著者

臺丸谷 政志 小林 秀敏

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:18848338)

巻号頁・発行日

vol.77, no.776, pp.638-646, 2011 (Released:2011-04-25)

参考文献数

18

被引用文献数

1 1

---

The Japanese sword is a weapon peculiar to Japan. The Japanese sword is interesting not only from the viewpoint of traditional crafts of arts, but also from the aspect of modern science and technology because the way of making and its functionality as a weapon are really consistent with science. The present study is concerned with the connection between tohshin (blade) and tsuka (hilt) of the sword. Only one mekugi-take (retaining peg made of bamboo) with about 5mm in diameter holds Nakago (tang) in the hilt. However the slender mekugi might not be broken, even though in the case of violent sword-fighting. This fact has been historically demonstrated in many battles by Japanese swords. In this study, using a Tachi being the typical Japanese sword, it is examined theoretically and experimentally from the viewpoint of impact engineering why a mekugi used in Japanese swords might not be broken. As a result, it is made clear that such a strong force as breaking mekugi-take does not act on it, because of the location of mekugi-ana (a hole for mekugi) in the tang, which has been made by the traditional code of sword-smiths.

著者

臺丸谷 政志

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:18848338)

巻号頁・発行日

vol.78, no.791, pp.928-933, 2012 (Released:2012-07-25)

参考文献数

9

著者

坂根 政男

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:18848338)

巻号頁・発行日

vol.77, no.779, pp.1078-1080, 2011 (Released:2011-07-25)

参考文献数

2

著者

杉本 一等

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:18848338)

巻号頁・発行日

vol.78, no.786, pp.213-222, 2012 (Released:2012-02-25)

参考文献数

21

被引用文献数

10 11

---

In the oscillating wear test under engine oil containing Mo-DTC (Molybdenum Dithio-Carbamate), friction coefficient and wear volume of cylinder-specimen were lower than without Mo-DTC, in contrast, DLC (Diamond-Like Carbon) film was worn deeply. A residue of oil contained amorphous carbon that had higher proportion of sp2 electron structure and lower density than DLC as coating. Judging by these results of our investigation, DLC film is graphitized in wear test under lubrication. This specific wear of DLC films is based on the wear mechanism that is attributed to graphitization, and the hard molybdenum sulfide and oxide which are decompositions of Mo-DTC are accelerated wear mechanically.

著者

真鍋 匡利 山田 崇恭 泉井 一浩 西脇 眞二

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:18848338)

巻号頁・発行日

vol.77, no.784, pp.2054-2066, 2011 (Released:2011-12-25)

参考文献数

35

被引用文献数

1 3

---

Topology optimization for structures has been applied to nonlinear structural problems, however conventional topology optimization methods for structures with geometrical nonlinearity encounter difficulties during nonlinear analysis using the FEM (Finite Element Method), due to the use of a mesh. In this study, we propose a new level set-based topology optimization method considering geometrical nonlinearity using a mesh-free/particle technique, for optimizing elastic structures that undergo large deformation. In the proposed method, the MPS (Moving Particle Semiimplicit) method, a particle method, is used for the response analysis, since it does not rely on a mesh for geometrically nonlinear analysis. In this paper, first, a topology optimization problem is formulated based on the level set method and a method for regularizing the optimization problem by the Tikhonov regularization method is explained. The reactiondiffusion equation that updates the level set function is then derived and an optimization algorithm, which uses the FEM to solve the equilibrium equations and the reaction-diffusion equation when updating the level set function, is constructed. Next, the particle interaction model and the treatment of geometrical nonlinearity in the MPS method are shown, and the implementation of combining the level set-based topology optimization and the MPS methods is explained. Finally, several numerical examples are provided to demonstrate the effectiveness of the proposed method of topology optimization for geometrically nonlinear problems.

