CN113866002A - Constant stress loading system and method for micro-sample creep property bulging test - Google Patents
Constant stress loading system and method for micro-sample creep property bulging test Download PDFInfo
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- 238000006073 displacement reaction Methods 0.000 description 5
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- G—PHYSICS
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- 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
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
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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
- G01N3/02—Details
- G01N3/04—Chucks
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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
- G01N3/02—Details
- G01N3/06—Special adaptations of indicating or recording means
- G01N3/068—Special adaptations of indicating or recording means with optical indicating or recording means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0071—Creep
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0075—Strain-stress relations or elastic constants
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/022—Environment of the test
- G01N2203/0222—Temperature
Abstract
The invention relates to a constant stress loading system and a constant stress loading method for a micro sample creep property bulging test, wherein a temperature control device enables a micro sample to be in a constant temperature environment under the control of a control system, a bulging deformation measuring system measures bulging deformation data of the upper surface of the micro sample and transmits the bulging deformation data to the control system, the control system calculates the adjusting load pressure of the micro sample by adopting a finite element automatic modeling and rapid analysis method according to the bulging deformation data, the control system compares the fluid pressure measured by a pressure gauge with the adjusting load pressure of the micro sample and controls the working state of a pressure regulating device according to the comparison result, so that the fluid pressure is equal to the adjusting load pressure of the micro sample, the sample is kept in a constant stress state by dynamically regulating the pressure load value, and more accurate high-temperature creep property test of the material micro sample is realized.
Description
Technical Field
The invention relates to the field of micro-sample creep property testing, in particular to a constant stress loading system and method for micro-sample creep property bulging testing.
Background
The micro-sample creep property testing method based on the bulging principle has the advantages of small sample size, small damage to in-use equipment, few influence factors in the testing process and the like, is more and more widely applied to the field of creep property testing of materials, and is of great importance to residual life evaluation and life prolonging analysis of in-use equipment. At present, a micro-sample mechanical property test based on a bulging principle generally adopts a constant-load test method. Although the load control is more convenient during the test by the constant load method, the stress state of the sample material is obviously changed along with the bulging deformation and the local thinning of the sample in the test process even if the load is not changed. This causes the data measurement and result analysis of the sample creep test process to become extremely complicated, and significantly affects the creep bulging deformation rate and the judgment life analysis accuracy of the material at high temperature, and the analysis result is easy to generate large deviation.
When high-temperature pressure-bearing equipment is used for evaluating residual life and analyzing service life extension in the fields of aerospace, nuclear power, large-scale petrochemical industry and the like, the data precision requirement on the high-temperature creep performance of the material is higher. Therefore, a constant stress loading method applicable to a creep property bulging test technology of a micro sample is needed, which is also a key problem to be solved in the field of creep property bulging test research of the micro sample.
Disclosure of Invention
The invention aims to provide a constant stress loading system and a constant stress loading method for a micro-sample creep property bulging test, so as to realize more accurate high-temperature creep property test of a material micro-sample.
In order to achieve the purpose, the invention provides the following scheme:
a constant stress loading system for a micro specimen creep performance bulge test, the system comprising: the device comprises a clamping structure, a temperature control device, a bulging deformation measuring system, a control system, a fluid pressurizing device, a pressure regulating device and a pressure gauge;
the micro sample is fixed on one end of the clamping structure, one end of the clamping structure penetrates through the temperature control device, the micro sample is arranged in the temperature control device, and the other end of the clamping structure is fixed on the ground;
the temperature control device is connected with the control system and is used for enabling the micro-sample to be in a constant temperature environment under the control of the control system;
the output end of the fluid pressurizing device is connected with the lower surface of the micro sample, and the pressure regulating device and the pressure gauge are both arranged on a pressure medium pipeline between the output end of the fluid pressurizing device and the lower surface of the micro sample; the fluid pressurizing device is used for generating pressure on the lower surface of the micro sample by using a fluid medium so as to enable the upper surface of the micro sample to generate bulging deformation;
the bulging deformation measuring system is connected with the control system and is used for measuring bulging deformation data of the upper surface of the micro sample and transmitting the bulging deformation data to the control system; the control system is used for calculating the adjusting load pressure of the micro sample according to the bulging deformation data;
the control system is also used for acquiring the fluid pressure measured by the pressure gauge, comparing the fluid pressure with the adjusting load pressure of the micro-sample, and controlling the working state of the pressure adjusting device according to the comparison result to enable the fluid pressure to be equal to the adjusting load pressure of the micro-sample.
