A high temperature, high and low cycle composite fatigue test system

Abstract

The present invention is a high-temperature, high-low cycle composite fatigue test system, which uses a hydraulic system to load low-cycle loads and an electromagnetic vibration table to load high-frequency vibration loads (the frequency can reach up to 1000Hz). For engineering materials and engineering parts, fatigue tests under the combined action of axial (Y-axis) low-cycle tensile stress and horizontal (X-axis) high-frequency loads can be completed, and the load spectrum is shown in Figure 1. The system of the present invention can save time and efficiently simulate the high-low cycle composite fatigue test of engineering materials and engineering parts in the use environment, and the test system is simple and practical with low cost.

Description

Technical Field

[0001] The invention relates to a high-temperature, high-low cycle composite fatigue test system, belonging to the technical field of mechanical performance testing. Background Art

[0002] Fatigue failure is a common form of failure of engineering materials. Conducting fatigue performance tests on engineering materials and obtaining fatigue failure life under specific stress levels are of great significance for the design and life prediction of engineering structural parts. In the past, material fatigue tests were mostly completed by axial stress loading, and high-cycle and low-cycle tests were performed in the elastic range and plastic range of the material, respectively, which could not reflect the actual working conditions of some engineering parts under high- and low-cycle composite stress. In recent years, with the development of industrial technology, the demand for fatigue performance testing of advanced materials under high- and low-cycle composite stress has greatly increased. Some industrial equipment (aircraft, high-speed rail, etc.) has also put forward higher requirements for the high- and low-cycle composite fatigue performance of key components, requiring fatigue testing of some key components to be completed under high- and low-cycle composite stress. For example, blades and shafts of aircraft engines. Therefore, high-frequency fatigue and low-cycle fatigue tests based on traditional single-item loading can no longer fully meet the testing needs of modern material fatigue performance, and high- and low-cycle composite fatigue performance tests are urgently needed.

[0003] At present, all material fatigue tests are based on traditional single-item loading high-frequency fatigue and low-cycle fatigue tests, which cannot simulate the actual working environment of some aircraft engine engineering parts. In addition, the traditional single-item loading high-frequency fatigue and low-cycle fatigue test data cannot accurately reflect the material fatigue characteristics of engineering parts under multi-axial stress. Summary of the invention

[0004] The present invention is designed to address the deficiencies in the above-mentioned prior art and provides a high-temperature, high- and low-cycle composite fatigue testing system. The system combines an electromagnetic vibration table and a hydraulic system together to achieve the testing of the high- and low-cycle composite fatigue properties of materials under room temperature and high temperature conditions. The test results have important application value for the fatigue life evaluation of engineering materials.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] This high temperature, high and low cycle composite fatigue test system includes a main control computer for receiving and processing data, and also includes a low cycle loading device and a high frequency vibration device, wherein:

[0007] The low-frequency loading device includes a rigid frame structure arranged on the main frame table 11, a low-frequency force hydraulic actuator 4 is fixed on the frame structure, a force value sensor 7 is installed on the low-frequency force hydraulic actuator 4 to measure and control the low-frequency force value and the holding time in real time, an actuating rod 5 of the low-frequency force hydraulic actuator 4 is rigidly connected to a vibration-assisting plate 1, and the vibration-assisting plate 1 is rigidly connected to one end of the sample to be tested 2 and performs low-frequency loading on the sample to be tested 2;

[0008] The high-frequency vibration device includes an electromagnetic vibration table 8, which is connected to a high-frequency force plate 6 through a transition plate 12. The high-frequency force plate 6 outputs high-frequency vibration, and the vibration direction is 90° to the action direction of the actuating rod 5 of the low-frequency hydraulic actuator 4. The center of the high-frequency force plate 6 is rigidly connected to the other end of the sample to be tested 2 through a clamp lower pull rod 3;

[0009] The laser displacement sensor 16 installed on the vibration-assisting plate 1 is used to monitor the amplitude of the vibration-assisting plate 1 in real time and feed it back to the main control computer to control the electromagnetic vibration table 8 and maintain the high-frequency load on the test sample 2.

