The Experts below are selected from a list of 72 Experts worldwide ranked by ideXlab platform
Anas Batou - One of the best experts on this subject based on the ideXlab platform.
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Attenuation of noise and vibration at low frequencies using a nonlinear microstructured material
2017Co-Authors: Déborah Lavazec, Denis Duhamel, Gwendal Cumunel, Christian Soize, Anas BatouAbstract:Because of their large wavelength, the acoustic waves and mechanical vibrations at low frequencies cannot easily be reduced in the structures by using dissipative porous materials (like fiberglass) contrarily to the waves at middle and high frequencies. We propose to reduce the noise and the vibrations on a broad low-frequency band through a microstructured material by inclusions that are randomly arranged in the material matrix (which is also structural). The inclusions will have a dynamical behaviour which will be imposed in the nonlinear domain in such a way that the energy be efficiently pumped over a broad frequency band around the resonance frequency. Indeed, the nonlinearity leads to a pumping of the energy over a broader frequency band than the linearity. The first step of this work is to design and to analyze the efficiency of an inclusion, which is made up of a Hollow Frame including a point mass centered on a beam. This inclusion is designed in order to exhibit nonlinear geometric effects in the low-frequency band that is observed. For this first step, the objective is to develop the simplest mechanical model that has the capability to nearly predict the experimental results that are measured. The second step, which is not presented in the paper, will consist in developing a more sophisticated nonlinear dynamical model of the inclusion. In this paper, devoted to the first step, it is proved that the nonlinearity induces an attenuation on a broad frequency band around the resonance, contrarily to its linear behavior for which the attenuation is only active in a narrow frequency band around the resonance. We will present the design in terms of geometry, dimension and materials for the inclusion, the experimental manufacturing of this system realized with a 3D printing system, and the experimental measures that have been performed. We compare the prevision given by the stochastic numerical model with the measurements. The results obtained exhibit the physical attenuation over a broad low-frequency band, as intended.
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Nonlinear microstructured material to reduce noise and vibrations at low frequencies
2017Co-Authors: Déborah Lavazec, Denis Duhamel, Gwendal Cumunel, Christian Soize, Anas BatouAbstract:At low frequencies, for which the wavelengths are wide, the acoustic waves and the mechanical vibrations cannot easily be reduced in the structures at macroscale by using dissipative materials, contrarily to the middle-and high-frequency ranges. The final objective of this work is to reduce the vibrations and the induced noise on a broad low-frequency band by using a microstructured material by inclusions that are randomly arranged in the material matrix. The dynamical regimes of the inclusions will be imposed in the nonlinear domain in order that the energy be effectively pumped over a broad frequency band around the resonance frequency, due to the nonlinearity. The first step of this work is to design and to analyze the efficiency of an inclusion, which is made up of a Hollow Frame including a point mass centered on a beam. This inclusion is designed in order to exhibit nonlinear geometric effects in the low-frequency band that is observed. For this first step, the objective is to develop the simplest mechanical model that has the capability to roughly predict the experimental results that are measured. The second step, which is not presented in the paper, will consist in developing a more sophisticated nonlinear dynamical model of the inclusion. In this paper, devoted to the first step, it is proved that the nonlinearity induces an attenuation on a broad frequency band around the resonance, contrarily to its linear behavior for which the attenuation is only active in a narrow frequency band around the resonance. We will present the design in terms of geometry, dimension and materials for the inclusion, the experimental manufacturing of this system realized with a 3D printing system, and the experimental measures that have been performed. We compare the prevision given by the stochastic computational model with the measurements. The results obtained exhibit the physical attenuation over a broad low-frequency band, which were expected.
Hong Guo - One of the best experts on this subject based on the ideXlab platform.
