JP4261080B2 - Residual stress measurement method - Google Patents

Residual stress measurement method Download PDF

Info

Publication number
JP4261080B2
JP4261080B2 JP2001102157A JP2001102157A JP4261080B2 JP 4261080 B2 JP4261080 B2 JP 4261080B2 JP 2001102157 A JP2001102157 A JP 2001102157A JP 2001102157 A JP2001102157 A JP 2001102157A JP 4261080 B2 JP4261080 B2 JP 4261080B2
Authority
JP
Japan
Prior art keywords
indentation
measured
residual stress
stress
shape
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
Application number
JP2001102157A
Other languages
Japanese (ja)
Other versions
JP2002296125A (en
Inventor
雅雄 板谷
徳彦 田中
政之 淺野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toshiba Corp
Original Assignee
Toshiba Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Toshiba Corp filed Critical Toshiba Corp
Priority to JP2001102157A priority Critical patent/JP4261080B2/en
Publication of JP2002296125A publication Critical patent/JP2002296125A/en
Application granted granted Critical
Publication of JP4261080B2 publication Critical patent/JP4261080B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Landscapes

  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、被測定体を破壊することなく、被測定体に存在する残留応力を精密に測定できる残留応力測定方法に関する。
【０００２】
【従来の技術】
各種構造体に適用される材料の寿命を判断するために、材料の疲労強度や疲労・応力腐食割れによるき裂進展寿命の推定が行われている。材料の表面・内部に存在する残留応力は、材料の疲労強度に影響を与え、また、疲労・応力腐食割れによるき裂進展寿命に多大な影響を与える。従って、材料寿命を精度良く推定するため、材料の表面・内部の残留応力を正確に測定することが、重要な技術課題となっている。
【０００３】
近年、材料の残留応力を測定するために、切断解放法が適用されている。
【０００４】
切断開放法は、被測定体の対象部位に貼付したひずみゲージの周囲を、ひずみゲージとともに小片として切り出し、解放されるひずみから残留応力を計算により求める方法である。
【０００５】
切断解放法による残留応力測定は、ひずみゲージの周囲を切断するため、被測定体を破壊して測定する破壊的な測定方法であった。このため、被測定体の残留応力の測定後は再使用できず、実機そのものに切断開放法を適用することは困難であった。
【０００６】
一方、被測定体の残留応力を測定する際、被測定体を破壊することなく、非破壊的に被測定体の残留応力を測定する方法として、例えば、Ｘ線回折法が挙げられる。
【０００７】
Ｘ線回折法は、被測定体の結晶の格子面間隔をゲージ長さに設定し、これを背面反射Ｘ線回折で精密に測定してひずみを求め、弾性論により応力に変換し、残留応力を求める方法である。
【０００８】
【発明が解決しようとする課題】
しかしながら、上記Ｘ線回折法では、材料の結晶組織の状態、例えば、被測定体の結晶粒径や結晶配向の影響を受け、残力応力の測定値にばらつきが生じ、被測定体の残留応力を精密測定することができないという問題を有していた。
【０００９】
従って、被測定体を破壊せず、かつ、被測定体の残留応力を精密測定することが課題となっていた。
【００１０】
本発明は、上記課題を解決するためになされたものであり、被測定体表面の残留応力を精度良く測定でき、かつ、半非破壊的に被測定体の残留応力を測定できる残留応力測定方法を提供することを目的とする。
【００１１】
【課題を解決するための手段】
本発明者らは、上記目的を達成すべく種々研究した結果、構造物表面に圧痕を付与した際に残留応力が存在する場合と残留応力が存在しない場合とで圧痕形状の方向および変化量の差異があり、この差異に基づき被測定体の残留応力を測定できることを見出し、本発明を完成させたものである。
【００１２】
