ResearchResearch projects
A Consistent Hybrid Approach with Machine Learning for Time Dependent Constitutive Modelling

Forschungsprojekte_Relaunch

  • Computational mechanics in terms of mixed aleatory and epistemic uncertain random fields
    This project investigates probability box (p-box) approach including probabilistic and possibilistic aspects. This way, both kind of uncertainties - aleatory and epistemic - can be considered within a random field.
    Leaders: Udo Nackenhorst, Amélie Fau
    Team: Mona Madlen Dannert, Rodolfo Fleury
    Year: 2016
    Sponsors: Priority Programme SPP 1886 of German Research Foundation (DFG), State of Lower Saxony
  • Reduced Order Modelling in Non-Linear Structural Mechanics
    Finite Element Methods are well established in structural mechanics, however, in many engineering applications fast numerical evaluations of parametric solutions are required, e.g. for optimisation, sensitivity analysis or uncertainty quantification. Model Order Reduction (MOR) are currently under investigation for drastically reduction of the computational effort in comparison to FEM simulations. However, to this point no clear guidelines on the treatment of non-linearity have been developed. In this project kernel based methods will be investigated with regard to their performance on tackling non-linear structural dynamics problems, in particular for structural failure to loss of material resistance. A goal oriented comparison of different branches of kernel-based methods, i.e. kernel POD, support vector regression and Kriging with special emphasis on damage and plasticity is performed.
    Leaders: Udo Nackenhorst
    Team: Steffen Funk
    Year: 2017
  • Meso-scale finite element modeling of concrete damage under fatigue loading
    Within the scope of this project, the mechanism of concrete damage under cyclic loading conditions will be invistigated at the meso-scale. At this scale, concrete will be considered as non-homogeneous three-phase composite material which consists of cement matrix (mortar), aggregates and interfacial transition zone (ITZ).
    Leaders: Udo Nackenhorst
    Team: Mohammed Hammad
    Year: 2018
    Sponsors: DAAD (German Academic Exchange Service)
  • Variational multiscale based data driven modeling of subgrid scales for fluid mechanics applications
    In recent work, we have cast various non-standard finite element formulations for advection based PDEs in the variational multiscale framework. Examples are Nitsche’s formulation and discontinuous Galerkin methods. This formalism has revealed the implicit multiscale decomposition inherent to these methods. Now, we extend upon this formalism and aim to develop localization techniques for the remaining fine scale interaction. Even after localization, determining the true scale interaction remains computationally expensive. During an offline stage, we produce training data of precise scale interaction for ranges of element shapes and underlying advective fields. A trained machine learning algorithm is used during the online phase to approximate the interaction with the unresolved scales, i.e., the turbulent subgrid scales. Our goal is thus to develop a highly capable, data driven, turbulence modeling tool with a mathematically rigorously foundation.
    Leaders: Dominik Schillinger
    Team: Stein Stoter
    Year: 2020
    Sponsors: Deutsche Forschungsgemeinschaft (DFG) via the Emmy Noether Award SCH 1249/2-1
    Field of influence of the fine scales for a classical method (left) and a discontinuous Galerkin method (right). Field of influence of the fine scales for a classical method (left) and a discontinuous Galerkin method (right).
  • Concurrent material and structure optimization of multiphase hierarchical systems
    In this project, we develop a concurrent material and structure optimization framework for hierarchical systems that relies on continuum micromechanics estimates for multiscale analysis. The analytical nature of these estimates enables simple constraint optimization problems at the material level that are essentially independent of the number of hierarchical scales, rendering our framework computationally tractable for multiphase hierarchical systems. After successfully establishing the framework for overall linear elastic behavior, we are currently working on extending our framework to inelasticity that originates from the material microscales in hierarchical systems. The methodology developed in this project could open up new possibilities for genetic tailoring of plant materials, multiscale bone remodeling, or fabrication of bioinspired engineering materials.
    Leaders: Dominik Schillinger
    Team: Tarun Gangwar
    Year: 2020
  • Development of a Coupled BCHM-Model for Numerical investigations of MICP treatment of soil
    Microbially induced calcite precipitation (MICP) offers the potential for the development of environmentally friendly and cost-effective solutions to a wide range of geotechnical engineering problems, from “improvement of the soft underground” to “control of groundwater contamination”.
    Leaders: Udo Nackenhorst
    Team: Xuerui Wang
    Year: 2020
    Sponsors: German Research Foundation (DFG)
    Lifespan: 2020-2022
    Figures: Schematic view of the relevant processes in MICP (left) and the BCHM couplings (right) Figures: Schematic view of the relevant processes in MICP (left) and the BCHM couplings (right)
  • A Consistent Hybrid Approach with Machine Learning for Time Dependent Constitutive Modelling
    Machine learning is currently uncovering new possibilities in data-driven and meta-modelling for the field of computational mechanics. In particular, material modelling can be augmented or completely replaced with experimental results. Such techniques exist in the literature, such as data-driven material modelling.
    Leaders: Udo Nackenhorst
    Team: Darcy Beurle
    Year: 2020

Stochastic Finite Element Method

  • Stochastic Finite Elements
    In vielen ingenieurtechnischen Anwendungen sind nicht deterministische Prozesse und/oder Parameter enthalten. die das Systemverhalten in erheblichen Maßen beeinflussen.
