scholarly journals Vibration Characteristics of Subway Tunnel Structure in Viscous Soil Medium

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Dawei Ren ◽  
Shengjun Shao ◽  
Xiaoshan Cao ◽  
Yifeng Hu
Keyword(s):  
Natural Vibration ◽  
Equation Of Motion ◽  
Vibration Characteristics ◽  
Natural Vibration Frequency ◽  
Tunnel Structure ◽  
Subway Tunnel ◽  
Soil Medium ◽  
Control Equation ◽  
Subway Tunnels ◽  
Variation Trends

Based on research on subway tunnels in a viscous soil medium, this paper establishes the vibration equation of a tunnel structure by using the theory of moderately thick cylindrical shells and the method of wave propagation. The soil around the tunnel is represented in simplified form as an isotropic viscoelastic medium to obtain the equation of motion of the soil, and the vibration control equation of the tunnel under the influence of viscous soil is obtained by coupling. By numerical calculations, the variation trends in the natural vibration frequency of the tunnel and attenuation affected by soil viscosity under different modes are given. Furthermore, the influences of the tunnel radius, wall thickness, and length on the vibration characteristics of a tunnel structure in viscous soil are discussed. This study will provide a reference for the design of subway vehicles and the antivibration design of subway tunnel structures.

Research of Test Method for the Natural Vibration Frequency of Bogie

2012 ◽  
Vol 503-504 ◽  
pp. 1050-1054 ◽  
Author(s):  
Xiu Gang Wang ◽  
Zheng Ji ◽  
Jian Su ◽  
Xiao Ning Cao ◽  
Meng Meng Li
Keyword(s):  
Vibration Frequency ◽  
Inverse Kinematics ◽  
Natural Vibration ◽  
Test Bench ◽  
Geometric Theory ◽  
Vibration Characteristics ◽  
Test Method ◽  
Solution Model ◽  
Natural Vibration Frequency ◽  
Natural Vibration Characteristics

In order to determine the，a test bench for the natural vibration characteristics of the bogie suspension was put forward. Firstly the natural vibration characteristics structure composition and the testing principle was introduced, the sine sweep incentive was simulated, and the inverse kinematics solution model and the real-time solution model were developed. The Comparison of the simulation result and the geometric theory results was carried out, proving the accuracy of the inverse kinematics solution model and the simulation model.

Modal analysis and experimental investigation into vibration of the diamond-beaded rope based on lumped mass

2021 ◽  
pp. 146134842110383
Author(s):  
Mengguang Fu ◽  
Peng Zhang ◽  
Fei Wang
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Natural Vibration ◽  
Vibration Characteristics ◽  
Lumped Mass ◽  
Key Factor ◽  
Control Equation ◽  
Multi Body ◽  
Natural Vibration Characteristics

The natural vibration characteristics of the diamond-beaded rope (DBR) based on lumped mass are analyzed both theoretically and experimentally. The dynamic model of the DBR is established by means of the multi-body dynamics theory. According to Lagrange’s equations, the control equation of the DBR is derived. It mainly analyzes the influence of the parameters, such as the motion velocity of the DBR, the tension of the DBR, the length of diamond beads, the quality of diamond beads, and their position in the DBR, on the natural vibration characteristics for the DBR are studied. The results show that the natural frequencies and the corresponding vibration shapes of the DBR based on lumped mass change significantly when the variations of the above parameters are considered. In the process of the movement of the DBR, the random impact force of diamond beaded is the key factor that causes the natural frequency of the DBR to fluctuate., In the high-order modal analysis, the natural frequency and vibration mode of the DBR fluctuate more obviously. The relative error of the result between the calculated and the measured is less than 10%, which validates the proposed method.

scholarly journals Theoretical, Numerical, and Experimental Study on the Identification of Subway Tunnel Structural Damage Based on the Moving Train Dynamic Response

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7197
Author(s):  
Hongqiao Li ◽  
Xiongyao Xie ◽  
Yonglai Zhang ◽  
Qiang Wang
Keyword(s):  
Structural Damage ◽  
Damage Index ◽  
Monitoring Program ◽  
Urban Rail Transit ◽  
Practical Significance ◽  
Current Status ◽  
Vehicle Speed ◽  
Tunnel Structure ◽  
Subway Tunnel ◽  
Subway Tunnels

