Axle fatigue test bench testing device, system and method

Abstract

The invention discloses an axle fatigue test bench testing device, system and method. The device comprises a counter-force seat, a loading mechanism, a gate-type support, an axle body supporting seat and an axle fixing assembly. One end of the loading mechanism is connected with the counter-force seat, and the other end is connected with the bridge body supporting seat through the gate-type bracket; the axle fixing assembly adopts a rigid base with topological optimization and a cover plate with a flexible liner to form a rigid-flexible coupling clamp; the loading mechanism comprises a transverse servo actuator and a vertical servo actuator which are spatially and orthogonally distributed, and multi-directional combined load application can be achieved. The system comprises a management layer, a control layer and an execution layer, closed-loop control is formed, and accurate reproduction of a load spectrum and self-adaptive matching of clamping force are achieved. The method comprises the steps of setting preparation, rigid-flexible coupling constraint establishment, closed-loop loading and real-time monitoring execution, data analysis and evaluation and the like. According to the invention, the problems of constraint boundary distortion and single loading mode in the traditional test are solved, and the high-fidelity laboratory reproduction of the complex fatigue failure mechanism of the axle is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of axle fatigue testing, in particular to an axle fatigue test bench testing device, system and method. BACKGROUND

[0002] In the existing technical field of axle fatigue testing, traditional test devices mostly adopt radial loading or axial torsion loading modes, and the fixture design generally has the defects of single constraint form and boundary condition simulation distortion. The typical scheme realizes bridge shell positioning by V-shaped support combined with bolt pressure plate, which is easy to introduce abnormal stress concentration in the clamping area, and cannot accurately reproduce the multi-degree-of-freedom coupling constraint state of the bridge body end and the suspension system during vehicle driving; the transverse loading mechanism often relies on single-actuator push-pull structure or eccentric wheel mechanism, resulting in single load direction and delayed frequency response, making it difficult to generate complex alternating transverse excitation in accordance with actual working conditions.

[0003] In the current axle fatigue test device, one representative scheme is disclosed in the patent document with publication number CN213985715U, which integrates hydraulic drive, V-shaped support block and hinged clamping structure with shock absorber, and can realize efficient cooperative fixation of non-driving steering front axle and driving steering front axle of the axle. The shock absorber design can effectively buffer the dynamic impact during the test process, and the hinged clamping jaw cooperates with the locking piece to enhance the adaptability of the clamping system, significantly improving the test stability and operation convenience. However, this scheme relies heavily on the mechanical strength of the clamping jaw hinge point and the long-term fatigue resistance of the locking piece. Under high-frequency testing, wear of the key connecting parts may cause clamping force attenuation or positioning inaccuracy, and the overall structure still needs further verification in terms of adaptability to more complex axle configurations, integration of intelligent monitoring modules, etc.

[0004] Another representative scheme is disclosed in the patent document with publication number CN220120373U, which improves the applicability of the equipment through innovative design of the adjustable down pressure assembly. The assembly includes a moving plate, a sliding groove, a moving block and a clamping mechanism, effectively solving the problem of insufficient adaptability of existing technology to different height axles, significantly improving the versatility and testing convenience of the device for different specifications of axles, and especially accurately adjusting the down limit position of the down pressure block to adapt to the height difference, ensuring the effective application of the knocking load in the fatigue test. However, this scheme relies on mechanical adjustment of the sliding block and clamping mechanism, which may cause a decrease in positioning accuracy or damage to stability due to mechanical wear over a long period of frequent use. The manual adjustment process may also introduce an operational efficiency bottleneck, and further engineering optimization is needed in terms of structural durability, long-term reliability and operational convenience.

[0005] The technical evolution of the existing axle fatigue test device mainly develops along the above two paths. Although the two schemes have their own breakthroughs, they have not effectively solved the following technical defects. From the perspective of constraint simulation, the mainstream scheme relies on V-shaped support blocks combined with bolt pressure plates or damping hinged clamping structures. Although it can achieve foundation positioning, it cannot accurately simulate the three-dimensional dynamic coupling boundary of the bridge body end and the suspension system, resulting in abnormal stress concentration in the clamping area, and the mechanical wear of the hinged clamping jaw will cause the clamping force to decay and the positioning to drift during long-term testing. From the perspective of load loading, the traditional radial and axial loading mechanisms and height-adjustable down pressure assemblies can only load in a single direction, making it difficult to generate complex alternating excitation in the spatial orthogonal vector plane and unable to reproduce the load spectrum characteristics of multi-directional random impact in vehicle driving, causing the laboratory working condition to be disconnected from the actual failure mode. And from the perspective of structural adaptability, the mechanical adjustment type adaptive structure improves the universality of the axle specifications, but frequent adjustment can easily lead to a decrease in positioning accuracy, and the overall architecture lacks flexible interfaces for integrated intelligent monitoring and multi-degree-of-freedom collaborative control.

[0006] The above defects together make it difficult for the traditional test bench to accurately reproduce the fatigue failure mechanism of the axle under complex multi-directional dynamic loads throughout its life cycle in the laboratory, severely restricting the engineering effectiveness of axle reliability evaluation, and highlighting the obvious shortcomings of existing technology in simulating the real constraint boundary at the end of the axle and the ability to load multi-directional composite loads. SUMMARY

[0007] The purpose of the present application is to provide an axle fatigue test bench testing device that can solve the problem of existing axle fatigue test devices in the simulation of the constraint boundary at the end of the bridge body, the lack of multi-directional composite load loading capability, and the inability to accurately reproduce the fatigue failure mechanism of the axle under complex loads.

