Aeroengine turbine blade vibration and thermal shock fatigue test apparatus and method

Abstract

The present application relates to a kind of aero-engine turbine blade vibration and thermal shock fatigue test device and method, the device includes high-frequency vibration loading unit, for applying controllable high-frequency vibration;Blade clamping unit, for fixing blade and simulating real constraint;Thermal shock loading unit, for spraying high-temperature flame to blade surface target area;Gas cooling unit, for controllable cooling to blade;Temperature measurement unit, infrared thermal imaging unit and blade amplitude measurement unit, for non-contact real-time monitoring blade temperature field, dynamic displacement and strain.The method includes making scheme, installing test piece, parameter setting, applying vibration and closed-loop control thermal shock and the like steps.The present application has the advantages that: it can high-fidelityly simulate the synergistic effect of high-frequency vibration and transient thermal shock that blade endures in actual service, realizes the research and reliable evaluation of life to composite fatigue failure mechanism.

Description

Technical Field

[0001] This invention relates to a test apparatus and method for vibration and thermal shock fatigue testing of aero-engine turbine blades, belonging to the field of aero-engine component testing. Background Technology

[0002] As a core hot-end component, aero-engine turbine blades operate under extremely harsh conditions. During engine operation, blades are subjected not only to enormous centrifugal loads generated by high-speed rotation but also to continuous vibration loads caused by airflow pulsation and rotor imbalance. Simultaneously, due to the periodic scouring of high-temperature exhaust gases at the combustion chamber exit and the effects of film cooling, the blade surface temperature field exhibits severe transient fluctuations, meaning it experiences frequent thermal shocks. This synergistic effect of vibration and thermal shock generates complex multiaxial stress states and thermal stresses within the blade material, easily inducing combined damage from high-cycle fatigue (HCF), low-cycle fatigue (LCF), and even creep-fatigue interactions, ultimately leading to blade failure and severely impacting the engine's reliability, safety, and service life.

[0003] Currently, fatigue performance assessment of turbine blades mainly relies on single-factor or simplified combination test methods. For example, vibration fatigue tests cannot consider the impact of instantaneous high-temperature changes on the degradation of material mechanical properties and vibration characteristics; traditional thermal fatigue tests (such as thermomechanical fatigue TMF) can simulate the coupling of temperature and mechanical strain, but the loading frequency is usually low, generally on the order of 0.01-1 Hz, making it difficult to reproduce the real coupling effect of high-frequency vibration (up to several kilohertz) and rapid thermal shock (heating and cooling rates can reach tens to hundreds of degrees Celsius per second) in actual operation. In addition, existing test equipment still has shortcomings in the precise control of heat flux density, the faithful transmission of high-frequency vibration, and the real-time synchronous monitoring of multi-physics parameters, resulting in significant differences between test results and actual operating conditions, making it difficult to accurately predict the combined fatigue life of the blades.

[0004] The present invention aims to overcome the shortcomings of the prior art and develop a vibration-thermal shock composite fatigue test device and test method that can accurately simulate the actual service environment of turbine blades, so as to achieve accurate evaluation of the fatigue failure mechanism and life of blades under the coupling of multiple physical fields. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a testing device and method for vibration and thermal shock fatigue testing of aero-engine turbine blades. The technical solution of this invention is as follows: A test apparatus for vibration and thermal shock fatigue of aero-engine turbine blades includes: A high-frequency vibration loading unit (1) is used to apply a high-frequency vibration load with controllable frequency and amplitude to the turbine blade under test. The blade clamping unit (2) is connected to the high-frequency vibration loading unit (1) and is used to fix the turbine blade under test and simulate its real constraint state in the engine. A thermal shock loading unit (3) is installed on the side of the blade clamping unit (2) to generate and spray high-temperature flames toward the target area on the surface of the turbine blade under test to simulate high-speed gas thermal shock. Gas cooling unit (6) is used to spray cooling gas onto the surface of the turbine blade under test to achieve cooling; Temperature measurement unit (4) is used for non-contact real-time measurement of the temperature at a preset point on the surface of the turbine blade under test; Infrared thermal imaging unit (5) is used to acquire the temperature field distribution image of the surface of the turbine blade under test; The blade amplitude measurement unit (7) is used for non-contact real-time measurement of the vibration displacement of the surface of the turbine blade under test; Among them, the high-frequency vibration loading unit (1), thermal shock loading unit (3), gas cooling unit (6), temperature measurement unit (4), infrared thermal imaging unit (5) and blade amplitude measurement unit (7) are all connected to the control unit to realize the timing control of vibration load, thermal shock load, cooling process and synchronous data acquisition.

[0006] The high-frequency vibration loading unit (1) includes an electromagnetic high-frequency vibration vertical stage (101), a connecting block (102), and a horizontal slide (103); the table surface of the electromagnetic high-frequency vibration vertical stage (101) is connected to the horizontal slide (103) through the connecting block (102), and the horizontal slide (103) is rigidly connected to the blade clamping unit (2); the high-frequency vibration loading unit (1) also includes a power amplifier and a real-time vibration controller electrically connected to the electromagnetic high-frequency vibration vertical stage (101) for adjusting the vibration frequency, amplitude, and waveform.

