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幡中 憲治
1984 年 50 巻 453 号 p.
831-838
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
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吉野 利男, 時田 広士
1984 年 50 巻 453 号 p.
839-846
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
フィラメント・ワインディングしたFRP製駆動軸を三次元シェル構造モデルとし,また繊維配向による直交異方性を考慮して,FEMを用いて,ピン穴継手部周辺の応力を解析した。繊維の配向角によりピン穴周辺の半径応力にはピークが2箇所現れ,そのうちの一つのピーク応力は等方性材料の場合よりも大きな値を示すことなどがわかった。
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西谷 弘信, 野田 尚昭
1984 年 50 巻 453 号 p.
847-854
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
体積力法により,無限個の円周き裂を有する丸棒の引張り問題を扱った。無限体中に無限個の集中力の対の輪が周期的に作用する場合の応力の式の表示を求め,それを基本解とした。き裂の間隔とき裂の深さを変えて応力拡大係数を求め,丸棒におけるき裂の干渉効果を考察した。また,一つの円周き裂を有する丸棒についても計算を行い,従来の研究と比較し検討した結果,より信頼性の高いと思われる応力拡大係数の数値を得た。
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谷川 義信, 竹内 洋一郎, 野田 直剛
1984 年 50 巻 453 号 p.
855-862
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
円柱座標系での三次元連成熱応力問題に対し,その解析的容易さを念頭に置き,熱弾性変位ポテンシャルの概念を用いて,温度,変位および応力成分の新しい定式化を行った。得られた基礎関係式は,連成項を無視した非連成問題に対しても,容易に適用できる。更に,上述の関係式を適用した解析例として,内側境界からの加熱を受ける中空円筒の軸対称連成熱応力問題を取上げ,その数値計算例を示し,連成効果について吟味した。
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上田 整, 進藤 裕英, 渥美 光
1984 年 50 巻 453 号 p.
863-868
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
衝撃負荷を受ける複合材中の界面き裂群の動的相互干渉の理論研究のため,2個の平行な円板状界面き裂を有する三層複合材のねじり衝撃応答問題を厳密に解析した。解法はラプラス・ハンケル二重積分変換を用いて得られる双積分方程式を数値的評価が容易な積分核を揺する第二種フレドホルム形積分方程式に導いて解く方法によった。数値計算を行い,動的応力拡大係数の時間的挙動におよぼす幾何学的形状および物質特性の影響をグラフに示し明らかにした。
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深津 綱次, 川島 紘一郎, 織田 昌信
1984 年 50 巻 453 号 p.
869-879
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
ホプキンソン圧縮棒(SHPB)法に対する一次元波動理論の適用限界を検討するために,短い円柱の一端の全面および同心円領域が縦衝撃を受ける場合の軸対称波動伝ぱ問題を従特性曲線法により解析した。特に同心円領域が衝撃を受ける場合について,円柱の直径に対する衝撃を受ける同心円の直径の比が衝撃応答に与える影響を調べ,SHPB法における試片と出力棒の直径比の適正値を求めた。また,実験を行い,本解析法の妥当性を確かめた。
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神宮 利夫, 久田 耕二, 中原 一郎, 町田 周郎
1984 年 50 巻 453 号 p.
880-887
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
円板の外周に径方向に対向してステップ関数状に変動する集中衝撃荷重が作用するときの応力波の伝ぱおよびそれによる応力変動を二次元動弾性理論にもとづいて厳密に解析した。応力関数を用い,波動方程式にラプラス積分変換法を適用し,境界条件を満足する解を求めた。ラプラス逆変換は留数計算に従って行った。衝撃荷重によって発生する縦波,せん断波,レーレー波の応力波および境界面で反射した応力はと応力変動の関係を明らかにした。
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百武 秀, 西谷 弘信
1984 年 50 巻 453 号 p.
888-893
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
切欠きをもつPC 板の破壊が延性形とぜい性形のいずれになるかを決める力学的因子を明らかにするために,切欠き平板の引張試験を切欠き半径ρ,切欠き深さcおよび板厚tの広い範囲にわたって行い,次の結果を得た。(1)破壊の形を決める支配的因子はρとtである。(2)破損時における切欠き底の最大応力は,ぜい性形ではρのみによって一意的に決まり,延性形ではt/ρのみによって一意的に決まる。cよびtとは無関係である。
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渡辺 勝彦
1984 年 50 巻 453 号 p.
