The Study Of The Semi-active Vibration Control Of Piezoelectrics Smart Structures

With the rapid development of modern industry,thin and flexible material is used more and more widely,and this significantly increases the flexibility of structure.Consequently,the easily happened structural vibration deteriorates the performance of the structure.How to suppress vibration efficiently has attracted much attention,and is becoming a hot spot.Semi-active vibration control using smart piezoelectric materials is becoming a new trend of vibration suppression.Piezoelectric materials can be utilized as sensors and actuators because of its inherent piezoelectric and inverse piezoelectric effects.The greatest advantage of semi-active control is that lower power consumption by regulation of damping or stiffness.This means the control system do not requir traditional power amplifier with high power assumption any more.The main contents of the thesis are as follows:(1)We systematically investigate the SSDI(synchorized switch damping on inductor)technique,and make a comprehensive comprision between self-powered SSDI technique,self-sensing SSDNC(synchorized switch damping on negative capacitor)technique and SSDI based on velocity zero-crossing detection.Effciency of the three techniques are illustrated by a real experiment for piezoelectric cantilever beam vibration control,and an analysis is also given to explain the factor leding to the difference.(2)A novel semi-active control using PWM(pulse width modulation)technique is presented to solve the problems besetting existing approach,such as too simple control strategy,weak control force rely on voltage inversion,etc.Although the new method inherits the idea of switch control,it also shows new features by introducing PWM and feedback control into contrl system.These innovations facilitate us to use more flexible control algorithm,and avoid usage of power amplifier with large power assumption.A new semi-active control system,including hardware and software,is designed to implement traditional PID controller and LMS(Least Mean Square)adaptive filter.Finally,it is validated by experiment,and the comparisions between velocity and displacement feedback are also made by experimental study.(3)Existed studies on nonlinear energy harvester using piezoelectric materials have shown that there are two energy orbits co-existed in oscillator: high-energy orbit and low-energy orbit.To maximize the output power,a piezoelectric-driven excitation circuit is designed to bring up the vibration from the low-energy orbit to the high-energy orbit,and attain large amplitude oscillation.The efficacy of the new approach is verified by experimental study.