Tension-bending composite ultrasonic fatigue test device and use method thereof

Abstract

The invention discloses a tension-bending composite ultrasonic fatigue test device and a use method thereof, and belongs to the field of material testing. The device mainly comprises a rack, an ultrasonic rotating module and a reflection detection module, the ultrasonic rotating module and the reflection detection module are both installed in the rack, the ultrasonic rotating module is arranged over the reflection detection module, and a to-be-tested sample block is arranged at the bottom of the ultrasonic rotating module; a tensile load and a bending load are simultaneously provided for the sample block through the ultrasonic rotation module, then the amplitude of the sample block is obtained through the reflection detection module and the external laser vibration meter, various data of the sample block in the test process are obtained through finite element analysis, and more accurate and reliable test conditions are provided for a workpiece needing to bear a composite load.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of material testing, and particularly relates to a tension-bending combined ultrasonic fatigue test device and a method for using the same. BACKGROUND

[0002] An aero-engine is a core component of an airplane, and its performance directly determines the flight performance, reliability and safety of the airplane. A turbine blade is a core component of an aero-engine. Due to its extremely complex structure, the turbine blade needs to withstand harsh working conditions such as high temperature, high pressure, high rotation speed and alternating stress during service. Among various failures of the turbine blade, fatigue failure accounts for a large proportion, and in various cases of turbine blade fatigue failure, the turbine blade is mostly caused to fail due to combined loading of bending load and tensile load, and finally caused to fail due to combined fatigue of the turbine blade.

[0003] Existing tensile fatigue tests and bending fatigue tests cannot be performed simultaneously. A conventional fatigue testing machine can only perform tensile load or bending load tests, and cannot simulate tensile stress generated due to high-speed rotation and bending force generated due to airflow impact of an airplane engine turbine blade in actual working conditions. Moreover, the stress detection equipment of the conventional fatigue testing machine can only detect stress generated due to single load, and cannot intuitively monitor the stress of a sample during a combined load fatigue test.

[0004] For example, a Chinese patent with application number CN2019101833123 discloses a material fatigue mechanical property testing device under tensile-bending combined load. The device can perform tensile-bending combined load fatigue tests, but the combined load is still a “quasi-static” scenario of static tensile plus bending, and is only suitable for general fatigue tests. Due to the three-point bending design, the load introduction point or the support point is easily damaged due to friction, especially at high frequencies (0-100 Hz) or ultrahigh frequencies (20 kHz). This bending mode easily causes uneven stress distribution and uncertain maximum stress point position, and affects the reliability of fatigue life evaluation. Therefore, the scheme cannot be dynamically loaded in the true sense of two combined loads, cannot accurately simulate dynamic centrifugal tension and high-frequency bending combined with the actual working conditions of the turbine blade, and lacks reliability in fatigue life evaluation at high frequencies.

[0005] Therefore, a new design is needed, which can add tensile load and bending load to a sample simultaneously and can detect the stress of the sample. SUMMARY

[0006] In view of the above problems existing in the prior art, the present application aims to provide a tension-bending combined ultrasonic fatigue test device and a use method thereof.

[0007] In order to solve the above problems, the technical scheme adopted by the present application is as follows: A tension-bending combined ultrasonic fatigue test device, comprising a rack, an ultrasonic rotating module and a reflection detection module, wherein the ultrasonic rotating module and the reflection detection module are both mounted on the rack, the ultrasonic rotating module is arranged directly above the reflection detection module, a laser vibration meter is arranged on the side surface of the reflection detection module, and the reflection detection module can adjust the direction of the laser beam emitted by the laser vibration meter. The ultrasonic rotating module comprises a servo motor, a transducer shell, a transducer and an amplitude transformer, the output end of the servo motor is connected with the upper shell cover plate of the transducer shell through a shaft coupling, an electrically conductive slip ring rotor is arranged outside the shaft coupling, an electrically conductive slip ring stator is rotatably connected to the outside of the electrically conductive slip ring rotor, a power supply wire is connected to the outside of the electrically conductive slip ring stator, an electrically conductive wire is connected to the electrically conductive slip ring rotor, the transducer and the amplitude transformer are fixedly connected inside the transducer shell, the amplitude transformer is fixedly connected below the transducer, the electrically conductive wire is connected with the transducer, and a sample block is fixedly connected to the bottom of the amplitude transformer.

