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Dynamic characteristics of a magnetorheological pin joint for civil structures

Yancheng LI,Jianchun LI

《机械工程前沿（英文）》 2014年 第9卷 第1期   页码 15-33 doi: 10.1007/s11465-014-0283-0

摘要：

Magnetorheological (MR) pin joint is a novel device in which its joint moment resistance can be controlled in real-time by altering the applied magnetic field. The smart pin joint is intended to be used as a controllable connector between the columns and beams of a civil structure to instantaneously shift the structural natural frequencies in order to avoid resonance and therefore to reduce unwanted vibrations and hence prevent structural damage. As an intrinsically nonlinear device, modelling of this MR fluid based device is a challenging task and makes the design of a suitable control algorithm a cumbersome situation. Aimed at its application in civil structure, the main purpose of this paper is to test and characterise the hysteretic behaviour of MR pin joint. A test scheme is designed to obtain the dynamic performance of MR pin joint in the dominant earthquake frequency range. Some unique phenomena different from those of MR damper are observed through the experimental testing. A computationally-efficient model is proposed by introducing a hyperbolic element to accurately reproduce its dynamic behaviour and to further facilitate the design of a suitable control algorithm. Comprehensive investigations on the model accuracy and dependences of the proposed model on loading condition (frequency and amplitude) and input current level are reported in the last section of this paper.

关键词： Magnetorheological pin joint     hyperbolic hysteresis model experimental testing frequency dependence    

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Design considerations and experimental studies on semi-active smart pin joint

Yancheng LI, Jianchun LI, Bijan SAMALI, Jiong WANG,

《机械工程前沿（英文）》 2009年 第4卷 第4期   页码 363-370 doi: 10.1007/s11465-009-0074-1

摘要： Hostile dynamic loadings such as severe wind storms, earthquakes, and sudden impacts can cause severe damage to many civil engineering structures. An intelligent structural system equipped with smart structural members that are controllable in real-time is an effective solution to structural damage and failure during such situations. Civil intelligent structures with controllable properties to adapt to any changes due to dynamic loadings can lead to effective protection of structures and their occupants. In this paper, design and testing of a semi-active magnetorheological (MR) pin joint, in which the moment resistance can be controlled in real-time by altering the magnetic field, is reported with the view of using it as a potential candidate for smart members in the development of intelligent structures. Design of prototype smart pin joints includes theoretical analysis related to the radius of the rotary plate, the property of MR fluids and the gap between the rotary plate and the casing based on the requirements of the dynamics of MR pin joints. FEM analysis was deployed to study the distribution of the magnetic field along the gap. It is found, from the theoretical analysis and experimental verification, that the MR pin joint with a diameter of 180 mm can produce a torque of up to 30 Nm, which meets requirements for semi-active members in a multi-storey prototype building model in the next stage of research and development.

关键词： magnetorheological (MR) fluids     smart pin joint     design consideration    

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Study on damping properties of magnetorheological damper

ZHOU Yu-feng, CHEN Hua-ling

《机械工程前沿（英文）》 2006年 第1卷 第4期   页码 452-455 doi: 10.1007/s11465-006-0057-4

摘要： To research the properties of a new kind of smart controllable MR (magnetorheological) fluid, in this paper, the rheological models are discussed. On the basis of analyzing the structural forms of MR dampers, an improved structure of the MR damper is introduced; the properties of the novel MR damper are then tested. The experimental results reveal that the Herschel-Bulkley model predicts the force-velocity well; the damping properties of the ameliorated structure of the MR damper have improved; when the excitation is a trigonal signal, the MR damper reveals a thinning effect at high velocity; and when the excitation is a sinusoidal signal, the MR damper reveals a nonlinear hysteretic property between the damping force and relative velocity. Finally, the main unsolved problems have been put forward.

关键词： nonlinear hysteretic     force-velocity     unsolved     excitation     magnetorheological    

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Variable stiffness and damping magnetorheological isolator

Yang ZHOU, Xingyu WANG, Xianzhou ZHANG, Weihua LI

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 310-315 doi: 10.1007/s11465-009-0039-4

摘要： This paper presents the development and characterization of a magnetorheological (MR) fluid-based variable stiffness and damping isolator. The prototype of the MR fluid isolator is fabricated, and its dynamic behavior is measured under various applied magnetic fields. The parameters of the model under various magnetic fields are identified, and the dynamic performance of the isolator is evaluated in simulation. Experimental results indicate that both the stiffness and damping capability of the developed MR isolator can be controlled by an external magnetic field.

