Resonant connecting rod fatigue test device

Abstract

The invention discloses a resonant type connecting rod fatigue test device which comprises a main frame body, a bottom frame of a vibration exciter is fixed to the middle of the top face of a bottom plate of the main frame body, the two ends of a first vertical guide rod are installed on a top plate and the bottom plate of the main frame body, and the two ends of a second vertical limiting rod are installed on the top plate and the bottom plate of the main frame body. The counterweight connecting block is located in the middle of the main frame body. The first vertical guide rod and the second vertical limiting rod are inserted into a left through hole and a right through hole of the counterweight connecting block in a sleeved mode. The practical working condition is more accordant, the structure is simple, the size is small, and the cost is low.

Description

Technical Field:

[0001] The present invention relates to the technical field of fatigue test equipment, and more specifically to a resonant connecting rod fatigue test device. Background Art:

[0002] The engine connecting rod is used to connect the piston and the crankshaft and transmit the force received by the piston to the crankshaft. Therefore, the connecting rod is subjected to the action of non-uniform alternating loads of the in-cylinder pressure and the reciprocating inertia force, and fatigue fracture is its main failure form. Therefore, the fatigue test of the engine connecting rod has become an important link in the development of the connecting rod.

[0003] Currently, the fatigue test of the connecting rod generally uses hydraulic loading or mechanical loading for the fatigue test, but there are the following deficiencies:

[0004] The hydraulic cylinder of the hydraulic test bench can only apply a unidirectional load, which does not conform to the alternating load received by the connecting rod during actual operation. And the loading frequency of the cylinder is low, resulting in a long test cycle, high energy consumption, large floor space for auxiliary equipment such as oil tanks, pump stations, and pipelines, and large test vibration and noise.

[0005] The mechanical loading structure is complex, the amplitude of the test load is limited, and the energy consumption is large. Summary of the Invention:

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a resonant connecting rod fatigue test device, which is more in line with the actual working conditions, has a simple structure, a small volume, and a low cost.

[0007] The solution for the present invention to solve the above technical problems is:

[0008] A resonant connecting rod fatigue test device includes a main frame body. The bottom frame of the exciter is fixedly installed in the middle of the top surface of the bottom plate of the main frame body. Both ends of the first vertical guide rod are installed on the top plate and the bottom plate of the main frame body. Both ends of the second vertical limiting rod are installed on the top plate and the bottom plate of the main frame body. The counterweight connecting block is located in the middle of the main frame body. The first vertical guide rod and the second vertical limiting rod are inserted into the left through hole and the right through hole of the counterweight connecting block.

[0009] The top end of the transmission rod at the top of the vibrator presses against the middle of the bottom surface of the counterweight connection block. Two lower connection seats are fixed in the middle of the top surface of the counterweight connection block. Below the top plate of the main frame body, there is an upper horizontal fixing plate. Two upper connection seats are fixed in the middle of the bottom surface of the upper horizontal fixing plate. An upper vertical adjusting screw is fixed in the middle of the upper horizontal fixing plate. The top of the upper vertical adjusting screw extends out of the top surface of the upper horizontal fixing plate and passes through the middle through hole of the top plate of the main frame body. The top of the upper vertical adjusting screw is screwed with an upper limit nut. The bottom surface of the upper limit nut presses against the top surface of the top plate of the main frame body. Upper elastic sleeves are installed on the two upper connection seats, and lower elastic sleeves are installed on the two lower connection seats. The upper and lower installation through holes of the connecting rod to be tested are inserted into the corresponding upper and lower elastic sleeves;

[0010] The inner side walls at the left and right ends of the upper elastic sleeve and the lower elastic sleeve are conical wall surfaces. Two transverse adjusting screws are respectively inserted into the upper elastic sleeve and the lower elastic sleeve. An axial screw-through hole is formed in the middle of the end support block. The end support block is screwed into the end of the transverse adjusting screw. The outer side wall of the end support block is a conical wall surface, which presses against the inner side wall at the end of the upper elastic sleeve or the lower elastic sleeve. The outer side walls of the upper elastic sleeve and the lower elastic sleeve press against the inner side walls of the corresponding installation through holes of the upper connection seat and the lower connection seat. The middle outer side wall of the upper elastic sleeve or the lower elastic sleeve presses against the inner side wall of the corresponding installation through hole of the connecting rod.

