JP2546747B2 - Method to detect crack growth of steel bridge structure using AE method - Google Patents
Method to detect crack growth of steel bridge structure using AE methodInfo
- Publication number
- JP2546747B2 JP2546747B2 JP3103333A JP10333391A JP2546747B2 JP 2546747 B2 JP2546747 B2 JP 2546747B2 JP 3103333 A JP3103333 A JP 3103333A JP 10333391 A JP10333391 A JP 10333391A JP 2546747 B2 JP2546747 B2 JP 2546747B2
- Authority
- JP
- Japan
- Prior art keywords
- crack
- sensor
- monitoring area
- signal
- crack growth
- 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 - Lifetime
Links
Landscapes
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ＡＥ法（アコースティ
ックエミッション法）を利用した鋼製橋梁構造物の診断
に関するもので、さらに詳しくは既設の橋梁構造物に生
じている亀裂の進展状況をノイズ除去手段を備えたＡＥ
法を用いて精度良く検査する方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to diagnosis of a steel bridge structure using the AE method (acoustic emission method), and more specifically, to the progress of cracks in an existing bridge structure as noise. AE with removal means
The present invention relates to a method for inspecting with high accuracy using a method.
【０００２】[0002]
【従来の技術】ＡＥ法は固体が変形もしくは破壊する際
にそれまで貯えられていたひずみエネルギーが解放され
て弾性波となって伝搬する現象を利用した検査法で、従
来からタンクや圧力容器等の検査に用いられた例は多
い。この検査法は、製品の完成後にその製品に多数のＡ
Ｅセンサーを取付け、製品に水圧等の外力を徐々に作用
させた際に生じる解放エネルギーによるＡＥ信号から亀
裂の発生とその位置を検知（標定）するものである。こ
のＡＥ検査においては、一般にノイズが多く目的のＡＥ
信号のみを抽出することが重要となる。従来から、ノイ
ズ除去法については、いくつかの方法が提案されてい
る。例えば「アコースティックエミッションの基礎と応
用」（株式会社コロナ社，昭和５１年１２月２５日発
行）に記載されている３つの空間フィルター法がある。
この方法は、（ａ）計測用ＡＥセンサーの外側にゲート
用ＡＥセンサーを設け、監視域外からの機械振動等のノ
イズをゲート用ＡＥセンサーで受信したらゲート開路を
閉じて、計測用ＡＥセンサーから出力させない方法、
（ｂ）２個のＡＥセンサーにほぼ同時に到達した波のみ
ＡＥ信号とみなすコインシデンス法、（ｃ）立上がりの
遅い波形は遠方からのノイズ信号として除く方法等であ
る。2. Description of the Related Art The AE method is an inspection method that utilizes the phenomenon that strain energy stored until then is released when a solid is deformed or destroyed and propagates as an elastic wave. There are many cases used for the examination of. This inspection method requires a large number of A
An E sensor is attached to detect (locate) a crack and its position from an AE signal due to release energy generated when an external force such as water pressure is gradually applied to the product. In this AE inspection, there is generally a lot of noise and the target AE
It is important to extract only the signal. Heretofore, some methods have been proposed as noise removal methods. For example, there are three spatial filter methods described in "Fundamentals and Applications of Acoustic Emission" (Corona Co., Ltd., issued December 25, 1976).
In this method, (a) a gate AE sensor is provided outside the measurement AE sensor, and when noise such as mechanical vibration from outside the monitoring area is received by the gate AE sensor, the gate open circuit is closed and output from the measurement AE sensor. How not to
(B) The coincidence method in which only the waves that arrive at two AE sensors almost at the same time are regarded as AE signals, and (c) the waveform with a slow rising edge is removed as a noise signal from a distance.
