---
_id: '64916'
abstract:
- lang: eng
text: 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.
article_type: original
author:
- first_name: Mohamad
full_name: Al Trjman, Mohamad
id: '65415'
last_name: Al Trjman
- first_name: Felix
full_name: Beule, Felix
id: '66192'
last_name: Beule
- first_name: Dominik
full_name: Teutenberg, Dominik
id: '537'
last_name: Teutenberg
- first_name: Gerson
full_name: Meschut, Gerson
id: '32056'
last_name: Meschut
orcid: 0000-0002-2763-1246
- first_name: Julia
full_name: Riese, Julia
id: '101499'
last_name: Riese
orcid: 0000-0002-3053-0534
citation:
ama: Al Trjman M, Beule F, Teutenberg D, Meschut G, Riese J. Experimental characterization
and numerical analysis of the influence of the CED coating process on viscous
fingering formation in hybrid-jointed mixed structures. The Journal of Adhesion.
Published online 2026:1-24. doi:10.1080/00218464.2026.2644394
apa: Al Trjman, M., Beule, F., Teutenberg, D., Meschut, G., & Riese, J. (2026).
Experimental characterization and numerical analysis of the influence of the CED
coating process on viscous fingering formation in hybrid-jointed mixed structures.
The Journal of Adhesion, 1–24. https://doi.org/10.1080/00218464.2026.2644394
bibtex: '@article{Al Trjman_Beule_Teutenberg_Meschut_Riese_2026, 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},
journal={The Journal of Adhesion}, publisher={Informa UK Limited}, author={Al
Trjman, Mohamad and Beule, Felix and Teutenberg, Dominik and Meschut, Gerson and
Riese, Julia}, year={2026}, pages={1–24} }'
chicago: Al Trjman, Mohamad, Felix Beule, Dominik Teutenberg, Gerson Meschut, and
Julia Riese. “Experimental Characterization and Numerical Analysis of the Influence
of the CED Coating Process on Viscous Fingering Formation in Hybrid-Jointed Mixed
Structures.” The Journal of Adhesion, 2026, 1–24. https://doi.org/10.1080/00218464.2026.2644394.
ieee: 'M. Al Trjman, F. Beule, D. Teutenberg, G. Meschut, and J. Riese, “Experimental
characterization and numerical analysis of the influence of the CED coating process
on viscous fingering formation in hybrid-jointed mixed structures,” The Journal
of Adhesion, pp. 1–24, 2026, doi: 10.1080/00218464.2026.2644394.'
mla: Al Trjman, Mohamad, et al. “Experimental Characterization and Numerical Analysis
of the Influence of the CED Coating Process on Viscous Fingering Formation in
Hybrid-Jointed Mixed Structures.” The Journal of Adhesion, Informa UK Limited,
2026, pp. 1–24, doi:10.1080/00218464.2026.2644394.
short: M. Al Trjman, F. Beule, D. Teutenberg, G. Meschut, J. Riese, The Journal
of Adhesion (2026) 1–24.
date_created: 2026-03-14T18:43:41Z
date_updated: 2026-03-14T19:04:46Z
ddc:
- '620'
- '670'
- '660'
department:
- _id: '9'
doi: 10.1080/00218464.2026.2644394
file:
- access_level: closed
content_type: application/pdf
creator: mohamada
date_created: 2026-03-14T18:50:31Z
date_updated: 2026-03-14T18:50:31Z
file_id: '64917'
file_name: Experimental characterization and numerical analysis of the influence
of the CED coating process on viscous fingering formation in hybrid-jointed mixe.pdf
file_size: 14668789
relation: main_file
success: 1
file_date_updated: 2026-03-14T18:50:31Z
has_accepted_license: '1'
keyword:
- 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).
language:
- iso: eng
main_file_link:
- open_access: '1'
oa: '1'
page: 1-24
publication: The Journal of Adhesion
publication_identifier:
issn:
- 0021-8464
- 1545-5823
publication_status: published
publisher: Informa UK Limited
status: public
title: Experimental characterization and numerical analysis of the influence of the
CED coating process on viscous fingering formation in hybrid-jointed mixed structures
type: journal_article
user_id: '65415'
year: '2026'
...
---
_id: '59239'
abstract:
- lang: ger
text: 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.
