日本機械学会論文集 A編
Online ISSN : 1884-8338
Print ISSN : 0387-5008
71 巻, 704 号
選択された号の論文の17件中1~17を表示しています
  • 宮崎 則幸
    2005 年 71 巻 704 号 p. 587-592
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
  • 斉藤 賢司, 冨田 佳宏
    2005 年 71 巻 704 号 p. 593-599
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    A crystalline orientation dependent transformation model has been developed and finite element simulations clarify the effects of the crystalline orientation on the deformation and transformation behavior of TRIP steels. The results revealed that the deformation and transformation behavior of single crystal substantially depend on the maximum value of the Schmid factors of all slip systems. Decreasing the value of the Schmid factors raises the yield stress and drives the transformation in the early stage of deformation. In the later stage of deformation, the transformation behavior depends on the rotation of crystalline orientation due to the non-uniform deformation in the crystal grain. Meanwhile, the deformation and transformation behaviors of polycrystalline is strongly affected by not only individual crystalline orientation but also the situation of the distribution of crystalline orientation. The increase in the deviation of the distribution of the crystalline orientation causes significant non-uniform deformation due to misalignment of crystalline orientation with respect to the neighboring crystals, which promotes the transformation. Therefore, the transformation and deformation behavior may not be reproduced by the simple superposition of those of single crystals.
  • 皮籠石 紀雄, 永野 茂憲, 森山 三千彦, 大園 義久, 浦 孝博
    2005 年 71 巻 704 号 p. 600-606
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    Rotating bending fatigue tests were carried out for an 18%Ni maraging steel in order to investigate the effect of humidity on a crack initiation and its propagation of the steel. Moreover, the effect of reverted austenite on the sensitivity of fatigue strength for humidity was also investigated. Many cracks were initiated at the specimen surface and intergranular cracks were observed on the fracture surface when humidity was high. Both of the crack initiation and the early stage of the crack propagation were accelerated by humidity, especially the effect on the crack initiation was large. However, the effect of humidity on the crack initiation and its propagation was decreased and the intergranular cracking was suppressed by the formation of reverted austenite.
  • 田中 啓介, 秋庭 義明, 加藤 拓也, 高橋 弘樹
    2005 年 71 巻 704 号 p. 607-614
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    Fatigue tests of crack propagation from a pre-crack in thin-walled tubular specimens made of a medium-carbon steel were performed under cyclic torsion with and without superposed static or cyclic axial loading. The stress ratio of cyclic loading was-1. The experimental path of fatigue crack propagation from a pre-crack was compared with the predictions based on the maximum tangential stress criterion. The direction of fatigue crack propagation was perpendicular to the direction of the maximum of the range of the tangential stress, Δσ*θmax, near the crack tip determined from the stress intensity factor which was calculated by considering the contacts of crack faces at the minimum load. The stress intensity factor calculated from the actual crack path by using the body force method showed that the mode II stress intensity factor range quickly got close to zero after a small amount of crack extension. In other words, fatigue cracks propagate to satisfy the local symmetry of the cyclic components of crack-tip deformation.
  • 金子 堅司
    2005 年 71 巻 704 号 p. 615-622
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    Inelastic deformation behavior of Polypropylene (PP) in tensile large strain and after axial precyclings is investigated experimentally and analyzed using the three elements model based on the overstress theory. In this experiments, cylindrical tubular specimen as well as solid bar specimen is used for torsional loading and volume change is measured to get the true stress-true strain curves. It is found that flow stress is almost constant in strain range of more than 0.1, Poisson's ratio varies depending on strains and the viscosity does not change even after cyclic pre-loadings in tension, torsion and compression. The quasi-static stress-strain curve g is represented as a function of temperature. A very good agreement can be obtained between predicted results based on the obtained constitutive equations having the first invariant of stress (static pressure) effect and the experimental results on both of flow stress and relaxation.
  • 深沢 剣吾, 渋谷 正樹, 岡部 朋永, 清水 真佐男, 川嵜 一博
    2005 年 71 巻 704 号 p. 623-629
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    This study was conducted to examine how and why a difference of fatigue strengths between unnotched and notched specimens, in terms of maximum stress amplitude at the notch bottom, depends on the change of hardness level in steel. As a result, the local fatigue strength of the notch bottom in the notched specimen became higher than that of the un-notched one with increase of notch sharpness and this was remarkable in high strength steel. This is because the transition of the fatigue fracture mode occurs from a slip induced crack initiation mode to a defect controled one with increasing hardness in steel. In addition, using a new experimental approach combined with a simulation technique based on the concept of risk competition of defects, a computer simulation was conducted on an effect of inclusion on the local fatigue strength at the notch bottom of high strength steel. It was clarified that the difference of fatigue strength between notched and un-notched specimens in high strength steel was caused by the statistical variation of the largest inclusion size contained in the critical volume at the notch bottom.