Optionally, the bulging deformation measurement system includes: the device comprises a laser transmitter, a beam splitter, a beam expander, an imaging lens, a beam combining prism and a CCD camera;
the laser emitter is used for emitting laser to the upper surface of the micro sample, and a beam splitter and a beam expander are sequentially arranged on the laser emitter and the laser emitting light path of the micro sample; the beam splitter is used for splitting laser emitted by the laser emitter into two beams, one beam of laser irradiates the beam combining prism, the other beam of laser irradiates the upper surface of the micro sample after being diffused by the beam splitter, and scattered laser is generated on the upper surface of the micro sample;
an imaging lens, a beam combining prism and a CCD camera are sequentially arranged on a scattered laser light path generated on the upper surface of the micro sample, the scattered laser light is subjected to interference synthesis with a beam of laser light on the beam combining prism after passing through the imaging lens, and the laser light after the interference synthesis forms bulging deformation data of the micro sample on the CCD camera;
the CCD camera is connected with the control system and used for transmitting the bulging deformation data to the control system.
Optionally, the pressure regulating device includes: a pressure pump and a pressure relief valve;
the pressurizing pump and the pressure relief valve are both arranged on a pressure medium pipeline between the output end of the fluid pressurizing device and the lower surface of the micro sample;
and the control end of the pressurizing pump and the control end of the pressure relief valve are both connected with the control system.
Optionally, the control system includes: a PLC and an upper computer;
the upper computer is respectively connected with the CCD camera and the PLC and is used for obtaining the adjusting load pressure of the micro-sample according to the bulging deformation data output by the CCD camera and transmitting the adjusting load pressure of the micro-sample to the PLC;
the PLC is respectively connected with the signal output end of the pressure gauge, the control end of the pressure pump and the control end of the pressure relief valve, and is used for obtaining the fluid pressure measured by the pressure gauge, comparing the fluid pressure with the adjusting load pressure of the micro-sample, and controlling the working states of the pressure pump and the pressure relief valve according to the comparison result, so that the fluid pressure is equal to the adjusting load pressure of the micro-sample.
Optionally, the temperature control device includes: an atmospheric furnace, an electric heating wire and a thermocouple;
the electric heating wire, the thermocouple and the micro sample are all arranged inside the atmospheric furnace;
the atmospheric furnace comprises quartz glass and two cuboid grooves;
one end of each of the two cuboid grooves is connected with the clamping structure, and the other end of each of the two cuboid grooves is connected with the quartz glass to form a closed cavity;
the electric heating wire and the thermocouple are connected with the PLC, and the thermocouple is used for measuring the temperature inside the atmospheric furnace and transmitting the temperature inside the atmospheric furnace to the PLC; the PLC is used for controlling the heating temperature of the electric heating wire according to the temperature in the atmosphere furnace, so that the temperature in the atmosphere furnace is kept constant.
Optionally, the clamping structure includes: two fixing devices;
the two fixing devices are respectively positioned below the micro-sample and distributed on two sides of the pressure medium pipeline;
the fixing device comprises a support ring, an upright post and a compression ring;
one side of the support ring is connected with the micro-sample, the other side of the support ring is connected with one end of the upright post, and the other end of the upright post is fixed on the ground; the upright post is fixedly connected with one end of each of the two cuboid grooves;
the compression ring is used for compressing and fixing the micro-sample on the support ring.
Optionally, the system further includes: a support stand and a cross beam;
the clamping structure, the temperature control device and the bulging deformation measuring system are all positioned in the supporting rack;
the laser emitter and the CCD camera in the bulging deformation measuring system, and the other end of the upright post in the clamping structure are fixed on the inner wall of the support rack; a cuboid groove of an atmospheric furnace in the temperature control device is fixed on the support rack through a cross beam; the crossbeam is adjustable structure, the crossbeam is used for adjusting the upper and lower front and back position of atmospheric furnace.
