As a critical structure of aerospace equipment,aluminum alloy stiffened plate will influence the stability of spacecraft in orbit and the normal operation of the system.In this study,a GWO-ELM algorithm-based impact d...As a critical structure of aerospace equipment,aluminum alloy stiffened plate will influence the stability of spacecraft in orbit and the normal operation of the system.In this study,a GWO-ELM algorithm-based impact damage identification method is proposed for aluminum alloy stiffened panels to monitor and evaluate the damage condition of such stiffened panels of spacecraft.Firstly,together with numerical simulation,the experimental simulation to obtain the damage acoustic emission signals of aluminum alloy reinforced panels is performed,to establish the damage data.Subsequently,the amplitude-frequency characteristics of impact damage signals are extracted and put into an extreme learning machine(ELM)model to identify the impact location and damage degree,and the Gray Wolf Optimization(GWO)algorithm is employed to update the weight parameters of the model.Finally,experiments are conducted on the irregular aluminum alloy stiffened plate with the size of 2200 mm×500 mm×10 mm,the identification accuracy of impact position and damage degree is 98.90% and 99.55% in 68 test areas,respectively.Comparative experiments with ELM and backpropagation neural networks(BPNN)demonstrate that the impact damage identification of aluminum alloy stiffened plate based on GWO-ELM algorithm can serve as an effective way to monitor spacecraft structural damage.展开更多
Fatigue crack prediction is a critical aspect of prognostics and health management research.The particle filter algorithm based on Lamb wave is a potential tool to solve the nonlinear and non-Gaussian problems on fati...Fatigue crack prediction is a critical aspect of prognostics and health management research.The particle filter algorithm based on Lamb wave is a potential tool to solve the nonlinear and non-Gaussian problems on fatigue growth,and it is widely used to predict the state of fatigue crack.This paper proposes a method of lamb wavebased early fatigue microcrack prediction with the aid of particle filters.With this method,which the changes in signal characteristics under different fatigue crack lengths are analyzed,and the state-and observation-equations of crack extension are established.Furthermore,an experiment is conducted to verify the feasibility of the proposed method.The Root Mean Square Error(RMSE)of the three different resampling methods are compared.The results show the system resampling method has the highest prediction accuracy.Furthermore,the factors affected by the accuracy of the prediction are discussed.展开更多
In this paper, a plate shape perception technique based on quasi-distributed fiber Bragg grating(FBG) array and space surface reconstruction algorithm is proposed. Firstly, in order to make curvature continuous, the b...In this paper, a plate shape perception technique based on quasi-distributed fiber Bragg grating(FBG) array and space surface reconstruction algorithm is proposed. Firstly, in order to make curvature continuous, the bicubic plane interpolation algorithm is studied. Then, taking the simulated satellite bulkhead structure as the research object, we research the space surface reconstruction algorithm based on orthogonal curvature and coordinate transformation(translation and rotation). Finally, a four-sided fixed plate deformation monitoring system based on quasi-distributed FBG sensors network and surface reconstruction algorithm is built. Many experiments are conducted to verify the reliability and accuracy of the algorithm. The proposed algorithm provides a new method for three-dimensional reconstruction of spacecraft structure.展开更多
Ship type identification is an important part of electronic reconnaissance. However, in the existing methods, such as statistical-based methods and fuzzy-mathematics-based methods, the information acquired by the pass...Ship type identification is an important part of electronic reconnaissance. However, in the existing methods, such as statistical-based methods and fuzzy-mathematics-based methods, the information acquired by the passive sensor is not fully utilized, and there is a certain ambiguity in the assignment relationship of the emitters-ship. They can’t conclude the accurate and reliable assignment relationship of the emitters-ship. Therefore, this paper proposes a comprehensive correlation discriminant method to obtain a more reliable and comprehensive emitters-ship assignment, and then uses information entropy method to identify the type of the target ship on the basis of this association and assign the credibility. The simulation results show that this algorithm can effectively solve the problem of target ship type identification using the information of multi-passive sensors.展开更多
<div style="text-align:justify;"> A new planar waveguide laser was demonstrated. The output energy of 400 mW was achieved by a single waveguide laser;the slope efficiency was 61%. The single waveguide ...<div style="text-align:justify;"> A new planar waveguide laser was demonstrated. The output energy of 400 mW was achieved by a single waveguide laser;the slope efficiency was 61%. The single waveguide laser can expand to waveguide laser group and waveguide laser array to produce higher energy. </div>展开更多
