Multi-axis multi-field coupling fatigue test device

Abstract

The invention discloses a multi-axis multi-field coupling fatigue test device, and belongs to the technical field of material testing. The device comprises a rack, a multi-axis loading unit, an environment simulation unit, a dynamic sealing interface and a cooperative control system. The core of the device is that the test sample can simultaneously bear the coupling effect of multi-axis mechanical stress (pulling, pressing and twisting) and various environmental fields (such as high and low temperatures, corrosive media, illumination and electric fields) through a highly integrated design; and the dynamic sealing problem of the actuator rod in the environment box is solved through an innovative dynamic sealing interface (such as labyrinth-magnetofluid composite sealing). According to the invention, accurate linkage control of multiple channels is realized through the cooperative control system, the service environment of key parts under actual complex working conditions can be truly simulated, and a reliable test platform is provided for failure analysis and life prediction of products under multi-field coupling.

Description

Technical Field

[0001] This invention relates to the field of mechanical property testing technology for materials and structural components, and specifically to a multi-axis, multi-field coupled fatigue testing device. Background Technology

[0002] Many critical engineering components, such as aero-engine blades, vehicle chassis axles, and bio-implants like artificial joints, not only endure complex alternating mechanical loads in multiple directions (tension, compression, torsion, and bending) during their service life, but also operate in harsh environments with multiple coupled fields, including high and low temperatures, corrosive media, light, and electric fields. Traditional material fatigue testing machines have limited functionality, mostly performing uniaxial loading (such as simple tension or torsion), and environmental simulation is usually separated from mechanical loading, making it impossible to accurately reproduce the failure mechanisms and fatigue life of components under actual working conditions.

[0003] The main bottlenecks in current technology are: 1) the difficulty in integrating a multi-axis loading system and a complex environment simulation system within a compact space; and 2) particularly critically, how to achieve a dynamic and reliable seal between the actuator rod and the environmental chamber to prevent leakage of the media inside the chamber (such as corrosive liquids and high-pressure gases) and maintain the stability of environmental parameters when the actuator rod needs to reciprocate at high speeds, is a long-standing technical problem that has not been well solved. This results in low confidence levels in test results, making it impossible to provide effective data support for the design and safety assessment of high-reliability equipment.

[0004] Therefore, there is an urgent need for a new type of experimental device that can highly integrate multi-axis mechanical loading and multi-physics environment and achieve precise and coordinated control. Summary of the Invention

[0005] To achieve the above objectives, the present invention aims to provide a multi-axis, multi-field coupled fatigue testing device, comprising: The rigid frame forms the basic support structure for the entire device. A multi-axis loading unit is fixed on the frame. The multi-axis loading unit includes at least one axial servo actuator and one torque servo actuator. The actuator rod of the axial servo actuator is arranged coaxially with the main shaft of the torque servo actuator. It is used to apply axial tensile and compressive loads and torsional loads around the axis to the specimen connected to its end, forming a multi-axis composite stress state. The environmental simulation unit includes a sealed environmental chamber that surrounds the sample and part of the loading rod system. The environmental chamber contains: The temperature control module is used to regulate the temperature inside the chamber. The media management module is used to introduce, maintain, and circulate environmental media into the enclosure; and at least one of the following: a light-emitting component or an electric field-applying electrode; A dynamic sealing interface is integrated into the opening of the environmental chamber wall. The actuator rod of the multi-axis loading unit passes through the interface and can reciprocate and rotate therein. The dynamic sealing interface is configured to maintain the airtightness of the environmental chamber when the actuator rod moves, prevent internal media leakage, and maintain internal pressure. The collaborative control system is electrically connected to each servo actuator of the multi-axis loading unit and each subsystem of the environmental simulation unit. The collaborative control system is programmed to generate and send synchronous control commands to execute predefined mechanical loading spectra and environmental field change spectra to realize multi-field coupling experiments.

[0006] Preferably, the dynamic sealing interface is a multi-stage composite sealing structure, comprising, from the outside to the inside, the following along the radial direction of the actuator rod: At least one static sealing ring is used to achieve a static seal between the interface and the enclosure wall; At least two levels of labyrinth sealing rings, with tortuous leakage paths formed between each level of labyrinth sealing rings; At least one magnetohydrodynamic seal is located on the innermost side. It generates a magnetic field through an excitation coil to fix the magnetohydrodynamic fluid around the actuator rod to form a dynamic sealing ring.

[0007] Preferably, the media management module includes: Medium storage tanks are used to store liquid or gaseous media. A circulating pump is connected to the medium storage tank and the injection port located on the environmental chamber via a pipeline. A filter, connected to the pipeline, is used to filter the circulating medium; Flow meters and electrically controlled valves are used to monitor and control the flow rate of media entering the environmental chamber; The recovery port is located at the bottom of the environmental chamber, and the medium is guided back to the medium storage tank through the return pipeline to form a closed loop system.

