6.163 final project photoelasticity

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6.163 final project photoelasticity

• megumi, rene, danny, ran

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agenda

• demo
• isoclinic (stress dependent) fringes
• isochromatic (wavelength dependent) fringes
• introduction
• mark i, goals, motivations
• background
• terms, linear and circular polariscopes
• results and analysis
• stress vs load, isoclinc vs isochromatic,
• multiple notches, beautiful images
• conclusion
• overview, future work

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demo using polarizers, quarter-wave plates, and
polycarbonate

• - isoclinic (stress)
• isochromatic (wavelength)

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mark i overview

• notched plastic strip - image easy to analyze
• squeezed cup - aesthetic image 1
• stretched saran wrap - aesthetic image 2

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project goals

• we wanted to study
• stress patterns vs load,
• isoclinic (stress) vs
• isochromatic (wavelength) fringes,
• multiple notches,
• crack propagation, and
• beautiful images.

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project motivations

• stresses are important in
• architectural structures,
• industrial parts,
• commercial goods,
• etc.

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isoclinic (stress) and isochromatic (wavelength)

• 1 daley, william. experimental stress
• analysis. pp 343 and 349.

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linear polariscope
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circular polariscope
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stress versus load 1

• increasing load on strip with no notch

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stress versus load 2

• increasing load on strip with one notch

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stress versus load 3

• increasing load on strip with two notches

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isoclinic (stress) and isochromatic (wavelength)

• attempt 1 - naïve linear combination
• attempt 2 - thresholds
• attempt 3 - gridded linear combinations

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multiple notches

• x 2
• what about 3 notches?

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beautiful images

• mit spotlight!

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bloopers

• fringeless images, acrylic (vs polycarbonate)
• fringeless images, stress perpendicular to plane
  of view
• failure of crack propagation study

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final project overview

• as load increases -gt more isoclinic
• as load increases -gt finer isochromatic
• isolation of isoclinic and isochromatic -gt
  possible
• predictability of stress in multiple notches -gt
• reasonable
• stress patterns -gt beautiful
• acrylic -gt not visible
• pressure perp. to plane of view -gt not visible

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future work

• for us, analysis using matlab.
• for future work, we recommend
• using a circular polariscope to study
  isochromatic fringes
• a further study of images via linear vs circular
  polariscope
• a further study on stress patterns vs elasticity.

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thank you. any questions?