Fused filament fabrication of continuous optic fiber reinforced polylactic acid composites

Purpose The limited strength of polylactic acid (PLA) hinders its extensive engineering applications. This paper aims to enhance its strength and realize diverse applications. Design/methodology/approach Here, the continuous fiber reinforced PLA composites are fabricated by a customized fused filament fabrication three-dimensional printer. Uniaxial tensile and three-point flexural tests have been conducted to analyze the reinforcement effect of the proposed composites. To unveil the adhering mechanism of optic fiber (OF) and PLA, post failure analysis including the micro imaging and morphology have been performed. The underlying mechanism is that the axial tensile strength of the OF and the interfacial adhesion between PLA and OF compete to enhance the mechanical properties of the composite. Findings It is found that 10%–20% enhancement of strength, ductility and toughness due to the incorporation of the continuous OF. Originality/value The continuous OFs are put into PLA first time to improve the strength. The fabrication method and process reported here are potentially applied in such engineering applications as aerospace, defense, auto, medicine, etc.

Application of Brillouin scattering in optic-fiber sensors

The article analyses possible applications for Brillouin scattering in optic-fiber sensors. They make it possible to do temperature and physical strain measurements with high accuracy for long line sections. The functional dependences of the output signals characteristics on parameters measured by the sensors are studied. Of particular interest are the results of the analysis of the spectral component shifts in the Brillouin light scattering depending on the fiber elongation and temperature. After a brief review of the basic theoretical principles the results of some researches aimed to expand the dynamic range and to increase spatial resolution. The results of simulation in professional design software environment OptiSystem 17.1. are described. The results are obtained by experimental research based on Brillouin reflectometer AQ8603 manufactured by “ANDO” (Japan). They show that it is possible to implement optic-fiber sensors based on Brillouin scattering in telecommunication systems, oil and gas industry, in electric-power industry, construction, aviation and space industry. The objectives for further research are to perform metrological analysis at all stages of the method implementation, to complete the base of Brillouin spectrograms for optical fiber of various types and to improve algorithms for automated processing spectra in order to expand functionality of the systems.

U-Shaped Optical Fiber Probes Coated with Electrically Doped GQDs for Humidity Measurements

The influence of the bending radius on the sensitivity of the graphene quantum dots (GQDs)-coated probe is experimentally investigated for a U-shaped probe. The fiber is bent into a U shape using the optic fiber flame heating method, and the optic fiber is enclosed in a glass tube to increase the stability of the probe. The surface of the U-shaped optical fiber was coated with electrospun fibers formed via electrospinning. Polymer materials doped with GQDs are applied to U-shaped optical fiber as humidity sensors. Graphene quantum dot nanofibers on the U-shaped optical fiber sensor to form a network structure of graphene quantum dots U-shape fiber sensor (GQDUS). The polymer network structure absorbs water molecules, which in turn affects the bending radius of the optical fiber, and changes the optical fiber spectrum. Graphene quantum dots provide optical enhancement benefits, which in turn increase the sensitivity of fiber optic sensors. The spectra monitoring system consists of an optical spectrum analyzer (OSA) and an amplified spontaneous emission (ASE). This system can be used to detect humidity changes between 20% RH and 80% RH in the chamber. Our results indicate promising applications for quantum dots probe sensors from electrospun nanofibers increasing sensitive environmental monitoring. As such, it could be of substantial value in optical sensors detection.