• Seat Safety

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Evaluation test of the seat safety

Evaluation test of the seat safety image
Evaluation of the seat safety is to provide the related information after estimating functions of the seat and the head restraint to prevent the neck whiplash of riders in case of the rear collision, and also is to induce the supply and the spread of safe vehicles with encouraging manufacturer to develop the excellent seat on the safety


Test method

Conditions of seat fixed and dummy types for the evaluation of the seat safely image
1. Test seat : Vehicle 1 raw driver and passenger sides
2. Test equipment : Dummy for the rear collision (BioRID II)
3. Test method : Collision to the single status seat after fixed it on the temporary collision test equipment with
    the speed of rear-side 16km/h.
4. Whiplash Assessment Criteria
    : With the rear collision, estimating the evaluation level with measuring 7 criteria related to the neck injury

  • Head Restraint Contact time : It is the time that the head of dummy contact to the head stand in case of the rear collision.
  • T1 X - Acceleration : The accelerating speed of the first joint on the backbone
  • Upper Neck Shear Force (FX)
  • Upper Neck Tension (FZ)
  • Head rebounding velocity : It is the speed to rebound by the repulsive power after the head of dummy collided to the head stand in case of the rear collision.
  • NIC : Combining value between the relative speed of T1 that is located between the head and the first joint on the backbone and the relative accelerating speed.
  • Combining values between the tension applied to upper neck of dummy and the moment
5. Calculation of evaluation level
  • Categorized to 5 levels based on total point 10 with adding max 1.5 point into evaluating item of the whiplash.
  • Hereby the final level is calculated by which the point of head stand figures performed in the safety evaluation for head stands added or decrease to -1~+1 point. Indicating the point and the number of stars together.

Mechanism occurring the neck injury in case of the rear collision

  • In general the neck injury can be occurred at all three steps. It is the moment upto that the head collide to head stands, and is the step that the neck figure turns to the S shape by shear force and tension after neck bending symptom and the neck injury can happen. The second is the step occurring the neck injury while the head collide to head stands and keep moving to backward and finally it move to forward by the repulsive power. In the final third step, it is the step occurring head bending symptoms while the head move further to forward by the repulsive speed with restricted the upper body by the safety belt. Conclusively to evaluate the neck injury, we need NIC that can evaluate all three steps and need to execute the evaluation for this injury constant in the estimation of seat safety of KNCAP.

    Initial position of head moving backward after collidingneck bending outwardneck bending inward

Active type of head stands

  • By preventing that passenger head move backward and bend outward with operating automatically head stands in the rear collision, it is the device to decrease the neck injury of passengers when the rear collision is occurred. In case of the rear collision, there are the mechanical method that can smooth the head impact with moving head stands if the impact apply to the back of the seat and the electronic method of head stands operated by electrical sensor in the vehicle.

    Operation of active type head stands image