Nacre's brick–mortar structure suppresses the adverse effect of microstructural randomness

• Published in: Journal of the mechanics and physics of solids Vol. 159; p. 104769
• Main Authors: Yan, Yi, Zhao, Zi-Long, Feng, Xi-Qiao, Gao, Huajian
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 01.02.2022; Elsevier BV
• Subjects: Biological effects; Biological materials; Crack initiation; Mechanical properties; Microstructural randomness; Nacre; Randomness; Size effects; Strain localization; Strength; Tension–shear–chain model; Weakest-link theory; Microstructural randomness; Nacre; Weakest-link theory; Tension–shear–chain model; Strength; Crack initiation
• ISSN: 0022-5096; 1873-4782
• DOI: 10.1016/j.jmps.2021.104769

•On the basis of virtual internal bond concept, a tension–shear–chain network model of nacre is proposed.•We investigate whether and how nacre suppresses the effect of microstructural randomness.•The ensemble strength of nacre is less dependent on the RVE size and obeys the classical type-I scaling law. Biological materials have evolved various degrees of robustness against microscopic defects and structural randomness. Of particular interest here is whether and how nacre's brick–mortar structure suppresses the adverse effect of microstructural randomness. To this end, a tension–shear–chain (TSC) network model, combined with the virtual internal bond concept, is adopted to investigate the effects of microstructural randomness of nacre, where we show that the ensemble strength and failure behaviors of a larger TSC model exhibit substantially lower randomness. Our results indicate that the staggered brick–mortar structure renders nacre insensitive to microstructural randomness, resulting in enhanced resistance to strain localization and crack initiation at weaker interfaces. The influence of microstructural randomness on the size effect of the ensemble mechanical properties of nacre is also revealed. This study provides further insights and guidelines for designing strong and robust nacre-mimic composites. [Display omitted] A tension-shear-chain (TSC) network model is proposed to reveal whether and how nacre suppresses the effects of microstructural randomness. The insensitiveness of the ensemble mechanical properties of nacre to microstructural randomness originates from the shear-stress transfer mechanism of its brick-mortar structure, and weakens the macroscopic size effect.