- lang: eng
text: This thesis explores the modeling and optimization of energy system components
incorporating phase change materials (PCM) through two different case studies.
PCM are materials whose phase change characteristics during melting and solidification
are utilized for heating and cooling purposes. The theoretical foundations of
heat transfer problems involving phase change, along with the relevant numerical
solution methods, are discussed. A phase change model is presented, which was
validated against analytical solutions and applied in the case studies. For both
case studies, a review of the state of the art is provided, followed by the formulation
of specific research problems. The first case study investigated PCM-enhanced
photovoltaic modules, while the second focused on packed bed latent heat storages
(PBLHS) utilizing non-spherical PCM capsules. Thermal models were developed for
both systems and validated with good accuracy against experimental data. These
models were employed in parameter studies to identify optimized system configurations.
The presented results demonstrate that a PCM heat sink with sufficient thickness
and thermal conductivity can significantly improve the efficiency and lifespan
of photovoltaic modules. Furthermore, PCM capsules with both high packing density
and surface area increase the volume-specific storage capacity and thermal power
output of PBLHS.
author:
- first_name: Matti
full_name: Grabo, Matti
id: '66520'
last_name: Grabo
citation:
ama: Grabo M. Modeling and Optimization of Energy System Components Equipped
with Phase Change Materials.; 2025. doi:10.17619/UNIPB/1-2199
apa: Grabo, M. (2025). Modeling and optimization of energy system components
equipped with phase change materials. https://doi.org/10.17619/UNIPB/1-2199
bibtex: '@book{Grabo_2025, place={Paderborn}, title={Modeling and optimization of
energy system components equipped with phase change materials}, DOI={10.17619/UNIPB/1-2199},
author={Grabo, Matti}, year={2025} }'
chicago: Grabo, Matti. Modeling and Optimization of Energy System Components
Equipped with Phase Change Materials. Paderborn, 2025. https://doi.org/10.17619/UNIPB/1-2199.
ieee: M. Grabo, Modeling and optimization of energy system components equipped
with phase change materials. Paderborn, 2025.
mla: Grabo, Matti. Modeling and Optimization of Energy System Components Equipped
with Phase Change Materials. 2025, doi:10.17619/UNIPB/1-2199.
short: M. Grabo, Modeling and Optimization of Energy System Components Equipped
with Phase Change Materials, Paderborn, 2025.
date_created: 2025-04-02T09:25:58Z
date_updated: 2025-04-02T09:44:05Z
department:
- _id: '9'
doi: 10.17619/UNIPB/1-2199
keyword:
- Heat transfer
- PCM
- numerical simulation
- renewable energy
- heat storage
language:
- iso: eng
place: Paderborn
publication_status: published
status: public
supervisor:
- first_name: Eugeny
full_name: Kenig, Eugeny
id: '665'
last_name: Kenig
title: Modeling and optimization of energy system components equipped with phase change
materials
type: dissertation
user_id: '66520'
year: '2025'
...
---
_id: '63497'
author:
- first_name: Nikolas
full_name: Förster, Nikolas
last_name: Förster
- first_name: Oliver
full_name: Wallscheid, Oliver
last_name: Wallscheid
- first_name: Frank
full_name: Schafmeister, Frank
last_name: Schafmeister
citation:
ama: 'Förster N, Wallscheid O, Schafmeister F. Dual-Active Bridge Sequential Pareto
Optimization for Fast Pre-Design and Final Component Selection. In: 2024 IEEE
Design Methodologies Conference (DMC). ; 2024:1-8. doi:10.1109/DMC62632.2024.10812131'
apa: Förster, N., Wallscheid, O., & Schafmeister, F. (2024). Dual-Active Bridge
Sequential Pareto Optimization for Fast Pre-Design and Final Component Selection.