[0008] In order to solve the above problems, the technical scheme adopted by the present application is: the axle fatigue test bench testing device comprises a counterforce seat, a loading mechanism, a portal frame, an axle body support seat, and an axle fixing assembly; one end of the loading mechanism is fixedly connected with the counterforce seat, the other end of the loading mechanism passes through the portal frame and is connected with the axle body support seat, the axle body support seat is provided with an axle end positioning hole for passing and mounting an axle body shaft end of an axle test piece, the portal frame is provided with an elastic suspension assembly for suspending the loading mechanism; the axle fixing base and the axle fixing cover plate are detachably connected through fasteners to jointly clamp and fix a half shaft sleeve of the axle test piece; the axle fixing base has a bearing frame which is matched with the half shaft sleeve through topological optimization, and the clamping surface of the axle fixing cover plate towards the half shaft sleeve is provided with a flexible gasket; the loading mechanism comprises a transverse servo actuator for applying a transverse load and a vertical servo actuator for applying a vertical load, the rear end of the transverse servo actuator is connected with the counterforce seat through a counterforce seat link plate, and the front end of the transverse servo actuator is connected with a link ball head on the axle body support seat through a link hook; the link hook of the vertical servo actuator is connected with a corresponding link ball head on the axle body support seat, and the force directions of the transverse actuator and the vertical servo actuator are spatially orthogonal.

[0009] In the technical scheme of the above axle fatigue test bench testing device, a more specific technical scheme can also be: further comprising a hydraulic adjusting mechanism assembled at a corresponding position of the axle fixing cover plate, a piston rod of the hydraulic adjusting mechanism acting on the axle fixing cover plate to adjust the contact pressure between the axle fixing cover plate and the axle test piece.

[0010] In some possible embodiments, the axle test piece is provided with an axle test piece fixing plate connected with the axle fixing cover plate and the axle fixing base through fasteners.

[0011] In some possible embodiments, the elastic suspension assembly comprises a hanger rod and a hook spring, the upper end of the hanger rod being fixed to the top of the portal frame, and the lower end being connected with the loading mechanism located below through the hook spring.

[0012] Another object of the present application is to provide an axle fatigue test bench testing system which deeply integrates and intelligently manages the rigid-flexible coupling clamping capacity and the spatial orthogonal loading capacity of the above testing device, realizes accurate dynamic reproduction of a composite load spectrum, adaptive matching of boundary conditions, and real-time monitoring and intelligent diagnosis of a testing state.

[0013] In order to achieve the above object, the scheme adopted by the present system is: applied to the above axle fatigue test bench testing device, the system comprises a management layer, a control layer, and an execution layer. The management team is responsible for test planning and monitoring, including the data processing and monitoring unit, which is responsible for planning the test load spectrum, monitoring the test process status, and storing and analyzing test data. The control layer is used for real-time collaborative and closed-loop control, including a multi-axis motion controller and a servo driver. The multi-axis motion controller receives load spectrum instructions from the management layer and generates multi-channel collaborative control signals. The servo driver responds to the control signals and drives the lateral and vertical servo actuators and hydraulic adjustment mechanism in the test device respectively. The execution layer is used for physical loading and measurement. It consists of the loading mechanism, the axle fixing components and the sensor group integrated thereon in the test device. It receives drive signals to perform physical loading and clamping actions, and at the same time collects loading force, clamping pressure and axle strain response signals in real time. The management layer transmits load spectrum commands unidirectionally to the control layer, while the control layer and the execution layer interact bidirectionally. The control layer outputs drive signals and receives signals acquired by the execution layer. The signals acquired by the execution layer are processed by the control layer and fed back to the management layer, forming a closed-loop control system that enables precise closed-loop control of load and clamping force and real-time monitoring of test status.

[0014] In the aforementioned technical solution of the vehicle axle fatigue testing rig, a more specific technical solution could be: the data processing and monitoring unit of the management layer includes a host computer and a data storage and analysis module; the host computer is used for test planning and real-time monitoring, generating target load spectra and displaying test data; the data storage and analysis module is used to store data from the entire test process, and generate stress-strain curves based on the data collected by the execution layer sensor group, completing the vehicle axle fatigue life assessment and adapting to the functional requirements of the management layer for test planning and monitoring.

[0015] In some possible implementations, the sensor group of the execution layer includes force sensors, displacement sensors, strain sensors, and pressure sensors; the force sensors are used to measure the loading force output by the servo actuator; the displacement sensors are used to measure the piston rod displacement of the servo actuator; the strain sensors are attached to key parts of the axle test piece to measure its strain response; the pressure sensors are set in the hydraulic adjustment mechanism to measure the clamping pressure; the physical signals collected by each sensor are transmitted to the control layer to provide data support for closed-loop control.

[0016] In some possible implementations, an extension interface is also included, which is connected to the management layer and / or control layer signals. The extension interface includes one or more of the following modules: The intelligent monitoring AI module interface is used to connect to the AI ​​computing unit that runs fault prediction or damage pattern recognition algorithms; A multi-degree-of-freedom extended axis interface is used to connect and control the drive unit of an additional servo actuator that applies axial force or torque; The remote monitoring interface is used to establish communication with remote terminals to realize the remote transmission and status monitoring of test data.

[0017] Another objective of this invention is to provide a vehicle axle fatigue testing method based on the aforementioned testing device. This method addresses the problems caused by the traditional method's reliance on simplified V-shaped / hinged constraints and single-axis push-pull loading modes, which result in a disconnect between laboratory loading conditions and real boundary conditions, and between the testing process and fatigue failure mechanism assessment.

[0018] To solve the above problems, the proposed solution is as follows: using the aforementioned axle fatigue testing rig, the method includes the following steps: S1. Preparation and Initial Setup: S11. Insert the axle end of the axle test piece into the axle end positioning hole of the axle support and fix it. Use the axle fixing base and the axle fixing cover plate to clamp and fix the axle test piece's half axle sleeve. S12. Install sensor groups on key parts of the axle test piece and calibrate the sensor groups; S13. Set the load mode, including setting the amplitude, frequency, and phase difference between the loads applied by the lateral servo actuator and the vertical servo actuator. S14. Set the load spectrum to define the characteristics of the multi-mode composite load applied during the test. S2. Clamping constraint establishment: The set clamping pressure is applied to the axle fixing cover plate by the hydraulic adjustment mechanism to establish the rigid-flexible coupling boundary constraint conditions. S3. Test Execution and Real-time Monitoring: S31. Control the movement of the lateral servo actuator and the vertical servo actuator in the loading mechanism to apply a spatial composite alternating load containing at least lateral and vertical components to the bridge support. S32. The sensor group collects the response data of the axle test piece under load in real time and feeds it back to the control system; the control system adjusts the motion state of the lateral servo actuator and the vertical servo actuator in real time according to the feedback data. S4. Data Analysis and Evaluation: S41. Store and process all collected response data; S42. Based on the processed response data, perform fatigue damage analysis to evaluate the fatigue life of the axle test piece and identify its fatigue failure mode.

