JP2004317158A

JP2004317158A - Method for measuring stress of member to be measured made of nonmagnetic material

Info

Publication number: JP2004317158A
Application number: JP2003107838A
Authority: JP
Inventors: Takashi Matsuoka; 敬松岡; Yasuhiro Fujioka; 康博藤岡; Takuya Oda; 卓也織田; Akira Iwagami; 明岩上; Takeshi Aritsune; 健有常; Seiichi Yasufuku; 精一安福
Original assignee: Chugoku Electric Power Co Inc; Chuden Engineering Consultants Co Ltd
Current assignee: Chugoku Electric Power Co Inc; Chuden Engineering Consultants Co Ltd
Priority date: 2003-04-11
Filing date: 2003-04-11
Publication date: 2004-11-11

Abstract

<P>PROBLEM TO BE SOLVED: To monitor stress changes in a long period on stress measurement on a member to be measured, a structure made of a nonmagnetic material. <P>SOLUTION: A measuring plate 2 made of a magnetic body is pasted to the member to be measured 1 made of a nonmagnetic material, and distortion of the measuring plate 2 is converted into stress by a magnetostrictive method to measure stress of the member to be measured 1. Stress immediately after the measuring plate 2 is pasted to the member to be measured 1 or before the pasting is measured by a magnetostrictive method and taken as initial stress. Stress of the measuring plate 2 after load of the member to be measured 1 is changed is measured by a magnetostrictive method, and the difference between the result of stress measurement after the load of the measuring plate 2 is changed and the initial stress is taken as stress of the member to be measured 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、構造物、特に非磁性材料からなる被測定部材の応力測定方法に関するものである。
【０００２】
【従来の技術】
従来、コンクリートなどの構造物の応力測定は歪みゲージ法により計測するのが一般的である。
図７は、このような従来の歪みゲージ法による応力測定方法を示すもので、被測定部材がコンクリートでその壁面ａに歪みゲージｂが防水用接着剤ｃにて貼付されている。歪みゲージｂには図示しない測定機器に接続するためのリード線ｄが設けられている。
【０００３】
そして、コンクリートａに応力がかかると、これとともに歪みゲージｂがその応力により歪み、これにより抵抗値が変化するため、該抵抗値の変化を応力換算してコンクリートａにかかった応力を測定することが出来る。
【０００４】
【発明が解決しようとする課題】
しかしながら、歪みゲージ法による応力測定方法にあっては、歪みゲージをコンクリートに貼付しなければならず、この歪みゲージは剥がれやすく一般的に寿命が短いため、長期間にわたる応力変化をモニタリングすることができないという問題があった。
【０００５】
【特許文献１】
ところで、構造体の応力測定には、その構造体が磁性材料である場合に、特開平２００３−２１５６３号に示されたような磁歪法を利用することが出来る。磁歪法による応力測定方法とは、強磁性材料に荷重が作用すると透磁率に異方性が生じ、荷重方向の透磁率が大きくなり、反対に荷重方向と直角方向の透磁率が小さくなるので、両透磁率の差を磁歪センサ（磁歪測定器の検出プローブ）により検出することによって、主応力の方向および大きさを測定する手法である。
