A seawater fatigue cycle simulation test device and test method

Abstract

The present invention discloses a seawater fatigue cycle simulation test device, which includes a circulating pressure chamber cylinder body and a test chamber cylinder body, which are respectively sealed by upper end covers and communicated through a connecting pipe string on the side. A pressure guiding rod is arranged in the connecting pipe string, and both ends of the pressure guiding rod extend into the circulating pressure chamber cylinder body and the test chamber cylinder body, and are respectively connected with a pressure receiving block and a pressure guiding block. The sides of the pressure receiving block and the pressure guiding block are sealed with the inner surfaces of the circulating pressure chamber cylinder body and the test chamber cylinder body through a first sealing gasket. An anti-corrosion plate is attached to the surface of the test chamber. A high-pressure water inlet pipe, a water outlet pipe and a pressure relief needle valve are arranged on the upper end cover of the circulating pressure chamber cylinder body. A water delivery pipe, a pressure sensor and a pressure relief needle valve are arranged on the upper end cover of the test chamber cylinder body. The device also includes a control system. The present invention can apply cyclic pressure and maintain pressure, is convenient for manufacturing, transportation, installation and use, has good sealing performance, low noise, and is more in line with the seawater fatigue cycle simulation test.

Description

Technical Field

[0001] The present invention relates to the field of marine equipment, and particularly to a seawater fatigue cycle simulation test device and a test method. Background Art

[0002] With the increasing progress of science and technology, the demand for the exploration and development of marine resources by humans is becoming increasingly strong. The exploration of the ocean is based on the research and development of deep-sea equipment. Therefore, the research and development of marine environment simulation test equipment is very important. Marine environment simulation test equipment can effectively reduce the research and development costs and cycle of marine equipment.

[0003] Currently, in the field of water pressure environment simulation test equipment, the test devices have the following deficiencies:

[0004] (1) During the water pressure application process, most of the test specimens are damaged by static pressure, which is quite different from the pressure environment that marine engineering equipment experiences during actual use;

[0005] (2) Most water pressure simulation test equipment uses water with little corrosion as the medium, ignoring the corrosiveness of actual seawater to metal containers;

[0006] (3) The loading of water pressure simulation tests is all static loads, without considering the diversity of cyclic loads, such as triangular waves, sine waves, trapezoidal waves, etc.;

[0007] (4) Due to the large test chamber, the convenience of installation, operation, and maintenance is not considered. Summary of the Invention

[0008] Object of the Invention: In order to overcome the deficiencies of the background art, the first object of the present invention is to disclose a seawater fatigue cycle simulation test device, and the second object is to disclose a seawater fatigue cycle simulation test method using the above test device.

[0009] Technical Solution: The seawater fatigue cycle simulation test device disclosed by the present invention includes a cyclic pressure chamber cylinder body and a test chamber cylinder body, which are respectively sealed by upper end covers. The cyclic pressure chamber cylinder body and the test chamber cylinder body are connected by a connecting pipe column on the side. A pressure guiding rod is arranged in the connecting pipe column. Both ends of the pressure guiding rod extend into the cyclic pressure chamber cylinder body and the test chamber cylinder body, and are respectively connected with a pressure-receiving block and a pressure guiding block. The sides of the pressure-receiving block and the pressure guiding block are sealed with the inner surfaces of the cyclic pressure chamber cylinder body and the test chamber cylinder body by first sealing gaskets. The surface of the side of the pressure-receiving block away from the pressure guiding rod and the inner surface of the cyclic pressure chamber cylinder body form a pressure chamber. The surface of the side of the pressure guiding block away from the pressure guiding rod and the inner surface of the test chamber cylinder body form a test chamber. An anti-corrosion plate is attached to the surface of the test chamber. A high-pressure water inlet pipe, a water outlet pipe, and a pressure relief needle valve are arranged on the upper end cover of the cyclic pressure chamber cylinder body. A water delivery pipe, a pressure sensor, and a pressure relief needle valve are arranged on the upper end cover of the test chamber cylinder body;

[0010] It further includes a control system, which comprises an air compressor, a driving pressure regulating valve, a driving pressure gauge, a first solenoid valve, a gas-liquid boosting pump, a water tank, a second solenoid valve, a pressure transmitter, a throttle valve, a corrosion-resistant pump and a control platform. The air compressor is connected to the driving pressure regulating valve. The driving pressure gauge is connected to the driving pressure regulating valve and the first solenoid valve. The gas-liquid boosting pump is respectively connected to the first solenoid valve, the water tank and the high-pressure water inlet pipe. The water outlet pipe is connected to the water tank, and a second solenoid valve, a pressure transmitter and a throttle valve are arranged therebetween. The control platform is connected to the first solenoid valve, the second solenoid valve, the pressure transmitter, the throttle valve and the corrosion-resistant pump.

