Fretting fatigue test device

Abstract

The invention provides a fretting fatigue test device, and belongs to the technical field of test devices. The device comprises a fatigue testing machine for providing a circulating axial load, a transverse load loading mechanism for providing a transverse load required by a test, and a loading test bench for providing a test platform for the transverse load loading mechanism. According to the invention, the constructed structure device is combined with the fatigue testing machine, the fretting fatigue test is carried out on the common fatigue testing machine, the centering position precision of the fretting pad and the sample is ensured through the designed loading test bed and the transverse load loading mechanism, the fretting pad can apply the same transverse load on the two sides of the sample, and the accuracy of the fretting fatigue test is ensured. According to the fretting fatigue testing device, the problems of uneven transverse load stress and the like in the fretting fatigue testing process are solved, the fretting fatigue testing accuracy is improved, the offset amplitude can be continuously applied, the influence of actual complex working conditions on parts can be better simulated, and the engineering applicability of the test is improved.

Description

Technical Field

[0001] The invention relates to the technical field of testing devices, and in particular to a micro-motion fatigue testing device. Background Art

[0002] Fretting fatigue refers to the complex wear caused by contact loads between two contacting structural units under cyclic loads and small displacements and relative sliding. When close-contact components are subjected to alternating fatigue loads, fatigue cracks will easily form on their surfaces, leading to fretting fatigue failure of the structure. Fretting fatigue is a phenomenon that is widely found in closely fitting parts in the fields of automobiles, railways, ships, aerospace, etc. Studies have shown that fretting fatigue has a huge impact on the material of parts, and its fatigue strength can be reduced by 2 to 5 times. In order to better analyze the fretting fatigue behavior of materials and reveal their loss failure mechanisms, material-level fretting fatigue testing has received much attention.

[0003] In order to study the fretting fatigue characteristics of materials, fretting fatigue tests need to be carried out in the laboratory. Since there is no unified test standard and complete test equipment for the study of fretting fatigue so far, researchers can only design and modify relevant equipment according to actual conditions. Ordinary uniaxial fatigue testing machines cannot apply lateral loads to standard test pieces, so they cannot be directly used for fretting fatigue tests. At present, the method of testing lateral loads mostly uses simultaneous loading on both sides. Even the control program can hardly ensure that the normal loads on the left and right sides are of the same size. Therefore, the specimen may be subjected to additional bending moment, which will also affect the accuracy of the centering position of the fretting pad. Summary of the invention

[0004] In view of this, in order to solve the technical problem that the uneven force of the lateral load during the existing micro-motion fatigue test affects the centering position accuracy of the micro-motion pad and the specimen. The present invention provides a micro-motion fatigue test device, which outputs the load through a single-sided actuator and forms a closed structure together with components such as a frame, a push rod, a limit seat, a micro-motion pad and a specimen to ensure the stable loading of the lateral load during the test. The micro-motion pad and the specimen position are adjusted by loading the test bench base, the limit seat and the positioner, thereby improving the centering position accuracy of the micro-motion fatigue test.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A micro-motion fatigue test device comprises a fatigue test machine for providing a cyclic axial load, a lateral load loading mechanism for providing a lateral load required for the test, and a loading test bench for providing a test platform for the lateral load loading mechanism;

[0007] The loading test bench comprises:

[0008] Loading test bench base;

[0009] A frame, disposed on the base of the loading test bench, for providing lateral load support for the lateral load loading mechanism;

[0010] A flexible pad, located between the base of the loading test bench and the frame, for offsetting the load loss caused by the lateral force;

[0011] The lateral load loading mechanism comprises:

[0012] A left limit seat and a right limit seat, both of which are arranged on the loading test bench base and are slidably connected to the loading test bench base;

[0013] A left push rod, one end of which is connected to the left end of the frame, and the other end of which is connected to the left limit seat;

[0014] an actuator connected to the right side of the frame;

[0015] A right push rod, one end of which is connected to the output end of the actuator, and the other end of which is connected to the right side of the frame;

[0016] The micro-motion pads are respectively arranged on the left limit seat and the right limit seat, and are driven by the actuator to contact the sample and apply a lateral load to the sample;

[0017] A lateral load sensor is used to monitor the magnitude of the lateral load;

[0018] The lateral load controller is used to control the actuator to apply a lateral load of a predetermined magnitude.

