ИСПОЛЬЗОВАНИЕ МЕТОДА КОРРЕЛЯЦИИ ЦИФРОВЫХ ИЗОБРАЖЕНИЙ ДЛЯ ИЗМЕРЕНИЯ ЛОКАЛИЗОВАННОЙ ДЕФОРМАЦИИ НА ПРИМЕРЕ ДВОЙНИКОВАНИЯ МАГНИЯ И ПОЛОС СДВИГА В МЕТАЛЛИЧЕСКОМ СТЕКЛЕ

Abstract

Digital image correlation (DIC) method is widely used all over the world when solving various tasks such as the control and monitoring of vibration of bridges, wind-power generators, snowslides, following the objects transfer in security systems and crash-tests, measuring local deformations and their distribution within the objects of various scale-levels, from micro- up to macro-. This paper covers the solution of the last specified problem, which is the measuring of deformation fields formed in the result of localized deformation using the DIC method. As the objects of the research, the authors selected such phenomena as the shear bands production in metallic glasses and the twinning in magnesium, actively discussed by the academic community nowadays. The authors carried out the mechanical testing of samples with video-registration of the deformable surface and followed up the procedure of sample surface preparing, and data getting and processing using the DIC method. The deformation fields on the surfaces of metallic glass and magnesium samples are measured. It is shown, that the experimentally measured field of displacement around the shear band apex to a high accuracy matches the theoretically calculated dislocation field in the isotropic material. The authors identified that the deformation field of magnesium sample changes the morphology asymmetrically during the load reversal and the local deformation amounts up to 20 % when twinning magnesium. The application of sub-pixel algorithm allowed achieving the resolution that is two orders greater than the resolution of the optical system used in the study. The authors concluded on the DIC method high efficiency when studying microdeformation of materials, including the deformation events on the example of shear bands and a twin.