Half sub region relevant optical measurement method of strain field in strain localization zone

Abstract

The invention provides a half sub region relevant optical measurement method of a strain field in a strain localization zone. An image of one surface of an object in a loaded process is collected; the displacement and the strain of each measuring point on the image and the inclination angle of the strain localization zone to be measured are obtained; two parallel measuring lines are arranged in the normal direction of the strain localization zone to be measured; a plurality of measuring points are arranged; the coordinates and the displacement of the measuring points simultaneously positioned on the measuring line and the starting boundary line of the strain localization zone to be measured are obtained; the coordinates and the displacement of the measuring points with the distance being a half of the distance of the measuring lines are determined inside and outside the strain localization zone to be measured; the strain of a rectangular pixel block is calculated; the distribution rule of the strain field inside the strain localization zone to be measured is obtained. The time-space distribution rule of the strain field in the strain localization zone can be better measured; the strain distribution in the strain localization zone obtained through measurement is smooth, continuous and accurate; the measurement precision of the inside strain field in the strain localization zone is improved; the wide application is realized in the field of solid experimental mechanics.

Description

technical field [0001] The invention relates to the technical field of optical measurement, in particular to a semi-sub-area correlation optical measurement method of a strain field in a strain localized band. Background technique [0002] Strain localization is the observed concentration of strain in narrow band-like regions prior to material failure. Strain localization precedes macrocracks and is one of the important precursors to failure in materials. By studying the spatio-temporal distribution of the strain field inside the strain localized zone, it is helpful to deeply understand the deformation, failure and instability mechanism of the material, and to propose various criteria, which can also provide the necessary basic parameters for the relevant analytical and numerical models. Or to test the correctness of these models. [0003] In the past, the spatio-temporal distribution of strain inside the strain localized zone was usually obtained from the strain field nep...

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Problems solved by technology

[0005] 1) The digital image correlation method based on the Newton-Raphson (N-R) method can obtain the displacement and strain in the object plane at the same time, but the error of the strain calculation result is relatively large;

[0006] 2) The digital image correlation method based on the central difference method obtains the strain field by performing central difference on the displacement field, but the noise contained in the displacement field will reduce the credibility of the strain calculation results

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