Distributed Fiber Optics Sensing Applied to Laminated Composites: Embedding Process, Strain Field Monitoring with OBR and Fracture Mechanisms

Author(s)

Souza, G. ; Tarpani, J. R.

• Document type: Journal article
• Source: JOURNAL OF NONDESTRUCTIVE EVALUATION; v. 39, n. 4, p. 15-pg., 2020-10-06.

Abstract

Optical fibers (OFs) are among the most promising technologies for distributed sensing in structure health monitoring of composites. Optical backscatter reflectometer (OBR) based on Rayleigh scattering enable to use the entire length of telcom OF as sensor, giving detailed information about the stain fields in the host structure. Embedded sensors can provide many advantages over surface bonded ones in terms of reliability and accuracy of the measurements. Here, OFs were embedded in between (0/0), (0/90) and (90/90) interfaces of a [0(2)/90(2)/0(2)] glass fiber reinforced polymer (GFRP) and were further interrogated with OBR during tensile tests. Sensors were evaluated in terms of its sensing capabilities and fracture mechanism. OFs aligned in between (0/0) direction endured 5500 mu epsilon and deviated only 2.7% in the Young's modulus calculation compared to mounted strain gauges. The other directions presented problems related to matrix rich area (0/90) and air bubbles imprisoning (90/90), reducing the sensing range. After reaching the cracking state, OFs fail progressively and are still capable of acting as sensor, as was showed in a simple visible laser scattering test. For the first time, embedding, interrogation with OBR and fracture mechanisms are approached in a single study, which provide valuable information for wide application of OFs in SHM. (AU)

• FAPESP's process: 14/00099-0 - Manufacturing of composite laminates by vacuum infusion of liquid resin with optical fibers insertion for strain and damage sensing
• Grantee: Gustavo de Souza
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 15/25554-4 - Manufacture of continuous fiber-reinforced polymer composite structures with embedded optical fibers for on-line health monitoring via optical backscatter reflectometry
• Grantee: Gustavo de Souza
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation