CN115839878A - Method for determining deviation of cutting seam in single-seam method stress test - Google Patents

Abstract

The invention discloses a joint-cutting deviation determining method in a single-slit method stress test, which comprises the following steps: s1: performing joint cutting operation on a workpiece to be measured and determining strain measuring points, wherein the strain measuring points comprise first strain measuring points P ₁ And a second strain point P ₂ (ii) a S2: according to P ₁ And P ₂ The middle point of the connecting line is used as an original point O to establish an original coordinate system xoy; s3: establishing an offset coordinate system x 'O' y 'by taking the center of a connecting line of two end points of the long side of the kerf as an original point O'; s4: measuring a plurality of distance data from two end points of the long side of the joint-cutting to the strain measuring point; s5: and calculating the kerf deflection angle between the x axis of the original coordinate system and the x' axis of the deflection coordinate system and the kerf displacement coordinate of the origin of the deflection coordinate system in the original coordinate system according to the plurality of distance data. The invention can improve the cuttingAccuracy and efficiency of slot offset determination.

Description

Method for determining deviation of cutting seam in single seam method stress test

Technical Field

The invention relates to the technical field of stress testing, in particular to a joint-cutting deviation determining method in single-slit stress testing.

Background

The single slit method stress test is to release the stress of the part to be tested by cutting a thin slit on the surface of the material, test the strain released by the slit by 2 strain gauges which are vertically and symmetrically distributed on two sides of the slit, and finally calculate the working stress of the material according to the test strain. In actual test, the center of the cutting seam is not necessarily exactly located at the strain measuring point P ₁ 、P ₂ Midpoint O of line and P ₁ P ₂ Maintaining perpendicularity, this positional deviation can result in stress testing errors.

Disclosure of Invention

The invention aims to provide a kerf deviation determination method in a single-slit method stress test, which can improve the accuracy and efficiency of kerf deviation determination.

The technical scheme for solving the technical problems is as follows:

the invention provides a method for determining joint-cutting deviation in a single-slit method stress test, which comprises the following steps:

s1: performing joint cutting operation on a workpiece to be measured and determining strain measuring points, wherein the strain measuring points comprise first strain measuring points P ₁ And a second strain point P ₂ ；

S2: according to the first strain measuring point P ₁ And said second strain measurement point P ₂ The middle point of the connecting line is used as an original point O to establish an original coordinate system xoy;

s3: establishing an offset coordinate system x 'O' y 'by taking the center of a connecting line of two end points of the long side of the kerf as an original point O';

s4: measuring a plurality of distance data from two end points of the long side of the joint-cutting to the strain measuring point;

s5: and calculating a kerf deflection angle between the x axis of the original coordinate system and the x' axis of the deflection coordinate system and a kerf displacement coordinate of the origin of the deflection coordinate system under the original coordinate system according to the plurality of distance data.

Optionally, in the step S4, the two end points of the long side of the slit include a slit end point D ₁ And a kerf end point D ₂ A plurality of said distance data including said kerf end point D ₁ And the first strain measuring point P ₁ A distance l of ₁₁ And the second strain measuring point P ₂ A distance l ₁₂ And the kerf end point D ₂ And the first strain measuring point P ₁ A distance l of ₂₁ And the second strain measuring point P ₂ A distance l of ₂₂ 。

Optionally, the step S5 includes:

s51: determining the first strain measuring point P by utilizing the trigonometric cosine theorem under the original coordinate system ₁ And the kerf end point D ₁ Of (2) a connection line

Angle gamma with y axis ₁ The first strain measuring point P ₁ And the kerf end point D ₂ In conjunction with a connecting line>

