Materials Research Lecture

The ability to design and fabricate microstructural architecture enables the creation of new materials that possess radically superior properties from those currently achieved by composites, alloys, and other naturally occurring materials. The Freedom and Constraint Topologies (FACT) synthesis approach has been successfully applied to the design and optimization of such new materials (e.g., materials with large negative Poisson s ratios and zero/negative thermal expansion coefficients). The basis for FACT is a comprehensive library of geometric shapes that represent the mathematics of screw theory and enable designers to visualize all the regions wherein various microstructural elements may be placed for achieving desired bulk material properties. In this way, designers may rapidly consider and compare every microstructural concept that best satisfies the design requirements before selecting the final concept. The FACT approach provides an ideal analytical tool, which enables the effective decoupling of naturally dependent material properties. It has successfully outperformed its computer‐based competitor, topological optimization, in that FACT has produced microstructure designs that (i) may be adapted to possess greater ranges of properties, (ii) are more easily fabricated using current processes, and (iii) possess a greater degree of symmetry and practicality. FACT is also well suited for the design of various other new materials such as artificial muscle‐like materials that may be actuated using electrical inputs, sophisticated smart materials with reconfigurable optical, magnetic, and electrical properties, and materials that behave as passive control systems, which respond to changes in ambient conditions. As progress towards high‐resolution multi‐material 3D printing technology advances, microstructure designs for these and other such sophisticated applications will be driven more by performance requirements and less by fabrication limitations.