CN1278597A - Controller for experiment of true constant-strain rate in superplastic stretch - Google Patents
Controller for experiment of true constant-strain rate in superplastic stretch Download PDFInfo
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- CN1278597A CN1278597A CN 00117802 CN00117802A CN1278597A CN 1278597 A CN1278597 A CN 1278597A CN 00117802 CN00117802 CN 00117802 CN 00117802 A CN00117802 A CN 00117802A CN 1278597 A CN1278597 A CN 1278597A
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- strain rate
- experiment
- cross beam
- true constant
- loop control
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Abstract
The experiment control device comprises computer, D/A interface board and servoamplifier. Said device adopts open-loop control, and the computer is connected with D/A imterface board by means of PC bus, and according to a special-purpose program the computer can convert the data value into voltage analog quantity by means of T-type filter, integrating circuit and operational amplifien IC, then the voltage delivered by IC is inputted into the servo-control system of original machine to implement the displacement control of actual constant strain rate of moving crass-beam of testing machine. The utilization of said device also can be designal and mado into new-type universal material teating machine.
Description
The present invention relates to a kind of control device that is used on the superplastic deformation universal testing machine, belong to machinery instrument engineering field.
The constant strain rate stretching experiment that existing electronic universal material testing machine can be implemented all is meant the engineering constant strain rate
This is exactly in fact approximate processing for the plastic yield of conventional material, for superplastic material, just can not satisfy accuracy requirement fully, the electronic universal material testing machine that present international generally accepted Britain Instron, day island proper Tianjin and American MTS company are produced all can not be realized true constant strain rate
Stretching experiment, domestic, the universal testing machine that Changchun Inst of Testing Machine, Jinan testing machine factory produce, and 1997 older spring testing machine factory also all fail to realize the function of true constant strain rate stretching with the novel universal testing machine of the how sharp company of Germany cooperative development, existing electronic universal material testing machine is mainly used in the mechanical behavior of test toughness material because of it, the extensibility of this class material is less, to the susceptibility of strain rate a little less than, so all adopt closed-loop control system to realize the engineering constant strain rate
Stretching, just can reach the purpose of requirement of experiment and stable control.When the mechanical behavior of test superplastic deformation,, not only must realize true constant strain rate because superplastic deformation has very big extensibility and very strong sensitivity of strain rate
Stretch, and testing machine will adopt closed-loop control system can not reach the experimental result of expection, though the displacement of moved cross beam accumulative total variable quantity can satisfy accuracy requirement, but, because the adjustment of its speed is constantly relatively finishing by theoretical velocity and actual speed, increase when therefore its actual travelling speed has, sometimes reduce, even it is constant sometimes, therefore, for the very sensitive superplastic material of speed, its load value increases, the amount of decrease degree is also very big, influence to pairing stress and strain speed relation curve is very big, the inventor is at the initial stage of equipment improvement, once carried out the constant strain rate stretching experiment of closed-loop control, experimental measurements finds that its load is very big with the fluctuating range that the variation of strain rate takes place, and is inappropriate so adopt closed-loop control.
The objective of the invention is in order to satisfy material science and modern plasticity and the precision machined requirement of superplasticity, provide a kind of and can realize controller for experiment of true constant-strain rate in superplastic stretch, utilize this device can manufacture and design novel universal testing machine, also can be inserted in the control system of existing electronic universal material testing machine, realize the stretching experiment of true constant strain rate.
