This paper presents numerical results on chaotic vibrations of a shallow cylindrical shell-panel under harmonic lateral excitation. The shell with a rectangular boundary is simply supported for deflection and the shell is constrained elastically in both in-plane directions. The effects of bi-axial in-plane elastic constraint on the chaotic behaviors of the shell are focused on. Using the Donnell-Mushtari-Vlasov type equation modified with an inertia force, the basic equation is reduced to nonlinear differential equation of a multiple-degree-of-freedom system by the Galerkin procedure. To estimate regions of the chaos, first, nonlinear responses of steady state vibration are calculated by the harmonic balance method. Next, time progresses of the chaotic response are obtained numerically by the Runge-Kutta-Gill method. The chaotic responses due to dynamic snap-through are examined by Fourier spectrum, Poincare projection and Lyapunov exponent. Contribution of multiple modes of vibration to the chaos is examined carefully by the Lyapunov dimension. The main results can be summarized as follows. Loosening the in-plane constraint perpendicularly along the curved edges and tightening the in-plane constraint along the straight edges, chaotic motion is restricted with less number of modes of vibration.

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In rotor systems, if the gyroscopic moment is small, a forward natural frequency and a backward natural frequency almost satisfy a condition of 1 : (-1) internal resonance. In such systems, the critical speeds of the forward and the backward subharmonic resonances of order 1/2 and the combination resonance are close in the vicinity of twice the major critical speed and internal resonance phenomena may appear. This study clarifies dynamical characteristics of nonlinear phenomena due to internal resonance, such as steady-state oscillations, almost periodic motions, bifurcation phenomena, and two kinds of chaotic vibrations, at the rotational speed of twice the major critical speed.

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The incremental transfer stiffness coefficient method was developed, in the previous report, in order to analyze the periodic steady-state vibrations of a large-scale structure having locally strong nonlinear elements. By the incremental transfer stiffness coefficient method, the computation cost can be reduced remarkably from the iterative computation process of approximate solution. In this report, an algorithm based on the present method is formulated to analyze the longitudinal, flexural and torsional coupled vibration of the three dimensional tree structure supported by the nonlinear base support elements. In addition, the method of stability analysis using reduction model is applied to the periodic solution obtained for the three dimensional tree structure. The validity of the incremental transfer stiffness coefficient method and the method of stability analysis using reduction model for three dimensional tree structures is confirmed by the numerical computational results.

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Many nonlinear characteristics are seen in a secondary system. The collision characteristic, which is seen in mechanical supports and joints, is one of nonlinear characteristics. In this paper, a simplified estimation method of the first excursion probability of a secondary system with gap, subjected to carthquake excitations, is proposed. This method is based on the equivalent linearization method. By using this method, the effect of gap on the first excursion probability is examined. In order to examine the effectiveness of the proposed method, the obtained results are compared with those obtained by the simulation method. It is found that the first excursion probability is independent of the natural period when the tolerance level is normalized by the maximum response of the scondary system without gap and the first excursion probability can be simply estimated by using the maximum response of the nonlinear secondary system.

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After the Hanshin-Awaji Earthquake Disaster, the number of earthquake isolated buildings is increasing with a great dominance. Even though most of the base isolated buildings or structures are built on laminated rubber bearings to give them certain natural periods, this situation also encourages structural engineers to research and develop non-rubber type isolation systems such as linear bearing isolators and friction pendulum systems. When using non-rubber type isolation systems in the open air circumstances, some have pointed out that long term durability of the systems must have been taken into account and it might have been very difficult to maintain the coefficient of friction. In this study, dynamic motion of the isolated structure model with 4 of Friction Pendulum Bearing (FPB) systems is investigated, especially in in-plane mode, considering a variance of coefficient of friction of each system, a distribution of the mass of superstructures and so on. A preliminary analysis of this study is presented in this report.

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There are three basic finite element formulations which are used in the dynamics of flexible beams. These are the floating frame of reference approach, the finite segment method and the large rotation vector approach. Recently, the absolute nodal coordinate formulation was proposed by A. A. Shabana et al. In this formulation, elastic forces are lead by approximating the slope of the arbitrary point on the neutral axis of the beam in terms of the slope of the simple support axis of the beam. In this paper, we propose the mean axis of the planar Bernoulli-Euler beam for the absolute nodal coordinate approach. The origin and the orientation of this axis are selected so as to minimize the total deformation of the concerned beam. And the selected axis can be simply described by the nodal coordinates of the beam element. Using the mean axis instead of the simple support axis, the elastic forces of the beam element may be more precisely calculated. Finally, we show numerical examples to demonstrate effectiveness of this approach.

