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Biofidelity of dummy legs for use in legislative car crash testing
Published June 07, 2000 by Institution of Mechanical Engineers in United Kingdom
Lower leg injuries are a common and potentially disabling injury experienced by car front seat occupants in frontal impacts. It is clearly important to be able to detect and quantify the risk of these injuries using anthropometric dummies in vehicle impact testing. The need for a more biofidelic lower leg and the development of well founded injury criteria has been identified. However, at present, there are insufficient dynamic biomechanical data available to aid the design and construction of advanced dummy legs, or to define injury risk criteria.
This paper reports a biofidelity study, comprising a series of dynamic low energy impact tests with post mortem human surrogate (PMHS) legs and volunteers both braced and unbraced. Comparative tests were performed on three existing dummy legs: the Hybrid III; the General Motors Corporation (GM/FTSS) foot and ankle attached to the Hybrid III lower leg; and the prototype Thor-Lx, a new lower leg recently developed by the National Highway and Traffic Safety Agency (NHTSA) in the USA.
Tests using a method of generating an Achilles force in PMHS specimens have enabled further biofidelic comparisons of the dummies with the human lower limb. The difficulties inherent in the interpretation of PMHS dynamic testing are discussed. The three dummy types have been evaluated against tests on PMHS subjects and human volunteers. The data presented shows the more accurate results, for both axial loading during impact, and kinematic response is seen with the advanced dummy legs (Thor-Lx and the GM/FTSS foot and ankle). The newly designed Thor-Lx has been shown to be much more biofidelic. This, in addition to the increased instrumentation in this prototype, makes it a useful research tool in the quest to help reduce the incidence of severely disabling injuries in frontal impacts.