Above-mentioned purpose of the present invention proposes according to following principle:
The initial gauge length l of logarithmic strain ε and test specimen
0And the pass between the instantaneous gauge length l is
(1) formula is at l
0Near can series development
When having only the value of logarithmic strain ε very little, it just can be similar to equals engineering strain e (e=(l-l
0)/l
0)
Because the plasticity of material under the superplasticity state is very good, compare with conventional material, its extensibility can reach percent hundreds of and even a few percent thousand, therefore engineering strain e and logarithmic strain ε can differ tens times, hundred times, and even it is higher, therefore, just fully can not with engineering strain e approximate expression logarithmic strain ε, again owing to realize that superplastic temperature (generally be material melting point absolute temperature over half) is very high, also can not directly be clipped in general tens(i)ometer the two ends of test specimen gauge length in the high temperature furnace, but, test specimen is that the form by accompanying drawing 1 is connected in the testing machine, the upper connecting rod 2 of last fixed cross beam 1 in the accompanying drawing 1 by universal joint and test specimen links to each other with pin, the lower connecting rod 6 of test specimen is connected with testing machine moved cross beam 7 by universal joint, the two ends of test specimen 3 are connected with lower connecting rod 6 with upper connecting rod 2 to articulate form, because the rheology drag of material under the superplasticity state is very little, it have only equivalent material under uniform temp 1/tens, and even 1/tens, therefore, upper connecting rod 2 in the universal testing machine shown in the accompanying drawing 1 and lower connecting rod 6, and on the test specimen, following root 4 is compared with the dependent variable of test specimen gauge length part 3 can be not significant.So test piece deformation dl equals the displacement dL of moved cross beam 7 like nearby, the deformation velocity dl/dt of test specimen equals the translational speed dL/dt of moved cross beam, the true constant strain rate of test specimen like nearby
For:
(3) when
During for constant, by (3) Shi Kede:
L=l during (4) by t=0
0Starting condition, determine c=l
0 (5) guaranteeing constant strain rate
Condition under, the speed dL/dt of testing machine moved cross beam can be controlled by following formula
(6)
By (6) formula as seen, as long as any strain rate of given test piece deformation
,, just can realize the true constant strain rate of test specimen in theory by the speed v of control moved cross beam
Distortion.
Above-mentioned purpose of the present invention is to realize like this, accompanying drawings is as follows: the part that frame of broken lines is gone in the accompanying drawing 2 is the main frame and the control system of existing electronic universal material testing machine, it is by servoamplifier, current regulator, electronic universal tester topworks, the Displacement Feedback of tens(i)ometer, velocity feedback, current feedback and function generator, display is formed, the part that the dotted line frame is gone in the accompanying drawing 2 is a control device of the present invention, it is by servoamplifier, D/A interface board and PC computing machine are formed, this device adopts open loop control, the PC computing machine is connected with the D/A interface board by the PC bus, and the PC computing machine is according to the speed of moved cross beam 7
Program with the resistance R of digital quantity in servoamplifier
2, R
3And capacitor C
1The T mode filter of forming, resistance R
5, potentiometer W
2And capacitor C
2The integrating circuit and the operational amplifier IC that form are converted into voltage analog, and the voltage of IC output is input to former motor servo-controlled system, by
, the true constant strain rate of moved cross beam of execution testing machine
Displacement control, thereby realize true constant strain rate
Stretcher strain.
Open loop control is that cut at the A place in former servo-control system, the reversing switch of packing into, and when A was connected with B, this device was carried out open loop control, when A is connected with A ', carries out former machine closed-loop control.
Compare with existing electronic universal material testing machine, the present invention has following innovation and characteristic:
1. to daily output Tianjin, island, English produces Instron and the beautiful MTS of producing electronic universal material testing machine, owing to not be used in the test piece end tens(i)ometer that is installed, this is very favorable to research material at the mechanical behavior under the condition of high temperature, also need not to change original machine mechanism, as long as operation circuit of the present invention is inserted the control system of former machine, can realize that just moved cross beam presses the rule operation of true constant strain rate.
2. for the tension test of superplastic material,,, just can realize the constant strain rate tension test so directly use circuit (Fig. 3) by the design of (6) formula because the travelling speed of moved cross beam is approximately equal to the deformation velocity of test specimen.
3. the material big to resistance of deformation, that extensibility is little according to the definite deflection of going up lower connecting rod 2,6 and test specimen root 4 of experiment, is revised (6) formula, also can realize true constant strain rate tension test.
4. the present invention adopts open loop control, the instability of the load measurement that causes so can eliminate superplastic deformation to have very strong sensitivity of strain rate.
