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Numerical analysis of vehicle-bridge coupling vibration concerning nonlinear stress-dependent damping

Pengfei LI; Jinquan ZHANG; Shengqi MEI; Zhenhua DONG; Yan MAO

《结构与土木工程前沿（英文）》 2022年 第16卷 第2期   页码 239-249 doi: 10.1007/s11709-021-0804-y

摘要： Damping is known to have a considerable influence on the dynamic behavior of bridges. The fixed damping ratios recommended in design codes do not necessarily represent the complicated damping characteristics of bridge structures. This study investigated the application of stress-dependent damping associated with vehicle-bridge coupling vibration and based on that investigation proposed the stress-dependent damping ratio. The results of the investigation show that the stress-dependent damping ratio is significantly different from the constant damping ratio (5%) defined in the standard specification. When vehicles travel at speeds of 30, 60, and 90, the damping ratios of the bridge model are 3.656%, 3.658%, and 3.671%, respectively. The peak accelerations using the regular damping ratio are 18.9%, 21.3%, and 14.5% of the stress-dependent damping ratio, respectively. When the vehicle load on the bridge is doubled, the peak acceleration of the mid-span node increases by 5.4 times, and the stress-related damping ratio increases by 2.1%. A corrugated steel-web bridge is being used as a case study, and the vibration response of the bridge is compared with the measured results. The acceleration response of the bridge which was calculated using the stress-dependent damping ratio is significantly closer to the measured acceleration response than that using the regular damping ratio.

关键词： vehicle-bridge vibration system     dynamic analysis     stress-dependent damping     energy dissipation    

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Stability and coupling dynamic behavior of nonlinear journal active electromagnetic bearing rotor system

LU Yanjun, HEI Di, WANG Yuan, DAI Rong, LU Yanjun, LIU Heng, YU Lie

《机械工程前沿（英文）》 2008年 第3卷 第2期   页码 193-199 doi: 10.1007/s11465-008-0023-4

摘要： The stability and coupling dynamic behavior of a journal active electromagnetic bearing rotor system are analyzed. The gyroscopic effect is considered in the rotor model. The system equations are formulated by combining equations for rotor motion and decentralized proportional integral differential (PID) controllers. A method combining the predictor-corrector mechanism and the Netwon-Raphson method is presented to calculate the critical speed at the corresponding Hopf bifurcation point of the system. For periodic motions, a continuation method combining the predictor-corrector mechanism and shooting method is presented. Nonlinear unbalanced periodic motions and their stability margins are obtained using the shooting method and established continuation method for periodic motions. With the change of control parameters, the system local stability and bifurcation behaviors are obtained using the Floquet theory. The numerical examples show that the schemes not only significantly save computing cost, but also have high precision.

关键词： proportional integral     bifurcation     corresponding     integral differential     predictor-corrector mechanism    

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Computation and investigation of mode characteristics in nonlinear system with tuned/mistuned contact

Houxin SHE, Chaofeng LI, Qiansheng TANG, Hui MA, Bangchun WEN

《机械工程前沿（英文）》 2020年 第15卷 第1期   页码 133-150 doi: 10.1007/s11465-019-0557-7

摘要： This study derived a novel computation algorithm for a mechanical system with multiple friction contact interfaces that is well-suited to the investigation of nonlinear mode characteristic of a coupling system. The procedure uses the incremental harmonic balance method to obtain the nonlinear parameters of the contact interface. Thereafter, the computed nonlinear parameters are applied to rebuild the matrices of the coupling system, which can be easily solved to calculate the nonlinear mode characteristics by standard iterative solvers. Lastly, the derived method is applied to a cycle symmetry system, which represents a shaft–disk–blade system subjected to dry friction. Moreover, this study analyzed the effects of the tuned and mistuned contact features on the nonlinear mode characteristics. Numerical results prove that the proposed method is particularly suitable for the study of nonlinear characteristics in such nonlinear systems.

