KR101631747B1 - Measuring apparatus and method of elastic modulus for diagnosing material damages - Google Patents

Abstract

The present invention relates to an indentation elastic modulus measuring device for local diagnosis of material damage and a measuring method thereof. The push-in elastic modulus measuring device according to an embodiment of the present invention is press-fitted into a specimen and includes main-pressure particles 210 having a first radius of curvature, the same material as that of the main-pressure particle 210, , A negative pressure particle (220) having a second radius of curvature smaller than the first radius of curvature, a load measuring part (220) for measuring a load applied to the main particle (210) A displacement sensor 500 for measuring the depth of the main pellet 210 or the subpenetration particle 220 inserted into the specimen, a load sensor 400 for measuring a load measured by the load measuring unit 400, 500) may be used to calculate the elastic modulus of the specimen.

Description

Technical Field [0001] The present invention relates to an apparatus for measuring an indentation elastic modulus for local diagnosis of a material damage,

The present invention relates to an indentation elastic modulus measuring device for local diagnosis of material damage and a measuring method thereof, and more particularly, to an apparatus for measuring a indentation elastic modulus for diagnosing a material damage using an indentor having a different radius of curvature, ≪ / RTI >

It has been reported that the elastic properties of the metal, that is, the elastic modulus, are lowered as the material damage of the metal member operated at high temperature and high pressure accumulates. In particular, even when exposed to an erosive environment such as hydrogen, Or defects accumulate in the grain boundaries, resulting in degradation of the elastic properties. If the elastic modulus of such a damaged member can be measured simply and quantitatively, it is also possible to grasp the degree of damage from the change in elastic modulus.

As a basic method for measuring the elastic modulus of a material, a method of inducing an elastic deformation of a material, measuring a force and a displacement necessary for its reversible recovery, and deducing from the slope is common. For example, in the uniaxial tensile test, the force-elongation displacement data when the specimen is stretched in the axial direction in the elastic section can be obtained and converted into the stress-strain data considering the elongation sectional area and initial length of the specimen. The slope of the converted elastic deformation line, that is, the increasing stress / elongation strain, becomes the elastic modulus of the uniaxial tensile test piece.

Since the 1990s, instrumented indentation tests have been developed to improve the indentation hardness test specimens and continuously measure the indentation load - penetration displacement curve.

Instrumented indentation testing is a robust method for locally diagnosing material damage because it provides techniques to measure the strength, residual stress and fracture toughness of the operating member in operation. In particular, a technique for evaluating the elastic modulus from the slope of the load removal graph, that is, contact stifffness, has been developed in a nanoindentation test, which induces a micron-sized indentation strain by applying a local load of several hundreds of mN or less. When using this method in the instrumentation indentation test method, it is possible to evaluate the elastic modulus of a material that has undergone simple material damage.

However, the evaluation of the modulus of elasticity using the load removal graph developed by the nano indentation test method showed an excessive evaluation of the elastic modulus due to the occurrence of excessive fatigue zone, particularly the accumulation of material around the pressure particle, in the instrumental indentation test , There was a limitation in measuring the quantitative elastic properties of the material.

Maneiro and Rodriguez then calculated the modulus of elasticity by substituting Hertz 's equation (1) from the load removal graph obtained in the spherical indentation test.

은 곡률을 가진 2개의 입자가 맞닿을 때의 하중이고,

은 유효 탄성계수이며,

는 압입자 및 시편 표면 사이의 접촉곡률반경이고,

는 탄성 압입변위를 나타낸다.In Equation (1)

Is a load when two particles having a curvature come into contact with each other,

Is an effective elastic modulus,

Is the radius of curvature of contact between the pressure particle and the specimen surface,

Represents an elastic indentation displacement.

을 결정하기 위해서는 압입자 및 시편 표면 사이의 접촉곡률반경

의 결정이 필요하다.As can be seen from Equation (1), the effective elastic modulus

The radius of curvature of contact between the compact particles and the specimen surface

Is required.

는 하기의 수학식 2와 같이 표현된다.Particularly, when the process of removing the indentation load after primary indentation on the surface of the specimen by the primary indenter is expressed by Equation (1), the radius of curvature of contact

Is expressed by the following equation (2).

는 압입자의 곡률반경이고,

은 압흔의 곡률반경을 나타낸다.In Equation (2)

Is the radius of curvature of the indenter,

Represents the radius of curvature of the indentation.

와 달리 압흔의 경우 오목한 형태로 음의 곡률반경인

을 가진다. 주 압입자의 곡률반경인

는 알려져 있으나, 압입하중을 인가하여 변형이 유발된 이후 탄성회복을 겪고 난 이후에 재료표면에 남은 압흔의 곡률반경 “

”의 값은 직접 관찰을 하지 않고서는 결정이 곤란하다.In particular, the radius of curvature of the indenter

In contrast to indentation, the radius of curvature

. The radius of curvature of the main indenter

The radius of curvature of the indentation remaining on the surface of the material after experiencing elastic recovery after the deformation is induced by applying the indentation load is known,

"Is difficult to determine without direct observation.

Maneiro and Rodriguez assume that the contact depth and contact radius determined in Oliver-Pharr's load removal graph analysis are equal to the contact properties between the blob and specimen surface under maximum load, The radius of curvature of indentation is expressed by Equation 3

은 압흔의 곡률반경이고,

는 압입자의 곡률반경이며,

max는 최대 압입깊이이고,

f는 압입하중을 완전히 제거하고 남은 잔류 압입깊이를 나타낸다.In Equation (3)

Is the radius of curvature of the indentation,

Is the radius of curvature of the indenter,

max is the maximum indentation depth,

f represents the residual indentation depth remaining after the indentation load is completely removed.

