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

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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

瀧本 昭夫 増田 芳則 小田 直樹 吉松 敦宏

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.54, no.508, pp.2135-2142, 1988

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Fracture tests of unsaturated polyester resin on large, single-edge notched-bend specimens were conducted under static and dynamic bend tests at room temperature. The velocity of a loading point in the three-point bending was changed from 8.3&times;10<SUP>-6</SUP>mm/s to 7&times;10<SUP>5</SUP> times its value. The two types of fracture marks of the both-ends-closed mark (like ellipses) and the one-end-opened mark (like parabolas) were observed and they were expressed by the equation of fracture marks. A rocket mark, defined here, was also often observed in the dynamic bending test and was well-approximated by the equation. The experimental number, percentage, relative interference appearing distance and the calculated relative critical distance of the marks changed with the crack propagation distance and the testing speed. The velocity of a primary crack propagation was measured and approximated by a mixed-condition relation proposed by us. This change and the gammer-letter relation between the velocity and a dynamic stress intensity factor K<SUB>D</SUB> (or a dynamic strain energy release rate, S<SUB>D</SUB>) gives the latter (K<SUB>D</SUB> or S<SUB>D</SUB>) as a function of the crack propagation distance. This provides a good theoretical explanation of the above variations of fracture marks.

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

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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

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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

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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

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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.

著者

三木田 嘉男 中林 一朗

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.53, no.487, pp.475-482, 1987

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Quench cracking and distortion are generally considered to occur under united thermal and transformational stresses. In this paper quench residual stresses were examined by using a S 55 C steel bar. Various polyalkylene glycol (PAG) solutions and oil were prepared for the quench cooling solutions. The micro structure of the test piece was observed with a metallurgical microscope. The residual stresses caused by quenching were measured by Sachs' method. Considerable tensile and compressive stresses existed on the surface and in the center of the steel. The distribution of stresses and the hardness were related to the PAG content and could be explained clearly by the quench cooling rate.

著者

髙井 直樹 元木 信弥 山崎 友裕

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.807, pp.1632-1647, 2013 (Released:2013-11-25)

参考文献数

9

被引用文献数

1

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The effects of applied stresses on dynamic characteristics of piezoelectric ceramics are analyzed based on the nonlinear electroelastic theory. Piezoelectric ceramics are used in many electric devices as functional elements, where mechanical constraint is usually applied. Estimation of piezoelectric properties under applied stresses is important in designing the devices. However, applied stresses cannot be considered in the basic equations in the linear piezoelectric theory, and the effects of the applied stresses cannot be predicted. In this study, we introduce additional terms related to the dissipation effects, specifically, electric conduction and internal viscosity resistance, and nonlinearity of elastic properties into electroelastic theory. As well, considered nonlinear effects are elastic, piezoelectric and dielectric constants up to 3rd order. Frequency dependence of admittance of PZT disks is measured under applied compressions, showing that applied stresses have certain influences on either of thickness and radial vibrations of PZT. Assuming proper material constants, experimental results can be well explained by the nonlinear electroelastic theory.

著者

斉藤 一哉 野島 武敏

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.78, no.787, pp.324-335, 2012 (Released:2012-03-25)

参考文献数

7

被引用文献数

2 3

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This study illustrates a new strategy to fabricate arbitrary cross-section honeycombs. These types of honeycombs are usually manufactured from normal flat honeycombs by curving or carving, but the proposed method enables us to construct objective shaped honeycombs directly. We first introduce the concept of the kirigami honeycomb, which is made from single flat sheets and has periodical slits resembling kirigami (Japanese art of study folding and cutting). In previous studies, honeycombs having various shapes, including tapered and aerofoil honeycombs, were made using this method, and were realized by only changing folding line diagrams (FLDs). In this study, these 3D kirigami honeycombs are generalized by numerical parameters and fabricated using a newly proposed FLD design method, which enables us to draw the FLD of arbitrary cross-section honeycombs

著者

江原 隆一郎

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.59, no.557, pp.1-11, 1993

被引用文献数

1 3

著者

高野 敦 森永 洋次 井上 登志夫

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.800, pp.455-462, 2013 (Released:2013-04-25)

参考文献数

15

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Methods of evaluating the one-sided tolerance limit (A- and B-basis values) of unbalanced sample sets are derived. The A- and B-basis values are statistically calculated numbers that respectively indicate that at least 99 and 90 percent of the population is expected to equal or exceed the statistically calculated value with a confidence of 95 percent, and they are often used as strength tolerance limits in aerospace designs. The A- and B-basis values tend to be underestimated when the sample size is small and the conventional methods are used. Our novel methods improve the basis values by combining multiple sample sets from normally (Gaussian) distributed populations. We extended analysis of variance (ANOVA) to evaluate the A- and B-basis values by using non-central t-distribution under the condition of equality of variances. In addition, we derive coefficients for the basis values under the condition of non-equality of variances by using a Monte-Carlo method. Numerical examples show that both methods, i.e., equality and non-equality of variance cases, increase the A- and B-basis values.

