Torsion of bars with uniform cross-sections is studied by many researchers, and the problem is well known as Saint-Venant torsional one. However, a few researchers have investigated as three dimensional problem. In this paper, the author conducted numerical analysis of torsional problem bythe finite element method using software called LUSAS. Numercal examples are shown for typical three kinds of cross-sections. Tortional moment subjected to concentrated loads at the end of the bars is compared with analytical solution. And the validity of Saint-Venant problem is proved.

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Since the soundness and life prediction methods of the material were important subjects in industry, ultrasonic spectroscopic non-destructive evaluation method on fatigue damage was proposed. In this method the velocity of an ultrasonic wave that propagated the material surface was measured, and then movable dislocation loop density was calculated using the measured velocity and also the area of slip bands that appeared in notch surface was measured. Then, as compared with the slip bands area method, validity of this method was examined. Since the results of the ultrasonic spectroscopy method and the slip bands area method were qualitatively agreed, it was clarified that this method was effective to evaluate the life prediction of metal materials.

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[in Japanese]

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Many Pitot-static Tubes were tried to make of Empty Cans, Straws and Paper-Board, those of which are materials that can be easily obtained. The Steel Empty Can is 53mm in diameter and 96mm in length. The Straw is 6mm in diameter and 207mm in length. The Paper-Board is 0.5mm in thickness. The Empty Cans were used to detect static-pressure, and the flexible Straws were used to read both total and static pressure, and the Paper-Board were used by the Flange Shape Fence. The result of the investigation on the characteristics of the hand made Pitot-Static tubes can be summarized as follow : 1) Handmade Pitot-Static tubes using Empty cans, Straws and Paper-Boards have coefficients ranging from 0.75 to 0.86,and can be used to measure low wind velocity, which cannot be measured using a standard Pitot-Static tube. 2) Pitot tube coefficients decrease when Fence diameters are between 1.6 to 1.8 times of the Can diameter.

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The development of an air jet retrieval system of the gravel scattered on the road surface for the slip prevention is studied. The purpose of this study is to clarify the optimum installation condition of the jet nozzle for blowing the gravel. The height of the nozzle exit was h=5mm, and the width was 50mm. In changing blowing angle θ of the jet and standoff distance from the road surface y_0,the blow off regions of the gravel were photographed and velocity distributions over the road surface were measured by hot-wire anemometer. As the result, optimum installation condition of the jet nozzle were found to be y_0/h=2〜3 and θ=15°∿20°, Where the blow off distance of gravel is increased.

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When two circular cylinders of different diameter are placed side by side in a uniform flow, fluctuating fluid forces acting on them vary with the spacing between them, and at very small spacing switching phenomena are observed. In this study, transitional characteristics of the switching phenomena are investigated by statistical analysis of localized average and localized standard deviation of fluctuating signal of lift acting on the circular cylinder of larger diameter.

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The results of a wind tunnel investigation on Strouhal frequencies of two identical, stationary, parallel circular cylinders arranged in staggered configurations, carried out in a uniform cross flow at a Reynolds number of 5.5×(10)^4,are presented in this paper. The new findings in this study are as follows. (i) When two cylinders are arranged with a stagger angle α=10°, there exists a superharmonic frequency on the inside surface of the downstream cylinder due to convective vortices from the upstream cylinder for spacing ratio of T/D>2.4 and bistable nature of flow for T/D<1.3. (ii) For α=25°, T/D=1.1&acd;1.8,a tristable nature of flow with regard to Strouhal number is detected by wavelet analysis, (iii) There exists a bistable nature of flow with regard to Strouhal numbers for α=45°, 60° and 75° in certain ranges of T/D.

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Lift forces and flow configurations of two circular cylinders in staggered arrangements at a subcritical Reynolds number of 5.5×(10)^4 were investigated experimentally. For very small spacings, lift forces acting on the cylinders change drastically with change in spacing ratio and are mainly governed by the behavior of the flow in the gap between the cylinders. The action of lift force acting on the upstream cylinder is attractive (negative) for smaller stagger angles and is repulsive (positive) for higher stagger angles. Bistable nature of flow at a series of spacing ratio is detected for two staggered circular cylinders.

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