을 수학식 2에 대입하여 결정된

와 하중제거곡선을 수학식 1로 최적화한 피팅 상수값

을 비교하여 환산 탄성계수

이 결정된다.The radius of curvature of the indentation determined in equation (3)

Into the equation (2)

And the fitting constant value optimized by the equation (1) for the load removal curve

And the calculated elastic modulus

Is determined.

However, since the contact depth and the contact radius are determined by the load removal curve analysis method of Oliver-Pharr in Equation (3), there is still a problem that it is impossible to clearly grasp the accumulation of material around the pressure particle.

Therefore, in the present invention, in order to more easily evaluate the radius of curvature of contact and the radius of curvature of the indentation, and ultimately to more clearly evaluate the material damage, a two-kind spherical indentation test apparatus And a test method thereof

1. W. C. Oliver and G. M. Pharr, An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments, Journal of Materials Research, 7 (1992) pp. 1564-1583. 2. J. Rodriguez and M.A. Garrido Maneiro, A procedure to prevent pile up effects on the analysis of spherical indentation data in elastic plastic materials. Mechanics of Materials, 39 (2007) pp. 987-997.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a user with an indentation elastic modulus measuring device for local diagnosis of material damage and a measuring method thereof.

을 결정할 수 있고, 이로부터 하중제거곡선 혹은 하중재인가 곡선의 접촉곡률반경인

나

를 독립적으로 결정할 수 있도록 하는데 그 목적이 있다.Specifically, by using the main-pressure particle and the negative indentor, the contact curvature radius ratio

From which the load removal curves or the contact curvature radii of the load application curve

I

To be able to decide independently.

나

가 결정되었기 때문에 탄성접촉식으로부터 압입변형된 시험편의 재료쌓임변형을 무시하는 것과 같은 별다른 가정없이 탄성계수를 정량적으로 결정할 수 있도록 하는데 그 목적이 있다.Also,

I

The elastic modulus can be determined quantitatively without any assumptions such as ignoring the material deformation of the specimens subjected to the press-in deformation from the elastic contact type.

The object of the present invention is to make it possible to determine the elastic modulus independently without influencing the accumulation of materials and so on, and to grasp the change of the elastic modulus eigenvalue which is clearly affected by the material damage.

The purpose of this study is to make it possible to carry out the instrumented indentation system without the need to move the instrumentation indentation system several times because it obtains a load removal curve or a load-carrying curve in a single indentation with different spherical indenters of different sizes.

In addition, after all the flow curve measurement, residual stress, and fracture toughness tests are performed by the main-pressure particle, it is possible to analyze the elastic modulus by replacing the negative indentation and obtaining the one- So that it can be used.

의 값을 키울 수 있고, 이로 인해 수 N 범위에서 Hertz식을 만족시키는 피팅을 할 수 있도록 하는데 그 목적이 있다.In addition, by removing the load on the curved surface rather than the flat surface or applying the load-carrying material, the Hertz constant

And it is therefore an object of the present invention to provide fitting that satisfies the Hertz equation in the range of N.

In addition, the method of forming a load-applying curve by using two spherical indenters is performed by adjusting the radius of the secondary indenter to be close to the radius of the primary indenter so that tens to hundreds of N is applied The goal is to obtain a reversible load-carrying curve that is maintained.

In addition, unlike Oliver-Pharr's interpretation or Maneiro-Rodriguez's interpretation, no information about the contact depth or contact radius is needed, so it is not affected by the accumulation of materials around the indentation particles, It has its purpose.

In addition, in the instrumental indentation test, when two kinds of main-pressure particle and negative indentor are fastened to the indentation system at the same time and only the process of replacing the main indentor with the indentor is performed between the load removal process and the lower- So that it is possible to accumulate sufficient data necessary for the elastic modulus analysis without complicatedness.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. It can be understood.

The push-in elastic modulus measuring device according to an example of the present invention for realizing the above-described problem is provided with a main-pressure particle 210 which is press-fitted into a specimen and has a first radius of curvature, a material having the same material as that of the main- (220) having a second radius of curvature smaller than the first radius of curvature, which is press-fitted into the specimen and is applied to the main or sub-particles (210, 220) from the specimen A load sensor 400 for measuring a load, a displacement sensor 500 for measuring a depth of the main-pressure particle 210 or the sub-pressure particle 220 inserted into the specimen, And a calculation unit 600 for calculating the elastic modulus of the specimen using the measured load and the depth measured by the displacement sensor 500.

Also, the calculation unit 600 may calculate the elastic modulus using Equation (1).

Equation 1

은 상기 시편의 탄성계수이며,

는 상기 주 압입자(210)와 상기 시편 간의 접촉곡률반경이고,

는 상기 부 압입자(220)와 상기 시편 간의 접촉곡률반경이며,

는 상기 주 압입자(210) 또는 상기 부 압입자(220)의 압입에 의한 상기 시편의 탄성 압입변위를 나타낸다.In the above equation (1) Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220. [

및 상기

를 계산할 수 있다.Further, the calculation unit 600 may calculate the sum

And

Can be calculated.

Equation 2

은

이며,

는 상기 주 압입자(210)와 상기 시편간의 접촉곡률 반경이고,

는 상기 부 압입자(220)와 상기 시편간의 접촉곡률 반경이며,

상기 제 1 곡률반경이고,

는 상기 제 2 곡률 반경을 나타낸다.In Equation (2)

silver

Lt;

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

The first radius of curvature,

Represents the second radius of curvature.

