JP3116123B2 - Measurement and evaluation method of stress intensity factor of three-dimensional surface crack by AC potential difference method - Google Patents
Measurement and evaluation method of stress intensity factor of three-dimensional surface crack by AC potential difference methodInfo
- Publication number
- JP3116123B2 JP3116123B2 JP03272128A JP27212891A JP3116123B2 JP 3116123 B2 JP3116123 B2 JP 3116123B2 JP 03272128 A JP03272128 A JP 03272128A JP 27212891 A JP27212891 A JP 27212891A JP 3116123 B2 JP3116123 B2 JP 3116123B2
- Authority
- JP
- Japan
- Prior art keywords
- crack
- potential difference
- stress intensity
- intensity factor
- load
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Description
【０００１】[0001]
【産業上の利用分野】原子力、火力発電設備、あるいは
化学プラント、石油プラント等における圧力容器、配管
等の機器・構造物などの健全性を評価する応力拡大係数
の計測評価方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring and evaluating a stress intensity factor for evaluating the soundness of devices and structures such as pressure vessels and pipes in nuclear power plants, thermal power plants, chemical plants, petroleum plants, and the like.
【０００２】[0002]
【従来の技術】各種機器構造物の線形破壊力学に基づく
健全性評価においては、応力拡大係数の評価が不可欠で
ある。応力拡大係数は、一般には理論解析に基づいて算
出される。しかしながら実際の構造物においては、形状
の複雑さや荷重作用形態の複雑さに起因して、解析が問
題となる場合が多い。応力拡大係数を評価する手法につ
いての研究では、従来次のような方法が提案されてい
る。2. Description of the Related Art In soundness evaluation of various equipment structures based on linear fracture mechanics, evaluation of stress intensity factor is indispensable. The stress intensity factor is generally calculated based on a theoretical analysis. However, in an actual structure, analysis often becomes a problem due to the complexity of the shape and the complexity of the load acting form. In the research on the method of evaluating the stress intensity factor, the following method has been conventionally proposed.
【０００３】第１の方法としては、コンピューター一式
（コンピューターと入出力装置）を使用した有限要素法
などによる弾性問題理論解析がある。例えば有限要素法
による応力拡大係数の理論解析は、形状の複雑な三次元
の亀裂部材内の亀裂を対象としたとき、亀裂発生箇所近
傍の連続体を取り出し、取り出した箇所だけを要素分割
して解析するか、あるいは対象亀裂部材全体を要素分割
して解析するという方法である。これはまず要素分割の
データ、境界条件のデータを作成してコンピューターに
入れ、弾性有限要素解析プログラムを用いて計算を実行
し、出力する方法である。As a first method, there is a theory analysis of an elastic problem by a finite element method using a set of computers (computer and input / output device). For example, the theoretical analysis of the stress intensity factor by the finite element method, when targeting a crack in a three-dimensional cracked member with a complicated shape, takes out a continuum near the crack occurrence location and divides only the taken-out location into elements It is a method of performing analysis, or performing analysis by dividing the entire target crack member into elements. This is a method in which data of element division and data of boundary conditions are created and put into a computer, and calculations are executed using an elastic finite element analysis program, and then output.
【０００４】第２の方法としては、『ひずみゲージ』に
よるひずみの計測に基づく方法がある。これは、図１の
ように亀裂部材側面（面Ｂ）上の亀裂先端近傍に抵抗線
ひずみゲージをはり付け、亀裂部材に力が作用したとき
のひずみを計測する方法である。図２は、亀裂部材側面
（面Ｂ）にはりつけた状態のひずみゲージの一例であ
る。図中１，２，３，１′，２′，３′がひずみゲージ
である。これらのひずみゲージには、それぞれリード線
をつけて、抵抗変化（ひずみ変化に伴う）の計測に供す
る。計測されたひずみと、ひずみと応力拡大係数の間の
理論関係式を照合して、応力拡大係数を評価する方法で
ある。[0004] As a second method, there is a method based on measurement of strain using a "strain gauge". This is a method in which a resistance wire strain gauge is attached near the tip of a crack on the side surface (surface B) of the crack member as shown in FIG. 1 to measure the strain when a force acts on the crack member. FIG. 2 is an example of a strain gauge in a state of being attached to a side surface (surface B) of a crack member. In the figure, 1, 2, 3, 1 ', 2' and 3 'are strain gauges. Each of these strain gauges is provided with a lead wire and is used for measuring a change in resistance (according to a change in strain). This is a method of evaluating the stress intensity factor by collating the measured strain with a theoretical relational expression between the strain and the stress intensity factor.
【０００５】第３の方法としては、コースティック法と
いうのがある。これは、図３に示すように、亀裂部材Ｘ
またはＹに光線を照射し、その入射光や反射光がスクリ
ーンに結ぶ実像または虚像がどのように歪むかによっ
て、応力拡大係数を評価する方法である。具体的には、
図３（Ａ）が透明な亀裂部材Ｘを対象としたコースティ
ック法であり、図３（Ｂ）が不透明な亀裂部材（入射光
側は鏡面仕上げ）Ｙを対象としたコースティック法であ
る。As a third method, there is a caustic method. This is because, as shown in FIG.
Alternatively, a method of irradiating light to Y and evaluating the stress intensity factor depending on how the real image or virtual image formed on the screen by the incident light or reflected light is distorted. In particular,
FIG. 3A shows a caustic method for a transparent crack member X, and FIG. 3B shows a caustic method for an opaque crack member Y (mirror finish on the incident light side).
