A low cycle fatigue test method for an aeroengine disk

Abstract

The present invention discloses a low-cycle fatigue test method for an aero-engine disk, belonging to the technical field of aero-engines. In this method, an elliptical hole is opened at the eccentric hole part of the test disk of the disk, and the short diameter of the elliptical hole passes through the position where the maximum stress is located in the eccentric hole part, so as to reduce the geometric mutation at the position where the maximum stress is located in the eccentric hole part, reduce the stress concentration and the maximum equivalent stress at the eccentric hole part, increase the fatigue life of the eccentric hole part of the test disk. At the same time, opening the elliptical hole can also eliminate the fatigue damage generated at the eccentric hole part of the test disk during the low-cycle fatigue test of the eccentric hole part, avoid the accumulation of fatigue damage at the eccentric hole part, and further increase the fatigue life of the eccentric hole part of the test disk, enabling the low-cycle fatigue test of the wheel center part of the test disk to proceed smoothly, realizing the low-cycle fatigue test assessment of the wheel center part and the eccentric hole part on a single test disk, and reducing the test cost.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engines, and particularly to a method for low-cycle fatigue test of an aero-engine disk. Background Art

[0002] For the disk of an aero-engine, a low-cycle fatigue test needs to be carried out to verify whether the low-cycle fatigue life of the disk meets the design requirements. During operation, the disk is mainly subjected to thermal stress in the gas environment and centrifugal force during rotation. By calculating the stress at the critical point of the disk and evaluating its low-cycle fatigue life, the assessment part is determined, and isothermal heating is carried out according to the temperature at the working state of the assessment point. Since the test environment is isothermal, the thermal stress at the assessment part needs to be equivalent by increasing the test speed;

[0003] In the existing low-cycle fatigue test of the disk, since only isothermal heating can be carried out, the thermal stress during the operation of the disk cannot be considered. For a disk with an eccentric hole, multiple positions such as the eccentric hole and the disk center need to be separately assessed in the low-cycle fatigue test. Since the stress at the eccentric hole is relatively high during the working state, when assessing the disk center in the low-cycle fatigue test, after the stress at the disk center is equivalent by increasing the speed, the stress at the eccentric hole is too high compared with the stress in the previous test, and the eccentric hole is likely to fail in advance, and ultimately the purpose of assessing the low-cycle fatigue life of the disk center cannot be achieved. Currently, the common solution is to use two test disks to separately assess the disk center part and the eccentric hole part, resulting in a large consumption of test materials and high test costs.

[0004] Based on this, the present invention designs a method for low-cycle fatigue test of an aero-engine disk to solve the above problems. Summary of the Invention

[0005] The present invention provides a method for low-cycle fatigue test of an aero-engine disk to solve the technical problem that the eccentric hole part of the disk cannot be assessed through the low-cycle fatigue test of the disk center part.

[0006] According to one aspect of the present invention, a method for low-cycle fatigue test of an aero-engine disk is provided, including the following steps:

[0007] S100, finite element stress analysis of the disk in the working state;

[0008] Establish a finite element model of the disk and perform finite element stress analysis in the working state of the disk to obtain the temperature T1 and stress S1 at the eccentric hole part, and the temperature T2 and stress S2 at the disk center part in the working state of the disk;

[0009] S200, determination of the test load at the eccentric hole part;

[0010] Apply a uniform temperature load of temperature T1 on the finite element model of the wheel disc and conduct finite element stress analysis under the test state to determine the test speed N1 when the stress at the eccentric hole reaches S1;

[0011] S300, low cycle fatigue test on the eccentric hole part;

[0012] Use the test wheel disc to carry out low cycle fatigue test at the test speed N1 and test temperature T1 to examine the eccentric hole part of the wheel disc;

[0013] S400, determination of the test load at the wheel center part;

[0014] Apply a uniform temperature load of temperature T2 on the finite element model of the wheel disc and conduct finite element stress analysis under the test state to determine the test speed N2 when the stress at the wheel center part reaches S2, the stress S3 at the eccentric hole part, and the stress distribution at the eccentric hole part, and use the stress S3 and temperature T2 to predict the fatigue life of the eccentric hole part. When the eccentric hole part fails to pass the low cycle fatigue test of the wheel center part, proceed to step S500. When the eccentric hole part can pass the low cycle fatigue test of the wheel center part, proceed to step S600;

