KR101841202B1 - Evaluating Method of Strain Using Void Deformation, Deflection Measurement Method and Stress Measurement Method Using the Same - Google Patents

Evaluating Method of Strain Using Void Deformation, Deflection Measurement Method and Stress Measurement Method Using the Same Download PDF

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KR101841202B1
KR101841202B1 KR1020150089563A KR20150089563A KR101841202B1 KR 101841202 B1 KR101841202 B1 KR 101841202B1 KR 1020150089563 A KR1020150089563 A KR 1020150089563A KR 20150089563 A KR20150089563 A KR 20150089563A KR 101841202 B1 KR101841202 B1 KR 101841202B1
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stress
strain
void
measuring
deflection
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KR1020150089563A
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Korean (ko)
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KR20170000554A (en
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김우석
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충남대학교산학협력단
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/32—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring the deformation in a solid
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/60—Analysis of geometric attributes
    • G06T7/62—Analysis of geometric attributes of area, perimeter, diameter or volume

Abstract

Stress and strain are measured through measurement of pore deformation by stress generated in the structure using a gap formed on one side of the structure according to the present invention.

Description

Technical Field [0001] The present invention relates to a strain measurement method using a pore strain, a deflection measurement method using the same, and a strain measurement method using the strain measurement method.

More particularly, the present invention relates to a strain measuring method using porosity deformation, and more particularly, to a method of measuring a deformation amount of a pore by taking a gap formed in a structure to calculate strain, stress and deflection of a structure in which an initial value of stress or strain does not exist The present invention relates to a strain measurement method using a pore strain capable of measuring a stress and a deflection of a structure through a strain gage.

Structures such as bridges, harbors, power plants, buildings, and tunnels are very important structures that can cause economic and social losses and disruptions in the event of disruption due to structural aging or unexpected accidents.

These structures must be maintained during the planning, design and construction phases as well as during use. In particular, bridges are an important structure connecting national transportation networks. However, the existing bridges in Korea are likely to have suffered serious damage due to increase in traffic volume and aging due to long - term use.

According to the detailed guideline for the safety diagnosis of concrete structures for safe use of these structures, the stability evaluation of the structure is to determine the stability of the structure by calculating the stress of the member and comparing with the allowable stress.

However, there is a problem in that it is not easy to calculate stresses and strains occurring in structures in which measurement apparatuses are not installed at the beginning of the existing construction. In order to measure the stresses occurring in these structures, there are a destructive test for destructively measuring one side of the structure and a non-destructive test for calculating the stress without destroying the structure.

In case of destructive inspection, there is a problem that it is difficult to be applied to a structure actually used, and a non-destructive inspection is also required to use a large amount of equipment.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems and it is an object of the present invention to measure the stress and strain of a structure through deformation of voids by photographing a gap formed in a structure in order to calculate stress and deflection of a structure, The present invention provides a method of measuring a strain using a pore deformation.

The objects of the present invention are not limited thereto, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the object of the present invention as described above, the strain measurement method using pore deformation measures stress and strain by measuring pore deformation by stress generated in the structure using pores formed at one side of the structure.

In this case, the strain measuring method using the pore deformation may include a photographing step of photographing one side of the structure, a pore checking step of checking pores in the image photographed in the photographing step, And a stress measuring step of measuring a stress of the structure based on the deformation amount calculating step and the strain of the void calculated in the deformation calculating step.

In addition, the void checking step may include an image extracting step of extracting voids from the image, and a radius measuring step of measuring a major axis and a minor axis value of the void modified by the ellipse.

The method may further include a deflection measuring step of measuring a deflection of the structure using the strain of the gap calculated in the deflection calculating step.

Further, it is possible to determine the stress generated in the structure using the average value of the calculated values by repeating at least one of the photographing step, the photographing step, and the stress measuring step.

The stress measurement method using the pore deformation of the present invention has the following effects.

First, the existing stress and strain can be calculated even in the case of the existing structure in which the initial measurement value of the structure without the measuring device is not present.

