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Numerical analysis and experimental investigation of modal properties for the gearbox in wind turbine

Pengxing YI,Peng HUANG,Tielin SHI

《机械工程前沿（英文）》 2016年 第11卷 第4期   页码 388-402 doi: 10.1007/s11465-016-0404-z

摘要：

Wind turbine gearbox (WTG), which functions as an accelerator, ensures the performance and service life of wind turbine systems. This paper examines the distinctive modal properties of WTGs through finite element (FE) and experimental modal analyses. The study is performed in two parts. First, a whole system model is developed to investigate the first 10 modal frequencies and mode shapes of WTG using flexible multi-body modeling techniques. Given the complex structure and operating conditions of WTG, this study applies spring elements to the model and quantifies how the bearings and gear pair interactions affect the dynamic characteristics of WTGs. Second, the FE modal results are validated through experimental modal analyses of a 1.5 WM WTG using the frequency response function method of single point excitation and multi-point response. The natural frequencies from the FE and experimental modal analyses show favorable agreement and reveal that the characteristic frequency of the studied gearbox avoids its eigen-frequency very well.

关键词： wind turbine gearbox     modal analysis     finite element analysis     modal frequency     bearing equivalence    

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A method of analysis for modal aero-damping of vibrating blade in incompressible flow

Jun XING, Lin LI,

《能源前沿（英文）》 2009年 第3卷 第4期   页码 465-471 doi: 10.1007/s11708-009-0037-6

摘要： By establishing a research model for aero-damping in a uniform incoming flow, the three-dimension analytical algorithm of the modal aero-damping based on the equivalent viscous damping principle was established. The algorithm, which is suited for low-speed flow, to compute aero-damping is based on classical lift line theory in aerodynamics, according to the analytical solution of unsteady aerodynamic force. According to the analytical equations, the modal aero-damping ratio for different nature frequencies of blades in various fluid field conditions can be solved, and the factors to affect the aero-damping can be determined.The first bend and the first torsion’s modal aero-damping ratios of a compressor blade are calculated by using the above algorithms. The results show that the aero-damping cannot be neglected comparing with the structure damping. It reflects the coupling degree between the flow field and the structure field, so the aero-damping is significant to compute the stress and life of blade.

关键词： compressor     different     three-dimension analytical     classical     low-speed    

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Experimental study of structural damage identification based on modal parameters and decay ratio of acceleration

Zhigen WU, Guohua LIU, Zihua ZHANG

《结构与土木工程前沿（英文）》 2011年 第5卷 第1期   页码 112-120 doi: 10.1007/s11709-010-0069-3

摘要： A novel damage assessment method based on the decay ratio of acceleration signals (DRAS) was proposed. Two experimental tests were used to show the efficiency. Three beams were gradually damaged, and then the changes of dynamic parameters were monitored from initial to failure state. In addition, a new method was compared with the linear modal-based damage assessment using wavelet transform (WT). The results clearly show that DRAS increases in linear elasticity state and microcrack propagation state, while DRAS decreases in macrocrack propagation state. Preliminary analysis was developed considering the beat phenomenon in the nonlinear state to explain the turn point of DRAS. With better sensibility of damage than modal parameters, probably DRAS is a promising damage indicator in damage assessment.

关键词： damage assessment     decay ratio of acceleration signals (DRAS)     wavelet transform (WT)     modal analysis     reinforced concrete beam     beat phenomenon    

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Experimental study of modal parameter identification in a simulated ambient-excited structure

JI Xiaodong, QIAN Jiaru, XU Longhe

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 281-285 doi: 10.1007/s11709-007-0036-9

摘要： Structure modal parameter online identification was used to monitor the structural health as evidenced by changes in the vibration characteristics. The natural excitation technique and the eigensystem realization algorithm were combined to identify the modal parameters in the time domain of a structure excited by simulated ambient vibrations. The mass-normalized mode shapes were obtained from the eigen-sensitivity analysis. The experimental modal analysis was performed on a two-story steel braced frame model excited by simulated ambient vibrations and hammer impacts. The mass-normalized mode shapes were acquired by changing the structural mass and by eigen-sensitivity analy sis. From finite element analysis results and the experimental data, it is shown that this method is effective.

