Bonded foil strain gauges can be as small as 16 mm2 and have strain sensitivity or gauge factor of 2. %PDF-1.3 %���� Like the sensitivity of a bridge reflects how much the magnitude its full-scale output As a result change in length of material is 2.5 cm. The gauge factor is defined as: = / / = / = + + / where Îµ = strain = / = absolute change in length = original length; Î½ = Poisson's ratio Ï = resistivity ÎR = change in strain gauge resistance due axial strain and lateral strain another way to express strain is as percent strain, which is x 100. Underneath are numerical founded on strain formula which might be useful for you. known, strain measurement will allow calculation of stress. This is the quantity measured by the strain gauge transducer that you wish to convert to a millivolt output reading. 1. Generally, the resistance of a strain â¦ 134 0 obj << /Linearized 1 /O 136 /H [ 768 813 ] /L 273411 /E 74038 /N 27 /T 270612 >> endobj xref 134 16 0000000016 00000 n If measurements have to be conducted at higher temperatures, high-temperature strain gauges that work according to different â¦ A strain gauge (also spelled strain gage) is a device used to measure strain on an object. NOTE: Corrections may be necessary for transverse sensitivity. The stress and strain at the center of the beam is zero. At 10V, the excitation, offset, and gain trimming are all fixed and no adjustments can be made. 0000002380 00000 n A strain gage with a GF of 2 exhibits a change in electrical resistance of only 2 (500 x 10 -6) = 0.1%. The strain gauge (SG) simulators models 9405 allow rapid and easy calibration of measuring chains consisting of, for example, a load sensor, a connecting lead and indicator. Strain Gauge or Strain Gage was invented in 1938 by Edward E. Simmons and Arthur C. Ruge. In a uniaxial stress condition, it is sufficient to detect the strain with a single measuring grid. SHEARING STRAIN Another type of strain, called SHEARING â¦ o Specifically, when force is applied to the wire, its length L increases by a small increment L, while its cross-sectional area A decreases, as sketched. Strain Gauge Theory. 10/15/2016 3 Strain Gauge 1-Metallic strain gauges (the resistance of which changes in response to the change in the mechanical dimensions caused by the strain). The stress analysis with strain gauge is used to determine the stress in a single component. A good quality, although fairly expensive gauge is the Carlson strain meter shown in Figure 16.20; like the ers gauge, it operates on the principle that a change in resistance of a coil of elastic steel wire is proportional to the strain imposed by movement in concrete. x[A����v����]�K�0�}p "!�|l�.�c�P��ع���Ֆ�1��C>�j=� J�C�Mbr�{Պ���Hw��iB������7�����z=U� +�~�޸���qL8^�����t�wwj1��7_@.6:��q�Al-౭�E/k�i�;.�+ȶR�a�|D�_��)�g����Q�&�jFr.�\��y�K��@1L�9_ A�Ð The gauge is attached to the object by a suitable adhesive, such as cyanoacrylate. Rosette Strain Gauge … Example Calculation: If you measured 3000 with a 120Î© metallic strain gauge (GF=2.00), its corresponding fractional change in resistance R/R = 2.00*3000*10-6 = 0.006, implying that this 120Î© gauge changed its resistance by only 0.6% or 0.72Î©. 0000002657 00000 n 0000001559 00000 n Answer: Known: x (Change in length) = 2 mm, L (Original length) = 5 cm = 2 x 10-3 /5 x 10-2 A strain is a normalized measure of deformation representing the displacement between particles in the body relative to a reference length. Stress is the ratio of applied force F to a cross section area - defined as "force per unit area". ,�c���^��̴b. The strain gauges are based on the resistive properties of the metal. 19, No. The bridge output voltage is amplified with a linear gain of 100 and the amplified voltage is measured as 0.24 V. A strain is a normalized measure of deformation representing the displacement between particles in the body relative to a reference length. Therefore, the strain has little effect on the second gauge, called the dummy gauge. The direction of the mechanical stress is required in this case, as known. Geotechnical News Magazine, Vol. Thus using four active gauges (‘arms’) provides benefits in precision (and accuracy) when measuring small strains. Strain is the geometrical measure of deformation representing the relative displacement between particles in the