A multifunctional fatigue test tool and test method

Abstract

The present application belongs to the technical field of test tooling, and particularly relates to a multifunctional fatigue test tooling and a test method. The multifunctional fatigue test tooling comprises a tension-compression fatigue test unit for tension-compression fatigue test of a to-be-tested rod; a bending-torsion fatigue test unit for bending-torsion fatigue test of the to-be-tested rod; a force applying unit for providing power for the tension-compression fatigue test unit and / or the bending-torsion fatigue test unit; a six-dimensional force sensor connected to the to-be-tested rod for detecting force or torque received by the to-be-tested rod; and a detection element arranged on the to-be-tested rod for detecting deformation of the to-be-tested rod. The force applying unit repeatedly applies a set force to the to-be-tested rod multiple times, and collects force measurement values of the six-dimensional force sensor and deformation measurement values of the detection element. When the force measurement values decrease to a set value and the deformation measurement values remain unchanged within a certain range or the to-be-tested rod is broken, a corresponding fatigue test critical point is reached under the same displacement of the force applying unit.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of test tooling, and particularly relates to a multifunctional fatigue test tooling and a test method. BACKGROUND

[0002] Fatigue refers to the phenomenon that the structural performance of a material is degraded or even damaged when the material is subjected to cyclic stress or strain. According to statistics, the proportion of fatigue failure parts in various machines is 60-70%. Fatigue fracture failure is a low-stress brittle fracture failure in principle, and obvious deformation is difficult to observe in fatigue. Fatigue is mainly based on local plastic deformation, and mainly occurs on the inherent defects of the structure. Although frequency has a certain influence on fatigue failure, in most cases, fatigue failure is mainly related to the number of cycles, so fatigue test of the material plays an important role.

[0003] Fatigue tests are generally divided into tension-compression fatigue, torsional fatigue and bending fatigue, etc. The current test tooling structure is relatively complex, and multiple fatigue tests cannot be performed on one platform, so a multifunctional fatigue test tooling needs to be designed. SUMMARY

[0004] In order to solve the problem of complex structure and single function of the fatigue test tooling in the background art, the purpose of the present application is to provide a multifunctional fatigue test tooling and a test method, which can solve the above problems.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0006] A multifunctional fatigue test tooling, comprising a tension-compression fatigue test unit, a bending-torsional fatigue test unit, a force applying unit, a six-dimensional force sensor, and a detection element, which are used to perform tension-compression fatigue test on a to-be-tested rod; the bending-torsional fatigue test unit is used to perform bending-torsional fatigue test on the to-be-tested rod; the force applying unit is used to provide power for the tension-compression fatigue test unit and / or the bending-torsional fatigue test unit; the six-dimensional force sensor can be connected to the to-be-tested rod, and is used to detect the force or torque received by the to-be-tested rod; and the detection element can be arranged on the to-be-tested rod and is used to detect the deformation amount of the to-be-tested rod.

[0007] In the fatigue test, the force applying unit applies force to the tested rod in each fatigue test unit, and in the tension-compression fatigue test, the force applying unit pulls or presses the tested rod, and then the tested rod generates corresponding force and deformation, and the six-dimensional force sensor and the detection element collect and analyze the force and deformation data of the tested rod. When the force measurement value decreases to the set value and the deformation measurement value remains unchanged within a certain range or the tested rod breaks under the same displacement of the force applying unit, the tension-compression test critical point is reached. The bending-torsion fatigue test and the tension-compression fatigue test method are the same as above, the force applying unit applies force to the end of the tested rod, and the six-dimensional force sensor and the detection element collect and analyze the force and deformation data of the tested rod. When the force measurement value decreases to the set value and the deformation measurement value remains unchanged within a certain range or the tested rod breaks under the same displacement of the force applying unit, the bending moment critical point is reached. The detection element can be selected but is not limited to a strain gauge; the six-dimensional force sensor and the strain gauge used in this scheme are measurement products existing in the prior art, and will not be described here. The tested rods in the two fatigue test units can be two brand new rods that have not been tested, and can be used in two fatigue test units respectively, or can be the same rod, which is tested in one fatigue test unit and then taken to another fatigue test unit for continuous testing.

[0008] Further, the six-dimensional force sensor is arranged at one end of the tested rod close to the force applying unit, which can collect the most direct force in each direction of the tested rod and analyze and feedback.