著者

高橋 由紀夫 戸村 典章

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:18848338)

巻号頁・発行日

vol.78, no.790, pp.799-803, 2012 (Released:2012-06-25)

参考文献数

7

---

Japan Society of Mechanical Engineers has developed various guidelines in relation to structural integrity of nuclear and fossil power plants. The guideline for evaluating modes and consequences of potential failure in particular part of piping system in nuclear power plants is one of them. Main part of this procedure is dedicated to the evaluation of likelihood of leak-before-break behavior and evaluation of leak rate. Leak-before-break evaluation requires prediction of fatigue crack growth from a prescribed initial flaw until penetration, calculation of crack length providing detectable leak as well as that causing unstable fracture. Specific guidance is given for each part. This paper discusses the scope and the outline of the present guideline.

著者

河越 正羽 水谷 義弘 轟 章 松崎 亮介 安岡 哲夫

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:18848338)

巻号頁・発行日

vol.79, no.801, pp.555-562, 2013 (Released:2013-05-25)

参考文献数

27

被引用文献数

1 3

---

In this study, a new welding method which utilizes conductivity of CFRTP (Carbon Fiber Reinforced Thermo-Plastic) is proposed. Electrical current is applied through the CFRTP single-lap joints in thickness direction. Since resistance of joining surface is the highest in the current path, the joining surface is preferentially heated by Joule heating. In this study, spot welding and surface welding were conducted. By applying constant voltage of 5.0V or 10.3V, the joint-surfaces were heated above melting temperature Tm of the material and were welded. In order to evaluate lap-shear strength (LSS) of welded joints, tensile lap-shear strength tests were conducted. As a result, the tensile lap-shear true stress of spot welding is 31.0MPa and LSS of surface welding is 22.0MPa. These strengths were comparable to those that were welded by traditional resistance welding method. It is also found that LSS is changed with welding pressure of joint parts.

著者

山本 憲隆 戸田 祐輔

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:18848338)

巻号頁・発行日

vol.79, no.800, pp.433-441, 2013 (Released:2013-04-25)

参考文献数

27

被引用文献数

2 2

---

Fibrils were isolated from rat tail tendons and tensile tests of the fibrils were performed in the air (dry) condition or in the physiological saline solution (wet) condition. After the fibrils were immersed in the physiological saline solution for 3 and 30 minutes, the fibrils were stretched to failure. There were no significant differences in the tensile properties between 3 and 30 minutes. These results indicate that the fibrils were sufficiently hydrated by the immersion of 3 minutes. The fibrils immersed for 3 minutes showed the tensile strength of 111±31 MPa (Mean±S.E.), strain at failure of 32.1±4.5 %, and tangent modulus of 350±53 MPa. Next, the fibrils were stretched to failure in the air. The dry fibrils showed the tensile strength of 702±137 MPa, strain at failure of 30.4±8.5 %, and tangent modulus of 2720±840 MPa. The tensile strength and tangent modulus of the dry fibrils were significantly larger than those of the wet fibrils. There were no significant differences in the strain at failure between the dry and wet fibrils. These results point to the great importance of water for the tensile properties of collagen fibrils.

著者

岡 正徳 都井 裕

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:18848338)

巻号頁・発行日

vol.79, no.806, pp.1411-1421, 2013 (Released:2013-10-25)

参考文献数

18

被引用文献数

1 1

---

The elasto-viscoplastic-creep constitutive equation based on the concept of continuum damage mechanics is formulated for the gray cast iron as used in diesel engine parts. It employs the viscoplastic strain given by Chaboche-Rousselier and the creep strain given by Perrin and Hayhurst. A part of the material parameters contained in the creep constitutive equation which was previously identified by Oka and Toi are assumed to be temperature-dependent in the present study. The identified model is applied to the creep fatigue life prediction of the cylinder head used in diesel engine parts which is made of gray cast iron. Although there are some points to be improved, the validity of the proposed model is illustrated by comparing the calculated results with the experimental results for the crack initiation locations and the crack propagation directions.

