Auxetilise

Auxetilise is a term used in materials science to denote the act of imparting auxetic properties to a material, i.e., engineering a negative Poisson's ratio so that the material expands laterally when stretched and contracts laterally when compressed. This process focuses on designing the material's microstructure rather than selecting a naturally auxetic substance.

Origin and usage: The word is a modern coinage built from the adjective auxetic, which describes materials with negative Poisson's ratio. It is used to describe fabrication, design, or treatment steps intended to produce an auxetic response in polymers, foams, metals, or composites.

Mechanisms: Auxetilise relies on specific geometries that convert axial deformation into transverse expansion. Common unit-cell patterns include re-entrant (bow-tie) cells, chiral lattices, and rotating-stiff-rod frameworks. These architectures enable hinge-like rotation or bulk shear that yields a negative Poisson's ratio.

Methods: Realizing auxetilise typically involves manufacturing technologies capable of creating the needed microstructure, such as additive manufacturing (3D printing), laser cutting, or precision foaming. Post-processing steps can include heat treatment or mechanical pre-stressing to stabilize the auxetic response.

Applications and challenges: Auxetilised materials show potential in impact absorption, protective gear, packaging, medical devices such as stents or grafts, and flexible electronics. Challenges include maintaining stiffness and strength, anisotropic behavior, manufacturing cost, and durability over time.

See also: auxetic materials, Poisson's ratio, metamaterials.