Research On Crack Damage Identification And Resonant Vibration Suppression Of Piezoelectric Beam

Flexible beam structure is characterized with light weight, low structural damping and low modal frequencies, and it is one of the main structure types used in the engineering field. The flexible beam will generate vibration when the flexible beam is subjected to the load or affected under a variety of unexpected external factors in the course of their work. The vibration will last for a long time. Prolonged vibration will cause the structural fatigue and damage, and it will reduce the working accuracy and working life of large and complex structures, such as spacecraft and industrial robot manipulator. Therefore, it is necessary to identify the damage and suppress the large amplitude vibration of the beam structures. In order to identify the crack damage and suppress the vibration under resonant excitation of flexible beams, the structural dynamics modeling, crack identification for a cantilever beam and the vibration control for a doubly-clamped (clamped-clamped) piezoelectric beam were investigated.Firstly, finite element method, Hamilton principle and four-node rectangle plate element were utilized to build the model of the dynamic system. The piezoelectric drive equation, piezoelectric sensor equation and acceleration sensor equation were given, and the state space equation of the system was derived.Secondly, damage identification method based on wavelet packet and artificial neural network method was analyzed, and numerical simulation was carried out. The damage index, i.e. H2norm of energy ratio relative variation was given based on wavelet packet energy spectrum. And the damage pattern recognition method based on neural network is analyzed. And simulation on crack damage identification for a piezoelectric flexible cantilever beam was performed as a reference for the subsequent experimental research.Then, numerical simulation on the vibration control under persistent excitation for a doubly-clamped piezoelectric beam was carried out. By using finite element modeling method, the state space equation of the system was obtained. The acceleration feedback based proportional-integral control method and variable structure control method were employed to suppress the vibration under resonant excitation of the beam, as a reference for the subsequent experimental investigation.Finally, an experimental setup for cracked piezoelectric flexible beam was built up and an experimental setup of doubly-clamped piezoelectric beam was established. Experimental research on crack damage identification and experimental research on the vibration control under resonant excitation for the doubly-clamped piezoelectric beam were conducted, and the experimental results were compared and analyzed.The theoretical analysis, numerical simulation and experimental results demonstrate that the crack damage of the flexible beam can be recognized by using wavelet packet analysis and neural network. And the acceleration feedback based proportional-integral control and variable structure control methods can suppress the vibration under resonant excitation effectively.