material body. All measuring amplifiers and displays suitable for SG sensors can be connected, checked and calibrated. And lastly (though there are many other less common load cell set ups), there is a strain gauge load cell, which is a mechanical element of which the force is being sensed by the deformation of a (or several) strain gaugeâ¦ Wheatstone Bridge for Strain Measurement. It is one of the significant sensors used in the geotechnical field to measure the amount of strain on any structure (Dams, Buildings, Nuclear Plants, â¦ Example Calculation: If you measured 3000 with a 120Ω metallic strain gauge (GF=2.00), its corresponding fractional change in resistance R/R = 2.00*3000*10-6 = 0.006, implying that this 120Ω gauge changed its resistance by only 0.6% or 0.72Ω. 0000001581 00000 n 0000033468 00000 n For example, many generic strain gauge-signal conditioner modules can be set to a fixed 3-mV/V rating. Strain gauges consist of a flat length of metal wire, metal foil strip, or a strip of semiconductor material which can be stuck onto surfaces like a postage stamp. If a strain gage is bonded on a surface of a pillar which receives uniform load from one direction and the gage axis is aligned to the direction, stress Ï is calculated by the following equation : Stress â¦ 0000003339 00000 n In the calibration sheet below Longitudinal strain gauges on front at R1 & R4 will respond to compression-tension: with gain VEX*G*ÎR/2R. However, since strain is an invisible infinitesimal phenomenon, the resistance change caused by strain is extremely small. For example, in full bridge configuration, you can use 4 strain gauges in one bridge to measure one force. For example, let’s calculate the resistance change on a strain gage caused by 1000 x10–6 strain. Basics of strain gauges - Theory and calculating change in resistance as a function of strain. Strain gauge load cell weighing systems convert weights into analog output signals that can be further conditioned to indicate weight in digital meters and control systems. The supply voltage source is loaded realistically by the simulator. Examples of Strain-gage Measurement of Tensile/Compressive Stress Quarter-bridge System (1-gage System) See the figure below. This makes the measurements have more resolution (precision) and make it more linear. Rosette Strain Gauge Calculation VI by: ExamplePrograms â02-27-2008 06:00 PM. Strain can be measured using various types of devices classified depending upon their principle of operation. and strain through the cross-section in the direction parallel to the load. Example code from the Example Code Exchange in the NI Community is â¦ 0000002421 00000 n Again, such a figure is precise if the bridge The same gauges connected as diametrically opposite arms of a full bridge (with temperature compensation dummy gauges in the other two arms) would measure the net axial strain â¦ (âforce, pressure, tension, weight, etc.â) (Omega). The torque requirements of a gear box are normally drilled down from the application, where the gearbox is coupled. The maximum range is about 300°C to 400°C. Temperature limits of strain gauges and adhesives. Strain meters/ digitizers have typical resolution/ precision of about ±1 x 10^-6 mm/mm (±0.0005 mV/V bridge output). Application example 1: Compensation of thermal output when using a temperature-integrated strain gauge Thermal output of strain gauge is automatically compensated when measuring a temperature-integrated strain gauge … Strain gauges have been around for almost 80 years and continue to be key assets for measuring fatigue and testing materials for productivity and safety reasons. Frequently Asked Questions. E. STRAIN GAGES. j�����39J�ޔ�h�\3�N��p�97�����ݹ9�ٕ�bG eq��+�F���ߧ��͛�`��}[� development, an example of a rectangular strain gage rosette mounted on a beverage can for the purpose of determining the pressure internal to the soda can is used. In the stress analysis with strain gauges usually bridge circuits are used with only one active measurement grid. These strain gauges are used to measure the normal strain in those three directions. Formula For Strain. Strain rosette can be defined as the arrangement of strain gauges in three arbitrary directions. However, since strain is an invisible infinitesimal phenomenon, the resistance change caused by strain is extremely small. H�b```# �� Ȁ �l@���1�A�Q�A *ܽ��?C��@N �a!