Like Digital Image Correlation (DIC) which is restricted to surface measurements, DVC calculates displacements in a complete 3D volume. Over one million displacement vectors per volume can be analyzed. StrainMaster DVC software from LaVision imports images from X-Ray CT, MRI scans, or optical tomography set-ups, and is able to quantify defects or discontinuities before they become visible in the volume image. DVC requires volume images contain a random pattern; local changes in contrast due to changes in density or voids in the case of X-ray CT scans (example in figure 1). DVC applications include biological research, metal powders, concrete structures, and composites. Dr Jürgen Adam (Royal Holloway University London), Dr. Klinkmüller and Dr Schreurs (Bern University) have used DVC in experiments simulating geological deformation in the earth crust, and non-linear fault and fracture formation in brittle rocks. Having previously utilised DIC to monitor surface displacements of sand-box experiments, they are now successful in applying DVC to the analysis of X-Ray Tomography volume images. An excerpt of the impressive results is shown in figure 2.

Fig 1: Experiment scan of reference (lower) and deformed (upper) states with interrogation sub volumes illustrated

Fig 2: Results showing displacement vectors and shear strain isocontours at conjugate fault zones