Numerical Modeling of the Mechanical Behavior of New Architectured Materials Based on Bi-Crystallographic Analogies

Additive manufacturing has allowed the development of architectured materials in the industry. However, despite their advantages, such as their low density and good energy absorption, the use of cellular materials as structural components is still hindered by concerns toward their mechanical stability and resistance [1]. In particular, highly periodic stretch-dominated lattice structures are subjected to the emergence of localization bands, which causes mechanical instabilities and early structural failure. A framework for improving the mechanical resistance of those lattice metamaterials consists in basing the design guidelines on an analogy between the macroscopic lattice structures and the crystalline microstructures [2]. For example, the introduction of defects like interfaces between different lattice orientations has been shown to hinder localization band propagation in an analogous manner to the interaction between grain boundaries and slip bands in polycrystals [2]. The objective of this study is to expand this framework by further exploring the analogy between both materials. The novelty of this approach stems from the implementation of the bi-crystallographic Coincidence Site Lattice (CSL) theory, commonly used in grain boundary engineering, to the design of bi-crystal inspired truss. Here, the CSL based bi-crystal parameters give access to bi-crystal inspired truss with a strong diversity of interface connectivity, through the nodes shared by the two lattice orientations. This allows to evaluate the influence of specific interfacial connectivity on both local and global mechanical behaviors. The reliability of this design methodology is assessed through finite element calculations. In fact, these simulations enable to assess the interface’s influence on strain localization and on the lattice-based architectured material’s stretch or bending-dominated deformation mode.

References

1. M. Benedetti, A. du Plessis, R. O. Ritchie, M. Dallago, N. Razavi, and F. Berto, Architected cellular materials: A review on their mechanical properties towards fatigue-tolerant design and fabrication, Materials Science and Engineering: R: Reports, 144:100606, 2021, https://doi.org/10.1016/j.mser.2021.100606.
2. M.-S. Pham, C. Liu, I. Todd, and J. Lertthanasarn, Damage-tolerant architected materials inspired by crystal microstructure, Nature, 565(7739):305–311, 2019, https://doi.org/10.1038/s41586-018-0850-3.