[0011] A connecting rod bushing is clamped on the inner side wall of the corresponding installation through hole of the connecting rod. The middle outer side wall of the upper elastic sleeve or the lower elastic sleeve presses against the inner side wall of the corresponding connecting rod bushing.

[0012] The first vertical guide rod is a cylindrical rod body, and its outer side wall is close to or in close contact with the inner side wall of the left part through hole;

[0013] A vertical guide groove is formed at the inner side wall of the left part through hole. The top surface of the vertical guide groove extends out of the top surface of the counterweight connection block. A plurality of vertically arranged balls are inserted into the vertical guide groove. The top surface of the counterweight connection block at the left part through hole is fixedly connected with an upper annular plate by bolts. The first vertical guide rod is inserted into the middle through hole of the upper annular plate. The upper annular plate covers the vertical guide groove. All the balls are partially located at the left part through hole and are in close contact with the outer side wall of the first vertical guide rod.

[0014] A plurality of vertically extending inclined side walls are formed at the side wall of the second vertical limiting rod. A part of the outer side wall of the second vertical limiting rod is in close contact with the inner side wall of the right part through hole.

[0015] Connecting counterweight blocks are fixedly connected to the left and right parts of the top surface of the counterweight connection block by bolts.

[0016] The bottom end of the upper vertical adjusting screw is formed with a spherical part having an outer diameter larger than that of the upper vertical adjusting screw. The middle part of the upper horizontal fixing plate is formed with a vertical screw-through hole. The inner side wall of the bottom end of the vertical screw-through hole is a conical wall surface. The upper vertical adjusting screw is screwed in the vertical screw-through hole, and the outer side wall of the upper part of the spherical part is pressed against the conical wall surface at the bottom of the vertical screw-through hole.

[0017] Upper vertical guiding through holes are formed in both the left part and the right part of the upper horizontal fixing plate. The upper parts of the first vertical guiding rod and the second vertical limiting rod are inserted into the corresponding upper vertical guiding through holes.

[0018] The tops of the first vertical guiding rod and the second vertical limiting rod are inserted into the corresponding upper vertical through holes formed in the top plate of the main frame body. The bottoms of the first vertical guiding rod and the second vertical limiting rod are inserted into the corresponding concave holes on the top surface of the bottom plate of the main frame body. Two positioning connecting seats are fixed on the top surface of the bottom plate of the main frame body. The lower parts of the first vertical guiding rod and the second vertical limiting rod are inserted into the middle through holes of the corresponding positioning connecting seats. Annular grooves are formed on the outer side walls of the lower parts of the first vertical guiding rod and the second vertical limiting rod. Multiple radially extending screw-through holes are formed on the outer side walls of the side plates of the positioning connecting seats. The set screws are screwed in the corresponding screw-through holes, and the protruding parts at the inner ends of the set screws are located in the middle through holes of the positioning connecting seats and inserted into the corresponding annular grooves.

[0019] The upper elastic sleeve and the lower elastic sleeve are metal sleeves, and their outer side walls are cylindrical.

[0020] Multiple left cutting grooves and right cutting grooves are formed on the side plates of the upper elastic sleeve and the lower elastic sleeve. The left cutting grooves extend from the left end of the upper elastic sleeve or the lower elastic sleeve to the right to the right part, and the right cutting grooves extend from the right end of the upper elastic sleeve or the lower elastic sleeve to the left to the left part.

[0021] Among the upper elastic sleeve and the lower elastic sleeve, all the left cutting grooves and the right cutting grooves are arranged at intervals.

[0022] The prominent effect of the present invention is:

[0023] By using the natural frequency and the first-order vibration mode of the test system, and applying a relatively small alternating load whose excitation frequency is close to the natural frequency, the test system will generate a large reciprocating vibration response along the vertical center line where the centers of the two mounting through holes of the connecting rod are located. At this time, by adjusting the excitation frequency, the purpose of applying the required load can be achieved.

