High-temperature internal pressure tensile torsion composite fatigue test system

Abstract

The invention discloses a high-temperature internal pressure tensile torsion composite fatigue test system, and relates to the technical field of material mechanical property tests.The high-temperature internal pressure tensile torsion composite fatigue test system comprises a furnace body, clamp assemblies are arranged in the furnace body, and the clamp assemblies are used for clamping the two ends of a test piece; the axial loading device is in transmission connection with the clamp assembly and can apply an axial tensile load, an axial compression load and an axial torsion load to the test piece; the annular internal pressure loading device is communicated with the clamp assembly through a pipeline and can introduce gas with set pressure into the test piece through the clamp assembly so as to apply annular internal pressure to the test piece; the temperature control device is connected in the furnace body and can heat the test piece to a set temperature; the measuring assembly can detect deformation data of the test piece in real time. According to the invention, various loads can be applied during the fatigue test, so that the high-temperature real service characteristics of the pipe can be truly reflected.

Description

Technical Field

[0001] This invention relates to the field of material mechanical property testing technology, and in particular to a high-temperature internal pressure tensile torsion composite fatigue testing system. Background Technology

[0002] With the application of pipes made from new materials such as high-temperature alloys and ceramics in aerospace, nuclear power and other fields, high-temperature service conditions have a significant impact on the service performance of pipes. Currently, most mechanical property tests of pipes under high-temperature service environments are based on uniaxial tensile tests. However, the mechanical properties measured by uniaxial tensile tests are relatively singular and often cannot truly reflect the service characteristics of the pipes.

[0003] Therefore, there is an urgent need to design a technical solution that can apply multiple loads during fatigue testing to truly reflect the service characteristics of the pipe. Summary of the Invention

[0004] The purpose of this invention is to provide a high-temperature internal pressure tensile torsion composite fatigue testing system to solve the problems existing in the prior art. It can apply multiple loads during fatigue testing, thereby truly reflecting the high-temperature service characteristics of the pipe.

[0005] To achieve the above objectives, the present invention provides the following solution: This invention provides a high-temperature internal pressure tensile torsion combined fatigue testing system, comprising: The furnace body contains a clamping assembly for holding both ends of the specimen. The loading device is connected to the clamp assembly and is capable of applying axial tensile load, axial compressive load and axial torsional load to the specimen; The circumferential internal pressure loading device is connected to the clamp assembly through a pipeline, and can introduce gas at a set pressure into the specimen through the clamp assembly to apply circumferential internal pressure to the specimen; A temperature control device, connected to the furnace body, is capable of heating the specimen to a set temperature; and The measuring component is capable of detecting the deformation data of the specimen in real time.

[0006] Preferably, there are two clamping assemblies, arranged symmetrically vertically. Each clamping assembly includes a pull rod, which is connected to the sample locking sleeve by a threaded pin. The sample locking sleeve is connected to the clamping body by a locking nut, and the clamping body is fixedly clamped to one end of the specimen. The pull rod of the upper clamping assembly passes through the top of the furnace body and is fixedly connected to the top of the support frame. The pull rod of the lower clamping assembly passes through the bottom of the furnace body and is connected to the axial loading device.

[0007] Preferably, the loading device includes a ball screw and a torsion motor. The nut on the ball screw is fixedly connected to the pull rod of the lower clamp assembly. A servo motor is driven to the bottom of the ball screw through a gear coupling. Both the servo motor and the gear coupling are housed in the servo motor gearbox. The output shaft of the torsion motor is fixedly connected to the top of the pull rod of the upper clamp assembly to apply an axial torsional load to the specimen.

[0008] Preferably, a displacement sensor is provided on the pull rod of the lower clamping assembly, and a pressure sensor is provided on the pull rod of the upper clamping assembly.

[0009] Preferably, the pull rod is provided with an internal pressure gas pipeline, and the internal pressure gas pipeline in the pull rod is sealed and connected to one end of the test piece. Specifically, the internal pressure gas pipeline of the pull rod and the test piece are sealed by a metal tapered thread, and the metal is made of a high-temperature resistant material. The circumferential internal pressure loading device includes an air compressor, an atmosphere control unit, an in-pipe gas filling unit, an in-pipe gas venting unit, an environmental chamber gas filling unit, and connecting pipelines. The air compressor is connected to the atmosphere control unit and the in-pipe gas filling unit through connecting pipelines. The air inlet of the in-pipe gas filling unit is connected to the internal pressure gas pipeline of the pull rod located at the upper part through connecting pipelines. The air outlet of the in-pipe gas venting unit is connected to the internal pressure gas pipeline of the pull rod located at the lower part through a return pipeline. The environmental chamber gas filling unit is connected to the interior of the furnace body.

[0010] Preferably, the atmosphere control unit includes a gas synthesis system connected to the air compressor via a connecting pipeline. The gas synthesis system is connected to an atmosphere unit gas source input group via multiple parallel gas source input pipelines. The gas source input pipelines are equipped with a gas source input electric proportional valve, a gas source input pressure gauge, and a gas source input flow meter. The output end of the gas synthesis system is connected to the in-pipe gas filling unit via a connecting pipeline.

