An Efficient Approach for Stochastic Vibration Analysis of High-Speed Maglev Vehicle-Guideway System

2021 ◽  
pp. 2150080
Author(s):  
Zhiwu Yu ◽  
Peng Zhang ◽  
Jianfeng Mao ◽  
Pol D. Spanos ◽  
Y. Frank Chen
Keyword(s):  
Vibration Analysis ◽  
High Speed ◽  
Random Vibration ◽  
Random Model ◽  
Dynamic Responses ◽  
Stochastic Dynamic ◽  
Time Step ◽  
Good Efficiency ◽  
Efficient Approach ◽  
Maglev Vehicle

The high-speed maglev vehicle-guideway coupled system (MVGCS) is a complex system, whose random vibration characteristics have not been well studied due to a limited number of examples. To address this issue, a new efficient approach is proposed for the random vibration analysis of the MVGCS, which combines the probability density evolution method and multi-time step method with multiple random loads considered. The random model established for 10-degree-of-freedom maglev vehicles and guideway is time-dependent, considering two different supporting conditions. The Monte Carlo method is used to assess the accuracy and efficiency of the proposed approximate approach, and the random model is verified through comparison with available results. The stochastic dynamic responses of the vehicles, guideway, and electromagnetic levitation forces, including the mean values and standard deviations, are determined in a case study. The results show that the proposed method is feasible for the dynamic analysis of maglev systems with a reasonably good efficiency in computation. Furthermore, critical parametric analyses involving vehicle speed, irregularity, and cut-off wavelength are performed with the results discussed.

Random Vibration Analysis of the Underframe Structure on a High-Speed Train

ICTE 2015 ◽  
2015 ◽  
Author(s):  
Hanfei Guo ◽  
Xiaoxue Liu ◽  
Wei Tong ◽  
Youwei Zhang ◽  
Yanlei Zhang
Keyword(s):  
Vibration Analysis ◽  
High Speed ◽  
Random Vibration ◽  
High Speed Train ◽  
Random Vibration Analysis

scholarly journals Explicit Time-Domain Approach for Random Vibration Analysis of Jacket Platforms Subjected to Wave Loads

2020 ◽  
Vol 8 (12) ◽  
pp. 1001
Author(s):  
Wei Lin ◽  
Cheng Su ◽  
Youhong Tang
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Time Domain ◽  
Vibration Analysis ◽  
Random Vibration ◽  
Present Approach ◽  
Dynamic Responses ◽  
Wave Loads ◽  
Morison Equation ◽  
Random Vibration Analysis

This paper is devoted to the random vibration analysis of jacket platforms under wave loads using the explicit time-domain approach. The Morison equation is first used to obtain the nonlinear random wave loads, which are discretized into random loading vectors at a series of time instants. The Newmark-β integration scheme is then employed to construct the explicit expressions for dynamic responses of jacket platforms in terms of the random vectors at different time instants. On this basis, Monte Carlo simulation can further be conducted at high efficiency, which not only provides the statistical moments of the random responses, but also gives the mean peak values of responses. Compared with the traditional power spectrum method, nonlinear wave loads can be readily taken into consideration in the present approach rather than using the equivalent linearized Morison equation. Compared with the traditional Monte Carlo simulation, the response statistics can be obtained through the direct use of the explicit expressions of dynamic responses rather than repeatedly solving the equation of motion. An engineering example is analyzed to illustrate the accuracy and efficiency of the present approach.

scholarly journals Random Vibration Analysis of Coupled Three-Dimensional Maglev Vehicle-Bridge System

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Wei Liu ◽  
Wenhua Guo
Keyword(s):  
State Space ◽  
Governing Equation ◽  
Vibration Analysis ◽  
Random Vibration ◽  
Three Dimensional ◽  
Equation Of Motion ◽  
Maglev Vehicle ◽  
Random Vibration Analysis ◽  
Space Equation ◽  
Bridge System