Secondly, there is an effect that it is possible to easily calculate the stress and sag generated in the structure without destroying the structure.

Third, since one side of the structure is photographed, the pores are extracted from the photographed image to calculate the stress and deflection generated in the structure through the deformation of the pore. Therefore, it is possible to easily calculate the stress and deflection of the structure without using a separate measuring equipment There is an effect that can be.

Fourth, by using the method according to the present invention, it is possible to easily calculate the stress and deflection of the structure easily, even without experts.

Fifth, there is an effect that the present invention can be applied to a structure made of various materials including pores such as concrete, metal, non-ferrous metal, polymer or plastic.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description, serve to further the understanding of the technical idea of the invention, And shall not be interpreted.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart sequentially illustrating a stress and a strain measuring method using a porosity strain according to the present invention;
2 is a side view of the bridge;
3 is a cross-sectional view taken along line II of Fig. 2;
FIG. 4 schematically shows an image taken at part E of FIG. 2; FIG.
Figure 5 is an enlarged view of one cavity in Figure 4; And
6 is a view schematically showing deflection of a bridge.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Air or gas is introduced into the structure 100, which is manufactured by pouring a material such as metal, non-ferrous metal, concrete, polymer, or plastic into a mold in a liquid state, . Such voids 200 are generally formed in a spherical shape by surface tension. In the present invention, it is assumed that the cavity 200 has a spherical shape having a spherical surface having a predetermined diameter from the center.

In the structure including the void 200, deformation occurs in the structure 100 due to the stress generated in the structure 100 over time, so that the void 200 is also deformed and deformed into an ellipse . The stress measurement method using the pore deformation according to the present invention uses the deformation of the pore 200 to calculate the stress generated in the structure 100 without destruction of the structure.

The stress measuring method for measuring the stress of the structure 100 through the deformation of the void 200 will now be described in more detail.

2 is a side view of a bridge, FIG. 3 is a sectional view taken along the line II of FIG. 2, FIG. 4 is a sectional view taken along the line E of FIG. 2 Fig. First, as shown in FIG. 1, one side of the structure 100 is photographed (S100). At this time, the photographing position of the structure 100 may be any position. In one embodiment, the E-point side of the concrete bridge structure 100 shown in FIG. 2 is photographed. In this case, the point E is a point near the lower or lower surface of the bridge structure 100. In the present invention, the lower surface of the bridge structure 100 is taken as a reference. As described above, when one side of the bridge structure 100 is photographed, as shown in FIG. 4, it is possible to acquire a photographed image of many voids 200.

FIG. 5 is an enlarged view of one cavity in FIG. Next, the void 200 is confirmed in the photographed image in the photographing step S100 (S200). This pore identification step S200 includes an image extraction step S210 and a radius measurement step S220.

The image extracting step S210 is a step of checking the gap 200 in the image photographed in the photographing step S100 and extracting any one of the vacancies 200 included in the identified image as shown in Fig. do. Since the size of the cavity 200 is small in the image extracting step S210, the image can be enlarged and extracted for smooth subsequent processing.

Next, the radius measurement step S220 measures the long axis and the short axis radius of the void 220 deformed into the ellipse according to the deformation of the structure 100 selected in the image extraction step S210.

Next, the deformation amount of the void 220 deformed by the ellipse identified in the void confirmation step S200 is calculated (S300). That is, since the cavity 210, which was formed in a circular shape at the initial installation of the structure 100, is deformed into an ellipse due to the stress caused by the stress applied to the structure 100, the deformation amount of the cavity 200 is calculated. As it is shown in Figure 3, the stress of the structure in the point A to the point E (100) ε A to E strain ε and σ σ A to E, respectively occurs. In the present invention, it will be described with reference to calculate the stress σ and strain ε E of E because the description based on the image taken in the E point.

At this time, the strain rate of the major axis and the strain rate of the minor axis of the void 220 deformed by the ellipse can be calculated through the following equations (1) and (2), respectively.