[0009] Further, in the tension-compression fatigue test, the power output direction of the force applying unit is the same as the axial direction of the tested rod; in the bending-torsion fatigue test, the power output direction of the force applying unit is variable to always keep perpendicular to the axial direction of the tested rod. In the tension-compression fatigue test, the tested rod needs to be pulled and pressed, and the power output direction of the force applying unit and the axial direction of the tested rod are guaranteed to be in the same direction, which can maximize the efficiency of the power output of the force applying unit and will not cause force loss; in the bending-torsion fatigue test, the power output direction of the force applying unit needs to always keep perpendicular to the axial direction of the tested rod to ensure the accuracy of the test results.

[0010] Further, the force applying unit is connected with a moving device, which can move the force applying unit to the tension-compression fatigue test unit or the bending-torsion fatigue test unit. Specifically, the moving device can be a pulley, a guide rail, or other moving devices. With the moving device, the force applying unit can be switched between the two fatigue test units, that is, one force applying unit can meet the requirements of the two fatigue test units, reducing the number of force applying units and the cost and complexity of the fatigue test tooling.

[0011] Further, the force applying unit comprises an intermediate connecting piece and a power lifting device, which applies force to the rod to be tested through the intermediate connecting piece; the intermediate connecting piece comprises a spherical pair, which comprises a ball head and a ball head sleeve, the ball head sleeve is connected with a first connecting rod, the axis of the first connecting rod passes through the ball center of the ball head sleeve; the ball head is connected with a second connecting rod, the axis of the second connecting rod passes through the ball center of the ball head, and the spherical surface area of the ball head matched with the ball head sleeve is greater than half the area of the ball head. In tension-compression fatigue testing, force needs to be applied along the axial direction of the rod to be tested, and in bending-torsion fatigue testing, force needs to be applied perpendicular to the axial direction of the rod to be tested. The spherical pair can meet the requirements of the above fatigue tests. At the same time, the ball head rotates inside the ball head sleeve, so that the ball head cannot escape from the constraint of the ball head sleeve during fatigue testing, and the spherical pair can meet the requirements of the intermediate connecting piece for force transmission during fatigue testing.

[0012] Further, the bending-torsion fatigue test unit further comprises a fixing block, which is fixed at the end of the rod to be tested, the fixing block is connected and fixed with the first connecting rod of the ball head sleeve, and the first connecting rod is perpendicular to the rod to be tested, the fixing block has at least two positions for connecting the first connecting rod, and when the first connecting rod is located at one of the positions, the axis of the first connecting rod intersects with the axis of the rod to be tested. Two connecting positions, one is used for connecting the first connecting rod in bending moment fatigue testing, and the other is used for connecting the first connecting rod in torsion fatigue testing. During bending moment fatigue testing, the first connecting rod only needs to be kept perpendicular to the rod to be tested; during torsion fatigue testing, since the rod to be tested will be twisted, the first connecting rod is fixed on the fixing block, the first connecting rod will also be deflected and keep its axis perpendicular to the axis of the rod to be tested, thereby ensuring that the force applied by the power lifting device is always perpendicular to the axial direction of the rod to be tested.

[0013] Further, the fatigue testing device further comprises a rotating device connected with the rod to be tested, and the rotating device drives the rod to be tested to rotate around its axis. In the bending moment fatigue test, bending moment fatigue tests in at least two directions can be realized. For example, bending moment fatigue tests in a first direction and a second direction are performed. After the bending moment fatigue test in the first direction of the rod to be tested is completed, the rotating device is started to rotate the rod to be tested by a certain angle, and then the bending moment fatigue test in the second direction of the rod to be tested can be continued, thereby increasing the multifunctional use of the fatigue testing device. Of course, the rotating angle can be selected according to actual conditions to realize bending moment fatigue tests in multiple directions.

[0014] Further, the fatigue testing device further comprises a flange connected with the rod to be tested and the six-dimensional force sensor. The flange has a fixed cylinder and a flange, and the end of the rod to be tested can be inserted into the fixed cylinder, and the flange is used for bolt fixation, which can well fix the rod to be tested and the six-dimensional force sensor. Without punching holes on the rod to be tested, the integrity and completeness of the rod to be tested are maintained, and the accuracy of the test results is ensured.

