著者

木村 成竹 泉 聡志 酒井 信介

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.73, no.734, pp.1105-1110, 2007-10-25 (Released:2011-03-02)

参考文献数

6

被引用文献数

4 4

---

A spring washer is widely used as a method for preventing loosening. However, experimental results presented by Sakai and Yamamoto et al., show that the performance of a spring washer as a loosening prevention mechanism is at best equal to that of a washer-less joint, if not worse. In this paper we analyzed loosening under shear loading and as a result were able to explain the mechanism that accelerates loosening in the framework of the three-dimensional finite element method (FEM). A spring washer causes non-uniformity of contact pressure at the washer interfaces, because of its asymmetric shape. When a bolted joint with a spring washer is subjected to shear loading, sticking area on the contact surfaces of the spring washer is limited to two corner points before the bearing surface undergoes gross slip. One of these points is on the upper surface of the spring washer and the other is on the lower surface. In this situation the nut rotation around these sticking points results in drastic loosening. We also conducted comparative simulation with Sakai's experimental results. Compared with experimental results, the bolted joint with the spring washer is easy to loosen according to the simulation results. It is believed that the difference comes from the spring washer's edge cutting into the contact surface of the nut, something not included in this simulation.

著者

尾田 十八 坂本 二郎 坂野 憲一

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.71, no.701, pp.89-94, 2005-01-25 (Released:2011-08-16)

参考文献数

6

---

A woodpecker strikes its beak toward a tree repeatedly. But, the damage of brain or the brain concussion doesn't occur by this action. Human cannot strike strongly the head without the damage of a brain. Therefore, It is predicted that the brain of a woodpecker is protected from the shock by some methods and that the woodpecker has the original mechanism to absorb a shock. In this study, the endoskeltal structure, especially head part structure of woodpecker is dissected and the impact-proof system is analyzed by FEM and model experiment. From the results, it is obvious that the woodpecker has the original impact-proof system as the unique states of hyoid bone, skull, tissue and brain. Moreover it is considered that woodpecker has the advanced impact-proof system relating with not only the head part but also with the whole body.

著者

趙 希禄 胡 亜波 萩原 一郎

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.76, no.761, pp.10-17, 2010

参考文献数

11

被引用文献数

2 11

---

During car frontal crash, crash energy is absorbed by the parts of front bumper, front side member, front panel member and so on. Previous research has indicated that front side member plays major role in energy absorption. For protecting the passengers, the front side member is expected to absorb crash energy as much as possible. In this study, we adopt cylindrical thin-walled structure using origami engineering as front side member instead of structure with box-shaped cross section which is generally used. We develop an optimization system of the cylindrical thin-walled structure using origami engineering, in which the objective function is to maximize the energy absorption of origami structure; the design variables are structural parameter, number of divisional sections along axis, number of edges of polygonal cross section and number of subdivision levels; the mass and initial peak load of optimal structure must be less than those of structure with box-shaped cross section. We then discuss the optimization results that the optimal structure is capable of absorbing energy 91% more than that of original box-shaped cross sectional structure which is usually bended on the way of being crashed, 37% more than that of original structure which is ideally crashed to bottom without bending.

著者

西本 哲也 村上 成之 阿部 俊昭 小野 古志郎

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.61, no.591, pp.2386-2392, 1995-11-25 (Released:2008-02-21)

参考文献数

16

被引用文献数

7 6

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The purpose of this study is to understand the mechanical properties of the human cranium in order to develop a FEM simulation model of the head. Craniectomy samples, autoclave bone flaps and dry cadaver skulls were tested using values of radial bending moment considered typical in the case of head injury. In this study, we developed a procedure for estimation of the mechanical properties of the cranium by assuming a proportional relation between the bone mineral density and Young's modulus. The mechanical properties of the human cranium have been determined from the three-point bending test and the bone mineral density measured by the dual energy X-ray absorptiometry. The human cranium consisted of inner and outer tables (cortical bones) and a diploe (a cancellous bone). The stress on the cortical and the cancellous bones in the field of bending stress was assumed that the cranium was a beam in which two different materials were combined. The experiment showed that fresh cranial fractures start at the inner table and the diploe and then propagate to the outer table. The fracture of a cranium taken out of a human being will exhibit elastic-plastic fractures. This fact implies that the inner table and the diploe fractures can occur even if no fracture is detected using plain X-rays in cases of acute extradural hematomas (EDH).

