An off-pile testing fixture and method for measuring creep in structural materials

Abstract

This invention relates to the field of creep characteristics and online measurement of nuclear structural materials, primarily for the study of creep characteristics of nuclear structural materials. It discloses an off-core experimental fixture and method for measuring the creep of structural materials, enabling creep measurement tests to be conducted off-core. The fixture includes a sensor section, a replacement rod, a bellows section, a connector, a clamping nut, a connecting gas pipe, a bellows section support rod, M3 nuts, and M4 nuts. The bellows section, through a double-bellows parallel structure, provides a constant and sufficient tensile force to the sample. The sensor section is used for online monitoring of minute deformations of the sample under prolonged tensile force. The replacement rod, bellows section support rod, and nuts connect and fix the bellows section and the sensor section. The connecting gas pipe is used to fill the bellows section with gas. The connector and clamping nut, matching the gas pipe, are used to connect the gas pipe to the experimental gas control system.

Description

Technical Field

[0001] This invention relates to the field of creep characteristics technology of structural materials, and specifically to an off-site testing fixture and method for measuring the creep of structural materials. Background Technology

[0002] Under the high temperature, high pressure, and strong radiation environment within a reactor, materials subjected to stress typically exhibit significant irradiation creep. The mechanical stability of nuclear fuel and materials is a crucial performance parameter. The creep characteristics of materials indirectly reflect their safe operational status; therefore, it is necessary to monitor changes in creep characteristics in real time. The traditional method for detecting the creep performance of structural materials is usually post-irradiation external inspection. However, external testing struggles to capture the dynamic evolution of material creep performance under irradiation environments such as neutron fields, which is detrimental to revealing the mechanisms of material performance evolution.

[0003] Creep implies slow deformation, thus it strongly embodies the concept of a time effect. Under constant temperature and load conditions, the deformation of a material specimen slowly increases over time; this phenomenon is called creep. Creep can be understood as the change in stress and deformation over time when a solid is subjected to a constant external force. The characteristic of this phenomenon is that the deformation and stress no longer maintain a one-to-one correspondence with the external force, and this deformation remains irreversible even when the stress is below the yield threshold.

[0004] Key factors involved in creep characteristics include providing a constant load and measuring minute deformations. Due to limitations in the size of test channels within the reactor and the complex environment inside the reactor, studying the creep characteristics of materials inside the reactor is extremely difficult. Therefore, before conducting in-reactor studies, it is necessary to design an off-reactor testing fixture for measuring the creep of structural materials to perform off-reactor tests. Summary of the Invention

[0005] The purpose of this invention is to provide an off-pile test fixture and method for measuring the creep of structural materials, which can meet the requirements of constant pressure supply and measurement of minute deformation.

[0006] The technical solution of the present invention is as follows: an off-pile test fixture for measuring creep of structural materials, comprising a sensor section, a replacement rod, a bellows section, a connector, a clamping nut, a connecting air pipe, a bellows section support rod, an M3 nut, and an M4 nut; wherein, the sensor section and the bellows section are connected by the replacement rod and the bellows section support rod; the connecting air pipe is matched with the connector and the clamping nut.

[0007] The sensor section includes a movable rod, a lower sample fixing block, an upper sample fixing block, an LVDT fixing plate, an M3 nut, a sample section support rod, an LVDT fixing block, an LVDT, and a sample. Both ends of the sample are fixed to the upper sample fixing block and the upper sample fixing block, respectively. One end of the LVDT is connected to the LVDT fixing block via a thread, and the other end of the LVDT is fixed to the LVDT fixing plate. One end of the movable rod is fixed to the upper sample fixing block and passes through a pre-drilled hole in the lower sample fixing block. The other end of the movable rod is fixed to the bellows section. One end of the sample section support rod is fixed to the lower sample fixing block, and the other end is fixed to the LVDT fixing block.

[0008] The bellows section includes a lower sealing section of bellows A, bellows A, an upper sealing end of bellows A, a lower sealing end of bellows B, an upper sealing end of bellows B, a bellows connecting rod, an outer sleeve of bellows B, and bellows B. Bellows A is fixed at both ends to the lower sealing end and the upper sealing end of bellows A, respectively. Bellows B is fixed at both ends to the lower sealing end and the upper sealing end of bellows B, respectively. One end of the bellows connecting rod is fixed to the upper sealing end of bellows A, and the other end passes unobstructed through the center hole of the lower sealing end of bellows B and connects to the upper sealing end of bellows B.

[0009] The sensor section and the bellows section are connected by a replacement rod and a bellows section support rod, and are fixed by corresponding M3 nuts and M4 nuts.

[0010] Both ends of the sample are fixed to the sample fixing block and the sample fixing block respectively by threads.

