Ανάπτυξη ψηφιακών εργαλείων για το σχεδιασμό και την κατασκευή κομματιών μεταβλητής πυκνότητας με τη μέθοδο της εξώθησης υλικού της προσθετικής κατασκευής
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Keywords
3D printing ; Εξώθηση υλικού ; Ετερογεννή δομή ; VoxelAbstract
Additive Manufacturing is a relatively new class of manufacturing methods that were
developed at the end of the 20th century. What, in practice, differentiates Additive
Manufacturing methods from standard/conventional manufacturing methods, is their ability to
efficiently handle morphological and structural complexity. In the context of the present thesis,
the issues concerning the design and fabrication of the manufacturing of heterogeneous
structures/objects, i.e. objects with locally defined density and composition, by thermoplastic
material extrusion are examined. Three main research questions were identified: a) the
fabrication of a heterogeneous structure at the layer level by a single deposition path without
interruptions, b) the fabrication of a heterogeneous structure at the object level without the use
of internal supporting structures, and c) the fabrication of heterogeneous structures using two
materials. To address the above issues, two methodological approaches were developed, the
point cloud approach and the grid approach. In the first approach, a cloud of points is aptly
distributed at the layer level based on the corresponding bitmap image, and the deposition path
is subsequently designed, by defining the visiting sequence of the points through Traveling
Salesman Problem optimization techniques. In the grid approach, heterogeneous objects are
represented by voxels, which are assigned specific density and/or composition values. The
voxels are broken down into sub-elements (laminae, cells and tiles), which are then used to
design layer-by-layer deposition paths by joining elementary paths of standard or semi-random
shape. Computational and fabrication tests of the developed methodological approaches and
algorithms showed that the computational burden is not particularly high, and that it is possible
to design and manufacture complex heterogeneous structures/objects satisfying the basic
constraints of a single and uninterrupted path per layer and the absence of internal supporting
structures. According to the results of the study, it is also possible to extend the specific
methodology to two materials, following the appropriate adjustments. Achieving, however,
uninterrupted paths for both materials faces more constraints and can only be achieved under
conditions. Interesting topics for further research, identified during the study, are the
development of methods to smooth the deposition path by reducing the number of turning
points and the application of the developed methodological techniques employing various
material combinations and different Additive Manufacturing technologies