scholarly journals Study on the Main Factors of Frequency Variation of LC Resonant Prestress Detection Method

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Benniu Zhang ◽  
Yuanyuan Zhao ◽  
Xingxing Li ◽  
Yanpeng Su ◽  
Qiang Yin ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Resonance Frequency ◽  
Relative Permeability ◽  
Stress Measurement ◽  
Length Change ◽  
Resonant Circuit ◽  
Frequency Variation ◽  
Stress Detection ◽  
Electric Circuits ◽  
Stress Changes

Stress loss of prestressed steel strands of existing bridges influences their bearing capacity, so it is of great significance to realize the stress detection. A steel strand that has an inductive property is designed into the resonant circuit, which can realize the stress measurement of the steel strands by testing the resonant frequency. This method is a promising approach for the stress detection of the steel strands. Previous research found that structural stress made the permeability of steel strands change due to the influence of magnetoelastic effect. In the process, the length of steel strands is also changed. Therefore, further research needs to be done to verify the main influence parameter affecting the resonant frequency of the circuit. Furthermore, it is very important to know how the stress affects the resonant frequency to realize the detection of the prestressed force of the steel strands. Therefore, in this paper, the relationship between stress and relative permeability and length is analyzed theoretically, and the theory of stress frequency of steel strands is modified and verified by experiments. The stress-frequency experiments of steel strands and aluminum strands with great difference in relative permeability are carried out. Experiments on stress frequencies of 7-Ф15.20 mm steel strands with different lengths are carried out. The influence of length and permeability parameters on resonance frequency is analyzed. The experimental results show that under the same conditions, the resonant frequencies of steel strands and aluminum strands are almost the same on LC electric circuits, and the resonant frequency decreases linearly with the increase of the natural length of the component and increases linearly with the increase of stress. Consequently, compared with the influence of length change on LC electromagnetic resonance frequency, the relative permeability of the stress change component can be ignored. The stress changes the resonant frequency mainly by changing the length of the strands.

scholarly journals LOCAL SEISMIC HAZARD ASSESSMENT OF THE MATARAM CITY, INDONESIA BASED ON SINGLE STATION MICROTREMOR MEASUREMENT

2018 ◽  
Author(s):  
Syamsuddin
Keyword(s):  
Seismic Hazard ◽  
Resonant Frequency ◽  
Resonance Frequency ◽  
Seismic Hazard Assessment ◽  
Spectral Ratio ◽  
Frequency Variation ◽  
Single Station ◽  
Noise Measurements ◽  
Dominant Period ◽  
Microtremor Measurement

Horizontal to vertical spectral ratio technique is used to assess the local seismic hazard through estimation of fundamental resonant frequency in Mataram city, Indonesia. In this study ambient noise measurements are carried out at 332 sites with the minimum duration of noise recording is about ten menit. Results of measurement indicate that the fundamental resonance frequency for Mataram range from 0.311 to 12,534 Hz. The resonance frequency variation showed a heterogeneous lithological conditions of the area. The resonant frequency is low or high are the dominant period in the western city of Mataram, while the resonant frequency high or low dominant periods are in the eastern. This means that the western region is very prone to earthquakes. In addition, there is a good correlation was found between Geology of Mataram city and HVSR results obtained in this research.

scholarly journals Resonant frequency stabilization technique in series-series contactless energy transfer systems

2017 ◽  
Vol 66 (3) ◽  
pp. 547-558 ◽  
Author(s):  
M. Marcinek ◽  
M. Hołub ◽  
S. Kalisiak ◽  
R. Pałka
Keyword(s):  
Energy Transfer ◽  
Phase Shift ◽  
Resonant Frequency ◽  
Resonance Frequency ◽  
Frequency Stabilization ◽  
Resonant Circuit ◽  
Power Circuit ◽  
In Series ◽  
Stabilization Technique ◽  
Zero Phase

AbstractA technique for stabilization of resonant frequency is proposed in this paper. An additional power circuit, a compensator that allows keeping constant resonance frequency was introduced by the authors. In the presented solution the resonant circuit frequency stabilization is achieved by forcing a zero phase shift between the current and the voltage of the main switching module.

