Induction heating type micro-oscillation fatigue test device and method

Abstract

The present disclosure provides an inductive heating type fretting fatigue test device and method, and relates to the technical field of material performance testing. The device comprises a clamping mechanism for clamping a fretting fatigue test piece and a pad, one end of the pad abutting against the surface of the test piece and transmitting a normal load to the test piece; a loading mechanism connected with the clamping mechanism for loading the test piece; and a heating mechanism comprising multiple groups of inductive coils and heating bodies, the heating mechanism heating the heating bodies by using the inductive coils, and the heating bodies providing a high-temperature environment for the test piece through heat radiation. The fretting fatigue test device and method provided by the present disclosure can prevent the pad from following the test piece during the loading process, prevent the eccentric loading of the fretting fatigue load during the test process, and heat the test piece based on the electromagnetic induction principle, thereby improving the heating efficiency, reducing the space required for the test, and facilitating the observation and analysis of the damage evolution of the fretting fatigue test piece during the test process.

Description

Technical Field

[0001] This disclosure relates to the field of material performance testing technology, and more specifically, to an induction heating type fretting fatigue testing device and method. Background Technology

[0002] Fretting fatigue refers to the phenomenon where, under cyclic loading, mating components undergo small-amplitude relative sliding, leading to a decrease in structural fatigue strength or premature fracture. The machinery industry widely uses tightly fitted structures such as riveting, pin connections, and tenon joints. These structures are highly susceptible to fretting fatigue failure under alternating loads, reducing component lifespan and severely impacting safe operation. Therefore, fretting fatigue damage is often referred to as "industrial cancer." Fretting fatigue involves multiple disciplines, including mechanics, materials science, heat transfer, and tribology. Its damage process is exceptionally complex, requiring high-precision testing equipment to accurately reveal the influence of various factors on the fretting fatigue of materials and structures.

[0003] In the field of fretting fatigue testing, most existing testing methods and devices are simple modifications of conventional uniaxial fatigue testing systems. They lack effective control and monitoring of fretting fatigue loads. Especially under high temperature conditions, the control accuracy of fretting fatigue loads is poor, and there is little data available during the test. It is difficult to accurately obtain the influence of relative slippage, tangential force, etc. on fretting fatigue damage during the fretting fatigue process.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this disclosure is to overcome the shortcomings of the prior art and to provide an induction heating type fretting fatigue testing device and method.

[0006] Other features and advantages of this disclosure will become apparent from the following detailed description, or may be learned in part from practice of this disclosure.

[0007] According to one aspect of this disclosure, an induction heating type fretting fatigue testing device is provided, comprising:

[0008] A clamping mechanism is used to clamp a fretting fatigue test piece and a pad, one end of which abuts against the surface of the fretting fatigue test piece and is used to transfer the normal load to the fretting fatigue test piece.

[0009] A loading mechanism is connected to the clamping mechanism and is used to apply a load to the fretting fatigue test piece.

[0010] The heating mechanism includes multiple sets of inductor coils and a heating element. The heating mechanism heats the heating element through the inductor coils, and the heating element provides a high-temperature environment for the fretting fatigue test piece through thermal radiation.

[0011] In some embodiments of this disclosure, based on the foregoing scheme, the pad has a wedge-shaped fixed end and a contact end, the fixed end is connected to the clamping mechanism through the wedge-shaped structure, and the contact end abuts against the surface of the fretting fatigue test piece.

[0012] In some embodiments of this disclosure, based on the foregoing scheme, the loading mechanism includes a normal loading component, which includes a pad holder, a slide plate, a push rod, and a servo actuator. The pad holder is provided with a wedge-shaped through hole, and the fixed end of the wedge-shaped structure of the pad is connected to the wedge-shaped through hole. The pad holder is connected to the first surface of the slide plate, and the push rod is connected to the second surface of the slide plate. The servo actuator applies a normal load to the fretting fatigue test piece by pushing the push rod.

[0013] In some embodiments of this disclosure, based on the foregoing scheme, the normal loading component further includes a fixed back plate and slide rails. The fixed back plate is provided with a through hole, and the push rod passes through the through hole into the fixed back plate. Multiple slide rails are fixed on the fixed back plate, and the slide plate slides through the multiple slide rails.

[0014] In some embodiments of this disclosure, based on the foregoing scheme, the loading mechanism includes an axial loading component, which includes an axial loading fixture, a hydraulic chuck, and an axial load control system. The fretting fatigue test piece is connected to the axial load control system through the axial loading fixture, and the axial load control system applies an axial load to the fretting fatigue test piece through the axial fixture.

[0015] In some embodiments of this disclosure, based on the foregoing scheme, the pad holder is provided with a cooling structure, which cools the pad holder through a cooling medium.

