This paper considers a cylindrical interface crack problem, from micro-mechanics-points of view, using a two phase material model consisting of a transversely isotropic circular cylinder embedded in a transversely isotropic infinite body which takes account of the anisotropy of a carbon fiber and the mechanical interaction between fibers. The problem relates to the stress state near a crack-like defect with curved surfaces at the interface between fiber and matrix in a unidirectional carbon fiber reinforced plastics. Mathematical formulations are made in terms of a Cauchy-type singular integral equation of the second kind and the results are compared with those of the macromechanics model in our previous paper.

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The effect of grain-boundary reaction (GBR) on high-temperature low-cycle fatigue life was investigated using an austenitic 21-4N heat-resisting steel at 973K in air. Grain boundary was considerably serrated by the occurrence of GBR during aging. The high-temperature fatigue with symmetrical triangular wave shape. The longest fatigue life was observed in the specimens with about 8% GBR in area fraction. The improvement of fatigue strength resulted from the inhibition of a brittle intergranular fracture by the serrated grain boundary. Therefore, it is important for the improvement of fatigue strength to reduce the extent of GBR to be small and to effectively use the strengthening effect of serrated grain boundary. The fatigue life was less improved by the GBR in the fatigue with asymmetrical triangular wave shape.

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The large deflection problem of a thin elastic simply supported beam is analysed for a symmetrical three-point bending .The derived nonlinear differential equation governing beam deflections is solved by applying the numerical method (R-K-G method) and the analytical method based on Legendre-Jacobi form's elliptic integrals of the first and the second kinds. Moreover, a reduction technique is proposed to estimate representative flexural quantities such as a maximum deflection, an end slope, and a maximum bending stress in large deflection states from the conventional linear bending theory in place of the exact large deflection theory. An experiment is also performed to confirm the applicability of the proposed large deflection theory. The experimental results agree well with those obtained from the exact large deflection theory.

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It has been shown that the Inverse Variational Shape Determination Method is a powerful tool to determine a structural shape on the basis of energy criterion subject to the constraint of the volume constancy. In this paper, the method is extended to three dimensional models and a procedure is proposed to treat the constraint easily. In numerical examples, the shape determination problems of the structures are solved under fundamental loading conditions such as tension, bending and torsion. It is shown through examples that the present method is applicable to the designing of actual structures and that it is especially effective in the case where behaviors of the structure under the applied load can not be predicted, that is, the method can be appropriately used in a preliminary design phase of a structure.

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This experiment has been undertaken to examine the relationship between the energy released from the movement of the hammer of the impact bending tester of the Charpy type and the stored energy in the fracture surface of the specimens in temperatures ranging from -90 °C to +30 °C. The specimens were slightly fatigued beforehand by bending in the same direction as the impact bending. The mechanism of the fracture of the specimens by impact forces has been clarified in the present study, after disseminating the information of the amount of energy accumulated in the tested specimens during the course of time. It was understood that the prefatigued notched carbon steel specimens showed a strong temperature-dependence for fracture at low temperatures.

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This paper presents an exact solution for the state of stress in an elastic circular cylinder with an oblate spheroidal cavity or an internal penny-shaped crack, which is subjected to a steady uniform heat flow. The solution is deduced with the aid of thermoelastic displacement potential and Dougall's harmonic stress function. Two sets of harmonic stress functions and two sets of biharmonic functions are given by simple expressions referred to the cylindrical and oblate spheroidal coordinates. The boundary conditions on the surfaces of the cylinder and the cavity area satisfied by using the relations between the cylindrical and oblate spheroidal harmonics and biharmonics. And the solution for the internal penny-shaped crack is given for a limiting case of the oblate spheroidal cavity. Numerical results for stress distributions, stress concentration factors and stress intensity factors are shown graphically.

