CN209878482U - Device for testing fatigue mechanical properties of material under tensile-bending composite load - Google Patents

Abstract

The utility model relates to a material fatigue mechanical properties testing arrangement under tensile-crooked combined load belongs to accurate scientific instrument and material test field. Including vibration isolation base, braced frame, supersound loading module, hydraulic pressure loading module, tensile loading module, ultrasonic inspection module, braced frame links to each other with the vibration isolation base, and hydraulic pressure loading module passes through flange and links to each other with braced frame, and supersound loading module passes through the screw and links to each other with hydraulic pressure loading module, and tensile loading module, ultrasonic inspection module set up on the vibration isolation base. Has the advantages that: the span-range loading with high frequency and high load can be realized; the ultrahigh frequency bending fatigue loading and the stretching-bending static and dynamic composite loading can be realized; the tensile loading module can ensure that the tested material sample is accurately centered. The high-frequency fatigue test device can be used for performing high-frequency fatigue tests on tested material samples of different materials and different sizes under static and dynamic composite loads, and provides a reliable means for service performance analysis of key materials in aerospace and numerous fields.

Description

Testing device for fatigue mechanical properties of materials under tensile-bending composite load

technical field

The utility model relates to the field of precision scientific instruments and material testing, in particular to a device for testing the fatigue mechanical properties of materials under tensile-bending composite loads. The device can carry out several tests such as traditional static tensile loading test, high-frequency bending fatigue loading test, ultra-high frequency bending fatigue loading test, etc., and can also realize tensile-bending composite loading high frequency under frequency and load cross-range loading Fatigue test, in-situ monitoring of the crack generation and propagation of the tested material during the test, provides a test method for revealing the correlation law between the fatigue mechanical properties of the tested material and the applied load and the fatigue damage mechanism.

Background technique

In recent decades, with the rapid progress of national science and technology and the vigorous development of the national economy, people have put forward more stringent requirements on the safety, reliability and economy of mechanical equipment. Fatigue failure is very common in engineering practice and involves a wide range of fields. According to incomplete statistics, fatigue failure accounts for about 80% of the total failure of materials. Especially in the fields of key materials such as aviation, aerospace and nuclear industry, materials are subjected to tension, bending alternating loads and composite loads under typical service conditions, and the frequency can be as high as thousands of hertz, resulting in aviation, aerospace equipment and other key machinery. High-frequency fatigue fractures of structures occur frequently, causing serious economic losses.

At present, conventional fatigue tests are carried out on commercialized electro-hydraulic servo fatigue testing machines, ultrasonic fatigue testing machines, rotating bending fatigue testing machines, etc., which can only achieve single-load fatigue loading such as conventional tensile/compression fatigue and bending fatigue, and are difficult to achieve. Fatigue tests under multi-load composite loading cannot be simulated under the composite load state of materials under actual service conditions. Therefore, for many fields, especially key material fields such as aviation, aerospace and nuclear industry, it has become an urgent need to develop high-frequency fatigue mechanical performance testing technology and high-frequency fatigue mechanical performance testing equipment under the action of composite loads of key structural materials. key issues to be resolved.

Contents of the invention

The purpose of this utility model is to provide a material fatigue mechanical performance test device under tensile-bending composite load, which can solve the problem that the existing test method cannot realize the loading of frequency and load across the range and the ultra-high Frequent fatigue loading problem. The device can carry out several tests such as traditional static tensile loading test, high-frequency bending fatigue loading test, ultra-high frequency bending fatigue test, etc., and can also realize tensile-bending composite loading high-frequency fatigue under frequency and load cross-range loading The experiment is to monitor the crack generation and propagation of the tested material in situ during the test, and provide a test method for revealing the correlation law between the fatigue mechanical properties of the tested material and the applied load and the fatigue damage mechanism. It provides a reliable means to analyze the mechanical properties of key structural materials in many fields.

