A size dependent crossover in common glass: Inverse Griffith behaviour enables architected strength

Natural glass architectures, such as the hierarchical lattice skeleton of Euplectella aspergillum , reveal how geometry and multiscale ordering can transform brittle silica into robust structural systems. Inspired by these biological strategies, we investigated the foundational mechanics needed to engineer analogous structures through glass additive manufacturing. Soda lime fibres spanning tens to hundreds of micrometres were drawn and mechanically characterised. We reveal a critical diameter (∼ 0.13 mm) at which glass fibres undergo a transition from flaw-limited Griffith behaviour to an intrinsic, primary flaw-tolerant regime, accompanied by concurrent changes in modulus and elongation. These regime-specific mechanics establish essential design rules for architected, additively manufactured glass that aspires to the performance of nature’s own glass metamaterials.