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Thermo Elastic Analysis of a Type 3 Cryogenic Tank Considering Curing Temperature and Autofrettage Pressure

In this study, effects of curing temperature and autofrettage pressure on a Type 3 cryogenic propellant tank, which is composed of composite hoop/helical layers and a metal liner, were investigated by thermo elastic analysis using finite element method. The temperature field of a Type 3 tank was obtained by solving the heat transfer problem and, in turn, was used as the nodal temperature boundary conditions during the elastic analyses for curing temperature and autofrettage pressure effects. Progressive failure analysis was also introduced in this procedure. As a result, it was shown that the higher the curing temperature was, the more residual compressive stress and tensile stress were induced in composites and metal liner, respectively. On the contrary, autofrettage pressure brought the reduction of these residual thermal stresses caused by cryogenic environments to the tank structure and these trends were verified from the composite/aluminum ring specimen tests at cryogenic temperature, which is suitable for preliminary tests of filament wound structures. This tradeoff for curing temperature and autoprettage pressure must be considered in the design and manufacturing stages for a Type 3 cryogenic tank.