すなわち、本発明は、被測定体表面の残留応力を非破壊的に測定する残留応力測定方法であって、予め前記被測定体と同種材料に対する一定断面の圧子による基準圧痕の形状を残留応力の無い状態下で実験的または解析により求めるとともに、当該材料に対応する応力の影響による前記圧痕形状の変形度合を方向的および寸法的に求めておき、実際の測定に際し、残留応力のある前記被測定体の表面に前記圧子と同一圧子を用いて同一条件で圧痕を形成し、その際に形成された実圧痕の形状と前記基準圧痕の形状とを比較し、その両形状の方向的および寸法的な差異に基づいて、前記基準圧痕の変形から求めておいた応力の値を用いて前記被測定体の残留応力を求めることを特徴とする。
【００１３】
本発明では、圧痕の深さをごく浅い形状としたため、被測定体の残留応力を測定した後、圧痕を研削等により除去して再使用可能なため、実機に適用できる。このため、被測定体を破壊することなく被測定体の残留応力を精密に測定することができる。
【００１４】
ここで、残留応力がない状態の基準測定体の圧痕形状は実験的に求めても良く、有限要素法（以下、ＦＥＭとする）等の解析的手法により求めても良い。
【００１５】
なお、圧痕を形成するための圧子形状は、球状、円錐形状、楔形形状などのいずれの形状としても良い。
【００１６】
また、上記残留応力測定方法において、前記基準圧痕の形状および寸法値と負荷した応力との関係をデータベースとして記憶手段に格納し、前記被測定体表面に形成した圧痕の方向的および寸法的な測定値を用いて、前記データベースから前記被測定体の残留応力を計算システムにより求めることを特徴とする。
【００１７】
本発明によれば、予め基準測定体の圧痕の単軸方向に負荷した応力と、単軸応力負荷により形成された圧痕寸法との関係をデータベースとして記憶手段に格納しておき、被測定体の圧痕寸法を測定することにより、測定値に用いてデータベースを参照することにより、即時に被測定体の残留応力を算出できる。
【００１８】
上記残留応力測定方法において、前記被測定体に対する圧痕の形成時の荷重または押し込み深さは、基準圧痕形成時における圧子の押し付け荷重または押し込み深さと同一とすることを特徴とする。
【００１９】
また、上記残留応力測定方法において、前記被測定体の圧痕寸法を測定した後に、前記被測定体の圧痕形成分を除去することを特徴とする。
【００２０】
本発明によれば、被測定体に形成された圧痕を除去することにより、圧痕からの割れ発生等を防止できる。また、圧痕の除去方法は、グラインダー等による研削または紙やすり等による研磨としても良い。
【００２１】
さらに、上記残留応力測定方法において、被測定体の表面に圧痕を形成し、この被測定体表面の２軸方向における圧痕寸法を測定する工程と、前記被測定体と同質の材料から形成し残留応力が存在しない基準測定体について予め実験的または解析的に１軸以上の方向から単位応力を負荷した場合について圧痕の２軸方向における圧痕寸法を求めておく工程と、前記基準測定体の単位応力を負荷した際の圧痕形状を前記基準測定体表面の２軸方向をそれぞれ表す変数で定式化し、この圧痕形状を示す式に乗じることにより前記被測定体の圧痕寸法となる数値を算出し、前記被測定体の残留応力を求める工程と、を有することを特徴とする。
【００２２】
【発明の実施の形態】
以下、本発明に係る残留応力測定方法について、図１〜図６を用いて説明する。
【００２３】
被測定体の残留応力測定方法の手順を示す。
【００２４】
まず、図１に示す球状の圧子１を用いて、基準測定体表面に圧痕を形成した。図１に示す（ａ）は球状圧子１の側面図、（ｂ）は球状圧子１の平面図である。なお、基準測定体は、後述する被測定体と同一成分の材料から形成したものであり、残留応力が存在しない材料とした。
【００２５】
図２は、基準測定体２に形成された圧痕形状を示す図であり、（ａ）は、ｘ方向に単位引張応力を負荷した際の圧痕３の形状を示す平面図、（ｂ）はその断面図である。また、（ｃ）はｙ方向に単位引張応力を負荷した際の圧痕４の形状を示す平面図、（ｄ）はその断面図を示す。
【００２６】
図２（ａ）〜図２（ｄ）に示すように、ｘ方向またはｙ方向に単位引張応力を各々負荷して形成された圧痕３，４の形状を測定した。なお、圧痕形状は実験的に求めても良いし、ＦＥＭ等の解析的手法により求めても良い。
【００２７】
各圧痕３，４の形状を測定した結果、ｘ方向に単位引張応力を負荷した際における応力負荷方向における圧痕形状をｕ（ｘ，ｙ）とし、ｙ方向に単位引張応力を負荷したときの圧痕形状をｖ（ｘ，ｙ）とした。
【００２８】
次に、上記球状圧子１を用いて、被測定体である構造物の表面に圧痕を形成した。なお、被測定体への圧痕形成は、上記基準測定体と同一の押し込み荷重を負荷して圧痕形成したものである。これを図３に示す。
【００２９】
図３に示す（ａ）は圧痕５を形成した構造物６の平面図であり、（ｂ）は構造物６の断面図を示す。図３（ａ）に示すように、構造物６の表面方向をｘ方向、ｙ方向とし、図３（ｂ）に示すように圧痕５の深さ方向をｚ方向とした。この圧痕５形状を接触式または非接触式のいずれかの形状測定装置を用いて測定した。具体的には、接触式の形状測定は触針式の三次元形状測定器を用い、非接触式の形状測定はレーザ三次元形状測定器などを用いた。そして、測定した圧痕５の形状をｚ（ｘ，ｙ）とした。
【００３０】
上記方法により得られたｚ（ｘ，ｙ），ｕ（ｘ，ｙ），ｖ（ｘ，ｙ）の測定値から、以下に示す式１の関係式を満たすｋおよびｈを、最小自乗法を用いて算出した。なお、ｋは圧痕のｘ方向の残留応力であり、ｈは圧痕のｙ方向の残留応力である。
【００３１】
【数１】