�@�+��>+8?ؿC���hΞ&mF� �9xp�q�0�aq���2���t�ok��#�֔0�ɒ�����Hy)lf���4\$�spX��c~ե�{��L0gV���}q�뒢��i����hx��ji3��9`:a�����D���zm��My���������D� ��vOP?Y��c��c��-���t��d L:��xX��I��9�\�鱁��O�U�Vn�R��0|�T��l;������Z����f���3vq)K��sz�k��.���Uw�� �{�@���E�-=s3 possible by the use of Complete Compensation Method of Strain. Strain o In the above simple example, the wire stretches vertically as a result of the force. Depending on the arrangement of strain gauges, strain rosettes are classified in to:- 1. conversion of mechanical strain to a corresponding electrical resistance change. The length of the wire is 25 mm or less. But how do I calculate material stress from strain? However, this VI can also be run in LabVIEW as a stand-alone VI that acts as a simple strain calculator. By using two strain gauges in the bridge, the effect of temperature can be avoided. Upon stretching, the metal material loses or increases its electrical resistance.The strain gauge foil is glued on the material, which will be tested using a specially adapted glue for strain gauges. Enter the maximum quantity that the strain gauge transducer will measure. The strain is the measure of how much distortion has befallen on the body compared to its initial shape due to the action of the force. A strain gage is an instrument used to calculate the strain acting upon an object and converts changes of electrical resistance into desired values, i.e. There is a clever solution to finding shear strain. Delta strain gauge â¦ So for the setup in Figure 4, strain gage G1 should read an equal and opposite strain to that of G2. 1, pp 35 - 38. So for the setup in Figure 4, strain gage G1 should read an equal and opposite strain to that of G2. 4. It is denoted by ϵ. Strain measures how much a given deformation differs locally from a rigid-body deformation. 0000000768 00000 n Fellenius, B. H., 2001. Compute the strain. WHERE: p,q = Principal strains p,q = Principal stresses p,q = the acute angle from the axis of gage 1 to the nearest principal axis. A typical example for a strain gauge of the type used for measuring force in industrial environments is 15 mV/V at 1000 pounds. The strain gage nomenclature used in Figure 4 There are three sorts of strain �� Gauge factor (GF) or strain factor of a strain gauge is the ratio of relative change in electrical resistance R, to the mechanical strain Îµ. For a given strain, the resistance change may be only a â¦ However, full-bridge type I requires three more strain … strain gauge transducers usually employ four strain gauge â¦ Example \(\PageIndex{2}\): Stretching a Rod. If a strain gage is bonded on a surface of a pillar which receives uniform load from one direction and the gage axis is aligned to the direction, stress σ is calculated by the following equation : Stress (σ) = ε 0 ・E the gauge factor of the strain gauge, which is given by the manufacturer as 2.012. However, there is no gage that is capable of measuring shear strain. strain gauge transducers usually employ four strain gauge elements that are electrically connected to form a Wheatstone bridge circuit. For example, if a positive (tensile) strain is applied to gauges 1 and 3, and a negative (compressive) strain to gauges 2 and 4, the total strain would be 4 times the strain on one gauge. The strain gauge forms one leg of a Wheatstone bridge, which is connected to a differential amplifier. For example, two gauges affixed to opposite faces of the component and connected on the same side of a half bridge would measure bending while cancelling the effect of any net axial strain. Consider a tie bar of 3 meters long which is 8cm wide and 16cm deep. 0000001739 00000 n The name bonded gauge is gâ¦ P�D[�� The HX711 and Load cell are used in building a weighing … Code to add this calci to your website Here we can calculate Strain, Length, Change in Length. Gauge factor (GF) or strain factor of a strain gauge â¦ 0000003109 00000 n Full Range. 0000004072 00000 n ���zV�J�� ���\��wT��Y�;ff�夤�x�M ���_�3����u��ϟ��?�hd%��h�1�氆��ހ6�u�/�Z5�!�ss:��iV������0�D(jP�㘀/��[^���P�C��0�pb(��C�4E)z�I�r �lEG���.�� �>��LE w\$ �a�b��H�Yy��c������ӺIs�� Basics of strain gauges - Theory and calculating change in resistance as a function of strain. For example, Figure 5 illustrates a strain gauge configuration where one gauge is active (R G + âR), and a second gauge is placed transverse to the applied strain. A strain gauges conductors are very thin: if made of round wire, about 1/1000 inch in diameter. Download The figure shows the example of a wire-wound strain gauges. In practice, the range of strain gauge resistance is from 30 ohms to 3000 ohms. �]�fRZ�B P��d�S�U �Ħ`�4�鹔!���3�f�˔ʠ�a��;w'�t�"N�6�rF ����1H��t&u�Rƭ{T~3����Li�F���f���2�Q8Ȱ7����.�!c(�.F���H����E�@�` endstream endobj 149 0 obj 697 endobj 136 0 obj << /Type /Page /Parent 128 0 R /Resources 137 0 R /Contents 141 0 R /MediaBox [ 0 0 612 792 ] /CropBox [ 0 0 612 792 ] /Rotate 0 >> endobj 137 0 obj << /ProcSet [ /PDF /Text ] /Font << /TT2 138 0 R /TT4 143 0 R >> /ExtGState << /GS1 144 0 R >> /ColorSpace << /Cs6 139 0 R >> >> endobj 138 0 obj << /Type /Font /Subtype /TrueType /FirstChar 32 /LastChar 121 /Widths [ 250 0 0 0 0 0 0 0 0 0 0 0 0 333 250 278 0 500 500 500 500 500 500 500 0 0 333 0 0 0 0 0 0 722 667 722 722 667 611 778 778 389 0 0 667 944 0 778 611 778 722 556 667 722 722 1000 0 0 0 333 0 333 0 0 0 500 556 444 556 444 333 500 556 278 0 0 278 833 556 500 556 0 444 389 333 556 500 722 500 500 ] /Encoding /WinAnsiEncoding /BaseFont /NDGFDG+TimesNewRoman,Bold /FontDescriptor 140 0 R >> endobj 139 0 obj [ /ICCBased 146 0 R ] endobj 140 0 obj << /Type /FontDescriptor /Ascent 891 /CapHeight 656 /Descent -216 /Flags 34 /FontBBox [ -558 -307 2000 1026 ] /FontName /NDGFDG+TimesNewRoman,Bold /ItalicAngle 0 /StemV 160 /XHeight 0 /FontFile2 145 0 R >> endobj 141 0 obj << /Length 377 /Filter /FlateDecode >> stream H�\UtMW���Ϲ7�)�xݸI� �j�7�1�E�\$��h�zu�zL��\A=�)ӆP�XX���23�3*�̗�5m�����}����}�)ހFڈ_FEO:f3�����Yy��%��Iݳ� Y��:2 In a uniaxial stress condition, it is sufficient to detect the strain with a single measuring grid. â&P?DAAÓ¬B¢lëßïÌ,»Ë¥x1Õîrçóû÷q`¥! :INxeÄ07³Éà>\$~ððc¢åO?\^](1%5Nãj_ub>^¼ÄÏ7óÁKý%´¸¼TJáv,´üµÔF\$.ï'çC­ìéåç°BoÅPçcdsÇ÷Å³hU&áJ)âêlââìÕÄgÁfh6%Ü\02yÜÞ .¿¬Nf7Ñ¶Otêí\Ö¸°=ÁO¸  (DA)iâºoWj;48_©@¨{NW!ÖËëbMQ°¿­¤´BíZ\§ÚtÍ¦¸H]í/v{#­ÝÏNG. Figure 4 illustrates the orientation of the rectangular strain gage rosette with respect to the major axes of the soda can. and strain through the cross-section in the direction parallel to the load. This article will tell you how to measure torque requirements for gear box. ݆Xh����▩ۃ!�&�����s`K�DS��N>� �! trailer << /Size 150 /Info 132 0 R /Root 135 0 R /Prev 270601 /ID[<123d3a3d7a4c316938654460a37b17da><461cc39a0cf52affe4a085f56062c45b>] >> startxref 0 %%EOF 135 0 obj << /Type /Catalog /Pages 129 0 R /Metadata 133 0 R /PageLabels 127 0 R >> endobj 148 0 obj << /S 739 /L 876 /Filter /FlateDecode /Length 149 0 R >> stream From Strain Measurements to Load in an Instrumented Pile Bengt H. Fellenius Introduction More and more, our profession is realizing that a conventional static loading test on a pile provides â¦ Strain is defined as the ratio of increase in length to original length. How can I select the right strain gauge and install it correctly? Pure torsion loading and shearing strain CASE 4: BIAXIAL STATE OF STRESS a) If less is known about the state of stress, but directions of principal As described to this point, strain is fractional change in length and is directly measurable. Problem 1: An elastic band of length 5 cm is stretched such that its length increases by 2 mm. I just want to know how to connect three wired strain gauge (TML strain gauge, type FLA-5-11, Tokyo Sokki Kenkyujo Co., Ltd.) with Agilent 34901a 20 channels multiplexer. To â¦ conversion of mechanical strain to a corresponding electrical resistance change. For the same strain gage, changing the bridge configuration can improve its sensitivity to strain. For example, suppose a test specimen undergoes a strain of 500 me. endstream endobj 142 0 obj << /Type /FontDescriptor /Ascent 891 /CapHeight 656 /Descent -216 /Flags 34 /FontBBox [ -568 -307 2000 1007 ] /FontName /NDGFGK+TimesNewRoman /ItalicAngle 0 /StemV 94 /XHeight 0 /FontFile2 147 0 R >> endobj 143 0 obj << /Type /Font /Subtype /TrueType /FirstChar 32 /LastChar 181 /Widths [ 250 0 0 500 0 833 0 0 333 333 0 0 250 333 250 278 500 500 500 500 500 500 500 500 500 500 278 0 0 0 0 0 0 722 667 667 722 611 556 722 722 333 389 722 611 889 722 722 556 722 667 556 611 722 722 944 722 722 0 333 0 333 0 500 0 444 500 