[0015] S500, re - machine the eccentric hole;

[0016] When the elliptical hole is not opened at the eccentric hole part on the finite element model of the wheel disc, open an elliptical hole along the axial direction of the wheel disc at the eccentric hole part on the finite element model of the wheel disc. Determine the short - radius direction of the elliptical hole according to the stress distribution at the eccentric hole part when the stress at the wheel center part reaches S2. After the hole opening is completed, proceed to step S400;

[0017] When the elliptical hole has been opened at the eccentric hole part on the finite element model of the wheel disc, adjust the major - radius and minor - radius dimensions of the ellipse according to the stress distribution at the eccentric hole part when the stress at the wheel center part reaches S2. After the adjustment is completed, proceed to step S400;

[0018] S600, low cycle fatigue test on the wheel center part;

[0019] When the elliptical hole is not opened on the finite element model of the wheel disc, use the test wheel disc to carry out low cycle fatigue test at the speed N2 and temperature T2 to examine the wheel center part of the test wheel disc;

[0020] When the elliptical hole is opened on the finite element model of the wheel disc, open an elliptical hole with the same size at the same position on the test wheel disc, and carry out low cycle fatigue test at the speed N2 and temperature T2 to examine the wheel center part of the test wheel disc.

[0021] As a further solution of the present invention, in S100, when conducting finite element stress analysis under the working state of the wheel disc, the working state adopts the maximum take - off state under standard weather.

[0022] As a further aspect of the present invention, in S400, a fatigue damage accumulation method is adopted to predict the fatigue life of the eccentric hole part.

[0023] As a further aspect of the present invention, in S300 and S600, the test disk is assembled to the test device for low-cycle fatigue test; the test device includes a transfer shaft, bolts and nuts, the transfer shaft includes a mounting edge for connecting with the test disk, the mounting edge is used to abut against the stop at one end of the test disk in the axial direction, and the mounting edge and the test disk are fixedly connected by bolts and nuts.

[0024] As a further aspect of the present invention, in S500, when an elliptical hole is opened on the disk finite element model, the difference between the short radius of the elliptical hole and the radius of the eccentric hole is not less than 1 mm.

[0025] As a further aspect of the present invention, in S500, when the elliptical hole is opened, the elliptical hole and the eccentric hole part are coaxially arranged.

[0026] As a further aspect of the present invention, in S500, when adjusting the long radius and short radius of the elliptical hole according to the stress distribution of the eccentric hole part when the stress at the wheel center part reaches S2, when the distance from the position where the maximum stress of the eccentric hole part is located to the short radius is less than the distance to the long radius, the long radius of the elliptical hole is increased, and when the distance from the position where the maximum stress of the eccentric hole part is located to the short radius is greater than the distance to the long radius, the short radius of the elliptical hole is increased.

[0027] As a further aspect of the present invention, the surface of the mounting edge (11) for contacting the disk in the axial direction of the test disk is the first contact surface. After the elliptical hole is opened on the test disk, the contact area between the first contact surface and the test disk is not less than half of the contact area before the elliptical hole is opened on the test disk.

[0028] As a further aspect of the present invention, the mass change of the disk finite element model after the elliptical hole is opened is less than 5%.

[0029] As a further aspect of the present invention, the average stress deformation of the disk finite element model after the elliptical hole is opened is less than 5% of the average stress of the original disk finite element model.

[0030] The present invention has the following beneficial effects:

[0031] When the low-cycle fatigue test of the eccentric hole part cannot pass the assessment of the wheel center part, in this method, an elliptical hole is opened at the eccentric hole part of the test wheel disc of the wheel disc. The short diameter of the elliptical hole passes through the position where the maximum stress of the eccentric hole part is located, thereby reducing the geometric mutation at the position where the maximum stress of the eccentric hole part is located, reducing the stress concentration and the maximum equivalent stress at the eccentric hole part, increasing the fatigue life of the eccentric hole part of the test wheel disc. At the same time, opening the elliptical hole can also eliminate the fatigue damage generated at the eccentric hole part of the test wheel disc during the low-cycle fatigue test of the eccentric hole part, avoid the accumulation of fatigue damage at the eccentric hole part, and further increase the fatigue life of the eccentric hole part of the test wheel disc, enabling the low-cycle fatigue test of the wheel center part of the test wheel disc to proceed smoothly, realizing the low-cycle fatigue test assessment of the wheel center part and the eccentric hole part on a single test wheel disc, and reducing the test cost.