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The superconducting magnetic bearings (SMBs) have been studied for the application to flyweel energy storage systems, where these SMBs are incorporated to support total weight of rotors without contacting them. In designing these SMBs, the levitation force should be reasonably predicted. To predict this force, practical analytical method should be developed. This paper deals with the analysis of levitation force characteristics for practicable radial-type SMBs with multiple superconducting bulks. It was found that. the attenuation of the levitation force due to flux creep and hysteresis of a superconductor assembly, etc. were well explained. This analysis used 'ideal bulk with equivalent thickness' model would be effectively applied to designing of an actual SMBs. We also show the distribution of supercurrent density in radial-type SMB.

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Various methods for detecting damages in structures are already proposed. Some of them use dynamical response of structure, FRFs, mode shapes, natural frequencies and so on. In almost of these techniques dynamical response is obtained from vibration testing of structures out of operation or the existence of measured dynamical response is assumed. However, in operation real-time methods for detecting damages are desired. In this paper, we propose a method for measuring FRFs under steady operational condition and perform two fundamental experiments as the first report of our researches on the development of real-time structural health monitoring. The fundamental concept of the method is measuring noise caused by steady operation at first, and then subtracting the noise from response to testing forces, Note here that the phase of measured noise and that of included in response are different. Simply subtraction is inexact. In the proposed method, we mesure two time series data of noise and obtain the relation between time difference and phase difference. Then we predict noise included in response by using this relation and subtract predicted noise from response.

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This paper deals with the experimental study of flow-induced vibration of multiple flexible disks rotating in a confined fluid subjeted to swirling fluid flow. The experiment is carried out to investigate the characteristics of the unstable vibration and the effect of the number of the rotating disk on the critical speed at which the flow-induced vibration occurs. Following major results are obtained. (1) Critical speed of the system which has more than two disks is much lower than that of one disk system. (2) Flow-induced vibration occurs as a travelling-wave (0, 3) mode with three nodal diameters. (3) The travelling speed ratio of the system which has more than two disks is larger than that of the one disk system. And the ratio is independent of the disk rotational speed. (4) Amplitude of the vibrational displacement of the extreme rotating disk is much larger than that of intermediate rotating disk for the system which has more than three disks.

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This paper investigates the effect of suppressing the vibration of a spinning disk/spindle system by applying a squeeze film damping to a commercially available HDD with five platters. The out-of-plane and in-plane vibrations of the top disk were measured with and without a squeeze air bearing and illustrated by the Campbell diagram. When the squeeze air bearing plate with angular length of 180° and radial length of 20 mm was used at 120 μm clearance, the largest resonance amplitude of the out-of-plane disk vibration decreases to less than 40%. The disk flutter caused by the surrounding air flow could be significantly suppressed. It was also found that the suppressing effect of the out-of-plane vibration can proportionally decrease the in-plane vibration.

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All degrees of freedom (especially wheel-axle rotation), Kalker's program 'FASTSIM' which considers spin creepage, and variation of contact ellipse were newly introduced for curving simulation of a roller-type pendulum vehicle. Digital simulations of curving for a representative example were made and the influence of newly introduced factors were studied. It was shown that wheel-axle rotation decreased lateral wheel-rail force by 8% (for steady value without track irregularity), by 5% (for maximum value with track irregularity) and changed wheel load by 1% (for steady value), by 5% (for minimum value). It was also shown that spin creepage increased lateral wheel-rail force by 19% (for steady value), by 7% (for maximum value), and variation of contact ellipse decreased lateral wheel-rail force by 8% (for steady value), by 4% (for maximum value). Spin creepage and variation of contact ellipse had little effect on wheel load.

