PSI - Issue 46

J. Bialowas et al. / Procedia Structural Integrity 46 (2023) 49–55 J. Bialowas et al. / Structural Integrity Procedia 00 (2021) 000–000

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Following the surface of the cylinder sector there are additional elements, so-called shadow elements (cf. Fig. 2). This additional surface has a thickness of one element in the radial direction. The purpose of these elements is to extend the rolled over surface so that the work roller can roll beyond the edge of the actual cylinder sector (cf. exit point on surface in Fig. 2 (b)). Rolling over edges usually causes problems in finite element simulation, such as buckling or unrealistic stress concentrations. For this purpose, the surface nodes of these shadow elements are coupled with nodes on the surface of the cylinder sector, as shown schematically with � � � and � � � � in Fig. 2 (b). Due to the coupling, the elements of the cylinder sector experience the same deformation as the actually rolled over shadow elements. Only, the coupling of both, the boundary nodes and the surface nodes enables the work roller to move over the edges. The work roller rolls until it reaches the end of the coupled rolling path, which is also the beginning of the following true rolling path, see Fig. 2 (b). A minimum elastic modulus is assigned to the shadow elements to avoid numerical instabilities but at the same time to keep the influence on the cylinder sector as small as possible. The features described so far allow the work roller to exit and entry onto the cylinder sector simultaneously, but neglect the axial portion of the work roller’s motion per revolution, which is called feed. The work roller moves along a spiral processing path, causing an axial displacement of the exit and entry points on the cylinder sector. In order to ensure that the coupled surface nodes are in one row of the mesh while respecting the feed, the cylinder sector is

(a)

(b)

Fig. 2 Schematic of the implemented simulation model: (a) model kinematics including coupled boundary conditions, shadow elements and simulation steps for one rollover divided into preload, load, rolling, unload and return, (b) details of node coupling at the boundaries and the surface, true and coupled rolling path, and the distortion angle of the cylinder sector θ .