A horizontal elastic ring non-linear stiffness test platform and test method

Abstract

The present invention relates to a horizontal elastic ring nonlinear stiffness testing platform and testing method, comprising a base, a measuring module, a test module and a loading module; the test module comprises a supporting inner ring fixedly connected to the base and a supporting outer ring sleeved on the outer ring of the supporting inner ring, and the elastic ring is located between the supporting inner ring and the supporting outer ring; the loading module comprises a load bracket fixedly connected to the base and a loading screw passing through the load bracket, a loading nut is installed on the loading screw on the side of the load bracket away from the test module, a polygonal portion is provided on the loading screw, a polygonal hole adapted to the polygonal portion is opened on the load bracket, and the loading screw is connected to the supporting outer ring through a tension sensor; the measuring module comprises a displacement sensor installed on the base and a displacement amplifier for amplifying the displacement of the supporting outer ring. The present invention can test elastic rings of different sizes and matching states, and has simple operation, a wide range of applications and low cost.

Description

Technical Field

[0001] The present invention relates to the field of novel test platforms, in particular to the field of elastic support test platforms, and specifically refers to a horizontal elastic ring nonlinear stiffness test platform and a test method. Background Art

[0002] The rotor systems of most aircraft engines are equipped with elastic supports at the fulcrums. The purpose is to adjust and control the critical speed by changing the support stiffness, while improving the strain energy distribution of the rotor-casing system.

[0003] Steel ring elastic supports, also known as elastic rings, are radial elastic supports with an equal number of bosses on their inner and outer surfaces, staggered and equidistant along the circumference. The outer bosses contact the inner ring surface of the bearing housing, while the inner bosses contact the outer ring of the bearing. The elastic rings offer a simple structure, lightweight design, high reliability, and excellent vibration damping properties. Their stiffness significantly influences the rotor system's unbalance response, vibration mode, critical speed, and transfer characteristics. Accurately determining the elastic ring stiffness is crucial for analyzing the rotor system's response characteristics.

[0004] Calculating the elastic ring's stiffness primarily involves analytical methods and the finite element method (FEM). The analytical method requires significant simplification of the ring model during the calculation process, resulting in low accuracy. It can only estimate the magnitude of the ring's stiffness and provide limited guidance in design, but cannot calculate the ring's strength characteristics, such as stress distribution. The FEM, on the other hand, can account for more structural details and more complex boundary conditions when calculating the ring's stiffness, resulting in higher accuracy. However, the nonlinearity of the ring's stiffness is primarily related to the contact between its boss and internal and external supports. Therefore, when using the FEM to calculate the nonlinear stiffness characteristics of the ring, it is necessary to determine the contact state experimentally, or to verify the contact state established by the FEM through experimental verification.

[0005] Prior art elastic ring stiffness testers typically employ a vertical structure. For example, CN108692925 B discloses a vertical elastic ring stiffness tester. This structure, coupled with the initial gravity load of the test fixture, obscures the nonlinear stiffness characteristics of the elastic ring under certain loads. Furthermore, the placement of the vertical sensor introduces a degree of randomness and uncertainty in the horizontal and vertical relative position between the sensor and the test piece, contributing to unreliable test results. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a horizontal elastic ring nonlinear stiffness testing platform and a testing method.

[0007] The present invention is achieved through the following technical solutions, providing a horizontal elastic ring nonlinear stiffness testing platform, including a base, a measuring module, a test module and a loading module; the test module includes a supporting inner ring fixedly connected to the base and a supporting outer ring sleeved on the outer ring of the supporting inner ring, and the elastic ring is located between the supporting inner ring and the supporting outer ring; the loading module includes a load bracket fixedly connected to the base and a loading screw passing through the load bracket, the loading screw of the load bracket away from the test module is equipped with a loading nut, the loading screw is provided with a polygonal portion, the load bracket is provided with a polygonal hole adapted to the polygonal portion, and the loading screw is connected to the supporting outer ring through a tension sensor; the measuring module includes a displacement sensor installed on the base and a displacement amplifier for amplifying the displacement of the supporting outer ring, and the displacement sensor detects the displacement of the amplifying end of the displacement amplifier.

