Modelling and computer simulation for the manufacture by powder HIPing of blanket shield components for ITER

Modelling and computer simulation have been developed in order to assist the hot isostatic pressing (HIP) fabrication of a shield prototype for the ITER blanket. Problems such as global bending of the whole part and deformations of tubes in their powder bed are addressed. It is important that the part does not bend too much. It is important as well to have circular shape of the cooling tube after HIP. For simulation purposes, the behaviour of the different materials is modelled. Although the modelling of the massive stainless steel behaviour is not neglected, the most critical modelling is about the stainless steel powder. For this study, a thorough investigation on the basic powder behaviour has been performed with some in situ HIP dilatometry experiments. These experiments have allowed the identification of a compressible viscoplastic model: improved Abouaf model by taking into account some strain hardening of the powder material. Some other important modelling side effects such as coupling of thermal properties of the powder with density are also taken into account. Validity of the modelling has been assessed with several fabricated partial scale mock-ups in terms of global shape changes with 3D simplified FEM mesh and local deformations of the tubes with 2D detailed FEM mesh. The simulation has also been used as a tool to study some particular local configurations of tube embedded in powder when designing rear side of the shield prototype. (C) 2007 Elsevier B.V. All rights reserved.