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Flutter control effect and mechanism of central-slotting for long-span bridges

YANG Yongxin, GE Yaojun, XIANG Haifan

《结构与土木工程前沿（英文）》 2007年第1卷第3期页码 298-304 doi: 10.1007/s11709-007-0039-6

摘要： The flutter control effect and mechanism of central-slotting, which have gradually been adopted in the design and construction of long-span bridges as an effective flutter controlling measure, were investigated with theoretical analysis and wind tunnel test. Five basic girder cross-sections representing five typical aerodynamic configurations were selected and central-slotted with two different slot widths. Then, a series of sectional model tests and theoretical analyses based on the two-dimensional three-degrees-of-freedom coupling flutter analysis method (2 dimension-3 degrees of freedom method, 2d-3DOF method) were carried out to investigate the aerodynamic performance, flutter mechanism and flutter modality of the five basic sections and their corresponding central-slotted sections. The results show that central-slotting can not always improve the aerodynamic stability of bridge structure. The control effect of central-slotting depends on the aerodynamic configuration of the original girder section and the corresponding central-slotting width. If the original section is inappropriate or the slot width is unsuitable, central-slotting will even deteriorate the structural flutter performance. Theoretical investigations indicated that the differences in flutter control effects come from the different formation and evolution of aerodynamic damping, and flutter modality especially the participation level of heaving motion also has a significant influence on the control effect of central-slotting.

关键词： aerodynamic configuration aerodynamic performance flutter mechanism aerodynamic stability theoretical analysis

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Comparisons of bridges flutter derivatives and generalized ones

Fuyou XU , Zhe ZHANG , Cailiang HUANG , Airong CHEN ,

《结构与土木工程前沿（英文）》 2009年第3卷第3期页码 272-278 doi: 10.1007/s11709-009-0042-1

摘要： The causes of the nonlinearity of self-excited aerodynamic force of bridge are interpreted from such two aspects as amplitude and wind velocity. The concept of “generalized flutter derivative” is proposed, and its physical meaning is illustrated. The graphs of the generalized flutter derivatives of plate and Sutong Bridge section model are plotted. The characteristics of all generalized flutter derivatives are compared and analyzed, and their superiorities are verified. The results indicate that the physical meaning of generalized flutter derivatives are more explicit compared to the traditional ones. It is more convenient to understand the nonlinearity properties of self-excited aerodynamic force of bridge according to the generalized flutter derivatives graphs with the wind velocity as the horizontal coordinate.

关键词： bridge flutter derivative generalized flutter derivative self-excited aerodynamic force Sutong Bridge

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Time-domain and frequency-domain approaches to identification of bridge flutter derivatives

Zhengqing CHEN

《结构与土木工程前沿（英文）》 2009年第3卷第2期页码 173-179 doi: 10.1007/s11709-009-0034-1

摘要： Flutter derivatives are essential for flutter analysis of long-span bridges, and they are generally identified from the vibration testing data of a sectional model suspended in a wind tunnel. Making use of the forced vibration testing data of three sectional models, namely, a thin-plate model, a nearly streamlined model, and a bluff-body model, a comparative study was made to identify the flutter derivatives of each model by using a time-domain method and a frequency-domain method. It was shown that all the flutter derivatives of the thin-plate model identified with the frequency-domain method and time-domain method, respectively, agree very well. Moreover, some of the flutter derivatives of each of the other two models identified with the two methods deviate to some extent. More precisely, the frequency-domain method usually results in smooth curves of the flutter derivatives. The formulation of time-domain method makes the identification results of flutter derivatives relatively sensitive to the signal phase lag between vibration state vector and aerodynamic forces and also prone to be disturbed by noise and nonlinearity.

关键词： long-span bridges wind-induced vibration flutter derivatives forced vibration test time-domain method frequency-domain method

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泰州大桥主梁施工阶段的颤振稳定性及管理对策

李承宬,陈艾荣,马如进

《中国工程科学》 2012年第14卷第5期页码 46-50

摘要：

以三塔两跨的泰州大桥为研究对象，根据有限元分析及全桥气弹模型风洞试验的结果，对主梁对称架设施工阶段的动力特性及颤振稳定性进行了研究。结合桥位地区30年的月极大风速分析，对主梁架设阶段的颤振稳定性进行了评价。最后提出了一套针对悬索桥施工阶段颤振稳定性评价及策略确定的流程，可供其他桥梁参考。

