JPH081412B2 - Fracture mechanical fatigue test method by double eccentric compression - Google Patents

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】セラミックス、サーメット、金属
間化合物、カーボン−カーボンコンポジット、セラミッ
クスコンポジット等のいわゆる耐熱高強度無機新素材は
特に１２７３Ｋ付近もしくはそれ以上の高温領域（以下
極高温領域という）において金属材料に較べ高強度、高
硬度の点で非常に優れているが、しばしばその脆性のた
め強度部材としての使用が避けられてきた。この発明は
これらの材料を必要且つ十分な信頼性を確保して強度部
材に使用するための強度評価に有効な極高温領域を含む
領域での破壊力学的疲労試験方法および試験装置に関す
るものである。[Industrial field of application] So-called heat-resistant high-strength inorganic new materials such as ceramics, cermets, intermetallic compounds, carbon-carbon composites, and ceramics composites are especially suitable for metals in the high temperature region around 1273K or higher (hereinafter referred to as extremely high temperature region). It is extremely superior to materials in terms of high strength and high hardness, but it has often been avoided from being used as a strength member due to its brittleness. The present invention relates to a fracture mechanical fatigue test method and a test device in a region including an extremely high temperature region which is effective for strength evaluation for using these materials in a strength member while ensuring necessary and sufficient reliability. .

【０００２】[0002]

【従来の技術】１２７３Ｋ付近もしくはそれ以上の耐
熱、耐摩耗、耐蝕などを必要とする苛酷な条件下では従
来その脆性のため困難とされてきたセラミックス等上記
新素材を強度部材として使用することが強く望まれてい
る。しかしこれらの材料は多くの場合、硬度、圧縮降伏
点、圧縮強度は高いが破壊靭性値が非常に小さい（通常
金属より１桁以上小さい）ため、引張強度は静疲労、繰
返し疲労とも十分ではなく、しかも非破壊検査の検出限
界以下の小さな初期欠陥もこれに影響するので、そのバ
ラッキも大きい。従って十分な信頼性を得るためには例
えばオーバースピンテスト等の全数プルーフ負荷試験が
必要となり、その場合の強度設計には使用環境条件下で
のプルーフ負荷を含む全実働荷重に対する寿命推定が必
要となる。しかもこれに不可欠な静疲労、繰返し疲労特
性を得るにも通常の疲労寿命試験ではバラッキにより多
数の試験片を用いての試験結果に統計的処理を行う必要
があり容易ではない。2. Description of the Related Art It is possible to use, as a strength member, the above-mentioned new materials such as ceramics, which have been conventionally difficult due to their brittleness, under severe conditions requiring heat resistance, wear resistance, corrosion resistance, etc. around 1273K or higher. Strongly desired. However, in many cases, these materials have high hardness, compressive yield point, and compressive strength, but very low fracture toughness values (one order of magnitude smaller than ordinary metals), so tensile strength is not sufficient for both static fatigue and cyclic fatigue. Moreover, since small initial defects below the detection limit of nondestructive inspection also affect this, the variation is large. Therefore, in order to obtain sufficient reliability, for example, 100% proof load test such as overspin test is required, and strength design in that case requires life estimation for all working loads including proof load under operating environment conditions. Become. Moreover, in order to obtain the static fatigue and cyclic fatigue characteristics which are indispensable for this purpose, it is not easy because the usual fatigue life test requires statistical processing of the test results using a large number of test pieces due to variations.

【０００３】しかしこれらの寿命のバラッキの主な要因
が初期欠陥のバラツキによることは一定のビッカース圧
痕をつけた試験片を用いるとバラツキが減少することか
らも容易に推測できる。そこでこれらの要因を切り離し
て先ずき裂進展寿命を別に調べること、すなわちき裂の
進展挙動を計測してその特性を明らかにする破壊力学的
静疲労、繰返し疲労試験が必要となる。However, it can be easily inferred that the main cause of these variations in the life is due to the variation in the initial defects, because the variation is reduced when the test piece having a certain Vickers indentation is used. Therefore, it is necessary to separate these factors and first examine the crack growth life separately, that is, fracture mechanical static fatigue and cyclic fatigue tests, which measure the crack growth behavior and clarify its characteristics.

【０００４】従来の脆性材料の破壊力学的繰返し疲労、
静疲労試験法としては、先ずダブルトーション試験法が
ある（以下ＷＴ試験法という）。これは片側の辺に予き
裂を与えた矩形平板の試験片のき裂の両側に板面に直角
方向の曲げモーメントを荷重点変位を制御して負荷して
き裂を進展させ、き裂の進展長さを荷重点の全変位と負
荷から求めたコンプライアンスの変化で推定し計測する
方法である。Fracture mechanics cyclic fatigue of conventional brittle materials,
As a static fatigue test method, there is a double torsion test method (hereinafter referred to as a WT test method). This is because a bending moment in the direction perpendicular to the plate surface is applied to both sides of the crack of a rectangular flat plate test piece with a pre-crack on one side to control the load point displacement and to propagate the crack. It is a method of estimating and measuring the length from the total displacement of the load point and the change in compliance obtained from the load.

【０００５】この方法は試験片のコンプライアンスが大
きく、き裂の安定成長が容易なので比較的古くからセラ
ミックスの定常もしくは準定常状態での静疲労試験法と
して用いられてきた。しかしき裂の前縁の形状が曲線と
なり、前縁に沿った条件が一様でないので計測結果の正
確な解析がむつかしく、特にき裂開閉口挙動など負荷条
件の変動にともなう過渡現象が含まれる場合は解析が困
難となる。従って定常もしくは準定常状態での静疲労試
験以外の一般的な繰返し疲労を含む試験に用いることは
困難である。This method has been used for a long time as a static fatigue test method for ceramics in a steady or quasi-steady state because the test piece has a large compliance and the stable crack growth is easy. However, the shape of the front edge of the crack becomes a curve, and the conditions along the front edge are not uniform, so accurate analysis of measurement results is difficult, and especially transient phenomena due to changes in load conditions such as crack opening and closing behavior are included. In that case, analysis becomes difficult. Therefore, it is difficult to use it for a test including general cyclic fatigue other than the static fatigue test in the steady or quasi-steady state.

【０００６】近年電気油圧サーボ試験機の制御性能が向
上したので、例えば岸本秀弘、他による「材料」（材料
学会誌）第３６巻（１９８７）１１２２〜１１２７頁に
あるようなコンパクトテンション（以下ＣＴという）試
験において負荷を荷重点間の相対変位が所定の波形にな
るように制御するいわゆる変位制御により得られるき裂
の安定条件下でのセラミックスの破壊力学的疲労試験、
或いは田中道七、他による「材料」第３８巻（１９８
９）１３７〜１４３頁にあるように片側に予き裂を有す
るスパンの短い四点曲げ試験（以下ＳＥＮＢという）等
セラミックスの破壊力学的繰返し疲労試験が二三進めら
れている。しかしこれらのき裂の進展量の計測は移動顕
微鏡によるものであり、特に１２７３Ｋ以上の高温での
試験はまだ成功していない。Since the control performance of the electro-hydraulic servo tester has improved in recent years, compact tension (hereinafter referred to as CT) as described in "Materials" (Journal of Japan Society of Materials) Vol. 36 (1987) 1122-1127 by Hidehiro Kishimoto et al. In the test, fracture mechanical fatigue test of ceramics under stable conditions of cracks obtained by so-called displacement control that controls the load so that the relative displacement between load points has a predetermined waveform,
Or Michichika Tanaka, et al. "Materials" Vol. 38 (198)
9) As shown on pages 137 to 143, a fracture mechanical cyclic fatigue test of ceramics such as a four-point bending test with a short span having a precrack on one side (hereinafter referred to as SENB) is underway. However, the measurement of the amount of growth of these cracks is performed by a moving microscope, and the test especially at a high temperature of 1273 K or higher has not been successful yet.

【０００７】本発明者ら（本発明者の１名菊川眞他２
名）はさきに次項（発明が解決しようとする課題）の一
部を解決する「材料」第３９巻（１９９０）１４４３〜
１４４９頁にある偏心圧縮負荷方式とも言うべき負荷方
式に菊川、城野他、「材料」、第２５巻（１９７６）８
９９〜９０３頁及び同誌第２９巻（１９８０）１２４０
〜１２４６頁にある除荷弾性コンプライアンス法、すな
わちき裂を有する物体に繰り返し荷重を掛け荷重変位の
ヒステリシスを計測し、除荷し始めてからき裂が閉口し
て剛性が増加しはじめる迄のき裂の開口している範囲の
ヒステリシス曲線の直線部分（除荷弾性線と略称する）
の傾斜の逆数、いわゆる除荷弾性コンプライアンスを求
め、この値がき裂長さとともに増加することからき裂長
さを測定する方法を組合せた試験方法を発明し、特許出
願中（公開特許公報（Ａ） 平３−２６７７３６）であ
るが、本発明はその後に明らかになった次項（５）以降
の課題をも解決し、さらにいままで殆ど手が着けられて
いなかったモード２き裂進展の場合にも適用範囲を拡大
できるように開発した二重偏心圧縮（ＤｏｕｂｌｅＥｃ
ｃｅｎｔｒｉｃ Ｃｏｍｐｒｅｓｓｉｏｎ，ＤＥＣ）負
荷方式とも名づけるべき新しい方式に関するものであ
る。The present inventors (one of the present inventors, Makoto Kikukawa et al. 2
Name) "Materials" Vol. 39 (1990) 1443-that solves a part of the following items (problems to be solved by the invention)
Kikukawa, Jono et al., "Materials", Vol. 25 (1976) 8
99-903 pages and Vol. 29 (1980) 1240.
~ Unloading elastic compliance method on page 1246, that is, the load displacement is repeatedly applied to an object having a crack and the hysteresis of load displacement is measured, and the crack is measured from the beginning of unloading until the crack closes and the rigidity starts to increase. The straight line part of the hysteresis curve in the open range (abbreviated as unloading elastic line)
Inventing a test method combining the method of obtaining the reciprocal of the inclination of the so-called unloading elastic compliance and measuring the crack length because this value increases with the crack length, and a patent application has been filed (Patent Publication (A) Flat 3 -267736), the present invention also solves the following problems (5) and later that have been clarified thereafter, and is also applicable to the case of mode 2 crack growth that has been barely touched until now. Double eccentric compression (DoubleEc
The present invention relates to a new method which should also be called a "centric compression (DEC) load method".

【０００８】セラミックス等脆性材料のモード２破壊に
ついては、Ｋ１Ｃがより低いとしていままで問題とされ
ず、セメント、岩石等の圧潰試験の他あまり試験も行わ
れていず、モード２き裂進展挙動については殆ど調べら
れていない。Regarding mode 2 fracture of brittle materials such as ceramics, K1C is considered to be lower and has not been a problem until now. In addition to the crushing test of cement, rock, etc., it has not been often tested. Has hardly been investigated.

【０００９】[0009]

【発明が解決しようとする課題】破壊力学は物体にき裂
が発生し、それが伝播して破壊に到る過程を定量的に取
り扱うもので、き裂先端の応力場を示すパラメーターと
して次式〔数１〕の応力拡大係数Ｋ値（Ｓｔｒｅｓｓ
Ｉｎｔｅｎｓｉｔｙ Ｆａｃｔｏｒ）を用いてき裂進展
速度等を評価する。Fracture mechanics deals quantitatively with the process in which a crack is generated in an object and propagates to the fracture, and the following equation is used as a parameter indicating the stress field at the crack tip. Stress intensity factor K value of [Equation 1] (Stress
Intensity factor) is used to evaluate the crack growth rate and the like.

【００１０】[0010]

【数１】 [Equation 1]

【００１１】ここにσ＝き裂が無い時の公称応力 ＭＰ
ａ ａ＝き裂長さｍ ｆ＝試料の形、き裂長さと試験片の幅との比等で決定さ
れる係数 Ｋ値がある臨界値Ｋ１ｃ（破壊靭性値）を越える、すな
わちＫ≧Ｋ１ｃとなるとき裂が急速に進展して殆ど瞬時
に破壊する。しかし実際にはＫ＜Ｋ１ｃでも長時間一定
荷重（静疲労現象）を負荷したり、繰り返し荷重（繰返
し疲労現象）を負荷するとき裂は徐々に進展する。この
ようにＫなる尺度を用いてき裂進展挙動を定量的に明確
にすることが破壊力学の目的である。Where σ = nominal stress without crack MP
a a = crack length m f = coefficient determined by sample shape, ratio of crack length to width of test piece, etc. K value exceeds a certain critical value K1c (fracture toughness value), that is, K ≧ K1c When the crack propagates rapidly, it breaks almost instantly. However, actually, even if K <K1c, the crack gradually propagates when a constant load (static fatigue phenomenon) is applied for a long time or when a repeated load (repetitive fatigue phenomenon) is applied. The purpose of fracture mechanics is to quantitatively clarify the crack growth behavior using the K scale.