关键词： magnetorheological (MR) fluid     stiffness     damping     mathematical model     dynamic performance     parameter identification    

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Creep and recovery behaviors of magnetorheological elastomers

Weihua LI, Yang ZHOU, Tongfei TIAN, Gursel ALICI,

《机械工程前沿（英文）》 2010年 第5卷 第3期   页码 341-346 doi: 10.1007/s11465-010-0096-8

摘要： This paper presents experimental and modeling study of creep and recovery behaviors of magneto-rheological elastomers (MREs) under constant stresses. Experimental study was accomplished using a rheometer with parallel-plate geometry. Under constant stresses ranging from a small value to a large one, the resultant strains were recorded. The experimental results demonstrated that MREs behave as linear visocleastic properties. The effects of the magnetic field and stress on MRE creep behaviors were discussed. Moreover, a four-parameter viscoelastic model was developed to describe MRE creep behaviors. The comparison between the experimental results and the modeling predictions indicates that the model can predict MRE creep behaviors very well.

关键词： magneto-rheological elastomers (MREs)     creep     recovery     linear viscoelastic model    

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Analytical study on damping performances of magnetorheological grease damper based on disk squeeze mode

Danxia ZHAO, Changrong LIAO, Qiong LIU, Jing LUO

《机械工程前沿（英文）》 2011年 第6卷 第3期   页码 312-317 doi: 10.1007/s11465-011-0235-x

摘要：

In this paper, a small displacement-type magnetorheological grease (MRG) damper based on disk squeeze mode is proposed. The squeeze flow differential equation is obtained. The Navier slip condition is considered on the surfaces and the boundary compatible condition is established. The radial velocity profiles and the radial pressure distributions are derived respectively, and the mathematical stress expression is calculated. To verify rationality of analytical method, the MRG damper is designed and fabricated according to the technical requirements of an engine vibration isolation system. The experimental damping force from MTS870 Electro-hydraulic Servo with sine wave excitation shows that the proposed analytical method is feasible and provides the reference value for designing MRG damper based on disk squeeze mode.

关键词： magnetorheological grease (MRG)     damper     squeeze model    

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multi-objective design method for seismic retrofitting of existing reinforced concrete frames using pin-supported

Yue CHEN; Rong XU; Hao WU; Tao SHENG

《结构与土木工程前沿（英文）》 2022年 第16卷 第9期   页码 1089-1103 doi: 10.1007/s11709-022-0851-z

摘要： Over the past several decades, a variety of technical ways have been developed in seismic retrofitting of existing reinforced concrete frames (RFs). Among them, pin-supported rocking walls (PWs) have received much attentions to researchers recently. However, it is still a challenge that how to determine the stiffness demand of PWs and assign the value of the drift concentration factor (DCF) for entire systems rationally and efficiently. In this paper, a design method has been exploited for seismic retrofitting of existing RFs using PWs (RF-PWs) via a multi-objective evolutionary algorithm. Then, the method has been investigated and verified through a practical project. Finally, a parametric analysis was executed to exhibit the strengths and working mechanism of the multi-objective design method. To sum up, the findings of this investigation show that the method furnished in this paper is feasible, functional and can provide adequate information for determining the stiffness demand and the value of the DCF for PWs. Furthermore, it can be applied for the preliminary design of these kinds of structures.

关键词： pin-supported rocking wall     reinforced concrete frame     seismic retrofit     stiffness demand     drift concentration factor     multi-objective design     genetic algorithm     Pareto optimal solution    

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Analysis and experiment of controllability of magnetorheological fluids based on micro-pipeline

Yongqing SU, Yikuan SONG, Jiguang YUE

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 339-344 doi: 10.1007/s11465-009-0048-3

摘要： The controllability of the magneto-rheological fluid (MRF) flowing through a micro-pipeline is analyzed. The coupled formulas for MRF are deduced by analyzing the property of the flow field and magnetic field. Then, the relationship between the flow speed of MRF and the special shear stress under the effect of the magnetic field is founded. The model of the MRF and micro-pipeline is established by using multi-physics software of Comsol, the curve of - in an ideal condition is attained by modifying parameters, and by adding the boundary condition of the model. This paper provides a theoretical proof of the controllability of MRF flowing through the micro-pipeline and explores MRF’s application on the micro-drive and control field.

