Evaluation of Flanking Noise Transmission within Periodically Distributed Lightweight Beam Elements

Wooden frame structures are highly preferred as lightweight building systems nowadays. Lightweight building structures have gained more interest due to lower cost of production. However, there is a growing concern regarding noise and vibration issues within lightweight structures. Sound may pass from one room to another as indirect or flanking noise via joints or as direct transmission between adjacent rooms. The present analysis concerns flanking transmission within two-dimensional infinite periodic beam structures. The beam is comprised of two different materials placed in a periodic manner. Two different theoretical methods are taken into consideration to evaluate flanking noise transmission within the beam structure: The finite-element method (FEM) and a Floquet theory approach. Research is carried out regarding the effects of periodicity in a wide range of frequencies from 0 to 300 Hz. The nature of vibrations and flexural wave propagation is studied, and stop bands are identified at certain periodic intervals within the considered frequency range. The span of the stop bands is found to increase in size with an increase of the frequency. Results from both of the above methods are thoroughly investigated and compared. The findings of the analysis are applicable in the design of structures such as buildings, ships and aircrafts, regarding minimization of flanking noise transmission.