@article{64916,
  abstract     = {{The joining of dissimilar materials, such as steel and aluminum, entails significant challenges during thermal curing processes due to differing coefficients of thermal expansion. This study addresses the formation of “viscous fingering” instabilities in structural adhesive joints, which are induced by thermally driven relative displacements during the liquid phase of the adhesive. Using a component-like specimen “bridge specimen,” the dependency of this phenomenon on process temperature and structural stiffness (rivet distance) was characterized. Experimental results reveal that while the relative displacement scales cubically with the free buckling length, the resulting adhesive area reduction follows an exponential trend, leading to a loss of effective bond area of up to 79%, which significantly compromises the joint strength in automotive applications. To predict these process-induced defects, a thermo-chemo-viscoelastic-viscoplastic adhesive model implemented in LS-DYNA was applied. The model combines curing kinetics, viscoelastic relaxation, and pressure-dependent plasticity and features a geometric damage parameter (D) that captures the adhesive area reduction caused by viscous fingering as an exponential function of the accumulated normal strain in the liquid phase. This damage parameter, calibrated on base-specimen level, was transferred to the component geometry. The simulation demonstrated high predictive accuracy with a maximum deviation of the adhesive area reduction of 3.1% compared to experimental data. This validates the model’s capability to predict manufacturing-induced damage in complex hybrid structures solely based on thermal boundary conditions.}},
  author       = {{Al Trjman, Mohamad and Beule, Felix and Teutenberg, Dominik and Meschut, Gerson and Riese, Julia}},
  issn         = {{0021-8464}},
  journal      = {{The Journal of Adhesion}},
  keywords     = {{Adhesive area reduction, CED coating process, delta alpha problem, epoxy structural adhesive, influence of manufacture, multi-material design, numerical simulation (FEM), relative displacements, viscous fingering (saffman-taylor-instability).}},
  pages        = {{1--24}},
  publisher    = {{Informa UK Limited}},
  title        = {{{Experimental characterization and numerical analysis of the influence of the CED coating process on viscous fingering formation in hybrid-jointed mixed structures}}},
  doi          = {{10.1080/00218464.2026.2644394}},
  year         = {{2026}},
}

@phdthesis{59239,
  abstract     = {{Diese Arbeit behandelt die Modellierung und Optimierung von mit Phasenwechselmaterialien (PCM) ausgestatteten, energietechnischen Komponenten anhand zweier Fallstudien. PCM sind Materialien, deren Phasenwechseleigenschaften während des Schmelzens und Erstarrens für Heiz- und Kühlzwecke genutzt werden. Zunächst werden die theoretischen Grundlagen zu Wärmeübertragungsproblemen mit Phasenwechsel erörtert und entsprechende numerische Lösungsmethoden diskutiert. Ein Modell für Phasenwechselvorgänge wird vorgestellt, welches anhand analytischer Lösungen validiert wurde und in den Fallstudien zum Einsatz kam. Für beide Fallstudien wird der Stand der Technik erörtert und die entsprechenden Forschungsfragen werden formuliert. Die erste Fallstudie behandelt PCM-integrierte Photovoltaikmodule und die zweite Festbett-Latentwärmespeicher, welche nicht-kugelförmiger PCM-Kapseln verwenden. Für beide Systeme wurden thermische Model-le entwickelt und anhand experimenteller Daten mit guter Genauigkeit validiert. Diese Modelle wurden in Parameterstudien eingesetzt, um optimierte Systemkonfigurationen zu identifizieren. Die vorgestellten Ergebnisse zeigen, dass ein PCM-Kühlkörper mit ausreichender Dicke und Wärmeleitfähigkeit den Wirkungsgrad und die Lebensdauer von Photovoltaikmodulen erheblich erhöht. Darüber hinaus verbessern PCM-Kapseln mit hoher Packungs-dichte und Oberfläche sowohl die volumenspezifische Speicherkapazität als auch die thermische Leistung von Festbett-Latentwärmespeichern.}},
  author       = {{Grabo, Matti}},
  keywords     = {{Heat transfer, PCM, numerical simulation, renewable energy, heat storage}},
  title        = {{{Modeling and optimization of energy system components equipped with phase change materials}}},
  doi          = {{10.17619/UNIPB/1-2199}},
  year         = {{2025}},
}

