Study on the three-point bending performance of a new type of negative Poisson’s ratio chiral honeycomb

As a class of advanced functional structural materials with intrinsic negative Poisson’s ratio (NPR) characteristics, auxetic chiral structures have been continuously and thoroughly investigated by researchers worldwide, attributed to their superior mechanical properties characterized by the synergy of stiffness and strength, as well as unique anomalous deformation behaviors induced by the inherent auxetic effect. In the present work, a novel chiral lattice structure with circular nodal rings (designated as NCL) is proposed and introduced to improve the energy absorption capacity of auxetic sandwich beams. Systematic numerical simulations are performed using the commercial finite element software Abaqus, to compare the flexural mechanical response and energy dissipation performance of the proposed NCL structure with those of the four-handed chiral honeycomb structure (designated as QCL). Results indicate that the NCL exhibits a 40% higher specific energy absorption (SEA) than the QCL, demonstrating superior anti-bending performance. The deformation behavior of the NCL sandwich beam is affected by crushing position, node circle radius ratio (R/L), and core thickness (t). Loading above the unit (T-position) engages more cells in deformation, enhancing load capacity. Increasing R/L strengthens the negative Poisson’s ratio (NPR) effect and improves energy absorption, peaking at R/L = 0.75. Greater face sheet thickness also improves bending resistance, with a higher back face sheet thickness ( t f /t b < 1) significantly boosting energy dissipation. By means of the complex proportional assessment (COPRAS) method, the core layer thickness (denoted as t) is identified as the most dominant influencing parameter governing the structural mechanical performance, with the optimal comprehensive performance attained at t = 1.2 mm. Furthermore, a significant enhancement in the energy absorption capacity is achieved by allocating a larger thickness to the ligaments than to the nodal ring, which provides a novel and effective optimization strategy for the performance improvement of auxetic sandwich beam structures.