Experimental method capable of directly measuring anisotropy coefficient in any direction in panel
By flanging and calendering the sheet metal sample, the anisotropy coefficient in any direction in the plane can be directly measured, which solves the error problem caused by the discreteness of experimental data in the prior art, realizes the continuous description of anisotropic characteristics, and improves the accuracy and reliability of experimental results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-29
- Publication Date
- 2026-03-31
AI Technical Summary
In the existing technology, the anisotropic experimental data of rolled plates are obtained based on discrete experimental methods, which makes it difficult to keep the experimental conditions consistent and cannot accurately describe the anisotropic characteristics of the plates under continuous changes, resulting in a large deviation between the numerical simulation results and the actual results.
An experimental method is adopted to cut a sample with a closed hole in the shape of the plate, and use a flanging die and a calendering die to flanging and calendering the sample to maintain a uniaxial tensile stress state during the deformation process, and directly measure the anisotropy coefficient in any direction in the plate.
It enables the continuous acquisition of anisotropy coefficients in any direction within the surface of the plate under the same experimental conditions, improving the accuracy and reliability of experimental data, reducing the measurement difficulty, and is applicable to rolled plates of various metal materials with a wide range of applications.
Smart Images
Figure CN121762800A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the plastic processing technology of metal sheets, and more specifically, to an experimental method that can directly measure the anisotropy coefficient in any direction within the surface of a sheet. Background Technology
[0002] With increasing demands for lightweight and strength in automotive body parts, the demand for various sheet metals is also constantly growing. However, during the stamping process of sheet metal, fractures frequently occur in the deep-drawing and flanging areas, increasing the manufacturing difficulty of automotive bodies. To reduce manufacturing costs and optimize processes, it is necessary to predict forming results through accurate numerical simulation. Achieving accurate numerical simulation requires precise data results, which necessitates accurate and comprehensive mechanical property testing results. The intense plastic deformation during the rolling process of sheet metal leads to preferred crystal orientation within the material, generating different textures and exhibiting significant in-plane anisotropy. The in-plane anisotropy coefficient plays a crucial role in the plastic forming process of sheet metal. Therefore, accurately measuring the anisotropy coefficient in any direction within the plane of the rolled sheet metal is essential for optimizing the manufacturing process.
[0003] Anisotropy signifies a property that changes continuously with the direction of loading. The most appropriate description of anisotropic plastic flow would be continuously varying material property data. However, current experimental data on the anisotropy of rolled steel sheets are all based on discrete experimental methods. This involves cutting independent specimens along different directions of the sheet (such as the commonly used 0°, 45°, and 90° directions) and conducting multiple uniaxial tensile tests to obtain experimental data for each direction. Each experiment yields data for only one specific direction. Furthermore, the experimental conditions and procedures for each independent experiment are difficult to maintain perfectly, and only a limited number of anisotropic experimental data directions can be obtained. Therefore, using these limited discrete experimental data to describe continuously changing characteristics is prone to unavoidable errors, resulting in significant discrepancies between numerical simulation results and experimental results, leading to a phenomenon of "simulation without realism."
[0004] Therefore, how to establish a mechanical property testing method that can describe the continuously changing anisotropic experimental data of rolled sheet metal and achieve an accurate description of the anisotropic plastic flow characteristics of sheet metal has become an urgent problem to be solved by those skilled in the art. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide an experimental method that can directly measure the anisotropy coefficient in any direction within the surface of a sheet material. This method ensures that the sheet material is simultaneously and continuously under uniaxial tensile stress in all directions during deformation, guaranteeing that the obtained experimental data is continuous under the same experimental conditions, thereby accurately measuring the anisotropy coefficient in any direction within the surface of the sheet material.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] An experimental method for directly determining the anisotropy coefficient in any direction within the surface of a sheet material includes the following steps:
[0008] S1, determine the shape and size of the experimental sample, and the center of the experimental sample has a closed hole;
[0009] S2, cut the experimental sample described in step S1 from the plate to be tested;
[0010] S3. Prepare a flanging die and a calendering die according to the shape and size of the experimental sample;
[0011] S4, the experimental sample is flanged using the flanging die to form a straight wall area around the hole in the experimental sample.
