Applied Mechanics and Materials Vols. 670-671

Abstract: A nonideal acoustic cloak with realizable physical properties is proposed. The density and modulus of the designed acoustic cloak are in a reasonable range of material parameters. Full-wave simulations are performed to demonstrate the properties of the proposed cloak. Results on far-field sound pressure level show that the nonideal acoustic cloak decreases the scattering field intensity and the target strength (TS) of the scatterer. The nonideal acoustic cloak also has significant effect on suppressing internal radioactive noise. A comparison is made with the reduced cloak proposed by Chen.

Abstract: The design of automotive trim configurations has become increasingly driven to maximize the acoustic performance benefit while minimizing material weight. Statistical energy analysis (SEA) can serve as a useful tool to predict the high frequency acoustic response on both a component and full vehicle level. This paper focuses on the automotive dash panel, using VAOne software to establish the SEA model. The method of orthogonal test is applied to optimize the sound package design to satisfy maximum high-frequency transmission loss (TL) and minimum weight by modifying the acoustic material, thickness, surface density and coverage of sound package.

Abstract: An increasing demand for vehicle noise control has been proposed and at the same time, vehicle weight and fuel economy have become critical for the automotive industry. The methodology of statistical energy analysis (SEA) is used to balance both light weight and high noise insulation performance. In this paper, the floor system which is one of the major paths for vehicle interior noise is studied with two sound package systems, the original floor insulation system and the lightweight one. The vehicle floor system is modeled by SEA and its transmission loss (TL) is analyzed. The results show that under certain sound package coverage, the TL of the floor system with the lightweight sound package is a little larger than the TL with the lightweight one. However, the lightweight sound package system has better absorption property and the advantage of weight reduction. Finally, in order to get the better TL, the sound package design is performed.

Abstract: Applying the method of finite element to research the composite damping vibration reduction effect of circular saw blade. Based on the structure of composite damping circular saw blade, contrast a composite saw blade and ordinary saw blade, to design and compare their vibration characteristics. Through research the vibration characteristics on the three kinds of saw blades found that the each order natural frequency of composite damping saw blade and composite saw blade is smaller than the corresponding order natural frequency of ordinary saw blade, and the each order natural frequency of composite damping saw blade slightly smaller than the corresponding order natural frequency of composite saw blade; The maximum displacement deformation of composite damping saw blade and composite saw blade is smaller than the corresponding order of ordinary saw blade. Through study the damping characteristics found that the modal damping ratio of composite damping saw blade is greater than others; and research the dynamics characteristics found that composite damping blade's vibration attenuation faster than others, and it illustrate the good effect of damping saw blade.

Abstract: The blade-disc in a turbine is characterized by symmetric-acyclic opening structure on the disc body. Four different numerical models with 3-D finite element method were established in the present investigation. The wave propagation technique was employed and the modal analysis of the blade disc was performed. The modal and vibration characteristics of different models in the same rotational speeds were compared in consideration of non-linear coupling/ interactions between blade and disc. The results indicate that in the modal analysis of symmetric-acyclic blade-disc system, the openings structure has low impact on the low-order mode frequency. Thus, cyclic symmetric model without the opening structure can help to get general frequency forecast to improve the analysis efficiency.

Abstract: Three-dimensional finite element analysis model of transmission tower is established by using ANSYS software. According to the characteristics of the tower, wind vibration control effect of transmission tower is to be studied through seven different kinds of distribution of MR dampers condition, then get the dynamic response in different position of the tower body and tower top. The analysis results show that:: Through using of different damper layout, it can reduce vibration of the tower, especially the third scheme which is tower head lower half part edge member bar plus dampers had the most significant vibration reduction effect. Research results can be reference for engineering design and engineering practice, it also has a certain theoretical and practical significance.

Abstract: This article from the vocal cords vocal mechanism, this paper presents a new model of vocal fold vibration and found the theoretical basis of the model is analyzed in detail on the proposed model, the establishment of research and analysis. The main vocal organs acoustic and acoustic characteristics of speech analyzed in the process. Study on the characteristics of the excitation source, the acoustic properties of the vocal organs and research work status channel. Lastly we analyzed the relationship between the vibration characteristics of the vocal cords and larynx between pronunciation tones.

Abstract: This paper reviews the study of wind induced vibration of transmission power tower-line system. Each fields of research of transmission power tower-line system —analysis model, dynamic characteristic, wind response and vibration control —are systematically introduced. the problem that exist in this stage and the development trend are summarized in the conclusions.

Abstract: This paper analyzes the modes of vibration of the strings and the strings of the material, the thickness effect on pronunciation, the establishment of a mass-spring model of vibrating strings and studied when the force pulling the strings and plucked violins panel vibration. Spectrum analysis and processing by MATLAB, the vibration of the resonance box is directly converted into sound, a sound judgment using spectral analysis methods.

Abstract: The seismic performance of the axial fan used in nuclear power plants (NPP) is investigated by using the commercial FEM software ANSYS. In the modal analysis, the first five orders of the natural frequencies of the axial fan is obtained, as well as the corresponding vibration modes. And in the spectrum analysis, the complete quadratic mode combination method is applied to determine the dynamic response of the axial fan under a random seismic excitation. The simulation results show that the seismic performance of the axial fan satisfies the requirement of the RCC-M 2007 design codes.