Registration of Acoustic Emission Signals in Polymer Composite Material during Its Destruction by Means of Embedded Adaptive Fiber-Optic Sensor

Fiber-optic sensors have several features that determine the effectiveness of their use for diagnostics of polymer composite materials (PCM). These features include the tolerance of the fiber sensors to electromagnetic radiation, which allows to diagnosis in fields of aircraft and shipbuilding. It is also an important fact that the optical fibers can be integrated into the object structure to protect them and minimize the used space. The small cross section of the fibers does not introduce significant changes into the architecture of the reinforcing element when they are integrated into the interlayer space of the layered composite material. In case of a surface arrangement of optical fibers, binders of a similar nature as a matrix material of a polymer composite are used, providing one material. However, the specificity of this type of sensors is the distribution of sensitive elements that are located in the structure of the material, in contrast to the widely used local piezoelectric transducers. Experimental acoustic emission data obtained using a piezoelectric transducer and a multimode optical fiber glued to a specimen surface. Static tensile test of a fiberglass reinforced plastics (FGRP) specimen was done on a SHIMADZU universal testing machine. FGRP specimens were made by vacuum infusion method using Derakane 411-350 binder and 10 layers of 62004 fiberglass. A comparative analysis of the destruction process was performed using parameters of acoustic emission signals, such as peak frequencies in the case of registration by a piezoelectric transducer, and level energy changes of wavelet decomposition in the case of a fiber-optic sensor. Acoustic emission signals recorded by fiber-optic sensors at the level of interference are identified, and the application boundaries of the sensors are determined.