Composite Materials Monitoring by Fiber Optic Sensors

Abstract

The paper presents methods for testing the composite materials using two types of fiber-optic sensors as well as a method for using radiation of the vertical-cavity emitting laser radiation (VCSEL) for checking the material deformation and its performances. The deformation checking sensor is a fiber Bragg grating (FBG) with a spectrum width of 50 pm, which is interrogated by the VCSEL. A new algorithm for modulating the laser diode current is proposed for the FBG interrogation providing a dynamic range of at least 3 nm. A new interrogation method of impulse Fabry-Perot interferometer was proposed. The interrogation method was applied for a fiber-optic acoustic emission sensor manufacturing. The sensor was experimentally investigated by the impact of a 6 mm diameter steel ball and compared to a reference piezoelectric acoustic emission transducer.