【００１２】ところでセラミックス等の耐熱高強度の前
記新素材は程度の差はあるが脆性高硬度でもあるのでそ
の破壊力学的疲労試験、特にこれを極高温領域で行う場
合には次のような課題がある。By the way, the new materials having high heat resistance and high strength, such as ceramics, are also brittle and highly hard to some extent, so that the following problems are encountered when carrying out a fracture mechanical fatigue test, especially in the extremely high temperature region. There is.

【００１３】（１）金属材料（靭性材料）では通常き裂
進展寿命（疲労寿命）が問題となる応力拡大係数Ｋ値の
領域（試験領域）は破壊靭性値Ｋ１Ｃよりはるかに低い
範囲であり、且つ繰り返し数依存性のいわゆる繰返し疲
労が主として支配する領域であるので、一般の試験条件
でもき裂は安定に成長し、き裂を計測する破壊力学的疲
労試験はどのような方法によっても比較的に容易であ
る。(1) In a metal material (toughness material), a region of stress intensity factor K value (test region) where crack propagation life (fatigue life) usually becomes a problem is a range far lower than fracture toughness value K1C, In addition, since this is a region in which so-called cyclic fatigue, which depends on the number of cycles, is mainly dominant, cracks grow stably under general test conditions, and the fracture mechanics fatigue test for measuring cracks is relatively Easy to.

【００１４】しかしセラミックス等の脆性材料ではＫ１
Ｃは低く、またＫ値がＫ１Ｃに近くならないと繰返し荷
重の場合でもしばしばき裂の進展が起こらない。従って
Ｋ値の試験領域はその最大値ＫｍａｘをＫ１Ｃに近くす
る必要があり、また材料、温度、環境等の試験条件によ
って異なり現在必ずしも明らかになっていないが、き裂
進展はＫｍａｘ依存性、時間依存性のいわゆる静疲労に
より支配される部分が、繰り返し数依存性、応力拡大係
数レンジ（変動巾）ΔＫ依存性の繰返し疲労に支配され
る部分より大きい。従ってき裂の進展にともなってＫ値
が増加するような静的不安定な試験条件では、特にＫｍ
ａｘがＫ１Ｃに近い場合、き裂の進展が一定荷重下でも
加速して、しばしば短時間で破断に到りき裂の進展を計
測することは困難となる。従ってき裂進展に伴ってＫ値
が大きくなるような荷重の負荷方式では安定して試験を
することができない。However, in brittle materials such as ceramics, K1
C is low, and unless the K value is close to K1C, crack growth often does not occur even under repeated loading. Therefore, it is necessary for the test area of K value to have its maximum value Kmax close to K1C, and it depends on the test conditions such as material, temperature, environment, etc. Although it is not always clear at present, crack growth depends on Kmax and time. The portion dominated by the so-called static fatigue of the dependence is larger than the portion dominated by the repetition fatigue of the repetition number dependence and the stress intensity factor range (variation width) ΔK dependence. Therefore, under statically unstable test conditions in which the K value increases with the progress of cracks, especially Km
When ax is close to K1C, the crack growth accelerates even under a constant load, often leading to fracture in a short time, and it is difficult to measure the crack growth. Therefore, it is not possible to perform a stable test with a load system in which the K value increases as the crack progresses.

【００１５】（２）セラミックス等の焼結後の仕上げ加
工はダイヤモンド砥石などによる研磨によらざるを得な
いので形状に制約があると共に形状が複雑となると高コ
ストとなる。また引張強度が低いので引張応力の集中を
避ける必要があり試験片の形状は簡単でなければならな
い。(2) Since the finishing process after sintering of ceramics or the like must be done by polishing with a diamond grindstone or the like, there are restrictions on the shape and the cost becomes high if the shape is complicated. Since the tensile strength is low, it is necessary to avoid concentration of tensile stress and the shape of the test piece must be simple.

【００１６】（３）セラミックス等の場合はその材料の
耐熱性を利用する場合が多いので極高温領域での試験が
重要となる。この場合に電気炉による加熱方式をとると
加熱範囲を試験断面部分に局限することは困難で試験片
のみならず試験片を掴むチャック部、計測のための検出
点からの引き出し部も高温となり、１２７３Ｋを越える
極高温領域の試験ではこれらもセラミックス製とする必
要がある。このため従来の三点、四点曲げ、引張試験な
ど小型試験片の静的試験でも治具等が非常に高コストと
なり、試験片破断時に破損することもしばしばであるの
で、設計が容易でなく、試験断面の大きさがある程度必
要で繰返し荷重の負荷を行う破壊力学的疲労試験の場合
には非常に困難である。(3) In the case of ceramics and the like, the heat resistance of the material is often used, so that testing in an extremely high temperature region is important. In this case, if the heating method using an electric furnace is adopted, it is difficult to limit the heating range to the test cross-section, and not only the test piece but also the chuck part that grips the test piece and the extraction part from the detection point for measurement become hot, In a test in an extremely high temperature region exceeding 1273K, these also need to be made of ceramics. Therefore, even in static tests of small test pieces such as conventional three-point, four-point bending, and tensile tests, jigs are very expensive and often break when the test piece breaks, so designing is not easy. However, it is very difficult in the case of the fracture mechanical fatigue test in which the size of the test cross section is required to some extent and the cyclic load is applied.

【００１７】（４）極高温領域のき裂進展量の計測が困
難である。室温あるいは中高温ではき裂進展を顕微鏡で
観察することができ、これを移動顕微鏡で計測すること
は通常行われており、画像処理により自動追尾して計測
する方法も開発されている。しかし１２７３Ｋ以上の温
度では輻射光が強く観察が困難になり、かげろうによる
ゆらぎも大きく、光学的にはレーザー光や高温用光フフ
ァバーを使うなど何らかの特殊な方法によらなければ困
難である。(4) It is difficult to measure the amount of crack growth in the extremely high temperature region. The crack growth can be observed with a microscope at room temperature or medium and high temperatures, and it is usually measured with a moving microscope. A method of automatically tracking and measuring by image processing has also been developed. However, at a temperature of 1273 K or higher, the radiant light is strong and observation becomes difficult, and the fluctuation due to the frostiness is large, and it is optically difficult unless some special method such as using a laser beam or a high temperature optical fiber is used.

【００１８】（５）以上に説明したように塑性変形が殆
ど無いセラミックス等の脆性材料では、単に予き裂をも
うけた試験片に引張荷重或いは曲げ荷重によってき裂先
端に引張応力を生じさせると亀裂の進展に従い応力拡大
係数Ｋが急激に大きくなり、速やかにき裂が進展し即時
破断するので、従来のこのような負荷方法による疲労試
験ではき裂進展を定量的に計測する破壊力学的な疲労試
験は通常困難であった。(5) As described above, in brittle materials such as ceramics that hardly undergo plastic deformation, if tensile stress is generated at the crack tip simply by a tensile load or a bending load on a test piece having a pre-crack. The stress intensity factor K rapidly increases as the crack progresses, and the crack progresses rapidly and immediately breaks. Therefore, in the fatigue test by the conventional load method as described above, the crack growth is quantitatively measured by the fracture mechanical method. Fatigue tests were usually difficult.

【００１９】この課題に対してさきに本発明者ら（本発
明者の１名菊川眞他２名）は、長方形状の試験片の片側
の中央に予き裂を置き両端面に反対側に偏心して圧縮荷
重を加えると予き裂の先端には始め引張の公称応力が加
わるが、き裂が進展してき裂先端が荷重の作用線に近づ
くと減少し、これを越えると圧縮になることに着目し、
適当な予き裂長さ負荷位置を選べばき裂の進展にともな
い応力拡大係数Ｋが減少するき裂進展が安定になる領域
が得られること、さらに試験片両端の相対角変位を制御
すればより広い領域、Ｋ値の変化のゆるやかな十分良い
特性が得られることを見い出した。この方法により窒化
けい素等セラミックスにつき室温（菊川他、日本材料学
会 第５回破壊力学シンポジウム講演論文集（１９８
９）２７２〜２７６頁，「材料」第３９巻（１９９０）
１４４３〜１４４９頁）、ならびに１６７３Ｋに到る極
高温領域（Ｍ．Ｋｉｋｕｋａｗａ ｅｔ．ａｌ．，Ｐｒ
ｏｃ．６ｔｈ Ｉｎｔ．Ｃｏｎｆ．Ｍｅｃｈａｎｉｃａ
ｌ Ｂｅｈａｖｉｏｕｒｏｆ Ｍａｔｅｒｉａｌｓ Ｖ
ｏｌ．２，ｐｐ．３４５／３５０，（１９９１））にて
破壊力学的疲労試験をすることが出来た。しかしその後
（菊川 他、日本機械学会 第６９期通常総会講演会講
演論文集Ｎｏ．９２０−１７ Ｖｏｌ．Ａ３７８〜３８
０頁（１９９２））に示すように窒化けい素でもある種
のものは偏心圧縮負荷方式で相対角変位制御で安定なき
裂成長が困難なことが判った。これは相対角変位を炉外
に引き出し計測するため計測系の固有振動数を十分高く
出来ず、ｄａ／ｄｔ−Ｋ曲線（ｔは時間、ｖ−Ｋ曲線と
も言う）の傾斜の特に大きい材料では制御遅れが問題と
なるためと思われる。荷重制御では試験領域が狭く良い
特性が得難いのでこの点を解決した次の新しい負荷方式
を用いる試験方法を発明した。To solve this problem, the present inventors (one of the present inventors, one of the present inventors, Makoto Kikukawa and others) placed a pre-crack in the center of one side of a rectangular test piece and placed it on opposite sides of both end surfaces. When an eccentricity is applied and a compressive load is applied, the nominal tensile stress is initially applied to the tip of the pre-crack, but it decreases when the crack progresses and the tip of the crack approaches the line of action of the load. Pay attention to
If an appropriate pre-crack length load position is selected, the stress intensity factor K decreases with the growth of the crack, and a region where the crack growth becomes stable can be obtained. Furthermore, by controlling the relative angular displacement of both ends of the test piece, It has been found that a wide range and a sufficiently good characteristic with a gradual change in the K value can be obtained. By this method, the room temperature of ceramics such as silicon nitride (Kikukawa et al., Proc.
9) pp. 272-276, "Materials" Vol. 39 (1990)
1443-1449), and an extremely high temperature region up to 1673K (M. Kikukawa et. Al., Pr.
oc. 6th Int. Conf. Mechanicala
l Behaviourof Materials V
ol. 2, pp. 345/350, (1991)), a fracture mechanical fatigue test could be conducted. However, after that (Kikukawa et al., Proc. Of the 69th Ordinary General Meeting of the Japan Society of Mechanical Engineers, No. 920-17, Vol. A378-38)
As shown on page 0 (1992)), it has been found that stable crack growth is difficult for some silicon nitrides by the eccentric compression load method and relative angular displacement control. This is because the relative angular displacement is drawn out of the furnace for measurement, the natural frequency of the measurement system cannot be made sufficiently high, and a material with a particularly large slope of the da / dt-K curve (t is time, also called v-K curve) is used. It seems that the control delay becomes a problem. In load control, the test area is narrow and it is difficult to obtain good characteristics. Therefore, the inventors invented a test method using a new load method that solves this problem.

