Floating spline rigidity damping parameter identification device and identification method

Abstract

The invention belongs to the field of aerospace transmission, and discloses a floating spline rigidity damping parameter identification device and identification method. The recognition device comprises a fixed support, a floating spline test piece, a supporting bearing seat, a rotating shaft and a torque loading system. The inner spline shaft and the outer spline shaft are rigidly connected through an expansion sleeve and a connecting disc and achieve spline meshing, the outer spline shaft is connected with a rotating shaft through a diaphragm coupling, and the rotating shaft is provided with a balance weight disc, a bearing and a positioning clamp spring and connected with a torque measuring instrument. The torque increasing shaft is connected with a torque measuring instrument through a diaphragm coupling, and loading torque is applied by a bidirectionally symmetrical spring force arm system, so that controllable loading is realized. The device is provided with an acceleration sensor to collect axial and radial vibration signals, and excitation can be applied through the horizontal and vertical vibration exciters. The floating spline rigidity damping parameter identification device and the identification method have the advantages of simple structure and simple and convenient implementation mode, and are high in repeatability and high in identification precision.

Description

Technical Field

[0001] The invention belongs to the field of aerospace transmission and relates to a floating spline stiffness and damping parameter identification device and an identification method. Background Art

[0002] Helicopter tail drive shafting suffers from weak tail boom stiffness, leading to support deformation and axial and radial fluctuations at the connection points. Therefore, floating splines combined with diaphragm couplings are commonly used to enhance tail drive shafting stability and reliability. Grease lubrication is commonly used in helicopter tail drive shafts. However, after a certain number of service cycles, the grease dries out and thins out due to centrifugal stress and frictional heat generation, resulting in poor lubrication. This causes fretting wear on the splines, altering the tooth surface topography and contact conditions, leading to significant changes in spline contact stiffness and damping. This change in spline contact stiffness can alter the critical speed of the shafting. When the shafting operating speed exceeds the critical speed, deteriorating lubrication can increase the friction damping within the spline pair, further inducing rotor instability and the so-called low-frequency synchronous vortex phenomenon. This phenomenon results in high shafting amplitude and high low-frequency vibration energy, potentially leading to serious accidents. Therefore, accurately identifying floating spline contact stiffness and friction damping is a prerequisite for floating spline design and the dynamics of helicopter tail drive shafting.

[0003] In the study of mechanical interface contact characteristics, many researchers have used finite element simulation to model and simulate spline contact stiffness, and combined this with direct stiffness testing for verification. However, research on spline friction damping is very limited, with the only available research focusing on deriving the energy dissipation of spline friction damping and obtaining an equivalent friction damping coefficient, and failing to achieve quantitative experimental verification. Therefore, it is necessary to design a floating spline stiffness and damping parameter identification device and identification method to achieve the combined identification of floating spline contact stiffness and friction damping. Summary of the Invention

[0004] Aiming at the deficiencies of existing spline contact stiffness and spline friction damping test devices and methods, the present invention proposes a floating spline stiffness and damping parameter identification device.

[0005] The technical solution of the present invention:

[0006] A floating spline stiffness and damping parameter identification device, the floating spline stiffness and damping parameter identification device includes a fixed constraint support 1, a flange shaft 2, a connecting disc 3, an expansion sleeve 4, an inner spline shaft 5, an outer spline shaft 6, a first diaphragm coupling 7, a rotating shaft 8, an expansion sleeve, a counterweight disc, an exciter fixture 11, a horizontal exciter 12, a horizontal exciter support 13, a vertical exciter 14, a vertical exciter support 15, a support bearing seat 18, a support bearing 19, an elastic ring 20, a retaining spring 21, a support bearing seat pressure cover 22, a second diaphragm coupling 7, a rotating shaft 8, a ... retaining sleeve, a counterweight disc, a vibrator fixture 11, a horizontal exciter 12, a horizontal exciter support 13, a vertical exciter 14, a vertical exciter support 15, a support bearing seat 18, a support bearing 19, a elastic ring 20, a retaining spring 21, a support bearing seat pressure cover 22, a second diaphragm coupling 7, a rotating shaft Shaft 23, torque measuring instrument 24, torque measuring instrument support 25, third diaphragm coupling 26, torsion shaft 27, torsion shaft support bearing seat 28, support bearing 29, torsion shaft support bearing seat gland 30, torsion arm 31, force bolt, spacer, upper spring support 34, force spring, lower spring support 38, acceleration sensor, industrial computer 44, dynamic data acquisition instrument 45, eddy current displacement amplifier 46, eddy current displacement sensor, signal generator 51, power amplifier 52, controller 53 and cast iron platform 54;

