High-frequency tension-compression vibration fatigue test system for self-heating material

Abstract

The utility model belongs to the technical field of aircraft structure fatigue tests, and particularly relates to a high-frequency tension-compression vibration fatigue test system for a spontaneous heating material. The system comprises a test piece (1), a balancing weight (3), a vibration table (4), a displacement sensor (5) and a vortex tube (6), the test piece (1) is of a structure which is made of a spontaneous heating material and has two wide ends and a narrow middle, and the middle section is a smooth curved surface; the vibration table (4) is used for providing vibration with the frequency being continuously adjustable within the range of 5 Hz to 4000 Hz, the test piece (1) is vertically arranged, and the bottom end of the test piece (1) is fixed to the vibration table (4). The balancing weight (3) is fixed at the top end of the test piece (1); the displacement sensor (5) is arranged right above the balancing weight (3); and a cold air outlet of the vortex tube (6) is aligned with the middle section of the test piece (1). The measurement precision can be improved, and the accurate fatigue performance of the material can be obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aircraft structure fatigue test, and particularly relates to a high-frequency tension-compression vibration fatigue test system of self-heating material. BACKGROUND

[0002] Blade is one of the main components of an aero-engine, and the performance of the blade not only determines the performance level of the whole engine, but also directly relates to the use reliability and service life of the engine. High-frequency tension-compression fatigue failure of the aero-engine blade due to resonance under the action of periodic airflow excitation force is an important failure form of the blade. In order to provide a reference for the design of the engine blade, it is necessary to test and study the high-frequency tension-compression fatigue performance of the blade material.

[0003] At present, the tension-compression fatigue test of the material is mainly carried out by using a hydraulic servo fatigue testing machine, and the highest loading frequency thereof is only dozens of hertz, while the natural frequency of the blade can reach 4000 Hz. The test frequency of the hydraulic servo fatigue testing machine is far lower than the natural frequency of the blade, and it is difficult to reflect the fatigue performance of the blade material under the working environment. An ultrasonic fatigue testing machine can also be used for testing the tension-compression fatigue performance of the material, and the loading frequency thereof is as high as 20 kHz, which is much higher than the natural frequency of the blade, and it is also difficult to reflect the fatigue performance of the blade material under the working environment.

[0004] In addition, the aero-engine blade material is mostly high-temperature titanium alloy and nickel-based high-temperature alloy, and a large amount of heat is generated in these materials during high-frequency vibration, so that the temperature of the test area is increased, and the test result is inaccurate. CONTENT OF THE INVENTION

[0005] In order to solve at least one of the above technical problems, the application provides a high-frequency tension-compression vibration fatigue test system of self-heating material, which mainly comprises:

[0006] A test piece made of self-heating material and having a structure of wide at both ends and narrow in the middle, and a smooth curved surface in the middle section;

[0007] A vibration table for providing continuous adjustable vibration with a frequency in the range of 5 Hz to 4000 Hz, the test piece is vertically placed, and the bottom end thereof is fixed on the vibration table;

[0008] A counterweight fixed at the top end of the test piece;

[0009] A displacement sensor arranged directly above the counterweight;

[0010] A vortex tube, and the cold air outlet thereof is aligned with the middle section of the test piece.

[0011] Preferably, the two ends of the test piece are provided with external threads to be threadedly connected with the vibration table and the counterweight.

[0012] Preferably, the test piece is provided with a locknut at the connection with the vibration table.

[0013] Preferably, the test piece is provided with a locknut at the connection with the counterweight.

[0014] Preferably, the outer wall of the cold air outlet pipe of the vortex tube is wrapped with heat insulation cotton.

[0015] Preferably, the vibration table is provided with an acceleration sensor on the table surface.

[0016] The application can improve the measurement accuracy and obtain accurate fatigue performance of the material. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural schematic diagram of the self-heating material high-frequency tension-compression vibration fatigue test system of the application.

[0018] Among them, 1-test piece, 2-locknut, 3-counterweight, 4-vibration table, 5-displacement sensor, 6-vortex tube, 7-heat insulation cotton, 8-compressed air inlet, 9-acceleration sensor. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme in the embodiment of the application will be described in more detail below in combination with the drawings in the embodiment of the application. In the drawings, the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The described embodiments are part of the embodiments of the application, not all of the embodiments of the application. The embodiments described below by referring to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application. The embodiments of the application will be described in detail below in combination with the drawings.

[0020] The application provides a self-heating material high-frequency tension-compression vibration fatigue test system, as shown in Figure 1 The application provides a self-heating material high-frequency tension-compression vibration fatigue test system, as shown in

[0021] The test piece 1 is a structure with two wide ends and a narrow middle part made of self-heating material, and the middle section is a smooth curved surface;

[0022] The vibration table 4 is used to provide continuous vibration with a frequency in the range of 5Hz-4000Hz, and the test piece 1 is vertically placed with its bottom end fixed on the vibration table 4;

[0023] The counterweight 3 is fixed at the top end of the test piece 1;

[0024] A displacement sensor 5 is arranged directly above the counterweight 3.

[0025] A vortex tube 6 has a cold air outlet directed at the middle section of the test piece 1.

[0026] The present application can apply tensile-compressive fatigue load with a stress ratio of -1 to the material, and the loading frequency is continuously adjustable in the range of 5 Hz to 4000 Hz. Meanwhile, the influence of spontaneous heating of high-frequency vibration on the test results can be eliminated. Specifically, by designing the test piece 1 and the counterweight 3, the natural frequency of the test system reaches the design frequency requirement. The excitation frequency of the high-frequency vibration table 4 is adjusted to be near the natural frequency of the test system. At this time, the test piece 1 resonates and generates a large high-frequency alternating tensile-compressive stress in the middle part, thereby realizing fatigue loading.