[0007] The blade clamping unit (2) includes a blade test piece mounting base (201), a blade locking bolt (202), and a blade locking clamp (203). One end of the blade test piece mounting base (201) is provided with a mortise (207) that matches the tenon of the turbine blade (204) under test, and the other end is provided with an interface for connecting to the horizontal slide (103). The blade locking clamp (203) presses and fixes the turbine blade (204) under test onto the blade test piece mounting base (201) through the blade locking bolt (202). The blade clamping unit (2) has an integrated circulating cooling water channel (206).

[0008] The thermal shock loading unit (3) includes a flame gun (301), a flame gun mounting bracket (302), a three-axis moving platform (303), and a mounting base (304). The flame gun (301) is mounted on the three-axis moving platform (303) via the flame gun mounting bracket (302), and the bottom of the three-axis moving platform (303) is fixedly mounted on the mounting base (304). The gas supply pipeline of the flame gun (301) is equipped with a proportional regulating valve, which is signal-connected to the control unit. The temperature data measured by the temperature measuring unit (4) is fed back to the control unit to dynamically adjust the ratio of gas and auxiliary gas.

[0009] The gas cooling system (6) includes a high-pressure gas source, a mass flow controller, and a cooling nozzle; the high-pressure gas source is used to provide high-pressure nitrogen, and its outlet is connected to the inlet of the mass flow controller through a pipeline; the outlet of the mass flow controller is connected to the cooling nozzle through a pipeline; the nozzle of the cooling nozzle faces the turbine blade (204) under test; the mass flow controller is signal-connected to the control unit and is used to receive control commands and adjust the flow rate of nitrogen flowing through the cooling nozzle, thereby controlling the cooling rate of the turbine blade (204) under test.

[0010] The blade amplitude measurement unit (7) includes a laser displacement sensor (701), a sensor mounting plate (702), an adjustment bracket (703), and a mounting base (705). The laser displacement sensor (701) is fixedly mounted on the sensor mounting plate (702), and the sensor mounting plate (702) is adjustablely mounted on the mounting base (705) via the adjustment bracket (703). The measurement optical path of the laser displacement sensor (701) is aligned with the measurement target on the surface of the turbine blade to be measured.

[0011] The temperature measurement unit (4) is an infrared thermometer, and the infrared thermal imaging unit (5) is an infrared thermal imager; at least one high-temperature strain gauge (205) is attached to the surface of the turbine blade (204) to be tested, and the high-temperature strain gauge (205) is used to monitor the strain of the turbine blade (204) to be tested in real time.

[0012] A method for combined vibration and thermal shock fatigue testing of aero-engine turbine blades based on the aforementioned test apparatus includes the following steps: S1. Develop an experimental plan and determine the vibration parameters, thermal shock parameters, and loading sequence; S2. Install the turbine blade to be tested (204) to the blade clamping unit (2), arrange the high temperature strain gauge (205) and the measurement target, and adjust the position of the thermal shock loading unit (3); S3. Calibrate each measuring device and set vibration and thermal shock loading parameters; S4. Activate the high-frequency vibration loading unit (1) to make the blade test position reach the target stress or strain; S5. Start the thermal shock loading unit (3) to perform transient heating on the blade, and perform closed-loop temperature control based on the feedback from the temperature measurement unit (4); S6. After heating is complete, remove the thermal shock loading unit (3) and start the gas cooling unit (6) to cool the blades; S7. During the test, temperature field, vibration displacement and strain data are collected simultaneously; S8. Repeat steps S5 to S7 to perform cyclic testing until the preset number of cycles is reached or fatigue cracks appear on the blade. S9. Analyze the failed blades and evaluate their fatigue life based on the collected multiphysics data.

[0013] The specific steps of step S5 are as follows: the temperature measurement unit (4) monitors the temperature of the target point on the surface of the turbine blade (204) under test in real time and feeds back the temperature signal to the control unit; the control unit compares the received real-time temperature with the preset target temperature value and generates a control command based on the comparison result; the control command is sent to the gas ratio regulating valve of the thermal shock loading unit (3) to dynamically adjust the mixing ratio of gas and auxiliary gas, so that the flame temperature generated by the flame gun (301) is maintained in the target temperature range.

[0014] The advantages of this invention are as follows: Compared with the prior art, this invention has the following beneficial effects: (1) Using a flame gun as a heat source, it can directly generate high-speed, high-temperature gas jets, which can realistically simulate the impact heating effect of the gas at the outlet of the combustion chamber of an aero-engine on the turbine blades. The transient characteristics of thermal shock and heat flux density are closer to the actual working conditions.

[0015] (2) An electromagnetic high-frequency vibration table is used, which can provide high-frequency vibration with a wide frequency range, large acceleration and diverse waveforms, and can effectively simulate the aerodynamic excitation and mechanical vibration that the blades are subjected to in actual work.

