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Engineering LibreTexts

13.7: Activities and Videos

  • Page ID
    36476
  • Sketch the pattern of isochromatic regions. Which of the isochromatic regions corresponds to the unstressed region of the bar?

    To determine the birefringence use a Michel-Levy chart, whose axes are retardation (birefringence times thickness) versus the thickness of the specimen. On the chart are plotted lines of constant birefringence. The thickness of the bar was 3.0 mm. Use the Michel-Levy chart to determine the optical path difference at the midpoints of the two long edges of the bar and deduce the optical path differences arising from the stress at these points. Hence estimate the stress at these points using the Stress-Optic Law

    \[n_Q - n_P = C(\sigma_P -\sigma_Q) \]

    The principal stresses, σP and σQ, in the plane section are aligned parallel to orthogonal directions P and Q; nP is the refractive index for the vibration direction parallel to P and nQ is the refractive index for the vibration direction parallel to Q.

    The stress-optical coefficient of polycarbonate is -78.0 × 10-12 Pa-1.

    3-point bending

    Normal bar

    https://www.doitpoms.ac.uk/tlplib/ph...deos/3-bar.mp4

    Annealed bar in 3-point bending rig under a
    circular polariscope

    https://www.doitpoms.ac.uk/tlplib/ph...3-bar-zoom.mp4

    Close up of annealed bar in 3-point bending rig under a
    circular polariscope

    https://www.doitpoms.ac.uk/tlplib/ph.../3-bar-sim.mp4

    Abaqus-generated simulation of a bar
    undergoing 3-point bending

    Bar with Notch

    https://www.doitpoms.ac.uk/tlplib/ph...os/3-notch.mp4

    Annealed bar with notch in 3-point bending rig under a
    circular polariscope

    https://www.doitpoms.ac.uk/tlplib/ph...-notch-sim.mp4

    Abaqus-generated simulation of a bar with notch
    undergoing 3-point bending

    Bar with Hole

    https://www.doitpoms.ac.uk/tlplib/ph...eos/3-hole.mp4

    Annealed bar with hole in 3-point bending rig under a
    circular polariscope

    https://www.doitpoms.ac.uk/tlplib/ph...3-hole-sim.mp4

    Abaqus-generated simulation of a bar with hole
    undergoing 3-point bending

    4-point bending

    Normal bar

    https://www.doitpoms.ac.uk/tlplib/ph...deos/4-bar.mp4

    Annealed bar in 4-point bending rig under a
    circular polariscope

    https://www.doitpoms.ac.uk/tlplib/ph...4-bar-zoom.mp4

    Close up of annealed bar in 4-point bending rig under a
    circular polariscope

    https://www.doitpoms.ac.uk/tlplib/ph.../4-bar-sim.mp4

    Abaqus-generated simulation of a bar
    undergoing 4-point bending

    Bar with Notch

    https://www.doitpoms.ac.uk/tlplib/ph...os/4-notch.mp4

    Annealed bar with notch in 4-point bending rig under a
    circular polariscope

    https://www.doitpoms.ac.uk/tlplib/ph...-notch-sim.mp4

    Abaqus-generated simulation of a bar with notch
    undergoing 4-point bending

    Bar with Hole

    https://www.doitpoms.ac.uk/tlplib/ph...eos/4-hole.mp4

    Annealed bar with hole in 4-point bending rig under a
    circular polariscope

    https://www.doitpoms.ac.uk/tlplib/ph...4-hole-sim.mp4

    Abaqus-generated simulation of a bar with hole
    undergoing 4-point bending

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