894-903
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
エネルギ保存と仮想仕事の原理の立場から経路独立積分に関わる基本的な保存則を導出し,その両者が等価なものになることを示すと共にエネルギ・モメンタム・テンソルの概念を任意の構成則を考える場合にも有効なものとして拡張した。また得られた保存則に基づき,破壊力学における最も基本的なパラメータであるき裂エネルギ密度の経路独立積分ε
Jによる表示を与え,併せてJ^^^積分の正確な位置付けを行った。
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三好 俊郎, 吉田 有一郎, 白鳥 正樹
1984 年 50 巻 453 号 p.
904-911
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
本論文は,不安定延性破壊における進展き裂に対するJ積分の評価法を有限要素法により検討したものである。さらにCOAxき裂進展条件を用いた場合のJ積分支配き裂進展の有効性に関し中央き裂およびCT試験片に対して理論値と有限要素法による結果の比較を行った。また不安定延性破壊発生点におよぼすき裂長さ,コンプライアンスの効果を示すスタビリティ・ダイヤグラムを提唱した。
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岸本 喜久雄, 立原 昌義, 青木 繁, 坂田 勝
1984 年 50 巻 453 号 p.
912-919
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
三点曲げ試験片に対して三次元弾塑性有限要素解析を行った。コンパクト試験片の場合と同様にJ^^^積分値は板厚中央部で高く,表面部で低い値となった。板厚中央のJ^^^積分値は,平面ひずみと平面応力の中間の値となった。Riceの簡便式によって評価されたJ積分値と板厚中央のJ^^^積分値は,ほぼ一致することを示した。また,板厚中央のJ^^^積分値が二次元有限要素解析の結果から推定できることを示した。
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座古 勝, 三好 俊郎, 辻村 健
1984 年 50 巻 453 号 p.
920-927
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
近年構造物や機械部品の破壊に対する評価が統計的手法で行われている.モンテカルロなどは,その例であるが計算時間がかかり過ぎる欠点がある.45000kL石油貯蔵タンクを例にとり,確率有限要素法を用いて,タンク底板部に腐食が生じた場合の破壊確率を求めた.計算のために,腐食の割合,年間の油の出し入れ回数などを仮定した.結果として10
-2となった.しかし,外力に変動を加えると8×10
-2となり,かなり増加することが判明した.
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戸谷 眞之
1984 年 50 巻 453 号 p.
928-935
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
弾塑性クラックのエネルギ解放率を定義し簡単な例に対し考察した.次に修正DBCSモデルについて説明し,このクラックのエネルギ解放率を計算した.その結果,破壊に使われるエネルギは解放されたポテンシャルエネルギのごくわずかの部分にすぎなく大部分は塑性変形に費やされることが分かった.スクラックに平行に加えられた垂直応力は破壊荷重に対して大きな影響をおよぼすことが結論された.
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土岐 仁, 八巻 昇, 谷 順二, 大友 規矩雄
1984 年 50 巻 453 号 p.
936-944
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
液体を部分的に満たした円筒殻の外圧座屈後の挙動について,ポリエステルフィルム製試験円筒殻と水を用いて精密な実験的研究を行った.その結果,一般に水位の増加につれて,座屈圧力,座屈後のつりあい圧力および円周方向波数は増大し,座屈後のたわみ波形は逐次上方に移動することを明らかにした.また先に求めた座屈圧力の理論値と本実験結果は非常に良く一致することを確認すると共に,二次座屈現象についてもふれた.
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福岡 秀和, 戸田 裕己, 平川 賢爾, 坂本 東男, 山口 久雄
1984 年 50 巻 453 号 p.
945-952
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
過酷な踏面ブレーキを受けた車輪リム部の残留応力を音弾性法により非破壊的に測定した.音弾性法則によれば,直交する主方向に偏向した二つのせん断波の伝ぱ速度差は主応力差に比例する.本研究では,5MHzの振動子を用い,シング・アラウンド装置により音速差を測定した.ブレーキ試験後,車輪リム部の音弾性測定により得られた円周方向の引張り残留応力の値を慣用の破壊法により得られた値と比較したところ満足し得る結果が得られた.
