Effect of Unit Cell Type and Pore Size on Porosity and Mechanical Behavior of Additively Manufactured Ti6Al4V Scaffolds

Abstract

Porous metal structures have emerged as a promising solution in repairing and replacing damaged bone in biomedical applications. With the advent of additive manufacturing technology, fabrication of porous scaffold architecture of different unit cell types with desired parameters can replicate the biomechanical properties of the natural bone, thereby overcoming the issues, such as stress shielding effect, to avoid implant failure. The purpose of this research was to investigate the influence of cube and gyroid unit cell types, with pore size ranging from 300 to 600 µm, on porosity and mechanical behavior of titanium alloy (Ti6Al4V) scaffolds. Scaffold samples were modeled and analyzed using finite element analysis (FEA) following the ISO standard (ISO 13314). Selective laser melting (SLM) process was used to manufacture five samples of each type. Morphological characterization of samples was performed through micro CT Scan system and the samples were later subjected to compression testing to assess the mechanical behavior of scaffolds. Numerical and experimental analysis of samples show porosity greater than 50% for all types, which is in agreement with desired porosity range of natural bone. Mechanical properties of samples depict that values of elastic modulus and yield strength decreases with increase in porosity, with elastic modulus reduced up to 3 GPa and yield strength decreased to 7 MPa. However, while comparing with natural bone properties, only cube and gyroid structure with pore size 300 µm falls under the category of giving similar properties to that of natural bone. Analysis of porous scaffolds show promising results for application in orthopedic implants. Application of optimum scaffold structures to implants can reduce the premature failure of implants and increase the reliability of prosthetics.

The manufacturability and compression properties of the Schwarz Diamond type Ti6Al4V cellular lattice fabricated by selective laser melting

“…Published studies concern regular lattice-based geometries and only some concern the TPMSbased geometries. For example, Zaharin et al [38] investigated the gyroid scaffold with pore sizes ranging from 300 to 600 μm and total porosity of 70.2-81.1%. The compression strength was in the range 23-11.5 MPa.…”

Role of implants surface modification in osseointegration: A systematic review

“…The well-recognized minimum pore size needs to be 100 μm, which allow the generation of mineralized bone and migration of osteocyte (Sundelacruz & Kaplan, 2009). Most of the studies claimed that pores sized between 100 μm and 400 μm were favorable for OI (Tsuchiya et al, 2008;Zaharin et al, 2018). Although the increase of pore size can reduce Young's modulus and yield strength, it can also decrease the stiffness and strength of implants (Ran et al, 2018).…”

“…Although the increase of pore size can reduce Young's modulus and yield strength, it can also decrease the stiffness and strength of implants (Ran et al, 2018). Most of the studies claimed that pores sized between 100 μm and 400 μm were favorable for OI (Tsuchiya et al, 2008;Zaharin et al, 2018). However, Taniguchi et al evaluated the effect of different pore sizes (300, 600, and 900 μm) on in vivo bone ingrowth in rabbits.…”

Corrosion Behaviors of Selective Laser Melted Aluminum Alloys: A Review

“…Growing attention has been paid to 3D printing due to the significant advantages it offers in manufacturing products with complex structures without extra machining processes [1][2][3]. As 3D printing can produce components with complex geometries, which are needed in many industries, it is widely used to produce various metallic parts, made from different metals, including aluminum alloys [4], titanium alloys [5,6], steels [7][8][9], nickel alloys [10,11] and shape memory alloys, [10,12]. Mehrpouya et al summarized in their review that 3D printing exhibits enormous market potential in industry 4.0 due to its significant advantages, such as time and materials saving and high design freedom [13].…”