Aero-engine axial load sensor modal test device and method

Abstract

The invention provides a modal test device and method for an axial load sensor of an aero-engine, and relates to the technical field of aero-engines, the axial load sensor is extruded under the combined action of a loading top seat and a loading base, the load borne by the axial load sensor in the engine can be simulated, and the reliability of the axial load sensor is improved. An experiment of the axial load sensor is carried out based on the method, during the experiment, a vibration exciter is adopted to carry out sweep frequency excitation, a finite element method is combined to carry out reasonable distribution design on strain gauges, the strain gauges are used to acquire strain response and corresponding frequency of the sensor in a resonance state, and a displacement reconstruction algorithm based on strain data is developed. Therefore, the vibration mode of the sensor can be accurately identified and reconstructed, the multi-angle test of the axial load sensor can be realized, and the problem of the axial load sensor in the actual use process can be comprehensively considered.

Description

Technical Field

[0001] The present application relates to the technical field of aero-engines, and in particular to a modal test device and method for an aero-engine axial load sensor. Background Art

[0002] The aircraft engine axial load sensor is installed on the engine's thrust bearing. As the thrust bearing serves as the foundation of the aircraft engine rotor and a key component limiting the engine's overhaul life, its reliability is paramount. Excessive axial load and slippage under light load are significant factors in causing bearing damage. Because axial load is influenced by numerous factors, field measurements are typically the primary method. Furthermore, axial dynamic load provides a direct understanding of the engine's operating status, making real-time monitoring of axial dynamic load essential for ensuring healthy engine operation.

[0003] Currently, the more accurate method for thrust bearing load testing is to use a ring axial load sensor such as Figure 1 As shown in the figure, a quasi-static test method is performed by placing the load cell on the thrust bearing of the engine. However, with the continuous optimization of aircraft engine structures, limited sensor installation space and the design requirements of multi-parameter integrated sensors, this type of annular axial load sensor is gradually being expanded to have both static and dynamic load testing capabilities. However, there is currently a lack of test methods and corresponding equipment for studying the natural vibration characteristics of this type of axial load sensor in the working environment, including vibration mode and frequency. Summary of the Invention

[0004] One of the technical problems to be solved by this application is that the existing test environment cannot truly reflect the working environment of the sensor under the aircraft engine and obtain the vibration characteristics in this environment for data collection.

[0005] To solve the above technical problems, the present invention provides an aircraft engine axial load sensor modal test device, which includes: A loading base is provided with a heat source to heat the surface of the loading base, and an oil layer is provided on the surface of the loading base to simulate the oil-immersion environment in an aircraft engine; An axial load sensor is provided with a boss at the center of the loading base, and the axial load sensor is located on the surface of the boss. The axial load sensor is in a ring shape; The loading top seat is connected to the external loading head and is movably arranged relative to the loading base along the gravity direction to cooperate with the boss to apply pressure to the axial load sensor; The surface of the axial load sensor is provided with a plurality of bumps, two adjacent bumps form a test area, and each test area is spaced apart along the circumference relative to the axial load sensor. The bottom of the loading top seat is provided with a plurality of pressure strips, which contact with the bumps in the test area to squeeze the axial load sensor. a plurality of strain gauges, wherein the plurality of strain gauges are located on the axial load sensor to collect strain response signals of the axial load sensor; The exciter is used to apply exciting force to the axial load sensor.

[0006] In some embodiments, the aforementioned aero-engine axial load sensor modal test device, wherein the side wall of the loading base is provided with a through hole, the surface of the through hole is provided with a connector, the exciter is connected to the connector through the through hole to apply an exciting force to the axial load sensor from a radial direction, and a plurality of strain gauges are located on the side walls of the inner circle and the outer circle of the axial load sensor; wherein the position of the strain gauge located on the inner ring corresponds to the position of the strain gauge located on the outer ring, and the strain gauge is located between any two adjacent test areas.

[0007] In some embodiments, in the aforementioned aero-engine axial load sensor modal test device, a sealing assembly is provided on the side of the through hole facing the loading base, and the sealing assembly is connected to the connector to prevent leakage of the oil layer.

