FE stress analysis for a first outline of the vacuum vessel of UST_1  
Abstract : The calculation of the stress in a porcelain vacuum vessel for the UST torus is described. The only load considered in this calculation is the atmospheric pressure. Magnetic forces are very low if only a basic set of power supplies is used. The objective is to continue experimenting with the code_ASTER and to obtain an approximate value of the stress in the structure..
Modelling
The major radius of the torus is 0.1125 m . The
minor radius of the external surface of the torus is 0.04775 m and the
thickness of the wall is 10mm. The reason of the relatively thick wall is
the specific process of moulding that is foreseen and to allow attaching the
external flanges to the nonprotuberant ports of the torus. A figure
representing the present idea about this type of ports is shown in Graph 2.
Nonprotuberant ports
The general structure of the
torus is thought to be similar to CTH, m=5 , l=2, [2] , but only 5
equatorial ports are planned.
Solution using ASTER
The general process of meshing with GMSH and solving with ASTER is described in [3]
The present model uses "3D modellisation" and the constraints are supposed to be on a ring on the internal hole of the torus.
The properties of the material are: Young’s modulus 137GPa ; Poisson’s ratio 0.19 corresponding to an average Zircon porcelain. All this values were defined using EFICAS, a tool to easily define the FEA model in ASTER.
The distribution of Von Mises stress around the port is represented in Graph 4. The maximum value is 1.36 x 10^{6}Pa and the minumum 1.1x10^{6}Pa . Maximum values are around the port. The stress, as was expected, is very small and far from the tensile strenght of an average zircon porcelain, about 7001000 Kg/cm2 .
Further developments If more power supplies were available the magnetic forces should be introduced in the model and the maximum current would be calculated.
References [1] "Forces on HF coil of the first outline of the UST_I" . See "All past research" in this web. [2] “Design and construction progress of the compact toroidal hybrid" Hartwell, G.J., Knowlton, S.F. Watts, C.Hanson, J.D., Brown, T. [3] "FE stress analysis of the case for the TF coils in HT7U using Code_ASTER and GMSH" . See "All past research" in this web.

Graph 4 . Von Mises stress around the port
Graph 1 . Deformation of the TF coil under outofplane loads. Units in meters. Calculation using ASTERGMSH
Graph 2 . Present ideas about a nonprotuberant port.
Graph 3 . Distribution of Von Mises stress. Units in Pa. Calculation using ASTERGMSH
Graph 4 . Von Mises stress around the port


Last Update 22072005 