Stress measurement device and method based on diffraction overlap iterative algorithm

Abstract

The invention provides a stress measuring apparatus and method based on a diffraction overlapping iteration algorithm. The apparatus comprises a light source, a polarizer, a polarization analyzer, twoquarter wave-plates, a filter, an object-placing table, two lenses, a translation bench clamped with a diffraction object, a CCD and an acquisition computer. The measuring method includes steps: placing a to-be-measured optical element in a circular polarization parallel light field, rotating the polarization analyzer, and respectively recording diffraction patterns of an object in two group of different polarization states; and reconstructing amplitudes and phases of two groups of light fields by employing the diffraction overlapping iteration algorithm, extracting the isochromatic line, theisopachic line and the isoclinic line of the to-be-measured element, and obtaining quantified stress information by employing an element photoelastic parameter. According to the apparatus and the method, the phase measurement advantage of the PIE is fully utilized, the isoclinic line and the isopachic line are both accurately extracted from phase information, the apparatus is applicable to all-field measurement of the stress of the elements, and an important practical significance is achieved for the development of the stress measurement technology of the optical elements.

Description

technical field [0001] The invention belongs to the technical field of photoelectric non-destructive testing, in particular to a stress measuring device and method based on a diffraction overlapping iterative algorithm. Background technique [0002] Combining photoelasticity with computer image processing technology to automatically collect photoelastic data and analyze stress is called digital photoelasticity, which is the direction of current experimental mechanics research. There are two key points to realize photoelastic stress measurement, one is to determine the grades of contour lines and isoclines of each point, and the other is to distinguish the properties of isoclines, that is, to determine the first (or second) principal stress direction. In the traditional photoelastic method, researchers can solve the first key point well, and usually use the six-step phase-shift method based on the circular polarization field to determine the full-field contour series. Altho...

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Problems solved by technology

But it also has some deficiencies: 1. The method of scanning the component to be tested is only suitable for the measurement of small-caliber components; 2. Five sets of data were collected in the experiment, and the amount of data is large. and isoclines, still based on the traditional four-step phase shift principle, only the intensity information of the data is used

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