[0019] Preferably, the loading test bench further comprises:

[0020] A left clamping seat and a left fixing seat, which cooperate with each other and are connected to the guide column of the fatigue testing machine;

[0021] A right clamping seat and a right fixing seat, which cooperate with each other and are connected to the guide column of the fatigue testing machine;

[0022] The two ends of the loading test bench base are respectively arranged on the left fixing seat and the right fixing seat.

[0023] Preferably, the lateral load loading mechanism further comprises:

[0024] A left micro-motion pad fixing block, which is located on the left limit seat and is used to press the micro-motion pad located on the left limit seat;

[0025] A right micro-motion pad fixing block, located on the right limit seat, and used for pressing the micro-motion pad located on the right limit seat;

[0026] The positioners are respectively arranged on the left limit seat and the right limit seat, and are used to accommodate the micro-motion pad.

[0027] Preferably, the positioner is a through slot respectively opened on the left limit seat and the right limit seat, the micro-motion pad is placed in the through slot, the size of the through slot is larger than the size of the micro-motion pad and the sample, and the thickness is lower than the thickness of the micro-motion pad.

[0028] Preferably, the left limit seat is composed of a left limit lower seat slidably connected to the loading test bench base and a left limit upper seat covering the left limit lower seat;

[0029] The right limit seat is composed of a right limit lower seat slidably connected to the loading test bench base and a right limit upper seat covering the right limit lower seat;

[0030] The left limit upper seat and the right limit upper seat are both provided with adjustment screws for leveling to ensure that the micro-motion pads are on the same horizontal plane.

[0031] Preferably, an offset amplitude device is also included for providing additional offset amplitude for the test.

[0032] Preferably, the offset amplitude device comprises:

[0033] A sample clamp, used for clamping the sample;

[0034] An offset amplitude disk, which is arranged on the fatigue testing machine;

[0035] The sample holder is meshedly connected with the offset amplitude disk, and the rotation of the offset amplitude disk is converted into the translation of the sample holder.

[0036] Preferably, the sample fixture is provided with teeth, and the offset amplitude disk is provided with a planar thread meshing with the gear.

[0037] Preferably, the fatigue testing machine comprises:

[0038] Host base;

[0039] An upper crossbeam, which is located on the main engine base;

[0040] A lifting cylinder, one end of which is connected to the main engine base, and the other end of which is connected to the upper crossbeam;

[0041] A guide column, which is arranged on the mainframe base and passes through the through holes opened at both ends of the upper crossbeam;

[0042] A centering device, a load sensor and a hydraulic upper clamp are coaxially connected to the bottom of the upper beam in sequence from top to bottom;

[0043] A lower clamp is arranged on the mainframe base and is arranged opposite to the upper clamp;

[0044] A controller system, used to control the lifting and lowering of the lifting cylinder and the opening and closing of the upper clamp and the lower clamp;

[0045] The servo hydraulic oil source is used to provide the required flow and pressure for the lifting cylinder.

[0046] Preferably, the flexible pad is a polyamide nylon pad.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The micro-motion fatigue test device provided by the present invention outputs load through a single-side actuator, and forms a closed structure together with the frame, the ejector, the limit seat, the micro-motion pad and the sample, thereby ensuring the stable loading of the lateral load during the test. The micro-motion pad and the sample position are adjusted by the loading test bench base, the limit seat and the positioner, thereby improving the centering position accuracy of the micro-motion fatigue test.

[0049] The offset amplitude device continuously applies the offset amplitude during the test, which can better simulate the influence of actual complex working conditions on parts and improve the engineering applicability of the test.

[0050] In summary, the present invention realizes micro-motion fatigue test on ordinary fatigue testing machine by combining the constructed structural device with fatigue testing machine. The centering position accuracy of micro-motion pad and specimen is guaranteed by the designed loading test bench and lateral load loading mechanism. The micro-motion pad can apply the same lateral load on both sides of the specimen, which solves the problem of uneven lateral load force during micro-motion fatigue test, improves the accuracy of micro-motion fatigue test, and can continuously apply offset amplitude, which can better simulate the influence of actual complex working conditions on parts and improve the engineering applicability of the test.