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水口 義久, 吉峯 鼎, 小泉 堯, 萩原 隆徳
1984 年 50 巻 453 号 p.
953-958
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
超音波により接触圧力を定量的に測定するため,測定物と同一の材質および高さからなる基準較正試験片を用いて接触面における反射波音圧と接触圧力との関係を求め,これを較正曲線として測定値を定量的に測定する方法を試みた.実験では圧縮荷重をうける2枚の重ねはりの接触圧力分布測定を行い,計算結果や測定ピンによる実験結果と比較して,本測定法の測定精度や実用性について検討した.
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市川 昌弘, 高松 徹
1984 年 50 巻 453 号 p.
959-965
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
Initiation of stable crack growth under Mode II loading in center cracked sheet specimens of 2024-T3 aluminum alloy is investigated using the apparatus devised previously by the authors. This apparatus makes it possible to conduct Mode II testing on the specimen which has the same geometry as that for Mode I testing. It is shown that the stress intensity factor at initiation of stable crack growth, (K
i)
II, is constant independent of the specimen width W for W≥W
0 and decreases as W decreases for W<W
0, where W
0 is a certain specimen width. This tendency is quite similar to our previous result for Mode I loading. Finite element analysis is carried out in order to examine if J-integral is applicable. It is shown that the specimen width dependence of (K
i)
II is well interpreted by (j
i)
II=const criterion. This result is similar to Kitagawa et al's analysis for Mode I loading.
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本間 寛臣, 伊藤 研志
1984 年 50 巻 453 号 p.
966-972
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
The experiments of repeated impacts with steel balls of 20mm in a diameter on the same spot of the plate specimen surface were preformed in order to clarify a mechanical parameter taking a dominant part for the erosion damage. The observation of the specimen surface was made every a few cycles to measure the number of impacts when a erosion-lip was removed, that if defined as a erosion life. The measurement of dynamic stress histories near the crater gave the useful information of applied pressure to the crater by the steel ball. The pressure was successfully used to explain the effect of the impact angle on the erosion life observed in the experiments. IT was concluded that the pressure is one of the important parameters which dominate the erosion damage.
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城野 政弘, 宋 智浩, 内田 秀史
1984 年 50 巻 453 号 p.
973-979
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
In order to study fatigue damage accumulation due to the understresses included in service loadings, repeated two- and three-step programmed loading tests were carried out on SUS410JI stainless steel and the cyclic plastic strain was monitored throughout the life. In addition to effects of the cycle ratio of overstress to understress and the tensile mean stress present in the understress cycle, their interaction effects on the behaivior of cyclic plastic strain and cumulative damage were investigated in detail. Based on analyses of experimental results, a critical modified S-N curve was proposed which could be obtained from repeated two-step loading tests on a particular condition and would be applicable to actual loadings as conservative life-estimation.
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森下 正樹, 朝田 泰英, 石川 明克
1984 年 50 巻 453 号 p.
980-987
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
A series of creep-fatigue tests conducted with SUS304 stainless steel at 650°C in a very high vacuum environment of 0.1μPa were subjected to evaluation based on damage concept relating to an inelastic deformation behaviors of the material. In the model, a damage is separated into two components of time-independent and -dependent. An inelastic strain is separated into a time independent and -dependent inelastic strain parameter. Damage components are related to inelastic strain parameters to give damage rate equations in which material constants are determined from experiments.
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黒田 聖昭, 岸本 喜久雄, 青木 繁, 坂田 勝
1984 年 50 巻 453 号 p.
988-995
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
Simple formulas for the dynamic fracture mechanics parameters. of a three-point elastic or viscoelastic bend specimen are derived by means of the Timoshenko's beam theory. Numerical analysis is performed for a specimen of steel or PMMA impacted by a falling steel cylinder or sphere. The contact force between the specimen and impactor is estimated by applying the Hertz's theory to the local deformation near the contact point, and the fracture mechanics parameters are evaluated by the simple formulas. For the purpose of comparison, computations are also performed by using the formula which has been obtained previously using the Euler-Bernoulli's beam theory. A fracture test of PMMA beam was conducted and the dynamic strain intensity factor was measured by a strain gauge mounted near the crack-tip. It is found that the fracture mechanics parameters are overestimated if the effects of rotary inertia and transverse-shear deformation of specimen are neglected.
