The present paper reviews the current research activities of the finite element methods for the incompressible viscous fluid flow. The status of the finite element flow analysis is discussed in comparison with the finite difference methods through the surveillance of the latest literature. The focus is placed upon the treatments of the incompressibility constraint and the non-linear convection term, both of which pose inherent difflculties in applying the finite element methods to the flow problems. Some fresh computational concepts which are intended to improve the efflciency and robustness are also scrutinized.

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This paper reviews recent progress in metal forming tribology. Tribo-testing methods are chronologically listed, and the correlation among various indices obtained by a compression-twist type tribometer is examined in detail. Results show that clear correlations exist between indices with similar physical meanings. Various factors influencing lubrication mechanisms are discussed, including plastic roughening and its effect on limit strain in the forming limit diagram, the application of the Reynolds equation to rolling, extrusion and drawing lubrication, elasto-hydrodynamic lubrication, micro-plasto-hydrodynamic lubrication, the galling mechanism and temperature analysis. Various lubricants and coating techniques for workpieces are briefly mentioned. Surface treatment techniques for tools such as TD process and Si₃N₄ ceramic provide excellent galling and wear resistance.

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Thermal fatigue tests were performed using straight pipe specimens subjected to cyclic thermal shocks of liquid sodium, and crack growth behaviors were estimated using striation patterns observed clearly on any crack surface. Crack growth rate under cyclic thermal strain reaches the maximum at one depth, and after that it decreases gradually with crack depth. The peak location of crack growth rate becomes deeper by superposition of constant primary stress. Parallel cracks co-existing in the neighborhood move the peak to shallower location and decrease the maximum crack growth rate. The equivalent stress intensity factor range calculated by Walker's formula is successfully applied to the case of negative stress ratio. Fatigue crack growth rate under cyclic thermal strain agreed well with that under the constant temperature equal to the maximum value in the thermal cycle. Simplified methods for calculating the stress intensity factor and the crack interference factor have been developed. Crack growth behavior under thermal fatigue could be well predicted using numerical analysis results.

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This paper is concerned with mixed-mode I-and mode II fracture criterion in the case where stable crack growth occurs before unstable fracture. Finite element analyses and tensile tests were carried out on thin sheet specimens of 2024-T3 aluminum alloy having a center crack inclined to the tensile loading axis. The specimen width and the angle between the center crack and the tensile loading axis were changed over a wide range. It was found that stable crack initiation follows approximately the criterion of J_I+αJ_II=(J_i)_I, where α is a constant. The direction of stable crack initiation was perpendicular to the tensile loading axis. The net stress at the maximum load was found to be nearly equal to the yield stress of the material tested.

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For the study of fracture criteria, adhesive tensile strengths (σ_Y) of scarf joints with a scarf angle of 30° and butt joints bonded by a brittle epoxy adhesive A and a ductile epoxy adhesive B have been measured at adhesive layer thicknesses (h) from 0.05 to 5.0mm, and three-dimensional elastic finite element analyses have been performed. σ_Y of each joint decreased with an increasing value of h. A brittle fracture occurred on the scarf and butt joints bonded by adhesive A and the butt joints bonded by adhesive B. The fracture of scarf joints A and B satisfied a maximum principal stress criterion and the von Mises criterion, respectively. Gradients of σ_Y-h curves for butt joints A and B were greater than those predicted from the results of stress analyses. The location of fracture initiation and fracture modes of adhesive layers observed with and optical microscope agreed with those expected from the results of experiments and stress analyses.

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The strength evaluation of adhesively bonded scarf joints having adherends of the same or dissimilar metal was investigated both analytically and experimentally in order to accomplish a way of strength designing of adhesively bonded materials. The strain and stress distributions in the adhesively bonded joints were analyzed by means of the finite element method. The strengths were calculated on the basis of our criterion. The effect of the mechanical properties of adherends on the joint strength was examined. The deformation state and fracture mode of the joints having adherends of the same metal. It was predicted that the smaller the difference in the Young's moduli between the adherends, the greater the joint strength was.

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In plastic goods which have rib/boss structures, partial deformation due to thermal shrinkage, called a "sink-mark" is formed. In this study, to make clear the characteristics of the sink-mark growth, and experimental and analytical approach is made. By using a T-shaped experimental mold cavity, the depths of the sink-marks are compared with both shape parameters and processing parameters. As a result, the pressure on the packing stage and the rib thickness are the most effective to cause the sink-mark growth. Also, and analytical method for evaluating the sinkmark in rib structures is proposed. In the analysis model, when the shape of the cross section does not change in the longitudinal direction, 2-dimensional transient thermal analysis by FDM is used. At the same time, by assuming the fiber elements, and by treating the model as a thermoelastic-plastic strain problem, the growth of the sink-mark in the die is theoretically evaluated. In consideration of the P-V-T characteristics of the resin, the analytical results are well-fitted to the experimental data.

