Limit analysis of complex welds between plasma vessel and ports in W7-X cryostat system

Abstract Wendelstein 7-X (W7-X) is an experimental modular stellarator of the HELIAS type, currently in the second phase of operation in Greifswald, Germany. The stellarator is a complex 3D structure with high level safety requirements. As a result, sophisticated methods are necessary for the analysis of critical components and it is very important to evaluate structural strength of the welded connections between the plasma vessel and the ports. The structural integrity analysis of the welded connection between plasma vessel and ports has been performed for several critical and/or representative port welds. The modelling of the welded connection was performed in two steps. First the geometrical 3D models of these port welds were prepared using the SolidWorks software. The model of a welded connection of the complex shape was modelled by creating a big number of sketches around the perimeter of the port-to-PV connection. Later, the sketches were connected using a loft feature and was transferred to the ABAQUS/Standard FE software. The limit analysis by means of finite element method (ABAQUS code) was used to confirm static strength reliability of port welds. According to the results of the analysis it is possible to conclude that the proposed welding between the plasma vessel and the analysed ports fully meets the structural requirements.