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This paper is concerned with the appilicability of the ultrasonic technique to the measurement of the interfacial stress between metallic punch and some non-metallic plates. The characteristics of the ultrasonic wave due to the variation of the interfacial stress between metal and polymers are graphically presented. The changes in ultrasonic beam density due to spreading near the edge of the punch are then investigated, and the scattering characteristics of the wave are estimated on the basis of variation of the echo height as the probe is moved. The stress field of non-metallic plates indented by the punch is depicted in plots of the interfacial stress distribution, and quantitative ultrasonic techniques for the determination of an interfacial stress in polymers are discussed.

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In the nickel electroplating method of stress analysis, basal copper plating is indispensable when nickel is deposited directly on a steel specimen. in this paper, when the acid copper plating executed in a sulfate bath is utilized as the basal plating, effects of the current density and the thickness of the basal copper plating on the proper stress of the upper nickel plating are examined, and an optimum condition form the basal plating is obtained. From the results obtained, it is concluded that the acid copper plating executed in the sulfate bath can be used satisfactorily as the basal one in the nickel electroplating method.

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Oil column separation in the return line of a large oil hydraulic system is studied analytically, and the relation between the valve operation of the break-line mode and the rejoin surge pressure is investigated. The valve operation of the break-line mode, which has a lower operation speed near the closing point, shortens the valve closing time without increasing the rejoin surge pressure following the oil column separation. There is a region of the dimensionless valve opening corresponding to the break point of the valve operation, in which the rejoin surge pressure is lowered. The critical value of this region depends upon the dimensionless parameters which describe the return line. The result obtained in this study is available for the design of the breakline mode valve operation which shortens the valve closing time.

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An implicit time-marching finite-difference scheme is developed for computing steady two-dimensional inviscid transonic flows with arbitrary shaped boundaries. Most of the existing implicit time-marching schemes, including the Beam-Warming scheme, are unconditionally stable according to Neumann's stability criterion, but actually cannot take a sufficiently large Courant number, because the diagonally dominant condition of the coefficient matrix is lost. In the present scheme, in order to remove this restriction of the Courant number, the Robert-Weiss convective-difference scheme is applied in place of the Crank-Nicholson scheme in the Beam-Warming delta-form approximate-factorization algorithm. As a numerical example, shocked flows through a nozzle are calculated, and the results are compared with the one-dimensional theory.

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A method of measuring turbulence by means of the laser homodyne technique without relying upon time-sequential data, which ordinary methods use in obtaining information on turbulence, is studied. The principle of this method is to detect relative fluid motions of turbulence by receiving a beat of light scattered from each pair of tracer particles. A photoelectron correlation method is used to process the photomultiplier signal to yield statistical average of the light beat over the pairs in the measuring volume. A set of autocorrelograms that are gained for different dimensions of the measuring volume leads to a relation between fluctuating velocity and the dimension, which is fitted to the theoretical one to yield turbulence intensity and integral scale. A verification of the proposed method is made by comparing the results with hot-wire anemometer results. A disscusion is made on several factors that affect the accuracy.

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For an approximate calculation of the bounded jet flow, a velocity distribution function on the bounded jet center-plane is proposed, considering the effects of the wall turbulence and the free turbulence. Also, in order to determine the empirical parameter contained in this function, experiments were carried out using a nozzle having an aspect ratio of 16 with the initial turbulence intensity prescribed. As a result, the velocity distributions of the bounded jet flow are well expressed by the proposed function, regardless of the initial turbulence intensity. Furthermore, the variation of the flow patterns towards downstream can be shown by means of the parameter contained in the function.

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This paper presents the results of an experimental study on the reattachment of a radial turbulent jet flow discharged from a cylindrical nozzle on an adjacent offset disc plate, in the presence of a control flow. Static pressure distributions along the wall surface and across the jet flow were measured with a disc type pressure hole, and the effects of step height and control flow rate (suction and blowing) on them were investigated. Length and mean negative pressure in the recirculation region, and position of the attachment to the wall surface were examined. An oil film flow visualizing technique was also applied to determination of the flow pattern. The results were compared with those obtained from the pressure distributions.