[0011] One end of the movable rod is fixed to the fixed block on the sample by a thread, and the other end is fixed to the bellows section by a thread.

[0012] One end of the sample section support rod is fixed to the lower fixing block of the sample with an M3 nut, and the other end is fixed to the LVDT fixing block with an M3 nut.

[0013] The two ends of the bellows A are welded and fixed to the lower sealing end and the upper sealing end of the bellows A, respectively.

[0014] The two ends of the bellows B are welded and fixed to the lower sealing end and the upper sealing end of the bellows B, respectively.

[0015] Yu: The bellows connecting rod is connected to the sealing end of the bellows B by a thread.

[0016] An off-pile test method for measuring creep of a constant tensile structural material includes the following steps:

[0017] Step 1: Inflate the bellows A with gas through the trachea until it reaches the maximum internal pressure that the bellows A20 can withstand, so that the bellows A provides the maximum tensile force F1;

[0018] Step 2: Inject gas into bellows B through another air tube until bellows B can withstand the maximum internal rolling, so that bellows B provides the maximum tensile force F2.

[0019] Step 3: The maximum tensile forces F1 and F2 provided by the two bellows act simultaneously on the sealing end of bellows B, forming a resultant force F3;

[0020] Step 4: Transfer the resultant force F3 to the fixed block on the sample via the movable rod.

[0021] An off-pile test method for measuring creep in structural materials with small deformation includes the following steps:

[0022] Step 1: The minute deformation of the specimen under a constant tensile force for a long time causes the fixed block on the specimen to move, thus transmitting the minute deformation;

[0023] Step 2: The movement of the fixed block on the sample drives the sealing end of the bellows B to move via the movable rod;

[0024] Step 3: The sealing end of bellows B transmits a small amount of movement to the LVDT fixing plate through the replacement rod;

[0025] Step 4: After the LVDT fixing plate receives the movement, it drives the iron core of the LVDT to move. The displacement-current conversion inside the LVDT is used to transmit the movement amount through an electrical signal, so as to realize the measurement of the minute displacement.

[0026] The significant advantages of this invention are:

[0027] 1. The purpose of this invention is to provide an off-pile test fixture and method for measuring the creep of structural materials that can meet the requirements of constant pressure supply and measurement of minute deformation.

[0028] 2. The bellows section adopts a design of two bellows in parallel. The air pressure in the inner cavity of the two bellows is controlled separately through air pipes. Thus, the two bellows can each provide a certain thrust to the sealing end of the bellows 2, and the two constant thrusts can be combined and transmitted to the sensor section.

[0029] 3. After receiving the thrust transmitted from the bellows section through the movable rod, the sensor section acts on the fixed block on the sample, thereby providing a constant tensile force to the sample.

[0030] 4. After the specimen is subjected to a constant tensile force for a long time, the small deformation will cause the fixed block on the specimen to move slightly. The slight movement of the fixed block on the specimen will cause the sealing end on the bellows 2 to move. The sealing end on the bellows 2 will be transmitted to the LVDT fixing plate through the replacement rod, and then the deformation will be measured by the LVDT.

[0031] 5. The lower sealing section of the bellows 1, the lower fixing block of the sample, and the LVDT fixing block are fixed by the bellows section support rod and the sample section support rod, so as to achieve relative fixation of the whole device and relative movement of the internal parts. Attached Figure Description

[0032] Figure 1 : A schematic diagram of the structure of the present invention;

[0033] Figure 2 :for Figure 1 AA view

[0034] Figure 3 : Figure 1 Schematic diagram of the middle sensor section 1;

[0035] Figure 4 : Figure 1 Triaxial mapping of the middle sensor section 1;

[0036] Figure 5 : Figure 1 Schematic diagram of the structure of corrugated pipe section 2;

[0037] Figure 6 : Figure 1 Triaxial drawing of section 2 of the corrugated pipe.

[0038] Symbol Explanation

[0039] 1. Sensor section, 2. Replacement rod, 3. Bellows section, 4. Connector, 5. Compression nut, 6. Connecting air pipe, 7. Bellows section support rod, 8. M3 nut, 9. M4 nut, 10. Movable rod, 11. Lower fixing block of sample, 12. Upper fixing block of sample, 13. LVDT fixing plate, 14. M3 nut, 15. Sample section support rod, 16. LVDT fixing block, 17. LVDT, 18. Sample, 19. Lower sealing section of bellows A, 20. Bellows A, 21. Upper sealing end of bellows A, 22. Lower sealing end of bellows B, 23. Upper sealing end of bellows B, 24. Bellows connecting rod, 25. Outer tube of bellows A, 26. Bellows B. Detailed Implementation

[0040] To more clearly describe the embodiments of the present invention, the following description, in conjunction with the accompanying drawings and specific embodiments, will illustrate the present invention. The illustrative embodiments and descriptions of the present invention are only for explaining the present invention and are not intended to limit the invention.