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Magnetorheological (MR) fluid is a functional material that responds to an applied magnetic field with a change in rheological behavior. The essential characteristic of this fluid is its ability to reversibly change from free-flowing, linear viscous liquid to semi-solid, which has controllable yield strength in milliseconds when exposed to a magnetic field. The MR fluid can, therefore, play an important role in the controllable vibration damper. In this paper, based on the experimental data, an improved mechanical model for MR damper is developed and confirmed by one degree of freedom vibration system. The model consists of a hysteresis part and a variable viscous damper proportional to the added voltage. In addition, numerical simulation are performed when the MR damper is used in the ground vehicles as a part of suspension system, while the MR damper is considered in two-stage state and on-off state. The results show that, as a controllable damper, MR damper is very effective for vibration isolation of the vehicle body acceleration and suspension travel, both in on-off state and two-stage state.

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This paper deals with the effect of a gyroscopic damper (GD) on bridge deck flutter considering nonlinear characteristics of the gyroscopic moment of the GD. The GD has been reported to have a major effect in suppressing bridge deck flutter through a linear analysis in which the GD motion is assumed to be sufficiently small. However, since the GD produces a large oscillation against the slight amplitude of deck torsional motion, the control effect of GD actually decreases on deck torsional motion as the GD amplitude increases. In this paper, applying the method of equivalent linearization, we proposed the index parameters that indicate the effect of the GD with large oscillation. The validity of these parameters was confirmed by the nonlinear time response analysis of a 2-D bridge deck model with the GD which self-excited aerodynamic forces and gusty wind forces act on.

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A basic noise control system applicable to a moving evaluation point was proposed in the previous report, and its effectiveness was examined numerically and experimentally. Although the results showed that the proposed system is effective, it can only handle the case of slow evaluation point velocity. This restriction seemed to be due to the slow convergent speed of the adaptive filter. In this paper the cause of restriction is examined in detail, and an advanced control system is proposed. The features of the proposed system are as follows : 1) Improved feedback controller where main filter is less affected by the movement of the evaluation point. 2) Introduction of IIR filter together with the learning identification method to the error path identifier. The new system is examined both in simulation and experiment and shows great improvement compared with the basic model.

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This paper deals with active noise control for minimizing the acoustic power radiated from a vibrating planar structure. ' First, using a set of secondary sources, the optimal feedforward control law for minimizing the total acoustic power is derived. Under the optimal control, control power at each secondary source is found to be zero, and hence the total acoustic power control is also zero. Acoustic intensity flow pattern also changes from sink or source phenomenon to a saddle point or vortex flow pattern in the vicinity of the optimal control sources. Furthermore, the relevance between the control location and the control effect for suppressing the total acoustic power is clarified. Finally, the optimal location for the control sources is presented using a comprehensive acoustic intensity distribution.

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A large number of home care equipment has been developed to support the independent living and the care of the elderly person. Almost equipments have a alarm to call a care person or to sound a warning in case of emergency. Physiological characteristics of human will be getting weaker with age. The alarm sound must be designed with considering a hearing loss of the elderly person. Since the alarm is usually used indoor, it is also necessary to evaluate the relation between the basic characteristic of sound and the room layout. In this work, we investigated the alarm sound of the home care equipment based on both the age-related hearing characteristic of the elderly person and the propagation property of indoor sound. As a result, it was clear that the hearing characteristic of the elderly person is highly sensitive to the sound which has the frequency from 700 Hz to 1 kHz. In addition, the indoor absorption ratio of the sound is the smallest when the frequency is 1 kHz. Therefore, the frequency of 1 kHz is good for the alarm sound of the home care equipment. The flow chart to design the alarm sound of home care equipment was proposed taking the age-related auditory sense into account.

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This paper is concerned with a human interface between a human operator for decision-making of obstacle avoidance and a crane transferring an object. Overhead traveling cranes are usually manipulated by human operator in practical industries. The transfer object can be freely moved in the three dimensional space by human operator for obstacle avoidance. Although manipulation for the moving direction of crane is simple, the crane's operation without sway of a load is difficult for unskilled operators, and therefore the oscillation of the residual vibration is generated after the transfer object is reached at a goal point. A semiautomatic control system is proposed in terms of a diffusion equation strategy in order to check and revise the reference trajectory directed by human operator for obstacle avoidance. Moreover, this system includes an optimal servo controller to suppress the oscillation of the transfer object and to control the cart velocity. The usefulness of the proposed method is demonstrated through experimental studies.

