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

More documents

Recommendations

Info

Strain-Based Measurement Introduction:The piezoelectric class of sensors utilizes the charge-generating characteristicsof the piezoelectric class of materials as a function of applied stress and resultantstrain to produce charge outputs as a function of the applied parameterinput. The spring member in a piezoelectric sensor structure is generally thepiezoelectric material itself.The performance of any strain-based sensor technology relates directly to themechanical, thermal, and electrical qualities of the internal spring member andstrain-sensing mechanism utilized.Other selected non-strain-based sensor technologies are discussed with theobjective of providing you with a fuller and more complete perspective of theworld of measurement in general.The measurement environment and the parameter to be measured as well as thetime-varying nature of both will impose constraints upon the shape, position,mass, stiffness, structural support, thermal inertia, thermal impedance, allowablematerials, and processes that can be used with present technology to fabricatethe sensor. The Art of Applications Engineering is the study of theimplications of these constraints, relative to the many varied measurementenvironments, with the objective of maximizing the validity of the informationoutput that the sensor provides.CHAPTER 1-18 The Art of Practical and Precise Strain Based Measurement 2nd Edition © 1999
Applications Note 1-6:Applications Note 1-6:The Measurement System Transfer FunctionThe transfer function is the complete relationship defining the output of a sensorfor any set of measurand inputs. The transfer function is also the relationship bywhich the time-varying input measurand is related to the resulting time-varyingoutput of a sensor. The transfer function is generally accepted as:F outH(f) where:( f ) = H( f)F in ( f )F out = the output function of the sensor.F in = the input measurand function.Note that each element of the signal-processing system will also possess a uniquetransfer function as well.The Concept of Spatial Independence:The concept of spatial independence means that a variable measurand is spatiallyuniform and that the value of the measurand is constant and independent of position,relative to the size of the sensorÕs active member. The statically-pressurizedvessel meets the requirements of spatial independence. Tight turbulent flow fields,as may be encountered around an antenna mounted to a high-performance fighteraircraft, will show high-level pressure variations over small linear distances,implying that the value of the measurand may not be constant over the sensitivearea of the sensor. In cases such as this, the requirement for spatial independencemay not be met. Figure 1-6 graphically shows the concept of spatial independence.The Art of Practical and Precise Strain Based Measurement 2nd Edition © 1999 CHAPTER 1-19
Page 1 and 2: The Art of Practical andPrecise Str
Page 3 and 4: Special Credits:Mrs. Helen Pierson,
Page 5 and 6: Table of ContentsBy James G. Pierso
Page 8 and 9: ContentsApplications Note 4-10:Lead
Page 10: ContentsCHAPTER 8Electrical Conside
Page 13 and 14: CHAPTER 1Strain-BasedMeasurementInt
Page 15 and 16: Applications Note 1-1: Introduction
Page 17 and 18: Applications Note 1-1: Introduction
Page 19 and 20: Applications Note 1-2:The Art of Ap
Page 21 and 22: Applications Note 1-31. The presenc
Page 23 and 24: Applications Note 1-3result in a pe
Page 25 and 26: Applications Note 1-4:The measureme
Page 27 and 28: Applications Note 1-4:uncertainty i
Page 29: Applications Note 1-5:All strain-ba
Page 33 and 34: Applications Note 1-6:ical size of
Page 35 and 36: Applications Note 1-6:and where:j i
Page 37 and 38: Applications Note 1-6:5. millivolts
Page 39: Applications Note 1-6:.Electrodynam
Page 44 and 45: Strain-Based Measurement Introducti
Page 80 and 81:
Strain-Based Measurement Introducti
Page 82 and 83:
Page 84 and 85:
Page 86 and 87:
Page 88 and 89:
Page 90 and 91:
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104:
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?