을 계산할 수 있다.Also, the calculation unit 600 may calculate the average value

Can be calculated.

Equation 3

은

이며, 상기 수학식 3에서,

은 상기 시편으로부터 상기 주 압입자(210) 또는 상기 부 압입자(220)에 인가되는 하중이고,

은 상기 시편의 탄성계수이며,

은 상기 주 압입자(210)와 상기 시편 간의 접촉곡률반경이고,

는 상기 부 압입자(220)와 상기 시편 간의 접촉곡률반경이며,

는 상기 주 압입자(210) 또는 상기 부 압입자(220)의 압입에 의한 상기 시편의 탄성 압입변위를 나타낸다.remind

silver

In the above equation (3)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is the contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220. [

A press-in elastic modulus measuring apparatus according to an example of the present invention for realizing the above-mentioned problems is characterized in that a press-in elastic modulus measuring apparatus which is press-fitted into a specimen, has the same material, and has a plurality of pressure grains having different radii of curvature, A displacement sensor 500 for measuring the depth at which at least one indentator of the plurality of indenters is press-fitted into the specimen, and a load sensor 400 for measuring the load applied to the specimen, And a calculation unit for calculating a modulus of elasticity of the specimen using a load and a depth measured by the displacement sensor 500. [

Meanwhile, in order to achieve the above-mentioned object, the method of measuring the indentation elastic modulus according to an example of the present invention includes a first step of press-fitting a main-pressure particle 210 having a first radius of curvature to a specimen by a predetermined depth, A second step of measuring, in real time, a first load applied to the main-pressure particle (210) and a first depth into which the main-pressure particle (210) is press-fitted while removing the pressure particle (210) from the specimen, The secondary particles 220 are made of the same material as the material of the main particle 210 at the center of the primary indent due to the indentation of the particles 210 and have a second radius of curvature smaller than the first radius of curvature A third step of measuring in real time a second load applied to the sub-pressure particles 220 and a second depth at which the sub-pressure particles 220 are press-fitted, while the first load, the first depth, The second load and the second depth And it may include a fourth step of calculating the elastic modulus of the specimen.

In the fourth step, the elastic modulus can be calculated using Equation (1) below.

Equation 1

은 상기 시편으로부터 상기 주 압입자(210) 또는 상기 부 압입자(220)에 인가되는 하중이고,

은 상기 시편의 탄성계수이며,

는 상기 주 압입자(210)와 상기 시편 간의 접촉곡률반경이고,

는 상기 부 압입자(220)와 상기 시편 간의 접촉곡률반경이며,

는 상기 주 압입자(210) 또는 상기 부 압입자(220)의 압입에 의한 상기 시편의 탄성 압입변위를 나타낸다.In the above equation (1)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220. [

및 상기

를 계산할 수 있다.Further, by using the following equation (2)

And

Can be calculated.

Equation 2

은

이며,

는 상기 주 압입자(210)와 상기 시편간의 접촉곡률 반경이고,

는 상기 부 압입자(220)와 상기 시편간의 접촉곡률 반경이며,

상기 제 1 곡률반경이고,

는 상기 제 2 곡률 반경을 나타낸다.In Equation (2)

silver

Lt;

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

The first radius of curvature,

Represents the second radius of curvature.

을 계산할 수 있다.Further, by using the following equation (3)

Can be calculated.

Equation 3

은

이며, 상기 수학식 3에서,

은 상기 시편으로부터 상기 주 압입자(210) 또는 상기 부 압입자(220)에 인가되는 하중이고,

은 상기 시편의 탄성계수이며,

은 상기 주 압입자(210)와 상기 시편 간의 접촉곡률반경이고,

는 상기 부 압입자(220)와 상기 시편 간의 접촉곡률반경이며,

는 상기 주 압입자(210) 또는 상기 부 압입자(220)의 압입에 의한 상기 시편의 탄성 압입변위를 나타낸다.remind

silver

In the above equation (3)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is the contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220. [

In order to achieve the above object, there is provided a method of measuring a press-in elastic modulus according to an example of the present invention, comprising the steps of: pressing a first indentor among a plurality of indentations having the same material and having different radii of curvature, A second step of real-time measurement of a first load applied to the first pressure particle and a first depth in which the first presser is press-fitted while the press-fitted first presser is removed from the specimen, And a second load applied to the second indentation while pressing the second indentor having a curvature radius smaller than that of the first indentation among the plurality of indentations, A first depth, a second depth, a second depth, and a second depth in real time, and measuring the elasticity of the specimen using the first load, the first depth, To count the number may include a fourth step.

In the fourth step, the elastic modulus can be calculated using Equation (1) below.

Equation 1

은 상기 시편으로부터 상기 주 압입자(210) 또는 상기 부 압입자(220)에 인가되는 하중이고,

은 상기 시편의 탄성계수이며,

는 상기 주 압입자(210)와 상기 시편 간의 접촉곡률반경이고,

는 상기 부 압입자(220)와 상기 시편 간의 접촉곡률반경이며,

는 상기 주 압입자(210) 또는 상기 부 압입자(220)의 압입에 의한 상기 시편의 탄성 압입변위를 나타낸다.In the above equation (1)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220. [

On the other hand, a program of instructions executable by the digital processing apparatus is implemented tangibly to carry out the method of measuring the indentation elastic modulus according to an example of the present invention for realizing the above-mentioned problems, The recording medium capable of being press-fit includes a first step of press-fitting a main-pressure particle 210 having a first radius of curvature to a specimen by a predetermined depth, a step of removing the main-pressure particle 210 from the specimen while press- A second step of measuring a first load applied to the main particle 210 and a first depth of the main particle 210 in real time; Wherein the negative pressure particle (220) is made of the same material as the material of the main pressure particle (210), and the negative pressure particle (220) having a second radius of curvature smaller than the first radius of curvature is press- A second step of measuring a first load, a second load applied to the first load, a second load applied to the first load and a second depth into which the sub-molar particles 220 are pressed, And calculating a modulus of elasticity of the specimen.