[0019] In the above-mentioned technical solution of the vehicle axle fatigue test bench, a more specific technical solution may be: in steps S13 and S14, the definition of load mode and load spectrum is as follows: the lateral servo actuator and the vertical servo actuator are controlled to work together according to the preset load spectrum. The load spectrum defines the amplitude, frequency and phase relationship of the load in the two orthogonal directions of lateral and vertical, so as to simulate the composite working conditions in the actual driving of the vehicle; wherein, the composite load spectrum includes a lateral sinusoidal load of 0.5 to 1.5 Hz and a vertical broadband random load of 5 to 30 Hz, and the two are set with a time delay phase difference of 90°.

[0020] By adopting the above technical solution, the present invention has the following advantages compared with the prior art: 1. The device of this invention, using the axle fatigue testing rig protected by this claim, employs a topology-optimized axle fixing base and an axle fixing cover plate with flexible padding to form a rigid-flexible coupling constraint system. This eliminates the need for traditional hinged or damping clamping structures, precisely matching the structural form of the axle half-axle sleeve and evenly distributing the clamping force across the contact area. This effectively eliminates the abnormal stress concentration problem caused by the single constraint form of traditional clamps, while avoiding the risk of clamping force attenuation and positioning drift caused by mechanical wear at the hinge points. It achieves high-fidelity simulation of the three-dimensional dynamic coupling boundary between the axle end and the suspension system. The loading mechanism is equipped with orthogonally distributed lateral and vertical servo actuators, which breaks through the limitation of the single-actuator push-pull or eccentric wheel mechanism in terms of load direction. It can independently adjust the phase difference and amplitude-frequency characteristics of the load in the two directions, and generate spatial composite alternating excitation that conforms to the actual driving conditions of the vehicle. This solves the defect of the existing technology where laboratory conditions are out of sync with actual failure modes. The elastic suspension component of the gantry bracket can stably suspend and buffer the loading mechanism. Combined with the fixing effect of the reaction seat, it ensures the stability of the loading process and the accuracy of load application, which greatly improves the reliability and effectiveness of the axle fatigue test.

[0021] 2. A hydraulic adjustment mechanism is added to the corresponding position of the axle fixing cover plate. This mechanism acts on the axle fixing cover plate to adjust the contact pressure between it and the axle test piece. It can dynamically adjust the clamping force according to the specification differences of the axle test piece and the stress state during the test, so that the fit between the flexible pad and the half-axle sleeve is always kept in the optimal state. This further optimizes the self-adaptive capability of the rigid-flexible coupling constraint system. It not only improves the adaptability of the device to axles with different configurations, but also effectively avoids positioning inaccuracies caused by local stress concentration due to excessive clamping pressure or insufficient pressure. It significantly enhances the stability and accuracy of clamping constraint during the test, and ensures the test accuracy under long-term high-frequency tests.

[0022] 3. The axle test piece fixing plate can be set up as a transitional adapter for axles with different structures, converting them into a reliable installation interface for connection with the cover plate and base of this device, greatly expanding the versatility of this testing device and enabling it to cover a wider range of axle models.

[0023] 4. The specific structure of the elastic suspension assembly can use the elastic deformation of the hook spring to flexibly buffer the movement of the loading mechanism, effectively absorb the dynamic impact and vibration generated by the loading mechanism during the test, avoid the load transmission lag problem caused by rigid connection, and at the same time, can adaptively adjust the attitude of the loading mechanism to ensure that the lateral and vertical servo actuators always maintain the preset spatial orthogonal layout, ensure the accuracy of the load application direction, and improve the frequency response speed and test stability of the loading system.

[0024] 5. The system of this invention, by constructing a basic architecture of management layer, control layer, and execution layer, achieves deep integration and intelligent management of the rigid-flexible coupling clamping capability and spatial orthogonal loading capability of the testing device. The management layer can complete test load spectrum planning, process monitoring, and data storage and analysis. The control layer realizes synchronous closed-loop control of dual actuators and hydraulic adjustment mechanism through multi-axis motion controller and servo driver. The execution layer is responsible for physical loading and signal acquisition. The signal interaction between the three-level architecture forms a complete closed-loop control system, which can dynamically adjust the load output and clamping pressure according to the real-time data fed back by the sensor. This system not only realizes accurate dynamic reproduction of composite load spectrum and adaptive matching of boundary conditions, but also monitors the test status in real time, providing an intelligent solution for high-fidelity reproduction of vehicle axle fatigue failure mechanism and improving the engineering effectiveness of vehicle axle reliability assessment.

[0025] 6. The data processing and monitoring unit of the system management layer includes a host computer and a data storage and analysis module. The host computer can intuitively present the test planning interface and real-time data, which is convenient for operators to set working conditions and monitor status. The data storage and analysis module can completely save the data of the entire test process and generate stress-strain curves based on the data collected by the sensors, thereby completing the fatigue life assessment of the vehicle axle. This solves the defects of the traditional test system's insufficient data processing capabilities and inability to directly support fatigue life analysis, enabling the test data to be efficiently transformed into a valid basis for vehicle axle reliability assessment, and improving the data analysis capabilities of the test system and the application value of the test results.

[0026] 7. The sensor group in the actuator layer includes force sensors, displacement sensors, strain sensors, and pressure sensors. Each type of sensor accurately measures the loading force, actuator displacement, axle strain response, and clamping pressure. The multi-dimensional sensor data provides comprehensive and reliable data support for the closed-loop control of the control layer, enabling the control system to monitor the operating status of the loading mechanism and the force response of the axle test piece in real time, and adjust the actuator output and hydraulic adjustment mechanism pressure in a timely manner. This avoids control deviations caused by incomplete data from a single sensor. At the same time, the complete sensor data can comprehensively reflect the dynamic characteristics of the axle under combined loads, providing a detailed data foundation for subsequent fatigue damage analysis and failure mode identification, and ensuring the accuracy and comprehensiveness of the test results.

