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Ping Wang - One of the best experts on this subject based on the ideXlab platform.
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vibration response analysis of Floating Slab Track supported by nonlinear quasi zero stiffness vibration isolators
Journal of Zhejiang University Science, 2021Co-Authors: Zeming Zhao, Kai Wei, Juanjuan Ren, Ping WangAbstract:To improve the low-frequency vibration reduction effect of a steel spring Floating Slab Track (FST), nonlinear quasi-zero-stiffness (QZS) vibration isolators composed of positive stiffness elements (PSEs) and negative stiffness elements (NSEs) were used to support the FST. First, considering the mechanical characteristics of the nonlinear QZS vibration isolators and the dynamic displacement limit (3 mm) of the FST, the feasible parameter groups were studied with the nonlinear stiffness variation range and bearing capacity as evaluation indices. A vertical vehicle-quasi-zero-stiffness Floating Slab Track (QZS-FST) coupled dynamic model was then established. To obtain a reasonable nonlinear stiffness within a few millimeters, the original length of the NSEs must be analyzed first, because it chiefly determines the stiffness nonlinearity level. The compression length of the NSEs at the equilibrium position must be determined to obtain the low stiffness of the Floating Slab without vehicle load. Meanwhile, to meet the dynamic displacement limit of the FST, the PSE stiffness must be increased to obtain a higher stiffness at the critical dynamic displacement. Various stiffness groups for the PSEs and NSEs can provide the same dynamic bearing capacity and yet have a significantly different vibration reduction effect. Excessive stiffness nonlinearity levels cannot effectively improve the vibration reduction effect at the natural frequency. Furthermore, they also significantly amplify the vibrations above the natural frequency. In this paper, the vertical vibration acceleration level (VAL) of the Floating Slab and the supporting force of the FST can be decreased by 6.9 dB and 55%, respectively, at the resonance frequency.
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Influence of Vibration Isolator Failure on Vehicle Operation Performance and Floating Slab Track Structure Vibration Reduction Effectiveness
Shock and Vibration, 2019Co-Authors: Caiyou Zhao, Dongya Liu, Xiaoming Zhang, Liuchong Wang, Ping WangAbstract:At present, steel-spring Floating Slabs have been widely used in urban rail transit to reduce the influence of ground vibration caused by vehicle operation on the surrounding environment. As a core part of vibration reduction for Floating Slab Track, the steel-spring vibration isolator may fail in different forms during operation. In order to study the influence of vibration isolator failure on vehicle operation performance and Floating Slab Track structure vibration reduction effectiveness, a rigid-flexible coupling dynamic model of vehicle-rail-Floating Slab Track is established by multibody dynamics and finite element simulation, and the rationality of the model and its parameters is verified by comparing the theoretical calculation results with the measured data. Based on the model, the failure conditions of steel spring are simulated, considering the failure position and number of steel springs. The results show that the failures of steel-spring vibration isolators have a significant impact on operating safety and stability of vehicle, and the failure at end is more dangerous than that at midspan. In addition, it also changes the local restraint state of Floating Slab, resulting in the local vibration mode, which reduces the Floating Slab Track structure vibration reduction effectiveness, mainly within 10 Hz. The different numbers of steel-spring failures will change the natural modal frequency of Floating Slab to varying degrees, which may cause the resonance of a certain frequency of the vehicle-Track coupling system, leading to other Track structure diseases.
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A theoretical study on the train-induced vibrations of a semi-active magneto-rheological steel-spring Floating Slab Track
Construction and Building Materials, 2019Co-Authors: Kai Wei, Zhao Zeming, Du Xianggang, Ping WangAbstract:Abstract In order to further improve the vibration-reduction effect of a steel-spring Floating Slab Track (FST), especially at the inherent frequency of a steel-spring FST, semi-active magneto-rheological (MR) dampers were applied to support a Floating Slab in a traditional steel-spring FST. Based on the experimental study and the proposed theoretical model of the MR dampers with a simple semi-active control method, a vertical vehicle-magneto-rheological steel-spring FST coupled dynamic model was established. The proposed dynamic model was used for a safety analysis and a vibration-reduction evaluation to theoretically validate the feasibility of semi-active magneto-rheological steel-spring FST. It was concluded that the introduction of semi-active MR dampers to support a Floating Slab in a traditional steel-spring FST has no impact on the security of subway vehicles running on FST. MR dampers with a semi-active control strategy can effectively not only improve the vibration-reduction effect at the basic frequency of a steel-spring FST, but also they can also suppress the vibration-amplification negative effect under a Floating Slab above the basic frequency of a steel-spring FST. There are the two key parameters of the maximum MR damping force and the displacement threshold in a semi-active magneto-rheological steel-spring FST. The larger MR damping force can deteriorate the negative vibration-suppression effect under a Floating Slab above the inherent frequency of the FST, while the higher displacement threshold can decrease the vibration-attenuation velocity of the FST supporting force.
