Numerical and Experimental Study on Dynamic Response of Sandwich Beams With Particulate Hemp‐Reinforced <scp>PLA</scp> Bio‐Inspired Cellular Cores

ABSTRACT This study investigates the elastic behavior and dynamic mechanical response of bio‐inspired composite sandwich cores fabricated from polylactic acid (PLA) reinforced with varying concentrations of particulate hemp powder. Motivated by the need for sustainable lightweight structures with tailored mechanical properties, two distinct cellular architectures were developed: honeycomb inspired core (HIC) and lotus root inspired core (LIC). Three material compositions were examined—pure PLA, PLA with 2.5 wt% hemp powder, and PLA with 5 wt% hemp powder—to evaluate the influence of particulate natural filler content on structural performance. All specimens were manufactured using fused deposition modeling (FDM) additive manufacturing technology, enabling precise replication of complex bio‐inspired geometries. Mechanical characterization was performed using both experimental testing and finite element analysis. the alternate dynamic method (ADM) employing an OROS OR34 dynamic signal analyzer was utilized to determine transverse shear modulus, natural frequencies, and damping characteristics. Results demonstrated that the HIC configuration without hemp powder exhibited superior stiffness, achieving a shear modulus of 126.2 MPa and a natural frequency of 1120 Hz with minimal damping (damping ratio 0.0069), attributed to its higher core density of 172.94 kg/m 3 . The incorporation of particulate hemp powder, particularly at 5%, resulted in significant stiffness reductions of 49% in HIC and 27% in LIC designs due to decreased material density and the softening effect of the particulate filler. However, this reduction in stiffness was counterbalanced by enhanced damping behavior, with LIC configurations consistently demonstrating higher damping ratios and superior energy dissipation capabilities. Finite element simulations using ANSYS exhibited strong correlation with experimental results, particularly for LIC geometries, with prediction errors ranging from 2.84% to 5.90%. The study concludes that lotus‐inspired cellular structures, despite exhibiting slightly lower absolute stiffness, provide more stable and predictable mechanical performance, making them advantageous for lightweight engineering applications requiring both moderate structural rigidity and enhanced vibration damping. Future investigations may explore multi‐material printing strategies, optimized cellular geometries, or nano‐particulate integration to further enhance performance.