[0016] In some embodiments of this disclosure, based on the foregoing scheme, the multiple sets of inductor coils and the heating element are disposed at the circumferential position of the fretting fatigue test piece.

[0017] In some embodiments of this disclosure, based on the foregoing scheme, the fretting fatigue testing device further includes a fixing component, which includes a crossbeam, multiple columns, and a horizontal base plate.

[0018] The crossbeam, the horizontal base plate, and the axial load control system are connected in sequence through the plurality of columns. The horizontal base plate is provided with through holes, and the clamping mechanism passes through the through holes into the horizontal base plate. The normal loading component is disposed on the horizontal base plate.

[0019] According to another aspect of this disclosure, a fretting fatigue testing method is provided, the method being applied to the aforementioned fretting fatigue testing apparatus, the method comprising:

[0020] The heating element is heated by an inductor coil, and the heating element heats the fretting fatigue test piece by thermal radiation. When the heating temperature reaches the preset temperature value, the heating temperature of the fretting fatigue test piece is maintained at the preset temperature value for a certain period of time.

[0021] A normal load is applied to the fretting fatigue test piece and the pad block. The normal load of the fretting fatigue test piece and the normal displacement of the pad block are recorded. The normal load is controlled according to the ratio of the normal load to the displacement and the deviation of the normal load from the preset load value, so that the normal load has good symmetry and stability.

[0022] When the normal load reaches the preset load value, the normal load of the fretting fatigue test piece is kept at the preset load value, and axial fatigue load is cyclically applied to the fretting fatigue test piece;

[0023] When the fretting fatigue test piece fails due to fracture, the number of cycles of the axial fatigue load at the time of fracture is determined to obtain the fretting fatigue life of the fretting fatigue test piece.

[0024] In some embodiments of this disclosure, based on the foregoing scheme, before applying a normal load to the fretting fatigue test specimen and the pad, the method further includes:

[0025] An axial preload is applied to the fretting fatigue test specimen to determine its initial position;

[0026] The normal contact state between the fretting fatigue test piece and the pad is initialized based on the initial position and the initial contact load between the fretting fatigue test piece and the pad.

[0027] This disclosure provides an induction heating type fretting fatigue testing device. The device uses an inductor coil to heat the heating element, which can heat the fretting fatigue test piece in a small space. While ensuring that the fretting fatigue test piece is in the high temperature environment required for the test, it can also ensure the test accuracy of the fretting fatigue test.

[0028] Secondly, this disclosure provides a loading mechanism that, through the cooperation of the wedge-shaped pad and the wedge-shaped through hole of the pad holder, ensures that the pad is rigidly connected to the pad holder under the action of normal load, preventing the fretting fatigue pad from moving with the fretting fatigue test piece during the load loading process, thereby improving the accuracy of the fretting fatigue test.

[0029] Another aspect of this disclosure provides an induction heating fretting fatigue test method. On the one hand, this method ensures that the fretting fatigue test piece is within the range of the allowable displacement and allowable load during the loading process, and that the fretting fatigue test piece will not exhibit eccentric loading during the test.

[0030] On the other hand, this method improves the load loading accuracy and displacement measurement accuracy of fretting fatigue tests by applying normal symmetrical loads and axial alternating loads to the fretting fatigue test specimens. This ensures that the fretting fatigue tests are conducted under high-precision test conditions, thereby improving the accuracy of the test results.

[0031] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0033] Figure 1 This is a partial assembly schematic diagram of an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure.

[0034] Figure 2 This is a partial cross-sectional view of an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure.

[0035] Figure 3 This is an overall schematic diagram of an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure.

[0036] Figure 4 This is a schematic diagram of the clamping mechanism of an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure.

[0037] Figure 5 This is a schematic diagram of the load loading of a test piece in an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure.

[0038] Figure 6This is a schematic diagram of the pad holder structure of an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure.

[0039] Figure 7 This is a cross-sectional view of the connection structure between the pad holder and the pad in an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure.

[0040] Figure 8 This is a schematic diagram of the heating mechanism of an induction heating type fretting fatigue testing device according to an exemplary embodiment of the present disclosure.

[0041] Figure 9 This is a flowchart of a fretting fatigue test method according to an exemplary embodiment of the present disclosure.