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Control methodology for the platooning of automatic driving vehicles is presented in this paper. The currently proposed controller for the platooning has focused on keeping inter-vehicle distance, where the platooning is conducted by control of each vehicle. But this strategy has difficulty of conducting transient processes, such as merging and separating in dense traffic condition. As solution to the above problem, platoonlevel control is proposed to be placed over vehicle-level control. A hierarchical control architecture including the platoon-level control is proposed, and a control procedure for conducting the transient processes of merging and separating is concretely described. The proposed platooning controller is evaluated by simulation and clarified to be contributive to higher traffic throughput, lower fuel consumption and better ride comfort.

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Rotational speed control of a hydraulic motor with a large inertia load has issues on stability and sometimes falls into unstable. In this paper, the discrete-time sliding mode control (SMC) is applied to rotational speed control of a hydraulic motor for improving its robustness. Modeling of the control components and design of the sliding surface (switching line) in the state space are discussed. Furthermore, one of the means attenuating chattering due to SMC is presented. The control characteristics is evaluated by a testing apparatus which consists of the hydraulic motor of 28 cm³/ rev coupled to the fly-wheel with large inertia load of 0.88 kg·m². The results of a theoretical and experimental study of SMC show several benefits such as short settling time and low sensitivity to disturbances and system parameter variations.

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In recent years, the new vibration monitoring methods using distributed continuous sensors have been actively developed in the field of smart sensors and actuators. PVDF film sensors have been mainly used for such purposes because they are less expensive and easy to handle. A lot of techniques have been reported so far, but they are not available for the structures whose boundary conditions are unknown. The authors propose the new approach using the PVDF films with the shape of appropriate Fourier series, which is applicable to the structure of arbitrary boundary conditions. Identification of the mode shape is simulated in the case of cantilever beam, which shows the availability of the proposed method. Furthermore, the experiment was carried out with the cantilever-like plate. The good agreements were obtained when compared with the calculated results.

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This paper is concerned with the feasibility study based on computer simulation to realize a 10 MWh class energy storage flywheel system. Actually, we had done the exact vibration analysis of one model of 10 MWh class flywheel rotor using CAE software based on a finite element method taking into account a gyroscopic effect. This flywheel system is the outer rotor which consists of a four spoke rib, CFRP flywheel, superconducting magnetic bearing and active magnetic bearing. The conceptual design, vibration analysis, modeling for control and H_∞ controller design of the 10 MWh class energy storage flywheel system are discussed in this paper in detail. Specially, We propose five kind of models to verify the stability of 10 MWh class energy storage flywheel system with gyroscopic effect or not. The five kind of models are the ANSYS model, the one-dimensional FEM model without gyroscopic effect, the FEM model with gyroscopic effect, the reduced-order model without gyroscopic effect and the flexible support model with gyroscopic effect. The closed loop stability of system was verified by these models. It is clarified that H_∞ controller taking into account gyroscopic effect can stabilize the flywheel system.

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This paper presents a practical and quantitative technique for assessment and localization of infancy damages in a structure by measuring the impedance change of piezoelectric patches which were glued on the structure. The consideration of longitudinal wave propagation in structures is introduced for quantitative assessment of damage characteristics because the corresponding frequency regions are easily determined with longitudinal wave propagation analysis. It is shown that the damage location can be simply estimated by measuring the PZT's electric impedance and comparing with the longitudinal strain mode shape functions in the healthy structure.

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This paper deals with an investigation to the relationship between robotic intelligence and embodiment. The robotic intelligence may be strongly related among the task the environment, and the body. In the task that two-mobile robots composed of crawler and 1 dof prismatic arm carry a long bar horizontally along a compound road with keeping the bar support length constant, the two pair of the robots, with different character of body (size of body and locomotion-distance per 1 step), acquire the intelligence autonomously in a simulation environment by reinforcement learning. We investigated the structural characteristic of relationship between robotic intelligence and thesize of body, locomotion-distance per 1 step.