[0011] Furthermore, the control platform includes an A / D converter, an industrial control computer, a D / A converter, a driver and an oscilloscope. The driver is connected to the first solenoid valve, the second solenoid valve and the throttle valve. The A / D converter is connected to the pressure transmitter and the pressure sensor. The preset pressure P1, the critical pressure P0, the number of cyclic pressure applications n, the single-time pressure holding time t0, the pressure increasing time t1 and the pressure unloading time t2 can be set through the control platform. The set preset pressure P1 is the target pressure value for the fatigue cyclic compression of the test piece.

[0012] Furthermore, threaded through holes are opened on the upper end cover, and the press-in water pipe, the water outlet pipe, the pressure relief needle valve, the water delivery pipe and the pressure sensor are connected to the upper end cover through the threaded through holes.

[0013] Furthermore, the sealing structures of the cyclic pressure chamber cylinder body and the test chamber cylinder body with the upper end cover are the same. The upper opening of the cyclic pressure chamber cylinder body is an inward concave edge, and the lower surface of the upper end cover is an outward convex surface corresponding to and spliced with the inward concave edge. Different surfaces at the splicing part are respectively sealed by a second sealing gasket. A positioning pressing block is arranged on the upper end cover, and the upper edge of the cyclic pressure chamber cylinder body cooperates with the positioning pressing block upward and is fastened by a positioning pressing pin.

[0014] Furthermore, it further includes a gantry. Two vertically downward cylinders are arranged on the gantry, and the extending ends of the cylinders are connected to the upper end cover. Universal wheels are arranged at the bottoms of the gantry, the cyclic pressure chamber cylinder body and the test chamber cylinder body.

[0015] A seawater fatigue cyclic simulation test method uses the above-mentioned seawater fatigue cyclic simulation test device and includes the following steps:

[0016] S1. Open the upper end cover, place the test piece into the test chamber cylinder body, cover the upper end cover, and open the pressure relief needle valve on the upper end cover until the upper end cover tightly abuts against the test chamber cylinder body to form a seal. Turn on the corrosion-resistant pump to input the test liquid into the test chamber cylinder body, and at the same time discharge the air in the test chamber. After the air is exhausted, turn off the corrosion-resistant pump and the pressure relief needle valve successively.

[0017] S2. Set the preset pressure P1, critical pressure P0, number of cyclic pressure applications n, single-hold time t0, pressurization time t1, and unloading time t2 through the control platform. The set preset pressure P1 is the target pressure value for the fatigue cyclic compression of the test piece. Turn on the air compressor, adjust the drive pressure regulating valve, observe the value of the drive pressure gauge to ensure that the input gas pressure is the required value, and start the control platform.

[0018] S3. The control platform controls the energization of the electromagnetic coil of the first solenoid valve, and the gas is input into the gas-liquid booster pump. The water in the water tank is injected into the cylinder body of the cyclic pressure chamber through the gas-liquid booster pump. The pressure in the cyclic pressure chamber gradually rises, and the pressure passes through the pressure-receiving block, and is introduced into the test chamber through the pressure guiding rod and the pressure guiding block. The real-time pressure in the test chamber is output to the control platform through the pressure sensor.

[0019] S4. When the pressure in the test chamber increases to the preset pressure P1, the control platform controls the power-off of the electromagnetic coil of the first solenoid valve, and the liquid path is disconnected. The test chamber enters the pressure-holding stage. After the pressure-holding time reaches t0, the control platform controls the opening of the second solenoid valve, and the liquid in the cyclic pressure chamber flows back to the water tank through the water outlet pipe, throttle valve, and second solenoid valve. After the unloading time reaches t2, the pressure in the test chamber drops to the critical value P0, and the control platform controls the closing of the second solenoid valve.

