CN117030463A - Loading method for improving control precision of tensile test - Google Patents
Loading method for improving control precision of tensile test Download PDFInfo
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- CN117030463A CN117030463A CN202311064157.6A CN202311064157A CN117030463A CN 117030463 A CN117030463 A CN 117030463A CN 202311064157 A CN202311064157 A CN 202311064157A CN 117030463 A CN117030463 A CN 117030463A
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- 238000009864 tensile test Methods 0.000 title claims abstract description 50
- 238000011068 loading method Methods 0.000 title claims abstract description 21
- 238000012937 correction Methods 0.000 claims abstract description 53
- 238000012360 testing method Methods 0.000 claims abstract description 29
- 230000008859 change Effects 0.000 claims abstract description 22
- 238000006073 displacement reaction Methods 0.000 claims abstract description 12
- 238000012417 linear regression Methods 0.000 claims description 15
- 230000002159 abnormal effect Effects 0.000 abstract description 4
- 239000000463 material Substances 0.000 description 11
- 238000000034 method Methods 0.000 description 9
- 230000008569 process Effects 0.000 description 6
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000007769 metal material Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000006467 substitution reaction 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
- 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
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
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- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention provides a loading method for improving control precision of a tensile test, which comprises the following steps: providing at least two identical samples, one sample serving as a member to be tested; calculating the beam stretching speed of the piece to be tested; stretching the to-be-measured piece according to the stretching speed of the cross beam of the to-be-measured piece to obtain a center gauge length-time change curve; obtaining the ith moment when the beam displacement increasing trend turns according to the center scale distance-time change curve; calculating elastic correction control parameters from the 0 th moment to the i th moment and plastic correction control parameters from the i th moment to the end moment of the tensile test; and carrying out tensile test on the sample by using the elastic correction control parameters from the 0 th moment to the i th moment and using the plastic correction control parameters from the i th moment to the tensile test ending moment. The optimal loading scheme of the sample is obtained through the to-be-tested piece, so that the test control precision is effectively improved, and the abnormal condition that the central deformation of the tensile test sample controlled by displacement is insufficient is solved.
Description
Technical Field
The invention relates to the technical field of metal stretching, in particular to a loading method for improving the control precision of a stretching test.
Background
When the basic mechanical properties of the metal material are researched, a tensile test of the material is often carried out, and mechanical performance indexes such as a stress-strain curve, yield strength, tensile strength, elongation and the like of the material can be obtained by carrying out a unidirectional tensile test. However, because the actuating arm of the tensile testing machine can generate certain elastic deformation in the test process, the abnormal condition of insufficient deformation amount of the sample center can often occur during the stretching, the actual deformation rate of the material is far from the ideal state, and the testing machine can not complete the required tensile test according to the set test parameters. Because the metal material has obvious strain rate sensitivity, if the actual strain rate of the tensile test does not meet the test design requirement, the mechanical properties of the material are seriously affected, so that the tester cannot accurately obtain the mechanical property index of the material. Therefore, it is important to develop a loading method that improves the control accuracy of the tensile test.
At present, the common control modes for the tensile test comprise strain control and displacement control, wherein the strain control needs to cling the extensometer to the surface of a sample in the test process, and the extensometer is easily damaged by impact generated during test fracture and can only be marginally suitable for the tensile test of low-strength materials. The displacement control mode does not need to depend on an extensometer, can be suitable for tensile tests of materials with respective strength levels, but can not accurately obtain mechanical property indexes of the materials according to set test parameters due to insufficient deformation of the center of a tensile sample, and can not meet scientific research tests and engineering requirements.
In summary, the present invention provides a loading method for improving control accuracy of a tensile test.
Disclosure of Invention
According to the technical problem of insufficient deformation of the center of the sample in the tensile test, a loading method for improving the control precision of the tensile test is provided. The invention mainly utilizes the difference between the actual deformation rate of the material and the set parameters to effectively improve the test control precision, thereby avoiding the abnormal situation of insufficient deformation of the center of the tensile test sample in displacement control and meeting the practical application requirements of engineering such as scientific research test.