  • 西谷 弘信, 寺西 高広, 久保 道弘, 才本 明秀
    2005 年 71 巻 704 号 p. 630-635
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    The linear notch mechanics (LNM) has been proposed by H. Nisitani to estimate the strength of notched structures. In using LNM, the highly accurate value of stress concentration factor is necessary. Recently, a method for calculating the highly accurate values of the stress concentration factors has been proposed by H. Nisitani, based on the usefulness of the stress value at a notch root calculated by FEM. This method is called the zeroth node point method. The usefulness of this method has already been confirmed by the body force method in the cases of the tensile problems. In this study, an extension of the zeroth node point method to the bending problems was made. Then the accuracy of the present analysis was discussed through the stress concentration factors obtained by the body force method. As the result, it was confirmed that the present analysis has the sufficient accuracy in the cases of the bending problems.
  • 精度の向上と周波数の影響
    小野 勇一, 北岡 征一郎, 池上 洋一, 田中 赴夫, 鳥山 真澄
    2005 年 71 巻 704 号 p. 636-641
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    The mean stress detecting method by the nickel foil with microcircular holes uses the propagation rate of the fatigue crack, which propagates from the edge of microcircular holes. However, since the crack propagation rate does not change considerably even if the mean stress changes, it cannot be said that the accuracy of the conventional method is enough. From the above viewpoint, in this report using the nickel alloy foil with higher hardness than the nickel foil, the improvement of accuracy of this method is investigated. Namely, the effect of mean stress on fatigue crack propagation is examined under constant temperature and frequency at first. Moreover, the influence of the frequency on the sensitivity of this method is investigated. Namely, the fatigue crack propagation is examined under various frequencies, and the basic equations are proposed to obtain mean stress.
  • 浅野 明雄, 関 祥子, 佐藤 暁, 佐藤 良一
    2005 年 71 巻 704 号 p. 642-648
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    Stresses and stiffness of spot-welded curved box section cantilever beams with a concentrated load at the free end have been studied analytically. Quadrant beams with a radius of curvature of 250 mm have been adopted as the analytical models. The influences of spot-welded pitches on the stress distributions and the bending rigidities were investigated numerically. Stress concentrations were occurred at the spot-welded nuggets and they increased with increase of spot-welded pitches. Bending rigidities of beams with 50 mm of spot-welded pitch showed about 15 percent low values compared with continuous curved beams and decreased slightly with increase of spot-welded pitches. The analytical results were consistent with the results of finite element methods.
  • 後藤 仁一郎, 宇佐美 三郎, 森田 博
    2005 年 71 巻 704 号 p. 649-655
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    Cyclic bending is a dominant loading mode in structures sustaining thermal loads. Numerical analysis was performed for the evaluation of the main elliptical crack propagation and crack initiation and propagation on the counter surface under cyclic out-of-plane bending. Inelastic three-dimensional finite element analyses were conducted taking crack opening and closure into account. When the front surface is in tension, the main crack opens and the compressive strain on the counter surface increases. Thus, deeper the main crack, larger the total strain range on the counter surface and this stimulates crack initiation on the counter surface. As the main crack propagates, the J-integral range at the deepest point decreases for deeper than 40% of the plate thickness. These numerical results explain the previous cyclic bending test results; a crack initiates and propagates on the counter surface and meets the main crack near 1/3 of the plate thickness of the specimen while the main crack grows. The J-integral range of the counter surface crack increase rapidly and becomes larger than that of the main crack. The calculated crack propagation rates in both longitudinal and depth directions of the main and the counter surface cracks based on the J-integral ranges were close to the experimental ones.
  • 第1報, 損傷発生後静的曲げ試験法による残存強度評価
    倉敷 哲生, 座古 勝, 欅田 訓名理
    2005 年 71 巻 704 号 p. 656-662
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    Compression after impact (CAI) test has been applied as a representative method of the evaluation for the residual strength of CFRP laminates after the occurrence of cracks or delamination. As it has several problems such as the accuracy of load measurement, the strength dependency on attachment of specimen and so on, we have proposed an evaluation method of the static bending test without the special attachment instead of the compression test after impact. We used ultrasonic microscope and SEM to observe the damage states in CFRP laminates under the impact test with low energy and the static test. From these results, we have proposed three-point static bending test method, which can determine the equivalent static bending load for arbitrary impact load. It is recognized that the residual strength after the occurrence of damage can be evaluated by the proposed method. The method, which is presented, is more convenient than the conventional method like CAI.
  • 第2報, 損傷力学に基づく数値解析手法の適用
    倉敷 哲生, 座古 勝, 椎野 努, 林 禎彦
    2005 年 71 巻 704 号 p. 663-669
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    The aim of this study is to establish a convenient evaluation method of the residiral strength after impact with low energy considering damage development of CFRP laminates by FEM. In this paper, we have developed a numerical simulation program on damage development considering the angles of transverse cracks to the loading direction based on damage mechanics. The angle of transverse cracks were not 90° to the loading direction and changed with the distance from the impact point. It is revealed that the numerical results of crack angles have a same tendency with the experimental results, and the mechanical behaviors of transverse cracks and delamination, which are difficult to observe with experiments, can be clarified. We have also proposed an evaluation method of bending after impact (BAI) test instead of CAI, and the residual strength after impact is evaluated by the proposed method. The numerical results of the residual strength after the occurrence of damages have a good agreement with experimental results. From these results, it is recognized that the proposed numerical method is more convenient than CAI.