Above-mentioned purpose of the utility model is realized through the following technical solutions:

The device for testing the fatigue mechanical properties of materials under tensile-bending composite loads adopts a four-column vertical symmetrical arrangement as a whole, including a vibration isolation base 1, a support frame 2, an ultrasonic loading module 3, a hydraulic loading module 4, a tensile loading module 5, Ultrasonic flaw detection module 6, the support frame 2 is connected to the vibration isolation base 1 through threads, the hydraulic loading module 4 is connected to the support frame 2 through connecting flanges, the ultrasonic loading module 3 is connected to the hydraulic loading module 4 through threads, and the tensile loading The module 5 is set on the vibration isolation base 1 , and the ultrasonic flaw detection module 6 is set on the vibration isolation base 1 .

The vibration isolation base 1 is: the vibration isolation platform 11 is connected with the marble base 12 by screws; the support frame 2 adopts a four-column vertical structure, and the upper support plate 9 is connected with four columns 7 by screws, and the columns 7 It is connected with the vibration isolation base 1 through threads, the connection block c10 is fixed on the column 7, and connected with the hydraulic connection plate 8 through screws to achieve stable support for the device.

The hydraulic loading module 4 has the functions of static bending loading and high-frequency bending fatigue loading, and realizes static bending loading or 0-100 Hz high-frequency bending fatigue loading on the tested material sample; the accumulator 22, the hydraulic pipeline 25 and the The hydraulic valve plate 21 is connected, and the hydraulic valve plate 21 is connected with the high-frequency servo hydraulic cylinder 24; the hydraulic cylinder protective sleeve 23 and the end of the high-frequency servo hydraulic cylinder 24 are fixed by bolts, and the hydraulic flange 26 is connected with the high-frequency servo hydraulic cylinder 24 piston rod The protruding ends are connected by bolts; one end of the expansion sleeve 20 is connected with the end of the piston rod of the high-frequency servo hydraulic cylinder 24 , and the other end is connected with the tension sensor 27 .

The ultrasonic loading module 3 is connected to the hydraulic loading module 4 through the connecting plate 16 to realize 20 kHz UHF bending fatigue loading on the UHF bending fatigue sample 33; the ultrasonic connector 18 is connected to the ultrasonic transducer 17, The horn 13 is connected with the ultrasonic connector 18, the ultrasonic bending indenter 19 is connected with the horn 13; the ultrasonic connecting plate 14 is fixed on the shoulder of the ultrasonic connector 18, one end of the dowel 15 is connected with the connecting plate 16, and the other One end passes through the through hole on the ultrasonic connecting plate 14 and is fixed by a nut.

The tensile loading module 5 includes two sub-modules, the sample centering mechanism 36 and the pin-type stretch-bending composite fixture 32, which respectively realize accurate centering and static tension/compression loading of the tested material sample; Both the centering mechanism 36 and the pin-through-type stretch-bending composite fixture 32 are set on the Y mobile platform 31, and the two sub-modules of the sample centering mechanism 36 and the pin-through-type stretch-bend composite fixture 32 are quickly moved by manually moving the Y mobile platform 31. switch.

Described tensile loading module 5 is: servomotor 28 is fixed by motor fixing plate, links to each other with lead screw a37 that is fixed on lead screw seat a30, lead screw seat b34 through coupling 29, lead screw seat a30, lead screw The seat b34 is fixed on the base 41 by bolts; the slider 35 is assembled with the precision linear guide rail 40 and fixed on the base 41; the Y mobile platform 31 is assembled with the dovetail guide rail 38, and the dovetail guide rail 38 is fixed on the X mobile On the platform 39, the X mobile platform 39 is connected with the slide block 35; when the tensile loading module 5 is working, the servo motor 28 outputs the torque to the lead screw a37 through the shaft coupling 29, and drives the X mobile platform 39 to move in reverse to realize the Precise centering and static tensile loading of test material specimens.

The sample centering mechanism 36 is as follows: the lead screw c54 is set on the connection block a47 and the connection block b57, the support seat 56 is fixed on the connection block a47 and the connection block b57, and the lead screw positioning sleeve 52 is fixed on the lead screw c54 At both ends, the adjustment knob b55 is fixed at the end of the lead screw c54, the sample support seat 49 is fixed on the connection block a47, the axial positioning block 48 is assembled with the lead screw c54, and the guide rail 59 is fixed on the connection block b57 and the lead screw support seat on b61; lead screw d46 and lead screw c54 are respectively fixed on lead screw support seat a50 and lead screw support seat b61, and spline sleeve 45 is assembled with lead screw d46 and lead screw c54; adjusting knob c60 is connected with end of lead screw c54 The positioning block 58 is assembled with the guide rail 59 and the lead screw c54, and the two adjustment knobs a51 are respectively connected with the two positioning blocks 58.