[0041] An off-pile test fixture for measuring creep in structural materials. Figure 1As shown, the system includes a sensor section 1, a replacement rod 2, a bellows section 3, a connector 4, a clamping nut 5, a connecting gas pipe 6, a bellows section support rod 7, an M3 nut 8, and an M4 nut 9. The sensor section 1 and the bellows section 3 are connected via the replacement rod 2 and the bellows section support rod 7, and secured with the corresponding M3 nuts 8 and M4 nuts 9. The connecting gas pipe 6 is used to fill the bellows section with inert gas, and its matching connector 4 and clamping nut 5 are used to connect the gas pipe to the experimental gas conditioning system.

[0042] The structural diagram of sensor segment 1 is shown below. Figure 3 As shown. Sensor section 1 includes a movable rod 10, a lower sample fixing block 11, an upper sample fixing block 12, an LVDT fixing plate 13, an M3 nut 14, a sample section support rod 15, an LVDT fixing block 16, an LVDT 17, and a sample 18. Both ends of the sample 18 are fixed to the upper sample fixing block 11 and the lower sample fixing block 12 respectively via threads. The fixed end of the LVDT 17 is connected to the LVDT fixing block 16 via threads, and the other movable end of the LVDT 17 is fixed to the LVDT fixing plate 13 via threads on the bottom of the rod and an M3 nut 14. One end of the movable rod 10 is fixed to the upper sample fixing block 12 via threads, and also passes through a pre-drilled hole in the lower sample fixing block 11. The other end of the movable rod 10 is also threaded for fixing to the bellows section 3. One end of the sample section support rod 15 is fixed to the lower sample fixing block 10 via an M3 nut 14, and the other end is fixed to the LVDT fixing block 16 via an M3 nut 14.

[0043] The structural schematic diagram of corrugated pipe section 3 is shown below. Figure 5 As shown. Bellows section 3 includes a lower sealing section 19 of bellows A, bellows A20, an upper sealing end 21 of bellows A, a lower sealing end 22 of bellows B, an upper sealing end 23 of bellows B, a bellows connecting rod 24, an outer sleeve 25 of bellows B, and bellows B26. Bellows A20 is welded and fixed at both ends to the lower sealing end 19 and the upper sealing end 21 of bellows A, respectively, forming a relatively sealed space. Gas is introduced through a through-hole at the center of the lower sealing end 19 of bellows A. Bellows B26 is welded and fixed at both ends to the lower sealing end 22 and the upper sealing end 23 of bellows B, respectively, forming a relatively sealed space. The gas boundary inside bellows B26 is composed of the lower sealing section 19 of bellows A, the outer sleeve 25 of bellows A, the lower sealing end 22 of bellows B, bellows B26, and the upper sealing end 23 of bellows B. One end of the bellows connecting rod 24 is fixed to the upper sealing end 21 of the bellows A by welding, and the other end passes unobstructed through the center hole of the lower sealing end of the bellows B and is connected to the upper sealing end 23 of the bellows B by thread. Thus, the thrust generated by the bellows can be transmitted from the upper sealing end 21 of the bellows A to the upper sealing end 23 of the bellows B along the bellows connecting rod 24.