The invention adopts the following technical means:
the invention provides a loading method for improving control precision of a tensile test, which comprises the following steps:
providing at least two identical test pieces, one of which serves as a test piece;
obtaining the gauge length and the preset strain rate of the piece to be measured;
calculating the beam stretching speed of the to-be-measured piece according to the gauge length and the preset strain rate;
stretching the to-be-detected piece according to the stretching speed of the cross beam of the to-be-detected piece to obtain a center gauge length-time change curve;
obtaining the ith moment when the beam displacement increasing trend turns according to the center gauge length-time change curve;
calculating elastic correction control parameters from the 0 th moment to the i th moment and plastic correction control parameters from the i th moment to the end moment of the tensile test;
and performing a tensile test on the sample with the elastic correction control parameter from the 0 th time to the i th time and with the plastic correction control parameter from the i th time to a tensile test ending time.
Further, the beam stretching speed of the to-be-measured piece is calculated according to the following mode:
beam stretching speed of the part to be measured=the gauge length×the preset strain rate.
Further, the elastic correction control parameter and the plastic correction control parameter are calculated as follows:
dividing the 0 th time to the i th time in the center scale distance-time change curve into a first part, and dividing the i th time to the stretching end time into a second part;
performing linear regression analysis on the first part to obtain an elastic regression coefficient, and performing linear regression analysis on the second part to obtain a plastic regression coefficient;
and obtaining the elasticity correction control parameter according to the elasticity regression coefficient and the beam stretching speed of the to-be-detected piece, and obtaining the plasticity correction control parameter according to the plasticity regression coefficient and the beam stretching speed of the to-be-detected piece.
Further, when linear regression analysis is performed on the second portion, translating the second portion in the center scale distance-time variation curve so that a starting point of the second portion corresponds to a zero point of the center scale distance-time variation curve;
and performing linear regression analysis on the translated second part.
Further, the elasticity correction control parameter is calculated as follows:
and the elasticity correction control parameter=the beam stretching speed of the to-be-detected piece ≡the elasticity regression coefficient × the beam stretching speed of the to-be-detected piece.
Further, the plastic correction control parameter is calculated as follows:
and the plasticity correction control parameter=the beam stretching speed of the to-be-detected piece ≡the plasticity regression coefficient × the beam stretching speed of the to-be-detected piece.
Compared with the prior art, the invention has the following advantages:
the loading method for improving the control precision of the tensile test provided by the invention comprises the following steps: providing at least two identical samples, one sample serving as a member to be tested; obtaining the gauge length and the preset strain rate of a piece to be measured; calculating the beam stretching speed of the piece to be measured according to the gauge length and the preset strain rate; stretching the to-be-measured piece according to the stretching speed of the cross beam of the to-be-measured piece to obtain a center gauge length-time change curve; obtaining the ith moment when the beam displacement increasing trend turns according to the center scale distance-time change curve; calculating elastic correction control parameters from the 0 th moment to the i th moment and plastic correction control parameters from the i th moment to the end moment of the tensile test; and carrying out tensile test on the sample by using the elastic correction control parameters from the 0 th moment to the i th moment and using the plastic correction control parameters from the i th moment to the tensile test ending moment. The optimal loading scheme of the sample is obtained through the piece to be tested, so that the difference between the actual deformation rate of the material and the set parameters is greatly reduced, the test control precision is effectively improved, and the abnormal condition of insufficient central deformation of the tensile test sample under displacement control is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to the drawings without inventive effort to a person skilled in the art.
FIG. 1 is a flow chart of a loading method for improving control accuracy of a tensile test according to the present invention.
FIG. 2 is a graph showing the comparison of the test curves before correction and the target parameters provided by the invention.
FIG. 3 is a graph showing the comparison of the modified test curve and the target parameters provided by the invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Referring to fig. 1, fig. 1 is a flowchart of a loading method for improving control accuracy of a tensile test according to the present invention, to illustrate a specific embodiment of a loading method for improving control accuracy of a tensile test according to the present embodiment, including:
providing at least two identical samples, one sample serving as a member to be tested;
obtaining the gauge length and the preset strain rate of a piece to be measured;
calculating the beam stretching speed of the piece to be measured according to the gauge length and the preset strain rate;
the beam stretching speed of the piece to be tested is calculated according to the following mode:
beam stretching speed = gauge length x preset strain rate of the part to be tested.
