Subhash Narang

Circulatory system for unmanned air vehicles

We have built a platform circulatory system by fabricating channels whose dimensions and layout are analogous to a fractal system where the reactants (fluids) are carried from a central reservoir, through progressively smaller channels ultimately with a width of 100 microns as they interface with the cellular structure. The construction of the macro/micro channel platform has been carried out using the direct write/solid freeform photo fabrication hybrid platform developed by the principle investigator. The interaction of reactants is controlled at the cellular level depending upon the fractional change in structural properties to be performed. The macro/micro channel system is metallized with copper, nickel and gold to enable to allow electrochemical transformations on demand. The circulatory system has been used to increase the modulus of a beam by polymerizing monomers to high modulus polymers with a view towards repairing structural damage. The metallized channels have been used to alter the electromagnetic absorption of a structure via electrochemical switching between conducting, semiconducting and insulating states. The electromagnetic characteristics have also been altered by replacing the dopant anions with anions of significantly altered stereoelectronic characteristics by taking advantage of the circulatory system.

Acoustic properties of materials with reduced Poisson ratio.

Reduced Poisson ratio materials present an interesting opportunity for altering acoustic properties. Relationship of material morphology with Poisson ratio will be explored. The effect of Poisson ratio on mechanical properties will be reviewed. Relationship with moduli, flexural rigidity, and fracture toughness will be examined. Reduced Poisson materials have low cutoff frequencies and low wave dispersion constants compared to analogous conventional materials. Development of a variety of materials for specific applications will be discussed. The generic approach to the fabrication of reduced Poisson ratio materials, such as foams, honeycombs, laminates, and composites, provides application engineers added flexibility in choosing appropriate materials.