19.03.2008, Folie 1 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Nurgül Er
www.hbm.com
Strain Gauges and Accessories
19.03.2008, Folie 2 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
How to find the right strain gauge …
a wide range of strain gaugesa wide range of strain gauges
19.03.2008, Folie 3 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Leads
Cover
Measuring grid
Grid length
carrier
Gri
d w
idth
Strain gauge
19.03.2008, Folie 4 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Applications of Strain Gauges
Transducers for• Force•Torque• Pressure• Strain• ...
Experimental Test‘s• Exp. stress analysis• Determining Residual Stress • Analysis of loading
(e.g. life-time analysis)
• Determining thermal stress
19.03.2008, Folie 5 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Strain gauges for transducer manufactures Strain gauges for transducer manufactures
19.03.2008, Folie 6 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
HBM-bending beamHBM-bending beam
19.03.2008, Folie 7 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Strain gauges for experimental testsStrain gauges for experimental tests
19.03.2008, Folie 8 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
L Type Geometry of the strain gauges
Y Strain Gauges Series Material of the measuring grid and the carrier
1 Connections Leads / solder tabs / …
1 Temperature adjusted to thermal expansion variation coefficient α of an material
6 Measuring grid in mm
120 Measuring grid resistance in Ohm
Strain gauges type designation
Strain gauges type designation (example): LY11-6/120
19.03.2008, Folie 9 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
L one measuring grid (linear strain gauges)
D two measuring grid (direction: parallel)
X two measuring grids (T-rosette (offset by 90°)
R three measuring grids ( rosettes)
V four measuring grids (full bridge strain gauges)
K strain gauges chains for determining strain gradients
M full bridge strain gauges as diaphragm rosettes
Number of measuring grid and their relative position to each other
19.03.2008, Folie 10 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Typical strain gauges types
19.03.2008, Folie 11 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
εσ=E
Linear strain gauge e.g. LY11-6/120
Calculate the Young's Modulus on a tension / compression bar (Hooke‘s Law)
• measure strain ε• calculate the mechanical stress
AF=σ
Typical strain gauges types
F
19.03.2008, Folie 12 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Dual-element linear strain gauge e.g. DY11-6/350
F
Typical application: bending beam ...
... and the right strain gauge
Typical strain gauges types
19.03.2008, Folie 13 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
X-rosettes with 2 measuring grids e.g. XY11-6/120
l
q
εε
=ν
AF=σ
εσ=E
Typical strain gauges types
Calculate the Young's Modulus and the Poisson’s ratio on a tension bar
• measure strain ε
• calculate the mechanical stress
19.03.2008, Folie 14 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Typical strain gauges types
X-rosettes with 2 measuring grids e.g. XY41-6/120Example: torque transducer (torsions shaft with strain gauges mounted in the principal strain directions
19.03.2008, Folie 15 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
b
a
c
( ) ( ) ( )2bc
2ba
ca2/1
12
E21
E ε−ε+ε−ε⋅ν+
±ε+ε⋅ν−
=σ
(0º/45º/90º - rosette)
Typical strain gauges types
Rosettes with 3 measuring grids e.g. RY11-6/120
19.03.2008, Folie 16 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
determining a biaxial stress state with unknown principal directions
• 0º/45º/90º - rosettes • 0º/60º/120º - rosettes
Typical strain gauges types
Rosettes with 3 measuring grids e.g. RY11-6/120(planar)
19.03.2008, Folie 17 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Strain gauges chains, e.g. KY11-4/120
(for the determination of stress gradients)
Shapes of strain gauges chains:• measuring grids in a direction parallel to the chain‘s
longitudinal axis• measuring grids in a direction perpendicular to the
chain‘s longitudinal axis• measuring grids in a direction alternately parallel and
perpendicular to the chain‘s longitudinal axis• rosette chain
Typical strain gauges types
19.03.2008, Folie 18 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Five 0°/60°/120° - rosette and one compensation strain gauges
Typical strain gauges types
19.03.2008, Folie 19 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
strain measurement on a gear wheel
strain measurement on a gear wheel
19.03.2008, Folie 20 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Diaphragm rosette e.g. MY21-6/120Example: pressure transducer with diaphragm elastic elements
Typical strain gauges types
19.03.2008, Folie 21 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Y carrier polyimide / measuring grid constantan foil
C carrier polyimide / measuring grid CrNi special alloy
G carrier phenolic resin, glass fibre reinforced / measuring grid constantan foil
K carrier phenolic resin, glass fibre reinforced / measuring grid constantan foil, different creep adjustment
V carrier polyimide / measuring grid constantan foil, embedded in plastic resin
Strain gauge series
19.03.2008, Folie 22 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Strain gauges for harsh environments • embedded in plastic resin
• carrier polyimide / measuring grid constantan foil
• with 3m cable
Strain gauge series
19.03.2008, Folie 23 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
• with leads (aprox. 30mm)• with integrated solder tabs • pre-wired strain gauges
Type and position of connections
new
19.03.2008, Folie 24 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
pre-wired strain gaugesnew!
