Testing device for bearing base's fatigue resistance to alternating loads and method of use thereof

Abstract

The present invention provides a testing device for the fatigue resistance of a bearing base under alternating loads and a preparation method thereof, comprising four loading components, a mounting base, and a loading shaft; the loading shaft sequentially passes through the bearing base to be tested and the mounting base; the inner wall of the bearing base to be tested is in close contact with the outer wall of the loading shaft; the four loading components are capable of applying loads to the loading shaft, and the directions in which two adjacent loading components apply loads are perpendicular to each other. The testing device has a simple structure and is easy to operate. When in use, the cyclic load borne by the bearing base during the test is consistent with the cyclic load borne by the bearing base on the aircraft, and the fatigue life or fatigue performance of the bearing base can be accurately judged, so that the bearing base can be replaced or repaired in time before fatigue damage occurs to the bearing base. A new bearing base can also be redesigned according to the location of the damage to improve the fatigue resistance of the bearing base, making it easier to promote.

Description

Technical Field

[0001] The present invention relates to the technical field of bearing base performance testing, and in particular to a device for testing the alternating load fatigue resistance of a bearing base, and a use method and application thereof. Background Art

[0002] Rolling bearings can be used to transmit rotational driving force between various aircraft components. Examples of aircraft locations where rolling bearings are installed include propellers, landing gear, wheel hub assemblies, and other structures with drive shafts. Rolling bearings can be mounted and fixed to a bearing base, which provides stable load-bearing capacity for the rolling bearings, enabling them to stably transmit rotational driving force.

[0003] During aircraft operation, the bearing base is subjected to cyclical loads caused by rotation about its axis. This cyclical load can be considered an alternating load, making the bearing base susceptible to fatigue damage. Premature fatigue damage to the bearing base can cause the aircraft to malfunction or even lead to a serious accident. Therefore, accurately assessing the fatigue life or fatigue performance of the bearing base, so that it can be replaced or repaired before fatigue damage occurs, remains a technical challenge. Summary of the Invention

[0004] The purpose of the present invention is to provide a testing device for the fatigue resistance of bearing bases on large devices such as aircraft in the prior art, which is difficult to pre-judge. The testing device has a simple structure and is easy to operate. It can accurately judge the fatigue life or fatigue performance of the bearing base, so that the bearing base can be replaced or repaired in time before fatigue damage occurs. A new bearing base can also be redesigned according to the location of the damage to improve the fatigue resistance of the bearing base, which is convenient for promotion.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A device for testing the fatigue resistance of a bearing base under alternating loads comprises four loading components, a mounting base, and a loading shaft;

[0007] The mounting base is a cylindrical structural member, with a bearing portion provided on the top of the mounting base, on which the bearing base to be tested is provided; the loading shaft passes through the axial hole of the bearing base to be tested and extends to the bottom of the mounting base; the inner wall of the axial hole of the bearing base to be tested is in close contact with the outer wall of the loading shaft;

[0008] The four loading components are respectively connected to the top and bottom of the loading shaft, and the connection points are respectively located on the upper and lower sides of the bearing base to be tested; the four loading components can respectively apply loads to the loading shaft, and the directions in which the loads are applied by two adjacent loading components are perpendicular to each other.

[0009] The present invention provides a test device for the fatigue resistance of a bearing base under alternating loads, which mainly includes four loading components, a mounting base, and a loading shaft. The loading shaft passes through the bearing base to be tested and the mounting base in sequence. The inner wall of the bearing base to be tested is in close contact with the outer wall of the loading shaft. The four loading components can respectively apply loads to the loading shaft, and the directions in which two adjacent loading components apply loads are perpendicular to each other. The test device has a simple structure and is easy to operate. When in use, the cyclic load borne by the bearing base during the test is consistent with the cyclic load borne by the bearing base on the aircraft. The fatigue life or fatigue performance of the bearing base can be accurately judged, so that the bearing base can be replaced or repaired in time before fatigue damage occurs to the bearing base. A new bearing base can also be redesigned according to the location of the damage to improve the fatigue resistance of the bearing base, making it easier to promote.

[0010] Furthermore, the testing device also includes a base plate, and the mounting base and the four loading components are mounted on the base plate.

[0011] Furthermore, a load sensor is connected between the loading component and the loading shaft, and the load sensor is used to display the load value applied by the loading component to the loading shaft.

[0012] Furthermore, the loading component is a screw mechanism, a push rod mechanism or a pendulum mechanism.

