Research On Uncertainty Quantification Method And Response Prediction Of Typical Profile Dynamic Model

The high-speed EMU technology of China has formed an independent,standardized and serialized standard technology system.In particular,the hollow profile car body makes the body lightweight and greatly improves the running speed of the vehicle and reduces the wheel rail force,which makes the operation performance and ride comfort of China’s high-speed trains praised by passengers all over the world.With the increasing of passenger flow of high-speed railway,the design task of train is also increasing.For the design of series vehicle,the parametric modeling aided design by means of simulation can improve the design efficiency and shorten the product development cycle.The finite element model used for decision-making needs accurate calculation results,but because of the complexity of profile structure and many connecting structures,in the process of simulation and analysis,the discreteness of model,the diversity of connecting structure model forms,the uncertainty change of parameters and so on all cause the change of calculation results and affect the reliability of structural response prediction,so it is necessary to quantify the uncertainty of dynamic model of profile structure and transfer the uncertainty,and to predict the response of the model.In this paper,several typical profile structures such as frame structure,hollow profile base plate of motor car and beam structure in under-frame,are taken as the research objects.Combined with the layering thought in model confirmation and the structural vibration test,the uncertainty of structural dynamics model is studied,the uncertainty quantification method is deduced,and the uncertainty variation is reasonably described based on vibration modal response,so that it can be transferred in the whole process of structural calculation to realize the uncertainty response prediction of the whole structure.This paper mainly studies the selection basis of the grid discrete density of the finite element model of the structure,the application of Richardson extrapolation in the quantification of the discrete error caused by the grid density,and the influence of three Richardson extrapolation formulas with different convergence accuracy on the quantification result of the discrete error based on the derivation of the side column of the frame structure.On this basis,the uncertainty quantification methods of structural material parameters and connection parameters based on the basic theory of Bayesian mathematical statistics are studied,and the feasibility of the methods is verified by taking the side column and cross beam of frame structure as examples.The prior distribution of the uncertain parameters of the structure is determined by the sensitivity analysis and the prior test of the samples;the response surface model function of the uncertain parameters of the structure to the modal frequency is established according to the response surface method,and the posterior distribution law of the parameters is fitted with the overall sample test data;the welded joint structure is modeled by the thinlayer element and MCMC based on DRAM algorithm is established Sampling quantifies the uncertainty of connection parameters.Finally,based on the quantitative results of the uncertainty of the substructure model,the uncertainty transfer is realized in the overall structure,and the uncertainty response prediction is carried out for the vibration modal characteristics of the welded structure of the bottom plate and beam of the motor car profile.