In-situ ultrasonic detection method and apparatus for interface stiffness of aircraft-engine rotor with reference to microwave transmission line theory

Abstract

The present invention relates to the technical field of interface stiffness detection, and disclosed are an in-situ ultrasonic detection method and apparatus for the interface stiffness of an aircraft-engine rotor with reference to microwave transmission line theory. The in-situ ultrasonic detection apparatus for the interface stiffness of an aircraft-engine rotor is based on an apparatus base body, and uses an intermediate connecting structure to form an upper-lower structural distribution. Two probes each perform extension and retraction movements by using a servo turntable as a reference. The detection apparatus is positioned and affixed by means of a clamping mechanism, clamping displacement of the probes is achieved by means of an electromagnet and a suction cylinder, and the clamping force of the probes is provided by means of compression springs. The in-situ ultrasonic detection apparatus for the interface stiffness of an aircraft-engine rotor of the present invention can utilize microwave transmission line theory to reduce the random effects of sensing boundaries, and can carry out interface stiffness detection within the narrow space of an aircraft engine; springs are used to provide pressure to achieve better repeatability; and a connecting cylinder is used to enable synchronous rotation of the upper and lower structures, thereby improving the coaxiality of the upper and lower probes.

Description

An in-situ ultrasonic testing method and apparatus for the interface stiffness of aero-engine rotors, drawing on microwave transmission line theory. Technical Field

[0001] This invention belongs to the field of interface stiffness testing technology, and relates to an in-situ ultrasonic testing method and device for interface stiffness of aero-engine rotors based on microwave transmission line theory. Background Technology

[0002] The various components of an aero-engine are connected by bolts. Due to limitations in processing and assembly, the engine rotor system contains many connecting structures. Changes in the local contact state of these structures can cause additional imbalances in the rotor system, leading to vibration problems throughout the engine. Therefore, the detection of interface stiffness in the internal cavity of an aero-engine is of great significance.

[0003] Compared with other measurement methods, ultrasonic measurement technology has the advantages of being unrestricted by material properties, having strong in-situ measurement capabilities, and high sensitivity to interface measurements, thus meeting the basic requirements for in-situ measurement of aero-engine rotors. Of particular importance is the robustness of the interface stiffness measurement method and its operability within the confined space of the aero-engine rotor.

[0004] Current interface stiffness detection methods have the following problems:

[0005] 1) In-situ testing is not possible. Li Rui's portable ring stiffness testing device and operating method require placing the pipe to be tested on a testing platform. For aero-engine rotors, due to testing process requirements, testing needs to be carried out at a specific workstation, increasing the difficulty of testing the interface stiffness of aero-engine rotors.

[0006] 2) Poor accessibility: Jiang Chunyu's ultrasonic testing-based non-destructive testing device for composite materials and related components uses an open testing device. For aero-engine rotors, the internal space of the compressor drum disk is small and the operating space is limited, making it difficult for existing open testing equipment to enter, and making it difficult to perform related interface stiffness testing on existing rotors.

[0007] 3) Poor robustness: Mu Xiaokai's interface stiffness detection device based on solid coupling does not consider the uncertainty of the sensing boundary parameters. For aero-engine rotors, the uncertainty of the sensing boundary parameters during the detection process can easily lead to a decrease in measurement performance, limiting the application of interface stiffness measurement.

[0008] Summary of the Invention

[0009] The purpose of this invention is to solve the problem of difficult interface stiffness testing in aero-engines, and to provide an in-situ ultrasonic testing method and device for aero-engine rotor interface stiffness based on microwave transmission line theory. This invention can reduce the randomness of sensing boundaries by utilizing microwave transmission line theory, enables interface stiffness testing in the confined space of an aero-engine, achieves good repeatability by using springs to provide pressure, and improves the coaxiality of the upper and lower probes by using a connecting cylinder to achieve synchronous rotation of the upper and lower structures.