In the fourth step, the elastic modulus can be calculated using Equation (1) below.

Equation 1

은 상기 시편으로부터 상기 주 압입자(210) 또는 상기 부 압입자(220)에 인가되는 하중이고,

은 상기 시편의 탄성계수이며,

는 상기 주 압입자(210)와 상기 시편 간의 접촉곡률반경이고,

는 상기 부 압입자(220)와 상기 시편 간의 접촉곡률반경이며,

는 상기 주 압입자(210) 또는 상기 부 압입자(220)의 압입에 의한 상기 시편의 탄성 압입변위를 나타낸다.In the above equation (1)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220. [

및 상기

를 계산할 수 있다.Further, by using the following equation (2)

And

Can be calculated.

Equation 2

은

이며,

는 상기 주 압입자(210)와 상기 시편간의 접촉곡률 반경이고,

는 상기 부 압입자(220)와 상기 시편간의 접촉곡률 반경이며,

상기 제 1 곡률반경이고,

는 상기 제 2 곡률 반경을 나타낸다.In Equation (2)

silver

Lt;

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

The first radius of curvature,

Represents the second radius of curvature.

을 계산할 수 있다.Further, by using the following equation (3)

Can be calculated.

Equation 3

은

이며, 상기 수학식 3에서,

은 상기 시편으로부터 상기 주 압입자(210) 또는 상기 부 압입자(220)에 인가되는 하중이고,

은 상기 시편의 탄성계수이며,

은 상기 주 압입자(210)와 상기 시편 간의 접촉곡률반경이고,

는 상기 부 압입자(220)와 상기 시편 간의 접촉곡률반경이며,

는 상기 주 압입자(210) 또는 상기 부 압입자(220)의 압입에 의한 상기 시편의 탄성 압입변위를 나타낸다.remind

silver

In the above equation (3)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is the contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220. [

On the other hand, a program of instructions executable by a digital processing apparatus is tangibly embodied in order to perform a method of measuring an elastic system using a plurality of indenters related to an example of the present invention for realizing the above-mentioned problems, A recording medium which can be read by the digital processing apparatus includes a first step of press-fitting a first indentifier among a plurality of indentations having the same material and having different radii of curvature into the specimen by a predetermined depth, A second step of measuring, in real time, a first load applied to the first indenter and a first depth of the first indenter being press-fitted while being removed from the specimen, a second step of measuring the indent of the indent due to the indentation of the first indenter And a second indenter having a radius of curvature smaller than that of the first indentifier among the plurality of indentations is press- A second step of measuring in real time a second load applied to the two-pressed particles and a second depth in which the second indentor is press-fitted, using the first load, the first depth, the second load and the second depth And calculating a modulus of elasticity of the specimen.

The present invention can provide a user with an indentation elastic modulus measuring device and a measuring method thereof for local diagnosis of material damage.

을 결정할 수 있고, 이로부터 하중제거곡선 혹은 하중재인가 곡선의 접촉곡률반경인

나

를 독립적으로 결정할 수 있다.Specifically, by using the main-pressure particle and the negative indentor, the contact curvature radius ratio

From which the load removal curves or the contact curvature radii of the load application curve

I

Can be determined independently.

나

가 결정되었기 때문에 탄성접촉식으로부터 압입변형된 시험편의 재료쌓임변형을 무시하는 것과 같은 별다른 가정없이 탄성계수를 정량적으로 결정할 수 있다.Also,

I

The modulus of elasticity can be determined quantitatively without any assumptions such as ignoring material accumulation deformation of the specimens subjected to indentation transformation from the elastic contact type.

In addition, it is possible to independently determine the elastic modulus without influencing the material accumulation and the like, so that it is possible to grasp the change in the elastic modulus inherent value, which is clearly affected by the material damage.

In addition, it is possible to test without the need to move the instrumentation indentation system several times because it obtains a load removal curve or a load-applying curve within a single indentation with a spherical indentor of different size.

In addition, after all the flow curve measurement, residual stress, and fracture toughness tests are performed by the main-pressure particle, it is possible to analyze the elastic modulus by replacing the negative indentation and obtaining the one- Can be used.

의 값을 키울 수 있고, 이로 인해 수 N 범위에서 Hertz식을 만족시키는 피팅을 할 수 있다.In addition, by removing the load on the curved surface rather than the flat surface or applying the load-carrying material, the Hertz constant

Can be increased, so that it is possible to perform fitting that satisfies the Hertz equation in the range of the number N. [

In addition, the method of forming a load-applying curve by using two spherical indenters is performed by adjusting the radius of the secondary indenter to be close to the radius of the primary indenter so that tens to hundreds of N is applied A reversible load carrying curve can be obtained.

In addition, unlike Oliver-Pharr's interpretation or Maneiro-Rodriguez's interpretation, no information about the contact depth or contact radius is needed, so it is not affected by the accumulation of materials around the indentation particles, have.

