Durability of Aircraft Structural Composites Processed by VaRTM Masahiro Moriyama, Kenichi Yoshioka, Akihiko Kitano Toray Industries, Inc.
Durability of Aircraft Structural Composites Processed by VaRTM
Masahiro Moriyama, Kenichi Yoshioka, Akihiko KitanoToray Industries, Inc.
2
Contents
1. Background2. Fatigue Tests
i. OHC : Open Hole Compressionii. CAI : Compression After Impact
3. Environmental Exposure Testsi. Temperature Exposureii. Moisture Exposureiii. Thermal Cycle Exposureiv. Hygrothermal Cycle Exposure
4. Modeling of Fatigue Damage Propagation5. Conclusion
3
CFRP Aircraft Structures
CFRP Ratio in Aircraft Structures
CFR
P W
eigh
t Rat
io in
Str
uctu
re [w
t%]
First Flight Year
1995 1970 1975 1980 1985 1990 2000
100
80
60
40
20
0 2005 2010
F14 F15
S76
Learfan 2000
Avtek 400
Voyager
V22
LHK Stership
F16 F18
AV8B
B757
B767 A310
X29
ATR42 A300
EAP Rafal
JAS39
ATF
Rafal D
A320
ATR72
A340 B777
Rotorcraft Business jets
Smallaircraft
Largeaircraft
A340-600
A380
B787
1. Background
4
CFRP Fabrication Process
Common applications:
Trucks, Boats, Building structures, etc.
Large and complex parts Low costLow energy consumption
Prepreg / autoclave process (conventional)
De-molding
Resin prepreg
Autoclave
CFRP
Bagging Cure Prepregging Lay-up CF
Filming
Bagging film
CF
Resin Bagging film
Pump CFRP De-molding Bagging Cure Lay-up
VaRTM (Vacuum-assisted Resin Transfer Molding)
Advantage of VaRTM Process
Disadvantage of VaRTM Process CFRP properties
1. Background
5
A-VaRTM
VaRTMLarge and complex parts, Low cost
Trucks, Boats, Building Structures, etc.
Fabrication technologies<Toray>
<Mitsubishi Heavy Industries>
Material technologies<Toray>
Advanced-VaRTM“A-VaRTM”
Large and complex parts, Low cost, Low energy consumption High performance
Aircraft primary structural elements
A-VaRTM Definition
Problem of A-VaRTM
Insufficient durability data compared with traditional materials
1. Background
6
Summary
・Fatigue tests (CAI, OHC)
・Environmental exposure tests (assumed for aircraft use)
1. Acquiring durability data of A-VaRTM
2. Modeling of fatigue damage propagation
・Damage detection of OHC fatigue specimen
・Life prediction of OHC fatigue
Objective:Long-term degradation model of A-VaRTM
1. Background
7
OHC Fatigue Test Results2. Fatigue Data
305
Hol
e D
iam
eter
:6.3
5
38.1
Unit:mmCompression-CompressionR = 10 f = 5Hz
Stacking Sequence:[45/0/-45/90] 2S
0
10
20
30
40
50
1 10 102 103 104 105 106
Cycles to Failure
Min
imum
Stre
ss [k
si]
T800H/3900-2 (G145)
CZ8433DP/TR-A37
σmin
σmax
8
CAI Fatigue Test Results2. Fatigue Data
0
10
20
30
40
50
1 10 102 103 104 105 106
Cycles to Failure
Min
imum
Stre
ss [k
si]
T800S/3900-2B
CZ8433DP/TR-A37
270in-lbs
720in-lbs
Compression-CompressionR = 10 f = 5Hz σmin
σmax
Stacking Sequence:[45/0/-45/90] 3S
152.
4
101.6
Unit:mm
9
1. Temperature Exposure
4. Hygrothermal Cycle Exposure
t
T
100°C
t
T
60°C / 85%RH
2. Thermal Cycle Exposure
3. Moisture Exposure
3. Environmental Resistance Data
3min t
T
RT
-54℃
100℃
10min 3min
10min
(125℃ for T800S/3900-2B)
-55°C
82°C
t
T
35°C 95%RH
24min 24min 72min
(Condition of T800S/3900-2B)
t
T
49ºC/95%RH 12h
within 24hr -54ºC 5min
36min (1cycle )
-54ºC
T
60min
71ºC 5min
Conditions of Environmental Exposure
Conditions of environmental exposure were based on durability study of T800S/3900-2B.
