Research About Dynamic Coupler Force Of C_80B Gondola Based On Simulation Analysis

The speed and shipment of railway train continue to increasing with the economic development,the forces beared by train become more and more complex.For heavy-load gondola,the analysis for fatigue strength design of rail transport has a very important significance.At present,the prediction based on simulation of random stress usually use quasi-static method and two-step approach in china.But it has a limit if use static methods to imitate dynamic process,and part of the power spectrum of the United States does not comply with our vehicle,the kinetic model of two-step calculation are rough,random stress got rough too,so the calculation accuracy is not high.To solve the above problems,our team developed a algorithm program of random vibration analysis which has the characteristics of adapting to the structural mechanics of rail vehicle,by combining the method of finite element with the algorithm of random vibration.This method can obtain random stress at the same accuracy with static stress calculation,it should be able to analyze structural fatigue directly in theory.However,due to the current dynamics simulation in the field of railway train’s design only considered the train irregularity spectrum(lateral and vertical vehicle incentives),there are no dynamic coupler load spectrum can be used for kinetic analysis,this makes the load in predicting structural fatigue is still imperfect,it will affect the fatigue life prediction inevitably.So,working out dynamic coupler load spectrum with random properties which can adapt fatigue simulation analysis,and setting up basic boundary conditions with complete become increasingly important.Based on the above problems,this article proposed an idea about the calculation of simple dynamic coupler force:it assumes coupler force is a low-frequency harmonic load,and use the harmonic load as input load in random vibration analysis.Doing fatigue calculation respectively with the static method-based on AAR standards of US and kinetics method-based on random vibration analysis system,according to the structure of C80B’s train body.Put the damage ratio’s equivalent of fatigue damage only coupler load with full loads as a criterion,by adjusting the amplitude of the harmonic load,so that the smallest difference between the results of the two methods,the harmonic load determined in this way is the coupler force.The ideas put forward three purposes:Firstly,it can meet an urgent need about the vacancy of coupler force in dynamic simulation;Secondly,we can learn the impact of the coupler force forced on the fatigue life by its reverse analysis;The third is to provide a reference for future dynamics analysis’s development of China’s railway gondola and find the coupler force which is necessary in fatigue design.In this article,firstly we use the finite element method established the structural model of quasi-static method and random vibration analysis;Secondly.completed finite element analysis of train body with the longitudinal,vertical,reverse and roll conditions based on the AAR standard,got the damage ratio of important parts of the train body under four conditions,then obtained a separate coupler force proportional contribution to the total fatigue damage.Thirdly;calculated the fatigue life of the important parts of the train body before and after considering coupler force in random vibration analysis system respectively,calculated coupler force proportional contribution to the total fatigue damage separately,by adjusting the harmonic load amplitude,so that the smallest difference between the results of the two methods,and then got coupler force;Finally,compared the fatigue life of the train body’s important parts before and after consider the coupler force,then got results:coupler force has a greater impact on the underframe,and a little effect on the side walls and end walls in the fatigue life assessment.Thus showing coupler force can not be ignored in fatigue assessment.