RESUMO
Background: Additive Manufacturing due to its benefits in developing parts with complex geometries and shapes, has evolved as an alternate manufacturing process to develop implants with desired properties. The structure of human bones being anisotropic in nature is biologically functionally graded i,e. The structure possesses different properties in different directions. Therefore, various orthopedic implants such as knee, hip and other bone plates, if functionally graded can perform better. In this context, the development of functionally graded (FG) parts for orthopedic application with tailored anisotropic properties has become easier through the use of additive manufacturing (AM). Objectives: and Rationale: The current paper aims to study the various aspects of additively manufactured FG parts for orthopedic applications. It presents the details of various orthopedic implants such as knee, hip and other bone plates in a structured manner. A systematic literature review is conducted to study the various material and functional aspects of functionally graded parts for orthopedic applications. A section is also dedicated to discuss the mechanical properties of functionally graded parts. Conclusion: The literature revealed that additive manufacturing can provide lot of opportunities for development of functionally graded orthopedic implants with improved properties and durability. Further, the effect of various FG parameters on the mechanical behavior of these implants needs to be studied in detail. Also, with the advent of various AM technologies, the functional grading can be achieved by various means e.g. density, porosity, microstructure, composition, etc. By varying the AM parameters. However, the current limitations of cost and material biocompatibility prevent the widespread exploitation of AM technologies for various orthopedic applications.
RESUMO
Fused deposition modelling (FDM) is a popular but complex additive manufacturing process that works with many process parameters which are crucial to investigate. In this study, 3D parts were fabricated by placing each filament layer in opposite direction to the others; for this, two combinations of raster angles, (45° -45°) and (0° 90°), along with three different infill speeds were used. In this study, two 3D printing material types-Polylactic Acid (PLA) and tough-PLA were used. The material properties of each 3D part were investigated to identify the best combination of these parameters. A microstructural analysis was also performed on outer and inner surfaces along with fracture interface of the parts after tensile testing using a scanning-electron-microscopy (SEM) to explain material failure modes and reasons. The results suggest that for both the material types, a raster angle of 45° -45° produces stronger parts than to a raster angle of 0° 90°. This study also suggests that a slow infill speed improves tensile properties by providing a better inner-connection between two contiguous roasters. Thus, the detailed analysis of microstructural defects correlated with tensile test results provides insight into the optimisation of raster angle and infill speed, and scope for improvement of mechanical properties.