The existing safety monitoring approaches for bollard structures is primarily to compare the mooring force measured with the allowable mooring force, which cannot completely meet the requirements of safety monitoring of bollards. Hence a new monitoring approach based on the mechanical characteristics of bollards is proposed and a monitoring interface is developed to display the safety status of the bollards in this paper. Firstly, according to analyzing the mechanical characteristics of bollard structure,the most unfavorable mooring condition that makes bollard the maximum stress under same mooring force is found out. Secondly, a safety evaluation approach of bollards structure is put forward, which regards the maximum strain calculated by finite element method as the safety threshold and classifies the safety levels according to it. Finally, the safety monitoring interface is developed by using Matlab GUI, which can display the safety status information of the bollards in real time. Carrying out the field experiments in Zhenhai harbor, FBG sensors are installed at the specified measuring points of the bottom of the 550KN cast iron bollard, and that measured strains are compared with the safety threshold so as to judge the bollard safety status, and its safety status is displayed in the GUI interface. The system takes strain value as evaluation index, establishes the communication between the FBG demodulation equipment and Matlab by UDP protocol, and displays it in the Matlab GUI interface, which has good accuracy and maneuverability and has positive significance in ensuring the safety of ships, mooring bollards and dock workers.
This paper designs a Carbon Fiber Reinforced Plastic Carbon Fiber Reinforced Plastic (CFRP) drive shaft with pre-buried Fiber Bragg Grating (FBG) sensors. The CFRP driveshaft shaft tube is made of full carbon fiber composite material, taking into account of the FBG sensor endface lead-out method and the influence of torsion and fatigue tester fixture size. Taking into account the FBG sensor end lead and the influence of torsional fatigue testing machine fixture size, the metal head of the drive shaft is optimized. At the same time, combined with the characteristics of the composite molding process, the lay-up design and torsional performance research were carried out. In order to obtain the interlayer strain information of the CFRP drive shaft in service due to the torsional load, 15 FBG sensors were pre-embedded in the fabrication process according to the design structure and layup scheme, and the layout of the FBG sensors was determined. The pre-embedded method of FBG sensors and the protection method of fiber optic lead-out are studied, and the pre-embedded 15 FBG sensors have good signals and a survival rate of 100%.
The magnetic field is a physical medium used to realize the levitation and motion control of magnetic bearings. It is necessary to conduct the air-gap flux density measurement so as to validate theoretical analyses and provide instructions for practical design. A thin-slice fiber Bragg grating-giant magnetostrictive material (FBG-GMM) sensor, in which the FBG was stuck perpendicular to the principal magnetostriction orientation of a thin GMM slice, was proposed to measure magnetic-flux density in the small air gap. The configuration of FBG-GMM sensor was the same with that of a sensor of 1.5 mm×14 mm×7 mm TbDyFe slice stuck with a 1300 nm-wavelength FBG on the side of the slice. The FBG-GMM magnetic field sensor was tested on an U-shape electromagnet test setup under static conditions. The sensor had a linear region of 0.121 to 0.261 T with the sensitivity of 1089.056 pm/T. The FBG-GMM magnetic field sensor was introduced to measure the air-gap flux density of radial magnetic bearings. Measurement of static flux density was conducted with 2 FBG-GMM sensors compensated with a temperature FBG; and the measured data showed that the FBG-GMM sensor had feasible linear region and sensitivity to measure the air-gap flux density of magnetic bearings.
Nowadays, there are many kinds of magnetic field sensors such as Hall sensor, Gauss meter and so on. But few of them can be used in the small air gaps which size is about millimeter. A thin-slice Giant Magnetostrictive Material-fiber Bragg grating (GMM–FBG) magnetic field sensor was proposed with the size of 14mm×7mm×1.5mm. The FBG was bonded along the GMM slice length orientation, perpendicular to the major magnetostriction orientation, to measure the GMM’s strain caused by external magnetic field. Experiment systems were established to test the GMM–FBG sensor’s static and dynamic properties. The results show that the sensor’s static property is consistent with the theoretical prediction, and the dynamic response is feasible in low frequencies from 1Hz to 20Hz.
Magnetic bearings are typical electromechanical systems of high performance. Current-displacement-force relationship between stator and rotor is an important research topic of magnetic bearings. The critical issue is to realize magnetic force online dynamic measurement. This paper presents a novel method on magnetic force measurement of magnetic bearings with optical fibre bragg gratings (FBG), which realizes a non-contact and online force measurement with simple configuration, good noise immunity even when the rotor is running. A novel micro force transducer is designed and fabricated, which is mounted within the stator magnetic pole. To obtain current-displacement-force relationship a FBG based magnetic force measurement test rig is setup to simulate magnetic bearing working states as the stator coils currents, air gap between stator and rotor, rotor speed is adjustable. Magnetic force is measured under three classifications of test conditions and test results are presented. The measurement data show good consistency with the theory analysis and calculation, which means that the FBG based magnetic force measurement is available and of good accuracy.
Magnetic Bearings are typical devices in which electric energy and mechanical energy convert mutually. Magnetic Field indicates the relationship between 2 of the most important parameters in a magnetic bearing - current and force. This paper presents calculation and measurement of the magnetic field distribution of a self-designed magnetic bearing. Firstly, the static Maxwell's equations of the magnetic bearing are presented and a Finite Element Analysis (FEA) is found to solve the equations and get post-process results by means of ANSYS software. Secondly, to confirm the calculation results a Lakeshore460 3-channel Gaussmeter is used to measure the magnetic flux density of the magnetic bearing in X, Y, Z directions accurately. According to the measurement data the author constructs a 3D magnetic field distribution digital model by means of MATLAB software. Thirdly, the calculation results and the measurement data are compared and analyzed; the comparing result indicates that the calculation results are consistent with the measurement data in allowable dimension variation, which means that the FEA calculation method of the magnetic bearing has high precision. Finally, it is concluded that the magnetic field calculation and measurement can accurately reflect the real magnetic distribution in the magnetic bearing and the result can guide the design and analysis of the magnetic bearing effectively.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.