Method for generating a full stress-strain curve of a metal

Abstract

The application provides a metal tensile full stress-strain curve generation method, which tests a metal sample, draws a plurality of original stress-strain curves, divides each original stress-strain curve into four parts, obtains stress values and strain deviation values of a plurality of data points in each part, takes average values of the stress values and the strain deviation values of the corresponding data points on the curves to obtain average stress values and average strain deviation values of the data points, further processes the original data, and draws an average full stress-strain curve or a minimum full stress-strain curve. The full stress-strain curve generation method can obtain the average full stress-strain curve and the minimum full stress-strain curve simultaneously, can avoid the mismatch between the slope of the original point to the proportional limit segment of the stress-strain curve and the elastic modulus and the discontinuity of the proportional limit to the yield strength segment, and can accurately and sufficiently obtain the material tensile constitutive relation to support the analysis of the super-rotation of a part and the analysis of the fracture margin.

Description

Technical Field

[0001] This invention relates to a method for generating full stress-strain curves of metal under tension. Background Technology

[0002] In the design of high-temperature equipment such as aero-engines and gas turbines, the average full stress-strain curve and the minimum full stress-strain curve are required as inputs to perform elastoplastic finite element analysis on the components, in order to support the analysis of component overspeed and fracture margin.

[0003] In the process of obtaining the full stress-strain curve data of a material under tension, the extensometer is used to track the specimen at a constant rate until the specimen fractures and fails to obtain the full stress-strain curve. How to make full use of the obtained stress-strain data is of great significance.

[0004] In existing technologies, the stress-strain curve is divided into two parts: before yielding and after yielding. Material constitutive models are established for each part to obtain the full stress-strain curve. However, this method has drawbacks such as insufficient utilization of curve data, weak model versatility, and inability to obtain the minimum full stress-strain curve. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of insufficient utilization of curve data, weak model universality, and inability to obtain minimum full stress-strain curve in the prior art. The present invention provides a method for generating full stress-strain curve of metal tension, which has the advantages of sufficient data utilization, wide applicability of model, and the ability to obtain minimum full stress-strain curve.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution:

[0007] This invention provides a method for generating full stress-strain curves of metal under tension, characterized in that the generation method includes:

[0008] S1. Perform a tensile test on the metal specimen until the metal specimen breaks, obtain the original data, and plot multiple original stress-strain curves.

[0009] S2. Process each of the original stress-strain curves, dividing the original stress-strain curves into four parts: a first part, a second part, a third part, and a fourth part. The first part extends from the origin to the proportional limit PL; the second part extends from the proportional limit PL to the yield strength TYS; the third part extends from the yield strength TYS to the tensile strength TUS; and the fourth part extends from the tensile strength TUS to the fracture stress FS. Calculate the modulus of the first part of each of the original stress-strain curves.

[0010] S3. Take several data points on each of the four parts and calculate the stress value and strain deviation value of each data point.

[0011] S4. Take the arithmetic mean of the stress value and strain deviation value of the corresponding data point on each of the original stress-strain curves to obtain the average stress value σ of the data point. A and mean strain deviation D A ;

[0012] S5. Further process the raw data and plot the average total stress-strain curve or the minimum total stress-strain curve.

[0013] In this technical solution, a tensile test is performed on the metal sample, and the obtained original stress-strain curves are divided into four parts. Several data points are taken from each part for further processing to obtain the final required curve. This ensures that the data of each part of the curve are effectively utilized, improves the accuracy of the final curve, and allows the minimum total stress-strain curve to be plotted.

[0014] Preferably, if the plotted curve is an average total stress-strain curve, then steps S51 to S54 are performed:

[0015] S51. Calculate the average proportional limit and average fracture stress of the metal specimen.

[0016] S52. Calculate the average stress at each of the data points;

[0017] S53. Calculate the average total strain for each of the data points;

[0018] S54. Based on the average stress and average total strain of each data point, plot the average total stress-strain curve.

[0019] In this technical solution, the average stress and average total strain of each data point are corrected by calculating the average proportional limit and average fracture stress, thereby improving the accuracy of the final plotted curve.

[0020] Preferably, if the plotted curve is the minimum total stress-strain curve, then proceed to steps S55 to S58:

[0021] S55. Calculate the minimum proportional limit and minimum fracture stress of the metal specimen;

[0022] S56. Calculate the minimum stress for each of the data points;

[0023] S57. Calculate the minimum total strain for each of the data points;

[0024] S58. Based on the minimum stress and minimum total strain of each data point, plot the minimum total stress-strain curve.

