Wissenschaftlicher Mitarbeiter
M.Sc. Mohammad Sarhil
RPTU Kaiserslautern-Landau
Postfach 3049
D-67653 Kaiserslautern
Forschungsthema
A variational scale-dependent transition scheme: From Cauchy elasticity to the relaxed micromorphic continuum
The overall goal of the project is to develop a physically motivated multiscale simulation environment without separation of length scales. In doing so, a relaxed micromorphic model (RMM) is defined on the macroscale and a Cauchy continuum on the microscale. This multiscale model will be developed especially for the simulation of metamaterials, starting from discrete microstructures. Based on the scientific findings of the first funding period, we aim to close the gap of the scale transition between both continua in the second funding period. For this purpose, a consistent homogenization procedure shall be developed. The finite element implementation is extended to a larger space than H(Curl) to achieve better flexibility in modeling. A central goal is to identify the effective moduli in the RMM. In a consistent two-scale approach, a suitable description of the effective (macroscopic) variables based on tensorial quantities of the microscale is necessary. Moreover, for the localization step, the identification of meaningful boundary conditions at the micro-scale is essential for the transfer of information between scales. The energetic equivalence between scales (Hill-Mandel condition) plays an important role in identifying these procedures. For all working points, we will address the following open questions in the field of higher order homogenization:
1. Is there a contribution to the strain energy from the fluctuations associated with higher order modes? In other words, do these fluctuations have to be periodic or not? If yes, then the second gradients of the deformation field cannot be controlled.
2. Does a unique RVE exist in the case of higher order theories? The analysis is often performed on a cluster of unit cells to remove boundary effects and account for convergent behavior in the central nit cell? This approach is questionable from an engineering perspective.
3. Does the higher order homogenization scheme provide convergent behavior for extreme cases, e.g., in a material with extremely hard and soft inclusions? This is not considered by asymptotic expansion homogenization as well as other theories.
4. Do the gradient effects disappear for homogeneous RVEs (which is a necessity)?
5. Does the classical first-order homogenization scheme arise when the separation of the scales is given?
Funded by DFG - Project number 440935806 - DFG SPP 2256
Veröffentlichungen
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- Experimental and Numerical Investigations of the Development of Residual Stresses in Thermo-Mechanically Processed Cr-Alloyed Steel 1.3505.
Metals, Vol. 9, Nr. 4, S. 480 - 28. (2019) - Description and analyses of pull-out behaviour of hooked steel fibres embedded in high performance concrete using phase-field modeling.
Concrete Innovations in Materials, Design and Structures, 16th fib Symposium Proceedings, (2019) - Deterioration development of steel fibre reinforced high performance concrete in low-cycle fatigue.
Advances in Engineering Materials, Structures and Systems, (2019) - Numerical calibration of elasto-plastic phase-field modeling of fracture for experimental pullout tests of single steel fibres embedded in high-performance concrete.
Advances in Engineering Materials, Structures and Systems, (2019) - Analysis and evaluation of single fibre pull-out behaviour of hooked steel fibres embedded in high performance concrete for calibration of numerical models.
Structural Concrete, Vol. 20, Nr. 4, S. 1254 - 1264. (2019) - Martensitic transformation in a two-dimensional polycrystalline shape memory alloys using a multi-phase-field elasticity model based on pairwise rank-one convexified energies at small strain.
Proceedings in Applied Mathematics and Mechanics, Vol. 20, Nr. 1, S. 202000200. (2021) - On a tangential-conforming finite element formulation for the relaxed micromorphic model in 2D.
Proceedings in Applied Mathematics and Mechanics, Vol. 21, Nr. 1, S. 202100187. (2021) - Lagrange and $H(\text curl,\mathcal B)$ based finite element formulations for the relaxed micromorphic model.
Computational Mechanics, Vol. 70, S. 1309 - 1333. (2022) - Modeling the size-effect of metamaterial beams under bending via the relaxed micromorphic continuum.
Proceedings in Applied Mathematics and Mechanics, Vol. 22, Nr. 1, S. 202200033. (2023) - On the identification of material parameters in the relaxed micromorphic continuum.
Proceedings in Applied Mathematics and Mechanics, Vol. 23, Nr. 3, S. 202300056. (2023) - Size-effects of metamaterial beams subjected to pure bending. on boundary conditions and parameter identification in the relaxed micromorphic model.
Computational Mechanics, Vol. 72, Nr. 5, S. 1091 - 1113. (2023) - Size-effects of metamaterial beams subjected to pure bending. on boundary conditions and parameter identification in the relaxed micromorphic model.
Computational Mechanics, Vol. 72, S. 1091 - 1113. (2023)
DOI: 10.1007/s00466-023-02332-9 - Modeling the size-effect of metamaterial beams under bending via the relaxed micromorphic continuum.
Proceedings in Applied Mathematics and Mechanics, Vol. 22, Nr. 1, S. 202200033. (2023) - On a tangential-conforming finite element formulation for the relaxed micromorphic model in 2D.
Proceedings in Applied Mathematics and Mechanics, Vol. 21, Nr. 1, S. 202100187. (2021)
DOI: https://doi.org/10.1002/pamm.202100187
https://onlinelibrary.wiley.com/doi/abs/10.1002/pamm.202100187 - Lagrange and H(curl,B) based finite element formulations for the relaxed micromorphic model.
Computational Mechanics, Vol. 70, S. 1309 - 1333. (2022)
DOI: https://doi.org/10.1007/s00466-022-02198-3 - Experimental and Numerical Investigations of the Development of Residual Stresses in Thermo-Mechanically Processed Cr-Alloyed Steel 1.3505.
Metals, Vol. 9, Nr. 4, S. 480 - 28. (2019) - Numerical analysis of residual stresses on microscale and mesoscale in hot bulk forming parts under specific cooling.
Proceedings in Applied Mathematics and Mechanics, Vol. 19, Nr. 1, S. 201900017. (2019)
DOI: 10.1002/pamm.201900017 - A computational approach to identify the material parameters of the relaxed micromorphic model.
Computer Methods in Applied Mechanics and Engineering, Vol. 425, S. 116944. (2024)
Werdegang
| Seit 2023 | Wissenschaftlicher Mitarbeiter am Lehrstuhl für Technische Mechanik (LTM), RPTU Kaiserslautern-Landau |
| Seit 2018 | Wissenschaftlicher Mitarbeiter am Institut für Mechanik, Universtiät Duisburg-Essen |
| 2015-2018 | "Computational Mechanics" Studium mit dem Abschluss M.Sc. an der Universität Duisburg-Essen |
| 2012-2015 | Wissenschaftlicher Mitarbeiter an der Tischren University – Syrien |
| 2007-2012 | "Structural Engineering" Abschluss an der Tischren University – Syrien |