Failure Analysis Of ChongQing Straddle Type Monorail Vehicle's Pantograph

Chongqing straddle type monorail vehicle pantograph is a very important component on the electric locomotive, which is installed on both sides of the locomotive, the main role of pantograph is contact the rigid catenaries which are on both sides of the track beams and current-collecting, the installation method of pantograph is different from the other rail transit system. Chongqing monorail vehicle pantograph and catenaries both apply Japanese advanced technology, and Japanese technology is more mature than the domestic technology, however, the economic costs of Japanese pantograph are high. In the process of pantograph and catenaries use prone to pantograph-catenaries breakdown, such as pantograph fracture, pantograph scratches, pantograph deformation, pantograph-catenaries wear and so on, in which the fracture failure of the pantograph is the most serious harm, if not resolve these failure issues immediately will bring life danger and huge economic losses. Based on the Chongqing University and Chongqing Rail Transit Corporation cooperation projects"The 2nd line of Chongqing rail transit straddle type monorail vehicle's pantograph fracture failure analysis and finite element simulation studies", one of Japanese fracture pantographes as the research object, a series of studies of this subject to find out the reasons for the fracture failure of pantograph and give some useful advices.This article aims to analyze the main reasons for the monorail vehicle pantograph fracture failure during work and put forward some reasonable measures to prevent the recurrence of fracture failure. Because the fracture failure of pantograph is very complicated, the analysis of fracture reasons must be considered from all aspects, such as materials, fracture situation, force situation, vibration situation, structural design, environmental factor, and operating condition, etc. The main researches in this paper as follows: (1)Introducing Chongqing monorail vehicle pantograph's structure and fracture failure situation.(2)Physical and chemical analysis and fracture analysis of pantograph are carried out, whose test samples are made in accordance with national standards, and test results are analyzed.(3)Three-dimensional entities model and finite element model of the pantograph are established in order to prepare finite element simulation.(4)The static analysis of the pantograph under different work locations and different contact pressure are carried out by using finite element analysis software.(5)Considering the vibration characteristics of pantograph, the finite element modal analysis can identify its structural weak areas and obtain stress-strain and displacement of pantograph under vibration situation.The following conclusions and related improvement measures can be come from above failure analysises of pantograph: (1)There are so many casting defects in the pantograph material that mechanical properties of the pantograph become worse, the improvement of material internal quality must be needed to enhance material's mechanical properties.(2)The structural design of pantograph is reasonable and meets the basic needs can be conclued from the static simulation analysis results, under normal circumstances, the fracture failure of the pantograph under the conventional force will not happen.(3)Through finite element vibration modal analysis of pantograph, the structural stiffness weak areas of pantograph can be found and the stress-strain and displacement values of pantograph increase dramatically with high-frequency vibration situation. Due to the incentive vibration frequency away from the natural frequency of pantograph, therefore, the possibility of high-frequency vibration lead to fracture failure of pantograph can be ruled out , but the stiffness weak areas can still be improved to avoid the destruction due to high-frequency vibration.(4) Fracture failure of pantograph may be mainly focused on the accidental impact, form the fracture analysis of pantograph can be drawn from the cracks source is on the foundry casting defects which are in the pantograph edge, if this casting defects subject to accidental impact load, they are vulnerable to become crack source and lead to fracture damage. However, there are a lot of causes of accidental impact, so in addition to the strict maintenance for pantograph, the catenaries or other work parts should also be strict maintained, such as the smooth transition between catenaries and catenaries must be ensured and there are no existence of size deviation, otherwise there is a greater impact load on the pantograph when it pass through the unsmooth transition and lead to fracture damage. Therefore, it is very important of the maintenances about pantograph-catenary and other working parts strictly and timely.