2024 IEEE Design Methodologies Conference (DMC), 1–8. https://doi.org/10.1109/DMC62632.2024.10812131
bibtex: '@inproceedings{Förster_Wallscheid_Schafmeister_2024, title={Dual-Active
Bridge Sequential Pareto Optimization for Fast Pre-Design and Final Component
Selection}, DOI={10.1109/DMC62632.2024.10812131},
booktitle={2024 IEEE Design Methodologies Conference (DMC)}, author={Förster,
Nikolas and Wallscheid, Oliver and Schafmeister, Frank}, year={2024}, pages={1–8}
}'
chicago: Förster, Nikolas, Oliver Wallscheid, and Frank Schafmeister. “Dual-Active
Bridge Sequential Pareto Optimization for Fast Pre-Design and Final Component
Selection.” In 2024 IEEE Design Methodologies Conference (DMC), 1–8, 2024.
https://doi.org/10.1109/DMC62632.2024.10812131.
ieee: 'N. Förster, O. Wallscheid, and F. Schafmeister, “Dual-Active Bridge Sequential
Pareto Optimization for Fast Pre-Design and Final Component Selection,” in 2024
IEEE Design Methodologies Conference (DMC), 2024, pp. 1–8, doi: 10.1109/DMC62632.2024.10812131.'
mla: Förster, Nikolas, et al. “Dual-Active Bridge Sequential Pareto Optimization
for Fast Pre-Design and Final Component Selection.” 2024 IEEE Design Methodologies
Conference (DMC), 2024, pp. 1–8, doi:10.1109/DMC62632.2024.10812131.
short: 'N. Förster, O. Wallscheid, F. Schafmeister, in: 2024 IEEE Design Methodologies
Conference (DMC), 2024, pp. 1–8.'
date_created: 2026-01-06T08:06:24Z
date_updated: 2026-01-06T08:07:50Z
department:
- _id: '52'
doi: 10.1109/DMC62632.2024.10812131
keyword:
- 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
language:
- iso: eng
page: 1-8
publication: 2024 IEEE Design Methodologies Conference (DMC)
status: public
title: Dual-Active Bridge Sequential Pareto Optimization for Fast Pre-Design and Final
Component Selection
type: conference
user_id: '83383'
year: '2024'
...
---
_id: '34209'
abstract:
- lang: eng
text: 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:
- first_name: Yuhao
full_name: Shi, Yuhao
last_name: Shi
- first_name: Sven
full_name: Harzheim, Sven
last_name: Harzheim
- first_name: Martin
full_name: Hofmann, Martin
last_name: Hofmann
- first_name: Thomas
full_name: Wallmersperger, Thomas
last_name: Wallmersperger
citation:
ama: 'Shi Y, Harzheim S, Hofmann M, Wallmersperger T. A Damage Model for Corrosion
Fatigue Due to Hydrogen Embrittlement. In: Material Modeling and Structural
Mechanics. Springer International Publishing; 2022. doi:10.1007/978-3-030-97675-0_9'
apa: Shi, Y., Harzheim, S., Hofmann, M., & Wallmersperger, T. (2022). A Damage
Model for Corrosion Fatigue Due to Hydrogen Embrittlement. In Material Modeling
and Structural Mechanics. Springer International Publishing. https://doi.org/10.1007/978-3-030-97675-0_9
bibtex: '@inbook{Shi_Harzheim_Hofmann_Wallmersperger_2022, place={Cham}, title={A
Damage Model for Corrosion Fatigue Due to Hydrogen Embrittlement}, DOI={10.1007/978-3-030-97675-0_9},
booktitle={Material Modeling and Structural Mechanics}, publisher={Springer International
Publishing}, author={Shi, Yuhao and Harzheim, Sven and Hofmann, Martin and Wallmersperger,
Thomas}, year={2022} }'
chicago: 'Shi, Yuhao, Sven Harzheim, Martin Hofmann, and Thomas Wallmersperger.
“A Damage Model for Corrosion Fatigue Due to Hydrogen Embrittlement.” In Material
Modeling and Structural Mechanics. Cham: Springer International Publishing,
2022. https://doi.org/10.1007/978-3-030-97675-0_9.'
ieee: 'Y. Shi, S. Harzheim, M. Hofmann, and T. Wallmersperger, “A Damage Model for
Corrosion Fatigue Due to Hydrogen Embrittlement,” in Material Modeling and
Structural Mechanics, Cham: Springer International Publishing, 2022.'
mla: Shi, Yuhao, et al. “A Damage Model for Corrosion Fatigue Due to Hydrogen Embrittlement.”