著者

平島 健一 木村 清和 広瀬 幸雄

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.57, no.542, pp.2516-2522, 1991-10-25 (Released:2008-02-21)

参考文献数

7

---

By using the theoretical results for closed-form analytical solutions of in-plane problems inclusion under point forces, dislocations and so on, several numerical examples are shown by many graphical representations. The previous results published by several authors can be included as particular cases of our solutions.

著者

尾田 十八

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.46, no.409, pp.997-1006, 1980-09-25 (Released:2008-02-21)

参考文献数

5

被引用文献数

7 10

---

本報は竹材を自然界における一つの設計物体と考え, その幾何学的および材料組織的構造が外力条件といかなる関係にあるかを明らかにした. そしてその結果から竹材の構造が外力条件の変化に対応した柔なものであること, また各部の形状や組織がきわめて多くの機能を有し, したがって強度的な面からみても一つの目的に対し種々の最適化がなされた高度な構造組織を有しそれが工学設計システムにも応用されるべきことを明らかにした.

著者

三木 光範 大貫 正秀 杉山 吉彦 山口 哲男

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.59, no.564, pp.1985-1992, 1993-08-25 (Released:2008-02-21)

参考文献数

12

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Composite pipes with structurally unsymmetric laminated configurations (SULC pipe) shows coupled deformations upon bending and torsion. Our previous study treated the static behavior of the SULC pipes, and this paper deals with their dynamic coupling behavior. The coupled bending and torsional vibration of a cantilevered SULC pipe with an eccentric weight at its free end is analyzed, neglecting the mass of the pipe and assuming that it is an undamped free vibration system with two degree of freedom, transversal and rotational displacements. It is found that the SULC pipe has an elastic principal axis apart from its geometric principal axis, and the vibration becomes uncoupled when the center of gravity of the eccentric weight is located on the elastic axis of the pipe. The effects of the fiber orientation angles and the eccentricity of the tip weight on the vibration behavior are also analyzed considering the dynamic center of rotation. The analytical results show good agreement with the experimental results.

著者

村上 敬宜 高橋 宏治 山下 晃生

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.63, no.612, pp.1612-1619, 1997-08-25 (Released:2008-02-21)

参考文献数

21

被引用文献数

10 43

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In order to investigate the effect of surface roughness on fatigue strength, fatigue tests for a medium carbon steel, which was annealed and free of residual stress (HV≅170) and quenched and tempered (HV≅650). were carried out. To simulate the actual surface roughness, extremely shallow periodical notches with a constant pitch but irregular depth were introduced. The equivalent defect size √(area)R for roughness was defined to evaluate the effect of irregularly shaped roughness using the √(area) parameter model. The fatigue limits of the annealed medium carbon steel specimens with artificial surface roughness are much higher than those of the specimen with a single notch because of the interference effect of notches. The fatigue limits predicted by the √(area) parameter model are in good agreement with the experimental results.

著者

許 金泉 付 列東 武藤 睦治

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.68, no.672, pp.1266-1272, 2002-08-25 (Released:2008-02-21)

参考文献数

7

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The three dimensional theoretical solution of a normal concentrated forces on the free surface of a coating material is deduced by introducing the infinite mirror points of the load point and applying the Dirichlet's uniqueness theorem. The deduction is based on the basic equations of the spatial axisymmetric problems. It is found that all the stress functions corresponding to the mirror points, which satisfy the continuous conditions at the interface and the free boundary conditions at the free surface, can be deduced from the fundamental solution of a concentrated normal force on the free surface of a semi-infinite homogeneous solid. It is also found that only the stress functions corresponding to the first few mirror points have an influence on the accuracy of the theoretical solution. It is also found that the effect of material combination cannot be expressed by Dunders' parameters only. The stress field can be described by using Dunders' parameters together with the additional parameter.

