Reliability Analysis Of Fatigue Lifetime Of Coupler Guard Arm Area Of Burden Strain

Coupler knuckle is one of the most importent bearing weight parts of heavy haul train. Coupler knuckle is importent to the safety of the railway transport and the problem of coupler knuckle cracks has been serious with the development of railway transport.It is necessary to study the reliability of coupler knuckle's fatigue lifetime as fatigue cracks is more likely to appear on the coupler guard arm area. The object researched in this paper are the types of no.16 and no.17 coupler knuckles,which are used universally on heavy-load wagon of china.Two kinds of that coupler knuckles,the Chinese coupler knuckle and the American coupler knuckle, were studied and the difference has been find.The contents of this paper can be summarized as follows:1. Simulation model of small subsample fluctuation method is built and many tests have been carried out to service for the test and data processing. The finally calculation results will be very different as the dual small subsample fluctuation method gives a smaller variation.In this part some useful conclusions about test interval, the number of staircases of small subsample fluctuation method and the variation estimatent have been caried out based on numerical simulation and some test date.2. The Chineae and American material properties have been tested by MTS and GPL-200 high frequency fatigue testing machine.Also combined with the conclusions obtained by numerical simulation ,fatigue limits and p-S-N curves have been tested using the group method and up-down method.3. The coupler knuckle's p-S-N curves have been derived by deduction from the material's curves.Geometry effect,size effect and surface effect are considered in this process.the focus of this discussion is size effect. Methods of calculate size effect have been summarized in this part.according to the coupler guard arm area's stress,size effect has been calculated mostly by the Statistics factors based on the resuts of the finite element analysis.4. Finite element analysis of the coupler knuckle is proposed.Finite element model of the coupler knuckle is built according to its entity, then is calculated by ANSYS based on its loads and constraints.Reliability analysis of fatigue lifetime of coupler guard arm area is proposed. It can program composition for caculating the reliability life of the coupler knuckle with the load spectrum date.the dispersion of coupler knuckle's fatigue strength can be simulated with the Monte-Carlo method. As the fatigue lifetime of American coupler knuckle is higher than the Chinese coupler knuckle,the main difference is the slope of the p-S-N curves.The research results of this paper can provide technical guarantee and support for the design and application of coupler knuckle of Chinese heavy haul train.Some research methods in this paper also can be used in the research of similar type problems.