Angle gamma with y axis ₂ And & ->

And &>

Angle gamma therebetween ₃ ；

S52: if the angle is gamma ₁ The angle of inclusion gamma ₂ And said angle γ ₃ If the preset condition is satisfied, the step S53 is entered; otherwise, the deviation of the cutting joint position is overlarge;

s53: according to the angle gamma ₁ The angle gamma ₂ The angle gamma ₃ And the first strain gauge point P ₁ And the second strain measuring point P ₂ The distance between the joint and the cutting joint is calculated to obtain the joint cutting end point D under the original coordinate system ₁ And a kerf end point D ₂ The coordinates of (a);

s54: according to the kerf end point D ₁ And the kerf end point D ₂ Calculating to obtain the coordinate of the origin O 'in the original coordinate system, wherein the coordinate of the origin O' in the original coordinate system is the joint-cutting displacement coordinate of the origin of the offset coordinate system in the original coordinate system;

s55: according to the coordinate of the origin O' in the original coordinate system and the included angle gamma ₁ And the angle gamma ₂ And obtaining the kerf deflection angle.

Optionally, in step S51, the included angle γ is ₁ Comprises the following steps:

the included angle gamma ₂ Comprises the following steps:

the included angle gamma ₃ Comprises the following steps:

wherein l ₁₁ Is the kerf end point D ₁ And a first strain point P ₁ A distance of l ₁₂ Is a kerf end point D ₁ And a second strain measurement point P ₂ A distance of l ₂₁ Is a kerf end point D ₂ And a first strain point P ₁ A distance of l ₂₂ Is a kerf end point D ₂ And a second strain measurement point P ₂ H is the first strain point P ₁ And a second strain measurement point P ₂ A is a kerf end point D ₁ And a kerf end point D ₂ Is an inverse cosine function.

Optionally, in step S52, the preset conditions are:

γ ₃ ≥γ ₁ +γ ₂

wherein, γ ₁ A first strain measuring point P under the original coordinate system ₁ And a kerf end point D ₁ Of (2) a connection line

Angle of inclination with respect to the y-axis, gamma ₂ Is a first strain measuring point P under an original coordinate system ₁ And the kerf end point D ₂ Is connected to>

Angle of inclination with respect to the y-axis, gamma ₃ Is a first strain point P ₁ And the kerf end point D ₁ Is connected to>

And a first strain point P ₁ And the kerf end point D ₂ Is connected to>

The included angle therebetween.

Optionally, in the step S54, the origin O' is a coordinate (x) in the original coordinate system _o′ ，y _o′ ) Calculated by the following way:

wherein x is _D1 Is a kerf end point D ₁ Abscissa and x of _D1 ＝-l ₁₁ sinγ ₁ ，x _D2 Is a kerf end point D ₂ Abscissa and x of _D2 ＝l ₁₂ sinγ ₂ ，y _D1 Is a kerf end point D ₁ Ordinate and y _D1 ＝l ₁₁ cosγ ₁ -h，y _D2 Is a kerf end point D ₂ Ordinate and y _D2 ＝l ₁₂ cosγ ₂ -h，l ₁₁ Is the slit end point D ₁ And a first strain point P ₁ A distance of l ₁₂ Is a kerf end point D ₁ And a second strain measurement point P ₂ H is the first strain point P ₁ And a second strain measurement point P ₂ Is half of the distance of (d), gamma ₁ Is a first strain measuring point P under an original coordinate system ₁ And a kerf end point D ₁ Of (2) a connection line

Angle of inclination with respect to the y-axis, gamma ₂ Is a first strain measuring point P under an original coordinate system ₁ And the kerf end point D ₂ Is connected to>

The angle between the y axis and the axis.

Optionally, in step S55, the kerf deflection angle θ is:

wherein sgn () represents a sign function and

y _D1 is a kerf end point D ₁ Ordinate and y _D1 ＝l ₁₁ cosγ ₁ -h，y _D2 Is a kerf end point D ₂ Ordinate and y _D2 ＝l ₁₂ cosγ ₂ H, arccos (-) is an inverse cosine function, l ₁₁ Is the slit end point D ₁ And a first strain point P ₁ A distance of l ₁₂ Is a kerf end point D ₁ And a second strain measurement point P ₂ H is the first strain point P ₁ And a second strain measurement point P ₂ A is a kerf end point D ₁ And a kerf end point D ₂ Is half the distance of (a).

