CN115112471A - A test device and method for testing high temperature creep properties of materials - Google Patents

Abstract

The invention discloses a test device and a method for testing the high-temperature creep property of a material, wherein the device comprises: the device comprises a temperature box, a test device outer frame, a temperature control system, a loading device, a creep test piece, a test piece clamping system, a full-field strain measurement system and a three-axis moving platform; the temperature box is fixed on a base of the outer frame of the testing device; the temperature control device is arranged on the temperature box; the test piece clamping system is placed in the temperature box; the creep test piece is fixed on the test piece clamping system; the loading device is connected with the creep test piece; the three-axis mobile platform is fixed on the outer frame of the testing device; and the full-field strain measurement system is fixed on the three-axis mobile platform. The invention also discloses a non-contact full-field creep test method, which can be used for measuring the local strain of the material by using the full-field strain measurement system, automatically measuring the creep property of the material in a long-time creep test and improving the precision and the efficiency of the creep test.

Description

A test device and method for testing high temperature creep properties of materials

technical field

The invention relates to the technical field of material mechanical property testing, in particular to a testing device and a testing method for testing and analyzing high temperature creep properties of materials.

Background technique

Creep test is a material mechanical property test to measure the phenomenon of slow plastic deformation of metal or non-metal materials under prolonged temperature and load.

The existing creep testing system generally uses a ruler to measure the relationship between the position of the specimen within the gauge length range and the test time to calculate the creep performance of the material. There may be errors in the measurement result itself, and the calculated strain value can only reflect the gauge length. The average strain level within the segment cannot be obtained from the actual strain of the material at different positions, which further limits the accuracy of the results; in addition, the creep test requires long-term, uninterrupted operation. In order to ensure the accuracy of the test results, the entire test The measurement and recording of displacement and time data in the process also have high requirements on the test personnel, and the consistency of repeated test results cannot be guaranteed; moreover, the characteristics of the creep performance test determine that the time for a single test is long. However, due to the limitation of the traditional strain acquisition system, the simultaneous testing of multiple samples requires multiple strain testing systems, which limits the application of simultaneous testing of multiple samples, thus greatly reducing the testing efficiency.

SUMMARY OF THE INVENTION

The invention provides a test device and method for testing the high temperature creep properties of materials, so as to overcome the requirements of strain measurement on test personnel in the creep test, measure the real change relationship of strain at any position of the material with time, and ensure that the test is repeated under repeated tests. The consistency of measurement conditions and the accuracy of measurement data are difficult, and the test efficiency is greatly improved.

For realizing the above-mentioned technical purpose, the technical scheme of the present invention is:

A first aspect of the embodiments of the present invention provides a test device for testing high-temperature creep properties of materials, including: a temperature box, an outer frame of the test device, a temperature control system, a loading device, a creep test piece, and a test piece clamping system, full-field strain measurement system and three-axis mobile platform;

The temperature box is fixed on the foundation base of the outer frame of the test device to keep the temperature inside the temperature box constant;

The temperature control system is arranged on the temperature box, and is used for the control and regulation of the temperature inside the temperature box;

The specimen clamping system is placed inside the temperature box for clamping and fixing the creep specimen;

The upper end bolt holes of the creep specimen are fixed with the specimen clamping system by bolts, and the lower end bolt holes are connected with the loading device for applying the creep load;

The digital camera of the full-field strain measurement system is fixed on the three-axis moving platform, and is used to accurately measure the full-field strain of the creep specimen in the gauge length section and its change with time;

The three-axis moving platform is fixed on the outer frame of the test device, and is used to realize the free movement of the full-field strain measurement system in three directions and the connection between the full-field strain measurement system and the creep specimen. precise focus;

Further, the specimen clamping system also includes a bracket and a clamp system; the clamp system includes two "L"-shaped clamps for clamping the specimen and two "L"-shaped clamps for adjusting the clamp to the creepage. Fasteners that change the clamping degree of the test piece; the "L"-shaped clamps are oppositely arranged, the creep test piece is placed in the middle of the clamps, and the bolts of the fasteners pass through the "L"-shaped clamps. The L"-shaped clamp, the bolt hole of the creep specimen, and the nut of the fastener, the specimen clamping is realized by tightening the bolt and nut.