Optionally, the fluid pressurizing device is a fluid feeding tank, and the fluid medium in the fluid feeding tank is liquid or gas.
A constant stress loading method of a constant stress loading system based on the creep property bulging test of the micro test sample comprises the following steps:
measuring the bulging deformation data of the micro sample by using a laser interference method;
generating a finite element calculation model according to the bulging deformation data;
calculating the stress value of each deformation point on the micro sample by using a finite element analysis method according to the finite element calculation model, and selecting the stress value of the arch vertex of the micro sample as the stress value of the micro sample under the current load pressure;
adjusting the stress value of the micro sample under the current load pressure to enable the stress value under the adjusted load pressure to be equal to the stress value under the reference load pressure, and acquiring the adjusted load pressure as the adjusted load pressure;
adjusting the fluid pressure applied to the micro-sample according to the adjusting load pressure, so that the adjusted fluid pressure is equal to the adjusting load pressure;
and repeating the steps until the creep property bulging test of the micro test sample is finished.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention discloses a constant stress loading system and a method for a micro sample creep property bulging test.A temperature control device enables a micro sample to be in a constant temperature environment under the control of a control system, a bulging deformation measuring system measures bulging deformation data of the upper surface of the micro sample and transmits the bulging deformation data to the control system, the control system calculates the adjusting load pressure of the micro sample by adopting a finite element automatic modeling and rapid analysis method according to the bulging deformation data, the control system compares the fluid pressure measured by a pressure gauge with the adjusting load pressure of the micro sample and controls the working state of a pressure regulating device according to the comparison result, so that the fluid pressure is equal to the adjusting load pressure of the micro sample, the sample is kept in a constant stress state by dynamically regulating the pressure load value, and the more accurate high-temperature creep property test of the material micro sample is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a structural diagram of a constant stress loading system for a micro-specimen creep property bulge test provided by the invention;
fig. 2 is a flowchart of a constant stress loading method according to the present invention.
Description of the symbols: the device comprises a CCD camera, a 2-support rack, a 3-beam combining prism, a 4-imaging lens, 5-quartz glass, a 6-atmosphere furnace, a 7-compression ring, an 8-micro sample, a 9-support ring, a 10-upright post, an 11-electric heating wire, a 12-base, a 13-upper computer, a 14-PLC, a 15-fluid feeding groove, a 16-laser emitter, a 17-beam splitter, an 18-beam expander, a 19-pressure medium pipeline, a 20-pressure relief valve, a 21-pressure gauge, a 22-pressure pump and a 23-ground.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a constant stress loading system and a constant stress loading method for a micro-sample creep property bulging test, so as to realize more accurate high-temperature creep property test of a material micro-sample.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
In order to realize more accurate high-temperature creep property test of the micro-sample of the material, the invention provides a constant stress loading system for creep property bulging test of the micro-sample, as shown in fig. 1, the system comprises: the device comprises a clamping structure, a temperature control device, a bulging deformation measuring system, a control system, a fluid pressurizing device, a pressure regulating device and a pressure gauge 21.
The micro sample 8 is fixed on one end of the clamping structure, one end of the clamping structure penetrates through the temperature control device, the micro sample 8 is arranged inside the temperature control device, and the other end of the clamping structure is fixed on the ground 23.
The temperature control device is connected with the control system and is used for enabling the micro-sample 8 to be in a constant temperature environment under the control of the control system.
The output end of the fluid pressurizing device is connected with the lower surface of the micro sample 8, and the pressure regulating device and the pressure gauge 21 are both arranged on the pressure medium pipeline 19 between the output end of the fluid pressurizing device and the lower surface of the micro sample 8; the fluid pressurizing device is used for generating pressure on the lower surface of the micro sample 8 by utilizing the fluid medium so as to generate bulging deformation on the upper surface of the micro sample 8.
