Spacecraft reaction flywheel multi-directional power absorber and testing method

Abstract

The application belongs to the technical field of spacecraft micro-vibration control, and particularly relates to a spacecraft reaction flywheel multidirectional power vibration absorber and a testing method; comprising a structural support plate, a mounting threaded column, a sliding block, a moving mass block and a rubber ball; the advantages of the proposed tuned mass damper are that the tuned mass damper is installed in the reaction flywheel by the mounting bracket, the overall structure is simple, the reliability is high, the micro-vibration can be inhibited from the disturbance source of the reaction flywheel, the stiffness is adjustable, the variable damping characteristics make the power vibration absorber have strong interchangeability, the nonlinear characteristics make the power vibration absorber have a wide vibration absorption frequency band, and the vibration absorption effect is better.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of spacecraft micro-vibration control, and particularly relates to a spacecraft reaction flywheel multidirectional dynamic vibration absorber and a testing method. BACKGROUND

[0002] When a spacecraft is performing a high-stability and high-precision pointing mission, the influence of micro-vibration with the characteristics of wide frequency band and multiple harmonics is particularly critical. As a core component of the spacecraft attitude control system, the internal rotor of the reaction flywheel becomes a major disturbance source due to factors such as dynamic and static imbalance, bearing error and motor harmonics. Therefore, effective suppression of the micro-vibration of the reaction flywheel is crucial to ensure the normal operation of the spacecraft. Early micro-vibration suppression methods mainly rely on viscous fluid friction and damping materials. Although these methods are simple and effective, they increase the mass of the spacecraft and have limitations in the design of lightweight and high-integration spacecraft. Subsequently, passive vibration isolation technology is developed to reduce vibration by increasing structural flexibility and damping. However, its vibration isolation effect is limited when facing low-frequency and random vibration disturbances, and the vibration reduction effect needs to be analyzed in conjunction with the entire spacecraft. To address the above problems, active vibration isolation technology is proposed and rapidly developed. This technology adapts to different vibration environments through a real-time feedback control system, and performs well in low-frequency vibration suppression. However, the active vibration isolation system is limited by the bandwidth of the actuator, high-frequency energy consumption and the stability of the control system, and may reduce the service life of the actuator in the high-frequency range. Dynamic vibration absorption technology is another suppression method that achieves vibration dissipation and transfer by constructing a stiffness-damping-mass mechanism. The micro-vibration dynamic vibration absorber technology used today is only a supplement to passive vibration isolation technology, with fixed vibration absorption frequency and narrow vibration reduction frequency band. SUMMARY

[0003] To solve the above problems, the present patent proposes a nonlinear variable stiffness dynamic vibration absorber designed to be integrated inside the reaction flywheel, which can effectively suppress the multi-harmonic disturbance and vibration of the reaction flywheel under time-varying conditions. The technical solution is as follows:

[0004] A spacecraft reaction flywheel multidirectional dynamic vibration absorber, comprising a structural support plate, a fixing screw, a mounting threaded column, a sliding block, a moving mass block and a rubber ball. Six structural support plates form a cube symmetric structure through fixing screws and are mounted and fixed on a mounting bracket through mounting threaded columns and nuts. A slide groove is provided on the inner side surface of the structural support plate, and the sliding block is located in the slide groove and can move along the vertical surface direction. The moving mass block is located in the cube, and an inner conical surface is provided on each of the six faces of the moving mass block corresponding to the faces of the six sliding blocks. The rubber ball is located between the inner conical surface of the moving mass block and the inner conical surface of the sliding block.

[0005] Preferably, a threaded hole is arranged at the center of the outer side of each structural support plate for mounting a compression adjusting screw, and a sliding groove is arranged at the center of the inner side of each structural support plate, and the sliding block is arranged in the sliding groove.

[0006] Preferably, the support structure is made of aluminum alloy material, the rubber ball is made of nitrile rubber material, and the moving mass is made of high-density brass.

[0007] Preferably, the rubber ball provides damping for the dynamic vibration absorber, the stiffness generated by the contact between the rubber ball and the inner conical surface and the stiffness generated by the compression of the rubber ball are used as the stiffness of the dynamic vibration absorber, and the moving mass is used as the moving mass of the dynamic vibration absorber.

[0008] Preferably, the sliding block is provided with an inner conical surface, and each surface of the moving mass is also provided with an inner conical surface, and the two inner conical surfaces have consistent structural parameters.

