Precise strain measurement in complex materials using Digital Volumetric Correlation and time lapse micro-CT data

AbstractDigital volumetric correlation (DVC) method can be employed for evaluation of full-volume displacement and strain fields in deformed material with clearly recognizable microstructure. This microstructure can be defined by complex inner geometrical topography, as trabecular bone and metal foam have for instance, or/and by significant variations of chemical composition, as aluminum grainy alloys have for instance. Volumetric image data were acquired using time lapse X-ray micro-CT during gradually specimen loading. Tetrahedral FE mesh was generated describing related volumetric data. The displacement fields were measured in set of control points by DVC utilizing vertices of this tetrahedral FE mesh. The advantage of the approach is that the resulting strain can be directly compared with FE simulation of the experiment. Problems of accuracy, especially in evaluation of the strain field from the noisy measured displacements and problems of computational efficiency of the method are discussed