10
Composite Testing1. CAI
2. OHC
3. IPS
[45/0/-45/90]3sImpact enegy = 30.5J (270in-lb)Deflection rate = 1.27mm/min
[45/0/-45/90]2sDeflection rate = 1.27mm/min
[45/-45]2sDeflection rate = 1.27mm/min
Mechanical properties were measured before and after environmental exposure.
3. Environmental Resistance Data
11
CZ8433DP/TR-A37
Test Matrix of Environment Exposure Tests 3. Environmental Resistance Data
0cycle400cycles
2000cycles
4. Hygrothermal Cycle Exposure[49℃/95%RH→-54℃→71℃]
0hr1000hrs3000hrs
3. Moisture Exposure[60℃/85%RH]
0cycle3000cycles
2. Thermal Cycle Exposure[-54℃→100℃]
0hr3000hrs
1. Temperature Exposure[100℃]
IPSOHCCAI
12
Temperature Exposure [ 100℃]
0
10
20
30
40
50
60
0 1000 2000 3000 4000Exposure period [hrs]
CA
I [ks
i]
T800S/3900-2B
CAI After Temperature Exposure
0
10
20
30
40
50
60
0 1000 2000 3000 4000Exposure period [hrs]
CA
I [ks
i]
CZ8433DP/TR-A37
Average of blank specimen
3. Environmental Resistance Data
13
0
10
20
30
40
50
0 1000 2000 3000 4000Exposure period [hrs]
OH
C [k
si]
OHC After Temperature Exposure
T800S/3900-2B
10
20
30
40
50
0 1000 2000 3000 4000Exposure period [hrs]
OH
C [k
si]
CZ8433DP/TR-A37
Temperature Exposure [ 100℃]
3. Environmental Resistance Data
14
0
5
10
15
20
25
0 1000 2000 3000 4000Exposure period [hrs]
In-p
lane
she
ar s
treng
th [k
si]
IPS Strength After Temperature Exposure
T800S/3900-2B
Exposure period [hrs]
0
5
10
15
20
25
0 1000 2000 3000 4000
In-p
lane
she
ar s
treng
th [k
si]
CZ8433DP/TR-A37
Temperature Exposure [ 100℃]
3. Environmental Resistance Data
15
CAI After Thermal Cycle Exposure
0
10
20
30
40
50
60
0 1000 2000 3000 4000Exposure period [cycles]
CA
I [ks
i]
0
10
20
30
40
50
60
0 1000 2000 3000 4000Exposure period [cycles]
CA
I [ks
i]
T800S/3900-2B CZ8433DP/TR-A37
3. Environmental Resistance Data
Thermal Cycle Exposure [-54℃→125 or 100℃]
16
OHC After Thermal Cycle Exposure
10
20
30
40
50
0 1000 2000 3000 4000Exposure period [cycles]
OH
C [k
si]
10
20
30
40
50
0 1000 2000 3000 4000Exposure period [cycles]
OH
C [k
si]
00
T800S/3900-2B CZ8433DP/TR-A37
3. Environmental Resistance Data
Thermal Cycle Exposure [-54℃→125 or 100℃]
17
IPS Strength After Thermal Cycle Exposure
Exposure period [cycles]
0
5
10
15
20
25
0 1000 2000 3000 4000
In-p
lane
she
ar s
treng
th [k
si]
Exposure period [cycles]
0
5
10
15
20
25
1000 2000 3000 4000
In-p
lane
she
ar s
treng
th [k
si]
0
T800S/3900-2B CZ8433DP/TR-A37
3. Environmental Resistance Data
Thermal Cycle Exposure [-54℃→125 or 100℃]
18
Moisture Exposure [60℃/85%RH]
CAI After Moisture Exposure
0
10
20
30
40
50
60
0 1000 2000 3000 4000Exposure period [hrs]
CA
I [ks
i]
0
10
20
30
40
50
60
0 1000 2000 3000 4000Exposure period [hrs]
CA
I [ks
i]
T800S/3900-2B CZ8433DP/TR-A37
3. Environmental Resistance Data
19
OHC After Moisture Exposure
10
20
30
40
50
0
OH
C [k
si]
01000 2000 3000 4000
Exposure period [hrs]
T800S/3900-2B CZ8433DP/TR-A37
10
20
30
40
50
0
OH
C [k
si]
01000 2000 3000 4000
Exposure period [hrs]
Moisture Exposure [60℃/85%RH]
3. Environmental Resistance Data
20
IPS Strength After Moisture Exposure
