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A new damage quantification approach for shear-wall buildings using ambient vibration data

Seung-Hun SUNG,Hyung-Jo JUNG

《结构与土木工程前沿(英文)》 2015年 第9卷 第1期   页码 17-25 doi: 10.1007/s11709-014-0278-2

摘要: This paper presents a new approach to estimate damage severity for shear-wall buildings using diagonal terms of a modal flexibility matrix estimated from dynamic properties. This study aims to provide a fundamental concept for quantifying the damage of realistic buildings by investigating an idealized shear-wall building. Numerical studies were performed on a 5-story shear-wall building model to validate the applicability of the presented approach, using two damage patterns. With the numerical simulations, the proposed approach accurately determined the damage ratio of the specimens. Experiments were also conducted on a 5-story shear-wall building model for which the system parameters were almost the same as those in numerical simulations. The estimated damage-quantification results from the experimental validations demonstrated that the performance of the presented method for shear-wall buildings was both suitable and accurate.

关键词: damage identification     modal flexibility     damage quantification     shear-wall buildings    

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    

工程承包联营体的柔性分析与评价

赵振宇,殷音

《中国工程科学》 2008年 第10卷 第9期   页码 84-87

摘要:

讨论了工程承包联营体环境动荡性评价指标和工程承包联营体柔性评价指标以及相应的评价方法。通过柔性分析,可以判断出工程承包联营体各方面的柔性程度能否与其相应的环境和内外部因素相适应,并为制订调整联营体柔性度的措施提供帮助,进而提高联营体的管理水平和竞争力。

关键词: 工程项目     承包商     联营体     柔性管理    

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    

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    

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    

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    

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    

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    

Response in piled raft foundation of tall chimneys under along-wind load incorporating flexibility of

B. R. JAYALEKSHMI,S.V. JISHA,R. SHIVASHANKAR

《结构与土木工程前沿(英文)》 2015年 第9卷 第3期   页码 307-322 doi: 10.1007/s11709-015-0288-8

摘要: The present paper deals with the numerical analysis of tall reinforced concrete chimneys with piled raft foundation subjected to along-wind loads considering the flexibility of soil. The analysis was carried out using finite element method on the basis of direct method of soil-structure interaction (SSI). The linear elastic material behavior was assumed for chimney, piled raft and soil. Four different material properties of soil stratum were selected in order to study the effect of SSI. The chimney elevation and the thickness of raft of piled raft foundation were also varied for the parametric study. The chimneys were assumed to be located in terrain category 2 and subjected to a maximum wind speed of 50 m/s as per IS:875 (Part 3)-1987. The along-wind loads were computed according to IS:4998 (Part 1)-1992. The base moments of chimney evaluated from the SSI analysis were compared with those obtained as per IS:4998 (Part 1)-1992. The tangential and radial bending moments of raft of piled raft foundation were evaluated through SSI analysis and compared with those obtained from conventional analysis as per IS:11089-1984, assuming rigidity at the base of the raft foundation. The settlements of raft of piled raft foundation, deflection of pile and moments of the pile due to interaction with different soil stratum were also evaluated. From the analysis, considerable reduction in the base moment of chimney due to the effect of SSI is observed. Higher radial moments and lower tangential moments were obtained for lower elevation chimneys with piled raft resting on loose sand when compared with conventional analysis results. The effect of SSI in the response of the pile is more significant when the structure-foundation system interacts with loose sand.

关键词: finite element method     piled raft     tall chimney     soil-structure interaction     along-wind load    

Review of

Yang YU, Jiafu TANG

《工程管理前沿(英文)》 2019年 第6卷 第2期   页码 183-192 doi: 10.1007/s42524-019-0028-1

摘要: production is regarded as a new production mode and derived from the production site of Japanese electronics industry. This production mode is proposed to overcome the low flexibility of the assembly line. production has been successfully implemented in Japanese electronics industry, such as Canon and Sony. Benefits from production include rapid response, good flexibility, and high productivity. production has received extensive attention in academic research and production practice. This study reviews the background, characteristics, types, and operation of production. The advantages and applicable scenes of production are summarized from the perspective of business practice. We compare production and famous production modes, i.e., assembly line, cellular manufacturing, and Toyota Production System. The literature on production is surveyed and classified. Furthermore, future research directions are provided.

