A method for identifying the resonance stress of spiral bevel gear spokes

Abstract

This invention discloses a method for testing and identifying the resonant stress of bevel gear spokes, relating to the field of bevel gear spoke resonance stress identification technology. It can determine the resonant speed, resonant frequency, and resonant stress of the spokes within the operating speed range, facilitating subsequent vibration reduction optimization. The method includes the following steps: Step 1, information acquisition; Step 2, setting up a dynamic stress test bench for the spokes; Step 3, conducting a uniform speed increase and frequency sweep test; Step 4, obtaining the relationship between strain and speed based on the strain-speed curve obtained in Step 3, thereby determining the resonant speed range and traveling wave resonant speed point when pitch diameter resonance occurs; Step 5, conducting a speed dwell test; Step 6, data analysis; Step 7, result processing. This method helps to accurately and quickly formulate vibration reduction design schemes for bevel gears, which is beneficial for lightweight vibration reduction design of bevel gears.

Description

Technical Field

[0001] This invention relates to the field of bevel gear spoke resonance stress identification technology, specifically to a test method for the experimental resonance frequency and spoke resonance stress of a bevel gear when traveling wave resonance occurs. Background Technology

[0002] The gear transmission system of aero-engines operates at high speeds and under complex conditions, resulting in significant vibration issues. To meet lightweight design requirements, bevel gears are often designed with thin spokes, increasing structural flexibility. However, this can lead to multiple resonant speed points within the operating range. Large resonant stresses can cause high-cycle fatigue in the gear spokes, potentially even causing them to fracture. This affects the lifespan of the entire transmission system and poses a threat to flight safety.

[0003] The resonant stress generated at different resonant speed points of bevel gears varies in magnitude. Not all resonant stresses will affect gear safety. While structural frequency tuning can move some resonant speed points away from the operating speed range, resonant speed points still exist. Therefore, identifying the resonant stress of the spokes at these speed points is of significant engineering importance for determining whether passive vibration reduction should be implemented subsequently.

[0004] Currently, there is a lack of a complete and effective testing and identification method for the resonant stress of spokes within the operating speed range in China. It is impossible to obtain the resonant speed, resonant frequency, and resonant stress at the accurate resonant speed point, thus making it impossible to accurately and quickly formulate a vibration reduction design scheme for bevel gears, which restricts the lightweight vibration reduction design of bevel gears. Summary of the Invention

[0005] To address the above problems, this invention proposes a method for testing and identifying the resonance stress of the spokes of an arc bevel gear. This method can determine the resonant speed, resonant frequency, and resonance stress of the spokes within the operating speed range, in order to facilitate subsequent vibration reduction optimization.

[0006] The technical solution of the present invention includes the following steps:

[0007] Step 1: Information Collection;

[0008] Prestressed modal analysis and Campbell's diagram were used to perform traveling wave resonance analysis on the spiral bevel gear pair to obtain the modal frequencies, modal displacements, and modal stresses that cause radial vibration of the spokes, and to obtain the strain gauge layout diagram.

[0009] Step 2: Construct the dynamic stress test bench for the spokes;

[0010] Based on the modal stress results and strain gauge layout diagram, strain gauges are placed at the positions with the maximum modal stress on the spokes of the test spiral bevel gear, and accelerometers are placed on the test gearbox. Strain values ​​are obtained through strain gauges, and vibration acceleration data transmitted from the spiral bevel gear to the test gearbox are obtained through accelerometers.

[0011] Step 3: Conduct a uniform speed-up frequency sweep test;

[0012] Rotate the spiral bevel gear and gradually increase the speed from the lower limit of the working speed range to the upper limit of the working speed range to extract the strain signal of the spokes within the working speed range.

[0013] Step 4: Based on the strain-rotation speed relationship obtained in Step 3, the resonant rotation speed range and traveling wave resonant rotation speed point when the pitch diameter type resonance occurs are obtained;

[0014] Step 5: Conduct a speed dwell test;

[0015] Using the traveling wave resonance speed point n obtained in step 4 as a reference, five speed points are taken before and after this speed, namely (n-40), (n-20), n, (n+20), and (n+40) speed points, and the dwell time of each speed point is determined. t And the acceleration time between each speed point;

[0016] A speed dwell test was conducted based on the set speed dwell time and dwell interval.

[0017] Extract the rotational speed change graph for this process;

[0018] Extract the strain gauge data during this process to obtain the strain signal diagram of the spokes;

[0019] Extract the vibration acceleration signal of the box during this process to obtain an acceleration signal diagram;

[0020] Step 6: Data Analysis;

[0021] Time-frequency analysis of acceleration signals and strain gauge signals was performed to obtain the resonant rotational speed, resonant frequency, and dynamic stress of the spokes at the resonant point.

