Manipulating the geometry of architectured beams for maximum toughness and strength

Highlights

• Interlocking of blocks can be achieved by enriching architectured beams with blocks having curved and wavy contact surfaces.

• The contact surfaces of blocks can be characterized by a waviness parameter ϕL which correlates with toughness and strength.

• Weak blocks allow little interlocking therefore toughness is achieved through deformation.

• Strong blocks allow interlocking therefore both strength and toughness are achieved through hardening.

• Architectured beams fail progressively resulting in 370 times the toughness and 40% the strength of the monolithic beam.

Abstract

Dense architectured materials are made of blocks that can slide, rotate, interlock and jam in powerful mechanisms that can generate simultaneous strength and toughness. Nature abounds of examples of such architectured materials, for example in the segmented structure of vertebrate spines. In this study we consider segmented beams made of stiff blocks and submitted to a transverse force. We start with simple cubes as a geometrical reference, which we then enrich by using two-dimensional polynomial functions. The flexural response of the beam is simulated using finite element modeling (FE-model) to predict strength, toughness and maximum local stresses. Using this procedure we identified the most efficient interface geometries and interlocking mechanisms within a set of polynomial functions and for a given strength of the individual blocks. To illustrate these results, we fabricated segmented beams of ceramic glass using a laser engraver. Experiments on these architectured glass revealed how enriched blocks turned the catastrophic brittle failure of monolithic glass into graceful progressive deformation. Resulting in a tougher response than the monolithic by 370 times and preserved 40% of strength of that of the monolithic.

^⁎Corresponding author.