著者

森 和也 陳 玳〓 西谷 弘信

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.57, no.544, pp.2987-2991, 1991-12-25 (Released:2008-02-21)

参考文献数

8

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The authers have developed a method for satisfying resultant boundary conditions on each divided boundary by discrete point forces. This method stands high accuracy and short calculating time at the same time. However, to obtain highly accurate solutions, it is necessary to put the point forces at the optimum locations. In this paper, the optimum location of point forces were obtained through several problems in 2D or 3D. The optimum location, that is, the optimum ratio of devided boundary length to distance between point force and boundary is 0.5∼0.7 in the case of notch problems and is 1.5 in the case of crack problems.

著者

田中 純夫 平島 健一 広瀬 幸雄 MURA Toshio

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.58, no.549, pp.745-752, 1992-05-25 (Released:2008-02-21)

参考文献数

11

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This paper presents an analysis of in-plane problems for isotropic semi-infinite body due to single force, single dislocation, dipole-force, dipole-dislocation, and so forth, with various surface boundaries such as free, fixed and two sliding conditions. Distributions of stresses and displacements under applied singular forces for the above four boundaries are illustrated by some graphical representations as numerical examples.

著者

馬渕 清資 藤江 裕道 佐納 義久

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.58, no.551, pp.1068-1072, 1992-07-25 (Released:2008-02-21)

参考文献数

20

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In the present study, the relationship between the femoral head diameter and the body weight of animals is shown. The diameter of femoral heads of fifteen terrestrial mammalian animals were measured directly from their skeletons. The body weight of these animals was referred from literature. Additionally, both the mean values of the femoral head diameters and the body weights of Japanese adult men and women were referred from the literature. The logarithm of femoral head diameter of these animals were plotted against the logarithm of body weight. The positive correlation was significant (p<0.01). The gradient of the regression line was 0.29. It showed that femoral head diameter is proportional to (body weight) 0.29. By analysis, we showed that this relationship can be deduced from the condition of uniform contact pressure or uniform performance of squeezed-film lubrication.

著者

後藤 真宏 西谷 弘信 宮川 浩臣 柳川 恭広

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.54, no.499, pp.497-502, 1988-03-25 (Released:2008-02-21)

参考文献数

13

被引用文献数

2 2

---

Using a series of base oils of different viscosity grades, rotating bending fatigue tests of 0.34 % C steel plain specimens were carried out to examine the effect of oil environments on the fatigue behavior. Although the effect of oil is hardly observed in one grain size crack initiation process, its effect appears in the crack propagation process. As the main effects of oil, two actions are considered ; that is, the isolation of the atmosphere and the oil wedging action. The propagation of a crack smaller than 0.1mm is controlled mainly by the former effect. For a crack larger than 0.1mm, its behavior is controlled mainly by the latter effect. On the other hand, the effect of oil on the fatigue limit is very small.

著者

谷村 眞治 王 虎 森田 浩章 海津 浩一 山崎 勝広 三村 耕司

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.61, no.586, pp.1344-1348, 1995-06-25 (Released:2008-02-21)

参考文献数

6

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The existence of critical impact velocity has been confirmed in experiments in which a sheet was perforated by a flying projectile. The experiments were performed to measure the values of parameters relevant to the normal impact of the cylinder against the sheets. By examining the relationship between the diameter of blanks and impact velocity, the phenomenon of the critical impact velocity was confirmed. The theoretical approach was also presented, for the same conditions as in the case of simple wave propagation, as in the Karman-Duwez solution. The comparison between theoretical examination and experimental results was also discussed.

著者

三村 泰成 吉村 忍 廣安 知之 三木 光範

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.69, no.683, pp.1066-1073, 2003-07-25 (Released:2008-02-21)

参考文献数

15

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This paper presents a new efficient real-coded genetic algorithms for constrained optimization. In general, it is efficient to use the gradient methods for the constrained optimization. However, because actual design problems often include extremely nonlinear or discontinuous characters, the gradient methods do not necessarily work well. Therefore, the present authors developed the "Center Neighborhood Crossover (CNX)" for real-coded genetic algorithms and applied to truss structure optimization. But, GAs have some fatal problems in handling the constraints. In the constrained optimization using GAs, designers have to translate the constrained problem to a basic unconstrained problem by using some methods such as the penalty function methods. It is, however, difficult to decide appropriate penalty parameters. In the present study, we developed "Real-coded Genetic Algorithms with Active Constraints (RGAAC)" In RGAAC, the points outside feasible area is pulled back to active constraints by the gradient method. The present method enables an efficient search.