[0032] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The following will refer to the drawings to further elaborate on the present invention in detail. Brief Description of the Drawings

[0033] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0034] Figure 1 is a schematic structural diagram of the wheel disc in the present invention;

[0035] Figure 2 is a schematic diagram of the stress distribution before the elliptical hole is opened at the eccentric hole part of the wheel disc;

[0036] Figure 3 is a schematic diagram of the elliptical hole opened at the eccentric hole part of the wheel disc;

[0037] Figure 4 is a schematic diagram of the stress distribution after the elliptical hole is opened at the eccentric hole part of the wheel disc;

[0038] Figure 5 is a schematic structural diagram of the test device in the present invention;

[0039] Figure 6 is a flow chart of the present invention.

[0040] Legend Explanation:

[0041] 1. Adapter shaft; 11. Mounting edge; 2. Bolt; 3. Nut. Detailed Embodiment

[0042] The following will elaborate on the embodiments of the present invention in detail with reference to the drawings. However, the present invention can be implemented in many different ways defined and covered by the following.

[0043] Please refer to Figure 1-6 , the present invention provides a technical solution: a low cycle fatigue test method for an aeroengine disk, comprising the following steps:

[0044] S100, finite element stress analysis of the disk working state;

[0045] Establish a finite element model of the disk and conduct finite element stress analysis of the disk in the working state to obtain the temperature T1 and stress S1 at the eccentric hole part, and the temperature T2 and stress S2 at the disk center part under the disk working state;

[0046] Before the test, it is necessary to determine the stress and temperature at the disk center part and the eccentric hole part of the disk in the working state, which are used as test parameters during the low cycle fatigue test. At the same time, using the stress and temperature in the working state to conduct low cycle fatigue tests on the disk center part and the eccentric hole part can ensure the accuracy of the low cycle fatigue test results;

[0047] S200, determination of the test load at the eccentric hole part;

[0048] Apply a uniform temperature load of temperature T1 on the disk finite element model and conduct finite element stress analysis under the test state to determine the test speed N1 when the stress at the eccentric hole part reaches S1;

[0049] Since the test environment is a uniform temperature without thermal stress, when conducting a low cycle fatigue test at the same speed as the working state, there will be a difference in the stress at the eccentric hole part of the test disk in the test environment and the stress in the working state. Therefore, it is necessary to determine the test speed through temperature T1 and stress S1. First, apply a uniform temperature load of temperature T1 on the disk finite element model, and then conduct finite element stress analysis under the test state. Adjust the speed of the disk finite element model until the stress at the eccentric hole part of the disk finite element model reaches S1. At this time, the speed of the disk finite element model is the test speed N1 for the low cycle fatigue test of the eccentric hole.

[0050] S300, low cycle fatigue test of the eccentric hole part;

[0051] Conduct a low cycle fatigue test on the test disk at the test speed N1 and test temperature T1 to evaluate the eccentric hole part;

[0052] After obtaining the test temperature T1 and test speed N1, the low cycle fatigue test can be started. During the test, control the temperature of the test disk at T1 and make the speed of the test disk reach N1. At this time, the stress at the eccentric hole part of the test disk reaches S1, ensuring the accuracy of the evaluation result;

[0053] S400, determination of the test load at the disk center part;

[0054] Apply a uniform temperature load of temperature T2 on the finite element model of the roulette wheel and conduct a finite element stress analysis under the test state to determine the test speed N2 when the stress at the wheel center reaches S2, the stress S3 at the eccentric hole part, and the stress distribution at the eccentric hole part. Then, use the stress S3 and temperature T2 to predict the fatigue life of the eccentric hole part. When the eccentric hole part fails to pass the low-cycle fatigue test of the wheel center part, proceed to step S500. When the eccentric hole part can pass the low-cycle fatigue test of the wheel center part, proceed to step S600;

[0055] Before conducting the low-cycle fatigue test on the wheel center part, it is necessary to determine the test speed. First, apply a uniform temperature load of temperature T2 on the finite element model of the roulette wheel, and then conduct a finite element stress analysis under the test state. Adjust the test speed of the finite element model of the roulette wheel until the stress at the wheel center of the finite element model of the roulette wheel reaches S2. At this time, the speed of the finite element model of the roulette wheel is the test speed N2 of the low-cycle fatigue test of the eccentric hole;