Further, the temperature box also includes a glass window for non-contact strain measurement;

Further, the fixture system includes six specimen loading positions, and simultaneously realizes multiple repeated tests or multiple load experiments according to test requirements, and simultaneously collects and analyzes test data for all samples under the same test conditions;

Further, when preparing the creep test piece, speckle is sprayed on the gauge length section, and the speckle is required to be uniformly distributed on the surface of the creep test piece.

Further, the full-field strain measurement system includes a digital camera, a data collection processor and a data display; the digital camera and the data display are respectively connected with the data collection processor; the digital camera is used for collecting test data, and the data collection processor and The data display is used to calculate and analyze the collected data and output the test results.

A second aspect of the embodiments of the present invention provides a method for testing and analyzing high temperature creep properties of materials, including the following steps:

S1: Prepare the creep specimen and spray speckle on its surface; fix the creep specimen with the fixture system of the specimen clamping system; place the specimen clamping system inside the temperature box;

S2: The internal temperature of the temperature box is heated to the preset temperature by the temperature control system, and maintained for a sufficient time to ensure that the internal temperature of the temperature box is consistent with the temperature of the creep specimen;

S3: Fix the digital camera of the full-field strain measurement system on the three-axis mobile platform, adjust the position and focus of the digital camera, and take pictures to record the original size of the creep specimen;

S4: Open the door of the temperature box, apply different loads through the loading device, set the digital camera to automatically shoot time-lapse and import the results into the data collection processor;

S5: Use the digital speckle full-field strain measurement method built in the data collection processor to calculate the instantaneous local strain of the creep specimen; use the shooting time recorded by the digital camera to calculate the variation law of strain with time, and obtain the creep curve of the material.

The beneficial effects of the invention are as follows: the invention discloses a method for testing and analyzing the creep properties of materials under the action of a high temperature environment, which is mainly suitable for the study of the deformation amount of materials subjected to tensile force under high temperature and constant load, especially can accurately reveal The local high-temperature creep behavior of materials under different temperature and load conditions is obtained. Specifically, the creep test device and test method perform the creep test on multiple samples at the same time, and automatically collect data on all samples at the same time under the same test conditions and data acquisition conditions, and use digital speckle analysis method. At the same time, the collected data is processed and analyzed, which can effectively avoid the test and analysis errors introduced by the testers in repeated tests, accurately analyze the local creep performance of the material, and greatly improve the test efficiency. The problem of variable failure is important.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments;

Fig. 1 is the overall structure schematic diagram of the high temperature creep test device of the present invention;

Fig. 2 is the structural representation of the temperature box of the present invention;

Fig. 3 is the schematic diagram of the specimen clamping system of the present invention;

4 is a schematic diagram of a fixture system of the specimen clamping system of the present invention;

FIG. 5 is a diagram of the full-field strain measurement system of the present invention and its connection relationship with the three-axis mobile platform;

Fig. 6 is the creep sample size of the present invention;

Fig. 7 is the spraying speckle effect diagram of creep sample of the present invention;

8 is a schematic diagram of an initial speckle position recording method of the present invention;

FIG. 9 is a schematic diagram of the loading conditions of the creep test of the present invention;

Fig. 10 is a graph showing the results of local strain analysis of materials at a certain time obtained by the test device of the present invention;

Fig. 11 is the strain-time relationship diagram drawn by the parameters obtained by the test device of the present invention;

Figure 12 is a flow chart of a method for testing and analyzing high temperature creep properties of a material according to the present invention;

The reference signs in the figure are: 1-temperature box; 11-glass window of temperature box; 2-external frame of test device; 3-temperature control system; 4-loading device; 5-creep specimen; 6-specimen clamp holding system; 7-full-field strain measurement system; 8-three-axis mobile platform; 21-basic base; 61-support; 62-fixture system; 621-"L"-shaped clamp; 622-fastener; 71-digital Camera; 72 - Data Collection Processor; 73 - Data Display.

Detailed ways

This embodiment provides a test device for testing the high temperature creep properties of materials under the action of a high temperature environment. As shown in FIG. 1 , the test device includes: a temperature box 1, an outer frame of the test device 2, and a temperature control system 3. Loading device 4 , creep specimen 5 , specimen clamping system 6 , full-field strain measurement system 7 and three-axis moving platform 8 .

Wherein, the outer frame 2 of the test device is a cube-shaped frame, including 4 columns and 8 beams.

