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When designing engine parts of motor vehicles, it is important to evaluate internal residual stresses that cause crack growth and influence the strength of parts. Internal stresses can be measured nondestructively by the neutron diffraction method. However, it is difficult to apply this method to aluminum alloy castings because they consist of coarse crystal grains. As for cylinder heads, the grain size ranges up to approximately 400 μm and there are few grains contributing to intensity of diffraction in each gauge volume. In the case of X-ray diffraction, "the oscillation method" has been employed for materials with coarse grains. In this study, the applicability of the oscillation method to aluminum alloy castings was investigated with the aim of establishing a method of measuring internal stresses and strains. A related objective was to determine the accuracy of stresses.

We have developed a new liquid-applied sound deadener material (LASD) that replaces asphalt-type dampening materials to reduce both automotive weight and the workload of factory associates. Compared to a loss factor of 0.30, this LASD is 62% lighter than conventional materials; compared to an area weight of 2.4kg/m2, it displays a 172% higher loss factor. This effect was obtained because the developed liquid-applied sound deadener material uses acrylic resin with a maximum tan δ at 34°C, with the expansion ratio set to 1.8 times. In addition, the viscosity of the liquid-applied sound deadener material was adjusted so the thixotropy would be high at shear speeds of 10 to 3000S-1 to minimize irregularities in the surface when a slit nozzle is used to apply the sound deadener material.

Regarding tapered roller bearings used on pinion shafts in differential gearboxes, it has been observed that some cases of bearing failure, like flaking or seizure, occurred much earlier than expected. As to the cause of this kind of failure, it has been clarified that on the shaft system supported by a pair of tapered roller bearings, the actual bearing load, including the preload of the bearings, fluctuates not only under the dynamic state but also under the static state because of the temperature distribution around the bearings. This fluctuation of the actual bearing load and preload greatly affects rolling fatigue life, seizure performance and the stiffness of the shaft support system. This paper discusses optimal design concepts for improving the rolling fatigue life, frictional torque, rigidity and seizure performance of a pair of tapered roller bearings. The design concepts are based on analysis results of the dynamic preload situation under actual operating conditions.

The peening of fine steel beads with diameters less than 80 micrometers onto the surface of a spring (referred to as SS Treatment in this paper) was found to improve the fatigue limit of the spring effectively since the surface compressive residual stress and surface hardness were improved significantly. As an example, by applying this technology to non–nitrided high–strength valve springs made from the so–called high–strength oil tempered wire, the fatigue limit was increased to the nearly equivalent level as the nitrided and conventionally shot–peened valve springs made from the same high–strength wire. This means that the SS Treatment can be used as a substitute to the nitriding process which has been applied in order to get improved fatigue property of high–strength valve springs.

This paper describes the construction, characteristics and capabilities of a compact automatic tensioner for timing belts that was recently developed by NSK. This auto-tensioner differs from conventional ones having separate actuators. By incorporating the damping mechanism inside the bearing, a compact size nearly equal to that of fixed type tensioners was achieved. The damper is a multi-disc viscous type that uses high viscosity silicone oil.