Figure 0004261080
【００３２】
このようにして上記式１に基づきｋ，ｈを算出することにより、ｘ方向およびｙ方向の各残留応力を求めることができる。
【００３３】
さらに、基準測定体に形成した圧痕に単位せん断応力を負荷して圧痕を形成し、この圧痕形状を測定してｗ（ｘ，ｙ）として示した。
【００３４】
上述したｚ（ｘ，ｙ），ｕ（ｘ，ｙ），ｖ（ｘ，ｙ）の測定値と、ｗ（ｘ，ｙ）の測定値に基づき、以下に示す式２の関係式を満たすようなｋ，ｈ，ｍについて、最小自乗法を用いて算出した。なお、ｋは圧痕のｘ方向の残留応力σｘ，ｈは圧痕のｙ方向の残留応力σｙ，ｍはせん断応力τｘｙを示す。
【００３５】
【数２】
Figure 0004261080
【００３６】
上記式２に基づきｋ，ｈ，ｍを算出することにより、ｘ方向およびｙ方向の各残留応力およびせん断応力を求めることができる。さらに、ｋ，ｈ，ｍの各値によりモールの応力円を用いて残留応力の最大値、すなわち、主応力とその方向を計算することができる。
【００３７】
なお、上述した被測定体の残留応力測定方法の手順では、球状圧子１を用いたが、圧子は、図４に示す円錐状の圧子７を適用しても良い。図４の（ａ）は圧子の側面図であり、（ｂ）は圧子の平面図である。
【００３８】
図４に示す円錐状の圧子７を用いた場合には、基準測定体に圧痕形成すると、軸対称形状の圧痕とすることができる。このため、ｙ方向に単位引張応力を負荷した際の圧痕形状は、ｘ方向に単位引張応力を負荷した際の圧痕形状を９０゜回転させたものと同一となる。従って、ｘ方向に単位引張応力を負荷した試験を行い、圧痕形状を解析するだけで良く、ｙ方向に単位引張応力を負荷した試験・解析を省略できる。
【００３９】
さらに、楔形形状とした圧子を用いて、被測定体の残留応力測定方法を以下に示す。
【００４０】
図５は、楔形形状の圧子８を示す図である。楔形形状の圧子８を適用した場合には、残留応力存在下における圧痕９の形状変化は、図５に示すＡ方向の応力成分の影響を最も強く受ける。このため、図５に示す応力成分、すなわち、上述した式１に示すｘ方向またはｙ方向のいずれか（なお、ここではｘ方向をＡ方向とみなして測定した。）に単位引張応力を負荷した際の圧痕形状を測定し、下記に示す式３に基づきｋを算出することにより、ｘ方向、すなわち、Ａ方向の残留応力を求めることができる。
【００４１】
【数３】
ｚ（ｘ，ｙ）＝ｋ・ｕ（ｘ，ｙ） ……（式３）
【００４２】
この楔形形状の圧子８を使用して形成された圧痕に応力を負荷した後の中央開口量δと、Ａ方向の残留応力との関係を各種測定し、これをデータベース化し、圧痕の中央開口量δからＡ方向の残留応力を測定することもできる。これを図６に示す。
【００４３】
まず、図６（ａ）に示すように、基準測定体２に楔形形状の圧子８を用いて圧痕９を形成し、この圧痕９の単軸方向に応力σを負荷した。次に、図６（ｂ）に示すように、圧痕の中央開口量δを測定した。さらに、基準測定体２の単軸方向に負荷する応力σの大きさを種々変えて、圧痕の中央開口量δをそれぞれ測定した。その後、図６（ｃ）に示すように、基準測定体２の単軸方向に負荷する応力σを横軸とし、圧痕の中央開口量δを縦軸にとり、両者の相関関係を示し、これをデータベース化し、記憶手段に格納した。
【００４４】
その後、被測定体である構造物６表面に楔形形状の圧子８により圧痕を形成し、圧痕の中央開口量δを測定した。そして、この測定値δから上記データベースに基づき応力を算出し、構造物６表面に付与された楔形のＡ方向の残留応力を測定した。
【００４５】
なお、上記応力測定方法において、被測定体および基準測定体に同一押し付け荷重を負荷して圧痕形成をした場合には、圧痕中央の開口量δは残留応力による変形のし易さを示す。また、被測定体および基準測定体に同一押し込み深さにより圧痕形成をした場合には、圧痕中央の開口量δは除荷時の弾性変形、すなわち、残留応力によるスプリングバック量を示すことになる。本実施形態においては、同一押し付け荷重を負荷するか、あるいは、同一押し込み深さにより圧痕形成をしても、いずれの方法を用いても良い。
【００４６】
本実施形態によれば、被測定体表面の残留応力を精度良く測定でき、かつ、残留応力測定により被測定体表面に形成する圧痕を微小とし、この圧痕を研削等により容易に除去できるため、半破壊的に被測定体の残留応力を測定でき、構造物の運用に支障をきたすことなく残留応力の測定後においても被測定体を再使用できる。
【００４７】
【発明の効果】
以上説明したように、本発明に係る残留応力測定方法によれば、構造物の表面に微小な圧痕を付与するのみで半非破壊的に残留応力の測定が可能となり、実構造物に適用可能である。
【図面の簡単な説明】
【図１】本発明の実施形態における、球状の圧子を示す図。
【図２】本発明の実施形態における、基準測定体に圧痕形成した基準測定体を示す図。
【図３】本発明の実施形態を説明する図。
【図４】本発明の実施形態における、円錐状の圧子を示す図。
【図５】本発明の実施形態における、楔形の圧子を示す図。
【図６】本発明の実施形態における、残留応力と圧痕形状との関係をデータベース化する手順図。
【符号の説明】
１…球状圧子，２…基準測定体，３…ｘ方向に単位引張応力を負荷した際の圧痕，４…ｙ方向に単位引張応力を負荷した際の圧痕，５…圧痕，６…構造物，７…円錐状の圧子，８…楔形形状の圧子，９…圧痕。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a residual stress measurement method capable of accurately measuring a residual stress existing in a measurement object without destroying the measurement object.
[0002]
[Prior art]
In order to determine the life of materials applied to various structures, the fatigue strength of materials and the crack growth life due to fatigue / stress corrosion cracking are estimated. Residual stress existing on the surface / inside of the material affects the fatigue strength of the material, and greatly affects the crack growth life due to fatigue / stress corrosion cracking. Therefore, in order to estimate the material life with high accuracy, it is an important technical problem to accurately measure the residual stress on the surface and inside of the material.
[0003]
In recent years, the cutting release method has been applied to measure the residual stress of materials.
[0004]
The cutting and opening method is a method of cutting out the periphery of a strain gauge attached to a target site of a measurement object as a small piece together with the strain gauge, and calculating residual stress from the released strain by calculation.
[0005]
The residual stress measurement by the cutting and releasing method is a destructive measurement method in which a measurement object is broken and measured in order to cut the periphery of the strain gauge. For this reason, it cannot be reused after the measurement of the residual stress of the object to be measured, and it is difficult to apply the cutting open method to the actual machine itself.
[0006]
On the other hand, when measuring the residual stress of the measured object, an example of a method for measuring the residual stress of the measured object nondestructively without destroying the measured object is an X-ray diffraction method.
[0007]
In the X-ray diffraction method, the lattice spacing of the crystal of the object to be measured is set to the gauge length, this is precisely measured by back reflection X-ray diffraction to obtain strain, converted into stress by elasticity, and the residual stress It is a method to ask for.
[0008]
[Problems to be solved by the invention]
However, in the above X-ray diffraction method, the measured value of the residual stress varies depending on the state of the crystal structure of the material, for example, the crystal grain size and crystal orientation of the measured object, and the residual stress of the measured object Has a problem that it cannot be measured accurately.
[0009]
Accordingly, it has been a problem to accurately measure the residual stress of the measurement object without destroying the measurement object.
[0010]
