The fatigue strength of high-speed tool steel, JIS SKH51, with TiAlN/DLC nano-multilayered coating film was investigated to verify the effectiveness of its coating in improving the fatigue strength of SKH51. Four-point static and fatigue bending tests were conducted to examine the static bending strength and S-N property. The AIP+UBMS hybrid coating system was adopted for deposition of nano-multilayered hard coating film on SKH51. TiAlN coated SKH51 and SKH51 were used as comparative materials. As a result of experimental tests, the average value of bending strength of TiAlN/DLC coated SKH51 was 2912 MPa, which is approximately 17 % less than that of SKH51 substrate. The bending strength of TiAlN coated SKH51 was 3034 MPa, approximately equal to that of the TiAlN/DLC material. Even in the low cycle region, the fatigue strengths of TiAlN/DLC, TiAlN coated SKH51 and SKH51 substrate were the same, and the superiority of TiAlN/DLC nano-multilayered coating was not so much. On the other hand, in the high cycle region, fatigue strength of the TiAlN/DLC material increased in fatigue strength of approximately 150 MPa relative to SKH51 substrate. This tendency was different from TiAlN coated SKH51 in which the improvement of fatigue strength was limited, and the superiority of TiAlN/DLC nano-multilayered coating to ordinary TiAlN coating was confirmed. As a result of fracture surface observation and residual stress measurement of the film, it was found that the superiority of fatigue strength of TiAlN/DLC coated SKH51 in the high cycle region is due to high residual stress in the film and high adhesiveness of the film.

Tapered roller bearing is used for various industrial machines because of high rigidity. However, the tapered roller bearing has a weakness that the running torque is larger than that of a ball bearing. The reason for the bearing have sliding contact area between the large roller end face and large inner flange face. Therefore, the authors attempted to reduce the running torque by attaching a herringbone type periodic micro groove on the large roller end face of the tapered roller bearing. In this paper, the authors changed position and direction of herringbone type micro groove and examined the effect to running torque. Because of the torque test, when the groove was applied to a position overlapping with the run mark portion, the running torque considerably increased. Conversely, it was possible to reduction the running torque most that sliding direction is reverse direction to the sliding direction of normal herringbone and the position where the groove does not overlap the running trace area, the P. C. D. of the groove is 7.9 mm, it was confirmed that we can reduce about 60% of the current product.

High-efficiency continuous processes combining compaction and extrusion for snow disposal using a rectangular cross-section container were investigated for continuous production of large dense cuboid ice blocks from shavings and ice pieces with cube edges of L_ice = 8 mm. During compaction, we investigated the ice density and formation pressure and compared them with circular cross-section cubes. Compaction formation pressure P_comp. obtained using a rectangular cross-section device requires more than 3.50 MPa pressure to produce compacted cuboid ice blocks with ρ = 0.8 g∙cm^-3 density. That value is 280% greater than products of a circular cross-section device. Then large ice solids underwent direct extrusion using rectangular cross-section dies for extrusion ratios of R = 1.12–1.30 with α = 90° die angles. The extrusion ratio is the initial cross-section area / final cross-section area of the extrusion container. During extrusion, some relations among extrusion formation pressure and the punch stroke position for each R were investigated to avoid pressure vessel breakage caused by compaction and extrusion. Results show that the proposed extrusion, having strain rate έ ≈ 10^-1 S^-1, can produce the large cuboid ice blocks. Furthermore, extruded ice blocks of L = 100 mm length, w = 50 mm width, and H = 50–60 mm height were obtained for R = 1.20–1.30.

This paper deals with the vibration damping analysis of cantilevered beams having partially inner layered damping material. Vibration and damping characteristics on bending vibration mode of the beam are evaluated on the basis of minimization scheme of the energy functional. The beam model is constructed in sandwich beam elements, two layers beam elements and the connecting springs for translation and rotation. The elastic moduli of damping material are treated as the complex quantity including the material loss factor. The frequency equation of the beam is obtained by minimizing the energy functional and solved to estimate the natural frequencies, modal loss factors and natural vibration modes. Accuracy and validation of present results are studied in terms of the convergence of solutions and comparisons with the analytical results from reference literature. Calculated results are illustrated for several beam models and various parameters such as division number and occupancy of the damping material. Effective design concepts on damping of beam structures are indicated through numerical results.

The rotor of the permanent magnet synchronous motor (PMSM) consists of one yoke and multiple permanent magnets (PMs) embedded in it, and their design greatly affects performances of the PMSM. It is desirable to concurrently optimize the PM layout and the topology of the yoke structure. However, it is known that the concurrent optimization is difficult, whereas it is relatively easy to solve the respective optimization problems independently. In this paper, we assume ahierarchy for the PMSM optimization problem, and propose to incorporate a topology optimization method for determining the yoke structure and the response surface methodology for determining the PM layout. First, the yoke structure is optimized under several PM layouts using the topology optimization method. Second, on the basis of these results, the response of the PMSM performance is approximated by the response surface methodology, and then the layout of the permanent magnets is optimized. Finally, topology optimization is performed for the yoke structure under the condition of the optimized layout. The effectiveness of the method is shown by a numerical example.

In recent years, nanobubbletechnology has drawn great attention due to their wide applications in many fields of science and technology, such as water treatment, biomedical engineering, and nanomaterials. Nanobubble technology is also used for seafood long term storage. The nitrogen nanobubble water circulation can be used to reduce the oxygen in water and slow the progressions of oxidation and spoilage. In previous study, a kind of honeycomb structure for high efficiency nanobubble generation has been investigated. In addition, thesmall-scale honeycomb structure is designed for the broader applications. Comparing with stainless steel, acrylic resin and titanium have good corrosion resisting property in various liquids including the sea water. Therefore, acrylic resin and titanium are considered in this study. In this paper, the honeycomb structure is optimized and improved. Combining experimental solutions and CFD analyses, the performance of the generator is studied. The strength of the honeycomb structure is also analyzed by FEM. The relationship between nanobubble generation efficiency and structure type is discussed.