【０００６】
しかし、被測定部材が非磁性材料から成る構造体にあっては、磁歪法による応力測定方法を用いることができず、歪みゲージ法により応力測定を行うしかなかった。
【０００７】
本発明は、かかる問題点を解決するために創設されたものである。すなわち、本発明の目的は、非磁性材料からなる構造物を被測定部材とし、その応力測定に関し、長期間にわたる応力変化をモニタリングすることが出来る非磁性材料からなる被測定部材の応力測定方法を提供することにある。
【０００８】
【課題を解決するための手段】
本発明の非磁性材料からなる被測定部材（１）の応力測定方法は、被測定部材（１）に磁性体からなる測定板（２）を貼付し、該測定板（２）の歪みを磁歪法により応力に換算して上記被測定部材（１）の応力を測定するようにしたことを特徴とする。
この発明によれば、コンクリートなどの非磁性材料からなる構造体の応力を磁歪法で測定することを可能とし、従来のように歪みゲージ法における歪みゲージ（５）を構造物に貼付する必要がないため、長期間にわたる応力変化をモニタリングすることが出来る。
【０００９】
測定板（２）の被測定部材（１）への貼付直後または貼付前の応力を磁歪法により測定して初期応力とし、被測定部材（１）の荷重変化後の測定板（２）の応力を磁歪法により測定して、該測定板（２）の荷重変化後の応力測定結果と上記初期応力との差分を被測定部材（１）の応力とすると、測定板（２）の初期応力を除いた被測定部材（１）の応力変化を精度良く測定することが出来る。
【００１０】
測定板（２）についてこれにかけた応力とそのときの磁歪法における磁歪測定器の出力電圧との対応関係を調べておき、該対応関係に基づいて以後の被測定部材（１）の磁歪法による応力測定を行うようにすると、被測定部材（１）の応力の測定をさらに精度良く行うことが出来る。
【００１１】
歪みゲージ（５）を上記測定板（２）に貼付し、磁歪法による測定板（２）の出力電圧と上記歪みゲージ（５）を用いた歪みゲージ法による応力値との関係を、以後の被測定部材（１）の磁歪法による応力測定に用いると、磁歪法による応力測定結果を歪みゲージ法による応力値で検証することが出来る。
【００１２】
歪みゲージ（６）を上記測定板（２）の近傍における被測定部材（１）に貼付し、磁歪法による該測定板（２）の出力電圧と上記歪みゲージ（６）を用いた歪みゲージ法による応力値との関係を、以後の被測定部材（１）の磁歪法による応力測定に用いると、磁歪法による応力測定結果を歪みゲージ法による応力値で検証することができ、検証の結果を上記測定板（２）の磁歪法による応力測定方法にフィードバックすることによりさらに精度良い測定結果を得ることが期待できる。
【００１３】
磁歪法による測定点（４）を複数設けると、複数の測定点（４）の測定値からせん断応力差積分法を用いて主応力をさらに精度良く測定ことが出来る。
【００１４】
測定板（２）の厚さを被測定部材（１）の応力変化に影響がない程度のものにすると、被測定部材（１）にかかる応力のみを精度良く測定できる。
【００１５】
測定板（２）を被測定部材（１）に蒸着することにより形成すると、測定板（２）の被測定部材（１）への貼付を簡単にすることが出来る。
【００１６】
【発明の実施の形態】
以下、本発明の好ましい実施の形態を図面を参照にして説明する。なお、各実施の形態は本発明をコンクリートの応力測定方法に適用したものである。
【００１７】
図１及び図２は、第１の実施の形態にかかるもので被測定部材としてコンクリート１に測定板である鋼板２を貼付したものを示し、図１は正面図を、図２は断面図を示す。
測定板２としてこの実施の形態では鋼板を用いたが、他に鉄・ニッケル・コバルト等の磁性体からなるものであればよい。
【００１８】
鋼板２はコンクリート壁面１に接着剤３により貼付される。コンクリート壁面１又は鋼板２に接着剤３を塗布した後、接着剤３が完全に硬化しない状態で鋼板２をコンクリート壁面１に貼付する。接着剤３は硬化に伴う収縮が少ないものを使用することが望ましい。これは接着剤３が硬化するときに鋼板２に応力が発生してしまうからである。
【００１９】
鋼板２の厚さは、例えば０．３ｍｍとされ、コンクリート１に応力がかかったときに、鋼板２が貼付されていることによりその応力に影響を与えない程度のものとする。なお、あらかじめ、鋼板２をコンクリート１に貼付することによるコンクリート１にかかる応力に対して与える影響の度合いを解析することにより、多少厚い鋼板を用いることも可能である。
鋼板２については、予め応力と磁歪式応力測定器の出力電圧の関係（磁化特性）を調べておく。
【００２０】
