Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 1 1
HYCOMAT: test rig under high
pressure of gaseous hydrogen at
Pprime Institute, France
Gilbert Hénaff, Sylvie Castagnet,
Denis Bertheau, Guillaume Benoit
Institut P’ • UPR CNRS 3346
Département Physique et Mécanique des Matériaux ENSMA • Téléport 2 1, avenue Clément Ader • BP 40109
F86961 FUTUROSCOPE CHASSENEUIL Cedex
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 2
Outline • Presentation of Pprime Institute – Damage & Durability
• Design approach
• Safety
• Capabilities
• Gas management
• Test specimens
• Problems (solved or not)
• Test procedures: – tensile and compressive test, explosive decompression failure,
dilatation (polymers)
– Fatigue crack growth (metals)
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 3
Damage & Durability Group – Pprime
Institute • Pprime Institute: > 500 persons – 3 scientific departments (Fluid
mechanics, Combustion, Energetics, Mechanical Engineering, Materials Science)
• Department of Physics & Mechanics of Materials, Damage & Durability Group
– Academic staff: 30 persons (11 CNRS + 19 ENSMA/UP)
– Staff: 18
– PhD students: 45
• FUNDINGS: ~1 M€ per year without salaries of permanent staff – 50 % industrial contracts
– 25 % european and national programs
– 25 % institutional grants
• Relations between microstucture, mechanical behavior and durabilty
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 4
HYCOMAT design approach
• Flexibility: Suitable for
mechanical testing on metals
as well as on polymers, in H2
as well as in CO2
• Servo-hydraulic load frame
• Dedicated metrology
• Maximum pressure: 40 MPa
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 5
HYCOMAT design approach (Cont’d)
• Pressure vessel and gas supply : design by TOP INDUSTRIE®
• Specific cells for : – Instron Servo hydraulic test
frame
– Power unit
– Outdoor Chiller
– Remote control for gas and test
– Outdoor gas storage and gas surpressors
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 6
Schematic overview
Surpressor H2
Surpressor CO2 Bouteille CO2
Bottle
H2 Bottle
N2 Bottle
flush
Pressure and
temperature
monitoring
Servo-
hydraulic
Machine
Cell
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 7
HYCOMAT : Safety
• Metallic structure for the test cell
• Separated command room /
Concrete wall
• H2 and CO2 detectors with 2 levels
of detection linked to :
– A double speed exhaust fan
– Interlocks (Vessel purge)
• Bursting discs
• Limited H2 volumes
• Water cooling flow and
temperature detectors
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 8
HYCOMAT capabilities
• Pressure : up to 400 Bars (40 MPa)
• Gas nature : H2, CO2, N2
• Temperature : up to 150°C
• Load cells:
– 25 kN (tension) pressure compensated internal cell Sixaxes®,
– Lower rod pressure compensated, no
piston effect due to internal pressure
– 25 kN external cell Instron®
• Actuator displacement (LVDT) : 20
mm (7,9 in)
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 9
HYCOMAT capabilities (Cont’d) • 2 front doors :
– 40 mm (15,7in) diameter window up
to 40 Bar
– 26 mm (10,2 in) diameter window up to 400 Bar
– 1 rear window 26mm up to 400 Bar
(10,2 in)
• Electrical connections for strain
gages and DCP
• Gas temperature measurement
(K-type TC)
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 10
HYCOMAT : capabilities (continued)
• Self alignment of the rods with ball joint
• Frequency : up to 20 Hz
• Test monitoring : Instron softwares :
– Wavematrix ® (Multi purpose software)
– Advanced Crack Growth ®
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 11
HYCOMAT : Gas Management • Automatic regulation for temperature and
pressure (PID control)
– Max H2 compression rate : 30 bar/minute
– Max H2 decompression rate : 50 bar/minute
• Manual purge of the vessel with inert gas (N2)
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 12
HYCOMAT: Test Specimens
• CT specimen (W= 40 mm,
B=8mm)
• Optical for observations
and measurements -
Questar®
• DCP crack measurement
• Strain gage for Crack
closure measurement
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 13
HYCOMAT: Test Specimens
• Cylindrical specimens
• Standard tension specimens (polymers)
• Strain measurement by patterning
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 14
HYCOMAT: Problems (solved or not)
Hardware Problems Responses
Gas compressor Valves & diaphragm
failures
Frequent changes
Water jacket Seals Explosive
decompression of seals
due to CO2
experiments
