OBJECTIVE: Investigate the feasibility of additive manufacturing techniques, also known as 3-D printing, to produce multifunctional materials to facilitate the development of multiscale hierarchical energy dissipation at the nano- and microscale level enabled by creating microstructures that eliminate traditional inverse material property relationships. There is a vital need for the development of agile manufacturing for defense systems. New manufacturing techniques utilizing advanced materials engineered at multiple length scales may potentially accelerate technological advances in military applications for years to come.
DESCRIPTION: Structures with radically improved performance and novel functionality have not been realized because they often require material property sets that are competing such as yield strength and ductility, hardness and density, and stiffness and toughness. The capability to realize structures that would surmount these barriers have been demonstrated separately by nature or in selected polymer-based systems, by advanced modeling results, and by experiments that span the nano to the micro scales. The integration of multiple components and subcomponents at different length scales may aid in actuation across a variety of vehicle platforms, material state-awareness to enable structural health monitoring for condition-based maintenance, or embedded multifunctional capabilities for semi-autonomous micro-vehicles.
Often, material synthesis methods are based on random processes rather than structured approaches across multiple scales as seen in nature, resulting in limited success. The design and synthesis of materials from the bottom-up, to create hierarchical structures and multifunctional materials in which the conventional concepts of structure and materials are merged will provide a fundamentally new direction for materials development that would change the way new structures are developed in the decades to come. Further, the integration of materials design and structural fabrication with active feedback processes (sensing, signaling, and control systems) to augment additive manufacturing will provide an innovative approach to enhance performance of materials under changing environmental conditions, and create a new generation of tunable structures capable of responding differently to various loading conditions. Advanced manufacturing capable of exploiting tunable hierarchical materials will enable the emergence of novel structures based upon techniques of hierarchical design principles, self-assembly, material characterization, and synthesis methods.
PHASE I: Develop multi-scale modeling and experimental characterization to investigate the inelastic response of high strength (>300 MPa) hierarchical structures composed of engineering materials. Demonstrate additive methods to produce a material system with a minimum of two hierarchical levels that can respond autonomously to diverse loading conditions and/or external stimuli.
PHASE II: Additively construct a material system that has the capability to eliminate traditional material property trade-off relations (strength and toughness, strength and density, hardness and ductility) when subjected to at least two significantly different loading conditions.
PHASE III DUAL USE APPLICATIONS: After constructing a material system outlined in Phase II the additive process should be scaled-up for large scale manufacturing. Optimization of commercial design codes to develop materials for both DoD and Civilian platforms where damage tolerance and survivability are critical. Efforts should be made to commercialize technology that focuses on components that undergo a full spectrum of loading conditions including fatigue, creep, and high rate loading.
REFERENCES:
1) Scott, J., Gupta, N, Weber, C., Newsome, S., Wohlers, T., Caffrey, T., "Additive Manufacturing: Status and Opportunities," IDA/Science and Technology Institute Report, 2012.
2) Wohlers, T.,"Wohlers Report 2011: Additive Manufacturing and 3D Printing, State of the Industry," Wohlers Associates, 2011.
3) Gibson, I., Rosen, D. W., and Stucker, B., Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing, New York, Springer, 2010.
KEYWORDS: hierarchical structures, self-assemble, multiscale, tunable materials
TPOC: Larry Russell, Jr
Phone: 919-549-4211
2nd TPOC: Jaret C Riddick
Phone: 410-278-9831
Email: jaret.c.riddick.civ@mail.mil
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