A multi-directional vibration test tool and method for an in-situ preloaded motor base

Abstract

The application discloses a motor base multidirectional vibration test tool and method which can be preloaded in a plane. The test tool comprises a bottom plate, a motor base mounting unit and a load applying unit arranged on the bottom plate. The motor base mounting unit is used for mounting and fixing the motor base, and the load applying unit is used for applying tension and torque simulating actual working conditions to the motor base. The test method comprises the following steps: preloading tension and torque simulating actual working conditions to the motor base on the vibration test tool; and fixing the motor base with preloaded tension and torque and the test tool as a whole on a vibration test device to perform multidirectional vibration test. The test tool of the application realizes the function of applying tension and torque under actual working conditions to the motor base on the vibration table plane through a simple structure. In combination with the vibration test device, the vibration fatigue test of the motor base under the "tension+torque+vibration" multi-load combined working condition is realized, a test environment which is more in line with actual working conditions and more scientific and reliable is constructed, and the test precision is improved.

Description

Technical Field

[0001] This invention relates to aircraft component testing technology, specifically to a multi-directional vibration testing fixture and method for an in-plane preloadable motor mount. Background Technology

[0002] With the booming development of the low-altitude economy, electric motors, as core power components, are widely used in new aircraft such as multi-rotor UAVs and electric vertical takeoff and landing (eVTOL) aircraft. The motor mount, as a key component connecting the motor to the main load-bearing structure of the aircraft, directly affects the structural reliability and even operational safety of the aircraft due to its dynamic mechanical properties, especially vibration fatigue strength. During the research, development, verification, and airworthiness certification stages of aircraft, conducting scientific and accurate vibration fatigue tests on the motor mount is an indispensable step in discovering design flaws, assessing service life, and ensuring flight safety.

[0003] Currently, motor mount vibration tests involve directly fixing the motor mount to a vibration table, simulating only simple harmonic vibration excitation in a single direction. However, in actual flight environments, the motor mount must withstand not only periodic vibrations but also the dynamic torque generated by the motor's rotation and the axial tension from the lift system. Therefore, the vibration fatigue strength obtained under existing simplified test conditions deviates significantly from actual operating conditions, often overestimating the load-bearing capacity of the motor mount. If designers base their structural designs on these test results, the motor will face premature fatigue cracking under real flight conditions, potentially leading to structural fracture and irreversible flight accidents. This disconnect between testing and actual operating conditions has become a key technological weakness restricting the reliability improvement of low-altitude aircraft.

[0004] Therefore, there is an urgent need in this field for a test fixture and method that can more realistically, conveniently and safely simulate the vibration fatigue strength of motor mounts under actual working conditions, so as to provide accurate data support for the reliability design of key aircraft components. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-directional vibration testing fixture and method for motor mounts with in-plane preloading capability. This testing fixture and method can accurately and conveniently apply preloads such as tension and torque to the motor mount within the vibration table surface, simulating the actual working conditions, and conduct multi-directional vibration tests while maintaining the preload. This realistically reproduces the combined stress state of the motor mount during actual operation, significantly improving the accuracy and reliability of vibration fatigue testing of the motor mount.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a multi-directional vibration testing fixture for an in-plane, pre-loadable motor mount, comprising: The base plate is used to fix the vibration testing equipment and provides an installation platform for other functional units. A motor mount unit is fixedly mounted on the base plate and is used to mount and fix the motor mount to be tested. The load application unit is fixedly mounted on the base plate and is used to apply load to the motor mount to simulate the tension and torque experienced by the motor mount under actual working conditions.

[0007] Using the above method and with the help of the test fixture, before the vibration test, the motor base is preloaded with the tension and torque under actual working conditions, and this preload state is locked. Then, the motor base with the preloaded tension and torque, together with the test fixture, is installed as a whole on the vibration test device for vibration test. This simulates the vibration test of the motor base under near-actual working conditions and obtains more accurate test data.

[0008] In another embodiment, to simulate the tensile force F and torque M of the motor mount, the load application unit includes a first load application unit, a second load application unit, and a third load application unit, wherein: the first load application unit applies a load to the motor mount to simulate the tensile force on the motor mount; the second and third load application units apply a pair of forces of equal magnitude and opposite direction to the motor mount, forming a torque couple to simulate the torque M on the motor mount. In this scheme, the tensile force and torque experienced by the motor mount under actual working conditions can be simulated using three simple load application units.

