A design method for low-cost structural simulation star

Abstract

A method for designing a low-cost structural simulation satellite, by designing the structural simulation satellite configuration, determining adjustable variables, selecting design parameters, performing structural detail design, completing static analysis and sinusoidal vibration analysis, performing cabin plate and screw strength verification, and completing the drawing of relevant design drawings of the structural simulation satellite, counterweights, and slings, solves the problems of high manufacturing cost in conducting satellite-rocket joint tests using existing methods, and significant differences between the satellite-rocket interface, longitudinal fundamental frequency, center of mass position, geometric shape, etc. and real satellites.

Description

Technical Field

[0001] The invention relates to a design method for a low-cost structural simulation satellite, and belongs to the field of satellite-rocket combined mechanical test design. Background Art

[0002] The satellite-rocket joint mechanical test is a critical large-scale ground verification test in the development process of new launch vehicles and upper stages. It includes full-rocket modal tests, sinusoidal vibration tests of upper stages and satellite assemblies, etc. The results and accuracy of the satellite-rocket joint mechanical test directly affect the accuracy of the dynamic load identification of the rocket and upper stage, the accuracy of the structural input parameters of the rocket and upper stage control system, and directly determine the success or failure of the rocket and upper stage launch. In view of the importance of the satellite-rocket joint mechanical test, the rockets, upper stages and satellites participating in the test should use prototype structural parts with the same mechanical properties as the model prototype. For example, my country's manned launch vehicle uses the real structural parts of the Shenzhou spacecraft and the launch vehicle to carry out full-rocket modal tests.

[0003] However, due to the long cycle of full-rocket modal testing (usually up to several months or even a year) and the high manufacturing cost of the satellite composite main structure, it is not always possible to conduct full-rocket modal testing using a real composite satellite structure in terms of time and cost. When the real structure of the satellite is not available, only satellite simulation parts can be used to carry out satellite-rocket joint testing. At present, satellite simulation parts are generally developed by the launch vehicle developer, mainly used to simulate the mass and fundamental frequency of the satellite, and have the following disadvantages:

[0004] (1) The satellite-rocket interface is different from the real satellite, so the real satellite adapter cannot be installed, and the impact of the mass and stiffness of the satellite adapter on the satellite-rocket joint test cannot be considered;

[0005] (2) The fundamental frequency has a large error with the real satellite. The satellite simulation can usually only simulate the first-order fundamental frequency in the horizontal direction, but has a large error with the real satellite in the first-order fundamental frequency in the vertical direction.

[0006] (3) The center of mass is different from that of the real satellite. Even if the mass and fundamental frequency of the satellite simulation are close to those of the real satellite, the difference in the center of mass will cause the mechanical properties of the satellite-rocket combination, especially the combination of the satellite and the upper stage, to deviate from those of the real product.

[0007] (4) The satellite geometry is significantly different from that of real satellites;

[0008] (5) Satellite simulation parts are usually not strength-checked according to the quasi-static load settings of real satellites. Their mechanical properties may be significantly different from those of real satellites. They cannot replace real satellites to carry out joint sinusoidal vibration tests with upper stages. Summary of the invention

[0009] The technical problem solved by the present invention is: in view of the problems in the current prior art that the existing methods for conducting satellite-rocket joint tests have high manufacturing costs, and that the satellite-rocket interface, longitudinal fundamental frequency, center of mass position, geometric shape, etc. are greatly different from those of real satellites, a design method for a low-cost structural simulation satellite is proposed.