[0042] The reference numerals in the attached figures are explained as follows:

[0043] 1: Clamping mechanism;

[0044] 11: First clamp; 111: First slot;

[0045] 112: First clamping end; 113: First cooling ring;

[0046] 12: Second clamp; 121: Second slot;

[0047] 122: Second clamping end; 123: Second cooling ring;

[0048] 211: Inductor coil; 212: Heating element;

[0049] 2: Spacer blocks;

[0050] 2211: First spacer block; 2212: Second spacer block;

[0051] 22111: First pad block body; 22112: First pad block head;

[0052] 2221: First block holder; 2222: Second block holder;

[0053] 2231: First skateboard; 2232: Second skateboard;

[0054] 2241: First fixed backplate; 2242: Second fixed backplate;

[0055] 2251: First putter; 2252: Second putter;

[0056] 2261: First servo actuator; 2262: Second servo actuator;

[0057] 227: Slide rail;

[0058] 231: Horizontal beam; 232: Vertical column; 233: Horizontal base plate;

[0059] 4: Fretting fatigue test specimens;

[0060] 5: Axial load control system;

[0061] 6: Hydraulic chuck;

[0062] 61: First hydraulic chuck; 62: Second hydraulic chuck;

[0063] 7: Axial load displacement sensor;

[0064] 8: Cooling holes. Detailed Implementation

[0065] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.

[0066] Although relative terms such as "above" and "below" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used here for convenience only. The terms "a," "an," "the," "the," and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to those listed; the terms "first," "second," and "third," etc., are used only as markings and are not a limitation on the number of objects.

[0067] This disclosure provides an induction heating type fretting fatigue testing device. Figure 1 This is a partial assembly schematic diagram of an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure, as shown below. Figure 1 As shown, the fretting fatigue testing device includes: a clamping mechanism, a loading mechanism, and a heating mechanism.

[0068] In some embodiments, the inventors provide a high-temperature fretting fatigue test clamping and loading device. In the device, a high-temperature furnace is used to provide a high-temperature environment for the test. However, during the load loading process, a cantilever beam structure needs to be extended into the high-temperature furnace to apply load to the test piece. Under the action of fatigue load, the cantilever beam will move with the test piece, which cannot guarantee the test accuracy of the fretting fatigue test.

[0069] In some embodiments, the inventors have provided a fretting fatigue loading device. This device also uses a high-temperature furnace to heat the test piece at high temperatures, and a loading ring to apply a load to the test piece. Although this device can apply a normal load to the test piece, its load control capability is poor, and it cannot be controlled during the test. Therefore, this disclosure provides an induction heating fretting fatigue testing device, which can ensure the stability of the loaded load and improve the accuracy of the fretting fatigue test.

[0070] The clamping mechanism is used to clamp the fretting fatigue test piece 4.

[0071] like Figure 4 As shown, Figure 4 This is a schematic diagram of the clamping mechanism of an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure. In this embodiment, the clamping mechanism includes a first clamp 11 and a second clamp 12, which are disposed opposite to each other. The first clamp 11 includes a first slot 111, a first clamping end 112, and a first cooling ring 113. The first slot 111 is used to clamp the fretting fatigue test piece. The second clamp 12 has the same structure as the first clamp 11, and will not be described again here.

[0072] The first cooling ring 113 and the second cooling ring 123 are hollow structures, and circulating cooling medium can be injected into the first cooling ring 113 and the second cooling ring 123 to circulate cooling of the axial loading mechanism during the test, which can ensure the normal operation of the axial loading mechanism.

[0073] Furthermore, the first clamping end 112 and the second clamping end 122 can be rectangular plate structures, and the corresponding first cooling ring 113 and the second cooling ring 123 can be adapted to be annular to adapt to the rectangular plate structure; the first clamping end 112 and the second clamping end 122 can be cylindrical structures, and the corresponding first cooling ring 113 and the second cooling ring 123 can be adapted to be annular to adapt to the cylindrical structure. This disclosure does not specifically limit the shape of the first clamping end 112 and the second clamping end 122, but needs to meet the strength and assembly requirements of the fretting fatigue test.

[0074] It should be noted that the axial clamp slot in this embodiment is suitable for test pieces of various sizes. In this embodiment, the axial clamp slot is suitable for flat pieces. If the test piece is cylindrical or other shapes, the axial clamp slot can be replaced with a slot suitable for the shape of the test piece. The clamping mechanism provided in this disclosure is suitable for various test piece shapes and sizes, and this disclosure does not make any specific limitations.

[0075] The clamping mechanism disclosed herein can clamp and fix test pieces of various sizes, providing stable clamping conditions for fretting fatigue testing.

[0076] The test piece includes a fretting fatigue test piece 4 and two pads. The fretting fatigue test piece 4 is located between two pads. The surface of the fretting fatigue test piece 4 is in contact with and abuts against the surfaces of the heads of the two pads, so that the pads can transfer the normal load to the fretting fatigue test piece.

[0077] The fretting fatigue testing device includes a heating mechanism, a loading mechanism, and a clamping mechanism. The loading mechanism is connected to the clamping mechanism, and the heating mechanism is disposed around the fretting fatigue test piece 4.