[0009] The test method of the multi-directional dynamic vibration absorber of the spacecraft reaction flywheel comprises the following steps:

[0010] S1. Micro-vibration test is performed on the reaction flywheel, data analysis is performed on the main modal vibration frequency domain of the reaction flywheel, and the main frequency band of each direction is recorded;

[0011] S2. The mass of the dynamic vibration absorber moving mass is selected based on the overall mass requirement of the reaction flywheel, the mass ratio of the reaction flywheel to the dynamic vibration absorber is calculated, and the frequency to be reached by the dynamic vibration absorber tuning is calculated according to the optimal coherence theory;

[0012] S3. The related design parameters of the dynamic vibration absorber are optimized by constructing a finite element model, the overall dynamic vibration absorber fundamental frequency is obtained by simulation, the main modal frequency of the reaction flywheel is made to be within the tunable frequency band, and the structure parameters of the dynamic vibration absorber are determined;

[0013] S4. The vibration absorption frequency is checked by calculating the contact stiffness of the dynamic vibration absorber, and the vibration reduction effect of the dynamic vibration absorber is verified by numerical simulation of a two-degree-of-freedom dynamic vibration model.

[0014] Preferably, the square composed of the structural support plates is on a one-way structure, the rotation depth of the compression adjusting screw is adjusted symmetrically to push the sliding block to move in the sliding groove, the inner conical surface of the sliding block compresses the rubber ball to change the internal contact state of the one-way dynamic vibration absorber, the fundamental frequency of the dynamic vibration absorber changes, and the tuning purpose is achieved.

[0015] Preferably, the optimal coherence theory formula is as follows:

[0016]

[0017] In the formula, ωm ian is the main modal frequency of the reaction flywheel, and ωDVA is the frequency of the dynamic vibration absorber.

[0018] The one-way contact stiffness of the dynamic vibration absorber is preferably calculated according to the following formula:

[0019]

[0020] Six structural support plates are combined into a cubic symmetric structure by fixing screws, and the structure is regarded as a main structure. The rubber ball is in contact with the inner conical surface in a conical annular surface with a half-width of b, the radius of the rubber ball is R1, ψ is the half-cone angle of the inner conical surface, F is the axial pressure provided by the main structure, E1, μ1, E2 and μ2 are the elastic modulus and Poisson's ratio of the main structure and the rubber ball, respectively, E * is the equivalent elastic modulus; r is the distance of the calculation point of the contact surface from the contact center, and z is the normal distance of the calculation point from the origin.

[0021] The two-degree-of-freedom dynamic vibration absorber model of the reaction flywheel in the translational mode is preferably:

[0022]

[0023] The dynamic vibration absorber model of the reaction flywheel in the radial swing mode is:

[0024]

[0025] m1, c1 and k1 are the mass, stiffness and damping of the reaction flywheel in the translational direction, respectively; k c , k a , k b are the equivalent stiffness of the rubber ball in contact, c2 is the damping of the rubber ball, U s is the static unbalance mass of the rotor, C i is the amplitude of the disturbance harmonic, h i is the harmonic number; is the moment of inertia of the reaction flywheel, U d is the dynamic unbalance of the rotor; m2 is the mass of the dynamic vibration absorber, x1 and x2 are the displacements of the reaction flywheel and the dynamic vibration absorber in the translational mode equation, respectively, θ 1x , θ 2x are the rotations of the reaction flywheel and the dynamic vibration absorber in the x direction in the radial swing mode equation, respectively, θ 1y , θ 2y are the rotations of the reaction flywheel and the dynamic vibration absorber in the y direction in the radial swing mode equation;

[0026] are the moments of inertia of the dynamic vibration absorber in the x and y directions, respectively; c4 and c5 are the dampings of the reaction flywheel in the x and y direction rotation degrees of freedom, respectively; Ω is the rotation speed of the reaction flywheel; θ 1x , θ 1y , θ 2x , θ 2yThe reaction flywheel rotation amounts in x and y directions, respectively, and the power absorber rotation amounts in x and y directions.

[0027] Compared with the prior art, the application has the following advantages:

[0028] 1. The absorber is characterized by the elastic restoring force of a rubber ball to represent nonlinear factors, and contact stiffness to realize the tunable function of the power absorber. By using the nonlinear dynamics principle and the variable stiffness technology, a lightweight and high-integration solution is provided to meet the continuous demand for high performance of the spacecraft in a complex vibration environment. The method reduces the complex joint design and analysis work of the vibration isolator and the whole satellite system involved in the passive vibration isolation technology.