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新津 靖, 池上 皓三
1984 年 50 巻 453 号 p.
996-1002
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
Combined stress tests were performed on thin-wall tubes of austenite stainless steel SUS304 in 600°C. Plastic behaviors subsequent to pre-plastic strain and pre-creep strain were experimentally investigated under various loading conditions. Consequently the influence of pre-creep strain at low stress level on subsequent plastic behavior was nearly equal to that of pre-plastic strain, but the influence of pre-creep strain at higher stress level and that of large pre-creep strain were weaker than that of pre-plastic strain. Stress-strain relations in these experiments were compared and discussed with the results calculated by the equi-plastic-strain surfaces.
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小林 英男, 辻 裕一, 朴 卿東, 中沢 一
1984 年 50 巻 453 号 p.
1003-1010
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
Fatigue crack growth characteristics and crack closure for an A 508-3 steel were investigated at elevated temperatures (150°C and 288°C). The results obtained are summarized as follows: (1) The occurrence of oxidation of crack surfaces at elevated temperatures can affect the formation of fretting oxide debris in fatigue crack growth and has an important role on the near-threshold characteristics. (2) It can be possible to exclude the contribution due to fretting oxide debris and oxidation at elevated temperature on the near-threshold characteristics by the selection of a moderate test temperature. In this case, the characteristic is controlled only by plasticity induced crack closure and becomes a structure- and enviroment-insensitive material constant.
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西島 敏, 松岡 三郎, 竹内 悦男, 湯山 道也, 木村 恵
1984 年 50 巻 453 号 p.
1011-1018
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
Axial fatigue property at room temperature was investigated for 15 types of current carbon steels, low alloy steels and some stainless steels designated in the Japanese Industrial Standard (JIS) and widely employed for machine structural use. 55 representative heats in total were selected from materials examined in the Fatigue Data Sheet at the National Research Institute for Metals. Cyclic softening or hardening behaviour, cyclic stress-strain relationship, Coffin-Manson relations, the deviation from the relation at higher number of cycles region, and correlations between low cycle properties and the high cycle properties in the Data Sheets were discussed.
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増田 千利, 西島 敏, 阿部 孝行, 住吉 英志
1984 年 50 巻 453 号 p.
1019-1025
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
Morphology of surface damage and small cracks by the corrosion fatigue was studied for quenched and tempered carbon steel S45C and Cr-Mo steel SCM435 in a deionized water and 3%NaCl water environments under rotating bending at frequencies from 0.03 to 30 Hz. In saline water the fatigue strength of the two steels decreased monotonously with increasing number of cycles and testing time, while in the pure water a kind of temporal fatigue limit was observed for frequencies higher than 3 Hz. In the latter case fatigue crack was arrested by the closure effect of corrosion product for certain periods but this was diminished by dissolution after enough long test duration. A map of corrosion fatigue fracture mechanism was proposed based on the results of observation and analysis.
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鈴木 章彦, 土屋 秋夫
1984 年 50 巻 453 号 p.
1026-1034
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
A modified fraction model is proposed to represent the inelastic behavior of metal. In the proposed model, the inelastic strain of each volume fraction is expressed by only one component which includes plastic and creep strain in a unified way. This is the different point from the conventional fraction model originally proposed by Besseling where the inelastic strain of each volume fraction is divided to the time independent plastic strain and the time dependent creep strain. The proposed model eliminates the ambiguity in the determination of creep parameters which exists in the conventional fraction model and all material parameters of the model can be determined by usual uniaxial tensile test of several strain rates. Several example calculations and comparison with the test data have revealed that the proposed model has the capability of representation of the plastic, creep and plastic creep interaction behavior of metals.
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辻 恒平, 久田 俊明, 北川 英夫
1984 年 50 巻 453 号 p.
1035-1041
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
Irregular configuration of the corroded surface is taken as spatial stochastic process and two-dimensional filtered Poisson process is newly developed as a numerical model of corrosion. In the present model any corroded surface is interpreted as being made by the superposition of pits. This enables us to characterize any general corrosion quantitatively, which has been hardly achieved. The availability of the proposed method is demonstrated through the analyses of two corroded specimens and discussions are give in the light of the above interpretation. Also the sensitivity study is exemplified making use of the flexibility of the model, which yields the basis of prediction of the development of corrosion.