[0010] The present invention solves the above technical problems by the following technical solutions:

[0011] A design method for a low-cost structural simulation star, the steps are as follows:

[0012] (1) According to the mass and stiffness characteristics of the actual satellite launch state, determine the mass, center of mass position, transverse fundamental frequency, and longitudinal fundamental frequency parameters of the structural simulation satellite;

[0013] (2) Design the structure simulation satellite configuration based on the actual satellite structure configuration and select the processing materials for the structure simulation satellite;

[0014] (3) Using the command stream modeling method to compile a parametric modeling program, the in-satellite configuration parameters of the structural simulation star and the non-structural mass distribution parameters of each cabin are set as adjustable variables;

[0015] (4) According to the design task requirements of the structural simulation star, select design parameters, establish a finite element model of the structural simulation star through a parametric modeling program, and determine the parameter indicators;

[0016] (5) Carry out structural detail design according to the design task requirements of the structural simulation star;

[0017] (6) Based on the satellite quasi-static design load conditions and sinusoidal vibration test conditions given by the launch vehicle, static analysis and sinusoidal vibration analysis are performed on the structural simulation satellite, and the strength of the cabin plate and screws is checked;

[0018] (7) Design the structural simulation star lifting interface and supporting lifting equipment, and conduct static analysis of the lifting state and the parking state of the support vehicle;

[0019] (8) Complete the design drawings of the structural simulation star, counterweight block, and sling.

[0020] In the step (2), the design method of the structural simulation satellite configuration is specifically as follows: the star body dimensions and the satellite-rocket interface of the structural simulation satellite are consistent with those of the real satellite; the extra-satellite accessories such as solar wings and antennas, as well as the intra-satellite accessories such as gas cylinders and tanks are eliminated, and the extra-satellite accessories and the intra-satellite equipment and chemical propellants are simulated by the weight of the cabin plate and the weight of the counterweight block; a circle of reinforcing ribs are arranged on the cabin plate to increase the local vibration frequency of the cabin plate; the intra-satellite configuration of the structural simulation satellite can be freely adjusted based on the design of the intra-satellite configuration of the real satellite, such as dividing the load-bearing cylinder into upper and lower sections, and the diameter and height of each section of the load-bearing cylinder, the thickness of each cabin plate, and the cross-sectional dimensions of the reinforcing ribs on the cabin plate can be adjusted;

[0021] The method for selecting processing materials for the structural simulation satellite is as follows: the material at the satellite-rocket interface is consistent with the real satellite, and steel is selected for the rest of the structural simulation satellite.

[0022] In step (4), the parameter index determination is specifically as follows:

[0023] Perform mass characteristic analysis and finite element modal analysis. If the mass, center of mass position, transverse and longitudinal fundamental frequencies of the structural simulation star meet the design index requirements, solidify the structural parameters selected in step 3; otherwise, adjust the structural parameters and return to step (3) until the mass, center of mass position, transverse and longitudinal fundamental frequencies meet the design index requirements;

[0024] The principles for selecting the initial values ​​of structural parameters are as follows: the thickness of the cabin plate should be selected from the standard steel plate thickness specification model table as much as possible to save costs; for the structural simulation star with a central bearing tube, the diameter of the lower section of the bearing tube is determined by the diameter of the actual star-rocket interface; the diameter of the upper section of the bearing tube is smaller than the actual bearing tube diameter.

[0025] In step (5), the structural details are specifically designed as follows:

[0026] Determine the design of the counterweight position, the connection design of the angle strips and screws between the cabin plates, and the design of the operation holes, and optimize the finite element model based on the determined design parameters;

[0027] The design principle of the counterweight position is: the fixed counterweight is designed inside the structure simulation star, and the counterweight that may be adjusted later is designed outside the structure simulation star to facilitate the adjustment of the counterweight;

[0028] The design principle of the operation hole is: refer to the configuration of the real satellite, and open a circular or semicircular and rectangular combination of operation holes on the +X and -X cabin panels. The area is based on the convenience of structural assembly operations.

[0029] In step (6), the sinusoidal vibration test conditions can be tailored according to the design status of the real satellite, and the analysis results of the static analysis and the sinusoidal vibration analysis are valid when the structural strength of the structural simulation satellite is not lower than that of the real satellite.

[0030] In step (7), the design principle of the lifting interface structure is: the lifting point is selected at the connection between the outer surface of the plate on the structural simulation star and the main load-bearing structure, the number of lifting points is 4, and the load condition of the lifting static analysis is longitudinal 1.3g multiplied by 2 times the safety factor.

