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020 _aTHE0009339(Local)
_qhardback
040 _aUMP
_beng
_cUMP
_erda
090 _aFTKMA .V67 2021 r Thesis
100 1 _aVorathin Epin,
_eauthor.
245 1 0 _aAccuracy improvement of rubber-based diaphragm fibre bragg grating pressure sensors /
_cVorathin Epin
264 1 _aKuantan, Pahang :
_bUMP,
_c2021
264 4 _c© 2020
300 _axx, 205 pages :
_billustrations (some color) ;
_c30 cm. +
_e1 CD ROM
336 _atext
_2rdacontent
336 _atext
_2rdacontent
337 _aunmediated
_2rdamedia
337 _acomputer
_2rdamedia
338 _avolume
_2rdacarrier
338 _acomputer disc
_2rdacarrier
347 _atext file
_bPDF
_2rda
500 _aFaculty of Mechanical and Automotive Engineering Technology
502 _aThesis (Doctor of Philosophy) -- Universiti Malaysia Pahang – 2021
504 _aIncludes bibliographical references
520 3 _aWater level sensing has become a great importance in various industrial applications. Due to its advantages, fibre Bragg grating (FBG) pressure sensor has been introduced to overcome the drawbacks of electrical pressure sensor for hydrostatic pressure based water level sensing. Over the years, various studies have been reported on the use of rubberbased diaphragms to increase the pressure sensitivity of the bare FBG pressure sensors. However, high thermal expansion of the rubber material is making the FBG pressure sensors more sensitive to the temperature effects due to the increased temperature sensitivity. This drawback can result in inaccuracy of the pressure sensors. Therefore, the main objective of this study is to eliminate the temperature sensitivity in order to improve the accuracy of the rubber-based diaphragm FBG pressure sensors. Here, four types of pressure sensors were developed to investigate the temperature effects. Type I pressure sensor was simply by bonding the bare FBG on rubber diaphragm without temperature compensation. Type II pressure sensor was similar to type I but with reference FBG temperature compensation technique. Type III and type IV pressure sensors were based on differential FBG and bandwidth modulation technique. All pressure sensors underwent pressure and temperature variations. Under pressure variation across 20 kPa, all the pressure sensors obtained high pressure sensitivity at 274.8 pm/kPa, 275.0 pm/kPa, 641.9 pm/kPa and -275.1 pm/kPa. Besides, type IV pressure sensor is also capable to be monitored using photodetector (PD) with the pressure sensitivity of -12.1 mV/kPa. Under temperature variation across 50 °C, all pressure sensors obtained high temperature sensitivity of more than 44.0 pm/°C when monitored based on single wavelength. However, the differential FBG and bandwidth modulation techniques obtained negligible average temperature sensitivity at only 0.5 pm/°C and -0.3 pm/°C. Due to this, the measured pressure and water level using type I and type II pressure sensors was far off from the actual readings with the percentage of error at 35% and 16.55%. Type III and type IV pressure sensors obtained an average highest percentage of accuracy error at only 3.24% and 5.51%. This is because the temperature effects have no influence on temperature insensitive pressure sensors. As a conclusion, the findings of this study shows that the use of rubber diaphragm with differential FBG and bandwidth modulation techniques capable to eliminate away the temperature sensitivity and retain the high pressure sensitivity of the pressure sensors. The temperature-independent high pressure sensitivity characteristics enabled the pressure sensors to be used for low pressure sensing in the fields of hydrology, agriculture, food processing and water supply system with better accuracy and reducing false information
610 2 0 _aFaculty of Mechanical and Automotive Engineering Technology
_xDissertations
650 0 _aUniversities and colleges
_xDissertations
650 0 _aTheses
942 _2lcc
_cTHESIS