Showing papers in "Transactions of the Japan Society of Mechanical Engineers. C in 1990"
23 citations
TL;DR: In this paper, a manufacturing system using the method of a centrifugal casting technique for a ceramics/metal functionally gradient material was studied and a mathematical model based on the expression was proposed to consider the effects of the volume fraction of the powder and the centrifugal force on the distribution.
Abstract: The aim of this investigation was to study a manufacturing system by the method of a centrifugal casting technique for a ceramics/metal functionally gradient material. The centrifugal force enables the ceramics powder in a metal to Create a gradient distribution. The mixtures consisting of plaster and corundum was chosen as a experimental model. The mixed materials were cast into rings under the combined conditions of four different volume fractions and three different No. times of gravity. The corundum profile was measured and analysed cubic order porinomial equation. A mathematical model based on the expression was proposed to consider the effects of the volume fraction of the powder and the centrifugal force on the distribution. The model can express the observed distribution fields in a unified manner. A manufacturing system using the model was discussed wether it satisfies the designed distribution of the powder.
21 citations
TL;DR: The rotational transmission errors of several assembled harmonic drive devices are precisely measured over one revolution of an output shaft by using three test pieces of each element, a ring gear, a cup gear and an oval cam as mentioned in this paper.
Abstract: The rotational transmission errors of several assembled harmonic drive devices are precisely measured over one revolution of an output shaft by using three test pieces of each element, a ring gear, a cup gear and an oval cam. Further, angular pitch errors of the tooth spaces of the tested rigid and cup gears with a small module (0.5mm) are also precisely measured by a newly designed measuring device with a resolution of 1/1000 deg. It is found that the rotational transmission error is composed of two components. One is caused by the angular pitch error of the ring gear and varies periodically with a period of half a revolution of the input shaft. The other is caused by that of the cup gear and varies with a shorter period.
17 citations
16 citations
TL;DR: In this paper, a sensitivity analysis method for the eigen problem of coupled acoustic-structural systems is proposed, which is to be applied for reducing the vehicle interior noise, by estimating the calculation error of this method theoretically, a guideline of the design variable change limit is shown.
Abstract: An sensitivity analysis method for the eigenproblem of coupled acoustic-structural systems is proposed, which is to be applied for reducing the vehicle interior noise. At first the conception of the left eigenvector and right eigenvector with regard to coupled acoustic-structural eigenproblems is introduced, and four propositions concerning this conception are then proved. On the basis of these propositions, the formulation of the eigenmode sensitivity analysis is obtained. The eigenmode sensitivity formulations are applicable to the change of structural parameters, acoustic parameters and acoustic-structural coupling conditions respectively. By estimating the calculation error of this method theoretically, a guideline of the design variable change limit is shown. The theoretical results and computation formulations are demonstrated through a cubic shell interior noise problem.
15 citations
14 citations
TL;DR: In this paper, the mechanism of the impact phenomena of golf clubs and golf balls by both time series analysis and the concept of mechanical impedance in the frequency domain and to investigate the maximum restitution.
Abstract: This paper proposes to clarify the mechanism of the impact phenomena of golf clubs and golf balls by both time series analysis and the concept of mechanical impedance in the frequency domain and to investigate the maximum restitution. By using a lumped mass system, the restitution coefficient and the impact transfer efficiency are investigated for the golf clubs and golf balls. Secondly, the optimum combination of golf club and golf ball which gives the maximum restitution coefficient and the maximum impact transfer efficiency is related to the concept of mechanical impedance. That is, the relation between time series analysis and frequency domain analysis is clarified in the problems to obtain the maximum restitution coefficient and the maximum impact transfer efficiency of two bodies. Furthermore, a few experiments on hitting the golf balls with golf clubs are performed, and the results of the experiments are compared with those of the numerical analysis.
13 citations
TL;DR: In this paper, the dynamic test results of high damping rubber bearings and analytical models for the hysteretic restoring force were discussed, and the appropriateness of each model was evaluated.
Abstract: This paper describes dynamic test results of high damping rubber bearings and discusses analytical models for the hysteretic restoring force. The dynamic tests were carried out for two types of rubber bearing which had a difference in hardness of rubber. The two types, the rubber bearing of 588kN rated load (the low hardness type) and that of 784kN (the high hardness type), had the same shape, and comprised of 23 rubber sheets of 6mm thickness and 450mm diameter bonded to steel plates. Each type of the rubber bearing was designed to provide the rated mass (60000kg or 80000kg) with a horizontal natural frequency of about 0.5Hz and an equivalent damping ratio of about 15%. For each type of the rubber bearings, the test results revealed various properties of the horizontal and vertical stiffnesses and equivalent damping ratios obtained from the hysteretic restoring force loops. Three analytical models were proposed to express the horizontal hysteretic restoring force, and appropriateness of each model was evaluated.