5. it is low, simple in structure that device of the present invention has cost, the advantage that is highly susceptible to implementing.
Further specify the particular content of the present invention and the course of work below in conjunction with accompanying drawing.
Fig. 1 Material Testing Machine sketch.
Fig. 2 controls general diagram.
Fig. 3 operation circuit figure.
Among Fig. 1: 1. go up upper and lower root 5. heating furnaces of fixed cross beam 2. upper connecting rods 3. test specimens 4. test specimens 6. lower connecting rods 7. moved cross beam
The invention is characterized in that this device is according to the designed electronic control circuit of (6) formula as shown in Figure 3, adopt open loop control moved cross beam speed dL/dt, according to superplastic deformation dL/dt is approximately equal to test piece deformation speed dl/dt, just reaches the realization constant strain rateThe purpose of stretcher strain.
Further specify control procedure of the present invention below in conjunction with Fig. 3: consult in the accompanying drawing 3 the with dashed lines frame and enter part (1), comprise PC computer, PC bus and optical isolation board, pressing
Program transport to the D/A interface board through the PC bus, digital quantity by the output of D/A interface board is input to part (2) again, partly (2) are comprised of T-shaped wave filter, IC operational amplifier and integrating circuit, by the D/A interface board digital quantity are input to by resistance R2、R
3And capacitor C1The T-shaped wave filter that forms and by resistance R5, potentiometer W2And capacitor C2The integrating circuit that forms, after being converted into voltage analog through filtering with digital quantity, again after operational amplifier IC amplifies, so just the signal that provides by (6) formula is passed to part (3) through A-B, after partly further amplify the voltage analog through the B input again (3), carry out according to this moved cross beam part of the main frame of control electronic universal tester, thereby realize constant strain rate stretcher strain.
Embodiments of the invention:
Accompanying drawing 2 is the former control system (dotted portion) of Tianjin, island AG-A electronic universal material testing machine and the present invention's's (dotted line part) general diagram, cut at A place in former control system, a reversing switch is installed, when A is connected with A ', is kept former closed-loop control system; When A is connected with B, promptly realize the open loop control of this device, in implementing constant strain rate control, selecting for use 386 computing machines to isolate the D/A interface board by 12 photoelectricity of PC bus and PCL-728 type is connected, according to formula (6) digital quantity is converted into voltage analog through accompanying drawing 2, voltage by accompanying drawing IC output is input to Tianjin, island AG-A electronic universal tester again after amplifying, the DC servo motor of direct driving host part, DC servo motor drives main-gear box and drives the leading screw rotation, thereby the driving moved cross beam, the final desired constant strain rate stretcher strain of realization theory formula (6) formula.
The numerical value of element and voltage is listed in table 1 in the accompanying drawing 2.Table 1:R (Ω), C (μ F)
| ????W 1 | ????W 2 | ????R 1 | ????R 2 | ????R 3 | ????R 4 | ????R 5 | ??IC |
| ????10K | ????10K | ????1M | ????10K | ????10K | ????1K | ????15K | ??LF356 |
| ????C 1 | ????C 2 | ????C 3 | ????C 4 | ????K A1 | ????K A2 | ????V B1 | ??K B2 |
| ????0.47 | ????0.1 | ????0.1 | ????0.1 | ????+15V | ????-15V | ????+15V | ??-15V |
In order to improve the control accuracy of constant strain rate, according to formula (6), corresponding to the initial gauge length l of given test specimen
0And constant strain rate
, make the speed v of crossbeam
bBe set in optimum range, the speed of crossbeam is divided into: 100mm/min, 80mm/min, 60mm/min, 40mm/min, 20mm/min, 10mm/min, 7 different class of 5mm/min, then according to the v of different speed class
bValue is adjusted the proportionate relationship of servoamplifier voltage and speed, determines different v again
bThe accurate analog voltage of value, its concrete scaling method are to utilize crossbeam register system record displacement L respectively
bAnd computer clock t writing time
b, by its ratio L
b/ t
bDetermine v
b, and make v
bCorresponding with the full sign indicating number transmission of D/A, this has just finished different class v
bDemarcation, by formula
As can be known, crossbeam speed is the index continuous function of time, if we select 12 high precision D/A cards for use, its velocity variations base unit is v
b/ 4896, the velocity variable in program reaches a base unit (v
b/ 4896) time, system could control crossbeam generation rapid change, therefore just produced the deviation of actual discontinuous velocity variations and theoretical velocity continuous function, in order to address this problem, earlier speed generation signal is amplified 10 times and 100 times respectively, this has just reduced the uncontinuity of speed control, and its concrete grammar is: test specimen extends by formula in time
Variable quantity show by computer screen, the actual displacement of crossbeam operation is by testing machine register system record, two record results relatively suitably revise formula (6) back, the limits of error that makes crosshead displacement surely in allowed limits, so the distortion of test specimen and the load of being born are still finished distortion-load-time triadic relation's correspondence one by one by former register system.
