The solid and finite element model of metal pushing type continuously variable transmission are established at speed ratio of i =0 5 and i=2 0. In order to solve the problem of the complicated of structure,the node no...The solid and finite element model of metal pushing type continuously variable transmission are established at speed ratio of i =0 5 and i=2 0. In order to solve the problem of the complicated of structure,the node node rod discrete finite element model is put forward and the whole system is simplified and established.The natural frequency and mode shape of system are solved by iterative Lanczos reduce method for sensitivity analysis in finite element model.The new method and the result can be used to improve the smoothness of the variable transmission system and to propose the theory for reducing noise at operation.展开更多
Uncertainties are unavoidable in practical engineering,and phononic crystals are no exception.In this paper,the uncertainties are treated as the interval parameters,and an interval phononic crystal beam model is estab...Uncertainties are unavoidable in practical engineering,and phononic crystals are no exception.In this paper,the uncertainties are treated as the interval parameters,and an interval phononic crystal beam model is established.A perturbation-based interval finite element method(P-IFEM)and an affine-based interval finite element method(A-IFEM)are proposed to study the dynamic response of this interval phononic crystal beam,based on which an interval vibration transmission analysis can be easily implemented and the safe bandgap can be defined.Finally,two numerical examples are investigated to demonstrate the effectiveness and accuracy of the P-IFEM and A-IFEM.Results show that the safe bandgap range may even decrease by 10%compared with the deterministic bandgap without considering the uncertainties.展开更多
The design strategies for powertrain mounting systems play an important role in the reduction of vehicular vibration and noise. As stiffness and damping elements connecting the transmission system and vehicle body, th...The design strategies for powertrain mounting systems play an important role in the reduction of vehicular vibration and noise. As stiffness and damping elements connecting the transmission system and vehicle body, the rubber mount exhibits better vibration isolation performance than the rigid connection. This paper presents a complete design process of the mounting system, including the vibration decoupling, vibration simulation analysis, topology optimization, and experimental verification. Based on the 6?degrees?of?freedom vibration coupling model of the powertrain mounting system, an optimization algorithm is used to extract the best design parameters of each mount, thus rendering the mounting system fully decoupled and the natural frequency well configured, and the optimal parameters are used to design the mounting system. Subsequently, vibration simulation analysis is applied to the mounting system, considering both transmission and road excitations. According to the results of finite element analysis, the topological structure of the metal frame of the front mount is optimized to improve the strength and dynamic characteristics of the mounting system. Finally, the vibration bench test is used to verify the availability of the optimization design with the analysis of acceleration response and vibration transmissibility of the mounting system. The results show that the vibration isolation performance of the mounting system can be improved effectively using the vibration optimal decoupling method, and the structural modification of the metal frame can well promote the dynamic characteristics of the mounting system.展开更多
The characteristics of vibrational power flow in an infinite elastic cylindrical shell filled with fluid are investigated. The simple harmonic motion of the shell and the pressure field in the contained fluid are desc...The characteristics of vibrational power flow in an infinite elastic cylindrical shell filled with fluid are investigated. The simple harmonic motion of the shell and the pressure field in the contained fluid are described by the Fltigge shell equations and Helmholtz equation respectively. The vibrational equation of this system is obtained by using the coupling of shell and fluid. The dispersion curves are discussed for different circumferential orders. By using Fourier transform and its inverse transform, the input power into this coupled system excited by a simple harmonic linearly distributed driving force is studied. Along the shell, the transmission of the power flow carried by different shell internal forces and by the contained fluid are展开更多
Polymer composite fibers with superior properties such as excellent combined strength and toughness and biocompatibility can be used in high-tech applications of braided protective devices and smart wearable,however t...Polymer composite fibers with superior properties such as excellent combined strength and toughness and biocompatibility can be used in high-tech applications of braided protective devices and smart wearable,however the research of high-performance polymer composite fiber remains in the infant stage.Here we present a strategy to produce strong and tough anisotropic polymer nanocomposite fibers with orientedly aligned salt rods using mechanical stretching-assisted salting-out treatment.The prepared nanocomposite fibers have a tensile strength of up to 786±2.7 MPa and an elongation at break of 81%,and the anisotropic fibers exhibit good transmission of mechanical vibration in the longitudinal direction with high resolution.During the fabrication process,the salt builds up into oriented rods during the directional salting process,and the polymer is confined to the 150 nm domain between the rods after the solvent is completely evaporated,giving the nanocomposite fibers superior mechanical properties.The presented strategy can be applied to the continuous mass production of nanocomposite fibers and is also generalizable to other polymer nanocomposites,which could extend the applicability of nanocomposite fibers to conditions involving more demanding mechanical loading and mechanical vibration transmission.展开更多
