Graded cellular structures for enhanced performance of additively manufactured orthopaedic implants

Hip implants face a significant challenge due to their limited lifespan, a concern amplified by the rising human life expectancy. Lattice structures have demonstrated the ability to provide precise control over geometry, thereby significantly enhancing implant performance. This paper introduces the development of graded additively manufactured Ti6Al4V lattice structures for orthopaedic implants. The objective focuses on developing a graded lattice unit cell design mirroring human bone properties, emphasising high surface curvature and design versatility to improve mechanical and biomedical properties, specifically osseointegration and stress shielding. The study involves modelling and grading simple cubic (SC) and body-centred cubic (BCC) lattice structures with various geometries and graded conditions and conducting compressive tests to identify the optimal configuration. The results showed that filleting was found to be the mechanical strength. On the other hand, BCC lattice structures demonstrated superior performance compared to SC structures. The optimised structure with a pore size of 400 µm provided an elastic modulus of 15.7 GPa, yield strength of 296 MPa and compressive strength of 530 MPa. This graded lattice design approach provides a promising technique for enhancing hip implant performance, offering potential improvements

Designing Lightweight 3D-Printable Bioinspired Structures for Enhanced Compression and Energy Absorption Properties

Recent progress in additive manufacturing, also known as 3D printing, has offered several bene-fits, including high geometrical freedom and the ability to create bioinspired structures with intri-cate details. Mantis shrimp can scrape the shells of prey molluscs with its hammer-shaped stick, while beetles have highly adapted forewings that are lightweight, tough, and strong. This paper introduces a design approach for bioinspired lattice structures by mimicking the internal micro-structures of a beetle’s forewing, a mantis shrimp’s shell, and a mantis shrimp’s dactyl club, with improved mechanical properties. Finite element analysis (FEA) and experimental characterisation of 3D printed polylactic acid (PLA) samples with bioinspired structures were performed to deter-mine their compression and impact properties. The results showed that designing a bioinspired lattice with unit cells parallel to the load direction improved quasi-static compressive perfor-mance, among other lattice structures. The gyroid honeycomb lattice design of the insect forewings and mantis shrimp dactyl clubs outperformed the gyroid honeycomb design of the mantis shrimp shell, with improvements in ultimate mechanical strength, Young’s modulus, and drop weight impact. On the other hand, hybrid designs created by merging two different designs reduced bend-ing deformation to control collapse during drop weight impact. This work holds promise for the development of bioinspired lattices employing designs with improved properties, which can have potential implications for lightweight high-performance applications

Designing Lightweight 3D-Printable Bioinspired Structures for Enhanced Compression and Energy Absorption Properties

Recent progress in additive manufacturing, also known as 3D printing, has offered several bene-fits, including high geometrical freedom and the ability to create bioinspired structures with intri-cate details. Mantis shrimp can scrape the shells of prey molluscs with its hammer-shaped stick, while beetles have highly adapted forewings that are lightweight, tough, and strong. This paper introduces a design approach for bioinspired lattice structures by mimicking the internal micro-structures of a beetle’s forewing, a mantis shrimp’s shell, and a mantis shrimp’s dactyl club, with improved mechanical properties. Finite element analysis (FEA) and experimental characterisation of 3D printed polylactic acid (PLA) samples with bioinspired structures were performed to deter-mine their compression and impact properties. The results showed that designing a bioinspired lattice with unit cells parallel to the load direction improved quasi-static compressive perfor-mance, among other lattice structures. The gyroid honeycomb lattice design of the insect forewings and mantis shrimp dactyl clubs outperformed the gyroid honeycomb design of the mantis shrimp shell, with improvements in ultimate mechanical strength, Young’s modulus, and drop weight impact. On the other hand, hybrid designs created by merging two different designs reduced bend-ing deformation to control collapse during drop weight impact. This work holds promise for the development of bioinspired lattices employing designs with improved properties, which can have potential implications for lightweight high-performance applications