In order to increase the multiplexing density of the fiber Bragg gratings (FBGs) for a low cost per-sensor, based on the analysis of the spectrum shadow distortion (SSD), a novel successive demultiplexing scheme f...In order to increase the multiplexing density of the fiber Bragg gratings (FBGs) for a low cost per-sensor, based on the analysis of the spectrum shadow distortion (SSD), a novel successive demultiplexing scheme for FBG sensors has been developed. It is based on the optical cade division multiple access (CDMA) balanced demodulation. A high-density multiplexing-demultiplexing system for FBG sensors has been designed, and corresponding simulation carried out has demonstrated that the FBG sensors' reflective signals can still be obtained accurately and respectively, even if FBG sensors' operating bandwidths heavily overlap. The SSD has been greatly mitigated.展开更多
This paper presents the fundamental technique of phase generated carrier (PGC) and its realization on compact reconfigurable input and output (RIO) which adopts real-time and field programmable grate array (FPGA...This paper presents the fundamental technique of phase generated carrier (PGC) and its realization on compact reconfigurable input and output (RIO) which adopts real-time and field programmable grate array (FPGA) techniques. Improvement of the PGC technique is also introduced by using peak-to-peak value detection method to reduce the influence of variation of the light intensity. A four-element fibre Bragg gratings (FBG) laser sensor system is conducted in the experiment and the demodulated results demonstrate correlation coefficient as high as 0.995 with the reference signal and the dynamic range to be 120dB@63Hz.展开更多
A novel fiber Bragg grating (FBG) sensor array system based on digital phase generated carrier (PGC) demodulation and reference compensation method is proposed and set up. Experimental results confirm that the dig...A novel fiber Bragg grating (FBG) sensor array system based on digital phase generated carrier (PGC) demodulation and reference compensation method is proposed and set up. Experimental results confirm that the digital PGC demodulation can be used for wavelength-division-multiplexed FBG sensor array and the reference compensation method can reduce the environmental interference by approximately 40 dB in the frequency range from 20 Hz to 2 kHz. The minimum detectable wavelength-shift of the sensor system is 1 × 10^-3 pm/Hz^1/2.展开更多
A spatial and wavelength division multi- plexing fiber Bragg grating (FBG) sensing system is reported for monitoring the temperature and the pressure (T-P) of hot water pipeline in petrochemieal factory. The FBG s...A spatial and wavelength division multi- plexing fiber Bragg grating (FBG) sensing system is reported for monitoring the temperature and the pressure (T-P) of hot water pipeline in petrochemieal factory. The FBG sensing system has 72 channels independently, and it provides the capability to monitor large number sensors at same time. A resolution of 0.1℃ and 0.01 MPa with a measurement bandwidth of 150 Hz has been achieved.展开更多
Aiming at the requirements of installation and work environment of metal-based fiber Bragg grating(FBG)sensor,a resistance spot welding method is presented.Firstly,the effect of welding parameters on welding quality i...Aiming at the requirements of installation and work environment of metal-based fiber Bragg grating(FBG)sensor,a resistance spot welding method is presented.Firstly,the effect of welding parameters on welding quality is discussed theoretically,and a suitable resistance spot welding method for the metal-based FBG sensor is proposed for the first time.Then through serial resistance spot welding tests,the feasibility and practicability of the method are verified,and optimal welding parameters for two different tested metals are obtained.Fatigue performance test validates FBG sensors installed by the proposed method with good fatigue properties and long-term stable measurement performance.The research results can provide technical guidance for engineering structure long-term safety monitoring.展开更多