[0010] The technical solution of this invention:

[0011] A method for in-situ ultrasonic testing of the interface stiffness of an aero-engine rotor, drawing on microwave transmission line theory, utilizes an in-situ ultrasonic testing device for the interface stiffness of an aero-engine rotor. A fixing claw 2 is clamped onto the inner annular surface of the aero-engine. The upper ultrasonic probe 28 and lower ultrasonic probe 36 are deployed, positioning them above and below the test point, respectively. The upper ultrasonic probe 28 and lower ultrasonic probe 36 are pressed tightly against the test position by the mutual attraction between the electromagnet 12 and the adsorption cylinder 16. Ultrasonic signals are emitted by the upper ultrasonic probe 28 and lower ultrasonic probe 36 to obtain the transmission coefficient B1 and the upper surface reflection coefficient C. 12 , Lower surface reflection coefficient C 43 Then, the interface stiffness of the test point is obtained through calculation;

[0012] The TRDI expression for the interface stiffness of the test point is:

[0013] In microwave transmission line measurements, S 11 Parameters and S 22 Parameters are often used to characterize reflection properties, S 21 The parameters are used to characterize the transmission properties, from which C can be obtained. ij Along with B1, the TRDI measurement index eliminates the influence of sensing boundaries, retaining only the transmission coefficient of the contact interface. Therefore, utilizing the similarity between ultrasonic propagation theory and microwave transmission line theory helps to reduce boundary effects and improve the robustness of interface stiffness measurement.

[0014] An in-situ ultrasonic testing device for the interface stiffness of an aero-engine rotor, drawing on microwave transmission line theory, includes a device base 1, fixed claws 2, positioning telescopic rods 3, fixed compression springs 4, upper turntable end cover 5, upper linear guide rail base 6, lower turntable end cover 7, lower linear guide rail base 8, upper rolling bearing 9, lower rolling bearing 10, hollow connecting cylinder 11, electromagnet 12, upper linear guide rail 13, upper linear slider 14, upper servo motor connecting plate 15, adsorption cylinder 16, adsorption cylinder seat 17, and lower linear... Linear guide rail 18, lower linear slider 19, lower servo motor connecting plate 20, upper servo motor adapter plate 21, upper servo motor 22, upper servo motor turntable 23, upper servo motor rotating plate 24, upper probe connecting rod fixing block 25, upper probe connecting rod 26, upper probe housing 27, upper ultrasonic probe 28, upper probe compression spring 29, lower servo motor 30, lower servo motor turntable 31, lower servo motor rotating plate 32, lower probe connecting rod fixing block 33, lower probe connecting rod 34, lower probe housing 35, lower ultrasonic probe 36, and lower probe compression spring 37;

