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Proceedings Paper

Out-of-plane and in-plane strain measured by shearography
Author(s): Wolfgang Steinchen; M. Schuth; Lian Xiang Yang; Gerhard Kupfer
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Paper Abstract

The shearographic interferometry is employed as a nondestructive full field, optical testing and measuring method without contact. Fringes of contant strain (so called isotase, tasis (Greek) equals strain) can be observed in real-time on the surface of the investigated machine parts and structures of any material and are represented by the shearogram. Using shearography two states of deformation are recorded by doubly exposing a Holotest film in an ordinary camera or stored by an electronic image processing system. In the objective of the camera a shearing element is integrated or the lateral Michelson shearing interferometer is used. Rigid body motions of the object are not recorded. Local deformation irregulatrites caused by a defect under or on the surface of the specimen create strain concentrations; the homogeneous surrounding is poorly superimposed by an interference pattern. The shearogram shows dark and bright fringes which are the functions of the displaceemnt derivative. The holographic interferometry measures the out of plane deformations directly. Terms of the out-of-plane strain can be determined by the shearographic method as well as the in-plane strain fringes which are described in this paper.

Paper Details

Date Published: 21 September 1995
PDF: 12 pages
Proc. SPIE 2509, Smart Structures: Optical Instrumentation and Sensing Systems, (21 September 1995); doi: 10.1117/12.221107
Show Author Affiliations
Wolfgang Steinchen, Univ. of Kassel (Germany)
M. Schuth, Univ. of Kassel (Germany)
Lian Xiang Yang, Univ. of Kassel (Germany)
Gerhard Kupfer, Univ. of Kassel (Germany)


Published in SPIE Proceedings Vol. 2509:
Smart Structures: Optical Instrumentation and Sensing Systems
Deepak G. Uttamchandani, Editor(s)

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