关键词： Magneto-rheological fluids (MRF)     micro-pipeline     coupled model     multi-physics simulation    

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Theoretical and experimental study on seismic response control on top of Three-Gorges ship lift towers using magnetorheological

Weilian QU, Jianwei TU

《结构与土木工程前沿（英文）》 2009年 第3卷 第1期   页码 32-41 doi: 10.1007/s11709-009-0003-8

摘要： A vertical ship lift under earthquake excitation may suffer from a whipping effect due to the sudden change of building lateral stiffness at the top of the ship lift towers. This paper proposes a roof magnetorheological (MR) intelligent isolation system to prevent the seismic whipping effect on machinery structures. Theoretically, the dynamic models of MR damper and the mechanical model of ship lift was established, the inverse neural network controlling algorithm was proposed and the fundamental semi-active control equation for the Three-Gorges ship lift where the MR intelligent isolation system was installed was deduced. Experimentally, the experimental model of the ship lift was given, the vibrating table experiment of the MR intelligent isolation system controlling the whipping effect was carried out and the results of the inverse neural network control strategy and passive isolation strategy were compared. In practical aspect, the large-scale MR damper (500 kN) and a sliding support with limited stiffness were designed and fabricated. It was proven that the MR intelligent isolation system with proper control strategy can greatly reduce the seismic whipping effect on the top workshop of the ship lift and be simple and effective enough to be applied to real engineering structures.

关键词： Three-Gorges ship lift tower     whipping effect     magnetorheological (MR) intelligent isolation system     neural network     sliding steel supporting    

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Analytical algorithms of compressive bending capacity of bolted circumferential joint in metro shield

《结构与土木工程前沿（英文）》   页码 901-914 doi: 10.1007/s11709-023-0915-8

摘要： The integrity and bearing capacity of segment joints in shield tunnels are associated closely with the mechanical properties of the joints. This study focuses on the mechanical characteristics and mechanism of a bolted circumferential joint during the entire bearing process. Simplified analytical algorithms for four stress stages are established to describe the bearing behaviors of the joint under a compressive bending load. A height adjustment coefficient, α, for the outer concrete compression zone is introduced into a simplified analytical model. Factors affecting α are determined, and the degree of influence of these factors is investigated via orthogonal numerical simulations. The numerical results show that α can be specified as approximately 0.2 for most metro shield tunnels in China. Subsequently, a case study is performed to verify the rationality of the simplified theoretical analysis for the segment joint via numerical simulations and experiments. Using the proposed simplified analytical algorithms, a parametric investigation is conducted to discuss the factors affecting the ultimate compressive bending capacity of the joint. The method for optimizing the joint flexural stiffness is clarified. The results of this study can provide a theoretical basis for optimizing the design and prediciting the damage of bolted segment joints in shield tunnels.

关键词： shield tunnel     segment joint     joint structural model     failure mechanism    

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Antibiotics-mediated intestinal microbiome perturbation aggravates tacrolimus-induced glucose disorders in mice

Yuqiu Han, Xiangyang Jiang, Qi Ling, Li Wu, Pin Wu, Ruiqi Tang, Xiaowei Xu, Meifang Yang, Lijiang Zhang