[0007] The fixed constraint support 1, the horizontal exciter support 13, the vertical exciter support 15, the support bearing seat 18, the torque measuring instrument support 25, the torsion shaft support bearing seat 28, the upper spring support 34 and the lower spring support 38 are fixed on the cast iron platform 54 at a certain distance; the fixed constraint support 1 is rigidly connected to the flanged shaft 2; one end of the internal spline shaft 5 is rigidly fixed to the flanged shaft 2 and the connecting disc 3 through the expansion sleeve 4, and the other end is engaged with one end of the external spline shaft 6 through the spline; the other end of the external spline shaft 6 is connected to one end of the rotating shaft 8 through the first diaphragm coupling 7, and the counterweight disc is rigidly fixed on the rotating shaft 8 by two expansion sleeves; the other end of the rotating shaft 8 is fitted with a support bearing 19 and an elastic ring 20, and is installed in the support bearing seat 18 for support, and the support bearing seat pressure cover 22 is fixed to the end face of the support bearing seat 18 to limit the axial displacement of the outer ring of the support bearing 19, and at the same time, a card is installed on the rotating shaft 8 The spring 21 positions the support bearing 19 and is connected to the left end of the shaft where the torque measuring instrument 24 is located through the second diaphragm coupling 23; the bottom of the torque measuring instrument 24 is fixed to the torque measuring instrument support 25, and the right end of the shaft where the torque measuring instrument 24 is located is connected to the left end of the torsion shaft 27 through the third diaphragm coupling 26 to realize real-time and precise control of the loading torque; the torsion shaft 27 is fitted with a support bearing 29 and installed in the torsion shaft support bearing seat 28 for support, and the torsion shaft support bearing seat pressure cover 30 is fixed to the end face of the torsion shaft support bearing seat 28 to limit the axial displacement of the outer ring of the support bearing 29; the right end of the torsion shaft 27 is tightly matched with the torque arm 31, and the torque arm 31 has symmetrically arranged force bolts, pads and force springs at both ends for applying two forces of equal size and opposite direction to the torque arm 31, thereby applying torque to the entire structure; the force bolts and force springs are fixed on the two spring supports;

[0008] Four acceleration sensors 40 to 43 arranged horizontally and vertically between the inner spline shaft 5 and the rotating shaft 8 are connected to a dynamic data acquisition instrument 45 and an industrial control computer 44 to measure the vibration acceleration of the structure; four eddy current displacement sensors arranged horizontally and vertically between the outer spline shaft 6 and the rotating shaft 8 are connected to an eddy current displacement amplifier 46, a dynamic data acquisition instrument 45, and an industrial control computer 44 to measure and control the axis trajectory;

[0009] When conducting the dynamic response test required for damping identification, the horizontal exciter 12 is fixed to the horizontal exciter support 13, and the vertical exciter 14 is fixed to the vertical exciter support 15. The horizontal and vertical exciters are connected to the rotating shaft 8 through the exciter clamp 11. The controller 53, the signal generator 51, and the power amplifier 52 together constitute an exciter control system, which controls the horizontal and vertical exciters to apply excitation to the floating spline stiffness damping parameter identification device. When conducting the inherent characteristic test required for stiffness identification, there is no need to install the horizontal and vertical exciters.

[0010] A method for identifying contact stiffness of a spline connection structure, characterized by comprising the following steps:

[0011] Step 1: Build a floating spline stiffness and damping parameter identification device; first, do not install the horizontal and vertical exciters to perform inherent characteristics tests;

[0012] Step 2: Use two force-adding bolts and two force-adding springs to apply forces of equal magnitude and opposite directions to the torque-adding arm 31, thereby applying a torque load T to the floating spline stiffness and damping parameter identification device. The torque load T is accurately monitored and controlled in real time by the torque measuring instrument 24;

[0013] Step 3: After the torque load T is applied, wait until the state of the floating spline stiffness and damping parameter identification device is stable, and use a hammer to hammer different positions on one end of the rotating shaft 8;

[0014] Step 4: Obtain the acceleration response signal of the floating spline stiffness and damping parameter identification device corresponding to the torque load T according to the acceleration sensor and the industrial computer 44;

[0015] Step 5: Apply a gradually increasing torque load T. Repeat step 4 after each loading to obtain the acceleration response signal of the floating spline stiffness and damping parameter identification device corresponding to the loading torque T. max Then gradually uninstall;

[0016] Step 6: After unloading, fix the horizontal and vertical vibrators to the horizontal vibrator support 13 and the vertical vibrator support 15 respectively with bolts, and install the vibrator fixture 11 to connect the horizontal and vertical vibrators to the rotating shaft 8 for dynamic response testing;

[0017] Step 7: Repeat step 2 and apply a torque load T of the same magnitude. Use the controller 53, signal generator 51, and power amplifier 52 to control the horizontal and vertical exciters to apply sinusoidal excitation in the horizontal and vertical directions to the floating spline stiffness and damping parameter identification device. The sweep frequency range is selected to be 20-100 Hz, and the excitation amplitude is set to 2.5 V. The vibration acceleration signal of the spline and the rotating shaft 8 is transmitted to the industrial computer 44 via the acceleration sensor and the dynamic data acquisition instrument 45 to obtain the acceleration response signal of the floating spline structure corresponding to the torque T.

