Structural Health Monitoring Systems for Inflatable Softgoods Space Structures

Abstract

Habitats are an essential component of any human spaceflight mission, called upon to provide the maximum amount of livable volume with the minimum amount of mass. Inflatable, deployable structures in particular have been investigated by NASA since the early 1950s and used in a number of spaceflight applications. Inflatable habitats, airlocks, and space stations can be used for in-space living quarters and surfaceexploration missions. Inflatable structures are being pursued as candidates for long-term habitats in space and on the surfaces of the Moon and Mars. Many concepts by NASA and industry utilize high-strength, low-weight softgoods materials, such as Vectran, as the primary load-bearing structure in inflatable habitats. The ability to monitor and assess the structural health and integrity of an inflatable module is an important factor in determining the feasibility of using these technologies for space habitats, especially in the presence of micrometeoroid and orbital debris (MMOD) threats. There is therefore a critical need for Structural Health Monitoring (SHM) methods to perform detection, localization, and quantification of damage to structural layers throughout the mission. This capability must be accomplished within real constraints for sensor volume, mass, and crew resources, including being able to perform effective damage monitoring of the inflatable habitat layers from the interior during a mission, either on a routine or quick-response basis. This paper discusses the design of new SHM sensor modules (consisting of colocated piezoelectric transducers and strain-gauge sensors) for inflatable softgoods and integration of a complete SHM system into inflatable habitat test articles for laboratory proof-of-concept testing. An experimental test setup for performing the initial feasibility demonstration of impact detection using the SHM sensor modules is discussed. Testing for high strain and impact detection was also conducted. The project demonstrates the feasibility of the newly-developed SHM sensor modules to provide impact detection and strain/load monitoring on inflatable softgoods for next-generation space habitation structures.