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小島, 宏行 ; Kato, Gustavo
概要:
application/pdf<br />Journal Article<br />In this paper, the dynamic behaviors of a two-link hopping robot with two stopper mechanisms are investigated theoretically. In the theoretical analysis, the dynamic behaviors of the
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two-link hopping robot with two stopper mechanisms are modeled by use of the four phases (phase-A, phase-B, phase-C, phase-D). At the moment when the first joint stops, the state of the system transfers from phase-A to phase-B. Then, at the moment when the second joint stops, the state of the system transfers from phase-B to phase-C. In phase-C, the two-link hopping robot moves in space, and at the moment when the two-link hopping robot lands, the state of the system transfers from phase-C to phase-D. Using the principle of the conservation of momentum and angular momentum, the initial states in the periods of phase-B and phase-C are derived, and the equations of motion of the two-link hopping robot in all phases are obtained. Furthermore, the numerical simulations have been carried out, and it is confirmed theoretically that the hopping and moving action can be performed successfully.
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神宮, 利夫 ; 根津, 紀久雄 ; 坂本, 賢治
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application/pdf<br />Journal Article<br />When a stepped beam is impacted, time histories of bending strain are measured by strain gauges which are cemented at the fixed end and the corner of discontinuity in the beam. Although the
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variations of bending strain calculated by the finite element method based on Bernoulli-Euler beam theory also involve the high frequency modes, those by experiment consist of the basic frequency mode and a few low frequency modes. Since the fixed end of a canti-lever beam in an experiment is not perfectly rigid, the periodicity of vibration is affected by it. The time histories of bending strain on the shelf of discontinuity differ from the flexural motion by the simpler Bernoulli-Euler theory. However, observing the variations of bending strain at the other location, except for the high frequency modes, the vibration of both is in fair agreement.
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神宮, 利夫 ; 松本, 浩之 ; 根津, 紀久雄 ; 坂本, 賢治
概要:
application/pdf<br />Journal Article<br />In the collision between the flat surface of solid and of a sphere, it can be considered that a high stress will be occur, since an impact load is applied in a small local contact area. If an
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impact stress exceeds the yield stress of a material, the local deformation of the contact surface converts from elastic to plastic flow. Therefore, the impact load may be moderated. It is important when formulating the impact load that the effect of the local plastic deformation of the contact surface on the time history of a load due to impact is investigated. On the other hand, it is revealed by Hertz's theory that the relationship between a force and the amount of approach of both solids during impact is nonlinear. If it is postulated as being linear, there is not little what be able to apply it to analyze the dynamic impact problem. In this paper, the effect of the local displacement behavior in the contact process on the impact load is shown by the experiment of a collision between a plate of mild steel and a high hardness steel ball. The impact load is evaluated by a piezo electric plastic transducer. The limitation which the modified approach of Hertz's theory is valid, are distinguished.
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神宮, 利夫 ; 松本, 浩之 ; 根津, 紀久雄
概要:
application/pdf<br />Journal Article<br />In this paper, the dynamic similarity of transient response caused by the collision between a sphere and a cantilever beam is theoretically investigated and the results are compared with the
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experiments. The theoretical analysis of transient response in a cantilever beam is conducted by the use of classical beam theory and with the aid of a Laplace transform which extends the fast Fourier transform to an inverse transform under the condition that the spheres strike cantilever beams at arbitrary points. The dynamic similarity of a cantilever beam is studied to use those results. In the experiment, the bending strain is measured by a strain gauge cemented to a bar of rectangular cross section of the model or the real thing. It is shown that the variation in bending strain of the model multiplied by the coefficient of similarity is in agreement with the real thing.
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神宮, 利夫 ; 松本, 浩之 ; 根津, 紀久雄
概要:
application/pdf<br />Journal Article<br />When applying the results of a model study to practical problems, it is convenient to find the relation of similarity of both. we experience the impact behavior as shown in a contact of cam and cam
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straddle, more space after punctuation arc spot welding, etc. This paper studies a mechanically similar manner of linear elastic to the collision of two round bars or a round bar and periphery of circular disk, which are of various dimensions and material constants. It is important that the similarity of stress and the motion equation are valid for the dimensions, material constants of the member, and the time. Supposing the similarity of dynamic manner, we could investigate the response to the use of the material which is stable to the impact, in stead of, for example, titanium of firing caused by heat storage resulting from a rapid deformation, and valuable materials which need not be subjected to an unknown impact load.
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神宮, 利夫 ; 松本, 浩之 ; 根津, 紀久雄
概要:
application/pdf<br />Journal Article<br />半無限弾性体の表面の四半無限領域に垂直およびせん断荷重がインパルス状に作用する時の応力の時間的変動を三次元動弾性理論に基づいて解析した. ラプラス逆変換にお
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いては三次元カグニアード法を適用した. この場合荷重領域と解析領域の関係に注目する必要がありカグニアード反転積分路の変更においてこのことを考慮すれば全領域の解析が可能であることを示した.
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神宮, 利夫 ; 松本, 浩之 ; 根津, 紀久雄
概要:
application/pdf<br />Journal Article<br />表面に衝撃荷重を受ける反無限弾性体の衝撃問題の理論的解析には主にラプラス変換法によって行われているが実空間解を得るためのラプラス逆変換が困難な場合がある.
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Cagniard法はこの点を解決しており二次元衝撃問題, 三次元軸対称問題に適用されている. 本研究では三次元のより一般性のある非軸対称問題にCagniard法が適用できるように拡張することを試み重直線状荷重およびせん断線状荷重の場合について標題の問題を理論的に解析した.
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神宮, 利夫 ; 松本, 浩之 ; 根津, 紀久雄
概要:
application/pdf<br />Journal Article<br />半無限弾性体の表面の四半無限領域に衝撃荷重が作用する問題に対する解析結果を重ね合わせて帯状領域に衝撃荷重が作用する問題の解を求めさらに帯状領域の問題を重ね合
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わせ法によって標題の問題に帰着させる. 標題の衝撃問題に重ね合わせ法を適用するときは静荷重に対するような解析結果の数値評価を重ね合わせるのでは解析されずに荷重作用領域と解析領域の関係に注目して各領域毎に導出される解析式を重ね合わせることが必要である.
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神宮, 利夫 ; 根津, 紀久雄
概要:
application/pdf<br />Journal Article<br />直径に沿って対向した集中荷重が時間に対してステップ関数状に変動する衝撃荷重を受ける球の衝撃応力を動的弾性理論に基づきラプラス変換法を適用して解析を行い球の各
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部の変位及び応力の時間的変動を明らかにした. ラプラス変換解は変数分離法によって誘導されるルジャンドル関数と第1種ベッセル関数で表されラプラス逆変換は留数定理を適用することによって行った. 解析結果は時間に対する変位及び応力に変動を図示した.
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