Reliability test method for torque transmission shaft of engine casing

Abstract

The application discloses a reliability test method for a transmission torque shaft of an engine case, and belongs to the technical field of engine component tests.The method is implemented by relying on a general shaft torsional fatigue test bench, and steps include: debugging and pre-checking the test bench; assembling the transmission torque shaft of the engine case to be tested at both ends of the test bench to ensure coaxiality meeting requirements; calibrating the test system for torque until qualification; controlling the test bench to apply cyclic torque load according to a preset variable load spectrum, the variable load spectrum containing high and low load sections each of 165 seconds and 5-second linear ramp transition sections, and the test being terminated after the transmission torque shaft is completely fractured; and performing fracture failure analysis on the fractured test piece to obtain a reliability conclusion in combination with test data.The application realizes accurate simulation of real working conditions of the transmission torque shaft of the engine case and accurate determination of the limit fatigue life, solves the problems of inaccurate load simulation and poor reliability of test results in the prior art, and provides an efficient and low-cost technical means for reliability examination of the transmission torque shaft of the engine case.

Description

Technical Field

[0001] This invention belongs to the field of engine component testing technology, specifically a reliability test method for a torsion transmission shaft for an engine casing. Background Technology

[0002] The torsion shaft in the engine casing is a critical component of the engine transmission, responsible for torque transmission and ensuring stable power output and normal operation of the entire machine. Fatigue failure of the torsion shaft can lead to transmission failure, causing abnormal noise, power reduction, and other issues, affecting the safety of testing and use.

[0003] Existing technologies commonly employ shaft torsional fatigue testing benches for related tests. These benches are mature, industry-standard equipment that can only perform basic torsional loading and routine fatigue performance testing of shaft components. There is currently no dedicated reliability testing method adapted to engine casing torsion shafts. They cannot effectively reproduce the complex load conditions of casing torsion shafts in actual transmission systems, nor do they establish a complete process for system torque calibration verification, automatic fault termination, reliability checks, and closed-loop evaluation of test data. During the development phase, it is impossible to accurately assess the working condition durability and reliability of casing torsion shafts, making it difficult to identify potential design and process hazards in advance. This poses quality risks to mass production and after-sales use. Therefore, there is an urgent need for a dedicated and automated reliability testing method for casing torsion shafts to meet reliability verification requirements. Summary of the Invention

[0004] To address the problems existing in the background art, the present invention provides a reliability test method for a torsion transmission shaft in an engine casing.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for testing the reliability of a torsion transmission shaft for an engine casing, the method comprising the following steps:

[0006] S1: Perform debugging and pre-inspection on the shaft torsion fatigue testing bench to confirm that the drive unit, loading unit, data acquisition unit and control unit are functioning normally;

[0007] S2: The torsion shaft of the casing to be tested is assembled on the drive end and loading end of the test bench using a special fixture to ensure that the coaxiality meets the requirements;

[0008] S3: Calibrate the torque of the test system until the calibration is qualified;

[0009] S4: The test bench applies a cyclic torque load to the casing torsion shaft according to a preset variable load spectrum. The preset variable load spectrum includes a high load segment and a low load segment. Each load segment lasts for 165 seconds. The high load and low load are transitioned by a 5-second linear ramp. The test continues until the casing torsion shaft completely breaks, at which point the test is immediately terminated.

[0010] S5: Perform fracture failure analysis on the fractured torsion shaft of the casing.

[0011] S6: Analyze and evaluate the data collected in the experiment to draw a reliability conclusion.

[0012] S1 includes the following steps:

[0013] S101: Debug the drive unit, loading unit, data acquisition unit and control unit of the test bench to verify the functional integrity of each unit;

[0014] S102: Check the tightness of the connections of each component, the reliability of the electrical wiring connections, and the working status of the sensors;

[0015] S103: Proceed to the next step after confirming that the test bench is fault-free.

[0016] S2 includes the following steps:

[0017] S201: Use spline clamps or flange clamps to install the torsion shaft of the test casing on the drive end and loading end of the test bench respectively;

[0018] S202: Adjust the position of the fixture so that the coaxiality error between the torque transmission shaft, drive shaft, and loading shaft is ≤0.05mm;

[0019] S203: Tighten the connecting bolts according to the torque value required by the design.

[0020] S3 includes the following steps:

[0021] S301: The test system is calibrated across its entire range using a standard torque sensor;

[0022] S302: If the calibration fails, adjust the system parameters and recalibrate.

