Materials Science and Manufacturing Engineering Miscellaneous


Materials Science and Manufacturing Engineering Miscellaneous

Materials Science and Manufacturing Engineering

  1. A bar is compressed to half of its original length. The magnitude of true strain produced in the deformed bar is (correct to two decimal places).









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    T = lnlf²
    li


    Correct Option: A

    T = lnlf²
    li



  1. In a two-stage wire drawing operation, the fractional reduction (ratio of change in crosssectional area to initial cross-sectional area) in the first stage is 0.4. The fractional reduction in the second stage is 0.3. The overall fractional reduction is









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    40% Reduction = 1 × 0.4 = 0.4
    30% Reduction of 0.6 = 0.6 × 0.3 = 0.18
    Total Reduction = 0.58

    Correct Option: B

    40% Reduction = 1 × 0.4 = 0.4
    30% Reduction of 0.6 = 0.6 × 0.3 = 0.18
    Total Reduction = 0.58



  1. A metal rod of initial length L0 is subjected to a drawing process. The length of the rod at any instant is given by the expression, L(t) = L0 (1 + t²), where t is the time in minutes. The true strain rate (in min–1) at the end of one minute is _______.









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    L(t) = L0 (1 + t²)
    ⇒ dL = L0 × 2t dt

    As d ∈T =
    dL
    L

    d ∈T =
    L02t dt
    L0 (1 + t²)

    d ∈T
    =
    2t
    dt1 + t²

    at t = 1 min
    T
    =
    2 × 1
    = 1 min- 1
    T1 + 1²

    Correct Option: A

    L(t) = L0 (1 + t²)
    ⇒ dL = L0 × 2t dt

    As d ∈T =
    dL
    L

    d ∈T =
    L02t dt
    L0 (1 + t²)

    d ∈T
    =
    2t
    dt1 + t²

    at t = 1 min
    T
    =
    2 × 1
    = 1 min- 1
    T1 + 1²


  1. In a wire drawing operation, diameter of a Steel wire is reduced from 10 mm to 8 mm. The mean flow stress of the material is 400 MPa. The ideal force required for drawing (ignoring friction and redundant work) is









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    Di = 10 mm, Di = 8mm
    σ0
    = 400 MPa

    σd = σ0lnDi²
    Df

    σd = 400ln10²
    8

    σd = 178.51 MPa
    Ideal force = 178.51 × 106 ×
    π
    (0.008)²
    4

    I deal force 8.97 KN

    Correct Option: B

    Di = 10 mm, Di = 8mm
    σ0
    = 400 MPa

    σd = σ0lnDi²
    Df

    σd = 400ln10²
    8

    σd = 178.51 MPa
    Ideal force = 178.51 × 106 ×
    π
    (0.008)²
    4

    I deal force 8.97 KN



  1. Cold shut is a defect in casting due to









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    NA

    Correct Option: D

    NA