The present invention has been made to solve the above-described problems, and is capable of accurately measuring the residual stress on the surface of the object to be measured and capable of measuring the residual stress of the object to be measured in a non-destructive manner. The purpose is to provide.
[0011]
[Means for Solving the Problems]
As a result of various studies to achieve the above object, the present inventors have found that the direction of the indentation shape and the amount of change in the presence of residual stress and the absence of residual stress when indentation is applied to the structure surface. The present invention has been completed by finding that there is a difference, and that the residual stress of the object to be measured can be measured based on this difference.
[0012]
That is, the present invention is a residual stress measurement method that non-destructively measures the residual stress on the surface of the object to be measured. Obtained by experiment or analysis under no conditions, and obtained the degree of deformation of the indentation shape due to the influence of the stress corresponding to the material in a directional and dimensional manner. Using the same indenter and the same indenter on the surface of the body, form an indentation under the same conditions, compare the shape of the actual indentation formed at that time with the shape of the reference indentation, and the direction and dimension of both shapes Based on the difference, the residual stress of the object to be measured is obtained using the stress value obtained from the deformation of the reference indentation.
[0013]
In the present invention, since the depth of the indentation is a very shallow shape, the indentation can be removed by grinding or the like after measuring the residual stress of the object to be measured, and thus can be applied to an actual machine. For this reason, the residual stress of the measured object can be measured accurately without destroying the measured object.
[0014]
Here, the indentation shape of the reference measurement body in the absence of residual stress may be obtained experimentally or by an analytical method such as a finite element method (hereinafter referred to as FEM).
[0015]
The indenter shape for forming the indentation may be any shape such as a spherical shape, a conical shape, or a wedge shape.
[0016]
Further, in the residual stress measurement method, the relationship between the shape and dimension value of the reference indentation and the applied stress is stored in a storage means as a database, and the directional and dimensional measurement of the indentation formed on the surface of the object to be measured is performed. Using the value, the residual stress of the measured object is obtained from the database by a calculation system.
[0017]
According to the present invention, the relationship between the stress applied in the uniaxial direction of the indentation of the reference measurement body and the indentation dimension formed by the uniaxial stress load is stored in the storage means as a database, and the measurement object By measuring the indentation size, the residual stress of the measured object can be immediately calculated by referring to the database using the measured value.
[0018]
In the residual stress measurement method, a load or an indentation depth when forming an indentation on the object to be measured is the same as an indenter pressing load or an indentation depth when forming a reference indentation.
[0019]
In the residual stress measuring method, the indented portion of the measured object is removed after measuring the indented dimension of the measured object.
[0020]
According to the present invention, it is possible to prevent the occurrence of cracks from the indentation by removing the indentation formed on the measurement object. The method for removing the indentation may be grinding by a grinder or polishing by sandpaper.
[0021]
Further, in the residual stress measurement method, a step of forming an indentation on the surface of the object to be measured and measuring an indentation dimension in the biaxial direction of the surface of the object to be measured; a residual material formed from the same material as the object to be measured a step of previously obtained an impression dimensions in the two axial directions of the indentation for the case where stress is loaded in advance experimentally or analytically unit stress from uniaxial or more directions for the reference measurement member does not exist, the unit stress of the reference measurement member The indentation shape when loaded is formulated with variables each representing the biaxial direction of the surface of the reference measurement body, and a numerical value that becomes the indentation dimension of the object to be measured is calculated by multiplying the expression indicating the indentation shape , And obtaining a residual stress of the object to be measured.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the residual stress measurement method according to the present invention will be described with reference to FIGS.