[0018] Step 8: Gradually increase the applied torque T. Each loading is the same as the torque T corresponding to step 5. After each loading, repeat step 7 to obtain the acceleration response signal of the floating spline structure under the loading torque T. When the maximum torque T is reached, max After that, gradually uninstall and complete all tests;

[0019] Step 9: Floating spline contact stiffness identification method:

[0020] S9.1 Define the squared error function between the intrinsic characteristic test results and the simulation model modal results:

[0021]

[0022] in, are the natural frequencies of each order under the action of a specific torque in the inherent characteristics test of the spline connection structure, is the modal frequency of each order obtained by finite element model simulation based on thin layer element method, η i is the weight ratio of each order natural frequency measured in the test, which indicates the sensitivity of each order natural frequency to torque changes and is defined as:

[0023]

[0024] S9.2 Use MATLAB software to find the elastic modulus value that minimizes R(N) by the formula h is the thickness of the thin layer element, and the contact stiffness per unit area of ​​the floating spline contact surface corresponding to different torque loads is identified;

[0025] Step 10: Identification method of floating spline friction damping:

[0026] S10.1 Establish a finite element model of a damped thin-layer unit and perform dynamic response simulation considering the influence of damping. Use MATLAB software to fit the dynamic response simulation results and establish a functional relationship between the damping ratio and the response amplitude.

[0027] S10.2 The acceleration response amplitude measured in the dynamic response test is substituted into the fitting formula to inversely deduce the equivalent damping ratio of the thin layer material matched with the corresponding test torque, and the friction damping of the floating spline contact surface corresponding to different torque loads is identified.

[0028] The floating spline contact stiffness identification method, the identification principle is: through the force bolts, pads and force springs symmetrically arranged at both ends of the torque arm 31, two forces of the same size and opposite directions are applied to the torque arm 31 to complete the application of the torque load T of the spline connection structure; after the state of the whole structure is stable, different positions of one end of the shaft 8 are hammered using a force hammer, and the acceleration response signal of the floating spline structure corresponding to the torque T is obtained according to the acceleration sensors 40-43, the dynamic data acquisition instrument 45 and the industrial computer 44; the torque load T is gradually increased, and the acceleration response signal of the floating spline structure corresponding to the loading torque T can be obtained after each loading, and the maximum torque T max is reached, then the torque load T is gradually unloaded; finally, the variation law of the natural frequency of the spline connection structure and the variation law of the vibration characteristic under different torque loads T are obtained, and the contact stiffness of the spline connection structure is inversely deduced according to the relationship between the torque load T and the vibration frequency and in combination with the finite element analysis.

[0029] The floating spline friction damping identification method, the identification principle is: the horizontal and vertical exciters 12, 14 are fixed on the horizontal exciter support 13 and the vertical exciter support 15 respectively through bolts, and the exciter clamp 11 is installed to connect the horizontal and vertical exciters 12, 14 with the shaft 8 for dynamic response test; through the force bolts, pads and force springs symmetrically arranged at both ends of the torque arm 31, two forces of the same size and opposite directions are applied to the torque arm 31 to complete the application of the torque load T of the spline connection structure; after the state of the whole structure is stable, the controller 54, the signal generator 51 and the power amplifier 52 are used to control the horizontal and vertical exciters 12, 14 to apply horizontal and vertical sinusoidal excitations to the structure, the sweep frequency range is selected as 20-100Hz, the excitation amplitude is set as 2.5V, the corresponding excitation force size at this time is 18N which is calibrated in advance using a force sensor, the spline and shaft vibration acceleration signals are transmitted to the industrial computer 44 through the acceleration sensors 40-43 and the dynamic data acquisition instrument 45 to obtain the acceleration response signal of the floating spline structure corresponding to the torque T; the applied torque T is gradually increased, and the acceleration response signal of the floating spline structure corresponding to the loading torque T can be obtained after each loading; the maximum torque T maxAfter that, all tests were completed by gradually unloading; a finite element model of a damped thin-layer unit was established, and a dynamic response simulation considering the influence of damping was carried out. The dynamic response simulation results were fitted using MATLAB software, and a functional relationship between the damping ratio and the response amplitude was established; the acceleration response amplitude measured in the dynamic response test was substituted into the fitting formula, and the equivalent damping ratio of the thin-layer material that matched the corresponding test torque was inferred, and the friction damping of the floating spline contact surface corresponding to different torque loads was identified.

