then rebounded to its maximum extension at Point B before retracting back to the canister (9).
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Figure 6: Extracts from Goldstein showing the mounting canister for a specimen located near the shock-tube exit. Tracking of the nose of the specimen shows the head made a violent focal impact with the rim of the canister at Point “A,” then rebounded to its maximum extension at Point B before retracting back to the canister (9).

Mentions: The mounting of a specimen in shock-tube testing must be done with the same care applied for supersonic wind-tunnel research. Apart from the blockage aspect described earlier, anomalous loading of the specimen will be caused by local shock reflections and flow patterns developed around the support structure. There is also high potential for inflicting injury artifacts entirely due to the restraint system. For example, Goldstein (9) describes a cylindrical canister for mounting a rat specimen perpendicular to the shock tube flow as shown in Figure 6. Being located near the exit, the test location will be subjected to exaggerated dynamic pressure exacerbated by high-speed flow around the canister; anomalous pressure loading would be imparted to the body and head due to the canister. Perhaps most importantly, in that case, tracking of the head motion shows the head made a violent focal impact with the rim of the canister.


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)

Extracts from Goldstein showing the mounting canister for a specimen located near the shock-tube exit. Tracking of the nose of the specimen shows the head made a violent focal impact with the rim of the canister at Point “A,” then rebounded to its maximum extension at Point B before retracting back to the canister (9).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Extracts from Goldstein showing the mounting canister for a specimen located near the shock-tube exit. Tracking of the nose of the specimen shows the head made a violent focal impact with the rim of the canister at Point “A,” then rebounded to its maximum extension at Point B before retracting back to the canister (9).
Mentions: The mounting of a specimen in shock-tube testing must be done with the same care applied for supersonic wind-tunnel research. Apart from the blockage aspect described earlier, anomalous loading of the specimen will be caused by local shock reflections and flow patterns developed around the support structure. There is also high potential for inflicting injury artifacts entirely due to the restraint system. For example, Goldstein (9) describes a cylindrical canister for mounting a rat specimen perpendicular to the shock tube flow as shown in Figure 6. Being located near the exit, the test location will be subjected to exaggerated dynamic pressure exacerbated by high-speed flow around the canister; anomalous pressure loading would be imparted to the body and head due to the canister. Perhaps most importantly, in that case, tracking of the head motion shows the head made a violent focal impact with the rim of the canister.

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