    Team: Prof.Dr.-Ing. U. Nackenhorst, M.Sc. P.Jablonski
  • Investigations on the Numerical Solution of the Fokker-Planck Equation with Discontinuous Galerkin Methods
    As the probability density distribution is an appropriate measure for comprehensive description of stochastic processes, the derivation and solution of transport equations for the probability density requires particular attention. Examination of nonlinear dynamic systems under uncertain excitation or with uncertain parameters leads to stochastic equations of motion.
    Team: Prof.Dr.-Ing. U.Nackenhorst, Dipl.-Ing. F. Loerke
  • Development of a numerically robust material model for rock salt
    Around 300000 tons of high-level radioactive waste exists on earth and around 12000 tons of high-level radioactive waste will be added every year. Possible solutions for storage of radioactive waste are salt domes as reservoirs for toxic and nuclear waste.
    Leaders: Udo Nackenhorst
    Team: Mathias Grehn
    Year: 2011
  • Numerische Simulation probabilistischer Schädigungsmodelle mit der Stochastischen Finite Elemente Methode
    Numerische Umsetzung diverser probabilistischer Methoden, u.a. Monte Carlo Simulation, Kollokationsmethode oder Polynomial Chaos, für die Berschreibung unsicherer Materialparameter innerhalb verschiedener Schädigungsmodelle in Verbindung mit der Finite Elemente Methode
    Leaders: Udo Nackenhorst
    Team: Philipp-Paul Jablonski
    Year: 2014
  • A Stochastic Approach on Stress Adaptive Bone Remodeling
    In this project the uncertainties in stress adaptive bone remodeling are addressed. Accounting for these uncertainties stochastic techniques like Polyomial Chaos Expansion or Stochastic Collocation Methods are used in order to build a stochastic response surface for evaluating the stochastic properties, e.g. sensitivity, of the system.
    Leaders: Udo Nackenhorst
    Team: Maximilian Bittens
    Year: 2016
  • Stochastic Modeling of Fatigue Processes
    Leaders: Udo Nackenhorst
    Team: Wei Ran Zhang, Amelie Fau
    Year: 2016
    Sponsors: International Research Training Group 1627, DFG (German Research Foundation)
    Lifespan: 2016-2019
  • Computational techniques for the stochastic excitation of rolling tires from rough road surface contact
    In this project, we intend to address issues in modeling rolling tires on rough road surfaces by (a) extending previously developed methods by a stochastic excitation function describing the interaction of the macroscopic tire model and the detailed meso-mechanical contact behavior of the tire tread with the road surface; (b) including dynamic stiffening effects in the rubber compound.
    Leaders: Udo Nackenhorst
    Team: Robert Lee Gates
    Year: 2016
    Sponsors: DFG (German Research Foundation)
  • Dynamic properties of heterogeneous materials with uncertain microstructures and local damage
    The goal of this research project is the development of novel predictive techniques for damage monitoring in heterogenous materials. Multi-scale modeling techniques are combined with related statistical methods for scale bridging.
    Leaders: Udo Nackenhorst
    Team: Andre Hürkamp
    Year: 2016

Biomechanics

  • Image reconstruction / finite element modelling
    Due to the complex structure of bone it is very difficult to get geometry data for the generation of simulation models. In addition it is impossible to get patient-specific geometry data for patient-specific treatment. With this program it is possible to extract geometry data from CT datasets and generate finite element models. Furthermore it is possible to map bone density information on the created finite element model for the purpose of calculating statically equivalent load sets.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Andre Lutz
  • Studies on the biomechanical compatibility of hip-joint endoprostheses
    The biomechanical compatibility of different devices for artificial hip joint replacement is studied by use of computer simulation. Special emphasis is laid onto the bone remodelling caused from different prosthesis designs. Already these qualitative comparisons enables for rating the systems regarding their long term success.
    Team: Prof.Dr.-Ing. Udo Nackenhorst, M.Sc. Andre Lutz, ext. B. Ebbecke
  • Finite Element Evaluation of Primary Stability of Teeth Implants
    Usually dental implants are loaded after the healing period which is generally 2 to 3 months after the insertion of the implant. During the healing period the patient is dependent on liquid diet. Therefore implant technologies are heading towards implants that can be loaded directly after insertion. The aim of this project is to compare the primary stability of two dental implants, one standard model and one model with a bar for rotational stabilization.
  • Studies on bone remodelling theory based on microcracks
    Inside the cortical section of every bone, a remodelling cycle, including the resorption and build up of bone matrix, takes place. This phenomenon lasts for the life time. Research groups nowadays agree on the theory, that bone cells called osteocytes, lying inside the bone matrix, have the function as a sensor and are responsible for the remodelling behaviour – but still there is disagreement regarding to what is stimulating the cells.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dipl.-Ing.(FH) Dieter Kardas
    Sponsors: This work is supported by the Research training group 615 of the DFG (German Research Foundation)
  • Theoretical and algorithmic concepts for description of demand-adaptive bone growth
    Computational techniques for the simulation of stress-adaptive bone-remodelling have been developed and applied for the analysis of the biomechanical compatibility of hip-joint endo-prothesis. Numerical simulations are in good agreement with clinical observations and enable parameter studies for the development of optimized prosthesis designs.
    Team: Prof.Dr.-Ing. Udo Nackenhorst, M.Sc. Andre Lutz, ext. B.Ebbecke
    Sponsors: This work is in cooperation with the MHH (Medizinische Hochschule Hannover)
  • FE-Analysis of Osteons concerning the Mechanosensation of Bone Material
    The aim of this project is to localize the detection mechanism of external loads in bone tissue and simulate the formation of new osteons.