[0030] Beneficial effects of the present invention:

[0031] (1) Realize floating simulation of spline connection and convenient disassembly and assembly of spline test pieces: the internal / external spline test pieces are rigidly connected to the rotating shaft 8 through the expansion sleeve 4, and the internal / external spline test pieces are connected to the other section of the rotating shaft through the first diaphragm coupling 7, which is convenient for test piece replacement; at the same time, the radial and axial degrees of freedom of the spline are floating.

[0032] (2) The simulation of the vortex motion of the spline in the radial direction in the non-rotating state is realized: through the horizontal exciter 12 and the vertical exciter 14 in two directions with an angle of 90°, combined with the power amplifier 52 and the signal generator 51, the vibration frequency, amplitude and phase in the two directions are controlled. In the non-rotating state, the simulation of the radial vortex axis trajectory of the spline is realized, and the relative motion and friction and wear state between the inner and outer splines are revealed. In combination with the first diaphragm coupling 7, the system is given the ability to float axially freely, and the multi-dimensional motion state of the spline in actual operation is fully reproduced.

[0033] (3) The resonance frequency of the spline shaft system is adjustable: the resonance frequency of the spline shaft system is controlled by changing the wheel mass, diaphragm coupling stiffness, shaft diameter, and support stiffness, simulating the critical speed of the actual helicopter tail shaft.

[0034] (4) While applying a quantitative torque to the spline, the support boundary conditions of the shaft system are quantified: a controllable torque loading system is constructed to ensure that the constraint boundary conditions are clear while applying the torque; the loading arm is equipped with a double spring structure with a constant stiffness and adjustable torque, and precise stiffness control is achieved by replacing the spring; the support end uses an elastic ring with a known small stiffness in series with the rolling bearing to construct a support boundary with a known stiffness, avoiding the problem of traditional rolling bearings with large stiffness and stiffness uncertainty caused by changes in load, clearance and direction;

[0035] In summary, the floating spline stiffness and damping parameter identification device and identification method of the present invention provide good boundary conditions and excitation conditions for spline stiffness and damping identification, support the reproduction of spline self-excited vibration behavior and the identification of stiffness and damping parameters. In addition, it has the ability to operate stably for a long time, and can realize the testing of torque, amplitude, and misalignment spline wear under quantitative boundary conditions, providing accurate data for spline wear model verification. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a floating spline stiffness and damping identification device;

[0037] Figure 2 This is a partial enlarged view of the connection structure of the internal / external spline test piece;

[0038] Figure 3 is the support bearing seat, which is used to construct the support boundary with known stiffness;

[0039] Figure 4 It is a torsion shaft support bearing seat;

[0040] Figure 5 is the contact stiffness per unit area diagram of the spline identified under different torque loads;

[0041] Figure 6 is the curve of resonance response changing with the damping ratio of thin-layer unit under different torques;

[0042] Figure 7 It is the amplitude-frequency response curve of the X-axis measuring point of the floating spline in the test;

[0043] Figure 8 The friction damping diagram of the floating spline contact interface is identified under different torque loads.

[0044] In the figure: 1 fixed constraint support, 2 flanged shaft, 3 connecting disc, 4 expansion sleeve, 5 internal spline shaft, 6 external spline shaft, 7 first diaphragm coupling, 8 rotating shaft, 9 expansion sleeve, 10 counterweight disc, 11 exciter fixture, 12 horizontal exciter, 13 horizontal exciter support, 14 vertical exciter, 15 vertical exciter support, 16 expansion sleeve, 17 counterweight disc, 18 support bearing seat, 19 support bearing, 20 elastic ring, 21 retaining ring, 22 support bearing seat cover, 23 second diaphragm coupling, 24 torque measuring instrument, 25 torque measuring instrument support, 26 third diaphragm coupling, 27 torsion shaft, 28 torsion shaft support bearing seat, 29 support bearing, 30 torsion shaft support Support bearing seat cover, 31 torque arm, 32 upper force bolt, 33 spacer, 34 upper spring support, 35 upper force spring, 36 lower force bolt, 37 spacer, 38 lower spring support, 39 lower force spring, 40 first acceleration sensor, 41 second acceleration sensor, 42 third acceleration sensor, 43 fourth acceleration sensor, 44 industrial computer, 45 dynamic data acquisition instrument, 46 eddy current displacement amplifier, 47-50 eddy current displacement sensor, 48 second eddy current displacement sensor, 49 third eddy current displacement sensor, 50 fourth eddy current displacement sensor, 51 signal generator, 52 power amplifier, 53 cast iron platform, 54 controller. DETAILED DESCRIPTION

