The present authors have recently proposed a new method for obtaining the stress intensity factors for the opening mode cracks. The same method has now been extended to the calculation of the stress intensity factors for the sliding mode cracks. The usefulness of the method has been tested with a number of rectangular plates having oblique straight cracks of various inclinations and lengths, and the results have turned out to be fairly satisfactory. In addition, a static problem of a rectangular plate with a pair of oblique cracks emanating from the boundary surface of a circular hole and a dynamic problem of a rectangular plate with an oblique straight crack are investigated.

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Mode III fatigue crack growth was studied using cylindrical specimens with ring-shaped edge cracks under reversed torsion. Cracks grew locally in Mode I making small branches but their macroscopic growth direction was perpendicular to the specimen axis. The crack depth was successively estimated by the compliance calibration method and the growth rate of torsional cracks was related to the applied stress intensity factor range ΔK_III. In torsion, friction must be considered together with mutual sliding of pre-fatigue crack surfaces. Consequently, the applied torsional torque should be modified in evaluating the effective stress intensity factor. Effect of the surface friction on the stress state around the crack tip was examined by an elastic-plastic finite element analysis.

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An internally-pressurized hollow cylinder with a reinforcing ring is studied within the framework of the three dimensional elasticity theory, and the effects of the ring width and the cylinder thickness on the stresses and deformations as well as contact pressure are examined. We assume no shear stresses in the contact zone. The use of Dougall's stress function and method of Fourier transforms then leads to a dual integral equation, which is reduced to simultaneous algebraic equations by use of a series expansion method.

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The transient thermal stress concentration of a notched semi-infinite plate is analysed numerically. The plate which is initially in a uniform temperature state is assumed to be heated along the straight and notched boundaries through a fluid touching directly on it. The notch shapes are semi-elliptic with various radius ratios. A finite-difference method is used both for temperature and stress analyses. The finite-difference mesh is formed on basis of the equi-potential and flow lines in the potential flow around an elliptic cylinder. It is found by this method that the thermal stress concentration increases with time and the Biot number of heat convection. An approximate method, by which the stress concentration factor of a semi-elliptically notched strip with finite width can be estimated, is proposed.

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In this paper, the contact stress between two different finite hollow cylinders connected by a bolted joint is studied. The three dimensional theory of elasticity is used to analyse the contact stress and the deformation in laminated finite hollow cylinders whose both sides are compressed axisymmetrically under a local uniform pressure. By neglecting shearing stress on the contact surface, an exact solution satisfying the remaining boundary conditions is obtained. Numerical calculations are carried out for various rigidities and thicknesses of the finite hollow cylinders under various loading conditions. In order to examine the results of the theoretical analysis, the contact stress is measured experimentally by using pressure-sensitive pins attached to a finite hollow cylinder. It is confirmed that the theoretical results agree well with the experimental ones except at the vicinity of the loaded area.

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An interference effect of notches on the strengths and deformation properties of rectangular and cylindrical specimens with double U-notches is investigated experimentally. The stress at which the tensile load vs. elongation curve begins to depart from its elastic slope also reduces due to the interference effect. The magnitude of the interference effect on this stress is the same degree as that on the general yield strength, and is not predicted on the basis of the interference effect on the elastic stress concentration factor although the plastic region near the notch root is much smaller at this stress level than at general yielding. The interference effect on the notch tensile strength of the material with both weak strain-hardening and small total elongation can be predicted accurately from that on the yield point load or on the general yield strength. The interference effect produces an X-shape extension of the plastic region. In the notch pitch range influencing the interference effect an inclined plane fracture occurs due to the X-shape extension of the plastic region.

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Stress analysis of diametrical compression of an elastic circular cylinder between two smooth, flat and parallel rigid planes is performed by the indirect fictitious-boundary integral method. As the contact conditions, a frictionless case and a perfectly adhesive case are treated. Through the present study, an applicability of the present method to the contact problem is confirmed and the deformation process of the surface becomes clear.

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In this paper internal pressure tests are carried out on coated and naked cylinders made of cast iron to study the effect of pressure fluid on the bursting of brittle materials, with the following conclusions : (1) In the naked cylinder the strength under internal pressure differs depending on the pressure fluid. (2) In the naked cylinder having a constant diameter ratio, there is a remarkable size effect even with the same pressure fluid. (3) There is no size effect in the coated thin-walled cylinder.

