The Modal Parameter Identification Based On Spectrum Correction

Modal analysis is an interdisciplinary and comprehensive subject, which can be applied to various engineering fields and structures with no limits among those engineering subjects. Therefore, how to improve the precision of the modal parameter identification in order to serve the engineering fields better is the key subject, which is now being researched by many engineers. We can implement the modal parameter identification in frequency domain or time domain. The precision of traditional modal parameter identification depends on the precision of frequency response function, which has some specific shortcomings including poorer precision caused by window function truncation, the difficulty of calculating the frequency response function, lots of mathematic calculation and the prerequisite of a known exciting function.A new approach of modal parameters identification based on the latest spectrum correction and damping identification technologies is put forward in thi's paper, which is a breakthrough over traditional methods. The new theory of modal parameter identification (including frequency, damping, phase difference, real mode shape and complex mode shape) is deduced in this paper. Simulation and testing results show that the method is easily carried out with high precision. The maximum error of frequency is almost zero, the maximum error of damping, phase and magnitude is respectively 1%, 2% and 3%~7%. This method is very simple and easy to be understood. However, this method can't be used if one frequency is very close to the others or if the damping of one mechanical system is very large.