Stress measurement method and stress measurement light path device

Abstract

The invention discloses a stress measurement method. The method comprises the following steps of (1) arranging a sample main body made of a single photoelastic material and a coating structure thereof; (2) arranging a stress measurement light path device; (3) starting a light source, through an arranged light path, refracting a speckle coating for multiple times and then enabling the light to coaxially enter an image acquisition unit with a reflection photoelastic pattern; (4) starting an image acquisition device, and obtaining a speckle image and a photoelastic image at the same moment at thetwo sides of the sample; and (5) jointly solving the related experiment results of a photoelastic experiment and a digital image to obtain a stress component of any pixel point of the image. The invention further discloses the stress measurement light path device for implementing the method. According to the present invention, a photoelastic method and a digital image correlation method are simultaneously carried out at the two sides of the sample to obtain the stress difference and the strain value of the whole field of the sample, so that the methods can be used for the sample with asymmetric loads, and the measurement applicability is greatly enhanced.

Description

technical field [0001] The invention relates to the technical field of stress measurement, in particular to a stress measurement method and a stress measurement optical path device in which a photoelastic method and a digital image correlation method are used in parallel. Background technique [0002] Photoelastic stress separation methods include numerical method, experimental method and hybrid method. Oblique shot method, strip method and stripe coating method and scribing method; hybrid method is mainly based on various methods of equal sum line method and photoelastic-infrared thermal imaging method and recently appeared photoelastic-digital image correlation method . The initial stress calculation value of the shear stress difference method starts from the free boundary, and the stress value of a point in the model is calculated numerically. If there is a large error between the initial value and the actual value, for example, if the model boundary is machined, there a...

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Problems solved by technology

However, analyzing the source of the experimental error, it can be found that although the experiment assumes that the loads on both sides are evenly distributed, which is reasonable, it is actually required that the boundary line between the speckle pattern and the photoelastic part made on the model before the experiment is perpendicular to the shape of the model The bisectors coincide, otherwise errors are likely to occur

[0007] The existing photoelastic and digital speckle mixed two-dimensional stress measurement method proposed by Li Bin and Yang Guobiao needs to find the middle dividing line on the surface of the sample. The dividing line is perpendicular to the optical axis of the photoelastic method, and the two sides of the dividing line are respectively Make photoelastic coatings and digital speckle coatings; or make samples with photoelastic materials, and then digital speckle coatings on the side of the middle dividing line of the samples, the principal stress difference and digital speckle obtained by the photoelastic method The strain value obtained by the method can be used to obtain the strain component of the whole field. The main defects of the existing method are: (1) It is necessary to find the middle boundary line of the sample on the surface of the sample, and obtain the photoelastic image and For speckle images, whether the division of the boundary line is accurate will affect the accuracy of the calculation; (2) it can only be used in the case where the load on both sides of the boundary line is symmetrical with the boundary line as the axis of symmetry, and cannot be used for asymmetrical loads on both sides of the boundary line situation, limited applicability

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