Substructure synthesis methods, which are applicable to the vibration analysis of large complex machine structures, are applied to acoustic analysis. At first, the frequency response spectra of sound pressure emitted from a flat rectangular steel plate in a cubical steel box are analyzed by the finite element method or by the boundary element method. Comparing the calculated results with experimental ones, their accuracy is discussed. Next, the reduced impedance method and the component mode synthesis method, which are the substructure synthesis methods previously proposed by the authors for the vibration analysis of machine structures, are applied to acoustic analysis. The sound pressure frequency response spectra calculated by these methods are quite close to experimental ones.

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Characteristic matrices are the most useful parameters for being used in the field of vibration analysis because they are physical parameters and all other kinds of parameters (modal parameters, etc.) can be calculated with them. Therefore, it is important to develop the techniques to estimate characteristic matrices from experimental data. The authors already proposed a method in the second report concerning this research. It was clear that characteristic matrices were able to be identified accurately by the method. But the method needs a lot of computational time, because the algorithm are so complex and the iterative. Then, in the present paper, the authors propose a new method by which characteristic matrices can be estimated in much shorter computational time than by the old method. The dynamic characteristics of two kinds of specimens are estimated with characteristic matrices by the proposed method in order to check the accuracy and the efficiency of the method.

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A stepped fountain-shaped rod is defined as a straight rod whose tip is symmetrically connected to two arc-shaped rods and whose sections suddenly vary stepwise at the joint part. Both parts are identical in material and have a large slenderness ratio. The purpose of this study is to obtain the natural frequency of this rod in a dimensionless form. Using Hamilton's principle, the authors set up the equation of vibration, boundary conditions, and conditions of continuity for the rod under in-plane vibration and then introduced the frequency equation thereof. This paper shows the relation between the non-dimensionalized natural frequency and its governing factors for several examples and describes the natural mode of vibration as well. It also states the authors finding that solving the frequency equation of the stepped fountain-shaped rod gives the non-dimensionalized natural frequency of a flare-shaped rod having no straight part.

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The transfer matrix method is applied to the calculations of fluid-dynamic forces acting on the walls of a one-dimensional, narrow passage when one of them is vibrating harmonically with a small amplitude. First, the fluid-dynamic coefficients in the case of a tapered passage are calculated to check the accuracy of this method. The results show a good agreement with those by theoretical solutions obtained in the first report. Second, fluid-dynamic coefficients in the case of the passage with a step are also calculated. It is found that if the cross sectional area of the upstream passage is smaller than the downstream one, both negative fluid-dynamic stiffness and negative fluid-dynamic damping can occur, and that when the effective pressure loss factor of the passage is nearly equal to unity, the area ratio of the downstream passage to the upstream one, where negative fluid-dynamic damping occurs, decreases with increasing upstream passage length.

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This paper presents a calculation method of the impact force and the vibratory response of a cylinder liner induced by the piston slap in internal combustion engines. In this method, the following dynamic conditions in the collision of the piston with the cylinder liner are assumed; (a) four points of collision at upper and lower parts of the piston, (b) employment of springs and dash-pots equivalent to the dynamic stiffness of the piston and the damping effect of the oil film. Also. the equation of motion for the coupled system of piston and cylinder liner is derived, taking account of several resonant modes of the cylinder liner to simulate accurately time histories of the impact force and the response. As a practical example, the piston slap phenomenon in an actual diesel engine is analyzed, and it is confirmed that calculated time histories of the vibratory acceleration of the cylinder liner agree well with measured data .

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The fundamental characteristics of fluid restraint of the annular region in coaxial circular cylinders were clarified. The effects of gap width, axial length, leakage from the end, etc., on the added mass coefficients and added damping coefficient of two types of circular cylinders were evaluated by both an experiment utilizing one-degree of freedom cylindrical models and analysis. The method for evaluating the vibration characteristics of a beam which has fluid restraint was investigated, and a convenient formulation for estimating the damping ratio was derived.

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A method of the master-slave type of bilateral control as one of the teleoperators is proposed in this paper to improve the operability of a micro-manipulator system for applications to genetic manipulation, micro surgery and others, which require contractive position and force. Conventional bilateral control methods can be classified from the viewpoint of a unified approach and a more general method is proposed here as the impedance reflective control method under some assumptions that the master slave dynamics are both linear. Then the stability problem is also described in the vein of the model reference adaptive system. The slave of the micro-gripper, as one of micromanipulators is made of a PMN ceramic actuator and the double link mechanism, while the master is made of a DC motor and an operating lever. The position and the force in both the master and the slave are all fed back to the control computer between them for computing control inputs for various methods. The comparison of experimental results between the conventional methods and the new method clarifies that the new method is effective for micro-manipulation.

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This paper is concerned with the characteristics of hydrostatic thrust bearings operating in the turbulent regime. Using the calculated results of the three-dimensional turbulent mean velocity between a rotating disk and a fixed wall as already proposed, the pressure distribution, the load capacity and the oil flow rate of the hydrostatic thrust bearing with a circular recess are presented. Comparing the calculated results with the experimental ones, it has been found that the characteristics of the above bearing are little influenced by the transition to turbulence of the lubricant flow in the recess, but that the transition in the land produces an extreme change to the bearing characteristics such as the load capacity and the lubricant flow rate.

