International Journal of Applied Electromagnetics and Mechanics - Volume 52, issue 1-2

Authors: Van Toan, Tran | Ueno, Satoshi | Fukuura, Takuya | Shinjyo, Takahiro

Article Type: Research Article

Abstract: In this paper, a novel disk type permanent magnetic motor which can actively control five degrees of freedom (5-DOF) of rotor postures without any contact has been proposed. Hence, although it has similar structure with an original Axial-Gap Self-Bearing Motor (ASBM), other radial magnetic bearings and its shaft of the rotor can be removed. Moreover, the number of stator coils is minimized; therefore, the structure and control system of the motor are simplified. This paper illustrates the structure and control principle of the proposed motor, and then the electromagnetic characteristics calculated by three-dimensional magnetic field FEM analyses are shown. An …experimental device whose dimensions was determined based on simulation results was manufactured and tests were carried out to demonstrate the feasibility of the proposed motor. Show more

Keywords: ASBM, 5-DOF active control, magnetic bearing

DOI: 10.3233/JAE-162141

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 243-250, 2016

Authors: Zhang, Yahong | Luo, Yajun | Zhang, Xinong

Article Type: Research Article

Abstract: Nonlinear vibration of a beam is active controlled with a fuzzy logic controller designed. The Von Karman's large deflection equation for a generally elastic beam partially covered by a macro fiber composite actuator (MFC) is established. Galerkin method is employed to convert the nonlinear partial differential equation derived into the nonlinear ordinary differential equation of motion, which is of Duffing's type. The method of multiple scales is adopted to figure out the relationship between the vibration amplitude and the nonlinear frequency. The nonlinear characteristics of the system are discussed when proportional and derivative feedback scheme is used. To depress the …nonlinear vibration, a fuzzy logic controller is designed and the vibration of the beam is suppressed effectively. Show more

Keywords: Nonlinear vibration, fuzzy logic control, MFC actuator, active vibration control

DOI: 10.3233/JAE-162155

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 251-260, 2016

Authors: Wang, Hongyuan | Qiu, Jinhao | Ji, Hongli

Article Type: Research Article

Abstract: The conventional impact localization strategies often assume that the wave velocity is independent of the propagation angle and obtain the wave velocity through theoretical calculation. These compromises may lead to inaccuracies of impact locations. In this paper, a Bayesian probabilistic methodology for impact localization is proposed. This approach utilizes the time of flight of diagnostic Lamb waves obtained by a piezoelectric sensor network for parameter identification. Bayes' theorem is then used to build the probabilistic relationship between measured time of flight data and unknown parameters. Finally, Markov chain Monte Carlo method is presented to implement the identification of probability distributions …of impact location and wave velocity. Experimental studies carried out by dropping a steel ball on a CFRP panel are conducted to validate the proposed Bayesian impact localization strategy. Show more

Keywords: Impact localization, lamb waves, Bayesian inference, Markov chain Monte Carlo method, uncertainties

DOI: 10.3233/JAE-162173

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 261-269, 2016

Authors: Yang, Baisong | Geng, Haipeng | Sun, Yanhua | Yu, Lie

Article Type: Research Article

Abstract: To meet the demands of high speed and excellent stability in modern oil free turbomachinery, a hybrid foil-magnetic bearing (HFMB) was first designed by Heshmat in 2000 [1]. However, in the HFMB, the journal should be carried out in certain eccentricity and attitude angle to the center of the bearing house due to hydrodynamic force which provided by the GFB. While the magnetic force caused by the AMB would try to force the journal of the reference position which is usually the center of the bearing at all times when using a conventional PD controller. While magnetic forces were commonly …linearize at the center position of the bearing with respect to journal displacement and coil current. Therefore, the fully nonlinear force to displacement and the force to current characteristics concerning the journal eccentricity effect should be applied. The main objective of this paper is to represent a kind of theoretical method to calculate the load capacity, dynamic stiffness and damping coefficients of the HFMB under a specified load sharing factor λ with the predetermined operational state. Show more

Keywords: Hybrid foil-magnetic bearing, gas foil bearing, active magnetic bearing

DOI: 10.3233/JAE-162083

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 271-279, 2016

Authors: Xia, Kai | Sun, Yanhua | Zhang, Feng | Guo, Jiafang | Yu, Lie

Article Type: Research Article

Abstract: This paper presented a coupled electromechanical model and numerical method to obtain the torque response in a gas turbine rotor through transient analysis. Firstly, the FE model of the rotor based on beam elements and the electrical model of the generator were established. Then a contact element was introduced in the FE model to consider the contact effect between discs of the gas turbine rotor. The 4th Runge-Kutta method and Newmark method were used to solve the coupled equations iteratively to obtain the numerical solution of the transient response. Finally, a case study was presented and the results show much …differences with those obtained through the conventional uncoupled analysis. The method and results of this paper are important to the rotor dynamic analysis and design of the gas turbine rotor in engineering. Show more

Keywords: gas turbine, short circuit fault, electromechanical coupling, transient response

DOI: 10.3233/JAE-162043

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 281-288, 2016

Authors: Hamanaka, Shunichi | Saito, Yoshifuru | Marinova, Iliana | Ohuch, Manabu | Kojima, Takaharu

Article Type: Research Article

Abstract: Previously, we have proposed an infinity coil as a high sensibility ECT sensor. This paper has evaluated a possibility of the backside defect searching by the low frequency excitation of a modified infinity coil whose exciting coils are the flat/film shape to fit to the curverved test targets. In the present paper, we have elucidated the lift-off characteristics of the backside defect searching when employing the low frequency excitation to our flat/film shape infinity coil.

