LaVision\'s state-of-the-art Digital Volume Correlation (DVC) software brings new depth to quantitative imaging analysis. DVC is not only capable of identifying defects and cracks before they are visible in the raw image, but it is also able to quantify the full volume strain distribution and actual magnitudes of the material displacements surrounding discontinuities. The level of information is extremely useful in validating Finite Element models of modern complex materials. Volume images can be imported into the software from a variety of sources such as:
X-Ray Computed Tomography
Magnetic Resonance Imaging (MRI)
Optical Coherence Tomography (OCT)
Confocal Microscopy
Relating to the volume shown in the figure below, this sequence is a scan in the z direction showing image slices with corresponding calculated vector and strain planes. Data courtesy of Dr K. Madi / Prof J. Tong (University of Portsmouth) et al., presented at ECCOMAS – Int Conference on Tissue Engineering 2011, Lisbon.
DVC tracks the displacement of the material structure pattern within the volume images. The algorithms used are extremely robust in terms of the appropriateness of the pattern type and DVC has successfully been applied to many materials.
Applications
metallic foams
carbon composites
powders and granular materials
nuclear graphite
biological materials including bone and synthetic cornea
geological simulations
3D representation of scaffold implant used for cartilage repair obtained using micro-computed tomography.
Calculations are performed quickly and efficiently with full volume displacement fields typically calculated in less than 5 minutes. The software includes many useful features including visualisation of the volume correlation peak, and the ability to correct for rigid body displacements; essential where samples are removed from the imaging device to be loaded. Advanced masking also means that it is possible to isolate the complex material shapes from noisy background levels even if it includes complex three-dimensional curvature - quite often the case in biological applications.
Features
local displacement precision better than 0.05 voxels
local strain precision better than 0.1%
ability to calculate very large images only limited
by PC RAM
able to yield over 1 million displacement vectors per volume image pair
DVC has proved invaluable to LaVision customers in revealing a wealth of information about the previously immeasurable sub-surface displacements. DVC is the only experimental technique available to quantify these phenomena and is becoming a critical part of experimental mechanics analysis.
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