13 citations
TL;DR: In this article, a thin duralumin beam coated with a sheet of thin vinyl was used as a test specimen for chaotic vibrations of a compressed buckled beam subjected to periodic lateral excitation.
Abstract: Experimental results are presented for chaotic vibrations of a compressed buckled beam subjected to periodic lateral excitation. A thin duralumin beam coated with a sheet of thin vinyl was used as a test specimen. The beam was clamped at both ends to the base frame of an electromagnetic shaker. Initial axial displacement of the beam was controlled utilizing thermal elongation both of the beam and frame. Typical responses of time history and the strange attractor of the chaotic vibration were observed near the frequency range of the fundamental resonant vibration. It is found that the correlation dimension of the strange attractor yields a value of d=3.8 under twice the axial displacement corresponding to buckling load.
13 citations
TL;DR: In this paper, the correlation between the amplitude of the tooth mesh frequency component of measured noise and that of the simulated single flank rolling test of gears using the measured form accuracy of tooth flank was investigated.
Abstract: In order to develop a better method of predicting gear noise of automotive power transmission as a function of gear accuracy, the correlation between the amplitude of the tooth mesh frequency component of measured noise and that of the simulated single flank rolling test of gears using the measured form accuracy of the tooth flank was investigated. Experimental and simulated results show, when the worst composite error surface of meshing tooth flanks is chosen as representative among many different composite error surfaces for possible combinations of meshing tooth pairs and the simulation is worked out under the hypotheses, that this worst composite error surface exists at every meshing of teeth, a very good correlation between simulated results of the single flank rolling test of the pair of gears and measured noise level of power transmission can be obtained. This result indicates that the development of the gear production method to minimize the scattering of deviation of tooth flank accuracy at each tooth of a gear is more effective in producing noiseless power transmission than in improving the average quality of tooth flank accuracy of gears.
13 citations
TL;DR: In this article, an equation of motion is derived by the finite element method considering kinematic motion and vibration of the club and real swing data, that is, angular velocity and acceleration of a golf swing, are measured using a high-speed video camera and digital image processing.
Abstract: This paper deals with the optimum design of a golf club by tuning the shaft stiffness. First, an equation of motion is derived by the finite element method considering kinematic motion and vibration of the club. Then real swing data, that is, angular velocity and acceleration of a golf swing, are measured using a high-speed video camera and digital image processing. Applying these data to the above equation, the following results are obtained. It is found that in the process of optimizing, the design of the club head and shaft can be separated. Optimum flexibility is generally determined in proportion to the level of ability: optimum club shafts for beginners should be more flexible than those of more advanced players.
TL;DR: In this paper, an active isolation system using linear motors was developed, in which the table supported by air springs was controlled by 4 vertical linear motor actuators and 4 horizontal linear motors actuators.
Abstract: Microtremor isolation is important for improving the yield rate of complete IC chips. For this purpose, passive isolation devices using air springs have been used so far. However, as the degree of integration in IC chips increases and patterns of circuits become more fine, more complete isolation is becoming necessary. Therefore an active isolation system using linear motors was developed, in which the table supported by air springs was controlled by 4 vertical linear motor actuators and 4 horizontal linear motor actuators. The isolation system used a full-state feedback control system designed by the optimal regulator theory. The controller, implemented by a 16-bit personal computer, calculated 8 control inputs to the actuators from 12 signals made by integration of absolute accelerations detected by sensors, 6 of which were absolute velocities and the other 6 of which were absolute displacements. Through tests, it was confirmed that the active system could achieve superior performance compared with a passive system with high performance.
TL;DR: In this paper, a static analysis of the link compliances is presented for appropriate compliance control of a flexible manipulator, and the results show that the smooth and precise assembly was established by selecting adequate attitude and setting servo compliance conditions more flexible than the link compliance.