[0015] Further, the fatigue testing device further comprises a flange connected with the rod to be tested and the six-dimensional force sensor. The flange has a fixed cylinder and a flange, and the end of the rod to be tested can be inserted into the fixed cylinder, and the flange is used for bolt fixation, which can well fix the rod to be tested and the six-dimensional force sensor. Without punching holes on the rod to be tested, the integrity and completeness of the rod to be tested are maintained, and the accuracy of the test results is ensured.

[0016] The tension-compression fatigue test comprises the following steps:

[0017] S11: The rod to be tested is installed in the tension-compression fatigue test unit,

[0018] S12: The force applying unit moves to the tension-compression fatigue test unit, and the force applying unit repeatedly applies a set tension and compression to the rod to be tested multiple times, and collects the force measurement value of the six-dimensional force sensor and the deformation measurement value of the detection element;

[0019] S13: When the force measurement value decreases to a set value and the deformation measurement value remains unchanged within a certain range or the rod to be tested is broken, the tension-compression test critical point is reached under the same displacement of the force applying unit;

[0020] The bending moment fatigue test comprises the following steps:

[0021] S21: The rod to be tested is installed in the bending-torsion fatigue test unit;

[0022] S22: The force applying unit moves to the bending-torsion fatigue test unit, and the force applying unit repeatedly applies a bending moment to the rod to be tested multiple times, and collects the force measurement value of the six-dimensional force sensor and the deformation measurement value of the detection element;

[0023] S23: When the force measurement value of the force unit decreases to a set value and the deformation measurement value remains unchanged within a certain range or the test rod breaks, the bending moment critical point is reached.

[0024] Further, the fatigue test method further comprises a torque fatigue test,

[0025] The torque fatigue test comprises the following steps:

[0026] S31: The test rod is installed in the bending-torsion fatigue test unit.

[0027] S32: The force unit moves to the bending-torsion fatigue test unit, and the force unit repeatedly applies torque to the test rod multiple times, and collects the force measurement value of the six-dimensional force sensor and the deformation measurement value of the detection element.

[0028] S33: When the force measurement value of the force unit decreases to a set value and the deformation measurement value remains unchanged within a certain range or the test rod breaks, the torque fatigue critical point is reached.

[0029] Compared with the prior art, the advantages of the present application are:

[0030] (1) The fatigue test tool integrates the tension-compression fatigue test function and the bending-torsion fatigue test function, and uses a six-dimensional force sensor to detect the force of the test rod, realizing multifunctional use;

[0031] (2) The six-dimensional force sensor is fixed to the force end of the test rod and close to the force unit, which can directly and comprehensively detect the change of the acting force of the test rod;

[0032] (3) The moving device, such as guide rail or roller, can move the power lifting device to the tension-compression fatigue test unit or the bending-torsion fatigue test unit, so as to share one power lifting device, reduce cost and complexity of the tool;

[0033] (4) The spherical pair is used as an intermediate connecting piece, which can meet the requirements of the acting force always along the axial direction of the test rod in the tension-compression fatigue test, and can meet the requirements of the acting force always perpendicular to the axial direction of the test rod in the bending-torsion fatigue test, and has good adaptability;

[0034] (5) The flange is used as the fixing device of the six-dimensional force sensor and the test rod, which has good fixing effect, and does not need to drill holes on the rod, ensuring the integrity of the test rod and further ensuring the accuracy and effectiveness of the measurement results;

[0035] (6) The rotating device is added, which can accurately adjust the rotation angle of the test rod, so as to realize the bending moment fatigue test of the test rod in different directions. Attached Figure Description

[0036] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0037] Figure 1 This is a schematic diagram of the overall structure of the fatigue testing fixture in this invention;

[0038] Figure 2 This is a schematic diagram of the spherical pair structure in this invention;

[0039] Figure 3 This is a schematic diagram of the fixing block structure in this invention;

[0040] Figure 4 This is a schematic diagram of the fixing block from another angle in this invention;

[0041] Figure 5 This is a schematic diagram of the fixing frame structure in this invention;

[0042] Figure 6 This is a schematic diagram of the structure in this invention where the rod to be tested is mounted on the large gear;

[0043] Figure 7 This is a schematic diagram of the servo electric cylinder structure in this invention;

[0044] Figure 8 This is a schematic diagram of the flange structure in this invention.

