Mounted Combat System Crew Shock Loading: Head and Neck Injury Potential Evaluation

Report No. ARL-TR-4170
Authors: Michael E. LaFiandra and Harry Zywiol
Date/Pages: July 2007; 50 pages
Abstract: The Future Combat System Mounted Combat System (MCS) is an assault vehicle that will employ a 120-mm weapon. The goal of this project was to quantify the effects of weapon fire recoil on a surrogate human occupant of the MCS. In March and April 2004, the U.S. Army Tank-Automotive Research, Development, and Engineering Center (TARDEC) ride motion simulator (RMS) was used to simulate the effects of gun firing shock on a Hybrid III instrumented anthropometric test device capable of measuring neck force and torque and head acceleration. The RMS was used to simulate the dynamic motion of two MCS crew positions during weapon firing scenarios: the driver and the gunner. Firing scenarios ranged in azimuth from 0 to 180 degrees and in elevation from -10 to 30 degrees. The raw data for this project were collected by the Motion Base Technologies Team of TARDEC and their contractors. The data were sent to the U.S. Army Research Laboratory's (ARL's) Human Research Engineering Directorate for analysis. Biomechanics researchers at ARL were tasked with relating the neck force and torque and head accelerations to establish injury criteria for the neck and head. Data from the Hybrid III manikin were compared to the standards established by the National Highway Traffic Safety Administration (NHTSA). Based on the standards used by NHTSA, the acceleration of the head and the forces and torques experienced by the driver's and gunner's necks during weapon firing are less than the injury criteria for the 50th percentile male. Resulting injury rates were nearly zero for head injuries but were as high as 0.13 (13%) for moderate neck injuries and as high as 0.023 (2.3%) for critical neck injuries. It is important to note that the injury criteria being applied are based on single impulse events, such as a vehicle hitting a tree, and are not necessarily appropriate for multiple impulse events such as repeated weapon firing, which is a major limitation of this study. Because of this and the fact that there may be a cumulative effect of repeated impulses on the probability of injury, the injury probabilities reported may be artificially low. At the time this report was written, a standard for multiple events had not been established.
Distribution: Approved for public release
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Last Update / Reviewed: July 1, 2007