A high-speed rotating bending fatigue stress and temperature synchronous test bench and measurement method

Abstract

A high-speed rotating bending fatigue stress and temperature synchronization test bench and measurement method are disclosed. The test bench primarily comprises a support base, on which a hollow shaft is rotatably mounted. A specimen is fixed at one end of the hollow shaft, and a strain gauge and thermocouple are mounted on the specimen. The strain gauge's stress signal leads and the thermocouple's thermocouple signal leads pass through the hollow shaft and are connected to corresponding sleeve-type electrodes. The sleeve-type electrodes are fixed at the other end of the hollow shaft. The other end of the sleeve-type electrodes passes through sealed bearings and liquid metal of multiple sets of liquid metal conductive devices. The multiple sets of liquid metal conductive devices are electrically connected to a dynamic signal acquisition instrument 13, which is electrically connected to a computer. The high-speed rotating bending fatigue stress and temperature synchronization test bench and measurement method provided by the present invention can accurately measure the real-time changes in stress and fatigue-induced temperature rise experienced by high-speed rotating fatigue specimens.

Description

Technical Field

[0001] The present invention relates to the technical field of rotary bending fatigue testing, and in particular to a high-speed rotary bending fatigue stress and fatigue temperature synchronous testing platform and measurement method. Background Art

[0002] High-speed rotating bending fatigue testing is primarily used to measure the fatigue life of smooth material specimens under cyclic alternating bending loads. A plot of the fatigue limit stress σ (nominal stress) versus the fatigue life (number of cycles) N is called a stress-life curve, or SN curve. The number of cycles a material undergoes before fatigue fracture is the fatigue life under that load. Fatigue life typically consists of four stages: crack nucleation, microcrack propagation, macrocrack growth, and final fracture. Currently, fatigue fracture initiation, fracture properties, fracture mode, fracture mechanism, stress state during the fracture process, and crack growth rate are primarily analyzed using fatigue fracture images. While fracture morphology provides some information about the stress state during the fracture process, it can deviate significantly from the actual alternating stress state experienced during the fatigue process. Fatigue fracture is a low-stress, plastic strain-accumulating damage. As the material undergoes an elastic-to-plastic transition during fatigue, the stress state inevitably changes in real time.

[0003] Furthermore, from a material perspective, the low-stress plastic strain energy generated during fatigue is converted into heat, causing a local temperature rise in the material. Therefore, fatigue temperature evolution, as a concomitant phenomenon in metal fatigue, is closely related to fatigue life. Using temperature change as a fatigue performance evaluation indicator allows for rapid prediction of material fatigue limits and fatigue life. In recent years, although non-contact temperature measurement methods such as infrared thermal imaging have been used to measure the temperature field of fatigue specimens under different loads, infrared thermal imaging is significantly affected by factors such as the specimen material, surface finish, fatigue amplitude, and environment. This is especially true in high-speed rotary bending fatigue tests, where the specimen rotates at a high speed, has a large radial amplitude, and dissipates heat rapidly, resulting in significant errors in temperature measurement results. To improve fatigue life prediction accuracy and reduce measurement uncertainty, fatigue damage assessment coupled with multiple characteristic quantities, based on real fatigue alternating stress and fatigue temperature rise, has become an important method for fatigue damage test analysis.

[0004] Current signal transmission in continuously rotating mechanisms often uses conductive slip rings, also known as collector rings, rotary joints, current collectors, adapters, and commutators. These rings primarily consist of a stator and rotor. Brushes are fixed to the stator or rotor, making electrical contact with corresponding conductive rings on the stator or rotor for power and data transmission. At low speeds (<1000 rpm), conductive slip rings can be used for partial signal measurement. However, at high rotor speeds, rapid friction between the brushes and the conductive rings causes wear marks and abrasive particles to accumulate on the surface. Frictional heat also raises the temperature. These wear marks and abrasive particles cause changes in contact resistance, generating significant interference signals. This temperature increase can cause signal drift and distortion. Furthermore, the small size of bending fatigue specimens limits the use of conductive slip rings. Achieving interference-free, drift-free, and distortion-free online, real-time transmission of contact measurement signals from high-speed rotating mechanisms has become a major challenge. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-speed rotating bending fatigue stress and temperature synchronous test bench and measurement method. While obtaining the commonly used SN curve, the real-time change process of the stress and temperature rise caused by fatigue of the high-speed rotating fatigue specimen can be accurately measured. The measurement signal is the real fatigue alternating stress and fatigue temperature. The signal is free of interference and drift and does not require processing.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A high-speed rotating bending fatigue stress and temperature synchronization test bench includes a support base on which a hollow shaft is rotatably mounted, and the hollow shaft is driven to rotate at high speed by a driving device; a specimen is fixed at one end of the hollow shaft, and a strain gauge and a thermocouple are mounted on the specimen; the stress signal lead of the strain gauge and the thermocouple signal lead of the thermocouple pass through the hollow shaft and are correspondingly connected to a sleeve combination electrode, and the sleeve combination electrode is fixed to the other end of the hollow shaft;

