13 research outputs found
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Accuracy and Mechanical Properties of Open-Cell Microstructures Fabricated by Selective Laser Sintering
This paper investigates the applicability of selective laser sintering (SLS) for the manufacture of
scaffold geometries for bone tissue engineering applications. Porous scaffold geometries with
open-cell structure and relative density of 10-60 v% were computationally designed and
fabricated by selective laser sintering using polyamide powder. Strut and pore sizes ranging from
0.4 - 1 mm and 1.2 -2 mm are explored. The effect of process parameters on compressive
properties and accuracy of scaffolds was examined and outline laser power and scan spacing
were identified as significant factors. In general, the designed scaffold geometry was not
accurately fabricated on the micron-scale. The smallest successfully fabricated strut and pore size
was 0.4 mm and 1.2 mm, respectively. It was found that selective laser sintering has the potential
to fabricate hard tissue engineering scaffolds. However the technology is not able to replicate
exact geometries on the micron-scale but by accounting for errors resulting from the diameter of
the laser and from the manufacturing induced geometrical deformations in different building
directions, the exact dimensions of the manufactured scaffolds can be predicted and controlled
indirectly, which corresponds favorably with its application in computer aided tissue engineering.Mechanical Engineerin
Powder bed generation in integrated modelling of additive layer manufacturing of orthopaedic implants
This paper presents an original model of powder
bed generation developed within the frame of an integrated
modelling approach for studying the interaction of physical
mechanisms in additive layer manufacturing (ALM) of orthopaedic implants. The model is based on cellular automata (CA) approach and describes the relationship between moving particles of different sizes during deposition on a surface in three dimensions. The surface is defined by the horizontal two-dimensional CA on which particles fall and irreversibly stick to a growing deposit. The model allows for consideration of different restructuring cases when particles are allowed to rotate as often as necessary until achievement of a local minimum
position. Changes in the packing density of the powder
bed have been investigated numerically depending on technological parameters, such as particle size distribution, deposition rate and sequence of powder deposition. The model has been developed with the aim of merging to the finite element (FE)-based integrated model and is applicable to a different ranges of materials including metals and also non-metals