Programmable multifunctional auxetic metamaterials via concave rib architecture

Auxetic metamaterials exhibit counterintuitive deformation (lateral expansion under tension) with significant potential in aerospace and automotive applications. However, conventional designs are limited by fixed negative Poisson’s ratios (NPR), single deformation modes, and restricted load responses. We introduce a concave-rib-modified auxetic metamaterial (CRMAM) that overcomes these limitations. This architecture enables programmable Poisson’s ratio (spanning negative to positive values), multi-step deformation, and sequential load plateaus, enhancing specific energy absorption ( SEA ) by over 135% compared to traditional re-entrant structures. CRMAMs also exhibit velocity-dependent dynamic crushing, classified into three distinct regimes by critical impact velocities. Furthermore, strategic rib arrangement generates ultra-wide phononic bandgaps (500–3600 Hz) with exceptional vibration attenuation. This design framework integrates on-demand mechanical tunability and wave control, extending metamaterial programmability beyond geometrical parameters for multifunctional applications. • A design insight for a two-load plateau auxetic metamaterial featuring concave ribs is proposed. • Negative/positive Poisson's ratio switching and multi-load plateau effects are achieved. • The impact-crushing deformation mode is revealed, with two critical velocities determined. • The phononic bandgaps are calculated, confirming the metamaterial's multifunctionality.