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松原, 雅昭 ; 伊澤, 悟 ; 平尾, 典盟 ; 毒島, 康二 ; 小山, 哲 ; 町田, 康治 ; 川田, 大介 ; 坂本, 賢治 ; 根津, 紀久雄
概要:
application/pdf<br />Journal Article<br />The authors developed a new testing equipment for studying statically indeterminate fracture mechanics. Its development purpose is to clarify load history-dependency of the collapse load.
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The equipment has two actuators orthogonalized. The horizontal actuator applies the axial force and the perpendicular one does the bending moment. In the experiment for examining the effect of load hysteresis on the collapse load, both actuators can keep the preceding load to the constant load value, until axial force and bending load reach the theory collapse point. The actuators can apply the following load under the displacement control in the experiment. The performance of the equipment was confirmed by demonstration tests using single-edge notched specimens of SUS 304 steel. The experimental result clarified load historydependency on collapse load in SUS 304 single-edge notched member subjected to combined tension and bending.
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松原, 雅昭 ; 伊藤, 勲 ; 坂本, 賢治 ; 小棚木, 光明 ; 吉川, 州彦
概要:
application/pdf<br />Journal Article<br />This paper describes strength evaluation of Al_2O_3/SUS 304 joints subjected to interlaminer shear at elevated temperatures. The jig developed enables us to evaluate shear strengths of
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ceramics/metal joints at elevated temperatures. The shear strengths of them decrease with increasing temperature. The crack generally initiates at the upper and lower sides of the interface, a brazing filler. It grows into Al_2O_3 after stable growth and becomes unstable till 873 K (I C type fracture). The crack propagates along the interface till unstable fracture from 1 173 K (II type fracture). The crack behavior shows a mixed mode of I C and II types at 973 K and 1 073 K (IC+II type fracture). Larson Miller Parameter is valid for creep rapture tests under shear loading. The fracture modes are the I C type under the condition of low temperature and short time and the II type under the long-term condition.
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小島, 宏行 ; 山口, 晃明 ; 坂本, 賢治
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application/pdf<br />Journal Article<br />This paper describes the control design method and the experimental results of the stabilizing control of a inverted pendulum by a one-link horizontal robot. First, the nonlinear equation
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of motion of the mechanical system consisting of the pendulum and the robot is showed. Then, by applying the optimal regulator theory to the linear equation of motion, the optimal feedback coefficients are derived, and the validity of the control design method are confirmed by the numerical simulation of the stabilizing control of the inverted pendulum. Furthermore, it is showed experimentally that the inverted pendulum can be controlled well by the robot, and the experimental results of the continuous control consisting of the swing-up control and stabilizing control is demonstrated.
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小島, 宏行 ; 三友, 啓之 ; 和田, 祐樹 ; 坂本, 賢治
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application/pdf<br />Journal Article<br />This paper describes a motion control method of a two-link horizontal bar gymnastics robot with passive joint by use of a feedforward control based on the inverse dynamics. The direct current
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servomotor is installed at only the second joint, and the first link is controlled by the coupling forces and the moments between the active and passive joints. The dynamic behavior of the robot is described by the use of a system with two equations of motion. In the design of the control system, first, the feedforward control angle of the first joint is obtained by the numerical simulation with the first equation of motion for the desired second joint angle. Then, the feedforward control torque of the servomotor is computed by applying inverse dynamics to the second equation, and the feedforward control voltage is obtained in consideration of the electric circuit of the servomotor. Furthermore, the experimental results are demonstrated, and the availability of the present motion control method is confirmed.
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神宮, 利夫 ; 永倉, 和郎 ; 根津, 紀久雄 ; 坂本, 賢治
概要:
application/pdf<br />Journal Article<br />The crack propagation velocity in tensile fracture is determined by comparison of the unloading wave observed by the strain gage method with the theoretical analysis based on postulating the
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crack growth models which are backed by the fractographic analysis using the photograph taken by the scanning electron microscope (SEM). The effect of elongation, contraction of notch bottom and load rate just before rupture on the crack propagation velocity is investigated using the notched round bar specimens of annealed JIS-SS41, S45C and quenched SKS93 steel. The fracture surface of SS41 and S45C is a dimple and SKS93 a cleavage. The deformation of SS41 is largest and in turn S45C, SKS93. It is shown that the crack speed slightly decreases as elongation or contraction of notch bottom increases. Particuraly, the decrease of crack speed of quenched SKS93 is a very little. The reduction of crack speed attributes to softening of notch bottom.