Figure 112015061106015-pat00001

Figure 112015061106015-pat00002

Where ε x is the strain of the major axis of the pore 220 deformed by the ellipse, ε y is the strain of the minor axis of the pore 220 deformed by the ellipse, r is the radius of the pore 210, E is the modulus of elasticity of the structure 100, υ is the shear rate of the structure 100, σ x is the longitudinal axial stress, σ is the shear modulus of the structure 100, σ y means uniaxial stress. In this case, the elastic modulus E of the structure 100 and the shear force u of the structure 100 are generally values that can be confirmed through other non-destructive testing methods such as the method of inspecting the structure 100 or the rebound test.

The above-described Equation 1 and Equation 2 for each of the major axis stress (σ x) and the short axis direction stress In summary, based on the (σ y) the following Equation 3 and Equation 4 by simultaneous Can be summarized as follows.

Figure 112015061106015-pat00003

Figure 112015061106015-pat00004

On the other hand, the strain rates of the long axis and the short axis of the void 220 deformed by the ellipse can be calculated through the following equations (5) and (6), respectively.

Figure 112015061106015-pat00005

Figure 112015061106015-pat00006

Therefore, the equations (1) and (5) are summarized as the strain rate (? X ) of the major axis of the void 220 deformed by the ellipse, and the equations (2) and The strain rate? Y of the uniaxial axis of the void 220 can be summarized as shown in the following equations (7) and (8), respectively.

Figure 112015061106015-pat00007

Figure 112015061106015-pat00008

The following formulas (9) and (10) can be summarized by summarizing the above-described equations (7) and (8) with respect to the radius (r) of the circular air gap 210, respectively.

Figure 112015061106015-pat00009

Figure 112015061106015-pat00010

Since the radii r of the circular apertures 210 in the above-described equations (9) and (10) are the same, the following formulas (11) and (10) Can be summarized as follows.

Figure 112015061106015-pat00011

If the above-mentioned Equation (11) is summarized on the left side, it can be summarized as the following Equation (12).

Figure 112017040707055-pat00026

The value of the uniaxial stress (? Y ) at point E in FIG. 2 is zero. In other words, as shown in FIG. 3, the resistance to bending does not generate stress in the y-axis direction, but the upper end compresses in the x-axis direction with respect to the neutral axis of the cross section and the lower end of the neutral axis in the x- It appears as a tension. The following equations (13) and (14) can be calculated by applying the above equations to the equations (12) and (1) and summarizing them on the basis of the long axis stress ( x ). Therefore, assuming a strain that changes linearly from the lowest strain value and the uppermost strain value, the strain value, that is, the strain (ε x ) of the long axis, can be found at any point of the beam. Once the strain rate? X of the major axis is determined, the strain rate? Y of the minor axis can be determined from the above-mentioned expression (8).

Figure 112017040707055-pat00027

Figure 112017128381094-pat00029

The following can be summarized as the following equation (15) by summarizing the strain rate ε x of the major axis of the void 220 deformed into ellipses by simultaneously combining the above-described [Equation 13] and [Equation 14] .

Figure 112017128381094-pat00030

The long axis radius b of the void 220 deformed by the ellipse and the short axis radius a of the void 220 deformed by the ellipse in Equation 15 are obtained through measurement in the deformation amount calculation step S200 The value of the strain rate ( x ) of the major axis of the void 220 deformed by the ellipse can be obtained.

Next, the stress of the structure 100 can be measured based on the value of the strain rate ε x of the major axis of the void 220 deformed by the ellipse calculated through the expression (15) (S400). That is, the long axis stress? X can be calculated by applying the value of the strain rate? X of the long axis of the void 220 deformed by the ellipse to the equation (14).

Here, since the value of the strain rate ε x of the long axis of the void 220 deformed by the ellipse is a value that can be calculated through the expression (15), and the elastic modulus E of the structure 100 is also a verifiable value, An accurate value of the directional stress ( x ) can be obtained.