【０００６】第４の方法は、光弾性法といわれるもので
ある。これは、図４に示すように亀裂部材Ｔの前後に偏
光子Ｐ1 ，Ｐ2 と１／４波長板Ｑ1 ，Ｑ2 を配設し、前
方光源より発射せられた光線を配設した偏光子Ｐ1 ，Ｐ
2 と１／４波長板Ｑ1 ，Ｑ2と亀裂部材Ｔを通して、ス
クリーンに写し、その際の光弾性縞を計測して、応力拡
大係数を評価する方法である。A fourth method is called a photoelastic method. As shown in FIG. 4, polarizers P 1 and P 2 and quarter-wave plates Q 1 and Q 2 are arranged before and after a crack member T, and light rays emitted from a front light source are arranged. Polarizers P 1 and P
In this method, the stress intensity factor is evaluated by measuring the photoelastic fringes on the screen through the two- and quarter-wave plates Q 1 and Q 2 and the crack member T and measuring the photoelastic fringes at that time.
【０００７】第５の方法として交流電位差法による二次
元亀裂の応力拡大係数計測評価方法がある。図５は、こ
の交流電位差法による応力拡大係数計測評価方法の基本
原理を示す説明図であり、図中１は交流参照信号発生装
置、２は電力増幅器、３は亀裂部材、４は電流入出力端
子、５は電位差測定端子、６はロックインアンプ、７は
データ解析装置である。As a fifth method, there is a method for measuring and evaluating a stress intensity factor of a two-dimensional crack by an AC potential difference method. FIG. 5 is an explanatory view showing the basic principle of the stress intensity factor measuring and evaluating method by the AC potential difference method, wherein 1 is an AC reference signal generator, 2 is a power amplifier, 3 is a crack member, and 4 is current input / output. Terminals 5 and 5 are potential difference measuring terminals, 6 is a lock-in amplifier, and 7 is a data analyzer.
【０００８】これは本発明者らの発明によるもので、交
流参照信号発生装置により発生した一定電圧、一定周波
数の信号を電力増幅器により増幅し、図１に示すような
二次元亀裂部材に面Ａ上で図５に示すように一定電流、
一定周波数の交流電流を流し、部材に作用する負荷の値
を変化させ、面Ａ上の亀裂をまたいだ一組の二点間での
電位差変化をロックインアンプにより計測し、計測デー
タをデータ解析装置により解析し、応力拡大係数と負荷
の関係を特定する。なお、データ解析装置は、電位差変
化と応力拡大係数の変化の間の比例関係を較正関係とし
て記憶しており、これと入力された計測データを照合す
る。この方法では、面Ａ上で計測を実施し、亀裂先端近
傍での計測は不要である。According to the invention of the present inventors, a signal of a constant voltage and a constant frequency generated by an AC reference signal generating device is amplified by a power amplifier, and the two-dimensional crack member as shown in FIG. Constant current as shown in FIG. 5 above,
A constant frequency alternating current is applied, the value of the load acting on the member is changed, and the potential difference between a pair of two points across the crack on the surface A is measured by a lock-in amplifier, and the measured data is analyzed. Analyze with a device to identify the relationship between stress intensity factor and load. The data analyzer stores a proportional relationship between a change in the potential difference and a change in the stress intensity factor as a calibration relationship, and compares this with the input measurement data. In this method, measurement is performed on the surface A, and measurement near the crack tip is unnecessary.
【０００９】[0009]
【発明が解決しようとする課題】従来技術の第１の方法
にあっては、有限要素法で亀裂発生箇所近傍の連続体を
取り出し、取り出した箇所だけを要素分割して解析する
場合には、どこまでの大きさの箇所を取り出せばよい
か、また取り出した箇所の境界面にいかなる大きさの応
力（あるいは変位）をいかなる分布で与えればよいかの
検討、すなわち境界条件の設定が問題となる。In the first method of the prior art, when a continuum near a crack occurrence location is taken out by the finite element method and only the taken out location is divided into elements and analyzed, The problem is how much size should be extracted and how much stress (or displacement) should be applied to the boundary surface of the extracted portion in what distribution, that is, setting of boundary conditions becomes a problem.
【００１０】仮に、適当な大きさの連続体を取り出し、
境界条件を与えたとしても、その解析により得られた応
力拡大係数がどの程度正しいかの検証が問題となる。一
方、亀裂部材全体を要素分割して解析する場合には、三
次元問題であることも原因して、非常に多くの要素が必
要となり、計算時間が多くかかることになる。[0010] If a continuum of an appropriate size is taken out,
Even if boundary conditions are given, it is a problem to verify how correct the stress intensity factor obtained by the analysis is. On the other hand, when analyzing the entire crack member by dividing it into elements, an extremely large number of elements are required due to the three-dimensional problem, and a long calculation time is required.
【００１１】第２の方法では、図１の面Ｂ上で計測を実
施する。又、亀裂先端近傍で計測を実施する。従って、
二次元亀裂に比べ実際上、はるかに多く経験される三次
元表面亀裂には使えない。In the second method, measurement is performed on plane B in FIG. The measurement is performed near the crack tip. Therefore,
It cannot be used for three-dimensional surface cracks, which are actually far more common than two-dimensional cracks.
【００１２】第３の方法では、第２の方法と同じであ
り、さらに透明な亀裂部材によること、あるいは不透明
な亀裂部材の場合は、鏡面仕上げを必要とすることよ
り、現場での適用には向かない。The third method is the same as the second method, and further requires a transparent crack member, or, in the case of an opaque crack member, requires a mirror finish, so that it is not suitable for on-site application. Not suitable.
【００１３】第４の方法も第２の方法と同じであって、
さらに透明な材料によるため、現場の応力拡大係数評価
には使えない。The fourth method is the same as the second method,
Furthermore, since it is made of a transparent material, it cannot be used for on-site stress intensity factor evaluation.
【００１４】第５の方法は二次元亀裂を対象とした方法
であり、三次元表面亀裂には使えない。The fifth method is for a two-dimensional crack, and cannot be used for a three-dimensional surface crack.