The bulging deformation measuring system is connected with the control system and is used for measuring bulging deformation data of the upper surface of the micro test sample 8 and transmitting the bulging deformation data to the control system; the control system is used for calculating the adjusting load pressure of the micro-specimen 8 according to the bulging deformation data.
The control system is also respectively connected with the pressure gauge 21 and the pressure regulating device, and is also used for obtaining the fluid pressure measured by the pressure gauge 21, comparing the fluid pressure with the regulating load pressure of the micro-sample 8, and controlling the working state of the pressure regulating device according to the comparison result to enable the fluid pressure to be equal to the regulating load pressure of the micro-sample 8.
Wherein, bulging deformation measurement system includes: the device comprises a laser transmitter 16, a beam splitter 17, a beam expander 18, an imaging lens 4, a beam combining prism 3 and a CCD camera 1.
The laser emitter 16 is used for emitting laser to the upper surface of the micro sample 8, and a beam splitter 17 and a beam expander 18 are sequentially arranged on the laser emitting light path of the laser emitter 16 and the micro sample 8; the beam splitter 17 is configured to split the laser emitted by the laser emitter 16 into two beams, one beam of laser irradiates the beam combining prism 3, and the other beam of laser irradiates the upper surface of the micro sample 8 after being diffused by the beam expander 18, and generates scattered laser on the upper surface of the micro sample 8.
An imaging lens 4, a beam combining prism 3 and a CCD camera 1 are sequentially arranged on a scattered laser light path generated on the upper surface of the micro sample 8, the scattered laser light is subjected to interference synthesis with a beam of laser light on the beam combining prism 3 after passing through the imaging lens 4, and the laser light after interference synthesis forms bulging deformation data of the micro sample 8 on the CCD camera 1; the CCD camera 1 is connected with the control system, and the CCD camera 1 is used for transmitting the bulging deformation data to the control system.
The pressure regulating device includes: a booster pump 22 and a pressure relief valve 20. The pressure pump 22 and the pressure relief valve 20 are both arranged on the pressure medium pipeline 19 between the output end of the fluid pressurizing device and the lower surface of the micro sample 8; the control end of the booster pump 22 and the control end of the pressure relief valve 20 are both connected to the control system.
The control system includes: a PLC14 and an upper computer 13. The upper computer 13 is respectively connected with the CCD camera 1 and the PLC14, and the upper computer 13 is used for obtaining the adjusting load pressure of the micro sample 8 according to the bulging deformation data output by the CCD camera 1 and transmitting the adjusting load pressure of the micro sample 8 to the PLC 14; the PLC14 is respectively connected with the signal output end of the pressure gauge 21, the control end of the pressure pump 22 and the control end of the pressure relief valve 20, the PLC14 is used for obtaining the fluid pressure measured by the pressure gauge 21, comparing the fluid pressure with the adjusting load pressure of the micro-sample 8, and controlling the working states of the pressure pump 22 and the pressure relief valve 20 according to the comparison result, so that the fluid pressure is equal to the adjusting load pressure of the micro-sample 8.
The temperature control device includes: an atmospheric furnace 6, an electric heating wire 11 and a thermocouple.
The electric heating wire 11, the thermocouple and the micro sample 8 are all arranged inside the atmospheric furnace 6; the atmospheric furnace 6 comprises quartz glass 5 and two cuboid grooves; the one end of two cuboid recesses all is connected with clamping structure, and the other end of two cuboid recesses all is connected with quartz glass 5, forms a confined cavity. Preferably, the thermocouples are respectively arranged at the upper, middle and lower three positions of the atmospheric furnace 6. The quartz glass 5 is high-temperature-resistant quartz glass.
The electric heating wire 11 and the thermocouple are both connected with the PLC14, and the thermocouple is used for measuring the temperature inside the atmospheric furnace 6 and transmitting the temperature inside the atmospheric furnace 6 to the PLC 14; the PLC14 is used to control the heating temperature of the electric heating wire 11 according to the temperature inside the atmospheric furnace 6, so that the inside of the atmospheric furnace 6 is maintained at a constant temperature.
