Model Updating And Random Vibration Analysis Of Welding Structure

In many industrial equipment and building structures,such as automobiles,airplanes,ships steel structures and so on,welding procedure is commonly used as the connection between components.In some cases,the influence of welding structure on the whole dynamic characteristics is very obvious.At present,there is relatively little research on the dynamics of welding structure,especially on the dynamic finite element modeling comparison and model updating.In view of this,the following work has been carried out:Firstly,the finite element modeling method of T-shaped welded plate is studied to explore the accuracy of different elements in NASTRAN for weld simulation.In NASTRAN,consolidation,BEAM element,SHELL element,SOLID element and CSEAM element can simulate welding.Taking T-shaped plate as research object,and comparing the natural vibration frequencies of different weld models with those obtained by experiments,it is found that the accuracy of weld simulation using CSEAM unit is the best.Compared with the experimental results,it is found that the error increases with the increase of frequency order.The result error of BEAM element simulation of T-shaped plate is the largest,and the result is not stable,so it is not suitable for simulation of weld dynamic model.Secondly,based on the CSEAM unit,the research of welding structure dynamic model updating is carried out.Based on the research of input force residual,parameter sensitivity and objective function,the corresponding model updating theory is introduced.Select the elastic modulus of CSEAM element of welding structure for parameter updating.In the process of solving the optimization problem,the applied methods are the large number experimental algorithm,the genetic algorithm,and the Fminbond function optimization method of MATLAB.After updating the elastic modulus by three different optimization methods,it is found that the Fminbond function optimization method is used to calculate the elastic modulus speed,and the accuracy of the calculation results is high.The trend map obtained by the large number method is more intuitive,but the calculation is slow,and it is not easy to generalize the update of the most parameter model.Although the genetic algorithm is more efficient than the large number of experimental algorithms,the accuracy of updating parameters is also slightly insufficient.Finally,random vibration analysis of welding structure subjected to stationary random load is carried out.The Pseudo-excitation method is used to solve the random vibration problem of welding structure,the basic principle of Pseudo-excitation method is introduced,the calculation process of single point stationary excitation and multi-point stationary excitation is deduced,and the Pseudo-excitation method is compared with the traditional algorithm(traditional CQC algorithm and traditional SRSS algorithm).Using MATLAB and ANSYS to model the T-shaped welded plate.Then,the random vibration analysis under stationary random load is carried out.And the influence of single point excitation and multi-point excitation on the random vibration behavior of the structure is discussed.