• no soldering at the measuringpoint
• cable length from 0.5m to 10mavailable
• 2, 3 and 4 wire options
• Teflon insulated wires preventunwanted cable bonding
Type and position of connections
19.03.2008, Folie 25 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Every strain gauge gives out a value when the temperature varies – without any mechanical load.
Cause:
• Work piece expansion with temperature • Change in specific resistance of strain gauge• Strain gauge grid expansion with temperature
HBM, Thomas Kleckers (Januar 1999)
Temperature compensated strain gauges
19.03.2008, Folie 26 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
1 for ferritic steel α = 10,8 ·10-6/ K
3 for aluminum α = 23 · 10-6/ K
5 for austenitic steel α = 16 · 10-6/ K
6* for quartz α = 0,5 ·10-6/ K
7* for titanium/ gray cast iron α = 9 ·10-6 / K
8* for plastic material α = 65 ·10-6/ K
9* for molybdenum α = 5,4 ·10-6/ K
1 for ferritic steel α = 10,8 ·10-6/ K
3 for aluminum α = 23 · 10-6/ K
5 for austenitic steel α = 16 · 10-6/ K
6* for quartz α = 0,5 ·10-6/ K
7* for titanium/ gray cast iron α = 9 ·10-6 / K
8* for plastic material α = 65 ·10-6/ K
9* for molybdenum α = 5,4 ·10-6/ K
* not for all measuring grid lengths available
Temperature compensated strain gauges
19.03.2008, Folie 27 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Self Temperature Compensation
19.03.2008, Folie 28 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Fstrain gauges application
a strain gauges with a long measuring grid giving an averagevalue with inhomogeneous material, e.g. concrete
point values, measured withshort strain gauges (measuringstress peaks)
F not correct
correct
Measuring grid length of an strain gauge
19.03.2008, Folie 29 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Fstrain gauges application
F
correct
The strain gauges forms an arithmetic mean of the strain conditions existing under its measuring grid.
Measuring grid length of an strain gauge
19.03.2008, Folie 30 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
19.03.2008, Folie 31 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Typically Values:
• 120Ω ... preferred for stress analysis
• 350Ω ... preferred for transducer manufacturing
• 700Ω ... preferred in combination with telemetriessystems and for the measurement on materialswith low thermal conductivity
and
1000 Ω
The values have an historical origin, but they have proven usefuland so they have been retained.
