Navigation

Springe zum Hauptinhalt
Fakultät für Maschinenbau
Technische Mechanik/Dynamik

Julian Dietzsch M. Sc.

2010-2013: Bachelorstudium Maschinenbau, Vertiefung Angewandte Mechanik und Thermodynamik, TU Chemnitz
2013-2016: Masterstudium Maschinenbau, Vertiefung Angewandte Mechanik und Thermodynamik, TU Chemnitz
2016-jetzt: Wissenschaftlicher Mitarbeiter, Professur TMD, TU Chemnitz
  • DFG-Projekt: GR 3297/4-1
    Physikalisch-konsistente Simulation der Thermodynamik faserverstärkter Kunststoffe
  • DFG-Projekt: GR 3297/4-2
    Physikalisch-konsistente Simulation der Thermodynamik faserverstärkter Kunststoffe

Publikationen im Jahr 2020

  • Dietzsch J., Groß M., and Schuffenhauer R. F. (2020), Mixed finite element formulations and energy-momentum time integrators for thermo-mechanical coupled fiber-reinforced continua, Proc. Appl. Math. Mech., 20, submitted.
  • Groß M., Dietzsch J. and Kalaimani I. (2020), ENERGY-MOMENTUM SCHEME WITH DRILLING DEGREES OF FREEDOM FOR COMPOSITES WITH CURVATURE-TWIST STIFFNESS. ECCOMAS conference ECCM-ECFD 2018 - 14th World Congress on Computational Mechanics (WCCM) - ECCOMAS Congress 2020) Paris F, 19-24 July 2020, submitted.
  • Groß M., Dietzsch J. and Röbiger C. (2020), An energy-momentum space-time discretization of a constrained micropolar continuum for 3D fiber-reinforced composites, Proc. Appl. Math. Mech., 20, submitted.
  • Groß M., Dietzsch J. and Röbiger C. (2020), Non-isothermal energy-momentum time integrations with drilling degrees of freedom of composites with viscoelastic fiber bundles and curvature-twist stiffness, Computer Methods in Applied Mechanics and Engineering, 365, 2020. doi.org/10.1016/j.cma.2020.112973.

Publikationen im Jahr 2019

  • Groß M., Dietzsch J. and Röbiger C. (2018), Locking-free higher-order energy-momentum schemes for thermo-viscoelastic fiber-reinforced materials derived by the principle of virtual power, INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS 2018, AIP Conference Proceedings 2116:340004, 2019 doi.org/10.1063/1.5114350 .
  • Dietzsch J., Groß M. and Flessing L. (2019), Mixed finite element formulations and energy-momentum time integrators for thermo-mechanically coupled fiber-reinforced continua, 8th GACM Colloquium on Computational Mechanics, University of Kassel, Germany, August 28-30, 2019. ISBN 978-3-86219-5093-9 .
  • Dietzsch J., Groß M. and Flessing L. (2019), THERMO-MECHANICAL COUPLING IN FIBER-REINFORCED CONTINUA: MIXED FINITE ELEMENT FORMULATIONS AND ENERGY-MOMENTUM TIME INTEGRATION, VIII International Conference on Computational Methods for Coupled Problems in Science and Engineering, Sitges (Barcelona), Spain, 3-5 June 2019. ISBN: 978-84-949194-5-9 .
  • Groß M., Dietzsch J. and Röbiger C. (2019), A higher-order energy-momentum scheme for a non-isothermal two-phase dissipation model of fibrous composites, 8th GACM Colloquium on Computational Mechanics, University of Kassel, Germany, August 28-30, 2019. ISBN 978-3-86219-5093-9 .
  • Groß M., Dietzsch J. and Röbiger C. (2019), A variational-based energy-momentum time integration of metamaterials in non-isothermal rotordynamical systems, 8th GACM Colloquium on Computational Mechanics, University of Kassel, Germany, August 28-30, 2019. ISBN 978-3-86219-5093-9 .
  • Groß M., Dietzsch J. and Röbiger C. (2019), ENERGY-MOMENTUM TIME INTEGRATIONS OF A NON-ISOTHERMAL TWO-PHASE DISSIPATION MODEL FOR FIBER-REINFORCED MATERIALS BASED ON A VIRTUAL POWER PRINCIPLE, VIII International Conference on Computational Methods for Coupled Problems in Science and Engineering, Sitges (Barcelona), Spain, 3-5 June 2019. ISBN: 978-84-949194-5-9 .
  • Groß M., Dietzsch J. and Röbiger C. (2019), A mixed variational-based dynamic simulation method for fiber-reinforced continua in non-isothermal rotordynamical systems, Proc. Appl. Math. Mech., 19 . doi:10.1002/pamm.201900009.
  • Bartelt M., Klöckner O., Dietzsch J. and Groß M. (2018), Higher order finite elements in space and time for anisotropic simulations with variational integrators. Application of an efficient GPU implementation, Mathematics and Computers in Simulation, 2019, in press. DOI 10.1016/j.matcom.2019.09.018.
  • Groß M., Dietzsch J. and Röbiger C. (2019), A mixed B-bar formulation derived by a principle of virtual power for energy-momentum time integrations of fiber-reinforced continua, Computer Methods in Applied Mechanics and Engineering, 350: 595-640, 2019. doi.org/10.1016/j.cma.2019.03.027.
  • Groß M. and Dietzsch J. (2019), Variational-based locking-free energy–momentum schemes of higher-order for thermo-viscoelastic fiber-reinforced continua, Computer Methods in Applied Mechanics and Engineering, 343: 631-671, 2019. DOI 10.1016/j.cma.2018.08.030.