[0011] Preferably, the in-pipe inflation unit includes an air compressor, the air outlet of which is connected to a compressed air inlet pipe. The compressed air inlet pipe is equipped with a manual compressed air inlet valve for the in-pipe inflation unit. The end of the compressed air inlet pipe is divided into three branches: the first branch is connected to the in-pipe inflation unit air pressure reducing valve on the gas output pipe of the in-pipe inflation unit; the second branch is connected to the in-pipe inflation unit pneumatic gas booster pump; and the third branch is connected to the atmosphere control unit, thereby achieving mixing with the atmosphere gas. The output end of the in-pipe inflation unit pneumatic gas booster pump is connected to a pipe fitting through the gas output pipe of the in-pipe inflation unit. The pipe fitting through the pipe fitting is used to connect to the air inlet pipe, which is connected to the internal pressure gas pipe of the upper pull rod. The internal pipe of the in-pipe deflation unit is connected to a return pipe, which is connected to the internal pressure gas pipe of the lower pull rod.

[0012] Preferably, the temperature control device includes a resistance wire disposed on the inner wall of the furnace body, the resistance wire being connected to a power source; the outer wall of the furnace body is covered with an insulation layer; a water-cooling jacket is provided between the outer wall of the furnace body and the insulation layer, and the water-cooling jacket is connected to a water chiller through a water-cooling circulation pipe.

[0013] Preferably, the measuring components include a radial extensometer, an axial extensometer, and a thermocouple disposed within the furnace body.

[0014] Preferably, it also includes a control component, which includes a deformation monitoring system, an air pressure control system, a temperature control system, and a central control system.

[0015] The present invention achieves the following technical effects compared to the prior art: This invention can apply circumferential internal pressure, axial tensile load, compressive load, torsional load and various composite loads to the specimen under a set high temperature environment, and monitor the deformation process and creep fatigue behavior of the specimen in real time through a measuring component, thereby truly reflecting the service characteristics of the pipe. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a high-temperature internal pressure tensile torsion composite fatigue testing system in one or more embodiments of the present invention; Figure 2 This is an enlarged schematic diagram of the circumferential internal pressure loading device of the high-temperature internal pressure tensile-torsional composite fatigue test system in one or more embodiments of the present invention. Figure 3 This is an enlarged schematic diagram of the axial loading device of the high-temperature internal pressure tensile torsion composite fatigue test system in one or more embodiments of the present invention.

[0018] In the diagram: 1-Servo motor, 2-Gear coupling, 3-Ball screw, 4-Displacement sensor, 5-Sample locking sleeve, 6-Specimen, 7-Radial extensometer, 8-Axial extensometer, 9-Thermocouple, 10-Resistance wire, 11-Internal pressure gas pipeline, 12-Furnace inner wall, 13-Furnace outer wall, 14-Support frame, 15-Pressure sensor, 16-Flow meter, 17-Gas pressure sensor, 18-Electric proportional valve, 19-Air compressor, 20-Inlet pipeline, 21-Servo electric drive, 22-Deformation monitoring system, 23-Air pressure control system, 24-Temperature control system, 25-Central control system, 26-Water chiller, 27-Servo motor gearbox, 28-Clamping body, 29-Locking nut, 30-Furnace body. 31-Pin, 32-Needle valve of environmental chamber inflation unit circuit, 33-220V electric switch valve of environmental chamber inflation unit, 34-24V electric switch valve of environmental chamber inflation unit, 35-Pressure regulator valve of environmental chamber inflation unit, 36-Pipeline through-plate connector, 37-Quick-release sealing structure, 38-Environmental chamber exhaust pipe, 39-Atmosphere unit gas source input group, 40-Gas source input electric proportional valve, 41-Gas source input pressure gauge, 42-Gas source input flow meter, 43-Gas source input pipe, 44-Gas synthesis system, 45-In-pipe inflation unit, 46-Atmosphere control unit, 47-Atmosphere inlet pipe, 48-Compressed air inlet pipe, 49-Gas output pipe of in-pipe inflation unit, 50-Circuit pipe, 51-In-pipe venting unit, 52- 53-Environmental chamber inflation unit, 54-Environmental chamber inlet pipe, 55-Torsion motor, 56-Water cooling jacket, 57-High temperature cooling water, 58-Environmental chamber inflation unit pressure reducer, 59-Environmental chamber inflation unit gas cylinder, 60-Environmental chamber inflation unit circuit 24V electric switch valve, 61-Environmental chamber inflation unit circuit 220V electric switch valve, 62-Environmental chamber inflation unit needle valve, 63-In-pipe venting unit 24V electric switch valve, 64-In-pipe venting unit 220V electric switch valve, 65-In-pipe venting unit needle valve, 66-In-pipe venting unit pressure gauge, 67-In-pipe venting unit temperature sensor, 68-In-pipe venting unit sampling bottle, 69-In-pipe venting unit internal piping, 70-In-pipe inflation unit high... Precision gas pressure reducing valve; 71-Pressure regulating filter of the first in-pipe filling unit; 72-Safety valve of the first in-pipe filling unit; 73-Pressure regulating filter of the second in-pipe filling unit; 74-Safety valve of the second in-pipe filling unit; 75-Pressure sensor of the in-pipe filling unit; 76-Pressure stabilizing tank of the in-pipe filling unit; 77-High pressure filter of the first in-pipe filling unit; 78-Electro-proportional valve of the in-pipe filling unit; 79-Air pressure reducing valve of the in-pipe filling unit; 80-Pneumatic control valve of the first in-pipe filling unit; 81-Solenoid valve of the first in-pipe filling unit; 82-Solenoid valve of the second in-pipe filling unit; 83-Pneumatic control valve of the second in-pipe filling unit; 84-Manual unloading valve of the in-pipe filling unit; 85-Unloading port of the in-pipe filling unit; 86-Pneumatic control valve of the third in-pipe filling unit.87-Solenoid valve of the third in-pipe filling unit; 88-Pneumatic gas booster pump of the in-pipe filling unit; 89-Safety valve of the third in-pipe filling unit; 90-Pressure gauge of the in-pipe filling unit; 91-High-pressure filter of the second in-pipe filling unit; 92-Manual medium inlet valve of the in-pipe filling unit; 93-Gas cylinder pressurization valve of the in-pipe filling unit; 94-Manual compressed air inlet valve of the in-pipe filling unit. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The purpose of this invention is to provide a high-temperature internal pressure tensile torsion composite fatigue testing system to solve the problems existing in the prior art. It can apply multiple loads during fatigue testing, thereby truly reflecting the high-temperature service characteristics of the pipe.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] This invention provides a high-temperature internal pressure tensile torsion combined fatigue testing system, with reference to... Figure 1 , Figure 2 , Figure 3 As shown, the system includes a furnace body 30, within which a clamping assembly is provided for holding both ends of a specimen 6. A loading device is connected to the clamping assembly and can apply axial tensile loads, axial compressive loads, and axial torsional loads to the specimen 6. A circumferential internal pressure loading device is connected to the clamping assembly via a pipeline and can introduce gas at a set pressure into the specimen 6 through the clamping assembly to apply circumferential internal pressure to the specimen 6. A temperature control device is connected inside the furnace body 30 and can heat the specimen 6 to a set temperature. A measuring component can detect the deformation data of the specimen 6 in real time. This invention can apply circumferential internal pressure, axial tensile loads, compressive loads, torsional loads, and various composite loads to the specimen 6 under a set high-temperature environment, and monitor the deformation process and creep fatigue behavior of the specimen 6 in real time through the measuring component, thereby truly reflecting the service characteristics of the pipe.