A low-energy ion spectrometer(LEIS) for use aboard three-axis stabilized spacecraft has been developed to measure ion energy per charge distribution in three-dimensional space with good energy-, angular-and temporal-r...A low-energy ion spectrometer(LEIS) for use aboard three-axis stabilized spacecraft has been developed to measure ion energy per charge distribution in three-dimensional space with good energy-, angular-and temporal-resolutions. For the standard top-hat electrostatic analyzer used widely in space plasma detection, three-axis stabilized spacecraft makes it difficult to obtain complete coverage of all possible ion arrival directions. We have designed angular scanning deflectors supplementing to a cylindrically symmetric top-hat electrostatic analyzer to provide a half-space field of view as 360°×90°(–45°–+45°), and fabricated the LEIS flight model for detecting magnetospheric ions in geosynchronous orbit. The performance of this payload has been evaluated in detail by a series of simulation and environmental tests, and the payload has also been calibrated through laboratory experiments using a low-energy ion source. The results show that capabilities of the LEIS payload are in accordance with the requirements of a magnetospheric mission.展开更多
A Chinese geosynchronous satellite was launched on June 23,2020.It carried a plasma detection package to monitor the space environment around the orbit.Here we report the inflight performance of a low energy ion spect...A Chinese geosynchronous satellite was launched on June 23,2020.It carried a plasma detection package to monitor the space environment around the orbit.Here we report the inflight performance of a low energy ion spectrometer(LEIS),one of the primary instruments in the plasma detection package,and its initial observations in flight.Benefiting from the state-of-the-art design of a top-hat electrostatic analyzer cooperated with angular scanning deflectors,three-dimensional measurement of ions in space with a large field of view of 360°×90°and a wide energy range from 50 eV to 25 keV per charge has been achieved.The differential energy flux spectra of ions around the orbit have shown clear signatures of surface charging and storm/substorm ion injections.The occurrence of surface charging could be caused by the lack of photoemission at the Earth's eclipse(near the midnight)or the storm energetic electron injection at the dawn sector.The present results demonstrated a good performance of the LEIS payload in flight for monitoring the space ion environment around the orbit.In situ measurements of the LEIS payload provide us an opportunity to understand the magnetospheric ion dynamics and forecast the associate space weather impacts.展开更多
To enhance the measurement precision of eddy current sensor in particular environments such asextreme temperature changes and limited available space in aerospace, we optimized the structural parameters ofthe traditio...To enhance the measurement precision of eddy current sensor in particular environments such asextreme temperature changes and limited available space in aerospace, we optimized the structural parameters ofthe traditional dual-coil eddy current sensor probe by electromagnetic field analysis and finite element simulationmodeling, and further presented the criteria for determining the optimal coil distance of the dual-coil probe. Thesimulation results are verified by setting up an experimental platform. For the extreme temperature environment,the displacement measurement error caused by the full range temperature variation of the dual-coil sensor underthe optimal distance is less than 21.0% of that of the single-coil sensor. On this basis, we analyzed and verified thethermal stability of the structurally optimized dual-coil eddy current sensor. After temperature compensation,the displacement measurement accuracy can reach 14.9 times more accurate than that of the single-coil sensor.The method proposed in this paper can provide a design reference for the structural optimization of the axialdual-coil eddy current sensor probe.展开更多
A visual reconstruction method was proposed based on fiber Bragg grating(FBG)sensors and an intelligent algorithm,aiming to solve the problems of low accuracy and complex reconstruction process in conventional reconst...A visual reconstruction method was proposed based on fiber Bragg grating(FBG)sensors and an intelligent algorithm,aiming to solve the problems of low accuracy and complex reconstruction process in conventional reconstruction methods of flexible structures.Firstly,the wavelength data containing structural strain information was captured by FBG sensors,together with deformation displacement information.Subsequently,a predicted model was built based on an extreme learning machine(ELM)and further optimized by the particle swarm optimization(PSO)algorithm.Different deformation patterns were tested on an aluminum alloy plate,indicating the ability of the predicted model to produce the deformation displacement for reconstruction.The experimental results show that the maximum error can be as low as 0.050 mm,which verifies that the proposed method is feasible and satisfied with the deformation monitoring of the spacecraft structure.展开更多
