An Alternative Digital Volume Correlation Method Based on Displacement Gradient Decomposition

Abstract

The invention discloses an ectopic digital volume correlation method based on displacement gradient decomposition. The ectopic digital volume correlation method based on displacement gradient decomposition comprises the following steps that primary three-dimensional imaging is conducted on a sample so as to obtain three-dimensional image data G1 (x, y, z) before the sample is deformed; ectopic deformation is conducted on the sample, secondary three-dimensional imaging is conducted on the deformed sample so as to obtain three-dimensional image data G2 (x, y, z) after the sample is deformed; a displacement field u (x, y, z) between the three-dimensional image data G1 (x, y, z) before the sample is deformed and the three-dimensional image data G2 (x, y, z) after the sample is deformed is calculated by means of DVC, and the displacement field u (x, y, z) comprises a rigid displacement field uR (x, y, z) and a deformation displacement field uD (x, y, z); a displacement gradient T (x, y, z) is calculated out by means of the displacement field u (x, y, z); a deformation displacement gradient D (x, y, z) and a rotation displacement gradient R (x, y, z) are calculated with a displacement gradient decomposition method; the rigid displacement field uR (x, y, z) is calculated by means of the rotation displacement gradient R (x, y, z) and boundary conditions; the deformation displacement field uD (x, y, z) is calculated by means of the displacement field u (x, y, z) and the rigid displacement field uR (x, y, z), and the deformation displacement field uD (x, y, z) of the sample is a three-dimensional displacement field after the sample is deformed in situ. The ectopic digital volume correlation method based on displacement gradient decomposition not only overcomes difficulties of in-situ on-line experiments in an in-situ digital volume correlation method, but also has a high degree of accuracy and high precision.

Description

technical field [0001] The invention relates to a dislocation digital volume correlation method based on displacement gradient decomposition, which belongs to the field of material structure deformation measurement. Background technique [0002] The digital volume correlation method (English full name: Digital Volume Correlation, abbreviation: DVC) is based on the digital image correlation method (English full name: Digital Image Correlation, abbreviation: DIC), which was proposed by B.K.Bay et al. in 1999 at the University of California, USA. , (Bay B K, Smith T S, Fyherie D P, et al.Digital volume correlation: Three-dimensional strain mapping using X-ray tomography[J].Experimental Mechanics, 1999, 39(3):217~226), can use sample deformation The two sets of three-dimensional images before and after are correlated to obtain the three-dimensional displacement field of the sample deformation, and then the experimental method of calculating the three-dimensional displacement fie...

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Problems solved by technology

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide a dislocation-based digital volume correlation method based on displacement gradient decomposition, which solves the difficulty in the operation of the in-situ digital volume correlation method and its application limitations

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