This summarizes the various parameters involved for Occupant Protection such as airbag pressure and volume, seat-belt sensor timings and importance of knee air-bags.

1. O C C U P A N T
P R O T E C T I O N
D E S I G N
P A R A M E T E R S I N
S L E D T E S T I N G
P R O J E C T - 2
M A D E BY :
A K S H AY M I S T R I
1

2. CONTENTS
• Objectives
• Injury Criteria to observe
• Effects of individual parameters:
– Sensor Timing (Slide 5 - 7)
– Retractor Load Limiter (Slide 8 - 10)
– Airbag Mass-Flow rate (Slide 11 - 14)
– Sled Pulse (Slide 15 - 17)
• Final Model (18 – 21)
• Conclusion
Note: Underlined words contain link to go to their respective slides.
2

3. OBJECTIVES
• Test conditions: Belted 50% Hybrid III dummy in driver seat subjected to 35 mph
impact.
• Design parameters to observe:
– Sensor timing (-5 ms /+5 ms)
– Retractor Load Limiter: Seatbelt load (Scaling: 0.8/1.2)
– Airbag mass flow rate (Scaling: 0.8/1.2)
– Sled pulse (Scaling: 0.8/1.2)
3

4. INJURY CRITERIA TO OBSERVE
Criteria Threshold
Head Injury Criteria (HIC15) 700
Chest Displacement [mm] 63
Chest Acceleration [g] 60
Left Femur Load [kN] 10
Right Femur Load [kN] 10
4

5. EFFECT OF SENSOR TIMING
5
Injury Criteria Baseline (@13ms) Timing -5ms (@8ms) Timing +5ms (@18ms)
HIC15 722 655 784
Chest Acceleration [g] 109.3 122 132.8
Chest Deflection [mm] 58.44 59 58.3
Left Femur Load [kN] 29.5 27.1 32.6
Right Femur Load [kN] 31.3 29.5 34.2
• Green and Red colors show decrement and increment in the injury values respectively.
• Here, pretensioner sensor fire timings were varied.
• Early action of pretensioner reduces the dummy travel and hence HIC and femur loads are
reduced.
• However, due to early action chest deflection increases.
• Chest acceleration worsens in both cases.

6. 6
EFFECT OF SENSOR TIMING
0
20
40
60
80
100
120
140
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
Chest Acceleration -5 ms +5 ms
0
10.5
21
31.5
42
52.5
63
0 15 30 45 60 75 90 105 120 135 150
Deflection[mm]
Time [ms]
Chest Deflection -5 ms +5 ms
0
50
100
150
200
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
HIC 15 -5 ms +5 ms
-40
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Left Femur -5 ms +5 ms
-40
-20
0
20
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Right Femur -5 ms +5 ms

7. 7
EFFECT OF SENSOR TIMING
• Time -5ms (@8 ms) • Time +5ms (@18 ms)

8. EFFECT OF RETRACTOR LOAD LIMITER
8
Baseline - SF 1
(@3.25 kN)
Scale Factor - SF 0.9
(@2.93 kN)
Scale Factor - SF 1.2
(@3.9 kN)
HIC15 722 760 742
Chest Acceleration [g] 109.3 127.9 128.8
Chest Deflection [mm] 58.44 64.3 65.6
Left Femur Load [kN] 29.5 29.1 29.3
Right Femur Load [kN] 31.3 31.8 31.4
• Increasing and decreasing the retractor load limit, demotes the injury values.
• More dummy travel is the reason in case of increasing the load limit. (Late action of
retractor)
• When limit is decreased, retractor acts early but makes the belt stiff for the occupant
which increases the injury values.
• Femur loads almost don’t vary for both cases.

9. 9
EFFECT OF RETRACTOR LOAD LIMITER
0
20
40
60
80
100
120
140
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
Chest Acceleration SF : 0.9 SF : 1.2
0
10
20
30
40
50
60
70
0 15 30 45 60 75 90 105 120 135 150
Deflection[mm]
Time [ms]
Chest Deflection SF : 0.9 SF : 1.2
0
50
100
150
200
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
HIC 15 SF : 0.9 SF : 1.2
-40
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Left Femur SF : 0.9 SF : 1.2
-40
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Right Femur SF : 0.9 SF : 1.2

10. 10
EFFECT OF RETRACTOR LOAD LIMITER
• SF: 0.9 (2.9 kN) • SF: 1.2 (3.9 kN)

11. EFFECT OF AIRBAG MASS-FLOW RATE
• VSCA: Volume Scale Factor and PSCA: Pressure Scale Factor.
• Decreasing the volume factor increases the injury values, as the dummy travel increases.
Accelerations and chest deflections increase.
• Best results are found when VSCA is increased and PSCA is decreased. Increase in volume
reduces the dummy travel and decrease in pressure reduces the stiffness of the bag which
is a bit desirable.
• Worst case is observed when VSCA and PSCA both are increased, in this case the airbag
becomes the cause of injury to the occupant.
11
Baseline -
VSCA:1 PSCA:1
Timing - VSCA: 0.8
PSCA: 0.8
Timing - VSCA:
1.2 PSCA:1.2
Timing - VSCA:
0.8 PSCA:1.2
Timing - VSCA:
1.2 PSCA:0.8
HIC15 722 780 749 749 743
Chest Acceleration [g] 109.3 126 125.8 126.5 125.4
Chest Deflection [mm] 58.44 59.4 57 62.4 55
Left Femur Load [kN] 29.5 29.4 45.4 29.6 29.5
Right Femur Load [kN] 31.3 31.3 47.7 31.5 32

