Reliability Risk Assessment For Coupler Of Wagons

With the need of economic and social development in our country,the railway transport heads towards the direction of high-speed and overloaded continuously.As a key component of railway vehicle,a coupling device is used for the vehicle’s connection and force transferring in the process of operation.In order to guarantee the normal operation of the railway transportation and transportation efficiency,it is necessary to carry out the reliability risk assessment for coupling device.The NO.17 coupler is selected as the research object of the paper.After understanding the operating principle and structure of coupling and the potential failure,some analysis must be done such as failure mode and effect analysis,fault tree analysis,static strength analysis and fatigue life analysis.The main work of this paper is implied as following.(1)A fuzzy failure mode and effect analysis method is carried out on the coupling device combined with triangular fuzzy Numbers.The first step is taken to build up the evaluation criterion of the fuzzy failure mode and effect analysis,the expert evaluation method is adopted to fuzzily evaluate the occurrence,the severity and detection of each failure mode.Considered the relative weight of the three kinds of risk factors and relative weight of expert members in expert grading results,the fuzzy risk priority number of every failure mode is calculated,expressed by a cutting set.The last step is to solve the centroid values of the failure mode based on the fuzzy risk priority number.And the calculated number need to be sorted to determine the biggest impact of the failure mode of the coupling device.(2)A fuzzy FTA method is carried out on the coupling device in the basis of the traditional fault tree analysis and the concept of normal fuzzy numbers.In the basis of fuzzy FMEA analysis for the coupler in the first part,the biggest impact of the failure mode is selected as the top event to build up the fault tree.When normal fuzzy probability is used to evaluate the probability of bottom events,it is acquired to calculate the probability of top event and the probability importance degree of bottom events.The final aim is to point out the key component in the fault tree.(3)Static strength analysis is carried out on the key components of the fault tree.First of all,Coupling finite element model is established.Combined assembly analysis method with the contact nonlinear analysis method,the method is used to static strength analysis on the finite element model.It is indicated to simulate the situation of coupling under the traction force.The static strength results is analyzed by checking stress nephogram of integral coupling and the key components of the coupling respectively.(4)Fatigue life analysis is carried out on the coupling model.Based on the result of static strength analysis in the third part.coupling fatigue model is established.After determining the material parameters of the model and algorithm of fatigue,the calculation about fatigue life and evaluation of 100 minimum life points is finished and analyzed on the model of the coupling.