[0016] (3) The infrared thermometer, infrared thermal imager and laser displacement sensor are integrated to realize high spatiotemporal resolution and non-contact real-time monitoring of blade surface temperature (point measurement and surface distribution) and dynamic displacement, providing rich data for analyzing the blade response under combined loads.

[0017] (4) The timing of vibration and thermal shock loading can be set independently or controlled synchronously, which can simulate various complex service load spectra, improving the flexibility and applicability of the test.

[0018] (5) Each system is modularly designed, highly integrated, and easy to install, debug and operate.

[0019] In summary, this invention provides a key technical means for the reliability verification of aero-engine turbine blades under real coupled operating conditions through efficient thermal shock loading achieved by a flame gun, combined with high-frequency vibration excitation and multi-physics field synchronous monitoring, and has significant engineering application value. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the main structure of the present invention.

[0021] Figure 2 yes Figure 1 A schematic diagram of the structure of a medium-to-high frequency vibration loading unit.

[0022] Figure 3 yes Figure 1 A schematic diagram of the structure of the blade clamping unit.

[0023] Figure 4 yes Figure 3 A schematic diagram of the mortise and tenon structure.

[0024] Figure 5 yes Figure 1 Schematic diagram of the thermal shock loading unit structure.

[0025] Figure 6 yes Figure 1 Schematic diagram of the blade amplitude measurement unit. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0027] See Figures 1 to 6This invention relates to a vibration and thermal shock fatigue testing device for aero-engine turbine blades, comprising: a high-frequency vibration loading unit 1, used to apply a high-frequency vibration load with controllable frequency and amplitude to the turbine blade under test; a blade clamping unit 2, connected to the high-frequency vibration loading unit 1, used to fix the turbine blade under test and simulate its real constraint state in the engine; a thermal shock loading unit 3, installed on the side of the blade clamping unit 2, used to generate and spray high-temperature flames toward a target area on the surface of the turbine blade under test to simulate high-speed combustion thermal shock; a gas cooling unit 6, used to spray cooling gas onto the surface of the turbine blade under test to achieve cooling; a temperature measurement unit 4, used to non-contactly measure the temperature at a preset point on the surface of the turbine blade under test in real time; an infrared thermal imaging unit 5, used to acquire an image of the temperature field distribution on the surface of the turbine blade under test; and a blade amplitude measurement unit 7, used to non-contactly measure the vibration displacement on the surface of the turbine blade under test in real time. The high-frequency vibration loading unit 1, thermal shock loading unit 3, gas cooling unit 6, temperature measurement unit 4, infrared thermal imaging unit 5, and blade amplitude measurement unit 7 are all connected to the control unit to achieve the timing control of vibration load, thermal shock load, and cooling process, as well as the synchronous acquisition of data.

[0028] The high-frequency vibration loading unit 1 employs a combination of an electromagnetic high-frequency vibration vertical stage and a horizontal slide stage, and is controlled in a closed loop by a real-time vibration controller. It can generate and transmit vibration loads with frequencies up to several kilohertz, diverse waveforms, and precisely controllable amplitudes. This design overcomes the limitation of low frequencies in traditional test benches and can realistically simulate the high-frequency aerodynamic vibrations experienced by blades during actual operation.

[0029] The blade clamping unit 2 uses a tenon-and-groove structure to match the blade tenon, replicating its actual installation boundary in the engine rotor and ensuring a true stress transmission path. An integrated circulating cooling water channel effectively isolates the high temperatures generated during thermal shock testing, protecting the expensive core components of the high-frequency vibration table and achieving physical decoupling and safe coexistence of the thermal and vibrational environments.

[0030] The thermal shock loading unit 3 uses a flame torch as a heat source, which can generate a high-speed, high-temperature (≥1200℃) gas jet. Its heat flux density and transient heating characteristics are closest to the actual combustion chamber outlet gas environment. Mounted on a three-axis moving platform, it can realize programmed and precise positioning heating of different areas such as the leading edge, blade base, and blade back of the blade, simulating complex thermal load distribution.

[0031] Gas cooling unit 6 uses high-pressure nitrogen as the cooling medium, which is regulated by a mass flow controller to achieve a rapid, uniform, and controllable forced cooling process. This accurately simulates the drastic temperature fluctuations caused by film cooling, internal cooling, and airflow changes in turbine blades during actual operation, a key factor in inducing thermal fatigue.

[0032] Temperature measurement unit 4 and infrared thermal imaging unit 5 intuitively reveal hot spots, temperature gradients and hot spot movement, providing irreplaceable visual data for analyzing thermal stress distribution.

[0033] The blade amplitude measurement unit 7 uses a laser displacement sensor for non-contact, high sampling frequency (≥50kHz) measurement. It can capture the dynamic displacement response of key parts such as the blade tip in real time without interference under harsh test environments with high temperature and strong vibration. It is a key means to obtain the blade vibration mode, resonance frequency and vibration stress level.