[0013] Furthermore, the loading component includes a front support seat, a loading mechanism and a rear support seat, the loading mechanism is connected to the loading shaft, a guide rail assembly is connected between the front support seat and the rear support seat, the loading mechanism is arranged on the guide rail assembly, and the loading mechanism can slide in a limited position along the guide rail assembly.

[0014] Furthermore, the loading mechanism is a hydraulic loading device; the guide rail assembly consists of four guide rail rods arranged opposite to each other.

[0015] Furthermore, it also includes an upper cross fastener and a lower cross fastener, the upper cross fastener and the lower cross fastener are hollow structural members, and the side of the upper cross fastener and the side of the lower cross fastener are circumferentially spaced apart with four mutually perpendicular extension frames; the side of the mounting base is circumferentially spaced apart with four windows, the loading shaft passes through the upper cross fastener, the bearing base to be tested, the mounting base and the lower cross fastener in sequence, the inner wall of the upper cross fastener is in close contact with the outer wall of the loading shaft, and the inner wall of the lower cross fastener is in close contact with the outer wall of the loading shaft; the four extension frames of the lower cross fastener extend out through the four windows respectively; the upper cross fastener and the lower cross fastener are respectively fixedly connected to the loading shaft; the four loading components are respectively connected to an extension frame of the upper cross fastener and an extension frame of the lower cross fastener.

[0016] Furthermore, the upper cross fasteners are integrally connected to the corresponding extension frames, and the lower cross fasteners are integrally connected to the corresponding extension frames; and the window is connected to the bottom end of the mounting base.

[0017] Another object of the present invention is to provide a method for using the above-mentioned testing device for the bearing base's resistance to alternating load fatigue.

[0018] The method for using the above-mentioned testing device for the bearing base's resistance to alternating load fatigue comprises the following steps:

[0019] Step 1: Confirm that the target alternating load is 0~Ft, the single load period is w, the single load time is t, and the number of load cycles is N;

[0020] Step 2. Install the bearing base to be tested in a test device for fatigue resistance to alternating loads, establish a rectangular coordinate system with the bearing as the center, wherein the loading directions of the four loading components on the bearing coincide with the X-axis and the Y-axis respectively; confirm that the application direction of the target alternating load and the angle between the target alternating load direction and the x-axis are θ, divide the target load into the X-axis and the Y-axis, and calculate that the maximum alternating load on the X-axis is Fx=Ft·cos(wt), and the maximum alternating load on the Y-axis is Fy=Ft·cos(wt+π / 2);

[0021] Step 3: Apply a load of Fx to the bearing in the X-axis direction and a load of Fy to the bearing in the Y-axis direction. After N load cycles, inspect the bearing base. If no fracture or damage occurs, the bearing base is judged to have qualified the alternating fatigue resistance. If fracture or damage occurs, the bearing base is judged to have failed the alternating fatigue resistance.

[0022] The present invention provides a method for using a testing device. The method first confirms the target cyclic load and other relevant data that a bearing base will bear during actual operation on an aircraft. The testing device then applies a load of Fx to the bearing in the X-axis direction and a load of Fy to the bearing in the Y-axis direction. After N load cycles, the bearing base is tested. By adjusting the amplitude and direction of the load Fx and the amplitude and direction of the load Fy during several load cycles, the cyclic loads borne by the bearing base during fatigue testing are aligned with the cyclic loads borne by the bearing base on the aircraft. This method accurately determines the fatigue life or fatigue performance of the bearing base, allowing the bearing base to be replaced or repaired before fatigue damage occurs. Furthermore, a new bearing base can be redesigned based on the location of the damage to improve the bearing base's fatigue resistance, facilitating widespread adoption.

[0023] Furthermore, in step 3, the load applied in the X-axis direction is the sum of the loads applied by the two corresponding loading components in the X-axis direction, or the load applied by a certain loading component, and the load of the other loading component is zero; the load applied in the Y-axis direction is the sum of the loads applied by the two corresponding loading components in the Y-axis direction, or the load applied by a certain loading component, and the load of the other loading component is zero.

[0024] Another object of the present invention is to provide an application of the above-mentioned testing device for the bearing base's resistance to alternating load fatigue.

[0025] The invention discloses an application of the above-mentioned testing device for the bearing base's resistance to alternating load fatigue in testing the bearing base's resistance to alternating load fatigue in aircraft structures.

[0026] The present invention provides an application of a testing device. The bearing base in an aircraft structure is large and bears a large alternating load value. It is not easy to predict the fatigue resistance of the bearing base, which creates certain difficulties in evaluating the safety of the aircraft. The present invention provides a new use of the testing device in large structures such as aircraft, which is easy to promote.