[0008] Each group of electrodes of the sleeve combined electrode passes through a group of liquid metal conductive devices, and the liquid metal conductive devices are electrically connected to a dynamic signal acquisition instrument and a computer in sequence.

[0009] The sheath combination electrode includes a conductive stress sheath negative electrode, a stress sheath positive electrode, a thermocouple sheath negative electrode, and a thermocouple sheath positive electrode. The stress sheath negative electrode, the stress sheath positive electrode, the thermocouple sheath negative electrode, and the thermocouple sheath positive electrode are sheathed together and fixed with insulating glue to maintain mutual insulation.

[0010] The four electrodes of the sleeve combination electrode are gradually lengthened from the outside to the inside and extend out gradually to the left and right.

[0011] The liquid metal conductive device includes a liquid metal device wall, which is connected to the liquid metal device head to form a sealed container. Sealed bearings for the sleeve combination electrode to pass through the sealed container are installed on the left and right sides of the sealed container. Liquid metal is provided in the sealed container, and a signal wire connector is installed on one side of the sealed container.

[0012] The liquid metal is a gallium-indium-based alloy that is liquid at room temperature, thereby ensuring that the rotating sleeve combined electrode immersed therein and the signal wire connector achieve non-contact signal communication at room temperature.

[0013] The hollow shaft and the sample, as well as the hollow shaft and the sleeve-combined electrode are fixed via spring chucks, and corresponding wire holes are provided on the spring chucks.

[0014] A high-speed rotating bending fatigue stress and temperature synchronization test bench, wherein the high-speed rotating fatigue alternating stress of the sample is collected in real time by a strain gauge, and the fatigue temperature is collected by a thermocouple; the collected signal is coaxially output through a lead wire and connected to a sleeve combination electrode; the sleeve combination electrode is fixed to a hollow shaft by a spring clamp and rotates synchronously with the sample; the four electrodes of the sleeve combination electrode respectively pass through and are immersed in four independent liquid metal conductive devices; when rotating at high speed, the sleeve combination electrode transmits the signal to a dynamic signal acquisition instrument through the liquid metal in the liquid metal conductive device, and the collected data is recorded in real time by a computer via a data line.

[0015] A method for synchronously measuring high-speed rotating bending fatigue stress and temperature comprises the following steps:

[0016] Step 1: First, pass the strain gauge, stress signal lead, thermocouple, and thermocouple signal lead through the spring collet and hollow shaft. Then, connect the positive and negative poles of the stress signal lead to the positive and negative poles of the stress sheath of the sheath combination electrode. Connect the positive and negative poles of the thermocouple signal lead to the positive and negative poles of the thermocouple sheath of the sheath combination electrode. Then, attach the strain gauge and thermocouple to the specimen and secure one end of the specimen to the hollow shaft with the spring collet.

[0017] Step 2: Fix the mounting connector to the other end of the specimen and attach the weight plate according to the fatigue load;

[0018] Step 3: Insert the sleeve combination electrode into the C-shaped adapter clamp, and then use the spring chuck to fix the sleeve combination electrode together at one end of the hollow shaft;

[0019] Step 4: After the four electrodes extending from the sleeve combination electrode pass through four independent liquid metal conductive devices, liquid metal is injected into the liquid metal conductive devices so that the four electrodes extending from the sleeve combination electrode are immersed in and pass through the liquid metal of the corresponding liquid metal conductive devices;

[0020] Step 5: Use multiple sets of signal wires to connect the liquid metal conductive device and the dynamic signal acquisition instrument respectively, and use data cables to connect the computer and the dynamic signal acquisition instrument. Open the stress and temperature acquisition control software, adjust the parameters to reset the bridge balance, and prepare to collect fatigue alternating stress and fatigue temperature data.

