Strain Gauge
Strain Gage Data Acquisition Products
Strain Gage-based data acquisition product for portable and lab applications. PC-based systems, 2 to 64 channels, software programmable. Request a catalog today.
www.iotech.com
Strain Gauge Tension Load Cells
Great selection of tension and compression load cells.
www.rdpe.com
Strain Measurement
Order Sensors & More from Digikey Check Availability - Ship Same Day.
www.DigiKey.com
Low Cost Digital Load Cells with USB Out
10-10K Capacities+Low Profile+Rugged Load Cells. Priced from $99+s/h.
www.loadstarsensors.com
Omega Engineering, Inc., Strain Gauge
Omega Engineering, Inc. - leader in process measurement & control products. The one stop source for all your pressure product needs.
www.omega.com
Sti Gage
Buy high-precision STI gages now. Free specialized tech support.
www.threadcheck.com
Load Cell Signal Conditioning
Strain gage amplifiers several outputs, 0-10VDC, 4-20mA, RS232/485.
www.800loadcel.com
Fantastic Strain Gage Amplifiers
A world-leader in data acquisition products. Call 800.444.7644 now.
www.Dataforth.com
Strain Gauge Search
Free Technical Search Engine Search Thousands of Catalogs Today.
www.globalspec.com
Strain Gauges Available
Recorders, Amplifiers & More. Rent, Lease, Buy Used Equipment.
www.ElectroRent.com
Warning: mkdir() [function.mkdir]: Permission denied in /home/webs/affiliatelib2/CacheManager.php on line 12
Warning: mkdir() [function.mkdir]: No such file or directory in /home/webs/affiliatelib2/CacheManager.php on line 12
Warning: fopen(/home/templatecore2cache//*cluesnet.com/f2/f2a675fc89057b7ca2b50d50ae2abb8975a68298.tc2cache) [function.fopen]: failed to open stream: No such file or directory in /home/webs/affiliatelib2/CacheManager.php on line 130
Warning: fwrite(): supplied argument is not a valid stream resource in /home/webs/affiliatelib2/CacheManager.php on line 131
Warning: fclose(): supplied argument is not a valid stream resource in /home/webs/affiliatelib2/CacheManager.php on line 132
A strain gauge (alternatively: strain gage) is a device used to measure deformation (Strain (materials science)) of an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an Electrical insulation flexible backing which supports a metallic foil pattern. The gauge is attached to the object by a suitable adhesive, such as cyanoacrylatehttp://www.efunda.com/designstandards/sensors/strain_gages/strain_gage_selection_matl.cfm. As the object is deformed, the foil is deformed, causing its electrical resistance to change. This resistance change, usually measured using a Wheatstone bridge, is related to the strain by the quantity known as the gauge factor.
The gauge factor GF is defined as GF=\frac{\Delta R/R_G}{\epsilon} where R_G is the resistance of the undeformed gauge, \Delta R is the change in resistance caused by strain, and \epsilon is strain. For metallic foil gauges, the gauge factor is usually a little over 2http://www.efunda.com/designstandards/sensors/strain_gages/strain_gage_sensitivity.cfm. For a single active gauge and three dummy resistors, the output v from the bridge is v=\frac{BV \cdot GF \cdot \epsilon}4 where BV is the bridge excitation voltage.
Foil gauges typically have active areas of about 2-10 mm in size. With careful installation, the correct gauge, and the correct adhesive, strains up to at least 10% can be measured.
Gauges in practice under exaggerated bending.
Foil strain gauges are used in many situations. Different situations place different requirements on the gauge.
Gauges attached to a load cell would normally be expected to remain stable over a period of years, if not decades; whilst those used to measure the response in a dynamic experiment may only need remain attached to the object for a few days, be energized for less than an hour, and operate for less than a second.
Variations in temperature Variations in temperature will cause a multitude of effects. The object will change in size by thermal expansion, which will be detected as a strain by the gauge. The resistance of the gauge will change, and the resistance of the connecting wires will change.
Most strain gauges are made from a constantan alloyhttp://www.vishay.com/brands/measurements_group/guide/tn/tn505/505b.htm.Various constantan alloys and Karma alloys have been designed so that the temperature effects on the resistance of the strain gauge itself cancel out the resistance change of the gauge due to the thermal expansion of the object under test.Because different materials have different amounts of thermal expansion, self-temperature compensation (STC) requires selecting a particular alloy matched to the material of the object under test.