The temperature box 1 is fixed on the basic base 21 of the outer frame 2 of the test device for keeping the temperature inside the temperature box constant.

As shown in FIG. 2 , the temperature control system 3 is arranged in the temperature box 1 for controlling and adjusting the internal temperature of the temperature box 1 .

As shown in FIGS. 3 and 4 , the specimen clamping system 6 is placed inside the temperature box 1 for clamping and fixing the creep specimen 5 . The specimen clamping system 6 includes a bracket 61 and a clamp system 62; the clamp system 62 includes two oppositely arranged "L"-shaped clamps 621 for clamping the creep specimen Fasteners 622 for the clamping degree of the clamps to the creep specimen 5; the two "L"-shaped clamps 621 are correspondingly provided with several fixing holes (bolt holes), and the creep specimens A fixing hole (bolt hole) is opened at the upper end of 5; several creep test pieces 5 are placed in the middle of two "L"-shaped clips 621, and the "L"-shaped clips are passed through the fasteners 622 621 and the threaded hole of the creep specimen 5 for fixing. The bottoms of the two "L"-shaped clips 621 are fixed on the bracket 61 .

The upper end of the creep specimen 5 is fixed with the specimen clamping system 6 by means of bolts, and the lower end is connected with the loading device 4 by means of bolts.

The full-field strain measurement system 7 includes a digital camera 71 , a data collection processor 72 and a data display 73 coupled in sequence, and the digital camera 71 is fixed on the three-axis moving platform 8 . The full-field strain measurement system 7 is used to accurately measure the full-field strain of the creep specimen 5 in the gauge length section and its variation with time.

As shown in FIG. 4 , the three-axis moving platform 8 is fixed on the outer frame 2 of the test device for realizing the free movement of the full-field strain measurement system 7 in three directions and the full-field strain measurement Precise focusing of the system 7 and the creep specimen 5 .

Specifically, the working process of the creep test device provided by the embodiment of the present invention is as follows: firstly prepare a standard sample for creep test, and the size of the sample can refer to relevant standards such as ISO527, as shown in Figure 5; Speckle is sprayed on the gauge length section, and the speckle is composed of white primer and black spots, as shown in Figure 6; the creep samples (1 to 6, 6 in this embodiment) are installed in the specimen clamping system, and the It is placed inside the temperature box; the temperature inside the temperature box is adjusted to reach a preset temperature (100°C in this embodiment), after the temperature is stabilized, the position and focus of the digital camera are adjusted, and a photo is taken as the initial value of the creep calculation. The displacement field, as shown in Figure 7; the creep specimen is loaded by the loading device (the same load can be applied for repeated tests, or different loads can be applied to simultaneously test the creep performance under different stress levels, the loads in this example are respectively 9.5N, 14.2N, 21.8N, 23.0N, 26.0N, 28.4N), as shown in Figure 8; use a digital camera to capture photos, set the digital camera to automatic time-lapse shooting, and automatically shoot once every 2 minutes for the first 30 minutes. After that, images are taken automatically every half an hour; the test is terminated when the test reaches 150 hours, and the data collection processor is used to collect test photos and perform full-field strain analysis, and calculate each test moment through the relative change between the instantaneous position of the speckle and the initial position The instantaneous strain is shown in Figure 9; the corresponding relationship between the instantaneous strain and the test time is determined by the photo number or the time-lapse shooting time, and finally the strain change of the creep specimen with time is obtained, as shown in Figure 10.

A method for testing and analyzing the creep properties of materials under the action of a high temperature environment in this embodiment includes the following steps, as shown in Figure 11:

S1: Prepare the creep specimen and spray speckle on the surface of its gauge length section; fix several creep specimens with the fixture system of the specimen clamping system; place the specimen clamping system inside the temperature box;

S2: The internal temperature of the temperature box is heated to the preset temperature by the temperature control system, and maintained for a sufficient time to ensure that the internal temperature of the temperature box is consistent with the temperature of the creep specimen;

S3: Fix the digital camera of the full-field strain measurement system on the three-axis moving platform, adjust the position and focus of the digital camera, and take pictures to record the original size of each creep specimen;

S4: Open the door of the temperature box, apply different loads to each creep specimen through the loading device, set the digital camera to automatically shoot time-lapse and import the results into the data collection processor;

S5: Use the data collection processor to calculate the instantaneous local strain of the creep specimen; use the shooting time recorded by the digital camera to calculate the variation law of the strain with time, and obtain the creep curve of the material.