[0024] Compared with the prior art, it utilizes the resonance principle, uses the electromagnetic exciter as the vibration excitation. During the test process, by frequency modulation, it is very easy to obtain the required test load. Its structure is simple, the vibration frequency is high. At the same time, through the weight adjustment of the weight connecting block and the connecting weight block, the vibration load conforms to the actual operation, making the test more accurate. Its manufacturing cost is low and the use effect is good.

[0025] Meanwhile, it is connected to the connecting rod through the upper elastic sleeve and the lower elastic sleeve, and the connecting bush between it and the connecting rod is clamped and fixed to ensure the connection tightness, so that during the detection, the upper elastic sleeve and the lower elastic sleeve will not collide with the connecting rod, ensuring the test accuracy. Description of the drawings:

[0026] Figure 1 is a schematic diagram of the partial structure of the present invention;

[0027] Figure 2 is a partial front view of the present invention;

[0028] Figure 3 is a partial cross-sectional view of the present invention;

[0029] Figure 4 is Figure 3 a partial enlarged view of

[0030] Figure 5 is a partial cross-sectional view of the present invention at a different angle;

[0031] Figure 6 is a schematic diagram of the partial structure of the upper elastic sleeve or the lower elastic sleeve;

[0032] Figure 7 is Figure 6 a partial structure diagram of at a different angle;

[0033] Figure 8 is a schematic diagram of the partial structure of the connecting bush;

[0034] Figure 9 is a partial top view of the present invention;

[0035] Figure 10 is a partial cross-sectional view at the installation connection seat;

[0036] Figure 11 is a schematic diagram of the finite element analysis simulation of the test of the present invention;

[0037] Figure 12 is a schematic diagram of the finite element analysis simulation of the first-order vibration mode of the connecting rod installed with the first vertical guide rod and the second vertical limiting rod;

[0038] Figure 13 is a schematic diagram of the finite element analysis simulation of the first-order vibration mode of the connecting rod without installing the first vertical guide rod and the second vertical limiting rod. Specific implementation manner:

[0039] Example, see Figures 1 to 10As shown in the figure, a resonant link fatigue test device includes a main frame body 200. The bottom frame 301 of the vibrator 300 is fixed in the middle of the top surface of the bottom plate of the main frame body 200. The two ends of the first vertical guide rod 201 are installed on the top plate and the bottom plate of the main frame body 200. The two ends of the second vertical limiting rod 202 are installed on the top plate and the bottom plate of the main frame body 200. The counterweight connection block 60 is located in the middle of the main frame body 200. The first vertical guide rod 201 and the second vertical limiting rod 202 are inserted into the left and right through holes of the counterweight connection block 60 respectively;

[0040] The top end of the transmission rod 302 at the top of the vibrator 300 is pressed against the middle of the bottom surface of the counterweight connection block 60. Among them, a spherical groove is formed in the middle of the bottom surface of the counterweight connection block 60. The top end of the transmission rod 302 is spherical and is pressed against the inner wall surface of the spherical groove, and the two cooperate with each other;

[0041] Two lower connection seats 20 are fixed in the middle of the top surface of the counterweight connection block 60. An upper horizontal fixing plate 70 is arranged below the top plate of the main frame body 200. Two upper connection seats 10 are fixed in the middle of the bottom surface of the upper horizontal fixing plate 70. An upper vertical adjusting screw 71 is fixed in the middle of the upper horizontal fixing plate 70. The top of the upper vertical adjusting screw 71 extends out of the top surface of the upper horizontal fixing plate 70 and passes through the middle through hole of the top plate of the main frame body 200. An upper limit nut 72 is screwed on the top of the upper vertical adjusting screw 71. The bottom surface of the upper limit nut 72 is pressed against the top surface of the top plate of the main frame body 200. Two upper elastic sleeves 30 are installed on the two upper connection seats 10. Two lower elastic sleeves 40 are installed on the two lower connection seats 20. The corresponding upper elastic sleeve 30 and lower elastic sleeve 40 are inserted into the upper and lower installation through holes of the link 100 to be tested;