Anti extrusion ring
Rods Rod galling Anti extrusion ring
Internal load cell Residual deformation
of the compensation
socket
New design
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 15
Test procedures: tension &
compression test (polymers) • Specimen design : flat dumbbell
specimens (tension, cylindrical samples (compression)
• Metrology : crosshead displacement / optical extensometer
• Example of results : hydrogen influence on some key mechanical properties for gas high-density polyethylene for current gas networking (=> 3 MPa)
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 16
Test procedures: tension &
compression test (polymers) (Cont’d)
0
1
2
3
4
5
6
7
1,E+01 1,E+02 1,E+03 1,E+04 1,E+05 1,E+06 1,E+07 1,E+08
time (s)
log
ari
thm
ic s
train
(%
)
H2
air
fluage long-termelong-term creep
y = 17,072 x + 38,363
y = 20,227x + 28,214
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14
ligament (mm)
sp
ecif
ic w
ork
of
fractu
re (
KJ.m
-²)
0
50
100
150
200
250
300
350
400
0 2 4 6 8 10 12 14
displacement (mm)
forc
e (
N) l
t
W
L
F
rupture ductile (EWF)ductile fracture (Essential Work of Fracture)
0
5
10
15
20
25
30
35
0 0,05 0,1
logarithmic strain
Ca
uch
y s
tre
ss (
MP
a)
air
N2 (3 MPa)
H2 (3 MPa)
H2 (10 MPa)
tension
Limitations and
challenges: length /
extension ratio to be
compromised
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 17
Depressurization of a silicon rubber at 15 MPa/min after 1h-saturation at Psat = 24 MPa
Specimen design : flat and cylindrical samples (especially for
superimposed tension or compression)
Metrology : CCD camera => optical detection of cavitation onset (magnification of pictures)
current hydrostatic pressure value
Depressurization of a polyethyl acrylate rubber at 10 MPa/min after 1h-saturation at Psat = 12 MPa
primary / satellite
bubbles
star-shape
morphology
Test procedures: Explosive
Decompression Failure
../../../../../Documents and Settings/portable/Bureau/archives Graz/ESMC 2012/DYFP2012/talk/castagns/Local Settings/Temp/110421-13_10fps.avi../../../../../Documents and Settings/portable/Bureau/archives Graz/ESMC 2012/DYFP2012/talk/castagns/Local Settings/Temp/110421-13_10fps.avi
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 18
Test procedures: Explosive
Decompression Failure • Example of Results
• Limitations and challenges: experimental protocol limited to transparent rubbers, detection of early stages of cavitation (acoustic emission?)
Decompression rate (MPa/min)
variable hydrostatic pressure
at cavitation onset
Current pressure at cavitation(MPa)
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 19
Test procedures: dilatation test
(rubber)
V/V
0
Pre
ssu
re (
MP
a)
Time (min)
Specimen design : cylindrical and spherical samples
weak volume changes during saturation vs. large ones upon decompression
Metrology :
Example of results : silica filled NBR rubber
Limitations and challenges : large
temperature transients => calculation needed to extract the
volume change linked with gas
diffusion
two devices :
(a) (b)
holder
sample
reference
observation zone
0,2 mm
low resolution (lens 12.5–75 mm f1.8)
high resolution (Questar)
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 20
Test procedures: fatigue crack growth
in metals • Specimen design: Compact Tension
W=40mm B=8mm
• Advanced Crack Growth Instron®
software
• Crack length monitoring: potential drop
(DC) technique (Current intensity 1A)
• Crack growth calculation: ASTM E647
• Possibility to monitor the crack growth by
means of a long-distance microscope
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 21
Fatigue crack propagation: Results
10-9
10-8
10-7
10-6
10-5
10-4
4 5 6 7 8 9 10 20 30 40
15-5 PH
R=0.7
20Hz, room temperature
air LT
air TL
H2 0.09 MPa
H2 9MPa
da
/dN
(m
/cy
cle
)
K (MPa x m1/2
)
Influence of pressure
in a precipitation-
hardened martensitic
stainless steeel
→Sharp increase in
da/dN at 9 MPa H2
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 22
Fatigue crack propagation: Results
10-10
10-9
10-8
10-7
10-6
10-5
10-4
4 5 6 7 8 9 10 20 30 40
0.9 MPa / 20Hz
0.9 MPa / 0.2Hz
da
/dN
(m
/cy
cle
)
K (MPa x m1/2
)
mean curve 9MPa/20Hz
mean curve 0.09MPa/20Hz
Influence of frequency at low pressure → da/dN enhancement associated with a change in fracture mode
Meeting on Advancing Materials Testing in Hydrogen, Gas,Sandia National Laboraties, Livermore CA 23
Acknowledgements
• Fundings: ANR, FEDER…
• Co-workers: J. Jaravel, J.-C. Grandidier,
M. Morisset, Z. Sun…