关键词： eigensystem realization     eigen-sensitivity analysis     realization algorithm     vibration     effective    

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Experimental and computational validation of a scaled train tunnel model using modal analysis

Janice B. D’SOUZA, Sangarapillai KANAPATHIPILLAI

《机械工程前沿（英文）》 2013年 第8卷 第4期   页码 420-428 doi: 10.1007/s11465-013-0281-7

摘要：

Acoustic engineers are faced with the challenge of minimising reverberation time in their designs so as to contribute to the health and well-being of those traveling by train and those on the platforms. Although the problem is easy to identify, it is not as simple to solve. The acoustical environment of a train tunnel is complex, with a variety of noise contributing factors such as train announcements, speech of commuters, ventilation systems, electrical equipment and wheel and rail noise. As a result, there is some difficulty in modeling the complete acoustic environment with computational or acoustic first principles. In this study, an experimental rig was constructed to model the acoustic behavior within a tunnel. The modal properties for the 300 Hz to 1500 Hz range, including resonances and mode shapes were identified and were shown to successfully correspond to theoretical results and a computational model created in COMSOL using Finite Element Analysis.

关键词： reverberation time     acoustic environment     modal properties     resonances    

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Variational mode decomposition based modal parameter identification in civil engineering

Mingjie ZHANG, Fuyou XU

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1082-1094 doi: 10.1007/s11709-019-0537-3

摘要： An out-put only modal parameter identification method based on variational mode decomposition (VMD) is developed for civil structure identifications. The recently developed VMD technique is utilized to decompose the free decay response (FDR) of a structure into to modal responses. A novel procedure is developed to calculate the instantaneous modal frequencies and instantaneous modal damping ratios. The proposed identification method can straightforwardly extract the mode shape vectors using the modal responses extracted from the FDRs at all available sensors on the structure. A series of numerical and experimental case studies are conducted to demonstrate the efficiency and highlight the superiority of the proposed method in modal parameter identification using both free vibration and ambient vibration data. The results of the present method are compared with those of the empirical mode decomposition-based method, and the superiorities of the present method are verified. The proposed method is proved to be efficient and accurate in modal parameter identification for both linear and nonlinear civil structures, including structures with closely spaced modes, sudden modal parameter variation, and amplitude-dependent modal parameters, etc.

关键词： modal parameter identification     variational mode decomposition     civil structure     nonlinear system     closely spaced modes    

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Parameter studies on impact in a lap joint

Amir M. RAHMANI,Elizabeth K. ERVIN

《机械工程前沿（英文）》 2015年 第10卷 第1期   页码 64-77 doi: 10.1007/s11465-014-0322-x

摘要：

To represent a loose lap joint, a beam impacting four springs with gaps is modeled. Modal analysis with base excitation is solved, and time histories of contact points are closely monitored. Using the impulse during steady state response, six influential parameters are studied: damping ratio, contact stiffness, intermediate contact position, gap, excitation amplitude and beam height. For all parameters, the system response is highly controlled by modes with two contacting springs. Each parameter’s effect on system response is presented including unstable regions, unique trend behaviours result. Recommendations for structural designers are also noted.

关键词： impact mechanics     contact     joint behaviour     modal analysis     parameter study    

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network for damage detection in functionally graded carbon nanotube-reinforced composite plates using modal

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1453-1479 doi: 10.1007/s11709-021-0767-z

摘要： This paper proposes a new Deep Feed-forward Neural Network (DFNN) approach for damage detection in functionally graded carbon nanotube-reinforced composite (FG-CNTRC) plates. In the proposed approach, the DFNN model is developed based on a data set containing 20 000 samples of damage scenarios, obtained via finite element (FE) simulation, of the FG-CNTRC plates. The elemental modal kinetic energy (MKE) values, calculated from natural frequencies and translational nodal displacements of the structures, are utilized as input of the DFNN model while the damage locations and corresponding severities are considered as output. The state-of-the art Exponential Linear Units (ELU) activation function and the Adamax algorithm are employed to train the DFNN model. Additionally, in order to enhance the performance of the DFNN model, the mini-batch and early-stopping techniques are applied to the training process. A trial-and-error procedure is implemented to determine suitable parameters of the network such as the number of hidden layers and the number of neurons in each layer. The accuracy and capability of the proposed DFNN model are illustrated through two distinct configurations of the CNT-fibers constituting the FG-CNTRC plates including uniform distribution (UD) and functionally graded-V distribution (FG-VD). Furthermore, the performance and stability of the DFNN model with the consideration of noise effects on the input data are also investigated. Obtained results indicate that the proposed DFNN model is able to give sufficiently accurate damage detection outcomes for the FG-CNTRC plates for both cases of noise-free and noise-influenced data.

