CN118275242A - Method for acquiring constitutive relation of metal material through small cylinder compression test - Google Patents
Method for acquiring constitutive relation of metal material through small cylinder compression test Download PDFInfo
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- CN118275242A CN118275242A CN202410369654.5A CN202410369654A CN118275242A CN 118275242 A CN118275242 A CN 118275242A CN 202410369654 A CN202410369654 A CN 202410369654A CN 118275242 A CN118275242 A CN 118275242A
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000012669 compression test Methods 0.000 title claims abstract description 22
- 239000007769 metal material Substances 0.000 title claims abstract description 20
- 239000000463 material Substances 0.000 claims abstract description 30
- 238000007906 compression Methods 0.000 claims abstract description 27
- 230000006835 compression Effects 0.000 claims abstract description 26
- 238000006073 displacement reaction Methods 0.000 claims abstract description 20
- 238000012360 testing method Methods 0.000 claims abstract description 16
- 238000012545 processing Methods 0.000 claims abstract description 9
- 238000009864 tensile test Methods 0.000 abstract description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 2
- 239000001257 hydrogen Substances 0.000 abstract description 2
- 230000007547 defect Effects 0.000 abstract 1
- 238000001514 detection method Methods 0.000 abstract 1
- 238000004088 simulation Methods 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000009795 derivation Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000013142 basic testing Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000004154 testing of material Methods 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
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Abstract
The invention discloses a method for acquiring constitutive relation of a metal material by a small cylinder compression test, which comprises the steps of performing power law fitting on an elastoplastic section of a compression load-displacement curve after acquiring the compression load-displacement curve of the material by a quasi-static compression test, and solving constitutive parameters of the material by a theoretical formula so as to obtain a tensile stress-strain curve of the material; and directly carrying out data processing on the compression load-displacement curve obtained by the test to obtain a compression stress-strain curve. According to the invention, a proper cylindrical sample can be intercepted according to the actual structural size, the tensile stress-strain curve and the compressive stress-strain curve of the material can be obtained at the same time, and the tensile asymmetry and the compressive asymmetry of the material can be compared; the method can also meet the requirements of micro-damage detection, the processing, testing and theoretical analysis of the test sample are relatively simple, the defects of larger size and the like of the traditional uniaxial tensile test sample are avoided, and the tensile and compressive mechanical property test of the material under special environments such as high temperature, high pressure hydrogen and the like is conveniently carried out.
Description
Technical Field
The invention relates to the technical field of metal material mechanical property testing, in particular to a method for acquiring constitutive relation of a metal material by a small cylinder compression test.
Background
The tensile and compressive constitutive relation curve of the metal material is the most basic physical relation of the material, and is also the basis for further carrying out numerical simulation analysis, reliability evaluation and other works on the material and the structural member. The traditional equal-straight round bar uniaxial tensile test sample has larger size, is difficult to be used for testing the local mechanical properties of some small-size structural parts, welding structures and service components, and cannot obtain the compression stress-strain curve of the material at the same time. The traditional cylinder sample compression test can only acquire the elastic modulus and the compressive stress-strain curve of the material, and is difficult to acquire the tensile stress-strain curve of the metal material at the same time.
Therefore, a method for obtaining the constitutive relation of the metal material by a small cylinder compression test needs to be developed.
Disclosure of Invention
The invention aims to provide a method for acquiring constitutive relation of a metal material by a small cylinder compression test.
The invention realizes the above purpose through the following technical scheme:
A small cylinder compression test method comprises the following steps:
S1, measuring and recording the diameter D and the height H of a small cylindrical sample, and carrying out a quasi-static loading test on the small cylindrical sample to obtain a compression load F-displacement H curve of the sample;
S2, performing power law fitting on the compression load F-displacement h curve elastoplastic segment obtained through the test by the formula (1) to obtain a fitting coefficient gamma 1 and a fitting index gamma 2;
(1)
wherein h is the compression displacement of the small cylindrical sample; f is a compression load;
S3, the elastic modulus E of the metal material is generally changed within a small range, and can be obtained by checking a material manual or measuring by adopting classical modes such as an ultrasonic method, a vibration method and the like. Bringing γ 1 and γ 2 into formula (2), calculating the yield strength σ y and hardening exponent n of the obtainable material;
(2)
s4, substituting E, sigma y and n of the metal material into Hollomon equation:
(3)
analyzing the uniaxial stretching constitutive curve of the obtained metal material;
S5, carrying out data processing on a compression load F-displacement h curve obtained by the sample according to a formula (4) to obtain a material compression constitutive curve:
(4)
the invention has the beneficial effects that:
The method for acquiring the constitutive relation of the metal material by the small cylinder compression test is simple in sample processing, test and data processing, and a learner can easily acquire the tensile stress and compressive stress-strain curve of the metal material by the method only by mastering simple theory and basic test skills, so that the tensile-compressive asymmetry of the material is evaluated, and the tensile and compressive mechanical property test of the material in special environments such as high temperature, high pressure hydrogen and the like can be conveniently realized, so that the method has higher engineering application value.