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Engineered metabarrier as shield from longitudinal waves: band gap properties and optimization mechanisms
Journal of Zhejiang University-SCIENCE A, 2018Co-Authors: Xi Sheng, Caiyou Zhao, Ping Wang, Xing MengtingAbstract:Phononic crystals that prevent the propagation of waves in a band gap have been widely applied in wave propagation control. In this paper, we propose the use of a metabarrier, based on a locally resonant phononic crystal mechanism, as a Floating-Slab Track bearing to shield the infrastructure in a Floating-Slab Track system from longitudinal waves from the Slab, thereby improving mitigation of ground-borne vibrations. The locally resonant band gap properties of the metabarrier were studied based on the finite element method, and the shielding performance was verified by the transmission spectrum. Simplified models for band gap boundary frequencies were built according to the wave modes. Furthermore, a 3D half-Track model was built to investigate the overall vibration mitigation performance of the Floating-Slab Track with the metabarrier. An optimization mechanism for the band gap boundary frequencies is proposed. As the low-frequency ground-borne vibrations induced by subways carry the most energy, multi-objective genetic algorithm optimization was conducted to obtain a lower and wider band gap for a better shielding performance. The results show that the retained vibration isolation performance of the low natural frequency, the shielding performance of the band gap, and the controllability of band gap boundary frequencies all contribute to an improvement in overall vibration mitigation performance. The vertical static stiffness of the metabarrier was close to that of the existing bearing of the Floating-Slab Track. An optimized locally resonant band gap from 50 to 113 Hz was generated using the optimization mechanism.
Kai Wei - One of the best experts on this subject based on the ideXlab platform.
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vibration response analysis of Floating Slab Track supported by nonlinear quasi zero stiffness vibration isolators
Journal of Zhejiang University Science, 2021Co-Authors: Zeming Zhao, Kai Wei, Juanjuan Ren, Ping WangAbstract:To improve the low-frequency vibration reduction effect of a steel spring Floating Slab Track (FST), nonlinear quasi-zero-stiffness (QZS) vibration isolators composed of positive stiffness elements (PSEs) and negative stiffness elements (NSEs) were used to support the FST. First, considering the mechanical characteristics of the nonlinear QZS vibration isolators and the dynamic displacement limit (3 mm) of the FST, the feasible parameter groups were studied with the nonlinear stiffness variation range and bearing capacity as evaluation indices. A vertical vehicle-quasi-zero-stiffness Floating Slab Track (QZS-FST) coupled dynamic model was then established. To obtain a reasonable nonlinear stiffness within a few millimeters, the original length of the NSEs must be analyzed first, because it chiefly determines the stiffness nonlinearity level. The compression length of the NSEs at the equilibrium position must be determined to obtain the low stiffness of the Floating Slab without vehicle load. Meanwhile, to meet the dynamic displacement limit of the FST, the PSE stiffness must be increased to obtain a higher stiffness at the critical dynamic displacement. Various stiffness groups for the PSEs and NSEs can provide the same dynamic bearing capacity and yet have a significantly different vibration reduction effect. Excessive stiffness nonlinearity levels cannot effectively improve the vibration reduction effect at the natural frequency. Furthermore, they also significantly amplify the vibrations above the natural frequency. In this paper, the vertical vibration acceleration level (VAL) of the Floating Slab and the supporting force of the FST can be decreased by 6.9 dB and 55%, respectively, at the resonance frequency.