[0008] Preferably, the temperature control module includes: Flexible silicone heating film attached to the inner wall of the environmental chamber; A liquid nitrogen injection nozzle that penetrates the wall of the environmental chamber is connected to an external liquid nitrogen source and is controlled to open and close by a solenoid valve. At least one PT100 platinum resistance temperature sensor is inserted into the environmental chamber to monitor the temperature; The collaborative control system receives temperature sensor signals and uses a PID algorithm to control the heating film power and the opening and closing of the liquid nitrogen solenoid valve, thereby achieving temperature control within the environmental chamber ranging from -70℃ to +300℃.

[0009] Preferably, it also includes a mechanical sensor and an environmental sensor; the mechanical sensor is mounted on the specimen or the loading unit and is used to measure the load, displacement or strain of the specimen; The environmental sensor is installed inside the environmental chamber and is used to monitor temperature, medium flow rate, or medium concentration.

[0010] Preferably, the hardware of the collaborative control system includes a multi-channel servo controller and a PLC controller. The multi-channel servo controller is responsible for controlling each servo actuator, and the PLC controller is responsible for controlling each subsystem of the environmental simulation unit. The two communicate with each other via Ethernet. The software of the cooperative control system integrates a coupled feedback control algorithm, which is configured as follows: Real-time acquisition of mechanical signals such as load, displacement, and strain from mechanical sensors, and environmental signals such as temperature and medium flow rate from environmental sensors; The signal is compared with a preset test spectrum, and the next output is predicted based on the built-in coupling model (such as a model of the effect of temperature on the elastic modulus of the material). The control commands sent to the servo actuators and environmental subsystems are dynamically adjusted to achieve real-time, closed-loop coupled control of mechanical loads and environmental parameters.

[0011] Preferably, the coupled feedback control algorithm is the Model Predictive Control (MPC) algorithm.

[0012] Preferably, it also includes a set of universal clamps or special clamps, which are made of corrosion-resistant high-temperature alloy material. One end of the clamps is connected to the spindle of the torque servo actuator, and the other end is provided with a clamping part for clamping the sample. The entire clamps are placed inside the environmental chamber.

[0013] Preferably, the environment simulation unit further includes: Ultraviolet LED lamps or xenon lamps are installed on the inner wall of the environmental chamber to simulate a light environment; And / or, at least one pair of insulating electrodes, symmetrically mounted on both sides of the sample, connected to an external high-voltage power supply, are used to create an electric field around the sample.

[0014] This invention provides an improved multi-axis, multi-field coupled fatigue testing device, which has the following improvements and advantages compared with the prior art: High integration and powerful functions: For the first time, a single device has achieved the synchronous application and coordinated control of multi-axis mechanical loads and multiple environmental fields (heat, medium, light, electricity, etc.), greatly expanding the functional boundaries of the testing machine.

[0015] Breakthrough in technical bottlenecks: The innovative dynamic sealing interface design, especially the labyrinth-magnetic fluid composite sealing structure, successfully solved the leakage problem of the actuator rod during reciprocating motion in a harsh environment. The high technical difficulty in implementation is the key to the realization of this invention.

[0016] High simulation realism: It can accurately reproduce the complex working conditions of key components in actual operation, obtain more realistic material failure data and fatigue life, and provide a solid foundation for product design and reliability assessment.

[0017] Intelligent control: Through a collaborative control system and advanced coupling feedback algorithm, it can execute complex multi-field coupled test spectra with a high degree of automation and good test repeatability. Attached Figure Description

[0018] Figure 1 This is a three-dimensional schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic cross-sectional view of the overall structure of the present invention; Figure 3 This is a partial structural schematic diagram of the present invention; Figure 4 for Figure 3 Enlarged view of point A in the image; Figure 5 This is a system framework diagram of the present invention.

[0019] In the diagram: 1. Frame; 2. Axial servo actuator; 3. Torque servo actuator; 4. Environmental chamber; 5. Dynamic sealing interface; 501. Static sealing ring; 502. Sealing ring; 503. Magnetohydrodynamic seal; 6. Inlet; 7. Outlet; 8. Clamp; 9. Medium storage tank; 901. Circulating pump; 902. Filter; 903. Flow meter; 904. Electrically controlled valve; 10. End clamp. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] See Figure 1-5 Example 1: This embodiment provides a specific implementation method for testing the fatigue performance of aerospace titanium alloy blade materials under multi-field coupling.

[0025] The frame 1 adopts a four-column high-strength cast steel frame to ensure extremely high rigidity under maximum load. The multi-axis loading unit includes an axial servo actuator 2 with a maximum load of ±100kN and a torque servo actuator 3 with a maximum torque of ±1000Nm, which are coaxially connected together by a flange.

