Investigation on the Bending Characteristics of Variable Thickness Negative Stiffness Honeycomb Core

This study investigates the bending behavior and energy absorption capacity of negative stiffness honeycomb cores with variable thickness under flexural loading. The objective is to improve structural performance by introducing local beam thickness modification in three models (LM1, LM2, and LM3) and by varying the initial beam height (h = 2.8-9 mm). Both experimental testing and finite element simulations using Abaqus CAE were conducted, with validation confirming good agreement between experimental and simulation results. Among the locally modified models, LM3 demonstrated the best overall performance, achieving the highest peak force and the greatest specific energy absorption (SEA). This corresponds to a 29 % increase in peak force and a 25.6 % improvement in SEA compared to the baseline constant-thickness core. Although LM3 showed sudden post-peak drops, its superior strength and energy dissipation make it well-suited for applications requiring high impact resistance. Furthermore, varying the initial beam height to 8 mm significantly enhanced the performance, delivering up to 95 % higher peak force and 142 % greater SEA. Overall, the results highlight the potential of functionally graded honeycomb cores for crash protection, aerospace, and vibration isolation systems.