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Homework Help: Strain gauge problem

  1. Apr 21, 2008 #1
    1. The problem statement, all variables and given/known data

    In a bridge circuit R1 is bonded to a cylindrical specimen of diameter 25.08mm. R4 is 160.1ohm, R3 is 2502.7ohm and R2 at balance is 2505.8ohm when the specimen is unloaded and 2511.7ohm when it is loaded with 50kN. the gauge factor of the strain gauges was 2.10. determine the value of young's modulus for the material of the specimen.

    2. Relevant equations

    Vo=V/4(dR1/R1 - dR2/R2)
    Vo=V/4.k.e where e is strain

    stress= force/area = 50kN/pi(12.54x10^-3)^2

    3. The attempt at a solution

    obviously all i need to do is derive the strain and then divide that into the stress calculated above but i really have no idea where to begin. the only relations aside from the simple ratio that i know for a wheatstone bridge circuit involve the input and output voltage which aren't given in the question. so how should i go about manipulating the resistances to work out the strain?

  2. jcsd
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