Enhanced in-plane impact characteristics of a novel circular-reinforced sinusoidal honeycomb

Curved-wall auxetic honeycombs show significant potential for alleviating stress concentrations and enhancing energy absorption. In this study, a novel circular-reinforced sinusoidal honeycomb (CRSH) was developed by reinforcing the nodes of a conventional sinusoidal honeycomb (SH) with circular rings. Finite element models were validated through quasi-static compression tests on 3D-printed CRSH and SH specimens. The influence of three dimensionless parameters ( a ¯ , t ¯ , and r ¯ ) on the in-plane performance of CRSH was systematically assessed across a broad range of impact velocities. As velocity increases, CRSH transitions from a five-stage deformation mode to a four-stage mode, and finally to a three-stage mode. Theoretical models were developed to predict two plateau stresses under low-velocity impacts and one plateau stress under high-velocity impacts, showing good agreement with the simulated results. Compared with geometrically equivalent circular-reinforced quadrilateral honeycomb (CRQH) and SH, CRSH exhibits a strong auxetic effect, more stable plateau stresses, and higher specific energy absorption (SEA). Under low-velocity impacts, CRSH shows 70.14 % higher SEA than CRQH and 131.01 % than SH. This advantage persists at medium velocities, with SEA exceeding CRQH by 26.09 % and SH by 110.92 %, and even at high velocities, CRSH maintains a 24.43 % advantage over SH. Parametric analyses reveal that reducing a ¯ while increasing t ¯ and r ¯ can optimize SEA, ensuring CRSH’s competitiveness under high-velocity impacts. Its tunable impact performance and multi-plateau mechanism make CRSH particularly well-suited for adaptive energy absorption applications in aerospace, automotive safety, and defense systems. ● Innovative circular-reinforced sinusoidal honeycomb shows excellent auxetic behavior. ● Circular walls increase SEA by 131.01 % (low) and 110.92 % (medium velocity). ● Theoretical plateau stress models are validated across low/high-velocity regimes. ● Three-stage energy absorption reduces to one-stage as velocity increases. ● Adjusting the geometric parameters can optimize the energy absorption.