Energy Resource for a RFID System Based on Dynamic Features of Reddy-Levinson Beam

2020 ◽  
Author(s):  
Alireza Babaei ◽  
Johné Parker ◽  
Paria Moshaver
Keyword(s):  
Resonant Frequency ◽  
Shear Deformation ◽  
Displacement Field ◽  
Energy Harvester ◽  
Frequency Variation ◽  
Low Input ◽  
Piezoelectric Energy ◽  
Rfid System ◽  
Proposed Model ◽  
Thick Beam

Abstract Understanding the effect of design parameters on resonant frequency variation is a critically important aspect of piezoelectric energy harvester device design. As a first step in more accurately investigating the performance of a fixture designed for targeted RFID tag communication that also utilizes an energy harvesting application, this paper analyzes the variations in resonant frequency of a higher-order beam based on Reddy-Levinson theory (RLBT) under rotation effects. A long-term goal of this research is to implement an effective energy harvester on the RFID system. Part of the experimental RFID test fixture can be modeled as a beam (or beam element); thus, understanding the resonance frequency variations due to shear deformation and rotation effects is an important first step in obtaining information about the efficacy of the fixture in serving as an energy harvester. Investigating the performance of a beam also provides valuable information about the maximum power, frequency bandwidth, and tuning ability of the device that can be expected from an analogous energy harvester. For the first time, the resonant frequency variation of a rotating thick beam is investigated. Specifically, RLBT is used to verify the effects of shear deformation upon resonant frequency, and a coupled displacement field is utilized to enable tuning the potential piezoelectric energy harvester to low-input excitations by means of constraining translational and rotational movements of the system based on a linear constraint equation. Navier’s method as an analytical-numerical method is adopted to discretize the continuous system and to find resonant frequencies, respectively. Results reveal the significance of beam thickness and rotation effects of the proposed model for the purpose of minimizing energy usage. Current results are compared and verified numerically with available benchmarks to confirm a satisfactory level of accuracy. The proposed model, which is based on a coupled displacement field, can also be used to design other piezoelectric electro-mechanical-systems; e.g., vibration isolators, and vibration controllers. In other words, in an energy-scavenging system, a fundamental understanding of parameters affecting the resonant frequency can be accomplished through the presented analysis. The proposed model highlights the fact that, by adopting a proper speed factor, tuning the piezoelectric energy harvester to low-input excitations is possible. Additionally, it is observed that the rotation effect on the resonant frequency is more severe than effects of slenderness ratio. Finally, in this paper an improved model is proposed to capture the shear deformation effect, particularly for thick-beam energy harvesters, with the capability of tuning to low-input excitations.

scholarly journals A Stress Measurement Method for Steel Strands Based on LC Oscillation

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Dongjun Chen ◽  
Benniu Zhang ◽  
Xingxing Li ◽  
Chong Tu ◽  
Can Yuan ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Oscillation Frequency ◽  
Stress Measurement ◽  
Resonant Circuit ◽  
Electromagnetic Signal ◽  
Prestress Loss ◽  
Factors Affecting ◽  
Existing Structures ◽  
Detection Circuit ◽  
Frequency Meter

The prestress loss is one of the main factors affecting the safety of prestressed concrete structure. While the detecting signals like sound and light are difficult to spread in steel strands, there is no effective method for prestress detection of the bonded prestressed steel strands in existing structures yet. In this paper, taking into consideration that the electromagnetic oscillation characteristic can make the signal propagate effectively on the bonded prestressed steel strands, a nondestructive prestress detection method based on the electromagnetic effect to detect oscillation frequency is proposed. In a detection circuit, the steel strands are simulated as an inductance component, in which an induced electromagnetic signal passes through the steel strands to form resonance. And then, a frequency meter is used to detect the oscillation frequency of the resonant circuit. The oscillation frequency is supposed to have relationship with the prestress loading on the steel strands. A section of steel strands with a length of 1.2 m is adopted to test the correlation of stress and oscillation frequency. Both the theoretical and experimental results show that the resonant frequency of the circuit decreases with the increase of the stress of the strand and is linear in a certain range.

