Research on sensitized Fiber Bragg Grating temperature sensor based on bimetal three-substrates.

Temperature is one of the most important physical quantities in the field of earthquake precursor observation. Aiming at the problem of low sensitivity in the Fiber Bragg Grating (FBG) temperature sensor, the sensitized FBG temperature sensor based on bimetal three-substrates is proposed. Through theoretical analysis of the bimetallic model, the structural parameters of the sensor are optimized, and the sensor is simulated and analyzed with ANSYS.

Cross spring leaf-based high-sensitivity low-frequency dual-FBG acceleration sensor.

The measurement of low-frequency vibration signals is of great significance in seismic monitoring, health monitoring of large and medium-sized engineering structures, and resource exploration. In view of the low sensitivity of fiber Bragg grating (FBG) acceleration sensors in measuring low-frequency vibration signals, a high-sensitivity, low-frequency dual-FBG acceleration sensor is proposed. Theoretical formula derivation and ANSYS software were used to optimize the design and simulation analysis of the structural parameters of the sensor.

A new L-shaped rigid beam FBG acceleration sensor.

Acceleration detection is an important technology in the fields of seismic monitoring, structural health monitoring and resource exploration. A FBG acceleration sensor with the combination of L-shaped rigid beam and spring structure based on bearings is proposed against the low sensitivity that predominates in the low-frequency vibration measurement by FBG acceleration sensors, where L-shaped rigid beam is utilized to amplify the vibration signal, and is fixed by the bearings at both ends to effectively suppress the transverse crosstalk. The effects of structural parameters on the sensitivity and natural frequency of the sensors were analyzed using Origin theory, and such parameters were optimized; next, static stress and modal simulation analysis was made using COMSOL; in the end, a test system was built to test the performance of the real sensors.

Hinge-type FBG acceleration sensor based on double elastic plate.

It is critical for the health monitoring of large-scale structures such as bridge, railway and tunnel to acquire the medium-frequency and high-frequency vibration signals. To solve the problems of low sensitivity and poor transverse anti-interference of the medium-frequency and high-frequency fiber acceleration sensor, a hinge-type Fiber Bragg Grating(FBG) acceleration sensor based on double elastic plate has been proposed, and the hinge and elastic plate are used as elastomer to realize the miniaturization and transverse interference suppression of the sensor. The MATLAB and the ANSYS are used for theoretical analysis and optimization of sensor sensitivity and resonance frequency, structural static stress analysis and modal simulation analysis, while the test system is built to test the sensor performance.

A multi-cantilever beam low-frequency FBG acceleration sensor.

The acquisition of 2-50 Hz low-frequency vibration signals is of great significance for the monitoring researches on engineering seismology, bridges & dams, oil & gas exploration, etc. A multi-cantilever beam low-frequency FBG acceleration sensor is proposed against the low sensitivity that predominates in the low-frequency vibration measurement by FBG acceleration sensors. Structural parameters of the sensor is subjected to simulation analysis and optimization design using the ANSYS software; the real sensor is developed based on the simulation results in the following manner: Three rectangular of the cantilever beams are evenly arranged around the mass block at 120°to improve the sensitivity and alleviate the transverse crosstalk of sensor; in the end, a performance test is performed on the sensor.

Structural analysis and optimization design of mechanical pendulum of differential capacitance seismometer.

Seismometers can collect and record earthquake information in real time, and they play an important role in earthquake prediction and post-earthquake monitoring. Aiming at the high natural frequency problem of the mechanical pendulum of differential capacitance seismometers, this study employed the ANSYS simulation software to establish a finite element model of the mechanical pendulum; using the constructed model, this study performed static and modal analysis on the key structure, the cross reed, and conducted topological optimization on the shape of the reed. Moreover, the sine calibration method was adopted to measure the natural frequency of the mechanical pendulum before and after optimization, and the experimental results showed that after optimization, the natural frequency of the mechanical pendulum had been reduced by 22%, decreasing from 5.

Estimation of stress distribution in ferromagnetic tensile specimens using low cost eddy current stress measurement system and BP neural network.

Estimation of the stress distribution in ferromagnetic components is very important for evaluating the working status of mechanical equipment and implementing preventive maintenance. Eddy current testing technology is a promising method in this field because of its advantages of safety, no need of coupling agent, etc. In order to reduce the cost of eddy current stress measurement system, and obtain the stress distribution in ferromagnetic materials without scanning, a low cost eddy current stress measurement system based on Archimedes spiral planar coil was established, and a method based on BP neural network to obtain the stress distribution using the stress of several discrete test points was proposed.