关键词: seru production     production mode     flexibility     literature review    

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    

Design of a novel side-mounted leg mechanism with high flexibility for a multi-mission quadruped earth

《机械工程前沿(英文)》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0740-0

摘要: Earth rover is a class of emerging wheeled-leg robots for nature exploration. At present, few methods for these robots’ leg design utilize a side-mounted spatial parallel mechanism. Thus, this paper presents a complete design process of a novel 5-degree-of-freedom (5-DOF) hybrid leg mechanism for our quadruped earth rover BJTUBOT. First, a general approach is proposed for constructing the novel leg mechanism. Subsequently, by evaluating the basic locomotion task (LT) of the rover based on screw theory, we determine the desired motion characteristic of the side-mounted leg and carry out its two feasible configurations. With regard to the synthesis method of the parallel mechanism, a family of concise hybrid leg mechanisms using the 6-DOF limbs and an L1F1C limb (which can provide a constraint force and a couple) is designed. In verifying the motion characteristics of this kind of leg, we select a typical (3-UPRU&RRRR)&R mechanism and then analyze its kinematic model, singularities, velocity mapping, workspace, dexterity, statics, and kinetostatic performance. Furthermore, the virtual quadruped rover equipped with this innovative leg mechanism is built. Various basic and specific LTs of the rover are demonstrated by simulation, which indicates that the flexibility of the legs can help the rover achieve multitasking.

关键词: design synthesis     parallel mechanism     hybrid leg mechanism     screw theory     quadruped robot    

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    

住宅建筑需求侧柔性——定义、柔性负荷及量化方法 Review

罗正意, 彭晋卿, 曹静宇, 殷荣欣, 邹斌, 谭羽桐, 严晋跃

《工程(英文)》 2022年 第16卷 第9期   页码 123-140 doi: 10.1016/j.eng.2022.01.010

摘要:

本文综述了近年来关于住宅建筑需求侧柔性的定义、柔性负荷及柔性量化方法方面的研究。首先,针对建筑需求侧柔性、运行柔性和能源柔性等不同的术语,进行了系统的比较和区分;其次,对住宅建筑主要柔性负荷的运行特性和柔性能力进行了总结和比较;再次,对柔性负荷的建模方法和柔性量化指标也进行了详细的综述和总结。最后,提出了当前建筑需求侧柔性领域存在的一些亟待解决的问题。研究结果表明当前针对住宅建筑需求侧柔性的研究主要以中央空调、储水式电热水器、湿电器、冰箱和照明为主,分别占现有研究的36.7%、25.7%、14.7%、9.2%和8.3%。这些柔性负荷在运行特性、使用频率和柔性能力
方面存在较大的差异,而对于它们实际的响应特性有待进一步研究。此外,本文给出了用于柔性负荷建模的白箱、灰箱和黑箱模型在不同应用场合下适用性的建议;对于柔性量化指标,现有研究主要从功率、时间、能量、效率、经济性和环保性等维度提出了大量的指标,但是缺少统一的柔性量化体系。本文能够帮助读者更好地理解建筑需求侧柔性、区分与柔性相关的不同的术语、了解住宅建筑不同柔性负荷的运行特性和柔性能力,同时也能为柔性负荷的建模和柔性量化的相关研究提供指导。

关键词: 住宅建筑     需求侧柔性     柔性负荷     建模方法     量化指标    

标题 作者 时间 类型 操作

A new damage quantification approach for shear-wall buildings using ambient vibration data

Seung-Hun SUNG,Hyung-Jo JUNG

期刊论文

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

Pengxing YI,Peng HUANG,Tielin SHI

期刊论文

工程承包联营体的柔性分析与评价

赵振宇,殷音

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

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

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

期刊论文

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

Zhengying LI, Zhengliang LI,

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

Response in piled raft foundation of tall chimneys under along-wind load incorporating flexibility of

B. R. JAYALEKSHMI,S.V. JISHA,R. SHIVASHANKAR

期刊论文

Review of

Yang YU, Jiafu TANG

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

Design of a novel side-mounted leg mechanism with high flexibility for a multi-mission quadruped earth

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

住宅建筑需求侧柔性——定义、柔性负荷及量化方法

罗正意, 彭晋卿, 曹静宇, 殷荣欣, 邹斌, 谭羽桐, 严晋跃

期刊论文