  • 佐々木 敏彦, 廣瀬 幸雄
    2005 年 71 巻 704 号 p. 670-676
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    In order to study on a method of neutron stress measurement using the cos a method, a numerical simulation study was performed comparing with experimental data. The resultant diffraction profiles, which are defined as the distribution of the intensity of diffracted beams in the radial direction from the center of the diffraction ring, were calculated by summing all diffraction profiles which were diffracted at entire depth in the material. The locations of the peak points which were determined using the half value breadth method (or the centroid method) showed dent distribution with respect to the central angle of the diffraction ring even in case of stress free state. Though the stresses calculated by the cos α method showed different values from the initial stresses, the difference between the calculated and initial stresses almost kept constant for different stress level. These misfit stresses can be vanished after correcting original diffraction radius using that in stress free. The results obtained by the present simulation study agreed with those obtained in the previous experiment, which suggests the validity of the method of neutron stress measurement combining both an area detector and the cos α method.
  • 岡田 裕, 遠藤 明香, 菊池 正紀
    2005 年 71 巻 704 号 p. 677-684
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    S-version finite element method (S-FEM) is applied to two dimensional linear/nonlinear fracture mechanics problems. S-FEM in crack problems is such that local detailed finite element mesh (local mesh) is superposed on cores finite element model (global mesh) representing the global structure. Therefore, the detailed mesh representing the crack and the global mesh are generated independently. This methodology is considered to be one of global-local type analytical strategies. In this paper, the formulation of S-FEM is reviewed and applied to various linear/nonlinear fracture mechanics problems. Stress intensity factors for linear fracture problems are computed by using virtual crack closure method (VCCM). For nonlinear fracture problems, J-integral is evaluated. Calculations for the fracture parameters are carried out based on the local mesh only.
  • 作動流体が液体の場合
    松本 光広, 沢 俊行
    2005 年 71 巻 704 号 p. 685-691
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    The leakage evaluation when gas is used is more severe than that when liquid is used in pipe flange connections. In a practical design, it is also necessary to examine the leakage in the connections under liquid internal pressure application. The contact gasket stress distributions in the connection with a spiral wound gasket subjected to internal pressure and bending moment were analyzed by using elasto-plastic finite element method (FEM) taking account hysteresis and nonlinearity in the stress-strain curve of the gasket. The effects of the initial clamping bolt force (bolt preload), the nominal pressure and the nominal diameter of the pipe flange and the equivalent pressure on the contact gasket stress distributions were examined. The leakage tests for the connections under the bending moment and the internal pressure were also conducted by using liquid (water). By using the results of the leakage tests and the calculated contact gasket stress distributions, the sealing performance of the connections was evaluated. It was found that the sealing performance of the connection can be estimated when liquid (water) was used. In addition, a method for determining the bolt preload in the connections under the bending moments was proposed for the reliable design.
  • 宮崎 祐介, 宇治橋 貞幸, 持丸 正明, 河内 まき子
    2005 年 71 巻 704 号 p. 692-699
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    The influence of the head shape on intracranial responses under impact was investigated by using Finite Element Method. Head shape models of 52 young adult male Japanese were analyzed by Multi Dimensional Scaling (MDS), and a 2 dimensional distribution map of head shapes was obtained. Four finite element models of the Japanese head were constructed by transformed finite element model of average American adult male (H-Head model) using Free Form Deformation technique. The constructed models represent 5%ile and 95%ile of the first 2 scales obtained by MDS. The same acceleration pulse was applied to H-Head model and the 4 finite element models. The cause of the difference was considered to be differences in pressure distribution in the brain caused by the differences in the head shape. Variation in the head shape should be taken into account in simulating the effects of impact using a finite element model.
  • 種 健, 清水 秀樹, 平島 健一, 浜野 浩幹
    2005 年 71 巻 704 号 p. 700-706
    発行日: 2005/04/25
    公開日: 2011/03/02
    ジャーナル フリー
    This paper presents numerical solutions for anisotropic elastic medium with multi-layered elliptic ring inclusions. An arbitrary direction of principal axes of elasticity is considered in the matrix. General solutions of this study are obtained by using complex stress functions. The new formulation to improve problems of Lekhniskii's Formalism is proposed for anisotropic medium. Using the formulation, it is possible to determine a solution without arbitrary exchange of anisotropic parameters μ<k (k=1, 2, 3). The formulation is compared with Lekhnitskii's Formalism as well as Stroh's Formalism. Several results of calculation are shown by numerical representations.
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