•A simplified model of the ITER Vacuum Vessel has been created for dynamic analyses.•The simplified model is based on a novel substructuring method.•Creating a model by combining many small ...superelements speeds up calculations.•The dynamic fidelity of the simplified model is excellent.
In order to characterize the behaviour of the ITER Tokamak during seismic events, it is desirable to integrate Finite Element (FE) models of the Tokamak into the model of the building (Tokamak complex). Detailed FE models exist for each of the main Tokamak systems, but these are so large that combining them is computationally impractical.
The aim of this paper is to present work performed on the creation of simplified models of the ITER Vacuum Vessel (VV) for use in global seismic analyses.
Two different methodologies have been considered for creating simplified models whose dynamic behaviour matches that of a detailed benchmark model. In the first method, a coarse mesh representing the shape of the VV is created. The element properties of this mesh are then modified using optimization algorithms until the desired dynamic behaviour is achieved.
The second method makes use of substructuring. In order to minimize the wavefront (and hence computational time), the simplified model is created from multiple superelements, each representing part of the VV.
The suitability of the simplified model based on substructuring is quantified by means of the Modal Assurance Criterion (MAC) and Power Spectrum Density (PSD) analysis.
In this paper, a methodology developed in Fusion for Energy (F4E) for interpolating mechanical loads both between compatible (i.e. from solid to solid models different in discretization) and ...incompatible (e.g. from solid models to shell/beam models) FE models is described. This novel procedure is able of transferring a force vector field (i.e. Lorentz forces) from a three-dimensional solid mesh (e.g. electromagnetic model) onto a target mesh (e.g. mechanical model), being it either three-dimensional solid or simplified beam/shell model. This interpolation procedure is developed with the aim of preserving both the global and local mechanical equilibrium of the system in terms of resultant of forces and overturning moments. The quality assessment of this procedure is based on the comparison between the global and local force and moment resultants of the source and the transferred load field. A few examples and their related results will be discussed in support of this methodology.
•Improved detail design of several NHF FW panels for ITER.•Implemented design solutions to improve the manufacturing of NHF FW panels.•Performed FEM simulations for the overall assessment of NHF FW ...panels.•Performed detailed analyses for integration of diagnostics in the NHF FW panels.
A typical NHF FW panel consists of a series of fingers, which represent the elementary plasma facing units and are designed to withstand 15,000 cycles at 2MW/m2. The fingers are mechanically joined and supported by a back structural element or “supporting beam”. The structure of a finger is made of three different materials: stainless steel for the supporting structure, copper chromium zirconium for the heat sink, and beryllium as armour material. Due to their location and to the interfaces with other systems (e.g. Diagnostics, Remote Handling), the NHF FW panels are divided in different main and minor variants.
The aim of this paper is to present the design work performed towards the PA signature. CAD detailed models have been created in CATIA for main and minor variants. Examples of local design solutions, as well as design work to achieve the global configuration of specific modules are provided. Finite Element (FE) analyses have been carried out, in order to simulate the operational scenario of ITER and assess the thermo-mechanical behaviour of the most important FW panels against the required design criteria. This design and analyses activity is required to progress towards the finalization of the detailed design of the NHF FW main and minor variants.
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