[0027] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0028] 1. The test device for the bearing base's resistance to alternating load fatigue provided by the present invention mainly includes four loading components, a mounting base, and a loading shaft. The loading shaft passes through the bearing base to be tested and the mounting base in sequence. The inner wall of the bearing base to be tested is in close contact with the outer wall of the loading shaft. The four loading components can respectively apply loads to the loading shaft, and the directions in which two adjacent loading components apply loads are perpendicular to each other. The test device has a simple structure and is easy to operate. When in use, the cyclic loads borne by the bearing base during the test are consistent with the cyclic loads borne by the bearing base on the aircraft. The fatigue life or fatigue performance of the bearing base can be accurately judged, so that the bearing base can be replaced or repaired in time before fatigue damage occurs to the bearing base. A new bearing base can also be redesigned according to the location of the damage to improve the fatigue resistance of the bearing base, making it easier to promote.

[0029] 2. The present invention provides a method for using a testing device. First, the target cyclic load and other relevant data that the bearing base will bear during actual operation on an aircraft are confirmed. Then, using the testing device, a load Fx is applied to the bearing in the X-axis direction and a load Fy is applied to the bearing in the Y-axis direction. After N load cycles, the bearing base is tested. By adjusting the amplitude and direction of the load Fx and the amplitude and direction of the load Fy during several load cycles, the cyclic load borne by the bearing base during the fatigue test is made consistent with the cyclic load borne by the bearing base on the aircraft. This method can accurately determine the fatigue life or fatigue performance of the bearing base, thereby allowing the bearing base to be replaced or repaired in a timely manner before fatigue damage occurs. A new bearing base can also be redesigned based on the location of the damage to improve the fatigue resistance of the bearing base, facilitating its promotion.

[0030] 3. The present invention provides an application of the testing device. The bearing base in the aircraft structure is large and bears a large alternating load value. It is not easy to predict the fatigue resistance of the bearing base, which creates certain difficulties in evaluating the safety of the aircraft. The present invention provides a new use of the testing device in large structures such as aircraft, which is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural schematic diagram of a bearing base provided in an embodiment of the present application.

[0032] Figure 2 yes Figure 1 Schematic diagram of the cross-sectional structure of the bearing base.

[0033] Figure 3 This is a front view structural schematic diagram of the bearing base fatigue testing device of this application.

[0034] Figure 4This is a schematic diagram of the top view of the bearing base fatigue test device of this application.

[0035] Figure 5 This is a side structural schematic diagram of the bearing base fatigue testing device of this application.

[0036] Figure 6 This is a partial structural diagram of the bearing base fatigue testing device of this application.

[0037] Figure 7 This is a schematic diagram of the structure after the loading shaft is installed.

[0038] Figure 8 Schematic diagram of the structure of the installation base.

[0039] Figure 9 Schematic diagram of the structure of the loading shaft.

[0040] Figure 10 Schematic diagram of the structure of the upper cross fastener.

[0041] Figure 11 Schematic diagram of the structure of the lower cross fastener.

[0042] Figure 12 Schematic diagram of the structure of the support platform.

[0043] Figure 13 Schematic diagram of the load application.

[0044] Icons: 1-loading component; 11-load sensor; 12-front support seat; 121-guide rail assembly; 1211-guide rail rod; 13-loading mechanism; 14-rear support seat; 2-mounting base; 21-window; 3-loading shaft; 31-bearing part; 4-bearing base to be tested; 41-axis hole; 42-first ring body; 43-second ring body; 44-third ring body; 5-upper cross fastener; 51-extension frame; 52-T-shaped loading member; 6-lower cross fastener; 61-cross loading support; 7-base plate. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below with reference to the accompanying drawings.

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] Example 1

[0048] Figure 1 and Figure 2The structure of the bearing base 4 to be tested is disclosed, comprising a first ring body 42, a second ring body 43, and a third ring body 44 fixed to each other. The central portion of the bearing base 4 to be tested is a through hole, namely, an axial hole 41. The space enclosed by the first ring body 42 and the second ring body 43 can be used to accommodate a rolling bearing, thereby enabling the rolling bearing to be fixed to the bearing base 4 to be tested. The third ring body 44 can be used to be fixed to an aircraft, or the bearing base fatigue test device provided in the embodiments of the present application, to enable the bearing base 4 to be tested and the rolling bearing to be fixed to the aircraft.