[0008] In some embodiments, a modal test device for an aero-engine axial load sensor is described above, wherein a plurality of recessed platforms are provided on the loading top seat, and the strain gauge is located between any two adjacent test areas on the surface of the axial load sensor; wherein the exciter applies an exciting force to the axial load sensor in the axial direction from the recessed platforms.

[0009] A second aspect of the present application provides a modal test method for an aero-engine axial load sensor, which is implemented using an aero-engine axial load sensor modal test device and includes the following steps.

[0010] S1. Determine the position of the axial load sensor to be detected, and then connect the strain gauge to the axial load sensor; S2. Place the axial load sensor on the boss at the center of the loading base. Add aviation lubricant to the surface of the loading base until the axial load sensor is completely covered and heat it. S3, using the external loading head to drive the loading top seat to move toward the axial load sensor for extrusion; S4, causing the exciter to apply an exciting force toward the axial load sensor along an axial or radial direction, and simultaneously obtaining the frequency of the axial load sensor through the strain gauge; S5. Calculate the curvature of the test point where the strain gauge is attached, calculate the strain of the points other than the test point where the strain gauge is attached by quadratic difference, and calculate the curvature by strain, then calculate the curvature function between the two adjacent strain gauge measurement points, then integrate the curvature function along the arc length to obtain the deflection curve angle equation, integrate the obtained deflection curve angle equation to finally obtain the curve equation, finally obtain the coordinates of the curve and fit it, and compare the fitted curve with the simulation curve.

[0011] In some embodiments, in the aforementioned modal test method for an aircraft engine axial load sensor, when the exciter in S4 applies an excitation force to the axial load sensor in a radial direction, and the strain gauges in S1 are located on the inner and outer circles of the axial load sensor, the curvature K of the axial load sensor is: ; in, is the inner radius of the axial load sensor (4), is the initial arc length of the inner circle at the measuring point of the strain gauge (9), is the arc length of the inner circle after the strain gauge (9) measures the change, is the inner circle variation strain at the measuring point of strain gauge (9), is the outer radius of the axial load sensor (4), is the initial arc length of the outer circle at the measurement location of the strain gauge (9), is the arc length of the outer circle after the strain gauge (9) measures the change, is the outer circle strain variation at the measuring point of strain gauge (9), is the central angle of the bending deformation at the measuring point of the strain gauge (9), h is the radial thickness of the axial load sensor (4).

[0012] In some embodiments, in the aforementioned aero-engine axial load sensor modal test method, the curvature function in S5 is expressed as: ; in, is the arc length between any point between point i and point i-1, The arc length from point i-1 is The curvature at the point, and Represents the linear interpolation coefficient of the arc segment between point i-1 and point i; The expression of the deflection curve angle equation is: ; in, is the angle between the tangent line of the deflection curve and the x-axis, is the arc length of the infinitesimal segment; The expression of the curve equation is: ; in, x ( u )and y ( u ) represent the x-axis coordinate and y-axis coordinate of the deflection curve respectively.

[0013] In some embodiments, in the aforementioned modal test method for an aircraft engine axial load sensor, when the exciter in S4 applies an excitation force to the axial load sensor in the axial direction, and the strain gauge in S1 is located between any two adjacent test areas, the curvature K of the axial load sensor is: ; in, is the axial thickness of the axial load sensor (4), L is the length of the strain gauge (9) at the measuring point, is the central angle of the bending deformation at the measuring point of the strain gauge (9), The strain at the end face measured by the strain gauge (9).