[0009] In another embodiment, the first load applying unit, the second load applying unit, and the third load applying unit each include: Install the uprights and fix them vertically to the base plate; The tension gauge has one end connected to the mounting column and the other end connected to the preset loading point on the motor base; The preload on the motor base can be adjusted and locked by adjusting the relative position of the tension gauge with the mounting column and the motor base.

[0010] In another embodiment, the first load unit, the second load unit, and the third load unit each include a force adjustment rod. The force adjustment rod is positioned between the tension gauge and the mounting column, with one end hinged or fixedly connected to the tension gauge and the other end movably connected to the mounting column. By adjusting the relative position of the force adjustment rod with the mounting column and the motor base, the preload on the motor base can be adjusted and locked. Simultaneously, the tension gauge can monitor and display the applied load in real time, achieving precise control of the preload.

[0011] In another embodiment, the force adjustment rod is a screw. One end of the screw is hinged or fixedly connected to a tension gauge, and the other end is fixedly connected to a mounting column via a nut. By loosening or tightening the nut, the connection position between the screw and the mounting column is changed, thereby finely adjusting the tension on the motor base. After reaching the target value, the load is stably maintained (locked) through the self-locking characteristic of the screw. This method is simple in structure, reliable, easy to adjust, and inexpensive.

[0012] In another embodiment, the motor mount unit includes a mounting column vertically fixed to a base plate. The upper part of the mounting column is provided with a connection structure, such as a through hole, threaded hole, or locating pin, adapted to the mounting hole positions of the motor mount to be tested, so as to rigidly fix the motor mount by fasteners such as bolts, ensuring the reliability of the connection interface under combined loads.

[0013] Secondly, based on the aforementioned in-plane preloadable multi-directional vibration test fixture for motor mounts, the present invention also provides an in-plane preloadable multi-directional vibration test method for motor mounts, comprising the following steps: S1. Fixture installation: Mount and fix the motor mount to be tested onto the motor mount mounting unit of the test fixture; S2. Apply preload to the motor mount: By operating the load application unit, apply the target load to the motor mount to simulate the tension and torque that the motor mount experiences under actual working conditions; S3. Vibration test: The motor base with preload applied, together with the test fixture, is fixed on the vibration test device through the base plate. Then, the vibration test device is started to apply vibration load to the motor base to simulate the stress state of the motor base under the coupled action of preload and vibration load and to carry out the vibration test. S4. Monitoring and Evaluation: During and after the vibration test, monitor and evaluate the structural response or fatigue damage of the motor mount under coupled loads.

[0014] In another embodiment, applying a preload to the motor mount in step S2 specifically includes the following steps: S21, Preloaded tension F: A tension with a target value of F1 is applied to the first loading point of the motor mount by the first load application unit to simulate the tension F experienced by the motor mount under actual working conditions; the first loading point is the mounting center of the motor on the motor mount; S22, Preloaded torque M: A tensile force F2 is applied to the second loading point of the motor mount through the second load application unit, and a tensile force F3 is applied to the third loading point of the motor mount through the third load application unit; the tensile forces F2 and F3 are equal in magnitude and opposite in direction, forming a pair of force couples to simulate the torque M experienced by the motor mount under actual working conditions; the second loading point and the third loading point are symmetrically arranged relative to the installation center.

[0015] As another implementation, considering that the motor mount may be subjected to vibrations from different directions during actual operation, the vibration test in step S3 includes: The vibration test is conducted in the Z-direction, with the vibration direction parallel to the directions of tensile forces F2 and F3. X-direction vibration test, the vibration direction is parallel to the direction of tensile force F1; The vibration test is conducted in the Y direction, with the vibration direction parallel to the lever arm direction of the tensile forces F2 and F3.

[0016] Compared with the prior art, the beneficial effects of the present invention are at least as follows: (1) Before the vibration test, the motor mount can be precisely preloaded by the test fixture to simulate the axial tension and torque generated by the motor operation under actual working conditions. Then, the motor mount with preloaded tension and torque is installed on the vibration test device as a whole with the test fixture, so that the motor mount can be subjected to vibration test under the real coupled force action of "tension + torque + vibration". This solves the problem of working condition distortion in single vibration test or complex external loading test, and builds a test environment that is more in line with actual working conditions and more scientific and reliable. This greatly improves the accuracy and reliability of vibration fatigue test data and provides accurate technical support for the performance verification and optimization of key components of aircraft power system. (2) The tooling structure is simple and the test method is easy to operate: The present invention uses standard tensile gauges, screws, columns and other common parts, which are simple in structure. Preloading can be completed by manually or by simply turning the screw. After preloading, the load is self-locked by the bolts, which is easy to operate. In addition, when switching to vibration tests in different directions, it is only necessary to change the tooling or the vibration table of the vibration test device. The whole test process is convenient to operate. Attached Figure Description

