Wireless monitoring of structures including acoustic emission techniques

The inspection of building structures is currently made by visual inspection or by wired sensor techniques, which are relatively expensive, vulnerable to damage, and time consuming to install. In contrast, wireless sensor networks are easy to deploy and flexible in application so that the network can adjust to the individual structure. Different sensing techniques can be used with such a network, but acoustic emission techniques have been rarely utilized. With the use of Acoustic Emission (AE) techniques it is possible to detect internal structural damage from cracks propagating during the routine use of a structure or the break of wires of pre-stressed elements for example. Most of the existing AE data analysis techniques are not appropriate for the requirements of a wireless network, especially power consumption. Sensors with low price are required for AE systems to be accepted. To fully utilize the power of the acoustic emission technique on large, extended structures, recording and analysis techniques need more powerful algorithms to handle and reduce the immense amount of data generated. In particular, this paper deals with the optimization of the network to record different type of data including AE data. The basic principles of a wireless monitoring system equipped with MEMS sensors is presented along with a first prototype able to record temperature, moisture, strain and other data continuously.