Condition monitoring of curve squeal based on analysis of acoustic and vibration data

The railway industry is currently investing in condition monitoring techniques to be able to compete with other transportation mediums. One of the reasons for this investment is to be able to identify the incipient development of curve squeal in railway systems. The annoying high-pitched tonal noise produced because of curve squeal has necessitated the need for mitigation measures to be taken by railway operators. However, noise from the surroundings and other trains has affected the conventional use of microphones for monitoring curve squeal in tight curves. It is imperative that the railway industry introduce additional sensors to help in the characterization and identification of curve squeal in railway track as the train negotiates the curve. The objective of this research is focused on the evaluation of condition monitoring performances using vibrations obtained from the wheel/rail roller and sound obtained remotely close to the wheel-rail interface to identify and characterize curve squeal. By the completion of the comparative studies, this research has resulted in a number of new findings that illustrate the significant contributions to knowledge. This research presents the application of correlation method to establish a reliable relationship between acoustic and sound for the detection and characterization of curve squeal on the twin disc rig. The sensors used to detect and characterize curve squeal are microphone and two accelerometers installed laterally on the wheel and rail roller rims. The contact conditions taken into consideration are dry contact, wet contact and friction modifier contacts. A MATLAB model was developed to detect and characterize curve squeal. The results of the simulated model showed some disparities between the simulated transition yaw angles and measured transition yaw angles for which curve squeal occurs. Time and frequency domain were employed to extract the features from the sensors. Correlation method was employed to classify the features extracted from the microphone and accelerometer data. The results obtained showed that a negligible or weak correlation coefficient value indicates the development of curve squeal on the twin disc rig in dry contact conditions. A moderate or strong correlation coefficient values is an indication of no curve squeal occur or curve squeal mitigation when contaminants (water and friction modifiers are introduced to the wheel-rail interface). The performance of the Correlation method for determining and classifying fault feature (curve squeal) extracted from the microphone and wheel/rail accelerometers has presented some useful qualities that makes it suitable in a real condition monitoring application system

Prediction of metal pm emission in rail tracks for condition monitoring application

Exposure to particulate material (PM) is a major health concern in megacities across the world which use trains as a primary public transport. PM emissions caused by railway traffic have hardly been investigated in the past, due to their obviously minor influence on the atmospheric air quality compared to automotive transport. However, the electrical train releases particles mainly originate from wear of rails track, brakes, wheels and carbon contact stripe which are the main causes of cardio-pulmonary and lung cancer. In previous reports most of the researchers have focused on case studies based PM emission investigation. However, the PM emission measured in this way doesn’t show separately the metal PM emission to the environment. In this study a generic PM emission model is developed using rail wheel-track wear model to quantify and characterise the metal emissions. The modelling has based on Archard’s wear model. The prediction models estimated the passenger train of one set emits 6.6mg/km-train at 60m/s speed. The effects of train speed on the PM emission has been also investigated and resulted in when the train speed increase the metal PM emission decrease. Using the model the metal PM emission has been studied for the train line between Leeds and Manchester to show potential emissions produced each day. This PM emission characteristics can be used to monitor the brakes, the wheels and the rail tracks conditions in future

Dynamic simulation of a roller rig

The dynamic behaviour of railway vehicles is greatly influenced by the interaction of the wheelsets on the railway track. This behaviour can be replicated in laboratory conditions using a scaled roller rig. This paper presents the results of the modeling and simulation of a one-fifth scale roller rig. The simulation results obtained have been compared with a real railway vehicle (bogie) on the track. It has been observed that the scale roller rig has a much lower critical velocity than real railway vehicle due to the similarity and dimensional scaling laws that are taken into consideration in the roller rig design. The scale roller rig critical speed was observed to be 10.2 m/s while the Full Scale railway vehicle model was found to be 52 m/s. It can be concluded that the critical speed of the scaled roller rig model is one-fifth of the full scale critical speed

A Novel Approach To Modelling And Simulation Of The Dynamic Behaviour Of The Wheel-Rail Interface

