Application of Functionally Graded Lattice Structures suitable for Additive Manufacturing in Mechanical Parts

Additive manufacturing (AM), also known as 3D printing, has transformed scientific and manufacturing fields with its rapid design iterations and ability to produce intricate geometries, making it accessible through its low entry prices and versatile applications. Within this domain, Functionally Graded Lattice Structures (FGLS) have emerged as a significant development: these low-density cellular structures, spanning large volumes, can be customized and optimized for specific needs.
Numerous recent publications delve into their application fields, potential improvements over conventional designs, and appropriate optimization methods, emphasizing advantages in both performance and production efficiency. However, the transfer from theoretical exploration to practical engineering implementation of FGLS remains a challenge, demanding the integration of various critical elements, including detailed material modelling, production requirements, and optimization
routines.
In this dissertation, a comprehensive investigation is conducted to address these challenges. The study explores suitable design software, lattice types, manufacturing techniques, and materials, aiming to develop a general-purpose optimization technique. The research evaluates the results based on their performance, providing valuable insights into the potential applications of FGLS. To illustrate the practical aspects of this research, two real-world examples are presented: a steel bicycle crank arm manufactured using metal Fused Deposition Modelling (FDM) printing and a bicycle helmet made of
Polyamide produced with Multi Jet Fusion (MJF). These applications showcase the versatility of FGLS, as the optimization goals differ: the crank arm lattice is optimized for maximum stiffness under a mass constraint, while the helmet lattice is optimized for the wearer's maximum protection. Furthermore, the research includes a synthetic test featuring a cuboid lattice geometry subjected to compressive loads, exploring its optimal thickness distribution following mathematical functions. The study demonstrates different lattice splitting and optimization techniques, varying in complexity levels.
Physical testing plays a crucial role in this research, allowing the correlation of simulative findings with actual behaviours. The dissertation includes detailed physical tests of several material and manufacturing options, evaluating their suitability for the presented applications. However, challenges arise during physical testing due to geometrical and material deviations resulting from manufacturing procedures, complicating reliable simulative predictions. Despite these challenges, the optimization routine proves its capability to enhance the performance of lattice structures in numerical simulations, suggesting the potential of FGLS to outperform conventionally produced appliances. These findings highlight the promising future of Functionally Graded Lattice Structures in engineering applications, showcasing their potential to change various industries.