[0078] In some embodiments, such as Figure 8 As shown, the heating mechanism includes multiple sets of inductor coils 211, which are arranged in the circumferential position of the fretting fatigue test piece 4. The multiple sets of inductor coils 211 can heat the heating element 212, thereby providing a stable high-temperature test environment for the fretting fatigue test piece 4.

[0079] Inductor coil 211 is used in combination with heating element 212. There can be two inductors, symmetrically arranged front and rear in the contact area between the fretting fatigue test piece 4 and the fretting fatigue pad. The two inductors provide the required temperature environment for the fretting fatigue test piece 4. Furthermore, the number of inductors 211 can also be four or six, etc. The number of inductors needs to meet the heating conditions of the test piece in the fretting fatigue test, ensuring uniform heating of the test piece. This disclosure does not specify a particular number of inductors.

[0080] The inductor coil 211 and the heating element 212 can be fixed on the horizontal base plate 233, and the installation position can be adjusted according to the position of the test piece.

[0081] The heating element 212 is fitted inside the induction coil 211. The heating element 211 needs to be adapted to the size of the induction coil 211. The induction coil 211 forms a strong magnetic field through high-frequency induced current, thereby forming a current in the heating element 212, which in turn allows the heating element 212 to generate a large amount of heat. After the heating element 212 is heated, it transfers the heat to the test piece through thermal radiation, thereby providing a high-temperature environment for the test piece.

[0082] The heating element 211 can be a metallic material, such as an iron rod, copper rod, or tungsten rod, but it can also be other materials that can be adapted to the induction coil and can generate heat. The selection can be made according to the specific requirements of the experiment, and this disclosure does not make any specific limitations.

[0083] The inductor coil provided in this disclosure heats a heating element, which provides a high-temperature environment for the test piece through thermal radiation. This effectively ensures the heating conditions for the test while greatly saving the space required for the test.

[0084] In some embodiments, the loading mechanism includes a normal loading component.

[0085] like Figure 1 As shown, the normal loading mechanism includes a pad holder, a slide plate, a slide rail, a fixed back plate, a push rod, and a servo actuator.

[0086] The pad is held on the pad holder of the normal loading mechanism. Specifically, the pad includes a first pad 2211 and a second pad 2212. The pad holder includes a first pad holder 2221 and a second pad holder 2222. The slide includes a first slide 2231 and a second slide 2232. The fixed back plate includes a first fixed back plate 2241 and a second fixed back plate 2242. The push rod includes a first push rod 2251 and a second push rod 2252. The servo actuator includes a first servo actuator 2261 and a second servo actuator 2262. The number of slide rails 227 is multiple.

[0087] The first pad 2211 and the second pad 2212 are respectively arranged opposite to each other on both sides of the test part of the fretting fatigue test piece 4. The first pad 2211 is located in the wedge-shaped hole of the first pad holder 2221, and the second pad 2212 is located in the wedge-shaped hole of the second pad holder 2222. The first pad holder 2221 is connected to the first slide plate 2231, and the second pad holder 2222 is connected to the second slide plate 2232. The first slide plate 2231 and the second slide plate 2232 are respectively provided with through holes equal in number to the slide rail 227. The first end of the slide rail 227 passes through the first slide plate 2231, and the second end of the slide rail 227 passes through the second slide plate 2232. The first slide plate 2231 and the second slide plate 2232 are assembled with the slide rail 227 through sliding bearings, so that the first slide plate 2231 and the second slide plate 2232 can slide along the normal direction on the slide rail 227.

[0088] It should be noted that the first pad holder 2221 is connected to the first slide plate 2231, and the second pad holder 2222 is connected to the second slide plate 2232. The connection method can be threaded connection, welding or riveting. The connection method needs to meet the connection requirements of the test device of this disclosure. This disclosure does not make specific limitations.

[0089] The first fixed back plate 2241 and the second fixed back plate 2242 can adopt an L-shape, a T-shape, or other structural forms, the purpose of which is to constrain the fixed back plate 2241 and the fixed back plate 2242 on the horizontal base plate, and no limitation is made here. This structure is provided with the same number of positioning holes as the slide rails 227. The first end of the slide rail 227 passes through the positioning hole of the first fixed back plate 2241 and is fixed thereafter, and the second end of the slide rail 227 passes through the positioning hole of the second fixed back plate 2242 and is fixed thereafter. In addition, the first fixed back plate 2241 and the second fixed back plate 2242 are each provided with a center hole. The first push rod 2251 is connected to the first fixed back plate 2241 through the center hole, and the second push rod 2252 is connected to the second fixed back plate 2242 through the center hole. The push rods and the fixed back plates are assembled using sliding bearings, and the push rods can move within the through holes of the fixed back plates.