The clamping structure includes: two fixing devices. The two fixing devices are respectively positioned below the micro-sample 8 and distributed on two sides of the pressure medium pipeline 19;
the fixing device comprises a support ring 9, a stand column 10 and a compression ring 7; one side of the support ring 9 is connected with the micro-sample 8, the other side of the support ring 9 is connected with one end of the upright post 10, and the other end of the upright post 10 is fixed on the ground 23; the upright post 10 is fixedly connected with one end of each of the two cuboid grooves; the compression ring 7 is used for compressing and fixing the micro-sample 8 on the support ring 9, so that pressure medium leakage is prevented, and the influence of medium pressure fluctuation on the accuracy of a test result is avoided. The support ring 9 is placed over the upright 10 and is centered on the upright 10.
The system further comprises: supporting the gantry 2 and the beam. The clamping structure, the temperature control device and the bulging deformation measuring system are all positioned in the supporting rack 2; the laser emitter 16, the CCD camera 1 and the other end of the upright post 10 in the clamping structure in the bulging deformation measuring system are all fixed on the inner wall of the support rack 2; a cuboid groove of an atmospheric furnace 6 in the temperature control device is fixed on the support rack 2 through a cross beam; the crossbeam is adjustable structure, and the crossbeam is used for adjusting the upper and lower front and back position of atmospheric furnace 6. The support stand 2 is mounted on the ground 23 for load bearing and fixing. The support rack 2 is composed of two parts of a column of the support rack 2 and a base 12, and the inverted U-shaped structure connected above the base 12 is the column of the support rack 2.
The fluid pressurizing device is a fluid feeding tank 15, and the fluid medium in the fluid feeding tank 15 is liquid or gas. The fluid feed channel 15 is used to contain a fluid medium for testing, typically a gas cylinder when using gas as the medium and a cylindrical vessel when using liquid as the medium.
The test device provided by the invention is standard in test, the pressure load value is dynamically adjusted to keep the sample in a constant stress state, and the test precision is high.
Based on the constant stress loading system for the creep property bulging test of the micro test sample, the invention also provides a constant stress loading method, as shown in fig. 2, the method comprises the following steps:
102, generating a finite element calculation model according to the bulging deformation data;
103, calculating stress values of all deformation points on the micro sample by using a finite element analysis method according to a finite element calculation model, and selecting the stress value of the arch top of the micro sample as the stress value of the micro sample under the current load pressure;
and step 106, repeating the steps until the creep property bulging test of the micro test sample is finished.
The detailed implementation process is as follows:
the method comprises the following steps: the laser full-field deformation measurement system is arranged to cover the bulge test area of the micro-sample 8 to be measured.
Step two: on one side of the micro sample bulging deformation, the full-field deformation (displacement) of the bulging sample is measured by a laser interference method, and deformation data is collected into a data analyzer.
Step three: and generating a finite element calculation model from all the deformation data measured by the laser in real time by using data processing software.
Step four: the finite element model automatically calculates the stress state of the sample, and adjusts the load to keep the constant stress state. During analysis, the stress distribution condition of the sample is calculated according to the current pressure load (a load pressure value can be randomly given in an initial state). And selecting the dome part of the micro test sample with the largest deformation, if the calculated stress value is lower than the target value, increasing the load pressure for calculation again, otherwise, reducing the load pressure until the deviation of the stress value of the dome top part and the target value is less than 0.01 percent of the target value, and the calculated load pressure is the load pressure value to be applied next step.
The finite element analysis system is used for receiving the image collected by the CCD camera, analyzing and converting the characteristic image by using special software to obtain the displacement deformation of each point in the upper surface measurement area of the test piece, generating a three-dimensional solid model by using a tool carried by the software, determining a calculated pressure value by using a finite element analysis method, and transmitting the calculated pressure value to the PLC.
Step five: and according to the load pressure value, controlling the pressure value of the pressure loading pipeline through the PLC, so that the deviation between the applied load pressure and the calculated load pressure is less than 0.1 percent of the calculated load pressure.
