Effect of gradient design on the compressive and energy absorption properties of 4D-printed deformable honeycomb structure

Abstract 4D-printed deformable honeycombs exhibit stimulus-responsive shape transformations with tunable mechanical properties, which can be applied in the multifunctional scenarios of adaptive compressive and energy absorption properties. For further enhancing their mechanical performances, the gradient design approach is implemented for improving the compressive and energy absorption properties of deformable honeycomb structure. The studied honeycombs can undergo automatic deformation between hexagonal honeycomb (Structure I) and triangular honeycomb (Structure II) under external temperature stimulus. Through comparative analysis of quasi-static compression tests and finite element simulations, the energy absorption capacity of Structure I and the compressive performance of Structure II are evaluated, obtaining the optimal internal angles for each unit cell under varying wall thicknesses. The results demonstrate that the gradient configuration 8-6-8-10-8 (LBH3 in Structure I and XJH3 in Structure II) can exhibit superior mechanical performance compared to conventional uniform-thickness honeycombs. The SEA value of LBH3 is 2.65 J/g, which is 8.16% higher than that of ID7 (uniform-thickness). Additionally, the stiffness ratio of the transformed deformable honeycomb structure XJH3 is 6.18 MPa/g, showing a 47.14% increase in compressive resistance compared to ID17 (uniform-thickness). The gradient design results have broad application prospects for the multifunctional applications of honeycomb structures in the future.