Contents lists available at ScienceDirect Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes Use of morphing techniques within weld distortion analysis to simulate the size customization of parts during assembly and welding of the vacuum vessel PS3 outer shell Eduardo Rodríguez a , Javier Ordieres b, ⁎ , Angel Bayón c , Joan Caixas c , Andrea Barbensi d , Francesco Di Muzio e a Department of Construction and Manufacturing Engineering, University of Oviedo, 33203 Gijón, Spain b Numerical Analysis Technologies S.L., Marqués de San Esteban 52, 33206 Gijón, Spain c F4E, Josep Pla 2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona, Spain d Ansaldo Nucleare S.p.A., Corso Perrone 25, 16152 Genova, Italy e Walter Tosto S.p.A., Via Erasmo Piaggio 62, 66100 Chieti Scalo, Italy ARTICLE INFO Keywords: Morphing Customization Manufacturing Weld distortion ABSTRACT During welding of large, massive and complex assemblies, the accumulated shrinkage of parallel welds may cause a cumulative distortion effect which significantly varies the dimensions and geometry of the welded portion while still unfinished. The subsequent parts to be added require customization to fit in the space to allocate them. When welding distortion analysis (WDA) is carried out, the process described of part size customization needs to be taken into account; otherwise it would be a relevant source of inexactitude for the prediction of distortion. A methodology is presented to include in WDA the size customization of the parts being added to fit into a distorted assembly. 1. Introduction 1.1. Part customization during manufacturing The ITER vacuum vessel (VV) will be constructed through the welding of nine 40° sectors, each one formed by four poloidal segments (PS1–PS4) [1]. The outer shell (OS) of the segments is built by the welding of plates between the poloidal ribs (Fig. 1). The welds in poloidal direction between outer shell plates and po- loidal ribs are foreseen to be performed using TIG narrow gap tech- nique. At the upper and lower parts of PS3, the number of welds in poloidal direction (nearly parallel welds) is 16. The initial sequence foreseen for welding of the plates is shown through numbering (Fig. 1). The four plates numbered as 1 are added and welded simultaneously. Subsequently, the six plates numbered as 2 are simultaneously added and welded; and the same for subsequent groups of plates 3 and 4. Due to weld shrinkage after welding of first set of plates, the space left for insertion of the adjacent sets of plates is expected to differ sig- nificantly from nominal, and plates shall be custom sized after dimensional survey of the assembly to be then fitted and welded. The same occurs after welding each set of plates in the sequence. 1.2. WDA method particularities WDA have been performed to predict PS3 distortion and final di- mensions, in order to validate the manufacturing route. The methodology followed for WDA uses finite elements (FE) as described by Guirao et al. [2], and has been successfully applied in previous studies [3–6]. According to this methodology new material is added at the weld, using the element birth and death technique [7]. The "element death" effect is not achieved by removing "killed" elements, instead they are always present in the FE model but deactivated, mul- tiplying their stiffness and mass by a severe reduction factor (1.0E- 6).When elements are "born", they are not actually added to the model, instead they are simply reactivated, and their stiffness and mass return to full original values. Therefore in the WDA performed all parts of the assembly and bevels between them are included in the model from the beginning of the simulation with their nominal sizes. A consequence of element https://doi.org/10.1016/j.fusengdes.2019.01.075 Received 24 September 2018; Received in revised form 26 December 2018; Accepted 11 January 2019 ⁎ Corresponding author. E-mail address: javier.ordieres@natec-ingenieros.com (J. Ordieres). Fusion Engineering and Design xxx (xxxx) xxx–xxx 0920-3796/ © 2019 Elsevier B.V. All rights reserved. Please cite this article as: Rodríguez, E., Fusion Engineering and Design, https://doi.org/10.1016/j.fusengdes.2019.01.075