CAREER: Understanding the Combined Effect of Microstructure and Topology on the Mechanical Behavior of Additively Manufactured Lattice Structures

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This Faculty Early Career Development (CAREER) grant focuses on understanding the mechanical behavior of additively manufactured lattice structures (AMLS). AMLS are hierarchical materials whose effective properties depend upon both the topology of the lattice structure and the base metallic material microstructure. Therefore, understanding the interplay between topology and microstructure is necessary to maximize the potential application of AMLS. In general, one of the major factors that limits a complex engineering system’s performance is that conventional structural metallic materials serve a singular purpose of providing structural support. However, flexibility in the design of AMLS enables an array of multifunctional applications, such as controlled heat transfer, vibration, energy management, and light-weighting. In this research, the potential of AMLS will be enhanced with an in-depth experimental-computational investigation of the combined role of microstructure and topology in the mechanical deformation mechanisms that control the mechanical behavior over a wide range of loading conditions. The educational part of this grant will provide: (1) an opportunity to senior design teams to build educational tools and techniques to teach mechanical engineering concepts to people with visual impairment; and (2) a hands-on research opportunity to low-income students.The research objectives of this project are understanding the specific contribution and interplay between the microstructurally driven mechanisms (e.g., those due to grain structures, orientation, and porosity) and geometrically driven events (e.g., unit-cell buckling, node fracturing, and macroscopic shear) on the deformation of AMLS, and determining which mechanisms dominate under different loading conditions. In order to elucidate the specific contribution of local microstructural features relative to topological attributes, experimental data obtained from microstructural and mechanical behavior characterization will be coupled with the local state of stress computed from finite element (FE) simulations. The FE analysis will use a yield criterion that will be customized for AMLS to capture the anisotropic behavior of the struts originating from the repeated solid-phase changes during layer deposition. The new yield criterion will be built based on the strut-level tension, compression, and shear experiments for different microstructures controlled by heat-treatment.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.