[0090] The first end of the first push rod 2251 is connected to the center of the first slide plate 2231, and the second end of the first push rod 2251 is connected to the first servo actuator 2261. The first end of the second push rod 2252 is connected to the center of the second slide plate 2232, and the second end of the second push rod 2252 is connected to the second servo actuator 2262. The above connection method can be a threaded connection or other connection methods, but the selection of the connection method must meet the strength and accuracy requirements of the fretting fatigue test. This disclosure does not make specific limitations.

[0091] Figure 2 This is a partial cross-sectional view of an induction heating fretting fatigue testing device according to an exemplary embodiment of this disclosure, such as... Figure 2 As shown, combined with Figure 1 When the fretting fatigue test piece 4 needs to be loaded with a normal load, the first servo actuator 2261 and the second servo actuator 2262 provide a normal load at the same time. The two normal loads are equal in magnitude and opposite in direction, and both act on the push rod. The load loaded by the first servo actuator 2261 pushes the first slide plate 2231 to slide on the slide rail 227 through the first push rod 2251. At the same time, the first slide plate 2231 drives the first pad holder 2221 and the first pad 2211 to move normally, applying a normal load on one side to the test piece 4. Similarly, the application of the normal load on the other side is the same as described above, and will not be repeated here.

[0092] It should be noted that the load applied to the test piece by the normal loading component is a symmetrical and equal rated load. This rated value can be set according to the actual test requirements, and the magnitude of the normal load can also be adjusted. This disclosure does not make any specific limitations.

[0093] The normal loading assembly provided in this disclosure can apply a symmetrical rated load to the test specimen. During the normal load loading process, there will be no eccentric loading, which improves the loading accuracy of the test.

[0094] In some embodiments, the loading mechanism includes an axial loading component.

[0095] Figure 3 This is a schematic diagram of an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure, as shown below. Figure 3 As shown, the axial loading assembly includes an axial load control system 5, a hydraulic chuck 6, and an axial loading fixture, wherein the hydraulic chuck includes a first hydraulic chuck 61 and a second hydraulic chuck 62.

[0096] The axial load control system 5 is fixed on a horizontal ground or a horizontal device. The axial load control system 5 is connected to the first end of the second hydraulic chuck 26. The second end of the second hydraulic chuck 62 is connected to the clamping mechanism 1. Specifically, the second end of the second hydraulic chuck 62 is connected to the second clamping end 122 of the second clamp 12 in the clamping mechanism 1. The first end of the first hydraulic chuck 61 is connected to the first clamping end 112 of the first clamp 11 in the clamping mechanism 1. The second end of the first hydraulic chuck 61 is connected to the fixing component 23.

[0097] When the test piece needs to be loaded with an axial load, the axial load control system 5 first applies a pre-load to the fretting fatigue test piece 4 through a hydraulic clamp, so that the fretting fatigue test piece 4 is pre-fixed in a stable position during the test to prevent the fretting fatigue test piece 4 from moving during the loading process. After the normal load on the fretting fatigue test piece 4 is completed, an alternating axial load is applied to the test piece 4 body through the axial load control system 5.

[0098] The axial loading fixture is provided with a cooling structure, which can be a cooling hole. The cooling medium cools the axial loading fixture through the cooling hole. However, the cooling structure on the axial loading fixture of this disclosure is not limited to the form of a cooling hole, and can also be other forms of cooling structure, as long as it meets the cooling function of the axial loading fixture of this disclosure.

[0099] It should be noted that the number of hydraulic chucks in this disclosure can be two or more, and the structure of the hydraulic chucks can be planar, wedge-shaped or other forms. The specific number and structure of the hydraulic chucks are set according to the structure of the fretting fatigue test piece or the actual use requirements, and this disclosure does not make specific limitations.

[0100] The axial loading assembly provided in this disclosure, through the setting of an axial load control system and a hydraulic clamp, can apply alternating axial loads to the test piece, ensuring the accuracy requirements of the test.

[0101] In some embodiments, the induction heating fretting fatigue testing device further includes a fixing component, which includes a crossbeam 231, a plurality of columns 232 and a horizontal base plate 233.

[0102] The crossbeam 231 and the horizontal base plate 233 are provided with an equal number of corresponding through holes. Multiple columns 232 connect the crossbeam 231, the horizontal base plate 233, and the axial load control system 5 from top to bottom. The crossbeam 231, the horizontal base plate 233, and the axial load control system 5 are arranged parallel to each other, but not limited to parallel arrangement. The relative positions can be adjusted according to the test requirements. In addition, the first fixed back plate and the side of the second fixed back plate of the normal loading assembly that is perpendicular to the fretting fatigue test piece are fixed on the horizontal base plate 233, realizing the fixed installation of the normal loading assembly on the fixed assembly.

