Sound Transmission of a Circular Membrane with Ring Masses

Abstract

In recent years locally resonance acoustic metamaterials have displayed feasible sound insulation capabilities at low frequencies Low frequency noise is often generated by machines when they are being operated and is difficult to be blocked by a traditional heavy concrete wall Using acoustic metamaterials sound insulation is much easier to be achieved Although these metamaterials is usually light and thin they still work well for insulating noise In this thesis we present a theoretical method to investigate transmission loss of circular membranes with mass inclusions and the analytical results are compared with finite element results We then discuss the characteristics of transmission loss (TL) effective dynamic mass and sound power flow We adjusted the mass weight area and the pretension force on the edges of the membrane and considered their effect on TL curves Furthermore the central mass embedded in the structure was replaced by the ring mass and we also considered a membrane with both one central mass and one ring mass or a membrane containing two masses The TL valley and peak frequency and bandwidth can be tuned by varying surface density the number of rings and ring locations

Date of Award	2015 Aug 4
Original language	English
Supervisor	Jung-San Chen (Supervisor)