Abstract
The application of the Fourier transform to photoelasticity was used in the evaluation of the retardation using a carrier system of fringes. In photoelasticity, the light intensity from the analyzer in a circular polariscope depends on both the retardation (isochromatics) and the isoclinic parameter. The theoretical analysis shows that the angle between the principal stresses in the model and in the carrier system of fringes influences the evaluation of the retardation (isochromatics), as occurs when misaligned compensators (namely, Babinet) are used. As a consequence, this method may not be applied as a full-field technique, although the error is small if the angle between the principal stresses in the model and in the carrier is less than 25 deg. Numerical simulations and experimental tests were conducted to corroborate this prediction.
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Abbreviations
- C :
-
stress optic coefficient
- d :
-
thickness of the model
- f :
-
fringe frequency of the model
- f c :
-
fringe frequency of the carrier
- I :
-
light intensity emerging from the polariscope
- I 0 :
-
background intensity
- I 1 :
-
modulation term
- I 2 :
-
noise
- I f :
-
intensity of the in-phase signal
- I q :
-
intensity of the in-quadrature signal
- α:
-
angle between the maximum principal stress in the model and the horizontal reference axis
- αc :
-
angle between the maximum principal stress in the carrier and the horizontal reference axis
- αr :
-
angle between the maximum principal stresses in the model and in the carrier (absolute value)
- δ:
-
retardation of the model
- δc :
-
retardation of the carrier
- δ *c :
-
wrapped retardation of the carrier
- δt :
-
total retardation
- δ *t :
-
wrapped total retardation
- λ:
-
light wavelength
- σ1,σ2 :
-
principal stresses in the model (σ1≥σ1)
- σ1c,σ2c :
-
principal stresses in the carrier σ1c≥σ2c
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Ajovalasit, A., Zuccarello, B. Limitation of fourier transform photoelasticity: Influence of isoclinics. Experimental Mechanics 40, 384–392 (2000). https://doi.org/10.1007/BF02326484
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DOI: https://doi.org/10.1007/BF02326484