[0012] S5, Take out the experimental sample formed in step S4, place it on the calendering die for calendering, so that the straight wall area undergoes the deformation required to determine the anisotropy coefficient of the plate in any direction;
[0013] S6, obtain the characteristic parameters of the straight-wall region;
[0014] S7, using the characteristic parameters to determine the anisotropy coefficients in each direction within the experimental sample.
[0015] Preferably, the experimental sample is made of metal.
[0016] Preferably, the metal material is aluminum alloy, low carbon steel, magnesium alloy, high strength steel or high temperature alloy.
[0017] Preferably, the outer contour of the experimental sample is circular, elliptical, or rectangular;
[0018] The hole is either circular or elliptical in shape.
[0019] Preferably, in step S2, the experimental sample is cut using wire electrical discharge machining, laser cutting, end milling, or water jet cutting.
[0020] Preferably, in step S3, the size of the center hole of the flanged die is larger than the size of the hole in the experimental sample;
[0021] The size of the center hole of the calender die is larger than the size of the hole in the experimental specimen after flanging.
[0022] Preferably, in step S6, the characteristic parameters include strain, strain increment, wall thickness, or length.
[0023] Preferably, if the characteristic parameter is strain, then the angle between the straight wall region and the rolling direction is circumferential strain, thickness strain, or radial strain.
[0024] If the characteristic parameter is a strain increment, then the angle between the straight wall region and the rolling direction is a circumferential strain increment, a thickness strain increment, or a radial strain increment.
[0025] If the characteristic parameter is wall thickness or length, then the angle between the straight wall region and the rolling direction is the thickness, circumferential length, or radial length of the straight wall region.
[0026] Preferably, the feature parameters include those obtained during and after the experiment.
[0027] Preferably, step S7, determining the anisotropy coefficients in each direction within the experimental sample, specifically includes:
[0028] When the angle between the straight wall region and the rolling direction is radial strain components in the direction and thickness strain components When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0029]
[0030] When the angle between the straight wall region and the rolling direction is Circumferential strain components in the direction and thickness strain components When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0031]
[0032] When the angle between the straight wall region and the rolling direction is Circumferential strain components in the direction and radial strain components When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0033]
[0034] When the angle between the straight wall region and the rolling direction is radial strain increment in the direction and thickness strain increment When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0035]
[0036] When the angle between the straight wall region and the rolling direction is Circumferential strain increment in the direction and radial strain increment When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0037]
[0038] When the characteristic parameter is the wall thickness or length of the straight wall region, the thickness strain, circumferential strain or radial strain is first calculated by the change in thickness or length, and then the anisotropy coefficient in each direction within the surface of the test sample is determined by the strain.
[0039] The present invention provides an experimental method for directly measuring the anisotropy coefficient in any direction within the surface of a plate, which has the following advantages:
[0040] (1) The present invention can directly obtain the anisotropy coefficient in any direction within the plate surface, and can ensure that the obtained test data is non-discrete and continuous. It ensures that the anisotropy coefficients in different directions are obtained under continuous deformation under the same experimental conditions, which provides important support for accurately establishing the plate plastic constitutive relationship that can fully reflect the continuous anisotropic flow characteristics of the plate, and thus lays the foundation for forming various typical complex integral components.
[0041] (2) This invention can ensure that the deformation of the straight wall area is not affected by other external forces, and maintain a unidirectional tensile stress state throughout the experiment, satisfying the mechanical conditions for determining the anisotropy coefficient in any direction. Furthermore, the experimental data at any position in the same direction of the straight wall area can be used to calculate the anisotropy coefficient in that direction. It can also reduce the difficulty of measuring experimental data and facilitate the real-time online acquisition of experimental data in different directions.
[0042] (3) In this invention, experimental data at any position in the same direction of the straight wall region can reflect the anisotropy coefficient of the material in that direction. It can not only comprehensively process multiple sets of experimental data at different positions in the same direction to obtain the optimal anisotropy coefficient in that direction, thus improving the accuracy of the results, but also use experimental data at different positions in the same direction to verify each other, thus improving the reliability of the results.
[0043] (4) The experimental principle and method of this invention are simple, the experimental samples are easy to process, and no complex control system is required, making it easy for operators to get started.