【００１５】三次元表面亀裂では、負荷の変化に伴う亀
裂部材表面上で計測される電位差変化の分布が亀裂の形
状・寸法にも依存するため、本発明の改良による如く、
同依存性をも考慮することが必要となる。従来、応力拡
大係数評価に交流電位差法を利用するという発想は、本
発明者らによる二次元亀裂を対象とした手法の考案以前
にはなく、三次元表面亀裂を対象としては、本発明に類
似の技術はない。In the case of a three-dimensional surface crack, the distribution of the change in potential difference measured on the surface of the crack member due to the change in load also depends on the shape and size of the crack.
It is necessary to consider the dependency. Conventionally, the idea of using the AC potential difference method for stress intensity factor evaluation was not before the inventors of the present invention devised a method for a two-dimensional crack, and similar to the present invention for a three-dimensional surface crack. There is no technology.
【００１６】本発明は、交流電位差法による二次元亀裂
の応力拡大係数評価方法に改良を加え、即ち負荷の変化
に伴う電位差変化の三次元亀裂形状・寸法依存性を考慮
し、三次元亀裂の応力拡大係数を評価できるようにした
ものである。本発明の計測は図６の面Ｃ上で実施する。The present invention improves the method for evaluating the stress intensity factor of a two-dimensional crack by the AC potential difference method, that is, considering the three-dimensional crack shape and size dependence of the potential difference change due to the load change, The stress intensity factor can be evaluated. The measurement of the present invention is performed on the plane C in FIG.
【００１７】各種亀裂部材の線形破壊力学に基づく健全
性評価においては、応力拡大係数の評価が不可欠であ
る。応力拡大係数は、負荷の大きさ・かかり方、亀裂の
形状・寸法と対象亀裂部材の形状・寸法で決まるパラメ
ータであり、線形破壊力学によれば、応力拡大係数の値
が対象亀裂部材を構成する材料の固有の破壊じん性値を
越えたときに、対象亀裂部材は破壊する。又、例えば、
金属疲労等の疲労破壊においては、負荷の変動に伴う応
力拡大係数の変動により亀裂の成長速度が決まる。In soundness evaluation of various crack members based on linear fracture mechanics, evaluation of stress intensity factor is indispensable. The stress intensity factor is a parameter determined by the size and manner of load, the shape and size of the crack, and the shape and size of the target crack member.According to linear fracture mechanics, the value of the stress intensity factor constitutes the target crack member. When the inherent fracture toughness value of the material to be cracked is exceeded, the target crack member fails. Also, for example,
In fatigue fracture such as metal fatigue, the growth rate of a crack is determined by the change in stress intensity factor accompanying the change in load.
【００１８】実在亀裂は三次元形状を呈している場合が
多い。対象亀裂部材で、運転時と同一形態の負荷を作用
させた状態で、当該亀裂発生箇所においてその応力拡大
係数を直接、計測評価することがねらいである。Real cracks often have a three-dimensional shape. It is an object of the present invention to directly measure and evaluate the stress intensity factor at the crack occurrence point in a state where a load of the same form as during operation is applied to the target crack member.
【００１９】形状の単純な構造物内の亀裂の応力拡大係
数は、弾性問題理論解析により解析できるが、実際の亀
裂部材においては、形状の複雑さや荷重作用形態の複雑
さによる境界条件の設定の困難さに起因して、解析が問
題となる場合が多い。そこで、上述のように、三次元形
状の亀裂発生箇所で応力拡大係数を直接計測評価するね
らいが生まれた。The stress intensity factor of a crack in a structure having a simple shape can be analyzed by an elasticity problem theoretical analysis. However, in an actual cracked member, the setting of the boundary conditions based on the complexity of the shape and the complexity of the load acting form is performed. Analysis is often a problem due to difficulties. Therefore, as described above, the aim was to directly measure and evaluate the stress intensity factor at the crack occurrence location in the three-dimensional shape.
【００２０】[0020]
【課題を解決するための手段】本発明は、三次元亀裂問
題を二次元の電流問題に置き換えて、解析するものであ
り、運転時と同一形態の負荷を作用させ、測定結果を得
るが、運転負荷形態により、実際に生じる応力拡大係数
を直接反映したデータを計測し、用いることになり、単
なる理論解析と異なり、実際の運転状態に対する応力拡
大係数を直接評価できることになり、この点で利点を有
するものである。According to the present invention, a three-dimensional cracking problem is replaced with a two-dimensional current problem and analysis is performed. A load having the same form as during operation is applied to obtain a measurement result. Depending on the operating load mode, data that directly reflects the stress intensity factor that actually occurs is measured and used, and unlike simple theoretical analysis, the stress intensity factor for the actual operating condition can be directly evaluated. It has.
【００２１】本発明は、交流定電流源と電流入出力端子
と電位差測定端子と電位差計測装置とデータ解析装置と
を備え、表面に亀裂が検出された検査対象の構造物（亀
裂部材）から交流電位差法を用いてデータを収集する
際、第１段階として亀裂部材に負荷１を作用させ、亀裂
をまたいで電流入出力端子の位置を定め、かつ位置を定
められた電流入出力端子間で、亀裂をまたいだ複数の二
点間で電位差測定端子を介し、電位差計測装置により電
位差を計測し、第２段階として亀裂部材に作用させる負
荷の値を負荷１から負荷２に変化させ、負荷２の状態で
電位差を計測し、第３の段階として、第１の段階、第２
の段階で得られた複数の二点間の電位差データを、デー
タ解析装置により解析し、対象亀裂の応力拡大係数と負
荷の関係を特定することを特徴とする交流電位差法によ
る三次元表面亀裂の応力拡大係数の計測評価方法であ
る。The present invention comprises an AC constant current source, a current input / output terminal, a potential difference measuring terminal, a potential difference measuring device, and a data analyzing device, and is provided with an alternating current from a structure (crack member) to be inspected whose surface has a crack detected. When collecting data using the potentiometric method, as a first step, a load 1 is applied to the crack member, the position of the current input / output terminal is determined across the crack, and between the defined current input / output terminals, A potential difference is measured by a potential difference measuring device between a plurality of two points across the crack through a potential difference measuring terminal, and the value of the load acting on the crack member is changed from load 1 to load 2 as a second stage, The potential difference is measured in the state, and the third step is a first step, a second step,
The potential difference data between a plurality of two points obtained in the step is analyzed by a data analysis device, and the relationship between the stress intensity factor of the target crack and the load is specified. This is a method for measuring and evaluating the stress intensity factor.
