ANSYS Based Finite Element Model Updating And Its Application

Finite element model(FEM)updating technique was first proposed in the field of aviation and used for the prediction of responses and loads,flutter analysis and vibration control of aircrafts.It has been successfully applied in various industrial fields in recent years.The model updating of some frequency domain methods is usually difficult to converge in case of large test noise and large number of model degrees of freedom(DOFS).In order to overcome these problems,some algorithms of model updating are developed and implemented.The main contents in this thesis is as follows.(1)A dynamic finite element model updating method based on maximum likelihood estimation and frequency shift is presented for cases of large test noise,large residual between initial analysis FRF and test FRF,or large number of parameters to be modified.The results of numerical simulation and experimental investigation show that the presented method can be successfully applied to update large and complex finite element models.(2)A method based on reduced basis vectors for dynamic finite element model updating is proposed.The number of DOFS can be greatly reduced by applying modal synthesis basis vectors or mode shape vectors for complicated finite element model.As a result,the computational efficiency is greatly improved.(3)A FEM updating method is presented to update local area of a complex structure where modeling error can be confirmed.Frequency response functions(FRFs)of the residual structure and the measured FRFs of the global structure are utilized in the algorithm.The updating process is simplified and the computational efficiency is greatly improved.(4)Based on ANSYS and Matlab environment,a FEM updating software with friendly interface is developed to implement all the algorithm proposed.