The laser dazzling effect has always been a crucial issue for the scientific community.Nevertheless,the experiments to study the laser dazzling effect may cost a lot.Therefore,the technology of simulation is promising...The laser dazzling effect has always been a crucial issue for the scientific community.Nevertheless,the experiments to study the laser dazzling effect may cost a lot.Therefore,the technology of simulation is promising for this field.Additionally,the effectiveness of the laser dazzling needs to be evaluated by a no reference cost functions.A general model of CCD is proposed in this paper.Additionally,two cost functions are proposed to evaluate the image.The simulation result based on the model shows feasibility of the cost functions.Afterwards an experiment is carried out to testify these cost functions.Different factors include the intensity of the irradiance,the beam radius and the dazzling location of the laser are taken into consideration.The experimental result shows the cost functions have monotonous relationship with the degree of the laser dazzling.This result indicates that the cost functions can be used in the field to measure the degree of the laser dazzling.展开更多
In order to address the future power generation needs for scientific exploration of the lunar permanently shadowed regions,this paper proposes a laser wireless power transfer(LWPT)system from a power source at the ill...In order to address the future power generation needs for scientific exploration of the lunar permanently shadowed regions,this paper proposes a laser wireless power transfer(LWPT)system from a power source at the illuminated rim of the crater to a photovoltaic laser receiver on a rover exploring inside the permanently shadowed region.To fill a gap between the conceptual design and an operational system,the required conditions were analyzed regarding the effects of beam alignment and shaping,wavelength-dependent conversion efficiency on the system level efficiency,and a ground-based prototype system was established.Electric–electric efficiency of 11.55%was measured at a ground transmission distance of 10 m.The study is complemented by discussing optimization analysis for subsequent research,can be more effective and employed in the future.展开更多
The seismic activities on the Earth can produce a disturbance of the electromagnetic field and particles in the ionosphere. The search coil magnetometer(SCM) mounted on China Seismo-Electromagnetic satellite(CSES) is ...The seismic activities on the Earth can produce a disturbance of the electromagnetic field and particles in the ionosphere. The search coil magnetometer(SCM) mounted on China Seismo-Electromagnetic satellite(CSES) is designed to measure the magnetic field fluctuation of low frequency electromagnetic waves in the frequency range of 10 Hz–20 k Hz. The SCM comprises a three-axis search coil sensor mounted on a 4.5 m boom and an electronic box inside satellite module. The sampling rate of the SCM is 51.2 k Hz and the time resolution of the power spectrum density(PSD) is 2 s. The frequency resolution is 12.5 Hz.There are three operation modes: survey, detailed survey and calibration. In the survey mode, the SCM can provide a PSD in the whole frequency range of 10 Hz–20 k Hz and wave forms in the low frequency range below 2 k Hz while in the detailed survey mode the SCM can provide both PSD and wave forms in the whole frequency range of 10 Hz–20 k Hz. The sensitivity of the SCM instrument is 5.0×10^(-4) n T Hz^(-1/2) at 10 Hz, 5.0×10^(–5) n T Hz^(-1/2) at 200 Hz, 3.4×10^(-5) n T Hz^(-1/2) at 2 k Hz and 1.1×10^(-4) n T Hz^(-1/2) at 20 k Hz. The telemetry rate is ~0.85 Mbps in the survey mode and ~3.0 Mbps in the detailed survey mode. The phase difference between three axes can be made generally with a precision of less than 1.0°. The dynamic range of the SCM instrument is over 100 d B. The orthogonality of three mechanical axes of search coil senor is better than 0.13°. The performance of SCM can satisfy the requirement of scientific objectives of CSES mission.展开更多
Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipmen...Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipment. In this paper, four fiber Bragg grating(FBG) sensors are used to establish the sensor array to locate the acoustic emission source. Firstly, the nonlinear locating equations are established based on the principle of acoustic emission, and the solution of these equations is transformed into an optimization problem. Secondly, time difference extraction algorithm based on the phase transform(PHAT) weighted generalized cross correlation provides the necessary conditions for the accurate localization. Finally, the genetic algorithm(GA) is used to solve the optimization model. In this paper, twenty points are tested in the marble plate surface, and the results show that the absolute locating error is within the range of 10 mm, which proves the accuracy of this locating method.展开更多
To achieve the real-time detecting and localization of hypervelocity impact events,a monitoring and localization system was designed based on fiber Bragg grating(FBG)sensor network.First,the simulation model was built...To achieve the real-time detecting and localization of hypervelocity impact events,a monitoring and localization system was designed based on fiber Bragg grating(FBG)sensor network.First,the simulation model was built to study the damage evolution and wave propagation process.Subsequently,based on the response mechanism of FBG to strain,the corresponding high frequency demodulation system was designed.Furthermore,a hypervelocity impact experiment was performed to verify the effectiveness of the designed system.Finally,combined with the diamond sensor array localization algorithm,the accurate position of hypervelocity impact source can be achieved.展开更多
基金supported by National Key Research and Development Project(2020YFE0204900)National Natural Science Foundation of China(Grant Nos.61903224,62073193,61873333)Key Research and Development Plan of Shandong Province(Grant Nos.2019TSLH0301,2021CXGC010204).
