著者

上西 甲朗 松久 寛 宇津野 秀夫 朴 正圭

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. C編 (ISSN:03875024)

巻号頁・発行日

vol.70, no.697, pp.2624-2630, 2004-09-25

被引用文献数

3

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During a car frontal collision, some part of the occupant's kinetic energy is transferred to the vehicle through the restraint system. The high ratio of the transferred energy has the advantage of protecting the occupant. This phenomenon is called "ride down effect". It is known from experience that if the deceleration of the automotive body is large in the early stages of a collision, the effect becomes large, provided that the vehicle kinetic energy and the maximum value of the automotive body deformation are same. In order to design an automotive body structure taking into consideration the ride down effect, the dynamic relation between the occupant deceleration, which is one of important injury criteria, and the automotive body structure must be studied. However, there have been few researches to analyze the theoretical mechanism of the ridedown effect in detail. In this paper, we formulated ridedown effect focusing on the protection devices using a two-degree-of-freedom model for a vehicle and an occupant. The relationship between the index of the ride down effect and the occupant deceleration caused by crashing the automotive body structure was theoretically analyzed, and an optimum automotive crash design was examined.

著者

佐藤 博則 山下 進介 宇津野 秀夫 松久 寛 山田 啓介 澤田 勝利

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集C編 (ISSN:18848354)

巻号頁・発行日

vol.77, no.775, pp.989-1003, 2011 (Released:2011-03-25)

参考文献数

7

被引用文献数

2 2

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Life style related diseases such as hypertension and diabetes promote arteriosclerosis which causes circulatory diseases. It is important to evaluate arterial condition for prevention of circulatory diseases. The pulse wave velocity method has become familiar as a vascular test because it is easy and non-invasively. However, the accuracy of the method seems not to be high because it just compares two points ignoring the frequency dependence and reflection waves from peripheral vessels. In this study theory of pulse wave propagation considering such effects was formulated. A new method to identify the reflection ratio from peripheral vessels and pulse wave velocity was proposed. This method was verified by experiment using a silicon tube and applied to measure the pulse wave propagation of human arm as a case study. The results showed that this method has possibility to apply to measure the pulse wave propagation of human pulse wave.

著者

西原 修 松久 寛

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集C編 (ISSN:03875024)

巻号頁・発行日

vol.63, no.614, pp.3438-3445, 1997

被引用文献数

23

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Fixed points design methods for dynamic vibration absorbers are very well-known in the field of vibration control and commonly applied for practical absorber design. However, they must be understood to be approximation methods from the point of view of their design criterion that the resonance amplitude magnification factor is minimized. In this study, the exact algebraic expressions of optimum tuning and damping parameters for the minimization of the largest resonance amplitude magnification factor of linear dynamic vibration absorbers have been derived for undamped primary systems. The existence of two equal height resonance points is reduced to a multiple root condition of an algebraic equation. The determinant is handled as an equation with respect to the resonance amplitude. It has became very clear that the fixed points theory design by Brock is highly accurate. In particular, it exhibits very small error in the practical mass ratio range, e.g., below unity. Algebraic solutions also exist for the resonance frequencies and the anti-resonance frequency. A numerical extension of the method is introduced in order to investigate the optimization problem for damped primary systems.

著者

秦 秀敏 宇津野 秀夫 松久 寛

出版者

一般社団法人 日本機械学会

雑誌

ジョイント・シンポジウム講演論文集:スポーツ工学シンポジウム:シンポジウム:ヒューマン・ダイナミックス

巻号頁・発行日

vol.2004, pp.89-94, 2004

被引用文献数

1

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Impact problem between a bat and a ball was studied using vibration modal analysis. Initial kinetic energy of the ball and the bat before the collision is transmitted to their vibration energies and their rigid body kinetic energies. The rebound speed of the ball is theoretically calculated and was measured in the experiments for slow speed impact condition. There was a good agreement between the calculation and experiment. The rebound speed of the ball was also calculated for the high speed impact condition. When the bat hits the ball with relatively high speed, higher order vibration modes appear. Therefore it is possible to increase the rebound speed of the ball by changing the design of the bat, such that the higher order modes are suppressed.

