Analysis of the effects of main design parameters variation on the vibration characteristics of a vehicle sub-frame

In the design process of an automobile part, several analysis methods are usually used to evaluate the performance of the part. However, most automobile design engineers do not directly use CAE (computer aided engineering) tools since specific skills are required to obtain practical results. Moreover, CAE requires a huge amount of computation time and cost. To resolve these problems, a new design approach, termed first order analysis (FOA), has been proposed. In this paper, the FOA technique is employed to design a vehicle sub-frame. An equivalent model of the vehicle subframe which only consists of beam elements is proposed and the modal properties obtained with the model are compared to those obtained with a full scale finite element model. The effects of some parameter variations on the modal characteristics of the vehicle sub-frame are investigated by employing the FOA equivalent model. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Hong Hee Yoo graduated from the Department of Mechanical Design and Production Engineering at Seoul National University in 1980 and received his Master’s degree from the same department in 1982. He received his Ph.D. degree in 1989 from the Department of Mechanical Engineering and Applied Mechanics at the University of Michigan at Ann Arbor, U.S.A. He is currently working as a professor in the School of Mechanical Engineering in Hanyang University, Seoul, Korea.     

Robust extended Kalman filter of discrete-time Markovian jump nonlinear system under uncertain noise

This paper examines the problem of robust extended Kalman filter design for discrete-time Markovian jump nonlinear systems with noise uncertainty. Because of the existence of stochastic Markovian switching, the state and measurement equations of underlying system are subject to uncertain noise whose covariance matrices are time-varying or un-measurable instead of stationary. First, based on the expression of filtering performance deviation, admissible uncertainty of noise covariance matrix is given. Secondly, two forms of noise uncertainty are taken into account: Non-Structural and Structural. It is proved by applying game theory that this filter design is a robust mini-max filter. A numerical example shows the validity of the method.     

Train energy simulation with locomotive adhesion model

Railway Engineering Science - Railway train energy simulation is an important and popular research topic. Locomotive traction force simulations are a fundamental part of such research. Conventional...     

Study on track dynamic forces due to rail short-wavelength dip defects using rail vehicle-track dynamics simulations

A rail vehicle-track interaction dynamics model has been applied to determine the track vertical dynamic forces due to rail shortwavelength dip defects such as squat, dip joints and welds, etc., which are required in both rail vehicle acceptance procedure and track maintenance. The model is validated using the field measurement data of rail squat defects and accelerations on a vehicle axlebox. The simulated track dynamic forces — the P₂ forces due to rail dipped joints have been compared with those calculated by using a well-known formula. The results are compared and the formula’s limitations have been discussed. The dependence of the track vertical dynamic forces on the rail dip defect size and vehicle speed has also been investigated.     

Investigation of influence of constraints with radius links on locomotive axle load distribution and wheelset steering ability

The problem of improving the tractive and dynamic performance of locomotives by means of using axle boxes with inclined radius links was investigated. The kinematics of axle boxes with different variants (different angles) and designs of inclined radius links, based on the vector contour method for link mechanisms, was studied. The results of a bogie design with vertically inclined radius links were used for the improvement of vertical load distribution for locomotives. The behavior of a locomotive running in a curve is more complicated because the lateral forces appear between a flange of the wheel and the head of the rail in the contact zone, and the values of wheel slip are higher than for straight sections of track. These two factors are the main reasons for wheel wear. Theoretical and experimental investigations to reduce wear and to improve vehicle dynamics were made, and the results obtained show that an effective solution can be reached by the use of inclined links to the longitudinal axis of a bogie in the horizontal plane. Questions about the development of a bogie with a radial installation and active steering are discussed.     

Problems,assumptions and solutions in locomotive design,traction and operational studies

Railway Engineering Science - Locomotive design is a highly complex task that requires the use of systems engineering that depends upon knowledge from a range of disciplines and is strongly...     

A review on design and testing methodologies of modern freight train draft gear system

Rolling stock connection systems are key to run-ning longer and heavier trains as they provide both the connections of vehicles and the damping,providing the lo...     

Experimental prototyping of the adhesion braking control system design concept for a mechatronic bogie

Railway Engineering Science - The dynamic parameters of a roller rig vary as the adhesion level changes. The change in dynamics parameters needs to be analysed to estimate the adhesion level. One...     

State and Mode Feedback Control for Discrete-time Markovian Jump Linear Systems With Controllable MTPM

In this note, the state and mode feedback control problems for a class of discrete-time Markovian jump linear systems (MJLSs) with controllable mode transition probability matrix (MTPM) are investigated. In most achievements, controller design of MJLSs pays more attention to state/output feedback control for stability, while the system cost in practice is out of consideration. In this paper, we propose a control mechanism consisting of two parts: finite-path-dependent state feedback controller design with which uniform stability of MJLSs can be ensured, and mode feedback control which aims to decrease system cost. Differing from the traditional state/output feedback controller design, the main novelty is that the proposed control mechanism not only guarantees system stability, but also decreases system cost effectively by adjusting the occurrence probability of system modes. The effectiveness of the proposed mechanism is illustrated via numerical examples.      

Numerical calculation of temperature in the wheel–rail flange contact and implications for lubricant choice

The realization of movement by railway vehicles creates a problem that is connected to the wear process for elements of a tribological wheel–rail system. Wheel–rail wear is a complex phenomenon that depends on many factors. One of the main wear zones is the contact area between a wheel flange and a rail gauge. As is well known, wear in this contact zone occurs when a railway vehicle moves on curved parts of track, realizes tractive, braking efforts or moves in a high-speed mode. In this case, the solution of this kind of wear problem can be found by means of lubricant implementation. The choice of a lubricant requires information about contact characteristics at the moment of a vehicle's movement. This paper focuses on the modeling of the temperature process in the contact between a wheel flange and a rail gauge. Examples of temperature calculation with some experimental data as input for this computation are presented. The obtained values of the temperature allow for making the correct choice of lubricant type.