Finite Elements Model Updating Of Body In White Based On Modal Parameters

At present,CAE technology is widely used in all phases of vehicle design and development.CAE technology greatly improves the efficiency of car design and development,and makes a revolutionary change in automotive product design.Because of the reasonable simplification of the structure in the modeling process,the simulation of the structural connection relationship,and the inconsistency of the material parameters of a large number of nonlinear components,it often results in deviations between the finite element model calculation results and the experimental model.The accuracy of the finite element model will directly affect the later stage of the structural optimization design process.So,it is of great significance to establish a high quality finite element model.This article takes a lightweight compact white car body as the research object.Firstly,it conducts the experimental modal analysis on the actual white body structure.It uses the test equipment to obtain the real white body modal frequency and mode shape.And then it obtains the white of the reverse direction.The vehicle body numerical simulation establishes the white body finite element model through the normative process.It further analyze the frequency and mode shape of its computational modal.Finally,through the frequency error comparison and the modal confidence criterion,the modal frequencies of the experimental mode and the calculated mode are respectively compared with the vibration mode.It is verified that the accuracy of the finite element model does not meet the engineering requirements.It may be due to the inaccuracy of the material parameters of the large number of nonlinear components existing in the BIP model.In order to establish a high-quality white-body finite element model,first select the center composite design test design method and the second-order polynomial basis function form.It uses the variance analysis to filter out the parameters that have greater significance for each modal frequency.The response surface method was used to establish the response surface model of the material parameters and the modal frequencies of these nonlinear components.And the fitting accuracy of the response surface model of each mode frequency was verified.Then the simulation data was based on the experimental data.The frequency value is close to the experimental modal frequency value,and the modal frequency values of the various orders are guaranteed to be within 5%of the acceptable error range of the project.Thereby it transforms the problem of model correction into an optimization solution for nonlinear programming with constraints.Finally,the sequential quadratic programming algorithm and the bionics-based multi-island genetic algorithm are used to optimize the nonlinear component,s material parameters.And the modified finite element is verified with the modal frequency and mode shape respectively.The validity of the model is compared with the optimization effects of the two optimization algorithms on the model modification problem.The optimization results show that the accuracy of the modified finite element model is significantly improved.The final high-quality white-body finite element model can be used for later optimization.