The strain-temperature cross-sensitivity problem easily occurs in the engineering strain monitoring of the self-sensing embedded with fiber Bragg grating(FBG)sensors.In this work,a theoretical investigation of the str...The strain-temperature cross-sensitivity problem easily occurs in the engineering strain monitoring of the self-sensing embedded with fiber Bragg grating(FBG)sensors.In this work,a theoretical investigation of the strain-temperature cross-sensitivity has been performed using the temperature reference grating method.To experimentally observe and theoretically verify the problem,the substrate materials,the preloading technique,and the FBG initial central wavelength were taken as main parameters.And a series of sensitivity coefficients calibration tests and temperature compensation tests have been designed and carried out.It was found that when the FBG sensors were embedded on different substrates,their coefficients of the temperature sensitivity were significantly changed.Besides,the larger the coefficients of thermal expansion(CTE)of substrates were,the higher the temperature sensitivity coefficients would be.On the other hand,the effect of the preloading technique and FBG initial wavelength was negligible on both the strain monitoring and temperature compensation.In the case of similar substrates,we did not observe any difference between temperature sensitivity coefficients of the temperature compensation FBG with one free end or two free ends.The curves of the force along with temperature were almost overlapped with minor differences(less than 1%)gained by FBG sensors and pressure sensors,which verified the accuracy of the temperature compensation method.We suggest that this work can provide efficient solutions to the strain-temperature cross-sensitivity for engineering strain monitoring with the self-sensing element embedded with FBG sensors.展开更多
Premature stress of cement concrete pavements i the coupled action of construction technique,structural ma-terial and environmental action.It is quite diffiault to accurately get the actual stress distribution merely ...Premature stress of cement concrete pavements i the coupled action of construction technique,structural ma-terial and environmental action.It is quite diffiault to accurately get the actual stress distribution merely based on the theoretical or simulation analysis.Ther efore,in-situ health monitoring is particularly si gnificant to obtain the stress or strain information for the assessment on structural perfor mance of cement concrete pavements.To contribute this topic,different kinds of FBG based sensors have been specially designed to measure the tem-perature,pressure and deformation in cement concrete pavements.A relatively long-term monitoring has been aonducted to collect the effective data after the solidification of the pavement lasts for about 15 d.Data analysis indicates that the temperature variation inside the pavement was very stable,with maximum ampltude smaller than 2.25°C in Sep.2020.The longitudinal,transverse and ver tical deformations of the pavement behaved in non-umniform distribution,and partial me asuring points suffered from large tensile force.The concrete course had better deformation resi stance than that of the soil base,and local interfacial micro void defects existed in the soil base.The preliminary results can help to understand the actual structural performance of cement concrete pavements based on the optical fiber sensing sys tem.展开更多
基金supported by the Harbin Science Research Foundation under Grant No.2003AFQXJ004
文摘In order to increase the multiplexing density of the fiber Bragg gratings (FBGs) for a low cost per-sensor, based on the analysis of the spectrum shadow distortion (SSD), a novel successive demultiplexing scheme for FBG sensors has been developed. It is based on the optical cade division multiple access (CDMA) balanced demodulation. A high-density multiplexing-demultiplexing system for FBG sensors has been designed, and corresponding simulation carried out has demonstrated that the FBG sensors' reflective signals can still be obtained accurately and respectively, even if FBG sensors' operating bandwidths heavily overlap. The SSD has been greatly mitigated.
基金supported by the National 863 Program under Grant No 2007AA03Z415.
文摘This paper presents the fundamental technique of phase generated carrier (PGC) and its realization on compact reconfigurable input and output (RIO) which adopts real-time and field programmable grate array (FPGA) techniques. Improvement of the PGC technique is also introduced by using peak-to-peak value detection method to reduce the influence of variation of the light intensity. A four-element fibre Bragg gratings (FBG) laser sensor system is conducted in the experiment and the demodulated results demonstrate correlation coefficient as high as 0.995 with the reference signal and the dynamic range to be 120dB@63Hz.
基金supported by the National 863 Program under Grant No. 2007AA03Z415.
文摘A novel fiber Bragg grating (FBG) sensor array system based on digital phase generated carrier (PGC) demodulation and reference compensation method is proposed and set up. Experimental results confirm that the digital PGC demodulation can be used for wavelength-division-multiplexed FBG sensor array and the reference compensation method can reduce the environmental interference by approximately 40 dB in the frequency range from 20 Hz to 2 kHz. The minimum detectable wavelength-shift of the sensor system is 1 × 10^-3 pm/Hz^1/2.