In addition, in the instrumental indentation test, when two kinds of main-pressure particle and negative indentor are fastened to the indentation system at the same time and only the process of replacing the main indentor with the indentor is performed between the load removal process and the lower- It is possible to accumulate sufficient data for the elastic modulus analysis without complication.

It should be understood, however, that the effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those skilled in the art to which the present invention belongs It will be possible.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate a preferred embodiment of the invention and, together with the description, serve to provide a further understanding of the technical idea of the invention, It should not be construed as limited.
Fig. 1 shows an example of a conventional instrumentation indentation test method for measuring the elastic modulus of a specimen by press-fitting an indenter into a specimen.
2 is a block diagram of an indentation elastic modulus measuring apparatus according to an embodiment of the present invention.
3A shows a state before a main indenter according to an embodiment of the present invention is pressed into a specimen and removed from the specimen.
FIG. 3B shows a state in which no load is applied to the main-pressure particle according to an embodiment of the present invention.
4 is a curve showing a load applied to the main-pressure particle with respect to the depth of the main indenter being press-fitted according to an embodiment of the present invention.
FIG. 5A shows a state before the negative indent according to an embodiment of the present invention is pressed into the specimen. FIG.
FIG. 5B shows a state in which the negative indentor is press-fitted into the test piece according to an embodiment of the present invention.
FIG. 6 is a curve showing a load applied to the negative pressure particle with respect to the depth of the indentation by the negative indentor according to an embodiment of the present invention.
FIG. 7 shows a curve in which the load is applied at the curve in FIG. 5 as the origin and a curve in which the load is applied at the curve in FIG. 6 as the origin, in one coordinate system.
8 is a flowchart showing a method of measuring elastic modulus using an indenter according to an embodiment of the present invention.

As the material damage of the metal member operated at high temperature and high pressure accumulates, the elastic property of the metal is degraded. If the elastic modulus of such a damaged member can be measured simply and quantitatively, it is also possible to grasp the degree of damage from the change in elastic modulus.

As a basic method for measuring the elastic modulus of a material, a method of inducing an elastic deformation of a material, measuring a force and a displacement necessary for its reversible recovery, and deducing from the slope is common.

Thereafter, as shown in Fig. 1, instrumented indentation test for continuously measuring indentation load-infiltration displacement curve using the pressure particle 1 was developed.

1 shows an example of a conventional instrumentation indentation test method in which a conventional indentor is pressed into a test piece to measure the elastic modulus of the test piece.

However, in the instrumentation indentation test, the elastic modulus was overestimated due to the excessive firing range, especially the serious material accumulation around the pressure particle, and there was a limitation in measuring the quantitative elastic properties of the material.

Maneiro and Rodriguez then calculated the modulus of elasticity by substituting Hertz 's equation (1) from the load removal curve obtained in the spherical indentation test.

은 곡률을 가진 2개의 입자가 맞닿을 때의 하중이고,,

은 유효 탄성계수이며,

는 압입자 및 시편 표면 사이의 접촉곡률반경이고,

는 탄성 압입변위를 나타낸다.In Equation (4)

Is the load when two particles having a curvature meet,

Is an effective elastic modulus,

Is the radius of curvature of contact between the pressure particle and the specimen surface,

Represents an elastic indentation displacement.

의 값은 구할 수 있으나 이는 탄성계수

과

가 복합된 정보로써 탄성계수만을 특정하기 어렵다.Using Equation 4 above,

The value of the elastic modulus

and

It is difficult to specify only the modulus of elasticity.

및

의 값을 구하고, 이들의 비 값인

을 구하여

및

를 구하며, 궁극적으로 탄성계수

을 해석할 수 있는 압입자의 곡률반경이 서로 다른 2종 구형압입시험을 제안한다.Therefore, in the present invention, two indentation curves are formed from two elastic indentation curves

And

, And their non-values

To obtain

And

, And ultimately the modulus of elasticity

We propose a two-kind spherical indentation test in which the radius of curvature of the indenter is different.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. In addition, the embodiment described below does not unduly limit the contents of the present invention described in the claims, and the entire configuration described in this embodiment is not necessarily essential as the solution means of the present invention.

2 is a block diagram of an indentation elastic modulus measuring apparatus according to an embodiment of the present invention.

The press-fitting elastic modulus measuring apparatus may include a main-pressure particle 210, a sub-pressure particle 220, a driving unit 300, a load measuring unit 400, a displacement sensor 500, a calculating unit 600, . However, the constituent elements shown in Fig. 2 are not essential, so that an indentation elastic modulus measuring apparatus having more or fewer constituent elements may be implemented.

Hereinafter, the components will be described in order.

The indenter conveys the external load to the specimen and has a hardness higher than that of the specimen so that it is unilaterally press-fitted into the object surface. The indenter may be a pyramid, a cone, a cylinder, a square column, a sphere, a Vickers type, a nubu type, etc. However, in the present invention, an indenter having curvature at the end is used.

In the present invention, the main-pressure particle 210 has a first radius of curvature at the tip, the sub-pressure particle 220 is made of the same material as the material of the main-pressure particle 210, and the second curvature Radius.

The driving unit 300 is configured to apply a force to the specimen or remove it from the specimen in order to change the press-fitting load applied to the pressure particle.

In addition, the load measuring unit 400 is a structure capable of measuring the load applied to the pressure particles from the specimen in the process of being applied to or removed from the specimen.

Further, the displacement sensor 500 is configured to measure the depth of the indentation from the initial indentation position.

