Modeling of time dependent localized flow shear stress and its impact on cellular growth within additive manufactured titanium implants.
Bottom Line: The model's effectiveness is demonstrated for two additive manufactured (AM) titanium scaffold architectures.The results demonstrate that there is a complex interaction of flow rate and strut architecture, resulting in partially randomized structures having a preferential impact on stimulating cell migration in 3D porous structures for higher flow rates.This novel result demonstrates the potential new insights that can be gained via the modeling tool developed, and how the model can be used to perform what-if simulations to design AM structures to specific functional requirements.
Affiliation: Department of Materials, Imperial College London, London, SW7 2AZ, UK.Show MeSH
Related in: MedlinePlus
Mentions: Figure 4 shows selected 2D cross sectional views of the velocity and shear stress distributions from central slice of the 3D model for both the (a) regular and (b) 30% randomized structures when the inflow velocity is 0.02 mm/s. In the regularly ordered implant structure, higher velocity flow occurs in the narrow channels with weak flow in the open channel [labeled as region ‘(N)' in Figure 4(a)]. The shear stress is almost zero in ‘(N)' regions. The maximum values of velocity along the flow direction within the regular (0.13 mm/s) and randomized structures (0.16 mm/s) exhibit a difference of 23.1%. The average velocity throughout the entire structure is also compared: the 30% randomized structure has a higher average velocity value of 22.7% greater than that of the regular structure at the final stage of growth. Higher shear stress values are seen at the locations where the changing in velocity is significant. The maximum value of shear applied on the solid in the randomized structure is 3.4 times greater than the regular. Note that we ran a CFD simulation in Fluent on same structures without cells to validate the initial stage results, and the overall pressure changes and velocities agreed with each other within experimental error.
Affiliation: Department of Materials, Imperial College London, London, SW7 2AZ, UK.