The invention has the following beneficial effects:

(1) The quantitative description of the slit deviation is realized by measuring the length, namely, the slit end point (D) ₁ ，D ₂ ) And strain gauge center (P) ₁ ,P ₂ ) Distance (l) of ₁₁ ，l ₁₂ ，l ₂₁ ，l ₂₂ ) To calculate the slot offset parameter (theta, x) _o′ ，y _o′ ). The length measurement can obtain high-precision data only by a common microscale, a vernier caliper and the like, and the obtained joint cutting deviation parameters are more accurate;

(2) The invention can pass through the joint cutting end point (D) ₁ ,D ₂ ) And strain gauge center (P) ₁ ，P ₂ ) Angle (gamma) between the line and the y-axis ₁ 、γ ₂ 、γ ₃ ) According to γ ₃ Whether or not gamma is greater than or equal to ₁ +γ ₂ Judging whether the position deviation of the cutting seam exceeds the requirement of test precision or not, thereby accurately judging whether the current test is effective or not;

(3) The joint cutting deviation determining method provided by the invention can quickly and accurately determine the actual joint cutting position deviation in the single-joint method stress test, and provides a theoretical basis for further evaluating the influence of the joint cutting position deviation on the precision measurement.

Drawings

FIG. 1 is a flow chart of a method for determining joint-cutting deviation in a single-slit stress test according to the present invention;

fig. 2 is a schematic diagram of a parameter solving process under kerf deviation.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

When the single-slit stress test method is used for actual test, the center of the slit is not necessarily exactly positioned at the strain test point P ₁ 、P ₂ Midpoint O of the connecting line and

maintaining perpendicularity, this positional deviation can result in stress testing errors. If the position deviation can be quantitatively described and a stress solving theory considering the position deviation of the cutting seam is constructed, stress testing errors caused by the deviation of the cutting seam can be eliminated.

Therefore, the invention provides a method for determining kerf deviation in a single slit method stress test, which is shown in fig. 1 and comprises the following steps:

s1: performing joint cutting operation on a workpiece to be measured and determining strain measuring points, wherein the strain measuring points comprise first strain measuring points P ₁ And a second strain point P ₂ (ii) a Here, the first strain gauge point P ₁ And a second strain point P ₂ Is determined according to the stress extension direction, and the connecting line of the stress extension direction and the stress extension direction is perpendicular to the cutting seam.

S2: according to the first strain measuring point P ₁ And said second strain measurement point P ₂ The middle point of the connecting line is used as an original point O to establish an original coordinate system xoy;

s3: establishing an offset coordinate system x 'O' y 'by taking the center of a connecting line of two end points of the long edge of the joint cutter as an original point O';

referring to FIG. 2, O' is the center point of the slit after the slit is deflected, and the coordinate is (x) _o′ ,y _o′ )。

S4: measuring a plurality of distance data from two end points of the long edge of the kerf to the strain measuring point;

the two end points of the long side of the cutting seam comprise cutting seam end points D ₁ And a kerf end point D ₂ A plurality of said distance data including said kerf end point D ₁ And the first strain measuring point P ₁ A distance l of ₁₁ And the second strain measuring point P ₂ A distance l of ₁₂ And the kerf end point D ₂ And the first strain measuring point P ₁ A distance l of ₂₁ And the second strain measuring point P ₂ A distance l of ₂₂ . With particular reference to FIG. 2, D ₁ 、D ₂ Showing the two end points of the long side of the slit,

indicates the length of the incision, is>

Represents the strain gauge point spacing, < >>

In reality, the cutting seam is a slit with missing material, and the center position of the slit is difficult to be accurately determined, so that the cutting seam is shifted (x) _o′ ,y _o′ ) It is difficult to measure directly; such problems also exist with the measurement of the kerf deflection angle theta. However, the end points D of the two ends of the long side of the kerf ₁ 、D ₂ Is clearly defined, measuring point center P ₁ 、P ₂ And will typically also be marked on the strain gage. Thus cutting the end point (D) ₁ 、D ₂ ) To the measuring point (P) ₁ 、P ₂ ) The distance can be conveniently measured by means of a micrometer, a micrometer or a vernier caliper. Note D ₁ And P ₁ 、P ₂ A distance of l ₁₁ 、l ₁₂ ，D ₂ And P ₁ 、P ₂ A distance of l ₂₁ 、l ₂₂ Then theta, x characterizing the kerf position deviation _o′ And y _o′ Three parameters can be passed through ₁₁ 、l ₁₂ 、l ₂₁ 、l ₂₂ These 4 length parameters are found.