Claims

1. A structural material creep measurement out-of-pile test fixture, characterized by: The sensor section (1), the replacement rod (2), the corrugated pipe section (3), the joint (4), the compression nut (5), the connecting air pipe (6), the corrugated pipe section support rod (7), the M3 nut A (8) and the M4 nut (9) are included; wherein the sensor section (1) is connected with the corrugated pipe section (3) through the replacement rod (2) and the corrugated pipe section support rod (7), and is fixed through the corresponding M3 nut A (8) and M4 nut (9); the connecting air pipe (6) is matched with the joint (4) and the compression nut (5); the connecting air pipe (6) is used to fill inert gas into the corrugated pipe section, and the connecting air pipe (6), the joint (4) and the compression nut (5) are used for the connection of the air pipe and the test gas regulating system; The sensor section (1) includes the movable rod (10), the sample lower fixed block (11), the sample upper fixed block (12), the LVDT fixed plate (13), the M3 nut B (14), the sample section support rod (15), the LVDT fixed block (16), the LVDT (17) and the sample (18); the sample (18) is fixed at both ends with the sample lower fixed block (11) and the sample upper fixed block (12), one end of the LVDT (17) is connected with the LVDT fixed block (16) through threads, and the other end of the LVDT (17) is fixed with the LVDT fixed plate (13); one end of the movable rod (10) is fixed with the sample upper fixed block (12), and the other end of the movable rod (10) is fixed with the corrugated pipe section (3) through the through hole reserved in the sample lower fixed block (11); one end of the sample section support rod (15) is fixed with the sample lower fixed block (11) through the M3 nut B (14), and the other end of the sample section support rod (15) is fixed with the LVDT fixed block (16) through the M3 nut B (14); The corrugated pipe section (3) includes the corrugated pipe A lower sealing end (19), the corrugated pipe A (20), the corrugated pipe A upper sealing end (21), the corrugated pipe B lower sealing end (22), the corrugated pipe B upper sealing end (23), the corrugated pipe connecting rod (24), the corrugated pipe A outer sleeve (25) and the corrugated pipe B (26); wherein the corrugated pipe A (20) is fixed at both ends with the corrugated pipe A lower sealing end (19) and the corrugated pipe A upper sealing end (21); the corrugated pipe B (26) is fixed at both ends with the corrugated pipe B lower sealing end (22) and the corrugated pipe B upper sealing end (23), one end of the corrugated pipe connecting rod (24) is fixed with the corrugated pipe A upper sealing end (21), and the other end passes through the center hole of the corrugated pipe B lower sealing end (22) without resistance and is connected with the corrugated pipe B upper sealing end (23); The corrugated pipe A outer sleeve (25) is connected at both ends with the corrugated pipe A lower sealing end (19) and the corrugated pipe B lower sealing end (22); The maximum pulling forces F1 and F2 provided by the two corrugated pipes act on the corrugated pipe B upper sealing end (23) at the same time, forming a resultant force F3; The resultant force F3 is transmitted to the sample upper fixed block (12) through the movable rod (10); The corrugated pipe B upper sealing end (23) transmits a small movement to the LVDT fixed plate (13) through the replacement rod (2); The LVDT fixed plate (13) receives the movement of the LVDT (17) core and transmits the movement through electrical signals by displacement-current conversion inside the LVDT (17), so as to realize the measurement of the micro displacement.

2. A structural material creep measurement ex-reactor test fixture according to claim 1, wherein: The sample (18) is fixed at both ends by threads with the sample lower fixed block (11) and the sample upper fixed block (12).

3. A structural material creep measurement ex-reactor test fixture according to claim 1, wherein: One end of the movable rod (10) is fixed by threads with the sample upper fixed block (12), and the other end is fixed by threads with the corrugated pipe section (3).

4. A structural material creep measurement ex-reactor test fixture according to claim 1, wherein: The corrugated pipe A (20) is welded and fixed at both ends with the corrugated pipe A lower sealing end (19) and the corrugated pipe A upper sealing end (21).

5. A structural material creep measurement ex-reactor test fixture according to claim 1, wherein: The corrugated pipe B (26) is welded and fixed at both ends with the corrugated pipe B lower sealing end (22) and the corrugated pipe B upper sealing end (23).

6. A structural material creep measurement ex-reactor test fixture according to claim 1, wherein: The corrugated pipe connecting rod (24) is connected with the corrugated pipe B upper sealing end (23) by threads.

7. A constant tension structural material creep measurement ex situ test method applied to the structural material creep measurement ex situ test fixture of claim 1, characterized by: The steps include: First step: fill gas into the corrugated pipe A (20) through a gas pipe until the maximum internal pressure that the corrugated pipe A (20) can withstand, so that the corrugated pipe A (20) provides the maximum tension F1; Second step: fill gas into the corrugated pipe B (26) through another gas pipe until the corrugated pipe B (26) can withstand the maximum internal pressure, so that the corrugated pipe B (26) provides the maximum tension F2; Third step: the maximum tensions F1 and F2 provided by the two corrugated pipes simultaneously act on the corrugated pipe B upper sealing end (23) to form the resultant force F3; Fourth step: the resultant force F3 is transmitted to the sample upper fixed block (12) through the movable rod (10).

8. A method for measuring creep of a small deformation structural material outside a reactor pile, using the structural material creep measuring test tooling according to claim 1, characterized in that: The steps include: First step: the micro deformation of the sample (18) under long-term constant tension drives the movement of the sample upper fixed block (12) to transmit the micro deformation; Second step: the movement of the sample upper fixed block (12) drives the movement of the corrugated pipe B upper sealing end (23) through the movable rod (10); Third step: the corrugated pipe B upper sealing end (23) transmits the micro movement to the LVDT fixed plate (13) through the alternative rod (2); Fourth step: the LVDT fixed plate (13) receives the movement of the LVDT (17) core and transmits the movement through electrical signals by displacement-current conversion inside the LVDT (17), so as to realize the measurement of the micro displacement.

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