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A Preliminary Study on Helicopter Crashworthy Stages Adapted to Different Impact ConditionsPaolo Astori
Department of Aerospace Science and Technology
CrashLab Research Group
Crash and dynamic test facilities and numerical tools
2
3Crash conditions
ax
az
High vertical component of acceleration
Main injury risk:• High lumbar spine load
Crash loads mitigation
Energy absorption by:• Landing gear shock absorber (certification at v = 2 m/s)• Subfloor (general recommendations)• Seat (certification at 9.15 m/s, 30 g’s)
4
ax
az
Object
Preliminary study:1. Set-up a numerical model of the relevant structural area and systems2. Define the mechanical parameters that could be controllable and
adaptive3. Carry out parametrical analyses at increasing impact speeds
5
Landing gear 6
0 50 100 150 2000
0.5
1
1.5
2
2.5x 10
4
Shock-Absorber Stroke [mm]
Gro
und R
eact
ion [
N]
AW109H02 -2pt limit
Landing gear 7
0 50 100 150 200
-20
0
20
40
60
80
Shock
-Abso
rber
Pre
ssure
[bar]
Shock-Absorber Stroke [mm]
AW109H02 -2pt limit
-0.5 0 0.5 1 1.5 2
-20
0
20
40
60
80
SA Rate [m/s]
DeltaPr
[bar]
AW109H02 -2pt limit
Compression
Release
0 50 100 150 200
-20
0
20
40
60
80
Shock
-Abso
rber
Pre
ssure
[bar]
Shock-Absorber Stroke [mm]
AW109H02 -2pt limit
GAS
OIL
TOTAL
Increases with SA rate
Landing gear
Adaptive shock absorber
Metering of the side orifice areas by electrically-controlled shuttersControl of max spool displacementMagneto-rheological fluids
8
CLOSED OPEN
FLOW FLOW
Seat 9
a = 30 g
Seat
Adaptive energy absorber
Roller distance calibrated by a micro-actuation system
10
Numerical model 11
Simplified model based on lumped parameters approachAnthrpomorphic Test Dummy, Seat system and Landing Gear validated against experimental data in certification dynamic conditions
Numerical analysis
Sensitivity analysis - response surface:
• max lumbar spine loads as functions of the mechanical characteristics of landing gear shock absorber and seat energy absorber
12
Numerical analysis: model and definition of parameters
Landing gear3 rigid bodies: wheel, piston block and cylinder blockPolytropic response: fixedViscous response: from 0 to 2 m/s from experimental data
from 2 to 4 m/s extrapolated but fixedfrom 4 to 8 m/s variable
13
45%
15%
-2 0 2 4 6 8-50
0
50
100
150
200
250
300
350Shock absorber viscous response
Stroke rate [m/s]
Loa
d [k
N]
Numerical analysis: model and definition of parameters
14
Stroke
Loa
d
BOTTOMING
190 mm
LOAD LEVEL RANGE: 6000 TO 16000 N
Seat energy absorber2 rigid bodies: lower fixed part and upper moveable partElastic – perfectly plastic response
Numerical analysis: results
Response surfaces vs. impact speed from 11 to 15 m/s (std speed for seats v = 9.15 m/s)
15
4 .7
4.7
4.7
5.7
5. 7
5.7 5. 7
5.7
5.7
6.7
6 .7
6.7
7.7
7. 7
7.7
8.7
8.7
8.7
9.7
9. 7
9.7
10.7
1 0.7
10.7
1 1.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
45
55
5565
65
65
75
75
75
8 5
85
85
9 5
9 5
95
105
10 5
105
115
115
115
125
125
125
135
135
135
145
145
145
155
155
155
16 5
165
165
1 75
175
175
185
185
185
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
30
40
40
40
50
50
50
50
60
60
60
70
70
70
80
80
90
90
100
100
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
11 m/s
Numerical analysis: results
Response surfaces vs. impact speed from 11 to 15 m/s (std speed for seats v = 9.15 m/s)
16
4 .7
4.7
4.7
5.7
5. 7
5.7 5. 7
5.7
5.7
6.7
6 .7
6.7
7.7
7. 7
7.7
8.7
8.7
8.7
9.7
9. 7
9.7
10.7
1 0.7
10.7
1 1.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
45
55
5565
65
65
75
75
75
8 5
85
85
9 5
9 5
95
105
10 5
105
115
115
115
125
125
125
135
135
135
145
145
145
155
155
155
16 5
165
165
1 75
175
175
185
185
185
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
30
40
40
40
50
50
50
50
60
60
60
70
70
70
80
80
90
90
100
100
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
11 m/s12
5.7
5.76 .7
6.7
6.7
