Strain Gauges and Accessories Nurgül Er nurguel.er@hbm.com www.hbm.com 19.03.2008, Folie 1 Hottinger Baldwin Messtechnik GmbH Nurgül Er
How to find the right strain gauge a wide range of of strain gauges 19.03.2008, Folie 2 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain gauge Cover carrier Measuring grid Leads Grid width Grid length 19.03.2008, Folie 3 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Applications of Strain Gauges Experimental Test s Exp. stress analysis Determining Residual Stress Analysis of loading (e.g. life-time analysis) Transducers for Force Torque Pressure Strain... Determining thermal stress 19.03.2008, Folie 4 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain gauges for transducer manufactures 19.03.2008, Folie 5 Hottinger Baldwin Messtechnik GmbH Nurgül Er
HBM-bending beam 19.03.2008, Folie 6 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain gauges for experimental tests 19.03.2008, Folie 7 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain gauges type designation 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 (example): LY11-6/120 19.03.2008, Folie 8 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Number of measuring grid and their relative position to each other L one measuring grid (linear strain gauges) D two measuring grid (direction: parallel) X two measuring grids (T-rosette (offset by 90 ) R V K M three measuring grids ( rosettes) four measuring grids (full bridge strain gauges) strain gauges chains for determining strain gradients full bridge strain gauges as diaphragm rosettes 19.03.2008, Folie 9 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types 19.03.2008, Folie 10 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types Linear strain gauge e.g. LY11-6/120 F Calculate the Young's Modulus on a tension / compression bar (Hooke s Law) measure strain ε calculate the mechanical stress σ = F A E = σ ε 19.03.2008, Folie 11 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types Dual-element linear strain gauge e.g. DY11-6/350 F Typical application: bending beam...... and the right strain gauge 19.03.2008, Folie 12 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types X-rosettes with 2 measuring grids e.g. XY11-6/120 Calculate the Young's Modulus and the Poisson s ratio on a tension bar measure strain ε calculate the mechanical stress σ = E = F A σ ε ν = ε ε q l 19.03.2008, Folie 13 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types X-rosettes with 2 measuring grids e.g. XY41-6/120 Example: torque transducer (torsions shaft with strain gauges mounted in the principal strain directions 19.03.2008, Folie 14 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types Rosettes with 3 measuring grids e.g. RY11-6/120 a c b (0º/45º/90º - rosette) σ 1/ 2 = E 1 ν ε a + ε 2 c ± 2 E ( 1+ ν) 2 ( ε ε ) + ( ε ε ) 2 a b c b 19.03.2008, Folie 15 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types Rosettes with 3 measuring grids e.g. RY11-6/120 (planar) 0º/45º/90º - rosettes 0º/60º/120º - rosettes determining a biaxial stress state with unknown principal directions 19.03.2008, Folie 16 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types 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 19.03.2008, Folie 17 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types Five 0 /60 /120 - rosette and one compensation strain gauges 19.03.2008, Folie 18 Hottinger Baldwin Messtechnik GmbH Nurgül Er
strain measurement on on a gear gear wheel 19.03.2008, Folie 19 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Typical strain gauges types Diaphragm rosette e.g. MY21-6/120 Example: pressure transducer with diaphragm elastic elements 19.03.2008, Folie 20 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain gauge series Y C carrier polyimide / measuring grid constantan foil 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 19.03.2008, Folie 21 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Strain gauge series Strain gauges for harsh environments embedded in plastic resin carrier polyimide / measuring grid constantan foil with 3m cable 19.03.2008, Folie 22 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Type and position of connections with leads (aprox. 30mm) with integrated solder tabs pre-wired strain gauges new 19.03.2008, Folie 23 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Type and position of connections no soldering at the measuring point cable length from 0.5m to 10m available 2, 3 and 4 wire options Teflon insulated wires prevent unwanted cable bonding new! pre-wired strain gauges 19.03.2008, Folie 24 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Temperature compensated strain gauges 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) 19.03.2008, Folie 25 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Temperature compensated strain gauges 1 for for ferritic steel α = 10,8 10,8 10 10-6 -6 // K 3 for for aluminum α = 23 23 10 10-6 -6 // K 5 for for austenitic steel α = 16 16 10 10-6 -6 // K 6* 6* for for quartz α = 0,5 0,5 10 10-6 -6 // K 7* 7* for for titanium/ gray cast iron α = 9 10 10-6 -6 // K 8* 8* for for plastic material α = 65 65 10 10-6 -6 // K 9* 9* for for molybdenum α = 5,4 5,4 10 10-6 -6 // K * not for all measuring grid lengths available 19.03.2008, Folie 26 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Self Temperature Compensation 19.03.2008, Folie 27 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Measuring grid length of an strain gauge strain gauges application F F not correct correct point values, measured with short strain gauges (measuring stress peaks) a strain gauges with a long measuring grid giving an average value with inhomogeneous material, e.g. concrete 19.03.2008, Folie 28 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Measuring grid length of an strain gauge strain gauges application F F correct The strain gauges forms an arithmetic mean of the strain conditions existing under its measuring grid. 19.03.2008, Folie 29 Hottinger Baldwin Messtechnik GmbH Nurgül Er