    Team: ext. C.Lenz
    Sponsors: This work is supported by the Graduiertenkolleg 615 of the DFG (German Research Foundation)
  • Bone Cell Simulations using Tensegrity Structures
    Bone quality detoriates with time, therefore it has to renew itself throughout the life. This process is called bone remodeling. It is well accepted, that osteocytes are the sensor cells for this process.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dipl.-Ing. (FH) Dieter Kardas, ext. IIya Arsenyev, Oleg Khromov
  • Finite Element Analysis of Hip Joint Contact
    Diseases and injuries of the human muscosceletal system are of particular importance in the health care systems worldwide. The overall costs in Germany including loss of production are estimated up to 100 billion Euros every year.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Kristin Fietz, M.Sc. Andre Lutz
  • An efficient approach for modeling hip joint contact
    In developed countries osteoarthritis is the major cause for artificial joint replacement. Unfortunately, the formation processes of this degeneration of cartilage and subchondral bone remain partly unknown. In this research project a three dimensional finite element model of the hip joint is developed in order to investigate the fluid cartilage contact under physiological loading conditions.
    Team: M.Sc. Kristin Fietz, Prof. Dr.-Ing Undo Nackenhorst
    Sponsors: This research is supported by the German Research Foundation under Grant NA 330/6-1.
  • Finite Element Simulation of Osseointegration of Uncemented Endoprostheses
    The term osseointegration means the ingrowth of bone into a porous coated implant. In order to simulate the osseointegration of bone implants, a bio-active interface theory is necessary.
    Team: Prof. Dr.-Ing. U. Nackenhorst, M.Sc. André Lutz
  • Finite Element Analysis of the Fracture Healing Process
    Team: Prof. Dr.-Ing. U. Nackenhorst, M.Sc. Alexander Sapotnick
    Sponsors: This project is funded by the DFG (German Research Foundation) NA-330/8-1
  • A Stochastic Approach on Stress Adaptive Bone Remodeling
    In this project the uncertainties in stress adaptive bone remodeling are addressed. Accounting for these uncertainties stochastic techniques like Polyomial Chaos Expansion or Stochastic Collocation Methods are used in order to build a stochastic response surface for evaluating the stochastic properties, e.g. sensitivity, of the system.
    Leaders: Udo Nackenhorst
    Team: Maximilian Bittens
    Year: 2016
  • Computational simulation of piezo-electrically stimulated bone adaption surrounding activated tooth implants
    This study aims for the development of active implants which provide additional electrical stimulation for bone adaption. A computational framework is presented in order to optimize new developments for activating dental implants with piezoelectric coatings.
    Leaders: Udo Nackenhorst
    Team: Seyed Alireza Shirazi Beheshtiha
    Year: 2016
    Sponsors: State of Lower Saxony

Contact Mechanics

  • A finite element tire modelling approach for car interior noise simulation
    A finite element approach for the simulation of the dynamic behaviour of tires rolling on rough roads for the car indoor noise prediction is presented. Based on a detailed finite element model valid for the nonlinear stationary rolling analysis a modal tire model to be coupled with a total vehicle dynamics simulation approach has been developed, where special care is taken on the physical consistency.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dipl.-Ing Raffeala Chiarello
  • Transient dynamic impact of inelastic solids with rough surfaces
    Since more than two decades a relative kinematic framework (ALE-description) has been widely used for rolling contact analysis of tire-road systems. The well known advantages of the ALE-formulation are the possibility of local mesh refinement in contact region and time-independent formulation of stationary elastic rolling.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Anuwat Suwannachit
    Sponsors: This work is supported by German Research Foundation (DFG)
  • ALE-interface coupling for multiscale analysis of treaded tires in rolling contact
    The Arbitrary Lagrangian Eulerian (ALE) formulation is well established for the finite element simulation of stationary as well as transient dynamics rolling contact phenomena. The method enables mesh refinements in the contact zone and a time independent formulation of stationary rolling. The inconvenience for the simulation of rolling tires is the incorrect treatment of the tread blocks due to the non axisymmetric geometry.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dip.-Ing. Raffaela Chiarello, Dipl. Ing. (FH) Ole Stegen
  • Computational Methods for Frictional Rolling Contact
    The aim of this research project is the development of efficient computation methods for the analysis of frictional rolling contact problems of elastomer solids on rigid surfaces.
    Team: ext. M. Ziefle
    Sponsors: This work is financed by the German Research Foundation (DFG), research group FOR492.
  • Modeling of electro-mechanical contact on a mesoscopic length-scale
    The aim of the project is a simulation of the electro-mechanical coupled contact behaviour between tip and surface of an afm.
    Team: ext. T. Helmich
    Sponsors: This work is supported by the Graduiertenkolleg 615 of the DFG (German Research Foundation).
