Cryogenic Fatigue Testing of Glass Reinforced Epoxy Tubes
In superconductive magnetic energy storage (SMES) units, cold to warm struts are required to transmit the magnetic radial load from the 1.8 K helium dewar surface to the 300 K vacuum vessel surface with a minimum heat leak. Glass reinforced epoxy tubes are proposed for such struts. Subscale samples of strut material and configuration are tested. Ultimate compressive strength testing at both ambient and liquid nitrogen temperatures in addition to the compression-compression fatigue life at 77 K are reported. Scanning electron micrographs of the failed specimens are discussed. The average ultimate compressive strength at 77 K is 128 ksi, about 50% higher than room temperature strength. The low temperature fatigue life at a stress level of 60% of the ultimate strength exceeds one half million cycles.
KeywordsFatigue Life Ultimate Load Ultimate Compressive Strength Composite Tube Room Temperature Strength
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