コンクリート１にかかる応力変化を測定するには、先ず、鋼板２の任意の点を測定点４（図面上●で表した部位である。以下同じ。）とし、該測定点４に磁歪測定器の検出プローブ（磁歪センサ）を当てて、その出力電圧を検出する。この測定点４は、図１に示すように碁盤目状に複数箇所とする。測定点４を複数箇所とするのは、磁歪測定器の出力電圧から得られる応力値が主応力差であることから、せん断応力差積分法を用いて主応力を分離するためである。なお、応力が作用する方向が明確な場合には測定点４は１点でも構わない。
【００２１】
このように、コンクリート１にかかる応力が変化したときには、鋼板２について磁歪測定法を用いて鋼板２の応力を測定することにより、コンクリート１にかかる応力を測定することが出来る。
【００２２】
そして、従来のように歪みゲージを用いないため、非磁性材料からなる被測定部材の長期間にわたる応力変化をモニタリングすることが出来る。
【００２３】
また、鋼板２をコンクリート１に貼付したときに、鋼板２に磁歪測定器の検出プローブ（磁歪センサ）を当ててその初期応力を測定すると、精度良い応力測定を行うことが出来る。
【００２４】
すなわち、鋼板２はその製造工程において、或いはコンクリート壁面への貼付時に応力が発生する場合がある。かかる初期応力が残留応力として残った状態である場合にはその後の応力測定に誤差が生じる可能性があり、測定結果を不正確なものにしてしまう。特に、鋼板２をボルト締めによりコンクリート１壁面に貼付した場合には、鋼板２にボルト締めによる応力が発生してしまっている。
【００２５】
そこで、コンクリート１に鋼板２を貼付した後鋼板２の初期応力を磁歪測定法により測定し、コンクリート１にかかる荷重変化等による応力の変化は、随時磁歪法で計測した応力と初期応力の差で表すことで、さらに精度良いコンクリート１の応力測定を行うことが出来る。
【００２６】
図３は、第２の実施の形態にかかるもので、正面図を示す。この第２の実施の形態が上記第１の実施の形態と異なる点は、鋼板２に歪みゲージを貼付した点である。従って、第２の実施の形態の説明については、上記第１の実施の形態を同様の部分については、図面に同一符号を付すことにより説明を省略し、異なる部分について主に説明する。
【００２７】
鋼板２には、図３に示すように、２つの歪みゲージ５がそれぞれ貼付されている。この歪みゲージ５は、鋼板２に生じた応力を測定することが出来る。
【００２８】
そして、コンクリート１に応力変化があった場合、鋼板２とともに歪みゲージ５も歪むため、鋼板２の磁歪測定法による応力測定と歪みゲージ５の歪みゲージ法による応力測定を同時に行うことが出来る。
【００２９】
そのため、特に、鋼板２について予め応力と磁歪式応力測定器の出力電圧の関係（磁化特性）が不明である場合でも、鋼板２を歪みゲージ法により応力測定を精度良く行うことが出来る。そして、鋼板２の磁歪法による出力電圧と上記歪みゲージ法による応力との対応関係から、以後の鋼板２についての磁歪法による応力測定法に用いることができ、コンクリート１の応力測定を可能にする。特に、短期間でのコンクリート１の応力変化が見込めるときに有効であり、また、測定板について応力と出力電圧の関係（磁化特性）が明確で無い磁性体の応力も簡単に計測できる。
【００３０】
図４は、第３の実施の形態にかかるもので、正面図を示す。この第３の実施の形態が上記第１の実施の形態と異なる点は、歪みゲージを鋼板２の他にコンクリート１壁面に貼付した点である。従って、第３の実施の形態の説明については、上記第１の実施の形態を同様の部分については、図面に同一符号を付すことにより説明を省略し、異なる部分について主に説明する。
【００３１】
コンクリート１の壁面であって、上記鋼板２の貼付箇所の近傍には２つの歪みゲージ６が貼付されている。
【００３２】
そして、コンクリート１に応力変化があった場合、鋼板２とともに歪みゲージ６が歪むため、鋼板２の磁歪測定法による応力測定と歪みゲージ６の歪みゲージ法による応力測定を同時に行うことができ、鋼板２についての磁歪法による応力測定方法の結果をコンクリート１の歪みゲージ法による応力測定値で検証することができ、検証の結果を上記鋼板２の磁歪法による応力測定方法にフィードバックすることによりさらに精度良い測定結果を得ることが期待できる。
【００３３】
なお、この第３の実施の形態にかかる鋼板２に、さらに別の歪みゲージを貼付し、該歪みゲージを用いて歪みゲージ法により鋼板２の応力測定を行い、その測定値を加味してコンクリート１の応力測定に反映させることが出来るのは勿論である。
【００３４】
図５及び図６は、第４の実施の形態にかかるもので、図５は正面図を、図６は断面図を示す。この第４の実施の形態が上記第１の実施の形態と異なる点は、測定板を鋼板２でなく、ニッケルの蒸着膜にした点である。従って、第４の実施の形態の説明については、上記第１の実施の形態を同様の部分については、図面に同一符号を付すことにより説明を省略し、異なる部分について主に説明する。
【００３５】
コンクリート１の壁面の任意の箇所にニッケルの蒸着膜７を形成し、該ニッケル蒸着膜７を測定板とした。
そして、ニッケル蒸着膜７の任意な点に複数の磁歪法による測定点４を形成する。
【００３６】