[0022] Step 7: Result Processing;

[0023] When the number of traveling wave resonance speed points obtained in step 4 is greater than 1, return to step 5 to conduct speed dwell tests on all traveling wave resonance speed points to obtain multiple spoke resonance stress values. Combine the Goodman curve and SN curve of the gear to determine whether the above multiple spoke resonance stress values ​​exceed the allowable dynamic stress range. If they exceed the range, then active or passive vibration reduction optimization processing is carried out.

[0024] The dynamic stress test bench for spokes built in step 2 includes a motor 1, a coupling 2, a speed-increasing gearbox 3, a torque meter 4, a test gearbox 5, a reduction gearbox 9, and an eddy current brake 10 connected in sequence.

[0025] The spiral bevel gear pair to be tested is installed in the test gearbox 5, and is connected to the torque meter 4 and the reduction gearbox 9 respectively. The motor 1 provides power to the spiral bevel gear pair to be tested, and the electric eddy current brake 10 provides torque to the spiral bevel gear pair to be tested.

[0026] The dynamic stress test rig for the spokes built in step 2 also includes strain gauges, accelerometers 6, slip rings 7, data acquisition instruments 8, and a computer 11 connected to the data acquisition instruments 8;

[0027] Several strain gauges are also installed on the spiral bevel gear. Based on the results of the modal stress and the strain gauge layout diagram, the strain gauges are arranged at the positions where the modal stress of the spokes of the test spiral bevel gear is the greatest. The strain gauges are connected to the data acquisition instrument 8 via slip ring 7.

[0028] An acceleration sensor 6 is also fixedly installed on the housing of the test gearbox 5, and the acceleration sensor 6 is also connected to the data acquisition instrument 8.

[0029] In step 6, time-domain and frequency-domain analyses are performed on the strain gauge signals and acceleration signals at each dwell speed:

[0030] If the frequency of the dynamic strain signal is at the same rotational speed n f d Frequency of acceleration signal f e The following relationship exists:

[0031] f e = f d ±mn / 60

[0032] Where: m is the number of nodal diameters, that is, the number of nodal lines in the nodal-diameter vibration, which is an integer;

[0033] like f e = f d +mn / 60, then at this time, m-node diameter forward traveling wave resonance occurs, and the resonance speed is n. F ;like f e = f d -mn / 60, at this point, traveling wave resonance occurs after the m-section diameter, and the resonance speed is n. B ;

[0034] Obtain the magnitude of the dynamic stress at the point where the traveling wave resonance occurs, and use it as the dynamic stress of the spokes at the resonance point.

[0035] Compared with the prior art, this invention forms a complete and effective method for testing and identifying dynamic stress of spokes. By combining strain gauge signals and acceleration signals, it can accurately obtain the resonant speed, resonant frequency, and resonant stress at the resonant speed point. This helps to accurately and quickly formulate a vibration reduction design scheme for bevel gears, which is beneficial to the lightweight vibration reduction design of bevel gears. Attached Figure Description

[0036] Figure 1 This is a flowchart of an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram illustrating the experimental principle of an embodiment of the present invention.

[0038] Figure 3 This is a diagram showing the distribution of strain gauges on a gear according to an embodiment of the present invention.

[0039] Figure 4 This is a lead diagram of a gear strain gauge according to an embodiment of the present invention.

[0040] Figure 5 This refers to the acceleration strain gauge signal in an embodiment of the present invention.

[0041] Figure 6 This is the time-domain signal of the dwell test speed in an embodiment of the present invention.

[0042] Figure 7 This is the time-domain signal of the strain gauge used in the dwell test according to an embodiment of the present invention.

[0043] Figure 8 This is the time-domain signal of the dwell test acceleration in an embodiment of the present invention. Detailed Implementation

[0044] To clearly illustrate the technical features of this patent, the following detailed description is provided through specific embodiments and in conjunction with the accompanying drawings.

[0045] like Figures 1-6 As shown in the figure, this embodiment provides a method for testing and identifying the resonance stress of the spokes of an arc-tooth bevel gear, including the following steps:

[0046] Step 1, as follows Figure 1 As shown, prestressed modal analysis and Campbell's diagram were first used to analyze the traveling wave resonance of the spiral bevel gear pair to obtain the modal frequencies, modal displacements and modal stresses of the radial vibration of the spokes, and the strain gauge layout diagram was obtained.