[0017] Figure 1 Schematic diagram of the installation structure for the vibration testing fixture and the motor mount. Figure 1 ; Figure 2 Schematic diagram of the installation structure for the vibration testing fixture and the motor mount. Figure 2 ; Figure 3 A schematic diagram of the working state for a Z-axis vibration test of a motor mount with in-plane preload; Figure 4 A schematic diagram of the working state for conducting an X-axis vibration test on a motor mount with in-plane preload; Figure 5 A schematic diagram of the working state for a Y-axis vibration test of a motor mount preloaded in-plane; Figure 6 Photograph of fatigue damage after vibration test of motor mount; Figure 7 Photograph 2 shows the fatigue damage after the vibration test of the motor mount; Figure 8 This is a simulation diagram of the maximum stress on the motor mount.

[0018] Explanation of reference numerals in the attached figures: 1-Base plate; 2-Motor mount unit; 3-First load application unit; 31-First column; 32-First tension gauge; 33-First force adjustment rod; 4-Second load application unit; 41-Second column; 42-Second tension gauge; 43-Second force adjustment rod; 5-Third load application unit; 51-Third column; 52-Third tension gauge; 53-Third force adjustment rod; 6-Motor mount; 7-Vibration test bench; 8-Horizontal test bench. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments are merely illustrative and explanatory and are not intended to limit the scope of protection of the present invention.

[0020] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0022] Please see Figures 1-2 The present invention provides a multi-directional vibration test fixture for a motor mount that can be preloaded in-plane, comprising: a base plate 1, a motor mount mounting unit 2, and a load application unit.

[0023] The base plate 1 is used for fixed connection with the vibration testing device and to provide an installation platform for other units. The base plate 1 is a thick, rigid metal plate, such as a steel plate, with multiple mounting holes on its bottom surface for use with bolts to install the entire testing fixture to the movable platform of the vibration testing device. The dimensions and load-bearing capacity of the base plate 1 need to be designed according to the size of the motor mount, the test load, and the specifications of the vibration worktable.

[0024] The motor mount unit 2 is fixedly mounted on the base plate 1 and is used to mount the motor mount 6 to be tested. The motor mount unit 2 includes a mounting column that is vertically welded or bolted to the base plate 1. The mounting column is provided with through holes or screw holes that correspond to the actual mounting feet of the motor mount 6. The motor mount 6 can be fixed to the motor mount unit 2 according to its actual assembly requirements by tightening bolts, ensuring connection rigidity and avoiding the introduction of additional flexibility during testing. The motor mount unit 2 can also be designed as an adjustable modular structure to accommodate motor mounts 6 of different sizes and specifications.

[0025] The load application unit includes a first load application unit 3, a second load application unit 4, and a third load application unit 5. The load applied by the first load application unit 3 to the motor mount 6 is used to simulate the axial tensile force F generated on the motor mount 6 when the motor is working. The loads applied by the second load application unit 4 and the third load application unit 5 to the motor mount 6 form a couple to simulate the torque M experienced by the motor mount 6.

[0026] The first load application unit 3 includes a first column 31, a first tension gauge 32, and a first force adjustment rod 33. The first column 31 is vertically fixed to the base plate 1. One end of the first tension gauge 32 is connected to the first loading point of the motor base 6, and the other end is connected to one end of the first force adjustment rod 33. The other end of the first force adjustment rod 33 passes through a through hole in the first column 31 and is then fixed to the first column 31 by bolts. By tightening / loosening the bolts, the load applied to the motor base 6 by the first load application unit 3 can be increased / decreased. The first loading point is located at the mounting center of the motor on the motor base 6.