《医学前沿（英文）》 2019年 第13卷 第4期   页码 471-481 doi: 10.1007/s11684-019-0686-8

摘要： Both immunosuppressants and antibiotics (ABX) are indispensable for transplant patients. However, the former increases the risk of new-onset diabetes, whereas the latter impacts intestinal microbiota (IM). It is still unclear whether and how the interaction between immunosuppressants and ABX alters the IM and thus leads to glucose metabolism disorders. This study examined the alterations of glucose and lipid metabolism and IM in mice exposed to tacrolimus (TAC) with or without ABX. We found that ABX further aggravated TAC-induced glucose tolerance and increased insulin secretion. Combined treatment resulted in exacerbated lipid accumulation in the liver. TAC-altered microbial community was further amplified by ABX administration, as characterized by reductions in phylum Firmicutes, family Lachnospiraceae, and genus . Analyses based on the metagenomic profiles revealed that ABX augmented the effect of TAC on microbial metabolic function mostly related to lipid metabolism. The altered components of gut microbiome and predicted microbial functional profiles showed significant correlation with hepatic lipid accumulation and glucose disorders. In conclusion, ABX aggravated the effect of TAC on the microbiome and its metabolic capacities, which might contribute to hepatic lipid accumulation and glucose disorders. These findings suggest that the ABX-altered microbiome can amplify the diabetogenic effect of TAC and could be a novel therapeutic target for patients.

关键词： antibiotics     tacrolimus     glucose disorders     microbiome    

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Finite element analysis on the seismic behavior of side joint of Prefabricated Cage System in prefabricated

Yunlin LIU, Shitao ZHU

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1095-1104 doi: 10.1007/s11709-019-0538-2

摘要： The Prefabricated Cage System (PCS) has the advantages of high bearing capacity and good ductility. Meanwhile, it is convenient for factory production and it is beneficial to the cost savings, construction period shortening. Side joint is the weak region of PCS concrete frame and has great influence on seismic behavior of the whole structure. Thus systematically study on the seismic behavior of PCS concrete side joint is necessary. This paper presents a finite element study on behavior of the side joint under seismic loading. In the finite element model, PCS concrete and the reinforced concrete (RC) is modeled by the solid element and fiber-beam element, respectively. The numerical results is compared with the experimental results and it is found that the results of model based on fiber-beam element is in better agreement with the experimental results than solid element model. In addition, the overall seismic behavior of the side joints in PCS concrete is better than that of the RC with the same strength.

关键词： PCS concrete side joint     numerical simulation     fiber-beam element joint model     solid element joint model     seismic behavior    

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Association of the genetic polymorphism of EPHX1 and EPHX2 with the susceptibility to chronic benzene poisoning

SUN Pin, ZHANG Zhongbin, WU Fen, WAN Junxiang, JIN Xibeng, XIA Zhaolin

《医学前沿（英文）》 2007年 第1卷 第3期   页码 320-326 doi: 10.1007/s11684-007-0062-y

摘要： The aim of this study was to explore the association of the genetic polymorphism of and with the susceptibility to chronic benzene poisoning (CBP). A case-control study of 268 patients with CBP and 268 healthy workers matched by age and sex, all of whom were occupationally exposed to benzene, was conducted. The single nucleotide polymorphisms (SNPs, rs2854451, rs3738047, rs2234922 and rs1051741) of gene and the SNP (rs751141) of gene were tested by the TaqMan PCR method. In the subjects carrying the genotype of rs3738047 GG, the risk of CBP was decreased in the individuals simultaneously carrying rs2234922 G ( = 0.02). Alternatively, in the subjects carrying the genotype of rs2234922 AA, the risk of CBP was increased in the individuals simultaneously carrying the allele of rs751141A ( = 0.03). It was also found that there were potential interactions between alcohol consumption and the polymorphism of rs1051741 ( = 5.28, = 0.02) or rs2234922 (= 6.71, = 0.01). Compared to individuals with rs1051741 CC or rs2234922 AA genotype in the drinkers, the risk of CBP in those carrying genotypes of rs1051741 CT+TT or rs2234922 AG+GG was decreased, respectively ( = 0.04, 〈0.01). Haplotype analysis of polymorphisms in showed that the risk of CBP was increased in the subjects with haplotype 2 (rs2854451-A, rs3738047-G, rs2234922-A, rs1051741-C) or haplotype 4 (rs2854451-G, rs3738047-A, rs2234922-G, rs1051741-T), but decreased in those with haplotype 6 (rs2854451-G, rs3738047-G, rs2234922-G, rs1051741-T) or haplotype 10 (rs2854451-A, rs3738047-A, rs2234922-G, rs1051741-T), respectively. Logistic regression analysis revealed that smoking might play a role in modifying the risk of CBP (OR = 0.313, 95% CI: 0.123 0.794, = 0.015). The genetic polymorphism in may be associated with the risk of CBP in the Chinese occupational population and further research is needed for the association between the genetic polymorphism in and the susceptibility to CBP.

