A torsional axis measurement method based on the adaptive window shape DIC

Abstract

Torsion test is one of the most basic tests in material mechanics, which can reflect the static and dynamic properties of materials. Torsional deformation measurement, as a key technology in torsion test, has received more and more attention in the field of mechanical engineering. Although there have been many measurement methods for measuring torsional deformation, these methods suffer from various disadvantages. To realize the torsion measurement of large torsional deformation, this paper proposes a torsion measurement method based on the Digital Image Correlation (DIC) method, which has the advantages of full-field, large-scale, and non-contact measurement. First, to solve the de-correlation problem caused by large torsional deformation, this paper proposed an adaptive window shape based DIC method, which adaptively changes the window shape with the torsion of the specimen to ensure the correlation between the reference and deformed sub-region at a high level. Second, the monocular camera was used to photograph the specimen from six directions to obtain six reference images, and the reverse matching method was used to overcome the problem of tracking points moving out of the camera's field of view. Experiment shows that, the adaptive window shape based monocular DIC method can effectively measure the large torsional deformation.