このように、コンクリート１に応力変化があった場合、ニッケル蒸着膜７が歪むため、これを磁歪測定法により応力測定することによりコンクリート１の応力変化を測定することが出来る。
また、この第４の実施の形態にあっては、測定板を蒸着膜としたが本発明はこれに限らず、磁性材料を塗布するようにしてもよい。
【００３７】
なお、上記各実施の形態において、被測定部材をコンクリートとしたが、本発明はこれに限らず、プラスチック等の非磁性材料から成るものであればよい。
【００３８】
【発明の効果】
上述したように、本発明の非磁性材料からなる被測定部材の応力測定方法は、非磁性材料からなる被測定部材の応力測定方法であって、被測定部材に磁性体からなる測定板を被測定部材に貼付し、該測定板の歪みを磁歪法により応力に換算して上記被測定部材の応力を測定するようにしたことを特徴とする。
この発明によれば、コンクリートなどの非磁性材料からなる構造体の応力を磁歪法で測定することを可能とし、従来のように歪みゲージ法における歪みゲージを構造物に貼付する必要がないため、長期間にわたる応力変化をモニタリングすることが出来る。
【００３９】
測定板の被測定部材への貼付直後または貼付前の応力を磁歪法により測定して初期応力とし、被測定部材の荷重変化後の測定板の応力を磁歪法により測定して、該測定板の荷重変化後の応力測定結果と上記初期応力との差分を被測定部材の応力とすると、測定板の初期応力を除いた被測定部材の応力変化を精度良く測定することが出来る。
【００４０】
測定板についてこれにかけた応力とそのときの磁歪法における磁歪測定器の出力電圧との対応関係を調べておき、該対応関係に基づいて以後の被測定部材の磁歪法による応力測定を行うようにすると、被測定部材の応力の測定をさらに精度良く行うことが出来る。
【００４１】
歪みゲージを上記測定板に貼付し、磁歪法による測定板の出力電圧と上記歪みゲージを用いた歪みゲージ法による応力値との関係を、以後の被測定部材の磁歪法による応力測定に用いると、磁歪法による応力測定結果を歪みゲージ法による応力値で検証することができ、検証の結果を上記鋼板の磁歪法による応力測定方法にフィードバックすることによりさらに精度良い測定結果を得ることが期待できる。
【００４２】
歪みゲージを上記測定板の近傍における被測定部材に貼付し、磁歪法による該測定板の出力電圧と上記歪みゲージを用いた歪みゲージ法による応力値との関係を、以後の被測定部材の磁歪法による応力測定に用いると、磁歪法による応力測定結果を歪みゲージ法による応力値で検証することが出来る。
【００４３】
磁歪法による測定点を複数設けると、複数の測定点の測定値からせん断応力差積分法を用いて主応力をさらに精度良く測定ことが出来る。
【００４４】
測定板の厚さを被測定部材の応力変化に影響がない程度のものにすると、被測定部材にかかる応力のみを精度良く測定できる。
【００４５】
測定板を被測定部材に蒸着することにより形成すると、測定板の被測定部材への貼付を簡単にすることが出来る。
【図面の簡単な説明】
【図１】図２とともに本発明の第１の実施の形態を示すもので、本図は正面図である。
【図２】図１のＩＩ−ＩＩ線に沿う断面図である。
【図３】第２の実施の形態を示す正面図である。
【図４】第３の実施の形態を示す正面図である。
【図５】図６とともに本発明の第４の実施の形態を示すもので、本図は正面図である。
【図６】図５のＶＩ−ＶＩ線に沿う断面図である。
【図７】従来の応力測定方法を説明するための正面図である。
【符号の説明】
１被測定部材（コンクリート）
２測定板（鋼板）
３接着剤
４測定点
５歪みゲージ
６歪みゲージ
７ニッケル蒸着膜[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for measuring a stress of a structure, in particular, a member to be measured made of a nonmagnetic material.
[0002]
[Prior art]
Conventionally, stress measurement of a structure such as concrete is generally performed by a strain gauge method.
FIG. 7 shows such a conventional stress measurement method using a strain gauge method, in which a member to be measured is concrete and a strain gauge b is adhered to a wall surface a of the member with a waterproof adhesive c. The strain gauge b is provided with a lead wire d for connecting to a measuring device (not shown).
