Tobias Karl Tobias Karl

Dr.-Ing. Tobias Karl

  • Former Research Assistant at ITM and ISTM
  • Karlsruher Institut für Technologie (KIT)
    Kaiserstraße 10
    Gebäude: 10.23
    76131 Karlsruhe

Curriculum Vitae

1/2025 Ph.D. at the Institute of Engineering Mechanics, Chair for Continuum Mechanics,
in collaboration with the Institute of Fluid Mechanics, Karlsruhe Institute of Technology (KIT)
Doctoral Disseration: “Micromechanical Modeling of Short-Fiber Orientation Dynamics”
02/2020–07/2024 Research Assistant, Institute of Engineering Mechanics, Chair for Continuum Mechanics,
in collaboration with the Institute of Fluid Mechanics, Karlsruhe Institute of Technology (KIT)
04/2017–11/2019 Studies of Mechanical Engineering (Master), Karlsruhe Institute of Technology (KIT)
Specialization: Theoretical Mechanical Engineering
Focus Areas: Applied Mechanics and Fluid Mechanics
09/2016–03/2017 Internship in modeling and simulation of fiber reinforced polymers,
Schaeffler Technologies AG & Co  KG, Herzogenaurach
10/2013–03/2017 Studies of Mechanical Engineering (Bachelor), Karlsruhe Institute of Technology (KIT)
Major Field: "Continuum Mechanics and Strength of Materials"

Field of Research

Fluid Mechanics and Homogenization of Anisotropic Flow Processes

During the processing of fiber-reinforced polymer materials by injection molding, the orientation of the fibers is determined by the flow field in the polymer melt. Since the orientation of the fibers significantly influences the anisotropic elastic properties of the manufactured part, a precise prediction of the orientation state at the end of mold filling is of great interest. The fibers induce an anisotropic viscous behavior of the fiber suspension that influences the flow field already during mold filling. One aim of the project is to investigate this so-called flow-fiber coupling with regard to the related effects on the predicted mechanical properties. The focus here is on micromechanical approaches for both the fiber-polymer melt and the composite.

In engineering practice, tensors are used to describe the orientation state, which are obtained by solving a suitable evolution equation. Since these equations are not closed, suitable approaches are required to close them. Another aim of the project is to develop closure methods that are both numerically efficient and accurately predict the evolution of the fiber orientation. In addition, closures are also used to predict the anisotropic viscous and elastic properties. The suitability of the developed closures in this context represents a further research objective.

Publications


Micromechanical Modeling of Short-Fiber Orientation Dynamics. PhD dissertation
Karl, T.
2025, September 16. KIT Scientific Publishing. doi:10.5445/KSP/1000180614
Generalized micromechanical formulation of fiber orientation tensor evolution equations
Karl, T.; Böhlke, T.
2024. International Journal of Mechanical Sciences, 263, Art.-Nr.: 108771. doi:10.1016/j.ijmecsci.2023.108771
On fully symmetric implicit closure approximations for fiber orientation tensors
Karl, T.; Schneider, M.; Böhlke, T.
2023. Journal of Non-Newtonian Fluid Mechanics, 318, 105049. doi:10.1016/j.jnnfm.2023.105049
Influence of flow–fiber coupling during mold-filling on the stress field in short-fiber reinforced composites
Karl, T.; Zartmann, J.; Dalpke, S.; Gatti, D.; Frohnapfel, B.; Böhlke, T.
2023. Computational Mechanics, 71 (5), 991–1013. doi:10.1007/s00466-023-02277-z
Asymptotic fiber orientation states of the quadratically closed Folgar-Tucker equation and a subsequent closure improvement
Karl, T.; Gatti, D.; Frohnapfel, B.; Böhlke, T.
2021. Journal of Rheology, 65 (5), 999–1022. doi:10.1122/8.0000245
Coupled simulation of flow-induced viscous and elastic anisotropy of short-fiber reinforced composites
Karl, T.; Gatti, D.; Böhlke, T.; Frohnapfel, B.
2021. Acta mechanica, 232 (6), 2249–2268. doi:10.1007/s00707-020-02897-z

Conferences

2024

Karl, T., Böhlke, T.:
A generalized homogenization approach to describe the orientation dynamics of fiber suspensions
16th World Congress on Computational Mechanics, 21.-26.07.2024, Vancoucer, Canada

