jun-ichi tomioka , kazuhiro kiguchi, yohsuke tamura, hiroyuki mitsuishi ,
DESCRIPTION
The 4th International Conference on Hydrogen Safety September 18th, 2011. Influence of Pressure and Temperature on the Fatigue Strength of Type-3 Compressed-Hydrogen Tanks for Vehicles. Jun-ichi TOMIOKA , Kazuhiro KIGUCHI, Yohsuke TAMURA, Hiroyuki MITSUISHI , - PowerPoint PPT PresentationTRANSCRIPT
The 4th International Conference on Hydrogen Safety September 18th, 2011Influence of Pressure and
Temperature on the Fatigue Strength of Type-3 Compressed-Hydrogen Tanks for
Vehicles
Jun-ichi TOMIOKA, Kazuhiro KIGUCHI, Yohsuke TAMURA,
Hiroyuki MITSUISHI,
Japan Automobile Research Institute
2
1. INTRODUCTION
3
www.peugeot.com
Carbon Fiber Reinforced
Plastic (CFRP)
Aluminum Alloy Liner
35MPa Type-3
35 MPa Compressed Hydrogen Tanks
Type-3 : Fully wrapped composite tanks with metal liners
Type-4 : Fully wrapped composite tanks with plastic liners
“Fuel Cell” or“Hydrogen Engine”
Background 1 – Hydrogen Tank
4
Background 2 – Fatigue Strength Fatigue strength against pressure cycling.
Hydraulic pressure cycle test examination of fatigue life fluid temperature changes slightly 300 cycles per one hour
Gas cycle test examination of fatigue life and hydrogen
embrittlement gas temperature changes greatly 1 cycle per one hour
Pre
ssur
e
Time
Leak...
It is not clear what effect the diferences in the test methods have on the fatigue process.
5
Background 3 – Load on Tank Internal pressure (gas)
Pressure changes with temperature, even if the same mass is filled.
SOC (State of charge) :hydrogen-filled state based on hydrogen-mass in the tank.
Thermal stress Because of differences in
thermal expansion rates, thermal stress is generated by temperature changes.
CFRP thermal expansion:
small
Aluminum Alloy Linerthermal expansion:
large
35MPaType-3
Fatigue life under the SOC100% condition is not
clear
-60-40-20 0 20 40 60 80 1000
1020304050
2835
44
SOC:100%
Temperature [°C]
Pre
ssu
re [
MP
a]
6
Purpose
To clarify the influence of environmental temperature and pressure assuming SOC100% on the fatigue life of compressed hydrogen tanks for vehicles.
Hydraulic pressure cycle tests with varying environmental temperatures and pressures
LT(low temp.) : -40°C, 28MPaRT(room temp.) : 15°C, 35MPaHT(high temp.) : 85°C, 44MPaAT(ambient temp.) : 15°C ~25°C, 44MPa
7
2. MATERIALS AND METHOD
8
Specification of Test Tank
Specification
FillingPressure [MPa]
Volume
[L]
External Diameter
- Length [mm]
Liner Material
Type-3 35 28 F280 – 730 Aluminum Alloy
Schematic Diagram of Compressed Hydrogen Tank
Carbon Fiber Reinforced Plastic (CFRP) Layer
Liner
Tail End PlugCylindrical Section
Dome Section
Specification of Test Tank
9
Thermostatic Chamber
Constant-temperature
(-40 ~ 150 deg.C)
High pressure pipe
Pump
Test Equipment – Hydraulic Tester
120 MPa Intensifier
Thermostatic Chamber
Intensifier
Power Unit
hydraulic Tester
10
0
10
20
30
40
50
Pres
sure
[M
Pa]
-40℃28MPa
15℃35MPa
85℃44MPa
Test Conditions
Pressure profile of cycle test
Test conditions of pressure cycle test
LT RT HT AT*
SOC 100% 125%
Temperature -40°C +15°C +85°C +15~25°
CMaximumPressure 28MPa 35MPa 44MPa 44MPa
MinimumPressure 0 MPa
Fluid(Medium)
Perfluoro-
polyether
Deionized Water
Frequency 15 sec/cycle
Waveform Sine Curve
TerminationOccurrence of Leak Before Break
(LBB) * Ambient-Temperature Pressure-Cycle Test specified in JARI S001
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3. RESULTS OF CYCLING TESTS
12
Fatigue Life of Type-3 Tank
Leakage occurred in all tanksLives under SOC 100% were longer than the life under
AT(SOC125%). →Pressure-cycle test under AT(SOC125%) can ensure the safety of a Type-3 tank against fatigue.
LT:-40℃28 MPa
SOC100%
RT:15℃35 MPa
SOC100%
HT:85℃44 MPa
SOC100%
AT:15~25℃44 MPa
SOC125%
10,000
100,000
1,000,000
135,626 147,797
27,645 22,782
Fati
gu
e L
ife [
cycle
s]
Fatigue life determined by hydraulic pressure-cycle tests
SOC100% the mean ± S.E., N=2
Leak Leak
Leak Leak
SOC125%
13
4. DISCUSSION
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Liner Stress of Type-3 tank
To determine the liner stress, we measured the strain on the inner surface of the liner.