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The present study was carried out to obtain basic data for the numerical simulation of pneumatic transport of solid particles. In the equation of motion of a spinning sphere, a force F^^→_v due to the velocity gradient of air flow through pipe was newly proposed. In the preliminary experiment, the drag coefficient C_d, coefficient of restitution e, friction coefficient μ_d were measured. Their values were substituted into the corresponding terms of the equation of motion. The equation of motion was numerically soved by the Runge-Kutta-Gill method. The values of lift coefficient C_L and coefficient G_s for F^^→_v were decided by making comparison between the computed and experimental results of the trajectory of sphere. As a result, C_d=0.6, G_s=0.1, C_L=(1.6-2.0) d_Pω/|W^^→| and μ_d=0.12-0.20 were obtained for the Reynolds number R_e.p =2000-6000.

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The steady flow characteristics around a swing-type valve plate installed in a rectangular duct are studied theoretically and experimentally in order to determine the fluid force acting on a swing-type check valve and the side-gap-leakage effects. The results show that the side-gap leakage has dominant influence upon the fluid force characteristics, which can be well predicted by a small modification of the conventional two-dimensional potential flow theory. For the case of a large side gap, the pressure over the valve plate becomes nearly uniform and is equal to the upstream one. And that the fluid force is expressed as a function of only the velocity ratio of the jet to the upstream, if the side-gap-leakage is less than the mainflow volume. It is pointed out that the separation zone at the back of a valve plate is recovered very rapidly due to momentum transfer effects of side-gap-leakage, and that the outlet flow from a valve plate is not contracted with its width nearly equal to the valve opening one. The experimental formulae of moment coefficient are also presented.

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Film flow of an incompressible, electrically conducting fluid in a non-uniform magnetic field is investigated theoretically and experimentally. The effects of the spatial gradient of the magnetic field strength on the flow are examined. Electric current is induced by an interaction of the non-uniform magnetic field with the flow field. And the combined action of it and the magnetic field causes the fluid to accelerate or to decelerate. The electromagnetic force which is induced deforms the liquid level curve and changes the film thickness, and it plays the role of a weir which never contacts with a fluid. An experimental study is carried out for mercury flow. Liquid level curves obtained by the experiments are shown to be in qualitative agreement with those of the approximate analysis. And experimental results can be explained well by analytical ones.

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Film flow of an incompressible, electrically conducting fluid in a nonuniform magnetic field was discussed in the first report. The effect of the gradient of an applied magnetic field strength on the film flow was clarified. And it was found that the electromagnetic force which is induced plays the role of a weir. In this paper a rivulet in such a field is discussed. When the flow rate is reduced, the film becomes thin, and then it ruptures and forms dry spots or a rivulet. Rivulet is supported by a relatively weak surface tension, and therefore it is easily influenced by the lateral force as well as the streamwise one. It is found that the lateral force which is induced by an interaction of the magnetic field with the streamwise component of the eddy-current acts like a non-contacting nozzle or a diffuser. An experimental study is carried out with a rivulet of mercury. The distributions of its widths and the heights of it are measured and they are shown to be in qualitative agreement with those of analytical results.

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This is a report on an investigation of the relation between an axisymmetric vortex breakdown and a stationary internal wave in a swirling flow field. An approximate mathematical model of the internal wave (wave disturbance) is constructed in consideration of fluid viscosity. Experiments are carried out on a swirling flow in a rotating pipe. The flow field, where internal waves occur, is observed by a visualization technique and is measured by a laser-Doppler-velocimeter. The effect of the upstream boundary condition on the internal wave is examined both by experiments and numerical calculations. The results are summarized as follows. A stationary internal wave occurs in a rotating pipe when the rotation is faster than a certain critical value. The characteristics of the waves are predicted fairly well by an approximate mathematical model. The bubble type breakdown is ultimately identified with the stationary internal wave of a sufficiently large amplitude.