[0056] At the same time, it is necessary to determine the stress S3 and stress distribution at the eccentric hole part when the stress at the wheel center reaches S2, and use the stress S3 and temperature T2 to predict the fatigue life of the eccentric hole part. Judge whether the eccentric hole part can pass the next low-cycle fatigue test of the wheel center part. If not, proceed to S500. If so, proceed to S600;

[0057] S500, rework the eccentric hole;

[0058] When the elliptical hole is not opened at the eccentric hole part on the finite element model of the roulette wheel, open an elliptical hole along the axial direction at the eccentric hole part on the finite element model of the roulette wheel. Determine the short radius direction of the elliptical hole according to the stress distribution at the eccentric hole part when the stress at the wheel center reaches S2. After the hole opening is completed, proceed to step S400;

[0059] Open an elliptical hole at the eccentric hole position according to the stress distribution at the eccentric hole part when the stress at the wheel center reaches S2, so as to reduce the geometric mutation of the large stress area at the eccentric hole part, reduce the maximum equivalent stress at the eccentric hole part, increase the fatigue life of the eccentric hole part, and thus enable the low-cycle fatigue test of the wheel center part to be successfully completed.

[0060] As Figure 2 shown, the maximum stress at the eccentric hole part is located on the side of the eccentric hole part close to the axis of the finite element model of the roulette wheel. Therefore, as Figure 3 shown, when opening the elliptical hole, the short radius direction of the elliptical hole coincides with the radial direction of the finite element model of the roulette wheel, so as to reduce the geometric mutation on the side of the eccentric hole part close to the axis of the finite element model of the roulette wheel, reduce the stress concentration, reduce the maximum equivalent stress at the eccentric hole part, and increase the fatigue life of the eccentric hole part;

[0061] Meanwhile, opening the elliptical hole can also remove the fatigue damage generated during the low-cycle fatigue test at the eccentric hole part, avoid the accumulation of fatigue damage at the eccentric hole part, and further increase the fatigue life of the eccentric hole part;

[0062] After the elliptical hole is opened, the mass of the disk finite element model will change. Therefore, it is necessary to re-determine the test rotation speed N2. At the same time, it is necessary to determine the stress level and stress distribution at the eccentric hole part after opening the elliptical hole, and determine whether the eccentric hole part after opening the elliptical hole can pass the low-cycle fatigue test at the wheel center part. Therefore, it is necessary to return to S400 again;

[0063] When the elliptical hole has been opened at the eccentric hole part on the disk finite element model, adjust the major radius and minor radius dimensions of the ellipse according to the stress distribution at the eccentric hole part when the stress at the wheel center part reaches S2. After the adjustment is completed, proceed to step S400;

[0064] When the disk finite element model has been opened with an elliptical hole and the eccentric hole part still cannot pass the low-cycle fatigue test at the wheel center part, it is necessary to adjust the size of the elliptical hole. When adjusting, refer to the stress level and stress distribution at the eccentric hole part after opening the elliptical hole;

[0065] S600, low-cycle fatigue test at the wheel center part;

[0066] When no elliptical hole is opened on the disk finite element model, use the test disk to conduct a low-cycle fatigue test at a rotation speed of N2 and a temperature of T2 to assess the wheel center part;

[0067] When an elliptical hole is opened on the disk finite element model, open an elliptical hole with the same size at the same position on the test disk, and conduct a low-cycle fatigue test at a rotation speed of N2 and a temperature of T2 to assess the wheel center part;

[0068] After predicting through S400 that the eccentric hole part can pass the low-cycle fatigue test at the wheel center part, the low-cycle fatigue test at the wheel center part can be started. When an elliptical hole is opened on the finite element model of the disk, open an elliptical hole on the test disk according to the position and size of the elliptical hole on the disk finite element model, and then start the low-cycle fatigue test at the wheel center part. When no elliptical hole is opened on the finite element model of the disk, there is no need to open an elliptical hole on the test disk, and directly conduct the low-cycle fatigue test at the wheel center part. During the test, control the temperature of the test disk at T2 and make the rotation speed of the test disk reach N2. At this time, the stress at the wheel center part of the test disk reaches S2 to ensure the accuracy of the assessment result;