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This paper presents a study on the residual stress of a carburized thin-rimmed spur gear. A heat conduction analysis of the temperature distributions in a cooling process and an elastic-plastic analysis of residual stresses by finite element method (FEM) for the carburized spur gears of various rim thicknesses are carried out. The effects of the case depth and the rim thickness on the residual stress are clarified to a considerable extent. Furthermore, the optimum case depth for the residual stress is also examined.

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The various configurations of thin-shaped bevel gears are used widely for such as main reduction gear of the helicopter and hovercraft. But, the reasonable and concise guide to design of these bevel gears is not yet obtained, since the tooth of bevel gear has complex form. The purpose of this investigation is to establish the design guide and to propose the desirable configuration for thin-shaped straight bevel gears. In this report, the desirable configuration is examined experimentally, by clearing up the effect of web and rim thicknesses, rim support condition upon the load distribution and the root stress distribution along the tooth trace. The results are summarized as follows. (1) The crowning of tooth trace exerts a significant effect on the root stress distribution of thin-shaped bevel gear. (2) As the desirabe configuration of thin-shaped bevel gear, it is to be recommended from viewpoint of root stress that the rim is supported at the heel side of tooth trace.

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A crossed helical gear is a hypoidal gear in which the pitch surface is a cylinder. Therefore, a crossed helical gear should be treated as a special case of the hypoid gear. From this point of view, this study visualizes the present problem of crossed helical gears, and considers the possibility of meshing with line contact. In this first paper, the relationships of the third-order surface contact for the tooth surface of hypoid gear are arranged and next going to use for the crossed helical gears. Moreover, the limit normal curvature and limit geodesic torsion of their tooth surfaces are described.

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In order to decide the optimum tooth form of die-wheel, computer simulations of a roll-finishing by a die-wheel with profile and longitudinal modifications were carried out. It was revealed that modifications of a die-wheel should be determined in consideration of a tooth form roll-finished by a die-wheel without any modifications, i.e. a tooth form of die-wheel should be hollowed out at the position corresponds to the hollowed part of a roll-finished tooth form and should be projected at the position corresponds to the projected part of a roll-finished tooth form. Furthermore, experiments of roll-finishing with a modified die-wheel were carried out. It is found that profile and longitudinal modifications of die-wheel determined by a manner mentioned above is very effective. And a fairly good roll-finished tooth form can be obtained by using such a die-wheel, provided that an interference between the tooth tip of die-wheel and the tooth root of work-gear is prevented by a tip relief of die-wheel.,

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Recently, smooth tooth surfaces have been obtained by hobbing with accurate finish hobs, resulting in the production of as-hobbed gears for practical use. However, further improvement of the gear accuracy in gear hobbing is needed in order to obtain high load-carrying capacity. In this study, the relation between the hob accuracy and the hobbed gear accuracy is investigated by calculating the tooth profile errors of gears caused by the various hob errors. From the analytical comparison of both hob and gear accuracy, the following are summarized. (1) The tooth profile of hobbed gears are not always highly accurate, even if they are hobbed with a highly accurate hob. (2) For the improvement of the gear accuracy, it is necessary not only to reduce the tooth profile error of hob, the lead variation of hob and the eccentricity in hob setting, but also to consider the hob error patterns.

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In order to develop CBN finishing hobs, the cutting performance of the sintered CBN tool is valued based on the intermittent turning tests. The sintered CBN cutting tool is very hard but fragile. The cutting edge of hob is liable to break, because the cutting mechanism on the hobbing is a kind of intermittent cutting. chamfering of the cutting edge is effective as a prevention against chipping. In this paper, first, the optimum form and size of chamfer is found out based on cutting tests. Secondly, the tool wear and the surface roughness are investigated under various cutting conditions. In spite of the cutting by CBN tools, a dead metal occurs on the cutting edge. It acts as built up edge and roughes the cutting surface.

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Tool life and surface roughness on finish hobbing With CBN hobs are valued, based on plain milling, which is quite similar to hobbing. Two dimensional cutting and V-groove cutting with CBN fly tools are carried out on the milling machine. The finished surface is fine and tool wear is relatively small in the cutting of a hard work piece at high speed, because a dead metal that is similar to built up edge disappears from the cutting edge. In this condition, the form and size of finished surface roughness correspond to those of tool flank face roughness.

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Carbide hobbing have been used widely because of the manufacturing the carbide hobbing machine and improvement in manufacturing the carbide hob. Nowadays anealed gear blanks which often used in mass production can be carbide-hobbed without trouble. And in addition to that, it becomes to be possible to hob the heat treated gear blanks or hardly to be cut gear blanks which were impossible to be cut with the high speed steel hob till now. However, in the case of carbide hobbing for the heat treated gear blanks or hard-cutted, the damage of chipping or thermal crack will occur before the life (increase of flank wear) is completed because of unsuitable cutting conditions. In this paper, the authors are investigated the cause and countermeasure of damage, after classified the shape of damage on cutting blade in carbide hobbing systematically.