[0103] A through hole is provided at the center of the horizontal substrate 233 to allow the clamping mechanism to pass through. The position of the horizontal substrate 233 can be adjusted to ensure that the test part of the fretting fatigue test piece matches the pad.

[0104] Meanwhile, the second end of the first hydraulic clamp 61 in the axial loading assembly is connected to the crossbeam 231. The hydraulic clamp 61 and the hydraulic clamp 62 are collinear, thereby ensuring that the axial load direction is consistent with the axis direction of the fretting fatigue test piece.

[0105] It should be noted that the crossbeam 231 in this disclosure is a movable crossbeam, and its specific position can be determined according to the actual test requirements; the horizontal base plate 233 in this disclosure can be adjusted up and down according to the test requirements. This disclosure does not impose fixed requirements on the positions of the crossbeam and the horizontal base plate, and their positions can be adjusted according to the actual test requirements.

[0106] The fixing components provided in this disclosure can fix the axial loading component and the normal loading component, and are easy to install and position adjust.

[0107] The induction heating fretting fatigue testing device provided in this disclosure also includes a load control system, which includes an axial load displacement sensor 7 and a servo actuator, wherein the servo actuator includes a first servo actuator 2261 and a second servo actuator 2262.

[0108] The axial load displacement sensor 7 is mounted on the clamping mechanism 1. The axial load displacement sensor 7 can be used to monitor and record the magnitude of the axial load applied to the fretting fatigue test piece, and at the same time, it can monitor and record the displacement of the fretting fatigue test piece in the axial direction.

[0109] The normal servo actuator is fixed on the horizontal base plate in the fixed assembly. While applying the normal load to the fretting fatigue test piece, the servo actuator can record the magnitude of the normal load on the test piece and the displacement of the test piece in the normal direction.

[0110] The load measurement and control system provided in this disclosure can accurately detect and record the magnitude of the normal and axial loads on the test specimen, as well as the displacement of the test specimen in the normal and axial positions, and can accurately control the fretting fatigue load.

[0111] Figure 6 This is a schematic diagram of the pad holder structure of an induction heating fretting fatigue testing device according to an exemplary embodiment of the present disclosure. Figure 7 This is a cross-sectional view of the pad holder and pad connecting device of an induction heating fretting fatigue testing device according to an exemplary embodiment of this disclosure, combined with... Figure 6 and Figure 7 As shown,

[0112] The pads include a first pad 2211 and a second pad 2212. Taking the first pad 2211 as an example, the first pad 2211 includes a first wedge-shaped fixing end 22112 and a first contact end 22111. The first wedge-shaped fixing end 22112 has a wedge-shaped structure. A wedge-shaped through hole is provided in the first pad holder 2221. The wedge-shaped structure of the first wedge-shaped fixing end 22112 and the wedge-shaped hole of the first pad holder 2221 are fixed inside the wedge-shaped hole by an interference fit. The first contact end 22111 acts on the surface of the fretting fatigue test piece, thereby applying a normal load to the test piece. The second pad 2212 has the same structure, connection relationship and working principle as the first pad 2211, and will not be described again here.

[0113] During the test, the wedge-shaped structure of the pad is interference-fitted with the wedge-shaped hole of the clamp. After the test or when the pad needs to be replaced, the pad can be pushed out of the wedge hole of the pad clamp and replaced.

[0114] It should be noted that the dimensions of the pad block and the dimensions and structure of the contact surface with the fretting fatigue test specimen can be designed and modified according to the actual needs of the test. In some embodiments, the pad block holder is provided with cooling holes 8, through which the cooling medium can cool the normal loading component.

[0115] It should be noted that the number of cooling holes 8 can be multiple, and the specific number and their arrangement on the pad holder are determined according to the actual test requirements. This disclosure does not make any specific limitations.

[0116] The present disclosure provides a pad block and a pad block holder and their matching structure, which can achieve loading stability of normal load on fretting fatigue test specimens, and use this structure to load normal load on the test specimens, and ensure that the pad block does not move during the test.

[0117] Figure 9 This is a flowchart of an induction heating fretting fatigue testing method according to an exemplary embodiment of the present disclosure. The present disclosure provides a fretting fatigue testing method, including:

[0118] S101: Apply axial preload to the fretting fatigue test specimen to determine the initial position of the fretting fatigue test specimen;

[0119] S102: Initialize the normal contact state between the fretting fatigue test piece and the pad block according to the initial position and the initial contact load between the fretting fatigue test piece and the pad block;

[0120] S103: The heating element is heated by an inductor coil, and the heating element heats the fretting fatigue test piece by thermal radiation. When the heating temperature reaches the preset temperature value, the heating temperature of the fretting fatigue test piece is maintained at the preset temperature value for a certain period of time.