[0034] The control unit integrates the signal connections and synchronous control of all the aforementioned loading and measurement units. This allows for precise programming and flexible combination of the application timing, amplitude, and duration of the three core loads—high-frequency vibration, transient heating, and forced cooling—and enables millisecond-level synchronous acquisition of all physical field data, providing a data foundation for studying multi-physics coupling effects.

[0035] In summary, this device is not a simple aggregation of individual unit functions, but rather achieves "realistic load simulation, precise measurement and control methods, and automated testing process" through a systematic and modular integrated design. For the first time in laboratory conditions, three harsh physical processes that occur simultaneously and are coupled together in reality—high-frequency mechanical vibration, transient high-temperature gas impact, and rapid controllable cooling—were integrated and reproduced, creating test conditions that are highly similar to the actual service environment of the blade.

[0036] By integrating multiple advanced non-contact sensors and synchronizing them with a central controller, it can simultaneously acquire multi-dimensional response data such as temperature, strain, and dynamic displacement, and all data have a unified timestamp, making it possible to analyze the vibration-thermal stress coupling mechanism.

[0037] The entire complex composite fatigue test process can be automated through the control unit's program, and the load spectrum can be accurately reproduced, greatly improving the efficiency of the test and the comparability and repeatability of the results.

[0038] This device is designed to address the failure mechanism, life prediction, and reliability verification of aero-engine turbine blades under combined vibration and thermal shock loads.

[0039] The high-frequency vibration loading unit 1 includes an electromagnetic high-frequency vibration vertical stage 101, a connecting block 102, and a horizontal slide 103; the table surface of the electromagnetic high-frequency vibration vertical stage 101 is connected to the horizontal slide 103 through the connecting block 102, and the horizontal slide 103 is rigidly connected to the blade clamping unit 2; the high-frequency vibration loading unit 1 also includes a power amplifier and a real-time vibration controller electrically connected to the electromagnetic high-frequency vibration vertical stage 101, used to adjust the vibration frequency, amplitude, and waveform.

[0040] The electromagnetic high-frequency vibration vertical stage 101 has advantages such as wide frequency range, large acceleration, and small waveform distortion. It drives the horizontal slide 103 to perform lateral vibration motion through the connecting block 102, which is suitable for simulating the aerodynamic vibration environment of turbine blades. The high-frequency vibration loading unit 1 has a maximum excitation frequency of not less than 2kHz, a maximum sinusoidal thrust of not less than 30kN, and a maximum acceleration of not less than 100g. It applies directional vibration load to the blade through the blade clamping unit 2. The vibration frequency, amplitude, and waveform can be precisely adjusted by the vibration controller.

[0041] A high-rigidity, low-loss vibration transmission path was constructed through a series rigid connection design of an electromagnetic high-frequency vibration vertical stage, a connecting block, a horizontal slide, and a blade clamping unit. The horizontal slide, as a key intermediary component, not only ensures the effective transmission of vibration energy from the vertical stage to the blade, but more importantly, it allows for precise adjustment of the blade clamping unit's position and angle in the horizontal plane. This design ensures that the applied high-frequency vibration direction is aligned with the geometric axis of the turbine blade under test or the direction of the preset test vibration mode, thus solving the problem of accurately converting the excitation from the laboratory vibration table into the actual aerodynamic or mechanical vibration experienced by the blade, ensuring the authenticity and accuracy of the mechanical load application during the experiment.

[0042] Using an electromagnetic high-frequency vibration vertical stage as the excitation source, which possesses characteristics of a wide frequency range, large acceleration, and high waveform fidelity, a closed-loop vibration control system is formed by combining it with an electrically connected power amplifier and a real-time vibration controller. This allows researchers to continuously adjust and dynamically control the frequency, amplitude, and waveform of the vibration load applied to the blade with high precision and over a wide range. Therefore, this structure can not only simulate steady-state high-frequency vibration but also reproduce complex vibration spectra under actual working conditions, providing a highly flexible and precisely controllable loading method for studying the fatigue behavior of blades under different vibration characteristics.

[0043] The blade clamping unit 2 includes a blade test piece mounting base 201, a blade locking bolt 202, and a blade locking clamping plate 203. One end of the blade test piece mounting base 201 is provided with a mortise 207 that matches the tenon of the turbine blade 204 under test, and the other end is provided with an interface for connecting to the horizontal slide table 103. The blade locking clamping plate 203 presses and fixes the turbine blade 204 under test onto the blade test piece mounting base 201 by the blade locking bolt 202. The blade clamping unit 2 integrates a circulating cooling water channel 206 inside.