[0026] Environmental chamber 4 is welded from 316L stainless steel and has an internal volume of approximately 50 liters. The chamber is designed with observation windows and lead-in holes. In this example, the environmental field is "high temperature + salt spray corrosion". Therefore, the temperature control module combines a tubular heater embedded in the chamber wall with a liquid nitrogen spray system, enabling rapid heating and active cooling from room temperature to 300°C. The media management module uses a 5% sodium chloride solution as the corrosive medium. The solution is pumped from the storage tank via a magnetic circulation pump 901, converted into salt spray by an ultrasonic atomizer, and sprayed into environmental chamber 4 through inlet 6 to simulate a marine atmospheric environment. Excess mist condenses on the chamber wall and flows back to the storage tank through the bottom recovery port, where it is filtered and recycled.

[0027] The dynamic sealing interface is key to this embodiment. Since the actuator rod needs to simultaneously perform high-speed axial reciprocating and rotational movements, sealing is extremely difficult. This invention employs a three-stage sealing combination: the outermost layer is a high-temperature resistant O-ring 501 for static sealing; the middle layer consists of two stainless steel labyrinth sealing rings 502, with the minimal gap between the rings and the rod forming a tortuous channel to effectively dissipate medium pressure; the innermost layer is a set of dual-stage magnetohydrodynamic seals 503, to which direct current is supplied to the excitation coil, adsorbing and forming two stable liquid magnetohydrodynamic sealing rings on the surface of the rotating rod, completely eliminating salt spray leakage and exhibiting extremely low frictional resistance.

[0028] The collaborative control system uses an industrial PC as the host computer, running test management software. Users can program complex test patterns, such as "at 300℃, maintaining an average axial load of 20kN and an average torque load of 200Nm, while applying sinusoidal loads of ±10kN axial load and ±100Nm torque load in phase, and continuously spraying salt spray." The slave computer consists of a multi-channel servo controller and a PLC. The servo controller controls the actuators to complete the mechanical loading, while the PLC controls the operation of the heater, liquid nitrogen valve, and atomizer according to a preset program and control algorithm, and maintains millisecond-level synchronization with the servo controller via the Modbus-TCP protocol to ensure precise coupling between the load and the environment.

[0029] The fixture 8 is a special rod-shaped sample fixture made of GH4169 high-temperature alloy. It is connected to the main shaft of the torque actuator by threads. The front end uses a hydraulic chuck to hold a standard cylindrical fatigue sample, and the rear end is wrapped by the end clamp 10 to restrict the rotation of the cylinder while enabling the cylinder to move axially. During the axial reciprocating movement, the end clamp 10 will generate frictional loss on the circumferential movement of the cylinder.

[0030] Example 2: This embodiment provides an implementation method for testing the durability of photovoltaic support materials under the conditions of "humid heat + ultraviolet radiation + mechanical vibration".

[0031] Its basic structure is the same as in Example 1, with the main difference being the environmental simulation unit. In this example, multiple sets of ultraviolet LED light panels are installed on the inner wall of the environmental chamber 4 to simulate solar ultraviolet radiation. The media management module heats deionized water to generate water vapor, which is then mixed with heated air and introduced into the environmental chamber to maintain a constant humid and hot environment of 85°C and 85% relative humidity. The multi-axis loading unit mainly applies small-amplitude, high-frequency axial tensile and compressive loads to simulate wind-induced vibration.

[0032] The collaborative control system needs to synchronously control the frequency, amplitude, and temperature and humidity stability of the vibration load. Its coupled feedback algorithm monitors the temperature and humidity inside the chamber in real time and precisely adjusts them by controlling the power of the steam generator and the opening of the air inlet valve to ensure that environmental conditions do not drift during vibration.

[0033] As can be seen from the above two embodiments, the device of the present invention, through modular design, can be flexibly configured with different combinations of environmental fields and mechanical loads, has a wide range of applications, and effectively solves the technical problem of simulating complex working conditions.

[0034] The foregoing description enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-axis, multi-field coupled fatigue testing device, characterized in that, include: The rigid frame (1) forms the basic support structure of the entire device; A multi-axis loading unit is fixed on the frame (1). The multi-axis loading unit includes at least one axial servo actuator (2) and a torque servo actuator (3). The actuator rod of the axial servo actuator (2) is arranged coaxially with the main shaft of the torque servo actuator (3) to apply axial tensile and compressive loads and torsional loads around the axis to the specimen connected to its end, forming a multi-axis composite stress state. The environmental simulation unit includes a sealed environmental chamber (4), which surrounds the sample and part of the loading rod system. The environmental chamber (4) contains: The temperature control module is used to regulate the temperature inside the chamber. The media management module is used to introduce, maintain, and circulate environmental media into the enclosure; and at least one of the following: a light-emitting component or an electric field-applying electrode; A dynamic sealing interface (5) is integrated into the opening of the wall of the environmental chamber (4). The actuator rod of the multi-axis loading unit passes through the interface and can reciprocate and rotate therein. The dynamic sealing interface (5) is configured to maintain the sealing of the environmental chamber (4) when the actuator rod moves, prevent internal media leakage and maintain internal pressure. The collaborative control system is electrically connected to each servo actuator of the multi-axis loading unit and each subsystem of the environmental simulation unit. The collaborative control system is programmed to generate and send synchronous control commands to execute predefined mechanical loading spectra and environmental field change spectra to realize multi-field coupling experiments.