[0045] Explanation of reference numerals in the attached drawings: 1. Fixed stand; 2. Rod to be measured; 3. Six-dimensional force sensor; 4. Fixing frame; 5. Fixing block; 6. Strain gauge; 9. Spherical pair; 10. Ball head; 11. Ball head sleeve; 12. First connecting rod; 13. Second connecting rod; 14. Fixing cylinder; 15. Flanged edge; 16. First bolt hole; 17. First flange; 18. Second flange; 19. Third flange; 20. First connecting hole; 21. First locking hole; 22. Second connecting hole; 23. Third connecting hole; 24. Second locking hole; 25. Threaded sleeve; 26. Output shaft; 27. Rotating device; 28. Large gear; 29. ​​Small gear; 30. Motor; 31. Mounting groove; 32. Fourth connecting hole; 33. Fifth connecting hole; 34. Rotating part; 36. Rotating shaft; 37. Base plate; 38. Fixing plate; 39. Guide rail; 40. Triangular connecting plate; 41. Servo electric cylinder. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present invention.

[0047] Example:

[0048] like Figure 1 As shown, this embodiment provides a multifunctional fatigue testing fixture, including a tensile / compressive fatigue testing unit, a bending / torsional fatigue testing unit, a force application unit, a six-dimensional force sensor 3, and a detection element. The tensile / compressive fatigue testing unit is used to perform tensile / compressive fatigue testing on the rod 2 under test; the bending / torsional fatigue testing unit is used to perform bending / torsional fatigue testing on the rod 2 under test; the force application unit is used to provide power to the tensile / compressive fatigue testing unit and / or the bending / torsional fatigue testing unit; the six-dimensional force sensor 3 can be connected to the rod 2 under test to detect the force or torque applied to it; and the detection element can be disposed on the rod 2 under test to detect its deformation. Preferably, the detection element is a strain gauge 6. The tensile-compressive fatigue testing unit includes a fixed stand 1, the test rod 2 is vertically fixed on the fixed stand 1, and the six-dimensional force sensor 3 is connected to the lower end of the test rod 2. The bending-torsional fatigue testing unit includes a fixed frame 4 and a fixed block 5. The test rod 2 is horizontally fixed on the fixed frame 4. The free end of the test rod 2 is sequentially connected to the six-dimensional force sensor 3 and the fixed block 5. One end of the fixed block 5 is fixed to the six-dimensional force sensor 3, and the strain gauge 6 is attached to the test rod 2. The force application unit includes a power lifting device, which can apply force to the test rod 2.

[0049] Preferably, the six-dimensional force sensor 3 is disposed at one end of the rod 2 under test, near the force application unit, and can collect the most direct force on the rod 2 under test in each direction and provide feedback.

[0050] Preferably, the force-applying unit is connected to a moving device, which can move the force-applying unit to the tensile / compressive fatigue testing unit or the bending / torsional fatigue testing unit. Specifically, the moving device can be a pulley, a guide rail 39, or other moving device. With the help of the moving device, the force-applying unit can be switched between the two fatigue testing units, that is, one force-applying unit can meet the needs of two fatigue testing units, saving the number of force-applying unit devices and reducing tooling costs and structural complexity.

[0051] like Figure 2As shown, the force applying unit further comprises an intermediate connecting member through which the power lifting device applies force to the rod 2 to be tested, the intermediate connecting member comprises a spherical pair 9, the spherical pair 9 comprises a spherical head 10 and a spherical head sleeve 11, the spherical head sleeve 11 is connected with a first connecting rod 12, an axis of the first connecting rod 12 passes through a spherical center of the spherical head sleeve 11; the spherical head 10 is connected with a second connecting rod 13, an axis of the second connecting rod 13 passes through a spherical center of the spherical head 10, a spherical surface area of the spherical head 10 matched with the spherical head sleeve 11 is greater than half of an area of the spherical head 10. In a tension-compression fatigue test, a force along an axial direction of the rod 2 to be tested needs to be applied, in a bending-torsion fatigue test, a force perpendicular to the axial direction of the rod 2 to be tested needs to be applied, and the spherical pair 9 can meet the requirements of the fatigue tests. Meanwhile, the spherical head 10 rotates inside the spherical head sleeve 11, so in the tension fatigue test, the spherical head 10 cannot be separated from the spherical head sleeve 11, and the spherical pair 9 can meet the requirement of tension force transmission as the intermediate connecting member in the tension fatigue test.