[0025] In this technical solution, the minimum stress and minimum total strain of each data point are corrected by calculating the minimum proportional limit and minimum fracture stress, thereby improving the accuracy of the final plotted curve.

[0026] Preferably, step S2 includes the following steps:

[0027] S21. Determine the maximum stress value of the given test record;

[0028] S22. Determine the initial upper limit value of the first portion of each of the original stress-strain curves;

[0029] S23. Determine the initial lower limit value of the first portion of each of the original stress-strain curves;

[0030] S23. Perform linear regression using the data between the initial upper limit value and the initial lower limit value to obtain the initial slope of the first part of the original stress-strain curve;

[0031] S24. Calculate the temporary yield strength using the initial slope;

[0032] S25. Using the temporary yield strength, calculate the final upper limit value of the first part of the original stress-strain curve;

[0033] S26. Using the final upper limit value, calculate the final lower limit value of the first part of the original stress-strain curve;

[0034] S27. Perform linear regression using the data between the final upper limit value and the final lower limit value to obtain the modulus estimate of the first part of the original stress-strain curve;

[0035] S28. For each of the original stress-strain curves, the proportional limit is obtained based on the estimated modulus value.

[0036] In this technical solution, the proportional limit value on the original stress-strain curve is obtained by processing the original data, which makes the division of the four parts of the curve more accurate, improves the accuracy of the curve, and avoids the mismatch between the slope and elastic modulus of the first part of the original stress-strain curve.

[0037] Preferably, step S3 includes the following steps:

[0038] S31. Take n1 data points from the second part, n2 data points from the third part, and n3 data points from the fourth part;

[0039] S32. If the data point is on the second part, then the stress value of the data point... In the formula, a1 is a given first coefficient; at the same time, the strain deviation value D from the extension line of the modulus to the original stress-strain curve is measured; there are n1 first coefficients a1, which are the values ​​of each endpoint of the interval after dividing the numerical interval (0, 100] into n1 equal parts;

[0040] S33. If the data point is on the third part, then the stress value of the data point... In the formula, a2 is a given second coefficient, and the strain deviation value D from the extension line of the modulus to the original stress-strain curve is measured. There are n2 second coefficients a2, which are the values ​​of each endpoint of the interval after dividing the numerical interval (0, 100] into n2 equal parts.

[0041] S34. If the data point is on the fourth part, then the stress value of the data point... In the second formula, a3 is a given third coefficient, and the strain deviation value D from the extension line of the modulus to the original stress-strain curve is measured. There are n3 third coefficients a3, which are the values ​​of each endpoint of the interval after the numerical interval (0, 100] is divided into n3 equal parts.

[0042] In this technical solution, by taking several data points on the original stress-strain curve and correcting them with coefficients, a more accurate stress value is obtained, and the strain deviation value is obtained at the same time, which facilitates subsequent data processing and avoids the discontinuity of the curve between the proportional limit and the yield strength.

[0043] Preferably, step S51 includes the following steps:

[0044] S511, the aforementioned average ratio limit:

[0045] σ T (PL)=(TYS Prod.Avg. / TYS Avg. )×σ Avg. (PL)

[0046] In the formula TYS Avg. σ is the average yield strength measured on each of the original stress-strain curves. Avg. (PL) is the average value of the proportional limits on each of the original stress-strain curves, and TYS Prod.Avg. The average yield strength value of the product is given in advance;

[0047] S512, the average fracture stress:

[0048] σ T (FS)=(TUS Prod.Avg. / TUS Avg. )×σ Avg. (FS)

[0049] TUS in the formula Avg. σ is the average value of the tensile strength on each of the original stress-strain curves. Avg. (FS) is the average value of the fracture stress on each of the original stress-strain curves, and TUS is the average value of the fracture stress. Prod.Avg. The average tensile strength value of the product is given in advance.

[0050] In this technical solution, by calculating the average proportional limit and average fracture stress, a correction function can be played in the subsequent data processing, thereby improving the accuracy of the plotted curve.

