International Journal of Applied Electromagnetics and Mechanics - Volume 21, issue 3-4

Article Type: Editorial

Abstract: Guest-editorial to INABIO 2004 special issues.

DOI: 10.3233/JAE-2005-677

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 143-143, 2005

Authors: Becker, S. | Brown, P.J. | Dennis, B. | Fröhlich, K. | Kanomata, T. | Matsumoto, M. | Neumann, K.-U. | Ouladdiaf, B. | Rasch, J. | Steinke, N. | Stephens, T. | Unverdi, O. | Ziebeck, K.R.A.

Article Type: Research Article

Abstract: The martensitic phase transition in Ni_2 MnGa related alloys is investigated. The stability of the low temperature phase is assessed by a structural investigation of a cold worked sample. The stability of the low temperature martensitic phase with respect to internal strains is determined. It is argued that the experimental observations are consistent with an electronic mechanism being responsible for causing the martensitic phase transition. Alloying experiments with partial substitution of Ga by either In …or Sn show a stronger dependence of the martensitic phase transition on the number of conduction electrons than on the size of atoms or variations of their distances. These experimental findings are consistent with band structure calculations and changes brought about by atomic disorder. Show more

DOI: 10.3233/JAE-2005-678

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 145-150, 2005

Authors: Kanomata, Takeshi | Nozawa, Takuji | Kikuchi, Daisuke | Nishihara, Hironori | Koyama, Keiichi | Watanabe, Kazuo

Article Type: Research Article

Abstract: Magnetic measurements on Ni_{2-x} Cu_{x} MnGa with 0 ≦ x ≦ 0.8 are made in the temperature range between 4.2 K and 440 K. A phase diagram of Ni_{2-x} Cu_{x} MnGa is determined from the results of the temperature dependence of the initial permeability. The Curie temperature T_{C} increases with the Cu concentration x. The martensitic and reverse martensitic transformation temperatures decrease abruptly with …x. It is deduced that the substitution for Ni by Cu in Ni_{2} MnGa promotes to localize the magnetic moment of Mn atom. Show more

Keywords: Ni_{2-x}Cu_{x}MnGa, ferromagnetic shape memory alloy, phase diagram, magnetic moment, phase transformation

DOI: 10.3233/JAE-2005-679

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 151-157, 2005

Authors: Fröhlich, K. | Dennis, B. | Kanomata, T. | Matsumoto, M. | Neumann, K.-U. | Ziebeck, K.R.A.

Article Type: Research Article

Abstract: The structure of Ni_{2.17} Mn_{0.83} Ga has been investigated as a function of temperature using neutron powder diffraction. Above T = 310 K the compound has the cubic L2_{1} structure, with lattice parameter a = 5.79 Å, and with the excess nickel atoms occupying the vacant manganese sites. Magnetisation and resistivity measurements indicate a Curie temperature of T = 340 K with a further transition at T = …301 K associated with a structural phase transition. The martensitic phase was found to have a tetragonal structure with cell parameters a = b = 3.87 Å and c = 6.47 Å and space group I4/mmm. Although there is negligible change in atomic volume the lattice parameters a and b change by ∼ 5.5% and the c-axis by almost 12%. The large change in cell parameters and the relatively high transition temperature make the compound a promising candidate for applications. Show more

DOI: 10.3233/JAE-2005-680

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 159-162, 2005

Authors: Sakamoto, Tatsuaki | Fukuda, Takashi | Kakeshita, Tomoyuki | Kishio, Kohji

Article Type: Research Article

Abstract: Rearrangement of variants of an Fe-31.2mol%Pd single crystal in the field-cooling process under the magnetic fields applied along [001]_{P} , [011]_{P} and [111]_{P} (P: parent phase) has been investigated by strain measurement and optical microscope observation. The fraction of the variant, which lowers the magnetocrystalline anisotropy energy most, becomes almost 100% by the rearrangement of variants under the magnetic field applied along [001]_{P} , but does …not reach 100% under the magnetic field applied along [011]_{P} . On the other hand, the rearrangement of variants hardly occurs under the magnetic field applied along [111]_{P} . Influence of the field direction on rearrangement of variants described above can be evaluated quantitatively by using the magnetic shear stress τ_{mag} and the shear stress required for rearrangement of variants τ_{req} . Show more

