A study on compressive behaviour and biocompatibility of direct metal laser sintered Ti64 cellular structures

Abstract

Abstract The Direct Metal Laser Sintering (DMLS) process is widely used for biomedical applications and to fabricate Cellular Structures (CS). Titanium alloy (Ti64) CS were modelled as a honeycomb structure with variations in pore diameters (0.8 mm, 0.9 mm and 1.0 mm) and interpore distances (1.6 mm, 1.7 mm and 1.8 mm) in this research work. The maxillofacial region is considered for implementation of CS, with mandible being the selected application. Finite Element Analysis (FEA) was carried out on all CS models and the least von-mises stress was observed to be 48.67 MPa and the corresponding Young’s modulus was calculated to be 34.76 GPa. Based on FEA results, CS were fabricated through DMLS and tested for compressive behaviour. The average Young’s modulus was calculated to be 32.10 GPa, the average compressive strength was evaluated to be 51.25 MPa and the average strain energy was calculated to be 0.94 J, respectively. The FEA and experimental results were in correlation with each other. Since CS was able to withstand the required load for mandibular implant application, it can be considered as safe. The compressive behaviour of Ti64 CS was observed to be sensitive to varying rate of loading. A ductile fracture was observed upon fractography analysis and the CS exhibited a martensitic microstructure, which accounts for good compressive strength. The average surface roughness of the CS was measured to be 1.26 μm, which is within a suitable range of tissue growth for mandibular implant. The tissue culture was done to study the biocompatibility of CS and an increase in the percentage of cell viability was observed as 55% on day 1, 68% on day 3 and 75% on day 5, respectively.