[0051] Preferably, step S52 includes the following steps:

[0052] S521. If the data point is on the second part, then the average stress is:

[0053] σ T =σ T (PL) + a1% × (TYS) Prod.Avg. -σ T (PL));

[0054] S522. If the data point is located on the third part, then the average stress is:

[0055] σ T =TYS Prod.Avg. +a2%×(TUS Prod.Avg. -TYS Prod.Avg. );

[0056] S523. If the data point is located on the fourth part, then the average stress is:

[0057] σ T =σ T (FS) + a3% × (TUS) Prod.Avg. -σ T (FS)).

[0058] In this technical solution, different formulas and coefficients are used to process data points in different parts, so that the obtained average stress value can be corrected and the accuracy of the plotted curve can be improved.

[0059] Preferably, step S53 includes the following steps:

[0060] S531. If the data point is on the second part, then the average plastic strain is:

[0061]

[0062] In the formula δ Prod.Avg.Elong. For a pre-defined average elongation of the product, D A atFractureStress is the average strain deviation value at which the metal specimen fractures;

[0063] S532. If the data points are located in the third or fourth part, then the average plastic strain is:

[0064]

[0065] S533, the average elastic strain of the data points:

[0066]

[0067] In the formula, E is the pre-given elastic modulus of the product;

[0068] S534. Add the average plastic strain and the average elastic strain to obtain the average total strain.

[0069] In this technical solution, the average plastic strain value is obtained by using different formulas for data points in different parts of the curve, so that the obtained average plastic strain value is more in line with the actual situation.

[0070] Preferably, step S55 includes the following steps:

[0071] S551, the minimum proportional limit:

[0072] σ T (PL) min =(TYS Prod.min. / TYS Avg. )×σ Avg. (PL)

[0073] In the formula TYS Avg. σ is the average yield strength measured on each of the original stress-strain curves. Avg. (PL) is the average value of the proportional limits on each of the original stress-strain curves, and TYS Prod.min. The minimum yield strength value of the product is given in advance;

[0074] S552, the minimum fracture stress:

[0075] σ T (FS) min =(TUSProd.min. / TUS Avg. )×σ Avg. (FS)

[0076] TUS in the formula Avg. σ is the average value of the tensile strength on each of the original stress-strain curves. Avg. (FS) is the average value of the fracture stress on each of the original stress-strain curves, and TUS is the average value of the fracture stress. Prod.min. This is the minimum tensile strength value of the product given in advance.

[0077] In this technical solution, by calculating the minimum proportional limit and the minimum fracture stress, a correction function can be played in the subsequent data processing, thereby improving the accuracy of the plotted curve.

[0078] Preferably, step S56 includes the following steps:

[0079] S561. If the data point is on the second part, then the minimum stress is:

[0080]

[0081] S562. If the data point is on the third part, then the minimum stress is:

[0082]

[0083] S563. If the data point is on the fourth part, then the minimum stress is:

[0084]

[0085] In this technical solution, different formulas and coefficients are used to process data points in different parts, so that the obtained minimum stress value can be corrected and the accuracy of the plotted curve can be improved.

[0086] Preferably, step S57 includes the following steps:

[0087] S571. If the data point is on the second part, then the minimum plastic strain is:

[0088]

[0089] In the formula δ Prod.min.Elong. The minimum elongation of the product is given in advance;

[0090] S572. If the data point is located in the third or fourth part, then the minimum plastic strain is:

[0091]

[0092] S573, Minimum elastic strain of the data point:

[0093]

[0094] S574. Add the minimum plastic strain and the minimum elastic strain to obtain the minimum total strain.

[0095] In this technical solution, the minimum plastic strain value is obtained by using different formulas for data points in different parts of the curve, so that the obtained minimum plastic strain value is more in line with the actual situation.

[0096] Preferably, when performing step S5, in the first part, the origin and the proportional limit are connected by a straight line; in the second, third and fourth parts, adjacent data points are connected by straight lines; the number of data points is greater than 100.

[0097] In this technical solution, a large number of data points are taken on the curve, resulting in more refined data and higher accuracy of the drawn curve.