6.7
6.7
7.7
7. 7
7 .7
8.7
8.7
8.7
9.7
9.7
9.7
10.7
10.7
10. 7
11.7
11. 7
11. 7
12.7
12.713
.713
.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
55
65
65
75
75
85
85
8 5
95
95
9 5
105
105
1 05
115
115
115
125
125
125
135
135
135
145
145
145
155
155
155
1 65
165
165
175
175
175
185
185
185
195
195
1 95
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
60
6070
70
70
80
80
80
90
90
90
100
100
100
100
110
110
110
120
120
130
130
140150
16017 0
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
Numerical analysis: results
Response surfaces vs. impact speed from 11 to 15 m/s (std speed for seats v = 9.15 m/s)
17
4 .7
4.7
4.7
5.7
5. 7
5.7 5. 7
5.7
5.7
6.7
6 .7
6.7
7.7
7. 7
7.7
8.7
8.7
8.7
9.7
9. 7
9.7
10.7
1 0.7
10.7
1 1.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
45
55
5565
65
65
75
75
75
8 5
85
85
9 5
9 5
95
105
10 5
105
115
115
115
125
125
125
135
135
135
145
145
145
155
155
155
16 5
165
165
1 75
175
175
185
185
185
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
30
40
40
40
50
50
50
50
60
60
60
70
70
70
80
80
90
90
100
100
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
11 m/s1213
5.7
5.76 .7
6.7
6.7
6.7
6.7
7.7
7. 7
7 .7
8.7
8.7
8.7
9.7
9.7
9.7
10.7
10.7
10. 7
11.7
11. 7
11. 7
12.7
12.713
.713
.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
55
65
65
75
75
85
85
8 5
95
95
9 5
105
105
1 05
115
115
115
125
125
125
135
135
135
145
145
145
155
155
155
1 65
165
165
175
175
175
185
185
185
195
195
1 95
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
60
6070
70
70
80
80
80
90
90
90
100
100
100
100
110
110
110
120
120
130
130
140150
16017 0
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
6.7
6.7
6.7
7.7
7.7
7 .7
7.7
8 .7
8.7
8.7
9.7
9.7
9 .7
10.7
10.7
10.7
11.7
11.7
1 1. 7
1 2.7
12.7
12.7
13.7
13.7
13.7
14.7
14.7
15.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
65
75
7585
85
95
95
105
105
115
115
125
125
125
135
135
135
145
145
145
155
155
155
165
165
1 65
175
175
175
185
185
185
195
195
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
90
901 00
100
110
110
110
120
120
120 130
130
140
140
140
150
150
160
160
160
170
170
170
180
180190
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
Numerical analysis: results
Response surfaces vs. impact speed from 11 to 15 m/s (std speed for seats v = 9.15 m/s)
18
4 .7
4.7
4.7
5.7
5. 7
5.7 5. 7
5.7
5.7
6.7
6 .7
6.7
7.7
7. 7
7.7
8.7
8.7
8.7
9.7
9. 7
9.7
10.7
1 0.7
10.7
1 1.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
45
55
5565
65
65
75
75
75
8 5
85
85
9 5
9 5
95
105
10 5
105
115
115
115
125
125
125
135
135
135
145
145
145
155
155
155
16 5
165
165
1 75
175
175
185
185
185
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
30
40
40
40
50
50
50
50
60
60
60
70
70
70
80
80
90
90
100
100
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
11 m/s121314
5.7
5.76 .7
6.7
6.7
6.7
6.7
7.7
7. 7
7 .7
8.7
8.7
8.7
9.7
9.7
9.7
10.7
10.7
10. 7
11.7
11. 7
11. 7
12.7
12.713
.713
.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
55
65
65
75
75
85
85
8 5
95
95
9 5
105
105
1 05
115
115
115
125
125
125
135
135
135
145
145
145
155
155
155
1 65
165
165
175
175
175
185
185
185
195
195
1 95
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
60
6070
70
70
80
80
80
90
90
90
100
100
100
100
110
110
110
120
120
130
130
140150
16017 0
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
6.7
6.7
6.7
7.7
7.7
7 .7
7.7
8 .7
8.7
8.7
9.7
9.7
9 .7
10.7
10.7
10.7
11.7
11.7
1 1. 7
1 2.7
12.7
12.7
13.7
13.7
13.7
14.7
14.7
15.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
65
75
7585
85
95
95
105
105
115
115
125
125
125
135
135
135
145
145
145
155
155
155
165
165
1 65
175
175
175
185
185
185
195
195
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
90
901 00
100
110
110
110
120
120
120 130
130
140
140
140
150
150
160
160
160
170
170
170
180
180190
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
6.7
7. 7
7.7
8.7
8.7
8 .7
9.7