[0015] The device base 1 and the hollow connecting cylinder 11 are concentric and are both hollow cylindrical structures. Three positioning telescopic rods 3 are evenly distributed inside the device base 1 and the hollow connecting cylinder 11. A fixing spring 4 is fitted on the positioning telescopic rod 3 located outside the hollow connecting cylinder 11. Under the action of the fixing spring 4, the positioning telescopic rod 3 positions and fixes the inner annular surface of the aero-engine. The upper and lower ends of the device base 1 are connected to the upper turntable end cover 5 and the lower turntable end cover 7 respectively through the upper rolling bearing 9 and the lower rolling bearing 10. The upper turntable end cover 5 and the lower turntable end cover 7 are connected through the hollow connecting cylinder 11 to achieve synchronous rotation and clamp the device base 1. The upper turntable end cover 5 is connected to the upper linear guide rail base 6. The upper linear guide base 6 is connected to the upper linear guide 13, the lower turntable end cover 7 is connected to the lower linear guide base 8, and the lower linear guide base 8 is connected to the lower linear guide 18; the electromagnet 12 is connected to the upper servo motor connecting plate 15, the adsorption cylinder 16 is connected to the adsorption cylinder seat 17, and the adsorption cylinder seat 17 is connected to the lower servo motor connecting plate 20; the mutual adsorption between the electromagnet 12 and the adsorption cylinder 16 provides clamping displacement for the ultrasonic probe; the upper servo motor 22 is connected to the upper servo motor connecting plate 15 through the upper servo motor adapter plate 21, the upper servo motor turntable 24 is connected to the upper servo motor 22 through the upper servo motor turntable 23, and the upper probe connecting rod 26 is connected to the upper probe adapter through the upper probe connecting rod fixing block 25. The upper ultrasonic probe 28 is connected to the upper probe connecting rod 26 via the upper probe housing 27 and the upper probe compression spring 29. The lower servo motor 30 is connected to the lower servo motor connecting plate 20. The lower servo motor rotating plate 32 is connected to the lower servo motor 30 via the lower servo motor turntable 31. The lower probe connecting rod 34 is connected to the lower probe adapter plate 63 via the lower probe connecting rod fixing block 33. The lower ultrasonic probe 36 is connected to the lower probe connecting rod 34 via the lower probe compression spring 37 and the lower probe housing 35. The upper linear slider 14 is fixedly connected to the upper servo motor connecting plate 15. The movement of the upper linear slider 14 on the upper linear guide rail 13 drives the linear motion of the upper servo motor 22 and the upper ultrasonic probe 28. The lower linear slider... The lower linear slider 19 is fixedly connected to the lower servo motor connecting plate 20. The movement of the lower linear slider 19 on the lower linear guide rail 18 drives the lower servo motor 30 and the lower ultrasonic probe 36 to move linearly. The upper servo motor 22 is connected to the upper servo motor turntable 23 through a spline. The rotation of the output shaft of the upper servo motor 22 drives the rotation of the upper servo motor turntable 24 and the upper ultrasonic probe 28. The lower servo motor 30 is connected to the lower servo motor turntable 31 through a spline. The rotation of the output shaft of the lower servo motor 30 drives the rotation of the lower servo motor turntable 32 and the lower ultrasonic probe 36. The upper ultrasonic probe 28 and the lower ultrasonic probe 36 are pressed against the upper probe housing 27 and the lower probe housing 35 by the action of the upper probe compression spring 29 and the lower probe compression spring 37, respectively.

[0016] The mutual attraction between the electromagnet 12 and the adsorption cylinder 16 provides clamping displacement for the upper ultrasonic probe 28 and the lower ultrasonic probe 36; under the clamping displacement generated by the electromagnet 12 and the adsorption cylinder 16, the upper ultrasonic probe 28 and the lower ultrasonic probe 36 are clamped by the upper probe compression spring 29 and the lower probe compression spring 37.

[0017] In the non-detection phase, the electromagnet 12 is not energized and has no magnetism. The upper servo motor connecting plate 15 and the lower servo motor connecting plate 20 are separated from each other, and the upper ultrasonic probe 28 and the lower ultrasonic probe 36 are in a retracted state. At this time, the upper ultrasonic probe 28 and the lower ultrasonic probe 36 do not have clamping force. In the detection phase, the upper ultrasonic probe 28 and the lower ultrasonic probe 36 are unfolded to the position to be tested. The electromagnet 12 is energized and generates magnetism, attracting each other to the adsorption cylinder 16. The upper servo motor connecting plate 15 and the lower servo motor connecting plate 20 move closer to each other, and the upper ultrasonic probe 28 and the lower ultrasonic probe 36 also move closer accordingly. Under the action of the upper probe compression spring 29 and the lower probe compression spring 37, a clamping force is generated, and the interface stiffness detection work is carried out.

[0018] The upper servo motor plate 24 and the lower servo motor plate 32 are initially in a retracted state. After the fixed claw 2 is positioned and fixed by the positioning telescopic rod 3 and the fixed compression spring 4, the upper servo motor plate 24 and the lower servo motor plate 32 are unfolded, so that the ultrasonic probe can be moved to the area to be tested.

[0019] The positioning telescopic rod 3 has a boss structure. When it is retracted, it can be locked on the inner plane of the device base 1 to prevent it from popping out under the action of the fixing spring 4. When it is extended, it cooperates with the groove of the device base 1 to make the fixing claw 2 pop out in a specific posture and fix it on the inner annular surface of the engine.

