TECHNIQUES

Digital Image Correlation

Digital Image Correlation (DIC) effectively tracks the movement of the naturally occurring, or applied surface pattern during the test or experiment. This is done by analysing the displacement of the patterns within discretised subsets or facet elements of the whole image. The maximum correlation in each window corresponds to the displacement, and this gives the vector length and direction for each window. Advanced algorithms use multi-pass processing, window deformation, and the possibility of non-square subsets to maximise the sub-pixel accuracy. 





The user acquires a series of images during a material testing experiment, with the first image normally being the case of zero applied load. With standard single camera or stereoscopic multi camera setups, 2D in-plane deformation or full 3D surface measurements are achieved. Local derivative calculations give the strain tensors across the entire surface, and a standard feature of StrainMaster is the ability to place a virtual strain gauge anywhere on the sample surface after the test, giving incredibly accurate strain data.

StrainMaster from LaVision offers a DIC system that is appropriate for many applications; small or large scale, and long term or ultra-fast dynamic tests. We also offer a special volume correlation upgrade for the analysis of tomographic images for full 3D analysis of internal material structures