9.7
9 .7
10. 7
10.7
10.7
11.7
11.7
11.7
12.7
12.7
1 2.7
1 3. 7
13.7
13.7
14.7
14.7
1 4.7
15 .7
15.7
15.7
16.7
16.7
16.7
17. 7
17.7
1 7.718.7
18.7
18.7 19.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
8595105115
125
135
145
145
1 55
155
165
165
175
175
1 85
185
185
195
195
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
140
140
1 50
150
160
160
170
170
180
180
190
190
190
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
Numerical analysis: results
Response surfaces vs. impact speed from 11 to 15 m/s (std speed for seats v = 9.15 m/s)
19
4 .7
4.7
4.7
5.7
5. 7
5.7 5. 7
5.7
5.7
6.7
6 .7
6.7
7.7
7. 7
7.7
8.7
8.7
8.7
9.7
9. 7
9.7
10.7
1 0.7
10.7
1 1.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
45
55
5565
65
65
75
75
75
8 5
85
85
9 5
9 5
95
105
10 5
105
115
115
115
125
125
125
135
135
135
145
145
145
155
155
155
16 5
165
165
1 75
175
175
185
185
185
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
30
40
40
40
50
50
50
50
60
60
60
70
70
70
80
80
90
90
100
100
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
11 m/s12131415
5.7
5.76 .7
6.7
6.7
6.7
6.7
7.7
7. 7
7 .7
8.7
8.7
8.7
9.7
9.7
9.7
10.7
10.7
10. 7
11.7
11. 7
11. 7
12.7
12.713
.713
.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
55
65
65
75
75
85
85
8 5
95
95
9 5
105
105
1 05
115
115
115
125
125
125
135
135
135
145
145
145
155
155
155
1 65
165
165
175
175
175
185
185
185
195
195
1 95
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
60
6070
70
70
80
80
80
90
90
90
100
100
100
100
110
110
110
120
120
130
130
140150
16017 0
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
6.7
6.7
6.7
7.7
7.7
7 .7
7.7
8 .7
8.7
8.7
9.7
9.7
9 .7
10.7
10.7
10.7
11.7
11.7
1 1. 7
1 2.7
12.7
12.7
13.7
13.7
13.7
14.7
14.7
15.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
65
75
7585
85
95
95
105
105
115
115
125
125
125
135
135
135
145
145
145
155
155
155
165
165
1 65
175
175
175
185
185
185
195
195
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
90
901 00
100
110
110
110
120
120
120 130
130
140
140
140
150
150
160
160
160
170
170
170
180
180190
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
6.7
7. 7
7.7
8.7
8.7
8 .7
9.7
9.7
9 .7
10. 7
10.7
10.7
11.7
11.7
11.7
12.7
12.7
1 2.7
1 3. 7
13.7
13.7
14.7
14.7
1 4.7
15 .7
15.7
15.7
16.7
16.7
16.7
17. 7
17.7
1 7.718.7
18.7
18.7 19.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
8595105115
125
135
145
145
1 55
155
165
165
175
175
1 85
185
185
195
195
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
140
140
1 50
150
160
160
170
170
180
180
190
190
190
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
7.7
8.79.710.711.7
12.7
12.7
13.7
13.7
14.7
14.7
15.7
15.7
16 .7
16.7
17.7
17.718.7
18.7
19.7
1 9.7
F Seat [kN]
w S
h A
bs [%
]
Lumbar spine load [kN]
6 8 10 12 14 1615
20
25
30
35
40
45
145155165
175185
19 5
195
F Seat [kN]
w S
habs
[%]
Seat stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
190
190
F Seat [kN]
w S
habs
[%]
Subfloor stroke [mm]
6 8 10 12 14 1615
20
25
30
35
40
45
MIGRATION OF THEDESGIN POINT vs. SPEED
20System arming
Crash landing condition triggered by ground proximity and vertical velocity detection
Pre-setting of landing gear shock absorber and seat energy absorber as a function of velocity (and occupant weight)
orClosed-loop control?
Work in progress
Test rig for adaptive seat energy absorber
21
FORCE
ACTUATOR
ADJUSTABLEROLLER
controller actuator
sensors?
roller position EA forceref
lumbar spine load
Extra slides 22
Full-scale test
Helisafe TA EU project, full scale UH-1 crash test, 15 m/s, 32°
23
Landing gear
Introduction of a passive crash stage
24
Subfloor 25
Numerical analysis: model and definition of parameters
Subfloor1 rigid body: floorElastic – perfectly plastic responseMechanical structure made of joined components ⇒ adaptive system hardly feasible
26
Stroke
Lo
ad
BOTTOMING
190 mm
CRUSHING LOAD FIXED TO 6000 N (OPTIMUM IN HIGH SPEED CONDITION)