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For an elasto-plastic crack, the crack energy density, of which the concept was proposed by author as the most important parameter to explain the behavior of crack, and the energy release rate are discussed. The results are as follows : (1) The relation between crack energy density and load-displacement curve is discussed and a method to evaluate crack energy density from load-displacement curve is established. Also, the physical meaning of so-called J_IC-test is clarified. (2) A general expression of energy release rate for an elasto-plastic crack is obtained, which is available for completely elastic fracture, fracture accompanied with small scale yielding and also fracture accompanied with large scale yielding. (3) The behavior of an elasto-plastic crack is explained from the stand-point of energy, and an error in Orowan-Irwin theory based on energy balance is pointed out.

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Three different methods were devised to determine the induced angle of attack as a function of lift coefficient at the mid-span of a circular cylinder with tangential blowing immersed in a uniform flow. The characteristic values such as aerodynamic coefficients of the cylinder were corrected to give two-dimensional ones by making use of the induced angle of attack thus obtained. The circumferential static pressure distribution on the surface of the cylinder was also calculated by modified Parkinson-Jandali's method to apply to an asymmetric flow around the cylinder with blowing.

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A numerical method is developed for analysing a three-dimensional steady incompressible potential flow through a cascade in axial flow turbomachines. In this method, the velocity potential of the absolute flow is determined by the functional minimization finite element method using hexahedral trilinear elements, and the velocity is calculated by a newly developed finite-difference method based on a quadratic polynomial approximation. A significant feature of the present method is to consider reasonably vortex sheets shedding from the trailing edge of blades in the finite element procedure. Therefore, the present method is applicable to more general design conditions including nonuniform blade loadings. As a numerical example, the flow through a moving compressor cascade is computed, and the calculated velocity and pressure distributions are shown. The solution is obtained stably and the computer time is relatively small. But the required computer memory is rather large.

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In this paper an experimental study on the behavior of the air-liquid surface in various vertical and circular pipes is described. The case when a liquid piston is suddenly started from a vertical pipe which is previously filled up with a liquid and pressurized air on the top, is examined. It is known that the measured velocity of the tip of the surface agrees approximately with the simplest one dimensional model, and the shape of the surface is divided into two areas ; one is flat shape for the case of nearly constant velocity, and the other is spherical shape accompanied with an accelerating velocity. And further, the effects of an obstacle on the wall on the air-liquid surface behavior are obserbed, and it is found that sometimes a turbulence appears on the surface and grows up sharply, and the condition for the growth of the disturbance depends on Reynolds number and stability number.

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Among many different types of transonic wind tunnels, a transonic Ludwieg tube is the most suitable facility for very high Reynolds number transonic wind tunnel testing. At present, however, the transonic starting process and starting time of this short duration test facility are not well clarified. In the present paper, the starting process of transonic Ludwieg tube with a quick-opening valve upstream of the transonic test section was experimentally investigated over a range of plenum chamber volumes and flow rates using a plenum exhaust system. As the result, it has been shown that a steady and uniform flow in the test section is established when the mass flow rate through the porous wall of the test section becomes equal to that through the plenum exhaust system. Based on the experimental results, wave diagrams showing the starting process were presented, and the flow mechanism of the starting process was clarified.

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In this paper, a numerical method for the analysis of flow and heat transfer in condensers is presented. This method is based on the modified FLIC Method using triangular mesh pattern of FEM and on the idea of anisotropic porous media modeling the flow resistance and heat transfer of tube bundles, and is suitable for analysis of the flow and heat transfer problems in condensers with tube bundles and baffle plates of any complicated configuration. This method was applied to two examples, a one-dimensional experimental condenser, and a two-dimensional experimental condenser. The calculated results were compared with the experimental results and good agreements were obtained.

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A series of experiments were carried out for small-scale vapor explosions in a "dropping" system using molten tin and water. Experimental parameters such as initial tin temperature, water temperature, ambient pressure and sample size of tin were varied over a wide range. The pressure of explosion, the rate of occurrence of explosion and the position of explosion were measured in detail. It is found that tough the vapor explosion has in general statistical characters, a delay time between tin-water first contact and explosion increases systematically with both water temperature and initial tin temperature. As a resul, it is concluded that the vapor explosion is closely related to transient boiling phenomenon, especially to the collapse of a stable vapor film around the molten metal.

