Crack tortuousity in the nacreous layer – Topological dependence and biomimetic design guideline

•Influence of overlap length on crack-tip driving force.•Identification of bounds of optimal overlap length under quasi-static loading.•Analogy established against nacre and previously published experimental data.•Biomimetic design guideline for light-weight and tough composite structures.

The nacreous layer in seashells is known for two phenomenal aspects: light-weightiness and superior fracture toughness. Of a multitude of toughening mechanisms, the highly meandering nature of the crack path through its staggered architecture has been reported to contribute approximately a third of its overall toughness. In the current article, we are trying to establish the scientific rationale associated with the influence of overlap length on the crack-tip driving force from a local perspective via development of a simplified analytical model. Characteristic overlap lengths computed showed reasonable agreement with the values reported in the nacreous layer and previously published experimental data. Biomimetic design guideline obtained from the current investigation would thereby lead to development of synthetic staggered architecture materials with improved stiffness, load-transfer and toughness.