Geometry‐Tunable Auxetic Behavior in a 3D‐Printed Multipoint Gap Cellular Metamaterial: Experimental and Numerical Insights

In this work, a novel rubber‐based auxetic metamaterial incorporating a multipoint gap cellular metamaterial (MPGCM) architecture is introduced and experimentally and numerically investigated. The proposed design, inspired by a four‐leaf clover geometry, exploits engineered multipoint gaps to achieve buckling‐resistant deformation and enhanced energy absorption under compression. The metamaterial exhibits a distinct two‐stage mechanical behavior, characterized by an initial linear force–displacement phase followed by progressive stiffening as deformation increases. A systematic parametric study reveals that the geometric angle between adjacent gap arms ( α = 110°, 120°, and 130°) plays a dominant role in controlling mechanical performance. Reducing α significantly increases structural resistance and energy absorption, with the maximum compressive force rising from 0.46 kN at α = 130° to 0.87 kN at α = 110°, while the absorbed energy increases by nearly 70%. Stress and elastic strain analyses show that deformation localizes at the intersections of multipoint gaps along the transverse direction, confirming that the auxetic behavior is controlled by the tailored cell geometry. The results highlight the novelty of the MPGCM concept as a geometrically tunable auxetic platform, offering adaptive stiffness, high energy absorption, and controlled deformation, making it a promising candidate for applications such as protective sports helmets.