Keywords: Nondestructive testing, ECT, ∞ coil, backside defect searching

DOI: 10.3233/JAE-162073

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 289-295, 2016

Authors: Cai, Wenlu | Xie, Zheng | Xie, Shejuan | Pei, Cuixiang | Li, Yong | Chen, Zhenmao

Article Type: Research Article

Abstract: In this study, the strategy to simulate a real stress corrosion crack (SCC) with a closed fatigue crack (FC) in view of eddy current testing (ECT) is investigated. An online four-point bending ECT device is designed and fabricated to provide the closure loading for a plate specimen and to enable online ECT measurements. The amplitudes of ECT signals due to FCs closed with different closure loads are measured. The experimental results show that the amplitudes of ECT signals due to closed FCs change regularly with the applied closure loads, and the ECT signal will recover to the initial state once …the closure loading is released. The experimental results also reveal that, instead of the residual plastic strain, the online closure loading can make the FC conductive and a larger load leads to bigger crack conductivity. Through inverse analysis of the measured ECT signals, it is found that the conductivity in the crack region can reach to as big as 45% of the base material conductivity due to a large closure load. The results of this work demonstrated the feasibility positively to simulate a SCC with an online closed FC specimen for ECT measurement. Show more

Keywords: Closed fatigue crack, online bending ECT device, stress corrosion crack, simulated test-piece, ECT

DOI: 10.3233/JAE-162114

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 297-306, 2016

Authors: Xie, Shejuan | Fang, Beipei | Cai, Wenlu | Tian, Mingming | Chen, Hong-En | Chen, Zhenmao

Article Type: Research Article

Abstract: In this study, quantitative evaluation of defects in an outer-square-inner-round (OSIR), aluminum pipe, which is used as the coolant pipe of Tokamak superconducting magnet, is conducted based on the eddy current testing (ECT) technique. First, numerical simulations to predict ECT signal due to defects in OSIR pipes are performed using a code of Ar method; Second, ECT signal is detected using an Eddyfi ECT instrument with an absolute pancake ECT probe; Finally, the defect profile in OSIR pipe is reconstructed from the experimental ECT signals with the help of a fast-forward ECT solver, the developed multiple databases strategy and …the deterministic inversion algorithm. Show more

Keywords: OSIR pipe, ECT, experiment, quantitative evaluation, multiple databases strategy

DOI: 10.3233/JAE-162127

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 307-314, 2016

Authors: Su, Zhiyi | Ye, Chaofeng | Tamburrino, Antonello | Udpa, Lalita | Udpa, Satish

Article Type: Research Article

Abstract: The detection of a crack under fastener heads (CUF) in a multi-layered aircraft structure remains a challenge in non-destructive evaluation (NDE). An EC-GMR system using a linear eddy current (EC) coil with giant magnetoresistive (GMR) sensors located on the axis of symmetry is proposed for detecting discontinuities in conducting materials. The signal received from sensors is greatly influenced by the excitation field. An ideal excitation field is purely tangential and uniform, however this is not achievable with coils of finite dimension. This paper proposed a methodology to optimize the coil design in order to approximate the ideal excitation field to …the best extent. In the proposed approach, the coil design is cast as a multi-objective optimization problem. The algorithm for solving this optimization problem is the NSGA II (non-dominated sorting genetic algorithm II). The original version of this algorithm is not efficient in finding the solution, i.e. an evenly-distributed Pareto front. Therefore a problem specific modification is proposed. Numerical simulations showed the effectiveness of the method. Show more

Keywords: Eddy current testing, excitation coil, optimization, NSGA II

DOI: 10.3233/JAE-162030

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 315-322, 2016

Authors: Li, Weibin | Cho, Younho

Article Type: Research Article

Abstract: Ultrasonic guided wave tomography provides an imaging potential over a hidden and inaccessible damage zone. The use of shear horizontal guided waves has been proposed as an attractive technique for surface defect characterization. In this paper, imaging of wall thinning defects in plate is investigated by using electromagnetic ultrasonic shear horizontal guided wave tomography. Shear horizontal guided waves are generated and measured by magnetostrictive patch transducers. The quantification via imaging of wall thinning defects is achieved by a modified reconstruction algorithm for the probabilistic inspection of damage tomography algorithm. The location and shape of wall thinning defects are successfully obtained …by the electromagnetic ultrasonic wave signals. The present approach provides an alternative alternative, that can be applied for detecting, locating and imaging the wall thinning defects in plate-like structures. Show more

Keywords: Electromagnetic ultrasonics, shear horizontal guided waves, tomographic imaging

DOI: 10.3233/JAE-162033

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 52, no. 1-2, pp. 323-330, 2016