[0044] The blade clamping unit 2 is used to fix the turbine blade 204 to be tested, restore its real constraint state in the engine, and connect it to the platform of the high-frequency vibration loading unit 1 and the action path of the thermal shock loading unit 3; the blade clamping module 2 must have good thermal stability and vibration resistance, and is made of high-temperature resistant alloy material; it integrates a circulating cooling water channel 206 to avoid damage to the high-frequency vibration excitation system due to heat conduction in the high-temperature heating area; The tenon and groove structure replicates the actual mounting interface of the blade in the engine disk, ensuring accurate load transfer path; the rigid locking mechanism ensures connection stiffness during vibration transmission; and the integrated circulating cooling channel effectively isolates the high temperature during thermal shock test from the transmission to the precision vibration table behind, thus enabling the entire device to work stably and reliably under long-term, high-intensity composite loads, resolving the contradiction between test environment simulation and safe equipment operation.

[0045] The blade clamping unit is designed with a mortise and tenon structure 207 that precisely matches the tenon of the blade under test. When the tenon of the blade is inserted into the mortise and tenon, the positioning is achieved, the installation constraint state is restored, and a real transmission path and boundary conditions are provided for the subsequent applied load.

[0046] After the blade is inserted into the tenon, the blade locking clamp 203, under the action of the blade locking bolt 202, firmly presses the blade tenon onto the blade test piece mounting base 201, forming a high-rigidity mechanical connection. This rigid connection ensures that all vibration energy transmitted from the high-frequency vibration loading unit 1 through the horizontal slide 103 can be completely applied to the blade without attenuation or distortion, which is the key to realizing high-frequency vibration fatigue testing.

[0047] When the thermal shock loading unit 3 sprays high-temperature flame onto the leading edge or blade body of the blade, a large amount of heat is conducted to the fixture through the blade tenon. At this time, the circulating cooling water channel 206 integrated inside the fixture starts to work, and the flowing cooling water continuously carries away the heat conducted here, effectively preventing the high temperature from being transferred to the horizontal slide 103 and the electromagnetic high-frequency vibration table 101 connected to the fixture behind, ensuring that these components work stably at room temperature.

[0048] The thermal shock loading unit 3 includes a flame gun 301, a flame gun mounting bracket 302, a three-axis moving platform 303, and a mounting base 304. The flame gun 301 is mounted on the three-axis moving platform 303 via the flame gun mounting bracket 302, and the bottom of the three-axis moving platform 303 is fixedly mounted on the mounting base 304. The gas supply pipeline of the flame gun 301 is equipped with a proportional regulating valve, which is signal-connected to the control unit. The temperature data measured by the temperature measuring unit 4 is fed back to the control unit to dynamically adjust the ratio of gas to auxiliary gas. The thermal shock loading unit 3 generates a high-temperature flame (maximum heating temperature ≥1200℃) by burning high-calorific-value gas (such as natural gas, propane, aviation kerosene), which is directly sprayed onto the target area on the surface of the blade test piece 204 to simulate the high-speed gas thermal shock experienced by the turbine blade. The flame gun 301, as a heat source generating unit, can generate a high-temperature, high-speed gas jet, which is directly sprayed onto the surface of the turbine blade under test to achieve rapid heating and simulate the impact heating effect of the combustion chamber outlet gas on the blade. The three-axis moving platform 303 carries the flame gun through the flame gun mounting bracket 302, which can drive the flame gun 301 to move and position precisely in the X, Y, and Z axes in the spatial rectangular coordinate system to achieve precise thermal shock loading on different areas of the blade (such as the leading edge, trailing edge, blade base, and blade back).

[0049] This thermal shock loading unit integrates triaxial precision positioning and closed-loop feedback temperature control to achieve dual precision in spatial positioning and temperature control for high-temperature thermal shock loading on any target area on the turbine blade surface, thereby simulating the transient thermal shock effect of high-speed combustion gas at the engine combustion chamber outlet with high fidelity.

[0050] The gas cooling system 6 includes a high-pressure gas source, a mass flow controller, and a cooling nozzle. The high-pressure gas source provides high-pressure nitrogen, and its outlet is connected to the inlet of the mass flow controller via a pipeline. The outlet of the mass flow controller is connected to the cooling nozzle via a pipeline. The nozzle orifice of the cooling nozzle faces the turbine blade 204 under test. The mass flow controller is signal-connected to the control unit and is used to receive control commands and adjust the flow rate of nitrogen flowing through the cooling nozzle, thereby controlling the cooling rate of the turbine blade 204 under test.

[0051] The signal connection between the mass flow controller and the control unit allows the flow rate of cooling nitrogen to be adjusted according to a preset program, accurately simulating various real-world cooling scenarios, from film cooling to convection cooling. Using high-pressure nitrogen as the medium, which is an inert gas, avoids side reactions such as oxidation during the cooling process of high-temperature blades. Simultaneously, the optimized cooling nozzle layout ensures uniform coverage of the blade surface by the cooling airflow, preventing additional, unintended thermal stress introduced by uneven local cooling, thus more realistically reflecting the cooling state of the blades in the engine flow field. This solves the problems of uncontrollable and uneven cooling rates, and the inability to precisely coordinate with thermal shock in traditional cooling methods (such as natural cooling or simple air blowing). It is an essential technical means to simulate the rapid, high-intensity, and unsteady-state cooling process experienced by turbine blades in actual operation.

