A Fiber Bragg Grating-Based Gap Elongation Sensor for The Detection of Gap Elongation in Bolted Flange Connection

Many attempts have been made by embedding a strain gauge sensor into the bolt shank to directly monitor the looseness of bolted structures. This application is constrained by many factors, including massive cabling connection, shortcomings of this sensor in harsh conditions, and low efficiency for high temperature applications. Therefore, fiber Bragg grating (FBG) sensing technology is a good alternative to solve the problem. In this article, an FBG-based gap elongation sensor was developed by embedding the sensor into a Teflon tube and clamping on the metal base structure. Several tests were carried out to calibrate the strain-sensitive coefficient of the sensor and also to determine the stability, linearity, and repeatability of the sensor for gap strain measurement. The strain sensitivity of the sensor was determined by a standard tensile test, with the strain sensitivity values ranging from 0.4221 pm/µε to 0.5245 pm/µε. During the calibration test, the FBG sensors showed excellent linearity and repeatability of less than 0.1% and 5% errors, respectively. The experimental results demonstrated a linear relationship between the applied force and the FBG sensor wavelength. Furthermore, the experimental results demonstrated acceptable linearity and stability of the sensor when subjected to bending loads with overall repeatability errors of less than 10%. This proposed method provides an alternative approach to monitor bolted gap elongation and characterize bolt looseness

A Fiber Bragg Grating-Based Gap Elongation Sensor for The Detection of Gap Elongation in Bolted Flange Connection

Many attempts have been made by embedding a strain gauge sensor into the bolt shank to directly monitor the looseness of bolted structures. This application is constrained by many factors, including massive cabling connection, shortcomings of this sensor in harsh conditions, and low efficiency for high temperature applications. Therefore, fiber Bragg grating (FBG) sensing technology is a good alternative to solve the problem. In this article, an FBG-based gap elongation sensor was developed by embedding the sensor into a Teflon tube and clamping on the metal base structure. Several tests were carried out to calibrate the strain-sensitive coefficient of the sensor and also to determine the stability, linearity, and repeatability of the sensor for gap strain measurement. The strain sensitivity of the sensor was determined by a standard tensile test, with the strain sensitivity values ranging from 0.4221 pm/µε to 0.5245 pm/µε. During the calibration test, the FBG sensors showed excellent linearity and repeatability of less than 0.1% and 5% errors, respectively. The experimental results demonstrated a linear relationship between the applied force and the FBG sensor wavelength. Furthermore, the experimental results demonstrated acceptable linearity and stability of the sensor when subjected to bending loads with overall repeatability errors of less than 10%. This proposed method provides an alternative approach to monitor bolted gap elongation and characterize bolt looseness

Development of fibre bragg grating (FBG) based pressure transducer with temperature compensation

In this work, an aluminium diaphragm fibre Bragg grating (FBG) pressure transducer with temperature compensation is been presented. FBG based sensors good for some applications such as pressure vessel, biomedical and combustion chamber. One of the greatest challenges for an FBG based transducer is the inconsistency in output wavelength due to temperature variations. This lead to huge variation pressure readings. In this study, two FBG are bonded on the diaphragm and base surface of the pressure transducer, respectively. The inconsistency of wavelength was eliminated by applying the temperature compensation technique. The result shows that this FBG pressure transducer has a sensitivity of 2.849 nm/MPa and a linear fitting coefficient of 99.97% in a pressure range from 0 to 0.2 MPa. This FBG pressure transducer is proven to be suitable for pressure measurement of gas or liquid with an average error of 1.97%

Review of high sensitivity fibre-optic pressure sensors for low pressure sensing

Fibre Bragg grating (FBG) pressure sensors show a great potential in replacing conventional electrical pressure sensors due to their numerous advantages. However, increasing their pressure sensitivity performance for low hydrostatic pressure measurement is still a challenge. This paper reviewed recent pressure sensitivity enhancement methods that could be divided into two groups, namely intrinsic and extrinsic. For the intrinsic enhancement method, this paper reviewed polymer FBGs, special fibre sensors, interferometric sensors, and special grating sensors. For the extrinsic enhancement method, polymer-based pressure transducers, diaphragm-based pressure transducers, and other structure-based pressure transducers were reviewed in detail

Investigation of low frequency fibre Bragg grating accelerometer based on thermoplastic cantilever beam

Vibration measurement technique is very important in structural integrity monitoring. Various fibre Bragg grating (FBG) based accelerometers have been developed for vibration measurement. However, most of the researchers focused on high frequency monitoring and only few reported works are based on low frequency measurement. Therefore, this paper presented a low frequency FBG accelerometer based on Polyphenylene Ether (PPE) thermoplastic cantilever beam. The proposed FBG accelerometer was attached to a shaker and vibration signals were given with variations in frequency and acceleration. As a result, the FBG accelerometer has a sensitivity of 110 pm/g and natural frequency of 9 Hz. The proposed accelerometer capable to detect low frequency of 2 Hz at 0.04 g which is suitable for utilisation in seismic monitoring of earthquake