[0020] S5. Repeat steps S3 - S4 until the number of test repetitions reaches the number of cyclic pressure applications n of the control platform, end the test, and stop the cycle. After the test ends, control the opening of the second solenoid valve through the control platform to maintain the unloading state. When the control platform shows that the real-time pressure in the test chamber is 0, the control platform controls the closing of the second solenoid valve, opens the pressure relief needle valve to relieve the pressure in the test chamber body, opens the upper end cover, and takes out the test piece for observation.

[0021] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows: An anti-corrosion layer is provided in the test chamber, and corresponding corrosion fatigue tests can be carried out on the test piece; the corrosive liquid in the test chamber only passes through the corrosion-resistant pump and does not pass through other electrical components, effectively protecting other metal parts; a high-pressure water inlet pipe is provided in the cyclic pressure chamber to control the internal pressure of the chamber body. The pressure environment is stable, easy to adjust, and a pressure cyclic fatigue environment can be realized; a control platform is provided, which can realize the control and adjustment of applying cyclic pressure and pressure holding to the test piece, and can realize functions such as timing, counting for the experiment, monitoring the real-time pressure in the test chamber, and recording and outputting relevant test data. Description of the Drawings

[0022] Figure 1 It is the general structure diagram of the present invention;

[0023] Figure 2 It is the cross-sectional view of the cylinder body of the cyclic pressure chamber and the cylinder body of the test chamber of the present invention;

[0024] Figure 3 This is the external three-dimensional view of the cylinder body of the cyclic pressure chamber and the cylinder body of the test chamber of the present invention;

[0025] Figure 4 is Figure 2 the partial enlarged view of A in

[0026] Figure 5 This is the schematic diagram of the control platform of the present invention;

[0027] Figure 6 is Figure 2 the partial enlarged view of B in

[0028] Figure 7 is Figure 2 the partial sectional view of C in Specific embodiments

[0029] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0030] As Figures 1-4 shown in the seawater fatigue cycle simulation test device, which includes a cyclic pressure chamber cylinder body 1 and a test chamber cylinder body 2, which are respectively sealed by upper end covers 3. The sides of the cyclic pressure chamber cylinder body 1 and the test chamber cylinder body 2 are connected by a connecting pipe string 4. A pressure guiding rod 5 is arranged in the connecting pipe string 4. Both ends of the pressure guiding rod 5 extend into the cyclic pressure chamber cylinder body 1 and the test chamber cylinder body 2, and are respectively connected with a pressure receiving block 6 and a pressure guiding block 7. The sides of the pressure receiving block 6 and the pressure guiding block 7 are sealed with the inner surfaces of the cyclic pressure chamber cylinder body 1 and the test chamber cylinder body 2 by a first sealing gasket 8. The surface of the pressure receiving block 6 away from the pressure guiding rod 5 forms a pressure chamber with the inner surface of the cyclic pressure chamber cylinder body 1. The surface of the pressure guiding block 7 away from the pressure guiding rod 5 forms a test chamber with the inner surface of the test chamber cylinder body 2. An anti-corrosion plate 9 is attached to the surface of the test chamber. The material of the anti-corrosion plate is selected as polytetrafluoroethylene, which has a relatively low cost and good seawater corrosion resistance. A high-pressure water inlet pipe 10, a water outlet pipe 11 and a pressure relief needle valve 12 are arranged on the upper end cover of the cyclic pressure chamber cylinder body 1. A water delivery pipe 13, a pressure sensor 14 and a pressure relief needle valve 12 are arranged on the upper end cover of the test chamber cylinder body 2;

[0031] It further includes a control system, which includes an air compressor 15, a driving pressure regulating valve 16, a driving pressure gauge 17, a first solenoid valve 18, a gas-liquid booster pump 19, a water tank 20, a second solenoid valve 21, a pressure transmitter 22, a throttle valve 23, a corrosion-resistant pump 24 and a control platform 25. The air compressor 15 is connected to the driving pressure regulating valve 16. The driving pressure gauge 17 is connected to the driving pressure regulating valve 16 and the first solenoid valve 18. The gas-liquid booster pump 19 is respectively connected to the first solenoid valve 18, the water tank 20 and the high-pressure water inlet pipe 10. The water outlet pipe 11 is connected to the water tank 20, and a second solenoid valve 21, a pressure transmitter 22 and a throttle valve 23 are provided therebetween. The control platform 25 is connected to the first solenoid valve 18, the second solenoid valve 21, the pressure transmitter 22, the throttle valve 23 and the corrosion-resistant pump 24.