19.03.2008, Folie 30 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Resistance of the strain gauges Typically Values: 120Ω... preferred for stress analysis 350Ω 700Ω and 1000 Ω... preferred for transducer manufacturing... preferred in combination with telemetries systems and for the measurement on materials with low thermal conductivity The values have an historical origin, but they have proven useful and so they have been retained. 19.03.2008, Folie 31 Hottinger Baldwin Messtechnik GmbH Nurgül Er
HBM adhesive program 19.03.2008, Folie 32 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Adhesives 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 19.03.2008, Folie 33 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Cyano-acrylate Z70 single component adhesive, preferred for experimental stress analysis thin liquid very easy to handle temperature limits: contact pressure: curing period: -70 C up to +100 C (+120 C) thumb pressure 5 C: 10 minutes 20 C: 1 minutes 30 C: 0,5 minutes Humidity of more than 40% is necessary for curing 19.03.2008, Folie 34 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Cyano-acrylate Z70 19.03.2008, Folie 35 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Methacrylate mixture X60 two components adhesive, preferred for experimental stress analysis pasty, even on absorbent or uneven surfaces easy to handle (mixing to components) temperature limits: contact pressure: curing period: -200 C up to +60 C (+80 C) thumb pressure 0 C: 60 minutes 20 C: 10 minutes 35 C: 2 minutes 19.03.2008, Folie 36 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Methacrylate mixture X60 19.03.2008, Folie 37 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Epoxy resin X280 two components adhesive, preferred for experimental stress analysis for smooth and absorbent surfaces temperature limits: -70 C up to +200 C (+280 C) contact pressure: 0,05 2 N/mm 2 curing period: room temperature: 8 hours 95 C: 1 hour 19.03.2008, Folie 38 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Epoxy resin X280 19.03.2008, Folie 39 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Epoxy resin EP250 two components adhesive, preferred in the manufacture of transducer or for stress analyses in a lager temperature range pasty, even on absorbent or uneven surfaces temperature limits: -240 C up to +250 C (+315 C) contact pressure: 0,1 1,5 N/mm 2 curing period: 95 C: 16 hours 200 C: 0,5 hour 19.03.2008, Folie 40 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Epoxy resin EP250 19.03.2008, Folie 41 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Epoxy resin EP310S two components adhesive, preferred in the manufacture of 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/mm 2 curing period: 95 C: 5 hours 200 C: 0,5 hour 19.03.2008, Folie 42 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Epoxy resin EP310S 19.03.2008, Folie 43 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Protective coatings 19.03.2008, Folie 44 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Protective coatings it is recommended that strain gauges be protect against external effects (such as humidity, water, oil, mechanical influences) protect the polished metal of our application area against rust 19.03.2008, Folie 45 Hottinger Baldwin Messtechnik GmbH Nurgül Er
The cover should be put on immediately after bonding of the strain gauge. The application area must clean as for the adhesive. Cover a large area surrounding the applied gauges. If bonding the strain gauges in humid ambient conditions the applied gauge should be dried with a hot air gun or hair dryer. 19.03.2008, Folie 46 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Polyurethane paint 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 PU120 19.03.2008, Folie 47 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Nitrile rubber curing conditions: air drying at room temperature application method: brush application temperature range: -269 C... +150 C oil and petrol resistance, preferred in contact with liquid gases (excluding oxygen!) NG NG 150 150 19.03.2008, Folie 48 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Silicon Rubber curing conditions: 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 resistant very good mechanical protection SG SG 250 250 19.03.2008, Folie 49 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Permanently plastic putty 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 AK AK 22 22 19.03.2008, Folie 50 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Permanently plastic putty with aluminium foil curing conditions: - application method: pressing on by hand temperature range: -50 C... +170 C range of application and properties similar to AK22 ABM 75 75 19.03.2008, Folie 51 Hottinger Baldwin Messtechnik GmbH Nurgül Er
Accessories cleaning agent RMS1 cleaning pads solder terminals cables and wires 19.03.2008, Folie 52 Hottinger Baldwin Messtechnik GmbH Nurgül Er
thank you...... for your attention Hottinger Baldwin Messtechnik GmbH Im Tiefen See 45 D-64293 Darmstadt www.hbm.com Nurgül Er Technical Support Center Tel. 06151/803-8352 nurguel.er@hbm.com Dikkatiniz icin tesekkürler 19.03.2008, Folie 53 Hottinger Baldwin Messtechnik GmbH Nurgül Er