[0069] When the low-cycle fatigue test of the eccentric hole part cannot pass the assessment through the low-cycle fatigue test of the wheel center part, in this method, an elliptical hole is opened at the eccentric hole part of the test wheel disc of the wheel disc. The short diameter of the elliptical hole passes through the position where the maximum stress of the eccentric hole part is located, so as to reduce the geometric mutation at the position where the maximum stress of the eccentric hole part is located, reduce the stress concentration and the maximum equivalent stress at the eccentric hole part, increase the fatigue life of the eccentric hole part of the test wheel disc. At the same time, opening the elliptical hole can also eliminate the fatigue damage generated at the eccentric hole part of the test wheel disc during the low-cycle fatigue test of the eccentric hole part, avoid the accumulation of fatigue damage at the eccentric hole part, and further increase the fatigue life of the eccentric hole part of the test wheel disc, so that the low-cycle fatigue test of the wheel center part of the test wheel disc can be carried out smoothly, realize the low-cycle fatigue test assessment of the wheel center part and the eccentric hole part on a single test wheel disc, and reduce the test cost.

[0070] Specifically, in S100, when performing the finite element stress analysis of the wheel disc under the working state, the working state adopts the maximum takeoff state under standard weather;

[0071] Simulating the most severe working conditions, under the maximum takeoff state, the mechanical load and thermal load borne by the aero-engine reach the peak. The core of the low-cycle fatigue test is the cumulative damage caused by high stress amplitude, and the stress level under the maximum takeoff state is the highest, which is the main working condition leading to the failure of the wheel disc. Testing under this state can ensure that the wheel disc design can still meet the safety margin requirements under the most adverse conditions;

[0072] At the same time, the engine may reduce the thrust due to the surge margin limit under non-standard weather (such as high temperature, plateau), and at this time the mechanical load is actually less than the maximum takeoff thrust under standard weather. Therefore, the maximum takeoff state under standard weather is actually the theoretical maximum load borne by the wheel disc, covering all actual working conditions.

[0073] Specifically, in S400, when predicting the fatigue life of the eccentric hole part, the fatigue damage accumulation method is used to predict the fatigue life of the eccentric hole part, which is closer to the complex working conditions in the actual working process, and the prediction result is more accurate. Using the fatigue damage accumulation to predict the fatigue life belongs to the conventional technical means in this field.

[0074] Specifically, in S300 and S600, the test wheel disc is assembled to the test device for low-cycle fatigue test;

[0075] As Figure 5 shown, the test device includes a transfer shaft 1, a bolt 2 and a nut 3. The transfer shaft 1 includes a mounting edge 11 for connecting with the test wheel disc. The mounting edge 11 is used to abut against the stop at one end of the test wheel disc in the axial direction. The mounting edge 11 is fixedly connected with the test wheel disc through the bolt 2 and the nut 3;

[0076] The mounting edge 11 is provided with bolt holes 2 for passing through bolts 2, and the number and positions of the bolt holes 2 on the mounting edge 11 correspond one-to-one with the number and positions of the eccentric holes on the test wheel disc. When installing the test wheel disc onto the adapter shaft 1, the mounting edge 11 is abutted against one of the shoulders of the test wheel disc, and the bolt holes 2 are aligned with the eccentric holes on the test wheel disc. After alignment, the test wheel disc is connected to the adapter shaft 1 by passing the bolts 2 through and assembling nuts 3. The end of the adapter shaft 1 away from the mounting edge 11 is used to connect to the torque output mechanism, and the adapter shaft 1 is driven by the torque output mechanism to drive the test wheel disc to rotate;

[0077] The size of the nut 3 can be replaced according to the size of the elliptical hole to ensure that the nut 3 has sufficient contact area with the test wheel disc.

[0078] Specifically, in S500, when opening the elliptical hole on the finite element model of the wheel disc, the difference between the short radius of the elliptical hole and the radius of the eccentric hole is not less than 1 mm;

[0079] When conducting the low-cycle fatigue test assessment on the eccentric hole part of the test wheel disc in S300, fatigue damage will occur in the eccentric hole part. The difference between the short radius of the elliptical hole and the radius of the eccentric hole is not less than 1 mm, ensuring that the elliptical hole can eliminate the fatigue damage in the eccentric hole part and preventing the short diameter of the elliptical hole from being too small to completely eliminate the fatigue damage.

[0080] Specifically, in S500, when opening the elliptical hole, the elliptical hole and the eccentric hole part are coaxially arranged to prevent the elliptical hole from affecting the dynamic balance of the test wheel disc.

