Research On A Composite Damage Identification Method For A Rotor Based On Piezoelectric Coupling Impedance

Rotary machinery is widely used in mechanical engineering. It plays an increasingly important role in various industry fields. Research on rotating machinery fault diagnosis technology, to ensure the safe operation of the equipment, to reduce the great economic losses, and to prevent catastrophic accidents is of great significance. It is easy to get to know the occurrence of damages while the real difficulties lie in how to locate and quantify damages.A rotor is the core component of a rotary machine. In this research, in order to localize and quantify damages of a rotor, the loss of bending moment is reckoned as the damage index. Based on the principle of the different degrees change of the system impedance value under the condition of different degree of damage in the structure, Piezoelectric Impedance Method(PIM) and Spectral Element Method(SEM) are introduced in the modeling. And studying the identification method of damaged rotor with single piezoelectric patch.Since the identification model of damaged rotor with single piezoelectric patch impedance have lower sensitivity matrix rank, and have a small number of effective admittance differences. In this research, an identification method of damaged rotor with double piezoelectric patches coupling impedance is proposed, thus further improve the identification precise. This method changes the dynamic characteristics of original electromechanical coupling system by adding a piezoelectric patch and relative circuit to form electromechanical coupling with the rotor, which leads to disagreement between coupling impedance of the rotor and the impedance of single piezoelectric patch; at the same time, since the two piezoelectric patches locate differently, stimulate them one after another to get two linear independent sensitivity matrix, and thus improve the sensitivity matrix rank and effective admittance, which improves the ill-condition problem of the algorithm equations of damage identification, and contribute to solving the damage index vector. It can be seen from the simulation analysis that the real part of impedance would imply the structural damage change with a higher probability. The simulation result of comparing two above methods indicates that an identification method of damaged rotor with double piezoelectric patches coupling impedance will identify the location and degree of the complex damage more accurately.Finally, Taking experimental verification with making identification on the complex damage of the same rotor using the identification method damaged rotor with single piezoelectric patch and the identification method damaged rotor with double piezoelectric patches coupling impedance, respectively. And the compute results validate the availabilities of these piezoelectric impedance methods. However, comparing to the identification method damaged rotor with single piezoelectric patch, the identification method damaged rotor with double piezoelectric patches coupling impedance proposed in this paper will have a higher identification accuracy of the complex damage of rotors.