Publikationen im Jahr 2018

  • Bartelt M., Dietzsch J. and Groß M. (2018), Efficient implementation of energy conservation for higher order finite elements with variational integrators, Mathematics and Computers in Simulation, 150: 83-121, 2018. DOI 10.1016/j.matcom.2018.03.002.
  • Groß M., Dietzsch J. and Bartelt M. (2018), Thermo-viscoelastic fiber-reinforced continua simulated by variational-based higher-order energy-momentum schemes, Proc. Appl. Math. Mech., 18: 1-2. doi: 10.1002/pamm.201800003.
  • Dietzsch J. and Groß M. (2018), MIXED FINITE ELEMENT FORMULATIONS FOR THE GALERKIN-BASED TIME INTEGRATION OF FINITE ANISOTROPIC ELASTODYNAMICS. ECCOMAS conference ECCM-ECFD 2018 - 6th European Conference on Computational Mechanics (ECCM 6), Glasgow UK, 11-15 June 2018 pdf
  • Groß M. and Dietzsch J. (2018), A MIXED ASSUMED STRAIN FINITE ELEMENT FORMULATION FOR VARIATIONAL- BASED ENERGY-MOMENTUM TIME INTEGRATIONS IN THERMODYNAMICS OF FIBER-REINFORCED CONTINUA. ECCOMAS conference ECCM-ECFD 2018 - 6th European Conference on Computational Mechanics (ECCM 6), Glasgow UK, 11-15 June 2018 pdf
  • Groß M., Dietzsch J. and Bartelt M. (2018), Variational-based higher-order accurate energy–momentum schemes for thermo-viscoelastic fiber-reinforced continua, Computer Methods in Applied Mechanics and Engineering, 336: 353-418, 2018. DOI 10.1016/j.cma.2018.03.019.

Publikationen im Jahr 2017

  • Groß M. and Dietzsch J. (2017), Dynamic thermo-mechanical coupling in fiber-reinforced bodies simulated by higher-order variational energy-momentum schemes, Proceedings of 3rd International Conference on Multiscale Methods for Solids and Fluids, 2017, ISBN 978-961-6884-48-8.
  • Groß M. and Dietzsch J. (2017), Variational-based energy–momentum schemes of higher-order for elastic fiber-reinforced continua, Computer Methods in Applied Mechanics and Engineering, 320: 509-542, 2017. doi.org/10.1016/j.cma.2017.03.018.
  • Dietzsch J. and Groß M. (2017), Locking free elements for polyconvex anisotropic material formulations, Proceedings of RCM 2017 - Research Challenges in Mechanics RCM2017 .
  • Groß M. and Dietzsch J. (2017), Variational-based higher-order energy-momentum schemes with incompatible modes for fiber-reinforced materials, INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS 2016, AIP Conference Proceedings 1863:320005, 2017, doi.org/10.1063/1.4992486 .

