CAREER: Multiscale Optimization of Additively Manufacturable Spatially Varying Cellular Microstructures

Embry-Riddle Aeronautical University, Daytona Beach FL

Investigators

Abstract

Cellular structures rely on patterns of solid materials and voids to achieve desirable combinations of high strength, light weight and other properties. A well-known example of this is the honeycomb pattern, but in general a cellular structure can consist of cells with varying shape, size and orientation. Cellular structures are important in many applications, including light-weight aerospace structures, biomedical devices, energy absorbers, heat exchangers, and acoustic insulation. However, general techniques for optimally designing cellular structures remain a challenge. This Faculty Early Career Development Program (CAREER) award supports fundamental research to create new techniques for optimally designing cellular structures to achieve unrivaled performance for specific engineering applications. The design approach will permit cellular shape and size to vary optimally throughout the structure and will incorporate manufacturing constraints associated with 3D printing techniques in the optimization process. Two applications are identified to evaluate the methodology and demonstrate its benefit to society: improved orthopedic implants and lightweight aircraft wing structures for improved energy efficiency. This CAREER project will integrate cellular structure design and fabrication concepts into interactive learning plans through hands-on demonstrations, visual tools, concept-mapping, and a cellular design computer app. Aimed at audiences from K-12 to the general public, with specific emphasis on diverse underrepresented groups, the educational plan consists of four components: (1) educator training, (2) student extracurricular activities, (3) curriculum development, and (4) public outreach. The theoretical and experimental foundations of this CAREER award will allow a shift from optimizing the topology of macrostructures to topology and morphology of cellular microstructures expanding design flexibility without placing excessive demands on computational resources. This project provides new fundamental understanding of abnormal features such as disconnectivity in optimized cellular microstructures and the level of homogeneity in the fabricated optimized designs. Innovative aspects of the research include utilizing a harmonics decomposition that is adaptable to different cell types to represent the cellular configurations in the optimization process and implementing cell size and length scale constraints in the methodology to ensure fabrication feasibility. The relationships between the optimized cellular geometries and mechanical properties and structural performance are studied through simulation and experimental testing. The optimized microstructures will be 3D printed and various manufacturability characteristics such as deformation and powder trapping will be studied for different cell types and length scales. To investigate the effectiveness of the novel optimization framework for different design requirements, application studies will be performed on optimizing an orthopedic implant for stiffness and strength and multi-disciplinary design optimization of a honeycomb wing skin with octet truss internal support structures. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.