[0008] The elastic ring is loaded by rotating the loading nut, causing it to deform under force, and the loaded load is detected by a tension sensor; the displacement of the supporting outer ring is amplified by a displacement amplifier and then transmitted to the displacement sensor, thereby improving the detection accuracy.

[0009] As an optimization, the displacement amplifier includes a telescopic rod hinged on the base and a translation slider sliding on the base, the short arm end of the telescopic rod is connected to the supporting outer ring, and the long arm end of the telescopic rod is connected to the translation slider, and the displacement sensor detects the displacement of the translation slider.

[0010] The outer ring of the support moves under force, driving the short arm end of the telescopic rod to swing, so that the long arm end of the telescopic rod swings and drives the translation slider to move. The displacement of the translation slider is detected by the displacement sensor, thereby realizing the amplified measurement of the displacement.

[0011] As an optimization, an extension head is fixedly attached to the side of the outer support ring away from the loading module. This extension head is hinged to the short lever arm end of the telescopic rod, and the long lever arm end of the telescopic rod is hinged to the translation slider. Both the short and long lever arms of the telescopic rod are retractable. In this solution, both ends of the telescopic rod are retractable, and the long lever arm end is hinged to the translation slider, thereby facilitating translation of the translation slider by the telescopic rod.

[0012] As an optimization, the load bracket is connected to the base via bolts, and the bolt holes in the base are elongated holes extending along the axial direction of the loading screw. This elongated hole in the loading screw allows the load bracket to be moved forward and backward to accommodate measurements of elastic rings of varying sizes.

[0013] As an optimization, a positioning groove adapted to the load bracket is provided on the base. The positioning groove in this solution plays a positioning role for the load bracket to prevent left and right movement.

[0014] As an optimization, the supporting inner ring is connected to the base via bolts. In this solution, the supporting inner ring is connected to the base via bolts, which facilitates the replacement of supporting inner rings of different sizes to accommodate elastic rings of different sizes.

[0015] As an optimization, the base is equipped with multiple universal ball bearings that support the outer ring. The universal ball bearings greatly reduce the friction at the bottom of the outer ring and reduce its influence on the test results.

[0016] As an optimization, the cross section of the polygonal portion is a regular hexagon.

[0017] As an optimization, one end of the tension sensor is connected to the loading screw, and the other end is connected to the support outer ring through a steel wire rope. In this solution, the tension sensor is connected to the support outer ring through a steel wire rope, realizing radial pulling loading of the support outer ring.

[0018] A method for testing the nonlinear stiffness of a horizontal elastic ring comprises the following steps: a. loading the elastic ring by rotating a loading nut to cause the ring to deform under stress, and detecting the loading load by a tension sensor;

[0019] b. The outer ring of the support moves under force, driving the short arm end of the telescopic rod to swing, so that the long arm end of the telescopic rod swings and drives the translation slider to move, and the displacement of the translation slider is detected by the displacement sensor;

[0020] c. When the displacement of the supporting outer ring reaches the test design value, record the load and displacement data;

[0021] d. Rotate the elastic ring 60° and measure the next measuring point;

[0022] e. Repeat steps a to d until all six test points are tested.

[0023] The beneficial effects of the present invention are:

[0024] 1. The test device is placed horizontally, which can test the nonlinear stiffness characteristics of the elastic ring in the full deformation range, avoiding the initial gravity influence of the additional test fixture of the vertical elastic ring stiffness test device.

[0025] 2. The loading device, sensor clamping device and test piece with centering and positioning functions ensure the accuracy of the load and displacement test applied to the test piece, effectively eliminating the test deviation caused by the randomness and uncertainty of the relative positions of the sensor, test piece and force loading direction of the vertical elastic ring stiffness test device, thereby improving the accuracy of the elastic ring stiffness test.