[0027] The test piece 1 is in the shape of a dog bone, with wide upper and lower ends and a smooth curved middle section. Under the action of high-frequency vibration load, the maximum stress occurs in the middle section of the test piece 1, and fatigue failure eventually occurs in this section.

[0028] The test piece 1 is made of a self-heating material. Under the action of high-frequency alternating large stress, the middle section of the test piece 1 quickly heats up. As the fatigue test progresses, the heat accumulates, causing the temperature to rise. The temperature in the middle section of the test piece 1 can reach several hundred degrees Celsius, which seriously affects the accuracy of the test results. In the test, compressed air is injected into the vortex tube 6 through the compressed air inlet 8. The compressed air forms low-temperature gas through the vortex tube 6, which directly cools the middle section of the test piece 1, thereby improving the cooling efficiency.

[0029] In the test, the displacement sensor 5 monitors the vibration displacement of the top end of the counterweight 3. The displacement sensor 5 is arranged directly above the counterweight 3, and the displacement measuring point is located at the geometric center of the counterweight 3. During the entire test process, the displacement measured by the displacement sensor 5 is used as the control quantity to keep it unchanged during the entire fatigue process, thereby ensuring that the stress of the test piece remains unchanged. Specifically, first, the vibration table 4 is started to perform a sweep test to obtain the resonance frequency of the test system. Then, the excitation frequency of the vibration table 4 is set near the resonance frequency of the test system, so that the test piece 1 is in a resonant state. When the fatigue test starts, the natural frequency of the system composed of the test piece 1 and the counterweight 3 will slowly decrease as the fatigue test progresses. At this time, the excitation frequency of the vibration table 4 can be adjusted to ensure that the displacement measured by the displacement sensor 5 remains unchanged, thereby keeping the test system in a resonant state. When the test piece 1 generates a fatigue crack, the number of fatigue cycles is recorded, and the test is completed.

[0030] In some optional embodiments, the two ends of the test piece 1 are provided with external threads to be threadedly connected with the vibration table 4 and the counterweight 3.

[0031] In some alternative embodiments, a locking nut 2 is provided at the connection between the test piece 1 and the vibration table 4. In this embodiment, the lower end of the test piece 1 is connected to the threaded hole in the middle of the table surface of the vibration table 4 by a thread, and the locking nut 2 is used to fasten the test piece 1 and the vibration table 4 to prevent loosening during vibration.

[0032] In some alternative embodiments, a locking nut 2 is provided at the connection between the test piece 1 and the counterweight 3. In this embodiment, the upper end of the test piece 1 is connected to the threaded hole in the middle of the counterweight 3 by a thread, and the test piece 1 and the counterweight 3 are fastened by the locking nut 2 to prevent loosening during vibration.

[0033] In some alternative embodiments, the outer wall of the cold air outlet pipe of the vortex tube 6 is wrapped with heat-insulating cotton 7. This embodiment can prevent water vapor in the air from condensing on the pipe wall, avoiding the impact of condensate on the electrical equipment in the test system.

[0034] In some alternative embodiments, an acceleration sensor 9 is attached to the surface of the vibration table 4. It is understood that in vibration testing, acceleration is often used to describe the intensity of the vibration signal, and by measuring acceleration, the severity of the fault can be assessed.

[0035] This application has the following beneficial effects:

[0036] a) The loading frequency of the test system is continuously adjustable in the range of 5Hz to 4000Hz, and it can apply tensile and compressive fatigue loads with a stress ratio of -1 to the material, thus broadening the range of loading frequencies for fatigue tests.

[0037] b) A cooling system consisting of vortex tubes and thermal insulation cotton was adopted, which can eliminate the influence of high-frequency vibration self-heating of materials on the test results, while improving cooling efficiency and avoiding the generation of condensate.

[0038] c) The test piece was secured to the high-frequency vibration table with anti-loosening nuts to prevent loosening during vibration.

[0039] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A high-frequency tensile and compressive vibration fatigue testing system for self-heating materials, characterized in that, include: The test piece (1) is a structure made of self-heating material, which is wide at both ends and narrow in the middle, with a smooth curved surface in the middle section; The vibration table (4) is used to provide vibration with a frequency that is continuously adjustable in the range of 5Hz to 4000Hz. The test piece (1) is placed vertically and its bottom end is fixed on the vibration table (4). The counterweight (3) is fixed to the top of the test piece (1); The displacement sensor (5) is positioned directly above the counterweight (3); The vortex tube (6) has its cold air outlet aligned with the middle section of the test piece (1).

2. The high-frequency tensile and compressive vibration fatigue testing system for self-heating materials as described in claim 1, characterized in that, The test piece (1) is configured with external threads at both ends to be threadedly connected to the vibration table (4) and the counterweight (3).

3. The high-frequency tensile and compressive vibration fatigue testing system for self-heating materials as described in claim 2, characterized in that, The test piece (1) is connected to the vibration table (4) with an anti-loosening nut (2).

4. The high-frequency tensile and compressive vibration fatigue testing system for self-heating materials as described in claim 2, characterized in that, The test piece (1) is provided with a locking nut (2) at the connection between it and the counterweight (3).

5. The high-frequency tensile and compressive vibration fatigue testing system for self-heating materials as described in claim 1, characterized in that, The outer wall of the cold air outlet pipe of the vortex tube (6) is wrapped with heat insulation cotton (7).

6. The high-frequency tensile and compressive vibration fatigue testing system for self-heating materials as described in claim 5, characterized in that, An acceleration sensor (9) is attached to the surface of the vibration table (4).

Images