[0014] In some embodiments, in the aforementioned aero-engine axial load sensor modal test method, the curvature function in S5 is expressed as: ; in, s is the length between any point between point i and point i-1, The distance from point i-1 is s The curvature at the point, and Represents the linear interpolation coefficient of the infinitesimal line segment between point i-1 and point i; The expression of the deflection curve angle equation is: ; in, is the tangent line of the deflection curve and xoy Plane angle, is the length of the infinitesimal line segment; Align the i-th segment with the y-axis of the coordinate axis, and then i The deflection curve integral calculation is performed on each segment to obtain the Z direction change of each end point Value, then The value is rotated by the coordinate matrix Transform to get the real change in the Z direction of each end point value, and finally The Z-axis coordinate of the reconstructed vibration mode is obtained by adding up the values The size of the value; The curve equation is expressed as: ; Z-axis coordinate of the reconstructed vibration mode The calculation process is: ; ; ; is the rotation matrix around the x-axis, is the rotation matrix around the z axis, For the i Point coordinate rotation matrix, is the initial angle between two adjacent infinitesimal line segments.

[0015] Through the above technical scheme, the present application provides a modal test device for an aero-engine axial load sensor, which can maximize the simulation and reproduction of the high temperature and oil immersion environment of the axial load sensor during engine operation through the oil layer and heat source on the loading base. At the same time, the axial load sensor is squeezed under the joint action of the loading top seat and the loading base, which can simulate the load on the axial load sensor in the engine and maximize the restoration of the use environment of the axial load sensor. Based on this, experiments on the axial load sensor are carried out. During the experiment, an exciter is used for swept frequency excitation, and the strain gauge is reasonably distributed and designed in combination with the finite element method. The strain gauge is used to collect the strain response and corresponding frequency of the sensor in the resonant state, and a displacement reconstruction algorithm based on strain data is developed, thereby realizing accurate identification and reconstruction of the sensor vibration mode, realizing multi-angle testing of the axial load sensor, and obtaining the accurate changes of the axial load sensor in this state, to ensure that all-round consideration is given to the problems that arise during the actual use of the axial load sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 This is a schematic structural diagram of an axial load sensor of an aero-engine axial load sensor modal test device disclosed in an embodiment of the present application; Figure 2 This is a structural schematic diagram of a loading top seat of a modal test device for an aero-engine axial load sensor disclosed in an embodiment of the present application; Figure 3 This is a schematic structural diagram of a loading base of a modal test device for an aero-engine axial load sensor disclosed in an embodiment of the present application; Figure 4 This is a schematic structural diagram of the radial connection of a vibrator of a modal test device for an aero-engine axial load sensor disclosed in an embodiment of the present application; Figure 5 This is a schematic structural diagram of the axial connection of a vibrator of an aero-engine axial load sensor modal test device disclosed in an embodiment of the present application; Figure 6 This is a schematic structural diagram of strain gauge connections during radial testing of a modal test device for an axial load sensor of an aero-engine disclosed in an embodiment of the present application; Figure 7 This is a structural diagram of the strain gauge connection during axial testing of a modal test device for an aero-engine axial load sensor disclosed in an embodiment of the present application; Figure 8 This is a schematic diagram of the local changes of an axial load sensor during radial testing of an aero-engine axial load sensor modal test device disclosed in an embodiment of the present application; Figure 9 This is a schematic diagram of the local changes of an axial load sensor during axial testing of an aero-engine axial load sensor modal test device disclosed in an embodiment of the present application; Figure 10 This is a partial cross-sectional structural diagram of a connector of an aero-engine axial load sensor modal test device disclosed in an embodiment of the present application when connected; Figure 11 1. This is a schematic diagram comparing the reconstructed calculation and simulation results of the vibration mode change of the axial load sensor during radial excitation in the second embodiment of the present application; Figure 12 This is a schematic diagram of the specific structure of a sealing component of an aero-engine axial load sensor modal test device according to the present application.

[0018] Description of reference numerals: 1. Loading base; 2. Through hole; 3. Connector; 4. Axial load sensor; 5. Boss; 6. Loading top seat; 7. Bump; 8. Pressure strip; 9. Strain gauge; 10. Vibrator; 11. Concave platform; 12. Sealing assembly; 1201. Sealing plate; 1202. Sealing rubber. DETAILED DESCRIPTION

[0019] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The detailed description of the following examples and the accompanying drawings are intended to illustrate the principles of the present application, but are not intended to limit the scope of the present application. The present application may be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but rather includes all technical solutions within the scope of the claims.