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In the turbulent wake behind and upstream cylinder in a uniform flow, the downstream cylinder was set in the form of an intersection with the upstream cylinder. It was found that the acoustic radiation from the two circular cylinders forming an intersection was far smaller than that of a single cylinder. The variation of the acoustic radiation was measured by varying the intersectional angle of the two cylinders, the point of mutual contact and the angle between the downstream cylinder and the uniform flow. Moreover, measurements were made on (1) the mean and fluctuating surface pressure distributions on both cylinders, and (2) the mean velocity profiles and fluctuating velocity distributions in the turbulent wake behind the upstream cylinder. The flow patterns were verified by oil-film and smoke-wire flow visualization. Then, the relationship between the flow and the noise generation was studied.

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Nitrogen gas is set to discharge from a small circular hole located at the end wall of a shock tube at about 3-5 ms before the shock wave arrives and undergoes reflection. Interacting with the jet, the reflected shock wave changes its shape from a normal shock wave to a hemispherical one. We observed the phenomenon by the use of a schlieren system, time counters and pressure gauges. We calculated the pressure and the temperature behind the apex of the hemisperical reflected shock wave by using its distance-time relations, differentiation of cubic natural smoothing spline functions, and Rankine-Hugoniot equations. In this paper, we want to prove that the method that we proposed in a previous work is a reasonable and available one. The results are as follows. (1) From pressure profiles, we cold show that the proposed method, in fact, was a reasonable and available one. (2) When an unstable hemispherical reflected shock wave reconverts to a stable, normal shock wave, it generates some expansion waves, which cause a temporary pressure-drop (about 120μs) in the Kistler transducer on the side wall after the passing of the reflected shock wave. (3) The calculated results using the proposed method are supported by the experimental facts of (2), and the facts show that a strong inverse flow is poaduced by the interaction between the reflected shock wave and the jet behind the reflected shock wave.

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An experimental and theoretical study is presented for the interfacial instability of magnetic fluids in rectangular containers subject to magnetic fields. Experiments were performed to determine the critical field intensity for incipient instability and to observe the growth of instability waves. Magnetic fluids used in the experiments were water-base ferricolloid W-35 and its dilution with distilled water. It was found that interfacial instability appeared when the field intensity exceeded the threshold value and grew in amplitude with the field intensity. It was also found that the wave number for the instability depended upon the field intensity and the dimensions of the container. The possible equilibrium configuration was analyze theoretically by minimizing the total energy. The experimental results can be explained well by the theoretical analysis.

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Heat transfer experiments for an asymmetric confined jet have been made for several nozzle locations of different eccentricities. The Craya-Curtet number, usually regarded as a similitude parameter for the flow pattern of an axisymmetric confined jet, has been found to be a useful parameter for correlating the measured heat transfer data. Therefore, it can be regarded to be a similitude parameter for heat transfer in the studied type of separating and reattaching flow. Measured values of the maximum Nusselt number and their positions at different peripheral angles θ have been plotted against the space L between the tube wall and the nozzle corresponding to each peripheral angle. Form this examination, a possibly existing secondary flow in a cross section has been suggested to affect the heat transfer characteristics of an asymmetric confined jet only slightly. Lastly, it has been found that slightly better overall heat transfer can be obtained with a larger eccentricity of nozzle location.

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An analytical and experimental study has been performed to investigate the heat transfer characteristics of the unsteady natural convection of heat-generating fluids in a horizontal cylinder. Experiments were carried out with dilute electrolyte which was heated by passing an alternating current through it. The rate of heat generation was constant and uniform, buy changed stepwise with time. The temperature profiles and the heat transfer coefficients were determined with an interferometer. The governing differential equations were solved numerically to simulate the velocity and temperature distributions. From these results, the maximum temperature, the maximum value of the stream function and mean Nusselt number were correlated in terms of the Rayleigh number and the Fourier number. The transient period, which is the time interval needed to get to a steady state, was also correlated to the Rayleigh number.

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Forty-four vapor pressures of Refrigerant 152a (CH₃CHF₂: 1, 1-difluoroethane) between 273 K and 386 K have been measured in the range of pressures from 0.26 MPa to 4.48 MPa. Ten saturated liquid densities and eleven saturated vapor densities near the critical point have also been measure in the range of temperatures from 370 K to the critical temperature which corresponds to a density variation of 153 kg·m^-3 to 635 kg·m^-3. The experimental uncertainties of temperature, pressure and density measurements have been estimated within 10 mK, 0, 8 kPa and 0.55%, respectively. On the basis of these results, the critical temperature, critical pressure and critical density of R 152a have been determined to be 386.44K, 4.5198 MPa and 368 kg·m^-3, respectively, in consideration of the meniscus disappearing level as well as the intensity of the critical opalescence. In addition, the correlation of vapor pressure and the vapor liquid coexistence curve have also been proposed.