The calculation unit 600 calculates the elastic modulus of the specimen using the load measured by the load measuring unit 400 and the depth measured by the displacement sensor 500. [

Hereinafter, a process of calculating a load removal curve using the main-pressure particle 210 will be described with reference to FIGS. 3A, 3B, and 4. FIG.

3A shows a state before a main indenter according to an embodiment of the present invention is pressed into a specimen and removed from the specimen.

FIG. 3B shows a state in which no load is applied to the main-pressure particle according to an embodiment of the present invention.

4 is a curve showing a load applied to the main-pressure particle with respect to the depth of the main indenter being press-fitted according to an embodiment of the present invention.

First, the indenter is press-fitted into the specimen so that a predetermined load is applied to the main-pressure particle 210 using the driving unit 300. 3, the main-pressure particle 210 is removed from the specimen, the load applied to the main-pressure particle 210 is measured using the load-measuring unit 400, and the displacement sensor 500 is used And the depth at which the main-pressure particle 210 is press-fitted is measured.

As a result of the measurement, a load removal curve, which is a relationship between the indentation depth of the main-pressure particle 210 and the load applied to the main-pressure particle 210, obtained in the process of removing the main-pressure particle 210 from the specimen, can do.

A primary indent due to the indentation of the bump particles 210 is generated in the specimen after obtaining the load removal curve by the bump particles 210.

Next, referring to FIGS. 5A, 5B, and 6, a secondary indenter having a second radius of curvature smaller than the first radius of curvature of the main-pressure particle 210 is used to form the main- 210 is subjected to a second indentation test at the center of the indent due to indentation to obtain a reloading curve.

5A shows a state before a negative indent is inserted into a test piece according to an embodiment of the present invention.

5B shows a state in which the negative indentor is press-fitted into the test piece according to an embodiment of the present invention.

FIG. 6 is a curve showing a load applied to the negative pressure particle with respect to the depth of the indentation by the negative indentor according to an embodiment of the present invention.

As shown in FIGS. 5A and 5B, by using the driving unit 300, the negative pressure particles 220 are pressed into the central portion of the indentation, and the negative pressure particles 220 The load is measured, and the depth at which the sub-pressure particles 220 are press-fitted is measured using the displacement sensor 500.

As a result of measurement, as shown in FIG. 6, the load-applied curve, which is the relationship between the indentation depth of the sub-pressure particles 220 and the load applied to the sub-particles 220, obtained in the process of pressurizing the sub- Can be obtained.

However, when the negative pressure particle 220 is pressed into the specimen, the specimen may enter the firing section when the applied load is excessive. That is, when the negative pressure particles 220 are removed, the specimen may not be restored to the state before the load is applied.

Multiple indentation can be used to apply the subpenetration (220) to the specimen because the data in the firing interval will cause an error in the experimental results. That is, the load application curve is obtained by repeating application and removal while slightly increasing the maximum load applied to the pressure particle. As we increase the maximum load, the application and removal curves lose their overlap at the point where they deviate from the elastic curve. That is, plastic deformation occurred in the portion where the overlap degree is lost.

Therefore, the load indentation curve with negative indentation should be used only in the section where plastic deformation does not occur, that is, in the section where the excitation and removal curves overlap.

Next, a process of calculating the modulus of elasticity from the curve obtained previously by the calculation unit 600 will be described with reference to FIG.

FIG. 7 shows a curve in which the load is applied at the curve in FIG. 5 as the origin and a curve in which the load is applied at the curve in FIG. 6 as the origin, in one coordinate system.

Since all the specimens have a reversible deformation process, the load removal curve obtained using the pumped particle 210 as shown in FIG. 7 and the load-applied curve obtained using the negative pressure particle 220 can be obtained by using the following equation (5) .

은 곡률을 가진 2개의 입자가 맞닿을 때의 하중이고,,

은 유효 탄성계수이며,

는 압입자 및 시편 표면 사이의 접촉곡률반경이고,

는 탄성 압입변위를 나타낸다.In Equation (5)

Is the load when two particles having a curvature meet,

Is an effective elastic modulus,

Is the radius of curvature of contact between the pressure particle and the specimen surface,

Represents an elastic indentation displacement.

과 탄성 압입변위

는 하중 측정부(400)와 변위 센서(500)로 구할 수 있으나

은 탄성계수

과

가 복합된 정보로써 하나의 정보를 특정하기 어렵다. 따라서 다음과 같은 방법으로 접촉곡률반경

를 구한다.weight

And elastic indentation displacement

Can be obtained by the load measuring unit 400 and the displacement sensor 500

Modulus of elasticity

and

It is difficult to specify one piece of information. Therefore, the radius of curvature of contact

.

와

로 결정된다. 사용된 두 압입자의 재질이 동일할 경우

값이 동일하기 때문에 두 피팅상수의 비 값은

가 된다.First, when the load removal curve and the under-insertion application curve are obtained as shown in FIG. 7, if the two curves are optimized by Equation (4)

Wow

. If the two indenters used are of the same material

Since the values are the same, the ratio values of the two fitting constants are

.

이 관련되어 있고, 하중재인가 과정의 경우 부 압입자(220)의 제 2 곡률반경과 압흔의 곡률반경

이 관련되어 있다. 사용된 압입자 각각의 곡률반경은 다르나 압입자와 접하는 압흔의 곡률반경은

로 공통이다. 따라서 상기 수학식 2로부터 수학식 6을 도출할 수 있다.The pressure drop particles and the indentations on the surface of the test piece, which are in contact with each other during the load removal process by the main-pressure particle 210 and the sub-intermediate particle application process by the sub-pressure particle 220, ) And the radius of curvature of the indentation

And in the case of the load application process, the second radius of curvature of the sub-pressure particle 220 and the radius of curvature of the indentation

. The radius of curvature of each indentation used is different, but the radius of curvature of the indentation in contact with the indentation is

. Therefore, Equation (6) can be derived from Equation (2).

