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Figure 6. Head rebound velocity vs Impact phase HIC. two exceptional cases. It was observed that there was higher deformation of the compartment in these two cases. The deformation is shown in Figure 7. The deformation occurred at the door aperture as high- lighted in the circle. Both vehicles with the compart- ment deformation recorded high head _ velocity compared to the vehicles without compartment

Figure 6 Head rebound velocity vs Impact phase HIC. two exceptional cases. It was observed that there was higher deformation of the compartment in these two cases. The deformation is shown in Figure 7. The deformation occurred at the door aperture as high- lighted in the circle. Both vehicles with the compart- ment deformation recorded high head _ velocity compared to the vehicles without compartment

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Figure 1. Head movement during the rebound phase: Hitting window glass (a) Head starts to rebound (b) Head rebounds rearward. During the rebound phase, the vehicle will rotate to the side, causing occupant’s head move toward the window door glass. There is a possibility of the head hitting the window glass that can lead to head injury to the occupant. The window glass is made from tem- pered glass and hard to break when hit by the head. At an impact velocity from 6 m/s to 9 m/s against empered glass windows, HIC values can stand over a imit of 1000 [6]. However, this impact cannot be cap- tured during offset collision test because the window glass winds down for the high speed camera recording purpose. During the rebound phase, the driver head moves toward window glass because of the lateral rotation of the vehicle. The video analysis in Figure 1 showed that the heads moved out of the window while the vehicle rotated. The head hit the window glass if it was not wound down. As seen from the images, it can be clearly seen the head was already at the outside of the window. On the other hand, during the rebound phase, the head hit the B inside the window frame at
Figure 1. Head movement during the rebound phase: Hitting window glass (a) Head starts to rebound (b) Head rebounds rearward. During the rebound phase, the vehicle will rotate to the side, causing occupant’s head move toward the window door glass. There is a possibility of the head hitting the window glass that can lead to head injury to the occupant. The window glass is made from tem- pered glass and hard to break when hit by the head. At an impact velocity from 6 m/s to 9 m/s against empered glass windows, HIC values can stand over a imit of 1000 [6]. However, this impact cannot be cap- tured during offset collision test because the window glass winds down for the high speed camera recording purpose. During the rebound phase, the driver head moves toward window glass because of the lateral rotation of the vehicle. The video analysis in Figure 1 showed that the heads moved out of the window while the vehicle rotated. The head hit the window glass if it was not wound down. As seen from the images, it can be clearly seen the head was already at the outside of the window. On the other hand, during the rebound phase, the head hit the B inside the window frame at
Figure 2. Head resultant acceleration.
Figure 2. Head resultant acceleration.
Figure 3. (a) Start of impact at t=Oms, (b) Head starting to rebound at t=141ms, (c) Before head hitting B-pil- lar t= 240 ms.
Figure 3. (a) Start of impact at t=Oms, (b) Head starting to rebound at t=141ms, (c) Before head hitting B-pil- lar t= 240 ms.
Figure 4. Head acceleration graph in X-direction. the Figure 3. Graph in Figure 4 shows example of head acceleration in X-direction. The peak at 141 ms represents the start of head rebound phase, which matched the analysis from the high speed video. The time before the head hitting B-pillar can be seen in the graph just before the second peak started. It also agrees with the analysis from the high speed video. Velocity in X-direction was acquired through integration from the head acceler- ation curve in X-direction.
Figure 4. Head acceleration graph in X-direction. the Figure 3. Graph in Figure 4 shows example of head acceleration in X-direction. The peak at 141 ms represents the start of head rebound phase, which matched the analysis from the high speed video. The time before the head hitting B-pillar can be seen in the graph just before the second peak started. It also agrees with the analysis from the high speed video. Velocity in X-direction was acquired through integration from the head acceler- ation curve in X-direction.
Figure 5. Velocity graph in X, Y, Z—direction. Results
Figure 5. Velocity graph in X, Y, Z—direction. Results
Table 1. Test mass of ASEAN NCAP vehicles. Table 2. Head kinematic analysis. The relationship between HIC during impact and the resultant head velocity was observed and established. HIC was chosen as a parameter because it represents the total vehicle restraint system performance includ- ing airbag, seatbelt, seat and other safety equipment. HIC was calculated based on the head resultant during impact phase. The relation between HIC and resultant head velocity is shown in Figure 6. The graph includes
Table 1. Test mass of ASEAN NCAP vehicles. Table 2. Head kinematic analysis. The relationship between HIC during impact and the resultant head velocity was observed and established. HIC was chosen as a parameter because it represents the total vehicle restraint system performance includ- ing airbag, seatbelt, seat and other safety equipment. HIC was calculated based on the head resultant during impact phase. The relation between HIC and resultant head velocity is shown in Figure 6. The graph includes
Figure 7. Compartment deform after crash test.
Figure 7. Compartment deform after crash test.
Figure 8. Head rebound velocity vs HIC during impact phase. deformation. These cases were removed from the graph because of the different character between the deformed compartment and undeformed compart- ment. These two cases were dropped from the analysis because the behaviours of their compartments were different from those in the other vehicles. The com- partment of the other vehicles remained intact and did not deform as these two vehicles. After removing these two data from the graph, the relationship between head rebound velocity and HIC during impact test became linear (Figure 8), giving the following formula:
Figure 8. Head rebound velocity vs HIC during impact phase. deformation. These cases were removed from the graph because of the different character between the deformed compartment and undeformed compart- ment. These two cases were dropped from the analysis because the behaviours of their compartments were different from those in the other vehicles. The com- partment of the other vehicles remained intact and did not deform as these two vehicles. After removing these two data from the graph, the relationship between head rebound velocity and HIC during impact test became linear (Figure 8), giving the following formula:
Figure 9. (a) With airbag and (b) Without airbag.
Figure 9. (a) With airbag and (b) Without airbag.
Table 3. Head kinematic comparison between vehicle with airbag and vehicle with- out airbag.
Table 3. Head kinematic comparison between vehicle with airbag and vehicle with- out airbag.
Figure 10. Crash pulse comparison for the vehicle with airbag and without airbag. The design of vehicle structure has evolved in order to meet the requirements of frontal impact tests. To achieve good performance in the offset test, it is necessary to minimise intrusion into the occupant compartment by absorbing the crash energy in the crush zone forward of the compartment. If a vehicle’s occupant compartment is weaker than the front crush zone, the occupant compartment will be compro- mised before full use of the available energy absorp- tion capacity of the front crush zone is deployed. In this case, front-end stiffness needs to be reduced while the occupant compartment stiffness needs to be increased. It is imperative to design vehicles with suf- ficient energy-absorption capacity in the crush zone and with an occupant compartment that can resist the forces of front-end crush without yielding [15].
Figure 10. Crash pulse comparison for the vehicle with airbag and without airbag. The design of vehicle structure has evolved in order to meet the requirements of frontal impact tests. To achieve good performance in the offset test, it is necessary to minimise intrusion into the occupant compartment by absorbing the crash energy in the crush zone forward of the compartment. If a vehicle’s occupant compartment is weaker than the front crush zone, the occupant compartment will be compro- mised before full use of the available energy absorp- tion capacity of the front crush zone is deployed. In this case, front-end stiffness needs to be reduced while the occupant compartment stiffness needs to be increased. It is imperative to design vehicles with suf- ficient energy-absorption capacity in the crush zone and with an occupant compartment that can resist the forces of front-end crush without yielding [15].
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Civil EngineeringMedicineCrash Test
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