[0010] In one implementation, the rigid frame structure is a cubic rigid structure consisting of a load-bearing structure tie rod 9 and front and rear plates 10 of the load-bearing structure, wherein the load-bearing structure tie rod 9 is in a transverse position and parallel to the actuating rod 5 of the low-frequency booster hydraulic actuator 4, and the front and rear plates 10 of the load-bearing structure are in a longitudinal position and parallel to the high-frequency force plate 6 connected to the electromagnetic vibration table 8.

[0011] In one implementation, a hydraulic oil tank 15 and a hydraulic oil pump 14 are installed below the main frame table 11 .

[0012] In one implementation, two sets of low-frequency hydraulic actuators 4 are fixedly mounted on the frame structure, and their actuator rods 5 are rigidly connected to the two ends of the vibration-supporting plate 1 so that the test sample 2 is located between the two ends.

[0013] Furthermore, the vibration-assisting plate 1 is an "E"-shaped structure, the actuating rods 5 of the two sets of low-frequency boosting hydraulic actuators 4 are rigidly connected to the upper and lower arms of the "E"-shaped structure, and one end of the test sample 2 is rigidly connected to the middle arm of the "E"-shaped structure.

[0014] In one implementation, a high-frequency heating induction coil 17 is mounted on the outer circumference of the test sample 2, and the eddy current heating function is used to achieve a temperature environment to simultaneously meet the high temperature requirements of the high- and low-cycle composite fatigue test.

[0015] In one implementation, the high-frequency force-applying plate 6 is a rectangular plate-shaped structure, and a pressure-bearing bearing 15 is installed between the high-frequency force-applying plate 6 and the front and rear plates 10 of the adjacent load-bearing structure.

[0016] In one implementation, threads are processed at both ends of the test sample 2, and the middle is a plate working section. The test sample 2 is tightly matched with the vibration-assisting plate 1 and the lower sample fixture 3 through the threads at both ends.

[0017] In one implementation, the force sensor 7 is a piezoelectric force sensor, which is a device for measuring the low-cycle load on the test sample 2 .

[0018] In one implementation, the loading frequency of the high-frequency vibration device is greater than 1000 Hz.

[0019] The main control computer is a conventional desktop electronic computer, which can realize the control of the test system and the real-time collection of test data by installing corresponding control and data acquisition software.

[0020] The electromagnetic vibration table 8 is a conventional electromagnetic vibration table, which utilizes electromagnetic excitation to generate a periodic driving force to apply a fatigue load to the test sample 2. The rated exciting force of the electromagnetic vibration table 8 meets the loading requirements of the sample in the fatigue test.

[0021] The main frame table top 11 and the rigid frame structure are both made of high-strength steel, which serves to connect and fix the various components of the test system. The strength and rigidity thereof meet the stability requirements of the test system.

[0022] The technical solution of the present invention uses a hydraulic system to load low-cycle loads and an electromagnetic vibration table to load high-frequency vibration loads (the frequency can reach up to 1000Hz). For engineering materials and engineering parts, fatigue tests under the combined action of axial (Y-axis) low-cycle tensile-tensile stress and horizontal (X-axis) high-frequency loads can be completed. The load spectrum is as follows: Figure 1 The system of the present invention can save time and efficiently simulate the high and low cycle composite fatigue test of engineering materials and engineering parts in the use environment. The test system is simple and practical with low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The load spectrum of the test system of the present invention is

[0024] Figure 2 The main structural diagram of the test system of the present invention is

[0025] Figure 3 for Figure 1 Top view

[0026] Figure 4 Schematic diagram of the shape of the sample to be tested

[0027] Figure 5 Schematic diagram of the shape of the test sample with a high-frequency heating induction coil DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments:

[0029] See attached Figures 2 to 5 As shown, this high temperature, high and low cycle composite fatigue test system includes a main control computer for receiving and processing data, and also includes a low frequency loading device and a high frequency vibration device, wherein:

[0030] The low-frequency loading device includes a rigid frame structure arranged on the main frame table 11, and the rigid frame structure is a cubic rigid structure composed of a load-bearing structure tie rod 9 and a load-bearing structure front and rear plates 10, wherein the load-bearing structure tie rod 9 is in a transverse position and parallel to the actuating rod 5 of the low-frequency booster hydraulic actuator 4, and the load-bearing structure front and rear plates 10 are in a longitudinal position and parallel to the high-frequency force application plate 6 connected to the electromagnetic vibration table 8; a hydraulic oil tank 15 and a hydraulic oil pump 14 are installed below the main frame table 11;