[0026] 3. The uniquely designed centering and anti-rotation loading device transmits the force through the cylindrical centering and hexagonal prism anti-rotation loading screw, ensuring the direction of force application and limiting the torque generated by rotational loading, thus ensuring the accuracy and reliability of load measurement.

[0027] 4. The invention amplifies the tiny displacement of the supporting outer ring through a telescopic rod displacement amplifier, which greatly reduces the difficulty of displacement measurement and the requirements for sensor accuracy, saving costs while ensuring accurate measurement.

[0028] 5. The present invention installs two circles of circumferentially evenly distributed universal ball bearing seats at the bottom of the supporting outer ring, which greatly reduces the friction at the bottom of the supporting outer ring and reduces its influence on the test results.

[0029] 6. The present invention processes a horizontal fixing groove at the fixed position of the load bracket, so that the load bracket can be moved forward and backward to adapt to the measurement task of elastic rings of different sizes.

[0030] 7. The present invention utilizes the differential method, that is, the ratio of the change in force to displacement, to obtain the stiffness of the elastic ring being tested, thereby further eliminating the test error caused by friction.

[0031] 8. The present invention reveals the elastic ring's stiffness characteristics in multiple ways. First, the displacement of the supporting outer ring when subjected to force replaces the local deformation of the elastic ring, reflecting the overall stiffness of a specific location on the elastic ring and making the test data more realistic. Second, the use of a stepwise loading and multiple measurement method effectively identifies and eliminates accidental test results. Furthermore, this loading method simultaneously determines both the local and average stiffness characteristics of the elastic ring, making the measurement results more comprehensive and accurate.

[0032] 9. The present invention can apply forces of different sizes and directions to the elastic ring, and by simply replacing the test module, it can test elastic rings of different sizes and matching states. It has simple operation, wide application range and low cost.

[0033] 10. The application of the present invention is not limited to the test of elastic ring stiffness. Through simple design and modification, the stiffness test of elastic supports of aircraft engines with structures such as squirrel cage type, pull rod type and return pull rod type can be carried out. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the structure of the present invention;

[0035] Figure 2 A top view of the present invention;

[0036] Figure 3 It is a front view of the present invention;

[0037] Figure 4For the present invention Figure 2 Middle AA plane section view;

[0038] Figure 5 For the present invention Figure 2 Middle BB plane cross-sectional view;

[0039] Figure 6 This is a schematic structural diagram of the loading screw of the present invention;

[0040] Figure 7 Schematic diagram of different measuring points of the present invention;

[0041] Figure 8 Schematic diagram of the testing method of the present invention;

[0042] Figure 9 This is a diagram showing the principle of displacement amplification of the present invention;

[0043] As shown in the figure:

[0044] 1. Displacement amplifier, 2. Sensor support, 3. Displacement sensor, 4. Support inner ring, 5. Support outer ring, 6. Wire rope, 7. Tension sensor, 8. Load bracket, 9. Universal ball bearing, 10. Base, 11. Loading screw, 12. Loading nut, 13. Washer, 14. Telescopic rod, 15. Translation slider, 16. Slide rail, 17. Elastic ring, 18. Fulcrum, 19. Extension head. DETAILED DESCRIPTION

[0045] In order to clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods.

[0046] like Figures 1 to 9 As shown, a horizontal elastic ring nonlinear stiffness testing platform of the present invention includes a base 10, a measurement module, a test module and a loading module; the base 10 is a horizontal plate fixed to the test bench by bolts.

[0047] The test module includes a supporting inner ring 4 fixed to a base 10 and a supporting outer ring 5 sleeved on the outer ring of the supporting inner ring 4. The supporting inner ring 4 is connected to the base 10 by bolts, which facilitates the replacement of supporting inner rings of different sizes to adapt to elastic rings of different sizes.

[0048] The elastic ring 17 is located between the supporting inner ring 4 and the supporting outer ring 5 ; specifically, the elastic ring 17 is sleeved outside the supporting inner ring 4 , and the supporting outer ring 5 is sleeved outside the elastic ring 17 to be measured.