关键词： coupling vibration     nonlinear mode     original algorithm     contact interface    

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An operating state estimation model for integrated energy systems based on distributed solution

Dengji ZHOU, Shixi MA, Dawen HUANG, Huisheng ZHANG, Shilie WENG

《能源前沿（英文）》 2020年 第14卷 第4期   页码 801-816 doi: 10.1007/s11708-020-0687-y

摘要： In view of the disadvantages of the traditional energy supply systems, such as separate planning, separate design, independent operating mode, and the increasingly prominent nonlinear coupling between various sub-systems, the production, transmission, storage and consumption of multiple energy sources are coordinated and optimized by the integrated energy system, which improves energy and infrastructure utilization, promotes renewable energy consumption, and ensures reliability of energy supply. In this paper, the mathematical model of the electricity-gas interconnected integrated energy system and its state estimation method are studied. First, considering the nonlinearity between measurement equations and state variables, a performance simulation model is proposed. Then, the state consistency equations and constraints of the coupling nodes for multiple energy sub-systems are established, and constraints are relaxed into the objective function to decouple the integrated energy system. Finally, a distributed state estimation framework is formed by combining the synchronous alternating direction multiplier method to achieve an efficient estimation of the state of the integrated energy system. A simulation model of an electricity-gas interconnected integrated energy system verifies the efficiency and accuracy of the state estimation method proposed in this paper. The results show that the average relative errors of voltage amplitude and node pressure estimated by the proposed distributed state estimation method are only 0.0132% and 0.0864%, much lower than the estimation error by using the Lagrangian relaxation method. Besides, compared with the centralized estimation method, the proposed distributed method saves 5.42 s of computation time. The proposed method is more accurate and efficient in energy allocation and utilization.

关键词： integrated energy system     state estimation     electricity-gas coupling energy system     nonlinear coupling     distributed solution    

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Microdamage study of granite under thermomechanical coupling based on the particle flow code

《结构与土木工程前沿（英文）》   页码 1413-1427 doi: 10.1007/s11709-023-0953-2

摘要： The thermomechanical coupling of rocks refers to the interaction between the mechanical and thermodynamic behaviors of rocks induced by temperature changes. The study of this coupling interaction is essential for understanding the mechanical and thermodynamic properties of the surrounding rocks in underground engineering. In this study, an improved temperature-dependent linear parallel bond model is introduced under the framework of a particle flow simulation. A series of numerical thermomechanical coupling tests are then conducted to calibrate the micro-parameters of the proposed model by considering the mechanical behavior of the rock under different thermomechanical loadings. Good agreement between the numerical results and experimental data are obtained, particularly in terms of the compression, tension, and elastic responses of granite. With this improved model, the thermodynamic response and underlying cracking behavior of a deep-buried tunnel under different thermal loading conditions are investigated and discussed in detail.

关键词： thermomechanical coupling effect     granite     improved linear parallel bond model     thermal property     particle flow code    

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Simulation of steel beam under ceiling jet based on a wind–fire–structure coupling model

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 78-98 doi: 10.1007/s11709-022-0936-8

摘要： For localized fires, it is necessary to consider the thermal and mechanical responses of building elements subject to uneven heating under the influence of wind. In this paper, the thermomechanical phenomena experienced by a ceiling jet and I-beam in a structural fire were simulated. Instead of applying the concept of adiabatic surface temperature (AST) to achieve fluid–structure coupling, this paper proposes a new computational fluid dynamics–finite element method numerical simulation that combines wind, fire, thermal, and structural analyses. First, to analyze the velocity and temperature distributions, the results of the numerical model and experiment were compared in windless conditions, showing good agreement. Vortices were found in the local area formed by the upper and lower flanges of the I-beam and the web, generating a local high-temperature zone and enhancing the heat transfer of convection. In an incoming-flow scenario, the flame was blown askew significantly; the wall temperature was bimodally distributed in the axial direction. The first temperature peak was mainly caused by radiative heat transfer, while the second resulted from convective heat transfer. In terms of mechanical response, the yield strength degradation in the highest-temperature region in windless conditions was found to be significant, thus explaining the stress distribution of steel beams in the fire field. The mechanical response of the overall elements considering the incoming flows was essentially elastic.

关键词： CFD–FEM coupling     steel beam     wind     ceiling jet     numerical heat transfer    

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catalysts derived from zeolitic imidazolate framework@MXene composites for efficient oxidative self-coupling

《化学科学与工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11705-023-2378-9

摘要： In this study, we synthesize a catalyst comprising cobalt nanoparticles supported on MXene by pyrolyzing a composite in a N2 environment. Specifically, the composite comprises a bimetallic Zn/Co zeolitic imidazole framework grown in situ on the outer surface of MXene. The catalytic efficiency of the catalyst is tested for the self-coupling of 4-methoxybenzylamine to produce value-added imine, where atmospheric oxygen (1 atm) is used as the oxidant. Based on the results, the catalyst displayed impressive catalytic activity, achieving 95.4% yield of the desired imine at 383 K for 8 h. Furthermore, the catalyst showed recyclability and tolerance toward benzylamine substrates with various functional groups. The outstanding performance of the catalyst is primarily attributed to the synergetic catalytic effect between the cobalt nanoparticles and MXene support, while also benefiting from the three-dimensional porous structure. Additionally, a preliminary investigation of potential reaction mechanisms is conducted.