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Measurments on the behavior of diesel fuel spray from a microscopic viewpoint are important to clarify atomization mechanism and temporal change in droplet size distribution. In this study, diesel spray injected from diesel nozzles into a quiescent atmosphere at room temperature and high pressure is observed by means of a direct microscopical photographing method varying the photographing time and the nozzle type. The results show that the mechanism of spray atomization is divided into 4 processes, and spatial distributions of breakup droplets are assessed. As time passes, spray droplets are distributed in a stratiform shape. And total distribution of droplet sizes and droplet size distribution in local region are expressed in equations as a function of time from injection, and changes in the distribution with the nozzle type are discussed. Subsequently, temporal changes in the uniformity of the distribution and in spatial distribution of droplets volume rates are clarified.

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So far the studies on the dynamic characteristic of internal combustion engines have been mainly carried out on the governor system and have led to development of a mathematical model more efficient for simulation and control purpose. But, there are still uncertain dynamic behaviors of the engine. The experiment and analysis on the transfer characteristic of effective torque under a changing fuel feed quantity or brake load were carried out by using the frequency response and indicial response methods. Consequently, it was confirmed that the transfer response of effective torque to the changes in fuel feed quantity and brake load comprises a response time lag and its time constant is variable with the operating condition of the engine.

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A cylinder block of 4 cylinders is analyzed by the component mode synthesis method. The component mode synthesis method is a general method of analysis of the vibration of a complex mechanical structure using the natural modes of the components. A structure is divided into some components. All components are classified into master components and branch ones. The natural modes of each component are determined by the finite element method. The natural modes of all components are synthesized to form the generalized system coordinates. The equation of motion under these system coordintes is solved to know the vibration of the total structure.

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In this paper, we show a method for analyzing free vibrations of thin cylindrical shells with noncircular cross sections which have been used in chemical plants, atomic plants, flight structures and so on. This method is a general one applicable to various noncircular cylindrical shells. As the first step, we obtain an exact solution of a noncircular cylindrical shell with freely supported ends. By the numerical calculations, we obtain natural frequencies and mode shapes of elliptical cylindrical shells and clarify their characteristics.

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Natural frequencies, natural modes and transfer functions of a combination of crankshaft and flywheel are investigated by a reduced impedance method the author proposed. The crankshaft is divided into a straight shaft part and an arm part. The straight shaft part is expressed first by the transfer matrix of Timoshenko beam, which is transformed into an impedance matrix. The arm part and the flywheel are expressed by the finite element method, and the impedance matrix of the arm part and the flywheel is reduced to the degrees of freedom of only the central node of their boundary parts. An equation of motion of the total body is made of these reduced impedance matrices, and this equation is solved to get natural frequencies, natural modes and transfer functions. The calculated results agree well with the experimental ones.

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A practical method whereby the damping ratio of a structure subjected to random excitations can be estimated is proposed. This method is based on the characteristics of the AR spectral analysis technique by Akaike. Using good correspondence of the shape of the frequency response function around the dominant peaks in the proposed method to that in the linear structural theory, estimation of the damping ratio to the fundamental vibration modes can be satisfactorily carried out by using curve-fitting technique. As a practical example, the damping ratio for the ground model which is necessarily used for the generation of an artificial earthquake motion is estimated and quite good results are obtained. It is expected that this method will be widely applicable to other technical dynamic problems in which estimation of damping is required.

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For the purpose of suppressing the ground vibration as public nuisance produced by vibrating machines such as a forging machine, a press machine, etc., this paper presents a new type active force controller. First, the principle of the active force controlling method is shown, and the system equations are derived. Secondly, the characteristics and the design parameters of the active force controller are presented. Thirdly, from a point of view of feedforward control method, three kinds of the dynamic compensators are designed so as to obtain sufficient effectiveness of suppressing the exciting force. Finally, in order to demonstrate the control effect, an experiment is carried out, and then the active force controller is proved to be applicable for suppressing the ground vibration as public nuisance.

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In a vibrating system (principal mass) attached on a damped magnetic dynamic absorber containing two fixed side magnets and an absorber magnet (floating mass) which is subjected to an external periodic force, the amplitude of the principal mass will be decreased, but by the character of the magnets in the magnetic dynamic absorber, a non-linear motion occurs in the vibrating system and also sub-harmonic vibrations are induced in it. In this paper, the sub-harmonic vibrations, especially the 1/2 sub-harmonic and the 1/3 sub-harmonic vibrations which occur in a vibrating system, are analyzed, the characteristic curves of the amplitudes are obtained, and the stabilities of those vibrations of the system are discussed. Moreover, the experimental results are shown. They almost agree with the theoretical results.