【００２２】以下、本発明を図面に基づいて詳細に説明
する。図７において、１は交流参照信号発生装置、２は
電力増幅器、３は亀裂部材、４は電流入出力端子、５は
電位差測定端子、６はロックインアンプ、７はデータ解
析装置である。図８に、本発明の方法による応力拡大係
数の計測評価の手順概略を示す。なお、交流定電流源
は、図示実施例において交流参照信号発生装置１と電力
増幅器２の組み合わせた装置に対応し、電位差計測装置
は、ロックインアンプに対応する。しかし、交流定電流
源、電位差計測装置は上記のものに限定されないこと勿
論である。Hereinafter, the present invention will be described in detail with reference to the drawings. 7, 1 is an AC reference signal generator, 2 is a power amplifier, 3 is a crack member, 4 is a current input / output terminal, 5 is a potential difference measuring terminal, 6 is a lock-in amplifier, and 7 is a data analyzer. FIG. 8 shows an outline of the procedure for measuring and evaluating the stress intensity factor according to the method of the present invention. The AC constant current source corresponds to an apparatus in which the AC reference signal generator 1 and the power amplifier 2 are combined in the illustrated embodiment, and the potential difference measuring apparatus corresponds to a lock-in amplifier. However, it goes without saying that the AC constant current source and the potential difference measuring device are not limited to those described above.
【００２３】本発明では、はじめに三次元表面亀裂を有
する部材に交流電流を流した時の、応力拡大係数の変化
に伴う亀裂をまたいだ二点間での理論電位差の変化を求
める。これについては、先に本発明者らが提案した理論
解析手法を用いる。なお本発明においては、対象とする
三次元表面亀裂の形状・大きさについては、何らかの方
法（たとえば直流電位差法）であらかじめ知っているこ
とを前提とする。次に実際に三次元表面亀裂を有する部
材に負荷を作用させ、その値を変化させたときに生じる
電位差の変化量の計測結果と、理論解析の両者を照合
し、作用させた負荷の変化と三次元表面亀裂の応力拡大
係数の変化の関係を逆問題解析により評価する。この関
係を用いることにより、所望の大きさの負荷に対する応
力拡大係数を求めることができる。In the present invention, first, when an alternating current is applied to a member having a three-dimensional surface crack, the change in the theoretical potential difference between two points across the crack due to the change in the stress intensity factor is determined. For this, the theoretical analysis method previously proposed by the present inventors is used. In the present invention, it is assumed that the shape and size of the target three-dimensional surface crack are known in advance by some method (for example, a DC potential difference method). Next, a load is actually applied to a member having a three-dimensional surface crack, and the measurement result of the amount of change in the potential difference generated when the value is changed is compared with the theoretical analysis. The relation of the change of stress intensity factor of three-dimensional surface crack is evaluated by inverse problem analysis. By using this relationship, a stress intensity factor for a load of a desired magnitude can be obtained.
【００２４】具体的に説明すると、まず応力拡大係数の
変化に伴う、亀裂をまたいだ二点間での理論電位差の変
化を、次のように解析している。はじめに図９に示すよ
うに亀裂面を部材表面と同じ平面上に展開する。これに
より得られる平面領域上で電場の支配方程式は二次元ラ
プラス方程式で与えられる。次に亀裂部材に作用する負
荷を変化させたとき、電磁物性値の変化が亀裂前縁上に
集中的に起こると考え、電磁物性値の変化を担うインピ
ーダンス（ラインインピーダンスと呼ぶ）により、上に
展開した亀裂前縁を接続する。Specifically, first, the change in the theoretical potential difference between two points across a crack due to the change in the stress intensity factor is analyzed as follows. First, as shown in FIG. 9, the crack surface is developed on the same plane as the member surface. The governing equation of the electric field on the obtained plane region is given by a two-dimensional Laplace equation. Next, when the load acting on the crack member is changed, it is considered that the change in the electromagnetic property value occurs intensively on the front edge of the crack, and the impedance responsible for the change in the electromagnetic property value (called line impedance) causes Connect the developed crack leading edge.
【００２５】ラインインピーダンスの特性は、二次元亀
裂の実験計測を実施して、応力拡大係数によって決定す
る。従って、亀裂前縁上の各位置で応力拡大係数の異な
る値を仮定する時には、対象となる各位置でラインイン
ピーダンスの特性は応力拡大係数の違いに応じて異なる
ことになる。最初、無負荷時（応力拡大係数＝０）の部
材表面での電位分布を計算する。計測上の亀裂をまたい
だ複数の二点間の理論電位差（Ｅth）i を求める。ここ
にi は計測点のi 番目の組を表す。The characteristic of the line impedance is determined by performing an experimental measurement of a two-dimensional crack and determining the stress intensity factor. Accordingly, when assuming different values of the stress intensity factor at each position on the crack leading edge, the characteristics of the line impedance at each target position differ according to the difference of the stress intensity factor. First, the potential distribution on the member surface when no load is applied (stress intensity factor = 0) is calculated. The theoretical potential difference (Eth) i between a plurality of two points across a crack in measurement is obtained. Where i represents the ith set of measurement points.