关键词： MXene     sacrificial template     oxidative self-coupling     Co nanoparticles     imine    

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Effect of alkyl nitrite decomposition on catalytic performance of CO coupling reaction over supported

Zhenhua LI, Weihan WANG, Dongxue YIN, Jing LV, Xinbin MA

《化学科学与工程前沿（英文）》 2012年 第6卷 第4期   页码 410-414 doi: 10.1007/s11705-012-1213-5

摘要： The syntheses of dimethyl oxalate (DMO) and diethyl oxalate (DEO) by CO coupling reaction in gaseous phase were investigated in a fixed bed reactor over Pd-Fe/Al O catalyst. The catalytic performance was characterized by CO conversion, space-time yield (STY) and selectivity of DMO (or DEO). The results showed that over Pd-Fe/Al O catalyst, the STY of DMO was higher than that of DEO under the same reaction conditions. The optimum reaction temperatures for synthesizing DMO and DEO were 403 K and 393 K, respectively, at the molar ratio 1 ∶ 1 of alkyl nitrite to CO. The difference in synthesizing DMO and DEO on the same catalyst was attributed to the decomposition performances of methyl nitrite (MN) and ethyl nitrite (EN), as density functional theory (DFT) calculation showed that EN decomposed more easily than MN.

关键词： palladium     CO coupling     dialkyl oxalate     alkyl nitrite     decomposition    

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Thermodynamic and economic analyses of a coal and biomass indirect coupling power generation system

Buqing YE, Rui ZHANG, Jin CAO, Bingquan SHI, Xun ZHOU, Dong LIU

《能源前沿（英文）》 2020年 第14卷 第3期   页码 590-606 doi: 10.1007/s11708-020-0809-6

摘要： The coal and biomass coupling power generation technology is considered as a promising technology for energy conservation and emission reduction. In this paper, a novel coal and biomass indirect coupling system is proposed based on the technology of biomass gasification and co-combustion of coal and gasification gas. For the sake of comparison, a coal and biomass direct coupling system is also introduced based on the technology of co-combustion of coal and biomass. The process of the direct and the indirect coupling system is simulated. The thermodynamic and economic performances of two systems are analyzed and compared. The simulation indicates that the thermodynamic performance of the indirect coupling system is slightly worse, but the economic performance is better than that of the direct coupling system. When the blending ratio of biomass is 20%, the energy and exergy efficiencies of the indirect coupling system are 42.70% and 41.14%, the internal rate of return (IRR) and discounted payback period (DPP) of the system are 25.68% and 8.56 years. The price fluctuation of fuels and products has a great influence on the economic performance of the indirect coupling system. The environmental impact analysis indicates that the indirect coupling system can inhibit the propagation of NO and reduce the environmental cost.

关键词： biomass     indirect coupling system     process simulation     thermodynamic analysis     economic analysis    

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Enhancing the aromatic selectivity of cyclohexane aromatization by CO2 coupling

《化学科学与工程前沿（英文）》 2023年 第17卷 第11期   页码 1801-1808 doi: 10.1007/s11705-023-2325-9

摘要： Improving the aromatic selectivity in the alkane aromatization process is of great importance for its practical utilization but challenge to make because the high H/C ratio of alkanes would lead to a serious hydrogen transfer process and a large amount of light alkanes. Herein, CO2 is introduced into the cyclohexane conversion process on the HZSM-5 zeolite, which can improve the aromatic selectivity. By optimizing the reaction conditions, an improved aromatic (benzene, toluene, xylene, and C9+) selectivity of 48.2% can be obtained at the conditions of 2.7 MPa (CO2), 450 °C, and 1.7 h−1, which is better than that without CO2 (aromatic selectivity = 43.2%). In situ transmission Fourier transform infrared spectroscopy spectra illustrate that many oxygenated chemical intermediates (e.g., carboxylic acid, anhydride, unsaturated aldehydes/ketones or ketene) would be formed during the cyclohexane conversion process in the presence of CO2. 13C isotope labeling experimental results demonstrate that CO2 can enter into the aromatics through the formation of oxygenated chemical intermediates and thereby improve the aromatic selectivity. This study may open a green, economic, and promising way to improve the aromatic selectivity for alkane aromatization process.