【００２０】（６）セラミックス等脆性材料は等方等質
の場合通常モード２き裂進展はモード１より生じ難く問
題とならないので、試験についても今まで殆どなされて
いないが、転動疲労のごとく圧縮応力下の破壊や、現在
実用されているＦＲＰ、ＣＦ ＲＰなど有機系複合材料か
ら推測されるように、異方性が強く層間剥離、層間せん
断、ブリッジングフリクションなどが問題となると思わ
れるセラミックス−セラミックスコンポジット、カーボ
ン−カーボンコンポジット等同種あるいは金属、金属間
化合物との異種の無機系複合材料の強度特性や破壊機構
の解明、さらに材料設計には、モード２あるいはモード
１、２混合モード、静モード１と繰り返しモード２等種
々の条件下のき裂進展試験をしその挙動を調べることが
重要で、これには上記と同様な問題点がある。 (6) Brittle materials such as ceramics are isotropic and isotropic
In the case of, normal mode 2 crack growth is less likely to occur than mode 1.
It's not a subject, so most of the exams have been done so far
However, there is a failure under compressive stress such as rolling fatigue,
Is it an organic composite material such as FRP or CF RP that is actually used?
As can be assumed from the above, the anisotropy is strong and delamination and delamination
Disconnection, bridging friction, etc.
Ceramics-ceramics composites, carbs
Carbon-carbon composite, etc.
Strength characteristics and fracture mechanism of heterogeneous inorganic composite materials with compounds
Of the mode 2 or mode
1, 2 mixed mode, static mode 1 and repeat mode 2 etc.
It is possible to conduct a crack growth test under various conditions and investigate its behavior.
Importantly, this has the same problems as above.

【００２１】（７）セラミックス等脆性材料の破壊力学
的疲労試験においては試験範囲のＫ従って応力レベルが
低く弾性係数は大きいのでひずみのレベルは非常に低く
ヒステリシスの計測に必要な精度は金属の場合に較べ一
桁以上高くしかも未だ不明なことの多いき裂進展挙動、
機構を調べるにはヒステリシスの細部の形状をも計測す
る高い精度が必要である。一方試験片毎の特性のばらつ
きが大きく特に高温では現象も複雑で試験中その経過を
精度を下げてもオンラインに知りこれに応じ個々の試験
片につき試験中に試験条件を微調節する必要がある。(7) In the fracture mechanical fatigue test of brittle materials such as ceramics, the stress level is low due to K in the test range and the elastic modulus is large, so the strain level is very low and the accuracy required for hysteresis measurement is in the case of metal. Crack growth behavior, which is more than an order of magnitude higher than that of
In order to investigate the mechanism, it is necessary to have a high accuracy to measure the shape of the hysteresis details. On the other hand, there is a large variation in the characteristics of each test piece, and the phenomenon is complicated especially at high temperatures, and it is necessary to finely adjust the test conditions during the test for each test piece according to this even if the accuracy is reduced during the test even if the accuracy is lowered. .

【００２２】[0022]

【課題を解決するための手段】この発明に用いる試験片
とその負荷方式は、基本的には次の原理に基ずく。高硬
度、低靭性の脆性材料の破壊力学的疲労試験において、
図１（ａ）示すように、長さＬが、幅Ｗより大きく、通
常２倍から数倍程度の厚さＢの直方体形状の試験片
（１）の長さ方向の中心軸を含む幅の中央の面を試験断
面とし一端から長さ約Ｗ／２もしくはそれ以上の予き裂
（２）を入れた試験片を用い、試験断面と両側面との中
心より、それぞれ外側へｅ偏心した間隔ｌ＝Ｗ／２＋２
ｅで、試験断面に平行な面と予き裂側の端面との２つの
交差線上に、それぞれ中心軸に平行に合力がＰ／２の任
意形状の波形の片振繰り返し、部分片振り繰り返し、コ
ンプライアンスの動的計測のための小頻度の部分除荷を
含む静圧縮荷重のいずれかあるいはそれらの組み合わせ
を含む圧縮負荷を、予き裂側と反対側の端面にこれと釣
り合う合力がＰの圧縮負荷を負荷すると、試験断面上で
はき裂先端にはモード１成分のみの応力拡大係数Ｋ１を
生じ、これに沿いき裂を進展させることが出来る 。しか
してサンプナンの原理（Ｓａｉｎｔ−Ｖｅｎａｎｔ’ｓ
ｐｒｉｎｃｉｐｌｅ ：Ｂ．ｄｅ Ｓａｉｎｔ−Ｖｅ
ｎａｎｔ，“Ｍｅｍｏｉｒｅ ｄｅｓ Ｅｎｔｒａｎｇ
ｅｒｓ，”ｖｏｌ．１４，１８５５．）によりき裂先端
が両端面から十分離れた領域では古典的な梁理論が適用
出来るので、この領域を試験領域とすれば、〔数２〕、
〔数３〕、〔数４〕、〔数５〕、〔数６〕、〔数７〕に
示す簡単な計算により、予き裂側の端面のき裂の両側の
角変位は、対称性から左右等しく方向反対であるので相
対角変位θの負荷Ｐに対する線形の範囲でのコンプライ
アンススλ＝Δθ／ΔＰの、き裂進展量Δａに対する増
加Δλは〔数７〕に示すごとくΔａに正比例する。 A test piece used in the present invention
And its load method are basically based on the following principles. High hardness
In a fracture mechanical fatigue test of brittle materials with low degree and low toughness,
As shown in FIG. 1A, the length L is larger than the width W and
A rectangular parallelepiped test piece with a thickness B that is normally twice to several times
Test the center surface of the width including the central axis in the length direction of (1)
Pre-crack with a length of about W / 2 or more from one end to the surface
Using the test piece containing (2), place it between the test section and both sides.
Distances eccentric to the outside from the center e = W / 2 + 2
2e, a plane parallel to the test cross section and an end face on the pre-crack side
On the intersection line, the resultant force is P / 2 parallel to the center axis.
Repetitive single-sided waveform, partial partial-sided repeat,
Infrequent partial unloading for dynamic compliance measurement
Any of static compression load including or a combination thereof
The compressive load including the
When the resultant resultant force is a compressive load of P, on the test cross section
The stress intensity factor K1 of only the mode 1 component is applied to the crack tip.
It can occur and cracks can grow along it . Only
The principle of Saint-Phunan (Saint-Venant's
principle: B. de Saint-Ve
nant, “Memoire des Entrang
ers, "vol. 14, 1855.)
The classical beam theory is applied in the region where the
Since this can be done, if this area is used as the test area, [Equation 2],
[Equation 3], [Equation 4], [Equation 5], [Equation 6], [Equation 7]
The simple calculation shown shows that both sides of the crack on the end face on the pre-crack side
Due to the symmetry, the angular displacement is equal to the left and right,
Compliant in a linear range with respect to load P of diagonal displacement θ
Increase of anx λ = Δθ / ΔP with respect to crack growth amount Δa
The addition Δλ is directly proportional to Δa as shown in [Equation 7].

【００２３】[0023]

【数２】 [Equation 2]

【００２４】[0024]

【数３】 (Equation 3)

【００２５】[0025]

【数４】 [Equation 4]

【００２６】[0026]

【数５】 (Equation 5)

【００２７】[0027]

【数６】 (Equation 6)

【００２８】[0028]

【数７】 (Equation 7)

【００２９】またこの時き裂先端の応力拡大係数は対称
性からモード１成分のみとなり、その値Ｋ１は〔数
８〕、〔数９〕に示すエネルギー法を用いて、〔数１
０〕により〔数１１〕のように求まり、この領域では荷
重Ｐに比例しき裂長さに関係なく一定となる。以上のサ
ンブナンの原理による古典的な梁理論の計算が適用出来
る範囲は所定の精度、試験片の形状、予き裂側端面の負
荷Ｐ／２の負荷位置とともにこれと釣り合う反対側の試
験片端面上における合力Ｐの分布にも支配される。（図
１（ａ）に示すＰは負荷の合力を示し、図９にも示すよ
うに実際には必ずしも集中力を直接試験片端面に作用さ
すことを意味しない。）理論的にはこの分布を仮定して
数値弾性計算によらなければならないが概略は既存のデ
ータから推測でき、また予備試験や、アクリル板など低
コストでき裂進展挙動が目視出来るモデル材を用いた容
易な予備実験で推定出来る。合力Ｐの分布を予き裂側端
面の負荷Ｐ／２によるその近傍の梁理論による分布に近
づけるとこの範囲すなわち試験断面は広くとれる。試験
片への負荷は圧縮荷重であるので合力Ｐの負荷点を定め
る円筒ローラと予き裂反対側の試験片端面との間に中継
ぎブロックを置き試験片との接触面で、薄いステンレス
箔をはさみ、あるいは逆に当たりを盗むなどにより、合
力Ｐの分布をおおよそ加減することは容易で、所要の精
度にもよるが、通常試験片の両端面から約Ｗ／２を除い
た約Ｌ−Ｗを試験領域にとることが出来る。 At this time, the stress intensity factor at the crack tip is symmetric.
Due to the nature, only the mode 1 component is available, and its value K1 is
8], using the energy method shown in [Equation 9], [Equation 1
0] is obtained as shown in [Equation 11].
It is proportional to the weight P and is constant regardless of the crack length. More than
The classical beam theory calculation based on Mbnun's principle can be applied.
The range is the specified accuracy, the shape of the test piece, and the
A test on the opposite side that balances with the load position of load P / 2
It is also governed by the distribution of the resultant force P on the end surface of the test piece. (Figure
P shown in 1 (a) indicates the resultant force of the load, which is also shown in FIG.
As a matter of fact, the concentration force is not always applied directly to the end face of the test piece.
Does not mean that ) Assuming this distribution theoretically
It must be based on numerical elasticity calculation, but the outline is
Can be inferred from the
A model material that is cost-effective and allows visual observation of crack growth behavior
It can be estimated by a simple preliminary experiment. Pre-distribution of resultant force P
It is close to the beam theory distribution in the vicinity of the surface load P / 2.
In addition, this range, that is, the test cross section, can be wide. test
Since the load on one side is a compressive load, the load point of the resultant force P is determined.
Between the cylindrical roller and the end face of the test piece on the opposite side of the pre-crack
Place the block and place it in contact with the test piece.
By sandwiching the foil or stealing the converse,
It is easy to adjust the distribution of force P roughly, and
Depending on the degree, usually about W / 2 is removed from both end faces of the test piece.
About L-W can be taken in the test area.

【００３０】[0030]

【数８】 (Equation 8)

【００３１】[0031]

【数９】 [Equation 9]

【００３２】[0032]

【数１０】 [Equation 10]

【００３３】[0033]

【数１１】 [Equation 11]

【００３４】従って図１（ｂ）に示すようにＫ値がき裂
長さに関係なく荷重のみで定まる約Ｌ−Ｗの十分広い安
定き裂成長領域が荷重制御によって得られ、ヒステリシ
スを計測しその線形範囲のコンプライアンスを求めれば
直ちにき裂進展量が求まる。ヒステリシスの非線形かき
裂閉口による時はこのコンプライアンスは除荷時の直線
部の前記のいわゆる除荷弾性コンプライアンスとなる
が、後記の実施例の図１５（ｂ）のごとく固休摩擦的で
ブリッジング摩擦と判断される時にはヒステリシスの除
荷、負荷の初期を除いて摩擦力がほぼ一定におちつき反
対方向になると思われるほぼ平行になった直線部の平
均、すなわち図１５（ｂ）のＥＥ’線を線形範囲と考
え、そのコンプライアンスを取るべきで、ヒステリシス
の形状の細部等から判断すべきものであるが、一般に線
形コンプライアンスと略称することにする。Therefore, as shown in FIG. 1 (b), a sufficiently wide stable crack growth region of about L-W, where the K value is determined only by the load regardless of the crack length, is obtained by load control, and hysteresis is measured to determine its linear shape. If the compliance of the range is sought, the crack growth amount can be immediately obtained. When the non-linear crack closure of the hysteresis is used, this compliance is the so-called unloading elastic compliance of the straight line portion at the time of unloading, but as shown in FIG. When it is judged that the hysteresis is unloading and the frictional force is almost constant except for the initial stage of the load, the average of the straight line portions which are almost parallel, which is the EE 'line of FIG. It should be considered as a linear range, and its compliance should be taken, and it should be judged from the details of the shape of the hysteresis, etc., but it will be generally referred to as linear compliance.

【００３５】ここにＩはき裂の片側を高さＷ／２、厚さ
Ｂの梁と考えた時の断面二次モーメント、Ｍは負荷のこ
の梁に対する曲げモーメント、σｂをその公称曲げ応
力、σｃを負荷による試験片の平均圧縮応力、ａは予き
裂を含むき裂長さ、Ｅは縦弾性係数、νはポアッソン比
で、Ｕは試験片のひずみエネルギーのうち古典的な梁理
論による部分、Ｕ０は真の値との偏差でき裂先端が両端
から約Ｗ／２以上離れたいま考える試験領域では一定で
ある。またき裂面に沿った公称応力σｘ＝σｂ＋σｃは
次式に示すようになる。Where I is the second moment of area when one side of the crack is considered to be a beam with height W / 2 and thickness B, M is the bending moment of this beam with respect to this beam, and σb is its nominal bending stress. σc is the average compressive stress of the test piece due to the load, a is the crack length including a pre-crack, E is the longitudinal elastic modulus, ν is the Poisson's ratio, and U is the strain energy of the test piece based on the classical beam theory. , U0 can deviate from the true value, and is constant in the test region where the crack tip is separated from both ends by about W / 2 or more. Further, the nominal stress σx = σb + σc along the crack surface is expressed by the following equation.

