Development of in-plane and out-of-plane deformation simultaneous measurement method for the analysis of buckling

摘要

The deformation measurement method by using only two speckle pattern has been proposed in ESPI by using Fourier transform. Speckle interferometry can measure not only the out-of-plane but also the in-plane deformation measurement of the objects with rough surfaces. So, speckle interferometry is useful optical measurement method in the analysis of buckling phenomenon that occurs simultaneously in-plane and out-of-plane deformations in a beam. Generally, the in-plane deformation can be detected by using the two-beam speckle interferometer. At present, some methods of 3-D deformation measurements have been also reported using some special speckle interferometers based on two-beam interferometer. Then, Fourier transform and the technologies based on digital holography were employed there. In these reports, some sets of the two-beam speckle interferometer are combined for 3-D deformation measurement. However, there are some problems. In this paper, a novel in-plane and out-of-plane deformation measurement optical system is proposed by combining one pair of interferometers under the idea based on the principle of two-beam interferometer. Then, the novel optical system is applied to the analysis of the buckling phenomena. The availability of the proposed method in the analyzing process of buckling phenomena is discussed with Euler's buckling theory. From the experimental results, it can be confirmed that the buckling analysis of the beam agrees very well with the theory of Euler's buckling.