  • A multi-scale approach on the transient dynamics of rolling tires
    The transient dynamic response of rolling tires, which is a major source of traffic noise nowadays, is excited from the tread impact and the road surface texture. A multi-scale approach is introduced in order to investigate the behaviour of tread rubber in contact with rough road surface at a sufficient small length-scale, which leads to the vibration of the overall structure.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Anuwat suwannachit
    Sponsors: This work is supported by German Ministry for Economics within the “Leiser Straßenverkehr 2” program
  • Finite Element Evaluation of Primary Stability of Teeth Implants
    Usually dental implants are loaded after the healing period which is generally 2 to 3 months after the insertion of the implant. During the healing period the patient is dependent on liquid diet. Therefore implant technologies are heading towards implants that can be loaded directly after insertion. The aim of this project is to compare the primary stability of two dental implants, one standard model and one model with a bar for rotational stabilization.
  • Numerical Treatment of Inelastic Constitutive Behaviour within an ALE-Framework of Rolling
    The aim of this research project is the development of efficient computation methods for the treatment of inelastic material behaviour of rolling elastomer solids.
    Team: ext. M. Ziefle
    Sponsors: This work is financed by the German Research Foundation (DFG).
  • Finite Element Analysis of Hip Joint Contact
    Diseases and injuries of the human muscosceletal system are of particular importance in the health care systems worldwide. The overall costs in Germany including loss of production are estimated up to 100 billion Euros every year.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Kristin Fietz, M.Sc. Andre Lutz
  • An efficient approach for modeling hip joint contact
    In developed countries osteoarthritis is the major cause for artificial joint replacement. Unfortunately, the formation processes of this degeneration of cartilage and subchondral bone remain partly unknown. In this research project a three dimensional finite element model of the hip joint is developed in order to investigate the fluid cartilage contact under physiological loading conditions.
    Team: M.Sc. Kristin Fietz, Prof. Dr.-Ing Undo Nackenhorst
    Sponsors: This research is supported by the German Research Foundation under Grant NA 330/6-1.
  • Finite Element Simulation of Osseointegration of Uncemented Endoprostheses
    The term osseointegration means the ingrowth of bone into a porous coated implant. In order to simulate the osseointegration of bone implants, a bio-active interface theory is necessary.
    Team: Prof. Dr.-Ing. U. Nackenhorst, M.Sc. André Lutz
  • Finite Element Analysis of the Fracture Healing Process
    Team: Prof. Dr.-Ing. U. Nackenhorst, M.Sc. Alexander Sapotnick
    Sponsors: This project is funded by the DFG (German Research Foundation) NA-330/8-1
  • Multiscale Modeling, with Applications in Contact Mechanics
    We seek for multi-scale methods with physically consistent coupling of the molecular dynamics (MD) method and the finite element methods (FEM), and apply it to contact problems. The material near the contact region will be modelled in MD models so that complicated behaviours such as dislocations, initiation of plastic deformations and crack propagation can be captured.
    Team: Prof.Dr.-Ing. U. Nackenhorst, Dr.-Ing W. Shan
    Sponsors: Deutsche Forschungsgemeinschaft (DFG), Graduiertenkolleg 614 (GRK615)
  • Numerical simulation of tire rolling noise radiation
    The structural dynamics of rolling tires is treated by a modal superposition approach whereas the underlying stationary rolling process is modeled within a nonlinear relative kinematics continuum theory.
    Year: 2013
    Sponsors: Supported by BMBF
  • Modeling and numerical simulation for the prediction of the fatigue strength of air springs
    Fatigue failure of cord-reinforced rubber composite has been the subject of extensive studies in automotive industries due to its importance in engineering applications. The classical examples of such composites are found in tires, hoses, and airsprings.
    Leaders: Udo Nackenhorst
    Team: Niraj Kumar Jha
    Year: 2014
    Sponsors: Continental Teves AG
  • Modeling and Simulation of Rolling Tires with Detailed Tread Pattern
    The analysis of tires is of importance in tire industries for determining wear phenomena, endurance and noise effects, etc. The relative kinematics framework based on ALE formulation has its main advantages in implementing the detailed contact analysis with local mesh refinement and time independent formulation of elastic stationary rolling. The weak point of the ALE formulation is that tires with detailed tread pattern cannot be simulated due to its axi symmetric constraint.
    Leaders: Udo Nackenhorst
    Team: Thirumalalagu Palanichamy
    Year: 2016
  • Computational techniques for the stochastic excitation of rolling tires from rough road surface contact
    In this project, we intend to address issues in modeling rolling tires on rough road surfaces by (a) extending previously developed methods by a stochastic excitation function describing the interaction of the macroscopic tire model and the detailed meso-mechanical contact behavior of the tire tread with the road surface; (b) including dynamic stiffening effects in the rubber compound.
    Leaders: Udo Nackenhorst
    Team: Robert Lee Gates
    Year: 2016
    Sponsors: DFG (German Research Foundation)
  • Thermo-mechanical analysis of tires in stationary rolling contact
    The optimization of tire designs towards less rolling resistance and higher durability is still a challenging task. In the recently finished project (Link to Anuwat Suwannachit 2012) a thermo-mechanical framework for the calculation of the energy dissipation in the bulk material of stationary rolling tires was developed.