This paper presents a framework for the linear random vibration analysis of the coupled three-dimensional (3D) maglev vehicle-bridge system. Except for assembling the equation of motion of vehicle only via the principle of virtual work, the fully computerized approach is further expanded to assemble the governing equation of fluctuating current via the equilibrium relation. A state-space equation couples the equation of motion of the vehicle and the governing equation of fluctuating current. The equation of motion of a real three-span space continuous girder bridge is established by using finite element methods. A separated iteration method based on the precise integration method and the Newmark method is introduced to solve the state-space equation for the maglev vehicle and the equation of motion for the bridge. Moreover, a new scheme to application of the pseudoexcitation method (PEM) in random vibration analysis is proposed to maximize the computational efficiency of the random vibration analysis of the maglev vehicle-bridge system. Finally, the numerical simulation demonstrates that the proposed framework can efficiently obtain the mean value, root mean square (RMS), standard deviation (SD), and power spectral density (PSD) of dynamic response for the coupled 3D maglev vehicle-bridge system.

Nonlinear Response of Carbon-Carbon Composite Panels Subjected to Thermal-Acoustic Loadings

2011 ◽  
Vol 117-119 ◽  
pp. 876-881 ◽  
Author(s):  
Yun Dong Sha ◽  
Fei Xu ◽  
Zhi Jun Gao
Keyword(s):  
High Speed ◽  
Random Vibration ◽  
Nonlinear Response ◽  
Elevated Temperatures ◽  
Thermal Protection ◽  
Random Noise ◽  
Carbon Composite ◽  
Dynamic Responses ◽  
Composite Panels ◽  
Thin Walled

Carbon-Carbon composite materials are widely used as the surface thermal protection systems (TPS) of advanced high-speed air-craft and spacecraft. The thin-walled structures with this kind of materials would exhibit large displacement response under high-level acoustic loads and possibly display buckling at elevated temperatures. Reliable experimental data are difficult to acquire because of the high costs and difficulties with instrumentation at high acoustic intensity and elevated temperatures. Thus, in the design process greater emphasis will likely be placed on improved mathematical and computational prediction methods. Among these researches, the simulation methods for nonlinear response of thin-walled composite panels under thermo-acoustic loadings are being developed emphatically .This paper presents a nonlinear finite element model for analyzing nonlinear random dynamic behaviors of Carbon-Carbon composite panels under the combined effects of thermal and random acoustic loads. The acoustic excitation is assumed to be a band-limited Gaussian random noise and uniformly distributed over the structural surface and the thermal load is assumed to be a steady-state with different predefined temperature distribution. Three types of motion: 1) linear random vibration about one of the two buckled positions, 2) snap-through motion between the two buckled positions, and 3) nonlinear random vibration over the two thermally buckled positions can be predicted. And the dynamic response behaviors of the structures are discussed. Based on this, the influences of sound pressure level (SPL) and elevated temperatures on the dynamic responses are analyzed emphatically.

Comparative Studies on the Dynamic Performances of High Speed Turbocharger Rotor Supported on Oil-Free Bearings Versus Conventional Floating Ring Systems

2017 ◽  
Author(s):  
Rajasekhara Reddy Mutra ◽  
J. Srinivas
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Equations Of Motion ◽  
Dynamic Modelling ◽  
Dynamic Responses ◽  
Effect Of Temperature ◽  
Time Step ◽  
Foil Bearing ◽  
Dynamic Performances ◽  
Bearing System

Present work focuses on the dynamic modelling of the dual-disc rotor supported on oil-free bearings idealizing a turbocharger rotor bearing system. The equations of motion of the rotor system are formulated and solved by finite element method to obtain the dynamic response of the system. The gas-foil bearing forces obtained from finite-difference approach at each time-step of solution. The same rotor model is used with the conventional floating ring bearing system where, the bearing forces are provided as displacement dependent time-varying oil and floating ring forces. As a practical environmental condition, the effect of temperature on the viscosity is studied using Dowson equation. The dynamic responses are illustrated both for rotor supported on both gas-foil and floating-ring type bearings. The effects of changes in bearing clearances on the overall dynamic characteristics of the rotor are reported. In order to utilize the gas foil bearing model, an identification study is performed to predict the operating clearance and air viscosity using dynamic response data.