[0032] As Figure 5 shown, the control platform 25 includes an A / D converter 2501, an industrial computer 2502, a D / A converter 2503, a driver 2504, and an oscilloscope 2505. The driver 2504 is connected to the first solenoid valve 18, the second solenoid valve 21, and the throttle valve 23. The A / D converter 2501 is connected to the pressure transmitter 22 and the pressure sensor 14. The preset pressure P1, the critical pressure P0, the number of cyclic pressure applications n, the single-time pressure holding time t0, the pressure increasing time t1, and the pressure unloading time t2 can be set through the control platform 25. The set preset pressure P1 is the target pressure value for the fatigue cyclic compression of the test piece.

[0033] Specifically, the main load applied in the present invention is a trapezoidal wave, and the curve displayed on the control platform 25 should conform to the following formula. During the pressure increasing stage: During the pressure holding stage: P = P1; during the pressure unloading stage: where P1 is the preset pressure, t0 is the pressure holding time, t1 is the pressure increasing time, t2 is the pressure unloading time, P is the real-time pressure, t′ is the start time of this cycle, and t is the test time.

[0034] The upper end cover 3 is provided with threaded through holes, and the high-pressure water inlet pipe 10, the water outlet pipe 11, the pressure relief needle valve 12, the water delivery pipe 13 and the pressure sensor 14 are connected to the upper end cover 3 through the threaded through holes.

[0035] The sealing structures of the cyclic pressure chamber cylinder body 1 and the test chamber cylinder body 2 with the upper end cover 3 are the same; the upper opening of the cyclic pressure chamber cylinder body 1 is an inward concave edge, and the lower surface of the upper end cover 3 is an outward convex surface corresponding to and spliced with the inward concave edge, with good self-positioning property.

[0036] As Figure 6 and Figure 7As shown, different surfaces of the splicing part are respectively sealed by a second gasket 26. A positioning and pressing block 27 is provided on the upper end cover 3. The upper edge of the circulating pressure chamber cylinder body 1 cooperates with the positioning and pressing block 27 upward and is fastened by a positioning and pressing pin 28. With multiple seals in two forms, the sealing effect is good.

[0037] It further includes a gantry 29. Two vertically downward cylinders 31 are provided on the gantry 29. The extended end of the cylinder 31 is connected to the upper end cover 3. Universal wheels 30 are provided at the bottoms of the gantry 29, the circulating pressure chamber cylinder body 1 and the test chamber cylinder body 2.

[0038] Using the above-mentioned seawater fatigue cycle simulation test device, the method for conducting a seawater fatigue cycle simulation test includes the following steps:

[0039] S1. Open the upper end cover 3, place the test piece into the test chamber cylinder body 2, cover the upper end cover 3, open the pressure relief needle valve 12 on the upper end cover 3 until the upper end cover 3 tightly abuts against the test chamber cylinder body 2 to form a seal; turn on the corrosion-resistant pump 24 to input the test liquid into the test chamber cylinder body 2, and at the same time discharge the air in the test chamber. After the air is exhausted, turn off the corrosion-resistant pump 24 and the pressure relief needle valve 12 successively;

[0040] S2. Set the preset pressure P1, critical pressure P0, number of cyclic pressure applications n, single-time pressure holding time t0, pressurization time t1, and pressure unloading time t2 through the control platform 25. The set preset pressure P1 is the target pressure value for the fatigue cycle compression of the test piece. Turn on the air compressor 15, adjust the driving pressure regulating valve 16, observe the value of the driving air pressure gauge 17 to ensure that the input gas pressure is the required value, and start the control platform 25;

[0041] S3. The control platform 25 controls the electromagnetic coil of the first solenoid valve 18 to be energized, and the gas is input into the gas-liquid booster pump 19. The water in the water tank 20 is injected into the circulating pressure chamber cylinder body 1 through the gas-liquid booster pump 19. The pressure in the circulating pressure chamber gradually rises. The pressure passes through the pressure-receiving block 6, and is introduced into the test chamber through the pressure guiding rod 5 and the pressure guiding block 7. The real-time pressure in the test chamber is output to the control platform 25 through the pressure sensor 14;