[0021] Step 6: Start the high-speed motor, the belt drives the transmission wheel and the hollow shaft to rotate, and the counter records the number of fatigue cycles;

[0022] Step 7: After the sample breaks, stop the high-speed motor, read the fatigue life times recorded by the control box, and obtain the SN data;

[0023] Step 8: Stop the stress and temperature acquisition control software and store the fatigue fracture full life stress change and fatigue temperature curve;

[0024] Step 9: Repeat the above steps to complete the SN curve and real-time stress and temperature change curve.

[0025] The present invention provides a high-speed rotating bending fatigue stress and fatigue temperature synchronous testing platform and measurement method, which has the following technical effects:

[0026] 1) Compared with existing bending fatigue testing devices, this invention can simultaneously obtain a general stress-life curve (SN curve) while also enabling real-time online measurement of high-speed rotating bending fatigue stress and fatigue temperature. This invention provides authentic and effective alternating stress and fatigue temperature rise data for in-depth research on fatigue cumulative damage and fracture in high-speed rotating shaft parts. This helps reveal the mechanism of material cumulative damage under fatigue alternating loads, develop accurate cumulative damage models, and accurately predict the lifespan of high-speed rotating shaft parts, thereby preventing high-speed rotating fatigue fracture accidents.

[0027] 2) Since liquid metal is used as the signal transmission medium of the rotating mechanism, no friction occurs when the rotating electrode and the liquid metal transmit signals, thereby avoiding the signal interference and drift problems caused by high-speed rotation friction marks and friction temperature rise of traditional conductive devices such as contact-type conductive slip rings, and realizing true and accurate measurement of high-speed rotating bending fatigue alternating stress and fatigue temperature without interference and drift.

[0028] 3) The coaxial signal transmission design is adopted, and the test device is separated from the test object, which does not generate any additional force on the sample and does not affect the measurement results. In addition, when the test sample is replaced, the test device does not need to be disassembled and can be used permanently.

[0029] 4) Patent application number "201720985741.9," titled "A Liquid Metal Conductive Slip Ring," utilizes a ring + conductor structure, with the ring filled with liquid metal and the conductor inserted into the ring cavity to enable electrical signal transmission. However, the device's conductor is a conductive sheet that does not pass through the liquid metal, resulting in only a single-level signal output. This application, on the other hand, utilizes multiple coaxially arranged groups of cylindrical electrodes that independently pass through corresponding groups of liquid metal, enabling coaxial output of multiple levels of signals. For example, fatigue signals (positive and negative) and temperature signals (positive and negative) require a total of four coaxially rotating electrodes to output the signals, a feat achieved by our device. However, the reference document only outputs a single pole and cannot achieve coaxial output of multiple poles. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings and examples:

[0031] Figure 1 It is a structural schematic diagram of the present invention.

[0032] Figure 2 This is a schematic diagram of the connection between the signal line and the sleeve combined electrode in the present invention.

[0033] Figure 3 This is a schematic diagram of the connection between the sleeve combined electrode and the liquid metal conductive device in the present invention.

[0034] Figure 4 Schematic diagram of the complete transmission route of the rotational alternating stress measurement signal in the present invention.

[0035] Figure 5 Schematic diagram of the fatigue-life measurement device in the present invention.

[0036] Figure 6 Schematic diagram of the counting device in the present invention.

[0037] Figure 7 Schematic diagram of the weight loading device in the present invention.

[0038] Figure 8 This is a schematic diagram of the structure in which the signal lead passes through the spring clip in the present invention.

[0039] Figure 9 This is a diagram showing actual measurements of fatigue stress and fatigue temperature during high-speed rotational bending alternating conditions in the present invention.

[0040] Figure 10 It is a partially enlarged diagram of fatigue stress and fatigue temperature in the present invention.