[0020] The present application provides these embodiments to make this application thorough and complete, and to fully express the scope of this application to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values ​​set forth in these embodiments should be interpreted as merely exemplary, and not as limiting.

[0021] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. A person of ordinary skill in the art will understand the specific meanings of the above terms in this application depending on the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intervening device between the specific device and the first or second device.

[0022] All terms used in this application have the same meaning as understood by one of ordinary skill in the art to which this application belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and should not be interpreted in an idealized or highly formal sense, unless explicitly defined as such herein.

[0023] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0024] Example 1 Reference Attachment Figure 1 To the attached Figure 10 and attached Figure 12The present embodiment discloses a modal test device for an aircraft engine axial load sensor 4, which includes a loading base 1, an axial load sensor 4, a loading top seat 6, a strain gauge 9 and an exciter 10; wherein the loading base 1 and the loading top seat 6 are hard metal base bodies, wherein the inner bottom of the loading base 1 is a hollow structure where a heat source can be placed, which can be, but is not limited to, an experimental electric heating furnace, and can provide a high-temperature environment for the detection test of the axial load sensor 4; in addition, a boss 5 is provided on the loading base 1, and when conducting the experiment, the axial load sensor 4 is placed on the boss 5 for detection test. Since the boss 5 is arranged on the surface of the loading base 1 to form a height difference, aviation lubricating oil can be added and the axial load sensor 4 can be completely immersed in the oil layer, simulating the actual use environment of the axial load sensor 4, and the loading top seat 6 acts vertically from the top to squeeze the axial load sensor 4 to apply an axial load.

[0025] In addition, when the loading seat 6 squeezes the axial load sensor 4, the pressure strip 8 on the loading seat 6 presses the bump 7 on the axial load sensor 4. In conjunction with the exciting force applied by the vibrator 10, more obvious changes in the axial load sensor 4 can be observed. As a result, the axial load sensor 4 will receive vibration responses in different directions when receiving the load. In order to capture responses in different directions, the vibrator 10 is required to apply exciting forces to the axial load sensor 4 from different positions to cause the axial load sensor 4 to undergo different vibration mode changes. Similarly, the strain gauge 9 also needs to be adjusted at any time according to the excitation when it is set on the axial load sensor 4. It can be understood that the excitation When the vibrator 10 applies a radial excitation force to the axial load sensor 4, the strain gauge 9 needs to be set on the inner circle and outer circle of the axial load sensor 4, because the inner circle and the outer circle will receive excitation at the same time and the stress changes at the two places need to be collected, and the strain gauge 9 on the inner circle and the strain gauge 9 on the outer circle are both located on the same radius extension line to ensure the synchronization of the test and the detection of the same position, and the setting of the strain gauge 9 is circumferentially distributed around the center of the axial load sensor 4, and can be but not limited to an interval angle of 45°, so that the strain gauge 9 is evenly distributed, and when the vibrator 10 applies a radial excitation force, it is specifically connected to the connector 3 in the through hole 2, such as Figure 12As shown, it can be understood that, since aviation lubricant is added to the loading base 1 to prevent leakage of aviation lubricant, a sealing component 12 is further provided on the contact surface of the connector 3 and the through hole 2, wherein the sealing component 12 includes a sealing plate 1201 and a sealing rubber 1202. The sealing plate 1201 is located at the entrance of the through hole 2, and the sealing rubber 1202 is used to connect the sealing plate 1201 and the connector 3. It can be, but is not limited to, fluororubber, which can still ensure the stability of performance when the ambient temperature reaches 200°C, and can meet the use requirements of the present environment under 150°C conditions. It can be understood that when the exciter 10 is connected, it passes through the through hole 2 and extends into the sealing rubber 1202, and is finally connected to the connector 3. The excitation force of the exciter 10 is transmitted through the connector 3. The exciter 10 and the connector 3 are connected and finally act together on the axial load sensor 4 to apply the excitation force, wherein the sealing rubber 1202 can realize the soft connection between the connector 3 and the sealing plate 1201, realize the free vibration of the exciter 10 and the connector 3, and realize the lossless transmission of the excitation force.