[0047] Step 2: Construct a dynamic stress test bench for spokes, including a drive motor, test gearbox, slip rings, torque meter, acceleration sensor, and eddy current brake. Its schematic diagram is shown below. Figure 2 As shown, motor 1 provides power to the spiral bevel gear pair under test, and eddy current brake 10 provides torque to the spiral bevel gear pair under test. Based on the modal stress results and strain gauge layout diagram, strain gauges are arranged at the positions with the maximum modal stress on the spokes of the tested spiral bevel gear, and at least four strain gauges are arranged along the circumference to eliminate random errors in the test. The arrangement positions are as follows: Figure 3 As shown; the slip ring rotor end is connected to the test gear shaft, the strain gauge lead passes through the shaft hole and connects to the rotor end lead, and the stator end lead is connected to the data acquisition instrument; the acceleration sensor is arranged on the test gearbox, its position is near the bearing of the test gear, and it is connected to the data acquisition instrument, as shown. Figure 4 As shown, strain values ​​are obtained using strain gauges, and vibration acceleration data transmitted from the spiral bevel gear to the test gearbox are obtained using an accelerometer.

[0048] Step 3: Conduct a uniform speed-up frequency sweep test. First, uniformly increase the motor speed to the lower limit of the operating speed range, such as 1000 r / min. Then, uniformly increase the speed at a rate of 50 r / min / s until the upper limit of the operating speed range, 4300 r / min, is reached. Extract the spoke strain signal within the operating speed range, such as... Figure 5 As shown.

[0049] Step 4: Based on the strain-rotation speed relationship obtained in Step 3, the resonant rotational speed range and traveling wave resonant rotational speed point at which the nodal-diameter resonance occurs are obtained. Specifically:

[0050] Strain gauge signal analysis revealed three traveling wave resonance speed points within the operating speed range: 2796 r / min, 3012 r / min, and 3896 r / min.

[0051] Step 5: Conduct a speed dwell test;

[0052] Taking the first resonance point as an example, the resonance speed range was determined to be 2750 r / min to 2830 r / min. Five speed points were selected before and after this speed, and the speed was stopped at 2750 r / min, 2770 r / min, 2790 r / min, 2810 r / min and 2830 r / min respectively. The stop time was 4 seconds, and the acceleration time between each speed point was 2 seconds. The speed stop test was carried out.

[0053] Based on the set speed dwell time and dwell interval, a speed dwell test is conducted, and the speed change graph during this process is extracted, as shown below. Figure 6As shown, the shaded area represents the dwell time rotation. Data from strain gauges during this process is extracted to obtain the strain signal diagram of the spokes, as shown below. Figure 7 As shown, the vibration acceleration signal of the box body during this process is extracted to obtain the acceleration signal diagram, as shown below. Figure 8 As shown.

[0054] Step 6: Perform time-domain and frequency-domain analysis on the acceleration signal and strain gauge signal. It was found that when the rotational speed remained around 2790 r / min, the amplitudes of both the strain gauge signal and the acceleration signal increased. According to the frequency-domain analysis, when the rotational speed was 2789 r / min, the first-order meshing frequency of the acceleration signal was... f e The strain gauge signal is at 2754 Hz. f d The strain amplitude is largest at 2849 Hz, reaching 196 με, according to the formula:

[0055] f e = f d ±mn / 60

[0056] At this point, the calculated number of nodes, m, is 2.04, which satisfies the condition. f e = f d -mn / 60, meaning that two-section travel wave resonance occurs at this point (conversely, if the following condition is met...). f e = f d If +mn / 60, it is considered that a two-section radial traveling wave resonance occurs. The resonance speed is 2789 r / min, the resonance frequency is 2849 Hz, and the resonance stress of the spokes is 40.37 MPa.

[0057] Step 7: Similarly, conduct speed dwell tests at the other two traveling wave resonance speed points to obtain the resonant stress values ​​of the three spokes. Combine the Goodman curve and SN curve of the gear to determine whether the above three values ​​exceed the allowable dynamic stress range. If they exceed the range, optimize the process by active or passive vibration reduction.

[0058] This embodiment proposes a method for testing and identifying the resonant stress of spiral bevel gear spokes. This method considers that excessive resonant stress in the operating speed range can lead to fatigue fracture of the gear spokes, thus enabling dynamic stress measurement during traveling wave resonance. First, prestress modal analysis and traveling wave resonance analysis of the spiral bevel gear pair are performed to obtain the resonance points within the operating speed range. A dynamic stress test bench is built, strain gauges are attached to the spokes, and acceleration sensors are placed at the bearing positions of the test gearbox. A uniform speed-up frequency sweep experiment is conducted to acquire strain and acceleration signals. Based on the results, the speed dwell range, dwell interval, and dwell time are set. Taking a traveling wave with two pitch diameters as an example, a speed dwell experiment is conducted to obtain the dynamic stress of the spokes when traveling wave resonance occurs with two pitch diameters. According to this dynamic stress testing and identification method, traveling wave resonance points within the operating speed range can be quickly and accurately identified, along with their resonant speed, resonant frequency, and pitch diameter number (i.e., the dynamic stress of the resonant spokes). This allows for the rapid and accurate development of vibration reduction schemes for excessively high resonant speed points.