【００３６】[0036]

【数１２】 (Equation 12)

【００３７】従って、ｅ＜Ｗ／１２の時は試験断面に沿
う応力は圧縮となるのでき裂は湾曲し進入し難くなりき
裂の試験断面に沿う直進を安定にする。しかし例えば
Ｗ＝３２ｍｍ、σｃ＝４０ ＭＰａ、ν＝０．３、とす
れば、荷重＝１２８００Ｎに対しＫ１＜３．０６ＭＰａ
√ｍとなり、試験片、負荷治具の寸法と負荷容量の関係
から実際上、Ｋ１をあまり大きくし難いのでかなり脆性
な材料以外には必ずし も実用的ではない。なおこれは最
も簡単な一つの安定限界の目安で試験例でもｅ＝Ｗ／８
で直進し、Ｗ／４では湾曲したものもある。 Therefore, when e <W / 12, it follows the test cross section.
The stress is compressive and the crack is curved and difficult to enter.
Stabilizes the straight line of the crack along the test section. But for example
W = 32 mm, σc = 40 MPa, ν = 0.3
If so, K1 <3.06 MPa for load = 1,800 N
√m, which is the relationship between the size of the test piece and load jig and the load capacity
Therefore, in practice, it is difficult to make K1 so large that it is quite brittle.
Not always be practical for other than such material. This is the maximum
Is a simple guideline for one stability limit, and in the test example, e = W / 8
Go straight on, and some are curved on W / 4.

【００３８】そこでより高靭性の材料に適用出来るよう
に、同じ試験片幅ＷでＫ１／Ｐを大きくするため、図２
に示すように試験断面を中心にこれ沿って試験片の表裏
両側もしくは裏面のみに長方形断面のガイド溝をもう
け、偏心量ｅを負荷の間隔１がＷの許す範囲で、もしく
は図３に示すようにさらに予き裂側の端面を外側に張り
出しこれを超えて大きくしてｅを増す。これによりＫ１
／Ｐはｅにほぼ比例して増すが、き裂が湾曲し易くなる
のでガイド溝により防ぎ直進さす。一方試験断面の厚さ
が試験片厚さＢから溝を差し引いた試験断面の正味厚さ
Ｂｎに減るのでこれによりさらにほぼ√（Ｂ／Ｂｎ）倍
になり、試験可能な応力拡大係数の値を大きくして、よ
り靭性の高い材料に適用範囲を拡げることができる。正
確には溝により試験断面の片側の断面の面積がＳからＳ
ｎへ減少し、二次モーメントがＩからＩｎへ減少し、試
験断面で切り離した両側をそれぞれ一つの梁と考えた時
の中立軸も外側へ移動し、偏心量ｅも半幅の中央でなく
この中立軸から測ったものを取りエネルギー法により以
下の式〔数１３〕、〔数１４〕、〔数１５〕、〔数１
６〕、〔数１７〕のように討算出来Ｋ１は〔数１８〕の
ごとくなる。 So that it can be applied to materials with higher toughness
In order to increase K1 / P with the same test piece width W,
As shown in Fig. 1, centering on the test section
There are rectangular guide grooves on both sides
The eccentricity e within the range where the load interval 1 allows W,
As shown in Fig. 3, the end face on the pre-crack side is further stretched outward.
The amount is increased beyond this to increase e. This makes K1
/ P increases almost in proportion to e, but cracks tend to bend
Since it is prevented by the guide groove, it goes straight. On the other hand, the thickness of the test section
Is the net thickness of the test section obtained by subtracting the groove from the specimen thickness B
Since it is reduced to Bn, this makes it approximately √ (B / Bn) times.
And increase the testable stress intensity factor value,
The application range can be expanded to materials with high toughness. Positive
To be precise, the area of the cross section on one side of the test cross section is S to S due to the groove.
n, and the second moment decreases from I to In,
When considering each side separated by the test section as one beam
The neutral axis also moves outward, and the eccentricity e is not in the center of the half width.
What is measured from this neutral axis is
The following equations [Equation 13], [Equation 14], [Equation 15], [Equation 1]
6] and [Equation 17], the calculation K1 is [Equation 18].
I'll get tired of it.

【００３９】[0039]

【数１３】 (Equation 13)

【００４０】[0040]

【数１４】 [Equation 14]

【００４１】[0041]

【数１５】 (Equation 15)

【００４２】[0042]

【数１６】 [Equation 16]

【００４３】[0043]

【数１７】 [Equation 17]

【００４４】[0044]

【数１８】 (Equation 18)

【００４５】ガイド溝によるＫ１への影響は√（Ｂｎ／
Ｂ）の項以外は小さく試験片幅Ｗ＝２０ｍｍ、溝の幅
ｗ、深さがｔがｗ／Ｗ＝２／２０、ｔ／Ｂ＝３／１０、
Ｂｎ／Ｂ＝４／１０、ｅ／Ｗ＝８／２０の時に約＋４．
９％、Ｗ＝３２ｍｍ、ｗ／Ｗ＝ ２／３２、ｔ／Ｂ＝３／
１０、Ｂｎ／Ｂ＝４／１０、ｅ／Ｗ＝５／３２の時に約
＋２．３％にとどまる。線形コンプライアンス増加Δλ
のき裂進展量Δａに対する比例定数もＩ／Ｉｎ倍になる
のみでそれぞれ約＋１８．４％、１８．１％である。こ
のような対称性をもつモード１き裂進展の場合ガイド溝
の断面形状は長方形にてもき裂は底の平坦部の両隅の拘
束のためかほぼ平坦部の中央を進み良好な結果が得られ
た。図３の（５）は計測用に引出し腕を取り付けに必要
な溝で、（２’）は頂角６０°程度のシェブロン形予き
裂でき裂幅が０．７ｍｍ程度と多少厚くとも安定にき裂
進展を開始するので便利に用いられる。ガイド溝の深さ
が一定の時は試験断面の試験領域ではき裂が進展しても
Ｋ値は負荷のみに比例する中立の安定であるが、高温領
域などでき裂進展挙動自身が固有の不安定性を持つ時は
ガイド溝の深さを漸減し正の安定性を持たせ試験を容易
にすることもできる。 The influence of the guide groove on K1 is √ (Bn /
Except for the item B), the width of the test piece is small W = 20 mm, the width of the groove
w, depth t is w / W = 2/20, t / B = 3/10,
About +4 when Bn / B = 4/10 and e / W = 8/20.
9%, W = 32 mm, w / W = 2/32 , t / B = 3 /
About 10, Bn / B = 4/10, e / W = 5/32
It stays at + 2.3%. Linear compliance increase Δλ
The constant of proportionality to the crack growth amount Δa also becomes I / In times
Only + 18.4% and 18.1% respectively. This
In the case of Mode 1 crack growth with symmetry like a guide groove
Although the cross-sectional shape of each is rectangular, the cracks are
Probably because of the bundle, we proceeded to the center of the flat part and obtained good results.
It was Figure 5 (5) is required to attach the drawer arm for measurement
Groove (2 ') is chevron type with apex angle of about 60 °
Can crack and crack stably even if the crack width is about 0.7 mm
Conveniently used as it initiates progress. Guide groove depth
Is constant, even if a crack propagates in the test area of the test section,
The K value is neutral and stable in proportion to the load only,
When the crack growth behavior itself has its own instability
Easy test by gradually reducing the depth of the guide groove and providing positive stability
You can also

【００４６】コンプライアンスの計測は理論的には静的
にもできるはずであるが、実際には、とくに高温試験で
は零点のドリフトの問題があり、線形部分の判定にも動
的ヒステリシスの計測によるのがよく静疲労試験の際も
動的ヒステリシスの計測のためにき裂進展に影響を与え
ない程度の小頻度の部分除荷を行う。 The measurement of compliance is theoretically static
It should be possible, but in practice, especially in high temperature tests
Has the problem of zero drift, and it also works for the determination of the linear part.
It is better to measure the dynamic hysteresis, even during static fatigue tests.
Affects crack growth for dynamic hysteresis measurement
Partial unloading is performed with a small frequency that does not occur.

【００４７】図２（ｃ）は表面の直接観察などのためガ
イド溝を裏面のみにした場合で、このときも負荷点の位
置を板厚方向にずらして、試験断面の裏と表でき裂進展
の差をある程度に抑えれば、Ｋ値はエネルギー法による
前縁の平均値で、き裂進展量もコンプライアンスによる
計測値で前縁の平均値であるので、その影響はあまり大
きくない。 FIG . 2 (c) shows a gas for direct observation of the surface.
When the id groove is only on the back side, the load point
The cracks on the back and front of the test cross section
If the difference between
The average value of the leading edge.
Since the measured value is the average value of the leading edge, its effect is not so great.
I don't like it.

【００４８】図４に示すごとく予き裂側の端面の両側の
圧縮負荷Ｐ／２をそれぞれ予き裂の片側の断面の中立軸
の両側でなく同じ側に、これと釣り合う反対側の端面の
圧縮負荷の合力Ｐも中心軸の同じ側に等しく偏心量ｅ偏
心させ中心軸と平行に加える。Ｐは予き裂側と同じよう
に二つに分割しても端面から離れれば等価で、このよう
に置き換えて考えた時、試験断面で仮に分割して考える
と両側の梁の圧縮及び曲げ変形は同じで分割面には面に
沿った相対せん断変位のみが生ずることから、 き裂先端
の応力拡大係数はモード２成分のみのＫ２を生じモード
１成分はないことがわかる。従って中心線に沿うガイド
溝の中央に沿ってき裂を進展させれば、き裂先端が両端
面から約Ｗ／２以上離れている約Ｌ−Ｗの領域ではＫ２
の値は前と同様に以下の数式〔数１９〕、〔数２０〕、
〔数２１〕、〔数２２〕、〔数２３〕により計算でき、
〔数２２〕に示すようになり、この領域ではき裂長さに
関係なく荷重に比例し定まるので荷重制御によりＫ２値
を直接制御してき裂を安定に成長させることができる。
ここに、Ｉｔは試験片全体の正味断面の断面二次モーメ
ントである。しかしモード２や以下に述べる混合モード
の場合は応力は試験断面に関し対称ではなく、一般に脆
性材料ではモード２に対しモード１に対してより強く、
材料、方位によりき裂はガイド溝の効果によっても必ず
しも試験断面に沿って進展するとは限らない。しかしこ
の試験が必要となるのはコンポジットなど異方性が強く
層間剥離、層間せん断などある弱い面に沿ってのき裂進
展挙動の計測であり、実際にはこの点は問題とならな
い。 As shown in FIG . 4, both ends of the pre-cracked end face are
Compressive load P / 2 at the neutral axis of one side of the precrack
On the same side, but not on both sides, of the opposite end face
The resultant force P of the compression load is also equal to the same side of the central axis
Add it parallel to the central axis. P is the same as the pre-crack side
Even if it is divided into two, it is equivalent if it is separated from the end face, like this
When you think about it by replacing it with
And the compression and bending deformation of the beams on both sides are the same,
Since only along relative shear displacement occurs, the crack tip
The stress intensity factor of causes a K2 of only mode 2 component
It can be seen that there is no one component. Therefore a guide along the center line
If the crack propagates along the center of the groove, the crack tip will
K2 in the area of about L-W, which is more than about W / 2 away from the surface
The value of is the same as in the following equations [Equation 19], [Equation 20],
It can be calculated by [Equation 21], [Equation 22], and [Equation 23],
As shown in [Equation 22], the crack length is
Regardless of the load, it is determined in proportion to the load.
Can be directly controlled to grow a crack stably.
Where It is the cross sectional secondary moment of the net cross section of the entire test piece.
It is an event. However, Mode 2 and the mixed mode described below
, The stress is not symmetric with respect to the test section and is generally brittle.
Is stronger for Mode 2 than for Mode 1,
Depending on the material and orientation, the cracks will always be due to the effect of the guide groove.
However, it does not always progress along the test section. But this
Is required because the anisotropy is strong such as composite
Crack propagation along weak surfaces such as delamination and shear
This is a measurement of the spreading behavior, and this point is not a problem in practice.
Yes.