The ultrasonic flaw detection module 6 is set on the vibration isolation base 1. During the test, the ultrasonic probe of the ultrasonic flaw detection module 6 is scanned on the surface of the UHF bending fatigue sample 33, so as to realize the UHF bending fatigue test during the test. In-situ monitoring of surface fatigue cracks of sample 33.

The beneficial effects of the utility model are:

1. Novel structure and compact layout. The loading of the composite load of the utility model is mainly realized by the hydraulic loading module 4, the ultrasonic loading module 3 and the tensile loading module 5, which truly simulates the typical stress state of key structural materials in many fields such as aviation and aerospace under service conditions. The ultrasonic flaw detection testing technology of the ultrasonic flaw detection module 6 realizes the in-situ monitoring of the crack generation and propagation phenomenon of the tested material sample during the testing process. The whole machine adopts modular design. It includes a vibration isolation base 1 , a support frame 2 , an ultrasonic loading module 3 , a hydraulic loading module 4 , a tensile loading module 5 and an ultrasonic flaw detection module 6 in sequence. Standardize equipment and facilitate maintenance.

2. The hydraulic loading and ultrasonic loading functions are integrated on the material fatigue performance testing device at the same time, and several tests such as traditional static tensile loading test, high-frequency bending fatigue loading test, and ultra-high-frequency bending fatigue test can be carried out, and it can also realize Tensile-bending composite loading high-frequency fatigue test under frequency and load cross-range loading.

3. The tensile loading module of the whole machine includes three positive and negative screw screws, which are respectively driven by a motor and manually adjusted to realize the coarse adjustment and fine adjustment of the centering of the tested material sample in the length direction and the centering in the width direction. Accurate alignment, bending fatigue test can be carried out on test material samples of different materials and different sizes.

4. The tensile loading module of the whole machine includes two sub-modules, the pin-type stretch-bending compound fixture 32 and the sample centering mechanism 34, and the switching of the above two sub-modules can be realized by manually adjusting the Y moving platform 31, so as to achieve super The switching between two loading modes of high-frequency bending fatigue loading and high-frequency fatigue loading under tensile-bending composite loading is easy to operate and increases the functions of the device.

5. The utility model can realize the high-frequency fatigue test of tension-bending composite loading under frequency and load cross-range loading, and can monitor the expansion of the crack of the tested material sample in real time, making up for the load coupling loading of the conventional material testing machine and the original Insufficient in position monitoring, it can more realistically simulate the service status of materials in key material fields such as aviation, aerospace and nuclear industry.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the utility model and constitute a part of the application. The schematic examples and descriptions of the utility model are used to explain the utility model and do not constitute improper limitations to the utility model.

Fig. 1 is the overall structural representation of the utility model;

Fig. 2 is a schematic diagram of a support frame and a vibration isolation base of the present invention;

Fig. 3 is the schematic diagram of each part of the ultrasonic loading module of the present invention;

Fig. 4 is a schematic diagram of various parts of the hydraulic loading module of the present invention;

Figures 5 to 7 are schematic diagrams of various parts of the tension loading module of the present invention;

Fig. 8 is a schematic diagram of the loading and detection control system of the ultrasonic loading module of the present invention.

