Abstract

With the emphasis on lightweighting, composites are being turned to for help to reduce weight while still maintaining strength and stiffness. However, composites tend to be linear elastic to failure so there is often no warning of failure unlike in metallic components. For this research, a pipe section was fabricated from an Inconel 718 liner with a carbon composite overwrap. The pipe was instrumented and then subjected to increasing internal pressure until failure. The carbon composite was composed of IM7 fibers in a geopolymer matrix. Since the exact properties of the composite were not initially known, a simple laminate model of the tube was done using carbon-epoxy data. This resulted in an over prediction of the failure load. The exact material used was tested and a new laminate model was created that better matched the experimental results. The results from the experiment and laminate model were used to assist in the creation and validation of a finite element model of the experiment. The model makes use of advanced numerical techniques to predict when failure will occur. The failed specimen was then analyzed to determine failure mechanism and quality of the composite wrap. This paper will present the fabrication, modeling, testing and failure analysis of this effort.

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