[0008] Further, a flange is arranged at the position of the bottom of the transducer shell, a flange fixing ring is arranged above the flange on the inside of the transducer shell, a shell lower cover plate is fixedly connected to the bottom of the transducer shell, the shell lower cover plate is of an annular structure, the flange of the amplitude transformer is arranged between the flange fixing ring and the shell lower cover plate, and flange washers are arranged above and below the flange.

[0009] Further, a protective frame is arranged outside the ultrasonic rotating module, a through hole for accommodating the shell upper cover plate is formed in the top surface of the protective frame, a bearing is arranged inside the through hole, the inner ring of the bearing is fixedly connected with the shell upper cover plate, and the outer ring of the bearing is fixedly connected with the protective frame; a through hole for accommodating the shell lower cover plate is formed in the bottom of the protective frame, a bearing is arranged inside the through hole, the inner ring of the bearing arranged at the bottom of the protective frame is fixedly connected with the shell lower cover plate, and the outer ring is fixedly connected with the protective frame.

[0010] Further, the reflection detection module comprises a reflecting mirror, an angle adjustment platform, a multi-axis adjustment platform and a vibration isolation base, the reflecting mirror is arranged above the angle adjustment platform, the angle adjustment platform is arranged above the multi-axis adjustment platform, and the vibration isolation base is arranged below the multi-axis adjustment platform.

[0011] Further, the rack is a gantry structure, and the rack comprises two columns and three layers of partitions, the three layers of partitions are arranged between the two columns, the lowermost layer of partitions is at a distance from the ground, the ultrasonic rotating module is arranged on the middle layer of partitions, and the reflection detection module is arranged on the lower layer of partitions.

[0012] Further, the sample block is a symmetrical cantilever structure extending to left and right sides with the connecting point of the amplitude rod as the center, the cantilever gradually tapers in the direction from the mounting point to the end of the cantilever, and the end of the cantilever is thickened, and a high stress zone is arranged between the thickened part of the end of the cantilever and the mounting point of the amplitude rod, the width and thickness of the whole high stress zone are equal.

[0013] Further, the sample block is a symmetrical cantilever structure extending to left and right sides with the connecting point of the amplitude rod as the center, the cantilever gradually tapers in the direction from the mounting point to the end of the cantilever, and the end of the cantilever is thickened, and a high stress zone is arranged between the thickened part of the end of the cantilever and the mounting point of the amplitude rod, the width and thickness of the whole high stress zone are equal.

[0014] Further, the rotation frequency of the servo motor and the vibration frequency of the transducer cannot be mutually divided.

[0015] A use method of a tension-bending combined ultrasonic fatigue test device, the use method comprises the following steps: Step one, fixing the sample block at the bottom of the amplitude rod; Step two, turning on the laser vibration meter, adjusting the positions of the components of the reflection detection module, and positioning the laser beam of the laser vibration meter to the two preset positioning measuring points; Step three, starting the servo motor and the transducer to simultaneously apply the tensile load and the bending load to the sample block; Step four, acquiring the data of the laser vibration meter, analyzing the high stress zone of the sample block by using the finite element analysis, and acquiring the maximum stress borne by the high stress zone; Step five, calibrating the relationship between the voltage of the transducer and the stress borne by the sample block based on the maximum stress data obtained by the sample block; Step six, performing batch tests according to the stress-voltage relationship table, and recording the fracture cycles of the sample block under different stress levels; Step seven, drawing a curve graph of the stress-fracture cycle relationship of the sample block according to the test results.

[0016] Further, in step four, the method for acquiring the maximum stress is as follows: Viewing the data collected by the laser vibration meter, determining the displacement amplitude H0 of the sample block close to the connecting point of the amplitude rod, and determining the displacement amplitude H1 of the high stress zone of the sample block; Through finite element analysis, the sample block is subjected to harmonic response analysis, H0 measured is input as displacement amplitude, damping ratio zeta0 is input, solving is carried out, then the displacement amplitude H2 of the high stress area of the sample block simulated in the finite element analysis is viewed through the displacement nephogram, the damping ratio zeta0 is gradually adjusted until H2=H1, and the damping ratio at this time is recorded as zeta1; Based on the damping ratio zeta1, harmonic response analysis is carried out again, the maximum stress at the maximum deflection of the sample block simulated is viewed through the stress nephogram, and the maximum stress is the maximum stress of the sample block in the test process.