Very little when the distortion of materials drag, extensibility is very high, the strain rate of moved cross beam displacement just equals the strain rate in the test specimen gauge length.
Because (6) formula is that web member 2,6 is compared very little with test specimen root 4 with the distortion of test specimen gauge length part about supposition, try to achieve under the prerequisite that can be not significant, therefore, the test specimen big for resistance of deformation, that plastic yield is less, above-mentioned part just can not be ignored, and this will be determined by experiment the deflection of this part, after (6) formula is revised, also can under the condition of no tens(i)ometer, realize the stretcher strain of true constant strain rate, promptly right
Add correction factor, make
Also can realize the true constant strain rate stretcher strain in the test specimen gauge length, the last fixed cross beam of L-deducts l to the moved cross beam total length
0Surplus length, the end of e-natural logarithm.
Claims (4)
1. controller for experiment of true constant-strain rate in superplastic stretch is made up of PC computing machine, D/A interface board and servoamplifier, it is characterized in that this device adopts open loop control, the PC computing machine is connected with the D/A interface board by the PC bus, and the PC computing machine is according to crossbeam speed
Program with the resistance R of numerical value in servoamplifier
2, R
3And capacitor C
1The T mode filter of forming, resistance R
5, potentiometer W
2And capacitor C
2The integrating circuit of forming, and operational amplifier IC is converted into voltage analog, the voltage analog of IC output is input to former motor servo-controlled system, carries out the moved cross beam constant strain rate of testing machine
Displacement control,
The velocity of displacement of-moved cross beam,
-test piece deformation speed, l
0The initial gauge length of-test specimen,
-true constant strain rate.
2. by the described controller for experiment of true constant-strain rate in superplastic stretch of claim 1, it is characterized in that said open loop control is the A place incision in former servo-control system, adorn a reversing switch, when A is connected with B, this device is carried out open loop control, when A is connected with A ', carry out former machine closed-loop control.
3. by the described controller for experiment of true constant-strain rate in superplastic stretch of claim 1, it is characterized in that, very little when the distortion of materials drag, extensibility is very high, the strain rate of moved cross beam displacement just equals the strain rate in the test specimen gauge length.
