Study of strain-transfer of FBG sensors embedded in unidirectional composites

Pereira, Gilmar Ferreira; Frias, C.; Faria, Hugo; Frazão, Orlando; Marques, A.T.

doi:10.1016/j.polymertesting.2013.05.006

Cited by 20 publications

(9 citation statements)

References 9 publications

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“…Another important issue linked to this monitoring scheme, is related to its reliability, and specifically to the capability to transfer the local strain field from the composite to the sensors [11], [16], [20]. Overall, it is recognized that, if not accurately designed, deployed and embedded, this class of monitoring systems may have adverse effects on the life cycle of the structure.…”

Section: Investigation Of the Effectiveness And Robustness Of I Intrmentioning

confidence: 99%

Investigation of the Effectiveness and Robustness of an MEMS-Based Structural Health Monitoring System for Composite Laminates

2014

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Failure of layered composites can be triggered by small inner defects; such defects can be present inside the composite from the beginning, or can be incepted by external actions during the life cycle of the structure. Defects generally evolve, under repeated loadings, into a delamination or debonding between adjacent laminae, and cannot be easily detected as they are masked by the composite skin: ad hoc health monitoring systems are therefore required. To prevent any distortion of the composite microstructure, which may trigger by itself the nucleation of the aforementioned defects, sensors should not be embedded inside the composite; in addition, to avoid a mechanical interaction between the monitoring system and the structure, sensors should be as lighter as possible. To comply with these two major requirements, we have recently investigated a microelectromechanical system-based, surface-mounted health monitoring strategy for laminates. In this paper, we provide the results of an experimental campaign to show the effectiveness of this strategy, in terms of sensitivity to the length of delamination in standard specimens (independently of the loading conditions at the tip of the delamination), and its robustness, in terms of repeatability of the outcomes relevant to the monitored state. The experimental data are compared with analytical predictions based on beam bending theory, showing a good accuracy.

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Section: Investigation Of the Effectiveness And Robustness Of I Intrmentioning

confidence: 99%

Investigation of the Effectiveness and Robustness of an MEMS-Based Structural Health Monitoring System for Composite Laminates

2014

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“…Among a number of currently available sensors, OFSs are becoming popular due to their capability to be embedded in, or attached to, a structure without affecting its operation [1]. Compared with conventional electric and mechanical sensors, OFSs have unique properties such as light weight, compact size, long-term durability, good linearity, immunity to external electromagnetic interference and resistance to corrosion [4,5]. Among the different types of fibre sensors, fibre Bragg gratings (FBGs) are widely used and are one of the most popular technology for SHM systems [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Fabrication and Characterization of a Magnetized Metal-Encapsulated FBG Sensor for Structural Health Monitoring

Jinachandran

et al. 2018

IEEE Sensors J.

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A novel means of metal packaging of a fibre Bragg grating (FBG) sensor using stainless steel and tin, together with high temperature resistant samarium cobalt (SmCo) magnet is proposed in this paper. The inclusion of high temperature-capable SmCo magnets enable the metal packaging of the FBG sensor with magnetic capabilities. This packaged sensor can be placed in direct contact with the substrate structures such as iron pipelines and other ferromagnetic components without any adhesives, making them easily detachable and reusable. This is a significant improvement compared to other commercial fibre optic sensors which are, surface attached using epoxies or welded to the substrate. The design parameters and characteristic properties such as load, temperature and vibration sensitivity of the magnetic metalpackaged FBG sensor are studied numerically and validated experimentally to demonstrate the feasibility of using the encapsulated reusable FBGs for structural health monitoring of compatible structures.

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“…In all of the cases, the physical processes are ultimately governed by micromechanical features of the considered multi-phase materials. As extensively discussed in the literature [ 8 , 9 , 10 ], such events may be difficult to detect in real time as they usually get intercepted and grow inside the laminate and are therefore hidden by the structural skin. Accordingly, damage has to be indirectly assessed through a network of sensors able to feel the change in the structural behavior induced by the damage itself [ 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

A Multiscale Approach to the Smart Deployment of Micro-Sensors over Lightweight Structures

Capellari

Caimmi

Bruggi

et al. 2017

Sensors

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A topology optimization approach has been recently proposed to maximize the sensitivity to damage of measurements, collected through a network of sensors to be deployed over thin plates for structural health monitoring purposes. Within such a frame, damage is meant as a change in the structural health characterized by a reduction of relevant stiffness and load-carrying properties. The sensitivity to a damage of unknown amplitude and location is computed by comparing the response to the external actions of the healthy structure and of a set of auxiliary damaged structures, each one featuring reduced mechanical properties in a small region only. The topology optimization scheme has been devised to properly account for the information coming from all of the sensors to be placed on the structure and for damage depending on its location. In this work, we extend the approach within a multiscale frame to account for three different length scales: a macroscopic one, linked to the dimensions of the whole structure to be monitored; a mesoscopic one, linked to the characteristic size of the damaged region; a microscopic one, linked to the size of inertial microelectromechanical systems (MEMS) to be used within a marginally-invasive health monitoring system. Results are provided for a square plate and for a section of fuselage with stiffeners, to show how the micro-sensors have to be deployed to maximize the capability to detect a damage, to assess the sensitivity of the results to the measurement noise and to also discuss the speedup in designing the network topology against a standard single-scale approach.

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Study of strain-transfer of FBG sensors embedded in unidirectional composites

Cited by 20 publications

References 9 publications

Investigation of the Effectiveness and Robustness of an MEMS-Based Structural Health Monitoring System for Composite Laminates

Investigation of the Effectiveness and Robustness of an MEMS-Based Structural Health Monitoring System for Composite Laminates

Fabrication and Characterization of a Magnetized Metal-Encapsulated FBG Sensor for Structural Health Monitoring

A Multiscale Approach to the Smart Deployment of Micro-Sensors over Lightweight Structures

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