Abstract: A new approach to the static analysis of the link compliances is presented for appropriate compliance control of a flexible manipulator. Unlike a rigid manipulator, there exists the interaction between the servo flexibility and link flexibility in a flexible manipulator system. Therefore, it is important for smooth control to understand properties of the link compliances and make good conditions of the system compliances. For this purpose, the authors derived the generalized compliance matrix, compliance ellipsoid and compliance center of the link flexibility. It was found that there was an adequate attitude of a manipulator for excluding the influence of the link compliance and establishing tasks smoothly. The validity of this analytic method was investigated by experiments of the round peg-hole assembly. A two-link flexible SCARA manipulator system was constructed for this purpose. This manipulator was 1.5 m long. The results showed that the smooth and precise assembly was established by selecting adequate attitude and setting servo compliance conditions more flexible than the link compliances.
TL;DR: In this article, a method of predicting sound absorbing capability for multi-layer sound absorbing materials was studied by using the boundary element method, which was characterized by the complex propagation speed and the complex effective density, which were measured using the two-microphone technique.
Abstract: A method of predicting sound absorbing capability for multi layer sound absorbing materials was studied by using the boundary element method. The sound absorbing material was considered as a medium transmitting sound waves, and it was characterized by the complex propagation speed and the complex effective density, which were measured using the two-microphone technique. The sound field containing the sound absorbing materials was analyzed using the boundary element method developed for multi domain problems. The normal sound absorption coefficient of the materials was calculated and compared with the experimental coefficients. The excellent agreement achieved suggests that the present method is sufficiently reliable to predict the normal sound absorption coefficient.
TL;DR: In this article, a multireference curve-fitting technique based on the maximum likelihood method is presented, which utilizes the frequency response function (FRF) as input data and obtains modal parameters by iterative calculation.
Abstract: Experimental modal analysis is widely used in many fields and many curve fitting techniques which estimate modal parameters have been developed. This paper presents a new multireference curve-fitting technique which is based on the maximum likelihood method. The proposed method utilizes the frequency response function (FRF) as input data and obtains modal parameters by iterative calculation. In this paper, initial values for the iteration are supposed to be obtained from the modal parameters estimated by the polyreference method. It turns out that modal parameters converge to the same value regardless of initial values. Therefore, the analyst can get rid of troublesome judgment on selecting physical roots in the polyreference method. The FRF constructed by the result of the proposed method agrees better with the experimental FRF than that by the polyreference method. Moreover, modal parameters estimated by the proposed method are more reliable from a statistical standpoint.
TL;DR: In this paper, the authors developed an automatic compensation method for the expansion of the ball screw using the thermal expansion detector installed near the NC zero point, and the thermal behavior of the horizontal machining center under various driving conditions was measured to examine the effectiveness of this compensating method.
Abstract: Thermal expansion of the ball screw in semi-closed loop type machining centers directly introduces positioning errors along the travel axis. The purpose of this study is to develop an automatic compensation method for the expansion of the ball screw using the thermal expansion detector installed near the NC zero point. The thermal behaviour of the ball screw of the horizontal machining center under the various driving conditions was measured to examine the effectiveness of this compensating method. From these results, the thermal expansions of the ball screw along the travel axis were approximated by a linear function of the distance from the ball screw support, and thereby the positioning accuracy could be maintained to better than ±3μm while using this compensation.
TL;DR: In this article, the authors developed a new type of parallel bicycle which can vary its configuration and change locomotion mode according to the working conditions or circumstances, such as postural and driving control using the controlling arm.
Abstract: The authors have developed a new type of parallel bicycle which can vary its configuration and change locomotion mode according to the working conditions or circumstances. The fundamental components of the vehicle are an inverted-pendulum-type parallel bicycle, a working arm and a controlling arm. By combining the components, three kinds of the configurations can be realized : a parallel bicycle with a working arm and an L-shaped controlling arm, a double-steered wheeler with a controlling arm, and a four-wheeled vehicle with a working arm. This paper describes the control methods of motions obtained with the first-type parallel bicycle with a working arm and an L-shaped controlling arm, and experimental results. The postural and driving control using the controlling arm is very useful and the motion of the working arm is well controlled by it. When an auxiliary wheel is installed at the tip of the working arm and the arm is lowered until it touches the ground, the vehicle is converted into a tri-wheeled car. Conversion from the two-wheeler to the tri-wheeler and the inverse conversion are also successfully attained by the intelligent control method proposed here.
TL;DR: In this paper, the elastic-plastic analysis based on a combination of the finite element method (FEM) and the body force method (BFM) is applied to the subsurface layer under cyclic pass of rolling-sliding contact loading.
