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Full-Text Articles in Mechanical Engineering
Scale Models Of Acoustic Scattering Problems Including Barriers And Sound Absorption, Nan Zhang
Scale Models Of Acoustic Scattering Problems Including Barriers And Sound Absorption, Nan Zhang
Theses and Dissertations--Mechanical Engineering
Scale modeling has been commonly used for architectural acoustics but use in other noise control areas is nominal. Acoustic scale modeling theory is first reviewed and then feasibility for small-scale applications, such as is common in the electronics industry, is investigated. Three application cases are used to examine the viability. In the first example, a scale model is used to determine the insertion loss of a rectangular barrier. In the second example, the transmission loss through parallel tubes drilled through a cylinder is measured and results are compared to a 2.85 times scale model with good agreement. The third example …
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 …
Simulation Of Whistle Noise Using Computational Fluid Dynamics And Acoustic Finite Element Simulation, Jiawei Liu
Simulation Of Whistle Noise Using Computational Fluid Dynamics And Acoustic Finite Element Simulation, Jiawei Liu
Theses and Dissertations--Mechanical Engineering
The prediction of sound generated from fluid flow has always been a difficult subject due to the nonlinearities in the governing equations. However, flow noise can now be simulated with the help of modern computation techniques and super computers. The research presented in this thesis uses the computational fluid dynamics (CFD) and the acoustic finite element method (FEM) in order to simulate the whistle noise caused by vortex shedding. The acoustic results were compared to both analytical solutions and experimental results to better understand the effects of turbulence models, fluid compressibility, and wall boundary meshes on the acoustic frequency response. …
Finite Element Analysis Of Cancellous Bone, Lucas T. Wilkerson
Finite Element Analysis Of Cancellous Bone, Lucas T. Wilkerson
Theses and Dissertations--Mechanical Engineering
A variety of pathologies exist which increase the likelihood of bone fracture. Present methods for determining the fracture risk of a specific patient are based exclusively on the amount of bone present. While the quantity of bone tissue is correlated with strength, it neglects to account for bone’s intricate microarchitecture. To assess the effect of bone quality on strength, a methodology was developed for the structural analysis of cancellous bone biopsies. Thirty biopsies were selected from a pre-existing biopsy bank, and scanned using a SCANCO µCT-40 at a resolution of 30 microns. Cortical bone was removed from the resulting three-dimensional …