Stress Measurement Technique Using Microballoons with Carbon Fibers Embedded inan RTV Film

摘要

This investigation examined the use of microballoon impregnated RTV to determinethe maximum compressive stress of the RTV. The use of microballoon impregnated RTV is an extension of microballoon sensors previously developed to measure the hydrostatic pressure in remote and hazardous locations. The results of this study showed that the microballoons, when embedded in RTV thin films, can provide an indication of the maximum applied compressive stress. The use of carbon fibers appears to provide some lateral constraints and thus increase the repeatability of the test data. However, the resolution or accuracy will be much higher than the 5 psi resolution found in the hydrostatic case. A further investigation of the specimen configurations such as types of microballoons, casting matrix, and lateral restraining technique to enhance the resolution is needed. Another potential line of investigation that could provide better resolution would be to replace the hydrostatic pressure chamber with a uniaxial loading frame. The use of a loading frame would provide a truer comparison between the load applied during the measurement and the load applied during the sample interrogation. While the use of microballoon filled RTV did not satisfy the requirements of the IR window measurement, it does have potential applications in the measurement of other more highly loaded joints.