[0045] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0046] like Figure 1 As shown, the floating spline stiffness and damping identification device of the present invention includes a fixed constraint support 1, a flange shaft 2, a connecting disc 3, an expansion sleeve 4, an inner spline shaft 5, an outer spline shaft 6, a first diaphragm coupling 7, a rotating shaft 8, an expansion sleeve, a counterweight disc, an exciter fixture 11, a horizontal exciter 12, a horizontal exciter support 13, a vertical exciter 14, a vertical exciter support 15, a support bearing seat 18, a support bearing 19, an elastic ring 20, a retaining spring 21, a support bearing seat cover 22, a second diaphragm coupling 23, Torque measuring instrument 24, torque measuring instrument support 25, third diaphragm coupling 26, torsion shaft 27, torsion shaft support bearing seat 28, support bearing 29, torsion shaft support bearing seat gland 30, torque arm 31, force bolt, spacer, upper spring support 34, force spring, lower spring support 38, acceleration sensor, industrial computer 44, dynamic data acquisition instrument 45, eddy current displacement amplifier 46, eddy current displacement sensor, signal generator 51, power amplifier 52, controller 53 and cast iron platform 54;

[0047] The specific implementation process is as follows:

[0048] 1) Assemble a floating spline stiffness and damping parameter identification device; first, do not install the horizontal vibrator 12 and the vertical vibrator 14 to perform an inherent characteristic test;

[0049] 2) Two forces of equal magnitude and opposite directions are applied to the torque arm 31 by means of the symmetrically arranged force bolts, spacers, and force springs at both ends of the torque arm 31, thereby applying a torque load T to the entire device. T can be accurately monitored and controlled in real time by the torque measuring instrument 24;

[0050] 3) After the torque T is applied, wait until the entire structure is stable and use a hammer to hit different positions on one end of the shaft 8;

[0051] 4) Obtaining the acceleration response signal of the floating spline structure corresponding to the torque T according to the acceleration sensor and the industrial computer 44;

[0052] 5) Apply a gradually increasing torque load T, and repeat step 4 after each loading to obtain the acceleration response signal of the floating spline structure corresponding to the loading torque T, until the maximum torque T is reached. max Then gradually uninstall;

[0053] 6) After unloading, the horizontal vibrator 12 and the vertical vibrator 14 are fixed to the horizontal vibrator support 13 and the vertical vibrator support 15 respectively by bolts, and the vibrator fixture 11 is installed to connect the horizontal vibrator 12 and the vertical vibrator 14 to the rotating shaft 8 for dynamic response testing;

[0054] 7) Repeat step 2) and apply the same magnitude of torque T. Use the signal generator 51 and the power amplifier 52 to control the horizontal exciter 12 and the vertical exciter 14 to apply sinusoidal excitation to the structure in the horizontal and vertical directions. The sweep frequency range is selected to be 20-100 Hz, and the excitation amplitude is set to 2.5 V. The corresponding excitation force at this time is 18 N after calibration using the force sensor in advance. The spline and shaft vibration acceleration signals are transmitted to the industrial computer 44 via the acceleration sensor and the dynamic data acquisition instrument 45 to obtain the acceleration response signal of the floating spline structure under the torque T.

[0055] 8) Gradually increase the applied torque T, each loading is the same as the torque T corresponding to step 5), and repeat step 7) after each loading to obtain the acceleration response signal of the floating spline structure corresponding to the loading torque T; reach the maximum torque T max After that, gradually uninstall and complete all tests;

[0056] 9) Floating spline contact stiffness identification method:

[0057] ① Define the square error function between the inherent characteristic test results and the simulation model modal results:

[0058]

[0059] in, are the natural frequencies of each order under the action of a specific torque in the inherent characteristics test of the spline connection structure, is the modal frequency of each order obtained by finite element model simulation based on the thin layer element method, ηi is the weight ratio of each order natural frequency measured by the experiment, which indicates the sensitivity of each order natural frequency to torque changes and is defined as:

[0060]

[0061] ②Use MATLAB software to find the elastic modulus value that minimizes RN, and use the formula h is the thickness of the thin layer element, and the contact stiffness per unit area of ​​the floating spline contact surface corresponding to different torque loads is identified.

[0062] 10) Identification method of floating spline friction damping:

[0063] ① Establish a finite element model of a thin layer unit with damping, perform dynamic response simulation considering the influence of damping, use MATLAB software to fit the dynamic response simulation results, and establish the functional relationship between the damping ratio and the response amplitude;

[0064] ②Substitute the acceleration response amplitude measured in the dynamic response test into the fitting formula, inversely deduce the equivalent damping ratio of the thin layer material that matches the corresponding test torque, and identify the friction damping of the floating spline contact surface corresponding to different torque loads

[0065] The present invention takes the stiffness and damping identification of a floating spline as an example, and the specific implementation steps are as follows:

[0066] 1) Test of inherent characteristics of a floating spline structure:

[0067] 1.1) Complete the assembly and debugging of the test bench according to the design drawings, ensure that each test piece is installed in the center, and reduce the measurement error caused by assembly deviation;

[0068] 1.2) According to Figure 1 Arrange the acceleration sensor at the position shown and connect it to the DASP acquisition system. Complete the relevant parameter settings in the acquisition software to ensure the accuracy and stability of data acquisition.

