Abstract
An interferometric technique is used to determine directly patterns of derivatives of displacements. In the case of plate models, the fringes are loci of equal slope; for specimens provided with surface gratings, one forms patterns of partial derivatives of in-plane displacements. A theory for the interpretation of the interference fringes in terms of displacements is outlined; some experimental applications illustrate the paper.
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Abbreviations
- A * :
-
complex conjugate ofA
- D :
-
stiffness of plate
- E :
-
Young's modulus
- f :
-
focal distance
- h :
-
thickness of plate
- I, (x, y) :
-
intensity distribution
- I :
-
moment of inertia
- i :
-
imaginary unit
- M, M x, My :
-
bending moments
- M xy :
-
twisting moment
- p :
-
distance
- P :
-
magnitude of point load
- ΔS :
-
optical path-length difference
- t(x, y) :
-
amplitude distribution
- U(x, y) :
-
field distribution
- v :
-
contraction coefficient (Poisson's ratio)
- w :
-
deflection
- x, y, z :
-
Cartesian coordinates
- σ, σ1, σ2 :
-
magnitude of shift
- ε:
-
strain
- ψ:
-
slope
- μm :
-
micrometer
- τ:
-
shear strain
- \(\mathop \Delta \limits_{}^2 Q\) :
-
increase ofQ between state 1 and 2
- \(< \mathop F\limits_{}^1 > \) :
-
approximate value ofF
References
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Meunier, J., Private communication.
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Boone, P.M. Determination of slope and strain contours by double-exposure shearing interferometry. Experimental Mechanics 15, 295–302 (1975). https://doi.org/10.1007/BF02318660
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DOI: https://doi.org/10.1007/BF02318660