CN113865954A - Construction method of non-contact forming limit diagram - Google Patents
Construction method of non-contact forming limit diagram Download PDFInfo
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- CN113865954A CN113865954A CN202110989975.1A CN202110989975A CN113865954A CN 113865954 A CN113865954 A CN 113865954A CN 202110989975 A CN202110989975 A CN 202110989975A CN 113865954 A CN113865954 A CN 113865954A
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- 238000010586 diagram Methods 0.000 title claims abstract description 30
- 238000010276 construction Methods 0.000 title abstract description 6
- 238000012360 testing method Methods 0.000 claims abstract description 78
- 239000000463 material Substances 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims abstract description 26
- 238000009864 tensile test Methods 0.000 claims abstract description 13
- 238000005516 engineering process Methods 0.000 claims abstract description 8
- 238000009826 distribution Methods 0.000 claims description 14
- 238000010008 shearing Methods 0.000 claims description 12
- 238000005336 cracking Methods 0.000 claims description 6
- 238000005520 cutting process Methods 0.000 claims description 4
- 238000005498 polishing Methods 0.000 claims description 4
- 230000000694 effects Effects 0.000 claims description 3
- 230000003068 static effect Effects 0.000 claims description 3
- 239000007769 metal material Substances 0.000 abstract description 10
- 238000004364 calculation method Methods 0.000 abstract description 3
- 238000004088 simulation Methods 0.000 abstract description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 239000002131 composite material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/32—Polishing; Etching
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
Abstract
The invention relates to a construction method of a non-contact forming limit diagram, belonging to the technical field of metal material forming methods. The technical scheme of the invention is as follows: a tensile test method is adopted, main strain and secondary strain of a frame before the material is broken are accurately obtained by utilizing a DIC technology, and a forming limit diagram of the metal material is accurately constructed. The invention has the beneficial effects that: the main deformation part does not need to be contacted with any die in the whole test process, so that the problems that the strain at the fracture position cannot be collected in the traditional forming limit test and the friction force when the male die is contacted with the sheet material influences the test result are effectively solved; the forming limit diagram obtained by the method more accurately describes the comprehensive forming capacity of the metal material, and provides a reliable judgment basis for the stamping forming simulation calculation of the plate.
Description
Technical Field
The invention relates to a construction method of a non-contact forming limit diagram, belonging to the technical field of metal material forming methods.
Background
The forming limit diagram is the limit principal strain epsilon of the plate material in the local cracking under different strain paths1And secondary strain epsilon2The resulting strip-shaped zone, which reflects the ability of the sheet metal to resist necking or cracking under uniaxial, planar and biaxial tensile stresses, is widely used to evaluate the sheet's ability to be formed in general. The method for obtaining the forming limit diagram is commonly used at present, a test piece is deformed to be broken by using the movement of a rigid male die, and the main strain and the secondary strain of a complete grid near a crack are measured instead of the strain distribution at a fracture position, so that the test result is low.
Disclosure of Invention
The invention aims to provide a method for constructing a non-contact forming limit diagram, which adopts a tensile test method, accurately obtains the main strain and the secondary strain of a frame before the material is broken by utilizing DIC technology, and accurately constructs the forming limit diagram of a metal material, wherein the main deformation part does not need to be contacted with any mould in the whole test process, thereby effectively solving the problem that the strain at the broken position and the friction force when a male die is contacted with a sheet material cannot be collected in the traditional forming limit test to influence the test result; the forming limit diagram obtained by the method more accurately describes the comprehensive forming capability of the metal material, provides a reliable judgment basis for the stamping forming simulation calculation of the plate, and effectively solves the problems in the background art.