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Self-assembled hierarchical Hollow CuS@MoS2 microcubes with superior lithium storage
Electrochimica Acta, 2017Co-Authors: Hang Zhou, Hui Liu, Mengfang Liang, Beihong Liu, Hong GuoAbstract:Abstract Hierarchical Hollow CuS@MoS 2 microcbues are prepared via an effective strategy. The synthesis mechanism of Hollow CuS@MoS 2 microcubes is based on the transformation from Cu 2 O to CuS and the precipitation formation of MoS 2 at the same time. The Hollow microspheres are characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. CuS@MoS 2 Hollow microcbues can deliver a reversible specific capacity of 912 mAh g −1 after 200 cycles at a specific density of 500 mA g −1 , and maintain good rate capability from 500 to 4000 mA g −1 . This Hollow Frame contributes greatly for the alleviation of mechanical stress during electrochemical cycling, and buffers volume change of active materials. Meanwhile, Hollow structure shortens the diffusion distance of lithium ions, and thus is beneficial for its rate performance. Furthermore, hybrid materials are also a valid way to improve the electrochemical property of transition metals sulfides. Therefore, the prepared CuS@MoS 2 microcubes present enhanced electrochemical performance. The reported strategy is general, fast and can also be possibly applied for the fabrication of other advanced Hollow materials used in the energy and environmental filed.
Déborah Lavazec - One of the best experts on this subject based on the ideXlab platform.
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Attenuation of noise and vibration at low frequencies using a nonlinear microstructured material
2017Co-Authors: Déborah Lavazec, Denis Duhamel, Gwendal Cumunel, Christian Soize, Anas BatouAbstract:Because of their large wavelength, the acoustic waves and mechanical vibrations at low frequencies cannot easily be reduced in the structures by using dissipative porous materials (like fiberglass) contrarily to the waves at middle and high frequencies. We propose to reduce the noise and the vibrations on a broad low-frequency band through a microstructured material by inclusions that are randomly arranged in the material matrix (which is also structural). The inclusions will have a dynamical behaviour which will be imposed in the nonlinear domain in such a way that the energy be efficiently pumped over a broad frequency band around the resonance frequency. Indeed, the nonlinearity leads to a pumping of the energy over a broader frequency band than the linearity. The first step of this work is to design and to analyze the efficiency of an inclusion, which is made up of a Hollow Frame including a point mass centered on a beam. This inclusion is designed in order to exhibit nonlinear geometric effects in the low-frequency band that is observed. For this first step, the objective is to develop the simplest mechanical model that has the capability to nearly predict the experimental results that are measured. The second step, which is not presented in the paper, will consist in developing a more sophisticated nonlinear dynamical model of the inclusion. In this paper, devoted to the first step, it is proved that the nonlinearity induces an attenuation on a broad frequency band around the resonance, contrarily to its linear behavior for which the attenuation is only active in a narrow frequency band around the resonance. We will present the design in terms of geometry, dimension and materials for the inclusion, the experimental manufacturing of this system realized with a 3D printing system, and the experimental measures that have been performed. We compare the prevision given by the stochastic numerical model with the measurements. The results obtained exhibit the physical attenuation over a broad low-frequency band, as intended.
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Nonlinear microstructured material to reduce noise and vibrations at low frequencies
2017Co-Authors: Déborah Lavazec, Denis Duhamel, Gwendal Cumunel, Christian Soize, Anas BatouAbstract:At low frequencies, for which the wavelengths are wide, the acoustic waves and the mechanical vibrations cannot easily be reduced in the structures at macroscale by using dissipative materials, contrarily to the middle-and high-frequency ranges. The final objective of this work is to reduce the vibrations and the induced noise on a broad low-frequency band by using a microstructured material by inclusions that are randomly arranged in the material matrix. The dynamical regimes of the inclusions will be imposed in the nonlinear domain in order that the energy be effectively pumped over a broad frequency band around the resonance frequency, due to the nonlinearity. The first step of this work is to design and to analyze the efficiency of an inclusion, which is made up of a Hollow Frame including a point mass centered on a beam. This inclusion is designed in order to exhibit nonlinear geometric effects in the low-frequency band that is observed. For this first step, the objective is to develop the simplest mechanical model that has the capability to roughly predict the experimental results that are measured. The second step, which is not presented in the paper, will consist in developing a more sophisticated nonlinear dynamical model of the inclusion. In this paper, devoted to the first step, it is proved that the nonlinearity induces an attenuation on a broad frequency band around the resonance, contrarily to its linear behavior for which the attenuation is only active in a narrow frequency band around the resonance. We will present the design in terms of geometry, dimension and materials for the inclusion, the experimental manufacturing of this system realized with a 3D printing system, and the experimental measures that have been performed. We compare the prevision given by the stochastic computational model with the measurements. The results obtained exhibit the physical attenuation over a broad low-frequency band, which were expected.