A highly sensitive multiplexed FBG pressure transducer based on natural rubber diaphragm and ultrathin aluminium sheet

Pressure measurement with a good sensitivity has always been a concern in most of the engineering applications and biomedical field. In this paper, a multiplexed FBG bonded on an ultrathin aluminium sheet which act as a cantilever deflected due to a deformation from a natural rubber based diaphragm has been proposed and studied. By using two gratings inscribed on a single optical fibre which senses the positive and negative strain has enhanced the sensitivity of the pressure transducer recorded at 329.56 pm/kPa or corresponding to 10.7893 kPa−1 across the range of 0 to 10 kPa with a good linearity of 99.76%. Furthermore, the thermal cross-sensitivity is compensated

Delamination detection in thin-walled composite structures using acoustic pitch-catch technique with Fiber Bragg Grating Sensors.

Structural health monitoring (SHM) of a composite structure is essential in maintaining the integrity of the structure. Over the years, various studies have reported on the use of conventional electrical sensors in analysing acoustic wave propagation for delamination detection. However, electrical sensors are associated with drawbacks such as high signal attenuation, are prone to electromagnetic interference (EMI) and are not suitable for harsh environments. Therefore, this paper reported on the use of fiber Bragg grating (FBG) sensors for delamination detection. Two composite structures with delamination sizes of 10 cm × 2 cm and 10 cm × 6 cm were fabricated. Two FBGs were bonded before and after the delamination. In addition, three trials of impacts were induced at the centre of the structure. Multiple signal parameters were obtained and analysed, which were the time delay, amplitude difference and velocity difference. The experimental results revealed that the time delay, amplitude and velocity analysis varied for both the delamination sizes with an average percentage of 42.36%, 97.09% and 42.39%, respectively. Therefore, it was confirmed that the increase in delamination size resulted in a longer time delay, higher signal amplitude attenuation and slower wave propagatio

High-Resolution Fibre Bragg Grating (FBG) Pressure Transducer for Low-Pressure Detection

Fibre Bragg grating (FBG) pressure sensor has shown great potential in replacing the conventional electrical pressure sensor due to its adaptability to the harsh environment. However, increasing its resolution for low-pressure measurement is still a challenge. In this work, the bonding of FBG to a rubber-based diaphragm pressure transducer was proposed. The proposed pressure transducer had enhanced the sensitivity to 117.7 pm/kPa across the range of 40 kPa, which corresponded to the pressure resolution of 0.008 kPa. Furthermore, the proposed pressure transducer possessed a reference FBG for temperature compensation, where the overall temperature effect was less than 1%

A Study Of Fiber Bragg Grating Temperature Sensor For Under Water Temperature Monitoring

Fiber Bragg grating (FBG) sensors have been widely utilized as a sensor for measuring strain, temperature, and vibration measurements. In this study, an optical FBG sensor system was developed to monitor the temperature fluctuation in water. The sensor was delicately packaged to eliminate the influence of strain acting on the sensor. The sensor had been submerged in iced water and the temperature was constantly increased by using an electric immersion heater. The experimental data were obtained to determine the temperature sensitivity of the FBG sensor. It is found that the relationship between the changes in temperature and changes in Bragg wavelength is virtually higher in linearity with R2 = 0.9997 and has superior sensitivity which is 10.13 pm/°C. This finding proves that the FBG sensor could be a good candidate for temperature-sensing device

Design and fabrication of smart mousetrap

The objective of this thesis is to design and fabricate a smart mousetrap to improve product in the market to catch more than one mouse and the mousetrap is safe for human and pets at home. This mousetrap is easy to use and not complicated. It also can be use oftenly, which mean that it can be use over and over again. The mousetrap also has no any poisonous or harmful substance use and the most important is that the mousetrap is safe to human where it will not injure the user. It also can catch up to maximum of four mouse. The material used in fabricating this mousetrap is galvanized iron sheet because the galvanized iron is cheap and easy to fabricate. Other materials that are used in fabricating this mousetrap are Perspex, fastener such as screws and rivet, handle, lock and door slot. The process have been involved in the project are cutting, bending, drilling and riveting. Solidwork Simulation Xpress software is used to simulate the stress analysis on critical part of the mousetrap. From the observation, handle support will be a critical part to sustain a maximum load. Lastly, the objective of this project has been achieved where the mousetrap can catch up to more than one mouse and it is safe to be use where it does not bring harm or any injury to the user and also pets at hom