Bonded magnet NdFeBwas made by mixing aNdFeBpowder (MQP -A) with a liquid epoxy resin (ER). The composition of the sample consisted of 95 wt.%. NdFeB powder and 5 wt.%ER. This mixture is then pressed with pressure about 1.5 ton/cm 2 and it was obtaineda pellet sample with size 40 x 18 x 6 mm. The pellet samples were cured by using drying oven at 80 o C for 2 hours and then the surface for all samples were coated by using silver paint and dried at room temperature for 6 hours. Magnetic properties were characterized by using Permagraph Magnet Physik Germany. The magnetic properties results show that, the 5 wt.% epoxy resin bonded magnet NdFeB has Flux density = 1,500 Gauss, Remanence Br = 5.40 kGauss, Coercivity Hc = 7.86 kOe and Energy product (BH) max = 5.31 MGOe.The purpose of this research is to make bonded magnet NdFeB using 5 % ER and know the extent to which can be applied in making an electric generator (micro). The NdFeB magnets that have been successfully made is used to create a prototype small electric generator (double disk type). The characterization results of small electric generator show that electric generator could produce a dc-current about 0.3A at 400 rpm and voltage 12.60 volt with LED light as load.
Whole deformation processes and slipband propagation of aluminum alloy in tensile experiments are directly observed on whole field in real time(lframe/s) by dynamic speckle interferometry. In plastic deformation, an inclined white band appears. It sweeps the specimen surface repeatedly in a certain speed and band width along the tensile direction. Sometimes the inclined angle of the white band transfers symmetrically. With plastic deformation increasing, the band speed decreases gradually, and the specimen cracks finally at the position where the band stops. Transient process of the white band formation is captured with a high speed CCD camera. It is revealed that the white band is a sharp slip deforming region consisted of concentrated inclined fringes. An interesting phenomenon that the strain value at a point of the specimen surface changes like a stair shape is accounted by the sweeping movement of the slipband. The moving picture encoding technique (MPEG2) is introduced to encode all of the sequential fringe patterns as one MPEG2 file. By watching the moving picture, the analysis of a huge volume of fringe patterns becomes easy, and subtle changes of fringe patterns can be observed clearly.KEY WORDS: slipband propagation, plastic deformation, dynamic speckle interferometry.
1.IntroductionIn metal alloy, localized, heterogeneous strain may happen during large plastic deformation due to metal atom dislocation and the existence of very large crystal grains relative to metal atom. In a tensile experiment of carbon steel, a Luders band appearing in the lower yield point is a typical example of localized and heterogeneous strain [1]. It is known that a complicated slip deformation happens in the Luders band. To observe the Luders band, usually a specimen is polished to a smooth surface to be conducted a tensile experiment. The Luders lines remaining in the surface are observed. In the case of carbon steel, after a Luders band appears in the lower yield point, it propagates to cover the entire length of specimen.However that the Luders band sweeping over the specimen can be observed only one time by polishing method. For the case
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