Drawings
FIG. 1 is a small cylinder compression loading schematic;
FIG. 2 is a graph of load versus displacement obtained by compression of a small cylindrical sample of 30CrMnSiA material;
FIG. 3 is a graph showing the comparison of tensile and compressive stress-strain curves obtained by the present invention with conventional uniaxial stretching results.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", "left", "right", etc. are based on the directions or positional relationships shown in the drawings, or the directions or positional relationships conventionally put in place when the inventive product is used, or the directions or positional relationships conventionally understood by those skilled in the art are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific direction, be configured and operated in a specific direction, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
In the description of the present invention, it should also be noted that, unless explicitly specified and limited otherwise, terms such as "disposed," "connected," and the like are to be construed broadly, and for example, "connected" may be either fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
The following describes specific embodiments of the present invention in detail with reference to the drawings.
The technical scheme adopted by the invention comprises two parts: and (3) a small cylinder compression test and a small cylinder compression theoretical model.
(1) Small cylinder compression test
In order to reduce deformation of the test clamp as much as possible, a high-strength steel processing test clamp such as tungsten steel is adopted for carrying out a quasi-static compression test on a small cylindrical sample, in order to reduce lateral bending risk of the sample in the test process, the ratio H/D of the height and the diameter of the sample is not more than 2, the compression displacement H/D is not more than 0.2, a small cylindrical compression test schematic diagram is shown in figure 1, and a compression load-displacement (F-H) curve of the sample is obtained through the compression test.
(2) Small cylinder compression theory model
The load-displacement curve obtained by the small cylinder compression test method can be found to contain a large amount of information such as materials, geometry and the like through theoretical derivation and finite element numerical simulation, and specific rules exist among the load-displacement curve and the small cylinder compression test method. For the material elastic modulus E, which generally varies within a small range, it can be measured by looking into a material handbook or by classical means such as vibration methods, and small variations in elastic modulus have little effect on the predicted stress-strain curve of the elastoplastic segment of the metal material, and thus can be assumed to be a known constant. Fitting coefficient gamma 1 and fitting index gamma 2 can be obtained by fitting the elastoplastic segment of the small cylinder compression load-displacement curve, and the method is obtained by the following formula: ; by means of the formula (1) and the formula (2), the tensile stress-strain curve of the material can be obtained, and by means of the formula (3), the compressive stress-strain curve of the material can be obtained by analysis.
(1)
(2)
(3)
In the technical scheme of the invention, the proper sample size can be determined according to the actual structure size, the micro-damage sampling of the in-service member can be realized, the load-displacement curve is obtained by means of a small cylinder compression test, the test method is simple, and the tensile stress-strain relation of the material can be determined by simple data processing.
Examples:
In the technical scheme of the invention, a technical theoretical system for acquiring the tensile and compressive stress-strain relationship of the material by adopting a small cylinder compression test is provided based on theoretical derivation and a small quantity of finite element simulation.
A material testing machine is used for carrying out compression test on a 30CrMnSiA small cylindrical sample (with the diameter of 5mm and the height of 10 mm), a load-displacement curve obtained by compression is shown as a graph in fig. 2, zero point correction is carried out on test data, a nonlinear section is fitted by using a power law, gamma 1 and gamma 2 obtained by fitting are brought into a formula (1) to carry out simultaneous equation solving, so that mechanical performance parameters sigma y and n of a material or a component can be obtained, a tensile stress-strain curve of the material can be obtained by bringing into the formula (2), and a compressive stress-strain relation curve can be obtained by processing the compressive load-displacement curve by virtue of the formula (3). Fig. 3 shows the comparison result of the tensile and compressive stress-strain curves of the 30CrMnSiA material obtained by the technical scheme of the present invention and the stress-strain curve obtained by the uniaxial tensile test of the conventional round bar sample, and it can be seen from the graph that the tensile stress-strain curve obtained by the method of the present invention is better matched with the tensile test result of the conventional round bar sample, and the compressive stress-strain curve obtained by compression is slightly higher than the tensile stress-strain curve, which indicates that the 30CrMnSiA material has a small amount of tensile-compression asymmetry. The tensile stress-strain curve and the compressive stress-strain curve of the metal material can be obtained simultaneously by utilizing a millimeter-level small cylinder compression test, and the method has important significance for measuring the stress-strain relation of rare and precious small-size structural members.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that it will be apparent to those skilled in the art that several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the scope of the invention.
Claims (1)
1. The method for acquiring the constitutive relation of the metal material by using the small cylinder compression test is characterized by comprising the following steps of:
S1, measuring and recording the diameter D and the height H of a small cylindrical sample, and carrying out a quasi-static loading test on the small cylindrical sample to obtain a compression load F-displacement H curve of the sample;
S2, performing power law fitting on the compression load F-displacement h curve elastoplastic segment obtained through the test by the formula (1) to obtain a fitting coefficient gamma 1 and a fitting index gamma 2;
(1)
wherein h is the compression displacement of the small cylindrical sample; f is a compression load;
S3, measuring the elastic modulus E of the metal material by checking a material manual or an ultrasonic method or a vibration method; bringing γ 1 and γ 2 into formula (2), calculating the yield strength σ y and hardening exponent n of the obtainable material;
(2)
s4, substituting E, sigma y and n of the metal material into Hollomon equation:
(3)
analyzing the uniaxial stretching constitutive curve of the obtained metal material;
S5, carrying out data processing on a compression load F-displacement h curve obtained by the sample according to a formula (4) to obtain a material compression constitutive curve:
(4)。
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118275242A true CN118275242A (en) | 2024-07-02 |
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