[0026] Next, when it is necessary to apply longitudinal excitation to the axial load sensor 4, that is, perpendicular to the axial direction of the axial load sensor 4, the exciter 10 is vertically connected to the axial load sensor 4, wherein a recess 11 is provided on the loading top seat 6, and the recess 11 is located between two adjacent pressure strips 8. The axial load sensor 4 is applied from here, and the strain gauge 9 is set on the surface of the axial load sensor 4 where the protrusion 7 is located, not at the position where the protrusion 7 is set. Similarly, the angle between each strain gauge 9 can also be set according to actual conditions, which can be but not limited to 45°. The vibration mode data of the axial load sensor 4 in two directions are completely collected in two ways.

[0027] In addition, after the vibration mode collection is completed, the vibration mode reconstruction algorithm is used to reconstruct the actual vibration mode change of the axial load sensor 4.

[0028] Example 2 In this embodiment, the exciter is connected to the connector to apply an excitation force to the axial load sensor from the radial direction, wherein the inner diameter of the axial load sensor is R 1 =95 mm , the outer diameter is R 2 =103.5mm , thick h` = 4.5mmTaking the ring as an example, the ring is evenly divided into 360 micro-segments using 360 points. The number of micro-segments can be adjusted according to the specific size of the ring. In addition, the size of the strain gauge is much larger than the micro-segment. The micro-segment detected by the strain gauge is the micro-segment located at the center of the strain gauge. The 360 ​​points are numbered 0, 1, 2...358, 359, of which 8 points are measuring points. The strains of the measuring points have been measured by the strain gauge, and the corresponding measuring points are numbered 0, 45, 90, 135, 180, 225, 270, and 315. The strains of the remaining points are obtained by quadratic interpolation.

[0029] Take points 50, 51, and 52 as an example to perform reconstruction calculation. Taking point 0 as the starting point, in order to calculate the strain of points 50-52, it is necessary to use points 45, 90, and 135 as nodes for interpolation calculation. Let s be the arc length from the measuring point to the starting point. is the strain at the point. The arc length and strain at the node obtained from the simulation are shown in Table 1.

[0030] Table 1: The arc length from each measuring point to the starting point and the strain at the measuring point; ; According to the quadratic interpolation formula: ; Similarly, the outer diameter strain of point 50 can be calculated And the internal and external strains of points 51 and 52 , and its values ​​are shown in Table 2.

[0031] Table 2: Inner diameter strain and outer diameter strain at points 50, 51, and 52; ; According to the relationship formula between strain and curvature, the curvature of points 50, 51, and 52 can be calculated. , the calculation formula for point 50 is as follows: ; According to the above algorithm, the curvatures of points 50, 51, and 52 are calculated as follows: , the curvature of each point in the infinitesimal segment between points 50 and 51 is fitted by linear interpolation, that is: ; Calculate the difference fitting coefficient of the infinitesimal segment M 50,51 and N 50,51 ,in is the arc length of the infinitesimal segment. Since the infinitesimal segment is evenly divided, the arc length is a constant. Similarly, the curvature function of the infinitesimal segment between points 51 and 52 can be obtained, so the curvature functions of the two infinitesimal segments are: ; Then, the curvature function is integrated along the arc length to obtain the rotation angle of the deflection curve of the axial load sensor. ; The angle of point 50 has been calculated from the curvature function between points 49 and 50. , then the rotation angle functions of the infinitesimal segment between points 50 and 51 and the infinitesimal segment between points 51 and 52 are: ; The coordinate expression can be obtained by integrating the rotation function along the arc length. From the coordinate expression between points 49 and 50, the coordinate of point 50 is , then the coordinate functions of the infinitesimal segment between points 50 and 51 and the infinitesimal segment between points 51 and 52 are shown as follows, and the coordinate data and rotation angles of points 51 and 52 are shown in Table 3.

