Load Spectrum Compiling And Life Prediction Simulation Of High Speed Train Carbody Based On The Accelerated Life Test

As the core component of the high-speed railway system, the high speed train is very important. High speed train is different from ordinary train with following characteristics: Operation speed is greater than 200 Km per hour; Carbody is light weighted by material aluminum alloy extrusion profiles; The driving mode is adopted the dynamic dispersion and fixed train groups; Suspended equipments are installed at the underframe of the car body; the floor middle beams and transverse beams on carbody underframe are cancelled. At present, the safety and reliability of the car body is an important research field in world. China is a big country in the field of high-speed railway. It can get the advantage in the fierce competition in the industry if make some progress. When high speed train car body with long life, high reliability in the actual operation of the process, its load spectrum has some characteristics: high frequency, low stress dominant. Therefore, in order to find the weak parts in the design period and then to improve the safety and reliability of the operation, it is very necessary to adopt the accelerated life test method in the test.This paper first describes the method of accelerated life test and accelerated life model parameter estimation. Then according to the life obeys the log-normal distribution, carry out accelerated life model parameter estimation combined with the existing aluminum alloy joint test data for typical vehicle aluminum alloy welded joint fatigue test data; Based on theoretical analysis, designed a program to estimate parameter of maximum likelihood from different reliability of accelerated life model. It is found that the estimated parameters of the accelerated life model are similar to that under the log-normal distribution.Then, according to the German FKM standard, the basic principle of the load spectrum is analyzed. Then the random load spectrum of the car body is obtained by using Simpack multi-body system dynamics simulation analysis. Through rain-flow counting, Weibull probability estimation, FFT analysis, load spectrum correction, load spectrum extrapolation etc. Finally get the load spectrum that obey the binomial distribution with in 1×107 cycles. And calculate the eight stress ratio of the three acceleration load spectrum.Secondly, established he finite element model of the carbody. Applied acceleration life test eight level load spectrum, respectively. Using Miner linear cumulative damage criterion and bio-linear damage criterion to predict the fatigue life of carbody. In order to research the effect caused by loading sequence on the damage to the vehicle body, this paper using nonlinear damage criterion to find the load spectrum effect on the damage induced by high and low loading and also provide a reference for reasonable bodywork loading sequence.Finally, the fatigue damage of the vehicle body under the random loads is analyzed by the quasi-static superposition method. And the fatigue damage of the vehicle body is compared with the acceleration load block spectrum. The results are obtained under the condition that the number of cycles of load is consistent, the model is consistent and the boundary condition is consistent.