[0052] As Figure 1 and Figure 8As shown, the fatigue test tooling also includes a flange, which has a fixing cylinder 14 and a flange 15, and the fixing cylinder 14 and the flange 15 are provided with first bolt holes 16, and the flange is connected to the end of the rod 2 to be tested, and the end of the six-dimensional force sensor 3 is provided with the flange. When fixing the rod 2 to be tested, the best fixing method is not to damage the inherent structure of the rod 2 to be tested, such as providing bolt holes on the rod 2 to be tested for bolt fixing, which will affect the accuracy of the test structure, and the use of the flange fixing can effectively solve the above problems, and the rod 2 to be tested is locked and fixed in the fixing cylinder 14, and the flange 15 of the flange is also used to fix the six-dimensional force sensor 3. Preferably, the flange includes a first flange 17, a second flange 18 and a third flange 19, both ends of the rod 2 to be tested are connected to the first flange 17 and the second flange 18 respectively, and the ends of the rod 2 to be tested are fixed in the fixing cylinder 14 of the corresponding flange, and are fixed by the first bolt hole 16 on the fixing cylinder 14 of the corresponding flange and the first bolt, the first bolt is screwed in the first bolt hole 16 and the rod 2 to be tested is clamped and fixed; both ends of the six-dimensional force sensor 3 are connected to the second flange 18 and the third flange 19; in the tensile-compressive fatigue test, the first connecting rod 12 of the ball head sleeve 11 is fixed in the fixing cylinder 14 of the third flange 19; in the bending-torsional fatigue test, the fixing block 5 and the third flange 19 are connected and fixed. In the tensile-compressive fatigue test unit, the first flange 17 fixes one end of the rod 2 to be tested on the fixed stand 1, the second flange 18 fixes one end of the six-dimensional force sensor 3 on the other end of the rod 2 to be tested, and the third flange 19 is connected and fixed between the spherical pair 9 and the six-dimensional force sensor 3; in the bending-torsional fatigue test unit, the first flange 17 fixes one end of the rod 2 to be tested on the fixing frame 4, the second flange 18 fixes the six-dimensional force sensor 3 on the other end of the rod 2 to be tested, and the third flange 19 is connected and fixed between the fixing block 5 and the six-dimensional force sensor 3, and the power lifting device exerts force on the fixing block 5 to perform bending-torsional fatigue test.

[0053] As Figure 3 and Figure 4As shown, the fixing block 5 is provided with a first connecting hole 20, the fixing cylinder 14 of the third flange 19 passes through the first connecting hole 20, the sidewall of the first connecting hole 20 is provided with a first locking hole 21, the diameter of the first connecting hole 20 matches the inner diameter of the fixing cylinder 14 of the third flange 19, the fixing cylinder 14 is inserted into the first connecting hole 20, and the fixing cylinder 14 of the third flange 19 is limited and fixed in the first connecting hole 20 by being tightly screwed into the first locking hole 21 by the second bolt. The fixing block 5 is provided with a second connecting hole 22 perpendicular to the first connecting hole 20, the axis of the second connecting hole 22 intersects the axis of the first connecting hole 20, and is used to be connected and fixed with the first connecting rod 12 of the ball head sleeve 11. In the bending moment fatigue test, the fixing cylinder 14 of the third flange 19 is locked and tightly fixed in the first connecting hole 20 on the fixing block 5 by the cooperation of the second bolt and the first locking hole 21, and the first connecting rod 12 of the ball head sleeve 11 is fixed in the second connecting hole 22, the axis of the second connecting hole 22 intersects the axis of the first connecting hole 20, that is, the first connecting rod 12 is perpendicular to the axis of the to-be-tested rod member 2, so that the force of the power lifting device is always perpendicular to the axial direction of the to-be-tested rod member 2 during the bending moment fatigue test, meeting the force requirement during the bending moment fatigue test. The fixing block 5 is provided with a third connecting hole 23 parallel to the second connecting hole 22, the axes of the second connecting hole 22 and the third connecting hole 23 have a set distance, the third connecting hole 23 is used to be connected and fixed with the first connecting rod 12 of the ball head sleeve 11, the sidewall of the third connecting hole 23 is provided with a second locking hole 24, and the first connecting rod 12 of the ball head sleeve 11 is tightly locked and fixed in the third connecting hole 23 by being screwed into the second locking hole 24 by the third bolt. In the torque fatigue test, one end of the fixing block 5 is fixed on the six-dimensional force sensor 3 through the third flange 19, the other end of the fixing block 5 is provided with a third connecting hole 23 spaced apart from the second connecting hole 22 by a set distance and parallel to the second connecting hole 22, and is used to be connected and fixed with the first connecting rod 12 of the ball head sleeve 11, the power lifting device acts on one end of the fixing block 5 where the third connecting hole 23 is located, and drives the to-be-tested rod member 2 to be twisted, and the six-dimensional force sensor 3 and the strain gauge 6 collect measurement data.

