Research On Damage Identification Based On Frequency Response And Model Updating Method

Structural damage identification is an important part of the structural health monitoring,and it is also the main problem of the structural health monitoring.At present,structural damage identification technology based on structural vibration characteristics has made great development.However,due to lack of test data of the structure,the structural freedom in actual test is often less than the structural freedom of finite element mode in the actual large complex structure.For this problem,on the basis of the structural frequency response function data,in combination with freedom match and model updating method,damage identification method was reseached on a plane rigid frame structure,in this paper.Normally,in order to make finite element calculation more accurate,nodes and meshing is more meticulous.But in actual test,measuring point which is distributing in the same with the finite element analysis is impossible and unnecessary.At the same time,for the limitation of experimental conditions,it is impossible to measure the response of each measuring point in all freedom,especially in rotational freedom.For this reason,the freedom of the real structure is less than the freedom of finite element mode.For this problem,freedom match which was used to match the freedom relationship between the real structure and finite element mode was introduced. The model updating method based on frequency response and the model polycondensation was mainly introduced.Guyan polycondensation and Kuhar polycondensation method which made low-order frequencies of polycondensated mode same with that of the original model is effective.Using the optimal fitting method,test data of the frequency response was extended.The extended test data of the frequency response was more convenient to damage identification.In this paper,a kind of damage identification method based on the frequency response was introduced.This method was simple and easy.It can realize qualitative,positioning and quantitative.In combination with the extension of the frequency response.This method based on the incomplete test data can identify structural damage.In the method of polycondensation,the stiffness matrix and mass matrix on the polycondensated freedom was superposition to other freedom. After polycondensation,The physical meaning of the stiffness matrix and mass matrix is not clear. It cann't realise positioning and quantitative,when using polycondensation in combination with damage identification method based on the frequency response. For this problem,damage identification method based on the fitting method was introduced in this paper.The correction which avoid the Negative impact from polycondensation was used to structal damage identification.The iteration in fitting method make the mode more accurate.Finally,the numerical simulation was made on the mode by MATLAB and ANSYS.The results show that the method can achieve satisfactory precision.