著者

相場 一希 大宮 正毅 射手矢 岬 紙谷 武 戸松 泰介

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:18848338)

巻号頁・発行日

vol.78, no.796, pp.1631-1641, 2012 (Released:2012-12-25)

参考文献数

16

被引用文献数

2

---

Beginning in 2012, judo has been selected to be a compulsory course in junior high schools in Japan. However, the number of participants, in particular beginners, who die or are injured in judo is higher than that for other sports. For this reason, there is a fear that there will be a drastic increase in the number of judo-related accidents leading to death or injury in junior high schools. The most serious form of head injury is acute subdural hematoma (ASDH). The purpose of the present study is to compare ASDH occurrence indices and to evaluate the effectiveness of using head protectors. Based on measurements of head acceleration during falling, the Head Injury Criterion (HIC), maximum angular acceleration and angular velocity variation range were calculated. The results indicated that the relative displacement between the brain and skull was most strongly correlated with the angular velocity variation range, which is thus a candidate evaluation index for ASDH. The results also suggest that in order to prevent ASDH, a head protector should be made of shock absorbing materials with a small coefficient of restitution, so as to reduce the rebound velocity of the skull after occipital impact.

著者

高野 敦 松林 三和子 松田 淑男 高野 千尋 小畑 貴稔 森川 洋

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:18848338)

巻号頁・発行日

vol.79, no.801, pp.682-690, 2013 (Released:2013-05-25)

参考文献数

22

被引用文献数

1

---

A high strength bolt fastening system for satellite structures has been developed. This fastening system enables high frictional strength by adopting titanium bolts with high strength and low torque-coefficient, as well as shims with high friction coefficient. Low torque-coefficient of the titanium bolts is achieved by PTFE (Polytetrafluoroethylene) solid-film lubricant, which is coated on the bolts. High friction coefficient of the shim is achieved by surface roughening by etching. To verify the design of the fastening system, long-term preload test, torque-coefficient test and vibration loosening test (Junker's test) were conducted and successfully completed. In addition, the fastening system was applied to a development model of satellite structure and was verified by mechanical environmental tests (static load test, system vibration test and thermal vacuum test). The observation showed no evidence of slip or alignment deviation. Thus, a conventional reamer-bolted-fastening system can be replaced with the developed high strength bolt fastening system that saves manufacturing period of satellites and furthermore enables the satellites to be competitive in terms of cost, delivery and performance.

著者

高野 敦 松林 三和子 松田 淑男 小畑 貴稔 森川 洋

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:18848338)

巻号頁・発行日

vol.79, no.804, pp.1201-1209, 2013 (Released:2013-08-25)

参考文献数

13

被引用文献数

1 2

---

Long-term measurement and prediction for Ti-6Al-4V and A286 bolts was conducted. It was pointed out that Ti-6Al-4V indicates significant creep behavior and accumulated large creep strain and thus Ti-6Al-4V can not be applied for preloaded bolts. In addition, preload relaxation due to creep of solid-film lubricants for bolts and fastened aluminum parts were also pointed out. Recently, the authors developed a high strength bolted fastening system for satellite structures with PTFE (polytetrafluoroethylene) solid film lubricated Ti-6Al-4V bolts and aluminum threadedand drilled-hole parts. The authors, hence, measured the preload of the fastening system for 253-days, predicted 30-years later preload, and confirmed that the preload reduction was not harmful.

著者

橋村 真治 山田 直樹 戸田 均

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:18848338)

巻号頁・発行日

vol.78, no.791, pp.1013-1022, 2012 (Released:2012-07-25)

参考文献数

10

---

In this study, influence of nut configuration on fatigue characteristic of bolt/nut assembly under transverse vibration has been investigated. In the experiments, the apparent fatigue limits were investigated for two bolt/nut assemblies tightened with a flange nut and a tapered nut. The results showed that the apparent fatigue limit of the bolt/nut assembly tightened with the tapered nut was higher than that of the flange nut. Its causes were revealed by FE Analyses. As the result, it could be seen that a difference of nut inclinations when the assembly received the transverse load caused the difference of fatigue limits. It was also seen that the nominal stresses at root of the first thread were different even if the same transverse load was applied to the bolt/nut assembly.