关键词：多塔悬索桥施工阶段颤振稳定性管理对策

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efficiency optimization and Sobol’s sensitivity indices of MTMDs design parameters for buffeting and flutter

Nazim Abdul NARIMAN

《结构与土木工程前沿（英文）》 2017年第11卷第1期页码 66-89 doi: 10.1007/s11709-016-0356-8

摘要： This paper studies optimization of three design parameters (mass ratio, frequency ratio and damping ratio) of multiple tuned mass dampers MTMDs that are applied in a cable stayed bridge excited by a strong wind using minimax optimization technique. ABAQUS finite element program is utilized to run numerical simulations with the support of MATLAB codes and Fast Fourier Transform FFT technique. The optimum values of these three parameters are validated with two benchmarks from the literature, first with Wang and coauthors and then with Lin and coauthors. The validation procedure detected a good agreement between the results. Box-Behnken experimental method is dedicated to formulate the surrogate models to represent the control efficiency of the vertical and torsional vibrations. Sobol’s sensitivity indices are calculated for the design parameters in addition to their interaction orders. The optimization results revealed better performance of the MTMDs in controlling the vertical and the torsional vibrations for higher mode shapes. Furthermore, the calculated rational effects of each design parameter facilitate to increase the control efficiency of the MTMDs in conjunction with the support of the surrogate models.

关键词： MTMDs power spectral density fast Fourier transform minimax optimization technique Sobol’s sensitivity indices Box-Behnken method

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Computational fluid dynamic analysis of flutter characteristics for self-anchored suspension bridges

ZHU Zhiwen, WANG Zhaoxiang, CHEN Zhengqing

《结构与土木工程前沿（英文）》 2008年第2卷第3期页码 267-273 doi: 10.1007/s11709-008-0034-6

摘要： This paper outlines the essentials and procedures of computational fluid dynamics (CFD) simulation applicable to evaluating flutter derivatives of bridge decks. An arbitrary Lagrangian-Eulerian (ALE) description of the flow around the moving rigid box girder combined with the finite volume discretization and multi-grid algorithm is presented. The proposed methods are employed to identify flutter derivatives of the bridge deck of the Sanchaji Self-anchored Suspension Bridge. The results agree well with ones from wind tunnel tests. It demonstrates accuracy and efficiency of the present method.

关键词： discretization computational description Self-anchored Suspension simulation applicable

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基于气动模型的大跨度桥梁抖振与颤振的比较评估

Igor Kavrakov, Guido Morgenthal

《工程（英文）》 2017年第3卷第6期页码 823-838 doi: 10.1016/j.eng.2017.11.008

摘要：

风致振动通常代表了大跨度桥梁设计的主要标准。桥梁空气动力学中的气动力主要基于准定常和线性非定常理论。本文旨在通过比较多跨斜拉桥在临界架设条件下的动力响应，进而推演出不同时域自激力与抖振力的表达式。这类混凝土箱梁桥是用于大型河流交叉口的典型参考对象。本文从模型复杂性的角度进行分析，对比了气动模型中隐含的气动参数，如气动阻尼和气动刚度、抖振力和自激力中的流体记忆、气动非线性和气动耦合等对桥梁响应的影响。选定的模型用于研究一定风速范围内的结果，该风速范围对于考虑两种湍流度情况的施工过程是典型范围。此外，还提出了一种计算包括气动导纳在内的抖振力的简化方法，避免了有理逼近。在层流流动下，也将对根据所选模型计算得到的临界颤振风速进行对比。

关键词：抖振颤振大跨度桥梁桥梁空气动力学桥梁气动弹性架设阶段

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A novel structural modification to eliminate the early coupling between bending and torsional mode shapes in a cable stayed bridge

Nazim Abdul NARIMAN

《结构与土木工程前沿（英文）》 2017年第11卷第2期页码 131-142 doi: 10.1007/s11709-016-0376-4

摘要： In this paper, a novel structural modification approach has been adopted to eliminate the early coupling between the bending and torsional mode shapes of vibrations for a cable stayed bridge model generated using ABAQUS software. Two lateral steel beams are added to the middle span of the structure. Frequency analysis is dedicated to obtain the natural frequencies of the first eight mode shapes of vibrations before and after the structural modification approach. Numerical simulations of wind excitations are conducted for the 3D model of the cable stayed bridge with duration of 30 s supporting on real data of a strong wind from the literature. Both vertical and torsional displacements are calculated at the mid span of the deck to analyze both the bending and the torsional stiffness of the system before and after the structural modification. The results of the frequency analysis after applying lateral steel beams declared a safer structure against vertical and torsional vibrations and rarely expected flutter wind speed. Furthermore, the coupling between the vertical and torsional mode shapes has been removed to larger natural frequencies magnitudes with a high factor of safety. The novel structural approach manifested great efficiency in increasing vertical and torsional stiffness of the structure.