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The problem investigated involves development of the moving mechanism for a soft floor and a low projection, a step. Behavior of the mechanism discussed looks like quickly small step running by twin legs. It has pair of big feet with kneeless short legs, which are alternatively driven out of phase with twin eccentric discs. The feet trot along, that is, vibratory motion, so its motion is called the vibratory trot. Its toe is pulled up by a coil spring corresponding to a tendon at the leg's step width and projection clear ability is effectively increased by swing motion of the leg. It may be available to move slowly in the house with the soft floor and some projections. Theoretical considerations have clarified fundamental properties of the machine on some kinds of floor, tatami mat, carpet and woody floor, and clear some heights of the woody step. Analytical results are proved by many

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This paper describes an optimal trajectory planning of walking locomotion for a biped mechanism which has thighs, shanks and small feet. We model the mechanism to be a 3-DOF link system composed of a stance leg and a 2-DOF swing leg. The one step walking locomotion is divided into two phases, i, e., the swing motion of 2-DOF swing leg with stance leg, and the free motion of straight swing leg with stance leg. It is assumed that the knee collision of the swing leg and the toe collision at foot exchage are plastic and occur instantly. The motion of the swing and stance legs in the first phase is solved by the optimal trajectory planning method based on the function approximation method. Under the full-actuated condition at the hip, knee and ankle joints, we obtained the minimum square input trajectory solutions with natural gaits for biped mechanism parameter values and adult's parameter values. One step period of the optimal solution for the human parameter values is 0.62s which is close to that of human. The validity of the optimal trajectory planning method is confirmed by forward dynamic simulation.

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Some recognition methods were compared with in this paper for characteristic signals of hand waving gestures. Confused motions between "beck" and "driving away" were distinguished by each characteristic signal, mixing with a gravity motion and an area variation of the image of a moving hand. Therefore their dynamic gestures were able to recognize by methods of DP matching, wave difference and others. The results are the following : (1) taking the difference of a hand waving trajectory, the recognition ratio rose to more than 92.3%, (2) DP matching was not so available in the formless motions, (3) but by using some categorized vectors to search the same vectors in a trajectory, it was cleared that the miss-recognition between "beck" and "driving away" is sup-pressed.

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Since there exist a lot of deformable objects in our daily life, method of manipulation of a deformable object for a robot is expected not only in industrial manufacturing but also in life support. Generally, a force/torque sensor is used in playing a contact task for a rigid object by a robot. However, only a force/torque sensor is not enough in handling of a deformable object by a robot. In this paper, a fusion algorithm by integrating data from both a force/torque sensor and a visual sensor is proposed for a robot to play a contact task in which an aluminum peg fixed on the robot hand is inserted into a hole installed on a deformable plate. To complete the task, a high-speed camera is used and a real time processing algorithm is developed to detect deformation of the central line of the hole. Then, the results of visual processing are integrated with data of the force/torque sensor using the proposed compliance control algorithm for a robot in playing the task. The effectiveness of the proposed method has been demonstrated through experiments.

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It is indicated that there is the high possibility of disagreement between the evaluation of shape in virtual space and that in real space in the previous paper. In this paper, the new virtual system for shape evaluation is proposed which integrates the visual and gazing line-motion linkage information in virtual space and the tactile information in real space. By using the system, the preferences of 3D shape images in the proposed virtual space under some experimental conditions were compared with those of the real photoforming products made from the same data in 28 subjects by the sensory evaluation of paired comparison and the questionnaire analysis. It is found that the preference for shapes is consistent in both spaces in the relation of the preference among shapes based on the Bradley-Terry model in sensory evaluation. This indicates that the proposed system provides almost the same environment as the real space for shape evaluation. The results of questionnaire also demonstrate that the tactile information and gazing line-motion linkage system play the important roles in 3D shape evaluation, and the proposed system is enough to evaluate the 3D shapes in virtual space. These results indicate that the system enables to investigate the desirable qualities of shape evaluation by handling the information of visual, tactile and gazing line-action.

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This paper describes an image processing method for recognizing white lines on the road ahead to accomplish automatic lane tracking. The behavior of detected points on the white lines can be regarded as multi-channel time-series data. The stochastic behavior of each point correlates with not only its own past behavior but also the behavior of other points around it. Behavior is identified by using a multi-variable auto-regressive (AR) model. This method can estimate the road configuration ahead logically even if the points cannot be detected clearly because a line is discontinuous or is hidden by a forward vehicle.