Resistance of the strain gauges
19.03.2008, Folie 32 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
HBM adhesive programHBM adhesive program
19.03.2008, Folie 33 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
cold curing adhesives
• preferred for experimental stress analysis
• easy to apply and require only little effort
• temperature range is smaller than hot curing adhesives
hot curing adhesives
• preferred in the manufacture of transducers (based on strain gauges)
• can be used where the measured object can be brought up to the curing temperature
• greater temperature range than cold curing adhesives
• contact pressure needed
Adhesives
19.03.2008, Folie 34 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
• single component adhesive, preferred for experimentalstress analysis
• thin liquid
• very easy to handle
• temperature limits: -70°C up to +100°C (+120°C)
• contact pressure: thumb pressure
• curing period: 5°C: 10 minutes20°C: 1 minutes30°C: 0,5 minutes
• Humidity of more than 40% is necessary for curing
Cyano-acrylate Z70
19.03.2008, Folie 35 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Cyano-acrylate Z70
19.03.2008, Folie 36 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
• two components adhesive, preferred for experimentalstress analysis
• pasty, even on absorbent or uneven surfaces
• easy to handle (mixing to components)
• temperature limits: -200°C up to +60°C (+80°C)
• contact pressure: thumb pressure
• curing period: 0°C: 60 minutes20°C: 10 minutes35°C: 2 minutes
Methacrylate mixture X60
19.03.2008, Folie 37 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Methacrylate mixture X60
19.03.2008, Folie 38 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
• two components adhesive, preferred for experimentalstress analysis
• for smooth and absorbent surfaces
• temperature limits: -70°C up to +200°C (+280°C)
• contact pressure: 0,05 … 2 N/mm2
• curing period: room temperature: 8 hours 95°C: 1 hour
Epoxy resin X280
19.03.2008, Folie 39 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Epoxy resin X280
19.03.2008, Folie 40 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
• two components adhesive, preferred in the manufactureof transducer or for stress analyses in a lager temperaturerange
• pasty, even on absorbent or uneven surfaces
• temperature limits: -240°C up to +250°C (+315°C)
• contact pressure: 0,1 … 1,5 N/mm2
• curing period: 95°C: 16 hours 200°C: 0,5 hour
Epoxy resin EP250
19.03.2008, Folie 41 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Epoxy resin EP250
19.03.2008, Folie 42 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
• two components adhesive, preferred in the manufactureof transducer or for stress analyses in a lager temperature range
• thin liquid, very easy to handle
• temperature limits: -270°C up to +260°C (+310°C)
• contact pressure: 0,1 … 0,5 N/mm2
• curing period: 95°C: 5 hours 200°C: 0,5 hour
Epoxy resin EP310S
19.03.2008, Folie 43 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Epoxy resin EP310S
19.03.2008, Folie 44 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Protective coatings
19.03.2008, Folie 45 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
• it is recommended that strain gauges be protectagainst external effects (such as humidity, water, oil,mechanical influences)
• protect the polished metal of our application areaagainst rust
Protective coatings
19.03.2008, Folie 46 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
The cover should be put on immediately after bonding of the strain gauge.
The application area must clean – as for the adhesive.
If bonding the strain gauges in humid ambient conditionsthe applied gauge should be dried with a hot air gun or hair dryer.
Cover a large area surrounding the applied gauges.
19.03.2008, Folie 47 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
• curing conditions: air drying (room temperature …+100°C)
• application method: brush application
• temperature range: -40°C ... +120°C
• suitable for light protection against touching and dust, for normal air humidity; likewise useful as insulating layer under other covers
Polyurethane paint
PU120PU120
19.03.2008, Folie 48 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Nitrile rubber
NG 150NG 150
• curing conditions: air drying at room temperature
• application method: brush application
• temperature range: -269°C ... +150°C
• oil and petrol resistance, preferred incontact with liquid gases (excludingoxygen!)
19.03.2008, Folie 49 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Silicon Rubber
SG 250SG 250
• curingconditions:air drying at room temperature
• transparent, solvent-free
• application method: tube application
• temperature range: -70°C ... +250°C
• suitable as protection against humidity and weather,against water at room temperature,limited oil resistantvery good mechanical protection
19.03.2008, Folie 50 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Permanently plastic putty
AK 22AK 22
• curing conditions: -
• application method:kneading on by hand
• temperature range: -50°C ... +170°C
• very good protection against humidity and weather,can be used under
19.03.2008, Folie 51 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
ABM 75ABM 75
• curing conditions: -
• application method:pressing on by hand
• temperature range:-50°C ... +170°C
• range of application andproperties similar to AK22
Permanently plastic putty with aluminium foil
19.03.2008, Folie 52 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
Accessories
• cleaning agent RMS1
• cleaning pads
• solder terminals
• cables and wires
• …
19.03.2008, Folie 53 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain Gauges and Accessories
thank you...
... for your attention
Dikkatiniz icin
tesekkürler…
Hottinger Baldwin Messtechnik GmbH
Im Tiefen See 45
D-64293 Darmstadt
www.hbm.com
Nurgül Er
Technical Support Center
Tel. 06151/803-8352