12. 12
EFFECT OF AIRBAG MASS-FLOW RATE
0
20
40
60
80
100
120
140
0 15 30 45 60 75 90 105 120 135 150
ChestAcceleration[g]
Time [ms]
Chest Acceleration VSCA, PSCA: 0.8 VSCA, PSCA: 1.2
0
10
20
30
40
50
60
70
0 15 30 45 60 75 90 105 120 135 150
ChestDeflection[mm]
Time [ms]
Chest Deflection VSCA, PSCA: 0.8 VSCA, PSCA: 1.2
0
50
100
150
200
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
HIC15 VSCA, PSCA: 0.8 VSCA, PSCA: 1.2
-50
-40
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Left Femur VSCA, PSCA: 0.8 VSCA, PSCA: 1.2
-60
-40
-20
0
20
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Right Femur VSCA, PSCA: 0.8 VSCA, PSCA: 1.2

13. 13
EFFECT OF AIRBAG MASS-FLOW RATE
0
20
40
60
80
100
120
140
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
Chest Acceleration VSCA: 1.2 PSCA:0.8 VSCA:0.8 PSCA:1.2
0
10
20
30
40
50
60
70
0 15 30 45 60 75 90 105 120 135 150
Deflection[mm]
Time [ms]
Chest Deflection VSCA:1.2 PSCA:0.8 VSCA:0.8 PSCA:1.2
0
50
100
150
200
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
HIC15 VSCA:1.2 PSCA:0.8 VSCA:0.8 PSCA:1.2
-40
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Left Femur VSCA:1.2 PSCA:0.8 VSCA:0.8 PSCA:1.2
-40
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Right Femur VSCA:1.2 PSCA:0.8 VSCA:0.8 PSCA:1.2

14. 14
EFFECT OF AIRBAG MASS-FLOW RATE
• VSCA:0.8 PSCA:0.8 • VSCA:1.2 PSCA:1.2
• VSCA:0.8 PSCA:1.2 • VSCA:1.2 PSCA:0.8

15. EFFECT OF SLED PULSE
15
Baseline - SF:1 Scale Factor - SF 0.9 Scale Factor - SF 1.2
HIC15 722 521 1103
Chest Acceleration [g] 109.3 111 147.8
Chest Deflection [mm] 58.44 58.14 58.4
Left Femur Load [kN] 29.5 25.8 35.4
Right Femur Load [kN] 31.3 29.6 35.7
• Decreasing the sled pulse, obviously, decreased the injury values.
• Injury values highly increased with the increase of sled pulse.

16. 16
0
20
40
60
80
100
120
140
160
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
Chest Acceleration SF: 0.9 SF: 1.2
EFFECT OF SLED PULSE
0
10
20
30
40
50
60
70
0 15 30 45 60 75 90 105 120 135 150
ChestDeflection[mm]
Time [ms]
Chest Deflection SF : 0.9 SF : 1.2
0
40
80
120
160
200
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
HIC15
SF : 0.9 SF: 1.2
-40
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Left Femur SF: 0.9 SF: 1.2
-40
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Right Femur SF: 0.9 SF: 1.2

17. 17
EFFECT OF SLED PULSE
• SF:
0.9
• SF:
1.2

18. FINAL MODEL
• A knee airbag is recommended to reduce femur loads, is added to the final model.
18
Baseline model Final model
Sled Pulse Scale Factor 1 0.95
Pretensioner Sensor timing [ms] 13 10
Knee Airbag VSCA, PSCA NA 0.3, 0.3
Airbag VSCA, PSCA 1, 1 1.2, 0.9
Knee Airbag

19. 19
FINAL MODEL
Injury Criteria Threshold Values Baseline Final Model
HIC15 700 722 613
Chest Acceleration [g] 60 109.3 52
Chest Deflection [mm] 63 58.44 57.9
Left Femur Load [kN] 10 29.5 13
Right Femur Load [kN] 10 31.3 11.6
• Knee airbag added to the model highly decreases the femur loads.
• Slight reduction in sled pulse helps to control the injury values, specially the HIC.
• While the combined effect of early action seatbelt pretensioner sensor time and airbag
flow scale factors (slightly high VSCA and slightly low PSCA), helps in controlling of HIC
and Chest injury values.

20. 20
FINAL MODEL
0
20
40
60
80
100
120
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
Chest Acceleration Baseline Final Model
0
10.5
21
31.5
42
52.5
63
0 15 30 45 60 75 90 105 120 135 150
Deflection[mm]
Time [ms]
Chest Deflection Baseline Final Model
0
50
100
150
200
0 15 30 45 60 75 90 105 120 135 150
Acceleration[g]
Time [ms]
HIC15 Baseline Final Model
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Left Femur Baseline Final Model
-40
-30
-20
-10
0
10
0 15 30 45 60 75 90 105 120 135 150
Force[kN]
Time [ms]
Right Femur Baseline Final Model

21. 21
FINAL MODEL
• Final Model• Baseline

22. CONCLUSION
• Airbag:
– High pressure in airbag can be a cause of injury. Similar will be the effect for low volume.
– High volume and slightly low pressure is the optimum case. High volume reduces the
dummy travel and slightly low pressure will not make the bag very stiff.
• Seatbelt:
– Early action of pretensioner was seen favorable, reducing the slack proved beneficial.
– Making the seatbelt very stiff (retractor force), are the reasons for high chest injuries.
• Sled Pulse:
– Reduction in sled pulse, decreased the injury values.
– However, this should not be reduced highly, since it will not reproduce the exact crash
impact scenario which could occur in real life.
– Slight reduction in sled pulse is justified, since it could be reduced by improving the
structure of the vehicle which could be made to absorb more energy.
22