[0049] In order to reduce the friction between the outer support ring 5 and the base 10, a plurality of universal ball bearing seats 9 are mounted on the base 10 to support the outer ring 5. In this embodiment, the universal ball bearing seats 9 are provided in two circles and are evenly distributed circumferentially.

[0050] The loading module includes a loading bracket 8 fixed to a base 10 and a loading screw 11 passing through the loading bracket 8 , wherein an axis extension line of the loading screw 11 passes through the center of the elastic ring 17 to be tested.

[0051] A loading nut 12 is mounted on the loading screw 11 of the load bracket 8 at the side away from the test module, and a washer 13 is mounted between the loading nut 12 and the load bracket 8 .

[0052] In order to prevent the loading screw 11 from rotating with the loading nut 12, causing the direction of the force to be deflected and generating torque, the loading screw 11 is provided with a polygonal portion, and the load bracket 8 is provided with a polygonal hole adapted to the polygonal portion. In this embodiment, the cross-section of the polygonal portion is a regular hexagon.

[0053] The loading screw 11 is connected to the supporting outer ring 5 through the tension sensor 7 ; in this embodiment, one end of the tension sensor 7 is connected to the loading screw 11 , and the other end is connected to the supporting outer ring 5 through the wire rope 6 .

[0054] The load bracket 8 is connected to the base 10 by bolts, and the bolt through hole on the base 10 is a long hole extending along the axial direction of the loading screw 11, so that the load bracket can be moved back and forth and fixed to adapt to the measurement tasks of elastic rings of different sizes.

[0055] The base 10 is provided with a positioning groove adapted to the load bracket 8 . The load bracket 8 can move forward and backward in the positioning groove, but cannot move left and right.

[0056] The measuring module includes a displacement sensor 3 mounted on a base 10 and a displacement amplifier 1 for amplifying the displacement of the supporting outer ring 5 . The displacement sensor 3 detects the displacement of the amplifying end of the displacement amplifier 1 .

[0057] The displacement sensor 3 is used to detect the radial displacement of the supporting outer ring 5 under loading. Since the single-step loading displacement of the supporting outer ring 5 is only about 0.01 mm, the requirements for the sensor and the test environment are extremely high, and the measurement is difficult. A displacement amplifier 1 is designed in the present invention, and the displacement sensor 3 is connected to the supporting outer ring 5 through the displacement amplifier 1.

[0058] The displacement amplifier 1 includes a telescopic rod 14 hinged on a base 10 and a translation slider 15 slidably connected to the base 10 . The translation slider 15 is slidably connected to a slide rail 16 so that the translation slider 15 can slide parallel to the loading direction.

[0059] The short arm end and the long arm end of the telescopic rod 14 are both telescopic ends. In order to realize the articulation of the telescopic rod 14, a fulcrum 18 is provided on the base 10. The telescopic rod 14 is connected to the fulcrum 18 along the vertical articulation axis. The telescopic rod 14 can rotate in a plane around the fulcrum 18.

[0060] The short arm end of the telescopic rod 14 is connected to the supporting outer ring 5, and the long arm end of the telescopic rod 14 is connected to the translation slider 15. The displacement sensor 3 is installed on the sensor support 2. The translation slider 15 is the amplifying end of the displacement amplifier 1. The displacement sensor 3 detects the displacement of the translation slider 15.

[0061] In this embodiment, an extension head 19 is fixedly connected to the side of the supporting outer ring 5 away from the loading module, and the extension head 19 is hinged to the short lever arm end of the telescopic rod 14 .

[0062] The long arm end of the telescopic rod 14 is hinged to the translation slider 15 .

[0063] The present invention drives the loading screw 11 with a special structure by rotating the loading nut 12, and transmits the load through the tension sensor 7, the wire rope 6 and the supporting outer ring 5, and finally loads it on the elastic ring 17. The tension sensor 7 is used to accurately test the magnitude of the radial force. The displacement of the supporting outer ring 5 is transmitted to the translation slider 15 through the displacement amplifier 1. The displacement size s0 of the translation slider 15 can be measured using the displacement sensor 3. Then, the displacement size s of the supporting outer ring 5 along the load direction after being loaded is calculated using formula (1), which represents the deformation of the elastic ring 17 being measured on the line connecting the force sensor 7 and the displacement sensor 3.