[0023]
The procedure of the method for measuring the residual stress of the object to be measured will be described.
[0024]
First, an indentation was formed on the surface of the reference measurement body using the spherical indenter 1 shown in FIG. 1A is a side view of the spherical indenter 1, and FIG. 1B is a plan view of the spherical indenter 1. Note that the reference measurement body was formed from a material having the same component as that of the measurement target to be described later, and was a material having no residual stress.
[0025]
2A and 2B are diagrams showing the shape of the indentation formed on the reference measurement body 2. FIG. 2A is a plan view showing the shape of the indentation 3 when a unit tensile stress is applied in the x direction, and FIG. It is sectional drawing. Further, (c) is a plan view showing the shape of the indentation 4 when a unit tensile stress is applied in the y direction, and (d) is a cross-sectional view thereof.
[0026]
As shown in FIGS. 2A to 2D, the shapes of the indentations 3 and 4 formed by applying a unit tensile stress in the x direction or the y direction were measured. The indentation shape may be obtained experimentally or by an analytical method such as FEM.
[0027]
As a result of measuring the shape of each indentation 3, 4, the indentation shape in the stress load direction when a unit tensile stress is applied in the x direction is u (x, y), and the indentation when the unit tensile stress is applied in the y direction The shape was v (x, y).
[0028]
Next, using the spherical indenter 1, indentations were formed on the surface of the structure which is a measurement object. Indentation formation on the object to be measured is formed by applying the same indentation load as that of the reference measurement object. This is shown in FIG.
[0029]
3A is a plan view of the structure 6 in which the indentation 5 is formed, and FIG. 3B is a cross-sectional view of the structure 6. As shown in FIG. 3A, the surface direction of the structure 6 was set to the x direction and the y direction, and the depth direction of the indentation 5 was set to the z direction as shown in FIG. The shape of the indentation 5 was measured using either a contact type or non-contact type shape measuring device. Specifically, a stylus type three-dimensional shape measuring instrument was used for contact-type shape measurement, and a laser three-dimensional shape measuring instrument was used for non-contact type shape measurement. And the shape of the measured indentation 5 was set to z (x, y).
[0030]
From the measured values of z (x, y), u (x, y), and v (x, y) obtained by the above method, k and h satisfying the relational expression of the following expression 1 are expressed by the least square method. Used to calculate. Here, k is the residual stress in the x direction of the indentation, and h is the residual stress in the y direction of the indentation.
[0031]
[Expression 1]
Figure 0004261080
[0032]
In this way, by calculating k and h based on the above equation 1, each residual stress in the x direction and the y direction can be obtained.
[0033]
Furthermore, a unit shear stress was applied to the indentation formed on the reference measurement body to form an indentation, and the indentation shape was measured and indicated as w (x, y).
[0034]
Based on the measured values of z (x, y), u (x, y), v (x, y) and the measured value of w (x, y) described above, the following relational expression 2 is satisfied. K, h, and m were calculated using the method of least squares. Here, k is the residual stress σ x in the x direction of the indentation, h is the residual stress σ y in the y direction of the indentation, and m is the shear stress τ xy .
[0035]
[Expression 2]
Figure 0004261080
[0036]
By calculating k, h, and m based on the above equation 2, each residual stress and shear stress in the x and y directions can be obtained. Furthermore, the maximum value of the residual stress, that is, the principal stress and its direction can be calculated using the Mole's stress circle based on the values of k, h, and m.
[0037]
Although the spherical indenter 1 is used in the procedure of the method for measuring the residual stress of the measurement object described above, the conical indenter 7 shown in FIG. 4 may be applied as the indenter. 4A is a side view of the indenter, and FIG. 4B is a plan view of the indenter.
[0038]
When the conical indenter 7 shown in FIG. 4 is used, if an indentation is formed on the reference measurement body, an indentation having an axially symmetric shape can be obtained. Therefore, the indentation shape when the unit tensile stress is applied in the y direction is the same as the indentation shape obtained by rotating the indentation shape by 90 ° when the unit tensile stress is applied in the x direction. Therefore, it is only necessary to perform a test with a unit tensile stress applied in the x direction and analyze the indentation shape, and the test / analysis with a unit tensile stress applied in the y direction can be omitted.
