In recent years, a revolution has occurred in the field of material engineering. The breakthrough is the possibility to design, predict the properties of, and even manufacture materials – not only with the help of experiments, but also with advanced computational modeling techniques. Until recently, determining mechanical properties of a material, such as its stiffness or strength, was only accessible through mechanical testing. In that context, the selection or manufacturing of new materials with enhanced properties was a time-consuming trial-and-error process, requiring significant experience and intuition about elementary phenomena and the influence of constituents.
Today, due to the conjunction of several advances in physical/mechanical modeling, computational capabilities, numerical/mathematical methods, and the development of new manufacturing processes like 3D printing, it is possible to accurately predict the properties of a large range of man-made materials like polymer/ceramic/metallic composites, concrete, or nanostructured materials – and manufacture them with controlled microstructures. While analytical micromechanical models have successfully helped to predict effective properties of heterogeneous materials for idealized microstructures, computational methods, computer capacities and the development of computational multiscale methods permit one to go beyond these restrictive assumptions and to consider realistic or architectured microstructures, with complex behaviors like elastoplasticity, damage, microcracking, or phase changes. Another new possibility offered by computational multiscale material modeling is to account for several space or time scales, or several models, e.g. atomistic and continuum.
While these developments are quite mature in the research community, their transition into engineering practice has only begun its first faltering steps. One reason is that many difficulties still persist in reaching solutions for industrial problems. Examples include predicting damage from microcracking, prediction of fatigue, and taking into account the complexity of microstructures with all their uncertainties in realistic materials. Another factor is that simulations related to complex material microstructures still involve extensive computational resources in terms of memory and CPU time, and cannot yet be efficiently incorporated in codes.
In this special issue, we invite experts from different disciplines working on open issues for scale-bridging in computational modeling of complex materials. Open problems are, among many others: the modeling and design of materials with emergent behavior (i.e. effective behaviors which are not observed for individual constituents), the reduction of computational costs in multiscale modeling for use in industrial applications, the use of realistic 3D experimental images (e.g. microtomography images), the prediction of damage of complex heterogeneous materials as in 3D printed structures, and the integration of stochastic phenomena.
Edited by: Julien Yvonnet, Paul Steinmann, Marc Geers, and Andrew McBride