[0027] 8. Set up extension interfaces to enable the system to have scalability. These interfaces allow for the seamless integration of advanced AI algorithms for fault prediction or intelligent identification of damage modes without changing the core system architecture. They can also connect additional servo actuators to achieve multi-degree-of-freedom loading such as axial and torsional loads, or connect to remote terminals to achieve remote monitoring and analysis of data. This enables the system to continuously adapt to more complex testing needs and technological developments in the future, extending its technological life cycle and application value.

[0028] 9. The method of this invention, through a series of logically rigorous steps based on a specific testing device, including preparation and initial settings, actively establishing rigid-flexible coupling clamping constraints, executing composite load loading and monitoring based on real-time feedback, and performing data-driven analysis and evaluation, forms a standardized, repeatable, high-fidelity testing process. Specifically, sensor calibration and load mode setting in the preparation stage ensure the consistency of initial test conditions; the clamping constraint establishment stage uses a hydraulic adjustment mechanism to set precise clamping pressure, constructing high-fidelity axle end boundary constraints; the dual-actuator collaborative loading and real-time feedback adjustment in the test execution stage ensure the accurate application of composite alternating loads; and the fatigue damage analysis and failure mode identification in the data analysis and evaluation stage can uncover the fatigue failure patterns of the axle throughout its entire life cycle from the test data. This method solves the problem of traditional testing methods relying on simplified constraints and single-axis loading, leading to a disconnect between laboratory conditions and real failure mechanisms. It achieves, for the first time, high-fidelity reproduction of the fatigue failure mechanism of the axle under a full range of operating conditions, providing a testing scheme for axle reliability assessment that combines accuracy and systematicity.

[0029] 10. By defining specific parameters for the load mode and load spectrum, the actual working conditions of the vehicle undergoing high-speed cornering, coupled with the centrifugal force and random road surface excitation, are accurately reproduced, solving the problem of discrepancies between traditional test load spectra and actual working conditions. By controlling the dual actuators to work collaboratively according to this load spectrum, the stress state of the axle under real driving scenarios can be simulated, making the fatigue crack initiation and development patterns generated in the test highly consistent with the actual usage conditions. This significantly improves the accuracy of fatigue life assessment and failure mode identification, providing more targeted test basis for the structural optimization and reliability improvement of axle products. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the test device for the transverse fatigue test bench of this vehicle axle.

[0031] Figure 2 yes Figure 1 The right view.

[0032] Figure 3 yes Figure 1 A three-dimensional image.

[0033] Figure 4 This is a schematic diagram of the transverse fatigue testing system for this vehicle axle.

[0034] The labels in the diagram are: 1. Reaction seat; 2. Gantry bracket; 3. Axle support seat; 4. Axle test piece; 5. Axle fixing cover plate; 6. Axle fixing base; 6-1. Bearing frame; 7. Lateral servo actuator; 8. Hanger rod; 9. Hook spring; 10. Half shaft sleeve; 11. Reaction seat connecting plate. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments: Figures 1 to 3 The axle fatigue testing rig shown mainly includes a reaction seat 1, a loading mechanism, a gantry bracket 2, an axle support 3, and an axle fixing assembly. The reaction seat 1 is firmly installed on the ground. One end of the loading mechanism is fixedly connected to the reaction seat 1 via a reaction seat connecting plate 11, and the other end passes through the gantry bracket 2 and connects to the axle support 3. The gantry bracket 2 spans in front of the reaction seat 1, and its top is equipped with an elastic suspension assembly. In this embodiment, the elastic suspension assembly includes a suspension rod 8 and a hook spring 9. The upper end of the suspension rod 8 is fixed to the top of the gantry bracket 2, and the lower end is connected to the loading mechanism located below it via the hook spring 9, used to balance the self-weight of the loading mechanism and buffer vibrations during dynamic testing. The axle support 3 has shaft end positioning holes for inserting the axle end of the axle test piece 4, achieving initial positioning and support of the test end of the axle test piece 4.

[0036] The axle fixing assembly is used to clamp and fix the axle sleeve 10 of the axle test piece 4. It includes an axle fixing base 6 and an axle fixing cover plate 5. The axle fixing base 6 has a base and a support frame 6-1 on the fixing base that precisely matches the contour of the lower half of the axle sleeve 10. The support frame 6-1 has a thickened structure and reinforcing ribs with topology optimization design based on mechanical analysis, so as to obtain optimal stiffness and strength in the critical force transmission path and efficiently and evenly distribute the clamping force and test load. The axle fixing cover plate 5 is detachably connected to the axle fixing base 6 by high-strength fasteners, together forming a clamping and fixing of the axle sleeve 10. A flexible pad is provided on the clamping surface of the axle fixing cover plate 5 facing the axle sleeve 10 to adapt to the micro-unevenness of the contact surface and provide cushioning. To further achieve precise, adaptive, and constant control of the clamping force, a hydraulic adjustment mechanism is installed on the back side of the axle fixing cover plate 5. This mechanism includes at least one hydraulic cylinder. The piston rod of the hydraulic cylinder acts on the axle fixing cover plate 5, adjusting the clamping force of the cover plate on the half-shaft sleeve 10. This ensures stable clamping boundary conditions throughout the fatigue test, fundamentally eliminating the clamping force attenuation problem caused by wear in traditional mechanical locking methods. To improve the adaptability of the device to axles of different structures, the device may also include an axle test piece fixing plate. This fixing plate, as a transitional adapter, is positioned between the axle test piece 4 and the axle fixing cover plate 5, and is connected to the axle fixing cover plate 5 and the axle fixing base 6 via fasteners. This allows axles of various specifications to be reliably connected to this device. In this embodiment, the fasteners are all bolt assemblies.