[0020] The beneficial effects of the present invention are as follows: The present invention is characterized by its ability to perform interface stiffness testing in the confined space of an aero-engine, its ability to achieve good repeatability by using a spring rod to provide pressure, and its ability to achieve good stability by using the synchronous rotation of the upper and lower structures. Attached Figure Description

[0021] Figure 1 shows a schematic diagram of the similarities between ultrasonic and microwave transmission: (a) impedance mismatch in microwave transmission; (b) interfacial impedance discontinuity in ultrasonic propagation.

[0022] Figure 2 shows the transmission and reflection results of ultrasonic waves at a multi-layer contact interface.

[0023] Figure 3 shows the robustness comparison results between the proposed method and the traditional method: (a) statistical histogram of boundary parameters; (b) box plot of interface stiffness obtained by different methods;

[0024] Figure 4 is a schematic diagram of the overall structure of the detection device;

[0025] Figure 5 is a side view of the detection device, showing the overall state of the detection device when it is retracted;

[0026] Figure 6 is a schematic diagram showing the internal connection structure of the detection device.

[0027] In the diagram: 1. Device base; 2. Fixing claw; 3. Positioning telescopic rod; 4. Fixing compression spring; 5. Upper turntable end cover; 6. Upper linear guide base; 7. Lower turntable end cover; 8. Lower linear guide base; 9. Upper rolling bearing; 10. Lower rolling bearing; 11. Hollow connecting cylinder; 12. Electromagnet; 13. Upper linear guide; 14. Upper linear slider; 15. Upper servo motor connecting plate; 16. Adsorption cylinder; 17. Adsorption cylinder seat; 18. Lower linear guide; 19. Lower linear slider; 2 0 Lower servo connection plate; 21 Upper servo adapter plate; 22 Upper servo; 23 Upper servo turntable; 24 Upper servo turntable; 25 Upper probe connecting rod fixing block; 26 Upper probe connecting rod; 27 Upper probe housing; 28 Upper ultrasonic probe; 29 Upper probe compression spring; 30 Lower servo; 31 Lower servo turntable; 32 Lower servo turntable; 33 Lower probe connecting rod fixing block; 34 Lower probe connecting rod; 35 Lower probe housing; 36 Lower ultrasonic probe; 37 Lower probe compression spring. Detailed Implementation

[0028] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0029] Interface stiffness testing methods:

[0030] When ultrasound propagates at high frequencies in a solid, the theories of ultrasound propagation and microwave transmission lines share strong similarities in governing equations, boundary conditions, and reflection laws. The Maxwell equations for microwaves consist of four equations and four variables (electric field strength, magnetic field strength, charge density, and current density). Similarly, ultrasound in a solid also consists of four equations and four variables (strain, stress, displacement, and velocity). Furthermore, as shown in Figure 1, microwave transmission lines and ultrasound in solids exhibit similar propagation laws at discontinuous interfaces. The reflection coefficient R of the ultrasound depends on the acoustic impedance of both materials.

[0031] Z1 and Z2 represent the acoustic impedances on both sides of the interface.

[0032] Microwaves also exhibit reflection characteristics when propagating in transmission lines with different characteristic impedances, and the expression for their reflection coefficient Γ is the same as that for ultrasound.

[0033] Z L Z0 is the terminal load, and Z0 is the characteristic impedance. These transmission and reflection characteristics can be expressed using S-parameters from microwave transmission line theory. Therefore, microwave transmission line theory can be used to facilitate the establishment of interface stiffness measurement models that reduce boundary effects.

[0034] The transmission and reflection propagation of ultrasonic waves is shown in Figure 2. As shown, the top and bottom layers are piezoelectric wafers used to transmit and receive ultrasonic waves, while the remaining layers in the middle are metal bonding components. Ultrasonic waves are reflected and transmitted not only at the contact interface, but also at the sensing boundary between the piezoelectric wafers and the metal layers, exhibiting both reflection and transmission characteristics.

[0035] As shown in Figure 2, each time the ultrasonic wave passes through the interface, a portion of the transmitted wave energy is lost. The transmission coefficient B1 of the first transmitted wave can be expressed as:

[0036] Among them, t i γ is the transmission coefficient of the i-th interface, γ is the propagation constant, and D is the transmission coefficient of the i-th interface. i Let be the thickness of the i-th layer. Furthermore, the reflection coefficient C of the first reflected wave from the upper sensing boundary is... 12 It can be represented as:

[0037] Where r i r is the reflection coefficient of the i-th interface. inter It is the reflection coefficient of the contact interface, t i ′ is the backpropagation transmission coefficient of the i-th interface.