In the figure: 1. Vibration isolation base; 2. Support frame; 3. Ultrasonic loading module; 4. Hydraulic loading module; 5. Tensile loading module; 6. Ultrasonic flaw detection module; 7. Column; 8. Hydraulic cylinder connecting plate ;9, upper support plate; 10, connecting block; 11, vibration isolation platform; 12, marble base; 13, horn; 14, ultrasonic connecting plate; 15, dowel bar; 16, connecting plate; 17, ultrasonic Transducer; 18. Ultrasonic connector; 19. Ultrasonic bending head; 20. Expansion sleeve; 21. Hydraulic valve plate; 22. Accumulator; 23. Hydraulic cylinder protective cover; 24. High frequency servo hydraulic cylinder; 25. Hydraulic pipeline; 26. Hydraulic flange; 27. Pull pressure sensor; 28. Servo motor; 29. Coupling; 30. Screw seat a; 31. Y mobile platform; Fixture; 33. UHF bending fatigue sample; 34. Lead screw seat b; 35. Slider; 36. Sample centering mechanism; 37. Lead screw a; 38. Dovetail guide rail; 39. X mobile platform; 40. Precision linear guide rail; 41. Base; 42. Stretch-bending compound load fatigue specimen; 43. Pin; 44. Clamp body; 45. Spline sleeve; 46. Lead screw d; 47. Connecting block a; 48. Shaft 49. Sample support seat; 50. Lead screw support seat a; 51. Adjustment knob a; 52. Lead screw positioning sleeve; 53. Lead screw b; 54. Lead screw c; 55. Adjustment knob b ; 56, support seat; 57, connecting block b; 58, positioning block; 59, guide rail; 60, adjusting knob c; 61, screw support seat b.

Detailed ways

Further illustrate the detailed content of the utility model and its specific implementation below in conjunction with accompanying drawing.

Referring to Figures 1 to 8, the device for testing the fatigue mechanical properties of materials under tensile-bending composite loads of the present utility model can realize frequency (high frequency: 0~100Hz, ultrahigh frequency: 20kHz), load (0~20kN ) cross-range loading; can realize ultra-high frequency bending fatigue loading and tensile-bending static and dynamic composite load loading; the designed tensile loading module can ensure the accurate centering of the tested material sample, and can be used for different materials and different sizes The tested material samples are subjected to high-frequency fatigue tests under static and dynamic combined loads, which provide a reliable means for the service performance analysis of key materials in aerospace and many fields. The device includes a vibration isolation base 1 , a support frame 2 , an ultrasonic loading module 3 , a hydraulic loading module 4 , a tensile loading module 5 , and an ultrasonic flaw detection module 6 . The support frame 2 is connected to the vibration isolation base 1 through threads; the hydraulic loading module 4 is connected to the support frame 2 through a connecting flange to realize high-frequency bending fatigue loading of the tested material sample; the ultrasonic loading module 3 is connected to the vibration isolation base 1 through threads. The hydraulic loading module 4 is connected to realize UHF bending fatigue loading on the tested material sample; the tensile loading module 5 is set on the vibration isolation base 1 to realize accurate centering and static stretching of the tested material sample Loading; the ultrasonic flaw detection module 6 is set on the vibration isolation base 1 to realize the in-situ monitoring of the UHF bending fatigue sample 33 . The device can carry out several traditional tests such as traditional static tensile loading test, high-frequency bending fatigue loading test, ultra-high frequency bending fatigue test, etc., and can also realize tensile-bending composite loading high frequency under frequency and load cross-range loading Fatigue experiment.

Referring to Fig. 2, the vibration isolation base 1 and support frame 2 of the present invention are mainly composed of column 7, hydraulic cylinder connection plate 8, upper support plate 9, connection block c10, vibration isolation platform 11, and marble base 12. Among them, the vibration isolation platform 11 is connected with the marble base 12 through threads, the upright column 7 is connected with the marble base 12 through end threads, the upper support plate 9 is connected with the upright column through screws, the connecting block c10 is fixed on the upright column 7, and the hydraulic cylinder connecting plate 8 and the connecting block c10 are connected by screws. It is mainly used to achieve stable support for the device and to provide effective vibration isolation during the test.