[0023] S303: Proceed to the next step after the calibration is passed.

[0024] S4 includes the following steps:

[0025] S401: Real-time acquisition of torque load, test time, number of cycles, and stepper motor operating frequency parameters during the test process;

[0026] S402: If a fixture falls off, the equipment overloads and stops, or other equipment or fixture malfunctions occur during the test, the test shall be terminated immediately and the fault shall be investigated. The test data shall be invalid, and a new specimen shall be replaced and the test shall be repeated.

[0027] S403: Record the fracture time, fracture load, and number of cycles at fracture.

[0028] S5 includes the following steps:

[0029] S501: Fracture Location Confirmation: Determine the location of fatigue crack initiation and final fracture;

[0030] S502: Macroscopic morphology analysis of fracture surface: Observe the macroscopic characteristics of the fracture surface to distinguish fatigue fracture from other fracture types;

[0031] S503: Dimensional Measurement: Measure the shaft diameter and deformation parameters at the fracture site.

[0032] S6 includes the following steps:

[0033] S601: Determine the fatigue life of a single torsion shaft, i.e., the number of cycles at which it breaks.

[0034] S602: Determine the failure mechanism of fatigue fracture based on the fracture surface analysis results;

[0035] S603: Take the average fatigue life of multiple parallel specimens from the same batch as the fatigue life of the batch of products.

[0036] S604: If the experimental data are too discrete and do not meet the statistical significance requirements, replace the test specimens with new specimens from the same batch and repeat the test.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] 1. Load simulation is more in line with actual working conditions: It adopts a variable load spectrum specifically designed for the actual operating conditions of the engine. Through the combination of high load segment, low load segment and linear ramp transition segment, it can effectively reproduce the dynamic stress state of the gearbox torsion shaft during acceleration, cruise and working condition switching, and solve the problem that the existing single constant amplitude load cannot simulate complex working conditions.

[0039] 2. It can accurately determine the ultimate fatigue life of the torsion transmission shaft: It uses complete fracture as the only effective test termination condition, does not preset any fixed number of cycles, and does not perform intermediate crack detection. It can completely record the entire process of the torsion transmission shaft from loading to final fracture, and obtain its true ultimate fatigue life under this working condition.

[0040] 3. Improve the accuracy of reliability assessment: Based on accurate load simulation and real limit life determination, the test results are more consistent with the actual failure of the torsion shaft, which can effectively identify potential fatigue failure hazards in advance and reduce after-sales quality risks after mass production.

[0041] 4. Low implementation cost and high practicality: It can be implemented based on the existing general-purpose NDW type microcomputer-controlled shaft torsion fatigue test bench without the need to modify the test bench structure itself, which greatly reduces the investment in test equipment; at the same time, it can be applied to the reliability test of the torsion transmission shaft of the casing of the same model but different batches of engines.

[0042] 5. Provide key data support for product optimization: By analyzing fracture failure, the location and mechanism of fatigue fracture can be identified. Combined with statistical analysis of multiple parallel specimens from the same batch, not only can the average fatigue life of the product be obtained, but also key data support can be provided for the structural optimization, material selection and life prediction of the torsion shaft.

[0043] In summary, by optimizing the test method and load spectrum design, this invention achieves accurate simulation of the real working conditions of the engine casing torsion shaft and accurate determination of its ultimate fatigue life on general-purpose test equipment. It solves the core problems of inaccurate load simulation and poor reliability of test results in the prior art, and provides an efficient and accurate technical means for the reliability assessment of the casing torsion shaft. Attached Figure Description

[0044] Figure 1 This is an overall flowchart of the present invention;

[0045] Figure 2 This is a schematic diagram of the load variation of the present invention. Detailed Implementation

[0046] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0047] This embodiment describes a reliability test method for a torsion shaft in an engine casing, the method comprising the following steps:

[0048] S1: Perform debugging and pre-inspection on the shaft torsion fatigue testing bench to confirm that the drive unit, loading unit, data acquisition unit and control unit are functioning normally;

[0049] S2: The torsion shaft of the casing to be tested is assembled on the drive end and loading end of the test bench using a special fixture to ensure that the coaxiality meets the requirements;

[0050] S3: Calibrate the torque of the test system until the calibration is qualified;

[0051] S4: The test bench applies a cyclic torque load to the casing torsion shaft according to a preset variable load spectrum. The preset variable load spectrum includes a high load segment and a low load segment. Each load segment lasts for 165 seconds. The high load and low load are transitioned by a 5-second linear ramp. The test continues until the casing torsion shaft completely breaks, at which point the test is immediately terminated.

