The electrical resistance strain gage discussed in this chapter is basically a piece of very thin foil or fine. Institute of technology ruge at mit independently discovered in 1938 that. You can also download the pdf of the book practical hints for the installation of strain gages by the same author. Treatise on mechanics long played the role of a standard textbook. Measuring strain with strain gages national instruments. Briefly summarized, the measurement procedure involves six basic steps. The classic, definitive work on strain gauge measurement.
Still symbols normal stress shear stress strain normal microstrain x 10 6 shear strain e modulus of elasticity or youngs modulus poisson ratio gf gage factor rg gage resistance in ohms kt transverse sensitivity ratio l length l change in length rg change in gage resistance due to strain % gf % change in gage factor. Principle of strain gages the strain gage is tightly bonded to a measuring object so that the sensing element metallic resistive foil may elongate or contract according to the strain borne by the measuring object. R3 is an active strain gage compensating for poissons effect this configuration is commonly confused with the quarterbridge type ii configuration, but type i has an active r3 element that is bonded to the strain specimen. As their name indicates they are used for the measurement of strain. Lets briefly learn about stress and strain and strain gages. For example, the piezoresistive strain gauge is a semiconductor device whose resistance varies nonlinearly with strain. Pdf design and construction of a strain gauge researchgate. However, at the present scientific level, there is no technology which. The strain gauge while there are several methods of measuring strain, the most common is with a strain gauge, a device whose electrical resistance varies in proportion to the amount of strain in the device.
An introduction to stress analysis and transducer design using. Introduction to strain gages instruments techno test inc. This method is simple, fast, and requires no manual adjustments. Measurement of residual stresses by the holedrilling. Terms and units of measurement used in strain gage technology 17. An introduction to measurements using strain gauges. It is also a major component used in the manufacturing of measurement transducers. This book is a profound compendium on strain gages and their application in materials science and all fields of engineering. Bonded foil strain gages strain gage arrangements the strain gage is one of the important electrical measurement technique applied to the measurement of mechanical quantities. A special three or six element strain gage rosette is installed on the test part at the point where residual.
Technology and practical use of strain gages with particular. Karl hoffmann an introduction to stress analysis and transducer design using strain gauges. When bearing mechanical elongation or contraction, most metals undergo a change in electric resistance. Strain gauge installation how to position strain gauges to monitor bending, axial, shear, and torsional loads inertia i are functions of the specimens crosssectional geometry. All the theories related t o design a strain gauge has already been. Learn the essentials of strain gauge measurement hbm. The major intent here is not to suggest electrical measurement techniques but rather to.
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