[0081] Specifically, in S500, when adjusting the long radius and short radius of the elliptical hole according to the stress distribution of the eccentric hole part when the stress at the wheel center part reaches S2, if the distance from the position of the maximum stress in the eccentric hole part to the short radius is less than the distance to the long radius, then increase the long radius of the elliptical hole; if the distance from the position of the maximum stress in the eccentric hole part to the short radius is greater than the distance to the long radius, then increase the short radius of the elliptical hole;

[0082] After an elliptical hole is opened at the eccentric hole part of the roulette finite element model, it is necessary to return to S400 for finite element stress analysis to determine whether the eccentric hole part after opening the elliptical hole can pass the low-cycle fatigue test at the wheel center part. When it still cannot pass the low-cycle fatigue test at the wheel center part, then the size of the elliptical hole needs to be adjusted. When adjusting the size of the elliptical hole, it is necessary to adjust according to the stress distribution at the eccentric hole part. When the maximum stress at the current eccentric hole part is closer to the short radius of the elliptical hole, increase the long radius of the elliptical hole, reduce the geometric mutation on the side of the short radius of the elliptical hole, and reduce the stress concentration. When the maximum stress at the current eccentric hole part is closer to the long radius of the elliptical hole, increase the short radius of the elliptical hole, reduce the geometric mutation on the side of the long radius of the elliptical hole, and reduce the stress concentration. Make corresponding adjustments according to the actual situation. The specific adjustment range of the short radius and long radius sizes is determined according to the actual stress magnitude, realizing precise and rapid adjustment of the elliptical hole size and reducing the elliptical hole size adjustment time.

[0083] As Figure 4 shown, after an elliptical hole is opened at the eccentric hole part, it still cannot pass the low-cycle fatigue test at the wheel center part. And at this time, the maximum stress at the eccentric hole part is located on the side of the long radius of the elliptical hole. At this time, the short radius of the elliptical hole can be increased, so that the geometric mutation on the side of the long radius of the elliptical hole is reduced, and the stress concentration on the side of the long radius of the elliptical hole is reduced, thereby increasing the fatigue life of the eccentric hole part.

[0084] One surface of the mounting edge 11 for contacting the test roulette in the axial direction of the test roulette is the first contact surface. After an elliptical hole is opened in the test roulette, the contact surface between the test roulette and the first contact surface will decrease, and the friction force between the first contact surface and the test roulette will decrease. At this time, the stress concentration coefficient at the hole edge of the eccentric hole part rises to compensate for the decrease in friction force caused by the reduction of the contact area. Therefore, the contact area between the first contact surface and the test roulette after opening the elliptical hole in the test roulette is not less than half of the contact area before opening the elliptical hole in the test roulette, controlling the stress concentration coefficient at the hole edge of the eccentric hole part, thereby increasing the fatigue life of the eccentric hole part.

[0085] Specifically, the mass change after opening the elliptical hole in the roulette finite element model is less than 5%, and the mass reduction is controlled within 5%, avoiding excessive weakening of the structural strength, making the fatigue life improvement of the eccentric hole part more significant. At the same time, reducing the influence of the mass change on the rotational inertia of the roulette test and reducing the influence of the elliptical hole on the overall stiffness of the test roulette, basically maintaining the original characteristics, and making the test results closer to the real working conditions.

[0086] Specifically, the average stress deformation after opening the elliptical hole in the roulette finite element model is less than 5% of the average stress of the original roulette finite element model, which can limit the local maximum strain within the material fatigue limit and reduce the influence on the fatigue life.