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The mechanism of rotation of Savonius rotors which have two semicylindrical blades is studied experimentally. The force acting on a blade is measured in a water tank for both cases where a rotor is at rest and where it is rotated. A flow around the rotor is observed by using aluminum powder floating on the water surface. Although the Savonius rotor is classified as a resistance type, the lift produces a torque in a pretty wide range of blade angles relative to the flow.

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Equations of motion of solid particles in a pump impeller having low specific speed were solved numerically with assumptions of an inviscid and incompressible quasi-three dimensional flow, and the general behavior of solid particles in the pump was clarified. The particle trajectories and forces acting on particles, the diameters of which range from 0.1 to 0.5 mm and the specific-gravities from 1.8 to 5.4 were obtained for different flow capacities. The locations and the velocities, with which the particles impinge on the boundary surface of the pump, were also discussed in order to predict the erosion damage in pumps.

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Straight guide vanes are installed axisymmetrically around a Savonius rotor and their effects on the performances of the rotor have been investigated empirically using the wind tunnel. An experiment has been conducted varying the number of guide vanes, the setting angle of the vanes, the relative angle of the guide vanes to the wind direction and the inner radius of the guide vanes. Using the circular guide vanes the starting characteristic of the rotor can be improved considerably, and the values of the parameters when the power of the rotor increases are presented.

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The effects of the shape of rotor end plates on rotor performances have been investigated empirically by using five kinds of the Savonius rotors. The optimum shape of the end plate has been found from experimental results, and it has been revealed that the contribution of the lift force to the rotor power is considerably large. Then, by using a deflecting plate placed in front of the rotor, it has been attempted to improve the performances of the Savonius-type wind turbine. By the use of the deflecting plate, the power has been increased about 24 %. It has been also proved that the deflecting plate can be used as a speed control device or a protection device of the Savonius-type wind turbine.

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A transient boiling and a two-phase flow in a narrow channel were experimentally investigated under the condition of step-wise heat input in our previous reports. A periodic pulsating flow due to bubble growth and collapse was observed under relatively low heat input. In the present report, such two-phase flow characteristics in the channel have been analyzed, considering the bubble growth and collapse process based on the transient heat conduction in the surrounding liquid layer in a fluctuating pressure field. The calculation results agree qualitatively with the fluctuation period and the voiding dynamics in the channel obtained by the experiment. It has been confirmed that the change of void fraction distribution along the channel with time is realized by such pressure feed-back effects on the transient boiling as boiling suppression due to local pressurization and boiling promotion due to local depressurization in the channel.

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Various types of pressure oscillations occur when steam is made to condence in pool water, depending on the pool water temperature and the steam mass flux. The pressure oscillations consist of high- and low-frequency components (around 200 Hz and several Hz, respectively, for the present apparatus). When the pool water temperature is raised, the pressure oscillations cease in order of high- and low-frequency components. Based on the experimental data, high- and low-frequency components were assumed to be pressure oscillations controlled by the volume of steam bubble and the volume including steam header respectively. The occurrence thresholds of pressure oscillation were analyzed by the linear stability theory as the limit whether any infinitesimal movements of steam-water interface diverge from the equilibrium condition. In the analysis, cylindrical and spherical bubble models were compared. The calculated thresholds by these bubble shapes were roughly consistent with published experimental data, although there are slight differences between models.

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The melting process of ice-air composite materials was investigated for the case where heat was supplied from the bottom and lost from the top of the body. The process was divided into four periods, and a one-dimensional melting model was formulated accounting for water permeation and its refreezing in porous materials. The model equations were solved numerically, and the calculated results were found to be in good agreement with the experimental results obtained for the melting of compacted snow. From comparison of melting time and melting efficiency between the present predictions and the classical Stefan solutions, it was found that water permeation and its refreezing in porous materials resulted in a longer melting time and a lower melting efficiency due to the increase in a heat loss from the top of the layer.