Publikationen im Jahr 2016

  • Groß M., Ramesh R. and Dietzsch J. (2016), ENERGY AND MOMENTUM CONSERVING VARIATIONAL BASED TIME INTEGRATION OF ANISOTROPIC HYPERELASTIC CONTINUA. ECCOMAS Congress 2016 VII European Congress on Computational Methods in Applied Sciences and Engineering Crete Island, Greece, 5-10 June 2016, ID 7883, 24 S., 2016
  • Groß M., Ramesh R. and Dietzsch J. (2016), Galerkin-based Energy-Momentum Time-Stepping Schemes for anisotropic hyperelastic Materials, Proc. Appl. Math. Mech., 16: 199-200. doi: 10.1002/pamm.201610088.

GACM 2019

Fiber-reinforced materials in lightweight structures and their accurate dynamic simulation play an even increasingly significant role today. These materials are used in aircraft, automobiles and wind turbines, for example. Their low density and their high modulus of elasticity play a major role, but also the thermal properties should not be neglected. First of all, the thermal expansion of the matrix part and the ability to conduct the heat in a directional way with the fibers. For these materials, volumetric locking effects of an incompressible matrix material as well as locking effects due to stiff fibers can occur. On the one hand, there are combinations of well known mixed finite elements with an independent approximation of the determinant of the deformation gradient and an independent approximation of the right Cauchy green tensor for the anisotropic part of the strain energy function to reduce these effects. On the other hand, we have developed mixed finite elements where fields for the fourth and fifth invariants are added, as well as a version with the corresponding tensor fields. For long-term simulations it is necessary to use higher order time integrators to perform an accurate dynamic simulation. Galerkin-based time integrators offer a good option for this application. To eliminate a huge energy error these have to be extended to an energy-momentum time integration scheme. It is logical to combine these methods and thus combine the advantages of these methods. We formulate the mixed finite elements by using Hu-Washizu functionals in a mixed principle of virtual power. By adding a thermo-mechanical coupling part in the strain energy and introducing the fourier heat conduction we obtain a thermo-mechanical formulation for the different mixed finite elements and a higher order Galerkin-based time integrator. Dirichlet boundary conditions in the form of Lagrange multiplier methods as well as Neumann boundary conditions in the mechanical and thermal context are also provided. In addition, we extend the continuum so that we can model different fiber families and the directional heat conduction of the fibers. As numerical examples serve cook's cantilever beam as well as a rotating heat pipe. We primarily analyze the spatial and time convergence, the conservation properties as well as the effect of the heat conduction of the fibers.