[0044] (5) This invention can be used to determine the in-plane anisotropy coefficient of rolled plates of various metal materials, such as aluminum alloys, titanium alloys, magnesium alloys, high-strength steel pipes, and has a wide range of applications. Attached Figure Description
[0045] Figure 1 This is a flowchart illustrating the experimental method of the present invention;
[0046] Figure 2 This is a schematic diagram showing that the experimental sample in the experimental method of this invention is circular;
[0047] Figure 3 This is a schematic diagram showing that the experimental sample in the experimental method of this invention is elliptical;
[0048] Figure 4 This is a schematic diagram showing that the experimental sample in the experimental method of this invention is rectangular;
[0049] Figure 5 This is a schematic diagram of the holes on the experimental sample in the experimental method of the present invention. (a) is a circular hole, and (b) is an elliptical hole.
[0050] Figure 6 This is a schematic diagram of the experimental sample after being formed by flanging in the experimental method of the present invention. (a) is the front view and (b) is the bottom view.
[0051] Figure 7 This is a schematic diagram of the experimental sample after calendering in the experimental method of the present invention. (a) is the front view and (b) is the bottom view.
[0052] Figure 8 This is a schematic diagram of the distribution of anisotropy coefficients within the surface of the experimental sample as measured in the experimental method of this invention. Detailed Implementation
[0053] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.
[0054] Combination Figure 1 As shown, the present invention provides an experimental method for directly measuring the anisotropy coefficient in any direction within the surface of a plate, comprising the following steps:
[0055] S1, determine the shape and size of the experimental sample 1, and the center of the experimental sample 1 has a closed hole 2;
[0056] S2, according to the shape and size of the experimental sample 1 determined in step S1, cut the experimental sample from the plate to be tested;
[0057] S3. Based on the shape and size of the experimental sample 1, prepare the flanging die and the calendering die, such as determining the shape and size of the punch, die and blank holder required for the experiment.
[0058] S4, the experimental specimen 1 is flanged using a flanging die, forming a straight-walled area around the hole in the specimen. During the forming process, the punch and die of the flanging die are placed coaxially. The punch descends until it contacts the experimental specimen 1 and continues to descend. The flanging process is completed under the combined action of the punch, die, and pressure ring. Figure 6 As shown;
[0059] S5, Take out the experimental sample 1 formed in step S4, place it on the calendering die for calendering, so that the straight wall area undergoes the deformation required for determining the anisotropy coefficient of the sheet in any direction. During the forming process, place the experimental sample 1 on the top of the die cavity of the calendering die, with the center of the experimental sample 1 coaxial with the center hole of the die cavity. The punch descends at a certain speed until the experimental sample 1 completes the deformation, such as... Figure 7 As shown;
[0060] S6, obtain the characteristic parameters of the straight-wall region;
[0061] S7, using characteristic parameters to determine the anisotropy coefficients in various directions within the experimental sample, such as... Figure 8 As shown.
[0062] In step S1, the experimental sample is made of metal.
[0063] The metal materials are aluminum alloy, low carbon steel, magnesium alloy, high strength steel or high temperature alloy.
[0064] The method for determining the shape of the experimental specimen is as follows: Based on experimental requirements, the outer contour of the experimental specimen may be circular, elliptical, or rectangular, such as... Figures 2 to 4 As shown in the figure, the angle between any direction of the experimental specimen and the rolling direction of the experimental specimen is defined as follows:
[0065] The holes can be round or oval in shape, such as... Figure 5 As shown.
[0066] In step S2, a suitable processing method can be selected to cut the experimental sample according to the experimental conditions, such as using wire electrical discharge machining, laser cutting, end milling or water jet cutting to cut the experimental sample.
[0067] In step S3, the size of the center hole of the flange die is larger than the size of the hole in the experimental sample;
[0068] The size of the center hole of the calender die is larger than the size of the hole in the experimental specimen after flanging.
[0069] In step S6, the characteristic parameters include strain, strain increment, wall thickness, or length.
[0070] If the characteristic parameter is strain, then the angle between the straight wall region and the rolling direction is circumferential strain, thickness strain, or radial strain.
[0071] If the characteristic parameter is the strain increment, then the angle between the straight wall region and the rolling direction is the circumferential strain increment, the thickness strain increment, or the radial strain increment.
[0072] If the characteristic parameter is wall thickness or length, then the angle between the straight wall region and the rolling direction is the thickness, circumferential length, or radial length of the straight wall region.