[0029] 2. Wideband vibration reduction capability, which can adapt to the time-varying characteristics caused by the change of the rotation speed of the RWA in orbit. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a perspective view of the application.

[0031] Figure 2 It is a perspective view of the application.

[0032] Figure 3 It is a front view of the application.

[0033] Figure 4 It is a semi-partial view of the application.

[0034] Figure 5 It is a test flowchart of the application.

[0035] In the figure: 1-structure support plate, 2-fixed screw, 3-mounting bracket, 4-mounting threaded column, 5-sliding block, 6-moving mass, 7-rubber ball, 8-compression adjusting screw. DETAILED DESCRIPTION

[0036] The invention and features will be described below in combination with the drawings, and the examples are only used to explain the invention and not to limit the scope of the invention.

[0037] A spacecraft reaction flywheel multi-directional power absorber, comprising a structure support plate 1, a fixed screw 2, a mounting threaded column 4, a sliding block 5, a moving mass 6, and a rubber ball 7; six structure support plates 1 form a cube symmetric structure through fixed screws 2, and are mounted and fixed on a mounting bracket 3 through mounting threaded columns 4 and nuts; the inner side surface of the structure support plate 1 is provided with a sliding groove, and the sliding block is located in the sliding groove and can move along the vertical surface direction; the moving mass 6 is located in the cube, and the six surfaces of the moving mass 6 are each provided with an inner tapered surface corresponding to the surface of the six sliding blocks, and the rubber ball 7 is located between the inner tapered surface of the moving mass and the inner tapered surface of the sliding block.

[0038] Each of the structural support plates is provided with a threaded hole at the center of the outer side surface for mounting a compression adjusting screw, and each of the structural support plates is provided with a sliding groove at the center of the inner side surface, and the sliding block is located in the sliding groove.

[0039] The support structure is made of aluminum alloy material, the rubber ball is made of nitrile rubber material, and the moving mass is made of high-density brass.

[0040] The rubber ball provides damping for the dynamic vibration absorber, the stiffness generated by the contact between the rubber ball and the inner conical surface and the stiffness generated by the compression of the rubber ball itself serve as the stiffness of the dynamic vibration absorber, and the moving mass serves as the moving mass of the dynamic vibration absorber.

[0041] The sliding block is provided with an inner conical surface, and each surface of the moving mass is also provided with an inner conical surface, and the two inner conical surfaces have consistent structural parameters.

[0042] The six structural support plates 1 in the dynamic vibration absorber are connected by 12 M3x8 fixing screws 2, the fixing screws are internal hexagonal cylindrical head screws, and each screw is embedded in the structural support plate. The material of the structural support plate is aluminum alloy 2A12. The overall envelope of the dynamic vibration absorber is 28mmx28mmx28mm.

[0043] There is a M2.5 threaded hole on the outer surface of each structural support plate 1 for mounting a compression adjusting screw 8. The specification of the compression adjusting screw 8 is M2.5x5.

[0044] There is a 8mmx8mmx3mm sliding groove on the inner surface of each structural support plate 1, and a sliding block 5 can be installed in the sliding groove. The sliding block 5 is tightly assembled with the sliding groove, and the thickness of the sliding block 5 is 5mm.

[0045] The inner surface of each sliding block 5 contains an inner conical surface with consistent parameters, the half-cone angle of the inner conical surface is 45°, and the diameter of the inner conical surface is 5mm.

[0046] The dynamic vibration absorber contains six rubber balls 7, the material of the rubber ball 7 is nitrile, the diameter is 6mm, and the six rubber balls 7 are symmetrically distributed on the six surfaces.

[0047] The size of the moving mass 6 is 8mmx8mmx8mm, the material is high-density metal brass, and there is an inner conical surface on each of the six surfaces. The size of the inner conical surface is consistent with the parameters of the inner conical surface on the sliding block 5, and the moving mass 6 in a single direction of the dynamic vibration absorber is fixed by compressing two rubber balls 7 by the sliding block 5.

[0048] Two threaded rods with M3 specification are arranged on the structure support plate 1 of the dynamic vibration absorber, and used to fix the dynamic vibration absorber on the mounting bracket 3. Two mounting threaded column 4 installation through holes with a diameter of 3.4 mm and a compression adjusting screw 8 through hole with a diameter of 5.5 mm are reserved on the mounting bracket 3, which facilitates the screwing in and out of the upward compression adjusting screw 8. The two ends of the mounting bracket 3 have through holes with a diameter of 2.4 mm, and the whole dynamic vibration absorber and the mounting bracket structure can be fixed in the reaction flywheel structure by screws.

