Structure Dynamic Load Identification, Time-domain Method

Parameter identification and load identification on basis of frequency-domain are all researched very well, while the error of truncation, which is brought by data conversion, can't be avoided. So, how to avoid these errors and identify the structure's modal-parameter and exterior-load accurately will be the key technique of this field in the future, and some research work shall be done in time-domain. The research work of this thesis gives an effectual method to identify specific dynamic-exterior-load that cannot be measured directly from some structure systems.On the basis of ITD (The Ibrahim Time Domain Technique), some special parameters selection are limited in a more precise range that was given in this thesis, while those parameters are essential in the procedure of modal parameter identification, using parameters those were selected in this range can bring us a satisfaction result. Compare with the prevenient research achievements, the range, which given in this thesis, is more precise. Some significative research work has been done in order to generalize ITD in factual engineering items and identify the modal parameters quickly.Many external conditions have limited direct measurement's application in the procedure of load identification, and the direct measurement is not an economic method anyway, which are all disadvantageous facts in factual engineering. On the contrary, identifying load from structural response data is more convenience, and it's also in common use in factual engineering items. During the research work, a formula of load identification has been acquired by applying the precise time-integration method; furthermore, the matrix expression has also been given. The value of exterior random instantaneous loading can be resolved by this matrix expression when the structural responses have been measured clearly. This method can give accurate results of load identification. Furthermore, the results' precision will be more satisfactory as soon as we know where the loadings act on exactly. Compare with frequency-domain method, the thesis provides a time-domain method, which is satisfactory in lessening calculation and precision for exterior loading identification.The numerical examples explain that the method of modal parameter identification and load identification in this thesis both are reasonable, applicable for factual engineering. On the basis of these research works, the key point of generalizing the technique to the more and more factual engineering items has been summarized at last.