[0031] Two sets of low-frequency forcing hydraulic actuators 4 are fixedly installed on the frame structure, and their actuating rods 5 are rigidly connected to the two ends of the vibration-assisting plate 1 so that the test sample 2 is located between the two ends; the vibration-assisting plate 1 is an "E"-shaped structure, and the actuating rods 5 of the two sets of low-frequency forcing hydraulic actuators 4 are rigidly connected to the upper and lower arms of the "E"-shaped structure, and one end of the test sample 2 is rigidly connected to the middle arm of the "E"-shaped structure; a force value sensor 7 is installed on the low-frequency forcing hydraulic actuator 4 to measure and control the low-frequency force value and the holding time in real time;

[0032] The hydraulic oil pump 14 supplies pressure to the low-cycle booster hydraulic actuator 4, and the actuator rod 5 applies a low-cycle load to the test sample 2, and the test sample 2 is in an overall rigid connection state;

[0033] The high-frequency vibration device includes an electromagnetic vibration table 8, which is an electromagnetic vibration table. The electromagnetic vibration table 8 uses electromagnetic excitation to generate a periodic driving force to apply a fatigue load to the test sample 2. The rated exciting force of the electromagnetic vibration table meets the loading requirements of the sample in the fatigue test. The electromagnetic vibration table 8 is connected to the high-frequency force plate 6 through a transition plate 12. The high-frequency force plate 6 outputs high-frequency vibration, and the vibration direction is 90° to the action direction of the actuating rod 5 of the low-frequency force hydraulic actuator 4. The center of the high-frequency force plate 6 is rigidly connected to the other end of the test sample 2 through the clamp lower pull rod 3;

[0034] In this embodiment, the high-frequency force-applying plate 6 is a rectangular plate-shaped structure, and a pressure-bearing bearing 15 is installed between the high-frequency force-applying plate 6 and the front and rear plates 10 of the adjacent load-bearing structure.

[0035] The laser displacement sensor 16 installed on the vibration-assisting plate 1 is used to monitor the amplitude of the vibration-assisting plate 1 in real time and feed it back to the main control computer to control the electromagnetic vibration table 8 and maintain the high-frequency load on the test sample 2.

[0036] In practice, a high-frequency heating induction coil 17 can be mounted on the outer circumference of the test sample 2 as needed, and the eddy current heating function can be used to achieve a temperature environment to simultaneously meet the high temperature requirements of the high- and low-cycle composite fatigue test.

[0037] In this embodiment, the test sample 2 is an hourglass-shaped round rod with threads at both ends and a plate working section in the middle. The test sample 2 is tightly matched with the vibration-supporting plate 1 and the sample lower fixture 3 through the threads at both ends.

[0038] In this embodiment, the force sensor 7 is a piezoelectric force sensor, which is a device for measuring the low-cycle load on the test sample 2.

[0039] The main control computer measures and controls the low-cycle force value and holding time in real time according to the force sensor 7; the laser displacement sensor 16 monitors the amplitude of the vibration-assisting plate 1 in real time, and feeds back to the main control computer to control the electromagnetic vibration table 8 to maintain the high-frequency load on the test sample 2, thereby completing the high- and low-cycle composite fatigue test under stress control.

[0040] The corresponding control software is installed on the main control computer. Before the specimen is installed and formally loaded, the average load is set according to the low-cycle load stress ratio through the visual interface, the specimen installation concentricity is checked by pre-loading, and the frequency sweep check is performed at the same time. When everything is normal, the test frequency, maximum load and other related information are input into the main control computer, and the test status can be monitored in real time through the signal acquisition software.

[0041] During the high temperature test, after the sample or engineering part 2 is installed, the high frequency heating induction coil 17 is placed on the working section of the sample 2 to be tested, and the test 2 is heated by power. After reaching the predetermined temperature, the temperature is kept unchanged. If the test requirement is a room temperature test, the high frequency heating induction coil 17 does not need to be installed.