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Natural convective heat transfer from a vertical plate having separated heating elements has been studied by numerical computation and experiment. IT has been found that convective heat transfer from the plate and the temperature distribution of unheated elements vary depending upon the ratio of thermal conductivity of convective fluid to that of the material of unheated elements, the ratio of thickness to length of unheated elements, and the length and surface temperature of heating elements. The heat transfer data are correlated by using a parameter S=B.R_λ/Gr_L^1/4, presented in this paper through the vectorial dimensional analysis, and by an observation of convective behavior visualized by Mach-Zehnder interferometer and computational results. An empirical formula has been presented to predict heat transfer coefficients of discontinuously heated plates based on the new parameter S.

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The process of ice growth that occurs in 180° curved pipes containing a water flow was investigated. Experiments were carried out under various experimental conditions in a set of pipes with an inside diameter of d = 16.5 mm - 21 mm, Reynolds numbers (based on pipe i.d.) Re = 290 - 6, 653, and temperature ratios of the freezing parameter. T^* (=Tf - Tw)/(T∞ - Tf), Tf = 0°C, Tf = cooling pipe temperature, T∞ = temperature of flowing water ) = 1.52 - 11. From visual observations of ice formation and measurements of the pressure drop between the inlet and outlet of a curved pipe, it was understood that the flow condition and temperature ratio T^* played an important role in the formation of ice in the curved pipe. The transient behaviors of ice formation with time lapse, were expressed in a relationship between nondimensional friction resistance f and Reynolds number for various temperature ratios T^*. Moreover, the critical condition of perfect ice blockage in the curved pipe was obtained from experimental correlation equations in terms of T^* and Re.

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A method was proposed to determine the snow fraction from the hydraulic gradient of a snow/water mixture flowing in a vertical pipe with a circular cross section. Experimental results showed that the mixing of snow did not affect the frictional force on the vertical pipe wall, and that the volume snow fraction C' in the pipe was nearly equal to the value C at the discharge. Based on these results, it was confirmed that C' was determined within an error of 2% by the method proposed here for the pipe diameter D corresponding to the range of Froude numbers Fr between 5 and 35 [Fr=U_m²/(|1-s|gD), U_m;flow velocity, s;density ratio of ice to water, g;gravity acceleration.

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A detailed examination was made on the behavior and unique combustion mechanisms of a refractory-lined distributed-injection type cyclone furnace protected thoroughly against heat loss. Stable combustion was maintained down to about 70% mixture strength on the lean flammable limit, when a propane-air mixture was fed at room temperature and atmospheric pressure. Excess enthalpies up to 44% above the specific enthalpy of the initial mixture appeared locally within the furnace due to the internal heat recirculation. The jets of the mixture injected tangentially into the furnace react slowly in forms of moving reactive eddies accompanied by no definite flame fronts.

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Flanged electrodes need to have two functions to determine the value of quenching distance with accuracy : The first function of flanged electrode is to start flame propagation at the center of the disk. The second is to stop and quench the flame by the disk. These functions are quite dependent on the ignition energy and the diameter of the flanged disk. The experimental results show that the value of quenching distance is essentially independent of the ignition energy but the recommendable value of the ignition energy is two or three times the minimum ignition energy, and the measuring limit of the quenching distance linearly extends with the diameter of the disk.

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The length of swirling turbulent diffusion flames of hydrogen, rising vertically from a cylindrical burner tube in free air, was measured by means of photography, and the turbulence intensity of the gas flow at the burner port was measured by LDV. The swirling intensity had a strong effect on the flame length, and an empirical equation was obtained as a function of the swirl number at the burner exit for the flame length in a fully developed turbulent region. The ratio of turbulence intensity and average gas exit velocity increased linearly with the swirl number at the burner exit, and the mixing length of the eddy diffusivity at the burner exit decreased exponentially with the swirl number.