[0017] Compared with the prior art, the beneficial effects of the present application are: The test device of the present application adopts a modular design idea, is composed of a rack, an ultrasonic rotating module and a reflection detection module, is highly modular, and is convenient for maintenance and function expansion.

[0018] Compared with the prior art, the present application realizes the internal and synchronous coupling loading of ultrahigh frequency bending load and rotating centrifugal tensile load through the ultrasonic rotating module, forms a highly integrated dynamic composite loading mechanism, realizes the truly synchronous high frequency bending load and dynamic centrifugal tensile simulation environment, and effectively solves the problems of complex structure, low efficiency, large simulation effect and actual gap of the traditional composite loading device. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the test device; Figure 2 It is a schematic diagram of the structure of the ultrasonic rotating module; Figure 3 It is a schematic diagram of the partial cross-sectional structure of the ultrasonic rotating module; Figure 4 It is Figure 3 It is an enlarged view of A in the middle; Figure 5 It is Figure 3 It is an enlarged view of B in the middle; Figure 6 It is a schematic diagram of the cross-sectional structure of the transducer and the amplitude bar; Figure 7 It is a schematic diagram of the structure of the reflection detection module; Figure 8 It is a three-view diagram of the shape of the sample block; Figure 9 It is a schematic diagram of the state of the sample block when vibrating; Figure 10 It is a schematic diagram of the position of the positioning measuring point; Figure 11 It is a simulation diagram of the intersection of the motor frequency and the ultrasonic vibration frequency; Figure 12A schematic diagram illustrating the acquisition of displacement amplitude using a laser vibrometer; Figure 13 This is a flowchart of the method for conducting experiments using this device; Figure 14 This is a state diagram of the sample block simulated by finite element analysis; In the diagram: 101, column; 102, partition; 103, base; 201. Servo motor; 202. Coupling; 2021. Conductive slip ring rotor; 2022. Conductive slip ring stator; 2023. Power supply line; 2024. Conductive wire; 203. Transducer; 2031. Upper cover plate of housing; 2032. Transducer housing; 2033. Flange retaining ring; 2034. Lower cover plate of housing; 2035. Flange washer; 2036. Bearing; 204. Amplitude bar; 205. Protective frame; 301. Reflector; 302. Angle adjustment platform; 303. Multi-axis adjustment platform; 304. Vibration isolation base; 401. Sample block. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments.

[0021] like Figure 1 As shown, this scheme mainly includes a frame, an ultrasonic rotation module, and a reflection detection module. Both the ultrasonic rotation module and the reflection detection module are mounted on the frame. The ultrasonic rotation module is positioned directly above the reflection detection module, and the sample block 401 is positioned at the bottom of the ultrasonic rotation module.

[0022] The frame is a gantry structure consisting of two uprights 101 and three partitions 102. The three partitions 102 are located between the two uprights 101. The bottom partition 102 is not completely aligned with the ground. The ultrasonic rotation module is located on the middle partition 102, and the reflection detection module is located on the bottom partition 102. Each of the two uprights 101 has a vibration damping base 103 at its bottom, which can also enhance the stability of the frame during the test.

[0023] like Figures 2-5As shown, the ultrasonic rotating module includes a servo motor 201, a coupling 202, a transducer 203 and an amplitude transformer 204. The servo motor 201 is arranged above the middle layer partition 102 of the rack, and the output shaft of the servo motor 201 is arranged downward and penetrates the inside of the partition 102. The output shaft of the servo motor 201 is fixedly connected with the coupling 202. A conductive slip ring rotor 2021 is arranged on the outside of the coupling 202. The conductive slip ring rotor 2021 is in interference fit with the coupling 202. A conductive slip ring stator 2022 is rotatably connected on the outside of the conductive slip ring rotor 2021. The conductive slip ring stator 2022 is fixedly arranged in the inside of the middle layer partition 102. The conductive slip ring stator 2022 is connected with a power supply wire 2023 which penetrates the partition 102. The power supply wire 2023 is used to supply power to the conductive slip ring stator 2022 and the conductive slip ring rotor 2021. A conductive wire 2024 is arranged on the bottom of the conductive slip ring rotor 2021. The conductive wire 2024 is used to supply power to the transducer 203.

