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Interfacial nanocomposite sensors (sQRS) for the core monitoring of polymer composites’ fatigue and damage analysis
摘要： The quick development of the smart factory and prognostic and health management (PHM), in the fields of aeronautic, automotive and green energies, is evidencing a need for sensors able to monitor the behavior of composite materials all along their life at the closest of the matter. In situ fabricated conductive polymer nanocomposite (CPC) sensors are bringing an interesting solution to this prospect as they can be integrated homogeneously in the core of composites to probe their deformations and damage. In particular fatigue which is one important mode of failure of polymer composites can be monitored from early signs of damage until the final breakage by analyzing the piezo-resistive response of quantum resistive strain sensors (sQRS) made of carbon nanotubes. We have developed all these aspects in the paper taking the example of a classical glass fibers/epoxy composite instrumented in its core with two sQRS to monitor its short and long term fatigue behavior.
关键词： damage detection,fatigue,structural health monitoring,Piezo-resistive strain sensors,conductive polymer nanocomposites,carbon nanotubes,polymer composites
更新于2025-09-10 09:29:36
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Optimisation of optical fibre using micro-braiding for structural health monitoring
摘要： Structural health monitoring is a fast growing area used to assess the state of various structures such as aircraft, building, bridge, wind turbine, pipe, automobile through appropriate data processing and interpretation. This article presents a novel technique of optimising the conventional optical fibres used for structural health monitoring, in order to improve their mechanical properties, and handling during the manufacturing process by micro-braiding the optical fibres. This study investigates and compares the tensile properties of the both micro-braided optical fibre and conventional optical fibres through uniaxial tensile tests. Experimental results show 85% improvement in strain at failure for the micro-braided optical fibre when compared to the optical fibres. Moreover, interfacial shear strength comparison, of the braiding yarn, between optical fibres and micro-braided optical fibre (carried out through micro-bond test) has also been conducted. In addition, the effect of embedding both micro-braided and conventional optical fibre in composite was also investigated by three-point bend test. Overall, the mechanical performance of the composite was not affected by the presence of micro-braided optical fibre. This article will also discuss the process and the advantage of micro-braided optical fibre for structural health monitoring.
关键词： braid angle,micro-braided optical fibre,Structural health monitoring,composites,conventional optical fibre
更新于2025-09-10 09:29:36
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Selection and Characterization of Packaged FBG Sensors for Offshore Applications
摘要： With the development in the exploitation of maritime resources, the structural health monitoring (SHM) of offshore structures becomes necessary. This study focuses on addressing the practical issues of application of fiber Bragg grating (FBG) sensors for the SHM of offshore structures, in particular an FPSO (floating, production, storage, and offloading unit) vessel. Due to the harsh marine environment and tough working conditions, the FBG sensors must have sufficient protection and good repeatability for long-term monitoring. Thorough research has been conducted to identify the most suitable, commercially available protection packaging for FBG sensors for offshore applications. Further, the performance of the selected FBG sensor packaging is tested under conditions of strong sunlight, heavy rain, and salty water in order to emulate the marine environment. Moreover, the installation method of the packaged FBG sensors is equally important, as it ensures the repeatability and durability of the sensors for their long-term performance. It is shown that the packaged FBG sensors can be installed using resin-based epoxy to maintain the repeatability of the sensor over the long-term. Further, the packaged FBG sensors are installed and tested on a simple FPSO model. The experimental results under full load and ballast draft conditions show that the proposed FBG sensors are competent for the SHM of offshore structures.
关键词： FBG sensor,structural health monitoring,FPSO,offshore structure
更新于2025-09-10 09:29:36
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An overview of corrosion defect characterization using active infrared thermography
摘要： Corrosion is considered a destructive phenomenon that affects almost all metals. There is a variety of corrosion monitoring and measurement techniques being deployed across industries. However, very few techniques are ideally characterised with non-contact, non-intrusive, on-line and direct features for measuring the accurate corrosion rate or actual metal loss. Infrared Thermography (IRT) allows the recording of electromagnetic waves emitted from objects by using an infrared imaging system, such as an infrared camera. IRT is an online method of Non-Destructive Testing (NDT) meaning the delays in receiving results from a laboratory experienced in many NDT techniques can be eliminated. It is non-intrusive which means no process disruption and downtime will be imposed to the production line. It is also a non-contact method which mitigates the hazard occurrence and need for highly experienced personnel.