【００４９】[0049]

【数１９】 [Formula 19]

【００５０】[0050]

【数２０】 (Equation 20)

【００５１】[0051]

【数２１】 [Equation 21]

【００５２】[0052]

【数２２】 [Equation 22]

【００５３】[0053]

【数２３】 (Equation 23)

【００５４】またこの領域においては予き裂側の端面の
き裂の両側の角変位θ／２はこの場合には大きさ向きと
も同じとなるが、負荷Ｐに対する線形コンプライアンス
の、き裂進展量Δａに対する増加量ΔλはΔａに正比例
し、コンプライアンスを計測すればその増加から容易に
き裂進展量が求まる。In this region, the angular displacements θ / 2 on both sides of the crack on the end face on the side of the pre-crack are the same in the magnitude direction in this case, but the crack propagation amount of the linear compliance with respect to the load P is the same. The amount of increase Δλ with respect to Δa is directly proportional to Δa, and if the compliance is measured, the amount of crack growth can be easily obtained from the increase.

【００５５】図５は所期のＫ１値を与える図２の負荷と
所期のＫ２値を与える図４の負荷を重ね合わせ試験片両
端面の負荷を予き裂両側と他の端面に一つづつの三つに
合成したもので、中心線に沿う予き裂からガイド溝の中
央に沿ってき裂を進展させれば、き裂先端が両端面から
約Ｗ／２以上離れる約Ｌ−Ｗの間の試験領域では、Ｋ
１、Ｋ２値はき裂長さに関係なく荷重に比例し定まるの
で荷重制御によりこれらを直接制御しき裂を安定に成長
させることができる。またこの領域においては、 各負荷
の比が一定であれば、予き裂側の端面のき裂の両側の角
変位、き裂の両側の相対変位の中心軸方向の成分はいず
れも、負荷に対し線形に変化する範囲での、コンプライ
アンスのき裂進展量に対する増加量はき裂進展量に正比
例するので、そのいずれかもしくはこれらを組み合わせ
た計測しやすいコンプライアンスを計測すればその増加
量からき裂進展量を求めることができる。 FIG . 5 shows the load of FIG. 2 which gives the desired K1 value.
Both test pieces are overlaid with the load shown in Fig. 4 to give the desired K2 value.
End face load is divided into three, one on each side of the pre-crack and the other end face
It is a synthetic material, and it is used in the guide groove from the pre-crack along the center line.
If the crack propagates along the center, the crack tip will be
In the test area between about L-W apart by about W / 2 or more, K
1, K2 value is determined in proportion to load regardless of crack length
By controlling the load directly with, the crack can be grown stably.
Can be made. In this area, each load
If the ratio is constant, the corners on both sides of the crack on the end face on the pre-crack side
None of the displacement and relative displacement components on both sides of the crack in the direction of the central axis
This is also due to compliance in the range that changes linearly with load.
The amount of increase in crack growth from an anth is directly proportional to the amount of crack growth.
For example, either one or a combination of these
Easy to measure Compliance increases by measuring compliance
The crack growth amount can be obtained from the amount.

【００５６】図６、図７は図２、図４の場合の試験断面
を中心軸より偏らせることができることを示すもので、
図に示すように予き裂の両側の荷重を試験断面の両側の
面積比に荷重と偏心量の積すなわちモーメントを断面二
次モーメントの比に配分し他の端面の合力をこれと釣り
合うようにすれば試験断面で仮に分割して考えると両側
の梁の圧縮変形は同じで、曲げ変形も大きさは同じで、
図６の場合は向きが反対で分割面には面に垂直な相対垂
直変位のみが生じ、従って中心線に沿うガイド溝の中央
に沿ってき裂を進展させれば、き裂先端の応力拡大係数
はモード１成分のみのＫ１を生じモード２成分はないこ
とがわかる。図７の場合には向きも同じで分割面には面
に沿った相対せん断変位のみが生ずることから、中心線
に沿うガイド溝の中央に沿ってき裂を進展させれば、き
裂先端の応力拡大係数はモード２成分のみのＫ２を生じ
モード１成分はないことがわかる。両方を組み合せば図
８のようになる。FIGS. 6 and 7 show that the test cross section in the case of FIGS. 2 and 4 can be deviated from the central axis.
As shown in the figure, the load on both sides of the pre-crack is distributed to the area ratio on both sides of the test cross section, and the product of the load and the eccentricity, that is, the moment is distributed to the ratio of the second moment of area, and the resultant force of the other end faces is balanced with this. Then, if the test cross section is divided and considered, the compressive deformation of the beams on both sides is the same, and the bending deformation is the same.
In the case of FIG. 6, only the relative vertical displacement perpendicular to the surface occurs on the split surface and the direction is opposite. Therefore, if the crack propagates along the center of the guide groove along the center line, the stress intensity factor of the crack tip is increased. It can be seen that produces K1 of only the mode 1 component and that there is no mode 2 component. In the case of Fig. 7, since the orientation is the same and only relative shear displacement occurs along the split surface, if the crack propagates along the center of the guide groove along the centerline, the stress at the crack tip will be increased. It can be seen that the magnification factor causes K2 of only the mode 2 component and that there is no mode 1 component. If both are combined, it becomes like FIG.

【００５７】この発明を実施するための負荷計測加熱装
置の正面図を図９に示す。図３の形状及び負荷状態の試
験片の場合を示すが試験片（１）の中央の試験領域を高
周波間接加熱し炉外に置いた両端面に（２１）（２２）
で水冷した、負荷治具端部（２０）を経て電気油圧サー
ボ試験機で繰り返し圧縮負荷を加え、炉外の一端面のき
裂両側での相対角変位を測定腕（１１）で引出して、
（１５）で熱絶縁した室温部分の（１７）、（１７’）
の間で伸び計（１６）で計測し、試験機のロードセルで
計測した荷重とのヒステリシスからいわゆる除荷弾性コ
ンプライアンスもしくは前記のようにより一般化した線
形コンプライアンスによりき裂を直接観察することなく
き裂進展量を求める。電気油圧サーボ試験機で加える負
荷は若干の基本荷重を含む繰り返し片振圧縮荷重を主と
するが、部分片振り、要すれば少頻度の除荷弾性コンプ
ライアンス法による計測のための部分除荷を含む静圧縮
荷重等をも含むものである。これのみではＫ値は負にな
らないが図９に示すように試験片の試験断面の片側の中
立軸から１０の計測腕の両端近くにＰｅ／４／１０以下
の小さい反対方向の副静荷重Ｐ０を柔いバネ（２８）に
より負荷することにより両振り、部分両振りにすること
が出来る。FIG. 9 shows a front view of a load measuring and heating apparatus for carrying out the present invention. Fig. 3 shows the case of the test piece in the shape and the loaded state, but the central test area of the test piece (1) is subjected to high-frequency indirect heating to both end faces placed outside the furnace (21) (22)
Repeatedly compressive load with an electro-hydraulic servo tester through the end of the load jig (20) water-cooled with, and pull out the relative angular displacement on both sides of the crack on one end face outside the furnace with the measuring arm (11),
(17), (17 ') of the room temperature part thermally insulated in (15)
Between the stress measured by an extensometer (16) and the load measured by the load cell of the tester and the hysteresis by the so-called unloading elastic compliance or the generalized linear compliance described above without directly observing the crack. Find the amount of progress. The load applied by the electro-hydraulic servo tester is mainly a cyclic unidirectional compression load including some basic loads, but partial unilateral oscillating, and if necessary, partial unloading for measurement by the elastic compliance method with less frequent unloading. It also includes static compression load and the like. Although this alone does not make the K value negative, as shown in FIG. 9, a small auxiliary static load P0 of Pe / 4/10 or less in the opposite direction from the neutral axis on one side of the test cross section of the test piece near both ends of the measuring arm 10 It is possible to make both swings and partial swings by loading the spring with a soft spring (28).

【００５８】負荷の偏心量ｅは通常数ｍｍ以下で小さい
ので、荷重点の位置、荷重の方向の精度が重要である。
また予き裂側端面では負荷サイクル毎に試験片の変形に
よりき裂の両側で１００分の数ｍｍ程度の相対変位を生
ずるのでこれを逃がし負荷する必要がある。しかし負荷
が圧縮であるので、これらは図９に示すように、セラミ
ックスの円筒ローラ（６）の転がり接触を用いることに
より容易にみたされる。負荷を試験片厚さの中央に保つ
ためにも半円筒ローラ（７）による線接触で荷重位置を
定め、また予き裂両側の負荷を均分、あるいは所定の配
分をするにも転がり接触による平衡梁を用いた。（２
５）は試験片の素材寸法の関係で試験片の長さが十分で
ない時にセラミックスのブロックをインコネル（２６）
で位置ぎめして接ぎ足したもので負荷が圧縮なので可能
である。Since the eccentricity e of the load is usually as small as several mm or less, the accuracy of the position of the load point and the direction of the load is important.
Further, at the end face on the side of the pre-crack, relative displacement of about several hundredths of a mm is generated on both sides of the crack due to deformation of the test piece at each load cycle, so it is necessary to escape and load this. However, since the load is compression, they are easily met by using the rolling contact of a ceramic cylindrical roller (6), as shown in FIG. The load position is determined by line contact with the semi-cylindrical roller (7) to keep the load at the center of the thickness of the test piece, and the rolling contact is used to evenly distribute the load on both sides of the pre-crack or to give a predetermined distribution. A balanced beam was used. (2
5) Inconel (26) is a ceramic block when the length of the test piece is insufficient due to the material size of the test piece.
This is possible because the load is compressed by positioning and adding with.

【００５９】図１７は部分断面図、図１８は部分側面図
で（３０）、（３１）はスーパーカンタルの間接加熱材
で軟質の耐火材（３３）を経て高周波コイル（２９）で
保持されいずれも試験片取り付けの容易なよう前後に二
分割される。間接加熱材（３０）、（３１）の上下の厚
さ、位置、間隔を調節、要すれば中間にもう一つ小片を
加え図１０に示すごとく上下方向にかかわらず２０ｍｍ
以上の領域の試験片の温度分布を±１０Ｋ以内に均一に
出来た。高周波加熱装置の温度制御は熱電対（３２）で
しているが試験片上の三点以上で測温パソコンでき裂先
端位置の温度を内挿制御するか、き裂進展にともない炉
を移動すればき裂先端近傍の温度の精度は上げることが
できる。また中心軸を水平にした場合、導電性材料の直
接高周波加熱、複数熱源による輻射加熱の場合には容易
にこれ以上の精度を得ることが出来る。FIG. 17 is a partial sectional view, and FIG. 18 is a partial side view. (30) and (31) are super-kanthal indirect heating materials, which are held by a high-frequency coil (29) through a soft refractory material (33). Is also divided into two parts, front and rear, for easy attachment of the test piece. Adjust the vertical thickness, position, and spacing of the indirect heating materials (30) and (31), and add another small piece in the middle if necessary, as shown in FIG.
The temperature distribution of the test piece in the above region could be made uniform within ± 10K. The temperature of the high frequency heating device is controlled by a thermocouple (32), but if the temperature at the crack tip position can be controlled by inserting a temperature measuring computer with three or more points on the test piece, or if the furnace moves as the crack progresses. The accuracy of the temperature near the crack tip can be increased. Further, when the central axis is horizontal, higher precision can be easily obtained in the case of direct high-frequency heating of the conductive material and radiant heating by a plurality of heat sources.

