The importance and influence of multiscale modeling from atoms to components.

Multiscale materials modeling simulations are a rapidly growing scientific field. With increasing computer power and more and more specialized numerical methods, an extensive simulation based description of the mechanics of materials can be achieved. For this purpose more than two simulation methods have to be connected for the integral description of materials behavior from the nanoscale to the microscale and finally to the macroscale.

The complete description of material behavior not only in inorganic material classes but also in biological and bioinspired materials can be found with these methods, which was not possible until now. The figure shows the whole process, described from two different points of view; the view from materials science – and the top down approach, the materials engineering view. Every year new discoveries are made with multiscale materials modeling techniques and are presented in different topics in the materials community.

Topics can be, for example, ‘Multi-time-scale and multi-length-scale simulations of precipitation and strengthening effects’ where simulations from the nano to the macroscale where conducted but also different time scales are involved. Examples for this type of multiscale simulations are the papers from Kizler et al. (‘Linking nanoscale and macroscale: Calculation of the change in crack growth resistance of steels with different states of Cu precipitation’, Kizler, Uhlmann, Schmauder) where the strengthening of steels due to Cu precipitates is in focus and a combination of dislocation theory and damage theory is used as well as the paper from Molnar et al. (‘Multiscale simulations on the coarsening of Cu-rich precipitates in α-Fe using kinetic Monte Carlo, molecular dynamics and phase-field simulations’, Molnar, Mukherjee, Choudhury, Mora, Binkele, Selzer, Nestler and Schmauder) where Monte Carlo, Molecular Dynamics, Phase Field as well as Finite Element Simulations are combined by parameter transfer between the methods for solving the macroscopic precipitation hardening problem with information from lower length scales.

Another topic comprises ‘Multiscale simulations of plastic deformation and fracture’ where it is all about plasticity and fracture and the principles behind. In the different simulations and examples the challenges of multiscale simulations with an emphasis on deformation as well as crack nucleation and propagation in different materials such as alumina and iron are conducted. An example is the work of Siddiq et al. (‘Niobium/alumina bicrystal interface fracture: A theoretical interlink between local adhesion capacity and macroscopic fracture energies’, Siddiq, Schmauder, Rühle) where the authors establish a theoretical interlink between local adhesion capacity and macroscopic fracture energies by a multiscale materials model which bridges the nano-, meso-, and macro-scales. For this, crystal plasticity theory has been used, combined with a cohesive modeling approach.

But also in other scientific fields, applied multiscale simulations start to be the basis of new findings: In topics like ‘Multiscale simulations of biological and bio-inspired materials, bio-sensors and composites’ the focus changes here from inorganic materials to bio-inspired or bio-connected materials. This shows the importance of a rather new and growing scientific topic, biomimetics, which also needs to develop scale passing strategies and methods to fully understand the strong or weak interactions of (partly) biological materials and which also cover additional, for example, functional material behavior on all length scales. These examples demonstrate a variety of different results. Starting with the article of Chen et al. (‘Multiscale modelling of nano-biosensors’, Chen, Shih, Chou, Chang, Mortar) with an emphasis on coupling a continuum description with first principles density functional theory calculations or classical molecular dynamics/statics simulations through linking atomistic contributions with kinematic constraints imposed by continuum mechanics. It continues with nanocomposites in the work of Weidt and Figiel (‘Finite strain compressive behaviour of CNT/epoxy nanocomposites: 2D versus 3D RVE-based modelling’, Weidt, Figiel) where the macroscopic finite strain compressive behavior of CNT/epoxy nanocomposites at quasi-static and high strain-rates was predicted and compared using 2D and 3D RVE approaches. The simulation of a bio-inspired material by Schäfer et al. (‘Peptide–zinc oxide interaction: Finite element simulation using cohesive zone models based on molecular dynamics simulation’, Schäfer, Lasko, Pleiss, Weber, Schmauder) combined molecular dynamics and finite element method simulations to investigate the mechanical properties of a ZnO–peptide material with interface in a multiscale simulation approach. Here the influence of the peptide conformation on the material behavior in the macroscale could be shown and can help to develop new material classes for all kind of different applications.

This short review shows the importance and influence of multiscale materials modeling from atoms to components and we hope that the spark of multiscale materials modeling ignites in the reader.

Additional information can be found in Refs. [1][2][3][4][5] and [6] as part of the forthcoming book: S. Schmauder, I. Schäfer Multiscale Materials Modelling Approaches to Full Multiscaling, Walter de Gruyter (Berlin).

Further reading:

[1] P. Kizler, D. Uhlmann, S. Schmauder
Nucl. Eng. Des., 196 (2) (2000), pp. 175–183

[2] D. Molnar, et al.
Acta Mater., 60 (20) (2012), pp. 6961–6971

[3] A. Siddiq, S. Schmauder, M. Ruehle
Eng. Fract. Mech., 75 (8) (2008), pp. 2320–2332

[4] D. Weidt, L. Figiel
Comput. Mater. Sci., 82 (2014), pp. 298–309

[5] I. Schäfer, et al.
Comput. Mater. Sci., 95 (2014), pp. 320–327

[6] D. Molnar, et al.
GAMM-Mitteilungen, 38 (2) (2015), pp. 228–247

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DOI: 10.1016/j.mattod.2016.01.013