    Leaders: Udo Nackenhorst
    Team: Robert Beyer
    Year: 2016
    Sponsors: German Research foundation (DFG)

Mechanics of Materials

  • A finite element tire modelling approach for car interior noise simulation
    A finite element approach for the simulation of the dynamic behaviour of tires rolling on rough roads for the car indoor noise prediction is presented. Based on a detailed finite element model valid for the nonlinear stationary rolling analysis a modal tire model to be coupled with a total vehicle dynamics simulation approach has been developed, where special care is taken on the physical consistency.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dipl.-Ing Raffeala Chiarello
  • Transient dynamic impact of inelastic solids with rough surfaces
    Since more than two decades a relative kinematic framework (ALE-description) has been widely used for rolling contact analysis of tire-road systems. The well known advantages of the ALE-formulation are the possibility of local mesh refinement in contact region and time-independent formulation of stationary elastic rolling.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Anuwat Suwannachit
    Sponsors: This work is supported by German Research Foundation (DFG)
  • Computational Methods for Frictional Rolling Contact
    The aim of this research project is the development of efficient computation methods for the analysis of frictional rolling contact problems of elastomer solids on rigid surfaces.
    Team: ext. M. Ziefle
    Sponsors: This work is financed by the German Research Foundation (DFG), research group FOR492.
  • Modeling of electro-mechanical contact on a mesoscopic length-scale
    The aim of the project is a simulation of the electro-mechanical coupled contact behaviour between tip and surface of an afm.
    Team: ext. T. Helmich
    Sponsors: This work is supported by the Graduiertenkolleg 615 of the DFG (German Research Foundation).
  • A multi-scale approach on the transient dynamics of rolling tires
    The transient dynamic response of rolling tires, which is a major source of traffic noise nowadays, is excited from the tread impact and the road surface texture. A multi-scale approach is introduced in order to investigate the behaviour of tread rubber in contact with rough road surface at a sufficient small length-scale, which leads to the vibration of the overall structure.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Anuwat suwannachit
    Sponsors: This work is supported by German Ministry for Economics within the “Leiser Straßenverkehr 2” program
  • Experimental Characterization of Mechanical Properties of Rubber
    The large strain mechanical response of rubber materials is investigated by experimental techniques. For a collective of well defined rubber systems stress softening, quasi-static hysterics, are studied by tension and compression tests. Additional experiments are performed regarding relaxation behaviour, anisotropic damage of the filler network, temperature dependency etc.
    Team: ext. M. Dämgen, R. Schuster (German Institute of Polymer Systems (DIK))
  • Non-linear theory and adaptive FEM of martensitic phase transformation with technical application
    The work concerns the micromechanical constitutive modelling, algorithmic implementation and numerical simulation of shape memory effect (SME) and superelastic effect for mono- and poly- crystalline shape memory alloys at fine strains.
    Team: Prof.em.Dr.-Ing.habil. Dr.-Ing.E.h. Dr.h.c. mult. Erwin Stein, M.Sc. Gautam Sagar
    Sponsors: This work is financed by the German Research Foundation (DFG Ste/51- 1 & 2).
  • Image reconstruction / finite element modelling
    Due to the complex structure of bone it is very difficult to get geometry data for the generation of simulation models. In addition it is impossible to get patient-specific geometry data for patient-specific treatment. With this program it is possible to extract geometry data from CT datasets and generate finite element models. Furthermore it is possible to map bone density information on the created finite element model for the purpose of calculating statically equivalent load sets.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Andre Lutz
  • Studies on the biomechanical compatibility of hip-joint endoprostheses
    The biomechanical compatibility of different devices for artificial hip joint replacement is studied by use of computer simulation. Special emphasis is laid onto the bone remodelling caused from different prosthesis designs. Already these qualitative comparisons enables for rating the systems regarding their long term success.
    Team: Prof.Dr.-Ing. Udo Nackenhorst, M.Sc. Andre Lutz, ext. B. Ebbecke
  • Studies on bone remodelling theory based on microcracks
    Inside the cortical section of every bone, a remodelling cycle, including the resorption and build up of bone matrix, takes place. This phenomenon lasts for the life time. Research groups nowadays agree on the theory, that bone cells called osteocytes, lying inside the bone matrix, have the function as a sensor and are responsible for the remodelling behaviour – but still there is disagreement regarding to what is stimulating the cells.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dipl.-Ing.(FH) Dieter Kardas
    Sponsors: This work is supported by the Research training group 615 of the DFG (German Research Foundation)
  • Numerical Treatment of Inelastic Constitutive Behaviour within an ALE-Framework of Rolling
    The aim of this research project is the development of efficient computation methods for the treatment of inelastic material behaviour of rolling elastomer solids.
    Team: ext. M. Ziefle
    Sponsors: This work is financed by the German Research Foundation (DFG).
  • Constitutive modeling of rubber behavior in a broad frequency domain
    Mechanical response of technical rubber is usually described by damage and hysteresis behaviour under quasi-static cyclic loading conditions, while dynamic stiffening and viscous effects are predominant for high frequency analysis. For the computation of rolling tire behaviour with questions regarding safety, comfort and sound radiation a constitutive description incorporating all of these effects is needed.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Anuwat Suwannachit
    Sponsors: This work is supported by German Ministry for Economics within the “Leiser Straßenverkehr 2” program
  • Theoretical and algorithmic concepts for description of demand-adaptive bone growth
    Computational techniques for the simulation of stress-adaptive bone-remodelling have been developed and applied for the analysis of the biomechanical compatibility of hip-joint endo-prothesis. Numerical simulations are in good agreement with clinical observations and enable parameter studies for the development of optimized prosthesis designs.
    Team: Prof.Dr.-Ing. Udo Nackenhorst, M.Sc. Andre Lutz, ext. B.Ebbecke
    Sponsors: This work is in cooperation with the MHH (Medizinische Hochschule Hannover)
  • FE-Analysis of Osteons concerning the Mechanosensation of Bone Material
    The aim of this project is to localize the detection mechanism of external loads in bone tissue and simulate the formation of new osteons.