[0042] The inner side walls at the left and right ends of the upper elastic sleeve 30 and the lower elastic sleeve 40 are conical wall surfaces. Two transverse adjusting screws 50 are respectively inserted into the upper elastic sleeve 30 and the lower elastic sleeve 40. An axial screw-through hole is formed in the middle of the end support block 51. The end support block 51 is screwed into the end of the transverse adjusting screw 50. The outer side wall of the end support block 51 is a conical wall surface and is pressed against the inner side wall at the end of the upper elastic sleeve 30 or the lower elastic sleeve 40. The outer side walls of the upper elastic sleeve 30 and the lower elastic sleeve 40 are pressed against the inner side walls of the corresponding installation through holes of the upper connection seat 10 and the lower connection seat 20. The middle outer side wall of the upper elastic sleeve 30 or the lower elastic sleeve 40 is pressed against the inner side wall of the corresponding installation through hole of the link 100.

[0043] Furthermore, a link bushing 101 is clamped on the inner side wall of the corresponding installation through hole of the link 100. The middle outer side wall of the upper elastic sleeve 30 or the lower elastic sleeve 40 is pressed against the inner side wall of the corresponding link bushing 101.

[0044] Furthermore, the first vertical guide rod 201 is a cylindrical rod, and its outer sidewall is close to or in close contact with the inner sidewall of the left through-hole;

[0045] A vertical guide groove is formed at the inner sidewall of the left through-hole. The top surface of the vertical guide groove extends out of the top surface of the weight connecting block 60. A plurality of vertically arranged balls 1 are inserted into the vertical guide groove. The top surface of the weight connecting block 60 at the left through-hole is fixedly connected with an upper annular plate 2 by bolts. The first vertical guide rod 201 is inserted into the central through-hole of the upper annular plate. The upper annular plate 2 covers the vertical guide groove. All the balls 1 are partially located at the left through-hole and are in close contact with the outer sidewall of the first vertical guide rod 201.

[0046] Furthermore, a plurality of vertically extending inclined sidewalls are formed at the sidewall of the second vertical limiting rod 202, that is, during processing, part of the sidewall of the second vertical limiting rod 202 is trimmed to form part of the inclined sidewalls.

[0047] Part of the outer sidewall of the second vertical limiting rod 202 is in close contact with the inner sidewall of the right through-hole.

[0048] The above structure enables the first vertical guide rod 201 to play a guiding role during the lifting and moving of the weight connecting block 60, while the second vertical limiting rod 202 only plays a limiting role, mainly preventing the weight connecting block 60 from undergoing lateral translation. Therefore, part of the inclined sidewalls are formed on its outer sidewall to reduce the contact area between it and the inner sidewall of the right through-hole.

[0049] Moreover, the first vertical guide rod 201 and the second vertical limiting rod 202 also ensure that the first-order vibration mode of the entire system (the first-order vibration mode refers to the vibration form of the structure at the lowest natural frequency, that is, the fundamental frequency. It is the simplest and most basic mode of the structure vibration, usually manifested as the consistent vibration of the whole structure) is consistent with the application direction of the connecting rod fatigue test load, that is, the vibration of the connecting rod 100 is along the vertical direction of the central vertical line of the connecting rod 100 (the central line where the central holes of the upper mounting through-hole and the lower mounting through-hole of the connecting rod 100 are located), as Figure 12 ; without the first vertical guide rod 201 and the second vertical limiting rod 202, problems such as tilting will occur in the vibration direction of the connecting rod 100, making the tested structure not what is needed and reducing the accuracy, as Figure 13 .

[0050] Furthermore, connecting weight blocks 61 are fixedly connected to the left and right parts of the top surface of the weight connecting block 60 by bolts. The connecting weight blocks 61 are arc-shaped blocks. These connecting weight blocks 61 can be increased or decreased according to the test needs, so as to change the total amount between the weight connecting block 60 and the connecting weight blocks 61 and meet the needs of the test loading load.