Referring to Fig. 3, the ultrasonic loading module 3 of the present invention is mainly composed of a horn 13, an ultrasonic connecting plate 14, a dowel 15, a connecting plate 16, an ultrasonic transducer 17, an ultrasonic connector 18, an ultrasonic bending indenter 19 compositions. Wherein, the ultrasonic connector 18 is connected to the ultrasonic transducer 17 through a stud, the horn 13 is connected to the ultrasonic connector 18 through a stud, and the ultrasonic bending indenter 19 is connected to the horn 13 through a stud. The ultrasonic connecting plate 14 is fixed on the shoulder of the ultrasonic connector 18. One end of the dowel 15 is connected to the connecting plate 16 through the thread at its end, and the other end passes through the through hole on the ultrasonic connecting plate 14 and is fixed by a nut. When the ultrasonic loading module is working, the ultrasonic frequency generator converts the 50 Hz electrical signal provided by the power supply into a 20 kHz electrical signal, and converts it into a mechanical vibration signal of the same frequency through the ultrasonic transducer 17, and passes through the ultrasonic connector 18, the horn 13 The two-stage amplification of the UHF (20 kHz) bending fatigue loading on the UHF bending fatigue specimen 33 is finally realized through the ultrasonic bending indenter 19 .

Referring to Fig. 4, the hydraulic loading module 4 of the present utility model is mainly composed of an expansion sleeve 20, a hydraulic valve plate 21, an accumulator 22, a hydraulic cylinder protective sleeve 23, a high-frequency servo hydraulic cylinder 24, a hydraulic pipeline 25, a hydraulic method Blue plate 26, pull pressure sensor 27 form. Wherein, the accumulator 22 and the hydraulic pipeline 25 are connected with the hydraulic valve plate 21, and the hydraulic valve plate 21 is connected with the high-frequency servo hydraulic cylinder 24 through bolts. The hydraulic cylinder protective sleeve 23 is fixed to the end of the high-frequency servo hydraulic cylinder 24 by bolts, and the hydraulic flange 26 is connected to the extended end of the piston rod of the high-frequency servo hydraulic cylinder 24 by bolts. One end of the expansion sleeve 20 is connected with the end of the piston rod of the high-frequency servo hydraulic cylinder 24 , and the other end is connected with the pull pressure sensor 27 . When the hydraulic loading module is working, the high-pressure oil output from the oil source passes through the filter, and the accumulator 22 enters the electro-hydraulic servo valve. At the same time, the electrical signal given by the electronic control system is compared with the feedback signal output from the pull pressure sensor 27. And the difference is amplified and sent to the electro-hydraulic servo valve to convert the electrical signal into the flow of high-pressure oil. The high-pressure oil is input to the upper and lower ends of the high-frequency servo hydraulic cylinder 24 to drive the piston to move, and then transmit it in turn through the dowel rod. The ultrasonic bending indenter 19 is used to realize static bending loading or high-frequency bending fatigue loading (0-100 Hz) of the material sample to be tested.

As shown in FIG. 5 , the tensile loading module 5 of the present invention is mainly used to realize accurate centering and tensile loading of the tested material sample. Its composition includes: servo motor (including reducer) 28, coupling 29, screw seat 30, Y moving platform 31, pin-type stretch-bending compound fixture 32, screw seat 30, slider 35, sample centering Mechanism 36, lead screw a37, dovetail guide rail 38, X moving platform 39, precision linear guide rail 40, base 41. Wherein, the servo motor 28 is fixed by the motor fixing plate, and is connected with the lead screw a37 fixed on the lead screw seat a30 and the lead screw seat b34 through the coupling 29, and the lead screw seat a30 and the lead screw seat b34 are fixed on the base 41 by bolts. superior. The slide block 35 is assembled with the precision linear guide rail 40 and fixed on the base 41 by hexagon socket bolts. The Y mobile platform 31 is assembled with the dovetail guide rail 38, and the dovetail guide rail 38 is fixed on the X mobile platform 39 by bolts, and the X mobile platform 39 is connected with the slide block 35 by screws. The pin-type stretch-bending composite fixture 32 and the sample centering mechanism 36 are connected to the Y moving platform 31 through bolts, and the switching of the two modules can be realized by manually adjusting the Y moving platform 31 . When the tensile loading module is working, the servo motor 28 outputs the torque to the lead screw 37 through the coupling 29, driving the X moving platform 39 to move in reverse, which can realize accurate centering and static tensile loading of the tested material sample .

As shown in FIG. 6 , the pin-through-type tensile-bending composite clamp 32 of the present invention is mainly composed of a tensile-bending composite load fatigue sample 42 , a pin 43 , and a clamp body 44 . The pin 43 passes through the through hole on the tensile-bending composite load fatigue specimen 42 and the clamp body 44 and is fixed by a nut, mainly used to provide clamping and supporting functions for the tensile-bending composite load fatigue specimen 42 .