关键词： aromatics     carbon dioxide     aromatization     coupling reaction     ZSM-5 zeolite    

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New nonlinear stiffness actuator with predefined torque‒deflection profile

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0721-3

摘要： A nonlinear stiffness actuator (NSA) could achieve high torque/force resolution in low stiffness range and high bandwidth in high stiffness range, both of which are beneficial for physical interaction between a robot and the environment. Currently, most of NSAs are complex and hardly used for engineering. In this paper, oriented to engineering applications, a new simple NSA was proposed, mainly including leaf springs and especially designed cams, which could perform a predefined relationship between torque and deflection. The new NSA has a compact structure, and it is lightweight, both of which are also beneficial for its practical application. An analytical methodology that maps the predefined relationship between torque and deflection to the profile of the cam was developed. The optimal parameters of the structure were given by analyzing the weight of the NSA and the mechanic characteristic of the leaf spring. Though sliding friction force is inevitable because no rollers were used in the cam-based mechanism, the sliding displacement between the cam and the leaf spring is very small, and consumption of sliding friction force is very low. Simulations of different torque‒deflection profiles were carried out to verify the accuracy and applicability of performing predefined torque‒deflection profiles. Three kinds of prototype experiments, including verification experiment of the predefined torque‒deflection profile, torque tracking experiment, and position tracking experiment under different loads, were conducted. The results prove the accuracy of performing the predefined torque‒deflection profile, the tracking performance, and the interactive performance of the new NSA.

关键词： compliant actuator     nonlinear stiffness actuator     nonlinear spring     predefined torque−deflection profile    

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Mild and highly regioselective synthesis of biaryl acids via Rh(I)-catalyzed cross-dehydrogenative coupling

Yun Liu, Youquan Zhu, Chaojun Li

《化学科学与工程前沿（英文）》 2018年 第12卷 第1期   页码 3-8 doi: 10.1007/s11705-017-1693-4

摘要： A mild and efficient synthesis for the biaryl acids via rhodium-catalyzed cross-dehydrogenative coupling reaction has been developed. This novel protocol with sodium chlorite as an oxidant featured many advantages such as mild reaction conditions, high regioselectivity, tolerance of various functional groups, and good to excellent yields.

关键词： biaryl acids     cross-dehydrogenative coupling     rhodium-catalyzed    

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Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 605-617 doi: 10.1007/s11709-018-0499-x

摘要： Mean wind response induced incompatibility and nonlinearity in bridge aerodynamics is discussed, where the mean wind and aeroelastic loads are applied simultaneously in time domain. A kind of incompatibility is found during the simultaneous simulation of the mean wind and aeroelastic loads, which leads to incorrect mean wind structural responses. It is found that the mathematic expectations (or limiting characteristics) of the aeroelastic models are fundamental to this kind of incompatibility. In this paper, two aeroelastic models are presented and discussed, one of indicial-function-denoted (IF-denoted) and another of rational-function-denoted (RF-denoted). It is shown that, in cases of low wind speeds, the IF-denoted model reflects correctly the mean wind load properties, and results in correct mean structural responses; in contrast, the RF-denoted model leads to incorrect mean responses due to its nonphysical mean properties. At very high wind speeds, however, even the IF-denoted model can lead to significant deviation from the correct response due to steady aerodynamic nonlinearity. To solve the incompatibility at high wind speeds, a methodology of subtraction of pseudo-steady effects from the aeroelastic model is put forward in this work. Finally, with the method presented, aeroelastic nonlinearity resulted from the mean wind response is investigated at both moderate and high wind speeds.