[0038] Similarly, the reflection coefficient C of the first reflected wave at the lower sensing boundary N(N-1) It can be represented as:

[0039] Although the transmission coefficient of the i-th interface may be unequal in different propagation directions, due to the reversibility of the propagation process, the product of the transmission coefficients of the 1st and Nth interfaces in different propagation directions is equal. t1×t N =t1′×t N ′ (6)

[0040] Since acoustic propagation loss is relatively small in a finite-thickness metallic solid medium, energy loss mainly originates from discontinuous interfaces, neglecting energy propagation loss in continuous solid media. Simultaneously assuming that the energy transfer characteristics of each contact interface are identical, by simultaneously solving equations (3), (4), (5), and (6), we can obtain...

[0041] The geometric mean of the reflection coefficients is usually used as the composite reflection coefficient.

[0042] For a two-layer connection structure (N=3), that is, a two-layer connection structure containing one contact interface and two sensing boundaries, equation (7) can be simplified to

[0043] Considering the influence of random errors in sensing boundary parameters and probe pose uncertainty, the robustness of a single ultrasonic measurement index is poor. Therefore, an interface stiffness measurement index (TRDI) that integrates transmission and reflection information is proposed. From equation (9), the expression for the interface stiffness measurement index TRDI corresponding to the double-layer connection structure can be obtained.

[0044] Similarly, for a three-layer connection structure (N=4), i.e., a three-layer connection structure containing two contact interfaces and two sensing boundaries, equation (7) can be further simplified to

[0045] Similarly, from equation (11), we can obtain the expression for the interface stiffness measurement index TRDI corresponding to the three-layer connection structure.

[0046] Furthermore, in microwave transmission line measurements, S 11 Parameters and S 22 Parameters are often used to characterize reflection properties, S 21 The parameters are used to characterize the transmission properties, from which C can be obtained. ij Along with B1, the TRDI measurement index eliminates the influence of sensing boundaries, retaining only the transmission coefficient of the contact interface. Therefore, utilizing the similarity between ultrasonic propagation theory and microwave transmission line theory helps to reduce boundary effects and improve the robustness of interface stiffness measurement.

[0047] As shown in Figure 3(a), the sensing boundary parameters exhibit a Gaussian distribution, with a maximum deviation rate of 36.4%. Figure 3(b) shows the box plots of interface stiffness obtained by different methods. It can be seen from the figures that when the deviation rate of the coupling layer parameters is 36.4%, the interface stiffness deviation rate obtained by the traditional method is 61.9%. This indicates that fluctuations in the sensing boundary parameters amplify the measurement error of the traditional method. Therefore, for the traditional method, to reduce the impact of uncertainties in the sensing boundary parameters, multiple data acquisitions and statistical analyses should be performed in RIAP to ensure the accuracy of the measurement results.

[0048] The results also show that, compared with traditional methods, the proposed method is less affected by uncertainties in sensing boundary parameters. This is because the proposed measurement index utilizes the intrinsic relationship between reflection and transmission information when calculating the transmission coefficient, thus reducing the impact of sensing boundary parameter uncertainties on the measurement results. Furthermore, in some practical measurement processes, RIAP is difficult to implement due to the special requirements of the measured object's spatial dimensions and operational processes. Therefore, compared with traditional methods, the proposed method achieves in-situ measurement of interface stiffness without the need for calibration reference data, making it more promising for practical applications.

[0049] An in-situ ultrasonic testing device for the interface stiffness of aero-engine rotors was designed by drawing on microwave transmission line theory.