The technical scheme of the invention is as follows: a construction method of a non-contact forming limit diagram comprises the following steps:
(1) processing the sample by using linear cutting to obtain a sample according with the size of a part, and finely polishing the edge of the sample to ensure the smooth edge of the sample and avoid the influence of surface microcracks on the accuracy of test data;
(2) the method comprises the following steps of (1) uniformly scattering speckles at main deformation parts of a sample, and collecting pictures of movement and distribution conditions of the speckles in a main deformation area by using a high-speed camera;
(3) processing the picture acquired in the step (2) by utilizing DIC technology to obtain a distribution map of main strain and secondary strain along with time in a main deformation area of the sample, finding a maximum strain point at a crack position of a frame before cracking, and extracting a change rule of the main strain and the secondary strain of the point along with time;
(4) repeating each test for three times to ensure good repeatability of the test result, and taking the intermediate value of the fracture main strain of the three tests and the corresponding secondary strain as the strain point of the material under the strain path when the material is cracked;
(5) drawing a graph of the relationship between the primary strain and the secondary strain when the material is fractured under different strain paths, wherein the graph is a forming fracture limit graph of the material;
(6) and (4) translating the forming fracture limit curve of the material downwards by 10 percent to obtain a forming limit diagram of the material when the material is unstable or necked in the stamping forming process.
In the step (1), the test sample has seven shapes, including a shearing test sample, a pulling and shearing test sample, a middle hole test sample, a uniaxial tension test sample, an R5 notch test sample, an R20 notch test sample and a biaxial tension test sample, the shearing test sample, the pulling and shearing test sample, the middle hole test sample, the uniaxial tension test sample, the R5 notch test sample and the R20 notch test sample are carried out on a uniaxial tension tester, and the biaxial tension test sample is carried out on a biaxial tension tester.
All tensile tests described are static tensile rates, without taking into account the effect of the dynamic properties of the material on the forming limit.
And acquiring the maximum main strain and the corresponding secondary strain of the previous frame of fracture under the bulging strain path of the material on the right side of the forming limit diagram by using a biaxial tensile testing machine.
The invention has the beneficial effects that: by adopting a tensile test method, the main strain and the secondary strain of a frame before the material is broken are accurately obtained by utilizing the DIC technology, the forming limit diagram of the metal material is accurately constructed, and the main deformation part does not need to be contacted with any die in the whole test process, so that the problems that the strain at the broken position cannot be collected in the traditional forming limit test and the friction force when the male die is contacted with the sheet material influences the test result are effectively solved; the forming limit diagram obtained by the method more accurately describes the comprehensive forming capacity of the metal material, and provides a reliable judgment basis for the stamping forming simulation calculation of the plate.
Drawings
FIG. 1 is a notch R20 strain path;
FIG. 2 is a composite strain path of tension and shear;
FIG. 3 is a mid-hole strain path
FIG. 4 is a uniaxial tensile strain path;
FIG. 5 is a shear strain path;
FIG. 6 is a notch R5 strain path;
FIG. 7 is a biaxial tensile strain path;
FIG. 8 is a graph of the principal strain distribution for a frame prior to fracture of the R20 strain path;
FIG. 9 is a plot of the strain profile of the R20 strain path over the previous frame before fracture;
FIG. 10 is a graph of the breaking limit of QP980-1.2mm material;
FIG. 11 is a forming limit diagram for QP980-1.2mm material.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the embodiments of the present invention with reference to the drawings of the embodiments, and it is obvious that the described embodiments are a small part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative work based on the embodiments of the present invention belong to the protection scope of the present invention.
A construction method of a non-contact forming limit diagram comprises the following steps:
(1) processing the sample by using linear cutting to obtain a sample according with the size of a part, and finely polishing the edge of the sample to ensure the smooth edge of the sample and avoid the influence of surface microcracks on the accuracy of test data;
(2) the method comprises the following steps of (1) uniformly scattering speckles at main deformation parts of a sample, and collecting pictures of movement and distribution conditions of the speckles in a main deformation area by using a high-speed camera;
(3) processing the picture acquired in the step (2) by utilizing DIC technology to obtain a distribution map of main strain and secondary strain along with time in a main deformation area of the sample, finding a maximum strain point at a crack position of a frame before cracking, and extracting a change rule of the main strain and the secondary strain of the point along with time;
(4) repeating each test for three times to ensure good repeatability of the test result, and taking the intermediate value of the fracture main strain of the three tests and the corresponding secondary strain as the strain point of the material under the strain path when the material is cracked;
(5) drawing a graph of the relationship between the primary strain and the secondary strain when the material is fractured under different strain paths, wherein the graph is a forming fracture limit graph of the material;
(6) and (4) translating the forming fracture limit curve of the material downwards by 10 percent to obtain a forming limit diagram of the material when the material is unstable or necked in the stamping forming process.