[0064]

[0065] Knowing the force and the deformation in the direction of the force, the stiffness of the elastic ring 17 to be tested can be obtained according to the testing principle of the stiffness of the elastic ring: a force of magnitude F is applied radially to the elastic ring 17 to be tested, and the displacement of the outer ring of the support at this position under this force is s. According to formula (2), the stiffness K of the elastic ring 17 to be tested can be obtained.

[0066]

[0067] By rotating the elastic ring 17 to be tested, the deformation conditions at different positions of the elastic ring 17 can be tested. i , i=1,2,…,n is the measurement point number, such as Figure 9 As shown, in the embodiment of the present invention, 6 measuring points are evenly taken along the circumference. The local stiffness K at different positions of the elastic ring 17 can be calculated by formula (2): i .

[0068]

[0069] By averaging the local stiffness at each position, the average stiffness K0 of the elastic ring 17 under test can be obtained, that is,

[0070]

[0071] Wherein, n is the number of measurement points, and in the embodiment of the present invention, n=6.

[0072] Taking into account the influence of friction, the present invention uses the differential method, that is, the ratio of the change in force to displacement, to obtain the stiffness K of the elastic ring 17 to be tested, that is,

[0073]

[0074] Where, ΔF is the change in force, and Δs is the change in displacement.

[0075] A method for testing the nonlinear stiffness of a horizontal elastic ring comprises the following steps:

[0076] Step S11: Design and manufacture the platform components such as the elastic ring 17, the supporting outer ring 5 and the supporting inner ring 4 to be used in the test.

[0077] Step S12: measuring the diameters of the elastic ring 17, the supporting outer ring 5 and the supporting inner ring 4 to preliminarily determine the matching state of the test device.

[0078] Step S13: Check whether the component processing dimensions meet the requirements, and reprocess the components that do not meet the requirements.

[0079] Step S14: Assemble the test platform as described above.

[0080] Step S15: Measure the fit between the inner and outer bosses of the elastic ring 17 and the inner and outer support rings. If a clearance fit is achieved, measure the clearance at the bosses directly. If an interference fit is achieved, measure the clearance at the elastic portion of the ring between the bosses and subtract the clearance from the boss height to determine the interference fit.

[0081] Step S16: Before the test officially begins, the tension sensor 7 and the displacement sensor 3 are zeroed respectively, and the gain of the tension sensor 7 is set according to the equipment instructions.

[0082] Step S17: Check the sensor zeroing result to ensure that the error is within an acceptable range.

[0083] Step S18: Load the elastic ring 17 by rotating the loading nut 12 so that the elastic ring 17 is deformed by the force, and the loading load is detected by the tension sensor.

[0084] Step S19: Observe the deformation of the elastic ring 17 and the size of the added load, that is, the readings of the displacement sensor 3 and the tension sensor 7. Do not let the size exceed the sensor range.

[0085] Step S20: The supporting outer ring moves under force, driving the short arm end of the telescopic rod to swing, so that the long arm end of the telescopic rod swings and drives the translation slider to move. The displacement of the translation slider is detected by the displacement sensor. When the displacement of the supporting outer ring 5 reaches the test design value, the load and displacement data are recorded.

[0086] Step S21: Rotate the elastic ring 17 by 60° and repeat the measurement of steps S14 to S20 for the next measuring point.

[0087] Step S22: Repeat steps S14 to S21 until all six test points have completed testing.

[0088] Step S23: Process the test data and obtain the local stiffness and average stiffness of the elastic ring 17 according to the above formula.

[0089] Of course, the above description is not limited to the above examples. Technical features not described in the present invention can be achieved by or by adopting existing technologies, which will not be described here. The above embodiments and drawings are only used to illustrate the technical solutions of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation methods. Ordinary technicians in this field should understand that changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not depart from the purpose of the present invention and should also fall within the scope of protection of the claims of the present invention.

