Low‐Frequency Multimodal Vibration Damping Characteristics of Acoustic Black Hole Beams with Variable Modulus of Elasticity

Bending waves can achieve energy aggregation and recovery through the acoustic black hole (ABH) effect, yet ABH structures often lack low‐frequency damping capability. This work proposes the axial direction variable elastic modulus ABH structure (A‐VSABH) to achieve the low‐frequency multimodal vibration damping and energy aggregation effect of ABH. This work creates the fitting function of the elastic modulus and the phase wave velocity along the axial direction based on the gradient change of the elastic modulus along the thickness variation direction of the A‐VSABH beam. Analytical and experimental results validate the validity and accuracy of the wave velocity fitting function of A‐VSABH beams in this work. After that, a comparison with ABH structures highlights the benefits of A‐VSABH in terms of energy aggregation and reflection coefficient. The trend of how various parameters affect the bending wave energy aggregation of the A‐VSABH structure is finally explained. A multiobjective offline optimization model combining GSM and NSGA‐II is then established to determine the optimal parameters of the proposed structure, which offers useful design guidance for the low‐frequency multimodal vibration damping‐oriented ABH metamaterials. This model is based on the trade‐off between structural strength and low‐frequency multimodal vibration‐damping capability.