[0024] The bottom of the coupling 202 is fixedly connected with a shell upper cover plate 2031. The shell upper cover plate 2031 extends from the inside of the middle layer partition 102 to the lower side of the middle layer partition 102. In this embodiment, the coupling 202 is rigidly connected with the shell upper cover plate 2031 by bolts. The shell upper cover plate 2031 is provided with a through hole. The conductive wire 2024 can extend to the lower side of the shell upper cover plate 2031 through the through hole. The bottom of the shell upper cover plate 2031 is fixedly connected with a transducer shell 2032. The transducer shell 2032 is rigidly connected with the shell upper cover plate 2031 by bolts. The transducer shell 2032 is a hollow cylindrical structure. The transducer 203 is arranged in the inside of the transducer shell 2032. The transducer 203 is connected with the other end of the conductive wire 2024.

[0025] The conductive slip ring is supplied with power through the power supply wire 2023, and the transducer 203 is supplied with power through the conductive wire 2024. Thus, the transducer 203 can be supplied with power by the external power supply wire 2023 while the servo motor 201 drives the shell upper cover plate 2031, the transducer shell 2032 and the transducer 203 arranged in the inside of the transducer shell 2032 to rotate through the coupling 202.

[0026] The bottom of the transducer 203 is fixedly connected with the amplitude transformer 204. The amplitude transformer 204 is rigidly connected with the transducer 203 by bolts. The amplitude transformer 204 can be removed for maintenance and replacement under the premise of ensuring its stability.

[0027] As shown in FIG. 4, the bottom of the amplitude transformer 204 is provided with a sample block 401. The sample block 401 is also fixedly arranged on the amplitude transformer 204 by bolts. The detachable structure facilitates replacement of different sample blocks 401.Figure 5 and Figure 6 As shown, the amplitude rod 204 has a flange at the bottom of the transducer housing 2032. A flange retaining ring 2033 is located on the inner side of the transducer housing 2032 above the flange. The bottom of the transducer housing 2032 is rigidly connected to a lower cover plate 2034 by bolts. The lower cover plate 2034 has a ring structure, allowing the lower half of the amplitude rod 204 to pass through it. However, the flange of the amplitude rod 204 is blocked by the lower cover plate 2034. Through the cooperation of the lower cover plate 2034 and the flange retaining ring 2033, the flange structure of the amplitude rod 204 is clamped between the lower cover plate 2034 and the flange retaining ring 2033. Flange washers 2035 are provided above and below the flange. (See reference...) Figure 5 The cross-sectional view shown indicates that the flange washer 2035 located below the flange structure has its upper and lower sides in contact with the flange and the lower cover plate 2034 of the outer casing, respectively. The left and right sides of the flange washer 2035 are in contact with the amplitude rod 204 and the lower cover plate 2034 of the outer casing, respectively. The flange washer 2035 located above the flange structure has its upper and lower sides in contact with the flange retaining ring 2033 and the flange, respectively. The left and right sides of the flange washer 2035 are in contact with the amplitude rod 204 and the lower cover plate 2034 of the outer casing, respectively. The two flange washers 2035 can fit tightly against the amplitude rod 204, clamping the amplitude rod 204 between the flange retaining ring 2033 and the lower cover plate 2034 of the outer casing in the vertical direction, and fixing the amplitude rod 204 inside the transducer housing 2032 in the horizontal direction. When the servo motor 201 drives the transducer housing 2032 to rotate, the amplitude rod 204, which is fixed to the bottom of the transducer housing 2032, will also rotate along with it. When the transducer 203 is started, the transducer 203 will drive the amplitude rod 204 to vibrate in the vertical direction. The flange washer 2035 can effectively reduce the vibration between the amplitude rod 204 and the transducer housing 2032, so that the vibration will not affect the transducer housing 2032 from driving the amplitude rod 204 to rotate.

