In order to apply a PZT-based pipeline structure damage detection technology in engineering, in this paper, a PZT wave-based active detection technology as theoretical foundation was used, combining with the characteristics of pipeline structure cracking, to develop a new type of portable detection system, which is based on virtual instrument (VI) technology. The developed system was validated through testing, and the results indicated that the system is stable and reliable, enabling to identify different crack damage states of pipeline structures in real-time and online. The proposed damage detection system can be used in pipeline structures with the low cost, portable, rapid diagnose and high-precision characteristics.
Pipeline structure has been widely used in petroleum, chemical, electric power, and natural gas industries, etc. However, due to environmental impacts or man-made disoperation pipeline will have cracks, corrosion and other defects, which will cause a great threat to the pipeline system safe operation, especially in the event of an accident, will cause huge economic losses and environmental pollution. To avoid possible accidents and ensure the safe use of pipeline structures, periodic safety inspections or long-term health monitoring of the piping system are of particular and great importance. Due to characteristics of long distance and large area of pipeline structures, applications of commonly used nondestructive testing (NDT) technologies are greatly restricted. At present, a new non-destructive testing method - the use of a piezoceramic active wave sensing detection technology for pipeline structures is gradually developed and good results are achieved (Song, Gu and Mo, 2008; Song, Gu and Mo, 2007; Song, Gu and Mo, 2006; Du, Kong, Lai and Song, 2013; Gazis, 1959; Alleyne and Cawley, 1996; Yan, Sun, Song, Gu, Huo, Liu and Zhang, 2009; Silk and Bainton, 1979; Lowe, Alleyne and Cawley, 1998; Park and Payne, 2011).
Piezoceramics, (such as Lead Zirconate Titanate, PZT), is a kind of intelligent material with sensing and driving dual characteristics. It is simple in manufacture, high in strength, resistant to moisture, heat and frequency response, etc. Due to a unique piezoelectric effect, the PZT material can be used as both a sensor element and an actuator component. The basic principle of the active detection technology applying the PZT wave based method is using the piezoelectric effects of piezoceramics to manufacture transducers which are arranged in the detected structures in a form of array for transmitting and receiving detection signals, thereby establishing an excitation and sensing channel. Based on the received data combining with a special damage detection algorithm, a structural damage identification and diagnosis can be realized by analyzing the signal difference between the healthy structure and the damaged one. The principle is shown in Fig. 1.