[0027] The second load application unit 4 includes a second column 41, a second force gauge 42, and a second force adjustment rod 43. The second column 41 is vertically fixed to the base plate 1. One end of the second force gauge 42 is connected to the second loading point of the motor base 6, and the other end is connected to one end of the second force adjustment rod 43. The other end of the second force adjustment rod 43 passes through a through hole on the second column 41 and is then fixed to the second column 41 with bolts. The third load application unit 5 includes a third column 51, a third force gauge 52, and a third force adjustment rod 53. The third column 51 is vertically fixed to the base plate 1. One end of the third force gauge 52 is connected to the third loading point of the motor base 6, and the other end is connected to one end of the third force adjustment rod 53. The other end of the third force adjustment rod 53 passes through a through hole on the third column 51 and is then fixed to the third column 51 with bolts. By tightening / loosening the bolts, the torque received by the motor base 6 can be increased / decreased. The second and third loading points are symmetrically arranged at both ends of the motor base 6 with respect to the installation center, and the distance between them is 2d.

[0028] In the aforementioned first load application unit, second load application unit, and third load application unit, hydraulic drive, electric push rod, or other hydraulic drive methods can also be used to accurately apply and maintain the preload.

[0029] The method for conducting vibration tests on the motor mount using the test fixture in this embodiment is as follows: S1. Fixture installation: Install and fix the motor mount 6 to be tested onto the motor mount mounting unit 2 of the test fixture; S2. Apply preload: Apply preload to motor mount 6 through load application unit to simulate the tension and torque experienced by motor mount 6 under actual working conditions; S21, Preload tension: The first load application unit 3 applies a tension with a target value of F1 to the first loading point of the motor mount 6 to simulate the tension F that the motor mount 6 is subjected to in actual working conditions; the first loading point is the installation center of the motor on the motor mount 6; when applying the load, tighten the nut on the force adjustment rod while observing the reading on the tension gauge. When the reading reaches the target tension value F1, stop tightening the nut and lock the tension F; S22, Preloaded Torque M: A tensile force F2 is applied to the second loading point of the motor mount 6 through the second load application unit 4, and a tensile force F3 is applied to the third loading point of the motor mount 6 through the third load application unit 5. The tensile forces F2 and F3 are equal in magnitude (F2=F3=M / 2d) and opposite in direction, forming a couple to simulate the torque M experienced by the motor mount 6 under actual working conditions. The second and third loading points are symmetrically arranged about the installation center. The adjustment methods of tensile forces F2 and F3 are the same as those of F1. The tension F and torque M are matched and set according to the actual working conditions of the motor base 6.

[0030] At this point, the motor base 6 is preloaded with a tension F and a torque M equivalent to the actual working conditions on the stationary base plate 1. S3. Vibration Test: The preloaded motor mount, along with the test fixture, is fixed as a whole onto the vibration test device. The vibration test device is started, and a vibration load is applied to the motor mount, placing it under the coupled force of the preload and the vibration load. During the vibration test, vibration can be applied to the motor mount in the X, Y, and Z directions sequentially (the order of application is arbitrary). The vibration time can be reasonably preset according to the actual working conditions that the motor mount needs to meet. The condition of the motor mount is observed at any time during the test, and the test is stopped immediately if vibration damage such as cracks occurs. In this invention, the direction of tension F1 is defined as the X direction, the direction of the lever arm of tensions F2 and F3 is defined as the Y direction, and the direction of tensions F2 and F3 is defined as the Z direction. The vibration test of the motor mount includes: S31. Place the entire test fixture directly on the vibration test bench 7 of the vibration test apparatus and apply vibration in the Z direction. See Appendix for details. Figure 3 ; After completing steps S32 and S31, move the entire test fixture to the horizontal test platform 8. Then, rotate the vibration test platform 7 90° and connect it to the horizontal test platform 8. Apply vibration in the X direction to the entire test fixture. See Appendix for details. Figure 4 ; After completing steps S33 and S32, rotate the test fixture 90° on the horizontal test bench 8, and then apply vibration in the Y direction to the entire test fixture. See Appendix for details. Figure 5 ; S4. Monitoring and Evaluation: During and after the vibration test, monitor and evaluate the structural response or fatigue damage of the motor mount under the coupled action of preload and vibration load.

[0031] In this invention, the aforementioned test fixtures and methods were used to conduct a vibration test on a 600 kg EVTOL motor mount. The motor mount was made of chopped carbon fiber composite material. During the test, the preload tension was 2500 N and the preload torque was 120 Nm. Vibration was performed for 24 hours in each of the Z, Y, and X directions. The motor mount was in good condition after vibration in the Z and Y directions. Cracks appeared after vibration in the X direction for 10 hours, at which point the test was stopped. The location of the cracks in the motor mount is shown in the appendix. Figure 6 and Figure 7 Meanwhile, finite element simulation was used to predict the location of the maximum stress on the motor mount. See the attached simulation diagram. Figure 8 .Depend on Figures 6-7 It can be seen that the location of the crack in the vibration test is consistent with the location of the maximum stress shown in the simulation results. The vibration test results and the simulation results verify each other, which shows the accuracy and reliability of the vibration test results.

