Experimental and numerical investigation of comparability of whiplash sled test results

  • Mustafa Özdemir
  • Sıtkı Kemal İder
  • Mustafa İlhan Gökler
Technical Paper

Abstract

Whiplash-associated neck injuries represent an important health and socioeconomic problem attracting more and more attention of the vehicle safety community. Sled tests are conducted for the dynamic whiplash assessment of seats. However, reproducibility of the initial backset distances and of the sled pulses in every test plays an important role on the comparability of these results. In this study, in order to investigate these aspects, three different driver seat types are considered with three identical and unused samples for each of them, and by strictly following the European New Car Assessment Program (Euro NCAP) whiplash protocol and using the BioRID II dummy, totally nine sled tests are performed. The sled pulses are in general reproduced quite well for different vehicle seats in these tests. However, it is seen that there are differences of up to 5 mm in the initial backset distances recorded for the identical seats of the same type, while this difference increases up to 7 mm among the different seat types considered. Moreover, taking into account the associated tolerances allowed in this protocol, this uncertainty in the backset can even increase up to 10 mm. Based on the previous simulation results obtained by using the finite element model of the BioRID II dummy, linear regression models are constructed, and it is shown that a 10-mm increase in the backset will yield an increase of 2.25, 2.89 and 3.11 m2/s2 in the NICmax values for the low, medium and high severity Euro NCAP pulses, respectively. Being 38, 22 and 31 % of the differences between the associated Euro NCAP higher and lower performance limits, and 68, 96 and 124 % of the differences between the associated Euro NCAP lower performance and capping limits, such increases in the NICmax values are found to bring an unacceptably high uncertainty in the test results, and they can even easily lead to the application of capping, which means giving a zero score for the entire test. In light of these findings, several suggestions are recommended for a more solid whiplash dynamic assessment procedure.

Keywords

Whiplash Neck injury Rear crash Vehicle seat Vehicle safety 

List of symbols and abbreviations

Amean

Mean acceleration

aHead

Horizontal acceleration of the center of gravity of the head

aT1

Horizontal acceleration of the first thoracic vertebrae

b

Backset distance

CFC

Channel frequency class

CL

Capping limit

CMM

Coordinate measuring machine

dV

Velocity change

Euro NCAP

European New Car Assessment Program

Fx

Upper neck shear force

Fz

Upper neck tension force

HPL

Higher performance limit

HPM

H-Point Manikin

H-point

Hip point

HRMD

Head Restraint Measuring Device

IIWPG

International Insurance Whiplash Prevention Group

LPL

Lower performance limit

NICmax

Maximum value of the Neck Injury Criterion

RCAR

Research Council for Automobile Repairs

t

Time

T-HRCstart

Head restraint contact time

TTF

Time to fire

Vrebound

Head rebound velocity in the horizontal direction

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Copyright information

© The Brazilian Society of Mechanical Sciences and Engineering 2015

Authors and Affiliations

  • Mustafa Özdemir
    • 1
  • Sıtkı Kemal İder
    • 2
  • Mustafa İlhan Gökler
    • 3
    • 4
  1. 1.Department of Mechanical Engineering, Faculty of EngineeringMarmara UniversityIstanbulTurkey
  2. 2.Mechanical Engineering Department, Faculty of EngineeringÇankaya UniversityEtimesgutTurkey
  3. 3.Department of Mechanical Engineering, Faculty of EngineeringMiddle East Technical UniversityÇankayaTurkey
  4. 4.METU-BILTIR CenterMiddle East Technical UniversityÇankayaTurkey

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