Ridge regression strain measurement method with initial value in digital image correlation

Abstract

The invention discloses a ridge regression strain measurement method with an initial value in digital image correlation, and belongs to the fields of experimental mechanics, non-contact full-field strain measurement and digital image correlation, and the method comprises the steps: firstly, building a digital image correlation measurement system, and obtaining digital images before and after deformation of a test piece; dividing grid units and nodes of the image, selecting feature points in the units, and obtaining displacement and strain of the feature points through a digital image correlation method; calculating the average value of the strain of each feature point in the unit; selecting a displacement function type in the unit, performing ridge regression on the displacement field in the unit by taking the strain average value as an initial value, and fitting to obtain the displacement field in the unit; and interpolating the strain of each unit to obtain full-field strain. According to the invention, the strain measurement precision and robustness of a digital image correlation method can be improved.

Description

technical field [0001] The invention relates to experimental mechanics, non-contact full-field strain measurement and a digital image correlation method, in particular to a ridge regression strain measurement method with an initial value in the digital image correlation. Background technique [0002] In many fields such as aerospace and building bridges, ensuring structural reliability is always the top priority. With the development of science and technology, it has become an important goal of many scientists to control and repair structures before irreversible damage occurs. The measurement results of material response load characterization provided by experimental mechanics have rich guiding significance for perfecting design, improving structure and monitoring damage. Displacement and strain, as important parameters of experimental mechanics, play a pivotal role in analyzing the mechanical properties of models, verifying basic assumptions, and identifying features. In ...

AI Technical Summary

Problems solved by technology

However, in the actual DIC measurement process, due to many reasons such as noise and pixel interpolation errors, there are certain errors in the displacement measurement results.

When the strain is differentially calculated from the displacement measurement results, the error in the displacement field will be further amplified, resulting in inaccurate strain measurement results

Relevant researchers have proposed a variety of displacement field smoothing methods to improve the accuracy of strain calculations, but most of them have complex mathematical forms or greatly increase the amount of calculation, which limits practical applications

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