And the PLC carries out comparative analysis according to the transmitted calculated load pressure value and the pipeline pressure value transmitted by the pressure gauge. If the calculated load pressure value is higher than the pipeline pressure value, transmitting a pressurization instruction to the pressurization pump, closing the pressure release valve, and increasing the pipeline pressure value until the calculated load pressure value is reached; otherwise, the pressurizing pump is closed, the pressure relief valve is opened, and the pipeline pressure is reduced until the load pressure value is calculated.
Step six: the operations from step one to step five were repeated every 1 second until the end of the test (breaking of the specimen).
The invention firstly carries out measurement on the bulging degree of the sample based on the laser interferometry, and obtains the displacement data of the full deformation field.
And inputting the displacement data into a computer, processing the displacement data by special software to produce a three-dimensional finite element model of the sample, and automatically performing finite element calculation to obtain the calculated load pressure corresponding to the constant stress.
The PLC control system adjusts the pressure of the test pipeline according to the calculated load pressure transmitted by the computer in a pressurization or discharge mode, so that the deviation between the pressure of the test pipeline and the calculated load pressure is kept within an allowable error range.
Because the sample is continuously expanded and deformed in the sample process and the load pressure needs to be dynamically adjusted, the working engineering of measurement, modeling, calculation and regulation is repeated every 5 s.
At present, all similar bulging test devices cannot realize the measurement of the mechanical properties of materials in a high-temperature and constant-stress state, and some data needing to be measured in the constant-stress state can only adopt approximate values, so that the deviation of test and analysis results is large. The invention aims to provide a constant stress test method for testing the high-temperature creep performance of a micro sample. In the test process, according to the finite element analysis result, the pressure load borne by the sample is adjusted in real time by using the PLC and the pressure loading control system, so that the sample is always in an optimal constant stress state in the whole test process.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (9)
1. A constant stress loading system for micro specimen creep performance bulge testing, the system comprising: the device comprises a clamping structure, a temperature control device, a bulging deformation measuring system, a control system, a fluid pressurizing device, a pressure regulating device and a pressure gauge;
the micro sample is fixed on one end of the clamping structure, one end of the clamping structure penetrates through the temperature control device, the micro sample is arranged in the temperature control device, and the other end of the clamping structure is fixed on the ground;
the temperature control device is connected with the control system and is used for enabling the micro-sample to be in a constant temperature environment under the control of the control system;
the output end of the fluid pressurizing device is connected with the lower surface of the micro sample, and the pressure regulating device and the pressure gauge are both arranged on a pressure medium pipeline between the output end of the fluid pressurizing device and the lower surface of the micro sample; the fluid pressurizing device is used for generating pressure on the lower surface of the micro sample by using a fluid medium so as to enable the upper surface of the micro sample to generate bulging deformation;
the bulging deformation measuring system is connected with the control system and is used for measuring bulging deformation data of the upper surface of the micro sample and transmitting the bulging deformation data to the control system; the control system is used for calculating the adjusting load pressure of the micro sample according to the bulging deformation data;
the control system is also used for acquiring the fluid pressure measured by the pressure gauge, comparing the fluid pressure with the adjusting load pressure of the micro-sample, and controlling the working state of the pressure adjusting device according to the comparison result to enable the fluid pressure to be equal to the adjusting load pressure of the micro-sample.
2. The system of claim 1, wherein the bulge deformation measurement system comprises: the device comprises a laser transmitter, a beam splitter, a beam expander, an imaging lens, a beam combining prism and a CCD camera;
the laser emitter is used for emitting laser to the upper surface of the micro sample, and a beam splitter and a beam expander are sequentially arranged on the laser emitter and the laser emitting light path of the micro sample; the beam splitter is used for splitting laser emitted by the laser emitter into two beams, one beam of laser irradiates the beam combining prism, the other beam of laser irradiates the upper surface of the micro sample after being diffused by the beam splitter, and scattered laser is generated on the upper surface of the micro sample;
an imaging lens, a beam combining prism and a CCD camera are sequentially arranged on a scattered laser light path generated on the upper surface of the micro sample, the scattered laser light is subjected to interference synthesis with a beam of laser light on the beam combining prism after passing through the imaging lens, and the laser light after the interference synthesis forms bulging deformation data of the micro sample on the CCD camera;
the CCD camera is connected with the control system and used for transmitting the bulging deformation data to the control system.