[0051] The bottom end of the upper vertical adjustment screw rod 71 is formed with a spherical part having an outer diameter larger than that of the upper vertical adjustment screw rod 71. The middle part of the upper horizontal fixing plate 70 is formed with a vertical screw connection through hole. The inner side wall of the bottom end of the vertical screw connection through hole is a conical wall surface. The upper vertical adjustment screw rod 71 is screwed in the vertical screw connection through hole, and the outer side wall of the upper part of the spherical part is pressed against the conical wall surface at the bottom of the vertical screw connection through hole.

[0052] Upper vertical guiding through holes are formed in both the left part and the right part of the upper horizontal fixing plate 70. The upper parts of the first vertical guiding rod 201 and the second vertical limiting rod 202 are inserted into the corresponding upper vertical guiding through holes.

[0053] The tops of the first vertical guiding rod 201 and the second vertical limiting rod 202 are clamped in the corresponding upper vertical through holes formed in the top plate of the main frame body 200. The bottoms of the first vertical guiding rod 201 and the second vertical limiting rod 202 are inserted into the corresponding concave holes on the top surface of the bottom plate of the main frame body 200. The outer side walls are pressed against the inner side walls of the corresponding concave holes on the top surface of the bottom plate of the main frame body 200. Two positioning connection seats 80 are fixed on the top surface of the bottom plate of the main frame body 200. The lower parts of the first vertical guiding rod 201 and the second vertical limiting rod 202 are inserted into the middle through holes of the corresponding positioning connection seats 80. Annular grooves are formed on the outer side walls of the lower parts of the first vertical guiding rod 201 and the second vertical limiting rod 202. Multiple radially extending screw connection through holes are formed on the outer side walls of the side plates of the positioning connection seats 80. The fastening bolts 81 are screwed in the corresponding screw connection through holes. The protruding parts at the inner ends of the fastening bolts 81 are located in the middle through holes of the positioning connection seats 80 and inserted into the corresponding annular grooves.

[0054] The bottom ends of the first vertical guiding rod 201 and the second vertical limiting rod 202 are limited through the positioning connection seats 80 and the fastening bolts 81, preventing the first vertical guiding rod 201 and the second vertical limiting rod 202 from disengaging from the concave holes at the bottom, and further realizing limiting and fixing.

[0055] Furthermore, the upper connection seat 10 includes an upper fixed connection block 11 and an upper connection block 12 fixed to the bottom surface of the upper fixed connection block 11 through bolts. The upper fixed connection block 11 is fixed to the middle of the bottom surface of the upper horizontal fixing plate 70. A upper semi-circular groove is formed in the middle of the bottom surface of the upper fixed connection block 11. A lower semi-circular groove is formed in the middle of the top surface of the upper connection block 12. The upper semi-circular groove and the lower semi-circular groove form an installation through hole. The end of the upper elastic sleeve 30 is inserted into the installation through hole, and its outer side wall is pressed against the inner side wall of the corresponding installation through hole.

[0056] The lower connecting seat 20 includes a lower fixed connecting block 21 and a lower connecting block 22 fixed to the top surface of the lower fixed connecting block 21 by bolts. The bottom surface of the lower fixed connecting block 21 is fixed to the middle of the top surface of the counterweight connecting block 60. A first lower semi-circular groove is formed in the middle of the top surface of the lower fixed connecting block 21, and a second lower semi-circular groove is formed in the middle of the bottom surface of the lower connecting block 22. The first lower semi-circular groove and the second lower semi-circular groove form an installation through hole. The end of the lower elastic sleeve 40 is inserted into the installation through hole of the lower connecting seat 20, and its outer side wall is pressed against the inner side wall of the corresponding installation through hole.

[0057] The upper and lower installation through holes of the connecting rod 100 to be tested are inserted with corresponding upper elastic sleeves 30 and lower elastic sleeves 40; a connecting rod bushing 101 is clamped and fixed on the inner side wall of the corresponding installation through hole of the connecting rod 100 by interference fit. The outer side wall of the middle part of the upper elastic sleeve 30 or the lower elastic sleeve 40 is pressed against the inner side wall of the corresponding connecting rod bushing 101. Among them, lubricating grooves are formed on the inner side wall of the connecting rod bushing 101.

