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Title: The mechanical and magnetic behaviour of sintered fibre networks and their suitability for a therapeutic, biomedical application
Author: Bosbach, Wolfram A.
ISNI:       0000 0004 6058 6971
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2015
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Background: Sintered, metallic fibre networks have been used in the design of a range of technical devices in the past years (e.g. heat exchangers or catalysts). One potential application in the field of therapeutic, biomedical engineering is the magnetic-mechanical stimulation of bone growth around prosthetic implants after joint replacement surgery. The loosening of prosthetic implants in the human bone is one of the current research topics of prosthesis design. Objectives and motivation: The present study aims at improving the understanding of the architecture of sintered fibre networks and their behaviour under mechanical, or magnetic actuation. The strain field imposed on a bone matrix in the void network phase is the final focus of the study. Materials and methods: To achieve the described objectives, 3D scans of sintered, cube-shaped fibre network samples made from AISI 316L or 444 stainless steel were acquired by means of computed tomography. Based on the finite element method and beam theory, the extracted network geometries were run as simulation models locally or on the Cambridge High Performance Computing Cluster Darwin. Results and conclusions: The obtained results show that the properties of material architecture or material mechanics are not constants. Instead, they rather have to be treated as functions of parameters such as the manufactured fibre volume fraction, of the available sample size, or of the applied boundary conditions. The results from the linear, elastic simulation under mechanical actuation were validated by experimental data. The obtained results identified the material as being transversely isotropic, the influence of the fibre segment tortuosity on the material’s Young’s modulus, or fibre deflection (instead of fibre elongation) as the dominating deformation mechanism within the fibre network samples. The size of the representative volume element could be determined, which showed a particular dependency on the applied boundary conditions. Under magnetic actuation, regions of tension, shear, and compression were obtained for the investigated samples, with strain peaks located in the free corners of the sample cubes. The obtained deformation of an inserted bone matrix confirmed that values, sufficiently large for the intended bone growth stimulation, are achievable under realistic conditions, with matrix strain peaks in the immediate proximity to the fibre structure.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: catalysts ; fibre segment tortuosity ; fibre networks