Collaborative Research: Computational Design of Multi-functional Minimal-Surface Lattice Structures

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Triply periodic minimal-surface (TPMS) lattices are widely present in nature and are finding increasing viability for use in engineering applications. Their geometric properties facilitate fabrication via additive manufacturing techniques, and they exhibit good mechanical and transport properties. However, an outstanding challenge in the design and use of these lattices is the lack of consideration for material failure criteria arising from cyclic loading, which is critical for many potential applications. This award supports fundamental research to formulate novel computational techniques to efficiently design multi-functional TPMS lattice structures with regards to strength, durability, transport, and manufacturability criteria, and to allow for modulation of the unit cell design within the component. This research has the potential to substantially increase the viability and range of applications of lightweight minimal-surface lattices in demanding applications in healthcare, welfare, and energy efficiency, such as porous orthopedic implants with enhanced bone-loss prevention, spacers for membrane distillation with high mass transfer efficiency for desalination and wastewater treatment, and architected battery electrodes with high power output and energy storage. This award will also support the development of teaching modules that explore the engineering and aesthetic aspects of designing artifacts with minimal-surface lattices for undergraduate industrial design students, K-12 teachers, and engineering graduate students.To achieve the goal of formulating efficient computational techniques to design TPMS lattices fabricated via additive manufacturing, this project will exploit the mathematical structure of minimal surfaces and couple tools in the differential geometry of surfaces with topology optimization techniques to: 1) design thickness-graded lattices that satisfy strength, permeability and manufacturability requirements; 2) incorporate mechanical fatigue requirements in the lattice design; and 3) modulate the design and orientation of the lattice unit cell within the structural component to render superior performance. Further, design techniques that systematically vary the local geometry of the unit cell within the component will be explored. Fabrication via metal additive manufacturing of TPMS lattices as well as surface morphological analysis, imaging and mechanical testing will be conducted both to inform geometric limits on the lattice design dictated by the manufacturing process, and to validate the performance of lattice designs obtained with the formulated computational techniques.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.