[0031] The advantages of the present invention compared with the prior art are:

[0032] (1) The present invention provides a design method for a low-cost structural simulation satellite. The structural simulation satellite is mainly made of steel, which is easy to process and produce compared to a real structural satellite. The cost is one order of magnitude lower than that of a real structural satellite made of composite materials. At the same time, the satellite-rocket interface is completely consistent with the real satellite. In the satellite-rocket joint mechanical test, the real satellite adapter can be matched and installed, so the influence of the mass and stiffness of the satellite adapter on the satellite-rocket joint test can be considered.

[0033] (2) Compared with existing satellite simulation parts, the present invention adopts model simulation, which can not only simulate the first-order lateral fundamental frequency of the satellite, but also simulate the first-order longitudinal fundamental frequency of the satellite, thereby reducing the error of the satellite-rocket joint mechanical test. At the same time, it can also simulate the strength of the satellite and can be used to cooperate with the upper stage to carry out sinusoidal vibration tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A flow chart of the design method provided for the invention;

[0035] Figure 2 A schematic diagram of the main structural configuration of the structural simulation star provided for the invention;

[0036] Figure 3 A perspective view of a preliminary finite element model provided for the invention;

[0037] Figure 4 A schematic diagram of the middle plate connection and counterweight distribution of the structure simulation star provided by the invention;

[0038] Figure 5 A schematic diagram of the final finite element model of the structural simulation star provided for the invention;

[0039] Figure 6 A schematic diagram of the upper plate connection and counterweight distribution of the structural simulation star provided by the invention; DETAILED DESCRIPTION

[0040] A design method for a low-cost structural simulation satellite is low in cost, and the satellite-rocket interface, center of mass position, geometric shape and other aspects are slightly different from the real satellite, which can improve the accuracy of the satellite-rocket joint mechanical test results. The specific method steps are as follows:

[0041] (1) Determine the mass, center of mass position, and lateral fundamental frequency parameters of the structural simulation satellite based on the mass and stiffness characteristics of the real satellite;

[0042] (2) Design a structural simulation satellite configuration based on the actual satellite structure configuration;

[0043] (3) Using the command stream modeling method, a parametric modeling program is compiled to set the diameter, height, deck thickness, stiffener section, and non-structural mass distribution parameters of the upper and lower load-bearing cylinders in the structural simulation star as adjustable variables;

[0044] (4) According to the design task requirements of the structural simulation star, select design parameters, establish a finite element model of the structural simulation star through a parametric modeling program, and determine the parameter indicators;

[0045] (5) Carry out structural detail design according to the design task requirements of the structural simulation star;

[0046] (6) Based on the satellite quasi-static design load conditions and sinusoidal vibration test conditions given by the launch vehicle, static analysis and sinusoidal vibration analysis are performed on the structural simulation satellite, and the strength of the cabin plate and screws is checked;

[0047] (7) Design the structural simulation star lifting interface and supporting lifting equipment, and conduct static analysis of the lifting state and the parking state of the support vehicle;

[0048] (8) Complete the design drawings of the structural simulation star, counterweight block, and sling;

[0049] Among them, in step (4), the parameter index determination is specifically as follows:

[0050] Perform modal analysis. If the mass, center of mass position, and lateral fundamental frequency all meet the design index requirements, solidify the structural parameters selected in step 3; otherwise, adjust the structural parameters and return to step (3) until the mass, center of mass position, and lateral fundamental frequency all meet the design index requirements;

[0051] In step (5), the structural detail design is specifically as follows:

[0052] Determine the design of the counterweight position, the connection design of the angle strips and screws between the cabin plates, and the design of the operation holes, and optimize the finite element model based on the determined design parameters;

[0053] In step (6), the sinusoidal vibration test conditions can be tailored according to the design status of the real satellite, and the analysis results of the static analysis and the sinusoidal vibration analysis are valid when the structural strength of the structural simulation satellite is not lower than that of the real satellite;

[0054] In step (7), the design principle of the lifting interface structure is: the lifting point is selected at the connection between the outer surface of the plate on the structural simulation star and the main load-bearing structure, the number of lifting points is 4, and the load condition of the lifting static analysis is longitudinal 1.3g multiplied by 2 times the safety factor.

