Graphite epoxy composite (GEC) materials are used in the construction of rocket fairings, nose cones, interstage adapters, and heat shields due to their high strength and light weight. However, they absorb moisture depending on the environmental conditions they are exposed to prior to launch. Too much moisture absorption can become a problem when temperature and pressure changes experienced during launch cause the water to vaporize. The rapid state change of the water can result in structural failure of the material. In addition, heat and moisture combine to weaken GEC structures. Diffusion models that predict the total accumulated moisture content based
on the environmental conditions are one accepted method of determining if the material strength has been reduced to an unacceptable level. However, there currently doesn’t exist any field measurement technique to estimate the actual moisture content of a composite structure.
This work was done by Mark Nurge, Robert Youngquist, and Stanley Starr of Kennedy Space Center. KSC-13499