[0032] ; ; Table 3: Coordinate data and angle of points 51 and 52; ; The coordinates of 360 points are calculated through the above process, and the sensor vibration shape can be reconstructed by fitting. The reconstruction result is consistent with the simulation result as shown in the figure. Figure 11 As shown, and compared with the simulation results R 2 =0.95, which meets the accuracy required by the test.

[0033] In addition, when applying longitudinal excitation to the axial load sensor 4, the i-th segment is first overlapped with the y-axis of the coordinate axis when calculating the Z-axis in the reconstructed vibration mode, with the starting coordinates as (0,0,0) and the end coordinates as The infinitesimal line segment is used to perform the deflection curve integral calculation to obtain the coordinates of the end point after integration for , the end point coordinates Rotate the coordinate matrix Get the change of the z-axis coordinate of each end point , and finally each segment changes Accumulate and get the Z-axis coordinate of the reconstructed vibration mode ;in and The relationship is: .

[0034] So far, the various embodiments of the present application have been described in detail. To avoid obscuring the concept of the present application, some details well known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0035] Although some specific embodiments of the present application have been described in detail through examples, those skilled in the art will understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present application. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present application. In particular, as long as there are no structural conflicts, the various technical features mentioned in the various embodiments may be combined in any manner.

Claims

1. A modal test device for an aero-engine axial load sensor, characterized in that: include: A loading base (1), wherein a heat source is provided in the loading base (1) to heat the surface of the loading base (1), and an oil layer is provided on the surface of the loading base (1) to simulate the oil-immersion environment in an aircraft engine; An axial load sensor (4), wherein a boss (5) is provided at the center of the loading base (1), the axial load sensor (4) is located on the surface of the boss (5), and the axial load sensor (4) is annular; A loading top seat (6), the loading top seat (6) is connected to an external loading head, and the loading top seat (6) is movably arranged relative to the loading base (1) along the direction of gravity to cooperate with the boss (5) to apply pressure to the axial load sensor (4); The surface of the axial load sensor (4) is provided with a plurality of protrusions (7), two adjacent protrusions (7) form a test area, and each of the test areas is spaced apart along the circumferential direction relative to the axial load sensor (4). The bottom of the loading top seat (6) is provided with a plurality of pressure strips (8), and the pressure strips (8) contact the protrusions (7) in the test area to squeeze the axial load sensor (4); a plurality of strain gauges (9), wherein the plurality of strain gauges (9) are located on the axial load sensor (4) to collect strain response signals of the axial load sensor (4); An exciter (10), the exciter (10) being used to apply an exciting force to the axial load sensor (4).

2. The aero-engine axial load sensor modal test device according to claim 1, characterized in that: The side wall of the loading base (1) is provided with a through hole (2), the surface of the through hole (2) is provided with a connector (3), the exciter (10) passes through the through hole (2) and is connected to the connector (3) to apply an exciting force to the axial load sensor (4) in a radial direction, and a plurality of strain gauges (9) are located on the side walls of the inner circle and the outer circle of the axial load sensor (4); The position of the strain gauge (9) located on the inner circle corresponds to the position of the strain gauge (9) located on the outer circle, and the strain gauge (9) is located between any two adjacent test areas.

3. The aero-engine axial load sensor modal test device according to claim 2, characterized in that: A sealing component (12) is provided on the side of the through hole (2) facing the loading base (1), and the sealing component (12) is connected to the connector (3) to prevent leakage of the oil layer.

4. The aero-engine axial load sensor modal test device according to claim 1, characterized in that: A plurality of concave platforms (11) are provided on the loading top seat (6), and the strain gauge (9) is located between any two adjacent test areas on the surface of the axial load sensor (4); The exciter (10) applies an exciting force in the axial direction to the axial load sensor (4) from the concave platform (11).