[0121] S104: Apply a normal load to the fretting fatigue test piece and the pad, record the normal load of the fretting fatigue test piece and the displacement of the pad, and control the normal load according to the ratio of the normal load to the displacement and the deviation of the normal load from the preset value.

[0122] S105: When the normal load reaches the preset load value, maintain the normal load of the fretting fatigue test piece at the preset load value, and cyclically apply axial fatigue load to the fretting fatigue test piece;

[0123] S106: When the fretting fatigue test piece fails due to fracture, determine the number of cycles of the axial fatigue load on the fretting fatigue test piece to obtain the fretting fatigue life of the fretting fatigue test piece.

[0124] In some embodiments, combined with Figure 5 One axial end of the fretting fatigue test specimen is fixed, and both sides of the specimen are in contact with the pad. Normal loads P1 and P2 are applied to the specimen through the pad, causing compression between the pad and the fretting fatigue test specimen. At the same time, the pad undergoes small displacements U1 and U2. Then, an axial alternating load F1 is applied to the other axial end of the specimen. Under the action of F1, the fretting fatigue test specimen and the pad will move slightly, thereby simulating the fretting fatigue damage state of the fretting fatigue test specimen.

[0125] In some specific embodiments, first, an axial loading component is used to preload an axial load on the fretting fatigue test piece to ensure that the test piece is initially axially loaded. At the same time, an inductor coil is used to heat the heating element, thereby providing a high-temperature condition for the test piece.

[0126] Secondly, the normal loading component pushes the cushion block against the fretting fatigue test piece. When the normal load is about to change, after initializing the current normal load and displacement to 0, continue to load the normal load on the fretting fatigue test piece, and record the normal load values on both sides of the fretting fatigue test piece as P1 and P2. At the same time, record the displacements on both sides of the fretting fatigue test piece during the normal loading process as U1 and U2. At the same time, define the normal load symmetry indication factor as ε1, and define the normal load error stability indication factor as ε2. ε2 includes ε21 and ε22, where:

[0127]

[0128] ε21 = |P1 - P0|

[0129] ε22 = |P2 - P0|

[0130] Where, P0 is the rated value of the normal load.

[0131] When ε1 < k1, the symmetry of the normal load during the normal load loading process is good, where k1 is the allowable value of the normal load symmetry indication factor. When (ε21, ε22) < k2, it can ensure the symmetry of the normal load during the loading process, where k2 is the allowable value of the normal load stability indication factor.

[0132] Using k1 and k2 as feedback signals to control the loading of the normal load can ensure the symmetry of the normal load during the loading process, where the specific values of k1 and k2 are determined according to the mechanical properties of the test piece material.

[0133] According to the above values, the allowable value of the normal symmetry indication factor and the allowable value of the normal load error stability indication factor can be determined.

[0134] Thirdly, after the normal load determines the normal symmetric allowable load value, an axial load is applied to the fretting fatigue test piece. The axial load is an alternating load, and the axial load can be designed with a load spectrum according to the test requirements. The load spectrum waveform of the alternating load can be a triangular waveform, a rectangular waveform, a sine waveform, or other waveforms, etc. The present disclosure does not specifically limit the type of the axial alternating load.

[0135] When applying the axial alternating load to the test piece, the normal load can be maintained at the normal symmetric allowable load value, or the normal load can be changed. The loading of the normal load can be controlled by controlling the value of ε2, or the change of the normal load can be determined according to the actual test requirements.

[0136] Based on the above steps, the fretting fatigue life of the fretting fatigue test piece is determined by recording the number of fatigue load cycles when the fretting fatigue test piece fails structurally.

[0137] The induction heating fretting fatigue testing method disclosed herein improves the load loading accuracy and displacement measurement accuracy of the fretting fatigue test by applying normal symmetrical load and axial alternating load to the fretting fatigue test specimen, and can ensure the load control accuracy of the fretting fatigue test.