Obviously, the above-mentioned embodiments are only used to illustrate the technical solutions of the present invention, but not to limit the specific embodiments; although the present invention has been described in detail with reference to the foregoing embodiments, for those of ordinary skill in the art, it is still possible to Modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements to some or all of the technical features, such as changing the number of "L"-shaped clip holes, the size of the temperature box, etc.; Obvious changes or changes are still within the protection scope of the claims of this patent application.

Claims (6)

1. A test device for testing high temperature creep properties of materials, characterized in that the test device comprises: a temperature chamber (1), an outer frame of the test device (2), a temperature control system (3), a loading device ( 4), creep specimen (5), specimen clamping system (6), full-field strain measurement system (7) and three-axis moving platform (8); The temperature box (1) is fixed on the foundation base (21) of the outer frame (2) of the test device, so as to keep the temperature inside the temperature box constant; The temperature control system (3) is arranged in the temperature box (1) for controlling and adjusting the internal temperature of the temperature box (1); The specimen clamping system (6) is placed inside the temperature box (1) for clamping and fixing the creep specimen (5); The upper end of the creep specimen (5) is fixed with the specimen clamping system (6), and the lower end is connected with the loading device (4); The full-field strain measurement system (7) is used to accurately measure the full-field strain of the creep specimen (5) in the gauge length section and its change with time; The three-axis moving platform (8) is fixed on the outer frame (2) of the test device, and is used to realize the free movement of the full-field strain measurement system (7) in three directions and the full-field strain measurement Focusing of the system (7) and the creep test piece (5). 2. A test device for testing high temperature creep properties of materials according to claim 1, wherein a glass window (11) is also opened on the temperature box (1) for non-contact strain measurement, so The size and position of the glass viewing window (11) should ensure that all creep specimens (5) are within the field of view of the full-field strain measurement system (7) during the creep test. 3. A test device for testing high temperature creep properties of materials according to claim 1, wherein the specimen clamping system (6) further comprises a bracket (61) and a clamp system (62); The clamp system (62) includes two "L"-shaped clamps (621) disposed opposite to each other for clamping the creep test piece (5); the two "L"-shaped clamps (621) are correspondingly open There are several fixing holes, and the upper end of the creep test piece (5) is opened with a fixing hole; the several creep test pieces (5) are correspondingly placed in the middle of the two "L" shaped clamps (621), Fasteners (622) pass through the fixing holes for fixing; the bottoms of the two "L"-shaped clips (621) are fixed on the bracket (61). 4 . The test device for testing high temperature creep properties of materials according to claim 1 , wherein the creep test piece ( 5 ) is sprayed with speckles in the gauge length section. 5 . 5. A test device for testing high-temperature creep properties of materials according to claim 1, wherein the full-field strain measurement system (7) comprises a digital camera (71) coupled in sequence, a data collection processor ( 72) and a data display (73), the digital camera (71) is fixed on the three-axis moving platform (8). 6. A test and analysis method for high temperature creep properties of materials, applied to a test device for testing high temperature creep properties of materials according to any one of claims 1-5, characterized in that, comprising the steps: S1. Prepare the creep specimen (5) and spray speckle on the surface of its gauge length section; fix several creep specimens (5) with the fixture system (62) of the specimen clamping system (6); The parts clamping system (6) is placed inside the temperature box (1); S2. The internal temperature of the temperature box (1) is heated to a preset temperature by the temperature control system (3), and maintained for a sufficient time to ensure that the internal temperature of the temperature box (1) is consistent with the temperature of the creep test piece (5); S3. Fix the digital camera (71) of the full-field strain measurement system (7) on the three-axis moving platform (8), adjust the position and focus of the digital camera (71), and take pictures to record each creep test piece (5). ) original dimensions; S4. Open the box door of the temperature box (1), apply different loads to each creep test piece (5) through the loading device (4), set the digital camera (71) to automatically take time-lapse photography and import the results into data collection and processing device (72); S5. Use the data collection processor (72) to calculate the instantaneous local strain of the creep specimen (5); use the shooting time recorded by the digital camera (71) to calculate the variation law of strain with time, and obtain the creep curve of the material.

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