Shearography is widely used in nondestructive testing because it has the advantages of full-field, robust, non-contact and high sensitivity. However, conventional shearography can only measure the first derivative of deformation in a single direction; multiple tests need to be done to obtain the first derivative of 3D deformation in different shearing directions. This paper presents a novel shearography system that simultaneously measures the first derivative of 3D deformation in two orthogonal shearing directions, one is in the x direction and the other is in the y direction. This system achieves dual-directional shearography by a modified Michelson interferometer. The object surface is illuminated by three different wavelengths of laser in different directions and a 3CCD color camera is used to record images. Different color shearograms recorded by 3CCD color camera were extracted respectively through channel separation, and cross talk does not exist. The phase change maps related to the first derivative of deformation are decoded by spatial carrier phase-shifting method, then the first derivative of 3D deformation in the x and y directions can be solved. The feasibility of the proposed system in measuring dual-directional first derivative of 3D deformation is verified by experiments.
Real-Time Simultaneous Measurement for Dual-Directional First Derivative of 3D Deformation Based on Shearography
Sae Technical Papers
SAE WCX Digital Summit ; 2021
2021-04-06
Aufsatz (Konferenz)
Englisch
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