[0023] In one embodiment, there are two clamping assemblies, arranged symmetrically vertically. Each clamping assembly includes a pull rod, one end of which passes through the sample locking sleeve 5 and is fixedly connected to the sample locking sleeve 5 by a threaded pin 31. One end of the sample locking sleeve 5 is fixedly connected to the clamping body 28 by a locking nut 29. The clamping body 28 is fixedly clamped to one end of the specimen 6. The fixed connection between the pull rod and one end of the specimen 6 is achieved through the sample locking sleeve 5 and the clamping body 28. The pull rod of the upper clamping assembly passes through the top of the furnace body and is fixedly connected to the top of the support frame 14. The support frame 14 is fixed to the ground, and the top of the support frame 14 is located above the furnace body. The pull rod of the lower clamping assembly passes through the bottom of the furnace body and is connected to the axial loading device. The loading device includes a ball screw 3 and a torsion motor 54. The nut on the ball screw 3 is fixedly connected to the pull rod of the lower clamping assembly. The bottom of the ball screw 3 is connected to a servo motor 1 via a gear coupling 2. Both the servo motor 1 and the gear coupling 2 are housed within the servo motor gearbox 27. The output shaft of the torsion motor 54 is fixedly connected to the top of the pull rod of the upper clamping assembly to apply an axial torsional load to the specimen. A displacement sensor 4 is installed on the pull rod of the lower clamping assembly, and a pressure sensor 15 is installed on the pull rod of the upper clamping assembly.

[0024] The ball screw 3 of the loading device applies tensile load to the specimen 6, while the torsion motor 54 applies torsional load to the specimen 6, simulating axial stress in the actual working environment. To ensure loading accuracy and stability under high-temperature conditions, a servo motor 1 and ball screw 3 transmission system are used. The servo motor 1 uses a Siemens S120 series servo system, which has high load adaptability and precise speed control characteristics, and can provide stable power output under high-temperature conditions. The ball screw 3 uses a BNS series ball screw manufactured by TBI Motion, which has a low coefficient of friction and high transmission efficiency, and can maintain high load accuracy and low temperature rise during long-term use. The servo motor 1 is connected to the ball screw 3 through a gear coupling 2, and then the axial load is applied to the specimen through the specimen locking sleeve 5 connected by a tie rod. The tie rod and the specimen locking sleeve 5 are connected by a threaded pin 31, and the locking sleeve and the clamp body 28 are connected by the preload of the locking nut 29, forming the transmission path of axial and torsional loads. The gear coupling 2 is made of high-temperature heat-resistant material, which can withstand the thermal expansion and contraction effect generated when working at high temperature, ensuring stable connection.

