An Optical Fiber Sensor System for Remote Displacement Monitoring of Structures — Prototype Tests in the Laboratory

Abstract

This study describes a new optical fiber monitoring system to measure structural displacements. The underlying concept is based on a square fiberglass `Smart Rod' containing grooves in each face, glued into which are optical fibers containing fiber Bragg gratings (FBGs) at a succession of points along their length. The Smart Rod is rigidly fiXed at discrete points to the structure being assessed and the strain at each FBG is determined optically. The strain is thereafter converted to structural displacements. This study describes a series of `bench test' laboratory eXperiments designed to eXplore the challenges of installing the monitoring system and interpreting the results. The results from the tests are presented and discussed in the conteXt of the accuracy achievable with the proposed system. The tests have shown that the Smart Rod is sensitive enough to measure rotational movements of 0.5° and lateral movements of 0.1 mm of the fiXings in the laboratory. Recommendations are consequently made for a practical instrumentation system based upon the Smart Rod. An eXample is provided showing the Smart Rod installed in a road tunnel to monitor displacements of the tunnel lining.

Multimode interference in single mode‐multimode‐single mode fiber structure for steel beam compressive strain measurement

“…One of the useful applications of fiber‐optic sensors is for structural health monitoring (SHM). The development of fiber optic sensors for SHM has been assisted by the rapid growth of microtechnology in composite materials, vast structural designing structures, and quantitative substance process . In principle, SHM is the process of detecting the response of a structure under observation to detect anomalies, identify deterioration and recognize existing damage for further action …”

A simple load sensor based on a bent single-mode-multimode-single-mode fiber structure

“…Optical fiber sensors have been widely used in measuring various physical, chemical, and even biological parameters, as they are compact, responsive, sensitive, stable and resistant to electromagnetic interference [1][2]. They have also been recommended for applications in areas such as structural monitoring of buildings [3], estimation of metal surface roughness [4], vibration tests [5], determination of the thickness of a transparent plate [6], etc. A fiber Bragg grating (FBG) based optical sensor is widely used and by far is the most common type of fiber sensors [7][8].…”

Rede Neural RBF aplicada ao Pré-Processamento de Sinais de Deformação em Estruturas de Alumínio

“…Dentre as formas de sensoriamento, existem muitas classes de sensores que podem ser utilizados para fins de SHM, entretanto os sensores de fibra óptica têm se mostrado bastante eficientes e dessa forma ganhado espaço entre os pesquisadores da área [7]. Tal preferência se explica diante das características desses sensores, tais como, versatilidade para diferentes aplicações, robustez e estabilidade, insensibilidade à interferência eletromagnética, tamanho e peso reduzidos, segurança e grande poder de multiplexação e distribuição, ou seja, em uma mesma fibra podem ser colocadas vários sensores em diferentes posições (ou a fibra inteira funciona como um único sensor).…”