444 500 444 333 500 500 278 278 500 278 778 500 500 500 500 333 389 278 500 500 722 500 500 444 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 333 444 444 0 500 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 549 0 0 0 536 ] /Encoding /WinAnsiEncoding /BaseFont /NDGFGK+TimesNewRoman /FontDescriptor 142 0 R >> endobj 144 0 obj << /Type /ExtGState /SA false /SM 0.02 /TR2 /Default >> endobj 145 0 obj << /Filter /FlateDecode /Length 26626 /Length1 46192 >> stream The strain must be calculated using the original voltage change, so the gain from the op-amp must divide into the output voltages. Strain gauge and rosettes Introduction A strain gauge is a device which is used to measure strain (deformation) on an object subjected to forces. Measuring strain gauge circuits In order to measure strain with a bonded resistance strain gauge, it must be connected to an electric circuit that is capable of measuring the minute changes in resistance corresponding to strain. Strain Gauge Theory. When the wire, foil, strip or semiconductor is stretched, its resistance R changes. Given that a strain gauge is a resistor, … Article: Temperature compensation of strain gauge ¼-bridges with example calculation Understand the ¼-bridge compensation calculation step by step based on a practical example. Experimental method: During the operation of strain gaging and calibration of shafts data should be recorded for torque vs. output mV/V (see example of data below). An excitation adjustment lets users set the excitation voltage to the maximum allowed by the manufacturer, which maximizes the bridge's output. A strain gauge is a device that measures electrical resistance changes in response to, and proportional of, strain (or pressure or force or whatever you so desire to call it) applied to the device. The outputs of this VI are two principal strains, minimum and maximum, the two angles to those strains, the maximum shear strain and the angle to that shear strain. Strain gauge is a device used to measure strain on an object. The strain gauges are based on the resistive properties of the metal. ME 410 â Experiment 5: Stress Analysis by Using Strain Gages Theory Page 6 / 15 Ï=Ï = Î³xy max xyG (3) where Î³=Îµxy 2 ( Îµ is the strain measured strain from the gage) Fig. Figure 1.14(a) shows the basic form of an electrical resistance strain gauge. Some of them are as follows: 1. This clip shows how a simple bridge circuit works. For example: 0.005 inch/inch = 5000 =0.5%. In the stress analysis with strain gauges usually bridge circuits are used with only one active measurement grid. Description: HX711 and Arduino-This tutorial is based on the HX711 breakout board, Arduino Uno and a Load cell or Strain gauge.This tutorial explains step by step how to use the load cell or Strain gauge with the HX711 breakout board and how to write a basic Arduino Uno program to access the values and print them on the Serial monitor. The latter form of the strain gauge is represented in the previous illustration. Strain measures how much a given deformation differs locally from a rigid-body deformation. Specifically, the Gauge Factor is the ratio of the fractional change in resistance to the strain ( GF = (êR / R) / (êL / L) = (êR / R) / e ). That is, at exactly 1000 pounds applied force (either compressive or tensile), the bridge will be unbalanced by 15 millivolts for every volt of excitation voltage. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. H���_O�0����q�Q���������� Stress analysis with strain gauges. Mechanical type, In order to compensate for such changes (which the instrumentation would interpret as mechanical strain) the gauge itself should be chosen, if â¦ Statement. Strain Formula is articulated as, Where, Change in dimension is x, The original dimension is L. Types of Strain. Upon stretching, the metal material loses or increases its electrical resistance.The strain gauge foil is glued on the material, which will be tested using a specially adapted glue for strain gauges. Measuring strain gauge circuits In order to measure strain with a bonded resistance strain gauge, it must be connected to an electric circuit that is capable of measuring the minute changes in resistance corresponding to strain. For example, the full-bridge type I configuration is four times more sensitive than the quarter-bridge type I configuration. Strain gauges need to be part of a bridge circuit. A 2.0-m-long steel rod has a cross-sectional area of 0.30 cm 2.The rod is a part of a vertical support that holds a heavy 550-kg … Stress, strain & youngâs modulus of elastictcity calculation can be easily explain through example. 