On the Evaluation of Volume Deformation from Surface DIC Measurements

摘要

Stereo DIC allows to measure with a good accuracy the displacement field and the shape changes of the surface of objects during deformation processes. Moreover, using multiple cameras makes possible to measure the deformation of the whole surface of the object in 360°. Such boundary information can be exploited to compute the internal displacement of a solid object using interpolation functions, especially if the deformation is large. This can be applied, for instance, to investigate the strain localization that occurs in metal specimen subjected to plastic deformation, and to study the necking initiation and the fracture development. In this paper, an interpolation method based on Bezier curves is developed and tested using simulated experiments on specimen with different shape. In particular, a flat and a round specimens are studied, looking at the deformation in the necking zone. The accuracy of the interpolation algorithm is evaluated at different level of deformation using both isotropic and anisotropic materials. Examples on real measurement are also discussed.