Development of an Analytical Model for Prediction of Drag Torque Characteristics of Disengaged Wet Clutches in High Speed Region

2017 ◽  
Author(s):  
Shahjada A. Pahlovy ◽  
Syeda Mahmud ◽  
Masamitsu KUBOTA ◽  
Makoto Ogawa ◽  
Norio Takakura
Keyword(s):  
Analytical Model ◽  
High Speed ◽  
Drag Torque

scholarly journals The coupled effects of bending and torsional flexural modes of a high-speed train car body on its vertical ride quality

2019 ◽  
Vol 233 (4) ◽  
pp. 979-993 ◽  
Author(s):  
Vahid Bokaeian ◽  
Mohammad A Rezvani ◽  
Robert Arcos
Keyword(s):  
Analytical Model ◽  
Quality Index ◽  
High Speed ◽  
Ride Quality ◽  
Vertical Acceleration ◽  
Beam Model ◽  
High Speed Train ◽  
Flexural Mode ◽  
Car Body ◽  
Rail Irregularities

This study is focused on the effects of bending and torsional flexural modes of the car body on the ride quality index of a high-speed train vehicle. The Euler–Bernoulli beam model is used to extract an analytical model for a high-speed train vehicle car body in order to investigate its bending and torsional flexural vibrations. The rigid model includes a car body, two bogie frames, and four wheelsets such that, each mass has three degrees of freedom including vertical displacement, pitch motion, and roll motion. The results obtained with the proposed analytical model are compared with experimental measurements of the car body response of a Shinkansen high-speed train. Moreover, it is determined that the bending and torsional flexural modes have significant effects on the vertical acceleration of the car body, particularly in the 9–15 Hz frequency range. Furthermore, the ride quality index is calculated according to the EN 12299 standard and it is shown that the faster the train the more affected is the ride quality by the flexural modes. In addition, the effect of coherence between two rail irregularities (the right and the left rails) on the results of the simulation is investigated. The results conclude that if the irregularities are completely correlated the torsional flexural mode of the car body does not appear in the response. Also, the first bending flexural mode in such cases is more excited compared with the partially correlated or uncorrelated rail irregularities. Therefore, the ride quality index in completely correlated cases is higher than other cases.

A Study of Transient Response of Flexible Rotors in High Speed Turbomachinery

1992 ◽  
Author(s):  
V. Pavelic ◽  
R. S. Amano
Keyword(s):  
Mathematical Model ◽  
Computer Program ◽  
Analytical Model ◽  
High Speed ◽  
Angular Speed ◽  
Journal Bearings ◽  
Hydrodynamic Characteristics ◽  
Flexible Assembly ◽  
Lagrange’S Equation ◽  
Equations Of Motions

In many applications the design operating range of the turbomachinery may be well above the rotor first critical speed which leads to the problem of insuring that the turbomachinery performs with a stable, low-level amplitude of vibration. Under certain conditions of high speed and loading the rotor system can start orbiting in its bearing at a rate which is less than the rotor angular speed, and this phenomena is commonly known as whirling or whipping action. This whipping action may produce additional undesirable dynamic loads on the overall flexible assembly and eventually destroy the rotor. Some of this action is also transient in nature. Whirling is a self-exited vibration caused mainly by the fluid bearings and by the internal friction damping of the rotor. To understand this occurrence, a general dynamic mathematical model was derived considering also the complete viscous characteristic of hydrodynamic journal bearings. The general equations of motions of the system are obtained from Lagrange’s equation of motion. The system kinetic, potential, and dissipation functions are determined based on the generalized coordinates of the system. The journal displacements are related to the overall dynamics of the rotor using deformable bearings. The loads acting at the journals of the shaft are integrated from the fluid film pressure distribution in the journal bearings using mobility method. A unique mathematical model is formulated and solved. This model includes the elastic and inertial properties of the flexible rotor, the elastic, damping and inertial properties of supports and the hydrodynamic characteristics of the journal bearings. The equations of motions result in a system of nonlinear second order differential equations which are solved by using finite difference method. The solution of the equations of motions is used to plot maps of motion of journal centers. A computer program was implemented to aid in the solution of the system of equations and to verify analytical model. The computer program used test data available in literature and the results were compared to be very good. The analytical model and results obtained in this study can be of great help to designers of high speed turbomachinery.

scholarly journals Analytical Modeling of Metamaterial Differential Transmission Line Using Corrugated Ground Planes in High-Speed Printed Circuit Boards

Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 299 ◽  
Author(s):  
Myunghoi Kim
Keyword(s):  
Analytical Model ◽  
High Speed ◽  
Printed Circuit Boards ◽  
Signal Transmission ◽  
Circuit Boards ◽  
Transmission Characteristics ◽  
Differential Signal ◽  
Printed Circuit ◽  
Full Wave ◽  
Differential Transmission

An analytical model for metamaterial differential transmission lines (MTM-DTLs) with a corrugated ground-plane electromagnetic bandgap (CGP-EBG) structure in high-speed printed circuit boards is proposed. The proposed model aims to efficiently and accurately predict the suppression of common-mode noise and differential signal transmission characteristics. Analytical expressions for the four-port impedance matrix of the CGP-EBG MTM-DTL are derived using coupled-line theory and a segmentation method. Converting the impedance matrix into mixed-mode scattering parameters enables obtaining common-mode noise suppression and differential signal transmission characteristics. The comprehensive evaluations of the CGP-EBG MTM-DTL using the proposed analytical model are also reported, which is validated by comparing mixed-mode scattering parameters Scc21 and Sdd21 with those obtained from full-wave simulations and measurements. The proposed analytical model provides a drastic reduction of computation time and accurate results compared to full-wave simulation.

