A Deformation Measurement Method of Tensile Specimen Based on Digital Image Correlation

Abstract

The invention provides a tensile sample deformation measurement method based on digital image correlation. The tensile sample deformation measurement method mainly applies an image correlation method and combines a measurement method based on a standard surface to realize high-speed and high-precision measurement of a test sample. The tensile sample deformation measurement method comprises the following steps: 1, carrying out integer pixel positioning based on the image correlation; 2, carrying out sub pixel positioning based on two-dimension curved surface fitting; and 3, carrying out image mapping positioning based on the standard surface. The three steps are organically combined to form a main body of the whole method. The tensile sample deformation measurement method has the beneficial effects that a standard plane mapping method is combined by adopting a simplified digital image correlation method so that the test sample is prevented from being marked; an operation flow is simplified, the measurement speed and the precision of the deformation of the test sample are improved, and the practicability of the system is improved.

Description

technical field [0001] The invention belongs to the field of digital image measurement of material deformation, and in particular relates to a method for measuring deformation of tensile samples based on digital image correlation. Background technique [0002] At present, according to the current situation of video extensometer, the measurement of sample deformation can be mainly divided into three methods, namely clamping markers, marking method and measurement method based on the texture characteristics of the sample itself. [0003] At present, the method of adding markers on the surface of the sample is relatively common in the scientific research and product fields. Combined with the image edge method, a clear and high-contrast sample image can be obtained, and the deformation of the sample can be measured through the displacement of the marker. The image The interference is small and the processing speed is fast, but considering that the deformation between the markers...

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Problems solved by technology

[0003] At present, the method of adding markers on the surface of the sample is relatively common in the scientific research and product fields. Combined with the image edge method, a clear and high-contrast sample image can be obtained, and the deformation of the sample can be measured through the displacement of the marker. The image The interference is small and the processing speed is fast, but considering that the deformation between the markers does not really represent the deformation of the sample itself, and the blessing itself brings a lot of work to the staff, artificial marking points gradually came into being. The surface is marked with high-contrast marking points to achieve deformation measurement. However, on the one hand, the marking points will increase the complexity of the operation. On the other hand, the requirements for the marking points themselves are relatively high, and the marking points themselves will also be deformed during the stretching of the material. , leading to a decrease in tracking accuracy

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