[0037] The loading mechanism includes a lateral servo actuator 7 that applies lateral loads. The rear end of the lateral servo actuator 7 is connected to the reaction seat 1 via a reaction seat link plate 11, while its front end is connected to a link ball joint on the bridge support 3 via a link hook, forming a ball joint connection. This ball joint connection allows the actuator and the bridge support 3 to swing freely within a certain angle range, effectively compensating for installation alignment errors and ensuring pure force transmission along the axial direction, avoiding the introduction of additional bending moments. To simulate more complex multi-axis composite force states, the loading mechanism can also include a vertical servo actuator that applies vertical loads. This vertical servo actuator is also connected to another corresponding link ball joint on the bridge support 3 via a link hook at its front end, and its force direction is spatially orthogonal to the force direction of the lateral servo actuator 7. This arrangement allows the two servo actuators to be driven independently or collaboratively by the control system, thereby applying a planar composite alternating load with controllable phase, amplitude, and frequency to the bridge support 3, accurately reproducing the multi-directional random impact conditions during vehicle operation.

[0038] Before operation, the piston rod of the lateral servo actuator 7 is in a stable, ready position under the balancing effect of the elastic suspension assembly. When installing the axle test piece 4, first insert the axle end of the axle body into the axle end positioning hole of the axle support 3 and lock it in place. Then, use the bearing frame 6-1 of the axle fixing base 6 to support the half-axle sleeve 10, close the axle fixing cover plate 5, and initially tighten the connecting bolts. Then, activate the hydraulic adjustment mechanism to apply a precise preset clamping force, completing the construction of the rigid-flexible coupling boundary constraint. During testing, activate the lateral servo actuator 7 and / or the vertical servo actuator to apply a dynamic load to the axle end through the axle support 3. Throughout the loading process, the elastic suspension assembly continuously absorbs the high-frequency reaction vibration generated by the actuator, ensuring smooth system operation. After the test is completed, unload the device, loosen the fasteners, and the axle test piece 4 can be removed.

[0039] This device realistically reconstructs the three-dimensional installation constraints at the end of the axle using a clamp composed of an optimized rigid base and a flexible cover plate; it achieves high-fidelity simulation of multi-dimensional composite fatigue loads through the coordinated loading of two spatially orthogonally arranged dual servo actuators; and through auxiliary designs such as elastic suspension, it ensures the stability and accuracy of long-term testing, thus providing an effective test method for the reliability verification of the axle.

[0040] This testing system is applied to the aforementioned vehicle axle fatigue testing rig to achieve deep integration and intelligent management of rigid-flexible coupling clamping capability and spatial orthogonal loading capability. Through a basic architecture of management layer, control layer, and execution layer, and closed-loop control logic, it achieves accurate dynamic reproduction of the composite load spectrum, adaptive matching of boundary conditions, and real-time monitoring and intelligent diagnosis of the test status. Preferably, it also includes expansion interfaces. For example... Figure 4 As shown in the diagram, the architecture and signal flow implementation corresponding to the system block diagram are as follows.

[0041] The management layer is used for test planning and monitoring, specifically consisting of a data processing and monitoring unit, including an industrial control computer (IPC) as the host computer and a data storage and analysis module. The host computer uses a high-performance industrial-grade mainframe with a visual operating interface, supporting test personnel in setting test parameters, generating target load spectra, real-time monitoring of the test process, and data visualization. The data storage and analysis module uses a large-capacity solid-state drive array and a relational database, providing real-time storage of data throughout the entire test process. It also integrates a fatigue analysis algorithm library, which can automatically generate stress-strain curves and load-displacement curves based on data collected from the execution layer, completing fatigue life assessment and preliminary failure mode determination for the vehicle axle.

[0042] The control layer is responsible for real-time coordination and closed-loop control, and consists of a multi-axis motion controller, servo driver and signal conditioning module, and safety protection module. The multi-axis motion controller uses a high-precision controller supporting the EtherCAT bus protocol, possessing multi-channel synchronous control capabilities. It can receive load spectrum commands from the management layer and decompose them into control components in two orthogonal directions: lateral and vertical, generating two precise voltage / current control signals. The servo driver uses a hydraulic servo valve matched to the actuator, accurately responding to control signals. By adjusting the flow and pressure of the hydraulic oil, it drives the lateral and vertical servo actuators and hydraulic adjustment mechanisms to operate according to set parameters. The signal conditioning module includes a filtering circuit and an isolation module, which amplifies, filters, and electrically isolates the analog signals collected by the actuator layer sensors, eliminating environmental interference and ensuring the stability and accuracy of signal transmission. The safety protection module integrates an emergency stop button, an overload protection switch, and limit switches. The emergency stop button is located in key positions around the operating table and test bench. The overload protection switch monitors the actuator output force and hydraulic system pressure. The limit switches are installed at the actuator's stroke limit positions, allowing for rapid disconnection of the system power source in case of abnormalities, ensuring safety during the testing process.

[0043] The execution layer is responsible for physical loading and measurement, consisting of the loading mechanism of the testing device, the axle fixing assembly, and the sensor group integrated thereon, while a hydraulic power unit ensures power supply. The loading mechanism includes the aforementioned lateral servo actuator and vertical servo actuator, which are installed in a spatially orthogonal layout and connected to the connecting ball joint on the axle support via a connecting hook to apply composite alternating loads. The axle fixing assembly includes a topology-optimized axle fixing base, an axle fixing cover plate with flexible padding, and a hydraulic adjustment mechanism, which achieves stable constraint of the axle end through a rigid-flexible coupling structure. The sensor group includes force sensors, displacement sensors, strain sensors, and pressure sensors. The force sensor is installed at the output end of the servo actuator to measure the magnitude of the loading force in real time. The displacement sensor is integrated inside the servo actuator to monitor the displacement of the piston rod. The strain sensor uses a high-precision strain gauge, which is attached to key parts of the axle test piece (such as the axle housing weld, the connection between the half-axle sleeve and the axle body, etc.) to measure the strain response of the axle. The pressure sensor is set in the oil circuit of the hydraulic adjustment mechanism to monitor the clamping pressure in real time. The hydraulic power unit includes a hydraulic pump station, an accumulator, and a cooling system. The hydraulic pump station provides hydraulic oil with a stable pressure for the entire hydraulic system. The accumulator can buffer pressure fluctuations in the hydraulic system. The cooling system reduces the temperature of the hydraulic oil by circulating cooling water to prevent the system performance from being affected by excessively high oil temperature.