2023

Karl, T., Schneider, M., Böhlke, T.:
Implicit fiber orientation tensor closures
MathSEE Symposium on Applications of Mathematical Sciences, 27.-29.09.2023, Karlsruhe, Germany

Karl, T., Schneider, M., Böhlke, T.:
Fiber orientation tensor approximations based on an implicitly defined closure approach
International Conference on Composite Materials, 30.07.-04.08.2023, Belfast, Northern Ireland

Karl, T., Zartmann, J., Dalpke, S., Gatti, D., Frohnapfel, B., Böhlke, T.:
Mean-field based modeling of anisotropic viscosity and flow-fiber coupled mold-filling simulation of short-fiber suspensions
16th International Conference on Advanced Computational Engineering and Experimenting, 03.-07.07.2023, Heraklion, Crete

Karl, T., Böhlke, T.:
Flow-fiber coupling of mold-filling fiber suspension simulations based on anisotropic viscosity and mean-field modeling
IRTG/ICRG Summer School 2023, 20.06.2023, WissenschaftsForum Berlin, Germany

Böhlke, T., Karl, T., Sterr, B., Krause, M., Gajek, S.:
Skalenübergreifende kontinuumsmechanische Modellierung von Kompositen und Polykristallen
Abschiedskolloquium H. Altenbach, 12.05.2023, Otto-von-Guericke-Universität Magdeburg, Germany

Karl, T., Böhlke, T.:
Mean-Field basierte Fließsimulationen von Fasersuspensionen unter Berücksichtigung anisotroper Viskosität
Kolloquium der Materialwissenschaft und Werkstofftechnik, 31.01.2023, Universität des Saarlandes, Saarbrücken, Germany

2022

Karl, T., Gatti, D., Frohnapfel, B., Böhlke, T.:
Asymptotic fiber orientation states of the quadratically closed Folgar-Tucker equation and a subsequent closure improvement
8th ECCOMAS Congress 2022, 05.-09.06.2022, Oslo, Norway

2021

Karl, T., Gatti, D., Frohnapfel, B., Böhlke, T.:
Coupled simulation of flow-induced viscous and elastic anisotropy of short-fiber reinforced composites
91st GAMM Annual Meeting 2020@21, 15.-19.03.2021, Kassel, Germany

Academic Teaching

Summer Semester 2024

  • Vertretung ausgewählter Vorlesungen in Mathematische Methoden der Mikromechanik (MMM)
  • Übungen zu Mathematische Methoden der Mikromechanik (MMM)

Winter Semester 2023/2024

  • Übungen zu Kontinuumsmechanik der Festkörper und Fluide (KMFF)
  • Rechnerübungen zu Kontinuumsmechanik der Festkörper und Fluide (KMFF)

Summer Semester 2023

  • Vertretung ausgewählter Vorlesungen in Mathematische Methoden der Mikromechanik (MMM)
  • Übungen zu Mathematische Methoden der Mikromechanik (MMM)
  • Übungen zu Nonlinear Continuum Mechanics (NCM)

Winter Semester 2022/2023

  • Übungen zu Kontinuumsmechanik der Festkörper und Fluide (KMFF)
  • Rechnerübungen zu Kontinuumsmechanik der Festkörper und Fluide (KMFF)

Summer Semester 2022

  • Übungen zu Mathematische Methoden der Mikromechanik (MMM)
  • Übungen zu Nonlinear Continuum Mechanics (NCM)

Winter Semester 2021/2022

  • Übungen zu Kontinuumsmechanik der Festkörper und Fluide (KMFF)
  • Rechnerübungen zu Kontinuumsmechanik der Festkörper und Fluide (KMFF)

Summer Semester 2021

  • Übungen zu Mathematische Methoden der Mikromechanik (MMM)
  • Übungen zu Nonlinear Continuum Mechanics (NCM)

Winter Semester 2020/2021

  • Übungen zu Kontinuumsmechanik der Festkörper und Fluide (KMFF)
  • Rechnerübungen zu Kontinuumsmechanik der Festkörper und Fluide (KMFF)

Summer Semester 2020

  • Rechnerübungen zu Einführung in die Finite-Elemente-Methode (FEM)
  • Übungen zu Mathematische Methoden der Mikromechanik (MMM)