Stretching the to-be-measured piece according to the stretching speed of the cross beam of the to-be-measured piece to obtain a center gauge length-time change curve;
obtaining the ith moment when the beam displacement increasing trend turns according to the center scale distance-time change curve;
calculating elastic correction control parameters from the 0 th moment to the i th moment and plastic correction control parameters from the i th moment to the end moment of the tensile test;
wherein, calculate elasticity correction control parameter and plasticity correction control parameter, calculate according to the following way:
dividing the 0 th time to the i th time in the center scale distance-time change curve into a first part, and dividing the i th time to the stretching end time into a second part;
performing linear regression analysis on the first part to obtain an elastic regression coefficient, and performing linear regression analysis on the second part to obtain a plastic regression coefficient;
specifically, when linear regression analysis is performed on the second part, translating the second part in the center scale distance-time change curve, so that the starting point of the second part corresponds to the zero point of the center scale distance-time change curve;
linear regression analysis was performed on the translated second fraction.
And obtaining elasticity correction control parameters according to the elasticity regression coefficient and the beam stretching speed of the piece to be tested, and obtaining plasticity correction control parameters according to the plasticity regression coefficient and the beam stretching speed of the piece to be tested.
Wherein, the elasticity correction control parameter is calculated according to the following mode:
elasticity correction control parameter = beam stretching speed of the part to be measured +.elasticity regression coefficient × beam stretching speed of the part to be measured.
The plastic correction control parameters are calculated as follows:
plastic correction control parameter = beam stretching speed of the part to be measured +.plastic regression coefficient × beam stretching speed of the part to be measured.
And carrying out tensile test on the sample by using the elastic correction control parameters from the 0 th moment to the i th moment and using the plastic correction control parameters from the i th moment to the tensile test ending moment.
It can be understood that when the beam tensile test of the testing machine stretches the piece to be tested according to the beam tensile speed of the piece to be tested, a unidirectional tensile test of the piece to be tested is carried out in a displacement control mode, a preset strain rate is determined before the test is carried out, a test condition defined by a tensile test is carried out by a tester, and an error exists between the beam tensile speed and the actual deformation rate of the piece to be tested calculated according to the preset strain rate, so that the error between the beam tensile speed and the actual deformation rate of the piece to be tested needs to be reduced, specifically, a center scale-time change curve is obtained according to the tensile test of the piece to be tested, the center scale-time change curve is divided into a first part and a second part, the plastic regression coefficient of the first part and the plastic regression coefficient of the second part are respectively calculated, and the elastic correction control parameter and the plastic correction control parameter are obtained according to the elastic regression coefficient, the plastic regression coefficient and the beam tensile speed of the piece to be tested, and the tensile test is carried out on the sample from the 0 th moment to the i moment to the actual deformation rate of the piece to the test, so that the actual deformation rate of the sample is more approximate to the preset strain rate, thereby the center scale of the sample is greatly improved, and the test accuracy of the sample is effectively improved.
In some alternative embodiments, referring to fig. 1, fig. 2 and fig. 3, fig. 2 is a graph of a test curve and a target parameter before modification provided by the present invention, and fig. 3 is a graph of a test curve and a target parameter after modification provided by the present invention, to illustrate a specific embodiment of a loading method for improving control accuracy of a tensile test provided by the present embodiment, which includes:
providing at least two identical samples, one sample serving as a member to be tested;
taking the preset strain rate of the to-be-measured piece as 0.001 and the gauge length of the to-be-measured piece as 50 mm as an example, calculating the beam stretching speed of the to-be-measured piece as 0.05 mm/s according to the beam stretching speed=gauge length×preset strain rate of the to-be-measured piece.
Stretching the to-be-measured piece according to the speed of 0.05 millimeter/second to obtain a central gauge length-time change curve, wherein as shown in fig. 2, V theory is that the stretching speed of the cross beam of the to-be-measured piece is V theory, the moment point of turning of the cross beam displacement increasing trend is 110 seconds according to the central gauge length-time change curve, the 0 th second to the 110 th second in the central gauge length-time change curve are divided into a first part, and the 110 th second to the stretching end moment are divided into a second part;
performing linear regression analysis on the first part to obtain a first regression equation y=0.016 x, so that the elastic regression coefficient K1 is 0.016; when the second part is subjected to linear regression analysis, translating the second part in the center scale distance-time change curve, so that the starting point of the second part corresponds to the zero point of the center scale distance-time change curve; linear regression analysis was performed on the translated second portion to obtain a second regression equation y=0.0299x, so the elastic regression coefficient K2 was 0.0299.