[0052] The blade amplitude measurement unit 7 includes a laser displacement sensor 701, a sensor mounting plate 702, an adjustment bracket 703, and a mounting base 705. The laser displacement sensor 701 is fixedly mounted on the sensor mounting plate 702, and the sensor mounting plate 702 is adjustablely mounted on the mounting base 705 via the adjustment bracket 703. The measurement optical path of the laser displacement sensor 701 is aligned with the measurement target on the surface of the turbine blade under test. The blade amplitude measurement unit 7 is used for high-precision, non-contact, real-time measurement of the dynamic displacement response of the blade under the combined action of vibration and thermal shock, especially the vibration amplitude at the blade tip, thereby indirectly obtaining blade amplitude, frequency, and vibration mode information. Its maximum measurement range is not less than 50 mm, and the sampling frequency is not less than 50 kHz. Through the integrated design of "laser non-contact measurement" and a multi-degree-of-freedom adjustable bracket, high-precision, high-frequency, and interference-free real-time measurement of blade dynamic displacement is achieved in harsh test environments with high temperature and strong vibration, providing key data for analyzing the dynamic response and fatigue mechanism of blades under vibration-thermal shock coupling.

[0053] The temperature measurement unit 4 is an infrared thermometer, and the infrared thermal imaging unit 5 is an infrared thermal imager, which can intuitively display information such as the temperature gradient and hot spot location of the blade during the thermal shock process, so as to facilitate the analysis of thermal stress distribution; at least one high-temperature strain gauge 205 is attached to the surface of the turbine blade 204 under test, and the high-temperature strain gauge 205 is used to monitor the strain of the turbine blade 204 under test in real time.

[0054] The present invention also relates to a method for combined vibration and thermal shock fatigue testing of aero-engine turbine blades based on the aforementioned test apparatus, comprising the following steps: S1. Develop an experimental plan and determine the vibration parameters, thermal shock parameters, and loading sequence; Define the purpose of the test (such as assessing the composite fatigue life of a specific part or studying the failure mechanism), and determine the vibration parameters (frequency, amplitude, waveform, duration), thermal shock parameters (flame temperature, heating time, cooling time, number of cycles), and loading sequence (synchronous / asynchronous relationship between vibration and thermal shock) based on the blade material and expected service conditions. S2. Install the turbine blade 204 to be tested onto the blade clamping unit 2, arrange the high-temperature strain gauge 205 and the measurement target, and adjust the position of the thermal shock loading unit 3; firmly fix the turbine blade test piece to be tested onto the vibration table of the high-frequency vibration excitation system through the blade clamping unit, ensuring that the blade axis is consistent with the vibration direction; adjust the position and angle of the flame gun so that the flame jet is accurately sprayed onto the target heated area of ​​the blade. Attach the high-temperature strain gauge to the blade surface and mark the target of the laser displacement sensor at the blade position; S3. Calibrate each measuring device and set vibration and thermal shock loading parameters; calibrate the temperature measuring device, infrared thermal imaging device and blade amplitude measuring device; set the vibration parameters of the high-frequency vibration loading system; set the parameters of the thermal shock loading system to obtain the required flame temperature and thermal shock cycle time. S4. Start the high-frequency vibration loading unit 1 and continuously adjust the frequency and amplitude of the high-frequency vibration loading unit so that the blade test position reaches the target stress or strain. S5. Start the thermal shock loading unit 3 to transiently heat the blade and perform closed-loop temperature control based on the feedback from the temperature measurement unit 4; generate a high-temperature flame through gas combustion to transiently heat the test blade, while using a temperature measurement device to monitor the blade surface temperature in real time and feed the temperature data back to the high-temperature flame heating unit to form a closed-loop control to accurately reach the target temperature. S6. After heating is complete, remove the thermal shock loading unit 3 and start the gas cooling unit 6 to cool the blade; when the blade heating time is complete, the three-axis moving platform moves the flame gun to the next target position according to the PLC automatic program, where the blade will not be heated; at the same time, start the airflow cooling unit and adjust the flow rate of high-pressure nitrogen through the mass flow controller to cool the test blade uniformly and quickly. S7. During the test, temperature field, vibration displacement and strain data are collected simultaneously; the infrared thermal imaging unit captures information such as temperature field distribution and hot spot location on the blade surface in real time; the blade amplitude measurement unit measures data such as blade vibration displacement in real time; and the high-temperature strain gauge monitors the strain and stress at the blade test location in real time. S8. Repeat steps S5 to S7 to perform cyclic testing until the preset number of cycles is reached or fatigue cracks appear on the blade. S9. Analyze the failed blade and evaluate its fatigue life using the collected multiphysics data. After the blade cools down, carefully disassemble it; perform macroscopic observation (crack location, length, morphology) and microscopic analysis (such as scanning electron microscopy (SEM) to observe the fracture morphology and metallographic analysis of the microstructure) on the failed blade to determine its main failure modes and failure mechanisms; organize and analyze the collected multiphysics data, including vibration characteristics, temperature field evolution, dynamic strain response, displacement response, and the relationship between vibration and thermal stress, etc., plot temperature-time curves, strain-time curves, and displacement-time curves, and perform spectral analysis; based on the experimental data and failure analysis results, evaluate the fatigue life of the blade under a given vibration-thermal shock combined load to verify the rationality of the blade design.