文摘As a critical structure of aerospace equipment,aluminum alloy stiffened plate will influence the stability of spacecraft in orbit and the normal operation of the system.In this study,a GWO-ELM algorithm-based impact damage identification method is proposed for aluminum alloy stiffened panels to monitor and evaluate the damage condition of such stiffened panels of spacecraft.Firstly,together with numerical simulation,the experimental simulation to obtain the damage acoustic emission signals of aluminum alloy reinforced panels is performed,to establish the damage data.Subsequently,the amplitude-frequency characteristics of impact damage signals are extracted and put into an extreme learning machine(ELM)model to identify the impact location and damage degree,and the Gray Wolf Optimization(GWO)algorithm is employed to update the weight parameters of the model.Finally,experiments are conducted on the irregular aluminum alloy stiffened plate with the size of 2200 mm×500 mm×10 mm,the identification accuracy of impact position and damage degree is 98.90% and 99.55% in 68 test areas,respectively.Comparative experiments with ELM and backpropagation neural networks(BPNN)demonstrate that the impact damage identification of aluminum alloy stiffened plate based on GWO-ELM algorithm can serve as an effective way to monitor spacecraft structural damage.
基金This work was supported by the National Natural Science Foundation of China(62073193,61903224,61873333)National Key Research and Development Project(2018YFE02013)Key research and development plan of Shandong Province(2019TSLH0301,2019GHZ004).
文摘Fatigue crack prediction is a critical aspect of prognostics and health management research.The particle filter algorithm based on Lamb wave is a potential tool to solve the nonlinear and non-Gaussian problems on fatigue growth,and it is widely used to predict the state of fatigue crack.This paper proposes a method of lamb wavebased early fatigue microcrack prediction with the aid of particle filters.With this method,which the changes in signal characteristics under different fatigue crack lengths are analyzed,and the state-and observation-equations of crack extension are established.Furthermore,an experiment is conducted to verify the feasibility of the proposed method.The Root Mean Square Error(RMSE)of the three different resampling methods are compared.The results show the system resampling method has the highest prediction accuracy.Furthermore,the factors affected by the accuracy of the prediction are discussed.
基金supported by the National Natural Science Foundation of China(Nos.62073193 and 61873333)the Key Research and Development Plan of Shandong Province(Nos.2019TSLH0301 and 2019GHZ004)the Natural Science Foundation of Shandong Province(No.ZR2021MF041)。
文摘In this paper, a plate shape perception technique based on quasi-distributed fiber Bragg grating(FBG) array and space surface reconstruction algorithm is proposed. Firstly, in order to make curvature continuous, the bicubic plane interpolation algorithm is studied. Then, taking the simulated satellite bulkhead structure as the research object, we research the space surface reconstruction algorithm based on orthogonal curvature and coordinate transformation(translation and rotation). Finally, a four-sided fixed plate deformation monitoring system based on quasi-distributed FBG sensors network and surface reconstruction algorithm is built. Many experiments are conducted to verify the reliability and accuracy of the algorithm. The proposed algorithm provides a new method for three-dimensional reconstruction of spacecraft structure.
文摘Ship type identification is an important part of electronic reconnaissance. However, in the existing methods, such as statistical-based methods and fuzzy-mathematics-based methods, the information acquired by the passive sensor is not fully utilized, and there is a certain ambiguity in the assignment relationship of the emitters-ship. They can’t conclude the accurate and reliable assignment relationship of the emitters-ship. Therefore, this paper proposes a comprehensive correlation discriminant method to obtain a more reliable and comprehensive emitters-ship assignment, and then uses information entropy method to identify the type of the target ship on the basis of this association and assign the credibility. The simulation results show that this algorithm can effectively solve the problem of target ship type identification using the information of multi-passive sensors.