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This paper presents an analysis of a new noncontacting face seal with circumferential pumping grooves and shrouded Rayleigh-steps. The hydrodynamic lubricating film is maintained under rotation due to the Rayleigh-steps. If the low pressure side of the seal is filled with a fluid, the fluid can be pumped into the high pressure side through the circumferential pumping grooves until the shaft speed reaches a limit value. The experimental result confirms the theoretical prediction for the lubricating and sealing performances. Due to the high pumping ability in addition to the high stiffness of its hydrodynamic film, the seal can operate without wear and leakage for a high pressure fluid.

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When a coiled spring whose both ends are kept parallel is gradually compressed, it generates a lateral deflection even before it is compressed to the critical load. This may result in undesired contact with other mechanical members. In this paper, compression tests were carried out and quantities of lateral deflection and shift of Tip-Contact Points (T.C.P.) were measured. It was made clear that the quantity of lateral deflection and shift of Tip-Contact Point caused by compression depend on the difference of spring indices. A model which illustrates this result successfully was introduced.

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The relationship between the Brinell hardness HB and the flow stress σ_ε of sintered porous metals is examined considering the ratio d/D ; the diameter of indentation to that of the indenter. When d/D=0.4, at which the Brinell hardness test is usually done, the ratio c=HB/σ_ε varies from 2 to 3 with a relative density ρ of 0.70 to 0.97. However, when d/D=0.7 to 0.9, the ratio c is almost constant at 2.5 to 2.8 without influence of the relative density. Therefore, the flow stress of porous metals can be estimated from the Brinell hardness test at a ratio d/D of 0.7 to 0.9.

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Piercing of brittle sheets, difficult by conventional shearing or drilling, is attempted using a new manufacturing process utilizing the impact compression of a viscoelastic pressure medium, recently proposed by the authors. The impact pressure is analysed with the linear viscoelastic model to determine optimum working conditions. Under a specific condition the process has succeeded in piercing a circular hole through various brittle materials : for example, inorganic glass, alumina ceramic and glassy graphite composite. The hole formation process in a glass sheet is examined experimentally and theoretically.

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In designing effective electromagnetic forming systems, more knowledge on the mutual induction between forming coils and workpieces and on resulting magnetic force are required. Coupling coefficient k_c between a spiral flat work coil of 15 turns and different specimens of circular plates in an electromagnetic forming machine is evaluated based on the measurement of effective coil inductance. k_c at different circuit frequencies is obtained and shown as a function of the ratio of the thickness of the specimen to the skin depth, h₀/δ_s. If h₀/δ_s is greater than 0.5, k_c is about 0.92. Impulses of an electromagnetic force defined by the time integral of the force are measured by accelerating specimens. The impulse depends on the conductivity and the thickness of the specimen. The surface density of a specimen also plays a significant role when kinematic energy gained by the specimen is concerned. It is shown that a frequency range to maximize the impulse at constant initial energy stored in a capacitor bank exists between h₀/δ_s=0.3∼0.8.

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This paper deals with an automated manufacturing system which consists of same machines located along a loop type of conveyor with a loading-unloading station. The system is described by a Markov chain model and the production rate is analytically derived. The relation between the production rate and the arrival rate of parts and the average processing time of the machines is studied by the numerical results. Furthermore, the optimal control problem of dispath of parts into the system is formulated as a Markov decision process. The properties of optimal control are considered and the production rate under the optimal control is compared with that under non-control.

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A multi-job cyclic scheduling problem for an automated flow-type manufacturing system was analyzed, Flow of jobs in the system was represented as a network. Using the network representation, the job output interval in a steady state was obtained. In the cyclic scheduling problem, an optimum schedule is a non-idle schedule, where a bottleneck machine produces jobs without idle time in a steady state. A lower bound on the buffer capacity and a scheduling method were obtained to construct a non-idle schedule.

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The problem of plant and process layout is one of the most significant and involved engineering problems. The digital computer is general]y employed to optimize the arrangement order for the products. This paper describes a new method for solving the layout problem. We use cofactors of graph theory and incident matrix to solve the problem efficiently. The last section of this paper deals with several examples of layout problems.

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This paper is concerned with the design of free-form surfaces using the B-spline in geometric modelling. Firstly, the algorithm for finding intersection lines between two free-form surfaces is discussed. The intersection lines are computed using the Newton-Raphson method between two subdivided Bezier surface patches. The performance of the proposed algorithm is compared with that of the algorithm to compute the intersection lines between planar polygons. Secondly, the combination operation of objects with free-form surfaces is discussed, and it is performed by transforming the intersection lines on the algorithm into consecutive ones, and by creating new boundary loops in the parameter space of each surface. As an example illustrating the effectiveness, a turbine blade and its boss are presented by creating the combination operation and by automatically transforming them into the corresponding boundary elements. The displacement of the turbine blade and its boss are calculated using the Boundary Element Method when the centrifugal force applies to them.

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