[0073] Characteristic parameters include those obtained during and after the experiment.
[0074] In step S7, determining the anisotropy coefficients in each direction within the experimental sample specifically includes:
[0075] When the angle between the straight wall region and the rolling direction is radial strain components in the direction and thickness strain components When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0076]
[0077] When the angle between the straight wall region and the rolling direction is Circumferential strain components in the direction and thickness strain components When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0078]
[0079] When the angle between the straight wall region and the rolling direction is Circumferential strain components in the direction and radial strain components When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0080]
[0081] When the angle between the straight wall region and the rolling direction is radial strain increment in the direction and thickness strain increment When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0082]
[0083] When the angle between the straight wall region and the rolling direction is Circumferential strain increment in the direction and radial strain increment When, the angle with the rolling direction is Anisotropy coefficient in direction Calculate as follows:
[0084]
[0085] When the characteristic parameter is the wall thickness or length of the straight wall region, the thickness strain, circumferential strain or radial strain is first calculated by the change in thickness or length, and then the anisotropy coefficient in each direction within the surface of the test sample is determined by the strain.
[0086] In step S6, the thickness strain of the straight wall region on the experimental specimen can be determined by the initial wall thickness of the straight wall region on the experimental specimen and the wall thickness of the straight wall region after calendering. The circumferential strain of the straight wall region can be determined by the initial circumferential length of the straight wall region on the experimental specimen and the circumferential length after calendering. Furthermore, the radial strain can be determined by utilizing the condition that the volume remains unchanged during plastic deformation.
[0087] Example 1
[0088] Example 1 uses a rolled aluminum alloy sheet with a wall thickness of 0.5 mm as an example, combined with... Figures 6-8 The implementation process of this invention is described below.
[0089] S1, the outer contour of the experimental sample 1 is determined to be circular with a diameter of 160 mm, and the center of the experimental sample 1 has a closed circular hole with a diameter of 56 mm.
[0090] S2, according to the shape and size of the experimental sample 1 determined in step S1, cut the experimental sample from the plate to be tested;
[0091] S3. Based on the shape and size of experimental sample 1, prepare the flanging die and the calendering die;
[0092] S4, the experimental specimen 1 is flanged using a flanging die, forming a straight-walled area around the hole in the specimen. During the forming process, the punch and die of the flanging die are placed coaxially. The punch descends until it contacts the experimental specimen 1 and continues to descend. The flanging process is completed under the combined action of the punch, die, and pressure ring. Figure 6 As shown;
[0093] S5, Take out the experimental sample 1 formed in step S4, place it on the calendering die for calendering, so that the straight wall area undergoes the deformation required for determining the anisotropy coefficient of the sheet in any direction. During the forming process, place the experimental sample 1 on the top of the die cavity of the calendering die, with the center of the experimental sample 1 coaxial with the center hole of the die cavity. The punch descends at a certain speed until the experimental sample 1 completes the deformation, such as... Figure 7 As shown;
[0094] S6, the characteristic parameters of the straight wall region are obtained, and the angle between them and the rolling direction is... radial strain components in the direction and thickness strain components The characteristic parameter data of the straight-wall region in the main directions are shown in Table 1;
[0095] Table 1 shows the measured radial and thickness strain component data points.
[0096]
[0097] S7, using characteristic parameters, according to formula The anisotropy coefficients in each direction within the surface of the experimental specimen were determined, and the calculation results are as follows: Figure 8 As shown.
[0098] Example 2
[0099] In step S6 of Example 2, the characteristic parameters of the straight wall region are obtained, and the angle between the parameter and the rolling direction is... Circumferential strain components in the direction and radial strain components The characteristic parameter data of the straight-walled region in the main directions are shown in Table 2;
[0100] Table 2 shows the measured data points for circumferential and thickness strain components.
[0101]
[0102] S7, using characteristic parameters, according to formula The anisotropy coefficients in each direction within the plane of the experimental specimen were determined, and the calculation results are as follows: Figure 8 As shown. The remaining steps S1 to S5 are the same as steps S1 to S5 in Example 1.
[0103] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.