[0050] As shown in Figures 4 to 6, this invention is based on the device base 1, and the entire device is constructed in the form of an upper and lower structure according to the requirements of ultrasonic transmission detection. The device base 1 is connected to the upper turntable end cover 5 and the lower turntable end cover 7 via upper rolling bearing 9 and lower rolling bearing 10, respectively. The upper linear guide rail 13, upper linear guide rail base 6, upper turntable end cover 5, hollow connecting cylinder 11, lower turntable end cover 7, lower linear guide rail base 8, and lower linear guide rail 18 are connected in sequence by bolts. The upper servo motor 22, upper servo motor adapter plate 21, upper servo motor connecting plate 15, and upper linear slider are connected in sequence by bolts; the lower servo motor 30, lower servo motor connecting plate 20, and lower linear slider 19 are connected in sequence by bolts. The upper servo motor 22 is connected to the upper servo motor turntable 23 via splines; the lower servo motor 30 is connected to the lower servo motor turntable 31 via splines. The upper probe housing 27, upper probe connecting rod 26, upper probe connecting rod fixing block 25, upper servo motor rotating plate 24, and upper servo motor rotating disk 23 are sequentially connected by bolts; the lower probe housing 35, lower probe connecting rod 34, lower probe connecting rod fixing block 33, lower servo motor rotating plate 32, and lower servo motor rotating disk 31 are sequentially connected by bolts. The upper ultrasonic probe 28 is fixed in the upper probe housing 27 under the action of the upper probe compression spring 29; the lower ultrasonic probe 36 is fixed in the lower probe housing 35 under the action of the lower probe compression spring 37.

[0051] The device base 1 and the hollow connecting cylinder 11 are hollow structures. The electromagnet 12 and the adsorption cylinder 16 are attracted to each other to provide clamping displacement for the ultrasonic probe. The upper probe compression spring 29 and the lower probe compression spring 37 provide clamping force for the ultrasonic probe.

[0052] The implementation steps of this invention are as follows:

[0053] 1) Initial stage: The three evenly distributed positioning telescopic rods 3 are retracted into the device base 1 and hollow connecting cylinder 11 under the restriction of the boss and the fixed compression spring 4. The upper servo motor plate 24 is in the vertically retracted state, and the lower servo motor plate 64 is in the side retracted state. At this time, the entire device is in the retracted state and enters the rotor cavity through the narrow inlet of the aircraft engine.

[0054] 2) Detection Preparation Stage: After reaching the designated position, rotate the three positioning telescopic rods 3 so that their upper bosses coincide with the grooves of the device base 1, and pop out under the action of the fixed compression spring 4. The fixed claws 2 at their ends clamp onto the inner annular surface of the aero-engine, and under the action of the same spring force, ensure the concentric positioning effect of the device base 1 and the inner annular surface of the aero-engine. After the positioning telescopic rods 3 and fixed claws 2 have completed their positioning and clamping functions, unfold the upper servo motor plate 24 and the lower servo motor plate 32, so that the upper ultrasonic probe 28 and the lower ultrasonic probe 36 are respectively positioned above and below the area to be tested.

[0055] 3) Testing Stage: Due to the extension of the positioning telescopic rod 3, the center position of the device base 1 and the hollow connecting cylinder 11 is in a hollow state. Under the mutual attraction of the electromagnet 12 and the adsorption cylinder 16, the upper servo connecting plate 15 and the lower servo connecting plate 20 approach each other and connect as a whole. The upper ultrasonic probe 28 and the lower ultrasonic probe 36 form a clamping force of 10N with the aero-engine structure under test, ensuring that the contact and stress state of the upper and lower interfaces are the same. After completing the interface stiffness test of a local position, the electromagnet 12 is de-energized and loses its magnetic force. The upper turntable end cover 5 is rotated by a specific angle to reach the next local position to be tested. The above steps are repeated to complete the full circle measurement.

[0056] 4) End of testing stage: Electromagnet 12 loses its magnetic force when de-energized, and separates from the adsorption cylinder 16 as the upper linear slider 14 and lower linear slider 19 separate. The upper servo plate 24 and lower servo plate retract under the action of the upper servo 22 and lower servo 30, and the three evenly distributed positioning telescopic rods 3 are pressed into the main body 11 of the device and the hollow connecting cylinder 11, converting them into a retracted state. The entire device is removed from the internal structure of the aircraft engine.