文摘<div style="text-align:justify;"> A new planar waveguide laser was demonstrated. The output energy of 400 mW was achieved by a single waveguide laser;the slope efficiency was 61%. The single waveguide laser can expand to waveguide laser group and waveguide laser array to produce higher energy. </div>
基金supported by the National Natural Science Foundation of China(Grant No.41327802)the CAS Key Research Program of Frontier Sciences(Grant No.QYZDB-SSW-DQC015)
文摘A low-energy ion spectrometer(LEIS) for use aboard three-axis stabilized spacecraft has been developed to measure ion energy per charge distribution in three-dimensional space with good energy-, angular-and temporal-resolutions. For the standard top-hat electrostatic analyzer used widely in space plasma detection, three-axis stabilized spacecraft makes it difficult to obtain complete coverage of all possible ion arrival directions. We have designed angular scanning deflectors supplementing to a cylindrically symmetric top-hat electrostatic analyzer to provide a half-space field of view as 360°×90°(–45°–+45°), and fabricated the LEIS flight model for detecting magnetospheric ions in geosynchronous orbit. The performance of this payload has been evaluated in detail by a series of simulation and environmental tests, and the payload has also been calibrated through laboratory experiments using a low-energy ion source. The results show that capabilities of the LEIS payload are in accordance with the requirements of a magnetospheric mission.
基金supported by the grants from Chinese Academy of Sciences(Grant Nos.XDB41000000,QYZDB-SSW-DQC015)the National Natural Science Foundation of China(Grant No.42188101)。
文摘A Chinese geosynchronous satellite was launched on June 23,2020.It carried a plasma detection package to monitor the space environment around the orbit.Here we report the inflight performance of a low energy ion spectrometer(LEIS),one of the primary instruments in the plasma detection package,and its initial observations in flight.Benefiting from the state-of-the-art design of a top-hat electrostatic analyzer cooperated with angular scanning deflectors,three-dimensional measurement of ions in space with a large field of view of 360°×90°and a wide energy range from 50 eV to 25 keV per charge has been achieved.The differential energy flux spectra of ions around the orbit have shown clear signatures of surface charging and storm/substorm ion injections.The occurrence of surface charging could be caused by the lack of photoemission at the Earth's eclipse(near the midnight)or the storm energetic electron injection at the dawn sector.The present results demonstrated a good performance of the LEIS payload in flight for monitoring the space ion environment around the orbit.In situ measurements of the LEIS payload provide us an opportunity to understand the magnetospheric ion dynamics and forecast the associate space weather impacts.
基金the National Natural Science Foundation of China(No.51975367)。
文摘To enhance the measurement precision of eddy current sensor in particular environments such asextreme temperature changes and limited available space in aerospace, we optimized the structural parameters ofthe traditional dual-coil eddy current sensor probe by electromagnetic field analysis and finite element simulationmodeling, and further presented the criteria for determining the optimal coil distance of the dual-coil probe. Thesimulation results are verified by setting up an experimental platform. For the extreme temperature environment,the displacement measurement error caused by the full range temperature variation of the dual-coil sensor underthe optimal distance is less than 21.0% of that of the single-coil sensor. On this basis, we analyzed and verified thethermal stability of the structurally optimized dual-coil eddy current sensor. After temperature compensation,the displacement measurement accuracy can reach 14.9 times more accurate than that of the single-coil sensor.The method proposed in this paper can provide a design reference for the structural optimization of the axialdual-coil eddy current sensor probe.
基金supported by the National Natural Science Foundation of China(Nos.62073193,61903224,61873333 and 61903225)the National Key Research and Development Project(Nos.2018YFE02013 and 2020YFE0204900)+1 种基金the Key Research and Development Plan of Shandong Province(Nos.2019TSLH0301 and 2019GHZ004)the Natural Science Foundation of Shandong Province,China(No.ZR2021MF041)。
文摘A visual reconstruction method was proposed based on fiber Bragg grating(FBG)sensors and an intelligent algorithm,aiming to solve the problems of low accuracy and complex reconstruction process in conventional reconstruction methods of flexible structures.Firstly,the wavelength data containing structural strain information was captured by FBG sensors,together with deformation displacement information.Subsequently,a predicted model was built based on an extreme learning machine(ELM)and further optimized by the particle swarm optimization(PSO)algorithm.Different deformation patterns were tested on an aluminum alloy plate,indicating the ability of the predicted model to produce the deformation displacement for reconstruction.The experimental results show that the maximum error can be as low as 0.050 mm,which verifies that the proposed method is feasible and satisfied with the deformation monitoring of the spacecraft structure.