[0044] The system is equipped with expansion interfaces to connect with the upper-level computer in the management layer and the multi-axis motion controller in the control layer. Specifically, it includes three types of interface modules: the intelligent monitoring AI module interface adopts a PCIe expansion slot, which reserves communication protocols (such as TCP / IP) with the AI ​​computing unit. It can connect to the AI ​​computing unit running fault prediction or damage mode recognition algorithms to realize intelligent fault early warning and accurate failure mode identification during the test process; the multi-degree-of-freedom extended axis interface adopts a standardized hydraulic servo interface and EtherCAT expansion port, which can connect to and control the drive unit of the additional servo actuator that applies axial force or torque. After expansion, it can realize multi-degree-of-freedom composite load loading; the remote monitoring interface is implemented based on the Ethernet interface, supports VPN communication protocol, and can establish stable communication with remote terminals to realize remote transmission of test data and remote monitoring of test status.

[0045] The specific signal flow process of this testing system is as follows: Load spectrum input stage: The tester sets the test conditions through the visual interface of the host computer. The host computer generates the target load spectrum according to the set parameters, such as the composite load spectrum corresponding to high-speed cornering of the vehicle + random road surface excitation. The target load spectrum is sent to the multi-axis motion controller in the form of a time-domain signal via Ethernet / EtherCAT bus; Control command generation stage: After receiving the target load spectrum, the multi-axis motion controller decomposes it into load components in two orthogonal directions, lateral and vertical, through its built-in algorithm, generating two corresponding control signals with a voltage range of 0-10V, and outputs the control signals to the corresponding hydraulic servo valves; Actuator action stage: After receiving the control signals, the hydraulic servo valves precisely adjust the flow and pressure of the hydraulic oil, driving the lateral servo actuators and vertical servo actuators to output force / displacement according to the set amplitude, frequency, and phase, while simultaneously driving the hydraulic adjustment mechanism to adjust the clamping pressure of the axle fixing cover; Real-time feedback acquisition stage: Various sensors at the execution layer synchronously collect data: force sensors collect the actual output force of the actuator, displacement sensors collect the piston rod displacement of the actuator, strain sensors collect the strain response of the axle test piece, and pressure sensors collect the clamping pressure of the hydraulic adjustment mechanism. The analog signals collected by each sensor are transmitted to the signal conditioning module. In the closed-loop calibration stage, the signal conditioning module amplifies, filters, and isolates the collected analog signals, converts them into standard digital signals, and feeds them back to the multi-axis motion controller. The controller compares the actual feedback signal with the target load spectrum signal, calculates the deviation value, and adjusts the control signal through a PID / feedforward compensation algorithm to achieve precise tracking of the load and clamping force. In the data recording and analysis stage, the multi-axis motion controller synchronously transmits the calibrated control signal and various feedback data to the host computer. The host computer displays the data in real time and stores the entire process data in the data storage and analysis module. The data storage and analysis module performs data post-processing according to the experimental requirements and generates an analysis report.

[0046] This testing system achieves dynamic, high-precision reproduction of composite alternating loads and adaptive matching of clamping boundary conditions through real-time signal interaction and closed-loop feedback across three layers, ensuring that the entire testing process is under intelligent real-time monitoring and closed-loop adjustment. The optimized expansion interface design further reserves channels for the system's functional evolution and intelligent upgrades.

[0047] This test method is based on the aforementioned vehicle axle fatigue test bench and test system, and the method specifically includes the following steps.

[0048] S1. Preparation and Initial Setup S11. Preparation of test equipment: Insert the axle end of the axle test piece 4 to be tested into the axle end positioning hole of the axle support 3. After adjusting the axle posture, fix the axle end through the locking bolt at the axle end positioning hole. According to the specifications of the half axle sleeve 10 of the axle test piece 4, select a suitable axle test piece fixing plate, attach the axle test piece fixing plate to the outside of the half axle sleeve 10, align the bearing frame 6-1 of the axle fixing base 6 with the lower half of the half axle sleeve 10, close the axle fixing cover plate 5, and initially tighten the bolt assembly between the cover plate and the base to complete the initial fixing of the axle. Then check the installation status of the horizontal servo actuator 7 and the vertical servo actuator, adjust the tension of the hook spring 9 to ensure that both actuators are in the preset horizontal or vertical posture, and ensure that the direction of the force meets the spatial orthogonality requirements; start the hydraulic power unit and perform a no-load test run of the actuator to check whether the actuator stroke is smooth and without jamming, and at the same time calibrate the output force and displacement accuracy of the actuator through the servo driver.

[0049] S12. Sensor Installation and Calibration: Install force sensors at the output ends of the lateral and vertical servo actuators, ensuring the sensors are coaxial with the actuator output shafts; integrate displacement sensors inside the actuators, completing signal interface between the sensors and actuators; attach strain gauges from strain sensors to key locations on axle test piece 4, such as axle housing welds, axle sleeve-to-axle connection points, and suspension connection points; install pressure sensors in the hydraulic adjustment mechanism's oil circuit, ensuring good sealing between the sensor and the oil circuit; install temperature sensors on the hydraulic oil tank and actuator cylinder surface, and install acceleration sensors on key stress-bearing locations on axle test piece 4. Calibrate all sensors to ensure the accuracy of measurement data and avoid sensor errors affecting experimental results.

[0050] S13. Load Mode Setting: The tester sets the load mode through the visual interface of the host computer, specifying the applied load parameters of the lateral and vertical servo actuators, including load amplitude, frequency, and phase difference between their actions. For the combined condition of high-speed vehicle cornering and random road surface excitation, the lateral load is set to a low-frequency sine wave of 0.5–1.5 Hz with an amplitude of ±10 kN to simulate centrifugal force during turning; the vertical load is set to a broadband random vibration of 5–30 Hz to simulate road surface unevenness excitation; the time delay phase difference between the lateral and vertical loads is set to 90° to simulate the coupling effect of lateral and vertical forces when the wheel turns; the load mode curve is previewed through the host computer, and the settings are saved after confirming that the parameters are correct.

[0051] S14. Load Spectrum Setting: Based on the set load modes, the characteristics of multi-mode composite loads are set in the host computer, i.e., multiple load modes are applied simultaneously, such as a combination of lateral and longitudinal loads, or multi-degree-of-freedom vibration of the axle during actual driving. The characteristics of the load spectrum, such as load frequency, amplitude, periodicity, and randomness, are set through the control system.

