Abstract
The topology optimization (TO) process has the objective to structurally optimize products in various industries, such as in biomechanical engineering. Additive manufacturing facilitates this procedure and enables the utility of advanced structures in order to achieve the optimal product design. Currently, orthopedic implants are fabricated from metal or metal alloys with totally solid structure to withstand the applied loads; nevertheless, such a practice reduces the compatibility with human tissues and increases the manufacturing cost as more feedstock material is needed. This article investigates the possibility of applying bioinspired lattice structures (cellular materials) in order to topologically optimize an orthopedic hip implant, made of Inconel 718 superalloy. Lattice structures enable topology optimization of an object by reducing its weight and increasing its porosity without compromising its mechanical behavior. Specifically, three different bioinspired advanced lattice structures were investigated through finite element analysis (FEA) under in vivo loading. Furthermore, the regions with lattice structure were optimized through functional gradation of the cellular material. Results have shown that optimal design of hip implant geometry, in terms of stress behavior, was achieved through functionally graded lattice structures and the hip implant is capable of withstanding up to two times the in vivo loads, suggesting that this design is a suitable and effective replacement for a solid implant.
Highlights
The additive manufacturing (AM) process has enabled the production of complex geometries [1,2,3,4]along with composite material structures [5,6], which are difficult to fabricate with traditional manufacturing techniques, such as machining and injection molding
An orthopedic hip implant was designed according to international standards and a topology optimization of its geometry was performed
The topology optimization process was implemented via bioinspired lattice structures, namely, Voronoi, Gyroid, and Schwarz Diamond structures, which are derived from nature having superior mechanical performance
Summary
Along with composite material structures [5,6], which are difficult to fabricate with traditional manufacturing techniques, such as machining and injection molding. This led to rapid development of the topology optimization process with advanced geometries via generative design and cellular materials. Topology optimization (TO) is a procedure that optimizes the material mass distribution within the already defined external volume [7], resulting in light-weight structures and minimization of feedstock material usage. The density-based approach is identical to generative design [9]. The truss-based approach utilizes periodic unit cells (lattice structures) in order to achieve the optimum mass distribution [10]. There is a plethora of applications in several industries
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