[0025] The tie rod is equipped with an internal pressure gas pipe 11, and the internal pressure gas pipe 11 inside the tie rod is sealed and connected to one end of the specimen 6; the circumferential internal pressure loading device includes an air compressor 19, an atmosphere control unit 46, an in-pipe gas filling unit 45, an in-pipe gas venting unit 51, and an environmental chamber gas filling unit 52. The atmosphere control unit 46 includes an atmosphere unit gas source input group 39 and a gas synthesis system 44. Multiple first air inlets of the gas synthesis system 44 are connected to the atmosphere unit gas source input group 39 via multiple gas source input pipes 43. Each gas source input pipe 43 is equipped with a gas source input electric proportional valve 40, a gas source input pressure gauge 41, and a gas source input flow meter 42. The atmosphere unit gas source input group 39 has multiple air inlets, enabling the input of oxygen, nitrogen, and other gases required for the test bench into the gas synthesis system 44 via different gas source input pipes 43. The outlet of the gas synthesis system 44 is connected to an in-pipe filling unit 45 via an atmosphere inlet pipe 47, thus forming the mixed gas to meet the required test atmosphere and achieve atmosphere control. The mixed gas is then transported to the test specimen via the in-pipe filling unit 45, achieving the purpose of applying internal pressure to the test specimen using a specific mixed gas. This facilitates experiments on the effects of introducing gases of different properties into the test specimen on its performance.

[0026] The in-pipe inflation unit 45 includes an air compressor 19. The outlet of the air compressor 19 is connected to a compressed air inlet pipe 48. The compressed air inlet pipe 48 is equipped with a manual compressed air inlet valve 94 for the in-pipe inflation unit. The end of the compressed air inlet pipe 48 is divided into three branches. The first branch is connected to the in-pipe inflation unit air pressure reducing valve 79 on the gas output pipe 49 of the in-pipe inflation unit, and the first branch is equipped with a high-precision gas pressure reducing valve 70 and an electric proportional valve 78 for the in-pipe inflation unit. The second branch is connected to a pneumatic gas booster pump 88 for the in-pipe inflation unit. The pneumatic gas booster pump 88 for the in-pipe inflation unit adopts the in-pipe inflation unit DLE. 75-1-2 Pneumatic gas booster pump; the second branch is equipped with a first in-pipe filling unit pressure regulating filter 71 and a first in-pipe filling unit safety valve 72; the third branch is connected to the electromagnetic control valve on the atmosphere inlet pipe 47 through the second in-pipe filling unit pressure regulating filter 73, thereby realizing the connection between the atmosphere inlet pipe 47 and the in-pipe filling unit 45, and thus realizing the initial mixing of high pressure gas and atmosphere gas. The electromagnetic control valve includes a third in-pipe filling unit solenoid valve 87 and a third in-pipe filling unit pneumatic control valve 86; the atmosphere inlet pipe 47 is sequentially equipped with an in-pipe filling unit pressure gauge 90, a second in-pipe filling unit high pressure filter 91, an in-pipe filling unit manual medium inlet valve 92, and an in-pipe filling unit gas cylinder pressurization valve 93.

[0027] The output end of the pneumatic gas booster pump 88 of the in-pipe inflation unit is connected to a pipe through-plate connector 36 via the gas output pipe 49 of the in-pipe inflation unit. The pipe through-plate connector 36 is used to connect to the air inlet pipe 20. The air inlet pipe 20 is equipped with a flow meter 16 and a gas pressure sensor 17. The end of the air inlet pipe 20 is connected to the top opening of the internal pressure gas pipe located at the top. The first end of the air inlet pipe 20 is connected to the gas output pipe 49 of the in-pipe inflation unit. The gas output pipe 49 of the in-pipe inflation unit is equipped with an in-pipe inflation unit pressure sensor 75, an in-pipe inflation unit pressure stabilizing tank 76, a first in-pipe inflation unit high-pressure filter 77, an in-pipe inflation unit air pressure reducing valve 79, a first in-pipe inflation unit air control valve 80, a first in-pipe inflation unit solenoid valve 81, a second in-pipe inflation unit solenoid valve 82, a second in-pipe inflation unit air control valve 83, an in-pipe inflation unit manual unloading valve 84, an in-pipe inflation unit unloading port 85, and a third in-pipe inflation unit safety valve 89.

[0028] The internal venting unit 51 includes an internal venting unit pipe 69 connected to the loop pipe 50. The internal venting unit pipe 69 is equipped with, in sequence, an internal venting unit 24V electric switch valve 63, an internal venting unit 220V electric switch valve 64, an internal venting unit needle valve 65, an internal venting unit pressure gauge 66, an internal venting unit temperature sensor 67, and an internal venting unit sampling bottle 68. The end of the loop pipe 50 away from the internal venting unit pipe 69 is connected to the bottom opening of the internal pressure gas pipe located at the bottom.

[0029] The environmental chamber filling unit 52 is used to fill the furnace with gas to create the gas environment required for the experiment. Its structure includes an environmental chamber inlet pipe 53 and an environmental chamber exhaust pipe 38, both connected to the furnace body. The end of the environmental chamber inlet pipe 53 is connected to an environmental chamber filling unit gas cylinder 59 via an environmental chamber filling unit pressure reducer 58. The environmental chamber inlet pipe 53 is sequentially equipped with a quick-release sealing structure 37, an environmental chamber filling unit needle valve 62, an environmental chamber filling unit 220V electric switch valve 33, an environmental chamber filling unit 24V electric switch valve 34, and an environmental chamber filling unit pressure regulating valve 35. The environmental chamber exhaust pipe 38 is sequentially equipped with an environmental chamber filling unit circuit 24V electric switch valve 60, an environmental chamber filling unit circuit 220V electric switch valve 61, and an environmental chamber filling unit circuit needle valve 32.