[0032] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A multi-directional vibration test fixture for a motor base with in-plane preloading capability, characterized in that, include: The base plate is used for fixed connection with the vibration testing equipment and to provide an installation platform for other functional units; A motor mount unit is fixedly mounted on the base plate and is used to mount the motor mount to be tested. The load application unit is fixedly mounted on the base plate and is used to apply load to the motor mount to simulate the tension and torque experienced by the motor mount in actual working conditions.

2. The in-plane preloadable multi-directional vibration test fixture for motor mounts according to claim 1, characterized in that, The load application unit includes a first load application unit, a second load application unit, and a third load application unit, wherein: the load applied by the first load application unit to the motor mount is used to simulate the tensile force on the motor mount; the load applied by the second load application unit to the motor mount and the load applied by the third load application unit to the motor mount form a couple, used to simulate the torque M on the motor mount.

3. The in-plane preloadable multi-directional vibration test fixture for motor mounts according to claim 2, characterized in that, The first load application unit, the second load application unit, and the third load application unit each include: Install the uprights and fix them vertically to the base plate; The tension gauge has one end connected to the mounting column and the other end connected to the preset loading point on the motor base; The load applied to the motor base can be adjusted and locked by adjusting the relative position of the tension gauge with respect to the mounting column and motor base.

4. The in-plane preloadable multi-directional vibration test fixture for motor mounts according to claim 3, characterized in that, The first load application unit, the second load application unit, and the third load application unit each include a force adjustment rod. The force adjustment rod is disposed between the tension gauge and the mounting column. One end of the rod is hinged or fixedly connected to the tension gauge, and the other end is connected to the mounting column. By adjusting the force adjustment rod, the relative position between the tension gauge and the motor base / mounting column can be controlled, and the magnitude of the load applied to the motor base can be adjusted and locked.

5. The in-plane preloadable multi-directional vibration test fixture for motor mounts according to claim 1, characterized in that, The motor mount unit includes a mounting column, which is vertically fixed to the base plate, and has a connecting structure for fixing the motor mount.

6. A method for multi-directional vibration testing of a motor mount with in-plane preloading capability, characterized in that, Based on the test fixture according to any one of claims 1-5, the test method includes the following steps: S1. Fixture installation: Mount and fix the motor mount to be tested onto the motor mount mounting unit of the test fixture; S2. Apply preload: Apply preload to the motor mount through the load application unit to simulate the tension and torque experienced by the motor mount under actual working conditions; S3. Vibration test: The motor base with preload applied, together with the test fixture, is installed and fixed as a whole on the vibration test device. Then, the vibration test device is started to apply a vibration load to the motor base, so that the motor base is under the stress state of the coupling action of preload and vibration load and the vibration test is carried out. S4. Monitoring and Evaluation: During and after the vibration test, monitor and evaluate the structural response or fatigue damage of the motor mount under the coupled action of preload and vibration load.

7. The method for multi-directional vibration testing of a motor mount with in-plane preloading as described in claim 6, characterized in that, Step S2 includes: Preload tension: A tension F1 is applied to the first loading point of the motor mount through the first load application unit to simulate the tension F experienced by the motor mount in actual working conditions; the first loading point is the installation center of the motor on the motor mount; Preloaded torque M: A tensile force F2 is applied to the second loading point of the motor mount through the second load application unit, and a tensile force F3 is applied to the third loading point of the motor mount through the third load application unit; the tensile forces F2 and F3 are equal in magnitude and opposite in direction, forming a pair of force couples to simulate the torque M experienced by the motor mount in actual working conditions; the second loading point and the third loading point are symmetrically arranged relative to the installation center.

8. The method for multi-directional vibration testing of a motor mount with in-plane preloading according to claim 6 or 7, characterized in that, The vibration test in step S3 includes: The vibration test is conducted in the Z-direction, with the vibration direction parallel to the directions of tensile forces F2 and F3. X-direction vibration test, the vibration direction is parallel to the direction of tensile force F1; The vibration test is conducted in the Y direction, with the vibration direction parallel to the lever arm direction of the tensile forces F2 and F3.

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