The Research Of Single Response Load Identification In Time Domain Based On System Total Decoupling

In recent decades,the development of engineering structure and technology make the dynamic load identification more and more important in the practical engineering problem.The complexity of engineering structure and the variety of incentive forms,which leads to the non-measurement of the external load of the system,so it is necessary to establish the corresponding model to identifiy the load according to the structure.In 1980 s,the load identification in time domain was proposed,which could identify the unknown load according to the structural response time history process directly.Its identification precision is available and has the potential to identify all kinds of loads,and the prospect of engineering application cdis very broad.The existing load identification method in time domain is to transform the multi-degree of freedom differential equation into the non-coupling form by the modal superposition method,then establish the specific inversion formula.In this process,the decoupling problem of the two order system is involved,and the main problem is the diagonalization of three matrices simultaneously.In the perspective of numerical algebra,it is very difficult to implement by the principal coordinate transformation.In this paper,in order to diagonalize the cofficient matrices simultaneously,the decoupling method of the two order system based on Lancaster structure was introduced to the system dynamics equation decoupling problem.On the basis,the new model of dynamic load identification was built by mathematic theory,and it was suitable for the proportional damping system and non-proportional damping system.The model was validated by numerical experiments and so did the resistance of noise.Firstly,the original system was transformed into Lancaster expansion form,and the corresponding decoupling transformation was obtained by the decoupling transformation method which was based on the Sylvester equation.Secondly,the load identification method based on the decoupling of the system was deduced by mathematical formula.Finally,the load identification method of single response was obtained by constructing the recursive iterative scheme,which could solve the external load only by the displacement or velocity,and it overcame the failure of load identification on account of the response's non-measurement in the practical engineering applications.In addition,the anti-noise performance of load identification method was studied.Aimed at the specific kind of load,the possible form of noise was given.The comparison was made between the existing method of single response load identification which was based on the modal analysis method and the proposed method in the article,and the identificaiton precisions that different response inverse the load were compared.On the one hand,the numerical simulation experiments verified that the identificaiton precision and the noise resistance of the proposed method was higher than that of the existing single response load identification method which was based on the modal method.On the other hand,it was suitable for the non-proportional damping system.At the same time,the precision and anti-noise performance could meet the need of the engineer project.