Claims

1. An in-situ ultrasonic testing device for aeroengine rotor interface stiffness based on microwave transmission line theory, characterized in that, The aero-engine rotor interface rigidity in-situ ultrasonic detection device comprises a device base body (1), a fixed clamping jaw (2), a positioning telescopic rod (3), a fixed compression spring (4), an upper rotary disc end cover (5), an upper linear guide rail base (6), a lower rotary disc end cover (7), a lower linear guide rail base (8), an upper rolling bearing (9), a lower rolling bearing (10), a hollow connecting cylinder (11), an electromagnet (12), an upper linear guide rail (13), an upper linear sliding block (14), an upper steering engine connecting plate (15), an adsorption cylinder (16), an adsorption cylinder seat (17), a lower linear guide rail (18), a lower linear sliding block (19), a lower steering engine connecting plate (20), an upper steering engine adapter plate (21), an upper steering engine (22), an upper steering engine rotary disc (23), an upper steering engine rotary plate (24), an upper probe connecting rod fixed block (25), an upper probe connecting rod (26), an upper probe shell (27), an upper ultrasonic probe (28), an upper probe compression spring (29), a lower steering engine (30), a lower steering engine rotary disc (31), a lower steering engine rotary plate (32), a lower probe connecting rod fixed block (33), a lower probe connecting rod (34), a lower probe shell (35), a lower ultrasonic probe (36) and a lower probe compression spring (37). The device base body (1) is concentric with the hollow connecting cylinder (11), and both are hollow cylindrical structures, three positioning telescopic rods (3) are evenly distributed in the device base body (1) and the hollow connecting cylinder (11), the positioning telescopic rod (3) outside the hollow connecting cylinder (11) is sleeved with a fixed compression spring (4), and the positioning telescopic rod (3) is positioned and fixed on the inner circular surface of the aero-engine under the action of the fixed compression spring (4); the upper and lower ends of the device base body (1) are connected with the upper rotary disc end cover (5) and the lower rotary disc end cover (7) through the upper rolling bearing (9) and the lower rolling bearing (10), the upper rotary disc end cover (5) and the lower rotary disc end cover (7) are connected through the hollow connecting cylinder (11) to realize synchronous rotation and clamp the device base body (1); the upper rotary disc end cover (5) is connected with the upper linear guide rail base (6), the upper linear guide rail base (6) is connected with the upper linear guide rail (13), the lower rotary disc end cover (7) is connected with the lower linear guide rail base (8), and the lower linear guide rail base (8) is connected with the lower linear guide rail (18); the electromagnet (12) is connected with the upper steering engine connecting plate (15), the adsorption cylinder (16) is connected with the adsorption cylinder seat (17), and the adsorption cylinder seat (17) is connected with the lower steering engine connecting plate (20); the mutual adsorption of the electromagnet (12) and the adsorption cylinder (16) provides clamping displacement for the ultrasonic probe; the upper steering engine (22) is connected with the upper steering engine adapter plate (21) (21) is connected with the upper rudder machine connecting plate (15), the upper rudder machine rotating plate (24) is connected with the upper rudder machine (22) through the upper rudder machine rotating disc (23), the upper probe connecting rod (26) is connected with the upper probe adapter plate 54 through the upper probe connecting rod fixing block (25), the upper ultrasonic probe (28) is connected with the upper probe connecting rod (26) through the upper probe shell (27) and the upper probe compression spring (29);The lower rudder machine (30) is connected with the lower rudder machine connecting plate (20), the lower rudder machine rotating plate (32) is connected with the lower rudder machine (30) through the lower rudder machine rotating disc (31), the lower probe connecting rod (34) is connected with the lower probe adapter plate 63 through the lower probe connecting rod fixing block (33), the lower ultrasonic probe (36) is connected with the lower probe connecting rod (34) through the lower probe compression spring (37) and the lower probe shell (35);The upper linear slide (14) is fixedly connected with the upper rudder machine connecting plate (15), the movement of the upper linear slide (14) on the upper linear guide rail (13) drives the linear motion of the upper ultrasonic probe (28) and the upper rudder machine (22), the lower linear slide (19) is fixedly connected with the lower rudder machine connecting plate (20), the movement of the lower linear slide (19) on the lower linear guide rail (18) drives the linear motion of the lower ultrasonic probe (36) and the lower rudder machine (30);The upper rudder machine (22) is connected with the upper rudder machine rotating disc (23) through the spline, the rotation of the output shaft of the upper rudder machine (22) drives the rotation of the upper ultrasonic probe (28) and the upper rudder machine rotating plate (24), the lower rudder machine (30) is connected with the lower rudder machine rotating disc (31) through the spline, the rotation of the output shaft of the lower rudder machine (30) drives the rotation of the lower ultrasonic probe (36) and the lower rudder machine rotating plate (32);The upper ultrasonic probe (28) and the lower ultrasonic probe (36) are pressed in the upper probe shell (27) and the lower probe shell (35) under the action of the upper probe compression spring (29) and the lower probe compression spring (37) respectively; The mutual adsorption of the electromagnet (12) and the adsorption cylinder (16) provides clamping displacement for the upper ultrasonic probe (28) and the lower ultrasonic probe (36);The upper ultrasonic probe (28) and the lower ultrasonic probe (36) generate clamping force under the action of the upper probe compression spring (29) and the lower probe compression spring (37) under the clamping displacement generated by the electromagnet (12) and the adsorption cylinder (16); In the non-detection stage, the electromagnet (12) is not energized and has no magnetism, the upper rudder machine connecting plate (15) and the lower rudder machine connecting plate (20) are separated from each other, the upper ultrasonic probe (28) and the lower ultrasonic probe (36) are in the retracted state, and the upper ultrasonic probe (28) and the lower ultrasonic probe (36) have no clamping force at this time;In the detection stage, the upper ultrasonic probe (28) and the lower ultrasonic probe (36) are unfolded to the to-be-detected position, the electromagnet (12) is energized to generate magnetism, the upper rudder machine connecting plate (15) and the lower rudder machine connecting plate (20) are close to each other, the upper ultrasonic probe (28) and the lower ultrasonic probe (36) are also close to each other accordingly, and the clamping force is generated under the action of the upper probe compression spring (29) and the lower probe compression spring (37), and the interface stiffness detection work is carried out; The upper steering engine rotating plate (24) and the lower steering engine rotating plate (32) are in a retracted state at an initial stage, and the upper steering engine rotating plate (24) and the lower steering engine rotating plate (32) are unfolded after the fixed clamping jaw (2) is positioned and fixed under the action of the positioning telescopic rod (3) and the fixed compression spring (4), so that the ultrasonic probe is moved to a detection area.

