Papers by Author: Cheng Bao Jiang

Abstract: Giant magnetostrictive materials have a broad potential application in aviation and aerospace field owing to its good properties. The actuators made of the materials show excellent performance which makes them a good choice for precision positioning. This paper presents a micro-displacement positioning system of the giant magnetostrictive actuator (GMA). The structure of the system and its control method are described. In order to achieve the steady micro-positioning characteristics, the adjustment process of the system based on the control algorithm of Programmable Multi-axis Controller (PMAC) was researched. The response time of the GMA was less than 1 ms which was shown in the step response curve. Relatively large displacement (5~20 µm) positioning and micro-displacement (0.9~3 µm) positioning were achieved with the average positioning systematical errors of less than 0.5 µm.

Abstract: The growth velocity has a significant effect on the preferred orientation of the directionally solidified Fe81Ga19 magnetostrictive alloy. Strong <100> preferred orientation was obtained for a velocity range from 10mm/h to 20mm/h. An excellent magnetostriction λ100 of 294×10-6 was achieved for the <100> oriented crystal at a pre-stress of 74.1MPa. Linear and volume magnetostrictions were investigated in the as-cast Fe81Ga19 alloys with A2 phase by measuring the change in length along the three-dimensional directions of the samples. Due to the contribution of the volume magnetostriction, the longitudinal magnetostriction increased from 27 ppm at 0.3 T to 47 ppm at 2.0 T. The volume magnetostriction can be drastically enhanced by doping Ga in Fe.

Abstract: A strong need exists to develop new kinds of high-temperature shape-memory alloys. In this study, two series of CoNiGa alloys with different compositions have been studied to investigate their potentials as high-temperature shape-memory alloys, with regard to their microstructure, crystal structure, and martensitic transformation behavior. Optical observations and X-ray diffractions confirmed that single martensite phase was present for low cobalt samples, and dual phases containing martensite and γ phase were present for high cobalt samples. It was also found that CoNiGa alloys in this study exhibit austenitic transformation temperatures higher than 340°C, showing their great potentials for developing as high-temperature shape-memory alloys.

Abstract: The Tb/Dy ratio of Tb0.30Dy0.70Fe1.95 giant magnetostrictive alloy was shifted away from 0.30/0.70 to 0.36/0.64 to enlarge the operating temperature range. However, the magnetostriction was reduced under low magnetic field and its hysteresis was enlarged with the shift of Tb/Dy ratio. Ho addition improves the magnetostriction under low magnetic field and reduces the hysteresis of TbxDyyHozFe1.95 (x+y+z=1). The crystal structure, lattice constant, Curie temperature, spin reorientation temperature, magnetization, magnetic anisotropy and magnetostriction of TbxDyyHozFe1.95 alloys were investigated. X-ray diffraction patterns demonstrate that all the samples possess MgCu2-type cubic Laves structure. The lattice parameter, Curie temperature and magnetic anisotropy constant K1 decreased with increasing Ho concentration. The hysteresis represented by the width of magnetostriction versus the applied field was reduced due to the addition of Ho. At a compressive stress of 10 MPa and a magnetic field of 1000Oe, the addition of Ho to the ternary TbxDyyFe1.95 compound reduced the width of magnetostriction by 25% for Tb0.296Dy0.472Ho0.232Fe1.95 and by 27% for Tb0.296Dy0.472Ho0.232Fe1.95 compared to the Tb0.36Dy0.64Fe1.95 alloy, while the strains were reduced by only 3% and 9%.

Abstract: Co and Si were selected as substitutes to improve performance of TbDyFe giant magnetostrictive alloys for special purpose, respectively. The results showed that the Co-doped Tb0.36Dy0.64Fe2 alloys can possess giant magnetostriction over a wide temperature range from -80 to 100
. Optimum magnetostriction, high electrical resistivity and improved corrosion resistance was obtained in Tb0.3Dy0.7(Fe1-xSix)1.95 system. High performance grain-aligned rods with <110> preferred orientation have been successfully prepared by zone melting unidirectional solidification. This paper also presents the design and fabrication of Giant Magnetostrictive Actuator (GMA) for active vibration control with oriented TbDyFe rods. Experimental results showed that the GMA possesses good static and dynamic performance. Excellent damping effect, 20-30 dB under the frequency range from 10 Hz to 120 Hz was obtained.

Abstract: Ultrafine-grained (UFG) pure Cu processed by equal channel angular pressing (ECAP) was subjected to cyclic deformation and subsequent ageing treatment at room temperature (RT) in order to investigate the stability of defects and grain size. Cyclic deformation for 1000 cycles at RT leads to a large decrease of internal stress. X-ray diffraction (XRD) shows that the stability of defects and grain size at RT in as-cyclic deformed sample is lower than that in as-processed sample and that a reduction of internal stress takes place prior to grain growth. TEM observations show that the microstructural evolution during ageing is characterized by normal grain growth accompanied with recovery within grain interior.

Abstract: A mechanical properties prediction model for cobalt-free maraging steel was built upon the experimental data by fuzzy identification method. A method of fuzzy identification based on fuzzy clustering and Kalman filtering is proposed. The results showed that good correlations between the predicted result and the experimental data. The technique proposed could be served as a reliable tool for cobalt-free maraging steel mechanical properties control and design.

Abstract: The non-stoichiometric NiMnGa shape memory alloy with high Ni content has been developed as promising thermo-actuated materials applied at high temperature. A substitution of Al for Ga in the Ni54Mn25Ga21 alloys is performed. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements have been carried out to study the effects of the phase transformations and microstructures of the Ni54Mn25Ga21-xAlx shape memory alloys. The results show that the martensitic transformation temperatures almost linearly decrease with the increase of Al substitution for Ga, which can be explained considering the effect of the size factor, i.e. the lattice parameter. A structural transition from a non-modulated tetragonal type to a seven-layered 14M one has been found during the increase of Al substitution for Ga.

Abstract: A six degree-of-freedom (DOF) Stewart platform is constructed, which consists of six TbDyFe alloy magnetostrictive actuators, and applied to active vibration control. To control the smart structure, a real time computer control system is built. An improved adaptive filtering algorithm is proposed in this paper, which is used for the computer control system. The results of experiments show that the smart structure and the proposed algorithm are efficient for active vibration control. More than 30 dB of vibration attenuation is achieved in real-time experiments.

Abstract: In this paper, a new method which combines the least square method with Tree-Structured fuzzy inference system is presented to approximate the Preisach distribution function. Firstly, by devising the input sequence and measure the output, discrete Preisach measure can be identified by the use of the least squares method. Then, the Preisach function can be obtained with Tree-Structured fuzzy inference system without any special smoothing means. So, this new method is not sensitive to noise, and is a universal approximator of the Preisach function. It collect the merit and overcome the deficiency of the existing methods.