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Natural materials show astonishing mechanical properties, despite their rather poor building blocks. This counterintuitive behavior can be traced back to their hierarchical organization that enhances the properties of the building blocks. A classic example is bone: lightweight, stiff, strong, yet tough. This property combination is attributed particularly to the microstructure, where osteons deflect and arrest cracks. In this work, we mimic the bone microstructure with fiber-reinforced composites: we perform a numerical parametric study, by varying the layup of the osteon-like structures (OLS) and interconnecting layers representing the interstitial bone lamellae, and we manufacture and test single OLS as proof of concept. Results show the key role of OLS and interconnecting layers in deflecting and arresting cracks, whereas the combination of diverse materials affects the elastic properties. Finally, the introduction of hollow OLS, not affecting fracture toughness, might be used to expand the material functionality, paving the way toward novel multifunctional composites.
Stagni et al. (Tue,) studied this question.