In the step (1), the test sample has seven shapes, including a shearing test sample, a pulling and shearing test sample, a middle hole test sample, a uniaxial tension test sample, an R5 notch test sample, an R20 notch test sample and a biaxial tension test sample, the shearing test sample, the pulling and shearing test sample, the middle hole test sample, the uniaxial tension test sample, the R5 notch test sample and the R20 notch test sample are carried out on a uniaxial tension tester, and the biaxial tension test sample is carried out on a biaxial tension tester.
All tensile tests described are static tensile rates, without taking into account the effect of the dynamic properties of the material on the forming limit.
And acquiring the maximum main strain and the corresponding secondary strain of the previous frame of fracture under the bulging strain path of the material on the right side of the forming limit diagram by using a biaxial tensile testing machine.
Example (b):
specifically, a method for constructing a forming limit diagram with the material of QP980-1.2mm by adopting a non-contact test method is introduced.
a. According to a CAD drawing of a sample, processing the sample with seven shapes of QP980-1.2mm by utilizing linear cutting, and finely polishing the edge of the sample to ensure that the edge of the sample has no burrs, damages and the like so as not to influence an experimental result;
b. uniformly spraying speckles on the main deformation area of each sample, and performing a test after the speckles are dried;
c. placing an R20 sample (shown in figure 1) into a clamping end of a tensile testing machine, ensuring that the length direction and the stress direction of the sample are on the same axis, and carrying out a tensile test by the tensile testing machine at a speed of 4 mm/min;
d. collecting speckle motion and distribution conditions of a main deformation area of an R20 sample by using a high-speed camera at the frequency of 10Hz, and analyzing speckle images by using DIC technology to obtain main strain distribution maps and secondary strain distribution maps of main deformation positions at different moments;
e. screening a main strain distribution diagram of each frame, determining that the cracking time of the R20 sample is 49s, the time of the previous frame of the R20 sample is 48.9s, finding the position of the maximum main strain point near the crack on the main strain distribution diagram of the frame, extracting the main strain and the secondary strain of the point, and extracting a change relation curve of the main strain of the point from the beginning to 48.9s along with the secondary strain;
f. repeating the test for three times, wherein the three tests obtain that the coincidence of a main strain-secondary strain curve of a fracture position point is better, the main strains of the three fracture position points are respectively 0.375, 0.366 and 0.358, then taking the intermediate value (0.366) of the fracture main strain of the three tests and the corresponding secondary strain (-0.072) as the fracture strain point of the material, and if the coincidence of the three tests is not good, then carrying out the test again;
g. repeating (except for the biaxial tension test) other uniaxial tension tests in the same method to obtain the fracture main strain and the fracture secondary strain of the metal material under the strain path;
h. a biaxial tension sample (as shown in figure 7) is arranged on a biaxial tension tester, an upper beam and a left beam of the tester move at the speed of 4mm/min at the same time, so that the sample is ensured to simultaneously generate the same deformation in the length direction and the width direction, and the speckle images shot by a high-speed camera, the subsequent images and the data processing mode are the same as those of an R20 notch test.
i. The relation curve of the main strain and the secondary strain of different strain paths is drawn on a relation graph, namely the fracture limit curve of the material QP980-1.2mm (as shown in figure 10);
and j, translating the breaking limit diagram of the QP980-1.2mm downwards by 10 percent to obtain a limit curve of necking or instability of the material during punching, wherein the breaking limit curve and the instability limit curve are enough to form the limit diagram of the QP980-1.2mm material (shown in figure 11).
According to the invention, a tensile test method is adopted, a forming limit diagram of a metal material is accurately obtained by utilizing DIC technology, and the influence of the friction force on a test result when a common FLC test is difficult to accurately capture the strain distribution of a fracture position and a mold is in contact with a sample is effectively avoided.