Mechanical vibration is an effective fruit harvesting method.To evaluate the dynamic characteristics of dwarf Chinese hickory(Carya cathayensis Sarg.)trees and the influence of the tree structure on transmission and a...Mechanical vibration is an effective fruit harvesting method.To evaluate the dynamic characteristics of dwarf Chinese hickory(Carya cathayensis Sarg.)trees and the influence of the tree structure on transmission and attenuation of dynamic response,a new method was proposed based on acceleration admittance measurement on dwarf Chinese hickory trees in orchard environment under impact excitation.The primary resonance frequencies of the tree can be determined based on the acceleration admittance measurement.The effect of the tree structure on the vibratory transmission was quantified using the attenuation ratio of the acceleration admittance.A 5-year-old dwarf Chinese hickory tree sample was tested.The responses at three resonance frequencies(5,9 and 12 Hz)were analyzed because they were identified as the most effective bands of excitation for the main part of the tree specimen.The results reveal that the variation of the dynamic response along the testing tree is greatly related to the Chinese hickory tree structure.The attenuation ratio of the acceleration admittance at the branch crotches indicates the leader top crotch may amplify the acceleration admittance no matter what the crotch angle and the branch diameter is.Unlike the crotches,the branch chain nodes generally have negative influence on the acceleration admittance along the branch chains which heavily depend on the branch chain configuration.The branch chains with a chain angle no less than 150°and a wood diameter ratio close to 1.0 could produce little influence on the vibration transmission.For those branches with chain angle less than 150°,the vibration was generally attenuated at their chain nodes at three resonance frequencies.To impose impact excitations on the tree,high mechanical harvesting efficiency could be achieved on those branch chains which are almost straight and uniform.展开更多
文摘The solid and finite element model of metal pushing type continuously variable transmission are established at speed ratio of i =0 5 and i=2 0. In order to solve the problem of the complicated of structure,the node node rod discrete finite element model is put forward and the whole system is simplified and established.The natural frequency and mode shape of system are solved by iterative Lanczos reduce method for sensitivity analysis in finite element model.The new method and the result can be used to improve the smoothness of the variable transmission system and to propose the theory for reducing noise at operation.
基金the National Natural Science Foundation of China(Nos.12272172 and 11847009)the Natural Science Foundation of Jiangsu Higher Education Institutions of China(No.22KJB580005)+1 种基金the Youth Talent Promotion Project from China Association for Science and Technology(No.2022QNRC001)the Priority Academic Program Development of Jiangsu Higher Education Institutions of China。
文摘Uncertainties are unavoidable in practical engineering,and phononic crystals are no exception.In this paper,the uncertainties are treated as the interval parameters,and an interval phononic crystal beam model is established.A perturbation-based interval finite element method(P-IFEM)and an affine-based interval finite element method(A-IFEM)are proposed to study the dynamic response of this interval phononic crystal beam,based on which an interval vibration transmission analysis can be easily implemented and the safe bandgap can be defined.Finally,two numerical examples are investigated to demonstrate the effectiveness and accuracy of the P-IFEM and A-IFEM.Results show that the safe bandgap range may even decrease by 10%compared with the deterministic bandgap without considering the uncertainties.
基金Supported by National Natural Science Foundation of China(Grant Nos.51375047,51775040)
文摘The design strategies for powertrain mounting systems play an important role in the reduction of vehicular vibration and noise. As stiffness and damping elements connecting the transmission system and vehicle body, the rubber mount exhibits better vibration isolation performance than the rigid connection. This paper presents a complete design process of the mounting system, including the vibration decoupling, vibration simulation analysis, topology optimization, and experimental verification. Based on the 6?degrees?of?freedom vibration coupling model of the powertrain mounting system, an optimization algorithm is used to extract the best design parameters of each mount, thus rendering the mounting system fully decoupled and the natural frequency well configured, and the optimal parameters are used to design the mounting system. Subsequently, vibration simulation analysis is applied to the mounting system, considering both transmission and road excitations. According to the results of finite element analysis, the topological structure of the metal frame of the front mount is optimized to improve the strength and dynamic characteristics of the mounting system. Finally, the vibration bench test is used to verify the availability of the optimization design with the analysis of acceleration response and vibration transmissibility of the mounting system. The results show that the vibration isolation performance of the mounting system can be improved effectively using the vibration optimal decoupling method, and the structural modification of the metal frame can well promote the dynamic characteristics of the mounting system.