[0028] like Figure 2As shown, a protective frame 205 is arranged outside the ultrasonic rotating module, the protective frame 205 is fixedly arranged below the middle layer partition plate 102 of the rack, the top of the protective frame 205 is fixedly connected with the lower surface of the middle layer partition plate 102 of the rack, a through hole for accommodating the upper cover plate 2031 of the shell is formed in the top surface of the protective frame 205, a bearing 2036 is arranged in the through hole, the inner ring of the bearing 2036 is in interference fit with the upper cover plate 2031 of the shell, and the outer ring of the bearing 2036 is in interference fit with the protective frame 205. In order to adapt to the interference fit of the inner and outer rings of the bearing 2036, in this embodiment, the bearing 2036 is a cylindrical bearing, which can better adapt to the interference fit assembly structure. A through hole is formed in the bottom surface of the protective frame 205 for the lower cover plate 2034 of the shell to pass through, the through hole is used for rotationally connecting with the lower cover plate 2034 of the shell, and a bearing 2036 is arranged in the through hole. The inner ring of the bearing 2036 arranged at the bottom of the protective frame 205 is in interference fit with the lower cover plate 2034 of the shell, and the outer ring is in interference fit with the through hole at the bottom of the protective frame 205.

[0029] The protective frame 205 is mainly used for protecting the rotating ultrasonic module in the working process. The transducer shell 2032 will be driven to rotate by the servo motor 201 during work, and the protective frame 205 can prevent the transducer shell 2032 from being accidentally touched and causing rotation to be affected, thereby causing the set effect to be unable to be achieved. The protective frame 205 is rotationally connected with the upper cover plate 2031 and the lower cover plate 2034 of the shell through the bearing 2036, which does not affect the rotation effect and can also prevent the transducer shell 2032 from being inclined in the axial direction during rotation, so that the operation is more stable.

[0030] As shown in FIG. 4, Figure 8 As shown in FIG. 4, Figure 8 (a) is an isometric view of the sample block 401, (b) is a front view of the sample block 401, and (c) is a top view of the sample block 401. The shape of the sample block 401 is designed to better cooperate with the test style of the present scheme. In order to avoid potential damping caused by irrelevant contact between the two ends of the sample block 401 and the amplitude rod 204 due to excessive deformation amplitude, and to avoid large stress concentration at the mounting point of the sample block 401 and the amplitude rod 204, the sample block 401 is designed as a structure with a mounting point at the bottom of the amplitude rod 204 as the center, symmetrically extending out cantilever arms to the left and right sides. The cantilever arms gradually taper from the mounting point to the end of the cantilever arm, and are thickened at the end of the cantilever arm. A high stress zone is provided between the thickened part at the end of the cantilever arm and the mounting point of the amplitude rod 204. The width and thickness of the entire high stress zone are equal. The high stress zone can be regarded as a long rectangular parallelepiped parallel to the ground, and each face is a plane.

[0031] As shown in FIG. 4, Figure 9 As shown in FIG. 4, Figure 9The dashed line structure in the normal state of the sample block 401, and the solid line structure is the attitude when the vibration bending occurs. The structure of the sample block 401 can make the high stress area of the sample block 401 (i.e. the bending fatigue area during the test) located on the horizontal plane, which facilitates polishing and pasting strain gauges, and is more convenient for measuring the amplitude in the vertical direction of the fatigue area during testing, thereby calculating the stress borne by the sample block 401, and the thickness of the high stress area of the sample block 401 is equal, the width is also equal, and the width of the high stress area is less than the width of the sample block 401 installed at the bottom of the amplitude lever 204. The structure can effectively reduce the measurement error of the high stress area when passing through the laser measuring point during rotation.

[0032] As shown in Figure 7 The reflection detection module is arranged on the lower partition plate 102 of the rack, and mainly includes a mirror 301, an angle adjusting platform 302, a multi-axis adjusting platform 303, and a vibration isolation base 304. The mirror 301 is arranged above the angle adjusting platform 302. The structure of the angle adjusting platform 302 in the embodiment is a common adjusting table structure, which includes a movable upper panel and a base panel for installation. One side of the upper panel is hinged to the base panel. The side of the upper panel that is not hinged to the base panel is provided with an adjusting structure that can lift the upper panel. The height of the part of the upper panel in contact with the base panel can be adjusted by the adjusting structure, so that the upper panel can rotate around the hinge point with the base panel, thereby achieving the function of adjusting the angle. There are many types of structures of the angle adjusting platform 302. In the embodiment, only a common structure is shown, but other structures of the angle adjusting platform 302 can also be used as long as they can adjust the angle of the mirror 301, which should fall within the scope of protection.