[0098] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0099] The positive and progressive effects of this invention are as follows:

[0100] The aforementioned method for generating full stress-strain curves for metal tension, based on a large amount of raw data, can simultaneously obtain both the average full stress-strain curve and the minimum full stress-strain curve. Dividing the curve into four parts for processing significantly improves its quality and accuracy, especially for materials with a large difference between the proportional limit and yield strength. Furthermore, it proposes a method for processing the minimum stress-strain curve for the first time, generating the minimum full stress-strain curve. In addition, it effectively avoids problems such as mismatch between the slope and elastic modulus in the segment from the origin to the proportional limit, and discontinuity in the segment from the proportional limit to the yield strength. Through this method, the tensile constitutive relationship of the material can be accurately and fully obtained to support analyses such as component overrun analysis and fracture margin. Attached Figure Description

[0101] Figure 1 This is a schematic diagram of the average total stress-strain curve and the minimum total stress-strain curve plotted according to the metal tensile total stress-strain curve generation method given in this invention embodiment. Detailed Implementation

[0102] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0103] like Figure 1 The illustration shows an embodiment of the method for generating a full stress-strain curve of a metal under tensile stress according to the present invention. This method includes the following steps:

[0104] S1. Perform a tensile test on the metal specimen until the metal specimen breaks, obtain the original data, and plot multiple original stress-strain curves.

[0105] S2. Process each original stress-strain curve, dividing it into four parts: Part 1, Part 2, Part 3, and Part 4. Part 1 extends from the origin to the proportional limit PL; Part 2 extends from the proportional limit PL to the yield strength TYS; Part 3 extends from the yield strength TYS to the tensile strength TUS; and Part 4 extends from the tensile strength TUS to the fracture stress FS. Calculate the modulus of the first part of each original stress-strain curve.

[0106] S3. Take several data points on each of the four parts and calculate the stress value and strain deviation value of each data point.

[0107] S4. Take the arithmetic mean of the stress value and strain deviation value of the corresponding data points on each original stress-strain curve to obtain the average stress value σ of the data points. A and mean strain deviation D A ;

[0108] S5. Further process the raw data to plot the average total stress-strain curve or the minimum total stress-strain curve. By conducting tensile tests on metal specimens, the obtained multiple raw stress-strain curves are divided into four parts. Several data points are taken from each part for further processing to obtain the final required curve. This ensures that the data from each part of the curve is effectively utilized, improves the accuracy of the final plotted curve, and allows for the plotting of the minimum total stress-strain curve.

[0109] If the plotted curve is an average total stress-strain curve, then proceed with steps S51 to S54:

[0110] S51. Calculate the average proportional limit and average fracture stress of the metal specimen.

[0111] S52. Calculate the average stress at each data point;

[0112] S53. Calculate the average total strain for each data point;

[0113] S54. Based on the average stress and average total strain of each data point, plot the average total stress-strain curve. By calculating the average proportional limit and average fracture stress, the average stress and average total strain of each data point are corrected, thereby improving the accuracy of the final plotted curve.

[0114] If the plotted curve is the minimum total stress-strain curve, then proceed with steps S55 to S58:

[0115] S55. Calculate the minimum proportional limit and minimum fracture stress of the metal specimen.

[0116] S56. Calculate the minimum stress for each data point;

[0117] S57. Calculate the minimum total strain for each data point;

[0118] S58. Based on the minimum stress and minimum total strain at each data point, plot the minimum total stress-strain curve. By calculating the minimum proportional limit and minimum fracture stress, the minimum stress and minimum total strain at each data point are corrected, thus improving the accuracy of the final plotted curve.

[0119] Step S2 includes the following steps:

[0120] S21. Determine the maximum stress value of the given test record;

[0121] S22. Determine the initial upper limit value of the first part of each original stress-strain curve. The initial upper limit value = 0.5 × the maximum stress value.

[0122] S23. Determine the initial lower limit value of the first part of each original stress-strain curve. The initial lower limit value = 0.3 × the initial upper limit value.

[0123] S23. Perform linear regression using the data between the initial upper limit and the initial lower limit to obtain the initial slope of the first part of the original stress-strain curve.

[0124] S24. Using the initial slope, offset 0.2% from the origin of the original curve, and draw a straight line with the initial slope as the slope. The intersection of this straight line and the original curve is the temporary yield strength.

[0125] S25. Using the temporary yield strength, calculate the final upper limit of the first part of the original stress-strain curve. The final upper limit = 0.6 × temporary yield strength.

[0126] S26. Using the final upper limit value, calculate the final lower limit value of the first part of the original stress-strain curve. The final lower limit value = 0.3 × the final upper limit value.

[0127] S27. Perform linear regression on the data between the final upper limit and the final lower limit to obtain the modulus estimate of the first part of the original stress-strain curve.