[0049] like Figures 3 to 7 As shown, this embodiment provides a test device for the fatigue resistance of a bearing base under alternating loads, comprising four loading components 1, a mounting base 2, and a loading shaft 3. The mounting base 2 is a cylindrical structure, specifically as shown in FIG. Figure 8 As shown, a bearing portion 31 is provided on the top of the mounting base 2, and a bearing base 4 to be tested is provided on the bearing portion 31; the loading shaft 3 passes through the axial hole 41 of the bearing base 4 to be tested and extends to the bottom of the mounting base 2; the inner wall of the axial hole 41 of the bearing base 4 to be tested is in close contact with the outer wall of the loading shaft 3; the four loading components 1 are respectively connected to the top and bottom of the loading shaft 3, and the connection points are respectively located on the upper and lower sides of the bearing base 4 to be tested; the four loading components 1 can respectively apply loads to the loading shaft 3, and the directions in which the loads are applied by two adjacent loading components 1 are perpendicular to each other.

[0050] The loading component 1 may be a screw mechanism, a push rod mechanism or a pendulum mechanism, specifically Figure 3-Figure 6 As shown, the loading component 1 includes a front support seat 12, a loading mechanism 13 and a rear support seat 14. The loading mechanism 13 is connected to the loading shaft 3. Specifically, a guide rail assembly 121 is connected between the front support seat 12 and the rear support seat 14. The guide rail assembly 121 is composed of four relatively arranged guide rail rods 1211. The cross-section of the four relatively arranged guide rail rods 1211 forms the four corner points of a square. The loading mechanism 13 is arranged on the guide rail assembly 121. The tail of the loading mechanism 13 is fixed. A plate is fixedly provided, and four guide rail rods 1211 penetrate the plate. The plate can drive the loading mechanism 13 to slide along the guide rail assembly 121. At the same time, another plate is fixedly connected to the front support seat 12. The front section of the loading mechanism 13 passes through the other plate and is connected to the load sensor 11. The load sensor 11 is used to display the load value applied by the loading component 1 to the loading shaft 3. When the loading mechanism 13 slides along the guide rail rods 1211, the loading mechanism 13 can slide relative to the plate on the front support seat 12. Specifically, the loading mechanism 13 is a hydraulic loading device.

[0051] Specifically, such as Figure 3-Figure 7 and Figure 10 and Figure 11 As shown, it also includes an upper cross fastener 5 and a lower cross fastener 6. The upper cross fastener 5 and the lower cross fastener 6 are hollow structural members. Four mutually perpendicular extension frames 51 are circumferentially spaced apart on the side of the upper cross fastener 5 and the side of the lower cross fastener 6.

[0052] like Figure 8 As shown, four windows 21 are provided at circumferential intervals on the side of the mounting base 2, and the loading shaft 3 passes through the upper cross fastener 5, the bearing base 4 to be tested, the mounting base 2 and the lower cross fastener 6 in sequence. The inner wall of the upper cross fastener 5 is in close contact with the outer wall of the loading shaft 3, and the inner wall of the lower cross fastener 6 is in close contact with the outer wall of the loading shaft 3; the four extension frames 51 of the lower cross fastener 6 extend through the four windows 21 respectively; the upper cross fastener 5 and the lower cross fastener 6 are fixedly connected to the loading shaft 3 respectively; the four loading components 1 are respectively connected to an extension frame 51 of the upper cross fastener 5 and an extension frame 51 of the lower cross fastener 6. Preferably, the upper cross fastener 5 is integrally connected to the corresponding extension frame 51, and the lower cross fastener 6 is integrally connected to the corresponding extension frame 51; the window 21 is connected to the bottom end of the mounting base 2. Preferably, a cross-loading support member 61 is also included, specifically as shown in FIG. Figure 12 As shown, the cross-load support member 61 can be disposed below the extension frame 51 of the lower cross fastener 6 , thereby increasing the stability of the lower cross fastener 61 .

[0053] Among them, Figure 9 As shown, the specific structure of the loading shaft 3 is divided into three parts. The middle cylindrical part has the largest diameter, and the outer wall of the middle cylindrical part fits tightly with the inside of the axial hole of the bearing base 4 to be tested; second cylindrical parts are respectively provided on both sides of the middle cylindrical part, and the diameter of the second cylindrical part is smaller than the diameter of the middle cylindrical part, and the second cylindrical parts are respectively located on the outside of the bearing base to be tested, on the upper and lower sides; at the same time, a third cylindrical part is provided at one end of the second cylindrical part away from the middle cylindrical part, and the diameter of the third cylindrical part is smaller than the diameter of the second cylindrical part; the upper cross fastener 5 and the lower cross fastener 6 are respectively sleeved on the third cylindrical part, and at the same time, the outer wall of the third cylindrical part is provided with a thread, and the upper cross fastener 5 and the lower cross fastener 6 can be fixedly connected to the loading shaft by a nut.