【０００３】[0003]
【発明が解決しようとする課題】本発明者等は、ＡＥ法
を既設橋梁の亀裂診断に利用する研究を行ってきたが、
従来のタンクや圧力容器等のＡＥ検査と異なり、橋梁構
造物はボルト結合部や沓部が存在し複雑な形状をしてお
り、また、走行車輛の繰返し荷重によるため非常に多く
のノイズ環境下での診断となるので、あらかじめ未知の
亀裂をＡＥ法によって検知することは、困難であること
が判った。また亀裂の存在位置が確認されている場合に
おいても、従来の空間フィルター法のみでは亀裂の進展
を検査することは出来なかった。即ち、監視域外からの
ノイズは除去できるが、監視域内において、走行車輛に
よる繰返し荷重の外力によって生じる新規な亀裂発生に
よる、解放エネルギーによるＡＥ信号の他に、既に生じ
ている亀裂部から生じる、叩き合いやこすれ合いによる
見掛けＡＥ信号（ノイズ）が発生するため、監視域内の
信号のみでは亀裂進展との相関が得られなかった。The inventors of the present invention have conducted researches using the AE method for crack diagnosis of existing bridges.
Unlike conventional AE inspection of tanks and pressure vessels, the bridge structure has a complicated shape with bolt joints and troughs, and due to repeated load of the traveling vehicle, it is exposed to a lot of noise environment. Therefore, it has been found that it is difficult to detect an unknown crack by the AE method in advance. Further, even when the location of the crack was confirmed, the progress of the crack could not be inspected only by the conventional spatial filter method. That is, noise from outside the monitoring area can be removed, but within the monitoring area, a new crack is generated due to the external force of the repeated load by the traveling vehicle, and in addition to the AE signal due to the release energy, the striking from the already existing crack portion is generated. Since an apparent AE signal (noise) is generated due to the contact and rubbing, the correlation with the crack growth cannot be obtained only with the signal within the monitoring area.
【０００４】[0004]
【課題を解決するための手段】本発明は、強度に影響を
及ぼさない程度の微少な亀裂を有する既設の橋梁構造物
において安全性を確保するために、亀裂の進展状況を監
視するＡＥ検査法を提供することを目的とするものであ
って、橋梁構造部材の亀裂先端位置近傍とあらかじめ予
測される亀裂進展方向のそれぞれに、複数のＡＥセンサ
ーを空間フィルターを形成するように配置することによ
り限定した監視域を設け、走行車輛によって生じる繰返
し荷重からそれぞれの監視域内に発生するＡＥ信号のみ
を抽出し、その経時変化の状況から亀裂の進展状況を推
定する。The present invention provides an AE inspection method for monitoring the progress of cracks in order to ensure safety in an existing bridge structure having minute cracks that do not affect the strength. The purpose of the present invention is to provide a plurality of AE sensors so as to form a spatial filter in the vicinity of the crack tip position of the bridge structural member and in each of the crack propagation directions predicted in advance. The monitoring area is provided, and only the AE signal generated in each monitoring area is extracted from the repeated load generated by the traveling vehicle, and the progress of cracks is estimated from the change over time.
【０００５】[0005]
【実施例】図１〜図５は本発明における空間フィルター
を説明するための図面である。空間フィルターを構成す
るには、４箇のＡＥセンサーＳ1 〜Ｓ4 を用い、このう
ちＡＥセンサーＳ1 を亀裂部または亀裂進展方向に設け
て測定センサーとし、他の３箇のＡＥセンサーＳ2 〜Ｓ
4 をＡＥセンサーＳ1 の周りの３方向に任意距離離して
設ける。なお３箇のＡＥセンサーＳ2 〜Ｓ4 をＡＥセン
サーＳ1 の周りの３方向に等距離で設けてもよい。監視
域はＡＥセンサーＳ1 の周りに形成され、その範囲Δｌ
は被検体の音速Ｖとの関係から受信時間範囲Δｔを設定
することにより任意に定めることができる。即ち、例え
ば被検出体が鋼でＶ＝３０００ｍ／ｓの場合、設定時間
範囲Δｔ＝１０μｓにすれば、Δｌ＝Ｖ×Δｔ＝３ｃｍ
となる。ＡＥ信号測定は、図２に示す如くＡＥセンサー
Ｓ1 の受信波を基準とし、それぞれのＡＥセンサーＳ2
〜Ｓ4 との距離に対応した時間ｔ2 ＝ｌ2 ／ｖ，ｔ3 ＝
ｌ3 ／ｖ，ｔ4 ＝ｌ4 ／ｖ後に設定時間範囲Δｔを設け
ておく。３箇のＡＥセンサーＳ2 〜Ｓ4 が、すべてこの
設定時間内に受信した場合のみ、監視域内から生じたＡ
Ｅ信号、即ち亀裂によるＡＥ信号である。図３は監視域
内ａ点から信号を各ＡＥセンサーＳ2 〜Ｓ4 が受信した
場合で、各ＡＥセンサーＳ2 〜Ｓ4 はすべて設定時間範
囲内で受信している。また図４および図５は監視域外の
ｂ点およびｃ点から発生したノイズであり、３箇のＡＥ
センサーＳ2 〜Ｓ4 が、すべて設定時間範囲内に受信す
ることを満足していない例を示している。以上述べたよ
うに、空間フィルターによりＡＥセンサーＳ1 周りの特
定の監視域内のみから生じるＡＥ信号のみを検出し、そ
