Vibration mitigation via integrated acoustic black holes

As a passive technology for vibration reduction, embedded acoustic black holes (EABHs) have been extensively studied in the last decades. Due to the substantial decrease of thickness, however, traditional EABHs inevitably meet the problem of low stiffness and strength and even are prone to structural failure. Therefore, in this paper, integrated acoustic black holes (IABHs) are suggested to provide another concept of exploiting ABHs. An IABH is considered as a dynamic vibration absorber (DVA) when it is connected to the host structure, via attaching ABHs, rather than via embedding them. As the research on the IABHs is still in its preliminary stage, a semi-analytical method is developed to characterize such a complex mechanical system in this paper. In particular, the coupling effects between the host structure and the IABHs are accounted for by taking the advantage of artificial springs. The correctness of the proposed model is validated against finite element simulations. After that, the zeros and poles of the reflection coefficient are discussed for obtaining the optimal solution about the size of the IABH and damping layers. Results show that it will be very effective once the IABH is properly shaped. Experiments are made to validate the correctness of the analysis model and damping effect of the optimal IABH. The theoretical model developed in this paper facilitates the characterization of the IABH DVAs, and is expected to accelerate their applications in engineering.