은 압흔의 곡률반경이고,

는 주 압입자(210)의 제 1 곡률반경이며,

는 주 압입자와 압흔의 접촉곡률반경이고,

는 부 압입자의 제 2 곡률반경이며,

는 부 압입자와 압흔의 접촉곡률반경을 나타낸다.here

Is the radius of curvature of the indentation,

Is the first radius of curvature of the main particle 210,

Is the radius of curvature of contact between the main particle and the indentation,

Is the second radius of curvature of the negative indenter,

Represents the contact radius of curvature of the indentation.

로 정의하고,

를 상기 수학식 6에 대입하여 정리하면 하기의 수학식 7과 같이 나타낼 수 있다.Next, the ratio of the fitting constant obtained experimentally

Respectively,

Can be expressed as Equation (7) below. ≪ EMI ID = 7.0 >

또는

를 상기 수학식 5에 대입하면 환산탄성계수

을 구할 수 있다.(7)

or

Is substituted into the equation (5), the elastic modulus

Can be obtained.

와

의 비값

로부터 해석된

또는

를 대입하게 되면 최종적으로 환산탄성계수

값이 결정된다.As a result, the fitting constant obtained by optimizing the load removal curve and the load-applied curve with Equation 4 analyzed by Hertz

Wow

The ratio of

Interpreted from

or

The final elastic modulus

Value is determined.

Next, with reference to Fig. 8, a method of measuring the elastic modulus using the indenter will be described.

8 is a flowchart showing a method of measuring elastic modulus using an indenter according to an embodiment of the present invention.

First, the main-pressure particle 210 having the first radius of curvature is press-fitted into the specimen by a predetermined depth (S100).

Next, the press-fitted main-pressure particle 210 is removed from the specimen, and a first load applied to the main-pressure particle 210 and a first depth at which the main-pressure particle 210 is press-fitted are measured in real time (S200).

The main indentation 210 is formed of the same material as the material of the main-pressure particle 210 at the center of the indent due to the press-fitting of the main-pressure particle 210, and has a second radius of curvature smaller than the first radius of curvature A second load applied to the sub-pressure particles 220 and a second depth at which the sub-pressure particles 220 are press-fitted are measured in real time while pushing the sub-pressure particles 220 (S300).

Then, the elastic modulus of the specimen is calculated using the first load, the first depth, the second load, and the second depth (S400).

The method of calculating the modulus of elasticity is as follows.

The measurement results for the first load and the first depth and the measurement results for the second load and the second depth may be expressed by Equation (5).

와

로 결정된다. 사용된 두 압입자의 재질이 동일할 경우

값이 동일하기 때문에 두 피팅상수의 비 값은 가 된다.When the above result is optimized by Equation (5), the fitting constants are

Wow

. If the two indenters used are of the same material

Since the values are the same, the ratio of the two fitting constants is.

를

로 정의하고 상기 수학식 6에 대입하면 상기 수학식 7을 얻을 수 있다. 실험적으로 구한 피팅상수의 비

을 상기 수학식 7에 대입하여

및

를 구하고 이를 상기 수학식 5에 대입하면 환산 탄성계수

을 계산할 수 있다.

To

And substituting it into Equation (6), the above Equation (7) can be obtained. The ratio of the fitting constant obtained experimentally

Into Equation (7)

And

And substituting this into the equation (5), the calculated elastic modulus

Can be calculated.

On the other hand, the elastic modulus measuring device using an indenter can measure elastic modulus by including not only two indenters but also three or more indenters.

The above-described invention can provide a user with an indentation elastic modulus measuring device for local diagnosis of material damage and a measuring method thereof.

을 결정할 수 있고, 이로부터 하중제거곡선 혹은 하중재인가 곡선의 접촉곡률반경인

나

를 독립적으로 결정할 수 있다.Specifically, by using the main-pressure particle 210 and the sub-pressure particle 220, the contact curvature radius ratio

From which the load removal curves or the contact curvature radii of the load application curve

I

Can be determined independently.

나

가 결정되었기 때문에 탄성접촉식으로부터 압입변형된 시험편의 재료쌓임변형을 무시하는 것과 같은 별다른 가정없이 탄성계수를 정량적으로 결정할 수 있다.Also,

I

The modulus of elasticity can be determined quantitatively without any assumptions such as ignoring material accumulation deformation of the specimens subjected to indentation transformation from the elastic contact type.

In addition, it is possible to independently determine the elastic modulus without influencing the material accumulation and the like, so that it is possible to grasp the change in the elastic modulus inherent value, which is clearly affected by the material damage.

In addition, it is possible to test without the need to move the instrumentation indentation system several times because it obtains a load removal curve or a load-applying curve within a single indentation with a spherical indentor of different size.

Further, after all the flow curve measurement, residual stress and fracture toughness tests are performed by the main-pressure particle 210, it is possible to analyze the elastic modulus by replacing the sub-pressure particle 220 with the one-time sub- Therefore, it can be used in combination with other measurement procedures.