5. A modal test method for an aero-engine axial load sensor, characterized in that: The method is implemented using the aircraft engine axial load sensor modal test device according to any one of claims 1 to 4, comprising the following steps: S1, determining the position of the axial load sensor (4) to be detected, and then connecting the strain gauge (9) to the axial load sensor (4); S2, placing the axial load sensor (4) on the boss (5) at the center of the loading base (1), adding aviation lubricating oil to the surface of the loading base (1) until the axial load sensor (4) is completely covered and heating is performed; S3, driving the loading top seat (6) toward the axial load sensor (4) through the external loading head to perform extrusion; S4, causing the exciter (10) to apply an exciting force to the axial load sensor (4) along the axial or radial direction, and simultaneously obtaining the vibration frequency of the axial load sensor (4) through the strain gauge (9); S5. Calculate the curvature of the test point where the strain gauge (9) is attached, calculate the strain of the points other than the test point where the strain gauge is attached by using the quadratic difference, and calculate the curvature by using the strain, then calculate the curvature function between two adjacent test points, then integrate the curvature function along the arc length to obtain the equation of the angle of the deflection curve, integrate the obtained equation of the angle of the deflection curve to finally obtain the curve equation, finally obtain the coordinates of the curve and perform fitting, and compare the fitting curve with the simulation curve.

6. The modal test method for an aero-engine axial load sensor according to claim 5, characterized in that: When the exciter (10) in S4 applies an exciting force to the axial load sensor (4) in the radial direction, the strain gauge (9) in S1 is located on the inner circle and the outer circle of the axial load sensor (4). At this time, the curvature K of the axial load sensor (4) is: ； in, is the inner radius of the axial load sensor (4), is the initial arc length of the inner circle at the measuring point of the strain gauge (9), is the arc length of the inner circle after the strain gauge (9) measures the change, is the inner circle variation strain at the measuring point of strain gauge (9), is the outer radius of the axial load sensor (4), is the initial arc length of the outer circle at the measurement location of the strain gauge (9), is the arc length of the outer circle after the strain gauge (9) measures the change, is the outer circle strain variation at the measuring point of strain gauge (9), is the central angle of the bending deformation at the measuring point of the strain gauge (9), h is the radial thickness of the axial load sensor (4).

7. The modal test method for an aero-engine axial load sensor according to claim 6, characterized in that: The expression of the curvature function in S5 is: ； in, is the arc length between any point between point i and point i-1, The arc length from point i-1 is The curvature at the point, and Represents the linear interpolation coefficient of the arc segment between point i-1 and point i; The expression of the deflection curve angle equation is: ； in, is the angle between the tangent line of the deflection curve and the x-axis, is the arc length of the infinitesimal segment; The expression of the curve equation is: ； in, x ( u )and y ( u ) represent the x-axis coordinate and y-axis coordinate of the deflection curve respectively.

8. The modal test method for an aero-engine axial load sensor according to claim 5, characterized in that: When the exciter (10) in S4 applies an exciting force to the axial load sensor (4) in the axial direction, and the strain gauge (9) in S1 is located between any two adjacent test areas, the curvature K of the axial load sensor (4) is: ； in, is the axial thickness of the axial load sensor (4), L is the length of the strain gauge (9) at the measuring point, is the central angle of the bending deformation at the measuring point of the strain gauge (9), is the end face strain measured by the strain gauge (9).

9. The modal test method for an aero-engine axial load sensor according to claim 8, characterized in that: The expression of the curvature function in S5 is: ； in, s is the length between any point between point i and point i-1, The distance from point i-1 is s The curvature at the point, and Represents the linear interpolation coefficient of the infinitesimal line segment between point i-1 and point i; The expression of the deflection curve angle equation is: ； in, is the tangent line of the deflection curve and xoy Plane angle, is the length of the infinitesimal line segment; Align the i-th segment with the y-axis of the coordinate axis, and then i The deflection curve integral calculation is performed on each segment to obtain the Z direction change of each end point Value, then The value is rotated by the coordinate matrix Transform to get the real change in the Z direction of each end point value, and finally The Z-axis coordinate of the reconstructed vibration mode is obtained by adding up the values The size of the value; The curve equation is expressed as: ； Z-axis coordinate of the reconstructed vibration mode The calculation process is: ； ； ； is the rotation matrix around the x-axis, is the rotation matrix around the z axis, For the i Point coordinate rotation matrix, is the initial angle between two adjacent infinitesimal line segments.

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