Design of lightweight broadband flexural wave absorber for noise and vibration attenuation through topological optimization

A lightweight structure endowed with broadband wave absorption capabilities is highly sought in the development of vibration and noise reduction applications. In this work, we present a type of absorbing meta-barrier via topological optimization which totally absorbs the waves near the boundaries at an extremely broadband frequency range. In order to elucidate the perfect absorption mechanism, we developed a theoretical model that incorporates a lumped mass-spring-damper system coupled to a semi-infinite thin beam. The sample is fabricated through 3D printing. The absorption performance is experimentally characterized, and a maximum absorption of more 95% is achieved over a broad frequency range from 700 Hz to over 3000 Hz in the experiment. Our approach provides an effective solution to the design of lightweight broadband noise and vibration isolation/suppression devices for practical engineering applications.