[0039]
Furthermore, a method for measuring the residual stress of the measurement object using a wedge-shaped indenter will be described below.
[0040]
FIG. 5 shows a wedge-shaped indenter 8. When the wedge-shaped indenter 8 is applied, the shape change of the indentation 9 in the presence of residual stress is most strongly affected by the stress component in the A direction shown in FIG. Therefore, a unit tensile stress was applied to the stress component shown in FIG. 5, that is, either the x direction or the y direction shown in the above-described equation 1 (measured by regarding the x direction as the A direction). The residual stress in the x direction, that is, the A direction can be obtained by measuring the shape of the indentation and calculating k based on Equation 3 shown below.
[0041]
[Equation 3]
z (x, y) = k · u (x, y) (Formula 3)
[0042]
Various measurements were made of the relationship between the center opening δ after applying stress to the indentation formed using the wedge-shaped indenter 8 and the residual stress in the A direction, and this was databased to obtain the center opening of the indentation. The residual stress in the A direction can also be measured from δ. This is shown in FIG.
[0043]
First, as shown in FIG. 6A, an indentation 9 was formed on the reference measurement body 2 using a wedge-shaped indenter 8, and a stress σ was applied in the uniaxial direction of the indentation 9. Next, as shown in FIG. 6B, the central opening δ of the indentation was measured. Further, the central opening δ of the indentation was measured by changing the magnitude of the stress σ applied in the uniaxial direction of the reference measurement body 2 in various ways. Thereafter, as shown in FIG. 6 (c), the stress σ applied in the uniaxial direction of the reference measurement body 2 is taken as the horizontal axis, the central opening δ of the indentation is taken as the vertical axis, and the correlation between the two is shown. A database was created and stored in storage means.
[0044]
Thereafter, an indentation was formed on the surface of the structure 6 to be measured by a wedge-shaped indenter 8, and the central opening δ of the indentation was measured. The stress was calculated from the measured value δ based on the database, and the wedge-shaped residual stress in the A direction applied to the surface of the structure 6 was measured.
[0045]
In the above stress measurement method, when the indentation is formed by applying the same pressing load to the object to be measured and the reference measurement body, the opening amount δ at the center of the indentation indicates the ease of deformation due to the residual stress. Further, when an indentation is formed on the object to be measured and the reference measurement body with the same indentation depth, the opening amount δ at the center of the indentation indicates an elastic deformation at the time of unloading, that is, a springback amount due to residual stress. . In the present embodiment, either method may be used, whether the same pressing load is applied or the indentation is formed with the same pressing depth.
[0046]
According to the present embodiment, the residual stress on the surface of the object to be measured can be accurately measured, and the indentation formed on the surface of the object to be measured by the residual stress measurement is minute, and the indentation can be easily removed by grinding or the like. The residual stress of the object to be measured can be measured semi-destructively, and the object to be measured can be reused even after the measurement of the residual stress without affecting the operation of the structure.
[0047]
【The invention's effect】
As described above, according to the method for measuring residual stress according to the present invention, it is possible to measure the residual stress semi-destructively only by giving a minute indentation to the surface of the structure, and it can be applied to an actual structure. It is.
[Brief description of the drawings]
FIG. 1 is a view showing a spherical indenter in an embodiment of the present invention.
FIG. 2 is a diagram showing a reference measurement body in which an indentation is formed on the reference measurement body in the embodiment of the present invention.
FIG. 3 is a diagram illustrating an embodiment of the present invention.
FIG. 4 is a diagram showing a conical indenter in the embodiment of the present invention.
FIG. 5 is a view showing a wedge-shaped indenter according to the embodiment of the present invention.
FIG. 6 is a procedure diagram for creating a database of the relationship between residual stress and indentation shape in the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Spherical indenter, 2 ... Reference | standard measuring body, 3 ... Impression when unit tensile stress is loaded to x direction, 4 ... Indentation when unit tensile stress is loaded to y direction, 5 ... Indentation, 6 ... Structure 7 ... Conical indenter, 8 ... Wedge-shaped indenter, 9 ... Indentation.

