Plastic strain localization in periodic materials with wavy brick-and-mortar architectures and its effect on the homogenized response

摘要

Biomimetic or bio-inspired microstructures are increasingly being explored as a source of inspiration for material innovation. The goal of this study is to aid future design of biomimetic materials by conducting analysis of material architectures that resemble brick-and-mortar microstructures found in nacre. Specifically, this study explores the thus-far undocumented combined effects of waviness and platelet architecture on composite material ductility under unidirectional loading parallel and perpendicular to the reinforcing platelets. Model material architectures, comprised of discontinuous silicon carbide platelets suspended in aluminum matrix, that mimic nacre's microstructure were constructed for analysis with the finite-volume direct averaging micromechanics (FVDAM) theory. The silicon carbide platelets play the role of nacre's load-bearing calcite phase while the aluminum matrix mimics the combined effects of hierarchical load transferring mechanisms and organic protein matrix. The FVDAM simulations indicate that the introduction of waviness leads to an increase in ductility. Just as significant to material performance is the degree of relative shift between wavy rows of discontinuous hard-phase platelets. The effect of shift on ductility was found to be most significant when introduced to a degree that disrupted unit cell symmetry and when applied to configurations with low amplitude-to-wavelength ratios. The differences in the observed homogenized response are rooted in the local microstructure-controlled stress and resulting plastic strain fields that are identified in this investigation.