New Concept of Dual-Sinusoid Distributed Fiber-Optic Sensors Antiphase-Placed for the SHM of Smart Composite Structures for Offshore

Abstract

This work is a follow-up to previous research by our team and is devoted to studying a dual-sinusoidal placement of distributed fiber-optic sensors (FOSs) that are embedded inside an adhesive joint between two composite laminates. The constructed smart continuous fiber-reinforced polymer composite structure is well suited to the structural health monitoring (SHM) system for offshore wind turbine blades. Three main drawbacks of SHM through embedded distributed FOSs, however, have been identified in this article, so their impact must be analyzed. Despite existing research, the influence of the dual-sinusoidal placement under various loading conditions on structural mechanical behavior and sensing functionality has not been considered yet since its introduction. Thus, this study aims to identify the resulting strain patterns and sensing capabilities from an optimized dual-sinusoidal placement of FOSs in various loading cases through finite element modeling. Ultimately, this work illustrates the strain-measuring advantages of dual-sinusoidal FOSs, explains the correspondence between the strains measured by FOSs and that of host structures, and discusses the balance among mechanical influences, sensing functions, and monitoring coverage. It is worth noting that the current work is a still introductory concept that aims at refining key parameters that have been emphasized in previous research, before starting an applied study that will consider both numerical and validation steps on real large smart composite structures.

Advances in Embedded Sensor Technologies for Impact Monitoring in Composite Structures

“…Their findings showed that the strain rate in the small contact area affects material properties such as hardness, yield strength, and fracture toughness, as well as the plastic deformation zone created by the scratching process. They also found that higher temperatures from faster scratching speeds reduced the radius of the plastic deformation zone, shortened crack lengths, decreased brittle fractures, and minimized subsurface damage [39].…”

“…Qu et al also explored diverse methodologies for monitoring the structural response of a carbon-fiber composite cylinder under internal pressure loading conditions, utilizing integrated optical fiber sensors [38]. Huan et al studied the subsurface damage in BK7 glass when scratched with a single abrasive, looking at how strain rate and temperature affect the material [39]. They wanted to see how these factors influence material properties, the size of the plastic deformation zone, and the start and growth of cracks such as lateral and median cracks.…”

“…Carbon Nanotubes (CNTs) are rolled-up sheets in cylindrical nanostructures composed entirely of carbon atoms and with diameters ranging from 0.5-2.0 nanometers, about 100,000 times thinner than the width of a human hair. Due to their exceptional tensile strength, thermal conductivity, and electrical properties, CNTs have been explored for various applications, including as sensors in composite materials [39,[56][57][58]. When embedded in a composite material, CNTs can detect strain and temperature changes and enable remote monitoring of the structure's health in real-time.…”