[0087] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A low cycle fatigue test method for an aircraft engine disk, characterized in that: The following steps are involved: S100: Finite element stress analysis of the working state of the wheel; Establish a finite element model of the wheel disc and perform finite element stress analysis under the working state of the wheel disc to obtain the temperature T1 and stress S1 of the eccentric hole part, and the temperature T2 and stress S2 of the wheel center part under the working state of the wheel disc; S200: Determination of test load at eccentric hole location; Apply a uniform temperature load of temperature T1 to the wheel finite element model and perform finite element stress analysis under the test state to determine the test speed N1 when the stress at the eccentric hole reaches S1; S300: Low cycle fatigue test on eccentric hole; A low cycle fatigue test is carried out using a test wheel at a test speed N1 and a test temperature T1 to assess the eccentric hole position; S400: Determination of the test load at the wheel center; Apply a uniform temperature load of temperature T2 to the wheel disc finite element model and perform finite element stress analysis under the test state to determine the test speed N2 when the stress at the wheel center reaches S2, the stress S3 at the eccentric hole, and the stress distribution at the eccentric hole, and use the stress S3 and temperature T2 to predict the fatigue life of the eccentric hole. When the eccentric hole cannot pass the low cycle fatigue test at the wheel center, perform step S500. When the eccentric hole can pass the low cycle fatigue test at the wheel center, perform step S600. S500: Reprocessing eccentric holes; When no elliptical hole is formed at the eccentric hole portion on the wheel disk finite element model, an elliptical hole is formed at the eccentric hole portion on the wheel disk finite element model along the axial direction, and the short radius direction of the elliptical hole is determined according to the stress distribution at the eccentric hole portion when the stress at the wheel center portion reaches S2. After the hole is formed, step S400 is performed; When an elliptical hole is formed at the eccentric hole portion on the wheel disc finite element model, the long radius and short radius of the ellipse are adjusted according to the stress distribution at the eccentric hole portion when the stress at the wheel center portion reaches S2, and step S400 is performed after the adjustment is completed; S600: Low cycle fatigue test on wheel center; When no elliptical hole is provided on the wheel finite element model, a low cycle fatigue test is carried out with a test wheel at a speed of N2 and a temperature of T2 to assess the wheel center. When an elliptical hole is opened on the finite element model of the wheel disc, an elliptical hole of the same size is opened at the same position on the test wheel disc, and a low cycle fatigue test is carried out at a rotation speed N2 and a temperature T2 to evaluate the wheel center.

2. A low cycle fatigue test method for an aircraft engine disk according to claim 1, characterized in that: In S100, when performing finite element stress analysis under the working state of the wheel disc, the working state adopts the maximum take-off state in standard weather.

3. The low cycle fatigue test method for an aircraft engine disk according to claim 1, characterized in that: In S400, the fatigue damage accumulation method is used to predict the fatigue life of the eccentric hole.

4. The low cycle fatigue test method for an aircraft engine disk according to claim 1, characterized in that: In S300 and S600, the test disc is assembled into the test rig for low cycle fatigue testing; The test device comprises an adapter shaft (1), a bolt (2) and a nut (3); the adapter shaft (1) comprises a mounting edge (11) for connecting to a test wheel disc; the mounting edge (11) is used to abut against a stop at one end of the test wheel disc in the axial direction; the mounting edge (11) and the test wheel disc are fixedly connected via the bolt (2) and the nut (3).

5. The low cycle fatigue test method for an aircraft engine disk according to claim 1, characterized in that: In S500, when an elliptical hole is opened on the wheel disc finite element model, the difference between the short radius of the elliptical hole and the radius of the eccentric hole is not less than 1 mm.

6. The low cycle fatigue test method for an aircraft engine disk according to claim 1, characterized in that: In S500, when the elliptical hole is opened, the elliptical hole and the eccentric hole are coaxially arranged.

7. The low cycle fatigue test method for an aircraft engine disk according to claim 1, characterized in that: In S500, when the long radius and short radius of the elliptical hole are adjusted according to the stress distribution at the eccentric hole when the stress at the wheel center reaches S2, when the distance from the position where the maximum stress is located at the eccentric hole to the short radius is smaller than the distance to the long radius, the long radius of the elliptical hole is increased; when the distance from the position where the maximum stress is located at the eccentric hole to the short radius is larger than the distance to the long radius, the short radius of the elliptical hole is increased.

8. The low cycle fatigue test method for an aircraft engine disk according to claim 4, characterized in that: A surface of the mounting edge (11) in the axial direction of the test wheel disc for contacting the wheel disc is a first contact surface. After the test wheel disc is provided with the elliptical hole, the contact area between the first contact surface and the test wheel disc is not less than half of the contact area before the test wheel disc is provided with the elliptical hole.

9. The low cycle fatigue test method for an aircraft engine disk according to claim 1, characterized in that: The mass change of the wheel disk finite element model after the elliptical hole is opened is less than 5%.

10. The low cycle fatigue test method for an aircraft engine disk according to claim 1, characterized in that: The average stress deformation of the wheel disk finite element model after the elliptical hole is opened is 5% less than the average stress of the original wheel disk finite element model.

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