Optimization Approaches for the Design of Additively Manufactured Scaffolds - Tissue Engineering: Computer Modeling, Biofabrication and Cell Behavior - page 120

Fig. 5 Stiffness values for structures obtained according to a given LASA pattern as a function of
porosity. The stiffness of solid body is presented as a reference
in combination with different porosity levels and pores dimensions. Thus, starting
from a given LASA solution, an optimization process can be carried out, modifying
design parameters until a good compromise among trabecular diameter (constrained
by the additive manufacture equipment), scaffold porosity and stiffness (related to
the specific tissue application), has been reached.
Three different LASA structures with different porosity (78 %, 61 % and 32 %)
were generated keeping constant the number and spacing of the trabecular elements,
while setting the thickness to 200, 400 and 800 µm, respectively. 2D CAD geome-
tries were imported in COMSOL and stiffness was calculated according to Eq. ( 3 ).
Figure 5 shows the different stiffness achieved by these geometries. A solid model
with dimensions corresponding to the continuum C has been added for comparison
reasons. As expected, stiffness increases with increasing fibers thickness approach-
ing the value assumed by the continuum solid geometry.
As an additional simulation, LASA structures were generated with different tra-
becular thickness (200, 400 and 800 µm), but keeping constant the total porosity
value, by changing number and spacing of the fibers. In these conditions, although
the cross section of each trabecula was increased, the reduction in the number of
load-bearing elements resulted in an overall decrease of stiffness values (Fig. 6 ).
Taken together, these considerations suggest that the proposed LASA approach
could provide a useful tool in designing tissue scaffolds with tailored morphology
and mechanical behavior.
2.1.3 Model Application
In view of a possible application to the fabrication of scaffolds for TE, the proposed
technique has been evaluated on a clinically relevant anatomic portion.