@inproceedings{63497,
  author       = {{Förster, Nikolas and Wallscheid, Oliver and Schafmeister, Frank}},
  booktitle    = {{2024 IEEE Design Methodologies Conference (DMC)}},
  keywords     = {{MOSFET, Thermal resistance, Surface resistance, Bridge circuits, Zero voltage switching, Pareto optimization, Capacitance, Numerical simulation, Optimization, Resistance heating, Pareto Optimization, Dual-Active Bridge, ZVS, Inductor Optimization, Transformer Optimization, Heat Sink Optimization}},
  pages        = {{1--8}},
  title        = {{{Dual-Active Bridge Sequential Pareto Optimization for Fast Pre-Design and Final Component Selection}}},
  doi          = {{10.1109/DMC62632.2024.10812131}},
  year         = {{2024}},
}

@inbook{34209,
  abstract     = {{Predicting the durability of components subjected to mechanical load under environmental conditions leading to corrosion is one of the most challenging tasks in mechanical engineering. The demand for precise predictions increases with the desire of lightweight design in transportation due to environmental protection. Corrosion with its manifold of mechanisms often occurs together with the production of hydrogen by electrochemical reactions. Hydrogen embrittlement is one of the most feared damage mechanisms for metal constructions often leading to early and unexpected failure. Until now, predictions are mostly based on costly experiments. Hence, a rational predictive model based on the fundamentals of electrochemistry and damage mechanics has to be developed in order to reduce the costs. In this work, a first model approach based on classical continuum damage mechanics is presented to couple both, the damage induced by the mechanical stress and the hydrogen embrittlement. An elaborated two-scale model based on the selfconsistent theory is applied to describe the mechanical damage due to fatigue. The electrochemical kinetics are elucidated through the Langmuir adsorption isotherm and the diffusion equation to consider the impact of hydrogen embrittlement on the fatigue. The modeling of the mechanism of hydrogen embrittlement defines the progress of damage accumulation due to the electrochemistry. The durability results like the S-N diagram show the influence of hydrogen embrittlement by varying, e.g. the fatigue frequency or the stress ratio.}},
  author       = {{Shi, Yuhao and Harzheim, Sven and Hofmann, Martin and Wallmersperger, Thomas}},
  booktitle    = {{Material Modeling and Structural Mechanics}},
  isbn         = {{9783030976743}},
  issn         = {{1869-8433}},
  keywords     = {{Hydrogen embrittlement, Fatigue, Continuum damage mechanics, Numerical simulation, Multi-field problem}},
  publisher    = {{Springer International Publishing}},
  title        = {{{A Damage Model for Corrosion Fatigue Due to Hydrogen Embrittlement}}},
  doi          = {{10.1007/978-3-030-97675-0_9}},
  year         = {{2022}},
}

@inproceedings{9784,
  abstract     = {{Piezoelectric inertia motors use the inertia of a body to drive it by means of a friction contact in a series of small steps. These motors can operate in ``stick-slip'' or ``slip-slip'' mode, with the fundamental frequency of the driving signal ranging from several Hertz to more than 100 kHz. To predict the motor characteristics, a Coulomb friction model is sufficient in many cases, but numerical simulation requires microscopic time steps. This contribution proposes a much faster simulation technique using one evaluation per period of the excitation signal. The proposed technique produces results very close to those of timestep simulation for ultrasonics inertia motors and allows direct determination of the steady-state velocity of an inertia motor from the motion profile of the driving part. Thus it is a useful simulation technique which can be applied in both analysis and design of inertia motors, especially for parameter studies and optimisation.}},
  author       = {{Hunstig, Matthias and Hemsel, Tobias and Sextro, Walter}},
  booktitle    = {{Ultrasonics Symposium (IUS), 2012 IEEE International}},
  issn         = {{1948-5719}},
  keywords     = {{friction, ultrasonic motors, Coulomb friction model, efficient simulation technique, friction contact, high-frequency piezoelectric inertia motor, motor characteristics prediction, numerical simulation, slip-slip mode, stick-slip mode, time-step simulation, ultrasonic inertia motor, Acceleration, Acoustics, Actuators, Computational modeling, Friction, Numerical models, Steady-state}},
  pages        = {{277--280}},
  title        = {{{An efficient simulation technique for high-frequency piezoelectric inertia motors}}},
  doi          = {{10.1109/ULTSYM.2012.0068}},
  year         = {{2012}},
}