    Team: ext. C.Lenz
    Sponsors: This work is supported by the Graduiertenkolleg 615 of the DFG (German Research Foundation)
  • Bone Cell Simulations using Tensegrity Structures
    Bone quality detoriates with time, therefore it has to renew itself throughout the life. This process is called bone remodeling. It is well accepted, that osteocytes are the sensor cells for this process.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dipl.-Ing. (FH) Dieter Kardas, ext. IIya Arsenyev, Oleg Khromov
  • Finite Element Analysis of Hip Joint Contact
    Diseases and injuries of the human muscosceletal system are of particular importance in the health care systems worldwide. The overall costs in Germany including loss of production are estimated up to 100 billion Euros every year.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Kristin Fietz, M.Sc. Andre Lutz
  • Finite Element Simulation of Osseointegration of Uncemented Endoprostheses
    The term osseointegration means the ingrowth of bone into a porous coated implant. In order to simulate the osseointegration of bone implants, a bio-active interface theory is necessary.
    Team: Prof. Dr.-Ing. U. Nackenhorst, M.Sc. André Lutz
  • Finite Element Analysis of the Fracture Healing Process
    Team: Prof. Dr.-Ing. U. Nackenhorst, M.Sc. Alexander Sapotnick
    Sponsors: This project is funded by the DFG (German Research Foundation) NA-330/8-1
  • Multiscale Modeling, with Applications in Contact Mechanics
    We seek for multi-scale methods with physically consistent coupling of the molecular dynamics (MD) method and the finite element methods (FEM), and apply it to contact problems. The material near the contact region will be modelled in MD models so that complicated behaviours such as dislocations, initiation of plastic deformations and crack propagation can be captured.
    Team: Prof.Dr.-Ing. U. Nackenhorst, Dr.-Ing W. Shan
    Sponsors: Deutsche Forschungsgemeinschaft (DFG), Graduiertenkolleg 614 (GRK615)
  • Stochastic Finite Elements
    In vielen ingenieurtechnischen Anwendungen sind nicht deterministische Prozesse und/oder Parameter enthalten. die das Systemverhalten in erheblichen Maßen beeinflussen.
    Team: Prof.Dr.-Ing. U. Nackenhorst, M.Sc. P.Jablonski
  • Investigations on the Numerical Solution of the Fokker-Planck Equation with Discontinuous Galerkin Methods
    As the probability density distribution is an appropriate measure for comprehensive description of stochastic processes, the derivation and solution of transport equations for the probability density requires particular attention. Examination of nonlinear dynamic systems under uncertain excitation or with uncertain parameters leads to stochastic equations of motion.
    Team: Prof.Dr.-Ing. U.Nackenhorst, Dipl.-Ing. F. Loerke
  • Development of a numerically robust material model for rock salt
    Around 300000 tons of high-level radioactive waste exists on earth and around 12000 tons of high-level radioactive waste will be added every year. Possible solutions for storage of radioactive waste are salt domes as reservoirs for toxic and nuclear waste.
    Leaders: Udo Nackenhorst
    Team: Mathias Grehn
    Year: 2011
  • Modeling and numerical simulation for the prediction of the fatigue strength of air springs
    Fatigue failure of cord-reinforced rubber composite has been the subject of extensive studies in automotive industries due to its importance in engineering applications. The classical examples of such composites are found in tires, hoses, and airsprings.
    Leaders: Udo Nackenhorst
    Team: Niraj Kumar Jha
    Year: 2014
    Sponsors: Continental Teves AG
  • Numerische Simulation probabilistischer Schädigungsmodelle mit der Stochastischen Finite Elemente Methode
    Numerische Umsetzung diverser probabilistischer Methoden, u.a. Monte Carlo Simulation, Kollokationsmethode oder Polynomial Chaos, für die Berschreibung unsicherer Materialparameter innerhalb verschiedener Schädigungsmodelle in Verbindung mit der Finite Elemente Methode
    Leaders: Udo Nackenhorst
    Team: Philipp-Paul Jablonski
    Year: 2014
  • A micro-mechanically motivated approach for modelling the oxidative aging process of elastomers
    Leaders: Udo Nackenhorst in collaboration with Markus Andre
    Team: Darcy Beurle
    Year: 2016
    Lifespan: 2016-2019
  • Concepts for Chemical Degradation of Materials and Structures
    The degradation of materials is of great importance especially when they are expected for a long service time or when it is not easily accessible for maintenance, for example like natural gas pipelines.
    Leaders: Udo Nackenhorst
    Team: Milena Möhle
    Year: 2016
  • Model Reduction Techniques for Probabilistic Fatigue Assessment
    This project aims to develop reliable model reduction techniques for the treatment of damage fatigue modeling in the framework of multiple time scales and probabilistic evaluation of service life of materials and structures.
    Leaders: Udo Nackenhorst in collaboration with David Neron (LMT, ENS Cachan) and Pierre Ladeveze (LMT ENS Cachan) in the framework of IRTG 1627
    Team: Shadi Alameddin, Amelie Fau, Mainak Bhattacharyya
    Year: 2016
    Sponsors: International Research Training Group 1627, DFG (German Research Foundation)
    Lifespan: 2016-2019
  • Innovative concepts for physically based modeling approaches of high-cycle fatigue
    The objective of this project is to go beyond S-N curves classically used to represent damage evolution for damage fatigue. Original sophisticated integration schemes are investigated to be able to predict damage evolution for a high number of cycles while considering physically based models.