著者

蓮沼 将太 宮田 陽平 仁田 祐輝 小川 武史

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:18848338)

巻号頁・発行日

vol.78, no.786, pp.161-170, 2012 (Released:2012-02-25)

参考文献数

8

被引用文献数

8 8

---

In this study, low cycle fatigue tests were conducted for carbon steel, STS410, low alloy steel, SFVQ1A and austenitic stainless steel, SUS316NG, in order to investigate surface and internal fatigue crack growth characteristics. The tests were conducted under repeated two-step variable amplitude straining conditions to appear beach marks of cracks on the fracture surface. In these tests, periodical surface removal was conducted to suppress surface fatigue cracks to be a main crack which led final fracture. STS410 specimen under surface removal test was not broken until its diameter became too small. There was a defect observed on the section of the specimen cut longitudinally. Cracks initiated from internal inclusion for SFVQ1A and SUS316NG and those fatigue lives were slightly larger under surface removal test compared to those under no surface removal tests. Internal crack growth rates calculated from beach marks were similar to those of surface cracks under the same crack driving force or J integral range, ΔJ.

著者

山敷 拓也 羽賀 俊雄 熊井 真次 渡利 久規

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:18848338)

巻号頁・発行日

vol.79, no.804, pp.1156-1160, 2013 (Released:2013-08-25)

参考文献数

5

---

A vertical type high speed twin roll caster is able to cast an aluminum alloy strip directly from a molten metal that is poured between the rotating rolls. However defects such as small cracks and unsound thickness distribution of the cast strip occur at faster roll speed. They are related to the contact condition of the roll surface and the melt. In the present study, we used the grooved roll to eliminate the defects, and to save the cost at the same time. We experimented using several grooved rolls with different patterns. When the groove width was 0.45mm; depth 0.2mm; pitch 0.1mm and 1.0mm, stable casting was possible. The shape of bulge was formed on the cast strip surface by the grooved roll. As a result of the color check, the grooved roll could eliminate the small cracks. The surface condition of the strip was more sound using the grooved roll with the pitch of 0.1mm than that of 1.0mm. Stopping the rotated roll during the casting, we observed the contact condition between the melt and the roll, and confirmed how the bulge was formed. To cold-roll for strip with bulges was possible and the bulges was erased. To cast for the sound strip was possible by the vertical type high speed twin roll caster with grooved rolls.

著者

田中 啓介 鈴木 健太 藤井 貴之 渋江 隆治 藤山 一成

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:18848338)

巻号頁・発行日

vol.79, no.799, pp.266-280, 2013 (Released:2013-03-25)

参考文献数

14

---

Fatigue crack propagation tests of center-notched plates of lead-free solder were conducted under displacement-controlled conditions with mean strain and load-controlled conditions with mean stress. The J-integral range was evaluated from load-displacement curves by using the simple estimate method. The mean stress introduced by the initial (mean) tensile strain in displacement-controlled tests was relaxed very quickly with cycles. The crack propagation rate was nearly constant during crack extension and was not much influenced by the mean strain. The crack closure did not take place under tensile mean strains, while it occurred under compressive strains. In load-controlled tests with mean stress, the ratcheting deformation was accumulated during fatigue tests. The crack propagation rate increased with crack length, and was not influenced by the tensile mean stress. The crack propagation rate was lower as the mean compressive stress was larger and as the stress range was lower. The crack closure took place only for the cases of compressive mean stresses. When the J-integral range was evaluated by taking into account of crack closure, the crack propagation rate was expressed as a power function of the J-integral range for all cases examined, The effective fractions of the applied load, strain and J-integral were unity for zero and positive mean stresses. They deceased linearly with increasing mean compressive stress down to -4 MPa, and remained nearly constant below -4 MPa.