[0003]
When a stress is applied to the concrete a, the strain gauge b is distorted by the stress, thereby changing the resistance value. Therefore, the change in the resistance value is converted into a stress to measure the stress applied to the concrete a. Can be done.
[0004]
[Problems to be solved by the invention]
However, in the stress measurement method using the strain gauge method, the strain gauge must be attached to concrete, and since the strain gauge is easily peeled off and generally has a short life, it is not possible to monitor a change in stress over a long period of time. There was a problem that could not be done.
[0005]
[Patent Document 1]
Incidentally, for measuring the stress of a structure, when the structure is a magnetic material, a magnetostriction method as disclosed in JP-A-2003-21563 can be used. With the stress measurement method by the magnetostriction method, when a load acts on a ferromagnetic material, anisotropy occurs in the magnetic permeability, the magnetic permeability in the load direction increases, and conversely, the magnetic permeability in the direction perpendicular to the load direction decreases, This method measures the direction and magnitude of the main stress by detecting the difference between the two magnetic permeability by a magnetostrictive sensor (a detection probe of a magnetostrictive measuring device).
[0006]
However, when the member to be measured is a structure made of a nonmagnetic material, the stress measurement method by the magnetostriction method cannot be used, and the only way to measure the stress is by the strain gauge method.
[0007]
The present invention has been created to solve such a problem. That is, an object of the present invention is to provide a structure to be measured made of a non-magnetic material as a member to be measured, and to measure a stress of the structure. To provide.
[0008]
[Means for Solving the Problems]
In the method for measuring stress of a member to be measured (1) made of a nonmagnetic material according to the present invention, a measuring plate (2) made of a magnetic material is attached to the member to be measured (1), and the distortion of the measuring plate (2) is measured by magnetostriction. The stress of the member to be measured (1) is measured by converting the stress into a stress by a method.
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to measure the stress of the structure which consists of nonmagnetic materials, such as concrete, by a magnetostriction method, and it is necessary to stick the strain gauge (5) by the strain gage method to a structure like the past. Therefore, it is possible to monitor long-term stress changes.
[0009]
The stress immediately after or before the measurement plate (2) is attached to the member (1) to be measured is measured by a magnetostriction method to obtain an initial stress, and the stress of the measurement plate (2) after a change in the load of the member (1) to be measured. Is measured by the magnetostriction method, and the difference between the stress measurement result after the load change of the measurement plate (2) and the initial stress is defined as the stress of the member to be measured (1). The change in stress of the removed member (1) can be accurately measured.
[0010]
The correspondence between the stress applied to the measurement plate (2) and the output voltage of the magnetostriction measuring device in the magnetostriction method at that time is examined in advance, and based on the correspondence, the subsequent measurement of the member to be measured (1) by the magnetostriction method. When the stress is measured, the stress of the member to be measured (1) can be measured more accurately.
[0011]
A strain gauge (5) was attached to the measurement plate (2), and the relationship between the output voltage of the measurement plate (2) by the magnetostriction method and the stress value by the strain gage method using the strain gauge (5) was described below. When used for the stress measurement of the member to be measured (1) by the magnetostriction method, the result of the stress measurement by the magnetostriction method can be verified by the stress value by the strain gauge method.
[0012]
A strain gauge (6) is attached to the member (1) to be measured in the vicinity of the measuring plate (2), and an output voltage of the measuring plate (2) by a magnetostriction method and a strain gauge method using the strain gauge (6). When the relationship with the stress value obtained by the measurement is used for the subsequent measurement of the stress of the member to be measured (1) by the magnetostriction method, the stress measurement result obtained by the magnetostriction method can be verified by the stress value obtained by the strain gauge method. It is expected that a more accurate measurement result can be obtained by feeding back to the stress measurement method of the measurement plate (2) by the magnetostriction method.
[0013]
When a plurality of measurement points (4) by the magnetostriction method are provided, the principal stress can be measured with higher accuracy from the measured values of the plurality of measurement points (4) by using the shear stress difference integration method.
[0014]
When the thickness of the measurement plate (2) is set to a value that does not affect the change in the stress of the measured member (1), only the stress applied to the measured member (1) can be accurately measured.
[0015]
When the measurement plate (2) is formed by vapor deposition on the member to be measured (1), it is possible to simplify the attachment of the measurement plate (2) to the member to be measured (1).
