CHARACTERISTICS OF LOCALIZED ACOUSTIC MODES IN A N -LAYER-BASED SUPERLATTICE WITH DEFECT LAYERS

We present general expressions to calculate localized acoustic modes in a N -layer-based superlattice with defect layers by using a transfer-matrix method. Numerically, we investigate the properties of the localized modes in an AlAs–AlxGa1-xAs–GaAs superlattice with a defect layer AlyGa1-yAs. The influences of material and structural parameters on the localized modes are revealed with analyses. A comparison between the higher and lower branches of the localized modes is made. We show that the minigap and optimum localization are determined by the material and structural parameters of constituent layers in a unit cell as well as periodicity, while localized modes are dependent on both constituent and defect layers. Moreover, we find that the localized modes vary periodically with the width of the defect layer, and the number of branches of localized modes increases with the index of minigaps.

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A method for determining the minimum period number in finite locally resonant phononic crystal beams

Journal of Vibration and Control ◽

10.1177/1077546319889851 ◽

2020 ◽

Vol 26 (9-10) ◽

pp. 801-813

Author(s):

Panxue Liu ◽

Shuguang Zuo ◽

Xudong Wu ◽

Minghai Zhang

Keyword(s):

Band Gap ◽

Transfer Matrix ◽

Transfer Matrix Method ◽

Matrix Method ◽

Structural Parameters ◽

Phononic Crystal ◽

Minimum Period ◽

Comprehensive Index ◽

Vibration Attenuation ◽

Vibration Transmissibility

To achieve the target band-gap in finite locally resonant phononic crystal beams, a method for determining the minimum period number is proposed. The vibration transmissibility method is extended to deal with the finite locally resonant phononic crystal beam. Comparing the vibration attenuation region obtained from the transmissibility method with the band-gap from the conventional transfer matrix method, the minimum period number can be calculated. Based on two forming patterns of locally resonant phononic crystal beams, the effects of the lattice constant and structural parameters of resonators on the band-gap as well as the influence of the period number on the vibration transmission characteristic are investigated. The minimum period number method can improve the applicability of the transmissibility method in the design of band-gaps and overcome the drawback that the transfer matrix method lacks the actual vibration attenuation. Finally, a comprehensive index is introduced to evaluate the effect of vibration reduction.

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A Simplified Transfer Matrix Method for Horizontal Seismic Response of Wall-Frame Structures Considering SSI

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1065-1069.1026 ◽

2014 ◽

Vol 1065-1069 ◽

pp. 1026-1030 ◽

Cited By ~ 1

Author(s):

Shuo Ying Zhang ◽

Ming Tao Li

Keyword(s):

Seismic Response ◽

Transfer Matrix ◽

Transfer Matrix Method ◽

Matrix Method ◽

Seismic Behavior ◽

Structural Parameters ◽

Frame Structure ◽

Frame Structures ◽

Elastic Parameters ◽

Efficient Tool

Based on the double member model of wall-frame structure and the corresponding transfer matrix method, the concept of frequent impedance of rigid foundation is introduced so that SSI can be taken into account. This method is more convenient and efficient compared to finite element method because of fewer structural parameters and faster calculation speed. Necessary structure parameters include 7 parameters of each storey, geometry size and total mass of foundation and elastic parameters of site soil. Totally 39 examples were calculated for 13 values of foundation mass and 3 kinds of soil, which are compared to the result of fix bottom model of upper structure. Results show that SSI does not always deduce a decrease of seismic response. Sometimes SSI may increases structural displacement evidently. The simplified method would provide structure designers an efficient tool to understand seismic behavior of wall-frame structures with various foundation and site soil.

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Effect of amorphous sequences on the longitudinal acoustic modes in partially crystalline polymers. I. Transfer matrix method

Journal of Polymer Science Polymer Physics Edition ◽

10.1002/pol.1983.180210808 ◽

1983 ◽

Vol 21 (8) ◽

pp. 1357-1380 ◽

Cited By ~ 10

Author(s):

G. R. Strobl

Keyword(s):

Transfer Matrix ◽

Transfer Matrix Method ◽

Matrix Method ◽

Longitudinal Acoustic ◽

Crystalline Polymers ◽

Acoustic Modes

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Dynamical Optimization of Tracked Vehicle Based on Riccati Transfer Matrix Method and PSO Algorithm

Volume 6: 14th International Conference on Multibody Systems, Nonlinear Dynamics, and Control ◽

10.1115/detc2018-85733 ◽

2018 ◽

Author(s):

Pingxin Wang ◽

Xiaoting Rui ◽

Jianshu Zhang ◽

Hailong Yu ◽

Hongtao Zhu

Keyword(s):

Transfer Matrix ◽

Transfer Matrix Method ◽

Matrix Method ◽

Closed Loop ◽

Structural Parameters ◽

Pso Algorithm ◽

Closed Loop System ◽

Vibration Acceleration ◽

Tracked Vehicles ◽

Dynamical Optimization

Aiming at the problems of complex modeling and low calculation efficiency during dynamical optimization of tracked vehicles, a method for the closed-loop system called Riccati transfer matrix method for multibody system is proposed. In order to reduce the vibration acceleration of track shoes in the driving process, this paper uses the PSO algorithm and utilizes a strategy of decreasing the inertia weight to optimize the structural parameters of tracked vehicles. The research shows that the root mean square of vibration acceleration of track shoes above the support rollers is obviously reduced. This method provides a theoretical reference for the design of tracked vehicles and is beneficial to the dynamic design of complex systems.

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