This paper presents a novel approach to modelling and simulation of the dynamic behaviour of rail-wheel interface. The proposed dynamic wheel-rail contact model comprises wheel-rail geometry and efficient solutions for normal and tangential contact problems. This two-degree of freedom model takes into account the lateral displacement of the wheelset and the yaw angle. Single wheel tread rail contact was considered for all simulations and Kalker‟s linear theory and heuristic non-linear creep models were employed. The second order differential equations are reduced to first order and the forward velocity of the wheelset is increased until the wheelset becomes unstable. A comprehensive study of the wheelset lateral stability is performed and is relatively easy to use since no mathematical approach is required to estimate the critical velocity of the dynamic wheel-rail contact model. This novel approach to modelling and simulation of the dynamic behaviour of rail-wheel interface will be useful in the development of intelligent infrastructure diagnostic and condition monitoring systems. The automated detection of the state of the track will allow informed decision making on asset management actions – especially in maintenance and renewals activities

Modelling and simulation of dynamic wheel-rail interaction using a roller rig

The interaction between the wheel and rail greatly influences the dynamic response of railway vehicles on the track. A roller rig facility can be used to study and monitor real time parameters that influence wheel-rail interaction such as wear, adhesion, friction and corrugation without actual field tests being carried out. This paper presents the development of the mathematical models for full scale roller rig and 1/5 scale roller rig and the wear prediction model based on KTH wear function. The simulated critical speed for the 1/5 scale roller rig is about one-fifth of the critical speed for the full scale model so the simulated results compare well with the theory related to wheel-rail contact and dynamics. Also the differences between the simulated rolling radii for the full scale model with and without wear function are analysed. This paper presents the initial stage of a large scale research project where the influence of wear on the wheel-rail performance will be studied in more depth

Prediction of metal pm emission in rail tracks for condition monitoring application

Exposure to particulate material (PM) is a major health concern in megacities across the world which use trains as a primary public transport. PM emissions caused by railway traffic have hardly been investigated in the past, due to their obviously minor influence on the atmospheric air quality compared to automotive transport. However, the electrical train releases particles mainly originate from wear of rails track, brakes, wheels and carbon contact stripe which are the main causes of cardio-pulmonary and lung cancer. In previous reports most of the researchers have focused on case studies based PM emission investigation. However, the PM emission measured in this way doesn’t show separately the metal PM emission to the environment. In this study a generic PM emission model is developed using rail wheel-track wear model to quantify and characterise the metal emissions. The modelling has based on Archard’s wear model. The prediction models estimated the passenger train of one set emits 6.6mg/km-train at 60m/s speed. The effects of train speed on the PM emission has been also investigated and resulted in when the train speed increase the metal PM emission decrease. Using the model the metal PM emission has been studied for the train line between Leeds and Manchester to show potential emissions produced each day. This PM emission characteristics can be used to monitor the brakes, the wheels and the rail tracks conditions in future

On Quasi-Newton Method Applied To 2D Wheel-Rail Contact Models

Reliable and proficient numerical methods are required to determine the contact points between wheel and rail. This paper presents the use of Quasi-Newton method for determining the solution of a reduced number of non-linear wheel-rail contact geometry equations that arise as a result of the interaction of wheel and rail on the track. A novel two dimensional (2D) wheel-rail contact model is developed by using the wheel-rail contact co-ordinates to calculate the wheel-rail normal contact forces without approximating the contact angle. The simulated results are stored in a lookup table and accessed during the simulation of the bogie dynamic behaviour thus reducing the computational time. The reduced number of non-linear wheel-rail contact geometry equations and employment of Quasi-Newton method enable the proposed 2D wheel-rail contact model to be used for fast and real time simulations of complex and non-linear wheel-rail contact mechanics

A New Method for Modelling and Simulation of the Dynamic Behaviour of the Wheel-rail contact

This paper presents a new method for modelling and simulation of the dynamic behaviour of the wheel-rail contact. The proposed dynamic wheel-rail contact model comprises wheel-rail contact geometry, normal contact problem, tangential contact problem and wheelset dynamic behaviour on the track. This two-degree of freedom model takes into account the lateral displacement of the wheelset and the yaw angle. Single wheel tread rail contact is considered for all simulations and Kalker's linear theory and Heuristic non-linear creep models are employed. The second order differential equations are reduced to first order and the forward velocity of the wheelset is increased until the wheelset critical velocity is reached. This approach does not require solving mathematical equations in order to estimate the critical velocity of the dynamic wheel-rail contact model. The mathematical model is implemented in MATLAB using numerical differentiation method. The simulated results compare well with the estimated results based on classical theory related to the dynamic behaviour of rail-wheel contact so the model is validated