关键词： case-control     rs2854451     regression analysis     haplotype     further research    

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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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Prediction of shield tunneling-induced ground settlement using machine learning techniques

Renpeng CHEN, Pin ZHANG, Huaina WU, Zhiteng WANG, Zhiquan ZHONG

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1363-1378 doi: 10.1007/s11709-019-0561-3

摘要： Predicting the tunneling-induced maximum ground surface settlement is a complex problem since the settlement depends on plenty of intrinsic and extrinsic factors. This study investigates the efficiency and feasibility of six machine learning (ML) algorithms, namely, back-propagation neural network, wavelet neural network, general regression neural network (GRNN), extreme learning machine, support vector machine and random forest (RF), to predict tunneling-induced settlement. Field data sets including geological conditions, shield operational parameters, and tunnel geometry collected from four sections of tunnel with a total of 3.93 km are used to build models. Three indicators, mean absolute error, root mean absolute error, and coefficient of determination the ( ) are used to demonstrate the performance of each computational model. The results indicated that ML algorithms have great potential to predict tunneling-induced settlement, compared with the traditional multivariate linear regression method. GRNN and RF algorithms show the best performance among six ML algorithms, which accurately recognize the evolution of tunneling-induced settlement. The correlation between the input variables and settlement is also investigated by Pearson correlation coefficient.

关键词： EPB shield     shield tunneling     settlement prediction     machine learning    

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标题 作者 时间 类型 操作

Dynamic characteristics of a magnetorheological pin joint for civil structures

Yancheng LI,Jianchun LI

期刊论文

Design considerations and experimental studies on semi-active smart pin joint

Yancheng LI, Jianchun LI, Bijan SAMALI, Jiong WANG,

期刊论文

Study on damping properties of magnetorheological damper

ZHOU Yu-feng, CHEN Hua-ling

期刊论文

Variable stiffness and damping magnetorheological isolator

Yang ZHOU, Xingyu WANG, Xianzhou ZHANG, Weihua LI

期刊论文

Creep and recovery behaviors of magnetorheological elastomers

Weihua LI, Yang ZHOU, Tongfei TIAN, Gursel ALICI,

期刊论文

Analytical study on damping performances of magnetorheological grease damper based on disk squeeze mode

Danxia ZHAO, Changrong LIAO, Qiong LIU, Jing LUO

期刊论文

multi-objective design method for seismic retrofitting of existing reinforced concrete frames using pin-supported

Yue CHEN; Rong XU; Hao WU; Tao SHENG

期刊论文

Analysis and experiment of controllability of magnetorheological fluids based on micro-pipeline

Yongqing SU, Yikuan SONG, Jiguang YUE

期刊论文

Theoretical and experimental study on seismic response control on top of Three-Gorges ship lift towers using magnetorheological

Weilian QU, Jianwei TU

期刊论文

Analytical algorithms of compressive bending capacity of bolted circumferential joint in metro shield

期刊论文

Antibiotics-mediated intestinal microbiome perturbation aggravates tacrolimus-induced glucose disorders in mice

Yuqiu Han, Xiangyang Jiang, Qi Ling, Li Wu, Pin Wu, Ruiqi Tang, Xiaowei Xu, Meifang Yang, Lijiang Zhang

期刊论文

Finite element analysis on the seismic behavior of side joint of Prefabricated Cage System in prefabricated

Yunlin LIU, Shitao ZHU

期刊论文

Association of the genetic polymorphism of EPHX1 and EPHX2 with the susceptibility to chronic benzene poisoning

SUN Pin, ZHANG Zhongbin, WU Fen, WAN Junxiang, JIN Xibeng, XIA Zhaolin

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

Prediction of shield tunneling-induced ground settlement using machine learning techniques

Renpeng CHEN, Pin ZHANG, Huaina WU, Zhiteng WANG, Zhiquan ZHONG

期刊论文