In order to realize a flexible, practical and efficient SHMS operating in harsh environments, power consumption, size and cost must be minimized. Integrating analog and digital signal processing functions into dedicated multi-sensor system appears an optimum solution. Today’s state-of-the art in SHMS is mainly characterized by the two following developments.
Fiber optic sensors are basically non-MEMS components which can be separated into two classes for discrete strain and temperature measurements: cavity-based designs (they do not allow for multiplexing capability in a single fiber, and thus may be limited for applications requiring large number of sensors) and grating-based designs (Bragg gratings that can be easily multiplexed by using gratings of different wavelength). Examples include the extrinsic Fabry-Perot interferometer (EFPI), the intrinsic or fiber Fabry-Perot interferometer (IFPI or FFPI), and all other etalon-type devices. Ongoing research areas are critical to the practical implementation of optical fiber sensors for aerospace structures.
- Acoustic Emission (AE) sensor
Acoustic Emission (AE) appears as a fast, accurate and cost effective method for structural health monitoring (SHM). Table 1 summarizes the main applications of the MEMS AE sensor arrays for structural health monitoring.