[0052] S2. Clamping Constraint Establishment: The hydraulic adjustment mechanism is activated, and the target value of the clamping pressure is set through the host computer. The target value is determined based on the material and structural strength of the axle test piece. The piston rod of the hydraulic cylinder of the hydraulic adjustment mechanism acts on the axle fixing cover plate 5 under hydraulic drive, pushing the cover plate to move towards the half-axle sleeve 10, and the flexible pad is in contact with the surface of the half-axle sleeve 10. The clamping pressure data is collected in real time by the pressure sensor in the hydraulic adjustment mechanism and fed back to the control system. When the collected pressure value reaches the set target value, the control system issues a command, and the hydraulic adjustment mechanism stops moving to maintain the current clamping pressure. During this process, the posture of the axle test piece is observed to ensure no deviation. The strain value of the axle clamping area is monitored by the strain sensor to confirm that there is no abnormal stress concentration, thus completing the establishment of the rigid-flexible coupling boundary constraint.

[0053] S3. Test Execution and Real-time Monitoring S31. Load Application: After the test personnel confirm that all preparations have been completed, they issue a test start command through the host computer. The control system starts closed-loop control, and the multi-axis motion controller outputs the decomposed control signals to the corresponding servo drivers. The servo drivers drive the hydraulic servo valves to adjust the flow and pressure of the hydraulic oil, thereby driving the lateral servo actuator 7 and the vertical servo actuator to work together according to the set load spectrum. The lateral servo actuator drives the axle test piece 4 to generate lateral vibration through the axle support 3, while the vertical servo actuator drives the axle to generate vertical vibration. The two work together to apply a spatial composite alternating load containing lateral and vertical components to the axle. During the load application process, the hook spring 9 of the elastic suspension component buffers the dynamic impact and vibration generated by the actuator, ensuring the stability of the actuator's attitude and ensuring the accuracy of the load application direction.

[0054] S32. Real-time Monitoring and Adjustment: Force sensors collect the actual output force of the two actuators, displacement sensors collect the actual displacement of the actuator piston rod, strain sensors collect the strain response of key parts of the axle test piece, pressure sensors collect the clamping pressure, temperature sensors collect the hydraulic oil temperature and actuator temperature, and acceleration sensors collect the vibration response of the axle. All collected data are processed by the signal conditioning module and fed back to the multi-axis motion controller in the control layer in real time. When the amplitude or frequency of the lateral or vertical load deviates, the corresponding control signal is adjusted through the PID algorithm to correct the opening of the servo valve, thereby adjusting the output of the actuator. When the clamping pressure decreases, the controller issues a command, the hydraulic adjustment mechanism acts, and the pressure is replenished to the target value. When the strain value of key parts of the axle exceeds the elastic range, or the hydraulic oil temperature is too high or the actuator displacement exceeds the stroke limit, the system automatically triggers an early warning and adjusts the load output parameters. If the abnormal situation is not relieved, the safety protection program is activated and the test is stopped. The host computer displays the change curves of all monitored parameters in real time, including load-time curves, displacement-time curves, strain-time curves, pressure-time curves, etc. Testers can observe the test status in real time and record abnormal situations.

[0055] S4. Data Analysis and Evaluation S41. Data Storage and Processing: During the test, the data storage and analysis module stores all collected response data in real time, including load data, displacement data, strain data, clamping pressure data, temperature data, vibration data, etc. After the test, the data processing software is called to post-process the stored data. Based on the strain data and load data, stress-strain curves are generated; based on the displacement data and load data, load-displacement curves are generated; and characteristic parameters such as stress amplitude and strain amplitude of key parts of the vehicle axle are calculated.

[0056] S42. Fatigue Damage Analysis and Assessment: Fatigue damage analysis is performed based on the processed response data: Miner's linear cumulative damage theory is used, combined with the SN curve (stress-life curve) of the axle test material, to calculate the cumulative damage degree of the axle under combined load, and then evaluate the fatigue life of the axle; by analyzing the shape of the stress-strain curve, the stress state of the axle is determined, and possible fatigue weak points are identified.

[0057] Fatigue failure mode identification is performed by observing the deformation of the axle test specimen surface to check for crack initiation; key areas such as welds and shaft end connections are observed using a high-precision microscope to record the crack initiation location, length, and propagation trajectory; the load cycle stages corresponding to crack initiation and propagation are analyzed by combining the variation patterns of strain data; based on the analysis results, fatigue failure modes such as bending fatigue failure and shear fatigue failure of the axle are determined, and a fatigue failure analysis report is generated; the fatigue life assessment results are combined with the failure mode analysis conclusions to provide data support for the structural optimization and reliability improvement of the axle.

[0058] After the test is completed, shut down the hydraulic power unit. After the actuator is reset and the system pressure is released, loosen the fasteners of the axle fixing components, remove the axle test piece and sensor, clean the test bench, and complete the entire test process.

[0059] This testing method enables high-precision and high-efficiency reproduction and evaluation of the fatigue failure process of vehicle axles under actual complex working conditions in the laboratory, establishing a reliable verification method for the reliability design verification and life prediction of vehicle axle products.

Claims

1. A vehicle axle fatigue testing bench and testing device, characterized in that: The system includes a reaction seat, a loading mechanism, a portal frame, an axle support, and an axle fixing assembly. One end of the loading mechanism is fixedly connected to the reaction seat, and the other end passes through the portal frame and connects to the axle support. The axle support has an axle end positioning hole for mounting the axle test piece. The portal frame has an elastic suspension assembly for suspending the loading mechanism. The axle fixing base and the axle fixing cover are detachably connected by fasteners to clamp and fix the axle test piece's half-shaft sleeve. The axle fixing base has a bearing frame, which is connected via... The axle fixing cover is matched with the half-axle sleeve through topology optimization, and a flexible pad is provided on the clamping surface of the half-axle sleeve facing the axle sleeve; the loading mechanism includes a lateral servo actuator for applying lateral load and a vertical servo actuator for applying vertical load. The rear end of the lateral servo actuator is connected to the reaction seat through a reaction seat link plate, and its front end is connected to the link ball head on the axle support through a link hook; the link hook of the vertical servo actuator is connected to the corresponding link ball head on the axle support, and the force directions of the lateral actuator and the vertical servo actuator are spatially orthogonal.