[0041] Figure: high-speed motor 1, mounting connector 2, sample 3, strain gauge 4, stress signal lead 5, stress lead positive electrode 51, stress lead negative electrode 52, spring chuck 6, stress wire hole 61, temperature wire hole 62, weight plate 7, hook 71, thermocouple 8, thermocouple signal lead 9, thermocouple lead positive electrode 91, thermocouple lead negative electrode 92, counter 10, counting wire 101, control box 11, power control line 112, support base 12, liquid gold conductive support platform 121, shaft support base 122, dynamic signal collector 13, computer 14, data line 15, stress signal lead negative electrode 16, stress signal lead positive electrode 161, thermocouple signal lead Negative electrode 162, positive electrode 163 of thermocouple signal wire, liquid metal conductive device 17, liquid metal device head 171, liquid metal device wall 172, sealed bearing 173, positive electrode 174 of thermocouple conductive column, negative electrode 175 of thermocouple conductive column, positive electrode 176 of stress conductive column, negative electrode 177 of thermocouple conductive column, liquid metal 178, sleeve combination electrode 18, negative electrode 181 of stress sleeve, positive electrode 182 of stress sleeve, negative electrode 183 of thermocouple sleeve, positive electrode 184 of thermocouple sleeve, C-shaped adapter clamp 19, hollow shaft 20, high-speed bearing 201, transmission wheel 21, counting hole 211, belt groove 212, tightening screw hole 213, belt 22. DETAILED DESCRIPTION

[0042] like Figure 1 、 Figure 5 As shown, a high-speed rotating bending fatigue stress and temperature synchronous test bench and measurement method includes a support base 12, to which are fixedly mounted a liquid metal conductive support base 121 and a rotating shaft support base 122. The liquid metal conductive support base 121 is used to mount a liquid metal conductive device 17. The rotating shaft support base 122 is provided in two sets, and a hollow shaft 20 is rotatably mounted on the rotating shaft support base 122 via bearings. The hollow shaft 20 is driven by a belt transmission mechanism consisting of a drive pulley 21 and a belt 22, and a high-speed motor 1. The rotational speed of the high-speed motor 1 is adjustable between 3,000 and 20,000 rpm.

[0043] like Figure 1 、 Figure 8 As shown, a spring chuck 6 is fixed to one end of the hollow shaft 20. The spring chuck 6 is provided with a stress wire hole 61 and a temperature wire hole 62. The stress wire hole 61 is for the stress signal lead 5 to pass through, and the temperature wire hole 62 is for the thermocouple signal lead 9 to pass through. The specimen 3 is mounted on the hollow shaft 20 via the spring chuck 6.

[0044] like Figure 1-2 As shown, a strain gauge 4 and a thermocouple 8 are installed on the sample 3, wherein the strain gauge is a temperature self-compensating strain gauge, and the thermocouple is any one of the welding point type K type, S type, E type, N type, J type, R type, and T type.

[0045] The stress signal lead 5 of the strain gauge 4 and the thermocouple signal lead 9 of the thermocouple 8 pass through the stress wire hole 61 and the temperature wire hole 62, respectively, and then connect to the sleeve assembly electrode 18. The sleeve assembly electrode 18 is inserted into the C-shaped adapter clamp 19 with an interference fit, and the C-shaped adapter clamp 19 is then locked to one end of the hollow shaft 20 using the spring collet 6.

[0046] The stress signal lead 5 includes a stress lead positive electrode 51 and a stress lead negative electrode 52 .

[0047] The thermocouple signal lead 9 includes a thermocouple lead positive electrode 91 and a thermocouple lead negative electrode 92 .

[0048] like Figure 3 As shown, the sheath combination electrode 18 includes four groups of electrodes, namely the stress sheath negative electrode 181, the stress sheath positive electrode 182, the thermocouple sheath negative electrode 183, and the thermocouple sheath positive electrode 184; among them, the stress lead negative electrode 52 is electrically connected to the stress sheath negative electrode 181, the stress lead positive electrode 51 is electrically connected to the stress sheath positive electrode 182, the thermocouple lead positive electrode 91 is electrically connected to the thermocouple sheath positive electrode 184, and the thermocouple lead negative electrode 92 is electrically connected to the thermocouple sheath negative electrode 183.

[0049] The stress sheath negative electrode 181, stress sheath positive electrode 182, thermocouple sheath negative electrode 183, and thermocouple sheath positive electrode 184 are made of metal. They are then sheathed together and secured with insulating adhesive to ensure they do not interfere with each other.

[0050] like Figure 3 As shown, the four electrodes of the sheathed electrode 18 gradually lengthen from the outside inward and extend outwards to the left and right. For example, in this embodiment, among the four electrode groups, the thermocouple sheath positive electrode 184 is the shortest and located in the outermost layer. The thermocouple sheath negative electrode 183 is nested within the thermocouple sheath positive electrode 184, with both ends extending out of the thermocouple sheath positive electrode 184; the stress sheath positive electrode 182 is nested within the thermocouple sheath negative electrode 183, with both ends extending out of the thermocouple sheath negative electrode 183; and the stress sheath negative electrode 181 is nested within the stress sheath positive electrode 182, with both ends extending out of the stress sheath positive electrode 182.