[0030] The principle of the circumferential inward pressure loading device is as follows: In-pipe inflation unit: First, compressed air from air compressor 19 passes through manual compressed air inlet valve 94 to in-pipe inflation unit 45. The first path passes through high-precision gas pressure reducing valve 70 and electric proportional valve 78 to the gas output pipe 49 of in-pipe inflation unit, achieving pre-stage feedback regulation of the gas output pipe 49. The second path of high-pressure gas from air compressor 19 passes through pressure regulating filter 71 to enter pneumatic gas booster pump 88, enabling the entry of main high-pressure gas. For safety, this pipeline is equipped with a safety valve 72. The third path of high-pressure gas... The gas enters the atmosphere system through the electromagnetic control valve of the second in-pipe filling unit pressure regulating filter 73 and the second in-pipe filling unit safety valve 74, achieving initial mixing of high-pressure gas and atmosphere gas. The mixed gas from the atmosphere control unit passes through the in-pipe filling unit cylinder pressurization valve 93, the in-pipe filling unit manual medium inlet valve 92, and the second in-pipe filling unit high-pressure filter 91, and finally reaches the third in-pipe filling unit pneumatic control valve 86, where it mixes with the high-pressure gas from the third path mentioned above before entering the in-pipe filling unit pneumatic gas booster pump 88. This ensures that the gas in the atmosphere system smoothly enters the in-pipe filling unit pneumatic gas booster pump 88. A pressure gauge 90 is installed on this pipeline to achieve real-time pressure monitoring. Finally, the high-pressure gas, after being pressurized and mixed, is output through the pneumatic gas booster pump 88 of the in-pipe inflation unit, passing through the high-pressure filter 77 of the first in-pipe inflation unit, the air pressure reducing valve 79 of the in-pipe inflation unit, the air control valve 83 of the second in-pipe inflation unit, and the manual unloading valve 84 of the in-pipe inflation unit, and finally output to the main test equipment. The pipeline is equipped with multiple safety settings, including the pressure sensor 75 of the in-pipe inflation unit, the pressure stabilizing tank 76 of the in-pipe inflation unit, the safety valve 89 of the third in-pipe inflation unit, and the unloading port 85 of the in-pipe inflation unit. In order to achieve pressure feedback regulation, the gas output pipe 49 of the in-pipe inflation unit is equipped with the air control valve 80 of the first in-pipe inflation unit and the solenoid valve 81 of the first in-pipe inflation unit, and is connected to the pneumatic gas booster pump 88 of the in-pipe inflation unit through a pipeline.

[0031] In-pipe venting unit: The experimental gas output from the main device enters the in-pipe venting unit 51, passes through the in-pipe venting unit 24V electric switch valve 63, the in-pipe venting unit 220V electric switch valve 64, the in-pipe venting unit needle valve 65, and finally reaches the exhaust port. The pipeline is equipped with devices such as the in-pipe venting unit pressure gauge 66, the in-pipe venting unit temperature sensor 67, and the in-pipe venting unit sampling bottle 68.

[0032] Environmental chamber filling unit: The gas in the environmental chamber filling unit 52 is stored in the environmental chamber filling unit gas cylinder 59. The gas is output from the environmental chamber filling unit gas cylinder 59 and passes through the environmental chamber filling unit pressure reducer 58, the environmental chamber filling unit pressure stabilizing valve 35, the environmental chamber filling unit 24V electric switch valve 34, the environmental chamber filling unit 220V electric switch valve 33, and the environmental chamber filling unit needle valve 62, reaching the quick-release sealing structure 37, and finally being sent into the main unit environmental chamber, i.e., the furnace body; then the gas after the experiment in the main unit environmental chamber passes through the environmental chamber exhaust pipe 38, through the environmental chamber filling unit circuit 24V electric switch valve 60, the environmental chamber filling unit circuit 220V electric switch valve 61, and the environmental chamber filling unit circuit needle valve 32, and is finally discharged.

[0033] In one embodiment, a control component is also included, comprising a servo electric drive 21, a deformation monitoring system 22, a pneumatic control system 23, a temperature control system 24, and a central control system 25.

[0034] The circumferential internal pressure loading device applies air pressure to the inside of the tubular specimen to simulate the creep fatigue behavior of the material under gas pressure. Specifically, the air compressor 19 uses an Atlas Copco GA7VSD+ air compressor, which supports a continuous and stable supply of high-pressure gas. The GA7VSD+ compressor has a maximum output pressure of 15MPa, capable of providing the required high-pressure gas. The in-tube gas filling unit uses a WIKA intelligent gas controller, which can provide precise flow pressure control within a pressure range of 0.5MPa to 15MPa, with a control accuracy of ±0.1%. The flow meter 16 and the gas pressure sensor 17 communicate with the control system via a pressure transmitter through digital signals, providing real-time feedback of pressure and flow data during the test. After calculation, the controller uses an electric proportional valve 18 to precisely control the gas flow and pressure.