[0055] Step S5 specifically involves: the temperature measurement unit 4 monitoring the temperature of the target point on the surface of the turbine blade 204 under test in real time and feeding the temperature signal back to the control unit; the control unit comparing the received real-time temperature with the preset target temperature value and generating a control command based on the comparison result; the control command being sent to the gas proportion regulating valve of the thermal shock loading unit 3 to dynamically adjust the mixing ratio of gas and auxiliary gas, thereby maintaining the flame temperature generated by the flame gun 301 within the target temperature range.

[0056] This method achieves its systematic nature, precision, and engineering applicability through the interconnectedness of its steps. Specifically: 1. Steps S1-S3: The test begins with the precise design of the load spectrum (S1), which involves determining the vibration and thermal shock parameters and their complex temporal relationships based on actual service conditions. This ensures that the test targets the actual physical processes from the outset. Subsequently, through tenon-groove installation and sensor placement (S2), the true boundaries are reconstructed and a full-field monitoring network is built. Then, system calibration and parameter setting (S3) lay the foundation for subsequent precise control. These three preparatory steps constitute a standardized pre-test procedure, ensuring the repeatability and comparability of test conditions and enhancing the engineering reference value of the results from the outset.

[0057] 2. Step S4 first applies a precise high-frequency vibration load to the target strain independently; Step S5 then superimposes a transient thermal shock based on real-time temperature feedback closed-loop control on the vibration; Step S6 then performs programmed rapid cooling with controllable flow rate.

[0058] Step S8 automatically cycles the aforementioned coupled load units until a preset number of life cycles is reached or fatigue crack initiation is detected in real time through monitoring data such as strain abrupt changes or abnormal vibration characteristics. This enables long-term, high-intensity automated testing and can pinpoint the exact failure initiation point.

[0059] Step S7: During the entire loading process from Step S5 to Step S8, multi-physics data such as temperature field infrared thermography, dynamic displacement laser vibration measurement, and local strain high-temperature strain gauge are collected synchronously and continuously, forming a massive dataset with time alignment.

[0060] Step S9: After failure, the crack initiation and propagation mode are determined by combining macroscopic and microscopic fracture surface analysis of the blade, and correlation analysis is performed with the multiphysics process data mentioned above. For example, the thermal cycling history at a specific location before crack initiation, the correspondence between vibration stress amplitude and temperature field, etc., can be analyzed, which greatly improves the reliability of the life prediction model.

[0061] This method not only simulates real working conditions, but also enables the visualization of composite fatigue failure mechanisms and verifiable assessment of lifespan through precise control throughout the entire process and synchronization of multi-dimensional data, providing a reliable verification method for blade design and material development.

[0062] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A test apparatus for vibration and thermal shock fatigue of aero-engine turbine blades, characterized in that, include: A high-frequency vibration loading unit (1) is used to apply a high-frequency vibration load with controllable frequency and amplitude to the turbine blade under test. The blade clamping unit (2) is connected to the high-frequency vibration loading unit (1) and is used to fix the turbine blade under test and simulate its real constraint state in the engine. A thermal shock loading unit (3) is installed on the side of the blade clamping unit (2) to generate and spray high-temperature flames toward the target area on the surface of the turbine blade under test to simulate high-speed gas thermal shock. Gas cooling unit (6) is used to spray cooling gas onto the surface of the turbine blade under test to achieve cooling; Temperature measurement unit (4) is used for non-contact real-time measurement of the temperature at a preset point on the surface of the turbine blade under test; Infrared thermal imaging unit (5) is used to acquire the temperature field distribution image of the surface of the turbine blade under test; The blade amplitude measurement unit (7) is used for non-contact real-time measurement of the vibration displacement of the surface of the turbine blade under test; Among them, the high-frequency vibration loading unit (1), thermal shock loading unit (3), gas cooling unit (6), temperature measurement unit (4), infrared thermal imaging unit (5) and blade amplitude measurement unit (7) are all connected to the control unit to realize the timing control of vibration load, thermal shock load, cooling process and synchronous data acquisition.

2. The aero-engine turbine blade vibration and thermal shock fatigue testing apparatus according to claim 1, characterized in that, The high-frequency vibration loading unit (1) includes an electromagnetic high-frequency vibration vertical stage (101), a connecting block (102), and a horizontal slide (103); the table surface of the electromagnetic high-frequency vibration vertical stage (101) is connected to the horizontal slide (103) through the connecting block (102), and the horizontal slide (103) is rigidly connected to the blade clamping unit (2); the high-frequency vibration loading unit (1) also includes a power amplifier and a real-time vibration controller electrically connected to the electromagnetic high-frequency vibration vertical stage (101) for adjusting the vibration frequency, amplitude, and waveform.

