Welding strain measurement system and method based on three-dimensional digital image correlation method

Abstract

The invention relates to a welding strain measurement system and method based on a three-dimensional digital image correlation method. The system comprises a first camera and a second camera which arerespectively mounted at two ends of a support holder in a translational manner, wherein a dimmer and a filter are respectively arranged in front of imaging lenses of the first camera and the second camera, a laser light source is arranged on the support holder between the first camera and the second camera, the first camera, the second camera and the laser light source are respectively connectedwith a control box, and the first camera and the second camera are respectively connected with a computer. Compared with the prior art, a digital image correlation method and a binocular stereoscopicvision technology are combined, full-field three-dimensional strain measurement is carried out in the welding process, the system can meet the requirements for welding three-dimensional full-field strain non-contact and high-precision measurement, and compared with a traditional method, the method has the advantages of being high in measurement precision, convenient to use, simple and compact in system structure and the like.

Description

technical field [0001] The invention relates to the field of welding strain measurement, in particular to a welding strain measurement system and method based on a three-dimensional digital image correlation method. Background technique [0002] Most of the research on welding deformation is based on finite element analysis, and the numerical simulation method is used to predict the welding deformation and strain of welded parts. This type of method generally has a low cost, but due to the complexity of the welding deformation mechanism, the difficulty of measuring material parameters at high temperatures, and other factors, the prediction results are quite different from the experiments. During the welding process, the deformation in the high temperature zone of the weld is the main cause of the residual strain, so it is necessary to study and measure the deformation law in the high temperature zone. Traditional measurement methods generally use high-temperature-resistant ...

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Problems solved by technology

However, these methods have the following disadvantages: (1) The strain gauge patch process is complicated, and the measurement result is a unidirectional average strain in a large area, while the displacement sensor can only be used for single-point, unidirectional measurement, which is difficult to measure The overall deformation field on the surface of the weldment: (2) technologies such as drilling, X-ray and neutron diffraction often require the help of more complex equipment in actual use; (3) visual measurement and laser scanning methods can only be used to measure The instantaneous displacement of finite points on the surface of the weldment during the welding process still cannot obtain the overall deformation field of the weldment surface

[0004] 1. Due to strong arc light interference, the brightness of the image collected by the industrial camera will increase significantly, which will reduce the image contrast, thereby reducing the accuracy of image matching, resulting in a large increase in the error of the final 3D strain field result;

[0005] 2. Severe uneven deformation during the welding process and a large range of strain changes during the welding process will also lead to a serious reduction in the accuracy of the measurement results;

[0006] 3. The high temperature during the welding process will cause the speckle generated by the commonly used speckle preparation method to slip, fall off and change color on the surface of the material

[0007] Therefore, the existing 3D digital image correlation methods cannot accurately obtain the 3D full-field strain during the welding process

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