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This paper exemplifies an attempt to clarify the characteristics of combustion noise generation of an engine. The transmission-radiation coefficients which are defined as a conversion ratio of the combustion impact to the acoustic power generated noise are examined for the transmission paths and the noise radiating surfaces of the engine. Experiments are carried out generating a single combustion impact by exploding an electric igniter with explosive or a fire cracker in the combustion chamber of a stationary engine. The calculation procedures of the transmission-radiation coefficient of the combustion noise are discussed. Using modified structures of a test engine, the characteristics of these coefficients are separately obtained for engine surfaces and for three transmission paths each, i.e. the gas excitation path, the piston-cylinder path and the piston-crankshaft path. For an air-cooled single-cylinder spark ignition engine, it was found that the combustion noise through the piston-cylinder path is most strongly radiated from the cylinder head and the cylinder block.

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A numerical method of the analysis for three-dimensional turbulent flows in cylinders of reciprocating engines with arbitrary geometry is described. A scheme of the finite volume/finite element methods is used, employing a large number of small elements of arbitrary shapes to form the cylinder. The fluid dynamic equations are expressed in integral form for each element, taking into account the deformation of the element shape according to the piston movements, and are solved in the physical space using rectangular coordinates. The conventional k-ε two-equation model is employed to describe the flow turbulence. Example calculations are presented for simple pancake-type combustion chambers having an annular intake port at either centre or asymmetric position of the cylinder head. The suction inflow direction is also changed in a couple of ways. The results show a good simulation of overall fluid movements within the engine cylinder.

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To elucidate the spray processes in a diesel engine, with special regard to the gasification and thermal decomposition of the injected fuel at an elevated air temperature, a study was carried out on a simulated two-cycle engine using a fast gas-sampling technique. The results obtained suggest that already in the period before an appreciable pressure rise in the cylinder is observed, in other words, even during the so-called ignition delay period, the injected fuel quickly gasifies and decomposes, forming a large quantity of split hydrocarbons. This phenomenon may be partly attributed to the fact that the hot burnt gas formed in the vicinity of the spray jet is sucked into the spray core, thus promoting the gasification and thermal decomposition. It is also suggested that a quantity of decomposed products which undergo turbulent mixing will accumulate in the down-stream of the fuel jet.

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Following the surface temperature variations and instantaneous heat flux in each cycle in the piston and the cylinder wall mentioned in the first report, the authors tried to verify them in the cylinder head and the suction/exhaust valve of a 4-stroke gasoline engine combustion chamber. The authors could make clear the heat flux distribution and heat loss conditions through the cylinder head and the valve surface for each stroke. In addition to the results as described in the first report, the heat loss on the entire combustion chamber wall against the quantity of supplied heat, namely, the ratio of heat transfer was known.

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The composite damping characteristics of a viscoelastic sandwich beam which is composed of a core layer of viscoelastic material and thin elastic outer layers, subjected to an axial force are investigated. As in the work of Kerwin and DiTaranto the vibratory energy dissipation is assumed to take place due to the shear deformation of the viscoelastic layer, whose shear modulus is represented as a complex one. The value of composite loss factor of the sandwich beam increases ad the axial compressive force increases, and decreases inversly as the axial tensile force increases. A large effect of axial force on the composite loss factor manifests itself with a lowering of the frequency of the sandwich beam. Experiments have been carried out with fixed ends sandwich beams subjected to axial forces .Good agreement has been found between the experimental and calculated composite loss factors to the axial forces within 30 per cent of the buckling load of the sandwich beam.