Calculating the elasticity correction control parameter to be 0.156 mm/s according to the elasticity correction control parameter = the beam stretching speed of the to-be-measured piece/(the elasticity regression coefficient/(the beam stretching speed of the to-be-measured piece); the plastic correction control parameter was 0.0836 mm/s based on the plastic correction control parameter = the beam stretching speed of the part to be measured +.plastic regression coefficient × the beam stretching speed of the part to be measured.
In the process of stretching a sample, the stretching sample is controlled by using the elastic correction control parameter to be 0.156 mm/s from 0 th second to 110 th second, the stretching sample is stretched by using the plastic correction control parameter to be 0.0836 mm/s from 110 th second to stretching end time, and fig. 3 is obtained, in fig. 3, the actual deformation rate of the sample is obviously close to the preset strain rate, namely, the corrected parameter is adopted to carry out the stretching test of the sample, the control precision is higher, and the method provided by the embodiment utilizes the deformation characteristic of the material and the intrinsic relation mechanism of the rigidity of the tester system to obtain the accurate control parameter, so that the control precision of the stretching test of the sample is improved, and the condition that the central deformation quantity of the sample is insufficient in the stretching test process is effectively improved.
The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.
In the foregoing embodiments of the present invention, the descriptions of the embodiments are emphasized, and for a portion of this disclosure that is not described in detail in this embodiment, reference is made to the related descriptions of other embodiments.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (6)
1. The loading method for improving the control precision of the tensile test is characterized by comprising the following steps of:
providing at least two identical test pieces, one of which serves as a test piece;
obtaining the gauge length and the preset strain rate of the piece to be measured;
calculating the beam stretching speed of the to-be-measured piece according to the gauge length and the preset strain rate;
stretching the to-be-detected piece according to the stretching speed of the cross beam of the to-be-detected piece to obtain a center gauge length-time change curve;
obtaining the ith moment when the beam displacement increasing trend turns according to the center gauge length-time change curve;
calculating elastic correction control parameters from the 0 th moment to the i th moment and plastic correction control parameters from the i th moment to the end moment of the tensile test;
and performing a tensile test on the sample with the elastic correction control parameter from the 0 th time to the i th time and with the plastic correction control parameter from the i th time to a tensile test ending time.
2. The loading method for improving the control precision of the tensile test according to claim 1, wherein the beam tensile speed of the part to be tested is calculated as follows:
beam stretching speed of the part to be measured=the gauge length×the preset strain rate.
3. The loading method for improving the control accuracy of the tensile test according to claim 1, wherein the elastic correction control parameter and the plastic correction control parameter are calculated as follows:
dividing the 0 th time to the i th time in the center scale distance-time change curve into a first part, and dividing the i th time to the stretching end time into a second part;
performing linear regression analysis on the first part to obtain an elastic regression coefficient, and performing linear regression analysis on the second part to obtain a plastic regression coefficient;
and obtaining the elasticity correction control parameter according to the elasticity regression coefficient and the beam stretching speed of the to-be-detected piece, and obtaining the plasticity correction control parameter according to the plasticity regression coefficient and the beam stretching speed of the to-be-detected piece.
4. The loading method for improving the control precision of the tensile test according to claim 3, wherein when the second part is subjected to linear regression analysis, the second part is shifted in the center scale distance-time variation curve so that the starting point of the second part corresponds to the zero point of the center scale distance-time variation curve;
and performing linear regression analysis on the translated second part.
5. A loading method for improving control accuracy of a tensile test according to claim 3, wherein the elastic correction control parameter is calculated as follows:
and the elasticity correction control parameter=the beam stretching speed of the to-be-detected piece ≡the elasticity regression coefficient × the beam stretching speed of the to-be-detected piece.
6. A loading method for improving control accuracy of a tensile test according to claim 3, wherein the plastic correction control parameter is calculated as follows:
and the plasticity correction control parameter=the beam stretching speed of the to-be-detected piece ≡the plasticity regression coefficient × the beam stretching speed of the to-be-detected piece.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311064157.6A CN117030463A (en) | 2023-08-21 | 2023-08-21 | Loading method for improving control precision of tensile test |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311064157.6A CN117030463A (en) | 2023-08-21 | 2023-08-21 | Loading method for improving control precision of tensile test |
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| CN117030463A true CN117030463A (en) | 2023-11-10 |
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| CN202311064157.6A Pending CN117030463A (en) | 2023-08-21 | 2023-08-21 | Loading method for improving control precision of tensile test |
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- 2023-08-21 CN CN202311064157.6A patent/CN117030463A/en active Pending
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