Exposure period [hrs]
0
5
10
15
20
25
1000 2000 3000 4000
In-p
lane
she
ar s
treng
th [k
si]
0
T800S/3900-2B
Exposure period [hrs]
0
5
10
15
20
25
1000 2000 3000 4000
In-p
lane
she
ar s
treng
th [k
si]
0
CZ8433DP/TR-A37
Moisture Exposure [60℃/85%RH]
3. Environmental Resistance Data
21
CAI After Hygrothermal Cycle Exposure
0
10
20
30
40
50
60
CA
I [ks
i]
0 500 1000 1500Exposure period [cycles]
T800S/3900-2B
0
10
20
30
40
50
60
0 500 2500Exposure period [cycles]
CA
I [ks
i]
1000 1500 2000
CZ8433DP/TR-A37
3. Environmental Resistance Data
Hygrothermal Cycle Exposure [-55℃→35℃/95%RH→82℃ or 49℃/95%RH→-54℃→71℃]
22
OHC After Hygrothermal Cycle Exposure
10
20
30
40
50
0
OH
C [k
si]
0 1000 2500
Exposure period [cycles]
10
20
30
40
50
0
OH
C [k
si]
0500 1000 1500
Exposure period [cycles]
T800S/3900-2B
500 1500 2000
CZ8433DP/TR-A37
3. Environmental Resistance Data
Hygrothermal Cycle Exposure [-55℃→35℃/95%RH→82℃ or 49℃/95%RH→-54℃→71℃]
23
IPS Strength After Hygrothermal Cycle Exposure
0
5
10
15
20
25
In-p
lane
she
ar s
treng
th [k
si]
0 500 1000 1500Exposure period [cycles]
T800S/3900-2B
0
5
10
15
20
25
In-p
lane
she
ar s
treng
th [k
si]
0 500 1000 2500Exposure period [cycles]
20001500
CZ8433DP/TR-A37
3. Environmental Resistance Data
Hygrothermal Cycle Exposure [-55℃→35℃/95%RH→82℃ or 49℃/95%RH→-54℃→71℃]
24
CT Image of OHC Fatigue Specimen
Fatigue behavior is dominated by delamination from the microbacking.
0.5mm
0% 50% 65%
80% 95%
0°
90°
0° 0° 0°
0° 0°
Microbackling
Delamination
Delamination growth
Tool side
Viewpoint
σmin=0.775σ0(Fatigue life is about 71,000 cycles.)
4. Modeling
25
y = 2E-55x21.27
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1.0E-05100 1000
∆GI[J/m2]
da/d
N[m
/cyc
le]
Life Prediction of OHC FatigueAnalytical model
σ0
5mm
x
Distribution of σy
y
Delamination
σ0
6mm
6.35mm
a0=2mm
5mm
a1=6mm
σy=1.5σ0
σy=1.5σ0
Cross-section
Two delaminations
(1)Overview
(2)Analytical model
Analytical solution for fatigue life
∫ ∆=
1
0)(
a
anf Gm
daN
Nf:Cycles to failurea0:Initial delamination lengtha1:Final delamination lengthΔG:Energy release ratem,n:Fitting parameter
Fitting parameters were determined from da/dN plot during DCB and ENF fatigue tests.
4. Modeling
26
Analytical Result
Analytical result is in good agreement with experimental result.
S-N Curve (OHC)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1 10 100 1000 10000 100000 1000000
Cycles to Failure
Nor
mal
ized
Stre
ss
Experimental Data
Analysis
4. Modeling
27
Conclusion
Fatigue TestsOHC and CAI fatigue behavior of A-VaRTM material is similar to that of aerospace grade prepreg.
Environmental Exposure TestsMechanical properties of A-VaRTM material exhibited little degradation after environmental exposure tests.This is similar to that of aerospace grade prepreg.
Modeling of Fatigue Damage PropagationOHC fatigue behavior of A-VaRTM material is dominated by delamination from the microbackling of 0 degree layer.By parameterizing energy release rate and delamination length, analytical result of OHC fatigue life was in good agreement withexperimental result.