[0054] As Figure 1 , Figure 5 and Figure 6As shown, the fatigue testing tool further comprises a rotating device 27 connected with the rod 2 to be tested, which drives the rod 2 to be tested to rotate around its axial direction. In the bending moment fatigue test, bending moment fatigue tests in at least two directions can be realized. In the embodiment, bending moment fatigue tests in a first direction and a second direction are performed, wherein the first direction and the second direction are perpendicular to each other and perpendicular to the axial direction of the rod 2 to be tested. After the bending moment fatigue test of the rod 2 to be tested in the first direction is completed, the rotating device 27 is started to rotate the rod 2 to be tested by 90° and adjust the installation of the fixed block 5, and then the bending moment fatigue test of the rod 2 to be tested in the second direction can be measured, thereby increasing the multifunctional use of the fatigue testing tool. Of course, the rotation angle can be selected according to the actual situation to realize bending moment fatigue tests in multiple directions. Preferably, the rotating device 27 comprises a large gear 28, a small gear 29 and a motor 30. The fixed frame 4 is provided with a mounting groove 31, and the two side walls of the mounting groove 31 are provided with a fourth connecting hole 32 and a fifth connecting hole 33. The large gear 28 and the small gear 29 are rotatably installed in the mounting groove 31. The large gear 28 has a rotating part 34 and a central hole. The rotating part 34 is rotatably arranged in the fifth connecting hole 33. The end of the rod 2 to be tested passes through the fourth connecting hole 32 and the central hole in sequence. The flange 15 of the first flange 17 is fixed on the large gear 28. The small gear 29 is engaged with the large gear 28. The rotating shaft 36 of the motor 30 is rotatably arranged on the two side walls of the mounting groove 31. The small gear 29 is fixed on the rotating shaft 36. When the rod 2 to be tested needs to be rotated, the motor 30 is started to drive the rotating shaft 36 to rotate, thereby driving the small gear 29, the large gear 28 engaged with the small gear 29, and the rod 2 to be tested fixed on the large gear 28 to rotate, so as to perform bending moment fatigue tests of the rod 2 to be tested in different directions.

[0055] As Figure 1 and Figure 7 shown, it further comprises a bottom plate 37, a fixed plate 38 and a guide rail 39. The fixed stand 1 and the fixed frame 4 are fixed on the bottom plate 37. The fixed plate 38 is fixed on the fixed stand 1. The fixed stand 1 is perpendicular to the bottom plate 37. A triangular connecting plate 40 is connected between the fixed stand 1 and the fixed plate 38. The right angle edges of the triangular connecting plate 40 are connected with the fixed stand 1 and the fixed plate 38 respectively. The rod 2 to be tested in the tension-compression fatigue test unit is fixed on the fixed plate 38. The power lifting device is a servo cylinder 41. The servo cylinder 41 is slidably arranged on the guide rail 39. One end of the guide rail extends below the fixed plate 38, and the other end extends to one side of the fixed frame 4.

[0056] Preferably, the force applying unit further comprises a threaded sleeve 25 with internal threads, the power lifting device has an output shaft 26, the second connecting rod 13 and the output shaft 26 are both provided with external threads corresponding to the internal threads of the threaded sleeve 25, and the second connecting rod 13 and the output shaft 26 are threadedly fixed at both ends of the threaded sleeve 25. The threaded sleeve 25 threadedly fixes the second connecting rod 13 and the output shaft 26, which is simple in structure and stable in structure, and facilitates power output of the force applying unit.