[0138] It should be noted that although the steps of the induction heating fretting fatigue testing method of this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that these steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0139] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. An induction heating fretting fatigue testing method, used in an induction heating fretting fatigue testing device, characterized in that, The induction heating type fretting fatigue test device includes: A clamping mechanism for clamping a fretting fatigue test piece and a spacer block. One end of the spacer block abuts against the surface of the fretting fatigue test piece, and the spacer block is used to transfer a normal load to the fretting fatigue test piece; A loading mechanism including an axial loading component and a normal loading component. The loading mechanism is connected to the clamping mechanism and is used to apply a load to the fretting fatigue test piece; A heating mechanism. The heating mechanism includes multiple groups of inductance coils and a heating body. The heating mechanism heats the heating body through the inductance coils, and the heating body provides a high-temperature environment for the fretting fatigue test piece through thermal radiation; The induction heating type fretting fatigue test method includes: Heating the heating body through the inductance coils. The heating body heats the fretting fatigue test piece through thermal radiation. When the heating temperature reaches a preset temperature value, keep the heating temperature of the fretting fatigue test piece at the preset temperature value for a certain period of time; Apply a normal load to the fretting fatigue test piece and the spacer block, record the normal load of the fretting fatigue test piece and the normal displacement of the spacer block, and control the normal load according to the ratio of the normal load to the displacement and the deviation value of the normal load to a preset load value, so that the normal load has good symmetry and stability; The normal loading component pushes the spacer block to abut against the fretting fatigue test piece. When the normal load is about to change, initialize the current normal load and displacement to 0, and then continue to apply a normal load to the fretting fatigue test piece. Record the normal load values on both sides of the fretting fatigue test piece as P1 and P2, and record the displacements on both sides of the fretting fatigue test piece during the normal loading process as U1 and U2. At the same time, obtain the normal load symmetry indication factor as ε1 and the normal load error stability indication factor as ε2. ε2 includes ε21 and ε22, where: ε21 = |P1 - P0| ε22 = |P2 - P0| Where, P0 is the rated value of the normal load; When ε1 < k1, the symmetry of the normal load during the normal load loading process is good, where k1 is the allowable value of the normal load symmetry indication factor; When (ε21, ε22) < k2, the stability of the normal load during the loading process is ensured, where k2 is the allowable value of the normal load stability indication factor; When the normal load reaches the preset load value, keep the normal load of the fretting fatigue test piece at the preset load value, and cyclically apply an axial fatigue load to the fretting fatigue test piece; When the fretting fatigue test piece fractures and fails, determine the number of cycles of the axial fatigue load when the fretting fatigue test piece fractures, and obtain the fretting fatigue life of the fretting fatigue test piece.

2. The induction heating type fretting fatigue test method according to claim 1, wherein Before applying a normal load to the fretting fatigue test piece and the spacer block, the method further includes: Applying an axial preload to the fretting fatigue test piece to determine the initial position of the fretting fatigue test piece; The normal contact state between the fretting fatigue test piece and the pad is initialized based on the initial position and the initial contact load between the fretting fatigue test piece and the pad.

3. The induction heating fretting fatigue testing method according to claim 1, characterized in that, The pad has a wedge-shaped fixed end and a contact end. The fixed end is connected to the clamping mechanism through the wedge structure, and the contact end abuts against the surface of the fretting fatigue test piece.

4. The induction heating fretting fatigue testing method according to claim 3, characterized in that, The normal loading assembly includes a pad holder, a slide plate, a push rod, and a servo actuator. The pad holder has a wedge-shaped through hole, and the fixed end of the wedge-shaped structure of the pad is connected to the wedge-shaped through hole. The pad holder is connected to the first surface of the slide plate, and the push rod is connected to the second surface of the slide plate. The servo actuator applies a normal load to the fretting fatigue test piece by pushing the push rod.

5. The induction heating fretting fatigue testing method according to claim 4, characterized in that, The normal loading component also includes a fixed back plate and slide rails. The fixed back plate is provided with a through hole, through which the push rod passes. Multiple slide rails are fixed on the fixed back plate, and the slide plate slides through the multiple slide rails.

6. The induction heating fretting fatigue testing method according to claim 1, characterized in that, The axial loading assembly includes an axial loading fixture, a hydraulic chuck, and an axial load control system. The fretting fatigue test piece is connected to the axial load control system through the axial loading fixture, and the axial load control system applies an axial load to the fretting fatigue test piece through the axial loading fixture.

7. The induction heating fretting fatigue testing method according to claim 4, characterized in that, The pad holder is provided with a cooling structure, which cools the pad holder through a cooling medium.

8. The induction heating fretting fatigue testing method according to claim 1, characterized in that, The multiple sets of inductor coils and the heating element are positioned circumferentially on the fretting fatigue test specimen.

9. The induction heating fretting fatigue testing method according to claim 1, characterized in that, The fretting fatigue testing device also includes a fixing assembly, which comprises a crossbeam, multiple columns, and a horizontal base plate. The crossbeam, the horizontal base plate, and the axial load control system are connected in sequence through the plurality of columns. The horizontal base plate is provided with through holes, and the clamping mechanism passes through the through holes into the horizontal base plate. The normal loading component is disposed on the horizontal base plate.

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