Abstract: The elastic-plastic analysis based on a combination (FEM+BFM) of the finite element method (FEM) and the body force method (BFM) is applied to the elastic-plastic analysis of the subsurface layer under cyclic pass of rolling-sliding contact loading. Two types of hardening rule are assumed. One is the isotropic hardening rule (IHR) and another is the kinematic hardening rule (KHR), i. e. Prager rule. If the material obeys IHR, so-called shakedown phenomenon is induced during the early cycle of pass of loading. On the other hand, if the material obeys KHR, the quasi-steady cumulative forward flow develops at the load level of q0/ks7, where q0 is the peak Hertzian pressure and k is the shear yield strength in von Mises' yield criterion. No apparent difference is found in the cyclic increment of the equivalent plastic strain range Δe^-p in the subsurface layer for the coefficient of friction=+0.1 and -0.1. The amount of the experimentally observed forward flow was more than the numerical results for IHR and less than those for KHR.
TL;DR: In this article, a wind-tunnel fan showed a large 2N vibration at 465rpm and was inferred to have a crack from the excitation test, and a shaft crack was detected.
Abstract: Our previous paper reported the fundamental dynamic characteristics of cracked rotors, crack detection methods by static tests, and a numerical vibration-analysis method of general cracked rotors. This paper describes an example of the diagnosis of a cracked rotor based on former results. A wind-tunnel fan showed a large 2N vibration at 465rpm and was inferred to have a crack from the excitation test, and a shaft crack was detected. The analysis of natural frequencies and responses of the cracked rotor shows the adequateness of the method.
TL;DR: In this article, a tactile sensor array consisting of a 6×15 matrix of 3×3 mm sensing sites is used to detect the distribution of the three components of a force vector.
Abstract: In order to improve the intelligence of a robot with a sense of touch, we have developed a tactile sensor array which can detect the distribution of the three components of a force vector. The tactile sensor consists of a 6×15 matrix of 3×3 mm sensing sites; each site is made of two single-crystal silicon rings on which semiconductor strain gauges are formed by means of a semiconductor processing technique. In this paper, we have introduced formulas to calculate applied force/moment, a center of distributed pressure, and some parameters of slip and hardness, and then carried out sensing tests in order to validate those formulas. Experimental results show that applied force/moment and the center of distributed pressure can be detected with practical accuracy. Slipping, rolling and rotating states can be distinguished by combinations of the slip parameters. Moreover, mechanical properties can be sensed by means of combinations of the hardness parameters. A lump in a soft object can be recognized using an adequate threshold method.
TL;DR: It is explained that safety reporting means have characteristics of asymmetricalerror output signal generation and that the safety information to be reported must depend on the structure of the equipment involved, and the asymmetrical error rate is defined as a means of safety evaluation.
Abstract: An injury arises from the transfer of potential or kinetic energy caused by the collision of a human with a hazardous object. Safety problems come from uncertainty involved in work space. As safety goes with information indicating safety of the work space, sampling and transmission of information on safety is indispensable as a means of proving safety. This paper presents 'principles of safety', describing (1) creation of safety, (2) continuity of safety, and (3) publication of safety. In order to achieve a safety (system) on the basis of the principles, this paper also explains that safety reporting means have characteristics of asymmetricalerror output signal generation and that the safety information to be reported must depend on the structure of the equipment involved. The asymmetricalerror rate is defined as a means of safety evaluation, and safety reporting means with asymmetricalerror characteristics are modeled as structures of a electric fuse and safety confirmation behavior.
TL;DR: In this article, the effects of contact pressure and relative slip displacement on smoothing conditions of surface asperities were examined with no bulk plastic deformation of a workmetal, disk specimens were compressed by a punch in a closed die and rotated with the die.
Abstract: To examine the effects of contact pressure and relative slip displacement on smoothing conditions of surface asperities acommpanied with no bulk plastic deformation of a workmetal, disk specimens were compressed by a punch in a closed die and rotated with the die. A little amount of the relative slip displacement under the contact pressure accelerated remarkably the smoothing of the surface asperities and thereby the workmetal surfaces were smoothed completely to the same surface roughness as the tool. The surface roughness change of the workmetal were approximated by the experimental equations which were expressed as a function of the contact pressure and relative slip displacement. On the basis of these results, smoothing conditions of surface asperities accompanied with bulk plastic deformation of a workmetal were investigated by a free upsetting of disk specimen and an upsetting of ring specimen in a closed die. Consequently, the smoothing conditions of the workmetal surface in these forming processes also could be approximated by the same equations as the above experimental equations.