[0069] 1.3) Two testers will work together to operate the force-adding bolts and accurately apply the torque load according to the real-time readings of the torque measuring instrument to ensure that the torque loading is uniform and consistent at each stage to improve the repeatability of the test results;

[0070] 1.4) After torque loading is complete and the system reaches a stable state, tap the shaft at multiple locations and record the peak positions of each natural frequency in the FFT spectrum. To reduce accidental errors and ensure data reliability, apply torque increments from 0 Nm to 150 Nm to ensure the stability of the results.

[0071] 2) Simulation of inherent characteristics of floating spline structure based on thin layer element method;

[0072] 2.1) According to Figure 1 Establish a finite element model of the spline structure and simplify the model part reasonably;

[0073] 2.2) Simplify the key tooth structure in contact between the external spline shaft 6 and the internal spline shaft 5 into an annular thin layer unit. The thickness of the thin layer unit is designed to be 0.5 mm. The middle radius of the annular ring is the spline pitch radius. The density and Poisson's ratio of the thin layer unit are consistent with those of the external spline shaft 6.

[0074] 2.3) Import the finite element model of the spline connection structure containing thin-layer elements into the simulation software, set the contact mode and boundary conditions, and keep the boundary conditions consistent with the test conditions;

[0075] 2.4) Perform modal analysis on the spline connection structure. By correcting the elastic modulus of the thin-layer elements, the simulation results are continuously approached to the experimentally measured natural frequencies of the spline connection structure. When the difference between the simulation results and the experimental results is minimized, the correct elastic modulus of the thin-layer elements and the corresponding first- and second-order natural frequencies are obtained, and the relationship between different elastic moduli and natural frequencies is then determined.

[0076] 3) Identification of contact stiffness of a floating spline structure;

[0077] 3.1) For a given torque load T, considering the weight influence of each order natural frequency of the spline connection structure, the square error function of the natural characteristic test results and the simulation model modal results is defined:

[0078]

[0079] in, are the natural frequencies of each order under the action of a specific torque in the inherent characteristics test of the spline connection structure, is the modal frequency of each order obtained by finite element model simulation based on the thin layer element method, ηi is the weight ratio of each order natural frequency measured by the experiment, which indicates the sensitivity of each order natural frequency to torque changes and is defined as:

[0080]

[0081] The elastic modulus value that minimizes RN is obtained using MATLAB software, and the formula h is the thickness of the thin layer element, and the contact stiffness per unit area of ​​the floating spline contact surface corresponding to different torque loads is identified.

[0082] 3.2) Table 1 shows the elastic modulus values, error function values ​​and corresponding unit area contact stiffness obtained based on the thin layer element method under some different torque load T conditions; and the unit area contact stiffness diagram of the spline identified under different torque loads T is drawn, as shown in Figure 5 shown.

[0083] Table 1 Contact stiffness identification results of floating spline under different torque loads

[0084]

[0085]

[0086] 4) Dynamic response simulation of floating spline structure

[0087] 4.1) Test the damping of floating spline materials in accordance with the national standard GB / T 18258-2000 "Test method for damping performance of damping materials";

[0088] 4.2) According to Figure 1 The dynamic response simulation of the floating spline structure still uses the spline connection structure finite element model containing thin-layer elements, and the corresponding material damping ratio is given to the inner and outer splines. The contact mode and boundary conditions are consistent with the test;

[0089] 4.3) Assign different damping ratios to the thin layer elements to simulate the spline tooth friction damping effect and extract the X-direction first-order resonance response of the floating spline X-direction mapping surface;

[0090] 4.4) According to Table 1, by changing the elastic modulus of the thin layer unit to match the working conditions under different torques, repeat step 4.3) to obtain the curve of the resonance response under different torques with the change of the damping ratio of the thin layer unit, as shown in Figure 6 shown.

[0091] 5) Dynamic response test of floating spline structure

[0092] 5.1) Based on the test system built for the inherent characteristics test of the floating spline structure, the horizontal vibrator 12 and the vertical vibrator 14 are introduced and fixed to the horizontal vibrator support 13 and the vertical vibrator support 15 respectively with bolts. The vibrator fixture 11 is installed to connect the horizontal vibrator 12 and the vertical vibrator 14 to the rotating shaft 8 for dynamic response testing;

[0093] 5.2) According to Figure 1 Arrange acceleration sensors 40-43 at the positions shown and connect them to the DASP acquisition system. Complete the relevant parameter settings in the acquisition software to ensure the accuracy and stability of data acquisition.