【００２６】 次に亀裂前縁上の各位置で応力拡大係数
の値を設定し、その状態での表面での電位分布を計算
し、無負荷時と同様に対象とする計測点間の理論電位差
（Ｅ′ｔｈ）ｉを求める。（Ｅｔｈ）ｉと（Ｅ′ｔｈ）
ｉから次の数１により（ΔＥｔｈ）ｉが求められる。Next, the value of the stress intensity factor is set at each position on the front edge of the crack, the potential distribution on the surface in that state is calculated, and the theoretical potential difference between the target measurement points is calculated in the same manner as when no load is applied. (E'th ) i is obtained. (Eth) i and (E'th)
(ΔEth) i is obtained from i by the following equation ( 1 ) .
【００２７】[0027]
【数１】 (Equation 1)
【００２８】この（ΔＥth）i は、応力拡大係数が上に
設定した値だけ変化することにより生じる、各計測点間
での電位差の変化量を与えることになる。ここで次の目
的関数Ｆを定義すると、次のような数２になる。Ｆはこ
れに限らないこと勿論である。This (ΔEth) i gives the amount of change in the potential difference between the measurement points caused by the change in the stress intensity factor by the value set above. Here, when the following objective function F is defined, the following equation 2 is obtained. Of course, F is not limited to this.
【００２９】[0029]
【数２】 (Equation 2)
【００３０】ここに（ΔＥex）i は計測される、負荷の
変化に伴う各計測点間での電位差の変化量である。また
n は計測点の組の個数である。最適化法によりＦを最小
とするような未知量である応力拡大係数の亀裂前縁上の
各位置に対する値をみつける。即ち逆問題を解く。Here, (ΔEex) i is the amount of change in the potential difference measured between the measurement points due to the change in the load. Also
n is the number of sets of measurement points. The value of the stress intensity factor, which is an unknown quantity that minimizes F, is found for each position on the crack leading edge by the optimization method. That is, the inverse problem is solved.
【００３１】[0031]
【本発明の作用】交流参照信号発生装置により発生した
一定電圧、一定周波数の信号を電力増幅器により増幅
し、図６に示すような三次元表面亀裂を有する部材に面
Ｃ上で一定電流、一定周波数の交流電流を図７で示すよ
うに流し、面Ｃ上の亀裂をまたいだ複数組の二点間に電
位差測定端子位置を定め、部材に作用する負荷の値を変
化させ、負荷の変化に伴う、電位差変化をロックインア
ンプにより計測し、計測データをデータ解析装置により
解析し、三次元表面亀裂の応力拡大係数と負荷の関係を
特定する。なお、データ解析装置は、二次元亀裂の実験
計測結果を記憶しており、これに基づきラインインピー
ダンスの特性を決定し、図９に従って図８の交流電流問
題理論解析を実施し、さらに入力された計測データと照
合して逆問題を解析し、三次元表面亀裂の応力拡大係数
と負荷の関係を特定する。The signal of a constant voltage and a constant frequency generated by the AC reference signal generating device is amplified by a power amplifier, and is applied to a member having a three-dimensional surface crack as shown in FIG. An alternating current having a frequency is applied as shown in FIG. 7, a potential difference measuring terminal position is determined between a plurality of sets of two points across the crack on the surface C, and the value of the load acting on the member is changed. The accompanying change in the potential difference is measured by a lock-in amplifier, and the measured data is analyzed by a data analyzer to specify the relationship between the stress intensity factor of the three-dimensional surface crack and the load. The data analysis device stores the experimental measurement results of the two-dimensional crack, determines the characteristics of the line impedance based on this, performs the AC current problem theoretical analysis of FIG. 8 according to FIG. 9, and further inputs the data. The inverse problem is analyzed by comparing it with the measured data, and the relationship between the stress intensity factor and the load of the three-dimensional surface crack is specified.
【００３２】[0032]
【実施例】図１０に亀裂部材を示す。材料は超強力鋼
（ＪＩＳ Ｇ４１０３ ＳＮＣＭ４３９）である。亀裂
は疲労で導入したものであり、部材表面に垂直にある。
その形状・寸法は図１０(ロ）に示す如くである。電流入
出力端子間隔は４０mm、電位差測定端子間隔は３mmであ
る。なお、電位差測定は、亀裂線に沿って１．５mm間隔
の１３箇所で亀裂をまたいで行っている。使用する交流
電流の周波数は、１０ｋＨｚ、電流量は１Ａである。FIG. 10 shows a crack member. The material is ultra-high strength steel (JIS G4103 SNCM439). Cracks are introduced by fatigue and are perpendicular to the member surface.
The shape and dimensions are as shown in FIG. The distance between the current input / output terminals is 40 mm, and the distance between the potential difference measuring terminals is 3 mm. In addition, the potential difference measurement is performed across 13 cracks at 13 locations at 1.5 mm intervals along the crack line. The frequency of the alternating current used is 10 kHz, and the amount of current is 1A.
【００３３】図１１には、図１０に示した亀裂部材に、
スパン１２０mmの三点曲げにより１８．６２ｋＮをかけ
たときに測定された電位差から０．９８ｋＮをかけたと
きに測定された電位差を引いた値ΔＥexを○印で示す。
なお、横軸χは亀裂部材中央線からの計測点の距離であ
る。なお、１８．６２ｋＮ−０．９８ｋＮ＝１７．６４
ｋＮ（≡ΔＱ）なる負荷変化に対して逆問題解析の実施
により評価された応力拡大係数の変化量ΔＫI は１５．
２ＭＰａ√ｍである。なお、本実施例では、亀裂前縁上
の各位置で応力拡大係数の値を一定と仮定している。図
１１には、求められたΔＫI ＝１５．２ＭＰａ√ｍに対
して理論計算より得られる電位差の変化量ΔＥthを実線
で示している。実線と○印はよく一致していることがわ
かる。FIG. 11 shows that the crack member shown in FIG.
The value ΔEex obtained by subtracting the potential difference measured when applying 0.98 kN from the potential difference measured when applying 18.62 kN by three-point bending with a span of 120 mm is indicated by a circle.
