Transmission loss characteristics of an annular cavity with arbitrary port locations using Green's function method.
The prediction of transmission loss characteristics of a short chamber requires the study of both longitudinal as well as transverse modes. This prompts the development of a three-dimensional (3D) transfer matrix, which can address the wave propagation in all three directions. Accordingly, an analytical methodology for transmission loss characteristics of an annular cavity using Green's function method is presented in this paper. The 3D wave equation is used to derive the mode shape functions for the cavity. The average pressure on the inlet and outlet ports is predicted using the Green's function derived from the mode shapes. Three different port location configurations of the annular cavity are considered for establishing the analytical methodology, viz., face-inlet-face-outlet (FIFO), side-inlet-side-outlet (SISO), and face-inlet-side-outlet (FISO). Numerical model results are used to corroborate the analytical results. The effects of geometrical parameters on the transmission loss are studied.
Loss of a Side Outlet Muffler
Vibration and noise reductionmethods are important research directions inmany industries. Mufflers are widely used in pipelines to reduce noise and vibration transmission. A theoretical analysis is conducted to determine the noise reduction mechanism of a muffler with a side outlet, and the results are verified with experiments. *e quadrupole parameters of the muffler are obtained using transfer matrix analysis, and sensitivity analysis of the quadrupole parameters is conducted. *e influence of the side outlet location on the transmission loss of the muffler is investigated experimentally using an impedance tube. *e key factors affecting the transmission loss are analyzed.*e theoretical calculation results of the transmission loss of the side outlet muffler are in good agreement with the experimental results.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.