[0042] S4. When the pressure in the test chamber increases to the preset pressure P1, the control platform 25 controls the electromagnetic coil of the first solenoid valve 18 to be de-energized, the liquid path is disconnected, and the test chamber enters the pressure holding stage; after the pressure holding time reaches t0, the control platform 25 controls the second solenoid valve 21 to open, and the liquid in the circulating pressure chamber flows back into the water tank 20 through the water outlet pipe 11, the throttle valve 23, and the second solenoid valve 21; after the pressure unloading time reaches t2, the pressure in the test chamber drops to the critical value P0, and the control platform 25 controls the second solenoid valve 21 to close;

[0043] S5. Repeat steps S3 - S4 until the number of test repetitions reaches the cyclic pressure application times n of the control platform 25, end the test, and stop the cycle; when the test ends, control the second solenoid valve 21 to open through the control platform 25 to maintain the unloading state. When the control platform 25 shows that the real-time pressure in the test chamber is 0, the control platform 25 controls the second solenoid valve 21 to close, open the pressure relief needle valve 12 to relieve the pressure in the test chamber body, open the upper end cover 3, and take out the test piece for observation.

Claims

1. A seawater fatigue cycle simulation test device, characterized in that: It includes a circulating pressure chamber cylinder body (1) and a test chamber cylinder body (2), which are respectively sealed by upper end covers (3). The sides of the circulating pressure chamber cylinder body (1) and the test chamber cylinder body (2) are connected by a connecting pipe string (4). A pressure guiding rod (5) is arranged inside the connecting pipe string (4). Both ends of the pressure guiding rod (5) extend into the circulating pressure chamber cylinder body (1) and the test chamber cylinder body (2), and are respectively connected with a pressure receiving block (6) and a pressure guiding block (7). The sides of the pressure receiving block (6) and the pressure guiding block (7) are sealed with the inner surfaces of the circulating pressure chamber cylinder body (1) and the test chamber cylinder body (2) through a first gasket (8). The surface of the side of the pressure receiving block (6) away from the pressure guiding rod (5) and the inner surface of the circulating pressure chamber cylinder body (1) form a pressure chamber. The surface of the side of the pressure guiding block (7) away from the pressure guiding rod (5) and the inner surface of the test chamber cylinder body (2) form a test chamber. An anti-corrosion plate (9) is attached to the surface of the test chamber. A high-pressure water inlet pipe (10), a water outlet pipe (11) and a pressure relief needle valve (12) are arranged on the upper end cover of the circulating pressure chamber cylinder body (1). A water delivery pipe (13), a pressure sensor (14) and a pressure relief needle valve (12) are arranged on the upper end cover of the test chamber cylinder body (2); It further includes a control system. The control system includes an air compressor (15), a driving pressure regulating valve (16), a driving pressure gauge (17), a first solenoid valve (18), a gas-liquid booster pump (19), a water tank (20), a second solenoid valve (21), a pressure transmitter (22), a throttle valve (23), a corrosion-resistant pump (24) and a control platform (25). The air compressor (15) is connected to the driving pressure regulating valve (16). The driving pressure gauge (17) is connected to the driving pressure regulating valve (16) and the first solenoid valve (18). The gas-liquid booster pump (19) is respectively connected to the first solenoid valve (18), the water tank (20) and the high-pressure water inlet pipe (10). The water outlet pipe (11) is connected to the water tank (20), and a second solenoid valve (21), a pressure transmitter (22) and a throttle valve (23) are arranged therebetween. The control platform (25) is connected to the first solenoid valve (18), the second solenoid valve (21), the pressure transmitter (22), the throttle valve (23) and the corrosion-resistant pump (24).

2. The seawater fatigue cycle simulation test device according to claim 1, characterized in that: The control platform (25) includes an A / D converter (2501), an industrial control computer (2502), a D / A converter (2503), a driver (2504), and an oscilloscope (2505). Among them, the driver (2504) is connected to the first solenoid valve (18), the second solenoid valve (21), and the throttle valve (23). The A / D converter (2501) is connected to the pressure transmitter (22) and the pressure sensor (14). The preset pressure P1, the critical pressure P0, the number of cyclic pressure applications n, the single-time pressure holding time t0, the pressure increasing time t1, and the pressure unloading time t2 can be set through the control platform (25). The set preset pressure P1 is the target pressure value for the fatigue cycle pressure of the test piece.

