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The purpose of this paper is to clarify the effects of shot peening (SP) on the torsional fatigue limit of high‐strength steel specimens containing an artificial small defect.

Specimens containing a drilled hole 0.1‐0.4 mm deep or a semi‐circular slit 0.15 or 0.3 mm deep were subjected to SP. Torsional fatigue tests were then carried out.

The torsional fatigue limits of specimens containing a drilled hole and those with a semi‐circular slit were increased 25‐64 per cent and 156‐186 per cent by SP, respectively. The torsional fatigue limits of the specimens subjected to SP and containing a drilled hole less than 0.1 mm in depth or a semi‐circular slit less than 0.15 mm in depth were almost equal to those of SP specimens without a defect. Based on these results, it can be concluded that a drilled hole less than 0.1 mm in depth and a semi‐circular slit less than 0.15 mm in depth could be rendered harmless by SP.

The proposed method can be applied to mechanical parts subjected to cyclic torsion, such as coil springs, crank shafts and drive shafts.

This is the first paper to investigate the torsional fatigue limits after SP in materials containing a surface defect. In this paper, the effect of SP on the torsional fatigue limit having a surface defect is investigated.

The purpose of this study is to clarify the influence of stress ratio (R) on the effects of shot peening (SP) on the fatigue limit of high-strength steel containing an artificial small defect.

SP was subjected on the specimens with a semi-circular slit with a depth of a=0.1, 0.2 and 0.3 mm. Then, bending fatigue tests were carried out under R=0.4.

The fatigue limits of specimens with a semi-circular slit were improved by SP under R=0.4. The fatigue limits of the SP specimens with a semi-circular slit under a=0.2 mm fractured outside the slit, and they had considerably high fatigue limits equal to specimens without a slit. Therefore, a semi-circular slit with a depth of under a=0.2 mm could be rendered harmless by SP under R=0.4. Compared to the results of R=0, the increasing ratios of fatigue limits under R=0.4 were lower than those under R=0. However, the size of semi-circular slit that could be rendered harmless by SP was same. In addition, it was found that whether the semi-circular slit is rendered harmless or not is decided by the relationship between the stress intensity factor range of semi-circular cracks and the threshold stress intensity factor regardless of stress ratio.

The proposed method can be applied to mechanical parts used in vehicles, aircraft and trains.

This is the first paper to investigate the fatigue limits after SP in materials containing a surface defect under positive stress ratio. In this study, the authors investigated the influence of stress ratio on the effects of SP on the fatigue limit containing a surface defects.

The purpose of this paper is to arrive at an understanding of how Japan allowed herself to become involved in a conflict with such tragic proportions, for both Japan and others, as the Second World War.

In a reconstruction, a series of similarities in widespread, local occurrences within the Japanese authority structure that produced larger‐scale reactions, events that could neither undo nor even attenuate the triggering incidents, are described.

The “triggers” occurred almost entirely at the tactical level, ignited by small groups or individuals ignorant of implications higher in the hierarchy of possible outcomes. Emphasized is the causative factor of formalized insubordination, or gekokujô.

The thrust of the paper is to interpret exactly how Japan's lost war against China and the Western Allies began. There may be lessons in this analysis for institutions and organizations outside the military sphere when contemplating new initiatives, especially major departures.