2. The multi-axis multi-field coupled fatigue testing device according to claim 1, characterized in that, The dynamic sealing interface (5) is a multi-stage composite sealing structure, which includes the following components from the outside to the inside along the radial direction of the actuator rod: At least one static sealing ring (501) is used to achieve a static seal between the interface and the box wall; At least two levels of labyrinth sealing rings (502) are provided, and tortuous leakage paths are formed between each level of labyrinth sealing rings (502); At least one magnetohydrodynamic seal (503) is located on the innermost side. It generates a magnetic field through an excitation coil to fix the magnetohydrodynamic fluid around the actuator rod to form a dynamic sealing ring.

3. The multi-axis multi-field coupled fatigue testing device according to claim 1, characterized in that, The media management module includes: Medium storage tank (9) is used to store liquid or gaseous environmental media; A circulating pump (901) is connected to the medium storage tank (9) and the injection port (6) provided on the environmental box (4) via a pipeline. Filter (902), connected to the pipeline, is used to filter the circulating medium; A flow meter (903) and an electrically controlled valve (904) are used to monitor and control the flow rate of the medium into the environmental chamber (4); The recovery port (7) is located at the bottom of the environmental box (4) and the medium is guided back to the medium storage tank (9) through the return pipeline to form a closed loop system.

4. The multi-axis multi-field coupled fatigue testing device according to claim 1, characterized in that, The temperature control module includes: Flexible silicone heating film attached to the inner wall of the environmental chamber (4); A liquid nitrogen injection nozzle that penetrates the wall of the environmental chamber (4) is connected to an external liquid nitrogen source and is controlled to open and close by a solenoid valve; At least one PT100 platinum resistance temperature sensor is inserted into the environmental chamber (4) to monitor the temperature; The collaborative control system receives temperature sensor signals and uses a PID algorithm to control the heating film power and the opening and closing of the liquid nitrogen solenoid valve, thereby achieving temperature control within the environmental chamber ranging from -70℃ to +300℃.

5. The multi-axis multi-field coupled fatigue testing device according to claim 1, characterized in that, It also includes mechanical sensors and environmental sensors; the mechanical sensors are mounted on the specimen or the loading unit and are used to measure the load, displacement or strain of the specimen. The environmental sensor is installed inside the environmental chamber (4) and is used to monitor temperature, medium flow rate or medium concentration.

6. The multi-axis multi-field coupled fatigue testing device according to claim 1, characterized in that, The hardware of the collaborative control system includes a multi-channel servo controller and a PLC controller. The multi-channel servo controller is responsible for controlling each servo actuator, and the PLC controller is responsible for controlling each subsystem of the environmental simulation unit. The two communicate with each other via Ethernet. The software of the cooperative control system integrates a coupled feedback control algorithm, which is configured as follows: Real-time acquisition of mechanical signals (load, displacement, strain) from mechanical sensors and environmental signals (temperature, medium flow rate) from environmental sensors; The signal is compared with a preset test spectrum, and the next output is predicted based on the built-in coupling model (such as a model of the effect of temperature on the elastic modulus of the material). The control commands sent to the servo actuators and environmental subsystems are dynamically adjusted to achieve real-time, closed-loop coupled control of mechanical loads and environmental parameters.

7. The multi-axis multi-field coupled fatigue testing device according to claim 6, characterized in that, The coupled feedback control algorithm is a model predictive control (MPC) algorithm.

8. The multi-axis multi-field coupled fatigue testing device according to claim 1, characterized in that, It also includes a set of universal clamps or special clamps (8), which are made of corrosion-resistant high-temperature alloy material. One end of the clamp is connected to the spindle of the torque servo actuator (3), and the other end is provided with a clamping part for clamping the sample. The clamp (8) is placed inside the environmental chamber (4).

9. The multi-axis multi-field coupled fatigue testing device according to claim 1, characterized in that, The environment simulation unit also includes: Ultraviolet LED lamps or xenon lamps are installed on the inner wall of the environmental chamber (4) to simulate the lighting environment; And / or, at least one pair of insulating electrodes, symmetrically mounted on both sides of the sample, connected to an external high-voltage power supply, are used to create an electric field around the sample.

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