Multi-field Mechanics



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The research comprises basic research and application-oriented research in civil and environmental engineering. The focus is on the development of methods and numerical models for the simulation of large structures and applications in geotechnics, geophysics, structural mechanics and energy. Model validation, the implementation of multiscale models, the application of data-based material models, the development of open source software and the use of artificial intelligence are of great importance.


Machine learning within the framework of multi-scale modelling

Recurrent neural networks in crystal plasticity Copyright: IAM

Machine learning is a helpful tool in the context of multi-scale modelling. It allows "deep" recurrent neural networks to be formed to generate an objective, path-dependent, anisotropic ML material model. Furthermore, the generation of data-based ML material models allows the consideration of microstructural information that cannot be captured in conventional material models. Deep Reinforcement Learning can also be used as a tool for the automatic determination of the optimal ND meta-parameters in connection with the fulfilment of a predefined condition. DRL in material modelling is an ongoing collaboration with Columbia University in the USA.

Contact: Dr.-Ing. Yousef Heider


Advanced continuum mechanical description of solids, saturated and unsaturated porous materials

Foundations for offshore wind turbines Copyright: IAM

Continuum mechanical descriptions comprise thermodynamically consistent, non-linear, inelastic material models. Stable solutions of strongly coupled problems with e.g. hybrid strategies from monolithic and staggered time-stepping methods are developed. It is also important to consider material heterogeneity in the continuum mechanical description.
Current applications can be found in the fields of seismology, wind energy and geotechnics.

Contact: Dr.-Ing. Yousef Heider


Hydraulic and drought-induced fracture modelling and validation using the phase field method

fracture modeling and validation Copyright: IAM

In fracture modelling and validation, the focus is not only on saturated but also on unsaturated porous media. Thereby diffusive phase field modelling of fractures is created. Current fields of application are geothermal energy e.g. Hot-Dry-Rock method, biomechanics e.g. herniated disc and agriculture e.g. drying-conditioned cracks in clay.

Contact: Dr.-Ing. Yousef Heider


Thermo-hydromechanical modeling and experimental validation of phase change materials - saturated porous media

Ground freezing in tunnel construction Copyright: IAM

Current applications are in thermal energy storage, geotechnics e.g. ground freezing and frost lifting and mechanics e.g. residual stresses in tungsten inert gas welding.

Contact: M.Sc. Abdel Hassan Sweidan, Dr.-Ing. Yousef Heider


Combined MD - PFM Approach

CaCo3 fracture Copyright: IAM

Although the mechanics of fracture has been a matter of extensive theoretical and experimental studies since the 19th century, studies addressing the multi-scale modeling of fracture are seldom found, particularly from nano to macro scale.

A novel combined method for highly brittle materials such as aragonite crystals is proposed, which provides an efficient and accurate in-sight understanding for multi-scale fracture modelling. In particular, physically-motivated molecular dynamics simulations are performed for crack modeling on the nano scale, whereas a macroscopic modelling of fracture has proven successful using the diffusive phase-field modeling technique. A link between the two modelling schemes is proposed by deriving PFM parameters from the MD atomistic simulations. Thus, in this combined approach, MD simulations provide a more realistic meaning and physical estimation of the PFM parameters. The proposed computational approach, that encompasses mechanics on discrete and continuum levels, can assist multi-scale modelling and easing, for instance, the simulation of biological materials and the design of new materials.

Contact: Dr.-Ing. Sandeep Patil, Dr.-Ing. Yousef Heider


Multiscale modelling of saturated and unsaturated porous materials:

Lattice-Boltzmann-Method Copyright: IAM

An important method within multiscale modelling is the Lattice-Boltzmann-Method. It is used to model fluid flow on the microscale in Palabos software. The numerical simulation of porous media on the basis of continuum mechanics is done by applying the "theory of porous media", whereby the hydraulic material parameters such as permeability are extracted from the LBM simulations.

Contact: M.Sc. Mohamad Chaaban, Dr.-Ing. Yousef Heider


Multiscale modelling and experimental validation of the flow of granular materials

Copyright: IAM

The Discrete Element Method is used for modelling on the micro scale in the open-source software LIGGGHTS. Exemplary applications can be found in the behaviour of free flowing and cohesive powders.

Contact: M.Sc. Bilal El Kassem,Dr.-Ing. Yousef Heider