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Title: Three dimensional characterization and multi-scale modelling of deformation in biomaterials
Author: Yan, Liye
ISNI:       0000 0004 7971 7169
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2019
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Mollusc shell and bone are two interesting materials with complicated morphological geometries and hierarchical microstructures, which present a good combination of stiffness, strength and toughness and therefore attract interests of researchers from engineering and clinic fields. In this work, in-situ mechanical tests during X-ray tomography have been done on common British limpet and bones (cortical bone and trabecular bone), which provide geometric and microstructural information for modelling. The 3-D displacement fields within deformed biomaterials have been extracted by digital volume correlation (DVC), which provides either boundary conditions for modelling or experimental comparison for simulated results. Different modelling approaches have been employed in order to provide a comprehensive understanding of mechanical properties of biomaterials. A value for the elastic modulus of the mollusc shell, which is consistent with literature, has been obtained using a finite element (FE) model with simple boundary conditions (experimental load) which incorporates the morphological information of limpet. Additional information of possible fracture sites within limpet have also been successfully predicted from the model, and the strain field within the deformed shell has been calculated using FE model with the 3D full displacement field from DVC analysis as boundary conditions. FE models of indentation tests on cortical bone have also been built which provide insight into the mechanical behavior of bone under indentation loading. A cellular model, PReMISe, which was designed for the prediction of elastic modulus of quasi-brittle and porous materials, has been employed in cortical bones. From this, the intrinsic elastic moduli of cortical bone have been obtained, with a good agreement with literature measurements by nanoindentation. To characterize the fracture resistance of trabecular bone, which has a very complex porous microstructure, in situ tomographs of a pre-notched test specimen were analysed to extract the averaged displacement fields from DVC to allow J integral calculation using the JMAN code. The obtained critical stress intensity factor (K) has a good agreement with literature.
Supervisor: Marrow, James Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available