Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Mechanical Engineering
Utilization Of Empirical Models To Determine The Bulk Properties Of Compressed Sound Absorptive Materials, Ruimeng Wu
Utilization Of Empirical Models To Determine The Bulk Properties Of Compressed Sound Absorptive Materials, Ruimeng Wu
Theses and Dissertations--Mechanical Engineering
Empirical models based on flow resistivity are commonly used to determine the bulk properties of porous sound absorbing materials. The bulk properties include the complex wavenumber and complex characteristic impedance which can be used directly in simulation models. Moreover, the bulk properties can also be utilized to determine the normal incidence sound absorption and specific acoustic impedance for sound absorbing materials of any thickness and for design of layered materials. The sound absorption coefficient of sound absorbing materials is measured in an impedance tube using wave decomposition and the measured data is used to determine the flow resistivity of the …
A Transfer Matrix Approach To Determine The Low Frequency Insertion Loss Of Enclosures Including Applications, Shujian He
Theses and Dissertations--Mechanical Engineering
Partial enclosures are commonly used to reduce machinery noise. However, it is well known in industry that enclosures sometimes amplify the sound at low frequencies due to strong acoustic resonances compromising the performance. These noise issues are preventable if predicted prior to prototyping and production. Though boundary and finite element approaches can be used to accurately predict partial enclosure insertion loss, modifications to the model require time for remeshing and solving. In this work, partial enclosure performance at low frequencies is simulated using a plane wave transfer matrix approach. Models can be constructed and the effect of design modifications can …