[0051] like Figure 3 As shown, the four groups of electrodes of the sleeve combination electrode 18 pass through a group of liquid metal conductive devices 17 respectively. Figure 3As shown, the four sets of liquid metal conductive devices 17 are labeled a, b, c, and d from right to left. The positive electrode 184 of the thermocouple sleeve passes through a and contacts the liquid metal 178 in a. The negative electrode 183 of the thermocouple sleeve passes through b and contacts the liquid metal 178 in b. The positive electrode 182 of the stress sleeve passes through c and contacts the liquid metal 178 in c. The negative electrode 181 of the stress sleeve passes through d and contacts the liquid metal 178 in d. When the sleeve combination electrode 18 rotates in the liquid metal 178, it can transmit the temperature signal to the head signal wire connector through the liquid metal 178.

[0052] like Figure 3-4 As shown, each set of liquid metal conductive devices 17 includes a liquid metal device wall 172, which is connected to the liquid metal device head 171 to form a sealed container. The sealed container is equipped with sealed bearings 173 on the left and right sides for the sleeve combination electrode 18 to pass through in a sealed manner. The sealed bearings 173 are high-speed waterproof bearings. Liquid metal 178 is provided in the sealed container, and a set of signal wire connectors is installed on one side of the sealed container. The four sets of signal wire connectors of the four sets of liquid metal conductive devices 17 are respectively the positive electrode 174 of the thermocouple conductive column, the negative electrode 175 of the thermocouple conductive column, the positive electrode 176 of the stress conductive column, and the negative electrode 177 of the thermocouple conductive column. When the sleeve combination electrode 18 rotates in the liquid metal, it transmits the signal to the four sets of signal wire connectors of the liquid metal conductive device 17 through the liquid metal.

[0053] The liquid metal device wall 172 and the liquid metal device head 171 are both made of insulating rubber material, and the sealing bearing 173 is made of insulating ceramic wear-resistant material.

[0054] The sealed container formed by connecting the liquid gold device wall 172 and the liquid gold device head 171, and the high-speed waterproof sealed bearing 173 can prevent the conductive liquid gold from seeping and leaking during the high-speed rotation of the sleeve combination electrode 18.

[0055] Preferably, the liquid metal 178 is a gallium-indium-based alloy that is liquid at room temperature, thereby ensuring that the stress sleeve negative electrode 181, stress sleeve positive electrode 182, thermocouple sleeve negative electrode 183, thermocouple sleeve positive electrode 184 immersed therein achieve non-contact signal communication with the thermocouple conductive column positive electrode 174, thermocouple conductive column negative electrode 175, stress conductive column positive electrode 176, and thermocouple conductive column negative electrode 177 at room temperature.

[0056] like Figure 4As shown, a dynamic signal acquisition instrument 13 is installed on one side of the workbench. Four sets of signal wire connectors on four sets of liquid metal conductive devices 17 are connected to the stress signal wire cathode 16, stress signal wire anode 161, thermocouple signal wire cathode 162, and thermocouple signal wire anode 163, respectively. The other ends of the stress signal wire cathode 16, stress signal wire anode 161, thermocouple signal wire cathode 162, and thermocouple signal wire anode 163 are connected to the dynamic signal acquisition instrument 13. The dynamic signal acquisition instrument 13 is electrically connected to a computer 14 via a data cable 15.

[0057] like Figure 6 As shown, a counting hole 211 is provided on the transmission wheel 21, and a counter 10 is installed at a suitable position below the transmission wheel 21. The counter 10 is connected to the control box 11 through a counting wire 101. The counter 10 counts and is used to record the number of fatigue life.

[0058] like Figure 7 As shown, a mounting connector 2 is fixed to the other end of the specimen 3, and a weight plate 7 is mounted on the mounting connector 2. In this device, power is provided by a high-speed motor, which drives the specimen to rotate via a belt and a drive pulley. The specimen is subjected to fatigue load by the weight, and the number of fatigue cycles is recorded by a counter. The test is stopped when the specimen breaks, and the cycle count is read from the counter. After repeated sets of tests, the SN curve is plotted based on the fatigue load and the number of cycles.