Claims (5)

被測定体表面の残留応力を非破壊的に測定する残留応力測定方法であって、予め前記被測定体と同種材料に対する一定断面の圧子による基準圧痕の形状を残留応力の無い状態下で実験的または解析により求めるとともに、当該材料に対応する応力の影響による前記圧痕形状の変形度合を方向的および寸法的に求めておき、実際の測定に際し、残留応力のある前記被測定体の表面に前記圧子と同一圧子を用いて同一条件で圧痕を形成し、その際に形成された実圧痕の形状と前記基準圧痕の形状とを比較し、その両形状の方向的および寸法的な差異に基づいて、前記基準圧痕の変形から求めておいた応力の値を用いて前記被測定体の残留応力を求めることを特徴とする残留応力測定方法。  This is a residual stress measurement method for nondestructively measuring the residual stress on the surface of the object to be measured, in which the shape of the reference indentation by the indenter having a constant cross section for the same kind of material as that of the object to be measured is experimentally tested in the absence of residual stress. Alternatively, it is obtained by analysis, and the degree of deformation of the indentation shape due to the influence of stress corresponding to the material is obtained directionally and dimensionally, and the indenter is applied to the surface of the measured object having residual stress in actual measurement. Using the same indenter to form an indentation under the same conditions, comparing the shape of the actual indentation formed at that time and the shape of the reference indentation, based on the directional and dimensional differences between the two shapes, A residual stress measuring method, wherein a residual stress of the object to be measured is obtained using a stress value obtained from deformation of the reference indentation. 請求項１記載の残留応力測定方法において、前記基準圧痕の形状および寸法値と負荷した応力との関係をデータベースとして記憶手段に格納し、前記被測定体表面に形成した圧痕の方向的および寸法的な測定値を用いて、前記データベースから前記被測定体の残留応力を計算システムにより求めることを特徴とする残留応力測定方法。  2. The residual stress measurement method according to claim 1, wherein the relationship between the shape and dimension value of the reference indentation and the applied stress is stored in a storage means as a database, and the directionality and dimension of the indentation formed on the surface of the object to be measured are measured. A residual stress measuring method, wherein a residual stress of the object to be measured is obtained from the database by a calculation system using a measured value. 請求項１または２記載の残留応力測定方法において、前記被測定体に対する圧痕の形成時の荷重または押し込み深さは、基準圧痕形成時における圧子の押し付け荷重または押し込み深さと同一とすることを特徴とする残留応力測定方法。  The residual stress measurement method according to claim 1 or 2, wherein a load or an indentation depth at the time of forming an indentation to the object to be measured is the same as an indentation pressing load or an indentation depth at the time of formation of a reference indentation. To measure residual stress. 請求項１から３までのいずれかに記載の残留応力測定方法において、前記被測定体の圧痕寸法を測定した後に、前記被測定体の圧痕形成分を除去することを特徴とする残留応力測定方法。  4. The residual stress measurement method according to claim 1, wherein after the indentation dimension of the object to be measured is measured, the indentation of the object to be measured is removed. . 被測定体の表面に圧痕を形成し、この被測定体表面の２軸方向における圧痕寸法を測定する工程と、前記被測定体と同質の材料から形成し残留応力が存在しない基準測定体について予め実験的または解析的に１軸以上の方向から単位応力を負荷した場合について圧痕の２軸方向における圧痕寸法を求めておく工程と、前記基準測定体の単位応力を負荷した際の圧痕形状を前記基準測定体表面の２軸方向をそれぞれ表す変数で定式化し、この圧痕形状を示す式に乗じることにより前記被測定体の圧痕寸法となる数値を算出し、前記被測定体の残留応力を求める工程と、を有することを特徴とする残留応力測定方法。A step of forming an indentation on the surface of the object to be measured and measuring an indentation dimension in the biaxial direction of the surface of the object to be measured, and a reference measuring object formed from the same material as the object to be measured and having no residual stress in advance wherein the step of previously obtained an impression dimensions in the two axial directions of the indentation case loaded with experimental or analytically unit stress from uniaxial or more directions, the indentation shape when loaded with unit stress of the reference measurement member Formulate with variables representing the biaxial directions of the surface of the reference measurement body, and calculate the numerical value to be the indentation dimension of the measurement object by multiplying the expression indicating the indentation shape to obtain the residual stress of the measurement object A process for measuring residual stress.
JP2001102157A 2001-03-30 2001-03-30 Residual stress measurement method Expired - Fee Related JP4261080B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2001102157A JP4261080B2 (en) 2001-03-30 2001-03-30 Residual stress measurement method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2001102157A JP4261080B2 (en) 2001-03-30 2001-03-30 Residual stress measurement method