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石田 和雄, 小林 信之
1984 年 50 巻 453 号 p.
1042-1048
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
An effective method for calculating the nonlinear-rocking response of ground-supported unanchored cylindrical tanks to earthquakes was developed. In this method, tank wall and liquid content are replaced with a mass-spring system, and the nonlinearity associated with the partial uplift of bottom plates due to overturning moments is considered as the rotational spring of bi-linear type which is determined by a static uplift analysis of tank bottom. The reliability of the dynamic analysis was illustrated by computing resonance frequencies, response accelerations and rotation angles of tank models and by comparing them with the results of vibration tests. A seismic deign procedure for nonlinear rocking of tanks is proposed, in which the uplift height of bottom plates is calculated by dynamic rocking analysis and the corresponding radial stress of them is obtained by static analysis. And a rocking analysis of a full-sized tank was tried, too.
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高尾 健一, 西谷 弘信
1984 年 50 巻 453 号 p.
1049-1053
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
Push-pull fatigue tests with zero mean stress were carried out on commercial purity titanium sheet specimens, in order to investigate the crack initiation characteristics and notch sensitivity. Special attention was given to the starting point of fatigue cracking at the root of a notch with various sharpness, and fatigue processes were observed successively. The followings were obtained; (1) The crack initiation process is the one in which the definite regions whose dimensions are closely related to the grain size, turn gradually into free surfaces as a whole by the repetitions of slop. (2) No non-propagating crack is initiated even for a specimen with a notch root radius of 0.1 mm. (3) The material is notch insensitive for blunt notches, however, appreciably sensitive for sharp ones due to absence of non-propagating cracks, compared to 7:3 brass and mild steels.
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福永 秀春, 合田 公一
1984 年 50 巻 453 号 p.
1054-1061
発行日: 1984/05/25
公開日: 2008/02/21
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フリー
The present paper deals with microstructures and segregations of silicon-carbide fiber reinforced copper-added aluminium and aluminium-added magnesium alloy composites, fabricated by squeeze casting, as well as refers to the effect of the microstructure on the tensile strength of composites. The results obtained as follows; (1) Microscopic examination showed the solute element rich layer of a semicircle surroundings was locally formed on fibers in the composites, whichever matrix alloy was used. The layer was identified to be a eutectic constitution by EPMA analysis. With the decrease of the percentage of alloying element, the layer decreases in thickness and area fraction, and finally, for the case of 1% copper-aluminium matrix, no copper-rich layer was detected. (2) The appearance of the layer decreases the tensile strength of composites because of its brittleness.
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鶴崎 明, 尾田 十八
1984 年 50 巻 453 号 p.
1062-1068
発行日: 1984/05/25
公開日: 2008/02/21
ジャーナル
フリー
The indirect tension test, so called splitting test, is one of simple and effective methods for the determination of the tensile strength of brittle materials. But the calculated tensile strength is not always valid, because of the deformation at loaded parts of cylindrical specimen, the fracture criterion applied and so on. In this paper, a new indirect tension test, of which the loaded parts of specimen are cut parallel to each other, is proposed. Furthermore, the Mohr criterion is applied as the fracture criterion of the test method. The effects of the load conditions and the material properties of brittle materials for this method are numerically analized by the FEM and experimentally by many experiments with the resin-mortar specimens. As the result of the analysis and experiments both, a method to estimate the accurate tensile strength of brittle materials was established by using the indirect tension test load and the compressive strength of the material.
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仲町 英治 /, R. Sowerby
1984 年 50 巻 453 号 p.
1069-1076
発行日: 1984/05/25
公開日: 2008/02/21
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フリー
A Large Strain and large displacement analysis of axisymmetric elastic-plastic shell bodies by means of finite element method is developed. In this Updated Lagrangian formulation for a ring shell element, the first Kirchhoff-Love hypothesis and the plate thinning treatment are introduced. Two material models, both treated as an isotropic and elastic-plastic solid, are employed. These are J2F and J2D models, obeying plastic-potential flow law and deformation rule, respectively. The analysis was performed for a free bulging of circular plate. It is concluded that thicker plate under clamped condition promote the formation of a local neck near the peripherally edge. In other case, such as thicker plate under simply supported condition or thinner plate under any boundary condition, the localized neck occurred near the center point.
