The use of composite materials in modern aircraft has been growing because of the numerous advantages that they provide. Generally, composite materials are less sensitive to corrosion, have enhanced fatigue behavior, and higher specific mechanical properties when compared to traditional materials used in aerospace applications. By contrast, composite materials have problems with damage detection which is an important procedure in the air transport industry. The main issue that occurs during the process of use is the separation of laminae from each other which happens on the inside of the material and is hidden from the outside. Nondestructive methods of aircraft testing are not effective enough for material monitoring.
Structural health monitoring consists of placing measuring and sensing devices on a structure to record, localize, analyze and eventually predict damage. Most structural health monitoring techniques strive to measure the needed data in a nondestructive way. Fiber Bragg grating sensors are optimal for measuring different variables as they are more cost-efficient, easy to implement on most surfaces, including composite materials.
Aircraft structures require regular, scheduled inspections and monitoring of all possible hazards due to their special conditions and the principles of their design. Therefore, structural health monitoring is conducted through fiber optic devices and has great potential to reduce the costs related to these operations. Fiber Bragg grating sensors have proved to constitute the most promising technology in this field. In order to prolong the operation period of all kinds of complex engineering systems and avoid catastrophic failures, so it is necessary to achieve the highest levels of damage detection. The automation of the inspection process is a point of major importance to reduce inspection efforts. The structural health monitoring system on the basis of fiber optic products can be defined as a set of devices that provides information that allows to locate, evaluate, and predict the loading and damage conditions of a structure. The structural health monitoring of aircraft structures can conduct real-time checks, reducing costs and improving the reliability and performance of the structures. A wide range of potential structural health monitoring technologies is being developed to meet these needs, and the most promising options are:
- electrical strain gauges and crack wires
- acoustic emissions methods
- optical-based technologies
- comparative vacuum monitoring
- microelectromechanical systems (MEMS)
Fiber optic products and fiber optic devices, in general, are very appropriate to perform structural health monitoring due to the fact that they have their intrinsic capabilities, such as sensitivity to electromagnetic radiation, low weight, compact size, great sensitivity and resolution, and their suitability to be embedded into structures. Fiber optic devices for monitoring the strain in aircraft structures can be classified into the following categories: intensity-based, interferometric, distributed and grating-based fiber optic devices.
Among grating-based sensors, FBGs and probably the most mature and widely employed optical sensors for structural health monitoring of engineering structures due to their fast development achieved in recent years.
Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line: fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed temperature sensing (DTS) systems. We create and supply a broad variety of top-notch fiber optic solutions for monitoring of various facilities all over the world.