关键词： damage detection     deep feed-forward neural networks     functionally graded carbon nanotube-reinforced composite plates     modal kinetic energy    

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Modal disturbance investigation of rod-shaped ultrasonic motor using bending vibrations

ZHANG Jiantao, ZHU Hua, ZHAO Chunsheng

《机械工程前沿（英文）》 2008年 第3卷 第3期   页码 343-347 doi: 10.1007/s11465-008-0058-6

摘要： Modal disturbance of a rod-shaped ultrasonic motor using bending vibrations can cause problems such as low motor efficiency, instability, and poor control. In this paper, a dynamic analysis model of a stator is created on the basis of the finite element method (FEM) and Hamilton principle. The modal frequency sensitivities of the stator to the structure parameters are investigated by modal analysis. Accordingly, the structure parameters of the stator are modified to separate working modes from disturbance modes. A rod-shaped ultrasonic motor stator is fabricated, and the experimental results of its amplitude frequency response characteristics show that the purpose of modal separation is achieved. The frequency separation between working modes and disturbance modes is more than 2 kHz. The validity of the method is verified.

关键词： Hamilton principle     disturbance     separation     frequency separation     dynamic analysis    

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Performance-based seismic assessment of a historical masonry arch bridge: Effect of pulse-like excitations

《结构与土木工程前沿（英文）》   页码 855-869 doi: 10.1007/s11709-023-0972-z

摘要： Seismic analysis of historical masonry bridges is important for authorities in all countries hosting such cultural heritage assets. The masonry arch bridge investigated in this study was built during the Roman period and is on the island of Rhodes, in Greece. Fifteen seismic records were considered and categorized as far-field, pulse-like near-field, and non-pulse-like near-field. The earthquake excitations were scaled to a target spectrum, and nonlinear time-history analyses were performed in the transverse direction. The performance levels were introduced based on the pushover curve, and the post-earthquake damage state of the bridge was examined. According to the results, pulse-like near-field events are more damaging than non-pulse-like near-field ground motions. Additionally the bridge is more vulnerable to far-field excitations than near-field events. Furthermore, the structure will suffer extensive post-earthquake damage and must be retrofitted.

关键词： masonry arch bridges     seismic behavior     modal properties     pulse-like records     nonlinear time history analysis    

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Control mode selection for modal control of long-span arch bridge

Zhengying LI, Zhengliang LI,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 401-406 doi: 10.1007/s11709-009-0052-z

摘要： For seismic control of arch bridge, a model reduction of long-span arch bridge was implemented based on modal analysis. As for the critical mode selection, an approach based on the maximum modal displacement was presented. This approach takes into consideration the effect of external seismic excitation and is more reasonable than only considering dynamic bridge characteristics based on a modal contribution ratio. The time domain and frequency domain analysis method were used to verify the simplified model of the Nimu arch bridge in Tibet as an example. The numerical results show that the method of maximal modal displacement better analyze long-span arch bridge when multisupport seismic excitation must be considered. The reduced-order system also is more in line with the performance of the original model.

关键词： selection     reduced-order     excitation     long-span     simplified    

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新型20 m桥梁检测车结构的有限元力学分析

沈意平,何福泉,王送来,张田

《中国工程科学》 2010年 第12卷 第9期   页码 107-112

摘要：

针对设计的新型20 m桥梁检测车，利用Pro/E软件建立了4种工况下整车结构的实体模型，运用有限元软件ANSYS对建立的模型进行了静力和模态分析。开展对设计结构进行强度校核，找出了设计结构的危险部位，并综合分析结果提出了设计结构的加强建议。有限元力学分析为校核结构强度提供了重要的理论方法，分析结果为桥梁检测车的结构设计与实际生产提供了理论依据与技术支持。

关键词： 桥梁检测车     有限元     静力     模态     强度    

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Modal analysis of acoustic leak signal in pipelines using time-frequency analysis

JIAO Jing-pin, FEI Ren-yuan, HE Cun-fu, WU Bin

《机械工程前沿（英文）》 2006年 第1卷 第2期   页码 146-150 doi: 10.1007/s11465-006-0013-3

摘要： It is important to analyze the propagation characteristics of guided waves in acoustic leak location in pipelines. In this paper, the acoustic leak signal is analyzed in the time-frequency domain. Based on the relation of time-frequency distribution of the acoustic leak signal and the dispersion curves of guided waves, the mode components of acoustic leak signals were obtained. The research can provide a guideline for the mode selection in pipeline leak location, and help improve the accuracy of leak location.

