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Leo Christodoulou with DARPA |
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Date: July 13, 2004
Time: 10:30am
Location: NASA LaRC, Bldg 1192C, Rm 102
Speaker: Leo Christodoulou with DARPA
Subject:* "Engineered Materials Systems for Aerospace Applications"
Additional Information: Presentation (PDF)
A Synthetic Multifunctional Material (SMFM) System is defined as a structural material (one which must, by nature of its application, bear mechanical loads or resist imposed mechanical stresses in service) that also exhibits at least one additional, performance-linked function. Synthetic multifunctional materials are explicitly designed and synthesized to realize multiple, predetermined, functions to meet specific requirements. The framework for such materials systems is based on materials science and engineering concepts but draws upon other disciplines such as biology, mathematics and design to enable revolutionary advances in overall platform capability. Biology exhibits an especially diverse repertoire of multifunctional materials (e.g., material systems with structural capability fully integrated with sensing, actuation and healing functions) and provides inspiration and templates for similar engineered (synthetic) material systems. Mathematics provides the tools for efficiently converging and optimizing solutions, linking multi-scale effects and provides control algorithms for managing the resultant materials. Design enables innovative architectures and forms the basis for efficient morphological and topological arrangements of features and attributes. The challenges in producing synthetic multifunctional material systems include:
1. achieving synergistic, not parasitic, combinations of properties
2. designing and synthesizing efficient multifunctional structures in engineering-compatible time-frames
3. assigning purposeful direction to tailoring of multifunctionality (unlike natural systems in which evolution is (locally) random and incremental)
4. establishing formalized design methodologies
5. efficiently predicting and combining functions that operate on different size scales
6. establishing rules and tools for the design of and design with such materials
In presentation, various multifunctional materials developed under the Defense Advanced Research Projects Agency (DARPA) sponsored initiative will be described and reviewed. Within the overall imitative a number of SMFM domains have been identified including:
1.Power structures; incorporating distributed electrical energy power
2.Autophagous; self-consuming structures
3.Autonomous sensing, actuation and damping
4.Survivable; damage tolerant and adaptive structures
5.Actuated for morphing structures
and deployable space antennas, and Autogenous structures; self generating/healing
Attainment of such multifunctionality places stringent requirements on the ability to tailor make materials systems through control at the salient spatial (nano-, micro-, meso-, and macro-scale), compositional (crystallography, morphology, defect character and distribution), and temporal (nanosecond to minutes or hours) levels. Such detailed control has by no means been completely achieved, but significant progress has been made in a number of areas as discussed below. It is hoped that this “first generation” of multifunctional materials will spur further research activity and suggest new design approaches and engineering concepts for aerospace structures of the future.
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