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This paper describes and experimental study on the relationship between fluctuating velocity in mufflers and flow induced noise for the expansion cavity type muffler and the perforated straight-through pipe type muffler. The visualization of internal flow and the measurement of fluctuating velocity in a muffler were performed using the smoke-wire method and a hot-wire velocimeter. From these experiments, the flow pattern and the distribution of the fluctuating velocity were able to be clearly shown for each type of muffler. The correlation between the fluctuating velocity at each point in the muffler and the flow induced noise which radiated from the open end was also studied by calculating the coherence function between them. It was seen that the flow induced noise was closely correlated with the fluctuating velocity of the internal flow, especially in the ranges of tail pipe and/or cavity resonance frequencies.

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In this paper, we report that the change in the vibration characteristics of a tennis racket due to structural modifications were identified. The modifications consisted of a change in the material of the frame and the attachment of a damping material to the grip. Due to these structural modifications the sweet spot was changed. The most effective modal parameter for the extension of the sweet spot was stiffness as determined by sensitivity analysis. Hence, the change of the sweet spot was predicted by changes in stiffness. There was good agreement between the predicted and measured values of the sweet spot.

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A newly designed diagnostic robot, Mark II, basically consisting of three modules with a joint between modules has capabilities of straight and spiral movement along the outside of pipelines, and of freely passing over obstacles such as flanges, T-joints and other plant equipment by sensing and recognizing obstacles in from of it; and of controlling its attitude automatically. By calculating the position and orientation of the robot using a transformation matrix, a method of motion control in the passing of T-joints is shown. A method of compensating for the torque generated by gravitational forces is also applied for each module, independently, to keep the holding torque constant, which leads to less vibrations in movement and, hence, yields better diagnostic results. The Mark II equipped with diagnosis sensors can identify the location and depth of flaws on the surface by inspecting pipelines in the spiral-moving mode. The Mark II also has intelligent abilities, such as routing the most efficient path for inspection in plants, provided a plant map has been previously furnished.

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Operational fatigue tests of nitrided gears were performed using a power circulating gear testing machine, in order to elucidate the failure mode, load carrying capacity and relation between tooth profile change and dynamic performance in the fatigue process of a nitrided aluminium-chromium molybdenum steel gear. The failure mode was a tooth breakage by bending fatigue at the tooth fillet under a higher applied load and tooth breakage due to spalling near the pitch point under a lower applied load. The surface durability of the nitrided gear was within the range of that of case-hardened gears. The changes of tooth root strain, noise and vibration during the fatigue process were slight, since the change of tooth profile deterioration was insignificant.

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The influence of tip interference on scoring load capacity was studied using gears having tooth profile wear due to scoring on the approach side. The results were compared with those obtained with gears having no profile wear from the viewpoints of scoring load and scoring temperature, taking the lubrication state on the working flank into consideration. The tip interference on the approach side should be reduced because, unlike on the recess side, it diminishes the scoring load capacity. In the mixed lubrication state, the working flank bulk temperature is suitable as an index for calculating the scoring load capacity of a spur gear pair. The scoring temperature on the cylinder just before seizure in two-cylinder tests, provided that the specific sliding and the sliding velocity at the end of gear meshing are taken into account.

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From observations of the metallic structure at the seized portion in two-roller tests and the calculation of the stress resulting from the combination of the Hertzian stress field, the frictional force field and the thermal stress field on the contacting rollers, it was found that the seized portion on the rollers adhered to the surface of the lower roller rotating at high speeds and that its hardness was considerable high; and that the portion could be easily separated from the surface of the lower roller. The mechanism of adhesion can be considered as follows: as the shearing stress (Hertzian stress + frictional force + thermal stress) acting on the upper roller is larger than that on the lower roller, the portion of the upper roller, at which the distribution of the hardness below the surface of the roller is minimum, is sheared due to the shearing stress, and adheres to the surface of the lower roller.

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The authors introduced a new method (element removal method) for calculating the profiles of the tools (hob, form grinding wheel, etc.) used for finishing gears with an arbitrary tooth profile. Because this method simulates exactly the metal removing process in the gear tooth profile generation, it is possible to calculate the generated tooth profile when interference occurs between the cutting edge and the finished tooth profile. Using this method, the authors calculated the exact wheel profile which can produce and involute tooth profile with a tip relief at a transverse section of the involute helical gears. The wheel profile was generated by a single point diamond dresser using a universal NC milling machine with an attachment made by the authors. The tooth flank and root of test gears were ground at the same time to prevent a step (notch), which is apt to be produced at the boundary of ground and unground surfaces. The accuracy of the form ground test gears was in the zero class of JIS and the surface roughness was in the range of 0.5 to 1.0 μm R_max.

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The influence of tool geomtry on hole deviation is investigated using four types of deep hole drilling tools, i.e. a normal type gundrill, a standard type BTA tool, a double-edge gundrill and a multi-edge BTA tool. Two types of workpieces are uned to make their influence clear: one has an unsymmetric wall thickness on the right or left side and the other is made up of two materials where the hardness of the bonded plate is lower than that of the base metal. Experimental and theoretical results show that balanced cutting forces on the tool head contribute to decreased hole deviation. However, to some extent, an unbalanced condition of forces generates a slightly oversized hole.

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