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This paper presents a study on root stresses of thin-rimmed spur internal gears of higher pressure angle (α₀=27°, α₀: standard pressure angle) with asymmetric web arrangements for planetary gear units of automatic transmissions of automobiles, caterpillar drives of construction machinery and so on. Tooth deflections of thin-rimmed spur internal gears with asymmetric web arrangements due to a concentrated load in the normal direction of the tooth surface were calculated by the three-dimensional finite-element method (3 D-FEM). On the basis of the calculated results, approximate equations for the influence function of tooth deflection were derived. The load sharing factor and the load distributions on contact lines were calculated using the approximate equations and Kubo and Umezawa's method. Root stresses of thin-rimmed spur internal gear pairs in mesh were calculated by means of 3 D-FEM, and the maximum root stress and its position were examined. Root stresses of the thin-rimmed spur internal gear of higher pressure angle with asymmetric web arrangements were determined by being compared with those of thick-rimmed or solid internal gears and with those of thin-rimmed spur internal gears of α₀=20° with asymmetric web arrangements.

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An investigation was carried out to explain the ball bearing stiffness which took into account the bearing ring flexibility, and the relationship between the deformation of the bearing ring and the stiffness of the ball bearing under an axial load. In this study, first, the axial stiffness of the ball bearing under the axial load and the deformation of the outer ring were measured. Second, the calculation method of the bearing stiffness incorporating the bearing ring flexibility was proposed. Third, the validity of the presented calculation method was discussed. Fourth, the deformation of the bearing ring was discussed. From the results of experiments and analysis, the conclusions were obtained as follows: (1) The calculation method of the bearing stiffness incorporating the bearing ring flexibility was proposed. The axial stiffness of the ball bearing under the axial load can be estimated using the presented calculation method. (2) The outside surface of the outer ring of the bearing under the axial load causes a deformation in the pyramid with the polygonal number n. The polygonal number n is equal to the number Z of balls. The bottom face of the pyramid is where the axial load is applied. (3) The out of roundness of the periphery of the outer ring of the ball bearing under the axial load changes with the axial position of the outer ring. The axial position where the out of roundness is maximized coincides with the axial position of the contact point between the ball and the outer ring.

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Because the life of power transmission gears has come to be greatly affected by the tooth surface strength, it is an important problem to clarify the influence of tooth profile and helix deviation on the tooth surface strength of carburized helical gears in a practical design. In this research, first, the experiments were carried out to measure the tooth surface strength using the test gears with six kinds of different tooth surface deviation. Next, this experimental result was arranged as S-N diagram by using Hertzian contact stress calculated in consideration of the tooth surface deviation. The influence of the tooth surface deviation on the tooth surface fatigue life was quantitatively shown by the empirical formula. Using the obtained result, the influence which the kind and the amount of the tooth profile and helix deviation exerted on the tooth surface fatigue life was considered. In addition, the effect of crowning was discussed.

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By re-examining the method proposed by Thomas and Hoersch, the author developed a new method, which does not use elliptic integral, for calculating stresses in a solid under elliptical Hertz contact pressure. Dimensionless parameters calculated by this method agree well with their calculation. Stress distribution and the depth of maximum shear can thus be calculated by incorporating the new method into a spreadsheet program for personal computers. 2664Spreading characteristics of molecularly thin lubricant on a grooved surface have been studied numerically by Monte Carlo simulations and compared with measurements obtained by perfluoropolyether (PFPE) thin film spreading on a solid surface with minute grooves. In the simulations, by incorporating the interactions between molecules and the side surfaces of a groove, the Monte Carlo method based on the Ising model was extended to the case of a surface with grooves and applied to simulate the spreading of non-polar lubricant inside a groove. Compared with the spreading on a smooth surface, lubricant spreads rapidly inside a groove, indicating an acceleration of the spreading along the groove. In the experiments, lubricant spreading on surfaces with groove-shaped textures was measured by making use of the phenomenon in which diffracted light vanishes in the lubricant-covered region. Based on the results showing lubricant spreading predominantly along the groove, the accelerating effect obtained in the simulations is well confirmed by the measurements.

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Spreading characteristics of molecularly thin lubricant on a grooved surface have been studied numerically by Monte Carlo simulations and compared with measurements obtained by perfluoropolyether (PFPE) thin film spreading on a solid surface with minute grooves. In the simulations, by incorporating the interactions between molecules and the side surfaces of a groove, the Monte Carlo method based on the Ising model was extended to the case of a surface with grooves and applied to simulate the spreading of non-polar lubricant inside a groove. Compared with the spreading on a smooth surface, lubricant spreads rapidly inside a groove, indicating an acceleration of the spreading along the groove. In the experiments, lubricant spreading on surfaces with groove-shaped textures was measured by making use of the phenomenon in which diffracted light vanishes in the lubricant-covered region. Based on the results showing lubricant spreading predominantly along the groove, the accelerating effect obtained in the simulations is well confirmed by the measurements.

