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STRAIN GAGE NETWORK DISTINGUISHES BETWEEN THERMAL AND MECHANICAL DEFORMATIONS

A STRAIN GAGE NETWORK CONSISTING OF A TEST GAGE AND TWO DUMMY GAGES ARRANGED TO DISTINGUISH THERMALLY INDUCED DEFORMATION FROM MECHANICAL STRAIN WAS DESIGNED TO MEASURE THE THERMAL COEFFICIENT OF LINEAR EXPANSION OF COMPOSITE METAL STRUCTURES. THREE SEPARATE STRAIN GAGES ARE MOUNTED ON THE TEST SPECIMEN AND WIRED INTO A DOUBLE BRIDGE CONFIGURATION. VARIABLE RESISTORS ARE USED IN THE LEGS OF THE BRIDGES TO BALANCE THE OUTPUTS. THE FIRST GAGE IS BONDED TO THE TEST SPECIMEN SURFACE IN SUCH A WAY THAT IT RESPONDS TO BOTH THERMALLY AND MECHANICALLY INDUCED STRAINS. THE SECOND GAGE IS ATTACHED TO THE TEST SPECIMEN SURFACE WITH A SILICONE GREASE AND COMPENSATES FOR THE ELECTRICAL CHANGES OF THE FIRST GAGE AS A FUNCTION OF TEMPERATURE. THE THIRD GAGE IS BONDED TO A STRIP OF MATERIAL IDENTICAL TO THE TEST SPECIMEN AND THE STRIP IS THERMALLY ATTACHED TO THE TEST SPECIMEN SURFACE. THIS GAGE COMPENSATES FOR BOTH ELECTRICAL CHANGES OF THE FIRST GAGE AND THERMAL EXPANSION IN THE MATERIAL CAUSING THE OUTPUT BETWEEN THE FIRST AND SECOND GAGES TO RESPOND ONLY TO MECHANICAL DEFORMATION INDUCED THERMALLY IN THE MATERIAL STRIP BY TEMPERATURE GRADIENTS OCCURRING IN THE TEST STRUCTURE. THE OUTPUT BETWEEN THE FIRST AND SECOND GAGES INDICATES THE TOTAL THERMAL AND MECHANICAL STRAIN CHANGE IN THE TEST STRUCTURE, WHILE THE OUTPUT BETWEEN THE FIRST AND THIRD GAGES INDICATES ONLY THE MECHANICAL COMPONENT. BY SUBTRACTING THE MECHANICAL STRAIN FROM THE TOTAL STRAIN, THE TRUE THERMAL STRAIN ACTING ON THE TEST STRUCTURE IS DETERMINED.

  • Supplemental Notes:
    • 2 Pp, 2 Fig
  • Publication Date: 1966-7

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  • Accession Number: 00216132
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 12 1994 12:00AM