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Most of the past research works on engine speed hunting have been devoted to discriminating the divergence of a small disturbance given at an equilibrium state, resulting in a hunting frequency estimation different from that of the actual system. In the present report, a numerical simulation is given on the basis of equations of elements of the engine-governor system. As a results of simulation, a self-sustained oscillation develops in the case of speed control with subventuri pressure which has a retarded hunting frequency component compared with the speed fluctuation, while hunting disappears under suction pressure control without phase lag, as predicted in the author's previous work. Calculations show good agreement with the experimental data regarding the frequency, amplitude, and hunting speed range.

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In this paper, a new substructure synthesis method is proposed. S total structure is divided into some components (substructures). The characteristic matrices (the mass, the damping and the stiffness matrices) of reduced degrees of freedom are identified for each component theoretically or by vibration tests. The identified characteristic matrices of all components are composed to make a reduced equation of motion of the total structure. There are three methods to identify the characteristic matrices of each components, namely Guyan's reduction, an identification from the transfer function and an identification from the modal parameters. The vibration of a model structure composed of three triangular plates is calculated by substructure synthesis methods, and the results are compared with the calculated result by direct use of the finite element method (FEM). Next, the vibration of an actual crank-shaft of an internal combustion engine is calculated by the proposed method, and the result is compared with the experimental result and the calculated result by the component mode synthesis method (CMS).

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This paper presents a new method to estimate the power contribution on the grip of the tennis racket, in a multiple input system where the input sources may be coherent with one another. Using multi-dimensional spectral analysis, it is found that the biggest part of the vibration source is generated by stress cn the grip of tennis racket. This analysis is modeled as multiple input/single output system when the stress generating system of the tennis racket is very complicated .The power contribution analysis of the vibration sources and stress on the grip of the tennis racket is proved to be useful for this purpose. Finally, the overall levels for stress on the grip obtained by multi-dimensional spectral analysis are compared with those measured and calculated by the frequency response function approach method.

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A study of spectral analysis as a field of applied engineering has been recently advanced for the identification of structural dynamic characteristics, and many analysis methods to detect vibration sources are under study. In this paper, an experimental modal analysis of tennis racket was carried out at the University of Han Yang in order to obtain the modal parameter. Air type and epoxy type rackets were compared with each other to investigate the damping effect due to the existence and/or nonexistence of damping material, by examining its maximum bending moment and logarithmic decrement after impact between racket and ball. In order to clarify the dynamic behaviour of tennis racket, mode shapes corresponding to each natural frequency were obtained, and its sweet spot was determined by considering the node line at each natural frequency. The final modification was applied in a new prototype and its dynamic behaviour was checked by experimental modal analysis.

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A study is made of the coupled non-linear vibrations of a simply supported beam, with ends restrained elastically in the direction of length of beam, carrying a concentrated mass to which a spring-mass system is attached, and subjected to a transverse periodic force at an arbitrary point under the influence of gravity. The solution is derived for the steady-state vibration in the first mode resonance region with first approximation. Numerical results of the amplitude responses of the concentrated mass on the beam and the mass of the spring-mass system are presented for the principal resonance and the second and third order higherharmonic resonances, and then the occurrence of these resonances, and especially the effect of damping in the spring-mass system on the higherharmonic resonances are investigated. The stability of the steady-state solutions is also investigated for the case of no-damping.

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The third higher-harmonic response of Duffing systems excited by a periodic force including the third higher harmonics has been studied. In such a case it is expected that the higher-harmonic resonance and the principal resonance occur simultaneously. An approximate solution has been obtained by using the harmonic balance method. From the numerical results it is shown that the response curves can be classified into three types depending on the rate of the higher harmonics of external force. The results are compared with those obtained by Runge-Kutta-Gill method and a close agreement in characteristics is obtained.

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The lateral vibration of a flexible clamped-hinged pipe hanging vertically, which is parametrically excited by a time-dependent harmonic component superposed on a steady internal flow, is examined theoretically and experimentally. Using the nonlinear coupled equations for the axial fluid flow and the lateral motion of the pipe, it has been shown mainly that as the amplitude of the pipe deflection grows larger, the nonlinearity of the fluid force acting on the pipe limits the growth, resulting in a steady-state vibration. Furthermore, experiments were performed using a water-conveying pipe model. The experiments were in qualitative agreement with the theoretical ones.

