In this paper a transient elastodynamic analysis of the stress intensity factors at the propagating tips of both a bifurcating crack and a skew one is presented. In the method of solution, the stress field in the vicinity of the crack tip is analyzed under a peculiar loading which makes the antiplane displacement self-similar, and then the result is used to know the stress intensity factors for the case that a branching or a skew actually occurs. Then, on the assumption that the crack propagates in a direction which maximizes the total energy released in a unit time, the angle and the velocity of the bifurcating or the skew crack are determined. In the present treatment the considerations are restricted to the case of antiplane shear.

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A dynamic zooming analysis method (ZAM) is presented, to calculate efficiently dynamic contact stresses and their distributions by the finite element method (FEM). The zooming region is determined by the same method as the static ZAM. However, displacements and velocities of nodal points in the region are iteratively computed by use of boundary values until their values approach the correct ones at a specific discrete time. this method is used to evaluate correctly the approximated initial values of the equation of motion. To verify this dynamic ZAM, we analyze the dynamic contact stresses of contact-impact problems under a condition starting from very roughly approximated initial values. The results calculated by this ZAM agree with those directly obtained by the elastodynamic contact FEM. The dynamic ZAM is efficient to analyze the dynamic contact problems and the dynamic stress concentrations by a small machine memory. Then, this method can be applied to the elastodynamic contact analysis of structures consisting of complicated configurations such as mating gears.

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The purpose of this research is to study the problem of determining optimal shapes of structures from a unified point of view by using the inverse variational principle. In this report, optimal structural designs for the buckling and vibration problems are treated by this principle. In the former problem a change in the potential energy during the buckling is considered as an energy functional to be made stationary, and in the latter the sum of the strain and kinetic energies is so considered. It is shown that consideration of the variations of these functionals with respect to shape and displacement leads to the conventional method which maximizes Rayleigh's quotients. As examples, this principle is applied to bars discretized into finite elements to obtain their optimal shapes for which the buckling loads or the fundamental frequencies are maximum among all shapes with the same volume.

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The present paper is concerned with the indentation of an elastic half-space by an axisymmetric, slightly concave rigid punch. When the indenting load is small, the contact area will be an annulus, the outer circumference of which coincides with the edge of the punch. The inner circumference of which coincides with the edge of the punch. The inner circumference of which coincides with the edge of the punch. The inner circumference will shrink with an increasing force. The stress state of such a problem is analyzed based on the theory of three-dimensional elasticity. For each case of parabolical and conical concaves, we obtain the distributions of surface displacements and contact stresses and their relations to the indenting force, indenting depth and concave's shape.

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Three dimensional elastic analysis of a finite hollow cylinder is very important to a practical design of machine parts. A few kinds of problems on an infinite hollow cylinder subjected to axi-asymmetric loads has already been studied. But the problem of a finite cylinder subjected to axi-asymmetric loads has not yet been analyzed. In this paper, a double Fourier series solution on the analysis of a finite hollow cylinder subjected to axi-asymmetric loads has been obtained by introducing stress functions which are given as series forms. Numerical results for some boundary conditions are obtained by using a digital computer and effects of Poisson's ratio, the ratio of inner radius to outer radius, and so on are discussed.

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There is a phenomenon making the internal flow in the wall-attachment fluid amplifier unstable. That is, a jet issued from the nozzle exit causes a continuous switching action between two side walls, and attachment of the jet to the walls becomes unstable. This unstable phenomenon is often observed when the fluid amplifier has a relatively large offset distance and a small splitter distance. This seems to be a kind of oscillations since it has almost constant periods. The frequency of the oscillation is low and it is changeable slightly when either the offset distance or the splitter distance changes. Hence, this unstable phenomenon can be used for a low frequency oscillator i practice. Geometrical shapes of the fluid amplifier having this unstable phenomenon are measured and frequencies are also measured.

