Arc far Side Impact Collaborative Research Program – Task 5b: Test Procedures Crash Tests and Sled Tests for the Far-side Environment

5.5Conclusions

Side-impact dummies, designed primarily to test for occupant injuries on the near-side are limited in their ability to emulate occupant kinematics for a far-side impact. Also a Hybrid III test device, designed primarily for frontal impacts, is limited in its ability to test for far-side impacts. Based on historical crash data, the leading cause of injury in side-impacts on the far-side is head strikes with the opposite side hard vehicle surfaces. The occupant kinematics that led to this result were reproduced with a post mortem human subject (PMHS). The cadaver, seated in the vehicle, moved out of its seat and contacted the far-side B-pillar when its vehicle was impacted on the far-side.

Computer simulations offer an easy way to test additional dummies and circumstances. Five anthropomorphic test devices (ATDs) were simulated in MADYMO for far-side impacts and all reacted similarly to the three dummies tested previously as would be expected, and failed to produce desired kinematics.

Despite the short-comings of the dummies for reproducing far-side kinematics, the reaction of these dummies in MADYMO to certain countermeasures offers some insight into future studies. A reverse 3-point seatbelt effectively restrained the occupant, however, significantly increased neck force levels, almost crossing injury threshold levels. Chest and shoulder airbags on the inside of the occupant contained the occupant and prevented excursion. However, left the head and neck unrestrained and showed awkward movement of the head. In addition, the use of a petite dummy exposed some vulnerability of odd sized occupants to airbags.

The human faceted MADYMO model did show promise by properly reproducing occupant kinematics. Future simulations and experimentation are necessary to determine whether such a model could appropriately predict occupant injury and kinematics for far-side impacts. In addition, a modified BioSID dummy tested by Bostrom properly contacted the far-side B-pillar and could be modeled for suitability.

5.6References

Bostrom, O., Haland, Y., (2004) Benefits of a 3+2 Point Belt System and an Inboard Torso Side Support in Frontal, Far-Side, and Rollover Crashes.

Cavanaugh, J.M., Zhu, Y., Huang, Y., King, A.I. (1993) Injury and Response of the Thorax in Side Impact Cadaveric Tests. SAE Paper 933127.

Fildes, B.N., Sparke, L.J., Bostrom, O., Pintar, F., Yoganandan, N., Morris, A.P. (2002) Suitability of Current Side Impact Test Dummies in Far-Side Impacts. IRCOBI Conference. September 2002.

Maltese, M.R., Eppinger, R.H., Rhule, H., Donnelly, B., Pintar, F.A., Yoganandan, N. (2002) Response Corridors of Human Surrogates in Lateral Impacts. Stapp Car Crash Journal, Vol. 46, Society of Automotive Engineers, Warrendale, PA.

Yoganandan, N., Pintar, F.A., Gennarelli, T.A., Maltese, M.R., Eppinger, R.H. (2002) Biofidelity Evaluation of Recent Side Impact Dummies. IRCOBI Conference. September 2002.

6Sled Test Configurations for the Far-Side Crash Environment

6.1Introduction

This research applies finite element modelling and occupant modelling to determine the sled test conditions required to simulate crash environments that produce significant numbers of AIS 3+ injuries to far-side occupants. Of particular interest are angular crashes and crashes that produce vehicle rotation that could influence occupant kinematics. The SNCAP test was included in the study because the striking barrier’s direction of travel is 63 degrees relative to the centerline of the struck vehicle.

The following crash modes were modelled in this study:

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  SNCAP Crash Test
  
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  Y Damage Crash Test
  
• 
  40% Overlap 30° Corner Impact Crash Test
  

6.2Background

The crash environment that produces injuries in far-side impacts has been studied by others [Gabler 2005, Digges 2001]. A large number of crashes that produce serious injuries occur in configurations that produce rotation of the impacted vehicle. To date, the countermeasures being evaluated in sled tests that do not consider the complications created by vehicle rotation [Bostrom 2003]. A requirement exists for appropriate sled test configurations to permit the economical development of effective far-side countermeasures. Initial considerations of the sled test requirements for crashes with rotation have been published by Smyth [2007]. The present study is based on a thesis for a Master’s degree at the George Washington University [Cuadrado, 2008]. The thesis contains additional simulations based on finite element models of vehicle-to-vehicle crashes and in-depth evaluations of the requirements for a sled crash pulse.

The change in velocity, or delta-V, is a metric frequently used by researchers and experts to define crash severity and determine injury causation [Palmer 2006]. Numerous studies have analysed the relationships between the vehicle delta-V, occupant delta-V, and occupant injury [Marine 1998, Buhdorf 1996, Roberts 1993]. For cases with negligible vehicle rotation, the occupant delta-V is similar to that of the vehicle [Cheng 1989]. However, the delta-V must be calculated for every position within the vehicle if it rotates to account for the change in angular velocity and angular displacement [Fay 1996]. Taking the rotational component into consideration means that the total delta-V for occupants on one side of the vehicle will be reduced while increasing the total delta-V for occupants on the other side of the vehicle [Fay 1996]. This fact is pertinent in understanding the differences in the crash environment between near and far-side occupants.

Another important consideration is that near-side occupants contact the inside of the vehicle within 50 ms of the initial impact while far-side occupants can strike the interior as late as 180 ms after impact [Solinski 1997]. This is particularly significant in side collisions. Near-side passengers are commonly struck by the intruding interior while far-side occupants have sufficient interior space to permit more of the crash energy to be absorbed by restraint systems before contact with the vehicle interior occurs. In addition, the longer “ride down” time for far-side occupants permits more time for a rotating vehicle to move relative to the occupant. Consequently, the influence of the vehicle’s motion and intrusion will be different for far-side occupants.

Automotive manufacturers would be encouraged to develop countermeasures for occupants seated on the non-stuck side of a vehicle if there were sled test procedures to evaluate the safety performance. To date there have been very few crash tests with dummies on the far-side of the crash. The primary purpose of this study is to develop sled tests that mimics the far-side crash environment. The tests selected for this study include the SNCAP test and tests of vehicles that undergo significant yaw during the event. A successful duplication of occupant motion in far-side crashes will prove that a sled test is an effective, cost-efficient means of testing and developing safety countermeasures for far-side occupants.