[0055] The following is further described in conjunction with specific embodiments:

[0056] In the current embodiment, the process is as follows Figure 1 As shown, the technical solutions are as follows:

[0057] Step 1: According to the mass and stiffness characteristics of the real satellite, determine the design indicators such as the mass, center of mass position, and transverse fundamental frequency of the structural simulation satellite; for example, the mass is 3500±100kg, the center of mass height is 1.3±0.1m, the transverse first-order fundamental frequency is 20±3Hz, and the longitudinal first-order fundamental frequency is 50±5Hz;

[0058] Step 2: Design a structure to simulate the satellite configuration by referring to the structure of the real satellite. Figure 2 As shown in the figure, the structural simulation satellite configuration of the segmented central bearing tube plus box plate structure; the outer dimensions of the box plate are the same as those of the real satellite body structure, and the satellite-rocket interface of the lower bearing tube is the same as that of the real satellite; except that the satellite-rocket docking frame is made of aluminum alloy, which is consistent with the original satellite, the materials used for the rest of the structural simulation satellite are all steel; in order to ensure that the upper cabin plate has a fundamental frequency greater than the first-order lateral fundamental frequency of the entire satellite, a circle of reinforcing ribs is designed on the upper cabin plate;

[0059] Step 3: Use the command flow modeling method to compile a parametric modeling program in the commercial finite element software, and set the structural parameters such as the upper and lower load-bearing cylinder diameters, heights, deck thickness, stiffener cross-sections, and non-structural mass distribution of each deck as adjustable variables;

[0060] Step 3: In commercial finite element software, use the command flow modeling method to compile a parametric modeling program. The following takes MSC.Patran software as an example to explain the main process of programming using its PCL language:

[0061] A: Use the Real command to define the names and initial values ​​of the adjustable variables of the structure simulation star, such as the diameter of the upper and lower bearing cylinders, the height of each bearing cylinder, the thickness of each deck, the non-structural mass of each deck, the cross-sectional size of the stiffener, etc.;

[0062] B: Use the material.create command to define the materials used for the structure simulation satellite, where the satellite-rocket interface is made of aluminum alloy, and the remaining bearing cylinders and cabin plates are made of steel plates;

[0063] C: Use the beam_section_create command to define the cross-sectional shape and size of the reinforcement of the structural simulation star;

[0064] D: Use ga_group_create to create the "upper plate" group, and then use asm_const_grid_xyz, asm_const_line_2point, sgm_const_surface_2curve and other commands to create the geometric plane of the "upper plate" in the form of points, lines, and surfaces. Use fem_create_mesh_surf_4 command to make a quadrilateral shell unit mesh for the "upper plate", and use elementprops_create command to assign material properties and unit thickness to the finite element model of the "upper plate".

[0065] E: Similarly, the grouping, geometric plane, and finite element model of other cabin plates and upper and lower load-bearing cylinders are established in turn; in order to reduce the lateral fundamental frequency of the entire satellite, the lower plate is not connected to the lower load-bearing cylinder;

[0066] F: Use the fem_equiv_all_group4 command to merge the repeated finite element nodes; connect the cabin plates in a common node manner;

