Identification of crack by vibration analysis and restoration of dynamic response in beams using PZT sensor/actuator

The endeavour of this research is to locate the position of small-depth cracks in beam type structural element and to restore the dynamic response of the cracked beam through steady-state vibration analysis with the help of piezoelectric material. An open crack induces a discontinuity in rotational displacement curve of a vibrating element, though this discontinuity is an efficient parameter to detect the crack, but at the same time, there is no proper conventional method to check the discontinuity in a vibrating beam. The present study reveals that a bending piezoelectric sensor can efficiently detect the discontinuity due to the fact that the voltage output from the piezoelectric sensor depends on the difference in rotational displacement at its two ends. Subsequently, it is observed that by applying external time-varying voltage on a piezoelectric patch, the dynamic response of a cracked beam can be restored. Since the applied external voltage on the patch produces a local moment near the crack which diminish the effect of crack. Mathematical and finite element model are developedto obtain the results. An experimental set-up is made to validate few of the theoretically obtained results.