Biomechanical Response of the Human Pelvis: A High-Rate Vertical Loading Pilot Study

The proliferation of improvised explosive devices (IEDs) in recent military conflicts have caused injuries which present new challenges to the biomechanics community. Vehicle-mounted U.S. and coalition warfighters are being exposed to extreme loading conditions from under-body blasts (UBB), and are suffering devastating injuries. One region of the body that is injured in these UBB events is the pelvis. For UBB events, the primary load vector is applied verticaly through the seat, thus loading the pelvis in a direction and at a rate never before researched. This study aims to quantify the mechanical response of the component pelvis from a high-rate vertical load, so as to improve understanding of the pelvic response and to provide data for anthropomorphic test device (ATD) development.

In ten post-mortem human surrogate (PMHS) pelves, the superior surface of the sacrum was rigidly secured to a 6-axis load cell, which was then rigidly mounted to an effective mass, equivalent to that of a 50th percentile male torso. This assembly was resting against a seat platen, which was impacted by a linear impactor, providing a single high-rate loading condition into the specimen. Accelerometers were used to quantify the boundary conditions. Additionally, accelerometers, an angular rate sensor, and strain gauges were used to capture the response of the pelvis.

The average input seat velocity for this study was 5.9 ± 0.3 m/s with a time to peak of 6.6 ± 0.2 ms. This input condtion yielded a calculated axial stiffness of 995 ± 159 kN/m before there was a failure at the rigid potting boundary. The average failure time was 4 ± 0.6 ms, and the peak axial force was -6 ± 1.8 kN. The primary rotation was positive about the y-axis, and the moment at time of failure was 311± 16 Nm.

This study offers detailed biomechanical response data of the component pelvis from a single high-rate impulse, including force and moment response corridors, as well as strain response and sacrum acceleration . This data is necessary for the development of a biofidelic pelvis for UBB applications, both for finite element analysis, and ATD development

Year	Entry
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2013	Bailey AM, Christopher JJ, Henderson K, Brozoski F, Salzar RS. Comparison of Hybrid‐III and PMHS response to simulated underbody blast loading conditions. In: Proceedings of the 2013 International IRCOBI Conference on the Biomechanics of Injury. September 11-13, 2013; Gothenburg, Sweden.158-170.
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Year

Entry

2001

Wang J, Bird R, Swinton B, Krstic A. Protection of lower limbs against floor impact in army vehicles experiencing landmine explosion. J Battlefield Technol. 2001;4(3):8-12.

2013

Bailey AM, Christopher JJ, Henderson K, Brozoski F, Salzar RS. Comparison of Hybrid‐III and PMHS response to simulated underbody blast loading conditions. In: Proceedings of the 2013 International IRCOBI Conference on the Biomechanics of Injury. September 11-13, 2013; Gothenburg, Sweden.158-170.

1995

Schueler F, Mattern R, Zeidler F, Scheunert D. Injuries of the lower legs - foot, ankle joint, tibia; mechanisms, tolerance limits, injury-criteria evaluation of a recent biomechanic experiment-series (impact-tests with a pneumatic-biomechanic-impactor). In: Proceedings of the 1995 International IRCOBI Conference on the Biomechanics of Impact. September 13-15, 1995; Brunnen, Switzerland.33-45.

1998

Crandall JR, Kuppa SM, Klopp GS, Hall GW, Pilkey WD, Hurwitz SR. Injury mechanisms and criteria for the human foot and ankle under axial impacts to the foot. Int J Crashworthiness. 1998;3(2):147-162.

1998

Bouquet R, Ramet M, Bermond F, Caire Y, Talantikite Y, Robin S, Voiglio E. Pelvis human response to lateral impact. In: Proceedings of the 16th International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 31–June 4, 1998; Windsor, Ontario, Canada.1665-1686.