An anisotropic negative thermal expansion metamaterial with sign-toggling and sign-programmable Poisson’s ratio

Abstract Objectives A mechanical metamaterial is introduced herein by drawing inspiration from an Aztec geometric pattern. This deformation mechanism for Poisson’s ratio and Young’s modulus based on non-rotating rhombi with rotating triangles, while the shear analysis hence ‘partially rigid units’. Methods The coefficient of thermal expansion was obtained equating potential energy expressions simple harmonic motion principle equipartition, effective-moduli were acquired strain rotational stiffness that assumed homogenized continuum. Due to zero extreme infinitesimal deformation, finite approach employed. Results indicate proposed exhibits anisotropic negative sign-switching when applied stress along one axis reversed. loading in another undefined under tension but can be programmed exhibit either sign compressed. moduli are directly governed strongly influenced extent rotation, followed aspect units. Conclusion its uniqueness, currently considered used specific requirements which difficult attained other materials properties.