0000001891 00000 n Strain Gauge Load Cells. Like the sensitivity of a bridge reflects how much the magnitude its full-scale output 1. tensile stress- stress that tends to stretch or lengthen the material - acts normal to the stressed area 2. compressive stress- stress that tends to compress or shorten the material - acts normal to the stressed area 3. shearing stress- stress â¦ The electric resistance strain gage was first reported in 1856 by Lord Kelvin, who used copper and iron wires Alternatively, strain gauge conductors may be thin strips of the metallic film deposited on a nonconducting substrate material called the carrier. The strain gauge is used to determine the amount of strain. Rectangular strain gauge rosette 2. A second op-amp is then used to both amplify and apply a low-pass filter to the measurement signal. Strain is the geometrical measure of deformation representing the relative displacement between particles in the material body. See Figure C. If total strain is four times the strain on one gauge, this means that the output will be four times larger. 0000030790 00000 n Examples of Strain-gage Measurement of Tensile/Compressive Stress Quarter-bridge System (1-gage System) See the figure below. For example, letâs calculate the resistance change on a strain gage caused by 1000 x10â6 strain. Strain Gage Rosette at Arbitrary Angles : Since a single gage can only measure the strain in only a single direction, two gages are needed to determine strain in the ε x and ε y. Find the stress, strain & youngâs modulus of â¦ The two methods for finding out the torque at the gearbox input and output shaft are: Strain gauge method and Calculation method. The temperature range of foil strain gauges is limited by the materials that are used. 0000003993 00000 n For a 120 Î© gage, this is a change of only 0.12 Î©. Frequently Asked Questions. 0000000671 00000 n When positive, the direction is the same as that of the gage numbering and, when negative, opposite. Strain gauge is a device used to measure strain on an object. Strain gauge load cells are by far the most common type of load cell-based weighing system in 2010. Millivolt Output Parameters Supply Voltage (V) This is the excitation voltage in volts applied to the wheatstone bridge strain gauge circuit. It is subjected to a pulling force of 4000 KN. The inputs to this VI are three strain readings and three angles from a Rosette. Strain Solved Examples. ���1c�ױ9���b�Hd�c����cS�,���s��5y�hZ����r�S�5&�,``��h``��``��1XC#::@W(�����e*��u�8���bP���� RQ��(l��-�� )A�A.�0�X\ ���: The active gauge R 1 is remote from the instrumentation, and both it and its associated wiring are subject to resistance changes brought about by any variation in temperature. The stress and strain at the center of the beam is zero. "X�xW2�R��d�:�uA`%�4�g��!� I IQ@�( c�\n{шVA��B��n!� Example-6.1: + - V 1 R R R V 2 F F Strain measurement system is shown in the figure. Therefore, the strain on the top and bottom of the beam are equal, opposite, and maximum. Here we can calculate Strain, Length, Change in Length. Therefore, the strain on the top and bottom of the beam are equal, opposite, and maximum. Longitudinal strain gauges on front at R1 & R2: will respond to bending: gain will be VEX*G*ÎR/2R. Strain of this type is also often referred to as normal strain. comes with the manufacture of each strain gage will specify the specific gage factor value. From strain measurements to load in an instrumented pile. Wire wound gauges are made of round wire of copper-nickel, chrome-nickel, or nickel-iron alloys about 0.0064 cm diameter. Most commonly for measuring the strain, strain gages are used whose electrical resistance varies with proportionate strain in the device. The Gauge Factor of a strain gauge is a characteristic transfer coefficient that relates the resistance change in a strain gauge to the actual strain that produced it. Suppose R1 is longitudinal front and R2 is longitudinal back side: Now best response for bending.