[0033] The multi-axis adjusting platform 303 is arranged below the angle adjusting platform 302, and the vibration isolation base 304 is arranged below the multi-axis adjusting platform 303. The multi-axis adjusting platform 303 is also a common structure. In the embodiment, the structure of the multi-axis adjusting platform 303 is a double-layer lead screw sliding table structure. Two lead screw sliding tables are arranged in layers. The upper lead screw sliding table is arranged above the sliding table of the lower lead screw sliding table. The angle adjusting platform 302 is arranged on the upper surface of the sliding table of the upper lead screw sliding table. The two lead screw sliding tables are arranged perpendicular to each other. One can slide in the left-right direction, and the other can slide in the front-back direction. The lead screws in different directions of the upper and lower layers can move and position the angle adjusting platform 302 in the plane direction.

[0034] The side of the reflection detection module is provided with an external detection component. The external detection component selected in the scheme is a laser vibration meter. The distance data between the laser vibration meter and the sample block 401 is collected through laser. Then the vibration amplitude of the sample block 401 is obtained through multiple different distance data. The laser vibration meter is arranged on the side of the reflection detection module and can be moved according to the specific position of the reflector 301. In actual testing, the reflector 301 is located directly below the sample block 401. The laser emitted by the laser vibration meter is reflected by the reflection detection module, and finally the laser beam is positioned at the positioning measurement point on the lower surface of the sample block 401. There are two positioning measurement points in total, as shown in Figure 10 The other positioning measurement point is located in the area close to the installation position of the sample block 401, that is, the area near the bottom of the sample block 401 installed on the amplitude lever 204.

[0035] The working process of the device is as follows: the specially shaped sample block 401 is bolted to the bottom of the amplitude lever 204, the laser beam of the laser vibration meter is aligned with the two positioning measurement points, and then the ultrasonic rotation module is started. The shell upper cover plate 2031, the transducer shell 2032 and the shell lower cover plate 2034 are driven to rotate by the servo motor 201. The amplitude lever 204 clamped in the transducer shell 2032 rotates together with the transducer 203. At the same time, the power supply wire 2023 supplies power to the transducer 203. The transducer 203 is started and provides vertical vibration for the amplitude lever 204 through ultrasonic waves. At this time, the rotation provides centripetal force as tensile load for the sample block 401, and the vibration provides bending load for the sample block 401, so as to realize the simultaneous application of tensile load and bending load to the sample block 401, and facilitate the tensile-bending composite ultrasonic fatigue test of the sample block 401.

[0036] As shown in Figure 11 and Figure 12 , the ultrasonic vibration frequency and the rotation frequency of the servo motor 201 are sinusoidal changes. The intersection of the two is the data point collected by the laser vibration meter. The positioning measurement point of the laser remains unchanged. The sample block 401 rotates one revolution, and the laser vibration meter can collect data twice. Therefore, the frequency collected by the laser vibration meter is intermittent. In order to avoid the collected data from not changing, it is possible that the maximum stress point cannot be selected through the intersection. The rotation frequency of the servo motor 201 and the rotation frequency of the ultrasonic vibration need to be relatively prime, so that the data at different amplitude positions of the ultrasonic vibration frequency can be detected, and the maximum deflection value of the high stress area of the sample block 401 during ultrasonic vibration can be accurately detected.

[0037] The use method of the device for testing is as follows: Step one, fix the sample block 401 on the bottom of the amplitude lever 204 by bolts; Step two, turn on the laser vibration meter, adjust the position of each part of the reflection detection module, and position the laser beam of the laser vibration meter to two preset positioning points; Step three, start the servo motor 201 and the transducer 203 to apply tensile load and bending load to the test block 401 simultaneously; Step four, obtain the data of the laser vibration meter, and analyze the high stress area of the test block 401 using finite element analysis to obtain the maximum stress borne by the high stress area.

[0038] Step five, based on the maximum stress data obtained from the test block 401, calibrate the relationship between the voltage of the transducer 203 and the stress borne by the test block 401; Step six, according to the stress-voltage relationship table, perform batch testing and record the fracture period of the test block 401 under different stress levels; Step seven, according to the test results, draw a curve graph of the stress-fracture period relationship of the test block 401.

[0039] In step four, the specific method for obtaining the maximum stress is as follows: View the data collected by the laser vibration meter, i.e. the amplitude data of the positions corresponding to the two laser measuring points, to determine the displacement amplitude H0 of the test block 401 near the connection of the amplitude-changing rod 204, and determine the displacement amplitude H1 of the high stress area of the test block 401.