DOI: 10.3233/JAE-2005-681

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 163-169, 2005

Authors: Qiu, Jinhao | Tani, Junji | Orikasa, Kazuyuki | Takahashi, Hirofumi

Article Type: Research Article

Abstract: In this study, a hybrid sintering process, which is a combination of microwave heating and hot-press, was applied to the fabrication of lead-free piezoelectric materials for the purpose of improving their performance, since the hybrid sintering process was found to be able to improve the density and consequently the piezoelectric properties of PZT and PNN-PZT materials in the former study. The lead-free piezoelectric material used in this study is BNT [(Bi_{1/2} Na_{1/2} ) …TiO_3 +0.1wt%MnO_2 ]. The BNT was sintered with the hybrid process, the conventional process, the microwave process and a hot-press process and their piezoelectric properties were investigated and compared. Show more

DOI: 10.3233/JAE-2005-682

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 171-181, 2005

Authors: Yuse, Kaori | Dalmas, Florent | Flandin, Lionel | Cavaillé, Jean-Yves

Article Type: Research Article

Abstract: This paper reports in situ measurements of electrical resistivity during mechanical solicitation of insulator-conductor composite. Electrical and mechanical behaviors will be discussed on 3 examples namely (i) unidirectional carbon fiber reinforced polymers (CFRP), (ii) stick-like whiskers reinforced soft thermoplastics and (iii) carbon nanotubes reinforced soft thermoplastics. Resistivity measurements are described as a useful tool to monitor the damage of these composites. In the case of composite materials consisting in reinforced insulated …matrix by electrically conducting fibers or fillers, resistivity (or conductivity) measurements show classically several features such as strong anisotropy in long fiber composites or the existence of continuous direct current (DC) conducting pathway for short fiber or particulate composites. Moreover, and this is the topic discussed here, in terms of mechanical stress/strain properties, the fibers or fillers conducting network may exhibit resistivity changes due to fiber ruptures, delamination, filler-filler debonding within filler network, etc. Show more

Keywords: non destructive testing, delamination, percolation, electrical conductivity, dielectric measurements, nanocomposites

DOI: 10.3233/JAE-2005-683

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 183-192, 2005

Authors: Guyomar, Daniel | Richard, Claude

Article Type: Research Article

Abstract: The proposed processing is applied on the voltage output, image of the vibrating displacement u(t), of a piezoelement (patch) bonded on a vibrating structure. It is based on a non-linear processing which, in the simplest version, short circuit the voltage output for a very brief time duration when the voltage reaches a maximum or a minimum. Right after the switching, the voltage is relaxed and becomes again an image of u(t) at the patch location. Repeating …the switching for each max and min of the voltage signal results in a transformed voltage waveform that is magnified and time shifted with respect to the non switched waveform. As a matter of fact, it can be shown that the processed voltage can be spilt in two waveforms: one, V_{1} (t), being the exact image of the displacement u(t) while the second, V_{2} (t), is related to the sign function of the vibration speed. Consequently V_{2} (t) appears to act as a mechanical dry friction force which leads to efficient and frequency independent removal of the energy stored in the piezoelement. Taking advantage of this particular energy removal, several topics (vibration damping, wave control, energy harvesting) have been experimentaly addressed. For the vibration damping, the experimental results obtained with the proposed semi-active approach are close to the active performances. Acoustic wave reflection reductions of 17~dB and 34~dB have been respectively obtained for air and water media and the scavenged energy using the switch process at fixed displacement is almost ten times higher than the harvested energy using a standard processing. Show more

DOI: 10.3233/JAE-2005-684

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 193-207, 2005

Authors: Shiraishi, Toshihiko | Nakaya, Noriyuki | Morishita, Shin

Article Type: Research Article

Abstract: Semi-active vibration control has attracted a great deal of attention taking advantage of vibration reduction effect, control stability and effective energy consumption. MR dampers are known as one of semi-active control devices, which consist of controllable fluids in fixed orifice dampers. In this paper, response reduction is numerically and experimentally conducted on a building structural model equipped with an MR damper on the first story. It is difficult to deal with time variation of properties and …nonlinearities of MR dampers and structures. It is another problem that optimal damping may be varied according to frequency and magnitude of components of a wave input to structures. In order to deal with these problems, neural networks are applied to the vibration control system. As a result, it is shown that the displacement of the top story of the structure is highly reduced using the neural network control system. Show more

DOI: 10.3233/JAE-2005-685

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 21, no. 3-4, pp. 209-219, 2005