[0128] S28. For each original stress-strain curve, based on the modulus estimate, offset 0.01% from the origin of the original curve and draw a straight line with the modulus estimate as the slope. The intersection of this straight line and the original curve is the proportional limit PL. If the straight line intersects the original curve at multiple points, the first intersection point is taken as the proportional limit.

[0129] In this technical solution, the proportional limit value on the original stress-strain curve is obtained by processing the original data, which makes the division of the four parts of the curve more accurate, improves the accuracy of the curve, and avoids the mismatch between the slope and elastic modulus of the first part of the original stress-strain curve.

[0130] Step S3 includes the following steps:

[0131] S31. Take n1 data points in the second part, n2 data points in the third part, and n3 data points in the fourth part;

[0132] S32. If the data point is on the second part, then the stress value of the data point... In the formula, a1 is a given first coefficient; at the same time, the strain deviation value D from the extension line of the modulus to the original stress-strain curve is measured; there are n1 first coefficients a1, which are the values ​​of each endpoint of the interval after dividing the numerical interval (0, 100] into n1 equal parts;

[0133] S33. If the data point is on the third part, then the stress value of the data point... In the formula, a2 is a given second coefficient, and the strain deviation value D from the extension line of the modulus to the original stress-strain curve is measured at the same time; there are n2 second coefficients a2, which are the values ​​of each endpoint of the interval after dividing the numerical interval (0, 100] into n2 equal parts;

[0134] S34. If the data point is on the fourth part, then the stress value of the data point... In the formula, a3 is a given third coefficient, and the strain deviation value D from the extension line of the modulus to the original stress-strain curve is measured. There are n3 third coefficients a3, which are the values ​​of each endpoint of the interval after dividing the numerical interval (0, 100] into n3 equal parts.

[0135] By taking several data points on the original stress-strain curve and correcting them with coefficients, a more accurate stress value is obtained, and the strain deviation value is also obtained, which facilitates subsequent data processing and avoids the discontinuity of the curve between the proportional limit and the yield strength.

[0136] Step S51 includes the following steps:

[0137] S511, Average Proportional Limit:

[0138] σ T (PL)=(TYS Prod.Avg. / TYS Avg. )×σ Avg. (PL)

[0139] In the formula TYS Avg. σ is the average yield strength on each of the original stress-strain curves. Avg. (PL) is the average of the proportional limits on each of the original stress-strain curves, and TYS Prod.Avg. The average yield strength value of the product is given in advance;

[0140] S512, Average Fracture Stress:

[0141] σ T (FS)=(TUS Prod.Avg. / TUS Avg. )×σ Avg. (FS)

[0142] TUS in the formula Avg. σ is the average tensile strength on each of the original stress-strain curves. Avg. (FS) is the average value of the fracture stress on each of the original stress-strain curves, and TUS is the average value of the fracture stress. Prod.Avg. This represents the pre-defined average tensile strength value of the product. Calculating the average proportional limit and average fracture stress can serve as a correction in subsequent data processing, improving the accuracy of the plotted curves.

[0143] Step S52 includes the following steps:

[0144] S521. If the data point is in the second part, then the average stress is:

[0145] σ T =σ T (PL) + a1% × (TYS) Prod.Avg. -σ T (PL));

[0146] S522. If the data point is in the third part, then the average stress is:

[0147] σ T =TYS Prod.Avg. +a2%×(TUS Prod.Avg. -TYS Prod.Avg. );

[0148] S523. If the data point is in the fourth part, then the average stress is:

[0149] σ T =σT (FS) + a3% × (TUS) Prod.Avg. -σ T (FS)). Different formulas and coefficients are used to process different data points to correct the obtained average stress value and improve the accuracy of the plotted curve.

[0150] Step S53 includes the following steps:

[0151] S531. If the data points are in the second part, then the average plastic strain is:

[0152]

[0153] In the formula δ Prod.Avg.Elong. For a pre-defined average elongation of the product, D A atFractureStress is the average strain deviation value when the metal specimen fractures;

[0154] S532. If the data point is in the third or fourth part, then the average plastic strain is:

[0155]

[0156] S533, Average elastic strain of data points:

[0157]

[0158] In the formula, E is the pre-given elastic modulus of the product;

[0159] S534. Add the average plastic strain and the average elastic strain to obtain the average total strain. Use different formulas to calculate the average plastic strain value for data points in different parts of the curve, so that the obtained average plastic strain value is more consistent with the actual situation.