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A theoretical study on the train-induced vibrations of a semi-active magneto-rheological steel-spring Floating Slab Track
Construction and Building Materials, 2019Co-Authors: Kai Wei, Zhao Zeming, Du Xianggang, Ping WangAbstract:Abstract In order to further improve the vibration-reduction effect of a steel-spring Floating Slab Track (FST), especially at the inherent frequency of a steel-spring FST, semi-active magneto-rheological (MR) dampers were applied to support a Floating Slab in a traditional steel-spring FST. Based on the experimental study and the proposed theoretical model of the MR dampers with a simple semi-active control method, a vertical vehicle-magneto-rheological steel-spring FST coupled dynamic model was established. The proposed dynamic model was used for a safety analysis and a vibration-reduction evaluation to theoretically validate the feasibility of semi-active magneto-rheological steel-spring FST. It was concluded that the introduction of semi-active MR dampers to support a Floating Slab in a traditional steel-spring FST has no impact on the security of subway vehicles running on FST. MR dampers with a semi-active control strategy can effectively not only improve the vibration-reduction effect at the basic frequency of a steel-spring FST, but also they can also suppress the vibration-amplification negative effect under a Floating Slab above the basic frequency of a steel-spring FST. There are the two key parameters of the maximum MR damping force and the displacement threshold in a semi-active magneto-rheological steel-spring FST. The larger MR damping force can deteriorate the negative vibration-suppression effect under a Floating Slab above the inherent frequency of the FST, while the higher displacement threshold can decrease the vibration-attenuation velocity of the FST supporting force.
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Analysis of vibration reduction characteristics and applicability of steel-spring Floating-Slab Track
Journal of Modern Transportation, 2011Co-Authors: Wanming Zhai, Kai WeiAbstract:A coupled dynamics computation model for metro vehicles, along with a steel-spring Floating-Slab Track, is developed based on the theory of vehicle-Track coupled dynamics. Using the developed model, the influences of the thickness, length and mass of Floating-Slab, spring rate and its arrangement space, running speed, etc. on the time and frequency domain characteristics of steel-spring fulcrum force are analyzed. The applicability of steel-spring Floating-Slab Track is discussed through two integrated example cases of metro and buildings possessing distinct natural vibration characteristics. It is concluded that, it is quite significant, in the optimization modular design of the parameters of steel-spring Floating-Slab Track, to take the matching relationship of both the amplitude-frequency characteristics of steel-spring fulcrum force and natural vibration characteristics of integrated structures into comprehensive consideration. In this way the expensive steel-spring Floating-Slab Track can be economically and efficiently utilized according to the site condition, and at the same time, the economic losses and bad social impact resulted from the resonance during usage of steel-spring Floating-Slab Track can be avoided.
Wanming Zhai - One of the best experts on this subject based on the ideXlab platform.
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Development of a Track dynamics model using Mindlin plate theory and its application to coupled vehicle-Floating Slab Track systems
Mechanical Systems and Signal Processing, 2020Co-Authors: Jun Luo, Shengyang Zhu, Wanming ZhaiAbstract:Abstract Unlike Track Slabs in high speed railways, Floating Slabs in metro lines are usually relatively thicker and their thickness can often reach 0.5 m or more. When the thickness of the Track Slab is relatively large compared to the length and width, the influence of shear effect and rotatory inertia will become significant and it is more reliable to regard the Track Slab as an elastic thick plate than adopt the classical thin plate model in the simulation. This paper presents a three-dimensional dynamic model for coupled vehicle-Floating Slab Track (CVFST) systems on the basis of Mindlin plate theory for the first time. The Floating Slab is described as an elastic rectangle Mindlin plate with free boundary conditions resting on steel springs, the mode shapes of the Mindlin plate are approximated by series of products of Timoshenko beam functions, and the corresponding vibration equations are solved by Rayleigh-Ritz method in time domain. The vehicle subsystem and Track subsystem are coupled via wheel-rail nonlinear interactions. The effectiveness of the proposed model is validated by comparing with the measured data from an impact test and numerical results in the previous literature. Influence of size effect on the Slab natural frequencies and dynamic responses of the CVFST system are investigated, and discrepancies of the calculation results between the developed model and the traditional thin plate model are simultaneously discussed. Some practical conclusions are drawn and the developed model may serve as a potent tool for more accurate assessment of train-induced vibrations in metro lines.
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Investigation of the vibration isolation performance of Floating Slab Track with rubber bearings using a stochastic fractional derivative model
Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit, 2019Co-Authors: Xuancheng Yuan, Shengyang Zhu, Wanming ZhaiAbstract:Floating Slab Track is an effective countermeasure to mitigate undesirable vibrations caused by metro trains. In this work, a stochastic fractional derivative model is proposed for simulating the d...
