Experiments of static creep, full reversed low-cycle fatigue and low-cycle fatigue with hole-time in tension were performed using commercial pure copper specimens at 270°C. Number of cycles to rupture of the specimen in fatigue with hold-time is smaller than that in pure fatigue, and this holes for the basis of time to rupture. Both crack initiation damage φ_i and propagation damage φ_p of the material computed by linear damage rule are nearly equal to unity. In the fatigue test with hold-time, the reversed loading from tension to compression results in a slower rate of crack propagation and this is interpreted from the dislocation model.

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The essential features of the distortional deformation of an open-cross-section member are studied. The analytical models are restricted to the members of one-degree-of-freedom. The assumptions used in the semi-membrane theory are employed, and one dimensional analytical method applicable to distortional deformation is introduced. The concept of two shear centers of distortion can be introduced. This is an extended concept of a centroid and a torsional shear center. The distortional bimoment introduced here should be taken into consideration as a generalized force. According to the results of the calculation of a cantilever, the stress value at the fixed end has the possibility of being about twice as high as the value of the conventional beam theory.

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Through a theoretical study on the general constitutive equation for an elastic/viscoplastic/plastic body, the experimental methods to examine the existence of the instantaneous plastic property and to obtain directly a practical form of the general equation are given. Combined tension-torsion impact testing apparatus with special mechanics was designed which could apply a combined stress pulse with a very short rise time, about 15 μs, to a thin walled tube. In an experiment of the incremental torsional impact to commercial pure aluminum and copper specimens, the analogous phenomena to the instantaneous plastic response were observed for both materials.

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The principal object of this paper is to investigate the fundamental properties of solutions with singularities in the theory of elasticity in order to consider its meaning as a concentrated load and possibility of applying it to practical problems, using the stress functions with singularities. The principal results are as follows: (1) The so-called force of a center of dilatation plays an important role in many problems of elasticity. If we appropriately distribute problems are obtained, and it is possible to make clear the meaning of a solution. (2) A hollow elastic sphere with two rigid taper pins inserted is analysed. (3) An exact solution to the problem of a center of dilatation acting at a point inside an elastic half-space is shown. (4) An exact solution to a problem of an indefinitely extended elastic solid subjected to radial forces acting on a finite straight line (a segment of crack subjected to an inner pressure) is shown, and it is compared with the result for an elastic half-space.

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Free vibrations of a string with time-varying length are analyzed. An equation of motion is the well-known wave equation. Since the length of the string varies with time, its free vibration can not be determined by previous methods. Therefore, new variables of position and time are introduced and the equations of motion with respect to the new variables are solved by method of separation of the variables. Though so-called "eigenvalues (or eigenfrequencies)" and "eigenfunctions" are determined, "eigenfunctions" and initial conditions are expanded into Fourier sine series and then algebraic equations of infinite dimensions are introduced. In such a way, the free vibrations are solved.

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Recently, train noise has become a great social problem. One of its main causes has been reported to be the vibration of the wheels, but only a few studies in this area have been reported. The authors made a wheel noise and vibration testing machine which had two wheels simulating the train wheel and the rail. The relationship between the noise and the vibration was studied, and the following results were obtained. 1) The noise is caused by wheel axial vibration. 2) Wheel axial vibration can be theoretically modeled by the vibration of a circular plate with the boundary conditions that the inside circumference (axis) is fixed, the outside is free and one point on it is simply supported.

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The paper presents an new dynamic absorber which consists of a variable stiffness-type spring, a mass, and a magnetic damper using the damping effect of eddy-currents. It has advantages that the absorber is able to use for improving the damping property of a main vibration system where changes of the natural frequency take place, and it is stable in damping characteristics under varying environment. To examine its practical applications, the damping performance of the absorber is studied in both experimental and theoretical aspects with a specific view to improving the dynamic stiffness of the ram structure. Further, the relation between viscous damping coefficient and intermediate factors of the magnetic damper is deduced in order to realize the best damping optionally.

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In the analyses of unsteady two-dimensional incompressible laminar flows past an obstacle by means of the vorticity transport equation and Poisson's equation of stream function, a condition [numerical formula] must be satisfied along a closed curve round the obstacle. First, the condition is derived from the one-valued pressure condition, and the relation between the condition and the boundary values of stream function is discussed. Next, for the duct flow with an obstacle, a finite-difference method is proposed for obtaining the solution to satisfy the condition. Them a numerical example that a flat plate in the parallel walled duct is initially at rest on the center line and then oscillates transversely is solved, and flow behavior leaving the plate and the time-variation of lift and drag forces of the plate are shown.