【００６０】セラミックス等脆性高強度材料ではコンプ
ライアンスからき裂進展量を求めるために計測すべき歪
み或いは変形量が小さいのでヒステリシスの計測に必要
な精度は金属の場合に較べ一桁以上高くしかも未だ不明
なことの多いき裂進展挙動、機構を調べるためヒステリ
シスの細部の形状の情報を得るにも高い精度が必要であ
る。一方試験月毎の特性のばらつきが大きく特に高温で
は現象も複雑で試験中その経過を精度を下げてもオンラ
インに知りこれに応じ個々の試験につき時々刻々試験条
件を調整する必要がある。本発明では図１１にブロック
線図を示す試験計測システムにより、パーソナルコンピ
ューターのＤＡ変換器により電気油圧サーボ試験機を駆
動し、疲労試験中連続して荷重−変形ヒステリシスのデ
ータを荷重周期に同期して大量に採取し、同一位相のデ
ータを加算平均してＳ／Ｎ比を高め、高精度化するとと
もに圧縮する。まず低精度のオンライン表示のため予め
設定した最小限の圧縮を行い荷重、Ｋ値、き裂進展長
さ、進展速度をオンライン表示し、試験中の試験条件を
微調節する。一方計測値のばらつき及びヒステリシスの
変化を計算し、両者から最適な期間を定めてデータを圧
縮する最適高精度化処理を行ってハードディスクに落
し、オフラインに高精度のこれら試験結果を求めるとと
もに詳細に荷重−変形ヒステリシスを調べ、き裂開閉口
挙動、ブリッジング現象等き裂進展挙動、機構に関する
細部の情報得る。In a brittle high-strength material such as ceramics, since the strain or deformation amount to be measured in order to obtain the crack growth amount from compliance is small, the accuracy required for hysteresis measurement is one digit or more higher than that of metal, and it is still unknown. In order to investigate the crack growth behavior and mechanism that often occur, it is necessary to obtain high precision in order to obtain information on the detailed shape of hysteresis. On the other hand, there is a large variation in characteristics between test months, and the phenomenon is complicated especially at high temperatures, and it is necessary to know the progress of the test online during the test even if the accuracy is lowered, and to adjust the test conditions for each test accordingly. In the present invention, the electromechanical servo tester is driven by the DA converter of the personal computer by the test measurement system whose block diagram is shown in FIG. 11, and the load-deformation hysteresis data is continuously synchronized with the load cycle during the fatigue test. A large amount of data is sampled, and the data of the same phase is added and averaged to increase the S / N ratio to improve accuracy and compress. First, for online display with low accuracy, preset minimum compression is performed, and the load, K value, crack growth length, and growth rate are displayed online, and the test conditions during the test are finely adjusted. On the other hand, the variation of the measured value and the change of the hysteresis are calculated, the optimum period is determined from both, and the data is compressed to the optimum precision to drop it on the hard disk. The load-deformation hysteresis is investigated to obtain detailed information on crack opening / closing behavior, crack propagation behavior such as bridging phenomenon, and mechanism.

【００６１】[0061]

【実施例】５０ＫＮインストロン電気油圧サーボ試験機
に、図９に示すような負荷装置を取り付け、図１１に示
すような試験システムを構成して片振り繰返し疲労試験
を行った。材料は前記の偏心圧縮負荷方式では安定な試
験が出来なかった硬度Ｈｖ約１５００の窒化けい素で５
Ｈｚ応力比Ｒ＝０．３の試験の結果図１２に示すように
安定な試験が出来て、図１２（ｂ）に示すようなｄａ／
ｄｎ−Ｋｍａｘ曲線がえられた。この結果はさきに偏心
圧縮負荷方式では安定な試験が出来た硬度Ｈｖ約１３０
０のものとは同じく窒化けい素ではあるが明らかにｄａ
／ｄｎ−Ｋｍａｘ曲線の傾斜がかなり大きくさきの推測
を裏付ける。なおこの場合には荷重を比較的速やかに２
万サイクル程度の間に下降上昇していて、図１２（ａ）
に示すようにデータをき裂長さで数ｍｍ程度の間に取っ
ている。EXAMPLE A load device as shown in FIG. 9 was attached to a 50KN Instron electrohydraulic servo tester, and a test system as shown in FIG. The material was silicon nitride with a hardness Hv of about 1500, which could not be stably tested by the above-mentioned eccentric compression load method.
As a result of the test with the Hz stress ratio R = 0.3, a stable test can be performed as shown in FIG. 12, and da / as shown in FIG.
A dn-Kmax curve was obtained. As a result, the hardness Hv of about 130 was able to be stably tested by the eccentric compression load method.
0 is the same as silicon nitride, but obviously da
The slope of the / dn-Kmax curve is quite large and supports the previous speculation. In this case, the load is relatively quickly set to 2
It is descending and ascending during about 10,000 cycles, and is shown in Fig. 12 (a).
As shown in, the data is taken within a crack length of several mm.

【００６２】図１３、図１４は同じ材料ほぼ同じ条件で
も荷重の上昇率を極く小さしく４０万サイクル以上試験
をつづけたもので、き裂が１０ｍｍ以上進むと図に見ら
れるように荷重従ってＫ値が増加しているのにき裂進展
速度が減少しだして図１３（ｂ）に示すようにｄａ／ｄ
ｎ−Ｋｍａｘ曲線が一つの曲線にならない。この時図１
５（ａ）に示す計測した試験片の予き裂側の端面のき裂
の両側の相対角変位θから荷重Ｐに比例する量を引算し
変位軸Ｄを充分拡大した引算拡大ヒステリシスの一例の
形状およびこれを復元した図１５（ｂ）のモデル図から
考えて見ると、これは金属における塑性変形の場合に負
荷の終わり近くで下に湾曲し除荷始めからいわゆる除荷
弾性線となるのとは異なり除荷の始めに上に負荷の始め
に下に湾曲しその後直線になるので方向がかわったとき
にすべり始め一定の摩擦力に落ち着く固体摩擦的な力に
起因するものと思われ、いわゆるブリッジングフリクシ
ョンにより減速が生じていることを示唆するものと考え
られる。図中Ａはヒステリシスの面積、Ｒは摩擦力で、
ｆはほぼＲを評価でき簡単に求まる無次元量ｆ＝Ａ／Ｐ
／Δθである。この時は除荷負荷の直線部分を平均した
ＥＥ’線が定常になった反対方向の摩擦力が打ち消され
て近似的に弾性線になると思われる。図１４（ａ）と
（ｂ）を見較べると、ｄａ／ｄｎの減少がＡ、ｆの増加
に起因することが推測される。FIGS. 13 and 14 show that the rate of increase in load is extremely small even under the same conditions of the same material, and the test is continued for 400,000 cycles or more. As the crack progresses by 10 mm or more, the load follows the load as shown in the figure. As the K value increases, the crack growth rate begins to decrease, and as shown in FIG. 13 (b), da / d
The n-Kmax curve does not become one curve. Figure 1 at this time
5 (a), the amount of proportional to the load P is subtracted from the relative angular displacement θ on both sides of the crack on the pre-crack side end surface of the measured test piece, and the displacement axis D is sufficiently expanded to obtain the subtraction expansion hysteresis Considering the shape of an example and the model diagram of FIG. 15 (b), which is a restored shape, this shows that in the case of plastic deformation in metal, it bends downward near the end of the load and becomes a so-called unloading elastic line from the beginning of unloading. In contrast to the above, at the beginning of unloading the curve bends downward at the beginning of the load and then becomes a straight line, so when the direction changes, it begins to slip and settles to a constant frictional force. It is considered that this suggests that deceleration is caused by so-called bridging friction. In the figure, A is the area of hysteresis, R is the frictional force,
f is a dimensionless quantity that can easily evaluate R and can be easily calculated f = A / P
/ Δθ. At this time, it is considered that the EE 'line obtained by averaging the straight line portion of the unloading load becomes steady and the frictional force in the opposite direction is canceled out to become an elastic line approximately. Comparing FIGS. 14A and 14B, it is estimated that the decrease in da / dn is due to the increase in A and f.

【００６３】図１６は応力比を変動させた時の応力比の
効果とブリッジングフリクシヨンによると思われる減速
との複合した場合効果の計測例である。FIG. 16 shows a measurement example of the combined effect of the effect of the stress ratio when the stress ratio is varied and the deceleration which is considered to be due to bridging friction.

【００６４】[0064]

【発明の効果】以上に詳しく説明したように、本発明の
方法及び装置を用いると、従前の方法はもとより発明者
らによるさきの偏心圧縮負荷方式よりもより容易な荷重
制御により十分広いき裂進展の安定領域でセラミックス
等の高硬度脆性材料からより破壊靭性値の高い耐熱高強
度無機新素材の両振、片振繰返し疲労、静疲労を含む広
義の破壊力学的疲労試験を行うことができ、またそれを
自動化することができる。As described in detail above, when the method and apparatus of the present invention are used, a sufficiently wide crack can be provided by easier load control than the conventional method and the eccentric compression load method of the inventors. It is possible to perform a broad-ranging fracture mechanical fatigue test that includes both vibration, single-sided cyclic fatigue, and static fatigue of a new heat-resistant high-strength inorganic material with a higher fracture toughness value from high hardness and brittle materials such as ceramics in the stable region of progress. , Also it can be automated.

【００６５】またこれらの材料の初期き裂のバラッキを
避けてき裂開閉口挙動、ブリッジングフリクション等を
含むき裂進展特性を求めることができ、疲労特性を明ら
かにするとともにこれらの挙動の解明に関する詳細な情
報を得ることもできる。また一つの試験片から非常に多
くの情報が得られるため試験片毎の材質のバラツキを避
けて疲労き裂進展の応力依存性、繰返数依存性、時間依
存性、変動荷重下のき裂進展則等の法則性を抽出し易
い。Further, crack propagation characteristics including crack opening / closing behavior, bridging friction, etc. can be obtained by avoiding the cracking of the initial cracks of these materials, and the fatigue characteristics can be clarified and the behaviors can be clarified. You can also get detailed information. In addition, since a large amount of information can be obtained from one test piece, avoid variations in the material of each test piece, stress dependence of fatigue crack growth, repeatability dependence, time dependence, crack under variable load. It is easy to extract laws such as progress rules.

【００６６】さらに本発明によると１７００Ｋに至る極
高温に到る領域を含む試験が可能となり、これらの領域
を含み、セラミックス、サーメット等の耐熱高強度無機
新素材の繰返し疲労、静疲労、クリープ等の基礎的な因
子を分離解明することができる等の有効な手段を与える
ものである。 またこれをモード２及びモード１、２混合
き裂進展試験の場合に拡張することによりいままでほと
んどなかった無機系複合材料の強度特性及び破壊機構の
解明に有効な定量的なき裂進展試験方法を与えるもので
ある。 Further, according to the present invention, a pole reaching 1700K
It is possible to perform tests including areas that reach high temperatures, and
Including heat resistant high strength inorganic such as ceramics and cermet
Basic factors such as cyclic fatigue, static fatigue, and creep of new materials
Give effective means such as separation and elucidation of offspring
It is a thing. In addition, this is mixed with mode 2 and mode 1, 2.
By expanding to the case of crack growth tests,
Of the strength characteristics and fracture mechanism of inorganic composite materials
It provides a quantitative crack growth test method effective for elucidation.
is there.

【図面の簡単な説明】[Brief description of drawings]

【図１】（ａ）は本発明に使用する試験片と負荷状態
で、試験断面の応力拡大係数をモード１成分のみにする
場合を示す試験片の基本的な形状および負荷状態を示す
正面図。（ｂ）はき裂進展にともなうＫ１値の変化で試
験領域でほぼ一定となる本発明の基本的な原理を示す。FIG. 1 (a) is a front view showing the basic shape and load state of the test piece used in the present invention and the loaded state, showing the case where the stress intensity factor of the test section is set to only the mode 1 component. . (B) shows the basic principle of the present invention in which the K1 value changes with crack growth and becomes almost constant in the test region.

【図２】（ａ）はガイド溝付き試験片を示す正面図、
（ｂ）は両側溝の場合の平面図、（ｃ）は片側溝の場合
の平面図。2A is a front view showing a test piece with a guide groove, FIG.
(B) is a plan view in the case of a double-sided groove, (c) is a plan view in the case of a single-sided groove.

【図３】ガイド溝および負荷点の範囲を拡げるため予き
裂側端面を外側へ張り出した形状の試験片を示す三面
図。 [Fig. 3] Preliminary to widen the range of the guide groove and load point
Three faces showing a test piece with the crack end face protruding outward
Fig.

【図４】試験断面の応力拡大係数をモード２成分のみに
する負荷方法を示す正面図。FIG. 4 is a front view showing a loading method in which a stress intensity factor of a test section is set to a mode 2 component only.

【図５】試験断面の応力拡大係数をモード１、モード２
成分混合にする負荷方法を示す正面図。FIG. 5 shows the stress intensity factors of the test cross section in mode 1 and mode 2
The front view which shows the loading method which mixes components.

【図６】試験断面を試験片の中央にしない時に応力拡大
係数をモード１成分のみにする負荷方法を示す正面図。FIG. 6 is a front view showing a loading method in which the stress intensity factor is only the mode 1 component when the test cross section is not centered on the test piece.

