Optimal Design of Structural Parameters of Flexible Linkage Mechanisms for Noise Attenuation

Author(s):  
Xianmin Zhang ◽  
Jianwei Lu

Optimal design of structural parameters of flexible linkage mechanisms for noise attenuation is studied in this paper. The sum of weighted mass of the structure and weighted measure of acoustic radiation energy is taken as the performance index, and the thickness of the links of the mechanism is taken as the design variable. Optimization is carried out based on the modified constrained variable metric method. Simulation demonstrates that the proposed method is valid.

Author(s):  
Xianmin Zhang ◽  
Arthur G. Erdman

The optimal placement of sensors and actuators in the active vibration control of flexible linkage mechanisms is studied. Based on the concept of the controllability and the observability of the controlled subsystem and the residual subsystem, the objective functions are proposed aiming at the maximization of the controllability and the observability of the controlled modes and minimization of those of the residual modes. The optimal model is solved using the modified constrained variable metric method. Numerical example shows the validness of the proposed modeling.


Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 602-608
Author(s):  
Jiyong Jin ◽  
Congyun Zhu ◽  
Rui Wu ◽  
Yanming Liu ◽  
Miao Li

Abstract The influence of acoustic radiation is considered in the prediction of noise attenuation effect of sound barrier, which provides a theoretical reference for further improving the insertion loss of sound barrier. Based on the theory of thin plate vibration, the vibration mode and natural frequencies of sound barrier under arbitrary boundary conditions are established by using two-dimensional beam function method, and the forced vibration response of the sound barrier is calculated based on the modal superposition method. MATLAB software (MathWorks Company, Natick, Massachusetts, USA) is used to calculate the natural frequencies and the radiated sound power level of the sound barrier, which indicated that the sound radiation caused by external excitation would significantly increase the sound pressure level at the received point, which should be considered as one of the influencing factors in the prediction of noise attenuation effect. The influence of diverse structural parameters on the radiated acoustic power is compared, providing an excellent reference for the design of sound barrier with low noise.


Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1163
Author(s):  
Yajun Yu ◽  
Liangshan Li ◽  
Jiale Zhao ◽  
Xiangeng Wang ◽  
Jun Fu

This paper takes a local drum-type corn thresher as an example. In order to make the threshing principle transform to the plate-tooth type, the width of the spike-tooth threshing component is increased gradually, and three threshing components of different shape and size are selected as the research objects. Based on the preliminary experimental research, the corn threshing process is simulation analyzed using the self-developed corn threshing process analysis software. The effects of the width of the threshing component on the corn ears threshing rate and kernel damage rate under different rates of drum rotation were studied from a macroscopic perspective. The results show that with the increase of drum rotation rate, both the corn ear threshing rate and kernel damage rate increase; with the increase of threshing component width, the threshing rate increases and the damage rate decreases; and when the component width is too large, the stacking between adjacent components has an impact on the threshing performance. The effects of threshing component width on the amount of kernel threshing and the total compressive force during the simulation time were investigated from microscopic perspective at different rates of drum rotation, and the results show that the microscopic analysis is consistent with the macroscopic analysis. Therefore, the optimization of the structural parameters and operating parameters of the threshing component was achieved. When the width of the threshing component was 25 mm and the roller speed was 187.50 rpm, the threshing performance was optimal, with a 98.04% corn ears threshing rate and a 2.56% kernel damage rate. This paper verifies the practical applicability of the corn threshing process analysis software and provides a reference for the optimal design of threshing devices.


2021 ◽  
Vol 871 ◽  
pp. 216-221
Author(s):  
Jing Tao Dai ◽  
Pei Zhong Zhao ◽  
Hong Bo Su ◽  
Hao Dong Liu ◽  
Yu Bo Wang ◽  
...  

Composite material is widely used to maintain damaged structures of aircraft. The 3D finite element model of composite cement maintenance for aircraft is established by finite element method software ANSYS Workbench. The structural characteristics and usage status of the composite cement maintenance model is analyzed, and then the optimal structural parameters of the composite patch are obtained, including the length, width and thickness. The results show that the composite cement maintenance method could effectively restore the rigidity, and improve the strength of the structure. Furthermore, the optimal design for composite patch ensures safety of aircraft, economics of maintenance, and operability of repair methods.


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