[0040] As shown in Figure 13 , first perform finite element analysis, then determine the actual rotation frequency and vibration frequency of the test block 401 for testing, and finally perform harmonic response analysis on the test block 401, input the measured H0 as the displacement amplitude, input the damping ratio ζ0, and solve, then view the displacement amplitude H2 of the high stress area of the test block 401 simulated in the harmonic response analysis through the displacement cloud map, gradually adjust the damping ratio ζ0 until H2= H1, and record the damping ratio at this time as ζ1.

[0041] Then, based on the damping ratio ζ1, perform harmonic response analysis again, i.e. Figure 14 The test block 401 model shown in the simulation diagram is the posture during harmonic response analysis, the line frame in the diagram is the posture of the undeformed test block 401, and the high stress area is the place bearing the maximum stress. View the maximum stress at the maximum deflection of the test block 401 simulated through the stress cloud map, which is the maximum stress borne by the test block 401 during the test.

[0042] In the use of steps one to four, mainly to a kind of material sample block 401 is tested to establish standard, in subsequent step five, the maximum stress data obtained by sample block 401, combined with displacement distance and the voltage of transducer 203 generates vibration, the relationship between the voltage of transducer 203 and the stress suffered by sample block 401 is deduced reversely, and then the relationship table between different stress suffered by sample block 401 and corresponding voltage is established, so as to facilitate subsequent batch experiments.

[0043] Step six is to carry out batch test according to the stress-voltage relationship table obtained in step five, and record the fracture period of sample block 401 under different stress.

[0044] Finally in step seven, according to the test results, the stress-fracture period relationship curve of sample block 401 is drawn, and the strength data of the material under composite load is obtained.

[0045] The present application realizes the synchronous dynamic application of rotating centrifugal tensile load and ultrahigh frequency bending load through the internal coupling design of the ultrasonic rotating module, which accurately simulates the real service environment of key components such as turbine blades of aero-engine under high-speed rotating working condition: centrifugal force increases linearly with radius, providing non-uniform dynamic tensile stress field (F = mω2r), superimposed with bending fatigue induced by 20 kHz ultrasonic vibration, fully reproducing the composite failure mode under high temperature, high pressure and high speed alternating stress (turbine blade fatigue problem as described in the background art).

[0046] In contrast, the static mechanical tensile and modular bending used in the prior art can only simulate quasi-static composite scenarios, and cannot capture the transient gradient distribution of rotating centrifugal effect and the nonlinear interaction of vibration-rotation coupling, resulting in deviation of test results from the dynamic fatigue evolution path of actual working condition, thereby existing significant deviation in service performance prediction. The integrated dynamic loading of the present application not only improves the physiological relevance of the test, but also provides more reliable engineering guidance for material optimization.

Claims

1. A tension-bending composite ultrasonic fatigue testing device, characterized in that, The ultrasonic rotating module and the reflection detection module are both installed on the rack, the ultrasonic rotating module is arranged above the reflection detection module, a laser vibration detector is arranged on the side of the reflection detection module, and the reflection detection module can adjust the direction of the laser beam emitted by the laser vibration detector. The ultrasonic rotating module comprises a servo motor, a transducer shell, a transducer and an amplitude transformer, the output end of the servo motor is connected with the upper shell cover plate of the transducer shell through a shaft coupling, a conductive slip ring rotor is arranged outside the shaft coupling, a conductive slip ring stator is rotatably connected to the outside of the conductive slip ring rotor, a power supply wire is connected to the outside of the conductive slip ring stator, a conductive wire is connected to the conductive slip ring rotor, the transducer and the amplitude transformer are fixedly connected inside the transducer shell, the amplitude transformer is fixedly connected below the transducer, the conductive wire is connected with the transducer, and a sample block is fixedly connected to the bottom of the amplitude transformer.

2. The tension-bending combined ultrasonic fatigue testing apparatus according to claim 1, wherein The amplitude transformer is provided with a flange at the position of the bottom of the transducer shell, the inside of the transducer shell is provided with a flange fixing ring above the flange, the bottom of the transducer shell is fixedly connected with a shell lower cover plate, the shell lower cover plate is of an annular structure, the flange of the amplitude transformer is arranged between the flange fixing ring and the shell lower cover plate, and flange gaskets are arranged above and below the flange.