Publications (2)

Publication Number Publication Date
JP2002296125A JP2002296125A (en) 2002-10-09
JP4261080B2 true JP4261080B2 (en) 2009-04-30

Family

ID=18955382

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2001102157A Expired - Fee Related JP4261080B2 (en) 2001-03-30 2001-03-30 Residual stress measurement method

Country Status (1)

Country Link
JP (1) JP4261080B2 (en)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4855920B2 (en) * 2006-12-26 2012-01-18 日立Ｇｅニュークリア・エナジー株式会社 Residual stress evaluation method for water jet peening surface
KR100932454B1 (en) 2007-12-27 2009-12-17 한국생산기술연구원 Residual stress measuring equipment calibration device and method
JP5148459B2 (en) * 2008-11-20 2013-02-20 日立Ｇｅニュークリア・エナジー株式会社 Residual stress measuring device and method
JP5375476B2 (en) * 2009-09-15 2013-12-25 新日鐵住金株式会社 Method for estimating compressive stress value, compressive stress value estimating apparatus, and laser processing apparatus
KR101208036B1 (en) 2010-09-01 2012-12-04 주식회사 쓰리텍 Measuring method for residual stress of concrete structure using indentation test apparaus and indenter used in the same
US10598556B2 (en) 2013-08-21 2020-03-24 United Technologies Corporation Method for in-situ markers for thermal mechanical structural health monitoring
CN104122205B (en) * 2014-07-31 2016-08-31 华中科技大学 A kind of method utilizing impression uplift capacity to measure residual stress
RU2570362C1 (en) * 2014-10-14 2015-12-10 федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Пермский национальный исследовательский политехнический университет" Device for detection of residual stresses
JP6149843B2 (en) * 2014-11-04 2017-06-21 Ｊｆｅスチール株式会社 Method and apparatus for analyzing shape correction of press-formed product, and method for correcting shape of press-formed product
KR101901789B1 (en) * 2016-11-01 2018-09-27 한국표준과학연구원 Measurement method for a residual stress of materials
JP7513234B1 (en) 2024-02-16 2024-07-09 株式会社Ｘ線残留応力測定センター How to determine principal stresses from measurements of stresses in multiple directions and shear stresses

Also Published As

Publication number Publication date
JP2002296125A (en) 2002-10-09

Similar Documents

Publication Publication Date Title
US8214162B2 (en) Estimation of non-equibiaxial stress using instrumented indentation technique
JP4261080B2 (en) Residual stress measurement method
Schajer et al. Overview of residual stresses and their measurement
KR101840958B1 (en) Residual stress measuring method
Peng et al. Spherical indentation method for estimating equibiaxial residual stress and elastic–plastic properties of metals simultaneously
CN105675419B (en) Biconial press-in prediction material single shaft constitutive relation assay method
Daoud et al. Strain-energy release rate for a single-edge-cracked circular bar in tension
Sagadevan et al. Novel Analysis on the Influence of Tip Radius and Shape of the Nanoindenter on the Hardness of Materials
CN111964824B (en) Method for testing residual stress based on indentation energy difference
KR100736436B1 (en) Method for measuring indentation hardness through analysis of indentation shape
CN104122205B (en) A kind of method utilizing impression uplift capacity to measure residual stress
JP2015163840A (en) Estimation method of corrosion, fatigue and operating life of steel material
CN107941689B (en) Method for testing in-place performance of components of particle reinforced composite material
CN108254253A (en) Material or component equivalent stress-strain relation assay method
KR20100009758A (en) Indentation-driven tensile test specimen with single test section and manufacturing method thereof
KR20130077923A (en) Calculation method for distribution of residual force
CN113029826A (en) Method for determining fracture performance of metal material by using pre-notched small punch test sample
JP4910135B2 (en) Strain measuring method and strain measuring apparatus
Glaser et al. Comparison between Stereo Optical Strain Measurements and Finite Element Results in Stress Concentration Zones
Seidt et al. Influence of fabrication method on tensile response of split Hopkinson bar-sized specimens
Soifer et al. Investigation of the local mechanical properties of potassium chloride single crystals by atomic force microscopy
CN115901455B (en) Die and method for testing cold bending processing residual stress of corrugated steel web
Kawdi et al. A Study on Approaches for Measuring Outstanding Stress
RU2654901C2 (en) Method of estimation of friction coefficient of materials
Schajer et al. Relaxation Type Residual Stress Measurement Methods

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20060815

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20081029

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20081104

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20081125

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20090127

A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20090205

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120220

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120220

Year of fee payment: 3

LAPS Cancellation because of no payment of annual fees