[0160] Step S55 includes the following steps:

[0161] S551, Minimum Proportional Limit:

[0162] σ T (PL) min =(TYS Prod.min. / TYS Avg. )×σ Avg. (PL)

[0163] In the formula TYS Avg. σ is the average yield strength on each of the original stress-strain curves. Avg. (PL) is the average of the proportional limits on each of the original stress-strain curves, and TYS Prod.min. The minimum yield strength value of the product is given in advance;

[0164] S552, Minimum Fracture Stress:

[0165] σ T (FS) min =(TUS Prod.min. / TUS Avg. )×σ Avg. (FS)

[0166] TUS in the formula Avg. σ is the average tensile strength on each of the original stress-strain curves. Avg. (FS) is the average value of the fracture stress on each of the original stress-strain curves, and TUS is the average value of the fracture stress. Prod.min. This represents the minimum tensile strength value of the product, given in advance. Calculating the minimum proportional limit and minimum breaking stress can serve as a correction in subsequent data processing, improving the accuracy of the plotted curves.

[0167] Step S56 includes the following steps:

[0168] S561. If the data point is in the second part, then the minimum stress is:

[0169]

[0170] S562. If the data point is on the third part, then the minimum stress is:

[0171]

[0172] S563. If the data point is on the fourth part, then the minimum stress is:

[0173] Different formulas and coefficients are used to process data points in different parts, so that the obtained minimum stress value can be corrected, thereby improving the accuracy of the plotted curve.

[0174] Step S57 includes the following steps:

[0175] S571. If the data point is in the second part, then the minimum plastic strain is:

[0176]

[0177] In the formula δ Prod.min.Elong. The minimum elongation of the product is given in advance;

[0178] S572. If the data point is in the third or fourth part, then the minimum plastic strain is:

[0179]

[0180] S573, Minimum elastic strain at data points:

[0181]

[0182] S574. Add the minimum plastic strain and the minimum elastic strain to obtain the minimum total strain. Use different formulas to calculate the minimum plastic strain value for different data points on different parts of the curve, so that the obtained minimum plastic strain value is more consistent with the actual situation.

[0183] In step S5, in the first part, a straight line is used to connect the origin and the proportional limit; in the second, third, and fourth parts, straight lines are used to connect adjacent data points; the number of data points is greater than 100. The large number of data points taken on the curve results in more refined data and a more accurate curve.

[0184] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for generating a full stress-strain curve of a metal under tension, characterized in that, The generation method includes: S1. Perform a tensile test on the metal specimen until the metal specimen breaks, obtain the original data, and plot multiple original stress-strain curves. S2. Process each of the original stress-strain curves, dividing the original stress-strain curves into four parts: a first part, a second part, a third part, and a fourth part. The first part extends from the origin to the proportional limit PL; the second part extends from the proportional limit PL to the yield strength TYS; the third part extends from the yield strength TYS to the tensile strength TUS; and the fourth part extends from the tensile strength TUS to the fracture stress FS. Calculate the modulus of the first part of each of the original stress-strain curves. S3. Take several data points on each of the four parts and calculate the stress value and strain deviation value of each data point. S4. Take the arithmetic mean of the stress value and strain deviation value of the corresponding data point on each of the original stress-strain curves to obtain the average stress value of the data point. σ A and mean strain deviation D A ; S5. Further process the raw data and plot the average total stress-strain curve or the minimum total stress-strain curve. If the plotted curve is an average total stress-strain curve, then proceed with steps S51~S54: S51. Calculate the average proportional limit and average fracture stress of the metal specimen. S52. Calculate the average stress at each of the data points; S53. Calculate the average total strain for each of the data points; S54. Based on the average stress and average total strain of each data point, plot the average total stress-strain curve; Step S51 includes the following steps: S511, the aforementioned average ratio limit: In the formula The average yield strength is the value of the measured original stress-strain curves. The average value of the proportional limit on each of the original stress-strain curves obtained. The average yield strength value of the product is given in advance; S512, the average fracture stress: In the formula The tensile strength is the average value of the measured original stress-strain curves. The average value of the fracture stress on each of the original stress-strain curves is calculated. The average tensile strength value of the product given in advance; Step S53 includes the following steps: S531. If the data point is on the second part, then the average plastic strain is: In the formula Given the average elongation of the product in advance, This is the average strain deviation value at the time of fracture of the metal specimen; S532. If the data points are located in the third or fourth part, then the average plastic strain is: ； S533, the average elastic strain of the data points: In the formula Given the elastic modulus of the product in advance, The average stress at the data points; S534. Add the average plastic strain and the average elastic strain to obtain the average total strain.

