| Coal hopper freight car is the core equipment of railway heavy haul transportation.Compared with gondola car,coal hopper car can accelerate vehicle turnover,improve unloading efficiency,and obtain good economic benefits.Therefore,running coal hopper truck is the best choice to improve the efficiency of railway coal transportation in various countries,which meets the requirements of sustainable development of national economy,energy saving and environmental protection.The International Heavy Haul Transport Association(IHHA)clearly pointed out at the 11th South African International Heavy Haul Congress that the heavy axle truck with the advantages of load,speed and energy saving will become the core technical equipment of heavy haul transportation in the future.Under this background,it is an inevitable trend to design and develop coal hopper truck with large axle load.Under the constraints of existing railway line conditions,lightweight design of car body has been recognized as an effective measure to increase the load.The fatigue problem of key components of vehicles caused by lightweight car body is also increasingly prominent,which seriously affects the safety of railway transportation.Therefore,it is of great significance to study the key components of coal hopper truck with large axle load in the development of railway heavy haul transportation technology.This subject takes NHDH coal hopper truck with large axle load exported to PN Company of Australia as the research object.Aiming at the fatigue problems of the key components of the truck,the fatigue damage causes and improvement schemes of the key components of the truck are studied by means of the combination of finite element analysis and line operation test,mainly include:(1)Analyzing and summarizing the technical status of large axle load coal hopper cars at home and abroad,investigating the fatigue problems of key components in the operation of vehicles,and formulating special technical solutions from two aspects of simulation analysis and experimental research,combining the structural characteristics and operating conditions of vehicles.(2)Taking NHDH coal hopper car with large axle load as the research object,the fatigue strength of the truck is evaluated by means of finite element analysis according to AAR M-1001-2007 manual of standards and recommended practices chapter 7(hereinafter referred as AAR standards).The analysis results show that the fatigue strength of the truck meets the design requirements.According to the fatigue damage location,the local finite element model of the structure is established.Combining with the specific working conditions of the structure,the fatigue load under the specific working conditions is analyzed,and the causes of fatigue damage are preliminarily analyzed,which provides data support for the formulation of technical scheme of line operation test.(3)According to the results of simulation analysis and the actual operating conditions of the vehicle,the detailed line operation test scheme of NHDH coal hopper truck with large axle load is worked out,the line operation test is carried out,and the data acquisition is completed.(4)The test data are analyzed and processed,and the measured response data of each measuring point during vehicle operation are obtained.Combining the response data of each measuring point,the stress state of key components in actual operation is analyzed.Based on the measured data,the load spectrum is compiled,the fatigue strength of key components is evaluated,and the cause of fatigue failure is analyzed.(5)Based on the actual line operation test data,the input loads of key components under specific working conditions are deduced,and the fatigue evaluation and verification of the improved scheme are carried out under the input conditions. |
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