Theoretical comparison of thermo-mechanical behavior of a tension rod and a coil as dewar support

Dewars continue to be the popular means of cryogen storage. Heat in leak through the insulation and the support system holding the two vessels is the main parameter determining the hold-up time of a Dewar. Support systems for dewars are designed by taking motivation from the design methodologies available for high temperature pressure vessels. While implementing these design guidelines, the mismatch between the material behaviors at these conditions are being taken care of by using various safety factors. The scientific motivation behind these safety factors are not apparent. The use of these factors add to the weight and cost of the storage system, thereby increasing the payload. In this paper, a mathematical model has been presented to determine the stress and temperature distribution in a support structure. The model has been solved by employing an FEM formulation using the commercial software ANSYS®. The thermal and structural behavior of two support systems has been compared by solving the model equations.