著者

松田 伸也 黄木 景二

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.78, no.790, pp.912-922, 2012 (Released:2012-06-25)

参考文献数

28

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This paper presents a probabilistic model for predicting the constant fatigue life (CFL) diagrams for ceramics. First, a unified probabilistic delayed-fracture (PDF) model was proposed on the basis of the slow crack growth (SCG) concept in conjunction with the two-parameter Weibull distribution. Second, probabilistic CFL diagrams for effective volume Veff, effective loading time teffNf, fracture probability F and stress ratio R were obtained using the PDF model. The probabilistic CFL diagram was then related with the modified Goodman's diagram. Third, the unified strength parameters associated with the PDF model were determined using the experiment data of Si3N4 subjected to rotating bending. The stress amplitude - the number of cycles to failure curves were then predicted for R=-1 and 0 and various values of F. Moreover, the probabilistic CFL diagrams for various values of Veff and teffNf at F were depicted using the unified strength parameters. The validity of the present model was confirmed through the comparison of the predicted CFL diagrams with the experiment data.

著者

山東 篤

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.600-609, 2011 (Released:2011-04-25)

参考文献数

9

被引用文献数

1 2

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The interactive terms in the mesh superposition method are calculated approximately because the integrand has a discontinuity along the mesh lines in a superimposed global mesh. In this paper, the accurate numerical integration technique for a discontinuous integrand by the Delaunay triangulation is proposed. Integral ranges including discontinuous integrands are divided into triangles only with a continuum integrand. The exact solution is sum of the integral values calculated in all triangles. Appropriate triangle edges can be regenerated by the swapping algorithm even though generated triangles contain the inappropriate boundary lines which bring about a discontinuity. A comparison of the accuracy of numerical integration between the proposed technique and conventional approximate means and an application to a sensitivity calculation are investigated in the first example. The second example illustrates the swapping algorithm for the adjustment of generated triangles.

著者

高木 知弘

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.783, pp.1840-1850, 2011 (Released:2011-11-25)

参考文献数

20

被引用文献数

1

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Phase-field topology optimization model which aims the maximum rigidity of mechanical structure has been developed and its fundamental performances have been evaluated by performing two-dimensional cantilever simulation. Here, the effects of interface thickness, initial morphology and solid volume fraction on the final morphologies and rigidity have been investigated. As a result, it has been confirmed that the thin interface thickness produces the high rigidity of the structure with small computational cost. Furthermore, the developed model enabled us to maximize the rigidity of mechanical structure stably and easily and the initial morphology dependencies of final morphology were relatively small.

著者

荒尾 与史彦 小柳 潤 武田 真一 宇都宮 真 川田 宏之

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.619-628, 2011 (Released:2011-04-25)

参考文献数

17

被引用文献数

7 8

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Strict geometrical stability is required for the precise structures like telescopes. Unpredictable out-of-plane deformation is a serious problem when we use CFRP (Carbon Fiber Reinforced Plastic) laminate to the precise structure. This out-of plane deformation of symmetrical CFRP laminate mainly arise from combination effects of ply angle misalignment and temperature change. We discussed here is effective stacking sequence of CFRP laminate that mitigate the deformation caused by the ply angle misalignment. The analysis based on laminate theory was performed to calculate the thermal deformation. In this analysis, the random numbers were added to each layers as ply angle misalignments. The analytical results were obtained statistically by Monte Carlo method. Mohr's curvature circle was also incorporated to evaluate the deformation as P-V (peak to Valley) values. We performed the analysis with various stacking sequence. It was calculated that the symmetric cross-ply laminates deformed 10 times larger than the other quasi-symmetric laminates. In the case of the total ply number is less than 12, the stacking sequence in the laminate has a significant effects on the thermal deformation. However, if the total number ply number is more than 24, effect of stacking sequence on the thermal deformation becomes negligible. We also discussed the geometrical stability of CFRP mirror by considering unavoidable ply angle misalignment. It was presumed that the CFRP mirror can be used for wide range of wave length when the back structure was attached to CFRP laminates.