关键词： aeroelastic instability structural damping flutter wind speed bending stiffness torsional stiffness

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湍流效应对桁架式桥梁断面气动弹性性能影响的研究

Hoang Trong Lam, Hiroshi Katsuchi, Hitoshi Yamada

《工程（英文）》 2017年第3卷第6期页码 845-853 doi: 10.1016/j.eng.2017.10.001

摘要：

本文介绍了在不同湍流条件下通过随机系统识别（SSI）方法提取颤振导数（FD）的过程。研究旨在通过对节段模型风洞试验来研究湍流对悬索式大跨度桥梁的影响。针对不同的湍流特性，对桁架式桥梁断面进行了几项风洞试验，包括降低湍流强度和湍流尺度。研究包括湍流对模型动态响应的影响。利用系统识别技术提取FD，对风洞试验中的瞬态响应和抖振响应进行了分析，同时讨论了该方法存在的困难。利用时域SSI 同时从一自由度（1DOF）和二自由度（2DOF）系统提取所有的FD。最后，讨论了不同情况下的结果并得出结论。

关键词：颤振导数系统识别湍流效应抖振响应

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大跨度桥梁抗风技术挑战与基础研究

项海帆,葛耀君

《中国工程科学》 2011年第13卷第9期页码 8-21

摘要：

以我国30年大跨度桥梁的快速发展为研究背景，对3种大跨度桥梁的抗风技术挑战进行了基础性研究和应用性研究，着重探讨了悬索桥的颤振性能及其控制、斜拉桥风振性能与拉索风雨振控制、拱式桥涡激共振及其控制、特大桥梁风振精细化理论等一系列抗风关键问题。研究结果表明：悬索桥的颤振稳定性跨径上限约为1 500 m，超过甚至接近这一上限时，必须采取措施改善加劲梁的抗风稳定性；千米级大跨度斜拉桥仍具有足够高的颤振临界风速，其主要抗风问题是长拉索的风雨振动；大跨径拱桥除了个别有涡振问题之外，还没有受到结构抗风性能的影响。文章还提出了三维桥梁颤振精确分析的全模态方法、任意斜风作用下桥梁抖振频域分析方法、基于二阶矩理论和首次超越理论的桥梁颤振和抖振可靠性评价方法，揭示了桥梁颤振演化规律、驱动机理和控制原理。

关键词：悬索桥斜拉桥拱桥颤振抖振涡振

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Theory and method of mechanism system design

Huijun ZOU, Qinghua LIANG, Qing ZHANG

《机械工程前沿（英文）》 2010年第5卷第4期页码 399-411 doi: 10.1007/s11465-010-0116-8

摘要： Conceptual design is the most critical and creative phase of design. Recently, increasing attention has been directed to supporting conceptual-level computer aided creative design and its theories and methodologies. Specifically, for conceptual design of mechanical products, this paper presents a novel function solving model for mechanical product design and highlights the importance of systematic synthesis to achieve creative design. Then it builds a framework as a function-effect-process-action- mechanisms (FEPAM) mapping process, which enables creative design on the basis of conceiving different action schemes. After that, several key points are elaborated including 1) representing and decomposition methods of functions and motion behaviors; 2) action scheme representing method based on network plan techniques; and 3) variation and creation methods based on action scheme transformations.

关键词： mechanism system creative design process model function solving model process action procedure mechanisms knowledge base principle of mechanism system composition

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Formation mechanism and modeling of surface waviness in incremental sheet forming

《机械工程前沿（英文）》 2022年第17卷第2期 doi: 10.1007/s11465-022-0679-1

摘要： Improving and controlling surface quality has always been a challenge for incremental sheet forming (ISF), whereas the generation mechanism of waviness surface is still unknown, which impedes the widely application of ISF in the industrial field. In this paper, the formation mechanism and the prediction of waviness are both investigated through experiments, numerical simulation, and theoretical analysis. Based on a verified finite element model, the waviness topography is predicted numerically for the first time, and its generation is attributed to the residual bending deformation through deformation history analysis. For more efficient engineering application, a theoretical model for waviness height is proposed based on the generation mechanism, using a modified strain function considering deformation modes. This work is favorable for the perfection of formation mechanism and control of surface quality in ISF.

