Design and Analysis of Transportation Frame For Upper Cylinder of Cryostat

Abstract

Manufacturing of huge vessel, the cryostat is done by welding of austenitic steel plates of thickness ranging from 50mm to 250mm thick. It is manufactured in different sectors and segments and subassemblies. These sub-assemblies require fixtures and tools for proper assembly and final building up of the Cryostat. To hold the work piece securely in the correct position to the machine centre during operation, fixture is used. In an industry, product quality, quantity and cost of production are largely impacted by fixtures. In this dissertation transportation frame has been designed for the assembly of different sectors and sections to build upper cylinder of ITER Cryostat. The frame consists of support structure, Bottom ring, Mid support ring and Top-plate assembly for the ease of welding and assembly of the upper cylinder of cryostat. The frame should be designed taking care of its compatibility to use for manufacturing and assembly of other subassemblies and in-situ machines too.The frame will also be used for the transportation of upper cylinder from the workshop to Tokamak pit with the help of SPMTs.Transportation frame is also subjected to seismic loads and transportation analysis of the subassemblies while manufacturing and installation at site. Conceptual modeling of transportation frame has been carried out in CATIA software. Manual calculations for the main frame beam and for the support structure has been carried out. Meshing of the upper cylinder and transportation frame has been carried out in HYPERMESH.Analysis has been carried out to validate the transport frame against different loading conditions on support stools as well as on SPMTs in ANSYS and the results have been interpreted by comparing the planned factor of safety against actual factor of safety.The stresses generated in the transportation frame are found to be within the ASME allowable limits. Reaction forces at the joints have been extracted from analysis result for bolt calculation. The bolt calculation has been done according to IS 800 and found to be safe.