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An inverted J-shaped rod is used for a street lamp-post. Assuming such a rod is constituted of a straight line and an arcuate portion, the dimensionless natural frequency and the natural vibration mode are obtained when the rod makes a transverse vibration in a plane containing the center line of the rod. The vibration equation is obtained by the use of Hamilton's Principle. Since the frequency equation is a transcendental equation, the dimensionless natural frequency calculated by a computer is shown in the drawing. Both ends of the rod are assumed to be respectively fixed-fixed, fixed-hinged, fixed-rolled or fixed-free. To eliminate the effect of rotational inertia and shearing deformation, a large slenderness ratio is given to the rod.

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The effects of vibration isolation of a new type mechanical damper on a simply supported beam and its thermal characteristics are discussed theoretically and experimentally. The damper is composed of a ball screw, a flywheel and a magnetic damper, which uses several pairs of rare-earth permanent magnets and an aluminium or copper disk. The results may be summarized as follows: (1) For larger values of moment of inertia of the flywheel, the damper approaches a snubber. (2) When the flywheel is removed, the damper acts as a mechanical dashpot having viscous damping. (3) This damper is effective even under high temperature circumstances of about 100°C.

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The structural design method of the noise control device was described in the 2nd report and it is possible to design the structure of the device by this method. But it is necessary to decide how to place the device for a noise source when it is applied. That is, an appropriate position for the noise source is required in order to obtain better noise reduction effect. Therefore, the design method for placing the device was considered through some model experiments in an anechoic room and the field, and the prediction method of the sound pressure level in the case of using the device with a barrier was investigated. The results are described in this paper.

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Sound generates when the compressed air is blown onto an open-ended face of a small pipe. The sound frequency varies with the displacement of a solid placed close to the other open-ended face of the pipe. Taking this phenomenon into consideration, a new measuring method for small displacement is examined and developed. In this paper, the relationship between the sound frequency and the displacement is experimentally obtained, and the behavior of an air jet blown onto an open-ended face of the pipe is theoretically analyzed.

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The limiting load for scoring and frictional loss of the hypoid gears were compared with those of the spur gears and the crossed helical gears. As lubricants were chosen not only the mineral oils but also synthetic oils and a new relationship between limiting load for scoring among these three kinds of gears and the frictional loss of these gears was also investigated. The limiting load for scoring differs depending on whether it is the lubricating oil with Zn-P additive or the mineral oil with EP additive, or synthetic oil. Further the relative defference between the velocities (V₁ and V₂) of tooth surfaces, which engage each other, is found one of the most important factors for determining the load carrying characteristics.

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The limiting loads for scoring of three kinds of hypoid gears, which have different dimensions and are produced by different methods, are tested and compared with each other. Then the effects of surface treatments on the limiting loads for scoring of hypoid gears were tested and compared with the results of spur gears and roller tests. From the test results, it was made clear that the contact conditions of the test surfaces affect the limiting load for scoring. Further the frictional losses of hypoid gears were measured. The results show that the coefficient of friction of hypoid gears does not change by the kind of hypoid gears, but it depends upon their sliding velocities, and their empirical formula was obtained.

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The biggest problem in use of the planetary gears is uneven load sharing of every planet gear. For solving the problem, many new designs have been offered, but there is not an exact method to confirm their results. Applying the principle that the shearing strain on the beam is constant in one side of the loaded point, a new measurement method of detecting the shearing strains on the planet gear exes is offered. The measurement by the method is done on actual planetary gears using the power circulation type test rig. As a result it is made clear that the offered measuring method of the load sharing in the planetary gears is practically useful and that the dynamic load sharing condition in actual planetary gears is considerably different from the estimated one from the static condition.

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