3. The aero-engine turbine blade vibration and thermal shock fatigue testing apparatus according to claim 2, characterized in that, The blade clamping unit (2) includes a blade test piece mounting base (201), a blade locking bolt (202), and a blade locking clamp (203). One end of the blade test piece mounting base (201) is provided with a mortise (207) that matches the tenon of the turbine blade (204) under test, and the other end is provided with an interface for connecting to the horizontal slide (103). The blade locking clamp (203) presses and fixes the turbine blade (204) under test onto the blade test piece mounting base (201) through the blade locking bolt (202). The blade clamping unit (2) has an integrated circulating cooling water channel (206).

4. The aero-engine turbine blade vibration and thermal shock fatigue testing apparatus according to claim 2 or 3, characterized in that, The thermal shock loading unit (3) includes a flame gun (301), a flame gun mounting bracket (302), a three-axis moving platform (303), and a mounting base (304). The flame gun (301) is mounted on the three-axis moving platform (303) via the flame gun mounting bracket (302), and the bottom of the three-axis moving platform (303) is fixedly mounted on the mounting base (304). The gas supply pipeline of the flame gun (301) is equipped with a proportional regulating valve, which is signal-connected to the control unit. The temperature data measured by the temperature measuring unit (4) is fed back to the control unit to dynamically adjust the ratio of gas and auxiliary gas.

5. The aero-engine turbine blade vibration and thermal shock fatigue testing apparatus according to claim 4, characterized in that, The gas cooling system (6) includes a high-pressure gas source, a mass flow controller, and a cooling nozzle; the high-pressure gas source is used to provide high-pressure nitrogen, and its outlet is connected to the inlet of the mass flow controller through a pipeline; the outlet of the mass flow controller is connected to the cooling nozzle through a pipeline; the nozzle of the cooling nozzle faces the turbine blade (204) under test; the mass flow controller is signal-connected to the control unit and is used to receive control commands and adjust the flow rate of nitrogen flowing through the cooling nozzle, thereby controlling the cooling rate of the turbine blade (204) under test.

6. The aero-engine turbine blade vibration and thermal shock fatigue testing apparatus according to claim 5, characterized in that, The blade amplitude measurement unit (7) includes a laser displacement sensor (701), a sensor mounting plate (702), an adjustment bracket (703), and a mounting base (705). The laser displacement sensor (701) is fixedly mounted on the sensor mounting plate (702), and the sensor mounting plate (702) is adjustablely mounted on the mounting base (705) via the adjustment bracket (703). The measurement optical path of the laser displacement sensor (701) is aligned with the measurement target on the surface of the turbine blade to be measured.

7. The aero-engine turbine blade vibration and thermal shock fatigue testing apparatus according to claim 1, characterized in that, The temperature measurement unit (4) is an infrared thermometer, and the infrared thermal imaging unit (5) is an infrared thermal imager; at least one high-temperature strain gauge (205) is attached to the surface of the turbine blade (204) to be tested, and the high-temperature strain gauge (205) is used to monitor the strain of the turbine blade (204) to be tested in real time.

8. A method for combined vibration and thermal shock fatigue testing of aero-engine turbine blades based on the test apparatus described in any one of claims 1 and 7, characterized in that, Includes the following steps: S1. Develop an experimental plan and determine the vibration parameters, thermal shock parameters, and loading sequence; S2. Install the turbine blade to be tested (204) to the blade clamping unit (2), arrange the high temperature strain gauge (205) and the measurement target, and adjust the position of the thermal shock loading unit (3); S3. Calibrate each measuring device and set vibration and thermal shock loading parameters; S4. Activate the high-frequency vibration loading unit (1) to make the blade test position reach the target stress or strain; S5. Start the thermal shock loading unit (3) to perform transient heating on the blade, and perform closed-loop temperature control based on the feedback from the temperature measurement unit (4); S6. After heating is complete, remove the thermal shock loading unit (3) and start the gas cooling unit (6) to cool the blades; S7. During the test, temperature field, vibration displacement and strain data are collected simultaneously; S8. Repeat steps S5 to S7 to perform cyclic testing until the preset number of cycles is reached or fatigue cracks appear on the blade. S9. Analyze the failed blades and evaluate their fatigue life based on the collected multiphysics data.

9. The test method according to claim 8, characterized in that, The specific steps of step S5 are as follows: The temperature measurement unit (4) monitors the temperature of the target point on the surface of the turbine blade (204) in real time and feeds back the temperature signal to the control unit; The control unit compares the received real-time temperature with the preset target temperature value and generates control commands based on the comparison result. The control command is sent to the gas ratio regulating valve of the thermal shock loading unit (3) to dynamically adjust the mixing ratio of gas and auxiliary gas, so that the flame temperature generated by the flame gun (301) is maintained in the target temperature range.

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