Sensitivity improvement of a new structure crack meter with angular adjustment

Abstract

In order to enhance the sensitivity improvement of crack meter in ruins rescue site, this paper proposes a novel crack meter with a V-shape structure. The mathematical analysis showed that there is a negative correlation between sensitivity of proposed crack and angle of V-shape structure. The finite element analysis using the ANSYS Workbench illustrates that sensitivity of proposed crack meter has rapid reduce with angle of V-shape structure of 14°–28°. Experimental findings show that the proposed V-shape structure crack meter has a higher sensitivity than the traditional one. With 14° V-shape structure crack meter, the sensitivity was enhanced to 1.16 mV/(mm/V), with an increase of 2.3 times over the traditional crack meter sensitivity of 0.35 mV/(mm/V).

A Temperature-Insensitive FBG Acceleration Sensor with Sinusoid-Shaped Curved Beams

“…According to the theoretical analysis results of Formulas (5) and 6 and when a is greater than 40 mm, the change tends to be stable. To meet the requirements of low-frequency vibration signal measurement for higher sensitivity and smaller resonant frequency, the value of a could be taken as greater than 40 mm to meet the requirements of the overall structural size of the sensor.…”

“…In fields such as the structural health monitoring of large-scale civil engineering projects, and seismic wave detection of oil and gas field exploration, the requirements for automated measurement and high-precision testing are becoming increasingly higher, proposing more stringent standards for the accuracy, reliability, stability, and other indictors of vibration sensors; and the sensors must pass tests on their quality and performance to ensure engineering safety and economic feasibility [1][2][3]. As a result, developing novel low-frequency vibration sensing technologies such as the acceleration sensors is of very important significance [4,5], and the emergence of optical fiber sensing technology has shed a new light on the vibration measurement of acceleration sensors. At present, a variety of new-type FBG acceleration sensors have been developed at home and abroad.…”

“…Changes of sensitivity and resonant frequency with length aIn view of the constraints of the assembly structure and size of the sensor, the width of the beams was adjusted. The length of the beams was set to 45  a mm and the thickness was set to 1  c mm, combining with Formulas(5) and(6), the impact of the width of the S-shaped curved beams on the sensitivity and resonant frequency of the sensor was investigated, and Figure 4 shows the changes of sensitivity S and resonant frequency 0 f with b, it can be seen from the figure, with the increase of width b, the sensitivity S decreases rapidly, and the resonant frequency 0 f increases, when width b was between 1mm and 3mm, the sensitivity and resonant frequency reached the requirements of low frequency vibration measurement. Changes of sensitivity S and resonant frequency 0 f with width b The length of the sensor beams was taken as 45  a mm, and the width 2  b mm, combining with Formulas (5) and (6), the impact of the thickness c of the S-shaped curved beams on the sensitivity and resonant frequency of the sensor was investigated, and Figure 5 shows the changes of sensitivity S and resonant frequency 0 f with c, it can be seen from the figure, with the increase of thickness c, S decreases rapidly, and 0 f increases accordingly, therefore, the beams should be as thin as possible.…”

“…, the length a , width b , thickness c and mass m of the sinusoidal-shaped curved beams are the four key parameters affecting the sensitivity and resonant frequency of the FBG acceleration sensor.For the measurement of low-frequency and weak vibration signals, it is necessary to optimize the design of the sensor to increase its sensitivity as much as possible, and assign a suitable value to the resonant frequency to ensure that the sensor could achieve high-sensitivityindicators within a good frequency response range. By comprehensively considering the performance requirements, manufacturing process, mechanical size, the materials and other factors of the sensor, according to Formulas(5) and(6), under the condition that other parameters were given, the impact of parameters that can be flexibly adjusted in the sensor structure on the sensitivity and resonant frequency of the sensor had been taken into consideration to determine a reasonable optimization scheme. During sensor fabrication, beryllium bronze was chosen as the material of the beams, the Young's modulus 14 the initial length of the grating 5 0  z mm.First of all, since the axial size of the sensor should be as small as possible to facilitate actual installation and use, the width of the sensor beam was set to 2  b mm, and the thickness was 1  c mm, combining with Formulas (5) and(6), the impact of the length of the S-Shaped curved beams on the sensitivity and resonant frequency was examined, andFigure 3shows the changes of sensitivity S and resonant frequency 0 f with a, it can be seen from the figure that, when a increases, S decreases accordingly, and 0 f increases rapidly,…”

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 1 , 2 . In recent years, acceleration sensors, one of the key devices for dynamic acquisition of vibration signals, has been extensively used for the monitoring of large structures and environmental safety 3 , 4 . By contrast, traditional electronic accelerometers have limited applications due to their susceptibility to electromagnetic interference.…”