Vibration and Sound Radiation Characteristics of a Novel Integrated Absorber Periodic Layered Isolator

Purpose: Vibration isolator combining the mechanical metamaterials could greatly improve the vibration isolation and sound suppression performances due to the extreme vibration attenuation in the forbidden bandgaps. The structure design, vibration and sound radiation analysis of the traditional isolator co-existing the Bragg and locally resonant metamaterials has attracted wide attention. The paper presents a novel integrated absorber periodic layered isolator, where the periodic layered isolator shows the Bragg scattering effect and the integrated absorber shows the locally resonant effect. The designed integrated periodic layered isolator combines periodic metal layer and rubber layer in adjacent and periodically embeds metal thin plate and metal ring block as absorber in metal layer. Method: Finite element method (FEM) analysis and the experimental validation of the proposed integrated absorber periodic layered isolator are carried out comparing to those of the periodic layered isolator. Furthermore, the influences of the structural parameter of the integrated absorber periodic layered isolator on the bandgap characteristic are investigated. Results: The results demonstrate that the integrated absorber periodic layered isolator increases a low-frequency bandgap comparing to the periodic layered isolator. The vibration responses of the two periodic isolators have broadband vibration attenuation at middle and high frequencies, while the vibration response of the integrated absorber periodic layered isolator obviously fall in low frequency bandgap. The sound radiation suppression of the integrated absorber periodic layered isolator performs better than that of the periodic layered isolator in the frequencies of the bandgaps. The parametrical analysis shows that the bandgap structure could be adjusted by the structural parameters of the proposed isolator. With different structural parameters, the bandgap coverages of the integrated absorber periodic layered isolators show around 70% while those of the periodic layered isolators show around 60% below 3000 Hz. Conclusion: The integrated absorber periodic layered isolator opens the low frequency bandgap which is more suitable for vibration isolation at low frequency in engineering application.