著者

今井 康文 森田 英毅 高瀬 徹 古賀 博之

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.55, no.509, pp.147-151, 1989-01-25

被引用文献数

7 7

---

Time-dependent thermal stress singularities at a semi-infinite crack tip associated with a transient temperature field have been analyzed on an infinite plate with a point heat source near the crack tip. As the heating begins, a mode I singularity increases gradually with time, but, after showing its maximum, decreases to be negative. This singularity variation causes a crack to start growing at some instance, but soon after to stop. That is, crack growth may be controlled, which is desirable for a cutting device for brittle materials. Deflection of a heating point from a crack line results in a mode II stress singularity, which also leads a crack to swerve from the original crack line. In an experiment using glass plates, a crack was successfully controlled to grow and also to branch in any angle toward the heat source as long as the heating location was kept appropriately apart from the crack tip.

著者

徳田 貴志 河合 浩志 岡田 裕 福井 泰好

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.76, no.770, pp.1255-1262, 2010-10-25

被引用文献数

3

---

Although three-dimensional finite element analysis has become a common tool in the industries to perform their design analyses, there still exist some difficulties in performing three-dimensional fracture analyses. One of them is that although automatic mesh generation techniques are available for tetrahedral finite elements, hexahedral finite elements are commonly used in three-dimensional crack analyses. The other is that the analysis models tend to be large in their scales. Therefore performing a three-dimensional fracture analysis takes much manual labor in the analysis model generation processes and computational time. In present research, the authors have been developing a fracture mechanics analysis system that minimizes the manual labor. The key components in the analysis system are a mesh generation software and the virtual crack closure-integral method (VCCM) for the second-order tetrahedral finite element to evaluate the crack parameters (the energy release rates and the stress intensity factors). Based on them, the software system was carefully designed to handle large scale analysis model. In this paper, as the first report, the outlines of the system and the finite element model procedures are described.

著者

西岡 俊久 小林 豊 Epstein S. J.

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.59, no.561, pp.1319-1326, 1993-05-25

被引用文献数

2

---

Finite element simulation was carried out for inhomogeneous elastic-plastic fracture specimens, which consist of A533B steel and HT80 steel. These two materials have considerably different yield stresses, although their elastic properties are exactly the same. The nonlinear fracture parameter, T^* integral, was extended for inhomogeneous multilayer materials. The T^* integral for inhomogeneous materials demonstrates excellent path independence, even in the stages of large plastic deformations around the crack tip and the material interface. Numerically generated moire fringe patterns are in good agreement with experimentally recorded patterns. The shapes of plastic zones appearing in the specimens reveal large inhomogeneity effects.

著者

西岡 俊久 西 正己 藤本 岳洋 坂倉 慧悟 Epstein S. Jonathan

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.59, no.559, pp.558-565, 1993-03-25

---

In order to investigate inhomogeneity effects in elastic-plastic fracture, A533B steel and HT80 steel, which have considerably different yield stresses, were chosen. The moire interferometry was used for direct measurements of the crack-tip behavior in the homogeneous CT specimens of A533B and HT80, and in electron-beam-welded inhomogeneous CT specimens of these two materials. Two-dimensional moire gratings with relatively low frequency of 300 lines/mm were used to follow large plastic deformations. The near-tip deformations were compared with the corresponding HRR singular fields. Large inhomogeneity effects were observed in the moire fringe patterns as plastic deformations proceed.

著者

小川 和洋 庄子 哲雄 青木 久彦 藤田 範生 鳥越 泰治

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.647, pp.1370-1376, 2000-07-25

被引用文献数

4 2

---

A two-layer plasma sprayed thermal barrier coating on Ni base superalloy substrate was characterized. The coating was comprised of an inner layer of MCrAlY bond coating and an outer layer of 8wt% yttria stabilized zirconia (YSZ) thermal barrier coating (TBC). After aging, the reaction layer at interface between YSZ and MCrAlY was observed. The reaction layer had two different contrast layers in the SEM images. One was black which was closer to MCrAlY and the other was gray which was closer to YSZ. The thickness of both layers increased with aging. Also countless porosities at the gray layer and microcrack at YSZ were observed. Most of the macrocrack grew through the porosities. From this viewpoint one may say that the mechanism of macrocrack formation is a deterioration of adhesion which was accompanied by an increase of the porosities or the microcrack.

