Integrated Sensors for the Evaluation of Structural Integrity of Inflatable Habitats

The objective of the proposed NASA Sequential Phase II STTR program is to continue the development of mechanically flexible piezoresistive sensors for the measurement of long-term creep strain in inflatable habitat webbing.nbsp; During the Phase I and base Phase II programs, NanoSonic has worked with the Electronic Textiles Laboratory at Virginia Tech to demonstrate the technical feasibility of fabricating low modulus, high yield strain planar piezoresistive Metal Rubber sensors and using them to measure strain and creep in webbing materials.nbsp; During the Phase II-S program we will continue the development of these sensors, and, by extrusion processing, fabricate similar piezoresistive Metal Rubber and electrically conductive monofilament yarns that may be directly woven into webbings during their manufacturing.nbsp; Using a crosshead extrusion die, protective coatings will be fabricated on the yarns.nbsp; By varying the volume percentage of metal nanocluster materials during the extrusion process, conductive monofilament with defined internal lengths of piezoresistive sensor elements will be produced, allowing the measurement of local strain.nbsp; The extrusion of piezoresistive monofilament has been made possible by NanoSonicrsquo;s recent installation of a new twin-screw extruder manufacturing system.nbsp; Virginia Tech researchers will model sensor orientation in and on different webbing architectures, continue the development of custom Metal Rubber material connectors, and weave a large area test fabric incorporating embedded yarn and surface mounted planar sensors using its laboratory dobby loom.nbsp; Through a subcontract effort, Bally Ribbon Mills will directly weave conductive and piezoresistive monofilament sensor yarns into 1rdquo; Vectran webbing for testing.nbsp; Through a separate subcontract, ILC Dover will use a load frame in a temperature-stepped thermal chamber to perform simulated creep measurements using the 1rdquo; Vectran webbing and time-temperature superposition analysis.nbsp;