S5: and calculating a kerf deflection angle between the x axis of the original coordinate system and the x' axis of the deflection coordinate system and a kerf displacement coordinate of the origin of the deflection coordinate system under the original coordinate system according to the plurality of distance data.

Optionally, the step S5 includes:

s51: determining the first strain measuring point P by utilizing the trigonometric cosine theorem under the original coordinate system ₁ And the kerf end point D ₁ Of (2) a connection line

Angle gamma with y axis ₁ The first strain measuring point P ₁ And the kerf end point D ₂ Is connected to>

Angle gamma with y axis ₂ And & ->

And &>

Angle gamma therebetween ₃ ；

Then, the angle γ ₁ Comprises the following steps:

the included angle gamma ₂ Comprises the following steps:

the included angle gamma ₃ Comprises the following steps:

wherein l ₁₁ Is the slit end point D ₁ And a first strain point P ₁ A distance of l ₁₂ Is a kerf end point D ₁ And a second strain measurement point P ₂ A distance of l ₂₁ Is a kerf end point D ₂ And a first strain point P ₁ A distance of l ₂₂ Is a kerf end point D ₂ And a firstTwo strain measurement points P ₂ H is the first strain point P ₁ And a second strain measurement point P ₂ A is a kerf end point D ₁ And a kerf end point D ₂ Is an inverse cosine function.

S52: if the angle is gamma ₁ The angle gamma ₂ And the angle gamma ₃ If the preset condition is satisfied, the step S53 is executed; otherwise, the deviation of the cutting joint position is overlarge;

that is, when the preset condition satisfies γ ₃ ≥γ ₁ +γ ₂ By time, it is meant that even if the slot position is offset, its end point D is ₁ And D ₂ Is still located

On both sides of the base. If the position deviation is not satisfied, the position deviation of the cutting seam is too large, and the test is invalid.

S53: according to the angle gamma ₁ The angle gamma ₂ The angle gamma ₃ And the first strain gauge point P ₁ And the second strain measuring point P ₂ The distance between the two joint-cutting end points is calculated to obtain the joint-cutting end point D under the original coordinate system ₁ And a kerf end point D ₂ The coordinates of (a);

thus, D ₁ And D ₂ Coordinates (x) in the xoy coordinate system _D1 ,y _D1 )、(x _D2 ,y _D2 ) Comprises the following steps:

x _D1 ＝-l ₁₁ sinγ ₁ ,y _D1 ＝l ₁₁ cosγ ₁ -h

x _D2 ＝l ₁₂ sinγ ₂ ,y _D2 ＝l ₁₂ cosγ ₂ -h

s54: according to the joint cutting end point D ₁ And the kerf end point D ₂ Calculating to obtain the coordinate of the origin O 'in the original coordinate system, wherein the coordinate of the origin O' in the original coordinate system is the joint-cutting displacement coordinate of the origin of the offset coordinate system in the original coordinate system;

known as D ₁ And D ₂ Is determined by the coordinate of (a) in the space,the coordinates of its center point O' can be expressed as:

wherein x is _D1 Is a kerf end point D ₁ Abscissa and x of _D1 ＝-l ₁₁ sinγ ₁ ，x _D2 Is a kerf end point D ₂ Abscissa and x of _D2 ＝l ₁₂ sinγ ₂ ，y _D1 Is a kerf end point D ₁ Ordinate and y _D1 ＝l ₁₁ cosγ ₁ -h，y _D2 Is a kerf end point D ₂ Ordinate and y _D2 ＝l ₁₂ cosγ ₂ -h，l ₁₁ Is the slit end point D ₁ And a first strain point P ₁ A distance of l ₁₂ Is a kerf end point D ₁ And a second strain measurement point P ₂ H is the first strain point P ₁ And a second strain measurement point P ₂ Is half of the distance of (d), gamma ₁ Is a first strain measuring point P under an original coordinate system ₁ And a kerf end point D ₁ Of (2) a connection line

Angle of inclination with the y-axis, gamma ₂ Is a first strain measuring point P under an original coordinate system ₁ And the kerf end point D ₂ Is connected to>

The angle between the y axis and the axis.

