On the generation and characterisation of internal micro-architectures
Raymont, David Richard
Date: 10 May 2011
Thesis or dissertation
Publisher
University of Exeter
Degree Title
PhD in Engineering
Abstract
Open cell micro-architectures are used in a large number of applications,
ranging from medical, such as bone scaffolds, to industrial, such as heat
transfer structures. Traditionally these structures are manufactured using
foaming processes, however advances in additive manufacturing (AM) now allow
such structures to be designed ...
Open cell micro-architectures are used in a large number of applications,
ranging from medical, such as bone scaffolds, to industrial, such as heat
transfer structures. Traditionally these structures are manufactured using
foaming processes, however advances in additive manufacturing (AM) now allow
such structures to be designed computationally and fabricated to a high degree
of precision.
In this thesis image-based methods are developed for the purpose of
generating periodic micro-architectures based on implicit representations.
The algorithms developed are shown to be efficient and robust, allowing for
the creation of both surface and volume meshes. Methods are presented for the
creation of functionally graded structures allowing for arbitrary variations in
density between specifiable volume fractions. These algorithms are further
extended for domain conforming applications as well as for internal structures
in CAD models. By utilising a hybrid approach, imaging techniques can be
exploited for the generation of internal structures in CAD models without
de-featuring the original external geometry. The structures of
interest are also shown to be manufacturable via selective laser melting (SLM).
The issue of characterisation, for linear elastic properties, is addressed
through the use of a novel homogenisation technique. Large multi-scale problems
in irregular domains are divided into smaller sub-volumes using established
tetrahedral volume meshing techniques. By performing a series of virtual tests
on these macroelements their effective properties can be computed and
subsequently used in macro-simulations. The technique is shown to yield results
in excellent agreement with the often used kinematic uniform boundary conditions
(KUBC). It is also shown how these properties may be used for visualising the
distribution in properties over a domain.
Doctoral Theses
Doctoral College
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