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each of the embodiments, the present invention is applied to a concrete stress measuring method.
[0017]
1 and 2 show the first embodiment in which a steel plate 2 as a measuring plate is adhered to concrete 1 as a member to be measured, FIG. 1 is a front view, and FIG. 2 is a cross-sectional view. Show.
Although a steel plate is used as the measurement plate 2 in this embodiment, any other plate made of a magnetic material such as iron, nickel, or cobalt may be used.
[0018]
The steel plate 2 is attached to the concrete wall surface 1 with an adhesive 3. After the adhesive 3 is applied to the concrete wall surface 1 or the steel plate 2, the steel plate 2 is attached to the concrete wall surface 1 in a state where the adhesive 3 is not completely cured. It is desirable to use an adhesive 3 that has a small shrinkage upon curing. This is because stress is generated in the steel plate 2 when the adhesive 3 hardens.
[0019]
The thickness of the steel plate 2 is, for example, 0.3 mm, and when the stress is applied to the concrete 1, the thickness of the steel plate 2 does not affect the stress because the steel plate 2 is attached. In addition, it is also possible to use a somewhat thicker steel plate by analyzing in advance the degree of the effect on the stress applied to the concrete 1 by attaching the steel plate 2 to the concrete 1.
For the steel sheet 2, the relationship between the stress and the output voltage of the magnetostrictive stress measuring device (magnetization characteristics) is checked in advance.
[0020]
In order to measure a change in stress applied to the concrete 1, first, an arbitrary point on the steel plate 2 is set as a measurement point 4 (a site indicated by a black circle in the drawing; the same applies hereinafter). The output voltage is detected by applying a detection probe (magnetostrictive sensor). As shown in FIG. 1, a plurality of measurement points 4 are formed in a grid pattern. The reason why the measurement point 4 is set to a plurality of points is to separate the main stress using the shear stress difference integration method since the stress value obtained from the output voltage of the magnetostriction measuring device is the main stress difference. If the direction in which the stress acts is clear, the measurement point 4 may be one point.
[0021]
As described above, when the stress applied to the concrete 1 changes, the stress applied to the concrete 1 can be measured by measuring the stress of the steel sheet 2 using the magnetostriction measurement method for the steel sheet 2.
[0022]
Further, since a strain gauge is not used unlike the related art, it is possible to monitor a long-term stress change of a member to be measured made of a nonmagnetic material.
[0023]
Further, when the steel plate 2 is attached to the concrete 1 and the initial stress is measured by applying a detection probe (magnetostrictive sensor) of a magnetostriction measuring device to the steel plate 2, accurate stress measurement can be performed.
[0024]
That is, stress may be generated in the steel plate 2 during the manufacturing process or when attaching the steel plate 2 to the concrete wall surface. If the initial stress remains as a residual stress, there is a possibility that an error will occur in the subsequent stress measurement, and the measurement result will be inaccurate. In particular, when the steel plate 2 is affixed to the wall of the concrete 1 by bolting, stress is generated in the steel plate 2 by bolting.
[0025]
Then, after the steel plate 2 is attached to the concrete 1, the initial stress of the steel plate 2 is measured by the magnetostriction measuring method. By expressing, the stress of the concrete 1 can be measured more accurately.
[0026]
FIG. 3 shows a front view according to the second embodiment. The difference between the second embodiment and the first embodiment is that a strain gauge is attached to the steel plate 2. Therefore, in the description of the second embodiment, the same parts as those in the first embodiment will be denoted by the same reference numerals in the drawings, and description thereof will be omitted, and different parts will be mainly described.
[0027]
As shown in FIG. 3, two strain gauges 5 are attached to the steel plate 2, respectively. This strain gauge 5 can measure the stress generated in the steel plate 2.
[0028]
When the stress changes in the concrete 1, the strain gauge 5 is also distorted together with the steel sheet 2, so that the stress measurement of the steel sheet 2 by the magnetostriction measuring method and the stress measurement of the strain gauge 5 by the strain gauge method can be performed simultaneously.