4. by the described controller for experiment of true constant-strain rate in superplastic stretch of claim 1, it is characterized in that, when the distortion of materials drag is very big, extensibility hour, determine the deflection of web member and root up and down by experiment, right
Add correction factor, make
Also can realize the true constant strain rate stretcher strain in the test specimen gauge length, the last fixed cross beam of L-deducts l to the moved cross beam total length
0Surplus length, the end of e-natural logarithm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB001178024A CN1138137C (en) | 1999-06-21 | 2000-05-20 | Controller for experiment of true constant-strain rate in superplastic stretch |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN99224201.0 | 1999-06-21 | ||
| CN99224201 | 1999-06-21 | ||
| CNB001178024A CN1138137C (en) | 1999-06-21 | 2000-05-20 | Controller for experiment of true constant-strain rate in superplastic stretch |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1278597A true CN1278597A (en) | 2001-01-03 |
| CN1138137C CN1138137C (en) | 2004-02-11 |
Family
ID=34195275
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB001178024A Expired - Fee Related CN1138137C (en) | 1999-06-21 | 2000-05-20 | Controller for experiment of true constant-strain rate in superplastic stretch |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1138137C (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1317554C (en) * | 2004-06-22 | 2007-05-23 | 吉林大学 | Photoelectric recording test apparatus for protective gas superplastic bulge controlled temperature and pressure |
| CN102297806A (en) * | 2011-05-26 | 2011-12-28 | 南昌航空大学 | Method for constructing superplastic constitutive relation by adoption of strain rate cycling tensile test |
| CN103091177A (en) * | 2013-01-15 | 2013-05-08 | 南昌航空大学 | Drawing method of relationship of strain rate sensitivity index m value and ductility delta |
| CN103115818A (en) * | 2013-01-25 | 2013-05-22 | 南昌航空大学 | Efficient superplastic deformation method based on minimum m value |
| CN109085061A (en) * | 2018-07-18 | 2018-12-25 | 天津钢管集团股份有限公司 | A method of obtaining metal material stress-strain diagram under static compress state |
| CN109115603A (en) * | 2018-07-18 | 2019-01-01 | 天津钢管集团股份有限公司 | A method of obtaining metal material stress-strain diagram under static stretch state |
| CN114062167A (en) * | 2021-11-15 | 2022-02-18 | 哈尔滨工业大学（深圳） | Method for accurately controlling constant strain rate of normal-temperature sample of universal testing machine in stretching process |
-
2000
- 2000-05-20 CN CNB001178024A patent/CN1138137C/en not_active Expired - Fee Related
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1317554C (en) * | 2004-06-22 | 2007-05-23 | 吉林大学 | Photoelectric recording test apparatus for protective gas superplastic bulge controlled temperature and pressure |
| CN102297806A (en) * | 2011-05-26 | 2011-12-28 | 南昌航空大学 | Method for constructing superplastic constitutive relation by adoption of strain rate cycling tensile test |
| CN103091177A (en) * | 2013-01-15 | 2013-05-08 | 南昌航空大学 | Drawing method of relationship of strain rate sensitivity index m value and ductility delta |
| CN103091177B (en) * | 2013-01-15 | 2015-08-12 | 南昌航空大学 | The drawing process of a kind of strain rate sensitivity m and extensibility δ relation |
| CN103115818A (en) * | 2013-01-25 | 2013-05-22 | 南昌航空大学 | Efficient superplastic deformation method based on minimum m value |
| CN103115818B (en) * | 2013-01-25 | 2016-03-02 | 南昌航空大学 | A kind of Efficient superplastic deformation method based on minimum m value |
| CN109085061A (en) * | 2018-07-18 | 2018-12-25 | 天津钢管集团股份有限公司 | A method of obtaining metal material stress-strain diagram under static compress state |
| CN109115603A (en) * | 2018-07-18 | 2019-01-01 | 天津钢管集团股份有限公司 | A method of obtaining metal material stress-strain diagram under static stretch state |
| CN109085061B (en) * | 2018-07-18 | 2020-09-29 | 天津钢管制造有限公司 | Method for obtaining stress-strain curve of metal material in static compression state |
| CN109115603B (en) * | 2018-07-18 | 2020-11-03 | 天津钢管制造有限公司 | Method for obtaining stress-strain curve of metal material in static stretching state |
| CN114062167A (en) * | 2021-11-15 | 2022-02-18 | 哈尔滨工业大学（深圳） | Method for accurately controlling constant strain rate of normal-temperature sample of universal testing machine in stretching process |
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| Publication number | Publication date |
|---|---|
| CN1138137C (en) | 2004-02-11 |
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| AR01 | Abandonment of patent right to avoid double patenting |
According to article 9 of the patent law and article 13 of the detailed rules for the implementation of the patent law: 117802.4 of the invention patents in this issue as a notice of authorization, and at the same time corresponding to the 235063.7 utility model patent to be given up, and in the 20 volume of the 06 issue of the new type of communique on the patent right to abandon the announcement. |
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