[0057] There is also a fatigue test method, including tensile-compressive fatigue test, bending-torsional fatigue test,

[0058] The tensile-compressive fatigue test comprises the following steps:

[0059] S11: The to-be-tested rod 2 is vertically fixed on the fixed stand 1,

[0060] S12: The power lifting device moves to the tensile-compressive fatigue test unit, and the force applying unit repeatedly applies a set tensile force and a set compressive force to the to-be-tested rod 2 multiple times, and the force measurement value of the six-dimensional force sensor 3 and the deformation measurement value of the strain gauge 6 are collected;

[0061] S13: When the force measurement value decreases to a set value and the deformation measurement value remains unchanged within a certain range or the to-be-tested rod 2 is broken, the tensile-compressive test critical point is reached under the same displacement of the force applying unit;

[0062] The bending-torsional fatigue test comprises the following steps:

[0063] S21: The to-be-tested rod 2 is horizontally fixed on the fixed frame 4;

[0064] S22: The power lifting device moves to the bending-torsional fatigue test unit, and the force applying unit repeatedly applies a bending moment to the to-be-tested rod 2 multiple times, and the force measurement value of the six-dimensional force sensor 3 and the deformation measurement value of the strain gauge 6 are collected;

[0065] S23: When the force measurement value decreases to a set value and the deformation measurement value remains unchanged within a certain range or the to-be-tested rod 2 is broken, the bending moment critical point is reached under the same displacement of the force applying unit.

[0066] Preferably, the fatigue test method further comprises a torque fatigue test, and the torque fatigue test comprises the following steps:

[0067] S31: The to-be-tested rod 2 is horizontally fixed on the fixed frame 4;

[0068] S32: the power lifting device moves to the bending and torsion fatigue test unit, the power lifting device pushes the fixed block 5, the test rod 2 is twisted, the position of the fixed strain gauge 6 is taken as a reference point, when the torque is applied for the first time, the test rod 2 is twisted, at this time, the torque value is captured by the six-dimensional force sensor 3, the angle of torsion or the deformation of torsion is captured by the strain gauge 6, the deformation captured for the first time is taken as a standard deformation, the torque captured for the first time is taken as a standard torque, the power lifting device repeatedly applies force to the standard torque, the force measurement value of the six-dimensional force sensor 3 and the deformation measurement value of the strain gauge 6 are collected;

[0069] S33: when the force measurement value decreases to a set value and the deformation measurement value remains unchanged within a certain range or the test rod 2 is broken under the same displacement of the power lifting device, the fatigue critical point of the torque is reached.

[0070] Working principle: when the tension and compression fatigue test is performed, the six-dimensional force sensor 3 and the power lifting device are sequentially arranged at the lower end of the test rod 2, the power lifting device repeatedly applies a set tension and compression force to the test rod multiple times, the force measurement value of the six-dimensional force sensor 3 and the deformation measurement value of the strain gauge 6 are collected, when the force measurement value decreases to a set value and the deformation measurement value remains unchanged within a certain range or the test rod 2 is broken under the same displacement of the power lifting device, the tension and compression test critical point is reached; when the bending moment fatigue test is performed, the test rod 2 is horizontally fixed on the fixed frame 4, the power lifting device vertically upward or downward repeatedly applies a bending moment multiple times, pushes the test rod 2 to bend, the force measurement value of the six-dimensional force sensor 3 and the deformation measurement value of the strain gauge are collected; when the force measurement value decreases to a set value and the deformation measurement value remains unchanged within a certain range or the test rod 2 is broken under the same displacement of the power lifting device, the bending moment fatigue test critical point is reached; when the torque fatigue test is performed, the power lifting device pushes the free end of the fixed block 5 away from the six-dimensional force sensor 3 to rotate, the test rod 2 is twisted, the position of the fixed strain gauge 6 is taken as a reference point, the power lifting device repeatedly applies force to the standard torque, the standard torque can be realized by controlling the torque of the power lifting device. The force measurement value of the six-dimensional force sensor 3 and the deformation measurement value of the strain gauge 6 are collected; when the force measurement value decreases to a set value and the deformation measurement value remains unchanged within a certain range or the test rod 2 is broken under the same displacement of the power lifting device, the fatigue critical point of the torque is reached.

[0071] It will be obvious to a person skilled in the art that the application is not limited to the details of the above-described exemplary embodiments, but that the application can be implemented in other embodiments without departing from the spirit of the application or within the scope of the features. The embodiments are therefore to be seen as exemplary and non-limiting, the scope of the application being defined by the claims appended hereto and not by the above description, and all variations falling within the meaning and range of equivalency of the essential features of the claims are therefore intended to be embraced therein.

[0072] Furthermore, it should be understood that, although the present specification describes exemplary embodiments, not every embodiment contains only one independent technical solution, and the present specification is described in this way only for the sake of clarity, and a person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that a person skilled in the art can understand.