3. The system of claim 2, wherein the pressure adjustment device comprises: a pressure pump and a pressure relief valve;
the pressurizing pump and the pressure relief valve are both arranged on a pressure medium pipeline between the output end of the fluid pressurizing device and the lower surface of the micro sample;
and the control end of the pressurizing pump and the control end of the pressure relief valve are both connected with the control system.
4. The system of claim 3, wherein the control system comprises: a PLC and an upper computer;
the upper computer is respectively connected with the CCD camera and the PLC and is used for obtaining the adjusting load pressure of the micro-sample according to the bulging deformation data output by the CCD camera and transmitting the adjusting load pressure of the micro-sample to the PLC;
the PLC is respectively connected with the signal output end of the pressure gauge, the control end of the pressure pump and the control end of the pressure relief valve, and is used for obtaining the fluid pressure measured by the pressure gauge, comparing the fluid pressure with the adjusting load pressure of the micro-sample, and controlling the working states of the pressure pump and the pressure relief valve according to the comparison result, so that the fluid pressure is equal to the adjusting load pressure of the micro-sample.
5. The system of claim 4, wherein the temperature control device comprises: an atmospheric furnace, an electric heating wire and a thermocouple;
the electric heating wire, the thermocouple and the micro sample are all arranged inside the atmospheric furnace;
the atmospheric furnace comprises quartz glass and two cuboid grooves;
one end of each of the two cuboid grooves is connected with the clamping structure, and the other end of each of the two cuboid grooves is connected with the quartz glass to form a closed cavity;
the electric heating wire and the thermocouple are connected with the PLC, and the thermocouple is used for measuring the temperature inside the atmospheric furnace and transmitting the temperature inside the atmospheric furnace to the PLC; the PLC is used for controlling the heating temperature of the electric heating wire according to the temperature in the atmosphere furnace, so that the temperature in the atmosphere furnace is kept constant.
6. The system of claim 5, wherein the clamping structure comprises: two fixing devices;
the two fixing devices are respectively positioned below the micro-sample and distributed on two sides of the pressure medium pipeline;
the fixing device comprises a support ring, an upright post and a compression ring;
one side of the support ring is connected with the micro-sample, the other side of the support ring is connected with one end of the upright post, and the other end of the upright post is fixed on the ground; the upright post is fixedly connected with one end of each of the two cuboid grooves;
the compression ring is used for compressing and fixing the micro-sample on the support ring.
7. The system of claim 6, further comprising: a support stand and a cross beam;
the clamping structure, the temperature control device and the bulging deformation measuring system are all positioned in the supporting rack;
the laser emitter and the CCD camera in the bulging deformation measuring system, and the other end of the upright post in the clamping structure are fixed on the inner wall of the support rack; a cuboid groove of an atmospheric furnace in the temperature control device is fixed on the support rack through a cross beam; the crossbeam is adjustable structure, the crossbeam is used for adjusting the upper and lower front and back position of atmospheric furnace.
8. The system of claim 1, wherein the fluid pressurizing device is a fluid feed tank, and the fluid medium in the fluid feed tank is a liquid or a gas.
9. A constant stress loading method based on the constant stress loading system for the creep property bulge test of the micro-specimen according to any one of claims 1 to 8, wherein the method comprises the following steps:
measuring the bulging deformation data of the micro sample by using a laser interference method;
generating a finite element calculation model according to the bulging deformation data;
calculating the stress value of each deformation point on the micro sample by using a finite element analysis method according to the finite element calculation model, and selecting the stress value of the arch vertex of the micro sample as the stress value of the micro sample under the current load pressure;
adjusting the stress value of the micro sample under the current load pressure to enable the stress value under the adjusted load pressure to be equal to the stress value under the reference load pressure, and acquiring the adjusted load pressure as the adjusted load pressure;
adjusting the fluid pressure applied to the micro-sample according to the adjusting load pressure, so that the adjusted fluid pressure is equal to the adjusting load pressure;
and repeating the steps until the creep property bulging test of the micro test sample is finished.
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