Chapter 6 - Future evolution: Multiscale modeling framework to develop a physically based nonlocal plasticity model for crystalline materials

Abstract

In the previous chapters, the study of size effects have been elaborated at different length scales from the nonlocal continuum models to the atomistic simulation. Each of these methods can handle certain ranges of time scale and length scale. Accordingly, each method can capture specific characteristics of the problem. The idea of multiscale modeling is to bridge the gap between different length scales to benefit the advantages of various length scales without paying the price of substantial simulations. In this chapter, a novel idea of multiscale framework is presented to develop a physically based nonlocal plasticity model to capture size and rate effects in micron-sized crystalline samples assisted by experiments and atomistic simulation. The results of the current framework can shed light on the role of dislocations at the smaller length scales for crystalline metals. This chapter presents a new framework to develop a new physically based nonlocal continuum plasticity model for crystalline metals, which is able to capture different mechanisms of strain rate and size effects using both experiments and molecular dynamics (MD) simulation. The model incorporates various features of length scale, strain rate, grain size, and dislocation density. The results obtained from the conducted indentation and microbending tests and large scale MD simulations of nanoindentation and micropillar compression tests can be incorporated to develop the model. Furthermore, the presented framework can stretch the current experimental knowledge of plasticity in metallic samples of confined volumes by conducting indentation and microbending tests and monitoring the evolution of dislocations. Finally, valuable information on the strain rate and size effects can be provided from a systematic parametric study using large scale MD for samples with various sizes, materials, grain sizes, crystal structures, and crystallographic orientations subjected to different strain rates.