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Dynamic Analysis on Stiffness Enhancement Measures of Slab End for Discontinuous Floating Slab Track
Computing in Science & Engineering, 2019Co-Authors: Jianjin Yang, Wanming Zhai, Kaiyun Wang, Shengyang Zhu, Kai Lan, Xuancheng YuanAbstract:The Slabs of a Floating Slab Track (FST) are usually discontinuously constructed, resulting in a gap between the consecutive Slabs. Therefore, wheel/rail impact may occur when a train runs over the gap, resulting in an adverse effect on the train and Track system. In this regards, the stiffness enhancement measure (SEM) is usually used at Slab ends to enable a smooth stiffness change. The SEM normally includes installing end connections between consecutive Slabs and increasing the supporting stiffness of Slab ends. For estimating the influence of SEMs on dynamic behaviors of train and FST systems, a detailed and efficient coupled dynamic model of the train–FST system with the SEMs is first developed. Furthermore, the influences of the two SEMs on the system dynamic performance are revealed by using the proposed model. Finally, the optimal parameter combination of the two SEMs is determined, which provide a valuable guiding reference for the design of the FST.
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Analysis of vibration reduction characteristics and applicability of steel-spring Floating-Slab Track
Journal of Modern Transportation, 2011Co-Authors: Wanming Zhai, Kai WeiAbstract:A coupled dynamics computation model for metro vehicles, along with a steel-spring Floating-Slab Track, is developed based on the theory of vehicle-Track coupled dynamics. Using the developed model, the influences of the thickness, length and mass of Floating-Slab, spring rate and its arrangement space, running speed, etc. on the time and frequency domain characteristics of steel-spring fulcrum force are analyzed. The applicability of steel-spring Floating-Slab Track is discussed through two integrated example cases of metro and buildings possessing distinct natural vibration characteristics. It is concluded that, it is quite significant, in the optimization modular design of the parameters of steel-spring Floating-Slab Track, to take the matching relationship of both the amplitude-frequency characteristics of steel-spring fulcrum force and natural vibration characteristics of integrated structures into comprehensive consideration. In this way the expensive steel-spring Floating-Slab Track can be economically and efficiently utilized according to the site condition, and at the same time, the economic losses and bad social impact resulted from the resonance during usage of steel-spring Floating-Slab Track can be avoided.
Wu Tian-xing - One of the best experts on this subject based on the ideXlab platform.
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2-D Modelling of Floating Slab Track and Performance Analysis on Vibration Isolation
Journal of the China Railway Society, 2011Co-Authors: Wu Tian-xingAbstract:In order to analyze the effects of phase difference of the wheelset loads and bending vibration modes of the Slab on the vibration isolation performance of the Floating Slab Track(FST),a two-dimensional(2-D) model for the FST is developed by using the dynamic receptance method,where a rectangular Kirchhoff plate with free boundary at four edges is used to account for the Slab.The vibration isolation effectiveness of FST is investigated based on the force transmission ratio.Simulation results show that more vibration modes of the Slab are excited when the wheelset loads have some phase difference,resulting in a decrease in the vibration isolation performance around these modal frequencies.The FST with short Slab gains better vibration isolation effectiveness at medium frequencies because of less vibration modes existing with comparison to FST with long Slab.When the wheelset loads are in phase,the one-dimensional model(Euler-Bernoulli beam to account for the Slab) for FST can be used for corresponding analysis instead of the 2-D model for simplicity,without causing errors.
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Parametric excitation vibration of a Floating Slab Track
Journal of Vibration and Shock, 2010Co-Authors: Wu Tian-xingAbstract:Although a Floating Slab Track(FST) is an effective way to isolate the vibration transmitted to infrastructures,the Track's stiffness varies periodically in space due to periodic arrangement and discontinuity of Floating Slabs.This leads to a parametric excitation vibration when a train is moving over the Track at certain speed.In order to make an investigation into this issue,a vehicle-Floating Slab Track coupling model was developed in the time domain and a solution based on the modal superposition method was proposed.Then,the parametric excitation vibration of FST and its affecting factors were studied using this model.It was found that the main frequency components of such vibration were the Floating Slab passing frequency and its multiples;with the train speeding up or the natural frequency of the Floating Slab isolation system decreasing,the wheel/rail dynamic interaction force increased,and its peak-to-peak value was about 75% of the static wheel/rail load when the vehicle run over the FST with natural frequency of 10 Hz or 6 Hz at a speed of 60 m/s;whereas,there existed a critical value of the single Slab length,it corresponded to the larger wheel/rail dynamic interaction force as the single Slab length changed;moreover,adjusting the installation location and the stiffness of the Slab vibro-isolator could decrease the Track variation;as a result,the wheel/rail dynamic load from the parametric excitation vibration decreased.