[0049] The test method of the spacecraft reaction flywheel multidirectional dynamic vibration absorber comprises the following steps:

[0050] S1. Micro-vibration test is performed on the reaction flywheel, data analysis is performed on the main modal vibration frequency domain of the reaction flywheel, and the main frequency band of each direction is recorded;

[0051] S2. The mass of the dynamic mass block of the dynamic vibration absorber is selected based on the overall mass requirement of the reaction flywheel, the mass ratio of the reaction flywheel to the dynamic vibration absorber is calculated, and the frequency to be reached by the dynamic vibration absorber tuning is calculated according to the optimal tuning theory;

[0052] S3. The related design parameters of the dynamic vibration absorber are optimized by constructing a finite element model, the overall dynamic vibration absorber base frequency is obtained by simulation, the main modal frequency of the reaction flywheel is made to be within the tunable frequency band, and the structure parameters of the dynamic vibration absorber are determined (by adjusting the compression adjusting screw, controlling the movement of the slider, and thus controlling the contact surface between the rubber ball and the inner conical surface);

[0053] S4. The vibration absorption frequency of the dynamic vibration absorber is checked by calculating the contact stiffness, and the vibration reduction effect of the dynamic vibration absorber is verified by numerical simulation of a two-degree-of-freedom dynamic vibration model.

[0054] A square composed of the structure support plate 1 is formed on the one-way structure, the rotation depth of the symmetric adjustment compression adjusting screw is adjusted to push the slider to move in the slide groove, and then the inner conical surface of the slider compresses the rubber ball to change the internal contact state of the one-way dynamic vibration absorber, the base frequency of the dynamic vibration absorber changes, and the tuning purpose is achieved.

[0055] The optimal tuning theory formula is as follows:

[0056]

[0057] In the formula, ωm ian is the main modal frequency of the reaction flywheel, and ωDVA is the frequency of the dynamic vibration absorber.

[0058] The one-way contact stiffness calculation formula of the dynamic vibration absorber is as follows:

[0059]

[0060] Six structural support plates are combined into a cubic symmetric structure by fixing screws as the main structure; the rubber ball is in contact with the inner conical surface with a semi-width of b, the radius of the rubber ball is R1, ψ is the semi-cone angle of the inner conical surface, F is the axial pressure provided by the main structure, E1, μ1, E2, μ2 are the elastic modulus and Poisson's ratio of the main structure and the rubber ball respectively, E * is the equivalent elastic modulus; r is the distance of the calculation point of the contact surface from the contact center, and z is the normal distance of the calculation point from the origin.

[0061] Preferably, the two-degree-of-freedom dynamic vibration absorption model of the reaction flywheel translational mode is:

[0062]

[0063] The dynamic vibration absorption model of the reaction flywheel radial swing mode is:

[0064]

[0065] m1, c1, k1 are the mass, stiffness and damping of the reaction flywheel in the translational direction respectively; k c , k a , k b are the equivalent stiffness of the rubber ball in contact with each other, c2 is the damping of the rubber ball, U s is the static unbalance mass of the rotor, C i is the amplitude of the disturbance harmonic wave, h i is the harmonic number; is the moment of inertia of the reaction flywheel, U d is the dynamic unbalance of the rotor; m2 is the mass of the dynamic vibration absorber, x1, x2 are the displacements of the reaction flywheel and the dynamic vibration absorber in the translational mode equation respectively, θ 1x , θ 2x are the rotations of the reaction flywheel and the dynamic vibration absorber in the x direction in the radial swing mode equation respectively, θ 1y , θ 2y are the rotations of the reaction flywheel and the dynamic vibration absorber in the y direction in the radial swing mode equation respectively;

[0066] are the moments of inertia of the dynamic vibration absorber in the x and y directions respectively; c4, c5 are the dampings of the reaction flywheel in the x and y direction rotation degrees of freedom respectively; Ω is the rotation speed of the reaction flywheel; θ 1x , θ 1y , θ 2x , θ 2y are the rotations of the reaction flywheel in the x and y direction degrees of freedom, and the rotations of the dynamic vibration absorber in the x and y direction degrees of freedom.

[0067] According to the design parameters of the dynamic vibration absorber, the structural components of the dynamic vibration absorber are processed and assembled, and the dynamic vibration absorber is installed in the reaction flywheel. The whole micro-vibration absorption process can be described as the disturbance generated by the reaction flywheel rotor, the motor and the bearing being transmitted to the dynamic vibration absorber structure through the reaction flywheel structure, and the micro-vibration level being attenuated through the motion transfer of the dynamic mass and the damping dissipation of the rubber ball.