[0094] 5.3) Use the torque loading system to apply different torques to the spline shaft system and monitor it in real time through the torque measuring instrument to ensure the stability and accuracy of the loading process;

[0095] 5.4) Use a signal generator to control the vibrator to output a swept frequency sinusoidal excitation signal. The excitation frequency range is set to 20-100 Hz based on the inherent characteristics test results. The excitation amplitude is set to 2.5 V. According to the force sensor calibration, the corresponding excitation force is about 18 N. Apply X-axis excitation;

[0096] 5.5) After completing each set of torque working condition tests, extract the response data of the floating spline X-axis measuring point and draw the amplitude-frequency response curve as shown in the figure. Figure 7 As shown, the peak point in the extracted curve includes the resonance frequency and the corresponding response amplitude data;

[0097] 5.6) After completing the current working condition test, load and measure the subsequent working conditions in sequence, repeating steps 5.3) to 5.5). The entire loading process uses a single incremental method to apply torque without unloading in the middle until all test conditions are completed;

[0098] 6) Identification of floating spline friction damping

[0099] 6.1) Based on the simulated acceleration response amplitude data of the floating spline structure under different torques, a seventh-order polynomial was used to fit it and establish a functional relationship between the damping ratio and the response amplitude;

[0100] A1=[M1][ζ b ]

[0101] [M1]=[M1(1),M1(2),M1(3),M1(4),M1(5),M1(6),M1(7),M1(8)]

[0102]

[0103] Among them, A1 is the first-order acceleration amplitude, ζ b is the damping ratio of the thin layer element, M1(1)-M1(8) are the fitting coefficients of the 7th-order polynomial;

[0104] 6.2) Substitute the acceleration response amplitude measured in the dynamic response test into the fitting formula, and inversely deduce the equivalent damping ratio of the thin layer material that matches the corresponding test torque, thereby identifying the friction damping of the floating spline contact interface under different loading torques, as shown in Table 2, and the friction damping versus torque variation diagram, as shown in Figure 8 As shown;

[0105] Table 2 Floating spline friction damping identification results

[0106]

[0107]

Claims

1. A floating spline stiffness and damping parameter identification device, characterized in that: The floating spline stiffness and damping parameter identification device comprises a fixed constraint support (1), a flanged shaft (2), a connecting disc (3), an expansion sleeve (4), an inner spline shaft (5), an outer spline shaft (6), a first diaphragm coupling (7), a rotating shaft (8), an expansion sleeve, a counterweight disc, an exciter fixture (11), a horizontal exciter (12), a horizontal exciter support (13), a vertical exciter (14), a vertical exciter support (15), a support bearing seat (18), a support bearing (19), an elastic ring (20), a retaining spring (21), a support bearing seat pressure cover (22), a second diaphragm coupling (23), a torsion spring (24), and a torque converter. A torque measuring instrument (24), a torque measuring instrument support (25), a third diaphragm coupling (26), a torsion shaft (27), a torsion shaft support bearing seat (28), a support bearing (29), a torsion shaft support bearing seat pressure cover (30), a torque arm (31), a force bolt, a spacer, an upper spring support (34), a force spring, a lower spring support (38), an acceleration sensor, an industrial computer (44), a dynamic data acquisition instrument (45), an eddy current displacement amplifier (46), an eddy current displacement sensor, a signal generator (51), a power amplifier (52), a controller (53) and a cast iron platform (54); The fixed constraint support (1), the horizontal exciter support (13), the vertical exciter support (15), the support bearing seat (18), the torque measuring instrument support (25), the torsion shaft support bearing seat (28), the upper spring support (34), and the lower spring support (38) are fixed on the cast iron platform (54) at a certain distance; the fixed constraint support (1) is rigidly connected to the flanged shaft (2); one end of the internal spline shaft (5) is rigidly fixed to the flanged shaft (2) through the expansion sleeve (4) and the connecting disc (3). The other end is engaged with one end of the external spline shaft (6) through a spline; the other end of the external spline shaft (6) is connected to one end of the rotating shaft (8) through a first diaphragm coupling (7), and the counterweight disc is rigidly fixed on the rotating shaft (8) through two expansion sleeves; the other end of the rotating shaft (8) is fitted with a support bearing (19) and an elastic ring (20), and is installed in the support bearing seat (18) for support, and the support bearing seat pressure cover (22) is fixed to the end face of the support bearing seat (18) to limit the axial displacement of the outer ring of the support bearing (19), and at the same time A retaining ring (21) is installed on the rotating shaft (8) to position the support bearing (19), and is connected to the left end of the shaft where the torque measuring instrument (24) is located through a second diaphragm coupling (23); the bottom of the torque measuring instrument (24) is fixed to the torque measuring instrument support (25), and the right end of the shaft where the torque measuring instrument (24) is located is connected to the left end of the torsion shaft (27) through a third diaphragm coupling (26) to achieve real-time and precise control of the loading torque; the torsion shaft (27) is fitted with a support bearing (29) and installed on the torsion shaft support bearing seat (28) is supported, and the torsion shaft support bearing seat pressure cover (30) is fixed to the end face of the torsion shaft support bearing seat (28) to limit the axial displacement of the outer ring of the support bearing (29); the right end of the torsion shaft (27) is tightly matched with the torsion arm (31), and the two ends of the torsion arm (31) are symmetrically arranged with a force bolt, a pad and a force spring to apply two forces of equal size and opposite direction to the torsion arm (31), thereby applying torque to the entire structure; the force bolt and the force spring are fixed to the two spring supports; Four acceleration sensors 40 to 43 arranged horizontally and vertically between the inner spline shaft (5) and the rotating shaft (8) are connected to a dynamic data acquisition instrument (45) and an industrial control computer (44) for measuring the vibration acceleration of the structure; four eddy current displacement sensors arranged horizontally and vertically between the outer spline shaft (6) and the rotating shaft (8) are connected to an eddy current displacement amplifier (46), a dynamic data acquisition instrument (45) and an industrial control computer (44) for measuring and controlling the axis trajectory; When performing a dynamic response test required for damping identification, a horizontal vibrator (12) is fixed to a horizontal vibrator support (13), and a vertical vibrator (14) is fixed to a vertical vibrator support (15). The horizontal and vertical vibrators are connected to a rotating shaft (8) via a vibrator fixture (11). A controller (53), a signal generator (51), and a power amplifier (52) together form a vibrator control system, which controls the horizontal and vertical vibrators to apply excitation to a floating spline stiffness damping parameter identification device. When performing an inherent characteristic test required for stiffness identification, it is not necessary to install the horizontal and vertical vibrators.