S55: according to the coordinate of the origin O' in the original coordinate system and the included angle gamma ₁ And the angle gamma ₂ And obtaining the kerf deflection angle.

Referring to fig. 2, the kerf deflection angle θ satisfies:

accordingly, the kerf deflection angle θ can be obtained as follows:

wherein sgn () represents a sign function and

y _D1 is a kerf end point D ₁ Ordinate and y _D1 ＝l ₁₁ cosγ ₁ -h，y _D2 Is a kerf end point D ₂ Ordinate and y _D2 ＝l ₁₂ cosγ ₂ H, arccos (-) is an inverse cosine function, l ₁₁ Is the kerf end point D ₁ And a first strain point P ₁ A distance of l ₁₂ Is a kerf end point D ₁ And a second strain measurement point P ₂ H is the first strain point P ₁ And a second strain measurement point P ₂ A is a kerf end point D ₁ And a kerf end point D ₂ Is half the distance of (a).

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (7)

1. A method for determining joint-cutting deviation in a single-slit method stress test is characterized by comprising the following steps:

s1: performing joint cutting operation on a workpiece to be measured and determining strain measuring points, wherein the strain measuring points comprise first strain measuring points P ₁ And a second strain point P ₂ ；

S2: according to the first strain measuring point P ₁ And said second strain measurement point P ₂ The middle point of the connecting line is used as an original point O to establish an original coordinate system xoy;

s3: establishing an offset coordinate system x 'O' y 'by taking the center of a connecting line of two end points of the long side of the kerf as an original point O';

s4: measuring a plurality of distance data from two end points of the long side of the joint-cutting to the strain measuring point;

s5: and calculating a kerf deflection angle between the x axis of the original coordinate system and the x' axis of the deflection coordinate system and a kerf displacement coordinate of the origin of the deflection coordinate system under the original coordinate system according to the plurality of distance data.

2. The method as claimed in claim 1, wherein the kerf displacement determination method in the single kerf stress test is characterized in that in the step S4, two end points of the long edge of the kerf comprise kerf end points D ₁ And a kerf end point D ₂ A plurality of said distance data including said kerf end point D ₁ And the first strain measuring point P ₁ A distance l of ₁₁ And the second strain measuring point P ₂ A distance l of ₁₂ And the kerf end point D ₂ And the first strain measuring point P ₁ A distance l of ₂₁ And the second strain measuring point P ₂ A distance l ₂₂ 。

3. The method for determining kerf displacement in single slit stress testing as claimed in claim 2, wherein said step S5 comprises:

s51: determining the first strain measuring point P by utilizing the trigonometric cosine theorem under the original coordinate system ₁ And the kerf end point D ₁ Of (2) a connection line

Angle gamma with y axis ₁ The first strain measuring point P ₁ And the kerf end point D ₂ Of (2) a connection line

Angle gamma with y axis ₂ And an

And

angle gamma therebetween ₃ ；

S52: if it is as describedIncluded angle gamma ₁ The angle gamma ₂ And the angle gamma ₃ If the preset condition is satisfied, the step S53 is entered; otherwise, the deviation of the cutting joint position is overlarge;

s53: according to the angle gamma ₁ The angle gamma ₂ The angle of inclusion gamma ₃ And the first strain gauge point P ₁ And the second strain measuring point P ₂ The distance between the joint and the cutting joint is calculated to obtain the joint cutting end point D under the original coordinate system ₁ And a kerf end point D ₂ The coordinates of (a);

s54: according to the joint cutting end point D ₁ And the kerf end point D ₂ Calculating to obtain the coordinate of the origin O 'in the original coordinate system, wherein the coordinate of the origin O' in the original coordinate system is the joint-cutting displacement coordinate of the origin of the offset coordinate system in the original coordinate system;

s55: according to the coordinate of the origin O' in the original coordinate system and the included angle gamma ₁ And said angle γ ₂ And obtaining the kerf deflection angle.

