Digital Imaging Correlation
Digital Image Correlation work was carried out using the Composite Research Centre (CRC) facilities, which consist of 3D DIC strain and deformation analysis consisting of 2x Imager E-lite 2M cameras including 50mm/f2.8 c-mount lenses, 1600 x 1200 pixel spatial resolution, and Davis StrainMaster software from LaVision (Grove, Oxfordshire, OX12 9FF, U.K).
Digital image correlation (DIC) is a practical and effective optical technique for surface deformation measurement. By processing the digital images of a test object’s surface recorded by an imaging device, typically a CCD camera, before and after deformation, DIC directly provides full-field displacements of the object surface to sub-pixel accuracy, and strains can be calculated directly or by further manipulations of the displacement. The basic principle of DIC is to match or track the same physical points imaged in the reference image and the deformed image.
Figure 1: 3D Layout of DIC cameras
These techniques were used to determine the local strain variations in the vicinity of localised pathologies such as aortic aneurysms to provide important information regarding how local changes in vessel structure or composition alter the biomechanical response and mechanical properties. Similarly the technique has been applied for extracellular matrix (ECM) material, to assess local strains of this anisotropic material, under physiological conditions.
Figure 2: Aortic Specimen, showing speckle for DIC
Figure 3: Decellularised ECM Specimen, showing speckle for DIC