Claims (4)
1. A method for constructing a non-contact forming limit diagram is characterized by comprising the following steps:
(1) processing the sample by using linear cutting to obtain a sample according with the size of a part, and finely polishing the edge of the sample to ensure the smooth edge of the sample and avoid the influence of surface microcracks on the accuracy of test data;
(2) the method comprises the following steps of (1) uniformly scattering speckles at main deformation parts of a sample, and collecting pictures of movement and distribution conditions of the speckles in a main deformation area by using a high-speed camera;
(3) processing the picture acquired in the step (2) by utilizing DIC technology to obtain a distribution map of main strain and secondary strain along with time in a main deformation area of the sample, finding a maximum strain point at a crack position of a frame before cracking, and extracting a change rule of the main strain and the secondary strain of the point along with time;
(4) repeating each test for three times, and taking the intermediate value of the fracture main strain of the three tests and the corresponding secondary strain as a strain point of the material under the strain path when the material cracks;
(5) drawing a graph of the relationship between the primary strain and the secondary strain when the material is fractured under different strain paths, wherein the graph is a forming fracture limit graph of the material;
(6) and (4) translating the forming fracture limit curve of the material downwards by 10 percent to obtain a forming limit diagram of the material when the material is unstable or necked in the stamping forming process.
2. The method for constructing a non-contact forming limit diagram according to claim 1, wherein: in the step (1), the test sample has seven shapes, including a shearing test sample, a pulling and shearing test sample, a middle hole test sample, a uniaxial tension test sample, an R5 notch test sample, an R20 notch test sample and a biaxial tension test sample, the shearing test sample, the pulling and shearing test sample, the middle hole test sample, the uniaxial tension test sample, the R5 notch test sample and the R20 notch test sample are carried out on a uniaxial tension tester, and the biaxial tension test sample is carried out on a biaxial tension tester.
3. A method of constructing a non-contact forming limit map according to claim 1 or 2, wherein: all tensile tests described are static tensile rates, without taking into account the effect of the dynamic properties of the material on the forming limit.
4. A method of constructing a non-contact forming limit map according to claim 1 or 2, wherein: and acquiring the maximum main strain and the corresponding secondary strain of the previous frame of fracture under the bulging strain path of the material on the right side of the forming limit diagram by using a biaxial tensile testing machine.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114509341A (en) * | 2022-02-23 | 2022-05-17 | 北京理工大学重庆创新中心 | Method for measuring stress triaxial degree in material sample tensile fracture test process |
Citations (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102305745A (en) * | 2011-05-25 | 2012-01-04 | 山东大学 | Differential-interference-contrast (DIC)-technology-based sheet metal forming performance testing device |
| CN102435512A (en) * | 2011-09-07 | 2012-05-02 | 西安交通大学 | Visual measurement method of plate forming limit curve (FLC) |
| CN102749253A (en) * | 2012-07-10 | 2012-10-24 | 首钢总公司 | Testing system and method of plate high temperature forming limit diagram |
| CN104155194A (en) * | 2014-07-22 | 2014-11-19 | 武汉钢铁(集团)公司 | FLC (forming limit curve) testing method based on variation of strain rate |
| CN104568611A (en) * | 2015-01-08 | 2015-04-29 | 泛亚汽车技术中心有限公司 | Method for evaluating plate forming capability and deformation homogenizing capability based on DIC strain measuring system |
| CN105223090A (en) * | 2014-06-09 | 2016-01-06 | 鞍钢股份有限公司 | A kind of automotive sheet FLC curve determination device and method based on DIC technology |
| CN106198179A (en) * | 2016-08-01 | 2016-12-07 | 湖南大学 | A kind of assay device measuring complex diversion systen lower thin sheet forming limit and method |
