Integrated Sensors for the Evaluation of Structural Integrity of Inflatable Habitats

Inflatable pressurized habitats are envisioned as a practical way to build shelters much larger than landing craft for astronauts and their scientific operations on Mars, the moon and elsewhere.  These habitats maintain their inflated shape via high-strength Vectran webbing. The piezoresistive extensometers developed through this STTR program can be directly integrated into or onto Vectran webbing and would allow the determination of webbing loads during the inflation process as well as creep during long-term deployment of the habitat. The objective of this NASA STTR program has been to develop such extensometer sensor materials based on NanoSonic's Metal Rubber materials technology that may be incorporated into the support webbing of stitched, pressurized space habitats during their production to monitor loading and creep.  The electrical resistance of these sensor materials changes linearly with strain, its modulus is low enough not to interfere with the deformation of the webbing during habitat stowage, inflation and operation, and its failure strain can be made higher than one hundred percent, so much larger than that of the webbing.  NanoSonic is working with faculty and students in the Electronic Textiles Laboratory at Virginia Tech, with input from inflatable habitat manufacturers at ILC Dover, to develop sewing / stitching / weaving methods for the integration of the sensor materials into layers of webbing during production.  During Phase I, sensor performance was tested in response to both uniaxial loading using a computer-controlled laboratory load frame, and using dead loads on representative webbing material that experiences long-term creep.  During Phase II, NanoSonic and Virginia Tech would work with ILC Dover to integrate and test webbing sensors on softgood habitat models and Bally Ribbon Mills to weave Metal Rubber extensometers directly into NASA habitat webbing materials.