の他のノイズを除去することができる。1 to 5 are drawings for explaining a spatial filter according to the present invention. In order to configure the spatial filter, four AE sensors S 1 to S 4 are used. Of these, the AE sensor S 1 is provided at the crack portion or the crack propagation direction to serve as a measurement sensor, and the other three AE sensors S 2 are used. ~ S
4 are provided at arbitrary distances in three directions around the AE sensor S 1 . Note that the three AE sensors S 2 to S 4 may be provided equidistantly in three directions around the AE sensor S 1 . The surveillance area is formed around the AE sensor S 1 and its range Δl
Can be arbitrarily set by setting the reception time range Δt from the relationship with the sound velocity V of the subject. That is, for example, when the detected object is steel and V = 3000 m / s, if the set time range Δt = 10 μs, Δl = V × Δt = 3 cm
Becomes AE signal measurement, with reference to the received wave AE sensor S 1 as shown in FIG. 2, each of the AE sensor S 2
~ Time corresponding to the distance from S 4 t 2 = l 2 / v, t 3 =
A set time range Δt is set after l 3 / v, t 4 = l 4 / v. Only when all three AE sensors S 2 to S 4 receive within this set time,
The E signal, that is, the AE signal due to the crack. Figure 3 is receiving signals from the surveillance area a point when receiving the respective AE sensor S 2 to S 4, within each AE sensor S 2 to S 4 are all set time range. 4 and 5 show noise generated from points b and c outside the monitoring area, and
An example is shown in which the sensors S 2 to S 4 are not all satisfied to receive within the set time range. As described above, the spatial filter can detect only the AE signal generated only within the specific monitoring area around the AE sensor S 1 and remove other noises.
【０００６】次に亀裂進展の監視を行う方法を図６ない
し図９によって説明する。前記の如く、空間フィルター
を形成するようにした監視域Ａを、あらかじめ目視，カ
ラーチェック，超音波検査等によって確認した橋梁ウェ
ブ３の亀裂１の先端部近傍に設ける。また、同様な監視
域Ｂを予測される亀裂１の進展方向２に複数箇所設け
る。亀裂の進展方向２は、最大引張主応力と直交する方
向となるため、応力解析から推定することができる。例
えば単純梁の橋梁主桁では縦スチフナーの端部に沿って
進展しやすくその亀裂がウェブ部に向かって進展するた
め容易に予測できる。亀裂進展を監視するには、既に亀
裂が生じている箇所の監視域Ａと亀裂の進展方向に最低
１箇所の監視域Ｂを設ければ良いが、亀裂進展の様子を
詳しく知りたい場合は、監視域Ｂを適宜間隔毎に複数設
ける方が好ましい。図６は監視域Ｂ1 ，Ｂ2 の２箇所に
設けた例を示している。図６において、４は橋梁の下フ
ランジである。Next, a method for monitoring crack growth will be described with reference to FIGS. As described above, the monitoring area A for forming the spatial filter is provided in the vicinity of the tip of the crack 1 of the bridge web 3 which is previously confirmed by visual inspection, color check, ultrasonic inspection and the like. Further, a plurality of similar monitoring areas B are provided in the predicted propagation direction 2 of the crack 1. Since the crack propagation direction 2 is a direction orthogonal to the maximum tensile principal stress, it can be estimated from the stress analysis. For example, in the case of a bridge main girder with a simple beam, it is easy to propagate along the end of the vertical stiffener and its cracks can be easily predicted because they propagate toward the web portion. In order to monitor the crack growth, it is sufficient to provide a monitoring area A where the crack has already occurred and at least one monitoring area B in the crack growth direction, but if you want to know the state of the crack growth in detail, It is preferable to provide a plurality of monitoring areas B at appropriate intervals. FIG. 6 shows an example in which the monitoring areas B 1 and B 2 are provided at two locations. In FIG. 6, 4 is a lower flange of the bridge.