| CN108027306A (en) * | 2015-08-10 | 2018-05-11 | 帝国创新有限公司 | Flat test system |
| CN109470559A (en) * | 2018-09-10 | 2019-03-15 | 上海交通大学 | Constriction failure limit strain detecting method based on DIC |
| CN109708969A (en) * | 2019-02-27 | 2019-05-03 | 西北工业大学 | A kind of method of determining metal material anisotropy and tension and compression asymmetry feature |
| CN110686976A (en) * | 2019-11-18 | 2020-01-14 | 湖南沃尔丁科技有限公司 | Electromagnetic force driven metal sheet high-speed forming limit testing device |
| JP2020046184A (en) * | 2018-09-14 | 2020-03-26 | Ｊｆｅスチール株式会社 | Stress-strain relationship estimation method |
| CN111260184A (en) * | 2020-01-08 | 2020-06-09 | 湖南沃尔丁科技有限公司 | Application method of forming limit strain diagram under nonlinear strain path |
| CN111292813A (en) * | 2020-01-17 | 2020-06-16 | 中国石油天然气集团有限公司 | Method for drawing fracture forming limit diagram of anisotropic material based on fracture criterion and use method thereof |
| WO2021037036A1 (en) * | 2019-08-28 | 2021-03-04 | 肖锋 | Test and calculation method for measuring real stress-strain curve of material |
| CN112547838A (en) * | 2019-09-10 | 2021-03-26 | 宝山钢铁股份有限公司 | Method for testing edge forming limit of metal plate |
-
2021
- 2021-08-26 CN CN202110989975.1A patent/CN113865954A/en active Pending
Patent Citations (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102305745A (en) * | 2011-05-25 | 2012-01-04 | 山东大学 | Differential-interference-contrast (DIC)-technology-based sheet metal forming performance testing device |
| CN102435512A (en) * | 2011-09-07 | 2012-05-02 | 西安交通大学 | Visual measurement method of plate forming limit curve (FLC) |
| CN102749253A (en) * | 2012-07-10 | 2012-10-24 | 首钢总公司 | Testing system and method of plate high temperature forming limit diagram |
| CN105223090A (en) * | 2014-06-09 | 2016-01-06 | 鞍钢股份有限公司 | A kind of automotive sheet FLC curve determination device and method based on DIC technology |
| CN104155194A (en) * | 2014-07-22 | 2014-11-19 | 武汉钢铁(集团)公司 | FLC (forming limit curve) testing method based on variation of strain rate |
| CN104568611A (en) * | 2015-01-08 | 2015-04-29 | 泛亚汽车技术中心有限公司 | Method for evaluating plate forming capability and deformation homogenizing capability based on DIC strain measuring system |
| CN108027306A (en) * | 2015-08-10 | 2018-05-11 | 帝国创新有限公司 | Flat test system |
| CN106198179A (en) * | 2016-08-01 | 2016-12-07 | 湖南大学 | A kind of assay device measuring complex diversion systen lower thin sheet forming limit and method |
| CN109470559A (en) * | 2018-09-10 | 2019-03-15 | 上海交通大学 | Constriction failure limit strain detecting method based on DIC |
| JP2020046184A (en) * | 2018-09-14 | 2020-03-26 | Ｊｆｅスチール株式会社 | Stress-strain relationship estimation method |
| CN109708969A (en) * | 2019-02-27 | 2019-05-03 | 西北工业大学 | A kind of method of determining metal material anisotropy and tension and compression asymmetry feature |
| WO2021037036A1 (en) * | 2019-08-28 | 2021-03-04 | 肖锋 | Test and calculation method for measuring real stress-strain curve of material |
| CN112547838A (en) * | 2019-09-10 | 2021-03-26 | 宝山钢铁股份有限公司 | Method for testing edge forming limit of metal plate |
| CN110686976A (en) * | 2019-11-18 | 2020-01-14 | 湖南沃尔丁科技有限公司 | Electromagnetic force driven metal sheet high-speed forming limit testing device |
| CN111260184A (en) * | 2020-01-08 | 2020-06-09 | 湖南沃尔丁科技有限公司 | Application method of forming limit strain diagram under nonlinear strain path |
| CN111292813A (en) * | 2020-01-17 | 2020-06-16 | 中国石油天然气集团有限公司 | Method for drawing fracture forming limit diagram of anisotropic material based on fracture criterion and use method thereof |
Non-Patent Citations (4)
| Title |
|---|
| 梁晋等: "数字图像相关法测量板料成形应变", 机械工程学报, vol. 49, no. 10 * |
| 牛超等: "数字图像相关法在薄板成形极限测定中的应用", 塑性工程学报, vol. 21, no. 06 * |
| 王永信等: "数字图像相关法的板料成形极限研究与应用", 锻压技术, vol. 38, no. 03 * |
| 邓陟等: "金属薄板成形技术", 31 August 1993, 兵器工业出版社, pages: 15 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114509341A (en) * | 2022-02-23 | 2022-05-17 | 北京理工大学重庆创新中心 | Method for measuring stress triaxial degree in material sample tensile fracture test process |
| CN114509341B (en) * | 2022-02-23 | 2023-08-25 | 北京理工大学重庆创新中心 | Method for measuring stress triaxial degree in tensile fracture test process of material sample |
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