Referring to FIG. 7 , the sample centering mechanism 36 of the present invention is mainly used for precise centering of the UHF bending fatigue sample 33 . Its composition includes: spline sleeve 45, lead screw d46, connection block a47, axial positioning block 48, sample support seat 49, lead screw support seat 50, adjustment knob a51, lead screw positioning sleeve 52, lead screw b53, Lead screw c54, adjustment knob b55, support seat 56, connection block b57, positioning block 58, guide rail 59, adjustment knob c60, lead screw support seat b61. Among them, the lead screw c54 is arranged on the connection block a47 and the connection block b57, the support seat 56 is fixed on the connection block a47 and the connection block b57 by screws, the lead screw positioning sleeve 52 is fixed on both ends of the lead screw c54, and the adjustment knob b55 is fixed At the end of the lead screw c54, the sample support seat 49 is fixed on the connection block a47 by screws, the axial positioning block 48 is assembled with the lead screw c54, and the guide rail 59 is fixed on the connection block b57 and the lead screw support seat 61. The leading screw d46 and the leading screw c54 are respectively fixed on the leading screw supporting seat a50 and the leading screw supporting seat b61, and the spline sleeve 45 is assembled with the leading screw d46 and the leading screw c54. The adjustment knob c60 is connected to the end of the lead screw c54, the positioning block 58 is assembled with the guide rail 59 and the lead screw c54, and the two adjustment knobs a51 are connected to the two positioning blocks 58 respectively. When the sub-module of the sample centering mechanism is working, the servo motor 28 outputs the torque to the lead screw d46 through the coupling 29, driving the X moving platform 39 to move in the opposite direction, and turning the adjustment knob a51 drives the lead screw b53 and the lead screw c54 (two The direction of rotation is opposite to the direction of rotation) to drive the two positioning blocks 58 to move toward each other to complete the coarse adjustment and fine adjustment of the centering of the measured material sample in the length direction; turn the adjustment knob b55 to drive the screw b53 to rotate and drive the two axial positioning The blocks 48 move toward each other to realize accurate centering of the UHF bending fatigue sample 33 in the width direction.

The above descriptions are only preferred examples of the utility model, and are not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made to the utility model shall be included in the protection scope of the utility model.

Claims (8)