①Stress due to internal pressure (tensile stress)
②Residual stress Autofrettage processing produces residual stress
(CFRP: tensile stress, Liner: compressive stress) ③Thermal stress
Because of differences in thermal expansion rates in aluminum alloy and CFRP
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①Stress due to Internal Pressure
Strain gauge on the liner
Hydraulic
system
Hydraulic pressure
Measuring method for strain due to internal pressure
The inner surface of the liner
Strain gauges were attached to the inner surface of the liner
Applying pressure to the tank
Measuring the strain due to internal pressure
Caluculate the stress based on the measured strain.
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①Stress due to Internal Pressure
Relationship between pressure and stress of the liner
Relationship between pressure and stress of the liner was linear-proportion.
0 10 20 30 40 500
50100150200250300350400450
circumferential stressaxial stress
Pressure [MPa]
Lin
er
str
ess [
MP
a]
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②Residual Stress
Measuring method for residual strain
A, B : Outer surface of CFRPa, b : Inner surface of liner
BA
Strain gauges
Cut 1 Cut 2
a
b
Strain gauges
Cut 3 : Separate CFRP and LinerCFRP
Liner
AabB
In all tanks after the pressure-cycle test, strain gauges attached to the outer surface of the CFRP and the inner surface of the liner
Cutting the tank at room temperature (15°C) to release the residual strain
Measuring the residual strain Caluculate the stress based on the measured strain.
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②Residual Stress (Measured results)
Residual stress of the liner after pressure-cycle test at HT was smaller than the others.
Usageenvironment
Liner circumferential
stress
LT : -40°C -256MPa
RT : 15°C -239MPa
HT : 85°C -126MPa
Residual stress of Liner
Axialstrain
Circumferentialstrain
CFRP 0.097% 0.034%
Liner -0.134% -0.265%
Residual strain of the tank after the pressure-cycle test
at RT
Tensile strain resided in the CFRP and compressive stress resided in the liner.
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③Thermal StressThermostatic
Chamber
Aluminum tube
-40°C ~ 85°CThermocouple
Strain gauge
εts = ε1 - ε2
εts: Strain due to the thermal stressε1 : Strain of the liner
ε2 : Strain of the aluminum tube
ε1 ε2
Strain gauges and thermocouples were attached to the inner surface of the liner and the aluminum tube
Changes in the temperature ranging from -40°C to +85°C(①15°C→②-40°C→③15°C→④85°C→⑤15°C )
Measuring the thermal strain Caluculate the stress based on the measured strain.
Measuring method for thermal strain
Thermocouple
Strain gauge
20
-50 0 50 100 -400
-300
-200
-100
0
Temperature [°C]
Lin
er
Str
ess [
MP
a]
Relationship between temperature and circumferential stress of the liner
In high-temperature and low-pressure, the liner was loaded with residual compressive stress and compressive stress due to the thermal stress.→The liner was deforemd plastically in high-temperature and low-pressure.
plastic deformation(yield stress: 300MPa)
③Thermal Stress
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Liner Stress (hydraulic cycle)
-50 -30 -10 10 30 50 70 90-400
-300
-200
-100
0
100
200
SOC0%
SOC100%
SOC125% at 20°C
Temperature [°C]
Lin
er
Str
ess [
MP
a]
Relationship between temperature and circumferential stress of the liner
Tensile stress at AT (SOC125%) exceeds that under any SOC100% condition.
⇒The pressure-cycle test under AT can ensure the safety of a Type-3 tank against fatigue life.
plastic deformation(yield stress: 300MPa)
LT -40°C,28MPa HT
85°C,44MPa
AT ( 15~25°C, 44MPa )
RT15°C,35MP
a
22
-50 -30 -10 10 30 50 70 90-400
-300
-200
-100
0
100
200
SOC0%
SOC100%
inferred SOC100% in gas cycle
Temperature [°C]
Lin
er
Str
ess [
MP
a]
Liner Stress (gas cycle)
Relationship between temperature and circumferential stress of the liner
gas cycle
at -40°Cgas
cycleat 15°C
the gas cycle is the repetition of a low-temperature and low-pressure condition and a high-temperature and high-pressure condition.
→The liner will be not deforemd plastically in gas cycle.
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-50 -30 -10 10 30 50 70 90-400
-300
-200
-100
0
100
200
SOC0%
SOC100%
inferred SOC100% in gas cycle
Temperature [°C]
Lin
er
Str
ess [
MP
a]
Liner Stress (hydraulic and gas)
Relationship between temperature and circumferential stress of the liner
gas cycle
at 15°C
The stress range during gas cycles is smaller than during hydraulic cycles.
⇒Hydraulic cycles are more severe than gas cycles.
LT -40°C
HT85°C
RT15°C
gas cycle
at -40°C
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5. SUMMARY
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Summary
Pressure cycle tests assuming SOC 100% in type-3 tanks revealed that The fatigue life assuming SOC 100% is longer
than the room temp. pressure cycle test (AT,SOC125%).
The room temp. pressure cycle test (AT,SOC125%) can ensure the safety of a Type-3 tank against fatigue.
Stress range during gas cycles is smaller than during hydraulic cycles, so the hydraulic-cycle tests are more severe than gas-cycle tests.
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THANK YOU
This study is summarizes part of the results of "Establishment of Codes & Standards for Hydrogen Economy Society - Research and Development Concerning Standardization of Hydrogen and Fuel Cell Vehicles" consigned by the New Energy and Industrial Technology Development Organization (NEDO).