scholarly journals Process Monitoring and Damage Detection in Composites Using FBG Sensors

Author(s):  
Xiao-fu Li ◽  
Hai-hu Yu ◽  
Hua Huang ◽  
Dong-sheng Zhang
Author(s):  
Mehmet Yildiz ◽  
Nazli G. Ozdemir ◽  
Gokhan Bektas ◽  
Casey J. Keulen ◽  
Talha Boz ◽  
...  

Research conducted on in situ process monitoring of resin transfer molded composites with fiber optic sensors is presented. A laboratory scale resin transfer molding (RTM) apparatus was designed and built with the capability of embedding fiber optic sensors and visually observing the resin filling process. Both fiber Bragg grating (FBG) and etched fiber (EF) sensors are embedded into glass fiber reinforcements in the RTM mold and used to monitor the resin flow front and cure. The cure cycle of the resin system utilized in this work is also studied using a Fresnel reflection refractometer (FRR) sensor. The results of this study show that both the FBG and EF sensors can be used efficiently for flow and cure monitoring of the RTM process. The experimental results of the EF and FRR sensors agree with those of the FBG sensors for cure monitoring.


Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3623 ◽  
Author(s):  
Shi-Zhi Chen ◽  
De-Cheng Feng ◽  
Wan-Shui Han

Damage detection of highway bridges is a significant part of structural heath monitoring. Conventional accelerometers or strain gauges utilized for damage detection have many shortcomings, especially their monitoring gauge length being too short, which would result in poor damage detection results. Under this circumstance, long-gauge FBG sensors as a novel optical sensor were developed to measure the macro-strain response of the structure. Based on this sensor, many derived damage detection methods were proposed. These methods exhibit various characteristics and have not been systematically compared. As a result, it is difficult to evaluate the state of the art and also leads to confusion for users to select. Therefore, a strict comparative study on three representative methods using long-gauge FBG was carried out. First, these methods’ theoretical backgrounds and formats were reformulated and unified for better comparison. Then, based on validated vehicle–bridge coupling simulation, these methods’ performances were tested through a series of parametric studies including various damage scenarios, vehicle types, speeds, road roughness and noise levels. The precision and reliability of three methods have been thoroughly studied and compared.


Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1728
Author(s):  
Cheng Xu ◽  
Zahra Sharif Khodaei

In this paper, a novel hybrid damage detection system is proposed, which utilizes piezoelectric actuators for guided wave excitation and a new fibre optic (FO) sensor based on Fabry-Perot (FP) and Fiber Bragg Grating (FBG). By replacing the FBG sensors with FBG-based FP sensors in the hybrid damage detection system, a higher strain resolution is achieved, which results in higher damage sensitivity and higher reliability in diagnosis. To develop the novel sensor, optimum parameters such as reflectivity, a wavelength spectrum, and a sensor length were chosen carefully through an analytical model of the sensor, which has been validated with experiments. The sensitivity of the new FBG-based FP sensors was compared to FBG sensors to emphasize the superiority of the new sensors in measuring micro-strains. Lastly, the new FBG-based FP sensor was utilized for recording guided waves in a hybrid setup and compared to the conventional FBG hybrid sensor network to demonstrate their improved performance for a structural health monitoring (SHM) application.


2019 ◽  
Vol 28 (9) ◽  
pp. 095023 ◽  
Author(s):  
Zhenwei Zhou ◽  
Chunfeng Wan ◽  
Bo Wen ◽  
Siyuan Li ◽  
Lei Zhao ◽  
...  

Author(s):  
Xiaoyi Sun ◽  
Linlin Ma ◽  
Stephen Howden ◽  
Bin Lin ◽  
Lingyu Yu

This paper discusses the temperature effects of using guided ultrasonic wave sensing in damage detection for structural health monitoring (SHM) for nuclear dry cast storage system (DCSS). The sensing capability of GUW under temperature effect is investigated and presented in this paper. Two types of sensors are studied: (a) piezoelectric wafer active sensor (PWAS) and (b) optical fiber Bragg grating (FBG) sensors. Temperature effect on the free sensors was first tested in experiments. Pristine specimens instrumented with PWAS are then investigated through sensing tests at selected temperatures. Parameters in wave modes are obtained and evaluated for changes in the waveforms at different temperatures. The investigation continues to evaluate the damage detection capability of GUW under temperature influence. The potential of using GUW for damage detection with temperature effect applied for DCSS application is discussed and concluded in the end, as well as suggestions for further work.


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