RECENT DEVELOPMENT OF VIBRATING-WIRE INSTRUMENTS

AN EXCITATION AND FEEDBACK SYSTEM IS USED TO MAINTAIN THE GAUGE-WIRE IN CONSTANT OSCILLATION AT ITS RESONANT FREQUENCY OF VIBRATION FOR VIBRATING-WIRE TYPE TRANSDUCERS. THE OSCILLATOR CIRCUIT IS PICTURED. WITH THIS SYSTEM THE OUTPUT OF THE GAUGE CONSISTS OF A CONTINOUS ALTERNATING CURRENT WHICH HAS THE SAME FREQUENCY AS THE RESONANT FREQUENCY OF VIBRATION OF THE GAUGE-WIRE. THE FREQUENCY OF THE ALTERNATING CURRENT IS MEASURED DIRECTLY ON A DIGITAL COUNTER. DIGITAL MEASUREMENTS OF FREQUENCY ARE THUS DIRECTLY OBTAINED WITHOUT HAVING TO TUNE OR ADJUST ANY CIRCUIT FOR SUCH MEASUREMENT. A DIGITAL READ-OUT INSTRUMENT IS USED WHICH CONSISTS OF A COMMERCIAL DIGITAL COUNTER PLUS THE AMPLIFIER AND CONTROL CIRCUITS WHICH ARE A NECESSARY PART OF THE EXCITATION SYSTEMS. THIS METHOD FACILITATES THE USE OF MORE SOPHISTICATED READ-OUT AND RECORDING EQUIPMENT, SUCH AS DIGITAL PRINTERS, TAPE RECORDERS OR PUNCHES, AND DIGITAL TO ANALOG CONVERTERS. A VIBRATING WIRE-GAUGE CALCULATOR WAS DEVELOPED WHICH WILL MEASURE DIRECTLY THE SQUARE OF THE FREQUENCY OR THE DIFFERENCE BETWEEN THE SQUARES OF TWO FREQUENCIES. THIS INSTRUMENT MEASURES FREQUENCY, COMPUTES THE SQUARE OF THE FREQUENCY AND MULTIPLIES IT BY A PRESET CONSTANT WHICH CAN BE VARIED. AN IMPROVED SURFACE MOUNTING VIBRATING-WIRE STRAIN GAUGE WAS DEVELOPED. THE GAUGE-WIRE IS INSIDE A STAINLESS STEEL TUBE WHICH IS SEALED BY O-RINGS. THE GAUGE-WIRE EXCITER IS MOUNTED DIRECTLY ON THE TUBE. THE GAUGE IS FASTENED DIRECTLY TO TWO SUPPORT POSTS THAT HAVE BEEN PREVIOUSLY ATTACHED TO THE STRUCTURE. A STUD WELDED INSTALLATION IS SHOWN. AN INCLINOMETER BASED ON VIBRATING-WIRE STRAIN GAUGE HAS ALSO BEEN DEVELOPED. THE APPARATUS CONSISTS OF A PIVOTING WEIGHT WHICH IS RESTRAINED BY TWO GAUGE-WIRES. IF THE INSTRUMENT IS TILTED, THE TENSION AND THEREFORE THE FREQUENCY OF VIBRATION OF THE GAUGE-WIRES WILL BE INCREASED FOR ONE GAUGE AND DECREASED FOR THE OTHER ONE. THIS CHANGE IN FREQUENCY OF THE GAUGE-WIRES IS A MEASURE OF THE TILT ANGLE OF THE MEASUREMENT GIVEN BY AN EQUATION. A DEVICE TO DETERMINE THE ORIENTATION OF AN INCLINOMETER INSIDE A ROUND CASING IS BEING TESTED.

  • Supplemental Notes:
    • No 75, pp 45-53, 9 FIG
  • Corporate Authors:

    N/A

    ,   United States 
  • Authors:
    • DiBiagio, E
    • Oien, K
  • Publication Date: 0

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  • Accession Number: 00229543
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 15 2004 2:38AM