[0035] The atmosphere control unit 46 is primarily responsible for controlling the gas composition of the internal pressure system, providing a precise experimental atmosphere for the sample, including parameters such as gas type, concentration, flow rate, and pressure. The atmosphere control system is designed to simulate the mechanical behavior of materials under different corrosive gas environments, providing realistic experimental data for material performance evaluation. The atmosphere control system mainly includes a gas source, a gas mixer, a gas source pressure gauge, a gas source flow meter 16, an electric proportional valve 18, and a sealed piping system. The system can provide a mixed environment of gases such as helium, methane, carbon monoxide, carbon dioxide, and oxygen to simulate corrosive atmospheres in actual working conditions. The gas mixer uses a gas synthesis system 44 from Messer Group. This system can precisely adjust gas concentration and provides synchronous mixing functionality, supporting precise adjustment of individual gas concentrations. Each gas input channel of the atmosphere control unit 46 has an individual pressure gauge, flow meter 16, and electric proportional valve 18, which are connected to the gas pressure control system via digital signals to achieve precise control of the internal pressure atmosphere.

[0036] The internal gas filling unit 45 is primarily responsible for regulating and controlling the internal pressure system. All components are interconnected via high-pressure stainless steel pipelines and digital signal lines. The gas pressure control system adjusts in real-time based on feedback data from the pressure and flow sensors of the central controller and experimental parameters, achieving closed-loop pressure regulation and monitoring. Experimental parameters mainly include target pressure, oscillation frequency, oscillation amplitude, and loading mode. The internal gas filling unit 45 primarily achieves precise control of the high-pressure gas within the tube. In creep or steady-state loading experiments, the internal gas filling unit 45 maintains a constant internal pressure, ensuring the long-term stress state of the sample under stable stress conditions. During fatigue experiments, the internal gas filling unit 45 can achieve periodic pressure oscillation according to set parameters, allowing the gas pressure within the tube to fluctuate regularly within the target range. This oscillation function supports various loading waveforms, including sine waves, square waves, triangular waves, and user-defined waveforms. The oscillation frequency range is 0.01Hz to 10Hz, and the pressure fluctuation amplitude can be flexibly set within the range of 0.5MPa to 15MPa. The system employs closed-loop adaptive control during the oscillation loading process, which can correct the deviation between the output and the target curve in real time, keeping the accuracy of pressure oscillation within ±0.5%, thereby effectively simulating the service environment of materials under complex alternating stress.

[0037] All gas flow piping in the circumferential internal pressure loading device utilizes a 316L stainless steel piping system from Swagelok. The gas pipes are connected to various equipment components via high-pressure quick-connect couplings to ensure airtightness and prevent gas leakage. This piping system boasts extremely high resistance to high temperatures and corrosion, enabling long-term stable operation under high pressure environments. All connection points employ metal-sealed technology to ensure no leakage even at a gas pressure of 15 MPa. The sealing system is also equipped with a helium mass spectrometer for real-time monitoring of the system's tightness, ensuring complete gas sealing.

[0038] To achieve the synergistic effect of dual-axis loading, this invention employs synchronous control technology, enabling precise and synchronized application of axial loading and circumferential internal pressure. Specifically, both the axial loading device and the internal pressure loading device are managed uniformly by a central control system, ensuring data synchronization and control accuracy during the loading process. The control system is connected to the driver of servo motor 1 and the pneumatic control system via an RS-232 serial port interface, adjusting the motor speed and the output pressure of the pneumatic control system in real time.

[0039] The temperature control device includes a resistance wire 10 installed on the inner wall 12 of the furnace body. The resistance wire 10 is connected to a power source and can heat the furnace body. The outer wall 13 of the furnace body is covered with an insulation layer, which can keep the furnace body at a set temperature. In addition to heating the furnace body, this embodiment can also cool the furnace body. When cooling is required, the resistance wire 10 is turned off. A water-cooling jacket 55 is provided between the outer wall of the furnace body and the insulation layer. The water-cooling jacket 55 is connected to a water chiller 2 through a water-cooling circulation pipe. 6. Cooling water is supplied from the outlet of the water chiller 26 through the water supply pipe of the water-cooled circulation pipe into the water-cooled jacket 55 on the outer wall of the furnace body. It flows along the channels of the water-cooled jacket 55 and absorbs the heat dissipated from the furnace body, thus indirectly cooling the furnace body. The high-temperature cooling water 56, after its temperature rises, returns to the water chiller 26 through the return pipe of the water-cooled circulation pipe. After heat exchange and cooling within the water chiller 26, it becomes low-temperature cooling water 57, which is then output from the outlet again. This cycle repeats, forming a closed loop to achieve continuous and stable cooling of the furnace body. The furnace body design takes into account the requirements of high-temperature stability, atmosphere control, and deformation monitoring; therefore, it features high temperature resistance, uniform heating effect, and good sealing. The high-temperature furnace body adopts a multi-layer insulation design, with an inner layer of high-temperature resistant ceramic fiber and an outer layer of heat-resistant steel to ensure the stability of the furnace temperature and insulation. The inner wall material of the furnace body is a (molybdenum) alloy, which can operate stably for a long time at 1000℃, is not prone to oxidation, and has high corrosion resistance. The temperature control system is crucial for ensuring that samples are heated to a stable high temperature and maintained at a uniform temperature. Employing a PID control algorithm, it can precisely control the furnace temperature under high-temperature conditions. The heating element inside the furnace is a heating resistance wire 10, which possesses excellent high-temperature stability and good resistance characteristics, providing continuous and stable heating at 1000℃. A K-type thermocouple is used as the temperature sensor. The temperature sensor is connected to the temperature control system via an RS-485 communication interface to ensure accurate temperature control. Furnace airtightness is an important design parameter for ensuring the stability of the experimental atmosphere. The furnace body employs metal sealing technology and a helium mass spectrometry detection system to effectively prevent gas leakage. Furthermore, to prevent the effects of high temperatures on the equipment, a water-cooling channel is designed between the furnace shells, with an external water chiller 26 continuously supplying cooling water to achieve cooling.