4. The method for determining joint-cutting offset in single slit method stress test as claimed in claim 3, wherein in step S51, the included angle γ is determined ₁ Comprises the following steps:

the included angle gamma ₂ Comprises the following steps:

the included angle gamma ₃ Comprises the following steps:

wherein l ₁₁ Is the slit end point D ₁ And first strain measurementPoint P ₁ A distance of l ₁₂ Is a kerf end point D ₁ And a second strain measurement point P ₂ A distance of l ₂₁ Is a kerf end point D ₂ And a first strain point P ₁ A distance of l ₂₂ Is a kerf end point D ₂ And a second strain measurement point P ₂ H is the first strain point P ₁ And a second strain measurement point P ₂ A is a kerf end point D ₁ And a kerf end point D ₂ Is the inverse cosine function.

5. The method for determining joint-cutting offset in a single-slit method stress test as claimed in claim 3, wherein in the step S52, the preset conditions are:

γ ₃ ≥γ ₁ +γ ₂

wherein, γ ₁ Is a first strain measuring point P under an original coordinate system ₁ And a kerf end point D ₁ Of (2) connecting wire

Angle of inclination with respect to the y-axis, gamma ₂ Is a first strain measuring point P under an original coordinate system ₁ And the kerf end point D ₂ Of (2) connecting wire

Angle of inclination with respect to the y-axis, gamma ₃ Is a first strain measurement point P ₁ And the kerf end point D ₁ Of (2) connecting wire

And a first strain point P ₁ And the kerf end point D ₂ Of (2) connecting wire

The included angle therebetween.

6. The method of claim 3, wherein in step S54, the origin O' is at the original positionCoordinates under the coordinate system (x) _o′ ，y _o′ ) Calculated by the following way:

wherein x is _D1 Is a kerf end point D ₁ Abscissa of (a) and x _D1 ＝-l ₁₁ sinγ ₁ ，x _D2 Is a kerf end point D ₂ Abscissa and x of _D2 ＝l ₁₂ sinγ ₂ ，y _D1 Is a kerf end point D ₁ Ordinate and y _D1 ＝l ₁₁ cosγ ₁ -h，y _D2 Is a kerf end point D ₂ Ordinate and y _D2 ＝l ₁₂ cosγ ₂ -h，l ₁₁ Is the slit end point D ₁ And a first strain point P ₁ A distance of l ₁₂ Is a kerf end point D ₁ And a second strain measurement point P ₂ H is the first strain point P ₁ And a second strain measurement point P ₂ Is half of the distance of (d), gamma ₁ Is a first strain measuring point P under an original coordinate system ₁ And a kerf end point D ₁ Of (2) a connection line

Angle of inclination with respect to the y-axis, gamma ₂ A first strain measuring point P under the original coordinate system ₁ And the kerf end point D ₂ Of (2) a connection line

The angle between the y axis and the axis.

7. The method for determining kerf deflection in a single kerf stress test as recited in any one of claims 3-6, wherein in step S55, the kerf deflection angle θ is:

wherein, sgn () expression symbolNumber function of and

y _D1 is a kerf end point D ₁ Ordinate and y _D1 ＝l ₁₁ cosγ ₁ -h，y _D2 Is a kerf end point D ₂ Ordinate and y _D2 ＝l ₁₂ cosγ ₂ H, arccos (-) is an inverse cosine function, l ₁₁ Is the slit end point D ₁ And a first strain point P ₁ A distance of l ₁₂ Is a kerf end point D ₁ And a second strain measurement point P ₂ H is the first strain point P ₁ And a second strain measurement point P ₂ A is a kerf end point D ₁ And a kerf end point D ₂ Is half the distance of (a).

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