International Journal of Applied Electromagnetics and Mechanics - Volume 45, issue 1-4

Authors: Garcia-Rodriguez, Daniel | Mihalache, Ovidiu | Ueda, Masashi

Article Type: Research Article

Abstract: This work presents the development of a new approach to EMAT finite element method (FEM) simulations by using a novel coupled electromagnetic-mechanical equation system. Validation is performed within the limits of the un-coupled equations using commercially available FEM codes. The advantages and drawbacks of the new method versus the traditional un-coupled approach are evaluated for various EMAT patterns. Numerical FEM analyses use a sparse direct solver with either Euler or Crank-Nicolson implicit time …integration methods. Show more

Keywords: Electromagnetic acoustic transducer, EMAT, eddy currents, coupled, uncoupled, time transient, FEM

DOI: 10.3233/JAE-141875

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 543-549, 2014

Authors: Jing, Zijian | Xu, Minglong | Feng, Bo

Article Type: Research Article

Abstract: A measuring system is presented to improve the volumetric strain measurement in hydrostatic pressure environment for a hydro-compression loading test. The measuring system consists of a new triaxial extensometer, a novel contactless signal transmission system and an IPT (inductive power transfer) equipment. By the extensometer, triaxial deformations of foam specimen can be measured directly, from which the volumetric strain is determined. Sensitivities of the triaxial extensometer are predicted using a simplified analytical …model, and verified through experimental calibrations. To avoid the punching and lead sealing techniques on the pressure chamber for hydro-compression loading and transfer the strain data of the triaxial extensometer effectively, a new modus of contactless differential signaling is developed in this paper for elimination of noise caused by the IPT. Show more

Keywords: Measuring system, triaxial extensometer, volumetric stain, contactless signal transmission

DOI: 10.3233/JAE-141876

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 551-558, 2014

Authors: Furutani, Katsushi | Sakata, Atsushi

Article Type: Research Article

Abstract: This paper deals with tweezers for a mass detection during micromanipulation. It measures 52 mm × 30 mm × 10 mm and weighs 37 g. Each finger consists of a bimorph piezoelectric actuator with a stainless steel tip. One of the tweezers working as a vibrator was oscillated at its resonance frequency, and another working as a grasper opened and closed the gap between the tips of the bimorph piezoelectric actuators. The simulation model that represents …the contact of two beams and a lumped mass as springs was described. The resonance frequency was increased when the tweezers grasped an object. The relationship between the mass of the object and frequency was obtained experimentally. Because the charge generated by the piezoelectric effect also affected the resonance frequency, the frequency change in the experiments was smaller than that in the simulation. Show more

Keywords: Piezoelectric actuator, mass evaluation, vibration, resonance frequency, cantilever

DOI: 10.3233/JAE-141877

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 559-564, 2014

Authors: Uppalapati, Kiran | Bird, Jonathan Z.

Article Type: Research Article

Abstract: In this paper the mechanical deflection of steel bars, of different length, in a flux focusing magnetic gear is studied. The mechanical deflection is caused by the magnetic attraction between the steel bars and the inner and outer rotor magnets of the magnetic gear. An iterative magnetomechanical approach using commercial finite element analysis software has been adopted. Two different diameter magnetic gear models with different axial lengths have been modeled and the deflection has been calculated …for each model. Experimental verification for one model is also shown. The paper shows that when operating with a small air-gap and long axial length the mechanical deflection can become significant. Show more

Keywords: Magnetic forces, displacement, magnetic flux density, magnetic gear

DOI: 10.3233/JAE-141878

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 565-571, 2014

Authors: Tanaka, Yoshikazu | Oko, Takuya | Mutsuda, Hidemi | Popov, Atanas A. | Patel, Rupesh | McWilliam, Stewart

Article Type: Research Article

Abstract: In this paper, forced vibration experiments on flexible piezoelectric devices operating in both air and water environments are discussed. Validation of the theoretical analysis method for such devices, via experimental means, is needed in order to achieve future cost effective design optimisations. In aim of this, numerous devices of differing dimensions are manufactured and tested, in various operating conditions, with comparison and discussion to simulation results provided.