[0054] Specifically, such as Figure 10 and Figure 11As shown, the end of the extension bracket 51 is provided with a latch hole. A T-shaped loading member is connected to the end of the loading mechanism 13 near the bearing base 4 to be tested. Both ends of the T-shaped loading member are provided with latch holes that mate with the extension bracket 51. The latch holes at both ends of the T-shaped horizontal line respectively form a pin connection with an extension bracket 51 of the upper cross fastener 5 and an extension bracket 51 of the lower cross fastener 6. Preferably, the bearing base fatigue test apparatus is mounted on a base plate 7, which serves as a test bench.

[0055] The testing device has a simple structure and is easy to operate. When in use, the cyclic load borne by the bearing base during the test is consistent with the cyclic load borne by the bearing base on the aircraft. It can accurately judge the fatigue life or fatigue performance of the bearing base, so that the bearing base can be replaced or repaired in time before fatigue damage occurs. A new bearing base can also be redesigned according to the location of the damage to improve the fatigue resistance of the bearing base, which is convenient for promotion.

[0056] Example 2

[0057] Example 2 provides a method for using the device system of Example 1, which specifically includes the following steps:

[0058] Step 1: Confirm that the target alternating load is 0~Ft, the single load period is w, the single load time is t, and the number of load cycles is N;

[0059] Step 2: Figure 13 As shown, the bearing base 4 to be tested is installed in a test device for fatigue resistance to alternating loads. A rectangular coordinate system is established with the bearing as the center, wherein the loading directions of the four loading components 1 on the bearing coincide with the X-axis and the Y-axis respectively. The application direction of the target alternating load and the angle between the target alternating load direction and the x-axis are confirmed to be θ, and the target load is divided into the X-axis and the Y-axis. By calculation, it can be found that the maximum alternating load on the X-axis is Fx = Ft·cos(wt), and the maximum alternating load on the Y-axis is Fy = Ft·cos(wt+π / 2);

[0060] Step 3: Apply a load of Fx to the bearing in the X-axis direction and a load of Fy to the bearing in the Y-axis direction. After N load cycles, inspect the bearing base. If no fracture or damage occurs, the bearing base is judged to have qualified the alternating fatigue resistance. If fracture or damage occurs, the bearing base is judged to have failed the alternating fatigue resistance.

[0061] Among them, in step 3, the load applied in the X-axis direction is the sum of the loads applied by the two loading components 1 corresponding to the X-axis direction, or the load loaded by a certain loading component 1, and the load of the other loading component 1 is zero; the load applied in the Y-axis direction is the sum of the loads applied by the two loading components 1 corresponding to the Y-axis direction, or the load loaded by a certain loading component 1, and the load of the other loading component 1 is zero.

[0062] Optionally, when the maximum load amplitude is at the target load, after the Nth load cycle, the bearing base is removed from the bearing base fatigue test device, and when the bearing base has not suffered fatigue damage, the fatigue life of the bearing base under the target load is greater than N; when the bearing base has suffered fatigue damage, the fatigue life of the bearing base under the target load is less than or equal to N.

[0063] The present invention provides a method for using a testing device. The method first confirms the target cyclic load and other relevant data that a bearing base will bear during actual operation on an aircraft. The testing device then applies a load of Fx to the bearing in the X-axis direction and a load of Fy to the bearing in the Y-axis direction. After N load cycles, the bearing base is tested. By adjusting the amplitude and direction of the load Fx and the amplitude and direction of the load Fy during several load cycles, the cyclic loads borne by the bearing base during fatigue testing are aligned with the cyclic loads borne by the bearing base on the aircraft. This method accurately determines the fatigue life or fatigue performance of the bearing base, allowing the bearing base to be replaced or repaired before fatigue damage occurs. Furthermore, a new bearing base can be redesigned based on the location of the damage to improve the bearing base's fatigue resistance, facilitating widespread adoption.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device for testing the fatigue resistance of a bearing base under alternating loads, characterized in that: It includes four loading components, a mounting base, and a loading shaft; The mounting base is a cylindrical structural member, with a bearing portion provided on the top of the mounting base, on which the bearing base to be tested is provided; the loading shaft passes through the axial hole of the bearing base to be tested and extends to the bottom of the mounting base; the inner wall of the axial hole of the bearing base to be tested is in close contact with the outer wall of the loading shaft; The four loading components are respectively connected to the top and bottom of the loading shaft, and the connection points are respectively located on the upper and lower sides of the bearing base to be tested; the four loading components can respectively apply loads to the loading shaft, and the directions in which the loads are applied by two adjacent loading components are perpendicular to each other.