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On Vibration Isolation Performance of Floating Slab Track
Journal of Shanghai Jiaotong University, 2007Co-Authors: Wu Tian-xingAbstract:In order to analyze the dynamic behavior of Floating Slab Track(FST),two kinds of model were developed for the FST system on the base of structure dynamics.The vibration isolation performance of the Track with short and long Floating Slab was calculated and compared using the developed models.It is found that the FST can effectively isolate the vibration transmitted from the rail to the infrastructure.The Track with long Floating Slab shows better performance than that with short Floating Slab in terms of vibration(isolation) at the forcing position,whereas the vibration decays more quickly in the Track with short Floating Slab.The lower the natural frequency of the FST is,the better the performance of vibration isolation is.Both increasing the mass and reducing the support stiffness of the Slab can reduce the natural frequency of the FST system to achieve better performance of vibration isolation.
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Study on the vibration isolation performance of Floating Slab Track using dynamic receptance method
Journal of Vibration Engineering, 2007Co-Authors: Wu Tian-xingAbstract:According to the structural characteristics of the Floating Slab Track(FST),a new model,which effectively reflects the dynamic behaviour of the FST,is proposed in this study and a dynamic receptance method is developed to solve the FST model.The vibration isolation performance of the FST and the factors affecting the performance are analyzed by numerical simulations.It is found that the FST presents a good capability to isolate the Track vibration in the frequency range above the system's natural frequency.In the middle frequency range over the natural frequency,the performance of the FST is affected by the dynamic behaviour of the single Floating Slab.For the Slabs with different lengths,the attenuations along the Tracks of the forces transmitted from the FST to the infrastructures are similar.However,the force transmitted to the infrastructure from one Slab to the neighbouring Slab decays very quickly in the high frequency range.In addition,the performance of vibration isolation becomes slightly poorer when the excitation acts above the Slab boundary,but at most other positions it is similar.
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On effectiveness of vibration isolation for super-elastic rail support combined with booted sleeper or Floating Slab Track
Journal of Vibration Engineering, 2007Co-Authors: Wu Tian-xingAbstract:Ground vibration or structural vibration of viaduct due to railway traffic can be reduced by use of super-elastic rail support,booted sleeper and Floating Slab to isolate vibration transmission from the Track to the infrastructure. In this study modeling in the frequency domain of Track structure and wheel/rail interaction is carried out.Wheel/rail interaction and transmission to the infrastructure of the interaction force due to relative displacement excitation are simulated.The effectiveness of vibration isolation is analyzed for booted sleeper or Floating Slab combined with super-elastic rail fastener.It is found that the combination of super-elastic rail fastener with booted sleeper or Floating Slab can effectively reduce the wheel/rail interaction force in the medium frequencies,compared with the booted sleeper or Floating Slab Track using usual rail pad.The combination also shows better ability to block vibration transmission from the Track to the infrastructure in the medium and high frequencies.
Guo Pengcheng - One of the best experts on this subject based on the ideXlab platform.
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Piezoelectric vibration energy harvesting for rail transit bridge with steel-spring Floating Slab Track system
Journal of Cleaner Production, 2020Co-Authors: Wenqi Hou, Yong Zheng, Wei Guo, Guo PengchengAbstract:Abstract Taking two (4 × 40) m continuous rail transit rigid bridges as practical examples, the train-SSFST (steel-spring Floating Slab Track)-bridge system was established to acquire the vehicle induced vibration responses on SSFST. Based on the concept of combing cymbal PE-VEH and multilayer stacks PE-VEH together, a kind of PE-VEH featured small size, lightweight, high bearing capacity and excellent efficiency in energy harvesting is proposed. The prominent highlight of the designed PE-VEH is the force amplifying mechanism composed of cover plates and bending plates, which is of great help in improving the energy harvesting efficiency. Secondly, the 6 multilayer piezoelectric stacks are favorable to meet the requirements of small dimensions when bearing the vehicle induced vertical steel-spring fulcrum forces. Dynamic simulation results showed that the optimum positions for the designed PE-VEH to be connected in series with the steel-springs is at the end of the Floating concrete Slab (FCS). Comparing with existed low-frequency PE-VEHs through evaluating by indicators of power density and NPD, the excellent energy output efficiency of the designed PE-VEH is demonstrated, and influence on the practical train-SSFST-bridge system is negligible as well. For the example bridge, with 144 PE-VEHs arranged on 36 blocks of FCS, the total energy power obtained would reach up to 31.4 kJ, enough to satisfy the normal use of intermittent collection and transmission components for wireless BHM.