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A permanent Global Positioning System receiver at Casa Diablo Hot Springs, Long Valley Caldera, California was installed in January, 1993, and has operated almost continuously since then.
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This report provides the technical basis for two new measurement methods usingoptical interferometry. The first proposed method is for in-plane length meausrements of microelectromechanical systems (MEMS) devices and is called the...
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This report provides the technical basis for two new measurement methods usingoptical interferometry. The first proposed method is for in-plane length meausrements of microelectromechanical systems (MEMS) devices and is called the Length Measurement Transitional Edge Method (or LMTEM). The second proposed method is for out-of-plane measurements. From these measurements, residual strain and strain gradient determinations are made. The method is called the Three Point Method for Strain (or 3PMFS).
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摘要 :
Optical methods, utilizing the interference fringes produced by diffraction of laser light passing through a narrow slit, have been developed for strain measurements at high temperature above 1000/degree/C. Basic principles, instr...
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Optical methods, utilizing the interference fringes produced by diffraction of laser light passing through a narrow slit, have been developed for strain measurements at high temperature above 1000/degree/C. Basic principles, instrumentation, calibration, and measurement techniques of the methods and sample applications are presented. 3 refs., 11 figs. (ERA citation 14:026966)
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摘要 :
A strain sensor uses an optical fiber including a strain sensitive portion and at least one strain insensitive portion. The strain sensitive portion is mounted on the surface of a structure at a location where a strain is desired ...
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A strain sensor uses an optical fiber including a strain sensitive portion and at least one strain insensitive portion. The strain sensitive portion is mounted on the surface of a structure at a location where a strain is desired to be measured. The strain insensitive portion(s) may be fused to the strain sensitive portion to transmit light therethrough, so that the resulting pattern may be detected to determine the amount of strain by comparison with a similar fiber not subjected to strain, or with the light pattern produced when the fiber is not under strain.
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The report describes the design and construction of a multi-component force transducer. The selected design was analyzed using a three-dimensional finite element model. The transducer was built and the calculated results were comp...
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The report describes the design and construction of a multi-component force transducer. The selected design was analyzed using a three-dimensional finite element model. The transducer was built and the calculated results were compared to experimental data. Results showed a good agreement between calculations and measurements. (Copyright Valtion teknillinen tutkimuskeskus (VTT) 1989.)
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A self-contained, nonelectrical strain gage capable of amplifying strain inputs and preserving the maximum strain measurement for later observance is presented.
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The data requirements for a standard strain recorder are developed to obtain shipstructural response data for a number of applications. A review of the state-of-the-art in strain recording instrumentation is presented and compared...
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The data requirements for a standard strain recorder are developed to obtain shipstructural response data for a number of applications. A review of the state-of-the-art in strain recording instrumentation is presented and compared to the ideal instrumentation. A specific standard strain recorder is recommended that is flexible in operation and capabilities. The standard strain recorder is capable of recording ship structural response data resulting from severe environments facilitating validation of load criteria and analysis for ship structural response.
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An ac excited self-balancing instrument for measuring low level strain gauge transducer outputs is described. The design of a specific circuit optimized for use with a small wind tunnel force balance is presented with sufficient i...
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An ac excited self-balancing instrument for measuring low level strain gauge transducer outputs is described. The design of a specific circuit optimized for use with a small wind tunnel force balance is presented with sufficient information to facilitate circuit optimization for other applications. The instrument is intended for applications where the bridge output voltage is below the level that can be conveniently handled by conventional dc amplifier systems. Tests on a prototype instrument showed an input noise in a 0.1 Hz to 0.7 Hz bandwidth of 4 nV RMS, a zero drift of less than 0.1 microvolt per day and negligible drifts.
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摘要 :
A practical holographic interferometer system has been developed together with quantitative interpretation algorithms enabling the precise measurement of three-dimensional deformations on diffusely reflecting objects. The objects ...
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A practical holographic interferometer system has been developed together with quantitative interpretation algorithms enabling the precise measurement of three-dimensional deformations on diffusely reflecting objects. The objects under investigation may be large and have irregular and unknown shapes. The accuracy of the system as presented here is governed by the inaccuracies made in measuring the interferometer geometry. These can easily be improved by an order of magnitude if dedicated equipment is used to determine this geometry, e.g. theodolites. Other possible improvements are the replacement of photographic registration of the fringe patterns by video-electronic registration using e.g. CCD (Charged Coupled Device) sensors, and the use of digital image processing techniques to analyze these patterns.
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摘要 :
The general problem of penetrator instrumentation is duscussed, and the advantages of strain gages for the field test environment are presented. The use of strain modes shapes to determine the best locations for strain gage instal...
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The general problem of penetrator instrumentation is duscussed, and the advantages of strain gages for the field test environment are presented. The use of strain modes shapes to determine the best locations for strain gage installation is explained and applied to a geometrically simple bar whose mode shapes can be derived analytically. For more complex structures such as penetrators, a rationale is provided to derive strain mode shapes from an acceleration-based modal analysis. This rationale is used to determine the strain mode shapes using experimental data for a penetrator body.
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