Application of Modal Analysis on Railway Vehicles using On-track Measurements

2014 ◽  
Author(s):  
L.M. Erviti ◽  
J.G. Gimenez
Keyword(s):  
Modal Analysis ◽  
Railway Vehicles

Analysis of Instabilities in Railway Vehicles Employing Operational Modal Analysis

2015 ◽  
Author(s):  
Lara Erviti Calvo ◽  
Gorka Agirre Castellanos ◽  
Germán Gimenez
Keyword(s):  
Numerical Model ◽  
Modal Analysis ◽  
Mode Shape ◽  
Operational Modal Analysis ◽  
Mode Shapes ◽  
Correct Identification ◽  
Unstable Condition ◽  
Static Tests ◽  
Railway Vehicles ◽  
Damping Rate

The application of Operational Modal Analysis (OMA) in the railway sector opens a broad field of opportunities. The validation of the numerical model employed in the design phase is usually performed employing data obtained in static tests. The drawback is that some suspension parameters, such as dampers, only have an influence in the dynamic behavior and not in the static behavior. Because of that, the use of the mode shapes identified from track measurements in combination with the static tests leads to a more accurate validation of the numerical model. Apart from that, most passenger comfort and dynamic problems are associated to slightly damped modes. A correct identification of the modal parameters can be used as a continuous design improvement tool to improve the comfort and dynamic characteristics of future designs. Another valuable application of OMA techniques is the identification of the mode shapes corresponding to instabilities, due to the safety impact that they have. In railway vehicles, instabilities are associated to mode shapes that present a damping rate which decreases with the increase of the running speed. Above a certain speed value, the excitation coming from track cannot be damped by the vehicle and it reaches an unstable condition. This unstable condition leads to high acceleration levels experienced by the passengers and high interaction forces between the wheel and the rail that may lead to safety hazards. The speed above which the vehicle is unstable is known as critical speed, and has to be greater than the maximum speed of the vehicle with a reasonable safety margin. The use of OMA techniques allows identifying the mode shape that causes the instability. This paper presents the application of OMA techniques to measurements performed on a passenger vehicle, in which the speed was increased until the vehicle was unstable. The mode shape that caused the instability was identified as well as its corresponding natural frequency and damping rate.

Application of Operational Modal Analysis on Railway Vehicles Using on Track Measurements

2013 ◽  
Author(s):  
Lara Mª Erviti Calvo ◽  
Gorka Agirre Castellanos ◽  
Igor Alonso Portillo
Keyword(s):  
Modal Analysis ◽  
Operational Modal Analysis ◽  
Modal Parameters ◽  
Railway Vehicle ◽  
Correct Identification ◽  
Static Test ◽  
Railway Vehicles ◽  
Analysis Techniques ◽  
Behavior Design ◽  
Nonlinear Components

Nowadays the application of experimental modal analysis techniques on railway vehicles is gaining importance. A correct identification of modal characteristics allows improving the dynamic behavior design of the vehicle and so reaching higher running speeds and accomplishing better comfort levels. So far, in the railway sector only conventional modal analysis techniques have been used. With these techniques, the modal parameters are determined during a static test by measuring the responses of the system to one or multiple known forces. This paper presents the application of the Operational Modal Analysis (OMA) technique on a railway vehicle. This technique determines the modal parameters employing only the responses of the system to an unknown excitation. In this way, the data to be used can be acquired during on track test which presents three main advantages. The first one is that the nonlinear components of the suspensions are working in their normal operating condition which is difficult to achieve during a static test. The second one is that the wheel spinning effect is taken into account. Finally, the test can be combined with other type of track tests, reducing the period of time before delivery of the vehicle to the client. In the case under study, the OMA technique is applied by means of commercial software to measurements performed on a passengers train. The modal parameters obtained for the carbody and one of the bogies are presented.

Modal Analysis on a High Speed Train Based on Forced Excitation From Track

2012 ◽  
Author(s):  
Lara Ma Erviti Calvo ◽  
Gorka Agirre Castellanos ◽  
Igor Alonso Portillo ◽  
Mayi Garcia Prada
Keyword(s):  
Modal Analysis ◽  
High Speed ◽  
Impact Force ◽  
Impact Excitation ◽  
Modal Parameters ◽  
Maximum Speed ◽  
Vibration Modes ◽  
Test Results ◽  
High Speed Train ◽  
Railway Vehicles

The more demanding safety and comfort requirements combined with the increasing maximum speed of trains have lead to a growing concern in aspects such as the determination of the modal parameters of railway vehicles. Until now, the modal parameters of a vehicle have been obtained by EMA (Experimental Modal Analysis) based on the application of an impact force on the vehicle frame. However this kind of test is not optimal for railway vehicles because, due to their large dimensions, an impact force is unable to excite all the points of the structure. Also, with this method only the structural modes can be analyzed. Because of these drawbacks, a new modal analysis methodology is proposed, in which the excitation force comes from a specially designed shaker mounted under a point of a test track. In this manner, real excitation conditions can be simulated and it allows to determine not only the structural modes, but also the vibration modes associated with the suspensions. In first place, a description of the test facilities is presented. Afterwards, we present a test carried out in one of the coaches of a high speed train. The instrumentation employed, test methodology and test results are described. Finally, the test results are compared with the results obtained from a modal test in which impact excitation was used. Also the vibration modes obtained in the test are compared with the theoretical ones, which have been calculated with a combination of a FEM (Finite Element Method) and a MBS (Multi-Body Simulation).

Modal Analysis of Turbulent Flow near an Inclined Bank–Longitudinal Structure Junction

2021 ◽  
Vol 147 (3) ◽  
pp. 04020100
Author(s):  
Nasser Heydari ◽  
Panayiotis Diplas ◽  
J. Nathan Kutz ◽  
Soheil Sadeghi Eshkevari
Keyword(s):  
Turbulent Flow ◽  
Modal Analysis ◽  
Longitudinal Structure

Active steering of railway vehicles: A feedforward strategy

2003 ◽  
Author(s):  
Shuiwen Shen ◽  
T X Mei ◽  
R. M. Goodall ◽  
J. Pearson ◽  
G. Himmelstein
Keyword(s):  
Railway Vehicles ◽  
Active Steering
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