Material Modeling and Structural Mechanics, Springer International Publishing,
2022, doi:10.1007/978-3-030-97675-0_9.
short: 'Y. Shi, S. Harzheim, M. Hofmann, T. Wallmersperger, in: Material Modeling
and Structural Mechanics, Springer International Publishing, Cham, 2022.'
date_created: 2022-12-05T20:53:13Z
date_updated: 2023-01-02T11:10:26Z
department:
- _id: '630'
doi: 10.1007/978-3-030-97675-0_9
keyword:
- Hydrogen embrittlement
- Fatigue
- Continuum damage mechanics
- Numerical simulation
- Multi-field problem
language:
- iso: eng
place: Cham
project:
- _id: '130'
grant_number: '418701707'
name: 'TRR 285: TRR 285'
- _id: '132'
name: 'TRR 285 - B: TRR 285 - Project Area B'
- _id: '142'
name: 'TRR 285 – B03: TRR 285 - Subproject B03'
publication: Material Modeling and Structural Mechanics
publication_identifier:
isbn:
- '9783030976743'
- '9783030976750'
issn:
- 1869-8433
- 1869-8441
publication_status: published
publisher: Springer International Publishing
status: public
title: A Damage Model for Corrosion Fatigue Due to Hydrogen Embrittlement
type: book_chapter
user_id: '14931'
year: '2022'
...
---
_id: '9784'
abstract:
- lang: eng
text: 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:
- first_name: Matthias
full_name: Hunstig, Matthias
last_name: Hunstig
- first_name: Tobias
full_name: Hemsel, Tobias
last_name: Hemsel
- first_name: Walter
full_name: Sextro, Walter
last_name: Sextro
citation:
ama: 'Hunstig M, Hemsel T, Sextro W. An efficient simulation technique for high-frequency
piezoelectric inertia motors. In: Ultrasonics Symposium (IUS), 2012 IEEE International.
; 2012:277-280. doi:10.1109/ULTSYM.2012.0068'
apa: Hunstig, M., Hemsel, T., & Sextro, W. (2012). An efficient simulation technique
for high-frequency piezoelectric inertia motors. In Ultrasonics Symposium (IUS),
2012 IEEE International (pp. 277–280). https://doi.org/10.1109/ULTSYM.2012.0068
bibtex: '@inproceedings{Hunstig_Hemsel_Sextro_2012, title={An efficient simulation
technique for high-frequency piezoelectric inertia motors}, DOI={10.1109/ULTSYM.2012.0068},
booktitle={Ultrasonics Symposium (IUS), 2012 IEEE International}, author={Hunstig,
Matthias and Hemsel, Tobias and Sextro, Walter}, year={2012}, pages={277–280}
}'
chicago: Hunstig, Matthias, Tobias Hemsel, and Walter Sextro. “An Efficient Simulation
Technique for High-Frequency Piezoelectric Inertia Motors.” In Ultrasonics
Symposium (IUS), 2012 IEEE International, 277–80, 2012. https://doi.org/10.1109/ULTSYM.2012.0068.
ieee: M. Hunstig, T. Hemsel, and W. Sextro, “An efficient simulation technique for
high-frequency piezoelectric inertia motors,” in Ultrasonics Symposium (IUS),
2012 IEEE International, 2012, pp. 277–280.
mla: Hunstig, Matthias, et al. “An Efficient Simulation Technique for High-Frequency
Piezoelectric Inertia Motors.” Ultrasonics Symposium (IUS), 2012 IEEE International,
2012, pp. 277–80, doi:10.1109/ULTSYM.2012.0068.
short: 'M. Hunstig, T. Hemsel, W. Sextro, in: Ultrasonics Symposium (IUS), 2012
IEEE International, 2012, pp. 277–280.'
date_created: 2019-05-13T13:20:17Z
date_updated: 2022-01-06T07:04:20Z
department:
- _id: '151'
doi: 10.1109/ULTSYM.2012.0068
keyword:
- 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
language:
- iso: eng
page: 277-280
publication: Ultrasonics Symposium (IUS), 2012 IEEE International
publication_identifier:
issn:
- 1948-5719
quality_controlled: '1'
status: public
title: An efficient simulation technique for high-frequency piezoelectric inertia
motors
type: conference
user_id: '55222'
year: '2012'
...