关键词： Infrared thermography,Non-destructive testing,Corrosion monitoring,Structural health monitoring,Image processing
更新于2025-09-04 15:30:14
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Non-contact fatigue crack detection in civil infrastructure through image overlapping and crack breathing sensing
摘要： Fatigue cracks are of critical structural safety concern in civil infrastructure. Many existing fatigue crack sensing methods are contact-based, hence extensive human operation is necessary for sensor and/or actuator deployment. In this study, we propose a vision-based non-contact approach to detect fatigue cracks through image overlapping. We treat crack breathing behavior, the small cyclic movement of the crack perpendicular to the crack path under repetitive fatigue loads, as a robust indicator for crack identification. The differential image features provoked by a breathing crack can be extracted, enhanced, and visualized through a series of image processing techniques. The performance of the proposed approach is experimentally validated through two laboratory setups including a small-scale steel compact specimen and a large-scale bridge to cross-frame connection specimen. Test results demonstrate the capability of the proposed approach in reliably identifying the fatigue crack, even the true crack is surrounded by other non-crack features.
关键词： Computer vision,Bridges,Civil infrastructure,Feature matching,Non-contact sensing,Image processing,Structural health monitoring,Image registration,Breathing crack,Fatigue crack detection
更新于2025-09-04 15:30:14
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Regenerated fiber Bragg grating sensing system for ultrasonic detection in a 900 °C environment
摘要： Heat-resistant composites, such as ceramic matrix composites (CMCs) and heat-resistant carbon fiber reinforced plastics (CFRPs), are expected to be used for aircraft engine parts. The development of reliable heat-resistant composite materials requires the use of nondestructive test (NDT) techniques for evaluating the progression of damage during material testing at elevated temperatures. Furthermore, structural health monitoring (SHM) technologies that operate under harsh environments are expected to be realized for monitoring heat-resistant composite structures. To provide potential solutions for the establishment of such technologies, this research developed a heat-resistant ultrasonic sensor based on a regenerated fiber-optic Bragg grating (RFBG). First, we fabricated an RFBG by annealing a normal FBG sensor. Because the RFBG exhibits high heat resistance at temperatures of 1000 °C, the sensor achieved stable ultrasonic detection at an elevated temperature. In addition, we attempted to use a π-phase-shifted FBG (PSFBG) as the seed grating to construct an ultrasonic sensor with enhanced performance. As a result, the R(PS)FBG sensor possessed a very short effective gauge length and achieved a broad frequency response to ultrasonic waves with frequencies greater than 1.5 MHz. The broadband detectability enables the R(PS)FBG sensor to acquire an accurate response to ultrasonic waves. Hence, we believe the regenerated Bragg grating-based ultrasonic sensors can contribute to establishing an effective nondestructive evaluation method for composite materials, thereby enabling a structural health monitoring system for a composite-made structure operating under extreme high-temperature environments.
关键词： structural health monitoring (SHM),ultrasonic detection,nondestructive test (NDT),regenerated fiber-optic Bragg grating (RFBG),high-temperature environment,Heat-resistant composites
更新于2025-09-04 15:30:14
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Nonlinearities Associated with Impaired Sensors in a Typical SHM Experimental Set-Up
摘要： Structural Health Monitoring (SHM) gives a diagnosis of a structure assessing the structural integrity and predicting the residual life through appropriate data processing and interpretation. A structure must remain in the design domain, although it can be subjected to normal aging due to usage, action of the environment, and accidental events. SHM involves the integration of electronic devices in the inspected structure that sometimes are Piezoelectric Transducers (PZT). These are lightweight and small and can be produced in different geometries. They are used both in guided wave-based and electromechanical impedance-based methods. The PZT bonding requires essential steps such as preparation of the surfaces, application of the adhesive, and assembly that make the bonding process not so easy to be realised. Furthermore, adhesives are susceptible to environmental degradation. Transducer debonding or non-uniform distributed glue underneath the sensor causes the reduction of the performance and can affect the reliability of the SHM system. In this paper, a sensor diagnostic method for the monitoring of the PZT operational status is proposed in order to detect bonding defect/damage between a PZT patch and a host structure. The authors propose a method based on the nonlinear behaviour of the contact PZT/structure that allows the identification of the damaged PZT and the geometrical characterization of the debonding. The feasibility of the diagnostic procedure is demonstrated by numerical studies and experiments, where disbonds were created by inhibiting the adhesive action on a part of the interface through Te?on ?lm. The proposed method can be used to evaluate the sensor functionality after an extreme loading event or over a long period of service time.
关键词： impaired sensor,Structural Health Monitoring,Time of Flight,subharmonics
更新于2025-09-04 15:30:14