Claims

1. A horizontal elastic ring nonlinear stiffness testing platform, characterized by: It includes a base (10), a measuring module, a test module and a loading module; The test module comprises a supporting inner ring (4) fixed to a base (10) and a supporting outer ring (5) sleeved on the outer ring of the supporting inner ring (4), and an elastic ring (17) is located between the supporting inner ring (4) and the supporting outer ring (5); The loading module comprises a load bracket (8) fixed to a base (10) and a loading screw (11) passing through the load bracket (8); a loading nut (12) is mounted on the loading screw (11) on the side of the load bracket (8) away from the test module; a polygonal portion is provided on the loading screw (11); a polygonal hole adapted to the polygonal portion is opened on the load bracket (8); and the loading screw (11) is connected to the supporting outer ring (5) via a tension sensor (7); The measuring module comprises a displacement sensor (3) mounted on a base (10) and a displacement amplifier (1) for amplifying the displacement of the supporting outer ring (5), wherein the displacement sensor (3) detects the displacement of the amplifying end of the displacement amplifier (1).

2. The horizontal elastic ring nonlinear stiffness testing platform according to claim 1, characterized in that: The displacement amplifier (1) comprises a telescopic rod (14) hinged on a base (10) and a translation slider (15) slidably connected to the base (10), wherein the short lever arm end of the telescopic rod (14) is connected to the supporting outer ring (5), and the long lever arm end of the telescopic rod (14) is connected to the translation slider (15), and the displacement sensor (3) detects the displacement of the translation slider (15).

3. The horizontal elastic ring nonlinear stiffness testing platform according to claim 2, characterized in that: An extension head (19) is fixedly connected to the side of the supporting outer ring (5) away from the loading module. The extension head (19) is hinged to the short arm end of the telescopic rod (14). The long arm end of the telescopic rod (14) is hinged to the translation slider (15). Both the short arm end and the long arm end of the telescopic rod (14) are telescopic ends.

4. The horizontal elastic ring nonlinear stiffness testing platform according to claim 1, characterized in that: The load bracket (8) is connected to the base (10) via bolts, and the bolt through hole on the base (10) is a long hole extending in the axial direction of the loading screw rod (11).

5. The horizontal elastic ring nonlinear stiffness testing platform according to claim 1, characterized in that: The base (10) is provided with a positioning groove adapted to the load bracket (8).

6. The horizontal elastic ring nonlinear stiffness testing platform according to claim 1, characterized in that: The supporting inner ring (4) is connected to the base (10) via bolts.

7. The horizontal elastic ring nonlinear stiffness testing platform according to claim 1, characterized in that: The base (10) is provided with a plurality of universal ball bearing seats (9) for supporting the outer ring (5).

8. The horizontal elastic ring nonlinear stiffness testing platform according to claim 1, characterized in that: The cross section of the polygonal portion is a regular hexagon.

9. The horizontal elastic ring nonlinear stiffness testing platform according to claim 1, characterized in that: One end of the tension sensor (7) is connected to the loading screw (11), and the other end is connected to the supporting outer ring (5) via a steel wire rope (6).

10. A method for testing the nonlinear stiffness of a horizontal elastic ring using the test platform according to claim 2, characterized in that: The steps include: a. Loading the elastic ring (17) by rotating the loading nut (12) to deform the elastic ring under stress, and detecting the loading load by the tension sensor (7); b. The supporting outer ring (5) is forced to move, driving the short arm end of the telescopic rod (14) to swing, so that the long arm end of the telescopic rod (14) swings and drives the translation slider (15) to move, and the displacement of the translation slider (15) is detected by the displacement sensor (3); c. Record the load and displacement data when the displacement of the supporting outer ring (5) reaches the test design value; d. Rotate the elastic ring (17) by 60° and measure the next measuring point; e. Repeat steps a to d until all six test points are tested.

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