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In cast-in bonding, insert may melt and be damaged by excessive heat supply from the molten metal. To reveal the conditions of insert melting, two experiments were performed and the solidification and melting transient proccess was analyzed by the difference method. Mild steel and ductile cast iron bars were dipped into gray iron melt held at three temperatures. Cast-in insertion experiment on the same materials with various diameters was also performed. The experiment and the analysis showed that the melting of ductile cast iron bars was determined by heat transfer. The melting of mild steel is determined by the carbon diffusion, because increasing carbon concentration and decreasing of melting temperature are necessary for mild steel to melt.

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GHTA (Gas Hollow Tungsten Arc) welding experiments were performed under simulated space environment and various gravity conditions in a vacuum chamber using an aircraft. An experimental system for GHTA welding test was placed in the cabin of the aircraft and the 10^-2G and 2 G gravity conditions were produced by a parabolic flight of the aircraft. Arc spot welding tests of 304 stainless steel plates and circumferential melt-run welding tests of 304 stainless steel pipes were conducted in a vacuum chamber under various conditions to investigate the influence of gravity on the welding phenomena such as arc discharge, melting and microstructure. The results are summarized as follows, (1) Although the microgravity condition makes the full penetration possible without hanging of weld metal, the investigations of arc spot welded zones by laser microscope make it clear that the gravity have no effect on surface properties such as minute rough of weld metals. The surface properties of circumferential melt-run welded zone are also independent of the gravity. (2) Microstructure and hardness of arc spot welded 304 stainless steel plates under simulated space environment are similar to those of welded plates with flat position under 1 G gravity in a vacuum. So it can be considered that there is no effect of the gravity. (3) Melt-run welding experiments with flat position under various gravity conditions make it clear that microstructure and hardness distribution in weld metals of 304 stainless steel pipes are also not affected very much by the gravity conditions.

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The necessity to substitute the artificial part so called medical implant for broken or worn bone is growing as old people increase. Materials for implant should have both the same mechanical properties as original tissues and biocompatibility. However, it is difficult that a single material satisfies these requirements simultaneously. In this study, a hybrid implant material which was composed of surface material and substantial material was developed by plasma spraying technique. Powders of hydroxyapatite (HAp) and titanium were sprayed on the titanium substrate in such way that the composition of HAp was increased gradually toward the surface. The performance of obtained HAp coatings was investigated with SEM observation, X-ray diffraction, adherence test, friction test and dissolution test. It was found that hardness, adhesion strength and corrosion resistance were improved with increase in plasma energy and that they were much improved by YAG laser irradiation after spraying. However, sprayed coatings were inferior in hardness and corrosion resistance to the pig bone or sintered HAp because of porous structure. Therefore to produce medical implants by this method, biomimetic designing will be necessary.

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A DC pulse resistance-sintering process is introduced to reduce the long processing time in the net shape sintering process of parts including intermetallic compounds by a hot-pressing (HP) process with chemical reaction between copper and aluminum powders and titanium and aluminum powders. By the DC pulse resistance-sintering mixed powder materials are sintered directly by a phenomenon of microscopic electric discharge between the particles using a DC pulse generator under a punch pressure in a graphite die. The powder mixtures of Cu-33 at % Al and Ti-50 at % Al were milled by a mechanical alloying (MA) process. The MA powder mixtures were sintered using the DC pulse resistance-sintering process. It has been confirmed that the mechanical properties obtained in a short processing time of only about 10 min by the resistance-sintering processes are as same as those in a long processing time of 2-3 hours by the HP process.

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This study examines numerical analysis of particle velocity and temperature distribution of struck material surface in fine particle peening. When the particle is accelerated using a direct-pressure type, the velocity of a 50 μm particle, just before striking the metal surface, was calculated to be 222 m/s. In applying air pressure, the acceleration of fine particles show significant increase compared to larger sizes. Moreover, the experimental values agree well with the calculated ones. On the other hand, the temperature distributions show the maximum surface temperature to be 1500 K and cools instantly.