scholarly journals Design Optimization of MEMS Based LLC Tunable Resonant Converter for Power Supplies on Chip

2013 ◽  
Vol 705 ◽  
pp. 258-263
Author(s):  
Fahimullah Khan ◽  
Yong Zhu ◽  
Jun Wei Lu ◽  
Dzung Dao
Keyword(s):  
Resonant Frequency ◽  
Resonance Frequency ◽  
Parallel Plate ◽  
Power Supplies ◽  
Resonant Converter ◽  
Load Variations ◽  
Leakage Inductance ◽  
Variable Capacitor ◽  
Numerical Software ◽  
On Chip

In this paper, a novel MEMS based LLC converter is proposed for on chip power supplies. The design is optimized based on commercially available Metal MUMPs process for fabrication. The resonant frequency is optimized at 20MHz and MEMS based variable capacitor is fabricated on the chip to tune the peak resonance frequency of circuit which varies due to the load variations. The Design is simulated in FEM based numerical software COMSOL and Intellisuite. According to analysis the magnetizing inductance of 42nH and leakage inductance of 40nH has been achieved from 16 mm2 rectangular coil transformer. The total capacitance of 1500pF has been achieved from parallel plate capacitors and variation of 3pF has been achieved from variable capacitor.

scholarly journals A Fiber Bragg Grating Borehole Deformation Sensor for Stress Measurement in Coal Mine Rock

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3267 ◽  
Author(s):  
Wusheng Zhao ◽  
Kun Zhong ◽  
Weizhong Chen
Keyword(s):  
Optical Fiber ◽  
Coal Mine ◽  
Stress Measurement ◽  
Mechanical Load ◽  
Field Tests ◽  
Test Accuracy ◽  
Stress Monitoring ◽  
Stress Changes ◽  
Term Performance

A borehole deformation sensor for long-term stress monitoring in coal mine rock based on optical fiber Bragg gratings (FBGs) is presented. The sensor converts borehole deformation into optical fiber strain by using four rings. For each ring, two FBGs are bonded with the ring to measure the borehole deformation, and a reference FBG free from mechanical load is introduced to remove the temperature effect. Two simple checks on the test data can be performed to improve the test accuracy. Laboratory and field tests were conducted to validate the accuracy and long-term performance of the sensor. The results show that the sensor is capable of measuring stress in rock with good accuracy, and it performs well over a long period of time in coal mines. The developed sensor provides an approach for the long-term monitoring of stress changes in coal mine rock.

scholarly journals Modeling of self-excited stress measurement system

2020 ◽  
pp. 146134842092945
Author(s):  
Ireneusz Dominik ◽  
Krzysztof Lalik ◽  
Stanisław Flaga
Keyword(s):  
Stress Measurement ◽  
Numerical Models ◽  
Piezoelectric Transducers ◽  
The Self ◽  
Model Parameters ◽  
Change Measurement ◽  
Stress Changes ◽  
Emitter System ◽  
New Type ◽  
Proper Power

In the paper two types of numerical models of the self-excited acoustical system are presented. This new type of auto-oscillating system is used for stress change measurement in constructions and rock masses. The essence of the self-excited acoustical system is to use a vibration emitter and vibration receiver placed at a distance, which are coupled with a proper power amplifier, and which are operating in a closed loop with a positive feedback. This causes the excitation of the system. The change of the velocity of wave propagation, which is associated with the change of the resonance frequency in the system is caused by the deformation of the examined material. Stress changes manifest themselves in small but detectable variations of frequency. The first of the presented models was created on the basis of estimating the model parameters by identification of the sensor–conditioner–amplifier–emitter system. The second mathematical model was delivered from the force–charge equation of the piezoelectric transducers: the sensor and the emitter. The model of the loaded beam, which determined the response of any beam point to the force applied to any other beam point is also presented.

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