Geoffrey R. Tomlinson - One of the best experts on this subject based on the ideXlab platform.
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Computational approaches to prediction of damping behavior of nanoparticle-reinforced coatings and foamy structures
III European Conference on Computational Mechanics, 1Co-Authors: Maksim V. Kireitseu, Geoffrey R. TomlinsonAbstract:This paper concerns advanced computational engineering approach based on finite element modeling and fundamental physical phenomena of energy dissipation mechanisms related to vibration damping [1]. Nanoparticle/tube-reinforced composite materials are relatively new class of engineering materials and their vibration damping application is commonly unknown from both computational and experimental sides [2]. The novel concept of nanoparticle-based damping technology shows that a molecule-level mechanism can considerably enhance vibration damping and dynamic of aerospace components (fan blades) via enhanced energy dissipation because of large surface-to-volume aspects in nanoparticle-reinforced composite material, large damping energy sources for friction and slipstick motion at interfaces of matrix and nanoparticle. Therefore, to add some knowledge our group is working on computational characterization approach and modeling technique that describe relationships between structure and damping/dynamic properties of the materials, formalize the set of structural mechanical approaches to build a bridge between macro and nanoscales. Structural micro to nanomechanical approach has been developed to predict damping (dynamic) behavior of carbonnanotube- reinforced composite material. The model is based on “stick-slip” frictional motion to address the damping characteristics of SWNT-reinforced composite material. It is worth noting that SWNT can be represented as a shell Hollow Frame-like structure with a simple nanoscale damping spring characteristics. Thus the developed model can be assembled into entire engineering workbench. A comparison of available modeling strategies is presented. Carbon nanotube-reinforced material is particularly illustrated via advanced numerical codes, using a Hollow shell representation of the individual nanotubes. Comparing to the FEM, the new technique may introduce further reduction of both computer time and storage requirement. Thus results of the project will potentially create fundamental basis for investigation and development of 3-D reinforced composite structures with high nanoscale structures volume content, using nano-scale reinforcement architecture to reduce component weight and dimension.
Hang Zhou - One of the best experts on this subject based on the ideXlab platform.
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Self-assembled hierarchical Hollow CuS@MoS2 microcubes with superior lithium storage
Electrochimica Acta, 2017Co-Authors: Hang Zhou, Hui Liu, Mengfang Liang, Beihong Liu, Hong GuoAbstract:Abstract Hierarchical Hollow CuS@MoS 2 microcbues are prepared via an effective strategy. The synthesis mechanism of Hollow CuS@MoS 2 microcubes is based on the transformation from Cu 2 O to CuS and the precipitation formation of MoS 2 at the same time. The Hollow microspheres are characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. CuS@MoS 2 Hollow microcbues can deliver a reversible specific capacity of 912 mAh g −1 after 200 cycles at a specific density of 500 mA g −1 , and maintain good rate capability from 500 to 4000 mA g −1 . This Hollow Frame contributes greatly for the alleviation of mechanical stress during electrochemical cycling, and buffers volume change of active materials. Meanwhile, Hollow structure shortens the diffusion distance of lithium ions, and thus is beneficial for its rate performance. Furthermore, hybrid materials are also a valid way to improve the electrochemical property of transition metals sulfides. Therefore, the prepared CuS@MoS 2 microcubes present enhanced electrochemical performance. The reported strategy is general, fast and can also be possibly applied for the fabrication of other advanced Hollow materials used in the energy and environmental filed.