Use of a Novel Fiber Optical Strain Sensor for Monitoring the Vertical Deflection of an Aircraft Flap

The present paper reports the use of a plastic optical fiber-based sensor for elongation measurements in an aircraft flap subjected to different types of flexural loading conditions. The sensor, bonded to the surface of the aircraft structure, relies on measuring the phase shift that occurs between two sinusoidally modulated light signals when the aircraft structure is bent. The light signals are guided through two optical fibers, one of them fixed to the top surface of the flap, and the other one to the bottom surface. The sensor offers good signal stability and repeatability and represents a cost-effective alternative to other more sophisticated health-monitoring systems currently used.