Negative Poisson's Ratio (Auxetic Behavior)

A negative Poisson's ratio describes a material that expands laterally when stretched, rather than contracting as ordinary materials do. Such materials are called auxetic. The source digest lists many chiral metamaterial patents whose stated purpose is to achieve negative Poisson's ratio, making it one of the most recurring themes in the patent half of the source.

Recurring patent themes

The titles in the digest associate negative Poisson's ratio with several design goals:

• Tunable or graded stiffness. CN121897689 describes a "different-chirality spliced variable-stiffness negative Poisson ratio metamaterial structure"; CN118815892 describes a variable stiffness unit and variable stiffness metamaterial.
• Composite chiral designs. CN121111926 describes a chiral composite negative Poisson's ratio metamaterial; CN120212178 describes an energy-absorbing 3D metamaterial with interactively combined positive and negative Poisson's ratio structures.
• Predetermined properties. CN112307663 describes a design method for a chiral metamaterial structure with predetermined negative Poisson's ratio characteristic.
• Structural components. CN120828905 describes a negative Poisson's ratio metamaterial wedge-shaped bottom; CN223411334 describes a negative Poisson's ratio mechanical metamaterial anti-collision energy-absorbing device; CN119911034 describes a damping wheel of auxetic metamaterial sandwich thickness gradient structure.
• Acoustic application. CN119479600 describes a pressure-contact type chiral-negative Poisson's ratio regulation and control acoustic metamaterial.

Caveat

The source gives titles only, with no abstracts, measured values or performance data. It cannot support claims about the magnitude of the effect achieved or the manufacturability of any listed design.