文摘The characteristics of vibrational power flow in an infinite elastic cylindrical shell filled with fluid are investigated. The simple harmonic motion of the shell and the pressure field in the contained fluid are described by the Fltigge shell equations and Helmholtz equation respectively. The vibrational equation of this system is obtained by using the coupling of shell and fluid. The dispersion curves are discussed for different circumferential orders. By using Fourier transform and its inverse transform, the input power into this coupled system excited by a simple harmonic linearly distributed driving force is studied. Along the shell, the transmission of the power flow carried by different shell internal forces and by the contained fluid are
基金supported by the National Key Research and Development Project(No.2022YFA1503000)the National Natural Science Foundation of China(Nos.22161142021 and 22175010).
文摘Polymer composite fibers with superior properties such as excellent combined strength and toughness and biocompatibility can be used in high-tech applications of braided protective devices and smart wearable,however the research of high-performance polymer composite fiber remains in the infant stage.Here we present a strategy to produce strong and tough anisotropic polymer nanocomposite fibers with orientedly aligned salt rods using mechanical stretching-assisted salting-out treatment.The prepared nanocomposite fibers have a tensile strength of up to 786±2.7 MPa and an elongation at break of 81%,and the anisotropic fibers exhibit good transmission of mechanical vibration in the longitudinal direction with high resolution.During the fabrication process,the salt builds up into oriented rods during the directional salting process,and the polymer is confined to the 150 nm domain between the rods after the solvent is completely evaporated,giving the nanocomposite fibers superior mechanical properties.The presented strategy can be applied to the continuous mass production of nanocomposite fibers and is also generalizable to other polymer nanocomposites,which could extend the applicability of nanocomposite fibers to conditions involving more demanding mechanical loading and mechanical vibration transmission.
基金financially supported by the National Natural Science Foundation of China(Grant No.51475433,51175476)the Research Fund for the Doctoral Program of Higher Education of China(RFDP)(Grant No.20113318110001)+1 种基金the Program for Scientific Research Innovation Team of Zhejiang Sci-Tech University(Grant No.13020049-Y)the 521 Talent Plan of Zhejiang Sci-Tech University.
文摘Mechanical vibration is an effective fruit harvesting method.To evaluate the dynamic characteristics of dwarf Chinese hickory(Carya cathayensis Sarg.)trees and the influence of the tree structure on transmission and attenuation of dynamic response,a new method was proposed based on acceleration admittance measurement on dwarf Chinese hickory trees in orchard environment under impact excitation.The primary resonance frequencies of the tree can be determined based on the acceleration admittance measurement.The effect of the tree structure on the vibratory transmission was quantified using the attenuation ratio of the acceleration admittance.A 5-year-old dwarf Chinese hickory tree sample was tested.The responses at three resonance frequencies(5,9 and 12 Hz)were analyzed because they were identified as the most effective bands of excitation for the main part of the tree specimen.The results reveal that the variation of the dynamic response along the testing tree is greatly related to the Chinese hickory tree structure.The attenuation ratio of the acceleration admittance at the branch crotches indicates the leader top crotch may amplify the acceleration admittance no matter what the crotch angle and the branch diameter is.Unlike the crotches,the branch chain nodes generally have negative influence on the acceleration admittance along the branch chains which heavily depend on the branch chain configuration.The branch chains with a chain angle no less than 150°and a wood diameter ratio close to 1.0 could produce little influence on the vibration transmission.For those branches with chain angle less than 150°,the vibration was generally attenuated at their chain nodes at three resonance frequencies.To impose impact excitations on the tree,high mechanical harvesting efficiency could be achieved on those branch chains which are almost straight and uniform.