[0040] The deformation monitoring system includes a radial extensometer 7, an axial extensometer 8, and a thermocouple 9, all housed within the furnace. The system is primarily responsible for acquiring deformation test data, mainly used for real-time monitoring of the specimen's deformation under biaxial loading conditions, including axial and radial deformation. Each device involved in this invention possesses high precision, high stability, and high-temperature adaptability, enabling it to operate synchronously during the test and acquire sample deformation data in real time.

[0041] The axial extensometer 8 is mainly used to measure the elongation of a sample under axial loading. A Vishayr extensometer manufactured by Micro-Measurements is selected. The axial extensometer 8 is installed and calibrated using a three-dimensional laser alignment instrument. The installation method is direct bonding, whereby the extensometer is glued to the gauge length of the sample using high-temperature adhesive.

[0042] The radial extensometer 7 is used to monitor the radial expansion of the sample under circumferential inward pressure. It employs a Vishay linear displacement sensor manufactured by Micro-Measurements. The radial extensometer 7 is connected to the specimen surface via an adjustable bracket, which allows for real-time adjustment of the extensometer's installation position during the test. In one embodiment, the sensor is fixed to the specimen surface using a high-temperature adhesive to ensure its stability during long-term creep testing. All deformation data is transmitted to the central control system 25 via a data acquisition system for analysis and processing.

[0043] The control component is responsible for acquiring various parameter data in real time during the experiment, and efficiently processing and analyzing the data to provide comprehensive and accurate experimental results. This control component can process data from multiple systems, including deformation monitoring, temperature control, and air pressure control, and uses advanced analysis algorithms to perform in-depth analysis, providing detailed reports on material creep behavior.

[0044] Data acquisition and control are primarily achieved through the central control system 25, which mainly consists of a central controller and a data acquisition card. This system employs a high-performance real-time computing platform, supporting synchronous acquisition and processing of multi-channel data. Based on the test parameters from the host computer, it sends different commands to the sub-controllers, enabling the system to dynamically adjust axial loading force, internal pressure loading force, and temperature environmental parameters according to sensor and test parameters under different loading modes, such as static loading, creep loading, fatigue loading, and burst loading, maintaining them within the set precise value range. The central control system 25 connects to the servo motor driver, deformation monitoring system, air pressure control system, and temperature controller via the data acquisition card, adjusting parameters such as motor speed and air pressure system pressure and temperature in real time, achieving coordinated operation of multiple systems. The central controller communicates with the sub-module controllers via an RS232 serial port interface for parameter reading and task command issuance, and communicates with the host computer system via an RJ45 interface for test parameter input and data processing.

[0045] This invention also includes an automatic compensation system, a safety mechanism integrated into the central controller, to ensure the safe and stable operation of the experimental system during the experiment. Through high-precision feedback control and a safety interlock mechanism, this system ensures that in the event of any abnormality during the experiment, it can promptly adjust or stop operation to prevent equipment damage or experimental failure.

[0046] During the test, the air pressure inside specimen 6 may fluctuate due to temperature changes, material expansion, or other reasons, leading to unstable test conditions. To ensure that the air pressure remains within the set range, an automatic pressure compensation mechanism is designed. This mechanism primarily uses pressure sensor 15 to monitor pressure changes within the specimen in real time. When the pressure exceeds the set range, the central control system 25 adjusts the gas flow or pressure via an electric regulating valve to quickly restore the pressure inside specimen 6 to the set value. The automatic pressure compensation mechanism employs a PID control algorithm for dynamic pressure compensation, ensuring precise pressure control during the test. The algorithm is corrected based on real-time data from pressure sensor 15 and sends adjustment commands through the computer control system to control the electric valve to respond quickly. The compensation system can complete pressure adjustment within 1 second, ensuring that the pressure change is less than ±0.5%.

[0047] Furthermore, this invention incorporates an emergency protection mechanism to ensure that the equipment automatically shuts down and cuts off hazardous sources in any abnormal situation. When the temperature exceeds the limit, the system automatically cuts off the heating source and stops the heating process. During testing, if a gas leak is detected, the system will immediately trigger an alarm and shut off the gas supply. Leak detection utilizes a helium mass spectrometer, which can quickly detect even the smallest gas leaks. The system is equipped with an emergency stop button; when the operator detects an anomaly, they can manually press this button, and the system will immediately stop all operations, disconnecting the power and gas supply to ensure operational safety.

