Effects of Interlocking Profile on Mechanics of Nacre-Like Materials: Modeling, 3D Printing, and Testing

Nacre’s remarkable strength and toughness arise from its brick-and-mortar architecture, where staggered mineral platelets and biopolymeric interfaces enable platelet sliding and interlocking that prevent strain localization. Inspired by this design, nacre-like materials have been widely studied, yet interlocking effects have mostly been explored using bowtie-shaped platelets with straight profiles. Here, we introduce a generalized interlocking model based on interpenetrating circular arcs to examine how interface waviness influences deformation, failure behavior, and mechanical properties. Constructs were fabricated via stereolithography using a custom photopolymer resin to mimic stiff and brittle mineral platelets and infiltrated with a tough polymer representing interfaces. Tensile tests combined with in-situ imaging, digital image correlation, and finite element analysis reveal that interlocking geometry strongly affects the extent of platelet sliding. For nacre-like materials with identical aspect ratios and interlocking angles, profiles with greater curvature – rather than straight edges – promote more uniform stress redistribution at platelet interfaces. This geometric effect increases the spread of deformation by 2× and enhances energy absorption by ~ 20% at the expense of reductions in stiffness (≈5%) and strength (≈10%). These findings suggest that the wavy interfaces in natural nacre may have evolved to promote distributed deformation, platelet sliding, and improved toughness.