[0051] Other advantages of the present invention will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0053] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0054] Figure 1 It is a schematic diagram of the overall structure of the fretting fatigue loading device and the test device;

[0055] Figure 2 This is a schematic diagram of the fatigue testing machine structure;

[0056] Figure 3 This is a schematic diagram of the loading test bench structure;

[0057] Figure 4 This is a partial detail diagram of the loading test bench;

[0058] Figure 5 It is a schematic diagram of the structure of the lateral load loading mechanism;

[0059] Figure 6 for Figure 5 The enlarged view of point A in the middle;

[0060] Figure 7 Schematic diagram of the principle of applying the offset amplitude;

[0061] In the figure, 1, fatigue testing machine; 2, loading test bench; 3, lateral load loading mechanism; 4, offset amplitude device; 11, upper crossbeam; 12, lifting cylinder; 13, guide column; 14, main engine base; 15, centering device; 16, load sensor; 17, upper clamp; 18, lower clamp; 19, controller system; 110, servo hydraulic oil source; 21, left clamping seat; 22, left fixed seat; 23, test bench fixing bolt; 24, loading test bench base; 25, rectangular frame; 26, polyamide nylon pad; 27, right fixed seat; 28, right clamping seat; 29, hexagon socket bolt; 3 1. Seat; 32. Left push rod; 33. Left micro-motion pad fixing block; 34. Right micro-motion pad fixing block; 35. Right push rod; 36. Connecting joint; 37. Connecting seat; 38. Transverse load sensor; 39. Transmission rod; 310. Actuator; 311. Left limit lower seat; 312. Left limit upper seat; 313. Adjusting screw; 314. Micro-motion pad fixing bolt; 315. Specimen; 316. Micro-motion pad; 317. Positioner; 318. Right limit lower seat; 319. Right limit upper seat; 320. Transverse load controller; 41. Specimen fixture; 42. Offset amplitude disk; 43. Plane thread. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0063] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", "top / bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0064] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] like Figure 1 , 3 -6, the present invention provides a micro-motion fatigue test device, including a fatigue test machine 1 for providing a cyclic axial load, a lateral load loading mechanism 3 for providing a lateral load required for the test, and a loading test bench 2 for providing a test platform for the lateral load loading mechanism 3;

[0066] Wherein, the lateral load loading mechanism 3 is fixed in the frame of the fatigue testing machine 1 through the loading test bench 2;

[0067] The loading test bench 2 comprises:

[0068] The loading test bench base 24 is preferably leveled using an optical level to improve the overall position accuracy of the lateral load loading mechanism 3 to ensure accurate loading position for the micro-fatigue test;

[0069] A frame, disposed on the loading test bench base 24, for providing lateral load support for the lateral load loading mechanism 3;

[0070] The frame is preferably a rectangular frame 25, and the frame provides lateral load support for the lateral load loading mechanism 3, which means that the two ends of the lateral load loading mechanism 3 are respectively connected to the two ends of the frame, providing a supporting platform for the lateral load provided by the lateral load loading mechanism 3;

[0071] A flexible pad, which has a certain flexibility and is located between the loading test bench base 24 and the frame, is used to offset the load loss caused by the lateral force to ensure that the lateral loads loaded on both sides are consistent in magnitude;

[0072] The lateral load loading mechanism 3 comprises:

[0073] The left limit seat and the right limit seat are both arranged on the loading test bench base 24 and are slidably connected to the loading test bench base 24; wherein the bottom of the left limit seat and the right limit seat are preferably provided with a slider to cooperate with the guide rail on the loading test bench base 24, which can limit them to only slide horizontally;

[0074] A left top rod 32, one end of which is connected to the left end of the frame, and the other end of which is connected to the left limit seat, wherein the left top rod 32 is preferably connected to the left end of the frame through a cushion seat 31;

[0075] The actuator 310 is connected to the right side of the frame to achieve unilateral application of the lateral load, which can avoid the problem that the left and right sides are loaded at the same time in the prior art, and even the control program can hardly ensure that the normal loads on the left and right sides can be consistent in size. The unilateral application of the lateral load can ensure that the lateral loads on both sides of the sample 315 are the same, thereby improving the accuracy;

[0076] A right push rod 35, one end of which is connected to the output end of the actuator 310, and the other end is connected to the right side of the frame;

[0077] The micro-motion pads 316 are respectively arranged on the left limit seat and the right limit seat, and are driven by the actuator 310 to contact the sample 315 and apply a lateral load to the sample 315;

[0078] A lateral load sensor 38 is used to monitor the magnitude of the lateral load. The magnitude of the lateral load of the sample 315 can be obtained in real time through the lateral load sensor 38, and can be adjusted in real time according to the lateral load controller 320 described below;

[0079] The lateral load controller 320 is used to control the actuator 310 to apply a lateral load of a predetermined magnitude.

