Simulation of the rolling of stator vanes Harm Wisselink
Contact info: Harm Wisselink Han Huetink Martien van Dijk Andre van Leeuwen h.h.wisselink@wb.utwente.nl j.huetink@wb.utwente.nl ID_eldim@eldim.nl ID_eldim@eldim.nl Introduction ELDIM manufactures among others stator vanes for the compressor of an aero engine (figure 1). These vanes are produced by a cold rolling process. The development of a rolling process for a new type of vane can take several cycles of trial and error, before all requirements are fulfilled. from strips of sheet metal
Analysis of guillotining and slitting, finite element simulations
Guillotining and slitting are two sheet metal cutting processes, which produce long straight cuts and can be seen as stationary processes. The analysis of these two processes is the subject of this thesis. This research project is part of a cluster of IOP projects on sheet metal cutting, originating from industrial requests for more fundamental knowledge, as sheet metal cutting is still mainly based on experience and trial and error. The objective is to develop models of guillotining and slitting to increase the insight and to contribute to the quality and productivity of these shearing processes.
Plasticity and ductile fracture of IF steels: experiments and micromechanical modeling
Abstract If one aims at the simulation of plasticity and failure of multiphase materials, the choice of an appropriate material law is of major importance. Plasticity models for porous metals contain, in addition to the yield surface and the flow potential, also functions describing the void nucleation, dependent on some macroscopically observable quantities, and the growth of these voids. In this paper, a micromechanically based method to develop a void nucleation function for porous plasticity models is proposed which is valid for all possible microstructures as long as the amount of second phase particles is low (i.e. the particles do not interact with respect to the stress and strain fields), and as long as the particles are large enough (above 0.1  μ m) justifying a continuum mechanical approach. The method described consists of two stages: In the first stage, the microstructure is investigated via a finite element model. The FE model implicitly contains the effects of the shape of the precipitates, of the material parameters of both the matrix and the precipitates, of the void nucleation hypothesis (by the assumption of “nucleation limits” for characteristic damage-related quantities), and of the applied stress state. In the second stage, during postprocessing, the volume fraction of precipitates as well as the influences of the particle orientation distribution, size distribution, and size dependence of the damage-related quantities are taken into account. The model is applied to the microstructure of IF ( I nterstitially F ree) steel, a material with a ductile matrix and rigid second phase particles of cubical shape. This microstructure is particularly suited for investigating shape and size effects. The model shows that either the size effect or the shape effect dominate the void nucleation behavior: in the case of particles of roughly the same size, the size distribution will hardly alter the nucleation strain distribution obtained by taking into account only the shape and orientation effects. For particles of very different sizes, the size effect will completely override the rather “sharp” original distribution regarding particle shape and orientation.