    Leaders: Udo Nackenhorst in collaboration with David Neron (LMT, ENS Cachan) and Pierre Ladeveze (LMT ENS Cachan) in the framework of IRTG 1627
    Team: Mainak Bhattacharyya, Amelie Fau
    Year: 2016
    Sponsors: International Research Training Group 1627, DFG (German Research Foundation)
    Lifespan: 2014-2017
  • Computational simulation of piezo-electrically stimulated bone adaption surrounding activated tooth implants
    This study aims for the development of active implants which provide additional electrical stimulation for bone adaption. A computational framework is presented in order to optimize new developments for activating dental implants with piezoelectric coatings.
    Leaders: Udo Nackenhorst
    Team: Seyed Alireza Shirazi Beheshtiha
    Year: 2016
    Sponsors: State of Lower Saxony
  • Computational techniques for the stochastic excitation of rolling tires from rough road surface contact
    In this project, we intend to address issues in modeling rolling tires on rough road surfaces by (a) extending previously developed methods by a stochastic excitation function describing the interaction of the macroscopic tire model and the detailed meso-mechanical contact behavior of the tire tread with the road surface; (b) including dynamic stiffening effects in the rubber compound.
    Leaders: Udo Nackenhorst
    Team: Robert Lee Gates
    Year: 2016
    Sponsors: DFG (German Research Foundation)
  • Sophisticated optimization techniques for structural health monitoring
    Structural monitoring and damage detection has become a growing area in research and development, as witnessed by the increasing number of relevant journal and conference papers. To this end, a crucial challenge is the development of robust and efficient structural identification methods that can be applied to identify key parameters and hence, cause change of structural state.
    Leaders: Udo Nackenhorst
    Team: Mahmoud M. Jahjouh
    Year: 2016
    Sponsors: DAAD – Deutscher Akademischer Austauschdienst
  • Thermo-mechanical analysis of tires in stationary rolling contact
    The optimization of tire designs towards less rolling resistance and higher durability is still a challenging task. In the recently finished project (Link to Anuwat Suwannachit 2012) a thermo-mechanical framework for the calculation of the energy dissipation in the bulk material of stationary rolling tires was developed.
    Leaders: Udo Nackenhorst
    Team: Robert Beyer
    Year: 2016
    Sponsors: German Research foundation (DFG)
  • Dynamic properties of heterogeneous materials with uncertain microstructures and local damage
    The goal of this research project is the development of novel predictive techniques for damage monitoring in heterogenous materials. Multi-scale modeling techniques are combined with related statistical methods for scale bridging.
    Leaders: Udo Nackenhorst
    Team: Andre Hürkamp
    Year: 2016

Structural Dynamics

  • A finite element tire modelling approach for car interior noise simulation
    A finite element approach for the simulation of the dynamic behaviour of tires rolling on rough roads for the car indoor noise prediction is presented. Based on a detailed finite element model valid for the nonlinear stationary rolling analysis a modal tire model to be coupled with a total vehicle dynamics simulation approach has been developed, where special care is taken on the physical consistency.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dipl.-Ing Raffeala Chiarello
  • Transient dynamic impact of inelastic solids with rough surfaces
    Since more than two decades a relative kinematic framework (ALE-description) has been widely used for rolling contact analysis of tire-road systems. The well known advantages of the ALE-formulation are the possibility of local mesh refinement in contact region and time-independent formulation of stationary elastic rolling.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Anuwat Suwannachit
    Sponsors: This work is supported by German Research Foundation (DFG)
  • ALE-interface coupling for multiscale analysis of treaded tires in rolling contact
    The Arbitrary Lagrangian Eulerian (ALE) formulation is well established for the finite element simulation of stationary as well as transient dynamics rolling contact phenomena. The method enables mesh refinements in the contact zone and a time independent formulation of stationary rolling. The inconvenience for the simulation of rolling tires is the incorrect treatment of the tread blocks due to the non axisymmetric geometry.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dip.-Ing. Raffaela Chiarello, Dipl. Ing. (FH) Ole Stegen
  • Computational Methods for Frictional Rolling Contact
    The aim of this research project is the development of efficient computation methods for the analysis of frictional rolling contact problems of elastomer solids on rigid surfaces.
    Team: ext. M. Ziefle
    Sponsors: This work is financed by the German Research Foundation (DFG), research group FOR492.
  • A multi-scale approach on the transient dynamics of rolling tires
    The transient dynamic response of rolling tires, which is a major source of traffic noise nowadays, is excited from the tread impact and the road surface texture. A multi-scale approach is introduced in order to investigate the behaviour of tread rubber in contact with rough road surface at a sufficient small length-scale, which leads to the vibration of the overall structure.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Anuwat suwannachit
    Sponsors: This work is supported by German Ministry for Economics within the “Leiser Straßenverkehr 2” program
  • Constitutive modeling of rubber behavior in a broad frequency domain
    Mechanical response of technical rubber is usually described by damage and hysteresis behaviour under quasi-static cyclic loading conditions, while dynamic stiffening and viscous effects are predominant for high frequency analysis. For the computation of rolling tire behaviour with questions regarding safety, comfort and sound radiation a constitutive description incorporating all of these effects is needed.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, M.Sc. Anuwat Suwannachit
    Sponsors: This work is supported by German Ministry for Economics within the “Leiser Straßenverkehr 2” program
  • Reduced-order models for structural dynamic Finite Element systems
    Computational models from different engineering fields tend to get more and more detailed and complex thanks to the development of more and more powerful computers. Nowadays, solving these large systems of equations is not impossible, but requires a lot of time and computational resources.