2. The aeroengine rotor interface stiffness in-situ ultrasonic testing apparatus of claim 1, wherein, The positioning telescopic rod (3) has a boss structure, which is clamped on the inner plane of the device base body (1) in the retracted state to prevent being ejected under the action of the fixed compression spring (4), and is matched with the groove of the device base body (1) in the unfolded state to make the fixed clamping jaw (2) be ejected in a specific posture and be fixed on the inner circular surface of the engine.

3. An in-situ ultrasonic detection method for the interface stiffness of an aero-engine rotor based on the theory of microwave transmission line, characterized in that, The fixed clamping jaw (2) is clamped on the inner ring surface of the aero-engine by using the in-situ ultrasonic detection device of the aero-engine rotor interface stiffness, the upper ultrasonic probe (28) and the lower ultrasonic probe (36) are unfolded and located above and below the to-be-detected point respectively, the upper ultrasonic probe (28) and the lower ultrasonic probe (36) are pressed to the to-be-detected position through the mutual adsorption of the electromagnet (12) and the adsorption cylinder (16), the transmission coefficient B1, the upper surface reflection coefficient C 12 , and the lower surface reflection coefficient C 43 of the ultrasonic signal emitted by the upper ultrasonic probe (28) and the lower ultrasonic probe (36) are obtained, and the interface stiffness of the to-be-detected point is obtained through calculation. The expression of the interface stiffness TRDI of the point to be tested is:

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