2. The vehicle axle fatigue testing rig testing device according to claim 1, characterized in that: It also includes a hydraulic adjustment mechanism mounted at the corresponding position of the axle fixing cover plate. The piston rod of the hydraulic adjustment mechanism acts on the axle fixing cover plate to adjust the contact pressure between the axle fixing cover plate and the axle test piece.

3. The vehicle axle fatigue testing rig according to claim 1 or 2, characterized in that: The axle test piece is provided with an axle test piece fixing plate, which is connected to the axle fixing cover plate and the axle fixing base by fasteners.

4. The vehicle axle fatigue testing bench according to claim 1, characterized in that: The elastic suspension assembly includes a suspension rod and a hook spring. The upper end of the suspension rod is fixed to the top of the gantry bracket, and the lower end is connected to the loading mechanism located below it via the hook spring.

5. A vehicle axle fatigue testing bench system, characterized in that: The vehicle axle fatigue testing rig is applied to the testing device according to any one of claims 2 to 4, the system comprising a management layer, a control layer, and an execution layer; The management team is responsible for test planning and monitoring, including the data processing and monitoring unit, which is responsible for planning the test load spectrum, monitoring the test process status, and storing and analyzing test data. The control layer is used for real-time collaborative and closed-loop control, including a multi-axis motion controller and a servo driver. The multi-axis motion controller receives load spectrum instructions from the management layer and generates multi-channel collaborative control signals. The servo driver responds to the control signals and drives the lateral and vertical servo actuators and hydraulic adjustment mechanism in the test device respectively. The execution layer is used for physical loading and measurement. It consists of the loading mechanism, the axle fixing components and the sensor group integrated thereon in the test device. It receives drive signals to perform physical loading and clamping actions, and at the same time collects loading force, clamping pressure and axle strain response signals in real time. The management layer transmits load spectrum commands unidirectionally to the control layer, while the control layer and the execution layer interact bidirectionally. The control layer outputs drive signals and receives signals acquired by the execution layer. The signals acquired by the execution layer are processed by the control layer and fed back to the management layer, forming a closed-loop control system that enables precise closed-loop control of load and clamping force and real-time monitoring of test status.

6. The vehicle axle fatigue testing bench system according to claim 5, characterized in that: The data processing and monitoring unit of the management team includes a host computer and a data storage and analysis module; the host computer is used for test planning and real-time monitoring, generating target load spectra and displaying test data. The data storage and analysis module is used to store data from the entire test process and generate stress-strain curves based on the data collected by the sensor group at the execution layer, thereby completing the fatigue life assessment of the vehicle axle and adapting to the functional requirements of test planning and monitoring at the management level.

7. The vehicle axle fatigue testing bench system according to claim 5, characterized in that: The sensor group in the execution layer includes force sensors, displacement sensors, strain sensors, and pressure sensors. The force sensors are used to measure the loading force output by the servo actuator; the displacement sensors are used to measure the piston rod displacement of the servo actuator; the strain sensors are attached to key parts of the axle test piece to measure its strain response; the pressure sensors are set in the hydraulic adjustment mechanism to measure the clamping pressure; the physical signals collected by each sensor are transmitted to the control layer to provide data support for closed-loop control.

8. The vehicle axle fatigue testing bench system according to claim 5, characterized in that: It also includes an expansion interface, which is connected to the management layer and / or control layer signals. The expansion interface includes one or more of the following modules: The intelligent monitoring AI module interface is used to connect to the AI ​​computing unit that runs fault prediction or damage pattern recognition algorithms; A multi-degree-of-freedom extended axis interface is used to connect and control the drive unit of an additional servo actuator that applies axial force or torque; The remote monitoring interface is used to establish communication with remote terminals to realize the remote transmission and status monitoring of test data.

9. A method for testing vehicle axle fatigue using a testing bench, characterized in that, Using the axle fatigue testing rig apparatus according to any one of claims 2 to 4, the method includes the following steps: S1. Preparation and Initial Setup: S11. Insert the axle end of the axle test piece into the axle end positioning hole of the axle support and fix it. Use the axle fixing base and the axle fixing cover plate to clamp and fix the axle test piece's half axle sleeve. S12. Install sensor groups on key parts of the axle test piece and calibrate the sensor groups; S13. Set the load mode, including setting the amplitude, frequency, and phase difference between the loads applied by the lateral servo actuator and the vertical servo actuator. S14. Set the load spectrum to define the characteristics of the multi-mode composite load applied during the test. S2. Clamping constraint establishment: The set clamping pressure is applied to the axle fixing cover plate by the hydraulic adjustment mechanism to establish the rigid-flexible coupling boundary constraint conditions. S3. Test Execution and Real-time Monitoring: S31. Control the movement of the lateral servo actuator and the vertical servo actuator in the loading mechanism to apply a spatial composite alternating load containing at least lateral and vertical components to the bridge support. S32. The sensor group collects the response data of the axle test piece under load in real time and feeds it back to the control system; the control system adjusts the motion state of the lateral servo actuator and the vertical servo actuator in real time according to the feedback data. S4. Data Analysis and Evaluation: S41. Store and process all collected response data; S42. Based on the processed response data, perform fatigue damage analysis to evaluate the fatigue life of the axle test piece and identify its fatigue failure mode.

10. The axle fatigue test method according to claim 9, characterized in that: In steps S13 and S14, the definition of load mode and load spectrum is as follows: the lateral servo actuator and the vertical servo actuator are controlled to work together according to the preset load spectrum. The load spectrum defines the amplitude, frequency and phase relationship of the load in the two orthogonal directions of lateral and vertical, so as to simulate the composite working conditions in the actual driving of the vehicle. The composite load spectrum includes a lateral sinusoidal load of 0.5 to 1.5 Hz and a vertical broadband random load of 5 to 30 Hz, and the two are set with a time delay phase difference of 90°.

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