2. The curve generation method as described in claim 1, characterized in that, If the plotted curve is the minimum total stress-strain curve, then proceed to steps S55~S58: S55. Calculate the minimum proportional limit and minimum fracture stress of the metal specimen; S56. Calculate the minimum stress for each of the data points; S57. Calculate the minimum total strain for each of the data points; S58. Based on the minimum stress and minimum total strain of each data point, plot the minimum total stress-strain curve.

3. The curve generation method as described in claim 1, characterized in that, Step S2 includes the following steps: S21. Determine the maximum stress value of the given test record; S22. Determine the initial upper limit value of the first portion of each of the original stress-strain curves; S23. Determine the initial lower limit value of the first portion of each of the original stress-strain curves; S23. Perform linear regression using the data between the initial upper limit value and the initial lower limit value to obtain the initial slope of the first part of the original stress-strain curve; S24. Calculate the temporary yield strength using the initial slope; S25. Using the temporary yield strength, calculate the final upper limit value of the first part of the original stress-strain curve; S26. Using the final upper limit value, calculate the final lower limit value of the first part of the original stress-strain curve; S27. Perform linear regression using the data between the final upper limit value and the final lower limit value to obtain the modulus estimate of the first part of the original stress-strain curve; S28. For each of the original stress-strain curves, the proportional limit is obtained based on the estimated modulus value.

4. The curve generation method as described in claim 1, characterized in that, Step S3 includes the following steps: S31, Take from the second part The data points mentioned above, taken from the third part The data points mentioned above, taken from the fourth part The data points mentioned above; S32. If the data point is on the second part, then the stress value of the data point... In the formula Given a first coefficient; simultaneously measure the strain deviation D from the extension of the modulus to the original stress-strain curve; the first coefficient have , in order, will (0, 100) The numerical ranges are all divided into After division, the values ​​of each endpoint on the interval; S33. If the data point is on the third part, then the stress value of the data point... In the formula For a given second coefficient, the strain deviation D from the extension of the modulus to the original stress-strain curve is simultaneously measured; the second coefficient have , in order, will (0, 100) The numerical ranges are all divided into After division, the values ​​of each endpoint on the interval; S34. If the data point is on the fourth part, then the stress value of the data point... In the second formula For a given third coefficient, the strain deviation D from the extension of the modulus to the original stress-strain curve is simultaneously measured; the third coefficient have , in order, will (0, 100) The numerical ranges are all divided into After that, the values ​​of each endpoint on the interval.

5. The curve generation method as described in claim 1, characterized in that, Step S52 includes the following steps: S521. If the data point is on the second part, then the average stress is: S522. If the data point is located on the third part, then the average stress is: ； S523. If the data point is located on the fourth part, then the average stress is: 。 6. The curve generation method as described in claim 2, characterized in that, Step S55 includes the following steps: S551, the minimum proportional limit: In the formula The yield strength is the average value of the measured original stress-strain curves. The average value of the proportional limit on each of the original stress-strain curves obtained. The minimum yield strength value of the product is given in advance; S552, the minimum fracture stress: In the formula The tensile strength is the average value of the measured original stress-strain curves. The average value of the fracture stress on each of the original stress-strain curves is calculated. This is the minimum tensile strength value of the product given in advance.

7. The curve generation method as described in claim 2, characterized in that, Step S56 includes the following steps: S561. If the data point is on the second part, then the minimum stress is: ； S562. If the data point is on the third part, then the minimum stress is: ； S563. If the data point is on the fourth part, then the minimum stress is: 。 8. The curve generation method as described in claim 2, characterized in that, Step S57 includes the following steps: S571. If the data point is on the second part, then the minimum plastic strain is: In the formula The minimum elongation of the product is given in advance; S572. If the data point is located in the third or fourth part, then the minimum plastic strain is: ； S573, Minimum elastic strain of the data point: ； S574. Add the minimum plastic strain and the minimum elastic strain to obtain the minimum total strain.

9. The curve generation method as described in claim 1, characterized in that, When performing step S5, in the first part, the origin and the proportional limit are connected by a straight line; in the second, third and fourth parts, adjacent data points are connected by straight lines; the number of data points is greater than 100.

Images