A Method To Identify Distribute Dynamic Load On Box-structure In Frequency Domain

In the analysis of structural dynamics it is an important research project to ascertain the load on the structural. Because of the complexity of the structure and load, to measure the load is impossible in most conditions. So, it is necessary to inverse it from the response and the characteristic of the structure. In this paper the technology to identify the distributed load on box-structure in frequency domain was studied based on the orthogonal polynomial.The main thought of this method is that use orthogonal polynomial to fit the dynamic load function, establishes the relation between polynomial progression coefficient and dynamic responses, work out the coefficient of the polynomial with the information of the response on the measuring point and the character of the system itself, thereby completes the dynamic load identification.This paper mainly worked on box-structure, carried out the identification of dynamic load distributed on box-structure using orthogonal polynomial through space mapping. The key is the space mapping. No matter from three-dimensional space to two-dimensional space or from parameter space to Cartesian coordinates space, the motive is to map the continuously structure to the simple coordinate space. The result of the computer simulation indicated that space mapping works well with orthogonal polynomial in the technology to identify the distributed load on box-structure in frequency domain. Further more the paper put forward dimension reduction thought and did some of related discussion. Finally, an experiment of the dynamic load identification on box-structure was introduced. The experiment included three parts:1, mode experiment to insure the consistency of the experimental model and finite element model; 2,measure the actual distribution of load for comparison with the distribution of identified load, and verifying the correctness of method; 3, measure the response for the identification of the distribution dynamic load.According to research, this paper indicates that the method has the abilities of high identification precision, anti-interference and non-restraint of the measure position that are suitable for engineering practice.