[0058] Furthermore, a rotating part protruding outward is formed in the middle of the outer end of the end support block 51, and the outer end of the axial screw-through hole extends out of the outer end face of the rotating part.

[0059] Furthermore, the upper elastic sleeve 30 and the lower elastic sleeve 40 are metal sleeves, and their outer side walls are cylindrical;

[0060] A plurality of left cutting grooves 31 and right cutting grooves 32 are formed on the side plates of the upper elastic sleeve 30 and the lower elastic sleeve 40. The left cutting grooves 31 extend from the left end of the upper elastic sleeve 30 or the lower elastic sleeve 40 to the right to the right part, and the right cutting grooves 32 extend from the right end of the upper elastic sleeve 30 or the lower elastic sleeve 40 to the left to the left part.

[0061] Furthermore, among the upper elastic sleeve 30 and the lower elastic sleeve 40, all the left cutting grooves 31 and the right cutting grooves 32 are arranged at intervals.

[0062] Furthermore, three left cutting grooves 31 and three right cutting grooves 32 are formed on both the upper elastic sleeve 30 and the lower elastic sleeve 40. The three left cutting grooves 31 are evenly distributed on the upper elastic sleeve 30 or the lower elastic sleeve 40 with the central axis of the upper elastic sleeve 30 or the lower elastic sleeve 40 as the center, and the three right cutting grooves 32 are evenly distributed on the upper elastic sleeve 30 or the lower elastic sleeve 40 with the central axis of the upper elastic sleeve 30 or the lower elastic sleeve 40 as the center.

[0063] Figure 11 It is a schematic diagram of the finite element analysis simulation of the test in this embodiment.

[0064] During the installation of this embodiment, first, the middle parts of the upper elastic sleeve 30 and the lower elastic sleeve 40 are inserted into the connecting bushing 101 at the corresponding installation through holes of the connecting rod 100. Then, the two ends of the upper elastic sleeve 30 and the lower elastic sleeve 40 are inserted into the corresponding installation through holes of the upper connecting seat 10 and the corresponding installation through holes of the lower connecting seat 20. The two transverse adjusting screws 50 are respectively inserted into the upper elastic sleeve 30 and the lower elastic sleeve 40, and the end support blocks 51 are screwed into the ends of the transverse adjusting screws 50. Rotate the rotating part formed in the middle of the outer end face of the end support block 51 to make the end support block 51 rotate, so that the outer side wall of the end support block 51 presses against the inner side wall at the end of the upper elastic sleeve 30 or the lower elastic sleeve 40. As the end support block 51 moves inward, the outer side walls of the upper elastic sleeve 30 and the lower elastic sleeve 40 are pushed outward, so that their outer side walls press against the inner side walls of the corresponding installation through holes of the upper connecting seat 10 and the lower connecting seat 20, and the outer side wall of the middle part of the upper elastic sleeve 30 or the lower elastic sleeve 40 presses against the inner side wall of the connecting bushing 101 of the corresponding installation through hole of the connecting rod 100 to achieve clamping and fixing;

[0065] The installation is completed. This structure makes the inner side wall of the connecting bushing 101 of the connecting rod 100 and the outer side wall of the upper elastic sleeve 30 or the lower elastic sleeve 40 in close connection, eliminating the gap, so that during subsequent tests, no impact load will be generated between the two, ensuring the accuracy of the test. That is, considering that it is difficult for the fatigue testing machine to reproduce the actual operating conditions of the connecting rod and cannot form a lubricating oil film to reduce the impact load of the hole / axis clearance, abnormal failure will occur. To solve this problem, the upper elastic sleeve 30 and the lower elastic sleeve 40 with adjustable clearance elimination are adopted to avoid incorrect test results and ensure the test accuracy.

[0066] At the same time, according to the need, connecting counterweight blocks 61 of corresponding weights are fixedly connected to the left and right parts of the top surface of the counterweight connecting block 60 through bolts to meet the load requirement, thereby changing the vibration frequency of the transmission rod 302.