[0029]
Therefore, in particular, even when the relationship (magnetization characteristics) between the stress and the output voltage of the magnetostrictive stress measuring device for the steel plate 2 is not known in advance, it is possible to accurately measure the stress of the steel plate 2 by the strain gauge method. Then, the correspondence between the output voltage of the steel sheet 2 by the magnetostriction method and the stress by the strain gauge method can be used for the subsequent stress measurement method of the steel sheet 2 by the magnetostriction method, and enables the stress measurement of the concrete 1. . In particular, this is effective when a change in stress of the concrete 1 in a short period of time can be expected. In addition, it is possible to easily measure the stress of a magnetic material whose relation between the stress and the output voltage (magnetization characteristics) of the measurement plate is not clear.
[0030]
FIG. 4 illustrates a front view according to the third embodiment. The third embodiment differs from the first embodiment in that a strain gauge is attached to the wall of concrete 1 in addition to the steel plate 2. Therefore, in the description of the third embodiment, the same parts as those in the first embodiment will be denoted by the same reference numerals in the drawings, and description thereof will be omitted, and different parts will be mainly described.
[0031]
Two strain gauges 6 are stuck on the wall surface of the concrete 1 in the vicinity of the place where the steel plate 2 is stuck.
[0032]
When the stress of the concrete 1 changes, the strain gauge 6 is distorted together with the steel sheet 2. Therefore, the stress measurement by the magnetostriction measuring method of the steel sheet 2 and the stress measurement by the strain gauge method of the strain gauge 6 can be performed simultaneously. The result of the stress measurement method by the magnetostriction method for No. 2 can be verified by the stress measurement value of the concrete 1 by the strain gauge method, and the result of the verification is fed back to the stress measurement method of the steel sheet 2 by the magnetostriction method to further improve the accuracy. Good measurement results can be expected.
[0033]
In addition, another strain gauge is attached to the steel sheet 2 according to the third embodiment, and the stress of the steel sheet 2 is measured by the strain gauge method using the strain gauge. Needless to say, it can be reflected in the stress measurement of No. 1.
[0034]
5 and 6 relate to the fourth embodiment. FIG. 5 is a front view, and FIG. 6 is a sectional view. The fourth embodiment differs from the first embodiment in that the measurement plate is not a steel plate 2 but a nickel vapor-deposited film. Therefore, in the description of the fourth embodiment, the same parts as those in the first embodiment will be denoted by the same reference numerals in the drawings, and description thereof will be omitted, and different parts will be mainly described.
[0035]
A nickel vapor deposition film 7 was formed at an arbitrary position on the wall surface of the concrete 1, and the nickel vapor deposition film 7 was used as a measurement plate.
Then, a plurality of measurement points 4 are formed at arbitrary points on the nickel vapor-deposited film 7 by the magnetostriction method.
[0036]
As described above, when there is a stress change in the concrete 1, the nickel vapor deposition film 7 is distorted. Therefore, the stress change of the concrete 1 can be measured by measuring the stress by the magnetostriction measuring method.
Further, in the fourth embodiment, the measurement plate is a vapor deposition film, but the present invention is not limited to this, and a magnetic material may be applied.
[0037]
In each of the above embodiments, the member to be measured is concrete, but the present invention is not limited to this, and any member made of non-magnetic material such as plastic may be used.
[0038]
【The invention's effect】
As described above, the method for measuring the stress of a member to be measured made of a non-magnetic material according to the present invention is a method of measuring the stress of a member to be measured made of a non-magnetic material. It is characterized in that it is attached to a measuring member, and the distortion of the measuring plate is converted into a stress by a magnetostriction method to measure the stress of the member to be measured.
According to the present invention, it is possible to measure the stress of a structure made of a nonmagnetic material such as concrete by a magnetostriction method, and it is not necessary to attach a strain gauge to a structure by a strain gauge method as in the related art. Long-term stress changes can be monitored.
[0039]
The stress immediately after or before the measurement plate is attached to the member to be measured is measured by magnetostriction as an initial stress, and the stress of the measurement plate after the change in the load of the member to be measured is measured by magnetostriction. When the difference between the stress measurement result after the load change and the initial stress is defined as the stress of the measured member, the change in stress of the measured member excluding the initial stress of the measurement plate can be accurately measured.
[0040]
The correspondence between the stress applied to the measurement plate and the output voltage of the magnetostriction measuring device in the magnetostriction method at that time is checked, and the stress measurement of the member to be measured is performed based on the correspondence according to the magnetostriction method. Then, the stress of the member to be measured can be measured with higher accuracy.
