Development of a PZT-based wireless digital monitor for composite impact monitoring

One of the major concerns in the whole lifetime of composite materials in aircraft is their susceptibility to impact damage. And there has existed a need in recent years to develop an online structural health monitoring (SHM) system for impact monitoring. This paper proposes a new PZT-based wireless digital impact monitoring system development method aimed at giving a localized area for further inspection. Based on this method, a PZT-based wireless digital impact monitor (WDIM) with advantages of compactness, light weight, low power consumption and high efficiency is developed. Differently from conventional SHM systems, the complex analog circuits are removed and the whole process is achieved in a digital way by turning the output of the PZT sensor directly into a digital queue through a comparator. A simple but efficient sub-region location method is implemented in a field programmable gate array (FPGA) as the processing core of the WDIM to detect and record the impact events. In addition, wireless communication technology is used in the WDIM to transmit data and form a monitoring network. To illustrate the capability of the WDIM, a complete process dealing with an impact event is investigated and the stability of the WDIM is also evaluated in this paper. The WDIM shows its potential for real online applications in aircraft.