著者

長島 伸夫 早川 正夫

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:18848338)

巻号頁・発行日

vol.79, no.797, pp.23-33, 2013 (Released:2013-01-25)

参考文献数

24

被引用文献数

3 2

---

Micro-hardness distribution was measured by using an ultra-micro hardness test at a crack tip under a plane strain condition for a crack propagation test specimen made of a low-carbon austenite stainless steel JIS-SUS316L. Moreover, crystal orientations were analyzed by EBSD for individual crystal grains in the plastic strained area at the crack tip. The conclusions can be summarized as follows. (1) The mean strain in a 500-μm region around the crack tip was supposed with 3% from the hardness distribution in an ultra-micro hardness test. Therefore, the plasticity strain distribution of the crack tip under a plane strain condition can be visualized based on the ultra-micro hardness and an experience equation of the true strain by measuring the hardness distribution. (2) When the analysis by EBSD increased the step size of the KAM map, the local misorientation increased. On the other hand, the color map of some grain boundary neighborhoods reversed when the step size changed in a GROD map. Therefore, an analysis of KAM is suitable for the local transformation of the crack tip neighborhood. (3) From the results of an EBSD analysis, it became clear that a local heterogeneous transformation occurred in random grain boundaries at the crack tip, and the transformation hardly occurred at the CSL grain boundary of the crack tip.

著者

笠原 直人 林 眞琴

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:18848338)

巻号頁・発行日

vol.78, no.789, pp.583-598, 2012 (Released:2012-05-25)

参考文献数

39

被引用文献数

1

---

Various kinds of thermal fatigue failure modes exist in nuclear power plant components. Main causes of thermal loads are structural responses to fluid temperature changes. These phenomena have complex mechanisms and so many patterns, that their problems still occur even though well-known issues. Among them, this paper treats high cycle thermal fatigue of branch pipes as the typical mode. Firstly, experimental and analytical researches are explained for thermal load evaluation. Through them, both numerical and kinematic methods were developed. Next chapter describes thermal fatigue strength studies on both crack initiations and propagations. They revealed the similarities of thermal crack initiations with mechanical ones and frequency characteristics of crack propagation. Finally, current status and future challenges are discussed for evaluation of actual plants.

著者

古巣 克也 尼子 龍幸 中川 稔章 浜辺 勉 青木 典久

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:18848338)

巻号頁・発行日

vol.79, no.801, pp.573-581, 2013 (Released:2013-05-25)

参考文献数

12

被引用文献数

2 8

---

Recently, high strength steel material is used increasingly for plates which constitute the frame structures of vehicles. Since these plates become thinner, the buckling on the plates has been recognized as an important issue for automotive industries. In this paper, the expression is derived to obtain simply the shear stress on plates at torsional buckling for the box beams which represent the frame structure. Assuming the deflection shape of the buckled plate simply supported on all sides and the right angle at four corners, the precise expression is derived based on the energy method. However, this expression is complicated and hard to use easily. Therefore, the approximate expression is proposed by the knowledge from the aforementioned derivation. The accuracy of that expression is investigated as compared with the results acquired in the buckling eigenvalue analysis by FEM. As the results, the difference of shear stress at torsional buckling is less than about 5% as for the aspect ratio of the cross section between 0.4 - 1.0.

著者

戒田 拓洋 最上 雄一 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:18848338)

巻号頁・発行日

vol.77, no.777, pp.731-735, 2011 (Released:2011-05-25)

参考文献数

5

---

In order to rationalize the safety margin of pressurized components subject to local metal loss, we applied a probabilistic reliability method. The modeling of the local metal loss is based on API 579-1/ASME FFS-1 and we investigated the safety margin for the pressure equipment subjected to local metal loss utilizing the actual corrosion rate data. Probabilities of failure of both shallow metal loss and deep metal loss were calculated. These results showed the relation between time until next inspection and probability of failure was cleared. We also analyzed the sensitivity of an assessment curve based on the reliability index for local metal loss. The reliability-based assessment curve was available regardless of COV of the shape of metal loss.