[0080] The present invention realizes the micro-motion fatigue test on the ordinary fatigue testing machine 1 by combining the constructed loading test bench, the lateral load loading mechanism 3 and the fatigue testing machine 1. The centering position accuracy of the micro-motion pad 316 and the sample 315 is guaranteed by the designed loading test bench and the lateral load loading mechanism 3. The micro-motion pad 316 can apply the same lateral load on both sides of the sample 315, which solves the problem of uneven lateral load force during the micro-motion fatigue test and improves the accuracy of the micro-motion fatigue test.

[0081] like Figure 3 As shown, the present invention provides an embodiment of a loading test bench, wherein the loading test bench further comprises:

[0082] The left clamping seat 21 and the left fixing seat 22 are connected to the guide column of the fatigue testing machine 1 in cooperation with each other;

[0083] The right clamping seat 28 and the right fixing seat 27 are connected to the guide column of the fatigue testing machine 1 in cooperation with each other;

[0084] Two ends of the loading test bench base 24 are respectively disposed on the left fixing seat 22 and the right fixing seat 27 .

[0085] In the present invention, it is preferred that the left clamping seat 21 and the left fixing seat 22 are butt-jointed together and sleeved on the guide column on the left side of the fatigue testing machine 1, and are connected and fastened by the hexagon socket bolt 29; the right clamping seat 28 and the right fixing seat 27 are butt-jointed together and sleeved on the guide column on the right side of the fatigue testing machine 1, and are connected and fastened by the hexagon socket bolt 29; in this way, the loading test bench is fixed to the fatigue testing machine 1.

[0086] The two ends of the loading test bench base 24 are preferably screwed to the left fixing seat 22 and the right fixing seat 27 through the test bench fixing bolts 23 to achieve the fixed connection of the loading test bench base 24 .

[0087] like Figure 4-6 As shown, in the present invention, the lateral load loading mechanism 3 also includes:

[0088] A left micro-motion pad fixing block 33, which is located on the left limit seat and is used to press the micro-motion pad located on the left limit seat;

[0089] A right micro-motion pad fixing block 34, which is located on the right limit seat and is used to press the micro-motion pad located on the right limit seat;

[0090] The positioner 317 is respectively disposed on the left limit seat and the right limit seat for accommodating the micro-motion pad, wherein the shape of the positioner 317 is specifically designed for the geometric shape and size of the micro-motion pad 316 and the sample 315 .

[0091] Among them, the left micro-motion pad fixing block 33 and the right micro-motion pad fixing block 34 are preferably fixed to the left limit seat and the right limit seat through the micro-motion pad fixing bolts 314, and are preferably fixed to the left limit upper seat 312 and the right limit upper seat 319 described below.

[0092] In the present invention, the positioner 317 is a through slot respectively opened on the left limit seat and the right limit seat, and the micro-motion pad is placed in the through slot. The size of the through slot is larger than the size of the micro-motion pad 316 and the sample 315, and the thickness is lower than the thickness of the micro-motion pad. The positioner 317 only plays a positioning role and does not exert influence on the micro-motion pad 316 and the sample 315.

[0093] In the present invention, the left limit seat is composed of a left limit lower seat 311 slidably connected to the loading test bench base 24 and a left limit upper seat 312 covering the left limit lower seat 311;

[0094] The right limit seat is composed of a right limit lower seat 318 slidably connected to the loading test bench base 24 and a right limit upper seat 319 covering the right limit lower seat 318;

[0095] The left limit upper seat 312 and the right limit upper seat 319 are both provided with adjustment screws 313 for leveling to ensure that the micro-motion pads are on the same horizontal plane. Specifically, the adjustment screws 313 can be adjusted with the help of an optical level to level the left limit upper seat 312 and the right limit upper seat 319 to ensure that the micro-motion pads are on the same horizontal plane.