3. The seawater fatigue cycle simulation test device according to claim 1, characterized in that: the upper end cover (3) is provided with threaded through holes, and the high-pressure water inlet pipe (10), the water outlet pipe (11), the pressure relief needle valve (12), the water delivery pipe (13) and the pressure sensor (14) are connected to the upper end cover (3) through the threaded through holes.

4. The seawater fatigue cycle simulation test device according to claim 1, characterized in that: the sealing structures of the circulating pressure chamber cylinder body (1) and the test chamber cylinder body (2) are the same as that of the upper end cover (3); the upper opening of the circulating pressure chamber cylinder body (1) is an inward concave edge, and the lower surface of the upper end cover (3) is an outward convex surface corresponding to and spliced with the inward concave edge. Different surfaces at the splicing part are respectively sealed by a second sealing gasket (26). A positioning pressing block (27) is provided on the upper end cover (3). The upper edge of the circulating pressure chamber cylinder body (1) cooperates with the positioning pressing block (27) upward and is fastened by a positioning pressing pin (28).

5. The seawater fatigue cycle simulation test device according to claim 1, characterized in that: it further includes a gantry (29). Two vertically downward cylinders (31) are provided on the gantry (29). The extending ends of the cylinders (31) are connected to the upper end cover (3). Universal wheels (30) are provided at the bottoms of the gantry (29), the circulating pressure chamber cylinder body (1) and the test chamber cylinder body (2).

6. A seawater fatigue cycle simulation test method, characterized in that, using the seawater fatigue cycle simulation test device according to claim 1, including the following steps: S1. Open the upper end cover (3), place the test piece to be tested into the test chamber cylinder body (2), cover the upper end cover (3), open the pressure relief needle valve (12) on the upper end cover (3) until the upper end cover (3) tightly abuts against the test chamber cylinder body (2) to form a seal; turn on the corrosion-resistant pump (24) to input the test liquid into the test chamber cylinder body (2), and at the same time discharge the air in the test chamber. After the air is exhausted, turn off the corrosion-resistant pump (24) and the pressure relief needle valve (12) successively; S2. Set the preset pressure P1, the critical pressure P0, the number of cyclic pressure applications n, the single-time pressure holding time t0, the pressurization time t1, and the pressure unloading time t2 through the control platform (25). The set preset pressure P1 is the target pressure value for the fatigue cycle compression of the test piece. Turn on the air compressor (15), adjust the driving pressure regulating valve (16), observe the value of the driving air pressure gauge (17) to ensure that the input gas pressure is the required value, and start the control platform (25); S3. The control platform (25) controls the electromagnetic coil of the first solenoid valve (18) to be energized, and the gas is input into the gas-liquid booster pump (19). The water in the water tank (20) is injected into the circulating pressure chamber cylinder body (1) through the gas-liquid booster pump (19). The pressure in the circulating pressure chamber gradually rises. The pressure passes through the pressure receiving block (6), and is introduced into the test chamber through the pressure guiding rod (5) and the pressure guiding block (7). The real-time pressure in the test chamber is output to the control platform (25) through the pressure sensor (14); S4. The pressure in the test chamber increases to the preset pressure P1. The control platform (25) controls the electromagnetic coil of the first solenoid valve (18) to cut off the power, disconnecting the liquid path, and the test chamber enters the pressure holding stage. After the pressure holding time reaches t0, the control platform (25) controls the second solenoid valve (21) to open, and the liquid in the circulating pressure chamber flows back into the water tank (20) through the water outlet pipe (11), throttle valve (23), and second solenoid valve (21). After the unloading time reaches t2, the pressure in the test chamber drops to the critical value P0, and the control platform (25) controls the second solenoid valve (21) to close. S5. Repeat steps S3 - S4 until the number of test repetitions reaches the number of cyclic pressure applications n of the control platform (25), end the test, and stop the cycle. After the test ends, control the second solenoid valve (21) to open through the adjustment control platform (25) to maintain the unloading state. When the control platform (25) shows that the real-time pressure in the test chamber is 0, the control platform (25) controls the second solenoid valve (21) to close, opens the pressure relief needle valve (12) to relieve the pressure inside the test chamber body, opens the upper end cover (3), and takes out the test piece for observation.

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