关键词： dispersion     selection     guided     research     time-frequency    

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Finite element model updating of a large structure using multi-setup stochastic subspace identification method and bees optimization algorithm

Reza KHADEMI-ZAHEDI, Pouyan ALIMOURI

《结构与土木工程前沿（英文）》 2019年 第13卷 第4期   页码 965-980 doi: 10.1007/s11709-019-0530-x

摘要： In the present contribution, operational modal analysis in conjunction with bees optimization algorithm are utilized to update the finite element model of a solar power plant structure. The physical parameters which required to be updated are uncertain parameters including geometry, material properties and boundary conditions of the aforementioned structure. To determine these uncertain parameters, local and global sensitivity analyses are performed to increase the solution accuracy. An objective function is determined using the sum of the squared errors between the natural frequencies calculated by finite element method and operational modal analysis, which is optimized using bees optimization algorithm. The natural frequencies of the solar power plant structure are estimated by multi-setup stochastic subspace identification method which is considered as a strong and efficient method in operational modal analysis. The proposed algorithm is efficiently implemented on the solar power plant structure located in Shahid Chamran university of Ahvaz, Iran, to update parameters of its finite element model. Moreover, computed natural frequencies by numerical method are compared with those of the operational modal analysis. The results indicate that, bees optimization algorithm leads accurate results with fast convergence.

关键词： operational modal analysis     solar power plant structure     multi-setup stochastic subspace     bees optimization algorithm     sensitivity analysis    

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近β锻造推翻陈旧理论发展了三态组织

周义刚,曾卫东,俞汉清

《中国工程科学》 2001年 第3卷 第5期   页码 61-66

摘要：

将坯料置于相变的临界点附近10～15℃加热、锻造、锻后水冷，随后，不是采用时效处理，而是先进行高温韧化再低温强化处理。近β锻造的组织不再是等轴α量过多，或是为零的网篮条状α的结构模式；而是约含20%等轴α、50%～60%条状α构成的网篮和β转变基体组成的三态组织。这种结构不仅丰富和发展了国 际上钛合金已有的4种组织类塑（等轴、双态、网篮和并列），而且将等轴和网篮组织的性能优势集于一身，由此带来的力学性能超过了国内外相关技术的性能水平：能在不降低塑性，不丧失热稳定性的条件下，提高材料的高温性能、低周疲劳性能和断裂韧性，在改善性能的同时提高使用温度。近β锻造适用于（α+β)型合金， 还可应用于α、近α和近β型合金，其研究成果已用于制造了多种发动机盘件、飞机和导弹等重要结构件。

关键词： 钛合金     近β锻造     三态组织    

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标题 作者 时间 类型 操作

Numerical analysis and experimental investigation of modal properties for the gearbox in wind turbine

Pengxing YI,Peng HUANG,Tielin SHI

期刊论文

A method of analysis for modal aero-damping of vibrating blade in incompressible flow

Jun XING, Lin LI,

期刊论文

Experimental study of structural damage identification based on modal parameters and decay ratio of acceleration

Zhigen WU, Guohua LIU, Zihua ZHANG

期刊论文

Experimental study of modal parameter identification in a simulated ambient-excited structure

JI Xiaodong, QIAN Jiaru, XU Longhe

期刊论文

Experimental and computational validation of a scaled train tunnel model using modal analysis

Janice B. D’SOUZA, Sangarapillai KANAPATHIPILLAI

期刊论文

Variational mode decomposition based modal parameter identification in civil engineering

Mingjie ZHANG, Fuyou XU

期刊论文

Parameter studies on impact in a lap joint

Amir M. RAHMANI,Elizabeth K. ERVIN

期刊论文

network for damage detection in functionally graded carbon nanotube-reinforced composite plates using modal

期刊论文

Modal disturbance investigation of rod-shaped ultrasonic motor using bending vibrations

ZHANG Jiantao, ZHU Hua, ZHAO Chunsheng

期刊论文

Performance-based seismic assessment of a historical masonry arch bridge: Effect of pulse-like excitations

期刊论文

Control mode selection for modal control of long-span arch bridge

Zhengying LI, Zhengliang LI,

期刊论文

新型20 m桥梁检测车结构的有限元力学分析

沈意平,何福泉,王送来,张田

期刊论文

Modal analysis of acoustic leak signal in pipelines using time-frequency analysis

JIAO Jing-pin, FEI Ren-yuan, HE Cun-fu, WU Bin

期刊论文

Finite element model updating of a large structure using multi-setup stochastic subspace identification method and bees optimization algorithm

Reza KHADEMI-ZAHEDI, Pouyan ALIMOURI

期刊论文

近β锻造推翻陈旧理论发展了三态组织

周义刚,曾卫东,俞汉清

期刊论文