[0059] A high-speed rotating bending fatigue stress and temperature synchronous test bench and measurement method, comprising the following steps:

[0060] Step 1: If Figure 4-5 、 Figure 8 As shown, first pass the strain gauge 4, stress signal lead 5, thermocouple 8, and thermocouple signal lead 9 through the spring collet 6 and hollow shaft 20. Then, connect the stress lead positive electrode 51 and the stress lead negative electrode 52 to the stress sheath positive electrode 182 and the stress sheath negative electrode 181 of the sheath combination electrode 18 respectively; connect the thermocouple lead positive electrode 91 and the thermocouple lead negative electrode 92 to the thermocouple sheath positive electrode 184 and the thermocouple sheath negative electrode 183 of the sheath combination electrode 18 respectively. Then, adhere the strain gauge 4 and thermocouple 8 to the specimen 3, and fix one end of the specimen 3 to the hollow shaft 20 using the spring collet 6.

[0061] Step 2: Fix the mounting connector 2 to the other end of the specimen 3 and attach the weight plate 7 according to the fatigue load.

[0062] Step 3: Insert the sleeve electrode assembly 18 into the C-shaped adapter clamp 19, and then use the spring clamp 6 to fix the sleeve electrode assembly 18 to one end of the hollow shaft 20.

[0063] Step 4: After the four electrodes extending from the sheath combination electrode 18 (the stress sheath negative electrode 181, the stress sheath positive electrode 182, the thermocouple sheath negative electrode 183, and the thermocouple sheath positive electrode 184) are passed through four independent liquid metal conductive devices 17, liquid metal 178 is injected into the liquid metal conductive device 17 so that the stress sheath negative electrode 181, the stress sheath positive electrode 182, the thermocouple sheath negative electrode 183, and the thermocouple sheath positive electrode 184 are immersed in and pass through the liquid metal 178.

[0064] Step 5: Use the stress signal wire negative electrode 16, the stress signal wire positive electrode 161, the thermocouple signal wire negative electrode 162, and the thermocouple signal wire positive electrode 163 to respectively connect the liquid metal conductive column stress conductive column negative electrode 177, the stress conductive column positive electrode 176, the thermocouple conductive column negative electrode 175, the thermocouple conductive column positive electrode 174 and the dynamic signal acquisition instrument 13, and use the data cable 15 to connect the computer 14 and the dynamic signal acquisition instrument 13, open the stress and temperature acquisition control software, adjust the parameters to clear the bridge balance, and prepare to collect data.

[0065] Step 6: Start the high-speed motor 1, the belt 22 drives the transmission wheel 21 and the hollow shaft 20 to rotate, and the counter 10 records the number of fatigue cycles.

[0066] Step 7: After the sample breaks, stop the high-speed motor 1 and read the control box 11 to record the fatigue life times.

[0067] Step 8: Stop the stress and temperature acquisition control software, store the fatigue fracture stress change and fatigue temperature curve throughout the life cycle, the results are as follows Figure 9 As shown in the figure, the collected fatigue alternating stress and fatigue temperature data have no interference signal and no signal drift; the local amplified signal is as shown in the figure. Figure 10 As shown in the figure, when the stress ratio of the rotating bending fatigue alternating stress is R=-1, the measured fatigue alternating stress is a sinusoidal wave law and the fatigue temperature is an upward trend.