As an important part of urban rail transit, subway tunnels play an important role in alleviating traffic pressure in mega-cities. Identifying and locating damage to the tunnel structure as early as possible has important practical significance for maintaining the long-term safe operation of subway tunnels. Summarizing the current status and shortcomings of the structural health monitoring of subway tunnels, a very economical and effective monitoring program is proposed, which is to use the train vibration response to identify and locate the damage of the tunnel structure. Firstly, the control equation of vehicle–tunnel coupling vibration is established and its analytical solution is given as the theoretical basis of this paper. Then, a damage index based on the cumulative sum of wavelet packet energy change rate (TDISC) is proposed, and its process algorithm is given. Through the joint simulation of VI-Rail and ANSYS, a refined 3D train-tunnel coupled vibration model is established. In this model, different combined conditions of single damage and double damage verify the validity of the damage index. The effectiveness of this damage index was further verified through model tests, and the influence of vehicle speed and load on the algorithm was discussed. Numerical simulation and experimental results show that the TDISC can effectively locate the damage of the tunnel structure and has good robustness.

scholarly journals Stochastic Natural Vibration Analyses of Free-Form Shells

2019 ◽  
Vol 9 (15) ◽  
pp. 3168
Author(s):  
Bingbing San ◽  
Yunlong Ma ◽  
Zhi Xiao ◽  
Dongming Feng ◽  
Liwei Yin
Keyword(s):  
Elastic Modulus ◽  
Shape Optimization ◽  
Shell Thickness ◽  
Natural Vibration ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Free Form ◽  
Probability Models ◽  
Geometric Imperfection ◽  
Natural Vibration Characteristics

This work investigates the natural vibration characteristics of free-form shells when considering the influence of uncertainties, including initial geometric imperfection, shell thickness deviation, and elastic modulus deviation. Herein, free-form shell models are generated while using a self-coded optimization algorithm. The Latin hypercube sampling (LHS) method is used to draw the samplings of uncertainties with respect to their stochastic probability models. ANSYS finite element (FE) software is adopted to analyze the natural vibration characteristics and compute the natural frequencies. The mean values, standard deviations, and cumulative distributions functions (CDFs) of the first three natural frequencies are obtained. The partial correlation coefficient is adopted to rank the significances of uncertainty factors. The study reveals that, for the free-form shells that were investigated in this study, the natural frequencies is a random quantity with a normal distribution; elastic modulus deviation imposes the greatest effect on natural frequencies; shell thickness ranks the second; geometrical imperfection ranks the last, with a much lower weight than the other two factors, which illustrates that the shape of the studied free-form shells is robust in term of natural vibration characteristics; when the supported edges are fixed during the shape optimization, the stochastic characteristics do not significantly change during the shape optimization process.

The Application of BESO in Vibration Damping of Ship Plate

2013 ◽  
Vol 572 ◽  
pp. 185-188 ◽  
Author(s):  
Xiao Yan Teng ◽  
Jia Shan Han ◽  
Liang Peng
Keyword(s):  
Natural Vibration ◽  
Target Function ◽  
Vibration Damping ◽  
Natural Vibration Frequency ◽  
Constraint Condition ◽  
Evolutionary Structural Optimization ◽  
Damping Material ◽  
Reasonable Result ◽  
Beso Method ◽  
Original Amount

Based on the bi-directional evolutionary structural optimization (BESO), the method of determining the adhesion position of the damping material is proposed in this paper, which is applicable to the vibration damping of ship plate. In this method, the needed amount of damping material is taken as the constraint condition, and the maximization of one natural vibration frequency of the structure is taken as the target function. A thin plate structure with both ends constraints has been taken as an example to get the best topology structure of its adhesion damper by taking the BESO method. The result of optimization shows that it still meets the damping requirements when the needed amount of damping material decreases by about 50% of the original amount. The reasonable result demonstrates the effectiveness and engineering value of the method.

