Research On Wireless Sensor Networks For Strain Monitoring

Structural health monitoring (SHM) and wireless sensor networks (WSNs) are both hotspot researches of current industrial technology. In recent years, a growing number of monitoring systems are researched to be applied on engineering structures. For these applications, the number of sensors, the volume of data to be processed and the complexity of the system have been increased significantly. The traditional way of cable wiring is cockamamie, and the large number wiring will increase the weight of the monitoring systems and the cost of maintaining expense. On the other hand, such traditional serial centralized monitoring systems have problems in system processing speed, system reliability and flexibility.Wireless sensor networks provide a good intelligent distributed monitoring network for the state monitoring of large-scale structures. Wireless sensor networks can greatly reduce the number of device wiring and the weight of the monitoring system. Since the wireless sensor network nodes have local signal processing abilities, much information can be processed locally. The sensor networks can form a parallel distributed processing system which can improve the system operating speed and reliability.Current application researches on wireless sensor networks mainly focus on the environmental monitoring area, the medical care, the large-scale construction and the military domain areas. Rare researches have been done to apply the WSNs technology to the aircraft structural monitoring. The main researches in this thesis are as followings:(1) Considering the demands of structural health monitoring and wireless sensor networks, a hierarchical modular of wireless sensor network system architecture is designed. A low-power multi-channel strain sensing acquisition module is designed and developed to be allocated to the wireless sensor network node. The performances of the module are calibrated.(2) Based on the understanding of wireless sensor network protocols in other applications, a two-tier wireless sensor network structure is developed. Software programs are designed including the multi-channel data acquisition module, the data fusion and transponder module of cluster heads module, multi-hop node module , relay node module and relay node module.(3) Based on the developed strain monitoring wireless sensor network, on-line strain distribution monitoring on a carbon fiber composite skin is realized. An evaluation strain monitoring experiment is also completed on a landing gear of a real fighter aircraft. These applications show that the developed system has good performance to monitor structural strain.