文摘The laser dazzling effect has always been a crucial issue for the scientific community.Nevertheless,the experiments to study the laser dazzling effect may cost a lot.Therefore,the technology of simulation is promising for this field.Additionally,the effectiveness of the laser dazzling needs to be evaluated by a no reference cost functions.A general model of CCD is proposed in this paper.Additionally,two cost functions are proposed to evaluate the image.The simulation result based on the model shows feasibility of the cost functions.Afterwards an experiment is carried out to testify these cost functions.Different factors include the intensity of the irradiance,the beam radius and the dazzling location of the laser are taken into consideration.The experimental result shows the cost functions have monotonous relationship with the degree of the laser dazzling.This result indicates that the cost functions can be used in the field to measure the degree of the laser dazzling.
文摘In order to address the future power generation needs for scientific exploration of the lunar permanently shadowed regions,this paper proposes a laser wireless power transfer(LWPT)system from a power source at the illuminated rim of the crater to a photovoltaic laser receiver on a rover exploring inside the permanently shadowed region.To fill a gap between the conceptual design and an operational system,the required conditions were analyzed regarding the effects of beam alignment and shaping,wavelength-dependent conversion efficiency on the system level efficiency,and a ground-based prototype system was established.Electric–electric efficiency of 11.55%was measured at a ground transmission distance of 10 m.The study is complemented by discussing optimization analysis for subsequent research,can be more effective and employed in the future.
基金supported by the National Natural Science Foundation of China(Grant No.41431071)
文摘The seismic activities on the Earth can produce a disturbance of the electromagnetic field and particles in the ionosphere. The search coil magnetometer(SCM) mounted on China Seismo-Electromagnetic satellite(CSES) is designed to measure the magnetic field fluctuation of low frequency electromagnetic waves in the frequency range of 10 Hz–20 k Hz. The SCM comprises a three-axis search coil sensor mounted on a 4.5 m boom and an electronic box inside satellite module. The sampling rate of the SCM is 51.2 k Hz and the time resolution of the power spectrum density(PSD) is 2 s. The frequency resolution is 12.5 Hz.There are three operation modes: survey, detailed survey and calibration. In the survey mode, the SCM can provide a PSD in the whole frequency range of 10 Hz–20 k Hz and wave forms in the low frequency range below 2 k Hz while in the detailed survey mode the SCM can provide both PSD and wave forms in the whole frequency range of 10 Hz–20 k Hz. The sensitivity of the SCM instrument is 5.0×10^(-4) n T Hz^(-1/2) at 10 Hz, 5.0×10^(–5) n T Hz^(-1/2) at 200 Hz, 3.4×10^(-5) n T Hz^(-1/2) at 2 k Hz and 1.1×10^(-4) n T Hz^(-1/2) at 20 k Hz. The telemetry rate is ~0.85 Mbps in the survey mode and ~3.0 Mbps in the detailed survey mode. The phase difference between three axes can be made generally with a precision of less than 1.0°. The dynamic range of the SCM instrument is over 100 d B. The orthogonality of three mechanical axes of search coil senor is better than 0.13°. The performance of SCM can satisfy the requirement of scientific objectives of CSES mission.
基金supported by the National Natural Science Foundation of China(No.41472260)the Fundamental Research Funds of Shandong University(No.2016JC012)the Young Scholars Program of Shandong University(No.2016WLJH30)
文摘Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipment. In this paper, four fiber Bragg grating(FBG) sensors are used to establish the sensor array to locate the acoustic emission source. Firstly, the nonlinear locating equations are established based on the principle of acoustic emission, and the solution of these equations is transformed into an optimization problem. Secondly, time difference extraction algorithm based on the phase transform(PHAT) weighted generalized cross correlation provides the necessary conditions for the accurate localization. Finally, the genetic algorithm(GA) is used to solve the optimization model. In this paper, twenty points are tested in the marble plate surface, and the results show that the absolute locating error is within the range of 10 mm, which proves the accuracy of this locating method.
基金supported by the National Natural Science Foundation of China(No.61873333)the National Key Research and Development Project(No.2018YFE02013)。
文摘To achieve the real-time detecting and localization of hypervelocity impact events,a monitoring and localization system was designed based on fiber Bragg grating(FBG)sensor network.First,the simulation model was built to study the damage evolution and wave propagation process.Subsequently,based on the response mechanism of FBG to strain,the corresponding high frequency demodulation system was designed.Furthermore,a hypervelocity impact experiment was performed to verify the effectiveness of the designed system.Finally,combined with the diamond sensor array localization algorithm,the accurate position of hypervelocity impact source can be achieved.
