Abstract
A simple and reliable technique is proposed for predicting the cartesian components of a general-displacement field from the usual double-exposure holographic fringes. An overdetermined set of simultaneous equations is developed at each point of interest and a least-squares solution provides the three displacement components. The reliability of this technique was tested by varying the degree of overdeterminacy of the set of equations. The three-dimensional displacement field of a beam under pure bending was determined holographically and compared with that from a closed-form theoretical solution. Finally, a highly skewed marine-propeller-blade model under uniform air pressure was analyzed holographically and the results were correlated with those from a finite-element analysis.
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Abbreviations
- A k, Bk, Ck :
-
coefficients
- H :
-
point on hologram
- P :
-
point on propeller blade
- P′:
-
displaced point on propeller blade
- R o :
-
distance betweenS andP
- R k :
-
distance betweenH andP
- S :
-
object light source
- U, V, W :
-
cartesian components of displacement
- X, Y, Z :
-
cartesian coordinates
- k :
-
subscript
- n :
-
fringe order
- σ:
-
optical-path-length difference
- λ:
-
wavelength
References
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Dhir, S.K., Sikora, J.P. An improved method for obtaining the general-displacement field from a holographic interferogram. Experimental Mechanics 12, 323–327 (1972). https://doi.org/10.1007/BF02320488
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DOI: https://doi.org/10.1007/BF02320488