TL;DR: In this paper, a flexible microactuator with 3 degrees of freedom was developed for micromanipulators, which was made of fiber reinforced rubber (FRR) and its deformation controlled by an electrohy-draulic or electropneumatic system.
Abstract: A flexible microactuator with 3 degrees of freedom was developed for micromanipulators. The device was made of fiber reinforced rubber (FRR) and its deformation controlled by an electrohy-draulic or electropneumatic system. This report deals with its dynamic characteristics from a practical point of view. First, a transfer function of the actuator is derived theoretically, considering (1) a fundamental frequency of FRR, (2) compressibility of working fluid in the actuator, and (3) friction of tubes between the actuator and control valves. Secondly, step responses of the prototypes are shown under various conditions. The response time is about 0.1 (s) with small tube friction, or 3(s) with large tube friction.
TL;DR: In this paper, a new type of actuator based on shape memory alloy (SMA) and its application to mechanisms of underwater mobile robots was reported. But the authors did not specify the shape of the actuator.
Abstract: This paper reports the key features of a new type of actuator based on shape memory alloy (SMA) and its application to mechanisms of underwater mobile robots. The proposed actuator consists of several modes of SMA, so that any shapes can be produced as the synthesized sum of excited modes, like the mode expansion and synthesis. Thus, the actuator shows the characteristics of the distributed parameter type of actuators with a specified number of modes. In this paper, the following aspects are described: (i) A flat-belt type of SMA is employed and its bending characteristics are examined. (ii) A synthetic method of wave forms is presented. (iii) Applying the proposed distributed actuators to the underwater mobile robot, mechanisms such as fish fins are shown to obtain thrust forces in the water. (iv) The shape of the actuator is experimentally verified to be similar to the computed shape, as expected. As a result, the proposed distributed actuator shows the possibility of applications to distributed parameter shape control.
TL;DR: In this paper, the authors proposed an analytical approach for designing air damper with a piston and a cylinder, which is based on the properties of air : viscosity and compressibility.
Abstract: Air damper has a great advantage that is independent of temperature change. This paper proposes an analytical approach for designing air damper with a piston and a cylinder. The characteristics of the air damper are depend on the properties of air : viscosity and compressibility. Thus, the air damper shows the so-called visco-elastic property : the applied force to the piston is resistant to the velocity and displacement of the piston. As a result, the air damper has two important factors, called damping coefficient and spring constant. Two types of air damper are discussed. Type I is a viscous damper whose resisting force is proportional to the piston velocity, and type II is a nonviscous damper whose resisting force is proportional to the velocity-squared of the piston. This paper leads to a simple and accurate method for designing these types of air damper.
TL;DR: In this paper, a squeeze film damper with Electro-Rheological fluid (ERF) has been used to reduce the vibration of a rotor system, and it is shown that ERF is quite effective for the reduction of vibration for any rotor system.
Abstract: Electro-Rheological fluid (ERF) has notable characteristics of viscosity which could be applicable for various industrial machines. Viscosity of ERF increases in accordance with the applied electric field. Without an electric field, ERF has the viscosity characteristics of a Newtonian liquid. Variation of viscosity is reversible, and the required time for variation is said to be as short as 0.001 sec. Numerous applications of ERF in the engineering field have been attempted since the characteristics of ERF were discovered by W. M. Winslow. However, no successful application has ever been reported. This paper deals with the successful application of ERF to a squeeze film damper. It is elucidated that the squeeze film damper with ERF is quite effective for the reduction of vibration for any rotor system. First and second critical speeds can be easily passed without large vibration amplitude. It is also shown experimentally that there may be the most effective damping ratios for every mode of the rotor. Transition phenomena of the modes in accordance with supported damping are clarified in the present experiment.
TL;DR: In this article, a vibrationless acceleration control for hard-disk drive positioning mechanisms is proposed, which accelerates a flexible positioning mechanism to a certain acceleration without the transient vibration that prolongs the settling time and decreases positioning accuracy.
Abstract: This paper describes vibrationless acceleration control for hard-disk drive positioning mechanisms. This control accelerates a flexible positioning mechanism to a certain acceleration without the transient vibration that prolongs the settling time and decreases positioning accuracy. We first describe how we derive the solution to optimal acceleration control based on optimal control theory. We then discuss results, and apply this control to the operation of a practical 5.25-inch magnetic disk drive.