[0067] The specific method is as follows: During the test, strain gauges (which are known components and will not be elaborated here) are attached to the rod body of the connecting rod 100. The frequency of the exciter 300 is adjusted. For example, it is adjusted upward from 200 Hz. At this time, the counterweight block 61 is not fixedly connected to the top surface of the counterweight connecting block 60. Observe the values of the strain gauges (the strain gauges are electrically connected to the control host through electrical connection wires, and the corresponding values are displayed on the display screen of the control host). When the values rise rapidly, it indicates that the frequency of the exciter 300 at this time is close to or equal to the overall natural frequency of this embodiment. At this time, the test can be carried out. The connecting rod 100 undergoes fatigue failure during this process, that is, crack initiation and rapid propagation occur. Then, the stiffness of the test system changes, and the natural frequency also changes accordingly. The system acceleration will be significantly different from that before failure. When this difference reaches the specified limit value, the test ends, and a life-load value is obtained as the result of this test. When the test reaches 5x10 6 cycles, if the connecting rod 100 does not undergo failure and damage, the test ends.

[0068] Then, a new round of test is carried out. At this time, the load applied to the connecting rod 100 needs to be changed. Change the weight of the counterweight block 61 to change the overall natural frequency. Adjust the frequency of the exciter 300 and observe the stress value at the same time. When the stress value rises sharply, it indicates that the system frequency is close to the frequency of the exciter 300, thus achieving resonance. This stress value is the load applied to the connecting rod 100, and the test can be carried out. The test process is the same as above and will not be elaborated.

[0069] That is, change the frequency of the exciter 300 and the number of counterweight blocks 61 connected. When the strain value of the connecting rod 100 measured by the strain gauge changes rapidly, it indicates that the frequency adjustment is completed, and the test can be carried out. Repeat the above process to conduct the fatigue test and obtain the test result of the next time. Conduct the test in such a cycle until the test points of the connecting rod 100 required by the confidence level are obtained; statistically analyze the life-load values of all failed specimens, and the fatigue limit result of the test can be obtained.

[0070] Finally, it should be pointed out that the above embodiments are only relatively representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and can have many variations. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention should be considered to fall within the protection scope of the present invention.

Claims

1. A resonant connecting rod fatigue test device, comprising a main frame (200), characterized in that: A bottom frame (301) of the vibration exciter (300) is fixed to the middle of the top surface of the bottom plate of the main frame (200), two ends of the first vertical guide rod (201) are mounted on the top plate and the bottom plate of the main frame (200), two ends of the second vertical limit rod (202) are mounted on the top plate and the bottom plate of the main frame (200), the counterweight connecting block (60) is located in the middle of the main frame (200), and the first vertical guide rod (201) and the second vertical limit rod (202) are inserted into the left through hole and the right through hole of the counterweight connecting block (60); The top end of the transmission rod (302) at the top of the exciter (300) is pressed against the middle of the bottom surface of the counterweight connecting block (60), and two lower connecting seats (20) are fixed to the middle of the top surface of the counterweight connecting block (60). An upper horizontal fixing plate (70) is provided below the top plate of the main frame (200), and two upper connecting seats (10) are fixed to the middle of the bottom surface of the upper horizontal fixing plate (70). An upper vertical adjustment screw (71) is fixed to the middle of the upper horizontal fixing plate (70), and the top of the upper vertical adjustment screw (71) protrudes out of the upper horizontal fixing plate ( The upper surface of the upper vertical adjustment screw (70) is threaded with an upper limit nut (72) at the top of the upper vertical adjustment screw (71), and the bottom surface of the upper limit nut (72) is pressed against the top surface of the top plate of the main frame (200). The two upper connecting seats (10) are equipped with upper elastic sleeves (30), and the two lower connecting seats (20) are equipped with lower elastic sleeves (40). The upper and lower mounting through holes of the connecting rod (100) to be tested are inserted with corresponding upper elastic sleeves (30) and lower elastic sleeves (40); The inner side walls of the left and right ends of the upper elastic sleeve (30) and the lower elastic sleeve (40) are tapered wall surfaces. Two transverse adjustment screws (50) are respectively inserted into the upper elastic sleeve (30) and the lower elastic sleeve (40). An axial screw connection through hole is formed in the middle of the end support block (51). The end support block (51) is screwed into the end of the transverse adjustment screw (50). The outer side wall of the end support block (51) is tapered wall surface, which is pressed against the inner side wall at the end of the upper elastic sleeve (30) or the lower elastic sleeve (40). The outer side walls of the upper elastic sleeve (30) and the lower elastic sleeve (40) are pressed against the inner side walls of the corresponding mounting through holes of the upper connecting seat (10) and the lower connecting seat (20). The middle outer side wall of the upper elastic sleeve (30) or the lower elastic sleeve (40) is pressed against the inner side wall of the corresponding mounting through hole of the connecting rod (100).