The horizontal axis χ is the distance of the measurement point from the center line of the crack member. In addition, 18.62 kN-0.98 kN = 17.64
The change amount ΔK I of the stress intensity factor evaluated by performing the inverse problem analysis for the load change of kN (≡ΔQ) is 15.
2 MPa√m. In this embodiment, it is assumed that the value of the stress intensity factor is constant at each position on the crack leading edge. In FIG. 11, the solid line indicates the amount of change ΔEth in the potential difference obtained by theoretical calculation with respect to the obtained ΔK I = 15.2 MPa√m. It can be seen that the solid line and the ○ mark match well.
【００３４】負荷とそれに伴う応力拡大係数の関係はＫ
I ＝αkQ・Ｑ と書ける。従って、係数αkQはΔＫI ／
ΔＱにより求めることができる。本実施例の場合にはα
kQ＝０．８６２×１０3 ｍ-3/2と評価される。この値を
上式に用いれば、対象とした形状・寸法の三次元表面亀
裂に、対象とした形態で作用する所望の大きさの負荷に
対し応力拡大係数を求めることができる。The relationship between the load and the resulting stress intensity factor is K
I = αkQ · Q. Therefore, the coefficient αkQ is ΔK I /
It can be obtained from ΔQ. In the case of this embodiment, α
evaluates to kQ = 0.862 × 10 3 m -3/2 . When this value is used in the above equation, a stress intensity factor can be obtained for a load of a desired size acting on a three-dimensional surface crack having a target shape and size in a target form.
【００３５】 Ｎｅｗｍａｎ−Ｒａｊｕは純曲げを受け
る平板の表面に垂直な半楕円板状亀裂の応力拡大係数を
弾性問題有限要素解析により求めている。ここで参考ま
でに、本発明の方法による評価結果と、Ｎｅｗｍａｎ−
Ｒａｊｕにより求められた応力拡大係数との比較を行っ
てみる。なおＮｅｗｍａｎ−Ｒａｊｕでは、本実施例側
の三点曲げとは異なり、純曲げが対象とされているた
め、比較にあたり、ここでは曲げモーメントの値を本実
施例における三点曲げによる負荷時の亀裂面でのモーメ
ントと等しく置いている。図１２に比較を示す。なお縦
軸は、亀裂深さ５．８５ｍｍの二次元亀裂に前記と同じ
曲げモーメントが三点曲げで作用したときの応力拡大係
数、ＫＩＯを用いて無次元化している。図１２より横軸
２ψ／πの値が０．５より大きい範囲において、本発明
による評価結果と、Ｎｅｗｍａｎ−Ｒａｊｕによる純曲
げの解はよく一致しており、純曲げに対する解との比較
ではあるが、本発明による方法の妥当性を示している。Newman-Raju finds the stress intensity factor of a semi-elliptical plate-shaped crack perpendicular to the surface of a flat plate subjected to pure bending by an elastic problem finite element analysis. Here, for reference, the evaluation results obtained by the method of the present invention and Newman-
A comparison with the stress intensity factor obtained by Raju will be made. In addition, in Newman-Raju, unlike the three-point bending on the side of the present embodiment, pure bending is an object. For comparison, here, the value of the bending moment is determined by the three-point bending in the present embodiment. Is set equal to the moment on the surface. FIG. 12 shows a comparison. Note ordinate, the stress intensity factor when the same bending moment is applied in three-point bending and the two-dimensional crack crack depth 5.85 mm, are dimensionless using K IO. From FIG. 12, in the range where the value of 2 軸 / π on the horizontal axis is larger than 0.5, the evaluation result of the present invention and the solution of the pure bending by Newman-Raju agree well, and the comparison with the solution for the pure bending shows that However, it shows the validity of the method according to the present invention.
【００３６】 図１０では、複数の電位差測定端子位
置を亀裂線に平行に並べたが、平行に限る必要はない。
また端子位置間隔も１．５ｍｍに限る必要はない。複数
の端子位置およびそれらの間隔はランダムであってもよ
い。 図１０では、電流入出力端子間隔を４０mmとした
が、４０mmに限る必要はない。 実施例では、周波数１０kHz、電流量１Ａの交流電流
を用いたが、これらの数値に限る必要はない。 実施例では、曲げ負荷を扱ったが、本方法の適用は
曲げに限らず可能である。 実施例では、負荷１、負荷２としてそれぞれ任意の
値を与えた場合を扱ったが、負荷１≠負荷２であればよ
く、これらの値の選び方は任意である。従って、負荷１
＝０、負荷２＝対象亀裂部材の運転荷重としてもよい。
この場合、図８のＥexを負荷１、Ｅ′exを負荷２に対す
る電位差であるとすれば、Ｅexは計測ではなく、理論解
析から求めることもできる。In FIG. 10, a plurality of potential difference measuring terminal positions are arranged in parallel to the crack line, but it is not limited to parallel.
Also, the terminal interval need not be limited to 1.5 mm. The plurality of terminal positions and their intervals may be random. In FIG. 10, the current input / output terminal interval is set to 40 mm. In the embodiment, an alternating current having a frequency of 10 kHz and a current amount of 1 A is used, but the present invention is not limited to these values. In the embodiment, the bending load is dealt with, but the application of the present method is not limited to the bending, but is possible. In the embodiment, the case where arbitrary values are given as the load 1 and the load 2 is dealt with. However, it is sufficient that the load 1 is equal to the load 2 and a method of selecting these values is arbitrary. Therefore, load 1
= 0, load 2 = operation load of the target crack member.
In this case, assuming that Eex in FIG. 8 is a potential difference with respect to the load 1 and E'ex is a potential difference with respect to the load 2, Eex can be obtained from theoretical analysis instead of measurement.
