Three-dimensional rotating rigid-body structure fabricated with engineered cementitious composites for enhanced auxetic behavior and energy absorption

In this study, a three-dimensional rotating rigid-body structure (3D-RR) was designed and successfully fabricated using engineered cementitious composites (ECC) via indirect 3D printing. Experimental tests and numerical simulations were conducted to systematically evaluate the compressive mechanical performance, including the deformation modes, stress–strain behavior, evolution of Poisson's ratio, and energy-absorption capacity. The auxetic behavior of the 3D-RR structure resulted from the rotation of its internal cubes. Under compression along the X, Y, and Z directions, it reached maximum strains of 33.5 %, 28.7 %, and 22.4 %, respectively, which were significantly higher than those of the 2D-RR structure (19.3 %), indicating superior deformability. The specific energy absorption ($SEA$) of 3D-RR also exceeded that of 2D-R\R by 319.7 %, 27.7 %, and 142.6 % in the X, Y, and Z directions, respectively. Under impact loading, the 3D-RR exhibited excellent energy dissipation, with the $SE{A}_v$ in the X direction reaching 185.20 $J/{mm}^3$, while the Y and Z directions achieved 97.32 $J/{mm}^3$ and 98.02 $J/{mm}^3$, respectively. These results highlight the 3D-RR's outstanding performance under both static and dynamic conditions. In summary, the 3D-RR structure's outstanding deformability and energy-absorption performance offer a scalable blueprint for high-performance, multifunctional cement-based infrastructure components, including multidirectional seismic isolators, vibration-damping high-speed-rail tracks, and impact-protection modules, and even paves the way for smart energy-harvesting devices via anisotropic auxetic strain coupling.