STRUCTURE CRACK DETECTION OF LONG DISTANCE PROPAGATION AND VARIOUS DAMAGES USING PZT SENSORS

摘要

Steel Plates are common components in many large structures. The real-time condition monitoring and active control of Steel Plates will improve the reliability and safety of many structures. SHM using PZT sensors is a major concern and has great significance for research about NDT. PZT sensors offer special opportunities for the SHM of structures constructed made of Steel Plates. We developed a method for finding crack position and estimating its location using the ultrasonic guided lamb wave. A powerful wavelet transform is used to extract the signals efficiently. Additionally, using the arbitrary function generator to excite the PZT patches we can generate the ultrasonic guided lamb wave. The ultrasonic guided lamb wave propagates along the beam and plate structures with PZT patches bonded and the realtime signals are recorded. Damages are indicated by a change of response signals when compared with a template in undamaged condition. The wave attenuation and mode conversion are sufficient to detect various types of defects. The results show considerable ability for detection localization of the simulated damages. Also, using the wave propagation velocity on the PZT sensor and Steel Plates, the crack position was detected exactly. The NI signal acquisition device and specially designed LabVlEW program were used for data acquisition and analysis. In particular, detection method of the damage with long distance propagation and different dimensions of the crack are presented in this paper. Each length of the Steel Plates are 3m, 5m and detection of different cracks with depths from 5mm to 15mm are presented in this paper.