【０００７】図７ないし図９は本発明の亀裂進展検出法
を疲労試験で確認した例を示すものである。ＡＥ信号は
当初監視域Ａ（亀裂近傍）に多く見られ、監視域Ｂでは
ほとんど認められないが、繰返し数の増加に伴い、監視
域ＡのＡＥ信号は減少し、監視域Ｂ1 のＡＥ信号が急激
に増加しその後減少する。次に監視域Ｂ2 のＡＥ信号が
急激に増加している。即ち、監視域Ｂ1，Ｂ2 のＡＥ信
号が急激に増加した時点で、それぞれの監視域に亀裂が
進展したことを示している。なお、監視域Ａ，Ｂを亀裂
が通過した後は本来新たな亀裂は生じないためＡＥ信号
は生じないはずであるが、ＡＥ信号が計測されているの
は亀裂破面の叩き合い等によるものと推定される。7 to 9 show an example in which the crack growth detecting method of the present invention is confirmed by a fatigue test. Initially, many AE signals were observed in the monitoring area A (near the cracks) and were hardly observed in the monitoring area B, but as the number of repetitions increased, the AE signal in the monitoring area A decreased and the AE signal in the monitoring area B 1 Rapidly increases and then decreases. Next, the AE signal in the monitoring area B 2 is rapidly increasing. That is, when the AE signals of the monitoring areas B 1 and B 2 suddenly increase, it is shown that cracks have propagated to the respective monitoring areas. After the crack passes through the monitoring areas A and B, no new crack originally occurs, so an AE signal should not occur. However, the AE signal is measured because of the striking of the fracture surfaces. It is estimated to be.
【０００８】[0008]
【発明の効果】本発明によれば、空間フィルターでノイ
ズを除去し、更に予測される亀裂進展方向に監視域を設
けることにより、非常に多くのノイズを含む場合でも正
確に亀裂の進展を監視することができるため橋梁の安全
監視を確実に行うことができる優れた効果を発揮する。According to the present invention, noise is removed by a spatial filter, and a monitoring area is provided in the predicted crack growth direction, so that crack growth can be accurately monitored even when a large amount of noise is included. Therefore, it has an excellent effect that the safety monitoring of the bridge can be surely performed.
【図１】監視域とＡＥセンサーとの配置関係を示す図で
ある。FIG. 1 is a diagram showing an arrangement relationship between a monitoring area and an AE sensor.
【図２】各センサーの受信時間範囲設定図である。FIG. 2 is a reception time range setting diagram of each sensor.
【図３】ａ，ｂ，ｃ点からの信号を受信した例を示す図
である。FIG. 3 is a diagram showing an example in which signals from points a, b, and c are received.
【図４】ａ，ｂ，ｃ点からの信号を受信した他の例を示
す図である。FIG. 4 is a diagram showing another example in which signals from points a, b, and c are received.
【図５】ａ，ｂ，ｃ点からの信号を受信した他の例を示
す図である。FIG. 5 is a diagram showing another example in which signals from points a, b, and c are received.
