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

---

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

浜田 実 渋谷 陽二

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. A編 (ISSN:03875008)

巻号頁・発行日

vol.50, no.452, pp.584-592, 1984-04-25

---

複数の自由縁の円孔を持つ円板の曲げ問題の解法として,極座標に対する重調和方程式の一般解を繰返し用いる方法を提案し,これにより,偏心位置に1円孔または対称位置に等大2円孔を持つ円板の外縁に一様曲げモーメントが作用する場合と,中央集中荷重が作用する場合の解を求める.また有限要素法と実験による結果と本解とを比較することにより,本解の妥当性を確かめる.

著者

久森 紀之 野末 章 木村 雄二

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. A編 (ISSN:03875008)

巻号頁・発行日

vol.67, no.657, pp.844-851, 2001-05-25

被引用文献数

2

---

High-temperature and high-pressure water corrosion behaviors of Y_2O_3 doped Zirconia (ZrO_2) were investigated in term of with the microstructural changes, residual strength characteristics and tetragonal to monoclinic phase transformation. Sintered ZrO_2 ceramics bodies with 2, 3, 4, 6 and 8 mol% Y_2O_3 doped ZrO_2 were made using a pressure less sintering method at 1 450℃, respectively. These ZrO_2 ceramics were corroded in high-temperature and high-pressure water condition such as 150℃〜300℃. Corrosion damage of the decrease Y_2O_3 dope ZrO_2 ceramics occurred preferentially on ZrO_2 particle after long-term immersion in high-temperature and high-pressure water environment. The tetragonal to monoclinic phase transformation occurred in decrease Y_2O_3 doped tetragonal ZrO_2 ceramics due to high-temperature and high-pressure water corrosion. For improvement of the corrosion characteristics (thermal stability) of the ZrO_2 ceramics, are important increasing the Y_2O_3 doped within a range in which no remarkable residual strength degradation is recognized. CeO_2 doped ZrO_2 ceramics were useful to improvement the thermal stability of Y_2O_3 doped ZrO_2 without loss of the fracture strength. CeO_2 doped ZrO_2 ceramics also have superior residual strength characteristics compared to Y-ZrO_2 ceramics. In addition design concepts used to obtain water-corrosion-resistant high strength and high toughness ZrO_2 ceramics were proposed.

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

日本機械学會論文集. A編 (ISSN:03875008)

巻号頁・発行日

vol.73, no.734, pp.1105-1110, 2007-10-25

被引用文献数

1 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

渡辺 浩志 久田 俊明 野口 裕久

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.59, no.557, pp.183-190, 1993

被引用文献数

4 1

---

'Kinking' is known as an unstable behavior of a twisted slender rod, which occurs after the torsional buckling. It is simulated by a hyper-elastic finite element code developed by the authors, with hexahedral solid elements. The mechanical characteristics and the criterion of the kinking are successfully discussed. An incompressible constraint to model a rubber-like material is introduced in the simulation by the Lagrange multiplier method and the penalty method. It is found that the former method is computationally more efficient in the case of extremely large deformation such as kinking.

著者

菊池 正紀 矢野 一範 田村 敏功

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.56, no.524, pp.831-837, 1990

---

Surface-cracked specimens are analyzed precisely using the three-dimensional finite element method, and the stress fields at the crack tip are compared with HRR solution. First, a plate with a surface crack subjected to a bending load is analyzed. It is shown that the stress field does not agree well with the HRR solution when the crack depth is not large. But as the crack depth increases, the stress field becomes nearer to the HRR solution. It is also shown that a displacement field similar to the HRR solution exists in a small region wheich is very near to the crack tip. Then the surface crack in a pipe is analyzed. The results show that the stress field is significantly different from the HRR solution. The reason for this difference is considered to be the difference of the stress distribution in the ligament of the specimen.