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Resonance in pressure conduits is studied on complex pipe systems which are composed of series, branching and parallel piping lines. In such complex systems, shapes of the resonance curves and also resonance frequencies differ remarkably depending on the location of input or output of the lines. It is shown that these phenomena are generally observed in a simple line or in a system with many degrees of freedom. Next, transient response plots are obtained experimentally for conduits lines with various boundary conditions such as open-end, closed-end and some loads. These plots are compared with results of numerical analysis obtained by the characteristic method. Their agreement is good.

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The flow induced in a particle-fluid mixture by an infinite flat plate, which oscillates in its own plate, is studied theoretically, assuming Basset-Boussinesq-Oseen's form of the interaction force between a particle and fluid. the influence of frequency and density ratio on the boundary-layer thickness, the wavelength of the viscous wave, the particle velocity and the viscous stress is examined i a discussion on the general properties of the basic equations and analytical solutions. It is shown that the time-dependent interaction force between a particle and fluid is important in the case of high frequency and the particle lighter than the fluid. It is not appropriate to assume Stokes' formula in these cases.

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The dependence of heat transfer on the cross-sectional distribution of void fractions in a diabatic two-phase bubble flow has been explored experimentally. A vertical tube of 16.9 mm ID was employed in the investigation. Two different types of the mixer were installed to realize the flows with different types of the mixer were installed to realize the flows with different distributions of void fractions even at the same flow rates of both phases. It was found that these two types of flows present different heat transfer coefficients due to the difference in the void fraction distributions. Increasing the void fraction near the tube wall causes an increase in heat transfer coefficient. The effect of bubble agitation on the thermal diffusivity in the radial direction is discussed based on the distributions of both void fractions and liquid temperatures.

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This paper presents analytical and experimental studies of transient laminar heat transfer from a flat plate with a constant heat capacity. The flat plate which was set parallel to a uniform flow, was initially at the same temperature as the flow, and a transient process was initially at the same temperature as the flow, and a transient process was initiated by heating stepwise with time. Transient laminar heat transfer characteristics on the plate were calculated by the Laplace transform and numerical inversion of the Laplace transform. The variation of local wall temperature of the plate was measured by a resistance thermometer of vacuum deposited nickel thin film. Close agreement between measured and calculated values was obtained.

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Turbulent shear stress and heat flux were measured using a hot-wire anemometer in the separated, reattached, and redeveloped regions of an axisymmetric incompressible air flow over a longitudinal circular cylinder having a blunt leading edge. The characteristic features of a turbulent heat flux are detected to be quite different from those of a turbulent shear stress, and in the turbulent boundary layer downstream from the reattachment point, the development of the turbulent heat flux is much quicker than that of the turbulent shear stress.

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Temperate zone such as Japan suffers from not only hot weather in summer but also cold weather in winter. This study explores the possibility of such seasonal thermal storage in terribly different weathers that undergroundwater stored in each available season can be used for heat sink or source. In this paper we made clear a 40% recovery in winter of the temperature of warm water stored during summer, both by field experiment and by numerical analysis. Finally we propose a suitable well distance at while thermal pollution caused by injection does not occur and effective utilization of seasonal thermal storage in aquifer can be expected.

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Kerosene-hybrid combustion was studied in a swirler type combustor. Kerosene was atomized by an air blast atomizer, and geseous hydrogen was supplied to a kerosene spray through an annular slit installed in the atomizer. The following results were obtained. Blow out limit of the flame shifts to the lea side of the air-fuel mixture in the hybrid combustion. Hybrid combustion results in a slight decrease in NOx emission and a remarkable decrease in soot emission. When the hybrid ratio is under 10%, the flame stability is improved by the hybrid combustion. Increasing the hybrid ratio from 10% to 50% produces and increased combustion efficiency and reductions of soot and NOx. While the hybrid ratio is over 50%, the characteristics of the hybrid combustion flame become similar to those of hydrogen gas flame.