关键词： surface waviness incremental sheet forming numerical simulation formation mechanism deformation history

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Autogenous healing mechanism of cement-based materials

《结构与土木工程前沿（英文）》页码 948-963 doi: 10.1007/s11709-023-0960-3

摘要： Autogenous self-healing is the innate and fundamental repair capability of cement-based materials for healing cracks. Many researchers have investigated factors that influence autogenous healing. However, systematic research on the autogenous healing mechanism of cement-based materials is lacking. The healing process mainly involves a chemical process, including further hydration of unhydrated cement and carbonation of calcium oxide and calcium hydroxide. Hence, the autogenous healing process is influenced by the material constituents of the cement composite and the ambient environment. In this study, different factors influencing the healing process of cement-based materials were investigated. Scanning electron microscopy and optical microscopy were used to examine the autogenous healing mechanism, and the maximum healing capacity was assessed. Furthermore, detailed theoretical analysis and quantitative detection of autogenous healing were conducted. This study provides a valuable reference for developing an improved healing technique for cement-based composites.

关键词： autogenous healing cement-based materials healing mechanism aggregation effect

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Optimal design of a linkage–cam mechanism-based redundantly actuated parallel manipulator

《机械工程前沿（英文）》 2021年第16卷第3期页码 451-467 doi: 10.1007/s11465-021-0634-6

摘要： A redundantly actuated parallel manipulator (RAPM) with mixed translational and rotational degrees of freedom (DOFs) is challenged for its dimensionally homogeneous Jacobian modeling and optimal design of architecture. In this paper, a means to achieve redundant actuation by adding kinematic constraints is introduced, which reduces the DOFs of the end-effector (EE). A generic dimensionally homogeneous Jacobian is developed for this type of RAPMs, which maps the generalized velocities of three points on the EE to the joint velocities. A new optimization algorithm derived from this dimensionally homogeneous Jacobian is proposed for the optimal design of this type of RAPMs. As an example, this paper presents a spatial RAPM involving linkages and cam mechanisms. This RAPM has 4 DOFs and 6 translational actuations. The linkage lengths and the position of the universal joints of the RAPM are optimized based on the dimensionally homogeneous Jacobian.

关键词： redundant actuation parallel manipulator linkage–cam mechanism Jacobian optimal design

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Cryogenic minimum quantity lubrication machining: from mechanism to application

《机械工程前沿（英文）》 2021年第16卷第4期页码 649-697 doi: 10.1007/s11465-021-0654-2

摘要： Cutting fluid plays a cooling–lubrication role in the cutting of metal materials. However, the substantial usage of cutting fluid in traditional flood machining seriously pollutes the environment and threatens the health of workers. Environmental machining technologies, such as dry cutting, minimum quantity lubrication (MQL), and cryogenic cooling technology, have been used as substitute for flood machining. However, the insufficient cooling capacity of MQL with normal-temperature compressed gas and the lack of lubricating performance of cryogenic cooling technology limit their industrial application. The technical bottleneck of mechanical–thermal damage of difficult-to-cut materials in aerospace and other fields can be solved by combining cryogenic medium and MQL. The latest progress of cryogenic minimum quantity lubrication (CMQL) technology is reviewed in this paper, and the key scientific issues in the research achievements of CMQL are clarified. First, the application forms and process characteristics of CMQL devices in turning, milling, and grinding are systematically summarized from traditional settings to innovative design. Second, the cooling–lubrication mechanism of CMQL and its influence mechanism on material hardness, cutting force, tool wear, and workpiece surface quality in cutting are extensively revealed. The effects of CMQL are systematically analyzed based on its mechanism and application form. Results show that the application effect of CMQL is better than that of cryogenic technology or MQL alone. Finally, the prospect, which provides basis and support for engineering application and development of CMQL technology, is introduced considering the limitations of CMQL.

关键词： cryogenic minimum quantity lubrication (CMQL) cryogenic medium processing mode device application mechanism application effect