2. The device for testing the bearing base's resistance to alternating load fatigue according to claim 1, characterized in that: A load sensor is connected between the loading component and the loading shaft component, and the load sensor is used to display the load value applied by the loading component to the loading shaft component.

3. The device for testing the bearing base's resistance to alternating load fatigue according to claim 1, characterized in that: The loading component is a screw mechanism, a push rod mechanism or a pendulum mechanism.

4. The device for testing the bearing base's resistance to alternating load fatigue according to claim 3, characterized in that: The loading component includes a front support seat, a loading mechanism and a rear support seat. The loading mechanism is connected to the loading shaft. A guide rail assembly is connected between the front support seat and the rear support seat. The loading mechanism is arranged on the guide rail assembly and can slide along the guide rail assembly.

5. The device for testing the bearing base's resistance to alternating load fatigue according to claim 4, characterized in that: The loading mechanism is a hydraulic loading device; the guide rail assembly consists of four guide rail rods arranged opposite to each other.

6. The device for testing the bearing base's resistance to alternating load fatigue according to any one of claims 1 to 5, characterized in that: It also includes an upper cross fastener and a lower cross fastener, wherein the upper cross fastener and the lower cross fastener are hollow structural members, and four mutually perpendicular extension frames are circumferentially spaced apart on the side of the upper cross fastener and the side of the lower cross fastener; Four windows are provided at circumferential intervals on the side of the mounting base. The loading shaft passes through the upper cross fastener, the bearing base to be tested, the mounting base, and the lower cross fastener in sequence. The inner wall of the upper cross fastener is in close contact with the outer wall of the loading shaft, and the inner wall of the lower cross fastener is in close contact with the outer wall of the loading shaft. Four extension frames of the lower cross fastener extend through the four windows respectively. The upper cross fastener and the lower cross fastener are fixedly connected to the loading shaft respectively. The four loading components are respectively connected to an extension bracket of the upper cross fastener and an extension bracket of the lower cross fastener.

7. The device for testing the bearing base's resistance to alternating load fatigue according to claim 6, characterized in that: The upper cross fastener is integrally connected to the corresponding extension frame, and the lower cross fastener is integrally connected to the corresponding extension frame; the window is communicated with the bottom end of the mounting base.

8. A method for using the device for testing the bearing base's resistance to alternating load fatigue according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Confirm that the target alternating load is 0~Ft, the single load period is w, the single load time is t, and the number of load cycles is N; Step 2. Install the bearing base to be tested in a test device for fatigue resistance to alternating loads, establish a rectangular coordinate system with the bearing as the center, wherein the loading directions of the four loading components on the bearing coincide with the X-axis and the Y-axis respectively; confirm that the application direction of the target alternating load and the angle between the target alternating load direction and the x-axis are θ, divide the target load into the X-axis and the Y-axis, and calculate that the maximum alternating load on the X-axis is Fx=Ft·cos(wt), and the maximum alternating load on the Y-axis is Fy=Ft·cos(wt+π / 2); Step 3: Apply a load of Fx to the bearing in the X-axis direction and a load of Fy to the bearing in the Y-axis direction. After N load cycles, inspect the bearing base. If no fracture or damage occurs, the bearing base is judged to have qualified the alternating fatigue resistance. If fracture or damage occurs, the bearing base is judged to have failed the alternating fatigue resistance.

9. The method for using the device for testing the bearing base's resistance to alternating load fatigue according to claim 8, characterized in that: In step 3, the load applied in the X-axis direction is the sum of the loads applied by the two loading components corresponding to the X-axis direction, or the load applied by a certain loading component, and the load of the other loading component is zero; the load applied in the Y-axis direction is the sum of the loads applied by the two loading components corresponding to the Y-axis direction, or the load applied by a certain loading component, and the load of the other loading component is zero.

10. Use of the device for testing the fatigue resistance of a bearing base under alternating loads according to any one of claims 1 to 7 in testing the fatigue resistance of a bearing base under alternating loads in an aircraft structure.

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