[0096] It should be noted that the left limit upper seat 312 is on the left limit lower seat 311, and the adjusting screw 313 can be adjusted for leveling with the help of an optical level; the right limit lower seat 318 is on the right limit upper seat 319, and the adjusting screw 313 can be adjusted for leveling with the help of an optical level; the bottom of the left limit lower seat 311 and the right limit lower seat 318 are both provided with sliders that cooperate with the guide rails on the loading test bench base 24 to limit them to horizontal sliding.

[0097] In the present invention, the transmission rod 39 (output end) of the actuator 310 is preferably coaxially connected to the connection seat 37, the connection joint 36 on the connection seat 37 is coaxially connected to the right push rod 35, and the lateral load sensor 38 is preferably arranged on the connection seat 37. The actuator 310 and the lateral load sensor 38 are both controlled by the lateral load controller 320, which can control the actuator 310 to output the required lateral load, and can also adjust the size of the lateral load applied by the actuator 310 according to the lateral load detected by the lateral load sensor 38.

[0098] In the above-mentioned lateral load loading mechanism 3 provided by the present invention, the actuator 310 outputs the load, and together with the rectangular frame 25, the pad 31, the left push rod 32, the left limit upper seat 312, the micro-motion pad 316, the specimen 315, the right limit upper seat 319, the right push rod 35, the connecting joint 36, the connecting seat 37, the lateral load sensor 38, the transmission rod 39 and other components form a closed mechanical structure to ensure the stable loading of the lateral load during the test.

[0099] like Figure 1 , 3 -4, preferably, it also includes an offset amplitude device 4 for providing an additional offset amplitude for the test, which can provide an additional offset amplitude for the test, better simulate the impact of actual complex working conditions on parts, and improve the engineering applicability of the test.

[0100] like Figure 3 As shown, in the present invention, the offset amplitude device 4 includes:

[0101] A sample clamp 41, used for clamping the sample, and the sample clamp 41 is preferably designed to be in a right angle shape;

[0102] An offset amplitude disk 42, which is arranged on the fatigue testing machine 1;

[0103] The sample holder 41 is meshedly connected with the offset amplitude disk 42 , and the rotation of the offset amplitude disk 42 is converted into the translation of the sample holder 41 .

[0104] like Figure 4 , 7 As shown, in the present invention, the sample fixture 41 is provided with teeth, and the offset amplitude disk 42 is provided with a planar thread 43 meshing with the gear.

[0105] The sample fixture 41 can multiply the sample offset amplitude c into a translation value d by the triangle amplification principle, and the mathematical relationship formula is:

[0106] Among them, a is the length of the small triangle side (half the parallel length of the specimen), and b is the length of the enlarged triangle side.

[0107] like Figure 2 As shown, in the present invention, the fatigue testing machine includes:

[0108] Host base 14;

[0109] An upper crossbeam 11, which is located on the mainframe base 14;

[0110] A lifting cylinder 12, one end of which is connected to the mainframe base 14 and the other end of which is connected to the upper beam 11, can drive the upper beam 11 to move up and down along the guide column 13 described below, thereby controlling the movement of the upper clamp 17 described below to adjust the position of the upper clamp 17;

[0111] A guide column 13, which is disposed on the mainframe base 14 and passes through the through holes opened at both ends of the upper crossbeam 11 to limit the upper crossbeam 11 to move only axially;

[0112] A centering device 15, a load sensor 16 and a hydraulic upper clamp 17 are coaxially connected to the bottom of the upper cross beam 11 in sequence from top to bottom;

[0113] A lower clamp 18 is disposed on the host base 14 and is disposed opposite to the upper clamp 17;

[0114] A controller system 19, used to control the lifting and lowering of the lifting cylinder 12, and the opening and closing of the upper clamp 17 and the lower clamp 18;

[0115] The servo hydraulic oil source 110 is used to provide the lifting cylinder 12 with the required flow and pressure.

[0116] In the present invention, the flexible pad is a polyamide nylon pad 26 .