【００３７】交流電流の表皮効果を利用することによ
り、かつ電磁物性値のひずみ依存性ならびにひずみは亀
裂先端近傍に集中し、その集中は応力拡大係数によって
決まるという自然現象を利用して、亀裂部材表面上では
みえない三次元表面亀裂前縁における応力拡大係数の情
報を電位差変化という形で部材表面上に運び出し、それ
を測定して、さらに交流電流問題理論解析と照合するこ
とにより、図６の面Ｃ上から三次元表面亀裂前縁の応力
拡大係数を評価できるようにした。By utilizing the skin effect of the alternating current, the strain dependence of the electromagnetic properties and the strain are concentrated near the crack tip, and utilizing the natural phenomenon that the concentration is determined by the stress intensity factor, the crack member is used. The information of the stress intensity factor at the leading edge of the three-dimensional surface crack, which cannot be seen on the surface, is carried out on the member surface in the form of a change in potential difference, and it is measured. It was made possible to evaluate the stress intensity factor of the leading edge of the three-dimensional surface crack from the surface C.
【００３８】[0038]
【本発明の効果】本発明は、三次元亀裂問題を二次元の
電流問題に置き換えて解析するものであり、計算時間の
観点から利点があり、また運転時と同一形態の負荷を作
用させ、測定結果を得るが、運転負荷形態により、実際
に生じる応力拡大係数を直接反映したデータを計測し、
用いることになり、単なる理論解析と異なり、実際の運
転状態に対する応力拡大係数を直接評価できることにな
り、この点にも利点を有するものである。According to the present invention, a three-dimensional crack problem is analyzed by replacing it with a two-dimensional current problem, which has an advantage in terms of calculation time, and has the same form of load as during operation. Obtain measurement results, but measure the data that directly reflects the stress intensity factor that actually occurs, depending on the operating load type,
This means that the stress intensity factor for the actual operating condition can be directly evaluated, which is different from a mere theoretical analysis, which has an advantage also in this point.
【図１】従来の二次元亀裂材における応力拡大係数評価
のための計測面である。FIG. 1 is a measurement surface for evaluating a stress intensity factor in a conventional two-dimensional cracked material.
【図２】従来の応力拡大係数測定用ゲージの一例であ
る。FIG. 2 is an example of a conventional stress intensity factor measuring gauge.
【図３】（Ａ）（Ｂ）は従来のコースティック法の基本
原理図である。FIGS. 3A and 3B are basic principle diagrams of a conventional caustic method.
【図４】従来の光弾性法の基本原理図である。FIG. 4 is a basic principle diagram of a conventional photoelasticity method.
【図５】従来の交流電位差法による二次元亀裂の応力拡
大係数計測評価方法の原理的構成を示したものである。FIG. 5 shows a principle configuration of a conventional method for measuring and evaluating a stress intensity factor of a two-dimensional crack by an AC potential difference method.
【図６】本発明の三次元表面亀裂の応力拡大係数評価の
ための計測面である。FIG. 6 is a measurement plane for evaluating a stress intensity factor of a three-dimensional surface crack according to the present invention.
【図７】本発明の原理的構成を示したものである。FIG. 7 shows a basic configuration of the present invention.
【図８】本発明の三次元表面亀裂の応力拡大係数計測、
評価手法の概略図である。FIG. 8 shows a stress intensity factor measurement of a three-dimensional surface crack of the present invention,
It is a schematic diagram of an evaluation method.
【図９】 本発明で使用する交流電場の理論解析手法の
概略図である。FIG. 9 is a schematic diagram of a theoretical analysis method of an AC electric field used in the present invention.
【図１０】図中（イ）は本発明の実施例における亀裂部
材の正面図であり、（ロ）は亀裂を示したものである。FIG. 10A is a front view of a crack member according to the embodiment of the present invention, and FIG. 10B shows a crack.
【図１１】本発明における負荷の変化に対する電位差変
化の測定結果と理論計算結果を本発明実施例について示
したものである。FIG. 11 shows a measurement result and a theoretical calculation result of a potential difference change with respect to a load change in the present invention for the embodiment of the present invention.
【図１２】本発明による方法から得られた応力拡大係数
と弾性問題有限要素解析により得られた応力拡大係数と
の比較を本発明実施例について示したものである。FIG. 12 shows a comparison between the stress intensity factor obtained by the method according to the present invention and the stress intensity factor obtained by the elastic problem finite element analysis for the embodiment of the present invention.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 阿部 博之 宮城県仙台市太白区八木山南一丁目５ー ６ (72)発明者 金子 隆 埼玉県飯能市新町18ー８ (56)参考文献 特開 平３−189538（ＪＰ，Ａ) 特開 平３−56848（ＪＰ，Ａ) 特開 昭60−44857（ＪＰ，Ａ) 特開 昭57−24804（ＪＰ，Ａ) 特開 平２−245649（ＪＰ，Ａ) 特開 平１−114738（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) G01L 1/00 G01N 3/32 G01N 27/20 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Abe 1-5-6, Yagiyama-minami, Taishiro-ku, Sendai-shi, Miyagi Prefecture (72) Inventor Takashi Kaneko 18-8 Shinmachi, Hanno-shi, Saitama (56) References JP-A-3-189538 (JP, A) JP-A-3-56848 (JP, A) JP-A-60-44857 (JP, A) JP-A-57-24804 (JP, A) JP-A-2-245649 (JP, A A) JP-A-1-114738 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) G01L 1/00 G01N 3/32 G01N 27/20
Claims (1)
測定端子と電位差計測装置とデータ解析装置とを備え、
表面に亀裂が検出された検査対象の構造物（以下亀裂部
材という。）から交流電位差法を用いてデータを収集す
る際、第１段階として亀裂部材に負荷１を作用させ、亀
裂をまたいで電流入出力端子の位置を定め、かつ位置を
定められた電流入出力端子間で、亀裂をまたいだ複数の
二点間で電位差測定端子を介し、電位差計測装置により
電位差を計測し、第２段階として亀裂部材に作用させる
負荷の値を負荷１から負荷２に変化させ、負荷２の状態
で電位差を計測し、第３の段階として、第１の段階、第
２の段階で得られた複数の二点間の電位差データを、デ
ータ解析装置により解析し、対象亀裂の応力拡大係数と
負荷の関係を特定することを特徴とする交流電位差法に
よる三次元表面亀裂の応力拡大係数の計測評価方法。An AC constant current source, a current input / output terminal, a potential difference measuring terminal, a potential difference measuring device, and a data analyzing device,