基金supported by Key Projects the National Natural Science Foundation of China under Grant No. 50538020the Education Department Science Foundation of Heilongjiang Province under Grant No. 11521211the Technology Department Science Foundation of Heilongjiang Province under Grant No. GC07A506.
文摘A spatial and wavelength division multi- plexing fiber Bragg grating (FBG) sensing system is reported for monitoring the temperature and the pressure (T-P) of hot water pipeline in petrochemieal factory. The FBG sensing system has 72 channels independently, and it provides the capability to monitor large number sensors at same time. A resolution of 0.1℃ and 0.01 MPa with a measurement bandwidth of 150 Hz has been achieved.
文摘Aiming at the requirements of installation and work environment of metal-based fiber Bragg grating(FBG)sensor,a resistance spot welding method is presented.Firstly,the effect of welding parameters on welding quality is discussed theoretically,and a suitable resistance spot welding method for the metal-based FBG sensor is proposed for the first time.Then through serial resistance spot welding tests,the feasibility and practicability of the method are verified,and optimal welding parameters for two different tested metals are obtained.Fatigue performance test validates FBG sensors installed by the proposed method with good fatigue properties and long-term stable measurement performance.The research results can provide technical guidance for engineering structure long-term safety monitoring.
基金supported by the National Natural Science Foundation of China(Grant No.52068014)Key Research&Development Projects in the Guangxi Autonomous Region(Grant No.GUIKE AA20302006)Major Construction Program of the Science and Technological Innovation Base in the Guangxi Autonomous Region(Grant No.2018-242-G02).
文摘The strain-temperature cross-sensitivity problem easily occurs in the engineering strain monitoring of the self-sensing embedded with fiber Bragg grating(FBG)sensors.In this work,a theoretical investigation of the strain-temperature cross-sensitivity has been performed using the temperature reference grating method.To experimentally observe and theoretically verify the problem,the substrate materials,the preloading technique,and the FBG initial central wavelength were taken as main parameters.And a series of sensitivity coefficients calibration tests and temperature compensation tests have been designed and carried out.It was found that when the FBG sensors were embedded on different substrates,their coefficients of the temperature sensitivity were significantly changed.Besides,the larger the coefficients of thermal expansion(CTE)of substrates were,the higher the temperature sensitivity coefficients would be.On the other hand,the effect of the preloading technique and FBG initial wavelength was negligible on both the strain monitoring and temperature compensation.In the case of similar substrates,we did not observe any difference between temperature sensitivity coefficients of the temperature compensation FBG with one free end or two free ends.The curves of the force along with temperature were almost overlapped with minor differences(less than 1%)gained by FBG sensors and pressure sensors,which verified the accuracy of the temperature compensation method.We suggest that this work can provide efficient solutions to the strain-temperature cross-sensitivity for engineering strain monitoring with the self-sensing element embedded with FBG sensors.
基金supported by the National Natural Science Foundation of China(Grant No.51908263,11932008,DL2021175003L and G2021175026L)Provincial Projects(2020-0624-RCC-0013 and JK2021-18)。
文摘Premature stress of cement concrete pavements i the coupled action of construction technique,structural ma-terial and environmental action.It is quite diffiault to accurately get the actual stress distribution merely based on the theoretical or simulation analysis.Ther efore,in-situ health monitoring is particularly si gnificant to obtain the stress or strain information for the assessment on structural perfor mance of cement concrete pavements.To contribute this topic,different kinds of FBG based sensors have been specially designed to measure the tem-perature,pressure and deformation in cement concrete pavements.A relatively long-term monitoring has been aonducted to collect the effective data after the solidification of the pavement lasts for about 15 d.Data analysis indicates that the temperature variation inside the pavement was very stable,with maximum ampltude smaller than 2.25°C in Sep.2020.The longitudinal,transverse and ver tical deformations of the pavement behaved in non-umniform distribution,and partial me asuring points suffered from large tensile force.The concrete course had better deformation resi stance than that of the soil base,and local interfacial micro void defects existed in the soil base.The preliminary results can help to understand the actual structural performance of cement concrete pavements based on the optical fiber sensing sys tem.