Modeling On Maintenance Process For Railway Based On Cost

China has entered highly developing era of railway construction.Railways are required to operate with a high level of reliability and safety for transporting passengers.The railway network,as a maintained or repairable system,suffers from deterioration processes as a result of usage and age.Therefore,optimum maintenance with acceptable cost has to be undertaken to ensure that railways fulfill their required function.Relative studies mainly focus on technic improvement and degradation modeling optimization.There are a few studies about maintenance process modeling and costs analysis.The objective of this thesis is to provide maintenance modeling optimization in order to reach maintenance optimization with lowest maintenance cost under required reliability and safety.This research can analyze existing problems and strengthen maintenance management in order to support the development of railway maintenance management system.This thesis develops a maintenance management framework based on dynamic data to solve the existing problems,and then chooses some typical maintenance processes,the inspection interval and monitoring technique to present the modeling.Petri nets technique is applied to model maintenance process.This thesis also provides maintenance proposals to improve railway safety and control maintenance cost.The main research contents include:(1)Optimization on the whole maintenance process of railway.By investigating the maintenance strategies,this thesis optimizes the maintenance process by developing lasting renewal database based on information collecting and renewing.By optimizing maintenance process,the following objects can be obtained: analyzing the operating state of component more precisely,predicting defects,reducing fault,arranging maintenance activities and balancing maintenance cost.By developing railway maintenance management system,railway can change from preventive maintenance to predictive maintenance.(2)Maintenance optimization for one-state component.The wear of component is a lasting process and also an inevitable mode in railway.Because wear caused by the friction between rail and vehicle and the wheel's operating condition highly related to safe operation.This thesis chooses the wheel as the research object,in order to analyze the wear process during operation and achieve maintenance activities for reliable and safe operation.This thesis models the wheel's wear process and its related maintenance activities,uses the wheel parameters to describe the wheel's degradation,analyzes maintenance activities including wheel maintenance,wheel inspection,renewal.Petri nets technology is applied to model the wheels.Furthermore,based on collected information,this thesis uses Monte-Carlo to simulate the maintenance process of the life cycle of the vehicle for the developed model,and assists the maintenance activities.(3)Maintenance optimization for multi-state component.Rail is a key component.Its failure could contribute significantly to the loss of system reliability,safety,and availability.This thesis analyzes the degradation process of rail and the related maintenance activities.This thesis uses Weibull function to deduce the rail's fault,and applies inspection,lubrication,wear,corrective maintenance and preventive maintenance to describe rail's maintenance activities,quantitatively analyzes the influences among maintenance activities,and applies Petri nets technique to model the rail.And Monte-Carlo method is also used to simulate the maintenance process.By applying the simulation result,maintenance optimization can be achieved.(4)Dynamic inspection interval for multi-state component.This thesis applies dynamic Petri nets technology to model multi-state components,in order to achieve optimum inspection period.As the requirement of reliability and safety during railway's operation,this thesis ensures the reliability of all the inspection intervals can satisfy the operation level in order to make sure that components can fulfill the function.Based on this aim,this thesis develops a dynamic inspection period model,applies Monte-Carlo method to simulate the model,and uses a case study to verify the feasibility of the developed model.(5)Economic benefits analysis on monitoring for multi-state component.Because of the long life cycle of railways,after construction,new technology can still be applied to improve maintenance efficiency in order to ensure the operation of the system.Real-time condition monitoring is one of the latest technologies.Using the investment on bearing's real-time condition monitoring technology as a case study,this thesis develops a Petri nets model on real-time monitoring,and simulates the developed model.Compared the life cycle cost before and after the investment,this thesis analyzes the cost efficiency of technology improvement with the simulation results in order to assist the maintenance staff with maintenance decisions.The innovations of this thesis can be summarized to:(1)This thesis applies graphic Petri nets technology with Monte-Carlo method to model the stochastic process in railway maintenance.Using case studies to discuss the developed model,optimum maintenance policies with cost-efficient methods can be found to guide maintenance activities for maintenance staff in the prerequisite of satisfying operation level.(2)Considering the maintenance characteristics of railway,this paper proposes a dynamic Petri nets technique.On the basis of Petri nets theory,this proposed method is expected to solve the practical application in modeling.(3)Based on dynamic data,maintenance management system framework of railway is created.There are few studies of the application of dynamic data in railway maintenance management.On the bases of disadvantages among maintenance activities,a way of the dynamic data in railway's application is presented.And this approach can efficiently optimize railway maintenance process and assist the application of dynamic data in railway management.This thesis proposes the dynamic Petri nets.The research results can provide theoretical support for the application of Petri nets technology in railway maintenance.Through the establishment of dynamic data_based railway maintenance management framework,this study promotes the establishment and improvement of railway management system,in order to strengthen the management of rail transport,and promote the railway from the corrective maintenance and preventive maintenance to predictive maintenance.So,this study has a strong practical significance.