Study on the Influence of Reactor Core Structure on Reactor Natural Vibration Frequency

2021 ◽  
Author(s):  
Yuan Zhou ◽  
Tian Tian ◽  
Xiongfei Yu ◽  
Ran Ren ◽  
Liangcai Zhou ◽  
...  
Keyword(s):  
Vibration Frequency ◽  
Natural Vibration ◽  
Reactor Core ◽  
Core Structure ◽  
Natural Vibration Frequency

scholarly journals Analysis of the natural oscillation frequency of the long-span trusses with flanged connections

2021 ◽  
pp. 76-85
Author(s):  
Татьяна Георгиевна Рытова ◽  
Людмила Анатольевна Максимова ◽  
Анастасия Георгиевна Николаева ◽  
Татьяна Михайловна Макарова ◽  
Надежда Георгиевна Пфаненштиль
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Frequency ◽  
Natural Vibration ◽  
Natural Oscillation ◽  
Natural Vibration Frequency ◽  
Building Structures ◽  
Long Span ◽  
Local Areas ◽  
Calculation Results ◽  
Natural Oscillation Frequency

Приводится анализ частоты собственных колебаний большепролетной фермы с фланцевыми соединениями. Выполнен расчет фланцевого соединения с различными случаями исключения болтов из работы соединения. Анализ результата расчета показал, что возникновение повреждений и дефектов конструкций здания в локальных зонах, величина которых несущественно снижает общую жесткость каркаса, практически не влияет на динамические характеристики каркаса. The analysis of the natural vibration frequency of a large-span truss with flanged connections is given. The calculation of the flange connection with various cases of exclusion of bolts from the connection operation is performed. Analysis of the calculation results showed that the occurrence of damage and defects in the building structures in local areas, the value of which significantly reduces the overall rigidity of the frame, practically does not affect the dynamic characteristics of the frame.

Study on Natural Vibration Characteristics Based on the Coupled Wave Theory of Spring Supported Elastic Pipes and Fluids

2020 ◽  
Author(s):  
Takeshi Tokunaga ◽  
Koji Mori ◽  
Hiroko Kadowaki ◽  
Takashi Saito
Keyword(s):  
Boundary Condition ◽  
Blood Vessel ◽  
Flow Velocity ◽  
Blood Vessels ◽  
Natural Vibration ◽  
Wave Theory ◽  
Vibration Characteristics ◽  
Elastic Pipes ◽  
Coupled Wave ◽  
Natural Vibration Characteristics

Abstract A gradient of a blood flow velocity on the surface of a blood vessel is one of the clinical medicine concerns from the view point of prevention of the arteriosclerosis. In previous study, we formulated a relationship between the pressure and a flow velocity based on the coupled wave theory of elastic pipes and Newtonian fluids [1]. In addition, a flow velocity distribution and a wall shear stress are estimated by using the blood pressure data, which are non-invasively obtained by the tonometry method. This method is quasi-analytical method to apply the coupled wave theory for industrial flow field inside steel pipes proposed by Urata [4] to blood vessel, and has the advantage of systematic estimator compared with the numerical calculation. However, the coupled wave theory has applied to the elastic pipes that were assumed to be infinitely long. In addition, a single wave was assumed to be dominant within the elastic pipes and the Newtonian fluids. Therefore, in order to apply various length vessels in clinical field, the boundary of the blood vessels that varies from site to site, and the natural vibration characteristics that depend on the boundary conditions, could not be reflected in the wall shear stress estimation. In general, in order to solve the forced vibration with the boundary condition, it is necessary to clarify natural frequency and natural mode as natural vibration characteristics of structure. In this study, we introduce the spring supported elastic pipes to the coupled wave theory and formulated a relationship between the natural vibration characteristics and the boundary conditions. In this proposed method, the spring-supported elastic pipe has a feature that can be treated as an arbitrary boundary condition of an artery by giving an appropriate spring coefficients. Therefore, it is easy to apply to various types of blood vessels clinically. By investigating the natural vibration characteristics of blood vessels that varies from site to site, it may be possible to clarify fluctuations of blood flow in response to blood pressure with some frequency-bands. In addition, natural angular frequencies and natural modes of the spring supported elastic pipes and the Newtonian fluids were estimated for general blood vessel based on the coupled wave theory. In the result, the natural angular frequencies and the natural modes that reflect the clinical vibration characteristics to some extent can be estimated. On the other hand, particular modes may not reflect boundary condition, and further examination of the relationship between natural vibration characteristics and boundary condition is needed.

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