[0048] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A high-temperature internal pressure tensile-torsional composite fatigue testing system, characterized in that: include: The furnace body contains a clamping assembly for holding both ends of the specimen. The loading device is connected to the clamp assembly and is capable of applying axial tensile load, axial compressive load and axial torsional load to the specimen; The circumferential internal pressure loading device is connected to the clamp assembly through a pipeline, and can introduce gas at a set pressure into the specimen through the clamp assembly to apply circumferential internal pressure to the specimen; A temperature control device, connected to the furnace body, is capable of heating the specimen to a set temperature; as well as The measuring component is capable of detecting the deformation data of the specimen in real time.

2. The high-temperature internal pressure tensile-torsional composite fatigue testing system according to claim 1, characterized in that: The clamping assembly consists of two components, arranged symmetrically vertically. Each clamping assembly includes a pull rod, which is connected to the sample locking sleeve by a threaded pin. The sample locking sleeve is connected to the clamping body by a locking nut, and the clamping body is fixedly clamped to one end of the specimen. The pull rod of the upper clamping assembly passes through the top of the furnace body and is fixedly connected to the top of the support frame. The pull rod of the lower clamping assembly passes through the bottom of the furnace body and is connected to the axial loading device.

3. The high-temperature internal pressure tensile-torsional composite fatigue testing system according to claim 2, characterized in that: The loading device includes a ball screw and a torsion motor. The nut on the ball screw is fixedly connected to the pull rod of the clamp assembly located at the lower part. The bottom of the ball screw is connected to a servo motor via a gear coupling. Both the servo motor and the gear coupling are housed in the servo motor gearbox. The output shaft of the torsion motor is fixedly connected to the top of the pull rod of the clamp assembly located at the upper part to apply an axial torsional load to the specimen.

4. The high-temperature internal pressure tensile-torsional composite fatigue testing system according to claim 2, characterized in that: A displacement sensor is provided on the pull rod of the lower clamping assembly, and a pressure sensor is provided on the pull rod of the upper clamping assembly.

5. The high-temperature internal pressure tensile-torsional composite fatigue testing system according to claim 2, characterized in that: The pull rod is equipped with an internal pressure gas pipeline, and the internal pressure gas pipeline inside the pull rod is sealed and connected to one end of the specimen; the circumferential internal pressure loading device includes an air compressor, an atmosphere control unit, an in-pipe gas filling unit, an in-pipe gas venting unit, an environmental chamber gas filling unit, and connecting pipelines; the air compressor is connected to the atmosphere control unit and the in-pipe gas filling unit through the connecting pipelines, the air inlet of the in-pipe gas filling unit is connected to the internal pressure gas pipeline of the upper pull rod through the connecting pipelines, and the air outlet of the in-pipe gas venting unit is connected to the internal pressure gas pipeline of the lower pull rod through the return pipelines; the environmental chamber gas filling unit is connected to the interior of the furnace body.

6. The high-temperature internal pressure tensile-torsional composite fatigue testing system according to claim 5, characterized in that: The atmosphere control unit includes a gas synthesis system, which is connected to an atmosphere unit gas source input group through multiple parallel gas source input pipes. The gas source input pipes are equipped with a gas source input electric proportional valve, a gas source input pressure gauge, and a gas source input flow meter. The output end of the gas synthesis system is connected to the gas filling unit inside the pipe through a connecting pipe.

7. The high-temperature internal pressure tensile-torsional composite fatigue testing system according to claim 5, characterized in that: The in-pipe inflation unit includes an air compressor, the air compressor outlet of which is connected to a compressed air inlet pipe. The compressed air inlet pipe is equipped with a manual compressed air inlet valve for the in-pipe inflation unit. The end of the compressed air inlet pipe is divided into three branches: the first branch connects to the in-pipe inflation unit air pressure reducing valve on the gas output pipe of the in-pipe inflation unit; the second branch connects to the in-pipe inflation unit pneumatic gas booster pump; and the third branch connects to the atmosphere control unit, thereby achieving mixing with the atmosphere gas. The output end of the in-pipe inflation unit pneumatic gas booster pump is connected to a pipe through-plate connector via the in-pipe inflation unit gas output pipe. The pipe through-plate connector is used to connect to the air inlet pipe, which connects to the internal pressure gas pipe of the upper pull rod. The in-pipe deflation unit has an internal pipe connected to a return pipe, which connects to the internal pressure gas pipe of the lower pull rod.

8. The high-temperature internal pressure tensile-torsional composite fatigue testing system according to claim 1, characterized in that: The temperature control device includes a resistance wire installed on the inner wall of the furnace body, which is connected to a power source; the outer wall of the furnace body is covered with an insulation layer; a water-cooling jacket is provided between the outer wall of the furnace body and the insulation layer, and the water-cooling jacket is connected to a water chiller through a water-cooling circulation pipe.

9. The high-temperature internal pressure tensile-torsional combined fatigue testing system according to claim 1, characterized in that: The measuring components include a radial extensometer, an axial extensometer, and a thermocouple disposed within the furnace body.

10. The high-temperature internal pressure tensile-torsional composite fatigue testing system according to claim 1, characterized in that: It also includes control components, which include a deformation monitoring system, an air pressure control system, a temperature control system, and a central control system.

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