ECCOMAS Coupled 2019

Our research activity is motivated by dynamic simulations of fiber-reinforced materials in light-weight structures. In order to accomplish this, we have to take various steps. The material behavior is formulated with an anisotropic, polyconvex strain energy function. We combine different mixed element formulations (e.g. see Reference Schröder, J., Wriggers, P., Balzani, D. (2011) A new mixed finite element based on different approximations of the minors of deformation tensors. Comput. Methods Appl. Mech. Engrg., 49:3583--3600 or Schröder, J., Viebahn, V., Wriggers, P., Balzani, D. (2016) A novel mixed finite element for finite anisotropic elasticity; the SKA-element Simplified Kinematics for Anisotropy. Comput. Methods Appl. Mech. Engrg., 310:475--494 with a Galerkin time integrator as shown in Reference Dietzsch J. and Groß M. (2018), MIXED FINITE ELEMENT FORMULATIONS FOR THE GALERKIN-BASED TIME INTEGRATION OF FINITE ANISOTROPIC ELASTODYNAMICS. ECCOMAS conference ECCM-ECFD 2018 - 6th European Conference on Computational Mechanics (ECCM 6), Glasgow UK, 11-15 June 2018. This reduces the volumetric locking effect of the matrix part as well as the locking effect of the stiff fiber. In addition, we increase the accuracy by using higher-order time integrators. For long-term simulations a hugh energy error is a strong problem. Therefor we extend this element formulations to an energy conserving time integration (see Reference Gross, M., Dietzsch., J. (2017) Variational-based energy–momentum schemes of higher-order for elastic fiber-reinforced continua. Comput. Methods Appl. Mech. Engrg., 320:509--542). In the next step, we will extend these formulations by adding a thermo-mechanical coupling. Here we will also describe the directional heat conduction of the fiber. As numerical examples serve cooks cantilever beam and a rotating heatpipe with multiple material domains and families of fibers. The Dirichlet boundary conditions are modelled by Lagrange-multiplier method (see Reference Groß M., Dietzsch J. and Bartelt M. (2018), Variational-based higher-order accurate energy–momentum schemes for thermo-viscoelastic fiber-reinforced continua, Computer Methods in Applied Mechanics and Engineering, 336: 353-418, 2018) and as Neumann boundary condition a pressure distribution is used.

ECCM 2018

Our research is motivated by dynamic simulations of fiber-reinforced materials in light-weight structures. For the description ofthe material behavior we use ahyperelastic, transversely isotropic and polyconvex formulation. On the one hand side wewant to reduce the volumetric locking effect of the matrix part. Here we use well knownmixed element formulations like the Displacment-Pressure formulation presented in Simo, J., Taylor, R., Pister., K., 1985. Variational and projection methods for the volume constraint in finite deformation elasto-plasticity. Computer Methods in Applied Mechanics and Engineering 1:177-208 ,or the so called CoFEM element shown in Schröder, J., Wriggers, P., Balzani, D., 2011. A new mixed finite element based on different approximations of the minors of deformation tensors. Computer Methods in Applied Mechanics and Engineering 49:3583–3600. Also we want to reduce the locking effectof the very stiff fiber as well. In Schröder, J., Viebahn, V., Wriggers, P., Balzani, D., 2016. A novel mixed finiteelement for finite anisotropic elasticity; the SKA-element Simplified Kinematics forAnisotropy. Computer Methods in Applied Mechanics and Engineering 310:475–494 is shown a new efficient mixed element formulation,called SKA element. On the other hand side, we want to perform long-term simulations and require accurate high-order time integrators. We use a Galerkin integrator with higher-order finite elements in time (see Erler N. and Groß M., 2015. Energy-momentum conserving higher-order time integra-tion of nonlinear dynamics of finite elastic fiber-reinforced continua. Computational Mechanics 55:921–942). To obtain a solutionwe combine both, mixed finite elements and the Galerkin time integrator, to reduce the locking effects and reach a highaccuracy. We compare the new elements with standard methodsfor hexahedral elementsup to a cubic approximation in space. As numerical example serves the well-known cooks cantilever beam (see Schr ̈oder, J., Wriggers, P., Balzani, D., 2011. A new mixed finite element based ondifferent approximations of the minors of deformation tensors. Computer Methodsin Applied Mechanics and Engineering 49:3583–3600). The Dirichlet boundary conditions aremodeled by using Lagrange multipliers and as Neumann boundary condition a pressure distribution is used.

RCM 2017

Our research activity takes place within the DFG project GR 3297/4-1. The target is the development of a new locking free energy consistent time integrator for a polyconvex anisotropic material formulation. In the first step we compare a non-standard mixed finite element \cite{schroeder2011} with standard methods for tetrahedral and hexahedral elements for bodies with multiple material domains and anisotropy directions within a static analysis. In the next steps we aim at the extension of this formulation to a dynamic system (see Erler N. and Gross M., 2015. Energy-momentum conserving higher-order time integration of nonlinear dynamics of finite elastic fiber-reinforced continua. Computational Mechanics 55:921--942) and to thermo-viscoelastic material behaviour.

Presseartikel