ICAMS / Interdisciplinary Centre for Advanced Materials Simulation

Micromechanics of Large Deformations

Napat Vajragupta

The research group “Micromechanics of Large Deformations” aims at using the micromechanical modeling approach to describe large deformation of materials or components at the macroscopic scale. To achieve this goal, we focus on several key research areas including method to generate the representative volume element (RVE), crystal plasticity models, and homogenization or optimization schemes.

Micromechanical modeling strategy to bridge the influence of microstructural features on large deformations

At the center of the micromechanical modeling approach, the method for generating RVE is of crucial importance, as it must be able to quantitatively capture all the important microstructural features such as grain size and shape distributions. Hence, difference platforms to construct RVE have been developed and investigated within our research group. Our aim is to generate sophisticated microstructure models from a small number of input parameters.

As new materials with complex microstructures are constantly being developed and introduced into technology, more complicated deformation mechanisms are to be expected and will require more advanced models to describe them. Thus, we continuously intensify our expertise in crystal plasticity to consider multi-deformation mechanisms such as slip, twinning, phase transformation, and diffusional creep. In addition, the parameterization of the material models is within the scope of our work as well.

The combination of methods for RVE generation and material modeling allows us to develop micromechanical models, with which the fundamental deformation mechanisms and their dependence on microstructural features can be investigated. Furthermore, by using sophisticated homogenization techniques, the results of the micromechanical models serve as basis for material descriptions with advanced continuum plasticity flow rules.

Group Members



  • Construction of representative volume element from quantitative description of microstructure morphology
  • Crystal plasticity model and parameterization of the material models
  • Homogenization and optimization techniques to bridge microscopic scale simulation with advanced continuum plasticity flow rules

Recent publications

W. Amin, J. A. Qayyum, K. Altaf, A. Abdul-Rani et al. Metal injection molding process parameters as a function of filling performance of 3D printed polymer mold MATEC Web of Conferences, MATEC Web of Conferences, Malaysia, 225, 6, (2018)

J. K. Engels, S. Gao, W. Amin, A. Biswas et al. Indentation size effects in spherical nanoindentation analyzed by experiment and non-local crystal plasticity Materialia, 3, 21-30, (2018)

G. Eggeler, P. Wollgramm, K. Neuking, J. Schreuer et al. On shear testing of single crystal Ni-base superalloys Metallurgical and Materials Transactions A, Springer Nature Switzerland AG, Cham (CH), 49, 3951-3962, (2018)

S. Gao, P. Wollgramm, G. Eggeler, A. Ma et al. A phenomenological creep model for nickelbase single crystal superalloys at intermediate temperatures Modelling and Simulation in Materials Science and Engineering, IOP Publishing Ltd, Bristol and Philadelphia, 26, 055001, (2018)

S. Gao, U. Gogilan, A. Ma, A. Hartmaier. Numerically efficient microstructure-based calculation of internal stresses in superalloys Modelling and Simulation in Materials Science and Engineering, IOP Publishing Ltd, Bristol and Philadelphia, 26, 025001, (2017)


Dr.-Ing. Napat Vajragupta
Ruhr-Universität Bochum
44780 Bochum
Tel: +49 234 32 22417
Fax: +49 234 32 14984

Email: napat.vajragupta@rub.de

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