[0041]
A strain gauge is attached to the measurement plate, and the relationship between the output voltage of the measurement plate by the magnetostriction method and the stress value by the strain gauge method using the strain gauge is used for the subsequent measurement of the stress of the member to be measured by the magnetostriction method. The stress measurement result by the magnetostriction method can be verified by the stress value by the strain gauge method, and it is expected that a more accurate measurement result can be obtained by feeding back the verification result to the stress measurement method of the steel sheet by the magnetostriction method. .
[0042]
A strain gauge is attached to the member to be measured in the vicinity of the measurement plate, and the relationship between the output voltage of the measurement plate by the magnetostriction method and the stress value by the strain gauge method using the strain gauge is determined by the magnetostriction When used for stress measurement by the method, the result of stress measurement by the magnetostriction method can be verified by the stress value by the strain gauge method.
[0043]
When a plurality of measurement points by the magnetostriction method are provided, the principal stress can be measured with higher accuracy by using the shear stress difference integration method from the measured values of the plurality of measurement points.
[0044]
When the thickness of the measuring plate is set to such an extent that the change in stress of the member to be measured is not affected, only the stress applied to the member to be measured can be accurately measured.
[0045]
When the measurement plate is formed by vapor deposition on the member to be measured, the measurement plate can be easily attached to the member to be measured.
[Brief description of the drawings]
1 shows a first embodiment of the present invention together with FIG. 2, and FIG. 1 is a front view.
FIG. 2 is a sectional view taken along the line II-II in FIG.
FIG. 3 is a front view showing a second embodiment.
FIG. 4 is a front view showing a third embodiment.
FIG. 5 shows a fourth embodiment of the present invention together with FIG. 6, which is a front view.
FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5;
FIG. 7 is a front view for explaining a conventional stress measuring method.
[Explanation of symbols]
1 member to be measured (concrete)
2 Measurement plate (steel plate)
3 Adhesive 4 Measurement point 5 Strain gauge 6 Strain gauge 7 Nickel deposited film

Claims

A method for measuring stress of a member to be measured (1) made of a nonmagnetic material,
A measurement plate (2) made of a magnetic material is attached to the member to be measured (1),
A method for measuring the stress of a member to be measured made of a nonmagnetic material, wherein the stress of the member to be measured (1) is measured by converting the strain of the measurement plate (2) into a stress by a magnetostriction method.

Immediately after or before applying the measuring plate (2) to the member (1) to be measured, a stress is measured by a magnetostriction method to obtain an initial stress,
The stress of the measurement plate (2) after the load change of the member to be measured (1) is measured by the magnetostriction method, and the difference between the stress measurement result after the load change of the measurement plate (2) and the above initial stress is measured. The method according to claim 1, wherein the stress of the member (1) is the stress of the member (1).

The correspondence between the stress applied to the measurement plate (2) and the output voltage of the magnetostriction measuring device in the magnetostriction method at that time was previously checked,
3. The member to be measured made of a non-magnetic material according to claim 1 or 2, wherein the subsequent measurement of the member to be measured (1) by the magnetostriction method is performed based on the correspondence. Stress measurement method.

Attach the strain gauge (5) to the measuring plate (2),
The relationship between the output voltage of the measurement plate (2) by the magnetostriction method and the stress value by the strain gauge method using the strain gauge (5) was used for the subsequent stress measurement of the member to be measured (1) by the magnetostriction method. 4. The method for measuring stress of a member to be measured made of a nonmagnetic material according to claim 1, wherein the stress is measured.

A strain gauge (6) is attached to the member to be measured (1) in the vicinity of the measurement plate (2), and an output voltage of the measurement plate (2) by a magnetostriction method and a strain gauge method using the strain gauge (6). 5. The method according to claim 1, wherein the relationship with the stress value according to (1) is used for a subsequent stress measurement of the member to be measured (1) by the magnetostriction method. A method for measuring stress of a member to be measured made of a magnetic material.

The stress of a member to be measured made of a non-magnetic material according to claim 1, wherein a plurality of measurement points (4) are provided by a magnetostriction method. Measuring method.

The thickness of the measuring plate (2) is set so as not to affect the change in stress of the member to be measured (1). A method for measuring a stress of a member to be measured, comprising the nonmagnetic material according to claim 5 or 6.

The measuring plate (2) is formed by vapor deposition on the member to be measured (1), wherein the measuring plate (2) is formed by vapor deposition. Item 8. A method for measuring a stress of a member to be measured made of a nonmagnetic material according to Item 7.