2. A floating spline stiffness and damping parameter identification method, characterized in that: The steps are as follows: Step 1: Build a floating spline stiffness and damping parameter identification device; first, do not install the horizontal and vertical exciters to perform inherent characteristics tests; Step 2: Using two force bolts and two force springs to apply forces of equal magnitude and opposite directions to the torque arm (31), thereby applying a torque load T to the floating spline stiffness and damping parameter identification device, and the torque load T is accurately monitored and controlled in real time by the torque measuring instrument (24); Step 3: After the torque load T is applied, wait until the state of the floating spline stiffness and damping parameter identification device is stable, and use a hammer to hammer different positions on one end of the rotating shaft (8); Step 4: obtaining an acceleration response signal of the floating spline stiffness and damping parameter identification device corresponding to the torque load T according to the acceleration sensor and the industrial control computer (44); Step 5: Apply a gradually increasing torque load T. Repeat step 4 after each loading to obtain the acceleration response signal of the floating spline stiffness and damping parameter identification device corresponding to the loading torque T. max Then gradually uninstall; Step 6: After unloading, the horizontal and vertical vibrators are fixed to the horizontal vibrator support (13) and the vertical vibrator support (15) respectively by bolts, and the vibrator fixture (11) is installed to connect the horizontal and vertical vibrators to the rotating shaft (8) for dynamic response testing; Step 7: Repeat step 2, apply a torque load T of the same magnitude, use a controller (53), a signal generator (51), and a power amplifier (52) to control the horizontal and vertical exciters to apply sinusoidal excitation in the horizontal and vertical directions to the floating spline stiffness and damping parameter identification device, select a sweep frequency range of 20-100 Hz, and set the excitation amplitude to 2.5 V. The vibration acceleration signal of the spline and the rotating shaft (8) is transmitted to the industrial computer (44) via the acceleration sensor and the dynamic data acquisition instrument (45), and the acceleration response signal of the floating spline structure corresponding to the torque T is obtained; Step 8: Gradually increase the applied torque T. Each loading is the same as the torque T corresponding to step 5. After each loading, repeat step 7 to obtain the acceleration response signal of the floating spline structure under the loading torque T. When the maximum torque T is reached, max After that, gradually uninstall and complete all tests; Step 9: Floating spline contact stiffness identification method: S9.1 Define the squared error function between the intrinsic characteristic test results and the simulation model modal results: in, are the natural frequencies of each order under the action of a specific torque in the inherent characteristics test of the spline connection structure, is the modal frequency of each order obtained by finite element model simulation based on thin layer element method, η i is the weight ratio of each order natural frequency measured in the test, which indicates the sensitivity of each order natural frequency to torque changes and is defined as: S9.2 Use MATLAB software to find the elastic modulus value that minimizes R(N) by the formula h is the thickness of the thin layer element, and the contact stiffness per unit area of ​​the floating spline contact surface corresponding to different torque loads is identified; Step 10: Identification method of floating spline friction damping: S10.1 Establish a finite element model of a damped thin-layer unit and perform dynamic response simulation considering the influence of damping. Use MATLAB software to fit the dynamic response simulation results and establish a functional relationship between the damping ratio and the response amplitude. S10.2 Substitute the acceleration response amplitude measured in the dynamic response test into the fitting formula to infer the equivalent damping ratio of the thin layer material that matches the corresponding test torque, and identify the friction damping of the floating spline contact surface corresponding to different torque loads.

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