3. The tension-bending combined ultrasonic fatigue testing apparatus according to claim 1, wherein The outside of the ultrasonic rotating module is provided with a protective frame, a through hole for accommodating the shell upper cover plate is formed in the top surface of the protective frame, a bearing is arranged inside the through hole, the inner ring of the bearing is fixedly connected with the shell upper cover plate, and the outer ring of the bearing is fixedly connected with the protective frame; a through hole for accommodating the shell lower cover plate is formed in the bottom of the protective frame, a bearing is arranged inside the through hole, the inner ring of the bearing arranged in the bottom of the protective frame is fixedly connected with the shell lower cover plate, and the outer ring is fixedly connected with the protective frame.

4. The tension-bending combined ultrasonic fatigue testing apparatus according to claim 1, wherein The reflection detection module comprises a mirror, an angle adjustment platform, a multi-axis adjustment platform and a vibration isolation base, the mirror is arranged above the angle adjustment platform, the angle adjustment platform is arranged above the multi-axis adjustment platform, and the vibration isolation base is arranged below the multi-axis adjustment platform.

5. The tension-bending combined ultrasonic fatigue testing apparatus according to claim 1, wherein The rack is of a gantry structure, the rack comprises two columns and three layers of partitions, the three layers of partitions are arranged between the two columns, the lowermost partition is at a distance from the ground, the ultrasonic rotating module is arranged on the middle layer of partitions, the reflection detection module is arranged on the lower layer of partitions, and a base for damping is arranged at the bottom of the column.

6. The tension-bending combined ultrasonic fatigue testing apparatus according to claim 1, wherein The sample block is of a symmetrical cantilever structure extending to the left and right sides with the connection point of the amplitude transformer as the center, the cantilever gradually tapers from the mounting point to the end of the cantilever, is thickened at the end of the cantilever, and a high stress zone is arranged between the thickened part at the end of the cantilever and the amplitude transformer mounting point, the width and thickness of the whole high stress zone are equal.

7. The tension-bending combined ultrasonic fatigue testing apparatus according to claim 6, wherein The sample block is provided with two positioning measuring points for laser sampling, one is arranged in the high stress zone of the sample block, and the other is arranged at the bottom of the connection between the sample block and the amplitude transformer.

8. The tension-bending combined ultrasonic fatigue testing apparatus according to claim 1, wherein The rotation frequency of the servo motor and the vibration frequency of the transducer cannot be divided by each other.

9. A method of using a tension-bending combined ultrasonic fatigue testing apparatus according to any one of claims 1 to 8, characterized by, The use method comprises the following steps: Step one, fixing the sample block at the bottom of the amplitude transformer; Step two, open the laser vibrometer, adjust the position of each part of the reflection detection module, and position the laser beam of the laser vibrometer to two preset positioning points; Step three, start the servo motor and transducer, and apply tensile load and bending load to the sample block at the same time; Step four, obtain the data of the laser vibrometer, analyze the high stress area of the sample block by using finite element analysis, and obtain the maximum stress borne by the high stress area; Step five, based on the maximum stress data obtained from the sample block, calibrate the relationship between the voltage of the transducer and the stress borne by the sample block; Step six, according to the stress-voltage relationship table, carry out batch testing, and record the fracture period of the sample block under different stress levels; Step seven, according to the test results, draw a curve graph of the stress-fracture period relationship of the sample block.

10. The method of using a tension-bending combined ultrasonic fatigue testing apparatus according to claim 9, wherein In step four, the method for obtaining the maximum stress is as follows: View the data collected by the laser vibrometer, determine the displacement amplitude H0 of the sample block near the connecting part of the amplitude changer, and determine the displacement amplitude H1 of the high stress area of the sample block; Through finite element analysis, the sample block is subjected to harmonic response analysis, the measured H0 is input as the displacement amplitude, the damping ratio ζ0 is input, and then the displacement amplitude H2 of the high stress area of the sample block simulated in the finite element analysis is viewed through the displacement cloud map, the damping ratio ζ0 is adjusted gradually until H2= H1, and the damping ratio at this time is recorded as ζ1; Based on the damping ratio ζ1, harmonic response analysis is carried out again, the maximum stress at the maximum deflection of the sample block simulated is viewed through the stress cloud map, and the stress is the maximum stress borne by the sample block in the test process.

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