2. A resonant connecting rod fatigue testing device according to claim 1, characterized in that: A connecting rod bushing (101) is clamped on the inner side wall of the corresponding mounting through hole of the connecting rod (100), and the middle outer side wall of the upper elastic sleeve (30) or the lower elastic sleeve (40) is pressed against the inner side wall of the corresponding connecting rod bushing (101).

3. The resonant connecting rod fatigue testing device according to claim 1, characterized in that: The first vertical guide rod (201) is a cylindrical rod body, and its outer side wall is close to or in close contact with the inner side wall of the left through hole; A vertical guide groove is formed on the inner wall of the left through hole, the top surface of the vertical guide groove extends out of the top surface of the counterweight connecting block (60), a plurality of vertically arranged balls (1) are inserted into the vertical guide groove, the top surface of the counterweight connecting block (60) at the left through hole is fixedly connected to an upper annular plate (2) by bolts, the first vertical guide rod (201) is inserted into the middle through hole of the upper annular plate, the upper annular plate (2) covers the vertical guide groove, all the balls (1) are partially located at the left through hole, and are closely attached to the outer wall of the first vertical guide rod (201).

4. A resonant connecting rod fatigue testing device according to claim 1, characterized in that: A plurality of vertically extending oblique side walls are formed on the side wall of the second vertical limiting rod (202), and part of the outer side wall of the second vertical limiting rod (202) is in close contact with the inner side wall of the right through hole.

5. The resonant connecting rod fatigue testing device according to claim 1, characterized in that: The left and right parts of the top surface of the counterweight connecting block (60) are both fixedly connected to a connecting counterweight block (61) by means of bolts.

6. The resonant connecting rod fatigue testing device according to claim 1, characterized in that: The bottom end of the upper vertical adjustment screw (71) is formed with a spherical portion whose outer diameter is larger than that of the upper vertical adjustment screw (71); a vertical screw connection hole is formed in the middle of the upper horizontal fixing plate (70); the inner side wall of the bottom end of the vertical screw connection hole is a conical wall surface; the upper vertical adjustment screw (71) is screwed into the vertical screw connection hole; the upper outer side wall of the spherical portion is pressed against the conical wall surface of the bottom of the vertical screw connection hole.

7. The resonant connecting rod fatigue testing device according to claim 1, characterized in that: The left and right parts of the upper horizontal fixing plate (70) are both formed with upper vertical guide through holes, and the upper parts of the first vertical guide rod (201) and the second vertical limiting rod (202) are inserted into the corresponding upper vertical guide through holes; The tops of the first vertical guide rod (201) and the second vertical limit rod (202) are mounted in corresponding upper vertical through holes formed on the top plate of the main frame (200), and the bottoms of the first vertical guide rod (201) and the second vertical limit rod (202) are inserted into corresponding concave holes on the top surface of the bottom plate of the main frame (200). Two positioning connection seats (80) are fixed on the top surface of the bottom plate of the main frame (200). The first vertical guide rod (201) and the second vertical limit rod (202) are connected to the top plate of the main frame (200). 2) is inserted into the middle through hole of the corresponding positioning connection seat (80), an annular groove is formed on the lower outer wall of the first vertical guide rod (201) and the second vertical limit rod (202), and a plurality of radially extending screw through holes are formed on the outer wall of the side plate of the positioning connection seat (80), and the fixing bolt (81) is screwed into the corresponding screw through hole, and the protrusion at the inner end of the fixing bolt (81) is located in the middle through hole of the positioning connection seat (80) and inserted into the corresponding annular groove.

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