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Proceedings Paper

Strain/stress measurements using electronic speckle pattern interferometry
Author(s): Tilo Pfeifer; Horst Konstantin Mischo; Andreas Ettemeyer; Zhiguo Wang; Ronny Wegner
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Paper Abstract

In its classical application Electronic Speckle-Pattern Interferometry (ESPI) is used to measure deformations with high resolution. Additionally, this methods also able to measure the 3D topography of technical surfaces even with discontinuities. If adequate set-ups are used, combined measurements of shape and deformation can also be carried out. Especially in production of machines and other metal parts, the determination of the stress and strain e.g. of welding points is a very important issue for evaluating about the quality of the specimen under test. Here, the use of wire resistance strain gauges is state-of-the-art for measuring length variations of parts under mechanical load. It is very time-consuming to prepare the corresponding measurement environment for strain gauges. Moreover, only very limited information about the strain can be measured by this means because all information is integrated over the whole area covered by the strain gauges without lateral resolution. In order to extend this kind of metrology to a matrix of some thousands points even including sensitivity in the out-of-plane-direction, ESPI-methods can be used. As described in this paper, it is therefore necessary to perform both,the shape and the deformation measurement to obtain the necessary information. Of course, the directions of sensitivity depend on the contour of the test specimen ad can be determined due to the previously measured topography. In this paper current work on the field of stress and strain measurements with ESPI is described. The experimental result of several technical applications is shown and it is compared to measurements with conventional strain gauges. Further possible technical applications are discussed and the prototype of an ESPI stress sensor is presented.

Paper Details

Date Published: 29 December 1998
PDF: 10 pages
Proc. SPIE 3520, Three-Dimensional Imaging, Optical Metrology, and Inspection IV, (29 December 1998); doi: 10.1117/12.334340
Show Author Affiliations
Tilo Pfeifer, Fraunhofer Institute of Production Technology (Germany)
Horst Konstantin Mischo, Fraunhofer Institute of Production Technology (Germany)
Andreas Ettemeyer, Dr. Ettemeyer GmbH & Co. (Germany)
Zhiguo Wang, Dr. Ettemeyer GmbH & Co. (Germany)
Ronny Wegner, Dr. Ettemeyer GmbH & Co. (Germany)

Published in SPIE Proceedings Vol. 3520:
Three-Dimensional Imaging, Optical Metrology, and Inspection IV
Kevin G. Harding; Donald J. Svetkoff; Katherine Creath; James S. Harris, Editor(s)

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