Claims

1. A multi-functional fatigue testing tool, characterized by, It comprises: a tension-compression fatigue test unit for testing the tension-compression fatigue of the test rod (2); a bending-torsion fatigue test unit for testing the bending-torsion fatigue of the test rod (2); a force application unit for providing power to the tension-compression fatigue test unit and / or the bending-torsion fatigue test unit; a six-dimensional force sensor (3) connected to the test rod (2) for detecting the force or torque received by the test rod (2); a detection element arranged on the test rod (2) for detecting the deformation of the test rod (2); The force application unit is connected to a moving device, which can move the force application unit to the tension-compression fatigue test unit or the bending-torsion fatigue test unit. In the tension-compression fatigue test, a force along the axial direction of the test rod (2) needs to be applied. In the bending-torsion fatigue test, a force perpendicular to the axial direction of the test rod (2) needs to be applied. The force application unit comprises an intermediate connecting piece and a power lifting device, which applies force to the test rod (2) through the intermediate connecting piece. The intermediate connecting piece comprises a spherical pair (9), which comprises a spherical head (10) and a spherical head sleeve (11). The spherical head sleeve (11) is connected to a first connecting rod (12), and the axis of the first connecting rod (12) passes through the center of the spherical head sleeve (11). The spherical head (10) is connected to a second connecting rod (13), and the axis of the second connecting rod (13) passes through the center of the spherical head (10). The spherical surface area of the spherical head (10) and the spherical head sleeve (11) is greater than half the area of the spherical head (10). The bending-torsion fatigue test unit further comprises a fixing block (5) fixed to the end of the test rod (2). The fixing block (5) is connected to the first connecting rod (12) of the spherical head sleeve (11) and is perpendicular to the test rod (2). The fixing block (5) has at least two positions for connecting the first connecting rod (12), and when the first connecting rod (12) is located at one of the positions, its axis intersects with the axis of the test rod (2).

2. The multi-functional fatigue testing tool of claim 1, wherein: The six-dimensional force sensor (3) is arranged at one end of the test rod (2) close to the force application unit.

3. The multi-functional fatigue testing fixture of claim 1, wherein: The fatigue test tool further comprises a rotating device (27) connected to the test rod (2), which drives the test rod (2) to rotate around its axial direction.

4. The multi-functional fatigue testing fixture of claim 1, wherein: The fatigue test tool further comprises a flange, and the ends of the test rod (2) and the six-dimensional force sensor (3) are connected to the flange.

5. A fatigue testing method based on the multifunctional fatigue testing tool of any one of claims 1-4, characterized in that, It comprises tension-compression fatigue test and bending-torsion fatigue test, The tension-compression fatigue test comprises the following steps: S11: installing the test rod (2) in the tension-compression fatigue test unit, S12: moving the force application unit to the tension-compression fatigue test unit, and repeatedly applying a set tension and compression force to the test rod (2) by the force application unit multiple times, and collecting the force measurement value of the six-dimensional force sensor (3) and the deformation measurement value of the detection element; S13: When the force measurement value drops to a set value and the deformation measurement value remains unchanged within a certain range or the rod (2) to be tested breaks under the same displacement of the force unit, the tension and compression test critical point is reached; The bending moment fatigue test comprises the following steps: S21: The rod (2) to be tested is installed in the bending and torsion fatigue test unit; S22: The force unit moves to the bending and torsion fatigue test unit, and the force unit repeatedly applies a bending moment to the rod (2) to be tested multiple times, and collects the force measurement value of the six-dimensional force sensor (3) and the deformation measurement value of the detection element; S23: When the force measurement value drops to a set value and the deformation measurement value remains unchanged within a certain range or the rod (2) to be tested breaks under the same displacement of the force unit, the bending moment critical point is reached.

6. A fatigue testing method according to claim 5, characterized in that: It also includes a torque fatigue test, The torque fatigue test comprises the following steps: S31: The rod (2) to be tested is installed in the bending and torsion fatigue test unit; S32: The force unit moves to the bending and torsion fatigue test unit, and the force unit repeatedly applies a torque to the rod (2) to be tested multiple times, and collects the force measurement value of the six-dimensional force sensor (3) and the deformation measurement value of the detection element; S33: When the force measurement value drops to a set value and the deformation measurement value remains unchanged within a certain range or the rod (2) to be tested breaks under the same displacement of the force unit, the torque fatigue critical point is reached.

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