[0042] like Figure 1 As shown, after satisfying the stress ratio settings, the hydraulic actuator 4 is then used to apply low-cycle loads for cyclic dynamic loading, and the electromagnetic vibration table (8) is used for vibration fatigue loading. According to the actual situation of the test sample 2, the loading frequency can be greater than 1000 Hz, and the cycle count is started at the same time as the vibration fatigue loading until the sample is fatigued or reaches the specified maximum cycle number (for example, 10 9 ) The test is stopped. For the specific operation method of the test, please refer to "Axial Force Control Method for Fatigue Test of Metallic Materials" (GB / T 3075-2008).

Claims

1. A high temperature, high and low cycle composite fatigue test system, characterized in that: The system includes a main control computer for receiving and processing data, a low-frequency loading device and a high-frequency vibration device, wherein: The low-frequency loading device comprises a rigid frame structure arranged on the table surface of a main frame, two groups of low-frequency force-added hydraulic actuators are fixed on the frame structure, force value sensors are installed on the low-frequency force-added hydraulic actuators to measure and control the low-frequency force value and the holding time in real time, the actuating rod of the low-frequency force-added hydraulic actuator is rigidly connected to the two ends of a vibration-assisted plate (1) so that the sample to be tested is located between the two ends, and the vibration-assisted plate is rigidly connected to one end of the sample to be tested and performs low-frequency loading on the sample to be tested; The vibration-assisting plate is an "E"-shaped structure, the actuating rods of two sets of low-frequency hydraulic actuators are rigidly connected to the upper and lower arms of the "E"-shaped structure, and one end of the sample to be tested is rigidly connected to the middle arm of the "E"-shaped structure; The high-frequency vibration device includes an electromagnetic vibration table, which is connected to a high-frequency force plate through a transition plate. The high-frequency force plate outputs high-frequency vibration, and the vibration direction is 90° to the action direction of the actuating rod of the low-frequency hydraulic actuator. The center of the high-frequency force plate is rigidly connected to the other end of the sample to be tested through a clamp lower pull rod. The electromagnetic vibration table uses electromagnetic excitation to generate a periodic driving force to apply a fatigue load to the sample to be tested. The rated exciting force of the electromagnetic vibration table meets the loading requirements of the sample in the fatigue test. The laser displacement sensor installed on the vibration-assisting plate is used to monitor the amplitude of the vibration-assisting plate in real time and feed it back to the main control computer to control the electromagnetic vibration table and maintain the high-frequency load on the test sample.

2. The high temperature, high and low cycle composite fatigue test system according to claim 1 is characterized in that: The rigid frame structure is a cubic rigid structure consisting of a load-bearing structure tie rod and front and rear plates of the load-bearing structure, wherein the load-bearing structure tie rod is in a transverse position and parallel to the actuating rod of the low-frequency booster hydraulic actuator, and the front and rear plates of the load-bearing structure are in a longitudinal position and parallel to the high-frequency force plates connected to the electromagnetic vibration platform.

3. The high temperature, high and low cycle composite fatigue test system according to claim 1 is characterized in that: A hydraulic oil tank and a hydraulic oil pump are installed below the main frame table.

4. The high temperature, high and low cycle composite fatigue test system according to claim 1, characterized in that: A high-frequency heating induction coil is mounted on the outer circumference of the test sample to simultaneously meet the high temperature requirements of high- and low-cycle composite fatigue tests.

5. The high temperature, high and low cycle composite fatigue test system according to claim 1 is characterized in that: The high-frequency force-applying plate is a rectangular plate-shaped structure, and a pressure bearing is installed between the high-frequency force-applying plate and the front and rear plates of the adjacent load-bearing structure.

6. The high temperature, high and low cycle combined fatigue test system according to claim 1, characterized in that: The two ends of the test sample are processed with threads, and the middle is a plate working section. The test sample is closely matched with the vibration-assisting plate and the lower clamp of the sample through the threads at the two ends.

7. The high temperature, high and low cycle combined fatigue test system according to claim 1, characterized in that: The force sensor is a piezoelectric force sensor.

8. The high temperature, high and low cycle combined fatigue test system according to claim 1 is characterized in that: The loading frequency of the high-frequency vibration device is greater than 1000 Hz.

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