Effect of the Grid Step of the Vector Displacement Field on the Strain Estimate in the Digital Image Correlation Method
S. V. Panin1,2, V. V. Titkov1, P. S. Lyubutin1,2
1Institute of Strength Physics and Material Science, Siberian Branch, Russian Academy of Sciences, Tomsk, 634055, Russia
2National Research Tomsk Polytechnical University, Tomsk, 634050, Russia
Keywords: поле векторов перемещений, шаг сетки, корреляция цифровых изображений, погрешность оценки деформации, текстура, шум Гаусса, displacement vector field, grid step, digital image correlation, strain error estimate, texture, Gaussian noise
Abstract
The influence of the grid step of the displacement vector field on the strain estimate in the digital image correlation method is considered. The reasons for the emergence and the magnitude of the strain estimate error in processing optical images of material surfaces with different textures are analyzed. The dependence of the grid step for strain estimation on the magnitude of displacements and also on the presence and size of the discontinuity region in the strain field is studied. An adapted algorithm for choosing the grid step is proposed, which allows the strain calculation error to be reduced by a factor of 1.9 with simultaneous reduction of computational expenses by a factor of 2.1.
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