When data is collected from a structure to be inspected having a crack detected on its surface (hereinafter referred to as a crack member) by using the AC potential difference method, a load 1 is applied to the crack member as a first step, and a current is applied across the crack. The position of the input / output terminal is determined, and between the determined current input / output terminals, the potential difference is measured by a potential difference measuring device through a potential difference measuring terminal between a plurality of points across a crack, and as a second step The value of the load acting on the crack member is changed from load 1 to load 2, and the potential difference is measured in the state of load 2, and as a third step, a plurality of two-steps obtained in the first and second steps are obtained. A method for measuring and evaluating a stress intensity factor of a three-dimensional surface crack by an AC potential difference method, characterized by analyzing potential difference data between points by a data analysis device and specifying a relationship between a stress intensity factor of a target crack and a load.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03272128A JP3116123B2 (en) | 1991-09-24 | 1991-09-24 | Measurement and evaluation method of stress intensity factor of three-dimensional surface crack by AC potential difference method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03272128A JP3116123B2 (en) | 1991-09-24 | 1991-09-24 | Measurement and evaluation method of stress intensity factor of three-dimensional surface crack by AC potential difference method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0772022A JPH0772022A (en) | 1995-03-17 |
| JP3116123B2 true JP3116123B2 (en) | 2000-12-11 |
Family
ID=17509484
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03272128A Expired - Fee Related JP3116123B2 (en) | 1991-09-24 | 1991-09-24 | Measurement and evaluation method of stress intensity factor of three-dimensional surface crack by AC potential difference method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3116123B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103883301A (en) * | 2014-03-31 | 2014-06-25 | 中国矿业大学 | Physical simulation method of coal-bed gas well hydraulic fractures |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4710061B2 (en) * | 2005-02-04 | 2011-06-29 | 株式会社竹中工務店 | Concrete component measuring apparatus and measuring method |
| JP4981472B2 (en) * | 2007-02-14 | 2012-07-18 | キヤノン株式会社 | Optical fringe generating member control apparatus and method |
| WO2018159294A1 (en) * | 2017-03-03 | 2018-09-07 | 東洋製罐グループホールディングス株式会社 | Strength inspection device, strength inspection method, and inner surface scratching method and inner surface scratching device for producing adjustment glass bottle |
| JP2018146324A (en) * | 2017-03-03 | 2018-09-20 | 東洋製罐グループホールディングス株式会社 | Device and method for inspecting strength |
-
1991
- 1991-09-24 JP JP03272128A patent/JP3116123B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103883301A (en) * | 2014-03-31 | 2014-06-25 | 中国矿业大学 | Physical simulation method of coal-bed gas well hydraulic fractures |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0772022A (en) | 1995-03-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Hicks et al. | A comparison of theoretical and experimental methods of calibrating the electrical potential drop technique for crack length determination | |
| EP1782038B1 (en) | Finite element analysis fatigue gage | |
| Robinson et al. | Measurement of K Ic on small specimens using critical crack tip opening displacement | |
| Ayatollahi et al. | A comprehensive photoelastic study for mode I sharp V-notches | |
| Berto | A criterion based on the local strain energy density for the fracture assessment of cracked and V-notched components made of incompressible hyperelastic materials | |
| Daoud et al. | Strain-energy release rate for a single-edge-cracked circular bar in tension | |
| Gomes et al. | Inverse structural damage identification problem in CFRP laminated plates using SFO algorithm based on strain fields | |
| Moutou Pitti et al. | Characterization of a cracked specimen with full-field measurements: direct determination of the crack tip and energy release rate calculation | |
| Stepanova et al. | Digital photoelasticity for calculating coefficients of the Williams series expansion in plate with two collinear cracks under mixed mode loading | |
| JP3116123B2 (en) | Measurement and evaluation method of stress intensity factor of three-dimensional surface crack by AC potential difference method | |
| Lobanov et al. | Mathematical data processing according to digital image correlation method for polymer composites | |
| Zheng et al. | Correlation of the Master curve reference temperature T0 with unified constraint parameter | |
| Abshirini et al. | Interaction of two parallel U-notches with tip cracks in PMMA plates under tension using digital image correlation | |
| Shah et al. | Toughening mechanisms in quasi-brittle materials | |
| Dong et al. | Marker load-aided bidirectional fatigue crack growth rate measurement via a semi-elliptical surface crack | |
| CN108548729A (en) | A kind of method and apparatus measuring material maximum stress in bend | |
| Lloyd et al. | Microtopography for ductile fracture process characterization Part 2: application for CTOA analysis | |
| Reddy et al. | Digital image correlation for structural health monitoring–a review | |
| Zhang et al. | Detection of fatigue crack propagation through damage characteristic FWHM using FBG sensors | |
| Hyde et al. | A compact mixed-mode (CMM) fracture specimen | |
| Marek et al. | Distortional hardening cyclic plasticity: Experiments and modeling | |
| Wissuchek et al. | A simple method for measuring surface strains around cracks | |
| Roebuck et al. | Data acquisition and analysis of tensile properties for metal matrix composites | |
| JP2001056272A (en) | Measuring method of stress enlarging factor | |
| Liu et al. | Fracture assessments of blunt V-notches using the coherent gradient sensing (CGS) method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20081006 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20091006 Year of fee payment: 9 |
|
| LAPS | Cancellation because of no payment of annual fees |