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

---

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

丸山 俊則 田口 真 岸田 和人 熊本 秀喜 吉川 孝男

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. A編 (ISSN:03875008)

巻号頁・発行日

vol.67, no.664, pp.1948-1954, 2001-12-25

参考文献数

8

被引用文献数

3 3

---

In these days, crashworthiness design has been required more frequently in rail vehicle. The results of static strength test of an end underframe that absorbs most of the crash energy were presented, as well as numerical simulations. By comparing both results, the numerical simulations were found to be adequately accurate. Then, a new and highly crashworthy structure was proposed. Both of the test and the numerical simulation confirmed that the structure worked well to absorb the crash energy. Further, effects of welding strength, geometrical initial imperfection, and strain rate on the crashworthiness were discussed. Especially, strain rate effect of materials is important to evaluate crashworthiness accurately.

著者

荒井 正行 佐久間 俊雄 岩田 宇一 山田 隆之 中村 一義 岸本 喜久雄

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. A編 (ISSN:03875008)

巻号頁・発行日

vol.66, no.641, pp.144-150, 2000-01-25

被引用文献数

1 3

---

The surfaces of many industrial products, such as a holl drill, gas turbine engine and so on, are coated with diamond and ceramic material for improving the material properties.On the other hand, the surface may accumulate an oxidation layer by reaction of oxygen with inceasing time.These Common damage, in service, is "delamination".It is known that the delamiation will be caused by compressive stress in these coating layer which is generated by vibration and fatigue loading for industrial coating, and volume expansion for oxidation.The actual coating delamination process as follow had been clarified by many studies.The coating layer is buckled locally by compressive loadingand is then delaminated along the substrate.The aim of this study is to clarify the coating delamination mechanism under compressive stress by observing continuously buckling and delaminating process in the coating layer, which is modelled by engineering plastic in this study. The delamination evaluation method is proposed based on an interface mechanics, and an accuracy of the evaluation is examined using finite element analysis.Finally, the proposed evaluation are applied to the experimental results obtained by this study.

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

---

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

長谷川 恵一 安藤 清 北出 正司 坂本 光正 福島 幸夫 沖田 耕一

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.61, no.588, pp.1713-1718, 1995-08-25

参考文献数

8

被引用文献数

2

---

The LE-7 rocket engine main injector has undergone a few occurrences of welded joint structural failure because it is subjected to high thermal stress during the engine start and stop sequence. The low-cycle fatigue test and high-strain fatigue test which were conducted as part of failure analysis revealed that the welded joint has a considerably shorter fatigue life than expected. To improve the ductility and toughness of the welded joint, high-temperature-solution heat treatment was applied after welding. The low-cycle fatigue life of a welded joint subjected to this solution heat treatment became three times longer than that without it. A design criterion was established for low-cycle fatigue life estimation, and the life requirement was found to be satisfied.

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

---

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

---

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

---

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

高尻 雅之 白川 寿照 宮崎 康次 塚本 寛

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. A編 (ISSN:03875008)

巻号頁・発行日

vol.72, no.723, pp.1793-1798, 2006-11-25

参考文献数

27

被引用文献数

8

---

n-type bismuth-telluride thin films are fabricated by flash evaporation method. Effects of hydrogen annealing on the thin films are investigated for potential application in micro thermoelectric devices. The thin films are grown up to 1 μm on a glass substrate by flash evaporation method. The hydrogen annealing is carried out in the temperature range between 200-350℃ on an atmospheric pressure. The electrical resistivity and Seebeck coefficient are measured at room temperature. Both the electrical resistivity and Seebeck coefficient are improved by the treatment of hydrogen annealing, then the power factor of the n-type bismuth-telluride thin film reaches 8.8μW・cm^<-1>・K^2 at annealing temperature of 350℃. The structure of the thin films, which is composition and crystallinity, is studied by electron probe micro analyzer and X-ray diffraction pattern, respectively. The composition of bismuth-telluride thin films is relativity constant until higher annealing temperature. The X-ray diffraction patterns indicate that the crystallinity of the thin films is improved as higher annealing temperature.