【図７】試験断面を試験片の中央にしない時に応力拡大
係数をモード２成分のみにする負荷方法を示す正面図。FIG. 7 is a front view showing a loading method in which the stress intensity factor is only the mode 2 component when the test cross section is not in the center of the test piece.

【図８】試験断面を試験片の中央にしない時に応力拡大
係数をモード１、モード２成分混合にする負荷方法を示
す正面図。FIG. 8 is a front view showing a loading method in which the stress intensity factors are mixed in mode 1 and mode 2 components when the test cross section is not centered on the test piece.

【図９】本発明を実施するための負荷計測加熱装置の具
体例の正面図。FIG. 9 is a front view of a specific example of a load measuring and heating device for carrying out the present invention.

【図１０】図９、図１７に示す高周波間接加熱炉の垂直
断面図と試験片の垂直温度分布の実測例を示すグラフ。 FIG. 10 is a vertical view of the high frequency indirect heating furnace shown in FIGS. 9 and 17.
Sectional drawing and the graph which shows the measurement example of the vertical temperature distribution of a test piece.

【図１１】本発明を実施するための負荷計測システムを
示すブロックダイヤグラム。FIG. 11 is a block diagram showing a load measuring system for carrying out the present invention.

【図１２】本発明の方法及び装置による窒化けい素のき
裂進展挙動の計測の荷重増減率の大きい場合の一例で、
（ａ）はｄａ／ｄｎ−ａ 曲線、（ｂ）はｄａ／ｄｎ−
Ｋｍａｘ曲線を示すグラフ。FIG. 12 shows an example of a case where the load increase / decrease rate is large in the measurement of the crack growth behavior of silicon nitride by the method and apparatus of the present invention,
(A) is a da / dn-a curve, (b) is da / dn-
The graph which shows a Kmax curve.

【図１３】図１２と同じ窒化けい素のき裂進展挙動の計
測例の荷重増加率の小さい場合の一例で、（ａ）はｄａ
／ｄｎ−ａ 曲線、（ｂ）はｄａ／ｄｎ−Ｋｍａｘ曲線
を示すグラフ。13 is an example of a case where the load increase rate is small in the example of measuring the crack growth behavior of silicon nitride, which is the same as FIG. 12, and (a) is da
/ Dn-a curve, (b) is a graph showing a da / dn-Kmax curve.

【図１４】図１３に示した荷重増加率の小さいの場合の
窒化けい素のき裂進展挙動の計測例で，（ａ）はＫｍａ
ｘ，ａ，ｄａ／ｄｎ−Ｎ 曲線、（ｂ）はＡ，ｆ（無次
元摩擦力）−Ｎ 曲線を示すグラフ。FIG. 14 is a measurement example of the crack growth behavior of silicon nitride when the load increase rate is small as shown in FIG. 13, where (a) is Kma.
x, a, da / dn-N curve, (b) is a graph showing A, f (dimensional frictional force) -N curve.

【図１５】図１３に示した荷重増加率の小さいの場合の
窒化けい素のき裂進展挙動の計測例の場合で，（ａ）は
引算拡大ヒステリシス曲線の計測例のグラフ、（ｂ）は
復元したヒステリシスのモデル化したグラフ。FIG. 15A is a graph showing a measurement example of crack growth behavior of silicon nitride when the load increase rate is small as shown in FIG. 13, and FIG. 15A is a graph of a measurement example of a subtractive expansion hysteresis curve; Is a modeled graph of the restored hysteresis.

【図１６】図１２と同じ窒化けい素のき裂進展挙動の計
測例であるが、応力比Ｒを変化させた場合の一例で、
（ａ）はＫｍａｘ，Ｋｍｉｎ，ａ，ｄａ／ｄｎ−Ｎ 曲
線、（ｂ）はＡ，ｆ（無次元摩擦力）−Ｎ 曲線を示す
グラフ。 16 is a diagram of the crack growth behavior of silicon nitride, which is the same as that of FIG .
It is an example, but it is an example when the stress ratio R is changed,
(A) is Kmax, Kmin, a, da / dn-N song
The line, (b) shows A, f (dimensional frictional force) -N curve.
Graph.

【図１７】間接加熱体の水平断面図。 FIG. 17 is a horizontal sectional view of an indirect heating element.

【図１８】円筒ローラ、半円筒ローラ、中継ぎ部側面
図。 FIG. 18: Cylindrical roller, semi-cylindrical roller, side surface of intermediate joint
Fig.

【符号の説明】[Explanation of symbols]

１ 試験片 ２ 予き裂 ３ ガイド溝 ４−４’ 試験片の試験断面の片側の中立軸 ５ 計測用引出し腕の取り付け溝 ６ セラミックス円筒ローラ ７ セラミックス半円筒ローラ ８ 平衡梁支点ローラ ９ 平衡梁 １０ ローラ支持枠 １１ 計測用引出し腕 １２ 円筒ローラ外側ストッパー １３ 円筒ローラ内側ストッパー １４ 外側計測腕 １５ 熱絶縁 １６ 伸び計 １７ 計測端 １８ 負荷位置調節ねじ １９ ローラガイド ２０ 負荷治具端部 ２１ 負荷治具端部冷却水入口 ２２ 負荷治具端部冷却水出口 ２３ 負荷板 ２４ 負荷位置ガイド ２５ セラミックス中継ぎブロック ２６ インコネルガイド ２７ セラミックス負荷板 ２８ 副静負荷ばね ２９ 加熱用水冷高周波コイル ３０，３１ 導電性間接加熱体 ３２ 制御用熱電対 ３３，３４ 耐火材 Ｐ 主繰り返し圧縮負荷の合力 Ｐ／２，Ｐ１，Ｐ２ 主繰り返し圧縮負荷 Ｐ０ 副静負荷 Ｗ 試験片の幅 Ｌ 試験片の長さ Ｂ 試験片の厚さ Ｂｎ ガイド溝付き試験片の正味厚さ ｅ 試験片の試験断面の片側の断面の中立軸からの負
荷の偏心量 １０ 上記中立軸から副静負荷点までの距離 ａ き裂長さ1 Test piece 2 Pre-crack 3 Guide groove 4-4 'Neutral axis on one side of test cross section of test piece 5 Mounting groove for pull-out arm for measurement 6 Ceramic cylindrical roller 7 Ceramic semi-cylindrical roller 8 Balance beam fulcrum roller 9 Balance beam 10 Roller support frame 11 Drawer arm for measurement 12 Cylindrical roller outer stopper 13 Cylindrical roller inner stopper 14 Outer measuring arm 15 Thermal insulation 16 Extensometer 17 Measuring end 18 Load position adjusting screw 19 Roller guide 20 Load jig end 21 Load jig end Part cooling water inlet 22 Load jig end cooling water outlet 23 Load plate 24 Load position guide 25 Ceramics intermediate block 26 Inconel guide 27 Ceramics load plate 28 Sub static load spring 29 Water cooling high frequency coil for heating 30, 31 Conductive indirect heating element 32 Control thermocouple 33, 34 Refractory material P Main repeated compression negative P / 2, P1, P2 Main cyclic compression load P0 Secondary static load W Specimen width L Specimen length B Specimen thickness Bn Net thickness of specimen with guide groove e Test section of specimen Of eccentricity of load from the neutral axis on one side of the shaft 10 Distance from the neutral axis to the auxiliary static load point a Crack length

Claims (11)