[0068] The above is an example of the best embodiment of the present application, where parts not described in detail are common knowledge to those skilled in the art. The protection scope of the present application is subject to the content of the claims, and any equivalent transformation based on the technical inspiration of the present application is also within the protection scope of the present application.

Claims

1. A method for testing a multi-directional dynamic vibration absorber of a spacecraft reaction flywheel, characterized in that: It includes a structural support plate, fixing screws, mounting threaded columns, sliders, a dynamic mass block, and a rubber ball. The six structural support plates are formed into a symmetrical cubic structure by fixing screws and are fixed to the mounting bracket by mounting threaded columns and nuts. A slide groove is provided on the inner side of the structural support plate, and the slider is located in the slide groove and can move along the vertical direction of the slide groove. The dynamic mass block is located in the cube, and the six faces of the dynamic mass block and the faces corresponding to the six sliders are all provided with inner conical surfaces. The rubber ball is located between the inner conical surface of the dynamic mass block and the inner conical surface of the slider. A threaded hole is provided at the center of the outer side surface of each of the structural support plates for installing a compression adjustment screw, and a slide groove is provided at the center of the inner side surface of each of the structural support plates, and the slider is located in the slide groove; S1. Perform micro-vibration testing on the reaction flywheel, analyze the main modal vibration frequency domain of the reaction flywheel, and record the main frequency bands of the disturbance in all directions; S2. Select the mass of the dynamic vibration absorber's moving mass based on the overall mass requirement of the reaction flywheel and calculate the mass ratio of the reaction flywheel to the dynamic vibration absorber. Calculate the desired tuning frequency of the dynamic vibration absorber based on optimal coherence theory. S3. Construct a finite element model to optimize the design parameters of the dynamic vibration absorber. Simulate and obtain the fundamental frequency of the entire dynamic vibration absorber, ensuring that the main modal frequency of the reaction flywheel is within the tunable frequency band. Determine the structural parameters of the dynamic vibration absorber. S4. Calculate the contact stiffness of the dynamic vibration absorber to check the vibration absorption frequency; use the two-degree-of-freedom dynamic vibration absorption model numerical simulation to verify the vibration reduction effect of the dynamic vibration absorber.

2. The method for testing a spacecraft reaction flywheel multi-directional dynamic vibration absorber according to claim 1, characterized in that: The structural support plate is made of aluminum alloy, the rubber ball is made of nitrile rubber, and the dynamic mass block is made of high-density brass.

3. The method for testing a spacecraft reaction flywheel multi-directional dynamic vibration absorber according to claim 1, characterized in that: The rubber ball provides damping for the dynamic vibration absorber by its own damping. The stiffness generated by the contact between the rubber ball and the inner conical surface and the stiffness generated by the rubber ball itself under pressure serve as the stiffness of the dynamic vibration absorber. The dynamic mass block serves as the dynamic mass of the dynamic vibration absorber.

4. The method for testing a spacecraft reaction flywheel multi-directional dynamic vibration absorber according to claim 1, characterized in that: The sliding block is provided with an inner conical surface, and each surface of the dynamic mass block is also provided with an inner conical surface, and the structural parameters of the two inner conical surfaces are consistent.

5. The method for testing a spacecraft reaction flywheel multi-directional dynamic vibration absorber according to claim 4, characterized in that: The cube structure envelope is composed of a structural support plate. In the one-way structure, the slider is pushed to move in the slide groove by symmetrically adjusting the screw-in depth of the compression adjustment screw, so that the conical surface inside the slider compresses the rubber ball to change the internal contact state of the one-way dynamic vibration absorber, and the fundamental frequency of the dynamic vibration absorber changes, thereby achieving the purpose of tuning.

6. The method for testing a spacecraft reaction flywheel multi-directional dynamic vibration absorber according to claim 1, characterized in that: The calculation formula of the one-way contact stiffness of the dynamic vibration absorber is as follows: ； ； ； The six structural support plates are assembled into a cube-shaped symmetrical structure by fixing screws and regarded as the main structure; the contact half-width between the rubber ball and the conical ring surface of the inner cone is , the radius of the rubber ball is , is the semi-cone angle of the inner cone, is the axial pressure provided by the main structure, 、 、 、 are the elastic modulus and Poisson's ratio of the main structure and rubber ball, is the equivalent elastic modulus; r Calculate the distance from the contact point to the contact center for the contact surface, z is the normal distance from the calculation point to the origin.

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