Dynamic Analysis of a Coupled System of High-Speed Maglev Train and Curved Viaduct

2018 ◽  
Vol 18 (11) ◽  
pp. 1850143 ◽  
Author(s):  
Z. L. Wang ◽  
Y. L. Xu ◽  
G. Q. Li ◽  
S. W. Chen ◽  
X. L. Zhang
Keyword(s):  
Dynamic Analysis ◽  
High Speed ◽  
Coupled System ◽  
Dynamic Responses ◽  
Global Coordinate System ◽  
Maglev Train ◽  
Horizontally Curved ◽  
Maglev Vehicle ◽  
Initial Equilibrium State ◽  
Stiffness And Damping

This study presents a framework for dynamic analysis of a coupled system of high-speed maglev train and curved viaduct. A series of trajectory coordinates are used to define the motion of maglev vehicles moving over a horizontally curved track, the stiffness and damping matrices of the equations can be thus reduced into those of the straight track. The curved viaduct system is modeled in the global coordinate system using the finite element method, in which the inner and outer rails in the different horizontal planes are duly included. The electromagnet force-air gap model is adopted for the maglev vehicle via its electromagnets and rails on the viaduct, by appropriate transformation of coordinates. By applying the proposed framework to the Shanghai maglev line, curved path-induced dynamic responses and characteristics of the vehicle are explored, which agree well with the measurement ones. The dynamic responses of the curved viaduct are also examined in the vertical, lateral and rotational directions by comparison with the straight viaduct. Moreover, the effect of various curve radii and cant deficiencies on the coupled system are investigated. The results show that for a maglev vehicle moving with an initial equilibrium state, its lateral and rotational response are mainly excited by track roughness. In addition to the track radius, cant deficiencies significantly affect the operational safety of the viaduct.

Statistical Linearization of Nonlinear Stiffness Matrix of Planetary Gear Train

2017 ◽  
Author(s):  
Jalal Taheri Kahnamouei ◽  
Jianming Yang
Keyword(s):  
Stiffness Matrix ◽  
Random Vibration ◽  
Planetary Gear ◽  
Small Time ◽  
Gear Train ◽  
Statistical Linearization ◽  
Stochastic Dynamic ◽  
Nonlinear Stiffness ◽  
Time Step ◽  
Planetary Gear Train

Stochastic dynamic analysis of the planetary gear train is complicated and it becomes more challenging when the nonlinear term is considered in the equation. A backlash between gears’ teeth is one of the nonlinearity sources in the gearbox which changes the equation of random vibration to nonlinear. In this paper, the linearization of the random vibration of multi-degrees of freedom (MDOF) with nonlinear stiffness is examined for planetary gear trains. The method used to treat nonlinearity is the statistical linearization method (SL). At first, to achieve adequate accuracy, the time domain is divided into very small time intervals then SL is utilized in each time step. For each time step an equivalent linear stiffness matrix is calculated and replacs the nonlinear stiffness matrix. The comparison between equivalent stiffness and linear stiffness at each step has shown a good agreement.

Vibration Analysis of a Flexibly Connected Double Span Beam Traversed by Uniformly Distributed Moving Load

2011 ◽  
Vol 71-78 ◽  
pp. 375-378
Author(s):  
Yu Yang ◽  
Yun Fang Yang ◽  
Qi Mao Cai
Keyword(s):  
Vibration Analysis ◽  
High Speed ◽  
Moving Load ◽  
Transportation Systems ◽  
Vertical Vibration ◽  
Dynamic Responses ◽  
Superposition Method ◽  
Mode Superposition Method ◽  
Distributed Load ◽  
Duhamel Integral

Considering the engineering background of high speed transportation systems such as maglev, vertical vibration of a flexibly connected double span beam is studied. The beam can be taken as two Euler-Bernoulli beams flexibly connected by an elastic joint and the model of it bearing moving distributed load with constant speed is then established. Duhamel integral as well as mode superposition method is applied to solve the dynamic responses of the beam. Numerical analysis base on different parameters such as the length of the train, the span of the beam and the velocity of the train are compared. The following conclusions are made:(1) the left span and right span’s dynamic responses is different so that each span should be analyzed separately; (2)the dynamic response of the beam is tied up with the factors such as the frequency of the beam, the moving frequency of the load and the relative bending stiffness of the joint.

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