【図６】本発明により亀裂進展を検査する監視域の配置
を示す図である。FIG. 6 is a diagram showing an arrangement of monitoring areas for inspecting crack growth according to the present invention.
【図７】本発明により得られた監視域ＡのＡＥ信号のデ
ータを示す図である。FIG. 7 is a diagram showing data of an AE signal in a monitoring area A obtained by the present invention.
【図８】本発明により得られた監視域Ｂ1 のＡＥ信号の
データを示す図である。FIG. 8 is a diagram showing data of an AE signal in a monitoring area B 1 obtained by the present invention.
【図９】本発明により得られた監視域Ｂ2 のＡＥ信号の
データを示す図である。FIG. 9 is a diagram showing data of the AE signal of the monitoring area B 2 obtained by the present invention.
Ｓ1 ＡＥセンサー（第一ＡＥ信号受信センサー） Ｓ2 ＡＥセンサー（第二受信センサー） Ｓ3 ＡＥセンサー（第三受信センサー） Ｓ4 ＡＥセンサー（第四受信センサー） Ｓ 信号波 Δｔ 受信時間範囲 Ａ 亀裂先端監視域 Ｂ1 亀裂進展監視域 Ｂ2 亀裂進展監視域 １ 亀裂 ２ 亀裂進展方向 ３ 橋梁ウェブ ４ 下フランジS 1 AE sensor (1st AE signal receiving sensor) S 2 AE sensor (2nd receiving sensor) S 3 AE sensor (3rd receiving sensor) S 4 AE sensor (4th receiving sensor) S signal wave Δt reception time range A Crack tip monitoring area B 1 Crack growth monitoring area B 2 Crack growth monitoring area 1 Crack 2 Crack growth direction 3 Bridge web 4 Lower flange
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭61−284657（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-61-284657 (JP, A)
Claims (1)
かじめ予測される亀裂進展方向のそれぞれに、複数のＡ
Ｅセンサーを空間フィルターを形成するように配置する
ことにより限定した監視域を設け、走行車輪によって生
じる振動からそれぞれの監視域内を発生源とするＡＥ信
号のみを抽出してその経時変化の状況から亀裂の進展状
況を推定することを特徴とするＡＥ法を利用した鋼製橋
梁構造物の亀裂進展検出法。1. A plurality of A's are provided in the vicinity of the crack tip position of the bridge structure member and in each of the crack propagation directions predicted in advance.
A limited monitoring area is provided by arranging the E sensor so as to form a spatial filter, and only the AE signals originating from within the respective monitoring areas are extracted from the vibration generated by the traveling wheels, and cracks are generated from the situation of the change over time. A method for detecting crack growth in steel bridge structures using the AE method, which is characterized by estimating the progress of
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3103333A JP2546747B2 (en) | 1991-04-09 | 1991-04-09 | Method to detect crack growth of steel bridge structure using AE method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3103333A JP2546747B2 (en) | 1991-04-09 | 1991-04-09 | Method to detect crack growth of steel bridge structure using AE method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04310857A JPH04310857A (en) | 1992-11-02 |
| JP2546747B2 true JP2546747B2 (en) | 1996-10-23 |
Family
ID=14351235
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3103333A Expired - Lifetime JP2546747B2 (en) | 1991-04-09 | 1991-04-09 | Method to detect crack growth of steel bridge structure using AE method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2546747B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4373627B2 (en) * | 2001-08-23 | 2009-11-25 | 株式会社東芝 | Defect depth measurement method for structures |
| JP2011196799A (en) * | 2010-03-18 | 2011-10-06 | National Institute Of Advanced Industrial Science & Technology | Rubber product inspection method and rubber product inspection device |
| JP2015098686A (en) * | 2013-11-18 | 2015-05-28 | 彬 小林 | Preventive maintenance monitoring system of structure |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61284657A (en) * | 1985-06-11 | 1986-12-15 | Sumitomo Metal Ind Ltd | Crack inspecting method |
-
1991
- 1991-04-09 JP JP3103333A patent/JP2546747B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04310857A (en) | 1992-11-02 |
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