As mentioned earlier, strain gauges work on the principle of the conductor’s resistance which gives you the value of Gauge Factor by the formula: Now, in practice, the change in the strain of an object is a very small quantity which can only be measured using a Wheatstone Bridge. The more is the applied force, more is the strain and more is the increase in length of the wire. There can be different types of strain. Where are strain gauges used? It is used for measuring tension, force, torque and stresses in structures. The main advantage of a four-wire ohm circuit is that the lead wires do not affect the values because the voltage is detected directly across the strain gauge element. In the General purpose strain gauge section you will find the strain gauge patterns next to the part numbers so that you will be able to see the geometry of the strain gauge. The Gauge Factor of a Strain Gauge is the sensitivity coefficient of strain gauges and, is given by the formula: ΔR = Change in the resistance caused due to strain. Strain gauges are arguably one of the most important sensors that implement electrical measuring techniques when applied to the measurement of mechanical applications. 3. This was all about strain gauges and, if you have any further queries, do let us know in the comments below. Any change in the values of R1, R2, R3, and R4 will, therefore, change the output voltage. The strain gage is better suited for locations subjected to dripping or running water or which may submerge in water. It is a measure of internal pressure on an object whenever an external force acts on it. Strain Gauge Applications. This article presents an application of strain gauges in measurements of strain which occurs in charge air cooler during the thermal cycle test. For example, Yamuna Bridge in Allahabad-Naini is a 630 m cable-stayed bridge across river Yamuna. In applications where such complementary pairs of strain gauges can be bonded to the test specimen, it may be advantageous to make all four elements of the bridge active for even greater sensitivity. Strain gauges measure axial tension or compression with no impact on the rails. In practice, the “unit” for strain is called “strain” and the symbol e is used. In a mechanical strain gage, inaccuracies may result from lost motion such as backlash gear train, friction, temperature changes, and wear in the mechanism, slippage, or flexure or deflection of the components. However, if they do get affected by temperature changes, a thermistor is available for temperature corrections. Your email address will not be published. Let’s take an in-depth look at them. On the other hand, using a load cell needs the application of voltage to opposite nodes whereas to make use of a strain gauge, you need to arrange two to four strain gauges to experience opposite forces. A strain gauge depends on the electrical resistivity of any conductor. Instrumentation of bridges is done to verify design parameters, evaluate the performance of new technologies used in the construction of bridges, to verify and control the construction process and for subsequent performance monitoring. The strain is calculated by measuring the resonant frequency of the wire (an increase in tension increases the resonant frequency). There is the general query of what are strain gauges used for, and here is the answer for you. Strain GaugeStrain Gage measures the strain (amount of contraction as well as expansion caused by external forces) on any object. The gauge factor for common metallic foil is usually a little over 2. It is used to measure stress and strain on rails. This results in the effect of oxidation, moisture, environmental conditions and any ingress of water being completely eliminated. Strain gauges are bonded directly to structural load bearing components to measure stresses along load paths for wing deflection. The strain is a unitless quantity since the values in the numerator and denominator always have the same units. In case of an emergency, the strain gauges can generate a warning so maintenance can be done early to minimize the impact on rail traffic. In case of an emergency, the strain gauges can generate a warning so maintenance can be done early to minimize the impact on rail traffic. The strain gauge foil is glued on the material, which will be tested using a specially adapted glue for strain gauges. Calibration is done … Any basic strain gauge consists of an insulating flexible backing that supports a metallic foil pattern. An extra waterproofing is provided on the strain gage by a heat-shrinkable tube to prevent the ingress of water. The garage is designed to be used only for flat surfaces. Strain Gauges for Special Applications. Custom strain gauge technology is used in both critical and non-critical medical device and equipment applications, ranging from high-precision robotic surgery to patient scale weight distribution and medical pump pressure and flow measurements. The dummy gauge is then finally replaced by the actual strain gage and clamped in position by a pair of set screws on each block. | What are the applications of strain gauges? Quartz crystal strain gauges are also used in geotechnical applications. Application of unbounded metal strain gauge: Used in applications where there is a need for removable gauges. The gauge is attached to the object under stress using an adhesive. Strain gauges can measure the torque applied by a motor, turbine, or engine to fans, generators, wheels, or propellers. Any basic strain gauge consists of an insulating flexible backing that supports a metallic foil pattern. In such cases, the error depends on the gauge length and the gauge width. Similarly, when it is compressed, it gets shorter and broader, ultimately changing its resistance. The bridge is installed with many measurement channels that sense wind speed and strain on its cables. Applications of the strain gauge. etc. A strain gauge and method of making same for use in certain medical applications, such as sensing the occurrence of an apnea event. The Wheatstone Bridge circuit is given below. Strain gauge technology is used in the real-time monitoring of huge bridges, making the inspections precise. The strain is proportional to the square of the frequency and the readout unit is able to display this directly in strains. 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