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Deformation behavior of Zr based bulk metallic glass ; Zr₅₅Cu₃₀Al₁₀Ni₅ (atomic %) under tensile stress at the supercooled liquid region was observed. The bulk metallic glass was produced by die casting into a copper mold at vacuum atmosphere. The amorphicity of cast bulk alloy and the crystallization behavior of the amorphous phase were tested by X-ray diffraction (XRD) and differential scanning calorimeter (DSC) respectively. Machined specimen was tensed at 713 K, 723 K and 733 K (in the supercooled liquid region) at various strain rates between 4.25 × 10^-3 s^-1 and 2.90 × 10^-1 s^-1. The supercooled liquid exhibited a Newtonian viscosity and superplastic-like behavior during tensile deformation. The bulk metallic glass was elongated as much as 1 000% at high strain rates ranging from 2.50 × 10^-2 s^-1 to 2.00 × 10^-1 s^-1. The largest elongation reached 1 700%, and the smallest breaking diameter was 27 μm. However, crystallization in tested specimen was observed. The crystallization of this bulk metallic glass has a tendency to be promoted under tensile deformation.

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As higher precision machining is required, reducing thermal deformation of a machine tool becomes more important. And in the 21st century, as it is also important to produce a product with care for protecting the earth, a producer must be careful on conservation of energy. Therefore, in previous reports, a self forced cooling for reducing thermal deformation was proposed. This method is the forced cooling using water evaporation, and thermal deformation of a machine tool is finally reduced. The countermeasure is very cheap and effective in order to reduce thermal deformation. In this report, a model of the self forced cooling using water evaporation was made for simulating phenomenon of its cooling and evaluated. Then, wind velocity is controlled by the model for reducing thermal deformation of a bench lathe. It is concluded from the results that (1) The suitable wind velocity for reducing thermal deformation of the bench lathe was calculated by this model. (2) This model could use effectively for controlling the self forced cooling.

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For applying CBN wheel to grind fuel injection bulb, it is essential to clarify what the shape factors of bulb influence to a gasoline leakage. The present paper describes the theoretical treatment on the relationships between a gasoline leakage and the roundness and corner dullness of valve and seat. Those were analyzed in connect with the shape and preciseness of valve-seat in bulb. It is necessary to decrease the roundness and corner dullness of valve, as well as the roundness and average clearance of seat, in order to decrease a gasoline leakage from valve-seat clearance.

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Carbide hobbing is suitable for high efficiency production with excellent hobbing precision. Therefore, factories for mass production of gear are recently planning to adopt carbide hobbing. However, the gear materials actually used by the factories are different in the chemical components, manufacturing method, shapes, and dimensions, and their machinability is various. For this reason, it will become the important subject to relatively evaluate the difference of the machinability from the view point of the damage of the tools. In this paper, the authors have prepared the carbide fly tools with the machining center modified, and cutting grooves in the gear materials, and classified the damages, by investigating the area of damage generation, clarified the characteristics of materials to be cut, and made clear the countermeasures against the chipping. The authors actually applied this evaluation method in the carbide hobbing, as a result, it was made clear that this method is very useful for use of carbide hobbing.

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This paper describes a method of cost-benefit analysis of recycling and/or reusing by life-cycle simulation of products. This method uses colored petri nets to model : the streams of objects (i.e., products, subassemblies, parts, materials, and so on) throughout the life cycles of products ; the streams of money among companies concemed with the life cycles ; and the control of the streams. The simulation using the model reveals whether the objects are recycled and/or reused without being stockpiled and whether each company concemed with the life cycles obtains a profit. The life-cycle simulation for a copier drum composed of three materials is presented as a validation example.

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We propose a periodic preventive maintenance policy for a repairable equipment considering required interval availability. Here the required interval availability is fraction of total operating time over a certain time interval, which is required to accomplish some task by the equipment. The proposed policy gives an optimal preventive maintenance interval that minimizes total expected cost per unit time assuring the required interval availability with a predetermined confidence probability. We derive its mathematical model and apply the policy to a vapor-reflow equipment in a PCB assembly line where minimal repair is performed upon failure. The results show its usefulness compared to conventional periodic preventive maintenance policy.

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