[0052] S5: Perform fracture failure analysis on the fractured torsion shaft of the casing.

[0053] S6: Analyze and evaluate the data collected in the experiment to draw a reliability conclusion.

[0054] S1 includes the following steps:

[0055] S101: Debug the drive unit, loading unit, data acquisition unit and control unit of the test bench to verify the functional integrity of each unit;

[0056] S102: Check the tightness of the connections of each component, the reliability of the electrical wiring connections, and the working status of the sensors;

[0057] S103: Proceed to the next step after confirming that the test bench is fault-free.

[0058] S2 includes the following steps:

[0059] S201: Use spline clamps or flange clamps to install the torsion shaft of the test casing on the drive end and loading end of the test bench respectively;

[0060] S202: Adjust the position of the fixture so that the coaxiality error between the torque transmission shaft, drive shaft, and loading shaft is ≤0.05mm;

[0061] S203: Tighten the connecting bolts according to the torque value required by the design.

[0062] S3 includes the following steps:

[0063] S301: The test system is calibrated across its entire range using a standard torque sensor;

[0064] S302: If the calibration fails, adjust the system parameters and recalibrate.

[0065] S303: Proceed to the next step after the calibration is passed.

[0066] S4 includes the following steps:

[0067] S401: Real-time acquisition of torque load, test time, number of cycles, and stepper motor operating frequency parameters during the test process;

[0068] S402: If a fixture falls off, the equipment overloads and stops, or other equipment or fixture malfunctions occur during the test, the test shall be terminated immediately and the fault shall be investigated. The test data shall be invalid, and a new specimen shall be replaced and the test shall be repeated.

[0069] S403: Record the fracture time, fracture load, and number of cycles at fracture.

[0070] S5 includes the following steps:

[0071] S501: Fracture Location Confirmation: Determine the location of fatigue crack initiation and final fracture;

[0072] S502: Macroscopic morphology analysis of fracture surface: Observe the macroscopic characteristics of the fracture surface to distinguish fatigue fracture from other fracture types;

[0073] S503: Dimensional Measurement: Measure the shaft diameter and deformation parameters at the fracture site.

[0074] S6 includes the following steps:

[0075] S601: Determine the fatigue life of a single torsion shaft, i.e., the number of cycles at which it breaks.

[0076] S602: Determine the failure mechanism of fatigue fracture based on the fracture surface analysis results;

[0077] S603: Take the average fatigue life of multiple parallel specimens from the same batch as the fatigue life of the batch of products.

[0078] S604: If the experimental data are too discrete and do not meet the statistical significance requirements, replace the test specimens with new specimens from the same batch and repeat the test.

[0079] This invention provides a dedicated fatigue life testing method adapted to existing general-purpose shaft torsional fatigue testing benches. It does not modify the bench structure itself. The testing bench for implementing this method can be an NDW-type microcomputer-controlled shaft torsional fatigue testing bench. Its core working principle is based on the fatigue damage accumulation theory and the mapping of actual engine operating loads, solving the technical problem that existing technologies cannot effectively reproduce the complex load states of the transmission shaft in actual transmission systems. In existing technologies, fatigue tests of shaft parts generally use a single constant amplitude cyclic load, and often employ a fixed-number termination method with a preset fixed number of cycles. This method can only simulate the stress on the transmission shaft under a certain fixed operating condition and cannot reproduce the dynamic variable load processes such as acceleration and cruising during actual engine operation. Furthermore, the non-fracture termination method cannot determine the ultimate fatigue life of the transmission shaft, leading to a significant deviation between fatigue test results and actual failure conditions. This makes it impossible to effectively identify potential failure hazards in advance, posing after-sales quality risks to mass production.

[0080] This invention extracts typical high-load and low-load segments by statistically analyzing torque data under actual engine operating conditions. The high-load segment is preferably 250N. m, the low load section is preferably 50N Simultaneously, a linear ramp transition section was added to simulate the switching process between acceleration and cruise conditions, constructing a dedicated variable load spectrum that highly matches actual working conditions. During the test, the stability of each unit of the test bench was first ensured through debugging and pre-checking to avoid equipment failure affecting the validity of the test data; then, the accuracy of the applied load was ensured through torque calibration; subsequently, cyclic torque loads were applied to the torsion shaft according to the aforementioned dedicated variable load spectrum. During the test, torque, time, number of cycles, and stepper motor operating frequency parameters were collected in real time. No fixed termination number of cycles was preset, and intermediate crack detection was not performed. The complete fracture of the torsion shaft was used as the only valid test termination condition, which can accurately determine its ultimate fatigue life.

