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Author: Hömberg, Dietmar × Author: Rocca, Elisabetta × DDC: 510 ×

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Now showing 1 - 4 of 4
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    Analysis and simulation of multifrequency induction hardening
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2013) Hömberg, Dietmar; Petzold, Thomas; Rocca, Elisabetta
    We study a model for induction hardening of steel. The related differential system consists of a time domain vector potential formulation of the Maxwells equations coupled with an internal energy balance and an ODE for the volume fraction of austenite, the high temperature phase in steel. We first solve the initial boundary value problem associated by means of a Schauder fixed point argument coupled with suitable a-priori estimates and regularity results. Moreover, we prove a stability estimate entailing, in particular, uniqueness of solutions for our Cauchy problem. We conclude with some finite element simulations for the coupled system.
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    Structural multiscale topology optimization with stress constraint for additive manufacturing
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2019) Auricchio, Ferdinando; Bonetti, Elena; Carraturo, Massimo; Hömberg, Dietmar; Reali, Alessandro; Rocca, Elisabetta
    In this paper a phase-field approach for structural topology optimization for a 3D-printing process which includes stress constraint and potentially multiple materials or multiscales is analyzed. First order necessary optimality conditions are rigorously derived and a numerical algorithm which implements the method is presented. A sensitivity study with respect to some parameters is conducted for a two-dimensional cantilever beam problem. Finally, a possible workflow to obtain a 3D-printed object from the numerical solutions is described and the final structure is printed using a fused deposition modeling (FDM) 3D printer.
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    Additive manufacturing graded-material design based on phase-field and topology optimization
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2018) Carraturo, Massimo; Rocca, Elisabetta; Bonetti, Elena; Hömberg, Dietmar; Reali, Alessandro; Auricchio, Ferdinando
    In the present work we introduce a novel graded-material design for additive manufacturing based on phase-field and topology optimization. The main novelty of this work comes from the introduction of an additional phase-field variable in the classical single-material phase-field topology optimization algorithm. This new variable is used to grade the material properties in a continuous fashion. Two different numerical examples are discussed, in both of them we perform sensitivity studies to asses the effects of different model parameters onto the resulting structure. From the presented results we can observe that the proposed algorithm adds additional freedom in the design, exploiting the higher flexibility coming from additive manufacturing technology.
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    A model for resistance welding including phase transitions and Joule heating
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2010) Hömberg, Dietmar; Rocca, Elisabetta
    In this paper we introduce a new model for solid-liquid phase transitions triggered by Joule heating as they arise in the case of resistance welding of metal parts. The main novelties of the paper are the coupling of the thermistor problem with a phase field model and the consideration of phase dependent physical parameters through a mixture ansatz. The PDE system resulting from our modelling approach couples a strongly nonlinear heat equation, a non-smooth equation for the the phase parameter (standing for the local proportion of one of the two phases) with quasistatic electric charge conservation law. We prove existence of weak solutions in the 3D case, while the regularity result and the uniqueness of solution is stated only in the 2D case. Indeed, uniqueness for the three dimensional system is still an open problem.