Even with strain gauges that are not self-temperature compensated (such as isoelastic alloy),using a Wheatstone bridge arrangement it is possible to compensate for temperature changes in the specimen under test and the strain gauge. To do this in a Wheatstone bridge made of four gauges, two gauges are attached to the specimen, and two are left unattached, unstrained, and at the same temperature as the specimen and the attached gauges http://www.efunda.com/designstandards/sensors/strain_gages/strain_gage_sensitivity.cfm.
Temperature effects on the lead wires can be cancelled by using a "3-wire bridge" or a "4-wire Ohm circuit"http://www.omega.com/literature/transactions/volume3/strain2.html (also called a "4-wire Kelvin connection").
Other gauge types For measurements of small strain, semiconductor strain gauges, so called Piezoresistive effect, are often preferred over foil gauges. A piezoresistor usually has a larger gauge factor than a foil gauge. Semiconductor gauges tend to be more expensive, more sensitive to temperature changes, and are more fragile than foil gauges.
In biological measurements, especially blood flow / tissue swelling, a variant called mercury-in-rubber strain gauge is used. This kind of strain gauge consists of a small amount of liquid mercury enclosed in a small rubber tube, which is applied around e.g. a toe or leg. Swelling of the body part results in stretching of the tube, making it both longer and thinner, which increases electrical resistance.
Mechanical Types Simple mechanical types (such as illustrated here) are used in civil engineering to measure movement of buildings, foundations, and other structures. In the illustrated example, the two halves of the device are rigidly attached to the foundation wall on opposite sides of the crack. The red reference lines are on the transparent half and the grid is on the opaque white half. Both vertical and horizontal movement can be monitored over time. In this picture, the crack can be seen to have widened by approximately 0.3mm (and no vertical movement) since the gauge was installed.
References See also
External links
- Strain Gauge Tutorial
- Fastest man on earth Strain gauges was the original topic of Murphy's law
- Strain Gauge->Computer Tutorial
- Applying Finite Element Analysis Methods to Strain Gage Design
- Strain Gage Knowledge base
- Strain Gage Calibration Software
Strain Gauges
BRIEF HISTORY 1856: Lord Kelvin first reported on a relationship between strain and the resistance of wire conductors. early 1930s: Charles Kearns made the first notable use of ...
Strain Gauge | Strain Gauges | Accelerometer | Pressure Transducer ...
Visit strainsense.co.uk for information on strain gauges, transducers, load cells, instrumentation and stress analysis.
What is a Strain Gauge - Strain Gauging Specialists, strain gages ...
PCM - Standard and Custom Load Cells, Load Pins, Force Bolts, Instrumentation and Systems, Load Cell Repair and Calibration, Load Cell and a Strain Gauge Bonding Service. ...
Definition: strain gauge from Online Medical Dictionary
The Online Medical Dictionary is a searchable dictionary of definitions from medicine, science and technology.
Strain gauge - Wikipedia, the free encyclopedia
A strain gauge (alternatively: strain gage) is a device used to measure the strain of an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of ...
Sensor Technology- Torque Measurement, Rotary Sensors, InLine ...
Torque Unit Converter TorqSense RWT310/320 Series TorqSense RWT330/340 Series E200 Optical Series E100 Base Mounted Strain Gauge Series E100 In-Line Strain Gauge Series TorqView Software ...
strain gauge
Mozilla/4.5 [en] (Win98; I) [Netscape] ... When something is stressed its length changes. change in length/original length = strain (e)
Strain Gauges and the Wheatstone Bridge experiment
Strain Gauges Wheatstone Bridge teaching experiment ... Object. Use strain gauges to measure the strain in a loaded steel cantilever.
Strain Gauge Products -Vishay Nobel U.K.
Vishay Nobel U.K. -Formerly Nobel Systems, supply stress analysis and transducer strain gauges from Vishay BLH for force, pressure and thrust measurement plus accessories including ...
Intrinsically Safe Strain Gauge Meter
INTRINSICALLY SAFE STRAIN METER The Intrinsically Safe Strain Meter is designed to meet the requirements of EN50014 and EN50020, and approved to operate reliably in potentially ...