The Art of Practical and Precise Strain Based ... - Webprofile.info

Applications Note 1-5:All strain-based sensor structures possess an internal spring member upon whichthe parameter acts to produce output. In the case of the cantilevered-beam accelerometerof Figure 1-4, the seismic mass will produce an inertial force acting on thebeam as a function of the acceleration of the device. The bending strain createdmay be measured by a variety of means, the most common being by means ofstrain gages bonded to the bending beam. In the case of the cantilevered-beamaccelerometer, the sensor spring member is the beam itself, as it is the beam thatprovides the elastic restoring forces that act in opposition to the applied inertialloads. In the case of the flush-diaphragm pressure sensor of Figure 1-5, unequalpressures acting upon the diaphragm structure results in a force imbalance producingbending and resultant strain. In all cases, the strain-based sensor possesses aninternal spring member that is configured to respond mechanically to a specificparameter input. The shape of the spring member will vary widely as a function ofthe parameter to which the sensor has been designed to respond.FIGURE 1-5. The Strain-Based Pressure Sensor:Strain gagesPressure Loading (P applied )P referenceDiaphragm bending whereP applied > P referenceThe Art of Practical and Precise Strain Based Measurement 2nd Edition © 1999 CHAPTER 1-17