[0059] There are many specific ways to implement this invention. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A method for testing and identifying the resonance stress of the spokes of an arc-tooth bevel gear, characterized in that, The steps include the following: Step 1: Information Collection; Prestressed modal analysis and Campbell's diagram were used to perform traveling wave resonance analysis on the spiral bevel gear pair to obtain the modal frequencies, modal displacements, and modal stresses that cause radial vibration of the spokes, and to obtain the strain gauge layout diagram. Step 2: Construct the dynamic stress test bench for the spokes; Based on the modal stress results and strain gauge layout diagram, strain gauges are placed at the positions with the maximum modal stress on the spokes of the test spiral bevel gear, and accelerometers are placed on the test gearbox. Strain values ​​are obtained through strain gauges, and vibration acceleration data transmitted from the spiral bevel gear to the test gearbox are obtained through accelerometers. Step 3: Conduct a uniform speed-up frequency sweep test; Rotate the spiral bevel gear and gradually increase the speed from the lower limit of the working speed range to the upper limit of the working speed range to extract the strain signal of the spokes within the working speed range. Step 4: Based on the strain-rotation speed relationship obtained in Step 3, the resonant rotation speed range and traveling wave resonant rotation speed point when the pitch diameter type resonance occurs are obtained; Step 5: Conduct a speed dwell test; Using the traveling wave resonance speed point n obtained in step 4 as a reference, five speed points are taken before and after this speed, namely (n-40), (n-20), n, (n+20), and (n+40) speed points, and the dwell time of each speed point is determined. t And the acceleration time between each speed point; A speed dwell test was conducted based on the set speed dwell time and dwell interval. Extract the rotational speed change graph for this process; Extract the strain gauge data during this process to obtain the strain signal diagram of the spokes; Extract the vibration acceleration signal of the box during this process to obtain an acceleration signal diagram; Step 6: Data Analysis; Time-frequency analysis of acceleration signals and strain gauge signals was performed to obtain the resonant rotational speed, resonant frequency, and dynamic stress of the spokes at the resonant point. Step 7: Result Processing; When the number of traveling wave resonance speed points obtained in step 4 is greater than 1, return to step 5 to conduct speed dwell tests on all traveling wave resonance speed points to obtain multiple spoke resonance stress values. Combine the Goodman curve and SN curve of the gear to determine whether the above multiple spoke resonance stress values ​​exceed the allowable dynamic stress range. If they exceed the range, then active or passive vibration reduction optimization processing is carried out.

2. The method for testing and identifying the resonance stress of the spokes of an arc-tooth bevel gear according to claim 1, characterized in that, The dynamic stress test bench for the spokes built in step 2 includes a motor (1), a coupling (2), a speed-increasing gearbox (3), a torque meter (4), a test gearbox (5), a reduction gearbox (9), and an eddy current brake (10) connected in sequence. The spiral bevel gear pair to be tested is installed in the test gearbox (5), and is connected to the torque meter (4) and the reduction gearbox (9) respectively; the motor (1) provides power to the spiral bevel gear pair to be tested, and the electric eddy current brake (10) provides torque to the spiral bevel gear pair to be tested; The dynamic stress test bench for the spokes built in step 2 also includes strain gauges, acceleration sensors (6), slip rings (7), data acquisition instruments (8), and a computer (11) connected to the data acquisition instruments (8). Several strain gauges are also installed on the spiral bevel gear. Based on the results of the modal stress and the strain gauge layout diagram, the strain gauges are arranged at the positions where the modal stress of the test spiral bevel gear spokes is the greatest. The strain gauges are connected to the data acquisition instrument (8) via slip rings (7). An acceleration sensor (6) is also fixedly installed on the housing of the test gearbox (5), and the acceleration sensor (6) is also connected to the data acquisition instrument (8).

3. The method for testing and identifying the resonance stress of the spokes of an arc-tooth bevel gear according to claim 1, characterized in that, In step 6), time-domain and frequency-domain analyses are performed on the strain gauge signals and acceleration signals at each dwell speed: If the frequency of the dynamic strain signal is at the same rotational speed n f d Frequency of acceleration signal f e The following relationship exists: f e = f d ±mn / 60 Where: m is the number of nodal diameters, that is, the number of nodal lines in the nodal-diameter vibration, which is an integer; like f e = f d +mn / 60, then at this time, m-node diameter forward traveling wave resonance occurs, and the resonance speed is n. F ;like f e = f d -mn / 60, at this point, traveling wave resonance occurs after the m-section diameter, and the resonance speed is n. B ; Obtain the magnitude of the dynamic stress at the point where the traveling wave resonance occurs, and use it as the dynamic stress of the spokes at the resonance point.

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