Keywords: Piezoelectric film, flexible piezoelectric device, renewable energy, theoretical analysis method, forced vibration, water

DOI: 10.3233/JAE-141879

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 573-580, 2014

Authors: Xu, Fei | Hu, Jianhui | Zou, Jibin | Li, Yong | Xu, Yongxiang | Fan, Hua

Article Type: Research Article

Abstract: The paper describes the alternative designs and performances of a single-phase moving-magnet linear oscillating actuator (LOA) which has been developed for orbital friction welding. The influences of the pole ratio on the performance of the LOAs are investigated and the optimal parameters have been identified with reference to the thrust force characteristics. It can be illustrated that a quasi-Halbach magnetized LOA, in which the magnets are assembled on a nonmagnetic mover yoke, represents the best electromagnetic …performances. Finally, the predicted thrust force-current characteristic of quasi-Halbach magnetized LOA is validated by measurements on a prototype actuator. Show more

Keywords: Orbital friction vibration welding, linear oscillatory actuator, thrust force, optimal design

DOI: 10.3233/JAE-141880

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 581-588, 2014

Authors: Moura, Emanuelle P. | Albert, Bruno B. | Fontgalland, Glauco

Article Type: Research Article

Abstract: This paper proposes to use a statistical approach for classifying the contamination level of insulators used in high voltage transmission lines. This studied case considers the voltage applied on glass insulators used in a chain of six elements of a 69 kV power line. When submitted to high voltage, the insulators radiate radio frequency signals up to frequencies of some GHz. In this frequency range the signal can be detected using portable antennas, and then be …applied to post processing. These received spectra are analyzed by statistical methods, mean and standard deviation, and the cross relation between them is used to classify the pollution level in insulators. To reduce complexity and cost a simple data processing using the mean and the standard deviation are used. Two types of glass insulators are considered: clean or polluted, and to cover the entire frequency range from 30 MHz to 1 GHz two types of antennas were needed. The results obtained with the mean and the standard deviation show that the first 100 MHz bandwidth can be used for statistical of the insulator pollution level. Show more

Keywords: High voltage transmission lines insulators, radio frequency spectrum, statistical classification methods, mean value, standard deviation

DOI: 10.3233/JAE-141881

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 589-595, 2014

Authors: Choi, Dawoon | Jung, Whansung | Cho, Yunhyun

Article Type: Research Article

Abstract: The axial flux permanent magnet (AFPM) machine is widely used in many applications due to its advantages. But the conventional AFPM machine has the major problem such as the deformation and unbalanced air gap occurred because of the large magnetic attraction force between the rotor and the stator. For these problems, the magnetic attraction force must be accuractly calculated in the process of the design step of the mechanical parts. Thus, this paper proposes the analysis …method to compute the magnetic attraction force of AFPM machine considering a unbalanced rotor structure. The quasi 3D model with a different air gap condition is introduced to analyze the magnetic flux density and the magnetic attraction force due to the eccentricity of rotor structure. To validate the proposed analysis process with the quasi 3D model, 3D FEM analysis is performed to compare the results. As results, the proposed analysis results was obtained the similar results to 3D FEM analysis results. The proposed method is applied and estimated to the 130 kW AFPM generator. Show more

Keywords: Axial flux permanent magnet machine (AFPM), magnetic attraction force, 3D quasi model, FEM analysis

DOI: 10.3233/JAE-141882

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 597-604, 2014

Authors: Ahn, Hyun-Mo | Kim, Joong-Kyoung | Ha, Jung-Woo | Kwak, Ki-Yeol | Oh, Yeon-Ho | Hahn, Sung-Chin

Article Type: Research Article

Abstract: In general, a lot of computing time is needed to analyze the transient characteristics of a power transformer with complex geometry by field-circuit coupling method. This paper proposed a modified 2-D model and an efficient field-circuit coupling technique of a power transformer in order to reduce the computing time. To analyze the transient electromagnetic force acting on each disk of transformer windings, we made 2-D axisymmetric model. First, the transient current equation considering the residual flux …was solved to get the inrush current. Next, the transient electromagnetic force due to the inrush current is obtained by applying finite element method (F.E.M.) to the modified 2-D model. The proposed method will be useful for the structure design of the power transformers. Show more

Keywords: Finite element analysis, inrush current, resultant force, transient electromagnetic force

DOI: 10.3233/JAE-141883

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 605-612, 2014

Authors: Lopato, Przemyslaw | Chady, Tomasz

Article Type: Research Article

Abstract: The aim of this study was to investigate the possibility of using electromagnetic radiation in the terahertz frequency range for testing of polymer composites. Glass, natural and basalt fiber reinforced polyester composites as well as sandwich structures after fatigue tests were evaluated. We examined detection abilities of detects and inhomogeneities occurred during bending process at various amounts of load cycles. Extraction and monitoring of proposed parameter enables accurate evaluation of composite structures …condition. Show more

Keywords: Nondestructive testing, terahertz method, composite materials

DOI: 10.3233/JAE-141884

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 613-619, 2014