[0117] The above are only preferred specific implementations of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and improved concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A fretting fatigue test device, characterized in that: It includes a fatigue testing machine for providing a cyclic axial load, a lateral load loading mechanism for providing a lateral load required for the test, and a loading test bench for providing a test platform for the lateral load loading mechanism; The loading test bench comprises: Loading test bench base; A frame, disposed on the base of the loading test bench, for providing lateral load support for the lateral load loading mechanism; A flexible pad, located between the base of the loading test bench and the frame, for offsetting the load loss caused by the lateral force; The lateral load loading mechanism comprises: A left limit seat and a right limit seat, both of which are arranged on the loading test bench base and are slidably connected to the loading test bench base; A left push rod, one end of which is connected to the left end of the frame, and the other end of which is connected to the left limit seat; an actuator connected to the right side of the frame; A right push rod, one end of which is connected to the output end of the actuator, and the other end of which is connected to the right side of the frame; The micro-motion pads are respectively arranged on the left limit seat and the right limit seat, and are driven by the actuator to contact the sample and apply a lateral load to the sample; A lateral load sensor is used to monitor the magnitude of the lateral load; The lateral load controller is used to control the actuator to apply a lateral load of a predetermined magnitude.

2. A fretting fatigue testing device according to claim 1, characterized in that: The loading test bench also includes: A left clamping seat and a left fixing seat, which cooperate with each other and are connected to the guide column of the fatigue testing machine; A right clamping seat and a right fixing seat, which cooperate with each other and are connected to the guide column of the fatigue testing machine; The two ends of the loading test bench base are respectively arranged on the left fixing seat and the right fixing seat.

3. A fretting fatigue testing device according to claim 1, characterized in that: The lateral load loading mechanism also includes: A left micro-motion pad fixing block, which is located on the left limit seat and is used to press the micro-motion pad located on the left limit seat; A right micro-motion pad fixing block, located on the right limit seat, and used for pressing the micro-motion pad located on the right limit seat; The positioners are respectively arranged on the left limit seat and the right limit seat, and are used to accommodate the micro-motion pad.

4. A fretting fatigue testing device according to claim 3, characterized in that: The positioner is a through slot respectively opened on the left limit seat and the right limit seat, the micro-motion pad is placed in the through slot, the size of the through slot is larger than the size of the micro-motion pad and the sample, and the thickness is lower than the thickness of the micro-motion pad.

5. A fretting fatigue testing device according to claim 3, characterized in that: The left limit seat is composed of a left limit lower seat slidably connected to the loading test bench base and a left limit upper seat covering the left limit lower seat; The right limit seat is composed of a right limit lower seat slidably connected to the loading test bench base and a right limit upper seat covering the right limit lower seat; The left limit upper seat and the right limit upper seat are both provided with adjustment screws for leveling to ensure that the micro-motion pads are on the same horizontal plane.

6. A fretting fatigue testing device according to claim 1, characterized in that: Also included is an offset amplitude device for providing additional offset amplitude for testing.

7. A fretting fatigue testing device according to claim 6, characterized in that: The offset amplitude device comprises: A sample clamp, used for clamping the sample; An offset amplitude disk, which is arranged on the fatigue testing machine; The sample holder is meshedly connected with the offset amplitude disk, and the rotation of the offset amplitude disk is converted into the translation of the sample holder.

8. A fretting fatigue testing device according to claim 7, characterized in that: The sample fixture is provided with tooth patterns, and the offset amplitude disk is provided with a plane thread meshing with the gear.

9. The fretting fatigue testing device according to claim 1, characterized in that: The fatigue testing machine comprises: Host base; An upper crossbeam, which is located on the main engine base; A lifting cylinder, one end of which is connected to the main engine base, and the other end of which is connected to the upper crossbeam; A guide column, which is arranged on the mainframe base and passes through the through holes opened at both ends of the upper crossbeam; A centering device, a load sensor and a hydraulic upper clamp are coaxially connected to the bottom of the upper beam in sequence from top to bottom; A lower clamp is arranged on the mainframe base and is arranged opposite to the upper clamp; A controller system, used to control the lifting and lowering of the lifting cylinder and the opening and closing of the upper clamp and the lower clamp; The servo hydraulic oil source is used to provide the required flow and pressure for the lifting cylinder.

10. A fretting fatigue testing device according to any one of claims 1 to 9, characterized in that: The flexible pad is a polyamide nylon pad.

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