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This paper deals with dynamic characteristics of an oil damper, whose piston is vibrating axially in a viscous fluid filling a fixed circular cylinder. Assuming a one-dimensional flow past the annular cross-sectional clearance between the piston and the cylinder, we evaluated a drag force acting on the piston. And the analytical results were compared with experimental observations. The following results were obtained. (1) The velocity profile in the clearance depends on the dimensionless factor λ= h√(ω/(2ν)), where h, ω, ν are radial clearance, circular frequency and kinematic viscosity, respectively. Being a parabolic distribution within λ<2 as is the case in a steady flow, for larger values of λ the velocity profile approaches uniformity over the clearance. (2) Pressere drag and friction drag exerted on the piston are both out of phase with the velocity of the piston. Therefore "damping coefficient" and "added mass" must be deemed the representative characteristics of the oil damper.

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A hydraulic shock absorber in a mechanical system was designed using a SUMT for optimum response to velocity shock. The resisting force of such a shock absorber is expressed as the product of the shock absorber velocity squared and a coefficient expressed in terms of the shock absorber displacement. In this paper, unknown parameters for optimum design include the piecewise linear resisting force of the shock absorber, spring constants, and a damping coefficient. As examples of the mechanical system using the shock absorber, springs, and damping to be optimized, high-speed models of car-to-barrier collisions are considered. As the result of numerical calculations, the optimum characteristics of the shock absorber, optimum spring constants, and optimum damping coefficient that minimize the maximum absolute acceleration of a mass in the mechanical system are obtained, and the effectiveness of using SUMT in dealing with the present problems is confirmed.

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This paper deals with the motion of a stilts type biped locomotion which is not constrained to a plane (e.g. sagittal plane). This kind of biped, just like stilts, has no knees and no dimensions of the feet, therefore stepping must be continued repeatedly to maintain an upright balanced posture. In order to achieve stable walk, both feedforward and feedback control are utilized. By computing the required actuator torque from the equations of motion, the feedforward control produces the planned ideal motion. The feedback control makes the biped stable around the planned trajectory. On this principle, BIPER-3 control system was constructed and the stable walk has been realized.

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As a basis for the automated machine design, an automatic and optimal design method, and computer program for mechanism elements are developed in this first report. This method consists of two parts, i.e., stress analysis and size optimization. The stress analysis is based on the displacement method, which is ordinarily used for the three dimensional frame structure analysis. The size optimization is based on the steepest descent method. The computer program developed in this report can determine the optimal dimensions of mechanism elements, such that the stress and compressive load of each part do not exceed the allowable stress and buckling load respectively, and that the weights of mechanism elements are as small as possible.

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This paper describes the effects of the crystal orientation upon the cutting phenomenon. The experiment were performed by orthogonal cutting of aluminum single crystals having the (111) plane and the (112) end plane. The results show that the effects of the orientation appear clearly in the cutting phenomenon. That is, the specific cutting force Ks, the shear angle and the amount of the side flow periodically fluctuate corresponding to a change of the cutting direction. It is revealed that the cutting mechanism of polycrystalline cold rolled materials is in good conformity with one of a single crystal having (112) end plane. The mechanism in the formation of the finished surface can reasonably be explained from the slip system of the crystal.

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The previous knowledge of the hobbing torques is useful to the strength-design for the hob teeth, the decision of optimum cutting conditions for the strength of the hob teeth and the analysis of vibrations on the hob machine. The hobbing torque is calculated from the cross sectional area of cut of the hob tooth and the specific cutting force of the gear material. This paper presents the calculating method of the cross sectional area of cut of the hob tooth, and also shows the methods of simple turning tests by which the specific cutting forces applied to hobbings are obtained. From the comparison of the calculated hobbing torque waves with the measured ones in hobbing tests, it is confirmed that the profiles of the hobbing torque waves are very much alike.

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Fundamental research was made on the effect of the components of the soluble cutting fluids and on the range of application of the fluids for the purpose of developing soluble cutting fluids which have cutting ability close or superior to that of cutting oils. The follwing results were mainly obtained : there are some soluble cutting fluids which decrease the damage of cutting tools more than the cutting oil at a high speed of l59m/min ; among the testing fluids containing rape-seed oil, chlorinated paraffin and sulfurized fatty oil respectively, the fluid, 40% of which consists of sulfurized fatty oil, gave the best performance in the wear on cutting tool and in the roughness of finished surface.

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