著者

長嶋 利夫 大本 洋平 谷 周一

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.70, no.691, pp.383-390, 2004-03-25

被引用文献数

1

---

Conventional FEM requires that the boundary of the element just matches the crack line to perform stress analyses of structures containing cracks in the field of fracture mechanics. These modeling processes are rather complicated and cannot be performed easily even if the automatic mesh generation technique is utilized. Recently, Belytschko et al. proposed the extended finite element method (X-FEM) based on the concept of partition of unity, and applied this method to the evaluation of the stress intensity factors and perfoming the crack extension simulation. The X-FEM can be used to simplify the modeling of continua containing several cracks and hence perform effective stress analyses related to fracture mechanics. This paper describes the two-dimensional thermal stress analysis of structures containing cracks. Stress intensity factors having mixed modes coupled with mode-I and mode-II are evaluated by M_1-integral method in conjunction with X-FEM. This method is examined in numerical examples of elastic and thermo elastic analyses. The numerical results show that X-FEM is an effective method for performing thermal stress analyses and evaluating stress intensity factors.

著者

長嶋 利夫 三浦 直樹

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.719, pp.974-981, 2006-07-25

被引用文献数

2

---

The extended finite element method (X-FEM), which can model the domain without explicitly meshing the crack surface, can be used to perform stress analyses for efficiently solving fracture mechanics problems. In this study, the constraint condition enforcement for X FEM analysis considering symmetry is presented. Since the interpolation functions utilized in X FEM analysis include the enrichment basis functions, the freedoms of the node on the symmetric plane should be constrained properly in X-FEM model with symmetric conditions. Moreover evaluation of the energy release rate by the domain integral method should be performed considering symmetry conditions. In this paper the constraint conditions for three dimensional X FEM analysis considering symmetric conditions are summarized and the numerical examples using symmetric X FEM models are shown. The proposed procedure can be used to perform efficient X FEM analyses of practical fracture problems.

著者

許 金泉 武藤 睦治 付 列東

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.68, no.672, pp.1259-1265, 2002-08-25

被引用文献数

1 7

---

The theoretical solution of a concentrated force on the free surface of a coating material is deduced by introducing the infinite series mirror points of the load point and applying the Dirichlet's uniqueness theorem. In this study, the two dimensional solution is deduced in details by using the infinite series of the Goursat's stress function corresponding to every mirror point. It is found that the stress function corresponding to a higher order mirror point can be determined from that corresponding to a lower one, therefore, all the stress functions can be determined from that corresponding to the first order mirror point which is in fact the stress function for concentrated forces on the free surface of a semi-infinite body. It is also found that the contribution of the stress function to stress distribution decreases as the increasing of the corresponding order of the mirror point. It is confirmed that only the stress functions corresponding to the first several mirror points have an influence on the accuracy of theoretical solution. This theoretical solution can be expected to be very useful in evaluating the strength of coating materials or other surface modificated materials.

著者

岸田 路也 佐々木 一彰 町野 史郎

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.57, no.533, pp.181-187, 1991-01-25

---

This paper describes the accuracy of surface integrals in the indirect boundary integral method containing singular integrals. Here, the surface integral is carried out directly and numerically by the use of Simpson's and Legendre-Gauss's quadrature formulae. Also, the line integral, obtained by applying Gauss-Ostrogradskii's transformation to the surface integral, is examined. The accuracy is evaluated by the convergence behaviors of surface and line integrals and by the comparison with the analytically obtained integral values.

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

---

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

---

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

---

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

---

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

藤田 祥子 尾上 雅人 浅野 明雄 佐藤 良一

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.63, no.606, pp.335-340, 1997-02-25

参考文献数

8

被引用文献数

1

---

Stresses and stiffnesses of band adhesive box section beams subjected to torsional loads have been studied analytically. The influences of pitches and width and thickness of the adhesives on the stress distributions and the torsional rigidities were investigated analytically and numerically. Maximum shear stress in the adhcsives occurs at an intersection of the adhered boundary and the inner edge of flange, and it decreases with increase in the width and thickness of the adhesives. The analytical results were consistent with the results of finite element methods.

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

著者

仲町 英治 三木 一生 古川 一憲 武川 雄一 土井 哲平

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 = Transactions of the Japan Society of Mechanical Engineers. A (ISSN:03875008)

巻号頁・発行日

vol.71, no.701, pp.73-79, 2005-01-25

参考文献数

9

被引用文献数

2

---

In this paper, a new head injury criterion evaluated by the hydrostatic stress occurred in the head crash phenomenon. In order to obtain the threshold value for brain's organ and tissue, <I>in vitro</I> impact experiments to cultured nerve cells were performed. PC-12 cultured nerve cell was employed to imitate the human's nerve cell. In the experiments, various pressure waves were generated by introducing different heights of dropping weight for impacting. Relationships between peak values of impact compressive and expansive pressure waves and detachment rates and injury rates evaluated by the cell membranes damage were obtained.