As described above, the uniaxial stress (? Y ) can also be calculated through the above-described process by photographing the point where the long axis stress (? X ) is zero. The stress acting on the structure 100 can also be calculated through the mutual alliance even when the long axis stress ( x ) and the uniaxial stress ( y ) are not zero.

The above equations are merely illustrative and are not intended to be limiting. Any mathematical expression that can measure the stress of the structure 100 using the deformation of the cavity 200 can be calculated through any mathematical expression It is acceptable.

6 is a view schematically showing deflection of a bridge. Also, the deflection of the structure 100 as shown in FIG. 6 can be calculated by using the strain rate ( x ) of the major axis of the void 220 deformed by the ellipse calculated through the above-described equation (15) (S500). The following formula (16) is obtained by applying the formula using the curvature (?) Of the strain rate (? X ) of the long axis of the void 220 deformed by the ellipse.

Figure 112015061106015-pat00016

Where κ is the curvature, and h is the distance from the neutral axis in the cross section, with the downward direction showing the (+) value and the upward direction showing the (-) value. If the above-described expression (16) is summarized on the basis of the curvature, it can be summarized as the following expression (17).

Figure 112015061106015-pat00017

Further, the curvature? Can be calculated through the following equation (18).

Figure 112015061106015-pat00018

Here, p represents the curvature radius. The differential equation of Equation (18) is summarized using the boundary condition of the structure as shown in the following Equation (19).

Figure 112015061106015-pat00019

Here, 隆 represents deflection of the structure (bridge) 100. Using the above equation (19), the deflection (delta) of the structure (bridge) 100 can be calculated. Thus, using the above-described formulas, it is possible to calculate the stresses and deflections acting at all points of the installed structure 100 without destroying the structure 100.

At this time, in order to calculate the stress and deflection acting on the structure 100 more accurately, the values of the stresses and deflections calculated through the plurality of voids 200 are calculated, and the average value of the stresses and deflections is calculated from the stress and deflection .

As described above, those skilled in the art will understand that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

100: Structure
200: air gap
210: Circular pore (pre-deformation pore)
220: voids deformed by ellipses

Claims (6)

A photographing step of photographing one side of the structure;
A void checking step of confirming voids in the image photographed in the photographing step; And
As the liquid material is cured during the manufacturing process of the structure, the air or gas inside the structure becomes spherical due to the surface tension, and the pore formed by the deformation of the structure due to the deformation of the structure over time, A deformation amount calculation step of calculating a deformation amount;
Wherein the method comprises the steps of: delete The method according to claim 1,
Wherein the void checking step comprises:
An image extracting step of extracting voids from the image; And
A radial measuring step of measuring a major axis and a minor axis value of the void modified by the ellipse;
Wherein the method comprises the steps of: The deflection measuring method according to claim 1 or 3,
Further comprising a deflection measurement step of measuring a deflection of the structure using the strain of the void calculated in the deflection calculation step. The stress measuring method according to claim 1 or 3,
And a stress measuring step of measuring a stress of the structure based on the strain of the void calculated in the deformation amount calculating step. 6. The method of claim 5,
Wherein the stress is generated by repeating at least one of the photographing step, the photographing step and the stress measuring step to determine a stress generated in the structure using an average value of the calculated values.
KR1020150089563A 2015-06-24 2015-06-24 Evaluating Method of Strain Using Void Deformation, Deflection Measurement Method and Stress Measurement Method Using the Same KR101841202B1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007303916A (en) * 2006-05-10 2007-11-22 K & T Consultant:Kk Method for measuring stress of structure
JP2009236754A (en) 2008-03-27 2009-10-15 Fukuoka Prefecture Distortion measurement method, and distortion measurement system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007303916A (en) * 2006-05-10 2007-11-22 K & T Consultant:Kk Method for measuring stress of structure
JP2009236754A (en) 2008-03-27 2009-10-15 Fukuoka Prefecture Distortion measurement method, and distortion measurement system

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