关键词： bridge     aerodynamics     nonlinear     aeroelastic model     Pseudo-steady     mean wind loads    

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General expression for linear and nonlinear time series models

Ren HUANG, Feiyun XU, Ruwen CHEN

《机械工程前沿（英文）》 2009年 第4卷 第1期   页码 15-24 doi: 10.1007/s11465-009-0015-z

摘要： The typical time series models such as ARMA, AR, and MA are founded on the normality and stationarity of a system and expressed by a linear difference equation; therefore, they are strictly limited to the linear system. However, some nonlinear factors are within the practical system; thus, it is difficult to fit the model for real systems with the above models. This paper proposes a general expression for linear and nonlinear auto-regressive time series models (GNAR). With the gradient optimization method and modified AIC information criteria integrated with the prediction error, the parameter estimation and order determination are achieved. The model simulation and experiments show that the GNAR model can accurately approximate to the dynamic characteristics of the most nonlinear models applied in academics and engineering. The modeling and prediction accuracy of the GNAR model is superior to the classical time series models. The proposed GNAR model is flexible and effective.

关键词： linear and nonlinear     autoregressive model     system identification     time series analysis    

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Evaluation of transmissibility for a class of nonlinear passive vibration isolators

Z. K. PENG, Z. Q. LANG, G. MENG

《机械工程前沿（英文）》 2012年 第7卷 第4期   页码 401-409 doi: 10.1007/s11465-012-0349-9

摘要：

In this study, the concept of Output Frequency Response Functions (OFRFs) is applied to represent the transmissibility of nonlinear isolators in frequency domain. With the OFRFs estimated from numerical simulation responses, an explicit analytical relationship between the transmissibility and the nonlinear characteristic parameters is derived for a wide class of nonlinear isolators that have nonlinear anti-symmetric damping characteristics and a comprehensive pattern about how the nonlinear damping characteristic parameters might affect the force and displacement transmissibility is built for the vibration isolators. The results reveal that it is reasonable to analyze the force and displacement transmissibility of the nonlinear isolators by simply investigating the fundamental harmonic components of the force and displacement outputs of the nonlinear isolators, and the introduction of a nonlinear anti-symmetric damping into vibration isolators can significantly suppress both the force and displacement transmissibility over the resonant frequency region, but has almost no effect on the transmissibility at non-resonant regions. These conclusions are of significant importance in the analysis and design of the nonlinear vibration isolators with nonlinear anti-symmetric damping.

关键词： nonlinear vibration     volterra series     Output Frequency Response Functions (OFRFs)     nonlinear damping     vibration isolator    

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标题 作者 时间 类型 操作

Numerical analysis of vehicle-bridge coupling vibration concerning nonlinear stress-dependent damping

Pengfei LI; Jinquan ZHANG; Shengqi MEI; Zhenhua DONG; Yan MAO

期刊论文

Stability and coupling dynamic behavior of nonlinear journal active electromagnetic bearing rotor system

LU Yanjun, HEI Di, WANG Yuan, DAI Rong, LU Yanjun, LIU Heng, YU Lie

期刊论文

Computation and investigation of mode characteristics in nonlinear system with tuned/mistuned contact

Houxin SHE, Chaofeng LI, Qiansheng TANG, Hui MA, Bangchun WEN

期刊论文

An operating state estimation model for integrated energy systems based on distributed solution

Dengji ZHOU, Shixi MA, Dawen HUANG, Huisheng ZHANG, Shilie WENG

期刊论文

Microdamage study of granite under thermomechanical coupling based on the particle flow code

期刊论文

Simulation of steel beam under ceiling jet based on a wind–fire–structure coupling model

期刊论文

catalysts derived from zeolitic imidazolate framework@MXene composites for efficient oxidative self-coupling

期刊论文

Effect of alkyl nitrite decomposition on catalytic performance of CO coupling reaction over supported

Zhenhua LI, Weihan WANG, Dongxue YIN, Jing LV, Xinbin MA

期刊论文

Thermodynamic and economic analyses of a coal and biomass indirect coupling power generation system

Buqing YE, Rui ZHANG, Jin CAO, Bingquan SHI, Xun ZHOU, Dong LIU

期刊论文

Enhancing the aromatic selectivity of cyclohexane aromatization by CO2 coupling

期刊论文

New nonlinear stiffness actuator with predefined torque‒deflection profile

期刊论文

Mild and highly regioselective synthesis of biaryl acids via Rh(I)-catalyzed cross-dehydrogenative coupling

Yun Liu, Youquan Zhu, Chaojun Li

期刊论文

Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

期刊论文

General expression for linear and nonlinear time series models

Ren HUANG, Feiyun XU, Ruwen CHEN

期刊论文

Evaluation of transmissibility for a class of nonlinear passive vibration isolators

Z. K. PENG, Z. Q. LANG, G. MENG

期刊论文