의 값을 키울 수 있고, 이로 인해 수 N 범위에서 Hertz식을 만족시키는 피팅을 할 수 있다.In addition, by removing the load on the curved surface rather than the flat surface or applying the load-carrying material, the Hertz constant

Can be increased, so that it is possible to perform fitting that satisfies the Hertz equation in the range of the number N. [

In addition, the method of forming the load-applying curve by using two kinds of spherical indenters is performed by adjusting the radius of the secondary indenter 220 to be close to the radius of the primary indent 210, A reversible load-carrying curve can be obtained, which is maintained even when several hundreds N are applied.

In addition, unlike Oliver-Pharr's interpretation or Maneiro-Rodriguez's interpretation, no information about the contact depth or contact radius is needed, so it is not affected by the accumulation of materials around the indentation particles, have.

In the instrumentation indentation test, two kinds of the main-pressure particles 210 and the sub-abrasive particles 220 are simultaneously fastened to the press-fitting system, and the main-pressure particle 210 is pressed between the load removal process and the sub- If only the process of exchanging with the particles 220 is needed, it is possible to accumulate sufficient data for the elastic modulus analysis without complicating the additional test.

It should be understood, however, that the effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those skilled in the art to which the present invention belongs It will be possible.

The above-described indentation elastic modulus measuring apparatus and method for localized material damage diagnosis are not limited to the configurations and methods of the above-described embodiments, but the embodiments are not limited thereto All or some of the embodiments may be selectively combined.

Claims (16)

A main-pressure particle 210 which is press-fitted into the specimen and has a first radius of curvature;
Wherein the main indentation particles are made of the same material as the main indentation particles 210 and are pressed into the central portion of the indentation caused by the indentation of the main indentation with respect to the specimen and have a second radius of curvature smaller than the first radius of curvature, (220);
A load measuring unit 400 for measuring a load applied to the main and sub-particles 210 and 220 from the specimen;
A displacement sensor (500) for measuring the depth of the pneumatic particle (210) and the sub-pressure particle (220) inserted into the specimen; And
And a calculation unit 600 for calculating the elastic modulus of the specimen using the load measured by the load measuring unit 400 and the depth measured by the displacement sensor 500,
The calculation unit 600 calculates the elastic modulus using Equation (1) below,
Equation 1

(In the above formula (1)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220.)
The calculation unit 600 may calculate the difference between

And

Lt; / RTI >
Equation 2

(In the above equation (2)

silver

Lt;

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

The first radius of curvature,

Represents the second radius of curvature.)
The calculation unit 600 may calculate the sum

Of the elastic modulus of elasticity.
Equation 3

(remind

silver

In the above equation (3)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is the contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220.) delete delete delete delete A first step of press-fitting the main-pressure particle 210 having the first radius of curvature to the specimen by a predetermined depth;
A second step of real-time measuring a first load applied to the main-pressure particle 210 and a first depth into which the main-pressure particle 210 is inserted while removing the pressurized main-pressure particle 210 from the specimen, ;
Wherein the main indentation 210 is made of the same material as the material of the main-pressure particle 210 at the center of the primary indent due to the pressurization of the main-pressure particle 210 and has a second radius of curvature smaller than the first radius of curvature, A third step of real-time measuring a second load applied to the sub-pressure particles 220 and a second depth into which the sub-pressure particles 220 are press-fitted while pressurizing the particles 220; And
And calculating a modulus of elasticity of the specimen using the first load, the first depth, the second load, and the second depth,
The fourth step calculates the elastic modulus using Equation (1) below,
Equation 1

(In the above formula (1)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220.)
Using the following equation (2)

And

Lt; / RTI >
Equation 2

(In the above equation (2)

silver

Lt;

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

The first radius of curvature,

Represents the second radius of curvature.)
Using the following equation (3)

And calculating a modulus of elasticity of the indentation.
Equation 3

(remind

silver

In the above equation (3)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is the contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220.) delete delete delete delete delete There is provided a recording medium on which a program of instructions executable by a digital processing apparatus is tangibly embodied and can be read by the digital processing apparatus to perform a method of measuring elastic modulus using an indenter,
A first step of press-fitting the main-pressure particle 210 having the first radius of curvature to the specimen by a predetermined depth;
A second step of real-time measuring a first load applied to the main-pressure particle 210 and a first depth into which the main-pressure particle 210 is inserted while removing the pressurized main-pressure particle 210 from the specimen, ;
Wherein the main indentation 210 is made of the same material as the material of the main-pressure particle 210 at the center of the primary indent due to the pressurization of the main-pressure particle 210 and has a second radius of curvature smaller than the first radius of curvature, A third step of real-time measuring a second load applied to the sub-pressure particles 220 and a second depth into which the sub-pressure particles 220 are press-fitted while pressurizing the particles 220; And
Calculating a modulus of elasticity of the specimen using the first load, the first depth, the second load, and the second depth,
The fourth step calculates the elastic modulus using Equation (1) below,
Equation 1

(In the above formula (1)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220.)
Using the following equation (2)

And

Lt; / RTI >
Equation 2

(In the above equation (2)

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Lt;

Is a contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

The first radius of curvature,

Represents the second radius of curvature.)
Using the following equation (3)

Of the recording medium.
Equation 3

(remind

silver

In the above equation (3)

Is a load applied to the main-pressure particle (210) or the sub-pressure particle (220) from the specimen,

Is the elastic modulus of the specimen,

Is the contact radius of curvature between the main particle 210 and the specimen,

Is a radius of curvature of contact between the sub-pressure particles (220) and the specimen,

Represents the elastic indentation displacement of the specimen due to the press-fitting of the main-pressure particle 210 or the sub-pressure particle 220.) delete delete delete delete

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