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小島, 宏行 ; 小山, 清 ; 根津, 紀久雄 ; 坂本, 賢治
概要:
application/pdf<br />Journal Article<br />In this paper, the swing-up control method of a pendulum by a horizontal one-link robot is presented, and the experimental results are demonstrated. In the design of the control systom,
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first, the equations of motion of the mechanical system consisting of the robot and the pendulum are derived. Second, the trajectory planning for the swing-up control of the pendulum is investigated by the numerical simulation about the pendulum. In this trajectory planning, the sinus control command of the joint angle is used. Then, the feedforward control voltage of the servomotor are obtained by applying inverse dynamics to the equation of motion with respect to the robot. Furthermore, it is demonstrated by the experimental results that the pendulum can be swung up by adjusting the amplitudes of the sinus control command of the joint angle that is obtained in trajectory planning.
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神宮, 利夫 ; 永倉, 和郎 ; 根津, 紀久雄 ; 坂本, 賢治
概要:
application/pdf<br />Journal Article<br />Since the tensile fracture is governed by the load rate, the unstable crack fracture must be observed under the condition in which the load rate is smaller than crack speed. In this paper, the
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time-dependent stress caused by the compression wave emanated from the rupture section of a notched round bar is observed by the strain gauge method, while the problem of the same condition is theoretically analysed by postulating the crack growth models. The crack speed is determined from a comparison of the experimental result with theoretical result. Furthermore, the present paper experimentally distinguishes the effect of various factors, load rate and stress intensity factor, strain hardening, and area contraction of the material on the crack speed in tensile fracture, and suggests the experimental condition in observing the unstable crack fracture by the tensile test.
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| 8.
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小島, 宏行 ; 根津, 紀久雄 ; 坂本, 賢治 ; 川鍋, 隆 ; 小島, 英男
概要:
application/pdf<br />Journal Article<br />A rapid position control method, to which the feedforward control based on the inverse dynamics is applied, is presented, and the availability is confirmed experimentally and theoretically.
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In the experiment, the linear direct current motor is made with an aluminum coil frame or an acrylic resin frame. Then, it is confirmed that, by the present control method, the moving part of the linear direct current motor can be controlled exactly to the position control command for an arbitrary settling time, without undesirable mechanical vibrations. When the settling time is comparatively long, the wave shape of the control current of the motor is affected mainly by the spring force of the beam. Then, with a decreasing value of the settling time, the inertia force has significant effects on the wave shape of the control current. Furthermore, the numerical simulation results obtained by the finite element method agree well with the experimental results.
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| 9.
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小島, 宏行 ; 植杉, 献 ; 根津, 紀久雄 ; 坂本, 賢治
概要:
application/pdf<br />Journal Article<br />In this study, the mechanical system and the circular path control system of a horizontal two-link robot are constructed by utilizing step motors and harmonic drive gears. The effects of
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the excitation method of the step motors and the shape of the velocity pattern of the circular path control system on the dynamic characteristics are investigated. In the circular path control system, the control pulse generation algorithm to the step motors is constructed by use of inverse kinematics. From the experimental results, it is seen that the circular path control can be achieved with a comparatively high accuracy. Then, it is advisable for stable and fast circular path control without the failure phenomenon of the step motors, to utilize the two-phase excitation method of the step motors and the trapezoidal velocity pattern of the circular path control.
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| 10.
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神宮, 利夫 ; 根津, 紀久雄 ; 坂本, 賢治
概要:
application/pdf<br />Journal Article<br />The mechanical components of a ball thrust bearing, constant-velocity universal joint, locker arm of a cam driving a cylinder valve and a ball-type pressure-regulating valve, involve the elements
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of a sphere and an anvil. These are subjected to impact load. In this paper, we suppose a model with the simplest form of only a sphere and an anvil for these complex components. The sphere and anvil are in contact with each other and rest along the straight line joining their centers. When the free-side end of the anvil undergoes the normal collinear impact by travelling around the bar, the impact load transmitted into the sphere adjacent to the anvil is theoretically analyzed by a motion equation and Hertz's contact theory. It is important to find the particle velocity evoked by the arrival of a stress wave at the end of the anvil which is a point contact with the sphere. This particle speed is an initial velocity as the anvil transmits the load into the sphere. The validity of theoretical analysis is confirmed by comparison with an experiment under the same conditions.
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