Computation of full-field displacements in a scaffold implant using digital volume correlation and finite element analysis

Abstract

Measurements of three-dimensional displacements in a scaffold implant under uniaxial compression have been obtained by two Digital Volume Correlation (DVC) methods, and compared with those obtained from micro-finite element models. The DVC methods were based on two approaches, a local approach which registers independent small volumes and yields discontinuous displacement fields; and a global approach where the registration is performed on the whole volume of interest, leading to continuous displacement fields. A customised mini-compression device was used to perform in situ step-wise compression of the scaffold within a micro-computed tomography (µCT) chamber, and the data were collected at steps of interest. Displacement uncertainties, ranging from 0.006 to 0.02 voxel (i.e.0.12 to 0.4 μm), with a strain uncertainty between 60 and 600 με, were obtained with a spatial resolution of 32 voxels using both approaches, although the global approach has lower systematic errors. Reduced displacement and strain uncertainties may be obtained using the global approach by increasing the element size; and using the local approach by increasing the number of intermediary sub-volumes. Good agreements between the results from the DVC measurements and the FE simulations were obtained in the primary loading direction as well as in the lateral directions. This study demonstrates that volumetric strain measurements can be obtained successfully using DVC, which may be a useful tool to investigate mechanical behaviour of porous implants.

Elastic stiffness characterization using three-dimensional full-field deformation obtained with optical coherence tomography and digital volume correlation

“…40 In the case of the FFT-based DIC algorithm used here, the period of the oscillation due to interpolation bias corresponds to a displacement equivalent to 2 voxels. [44][45][46] This is consistent with 2.5 fringes observed in Fig. 8(b) for a total deformation corresponding to 5 voxels.…”

Three-dimensional deformation mapping of Mode I interlaminar crack extension in particle-toughened interlayers

“…Given that the vector fields have been shown to be incorrect in this case, the strain resolution will be evaluated from the stationary and y-displaced scans. Previous studies have shown that any rigid body translation tests will cause an increase in strain standard deviation because of the additional errors from the interpolation biases due to the specimen movement [30], [26]. Although this is true for the z-displaced results, the y-displaced values are consistently lower than the stationary tests.…”

About the inevitable compromise between spatial resolution and accuracy of strain measurement for bone tissue: A 3D zero-strain study

“…Yet, another approach that combines repeated µCT images and digital volume correlation (DVC) techniques has been developed recently to study the mechanical behaviour of whole vertebrae (Hussein et al, 2012), trabecular bone (Bay et al, 1999;Bremand et al, 2008;Gillard et al, 2014;Liu and Morgan, 2007;Zauel et al, 2006), scaffolds (Madi et al, 2013) and bone implant interface (Basler et al, 2011). These deformable registration approaches can provide an estimation of the distribution of displacements and strains between two 3D images of the sample before and after a certain deformation is applied.…”