著者

宗宮 詮 沢田 耕司 国尾 武

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.51, no.465, pp.1448-1452, 1985-05-25 (Released:2008-02-21)

参考文献数

11

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In this paper, the fatigue fracture process of FRP (SMC) was studied with a special attention to the variation of the stiffness ratio K which takes place during cyclic loading. Experimental results showed that the fatigue fracture process might be devided into the three characteristic stages, that is, (1) First stage (N=1∼N1) in which K dose not vary irrespective of cyclic loading, (2) Second stage in which the decreasing rate of the stiffness ratio defined by d(K)/d(logN) is constant, and (3) Final stage where the rapid decrease of the stiffness ratio at KIII leads to the final fatigue fracture. Furthermore, examination of scatters in experimental data at each stages by aid of probability plots showed that their distributions are the logarithmic normal ones. Also, it was found that the fatigue strength of SMC might be given by three characteristic parameters of N1, d(K)/d(logN) and KIII.

著者

酒井 忍 尾田 十八 米村 茂 坂本 二郎

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.73, no.734, pp.1177-1182, 2007-10-25 (Released:2011-03-02)

参考文献数

10

被引用文献数

2 1

---

In the United States and Japan, baseball is a very popular sport played by many people. However, the ball used is hard and moves fast. A professional baseball pitcher in good form can throw a ball at up to 41.7 m/s (150km/hr). If a ball at this speed hits the batter, serious injury is quite likely. In this paper we will describe our investigations on the impact of a baseball with living tissues by finite element analysis. Baseballs were projected at a load cell plate using a specialized pitching machine. The dynamic properties of the baseball were determined by comparing the wall-ball collision experimentally measuring the time history of the force and the displacement using dynamic finite element analysis software (ANSYS/LS-DYNA). The finite element model representing a human humerus and its surrounding tissue was simulated for balls pitched at variable speeds and pitch types (knuckle and fast ball). In so doing, the stress distribution and stress wave in the bone and soft tissue were obtained. From the results, the peak stress of the bone nearly yielded to the stress caused by a high fast ball. If the collision position or direction is moved from the center of the upper arm, it is assumed that the stress exuded on the humerus will be reduced. Some methods to reduce the severity of injury which can be applied in actual baseball games are also discussed.

著者

古賀 達蔵

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.46, no.411, pp.1280-1289, 1980-11-25 (Released:2008-02-21)

参考文献数

6

被引用文献数

2 3

---

周方向に閉じた薄肉弾性円筒かくについて, 古典かく理論の自由振動方程式および境界条件式から, 系統的な近似によって最小固有振動数を求める実用的な近似式を導く. 4)のとおりの境界条件の組合わせを検討し, 軸方向面内拘束条件のいかんによって五つの異なった特性方程式で分類されることを明らかにする. 一つは不伸長振動解を与え, ほかは軸線素ばりのたわみ振動の特性方程式と一致する.

著者

侯 培紅 茶谷 明義 放生 明廣 立矢 宏

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.63, no.609, pp.997-1001, 1997-05-25 (Released:2008-02-21)

参考文献数

10

---

A method for the determination of dynamic stress-strain relation of materials by means of instrumented Charpy impact testing technique was proposed and its validity was shown by some measured examples. The dynamic strengths of steels (S55C, SCM3, SUJ2, SK3) hardened from HV340 to HV850 by heat treatment were obtained from stress-strain relations measured by the present method. As a result, it was found that the yield strength of hard steels increases roughly linearly with increasing hardness and that under dynamic loading was 20∼30% higher than that under static one. Those strengths are also found to become maximum in the vicinity of HV700.

著者

平川 賢爾

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.71, no.702, pp.187-190, 2005-02-25 (Released:2011-03-02)

被引用文献数

1