    Leaders: Udo Nackenhorst
    Team: Stefanie Tegtmeyer
    Year: 2013
    Sponsors: State of Lower Saxony
  • Numerical simulation of tire rolling noise radiation
    The structural dynamics of rolling tires is treated by a modal superposition approach whereas the underlying stationary rolling process is modeled within a nonlinear relative kinematics continuum theory.
    Year: 2013
    Sponsors: Supported by BMBF
  • Computational techniques for the stochastic excitation of rolling tires from rough road surface contact
    In this project, we intend to address issues in modeling rolling tires on rough road surfaces by (a) extending previously developed methods by a stochastic excitation function describing the interaction of the macroscopic tire model and the detailed meso-mechanical contact behavior of the tire tread with the road surface; (b) including dynamic stiffening effects in the rubber compound.
    Leaders: Udo Nackenhorst
    Team: Robert Lee Gates
    Year: 2016
    Sponsors: DFG (German Research Foundation)
  • Sophisticated optimization techniques for structural health monitoring
    Structural monitoring and damage detection has become a growing area in research and development, as witnessed by the increasing number of relevant journal and conference papers. To this end, a crucial challenge is the development of robust and efficient structural identification methods that can be applied to identify key parameters and hence, cause change of structural state.
    Leaders: Udo Nackenhorst
    Team: Mahmoud M. Jahjouh
    Year: 2016
    Sponsors: DAAD – Deutscher Akademischer Austauschdienst

Model Order Reduction

  • A finite element tire modelling approach for car interior noise simulation
    A finite element approach for the simulation of the dynamic behaviour of tires rolling on rough roads for the car indoor noise prediction is presented. Based on a detailed finite element model valid for the nonlinear stationary rolling analysis a modal tire model to be coupled with a total vehicle dynamics simulation approach has been developed, where special care is taken on the physical consistency.
    Team: Prof. Dr.-Ing. Udo Nackenhorst, Dipl.-Ing Raffeala Chiarello
  • Reduced-order models for structural dynamic Finite Element systems
    Computational models from different engineering fields tend to get more and more detailed and complex thanks to the development of more and more powerful computers. Nowadays, solving these large systems of equations is not impossible, but requires a lot of time and computational resources.
    Leaders: Udo Nackenhorst
    Team: Stefanie Tegtmeyer
    Year: 2013
    Sponsors: State of Lower Saxony
  • Model Reduction Techniques for Probabilistic Fatigue Assessment
    This project aims to develop reliable model reduction techniques for the treatment of damage fatigue modeling in the framework of multiple time scales and probabilistic evaluation of service life of materials and structures.
    Leaders: Udo Nackenhorst in collaboration with David Neron (LMT, ENS Cachan) and Pierre Ladeveze (LMT ENS Cachan) in the framework of IRTG 1627
    Team: Shadi Alameddin, Amelie Fau, Mainak Bhattacharyya
    Year: 2016
    Sponsors: International Research Training Group 1627, DFG (German Research Foundation)
    Lifespan: 2016-2019
  • Innovative concepts for physically based modeling approaches of high-cycle fatigue
    The objective of this project is to go beyond S-N curves classically used to represent damage evolution for damage fatigue. Original sophisticated integration schemes are investigated to be able to predict damage evolution for a high number of cycles while considering physically based models.
    Leaders: Udo Nackenhorst in collaboration with David Neron (LMT, ENS Cachan) and Pierre Ladeveze (LMT ENS Cachan) in the framework of IRTG 1627
    Team: Mainak Bhattacharyya, Amelie Fau
    Year: 2016
    Sponsors: International Research Training Group 1627, DFG (German Research Foundation)
    Lifespan: 2014-2017
  • Sophisticated optimization techniques for structural health monitoring
    Structural monitoring and damage detection has become a growing area in research and development, as witnessed by the increasing number of relevant journal and conference papers. To this end, a crucial challenge is the development of robust and efficient structural identification methods that can be applied to identify key parameters and hence, cause change of structural state.
    Leaders: Udo Nackenhorst
    Team: Mahmoud M. Jahjouh
    Year: 2016
    Sponsors: DAAD – Deutscher Akademischer Austauschdienst
  • Thermo-mechanical analysis of tires in stationary rolling contact
    The optimization of tire designs towards less rolling resistance and higher durability is still a challenging task. In the recently finished project (Link to Anuwat Suwannachit 2012) a thermo-mechanical framework for the calculation of the energy dissipation in the bulk material of stationary rolling tires was developed.
    Leaders: Udo Nackenhorst
    Team: Robert Beyer
    Year: 2016
    Sponsors: German Research foundation (DFG)
  • Dynamic properties of heterogeneous materials with uncertain microstructures and local damage
    The goal of this research project is the development of novel predictive techniques for damage monitoring in heterogenous materials. Multi-scale modeling techniques are combined with related statistical methods for scale bridging.
    Leaders: Udo Nackenhorst
    Team: Andre Hürkamp
    Year: 2016