Claims
1. An experimental method capable of directly measuring the anisotropy coefficient in any direction in the plane of a sheet, characterized in that, The method comprises the following steps: S1, determining the shape and size of an experimental sample, and the center of the experimental sample has a shape-closed hole; S2, cutting the experimental sample in step S1 from a plate to be tested; S3, preparing a flanging die and a calendering die according to the shape and size of the experimental sample; S4, flanging the experimental sample by using the flanging die to form a straight wall area around the hole of the experimental sample; S5, taking out the experimental sample after the forming in step S4 and placing it on the calendering die to perform calendering forming, so that the straight wall area is deformed for measuring the anisotropy coefficient in any direction of the plate; S6, obtaining a characteristic parameter of the straight wall area; S7, determining the anisotropy coefficient in each direction of the experimental sample by using the characteristic parameter.
2. The experimental method capable of directly measuring the anisotropy coefficient in any direction on the surface of a plate according to claim 1, characterized in that: The material of the experimental sample is metal.
3. The experimental method capable of directly measuring the anisotropy coefficient in any direction on the surface of a plate according to claim 2, characterized in that: The metal material is aluminum alloy, low-carbon steel, magnesium alloy, high-strength steel or high-temperature alloy.
4. The experimental method capable of directly measuring the anisotropy coefficient in any direction on the surface of a plate according to claim 1, characterized in that: The outer contour of the experimental sample is circular, elliptical or rectangular. The shape of the hole is circular or elliptical.
5. The experimental method capable of directly measuring the anisotropy coefficient in any direction on the surface of a plate according to claim 1, characterized in that: In step S2, the experimental sample is cut by using electric spark wire cutting, laser cutting, end milling or water cutting.
6. The experimental method capable of directly measuring the anisotropy coefficient in any direction on the surface of a plate according to claim 1, characterized in that: In step S3, the size of the concave mold center hole of the flanging die is greater than the size of the hole of the experimental sample. In step S3, the size of the concave mold center hole of the calendering die is greater than the size of the hole of the experimental sample after the flanging forming.
7. The experimental method capable of directly measuring the anisotropy coefficient in any direction on the surface of a plate according to claim 1, characterized in that: In step S6, the characteristic parameter includes strain, strain increment, wall thickness or length.
8. The experimental method capable of directly measuring the in-plane anisotropy coefficient in any direction of a plate according to claim 7, wherein: If the characteristic parameter is strain, the angle between the straight wall area and the rolling direction is circumferential strain, thickness strain or radial strain; If the characteristic parameter is strain increment, the angle between the straight wall area and the rolling direction is circumferential strain increment, thickness strain increment or radial strain increment; If the characteristic parameter is wall thickness or length, the angle between the straight wall area and the rolling direction is the thickness, circumferential length or radial length of the straight wall area.
9. The experimental method capable of directly measuring the anisotropy coefficient in any direction on the surface of a plate according to claim 7, characterized in that: The characteristic parameter includes the characteristic parameter obtained before and after the experiment.
10. The experimental method capable of directly measuring the anisotropy coefficient in any direction on the surface of a plate according to claim 8, characterized in that, In step S7, the anisotropy coefficient in each direction of the experimental sample is determined, which specifically comprises: when the straight wall region has an angle of a radial strain component in the rolling direction and a thickness strain component when the straight wall region has an angle of an anisotropy coefficient in the rolling direction is calculated as follows: when the straight wall region has an angle of a component of the hoop strain in the rolling direction and a component of the thickness strain when the straight wall region has an angle of an anisotropy coefficient of the direction is calculated as follows: when the straight wall zone has an angle with the rolling direction of the circumferential strain component in the direction and the radial strain component when the straight wall zone has an angle with the rolling direction of the anisotropy coefficient in the direction is calculated as follows: when the straight wall region has an angle of radial strain increment in the rolling direction and a thickness strain increment when the straight wall region has an angle of anisotropy coefficient in the rolling direction is calculated as follows: when the straight wall region has an angle of an anisotropy coefficient in the circumferential strain increment and the radial strain increment when the straight wall region has an angle of an anisotropy coefficient in the circumferential strain increment is calculated as follows: When the characteristic parameter is the wall thickness or length of the straight wall area, the thickness strain or circumferential strain or radial strain is calculated by the thickness or length change, and then the anisotropy coefficient in each direction of the sample to be tested is determined by the strain.