【特許請求の範囲】[Claims] 【請求項１】 高硬度、低靭性の脆性材料の破壊力学的
疲労試験において、 長さＬが幅Ｗより大きい直方体形状の試験片を用い、 この試験片の両側面に平行で、長さ方向の中心軸を含む
面を試験断面とし、 前記試験片には試験断面に沿って一端面から長さ約Ｗ／
２以上の予き裂を入れ、 試験断面と両側面との中央からそれぞれ外側へｅだけ偏
心した試験断面に平行な面と前記一端面との２つの交差
線上に、それぞれ中心軸に平行に合力がＰ／２の任意形
状の波形の片振繰り返し圧縮荷重、部分片振繰り返し圧
縮荷重、又はコンプライアンスの動的計測のための小頻
度の部分除荷を含む静圧縮荷重のいずれかを含む圧縮負
荷を負荷し、 前記試験片の予き裂側と反対側となる他端面に、前記圧
縮負荷と釣り合う合力がＰの圧縮負荷を負荷し、 前記試験片の両端面から約Ｗ／２以上離れた試験断面を
試験領域とし、 この試験領域での試験断面に沿うモード１形き裂進展挙
動を荷重制御により計測する ことを特徴とする二重偏心
圧縮による破壊力学的疲労試験方法。 1. Fracture mechanics of brittle materials with high hardness and low toughness
In the fatigue test, a rectangular parallelepiped test piece having a length L larger than the width W is used, and the test piece is parallel to both side surfaces of the test piece and includes a central axis in the length direction.
The surface is a test section, and the test piece has a length of about W /
Insert two or more pre-cracks, and deviate from the center of the test section and both side surfaces outward by e respectively.
Two intersections between the plane parallel to the test section and the one end face.
Any shape with a resultant force of P / 2 parallel to the center axis on the line
Wave-like single-sided repeated compression load, partial partial-sided repeated pressure
Moderate for dynamic measurements of shrinkage loads or compliance
Compression negative with any of the static compression loads including partial unloading
Apply a load to the other end of the test piece, which is
The resultant force balanced with the compressive load applies a compressive load of P, and the test cross section separated from the both end faces of the test piece by about W / 2 or more.
The test area is defined as the mode 1 type crack propagation along the test cross section in this test area.
Double eccentricity characterized by measuring movement by load control
Fracture mechanical fatigue test method by compression. 【請求項２】 高硬度、低靭性の脆性材料の破壊力学的
疲労試験において、 長さＬが幅Ｗより大きい直方体形状の試験片を用い、 この試験片の両側面に平行で、長さ方向の中心軸を含む
面を試験断面とし、 前記試験片には試験断面に沿って一端面から長さ約Ｗ／
２以上の予き裂を入れ、 試験断面の両側の中立軸から一側面側に偏心量ｅだけ偏
心した試験断面に平行な面と前記一端面との２つの交差
線上に、それぞれ中心軸に平行に合力がＰ／２の任意形
状の波形の片振繰り返し圧縮荷重、部分片振繰り返し圧
縮荷重、又はコンプライアンスの動的計測のための小頻
度の部分除荷を含む静圧縮荷重のいずれ かを含む圧縮負
荷を負荷し、 前記試験片の予き裂側と反対側となる他端面に、試験断
面から前記一側面側に等しく偏心させて合力がＰの圧縮
負荷を負荷し、 前記試験片の両端面から約Ｗ／２以上離れた試験断面を
試験領域とし、 この試験領域での試験断面に沿うモード２形き裂進展挙
動を荷重制御により計測する ことを特徴とする二重偏心
圧縮による破壊力学的疲労試験方法。 2. Fracture mechanics of brittle materials with high hardness and low toughness
In the fatigue test, a rectangular parallelepiped test piece having a length L larger than the width W is used, and the test piece is parallel to both side surfaces of the test piece and includes a central axis in the length direction.
The surface is a test section, and the test piece has a length of about W /
Insert two or more pre-cracks and deviate from the neutral axis on both sides of the test section by one side to the eccentric amount e.
Two intersections between the plane parallel to the test section and the one end face.
Any shape with a resultant force of P / 2 parallel to the center axis on the line
Wave-like single-sided repeated compression load, partial partial-sided repeated pressure
Moderate for dynamic measurements of shrinkage loads or compliance
Compression negative with any of the static compression loads including partial unloading
Load a load on the other end of the test piece, which is
Eccentricity from the surface to the one side surface side and the resultant force is P compression
Apply a load to a test cross section that is about W / 2 or more away from both end faces of the test piece.
The test area is defined as the mode 2 type crack growth along the test cross section in this test area.
Double eccentricity characterized by measuring movement by load control
Fracture mechanical fatigue test method by compression. 【請求項３】 高硬度、低靭性の脆性材料の破壊力学的
疲労試験において、 長さＬが幅Ｗより大きい直方体形状の試験片を用い、 この試験片の両側面に平行で、長さ方向の中心軸を含む
面を試験断面とし、 前記試験片には試験断面に沿って一端面から長さ約Ｗ／
２以上の予き裂を入れ、 試験断面と両側面との中央からそれぞれ外側へ一定量だ
け偏心した試験断面に平行な面と前記一端面との２つの
交差線上に、それぞれ中心軸に平行に負荷される任意形
状の波形の片振繰り返し圧縮荷重、部分片振繰り返し圧
縮荷重、又はコンプライアンスの動的計測のための小頻
度の部分除荷を含む静圧縮荷重のいずれかを含む圧縮負
荷と、試験断面の両側の中立軸から一側面側に一定量だ
け偏心した試験断面に平行な面と前記一端面との２つの
交差線上にそれぞれ中心軸に平行に負荷される任意形状
の波形の片振繰り返し圧縮荷重、部分片振繰り返し圧縮
荷重、又はコンプライアンスの動的計測のための小頻度
の部分除荷を含む静圧縮荷重のいずれかを含む圧縮負荷
とをそれぞれ合成した圧縮負荷を前記一端面に負荷し、 前記試験片の予き裂と反対側となる他端面に、前記圧縮
負荷の合計と釣り合う圧縮負荷を負荷し、 前記試験片の両端面から約Ｗ／２以上離れた試験断面を
試験領域とし、 この試験領域での試験断面に沿うモード１、２混合形き
裂進展挙動を荷重制御により計測する ことを特徴とする
二重偏心圧縮による破壊力学的疲労試験方法。 3. Fracture mechanics of brittle materials with high hardness and low toughness
In the fatigue test, a rectangular parallelepiped test piece having a length L larger than the width W is used, and the test piece is parallel to both side surfaces of the test piece and includes a central axis in the length direction.
The surface is a test section, and the test piece has a length of about W /
Insert two or more pre-cracks and set a certain amount outward from the center of the test section and both sides.
Two surfaces, one parallel to the eccentric test section and the other end
Arbitrary shape loaded on the intersection line parallel to the central axis
Wave-like single-sided repeated compression load, partial partial-sided repeated pressure
Moderate for dynamic measurements of shrinkage loads or compliance
Compression negative with any of the static compression loads including partial unloading
Load and a certain amount from the neutral axis on both sides of the test section to one side
Two surfaces, one parallel to the eccentric test section and the other end
Arbitrary shape loaded on the intersection line parallel to the central axis
Repetitive compression load, partial partial repetitive compression
Small frequency for dynamic measurement of load or compliance
Compression load including any of the static compression loads including partial unloading of
And a compressive load that is respectively synthesized with, is applied to the one end surface, and the compression load is applied to the other end surface opposite to the pre-crack of the test piece.
Apply a compressive load that balances the total load, and remove a test cross section about W / 2 or more from both end faces of the test piece.
Use as a test area and mix mode 1, 2 along the test cross section in this test area.
Characterized by measuring crack growth behavior by load control
Fracture mechanical fatigue test method by double eccentric compression. 【請求項４】 前記試験片が、試験断面と垂直の長さ方
向の表裏両面若しくは裏面のみに試験断面を中心にこれ
に沿って長方形を含む断面形状のガイド溝を設けられて
なり、試験断面で切り離した両側をそれぞれ一つの粱と
考えた時の中立軸から外側の予き裂側端面の負荷点まで
の偏心量ｅを負荷の間隔１をＷの許す範囲で、もしくは
さらに予き裂側の端面を外側に張り出しこれを超えて大
きくしたことを特徴とする特許請求の範囲第１項から第
３項までのいずれかに記載の二重偏心圧縮による破壊力
学的疲労試験方法。 4. The length direction in which the test piece is perpendicular to the test section.
This is centered around the test cross section on both front and back sides or the back side only.
Is provided with a guide groove of cross-sectional shape including a rectangle along
And each side separated by the test cross section
From the neutral axis at the time of thinking to the load point of the outer precrack-side end surface
The eccentricity e of the load interval 1 within the range of allowing W, or
Furthermore, the end face on the side of the pre-crack is extended outward and beyond this
Claims 1 to 3 characterized in that
Destructive force due to double eccentric compression described in any one of item 3
Fatigue test method. 【請求項５】 前記試験片が、試験断面の両側の幅を等
しくせずに形成され、予き裂の両側の負荷を試験断面の
両側の断面積に比例させ、負荷と偏心量の積が試験断面
の両側の断面二次モーメントに比例するように負荷およ
び偏心量を定めることにより力学的に等価に試験片形状
の範囲を拡大することを特徴とする特許請求の範囲第１
項から第４項までのいずれかに記載の二重偏心圧縮によ
る破壊力学的疲労試験方法。 5. The test piece has equal widths on both sides of the test section.
Formed without damage, the load on both sides of the precrack is
The product of load and eccentricity is proportional to the cross-sectional area on both sides
The load and load are proportional to the moments of inertia on both sides of
And the amount of eccentricity determine the shape of the test piece in a mechanically equivalent manner
The scope of claim 1 characterized by expanding the scope of
According to the double eccentric compression described in any one of items 4 to 4.
Fracture mechanical fatigue test method. 【請求項６】 前記試験片の予き裂側の端面に両側に延
びる計測腕を設け、 この計測腕の両端部に設けた柔いバネにより小さい副静
負荷を前記試験片に加える ことを特徴とする特許請求の
範囲第１項から第５項までのいずれかに記載の二重偏心
圧縮による破壊力学的疲労試験方法。 6. A pre-crack-side end face of the test piece is extended on both sides.
A measuring arm is installed, and the soft springs provided on both ends of this measuring arm reduce the static
Claims characterized in that a load is applied to the test piece .
Double eccentricity according to any one of ranges 1 to 5
Fracture mechanical fatigue test method by compression. 【請求項７】 前記試験領域にて試験中、予き裂側の端
面のき裂の両側の角変位と荷重とのヒステリシス曲線を
計測し、その線形範囲のコンプライアンスの増加量から
これに正比例するき裂進展量を求め、さらに、その細部
形状からき裂開閉口点、ブリッジングフリクションを含
むき裂進展挙動に影響する諸量を定量的に求める、き裂
先端の直接観察を必要とせず、負荷荷重と試験片の予き
裂側端面の角変位のみの計測により、き裂進展挙動を定
量的に求めることを特徴とする特許請求の範囲第１項か
ら第６項までのいずれかに記載の二重偏心圧縮による破
壊力学的疲労試験方法。 7. The end on the pre-crack side during the test in the test area.
The hysteresis curve of the angular displacement and load on both sides of the surface crack is
Measure and increase the amount of compliance in its linear range
Obtain the crack growth amount that is directly proportional to this, and
Includes crack opening and closing points and bridging friction
A crack that quantitatively determines various quantities that affect the crack growth behavior.
Predict load loads and test pieces without direct observation of the tip
Determining crack growth behavior by measuring only the angular displacement of the crack end face
Claim 1 characterized in that it is obtained quantitatively
To the breakage due to the double eccentric compression described in any one of 6 to 6.
Breaking fatigue test method. 【請求項８】 試験片への負荷の圧縮荷重の方向および
着力点の位置を正確に保ちかつ試験片の変形による微小
な相対変位を逃がすため試験断面に平 行な軸を持つセラ
ミックスの円筒ローラの転がり接触を用い、負荷を試験
片厚さの中央若しくは所要の位置に保つために試験断面
に垂直な軸を持つ半円筒状ローラによる線接触を、予き
裂両側の負荷を均分もしくは所期の比率に配分するため
に要すれば転がり接触による支点を持つ平衡粱を用いた
特許請求の範囲第１項から第７項までのいずれかに記載
の二重偏心圧縮による破壊力学的疲労試験方法。 8. The direction of compressive load applied to the test piece and
Precisely maintain the position of the force application point and
Sera with a flat line axis in the test section for releasing a relative displacement
Load tested using rolling contact of mix cylindrical rollers
Test cross section to keep the center of the thickness or the required position
Predict line contact by a semi-cylindrical roller with an axis perpendicular to
To distribute the load on both sides of the cleft evenly or at a desired rate
If necessary, we used equilibrium gruel with a fulcrum by rolling contact.
Any one of claims 1 to 7
Method of Fracture Mechanical Fatigue by Double Eccentric Compression of Steel. 【請求項９】 長さが幅の約３倍以上の試験片を用い、
高周波間接若しくは直接加熱炉あるいは赤外線輻射加熱
炉により試験片の試験領域を含む中央部分のみを加熱
し、試験片両端部を炉外に出して、１２７３Ｋ以上の極
高温領域を含む高温領域での試験においても、荷重負荷
治具および計測量引き出し用治具を最高８００Ｋ以下よ
り常温に到る比較的低温部に置き、常温での荷重ならび
に変位の計測をすることを特徴とする特許請求の範囲第
１項から第８項までのいずれかに記載の二重偏心圧縮に
よる破壊力学的疲労試験方法。 9. A test piece having a length about 3 times or more the width is used,
High frequency indirect or direct heating furnace or infrared radiation heating
Only the central part of the test piece including the test area is heated by the furnace
Then, put both ends of the test piece out of the furnace and use a pole of 1273K or more.
Even under test in high temperature range including high temperature range
Jigs and jigs for pulling out the measured amount must be under 800K
Place it in a relatively low temperature area that reaches room temperature and load it at room temperature.
Claims characterized in that the displacement is measured at
For double eccentric compression according to any one of items 1 to 8.
Fracture mechanical fatigue test method. 【請求項１０】 試験領域の試験温度をできるだけ一定
に保つために、高周間接加熱にて間接発熱体を試験片上
下に２もしくは３分割し、それぞれの厚さ、間隔、位置
を調節し、温度の均一分布をさせること、さらに高周
波、赤外線加熱とも炉を移動し、温度の極大位置を亀裂
先端位置のオンライン計測により、その位置に自動追尾
さすことにより、試験領域を広げ、温度精度を高めるこ
とを特徴とする特許請求の範囲第９項記載の二重偏心圧
縮による破壊力学的疲労試験方法。 10. The test temperature in the test area is as constant as possible.
In order to keep the indirect heating element on the test piece by high-frequency indirect heating.
Divide into 2 or 3 below, each thickness, spacing, position
Adjust the temperature distribution to obtain a uniform temperature distribution,
Wave and infrared heating both move the furnace and crack the maximum temperature position
Online measurement of the tip position automatically tracks the position
By extending the test area, the temperature accuracy can be improved.
Double eccentric pressure according to claim 9, characterized in that
Fracture mechanical fatigue test method by shrinkage. 【請求項１１】 パーソナルコンピューターを用いて試
験中、荷重周期に同期して荷重と試験片端面の角変位を
連続して計測し、採取した大量の荷重−変形ヒステリシ
スのデータを同一位相のデータの加算平均により第一段
階の最小限のデータ量の圧縮とノイズの除去をして、精
度を下げ即応性を保ったオンライン処理により応力拡大
係数、き裂長さ、進展速度を求め、ヒステリシスととも
に画面表示し、前記加熱位置の自動追尾を含め、負荷荷
重レベル、その増減速度などの試験条件を試験中にその
経過に対応して設定、微調節をし、要すれば第二段階の
圧縮をして、データをハードディスクに落とし、オフラ
インで最適高精度化処理を行って高精度の試験結果を得
るとともに、荷重−変形ヒステリシスの詳細形状からき
裂開閉口挙動、ブリッジング現象などのき裂進展挙動、
機構に関す る細部情報を得ることを特徴とする特許請求
の範囲第１項から第１０項までのいずれかに記載の二重
偏心圧縮による破壊力学的疲労試験方法。 11. A trial using a personal computer.
During the test, the load and the angular displacement of the end face of the test piece are synchronized with the load cycle.
Large amount of load continuously measured and collected-deformation hysteresis
1st step by adding and averaging the same phase data
Compress the minimum amount of data on the floor and remove noise to
Increased stress through online processing that reduces the rate and maintains responsiveness
Calculate the coefficient, crack length, and propagation speed, and calculate the hysteresis
Display on the screen and load load including automatic tracking of the heating position.
Test conditions such as heavy level and its speed of increase / decrease during the test.
Make settings and fine adjustments according to the progress, and if necessary, use the second stage
Compress it, drop the data on the hard disk, and
In-line optimal precision processing is performed to obtain high-precision test results.
And the detailed shape of load-deformation hysteresis.
Crack opening / closing behavior, crack growth behavior such as bridging phenomenon,
Claims, characterized in that to obtain detailed information about the mechanism
The range according to any one of items 1 to 10
Fracture mechanical fatigue test method by eccentric compression.