scholarly journals Suppression of Ground Borne Vibration Induced by High-Speed Lines

2018 ◽  
Vol 152 ◽  
pp. 02001
Author(s):  
Ali Mohamed Rathiu ◽  
Mohammad Hosseini Fouladi ◽  
Satesh Narayana Namasivayam ◽  
Hasina Mamtaz
Keyword(s):  
Mathematical Model ◽  
Analytical Model ◽  
High Speed ◽  
Moving Load ◽  
Ground Vibration ◽  
Harmonic Excitation ◽  
Vibration Response ◽  
Vibration Velocity ◽  
Velocity Response ◽  
The Mathematical Model

Vibration of high-speed lines leads to annoyance of public and lowering real estate values near the railway lines. This hinders the development of railway infrastructures in urbanised areas. This paper investigates the vibration response of an isolated rail embankment system and modifies the component to better attenuate ground vibration. Mainly velocity response is used to compare the responses and the applied force is of 20 kN at excitation frequencies of 5.6 Hz and 8.3 Hz. Focus was made on ground-borne vibration and between the frequency range of 0 and 250 Hz. 3D Numerical model was made using SolidWork software and frequency response was produced using Harmonic Analysis module from ANSYS Workbench software. For analytical modelling MATLAB was used along with Simulink to verify the mathematical model. This paper also compares the vibration velocity decibels (VdB) of analytical two-degree of freedom model mathematical model with literature data. Harmonic excitation is used on the track to simulate the moving load of train. The results showed that modified analytical model gives the velocity response of 75 VdB at the maximum peak. Changes brought to the mass and spacing of the sleeper and to the thickness and the corresponding stiffness for the ballast does not result in significant vibration response. Limitations of two-degree analytical model is suspected to be the cause of this inactivity. But resonance vibration can be reduced with the aid of damping coefficient of rail pad. Statistical analysis methods t-test and ANOVA single factor test was used verify the values with 95% confidence.

Evaluation of Windage Losses for High-Speed Disc Machinery

1992 ◽  
Vol 206 (3) ◽  
pp. 149-157 ◽  
Author(s):  
M R Etemad ◽  
K Pullen ◽  
C B Besant ◽  
N Baines
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Air Gap ◽  
Drag Torque ◽  
Torque Measurement ◽  
Air Mass ◽  
Temperature Changes ◽  
Insignificant Effect ◽  
Air Jets ◽  
Experimental Apparatus

Design and development of experimental apparatus is detailed for stator drag torque measurement as well as a method to evaluate rotor windage losses directly from air mass flow and temperature changes. Effects of air jets at the rotor rim were also investigated. Results are presented for air windage losses associated with ultra-high-speed machinery. These show that within the range investigated the air gap length between the rotor and the stator has an insignificant effect on windage losses. The lowest windage losses were encountered when air was forced through the rotor/stator gap from the direction of rim to bore.

1205 Study on design of the Seats for High Speed Railway Vehicle by using the Analytical Model of Vibration Characteristics

2009 ◽  
Vol 2009.18 (0) ◽  
pp. 109-112
Author(s):  
Yuta ICHIKURA ◽  
Masao NAGAI ◽  
Ryuzo HAYASHI ◽  
Ryohei SHIMAMUNE ◽  
Yoshitaka YASUI ◽  
...  
Keyword(s):  
Analytical Model ◽  
High Speed ◽  
Vibration Characteristics ◽  
Railway Vehicle ◽  
High Speed Railway

Hydrostatic Gas Journal Bearings for Micro-Turbomachinery

2004 ◽  
Vol 127 (2) ◽  
pp. 157-164 ◽  
Author(s):  
L. X. Liu ◽  
C. J. Teo ◽  
A. H. Epstein ◽  
Z. S. Spakovszky
Keyword(s):  
Natural Frequency ◽  
Analytical Model ◽  
High Speed ◽  
Experimental Testing ◽  
Fluid Dynamic ◽  
Damping Ratio ◽  
Journal Bearings ◽  
Fiber Optic Sensor ◽  
Gas Bearings ◽  
Aspect Ratios

Several years ago an effort was undertaken at MIT to develop high-speed rotating MEMS (Micro Electro-Mechanical Systems) using computer chip fabrication technology. To enable high-power density the micro-turbomachinery must be run at tip speeds of order 500m∕s, comparable to conventional scale turbomachinery. The high rotating speeds (of order 2 million rpm), the relatively low bearing aspect ratios (L∕D<0.1) due to fabrication constraints, and the laminar flow regime in the bearing gap place the micro-bearing designs to an exotic spot in the design space for hydrostatic gas bearings. This paper presents a new analytical model for axially fed gas journal bearings and reports the experimental testing of micro gas bearings to characterize and to investigate their rotordynamic behavior. The analytical model is capable of dealing with all the elements of, (1) micro-devices, (2) dynamic response characteristics of hydrostatic gas bearings, (3) evaluation of stiffness, natural frequency and damping, (4) evaluation of instability boundaries, and (5) evaluation of effects of imbalance and bearing anisotropy. First, a newly developed analytical model for hydrostatic gas journal bearings is introduced. The model consists of two parts, a fluid dynamic model for axially fed gas journal bearings and a rotordynamic model for micro-devices. Next, the model is used to predict the natural frequency, damping ratio and the instability boundary for the test devices. Experiments are conducted using a high-resolution fiber optic sensor to measure rotor speed, and a data reduction scheme is implemented to obtain imbalance-driven whirl response curves. The model predictions are validated against experimental data and show good agreement with the measured natural frequencies and damping ratios. Last, the new model is successfully used to establish bearing operating protocols and guidelines for high-speed operation.

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