This paper presents several amplifier circuits for use with strain gauges. In general, the gage factor for metal strain gages is about 2. Therefore, if we replace r4 in figure 3 with an active strain gauge, any changes in the strain gauge resistance will unbalance the bridge and produce a nonzero output voltage. Measurements, strain gauge sensor, measuring circuits. Alternatively, strain gauge conductors may be thin strips of the metallic film deposited on a nonconducting substrate material called the carrier. The exact value is specified on each strain gage package. Strain gages structure of strain gages there are many types of strain gages. Strain gauges are used to measure the strain of a material. I show the equation for output voltage and do an example calculation.
A short presentation on stress testing on printed circuit. But the loads can be different types and deflection can be. Usually, an instrument equipped with a bridge circuit and amplifier is used to measure the resistance change. Pdf strain gauges are used to measure the strain of a material. Most strain gauges are smaller than a postage stamp, and they look something like this. The circuits are inherently linear, produce four times the output of the standard wheatstone bridge, and can easily be. A strain gauge sensor is a thin waferlike device that can be attached to a variety of materials to measure applied strain. Measuring strain with strain gages national instruments. Fortunately, there are circuits available to do just that. Strain gauge working principle your electrical guide. When load is acted on a material, elongation or compression is happened.
Read the operation manual carefully before using bonding. Among them, a universal strain gage has a structure such that a gridshaped sensing element of thin metallic resistive foil 3 to 6m thick is put on a base of thin plastic film 15 to 16 m thick and is laminated with a thin film. For strain gauge measurement, the wheatstone bridge circuit. If the nominal resistance of the strain gauge is designated as rg, then the strain induced change in resistance. In experimental stress analysis, we apply a given load and then measure the strain on individual. A strain gage s electrical resistance varies in proportion to the amount of strain in the device.
Stress, strain, and strain gages penn state mechanical engineering. The metallic strain gage consists of a very fine wire or, more commonly, metallic foil arranged in a grid pattern. Below, the wheatstone bridge circuit will only be considered with respect to its application in. Hi friends, in this article, i am going to describe you strain gauge working principle, gauge factor and strain gauge load cell working. Lets briefly learn about stress and strain and strain gages. Karl hoffmann an introduction to stress analysis and transducer design using strain gauges. A strain gauge is a passive transducer, that converts mechanical displacement into the change of resistance. The factor k, also known as the gage factor, is a characteristic of the strain gage and has been checked experimentally 2. A short presentation on stress testing on printed circuit boards pcbs using strain gauges and a data acquisition system.
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