1. A device for testing the fatigue mechanical properties of materials under a tensile-bending composite load, characterized in that: the device as a whole adopts a four-column vertical symmetrical arrangement, including a vibration isolation base (1), a support frame (2), an ultrasonic loading module ( 3), a hydraulic loading module (4), a tensile loading module (5), an ultrasonic flaw detection module (6), the support frame (2) is connected to the vibration isolation base (1) through threads, and the hydraulic loading module (4) The connecting flange is connected to the support frame (2), the ultrasonic loading module (3) is connected to the hydraulic loading module (4) through threads, the tensile loading module (5) is set on the vibration isolation base (1), and the ultrasonic flaw detection module (6) Set on the vibration isolation base (1). 2. the tensile-bending compound load under the material fatigue mechanical property testing device according to claim 1, is characterized in that: described vibration-isolation base (1) is: vibration-isolation platform (11) passes screw and marble base The seat (12) is connected; the support frame (2) adopts a four-column vertical structure, and the upper support plate (9) is connected with the four columns (7) by screws, and the column (7) is threaded with the vibration-isolation base (1 ), the connection block c (10) is fixed on the column (7), and is connected with the hydraulic connection plate (8) by screws to realize stable support for the device. 3. The device for testing material fatigue mechanical properties under tensile-bending composite load according to claim 1, characterized in that: the hydraulic loading module (4) has functions of static bending loading and high-frequency bending fatigue loading, realizing the Static bending loading or 0-100 Hz high-frequency bending fatigue loading of the material sample to be tested; the accumulator (22), hydraulic pipeline (25) is connected to the hydraulic valve plate (21), and the hydraulic valve plate (21) is connected to the high-frequency The servo hydraulic cylinder (24) is connected; the hydraulic cylinder protective cover (23) and the end of the high-frequency servo hydraulic cylinder (24) are fixed by bolts, and the hydraulic flange (26) is connected to the piston rod extension end of the high-frequency servo hydraulic cylinder (24) It is connected by bolts; one end of the expansion sleeve (20) is connected with the end of the piston rod of the high-frequency servo hydraulic cylinder (24), and the other end is connected with the tension pressure sensor (27). 4. The device for testing the fatigue mechanical properties of materials under tensile-bending composite loads according to claim 1, characterized in that: the ultrasonic loading module (3) is connected to the hydraulic loading module (4) through a connecting plate (16) , to realize 20 kHz UHF bending fatigue loading on the UHF bending fatigue specimen (33); the ultrasonic connector (18) is connected to the ultrasonic transducer 17, and the horn (13) is connected to the ultrasonic connector (18) The ultrasonic bending indenter (19) is connected with the horn (13); the ultrasonic connecting plate (14) is fixed on the shoulder of the ultrasonic connector (18), and one end of the dowel rod (15) is connected with the connecting plate (16) connected, and the other end passes through the through hole on the ultrasonic connecting plate (14), and is fixed by a nut. 5. The device for testing the fatigue mechanical properties of materials under tensile-bending composite load according to claim 1, characterized in that: the tensile loading module (5) includes a sample centering mechanism (36) and a pin-type The two sub-modules of the tension-bending composite fixture (32) respectively realize accurate centering and static tension/compression loading of the material sample to be tested; They are all arranged on the Y mobile platform (31), and the quick switching of the two sub-modules of the sample centering mechanism (36) and the pin-type stretch-bending composite fixture (32) is completed by manually moving the Y mobile platform (31). 6. The device for testing material fatigue mechanical properties under tensile-bending composite load according to claim 1 or 5, characterized in that: the tensile loading module (5) is: the servo motor (28) fixes the plate through the motor Fixed, link to each other with the lead screw a (37) fixed on the lead screw seat a (30) and lead screw seat b (34) through the shaft coupling (29), the lead screw seat a (30), lead screw seat b ( 34) It is fixed on the base (41) by bolts; the slider (35) is assembled with the precision linear guide rail (40) and fixed on the base (41); the Y moving platform (31) and the dovetail guide rail (38) Assembled together, the dovetail guide rail (38) is fixed on the X mobile platform (39), and the X mobile platform (39) is connected with the slider (35); when the tensile loading module (5) is working, the servo motor (28) passes The shaft coupling (29) outputs the torque to the lead screw a (37), driving the X moving platform (39) to move in reverse, so as to realize accurate centering and static tensile loading of the tested material sample. 7. The device for testing the fatigue mechanical properties of materials under tensile-bending composite loads according to claim 5, characterized in that: the sample centering mechanism (36) is: the screw c (54) is set on the connecting block a (47), connecting block b (57), the support seat (56) is fixed on the connecting block a (47), connecting block b (57), the lead screw positioning sleeve (52) is fixed on the lead screw c (54 ), the adjustment knob b (55) is fixed at the end of the lead screw c (54), the sample support seat (49) is fixed on the connection block a (47), the axial positioning block (48) and the lead screw c (54 ) are assembled together, the guide rail (59) is fixed on the connection block b (57) and the screw support base b (61); the screw d (46) and the screw c (54) are respectively fixed on the screw support base a ( 50), on the lead screw support seat b (61), the spline sleeve (45) is assembled with the lead screw d (46) and the lead screw c (54); the adjustment knob c (60) and the lead screw c (54) The ends are connected, the positioning block (58) is assembled with the guide rail (59) and the lead screw c (54), and the two adjustment knobs a (51) are respectively connected with the two positioning blocks (58). 8. The device for testing the fatigue mechanical properties of materials under tensile-bending composite loads according to claim 1, characterized in that: the ultrasonic flaw detection module (6) is arranged on the vibration isolation base (1), and during the test The ultrasonic probe of the handheld ultrasonic flaw detection module (6) scans the surface of the UHF bending fatigue sample (33) to realize in-situ monitoring of fatigue cracks on the surface of the UHF bending fatigue sample (33) during the test.