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西谷 弘信, 陳 玳〓
1984 年 50 巻 453 号 p.
1077-1082
発行日: 1984/05/25
公開日: 2008/02/21
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This paper is concerned with an analysis of stress intensity factor for a partial semi-elliptic crack perpendicularly emanating from the surface of a shaft subjected to uniform tension. In the analysis, the influence of Poisson's ratio on stress intensity factor is considered. The analysis is based on the body force method. According to the results, the stress intensity factor is larger than that for a similar shape crack of a semi-infinite body, excepting the case where the both b/a and b/r are small. The effect of Poisson's ratio on the stress intensity factor of a shaft is more than that of a semi-infinite body.
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西谷 弘信, 陳 玳〓
1984 年 50 巻 453 号 p.
1083-1089
発行日: 1984/05/25
公開日: 2008/02/21
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フリー
The local strain concentration plays an important roll in low cycle fatigue of plain specimens. It is controlled by the strain hardening and strain softening properties of materials. In this study, low cycle torsional fatigue tests of age-hardened, strain softening Al alloy and annealed, strain hardening Al alloy were carried out on plain specimens having the fine lines drawn on the surface by which local strain s were evaluated. The results obtained are summarized as follows: (1) The crack nucleation due to the strain concentration near the grain boundaries is one of the representative mechanisms of micro-crack initiation in both age-hardened and annealed Al alloys. (2) Since an age-hardened Al alloy is not necessarily as strain softening type in a macroscopic scale but is strain softening type in a microscopic slop, the tendency of strain concentration in any location is strong. (3) The relation between the number of cycles and the amount of slip in the location where it becomes a crack in the future depends on the strain hardening-softening properties of the two materials. However, the relations in slop band crack and grain boundary crack are similar in each material.
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西谷 弘信, 後藤 真宏
1984 年 50 巻 453 号 p.
1090-1096
発行日: 1984/05/25
公開日: 2008/02/21
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フリー
Fatigue tests under axial loading of plain steel specimens with a crack were carried out under various stress ratios R (R=0-1.5). When the crack is comparatively large and the stress amplitude σ
a is small, the crack growth rate is nearly proportional to ΔK
4(ΔK: stress intensity factor range). When the crack is small and σ
a is large, the growth rate is nearly proportional to σ
a81(1: crack length). In both cases, the effect of stress ration appears as the changes in the proportional constants.
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内藤 正鄰, 台丸谷 政志
1984 年 50 巻 453 号 p.
1097-1103
発行日: 1984/05/25
公開日: 2008/02/21
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フリー
The purpose of this paper is to examine not only qualitatively but also quantitatively the influence of a rise time of longitudinal impact on the propagation of elastic waves in a bar. The adequacy of application of the Love theory for the propagation of longitudinal elastic waves to this problem is discussed by means of the simultanuous measuring of both axial and radial strain waves at the same stations along a bar. Theoretical results based on the Love theory predicts that, as the rise time of impact velocity increases, the effect of lateral inertia on longitudinal waves decreases and rise time of impact velocity increases, the effect o f lateral inertia on longitudinal waved decreases and then the oscillatory wakes of it become negligibly small. Experimental results for a steel bar agreed well with the theoretical results. Moreover, as an example of application, the consideration of the experimental measurement of the dynamic yield stress by using the one dimentional stress bar was made.
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西谷 弘信, 緒方 隆志, 遠藤 正浩
1984 年 50 巻 453 号 p.
1104-1109
発行日: 1984/05/25
公開日: 2008/02/21
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フリー
Rotating bending fatigue tests were carried out on four kinds of heat-treated 0.45% C steels A, B, C and D whose Vickers hardness numbers Hv are 180, 480 650 and 800, respectively. The fatigue processes of these materials were observed successively. The fatigue limit of materials A and B is proportional to Hv, while that of materials C and D is not, especially the fatigue limit of material D is smaller than that of material C. This phenomenon is explained according to the differences of fatigue processes of these materials.
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