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Basic theoretical consideration is made on the dynamics of fluid mixtures in which dynamic interaction among the component fluids is significant. The expression for kinetic energy of the fluid mixtures is assumed to be a general quadratic form of the velocities of the component fluids. The conjugate momenta are defined and the equations of motion are obtained as stating the evolution of the conjugate momenta. The method of derivation is based only on the most dependable principles, i.e., the conservations of energy and masses as well as the invariance with respect to Galilei transformation. The constitutive equations are given for cases with no energy dissipation.

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This study has clarified the characteristics of the fiat disk valves with a rounded inlet corner of clearance. In the range of small lifts in which water is used as the experimental fluid, the head distributions at the inlet pipe are almost constant. And there is no difference between the head at the valve and that at the valve seat. On the other hand in the range of large lifts in which #30 motor oil is used as the experimental fluid, the head distributions at the inlet pipe depend on the size of rounded inlet clearance. And a decrease in head at the inlet pipe is almost equal to the additional loss of head. It is clear that the additional loss of head occurs at the entrance part which is the area between the center of inlet pipe and the inlet of clearance.

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Analytical method for heat conduction with freezing, by using the apparent heat capacity which takes into account the latent heat effect, was applied to freezing of materials containing aqua-solutions. The method was examined with experiments and had its validity established for analyzing the freezing problems of materials not having a fixed freezing point but being in solidification ranges. The method to decide the apparent heat capacity by means of the phase diagram was also shown.

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The phenomenon of freezing around a cooled pipe in crossflow is investigated experimentally and theoretically. The thicknesses of a frozen layer under various freezing conditions - temperatures of water and the cooled pipe, the velocity of water, and the pipe diameter - are measured at both transient and steady states, and the characteristic shape of the frozen layer is obtained. The equations expressing the shape of the frozen layer are obtained from the characteristic, and the process of growth of the frozen layer is analyzed from combining the heat conduction in the frozen layer with the forced convection heat transfer around the frozen layer. It is shown that the analytical results agree well with the experimental results. A simple non-dimensional relationship between the overall heat transfer rate from water to the pipe at the steady state and the above mentioned freezing conditions is obtained from the analysis and the experiments.

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Displacements of spatial four-bar mechanisms which have revolute or prismatic pairs on the fixed links and have revolute, prismatic, cylindric, spheric or sphere-groove pairs on the coupler links have been systematically analysed by means of seven transformation functions. The maximum numbers of displacement curves existent in each mechanism on account of geometric inversions of links have been also clarified by means of the transformation functions.

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Experiments on the wedge indentation of a porous material are carried out using workhardened and annealed specimens of sintered copper powder. Studies are made on influences of the initial relative density, the wedge angle and the frictional condition on the indentation pressure. The indentation pressure is compared with the flow stress obtained from tests of plane strain compression of sintered copper powder. The deformation pattern is also obtained by means of the grid method.

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An analysis of indentation of a porous material with square-based pyramids is made. The analysis is based on an approximate energy method using a velocity field which is constructed with the slip line field for the wedge indentation of the porous material. The hardness, that is, the indentation pressure is expressed as a function of the yield stress and the relative density of the porous material. Experiments on the indentation with square-based pyramids are also carried out using workhardened and annealed specimens of sintered copper powder. The experimental results are compared with the theoretical results.

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For helical gears which have tooth form error and pitch error simultaneously, the calculating method of the maximum tooth fillet stress σ_max is shown, and the effect of tooth form on σ_max is discussed: The ratio between σ_max and the maximum tooth fillet stress of error free gears can be expressed as a function of two variables: one variable is the ratio between amplitude of tooth form error and tooth loading, and the other is the ratio between pitch-difference and tooth loading. Some charts and diagrams for the ratio concerning the maximum tooth fillet stress are shown. It is also theoretically shown, that the convex tooth form induces the least or almost least stress increase comparing with another tooth form, and for some gears convex tooth form prevents the stress increase due to pitch error, if its amplitude is properly chosen.

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