Claims

1. A high-speed rotating bending fatigue stress and temperature synchronization test bench, characterized by: The hollow shaft (20) is rotatably mounted on the support base (12), and the hollow shaft (20) is driven to rotate at high speed by a driving device; a sample (3) is fixed to one end of the hollow shaft (20), a strain gauge (4) and a thermocouple (8) are mounted on the sample (3), a stress signal lead (5) of the strain gauge (4) and a thermocouple signal lead (9) of the thermocouple (8) pass through the hollow shaft (20) and are correspondingly connected to the sleeve combination electrode (18), and the sleeve combination electrode (18) is fixed to the other end of the hollow shaft (20); Each set of electrodes of the sleeve combined electrode (18) passes through a corresponding set of liquid metal conductive devices (17), and the liquid metal conductive devices (17) are electrically connected to the dynamic signal acquisition instrument (13) and the computer (14) in sequence; The sheath combination electrode (18) comprises a conductive stress sheath negative electrode (181), a stress sheath positive electrode (182), a thermocouple sheath negative electrode (183), and a thermocouple sheath positive electrode (184); the stress sheath negative electrode (181), the stress sheath positive electrode (182), the thermocouple sheath negative electrode (183), and the thermocouple sheath positive electrode (184) are sheathed together and fixed with insulating glue to maintain mutual insulation; The four electrodes of the sleeve combination electrode (18) gradually become longer from the outside to the inside and extend gradually to the left and right; The liquid metal conductive device (17) includes a liquid metal device wall (172), the liquid metal device wall (172) is connected to the liquid metal device head (171) to form a sealed container, and sealed bearings (173) for the sleeve combined electrode (18) to pass through are installed on the left and right sides of the sealed container. Liquid metal (178) is provided in the sealed container, and a signal wire connector is installed on one side of the sealed container; The high-speed rotation fatigue alternating stress of the sample (3) is collected in real time through the strain gauge (4), and the fatigue temperature is collected through the thermocouple (8); the collected signal is output coaxially through the lead and connected to the sleeve combination electrode (18); the sleeve combination electrode (18) is fixed on the hollow shaft (20) by the spring clamp (6) and rotates synchronously with the sample (3); the four electrodes of the sleeve combination electrode (18) pass through and are immersed in four independent liquid metal conductive devices (17); when rotating at high speed, the sleeve combination electrode (18) transmits the signal to the dynamic signal acquisition instrument (13) through the liquid metal in the liquid metal conductive device (17), and the collected data is recorded in real time by the computer (14) through the data line.

2. The high-speed rotating bending fatigue stress and temperature synchronous test bench according to claim 1, characterized in that: The liquid metal (178) is a liquid gallium-indium-based alloy at room temperature.

3. The high-speed rotating bending fatigue stress and temperature synchronization test bench according to claim 2, characterized in that: The hollow shaft (20) and the sample (3), and the hollow shaft (20) and the sleeve combination electrode (18) are fixed by a C-shaped adapter tube clamp (19) with an insulating layer on the inner wall and a spring chuck (6), and the spring chuck (6) is correspondingly provided with a wire hole.

4. The method for measuring a high-speed rotating bending fatigue stress and temperature synchronization test bench according to claim 3, comprising the following steps: Step 1: First, pass the strain gauge (4), stress signal lead (5), thermocouple (8), and thermocouple signal lead (9) through the spring chuck (6) and the hollow shaft (20); then connect the positive and negative poles of the stress signal lead (5) to the positive and negative poles of the stress sleeve of the sleeve combination electrode (18); connect the positive and negative poles of the thermocouple signal lead (9) to the positive and negative poles of the thermocouple sleeve of the sleeve combination electrode (18); then stick the strain gauge (4) and the thermocouple (8) on the sample (3), and fix one end of the sample (3) on the hollow shaft (20) with the spring chuck (6); Step 2: Fix the mounting connector (2) to the other end of the specimen (3) and attach the weight plate (7) according to the fatigue load; Step 3: Insert the sleeve-type electrode (18) into the C-shaped adapter tube clamp (19), and then use the spring chuck (6) to fix the sleeve-type electrode (18) together at one end of the hollow shaft (20); Step 4: After the four electrodes extending from the sleeve combination electrode (18) pass through the four independent liquid metal conductive devices (17), liquid metal (178) is injected into the liquid metal conductive device (17) so that the four electrodes extending from the sleeve combination electrode (18) are immersed in and pass through the liquid metal (178) of the corresponding liquid metal conductive device (17); Step 5: Use multiple sets of signal wires to connect the liquid metal conductive device (17) and the dynamic signal acquisition instrument (13) respectively, and use a data line (15) to connect the computer (14) and the dynamic signal acquisition instrument (13), open the stress and temperature acquisition control software, adjust the parameters to reset the bridge balance, and prepare to collect fatigue alternating stress and fatigue temperature data; Step 6: Start the high-speed motor (1), the belt (22) drives the transmission wheel (21) and the hollow shaft (20) to rotate, and the counter (10) records the number of fatigue cycles; Step 7: After the sample breaks, stop the high-speed motor (1), read the fatigue life times recorded by the control box (11), and obtain a SN data; Step 8: Stop the stress and temperature acquisition control software and store the fatigue fracture full life stress change and fatigue temperature curve; Step 9: Repeat the above steps to complete the SN curve and real-time stress and temperature change curve.

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