著者

本田 善久 松久 寛 佐藤 進

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. C編 (ISSN:03875024)

巻号頁・発行日

vol.60, no.579, pp.3749-3754, 1994-11-25

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The vibration of a rotating elastic disk subjected to base excitation is theoretically analyzed. Formulation of the steady-state response to harmonic excitation is derived as an eigenfunction series where the eigenfunctions are given in the form of rotating waves. It is presented that a parallel motion to the axis excites only the axisymmetric modes. It is also shown that a tilting motion around an arbitrary diameter excites the forward and backward rotating modes whose circumferential wavenumbers are one. The Doppler's effect and the coupling effect between the inertia force and the Coriolis force are discussed. The response curves and the vibratory modes of the rotating disk are studied in detail. It is shown that the standing waves fixed in space can be formed. The relation between the excitation frequency and the configuration of the vibratory modes is also presented.

著者

西原 修 松久 寛 佐藤 進

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. C編 (ISSN:03875024)

巻号頁・発行日

vol.60, no.580, pp.4098-4106, 1994-12-25

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The design optimization of passive vibration control mechanisms in the accelerance domain is discussed. In this study, the fixed points theory is developed which approximately minimizes the maximum accelerance in the frequency domain by equally adjusting the accelerance of two fixed points. This design method is applied to the dynamic vibration absorber (DVA) and the passive gyroscopic damper (PGD), and thus the maximum accelerances of these mechanisms are successfully reduced. The concept of the fixed points theory is reinvestigated. The accuracy and the degree of improvement compared with the fixed points design in the compliance domain are examined. The PGD realizes relatively higher damping effects, and then the accelerance reduction of the PGD by the new design method is considerably larger than that of the DVA with a moderate mass ratio.

著者

西原 修 松久 寛

出版者

一般社団法人日本機械学会

雑誌

日本機械学会論文集. C編 (ISSN:03875024)

巻号頁・発行日

vol.63, no.614, pp.3438-3445, 1997-10

参考文献数

6

被引用文献数

9

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Fixed points design methods for dynamic vibration absorbers are very well-known in the field of vibration control and commonly applied for practical absorber design. However, they must be understood to be approximation methods from the point of view of their design criterion that the resonance amplitude magnification factor is minimized. In this study, the exact algebraic expressions of optimum tuning and damping parameters for the minimization of the largest resonance amplitude magnification factor of linear dynamic vibration absorbers have been derived for undamped primary systems. The existence of two equal height resonance points is reduced to a multiple root condition of an algebraic equation. The determinant is handled as an equation with respect to the resonance amplitude. It has became very clear that the fixed points theory design by Brock is highly accurate. In particular, it exhibits very small error in the practical mass ratio range, e.g., below unity. Algebraic solutions also exist for the resonance frequencies and the anti-resonance frequency. A numerical extension of the method is introduced in order to investigate the optimization problem for damped primary systems.

著者

松久 寛 西原 修 本田 善久 柴田 俊忍 佐藤 進

出版者

京都大学

雑誌

一般研究(C)

巻号頁・発行日

1990

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スキ-時の人体の上下運動に関してはひざをリンク機構、筋肉を収縮要素、それと直列につながる弾性要素、並列の減衰要素で模擬した。ひざは大きく曲げる程ばねが柔らかくなるリンク機構による幾何学的非線形性を持ち、筋肉はばねと減衰からなる受動的なダンパ-としての役割と収縮による能動的な運動を行う。動特性としてはひざを深く曲げる程緩衝効果は大きくなるが、筋肉にかかる荷重は大きくなる。能動的に立ち上がる場合は立ち上がりの前半に雪面への押し付け力が増加し、後半に減少する。この雪面押し付け力の増加減少をタイミングより利用することによって、雪面の凸凹による体の不安体を安定化することができる。またスキ-板をはりとして、足首で力とモ-メントが働くとして人体とスキ-板の連成振動の解析モデルを作成した。ここで、人体の動きとスキ-板の形状、剛性などとタ-ンの関係が明らかになった。テニスに関してはボ-ルを一つの質点と一つのばね、ラケットを弾性はり、ガット面を一つのばね、腕を回転とねじり方向各3自由度のばね・質点系でモデル化した。ここで、腕のモデル化においては、腕をインパルス加振したときの各部の回転角加速度を計測し、時系列デ-タの最小自乗法によって各係数を同定した。そして数値計算によって、ボ-ルの飛距離、腕にかかる衝撃力の関係を明らかにした。また、ラケットの特性、すなわち曲げ剛さや、ガットのはり具合の影響についても検討し、このモデルがほぼ妥当なものであることがわかった。また、ラケットの構造の変化、すなわち重心位置とボ-ルの飛距離や手にかかる衝撃力の関係についても検討した。これらの研究により、人体の力学モデルの作製法およびスポ-ツ用具の解析法が確立されたので、これらを組み合わせることにより、人体の運動時の動特性、特に関節にかかる応力等を求める手法が得られた。