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In designing electromagnetic levitation (EML) vehicles as a means of high speed ground transit, it is important to explore the dynamic interactions between a long train of EML vehicles and their guaideways. For the numerical analysis of this system, the computer simulation program has been developed, in which vehicle equations are fully coupled with guideway equations through distributed suspension forces. Vehicle motion is asumed to consist of heave and pitch of the vehicle body and heave of two trucks. According to the analysis, there is a difference between variations of the vibration of each truck or each vehicle body, especially in a high speed operation, depending on the velocity parameter, the truck intervals and guideway structures. In some cases, the variations of the vertical accelerations and the clearances between magnets and guideway surfaces at the following vehicles tend to increase to about twice those at the preceding one.

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This paper deals with two methods of analyzing and planning an assembly work. First, we propose a method of breaking the assembly work down into its work elements, in which all parts constituting the product are classified into unit groups based on the fastener method in assembling (e.g. bolted joints, riveted joints, shrinking and pressing fits, and so on). As a result, the assembly work is broken down into its work elements which fasten the parts in each group. At the same time, a problem of precedence relation among them arises. Secondary, we propose an assignment method in which the number of stations is determined, and the work elements are assigned to the work stations in a single assembly line as the efficiency of line balancing alters as a variable. By using the methods proposed here, we could analyze the assembly work consistently through breaking it down into work elements and assigning the work elements to work stations.

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In case of solving simultaneous equations with a number of variables, many limitations are imposed with respect to the capacity of memory of computers or processing time of computation. Especially, applying the existing methods to nonlinear equations requires a large capacity of memory and the rate of processing of computation becomes very slow. So, a new method with a doubly accelerating scheme to solve such equations numerically is proposed and some numerical examples of solution are shown.

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The authors calculated the deflection of spur gear teeth by using a two-dimensional elastic theory and the mapping function, and compared the calculated results with the values calculated by the well-known tooth deflection formulas. Consequently, it was found that all values of tooth deflection calculated by this method are smaller than that by the well-known tooth deflection formulas and the measured value, because of the Herzian contact deformation, which is smaller than the value obtained from Lundberg's method. Furthermore, it was also found that the tooth deflection is nearly proportional to the tooth load.

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It is very important to study the load carrying characteristics i. e. limiting load for scoring, specific wear and efficiency of hypoid gears. But only a few experimental results have been reported in this field. From this point of view we made a new equipment of power circulating type for testing of load carrying characteristics of hypoid gears. By means of this equipment we found general tendencies of load carrying characteristics of hypoid gears by using four kinds of oil. Furthermore we have compared our test results of hypoid gears with other test results of FZG spur gear test, crossed helical gear test, 4-ball test and roller test.

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In a bolted joint receiving repeated impacts, the slip between external and internal threads is the cause of loosening of the employed fastener and subsequent failure of the joint. Selection of right locking method is important to minimize the detrimental effects of the slip in a joint. In this paper, firstly, a theoretical formula for self-locking of threaded fastener has been deduced from the theory of self-loosening process. Secondly, an equation for critical preload to cope with a certain repeated impact has been derived from the experimental results. Thirdly, by comparing the equation with the formula, the significance of parameters in equation has been clarified and the expressions of the parameters have been found out. Lastly, on the basis of experimental results, the performance of different locking method have been evaluated, the causes of difference of each performance have been evaluated, the causes of difference of each performance have been clarified, and the coefficients of impulsive friction for the threads have been calculated.

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Metal flow toward the triangular cavities remaining in web portion is studied to estimate forging load and the occurrence of laps during a filling stage of die forging. In the experiment plasticine-blanks with V-shaped grooves were compressed with upper and lower dies which had a flat-bottomed recess. The mechanism of the formation of laps and incomplete fills in the impression dies is analyzed by utilizing the slip-field solutions as upper-bound techniques. It has been proved by the analysis that five typical modes of deformation appear depending on the ratio of the volume of material flowing toward the cavities to the volume of material flowing into gutters. And it has been found that the shape and dimensions of the cavities and the amount of confinement of the material by the dies have a great influence on the depth of laps caused and the forging pressure.

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