[0081] After the test was terminated, a comprehensive fracture failure analysis was conducted on the fractured specimens through fracture location confirmation, macroscopic fracture morphology analysis, and dimensional measurement to clarify the fatigue fracture failure mechanism. Then, statistical analysis of the test data from multiple parallel specimens was performed to obtain the average fatigue life of this batch of products, providing crucial data support for structural optimization, material selection, and life prediction of the torsion shaft. The method of this invention can effectively reproduce the load state of the torsion shaft under actual transmission conditions, accurately assess its durability and reliability, and significantly reduce after-sales quality risks after mass production. This method is applicable to reliability testing of engine casing torsion shafts made of different materials and with different heat treatment methods.

[0082] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalent features of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for testing the reliability of a torsion transmission shaft in an engine casing, characterized in that: The method includes the following steps: S1: Perform debugging and pre-inspection on the shaft torsion fatigue testing bench to confirm that the drive unit, loading unit, data acquisition unit and control unit are functioning normally; S2: The torsion shaft of the casing to be tested is assembled on the drive end and loading end of the test bench using a special fixture to ensure that the coaxiality meets the requirements; S3: Calibrate the torque of the test system until the calibration is qualified; S4: The test bench applies a cyclic torque load to the casing torsion shaft according to a preset variable load spectrum. The preset variable load spectrum includes a high load segment and a low load segment. Each load segment lasts for 165 seconds. The high load and low load are transitioned by a 5-second linear ramp. The test continues until the casing torsion shaft completely breaks, at which point the test is immediately terminated. S5: Perform fracture failure analysis on the fractured torsion shaft of the casing. S6: Analyze and evaluate the data collected in the experiment to draw a reliability conclusion.

2. The test method according to claim 1, characterized in that: S1 includes the following steps: S101: Debug the drive unit, loading unit, data acquisition unit and control unit of the test bench to verify the functional integrity of each unit; S102: Check the tightness of the connections of each component, the reliability of the electrical wiring connections, and the working status of the sensors; S103: Proceed to the next step after confirming that the test bench is fault-free.

3. The test method according to claim 1, characterized in that: S2 includes the following steps: S201: Use spline clamps or flange clamps to install the torsion shaft of the test casing on the drive end and loading end of the test bench respectively; S202: Adjust the position of the fixture so that the coaxiality error between the torque transmission shaft, drive shaft, and loading shaft is ≤0.05mm; S203: Tighten the connecting bolts according to the torque value required by the design.

4. The test method according to claim 1, characterized in that: S3 includes the following steps: S301: The test system is calibrated across its entire range using a standard torque sensor; S302: If the calibration fails, adjust the system parameters and recalibrate. S303: Proceed to the next step after the calibration is passed.

5. The test method according to claim 1, characterized in that: S4 includes the following steps: S401: Real-time acquisition of torque load, test time, number of cycles, and stepper motor operating frequency parameters during the test process; S402: If a fixture falls off, the equipment overloads and stops, or other equipment or fixture malfunctions occur during the test, the test shall be terminated immediately and the fault shall be investigated. The test data shall be invalid, and a new specimen shall be replaced and the test shall be repeated. S403: Record the fracture time, fracture load, and number of cycles at fracture.

6. The test method according to claim 1, characterized in that: S5 includes the following steps: S501: Fracture Location Confirmation: Determine the location of fatigue crack initiation and final fracture; S502: Macroscopic morphology analysis of fracture surface: Observe the macroscopic characteristics of the fracture surface to distinguish fatigue fracture from other fracture types; S503: Dimensional Measurement: Measure the shaft diameter and deformation parameters at the fracture site.

7. The test method according to claim 1, characterized in that: S6 includes the following steps: S601: Determine the fatigue life of a single torsion shaft, i.e., the number of cycles at which it breaks. S602: Determine the failure mechanism of fatigue fracture based on the fracture surface analysis results; S603: Take the average fatigue life of multiple parallel specimens from the same batch as the fatigue life of the batch of products. S604: If the experimental data are too discrete and do not meet the statistical significance requirements, replace the test specimens with new specimens from the same batch and repeat the test.

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