[0067] Step 4: Rationally select design parameters, use parametric modeling program in commercial finite element software to quickly establish finite element model of structure simulation star and conduct mass characteristic analysis and modal analysis; if mass, center of mass position and lateral fundamental frequency meet the design index requirements, solidify the structural parameters selected in step 3 and obtain Figure 3 The finite element model shown in the figure is as follows; otherwise, adjust the structural parameters and repeat steps three and four until the requirements are met; the main structural parameters of the optimized structure of this example are: the diameter of the upper bearing cylinder is 711mm, the height is 2600mm, the diameter of the lower bearing cylinder is 1194mm, the height is 600mm, the distance between the middle plate and the lower plate is 500mm; the steel plate thickness of the upper plate, middle plate and lower plate is 10mm, and the steel plate thickness of the remaining cabin plates is 6mm; the hollow rectangular beam with a stiffener section of 60mm x 60mm and a thickness of 4mm; the non-structural mass (total mass of the counterweight block) of the upper plate, middle plate and lower plate is 200kg, 400kg and 400kg respectively.

[0068] Step 5: Carry out detailed design of the structural simulation star, including the position design of the counterweight block, the connection design of the angle strips and screws between the cabin plates, the design of the operation holes, etc., and refine the finite element model according to the detailed design results; in this example, there are three types of counterweight blocks of 5kg, 15kg, and 30kg distributed on the upper plate, middle plate, lower plate and other cabin plates, totaling 1000kg. Figure 4 As shown in the figure, the distribution design of the configuration blocks on the upper surface of the middle plate and the corner strip and screw connection design of the cabin plate; Figure 5 As shown, the main operating hole locations of the structural simulation star are given through a refined finite element model, which are mainly distributed on the upper cabin plates on the +X and -X sides of the satellite.

[0069] Step 6. If the structural simulation satellite is to carry out sinusoidal vibration test with the upper stage, it is necessary to use commercial finite element software to perform static analysis and sinusoidal vibration analysis on the structural simulation satellite according to the satellite quasi-static design load conditions and sinusoidal vibration test conditions given by the launch vehicle, and perform cabin plate and screw strength verification; the quasi-static design load is generally multiplied by a safety factor ranging from 1.2 to 1.5. This example selects a 1.5 times safety factor, and the final calculation condition is shown in Table 1, where the positive sign in the Z-direction load indicates compression and the negative sign indicates tension; the sinusoidal vibration test conditions can be tailored according to the design status of the real satellite; the final analysis result must ensure that the structural strength of the structural simulation satellite is not lower than that of the real satellite;

[0070] The quasi-static design load table of the structural simulation star is as follows:

[0071] direction Condition 1 Condition 2 Condition 3 Condition 4 Condition 5 Condition 6 Z direction (g) +4.5 +4.5 +9.15 +9.15 -3.9 -3.9 X direction (g) 2.25 0 1.5 0 1.5 0 Y direction (g) 0 2.25 0 1.5 0 1.5

[0072] Step 7: Design the structural simulation star lifting interface and supporting lifting equipment, and conduct static analysis of the lifting state and the parking state of the support vehicle; Figure 6 As shown, in this example, the lifting interface of the structural simulation star is designed as four "cross"-shaped channel steels on the outer surface of the upper plate. The four channel steels are respectively installed on the outer sides of the four upper partitions in the ±X and ±Y directions. Each channel steel has a circular hole with a diameter of 20 mm on its two side bars. An M20 screw (made of steel) is passed through the circular hole, and the middle of the four M20 screws is the lifting point.

[0073] Step 8. Complete the design drawings of the structural simulation star, counterweight block, and sling.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0075] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A design method for a low-cost structural simulation star, characterized in that Here are the steps: (1) Determine the mass, center of mass position, transverse fundamental frequency, and longitudinal fundamental frequency parameters of the structural simulation satellite based on the mass and stiffness characteristics of the actual satellite launch state; (2) Design the structure simulation star configuration based on the actual satellite structure configuration and select the processing materials for the structure simulation star; (3) Using the command stream modeling method, a parametric modeling program is compiled to set the internal configuration parameters of the structural simulation star and the non-structural mass distribution parameters of each cabin as adjustable variables; (4) According to the design task requirements of the structural simulation star, select design parameters, establish a finite element model of the structural simulation star through a parametric modeling program, and determine the parameter indicators; In step (4), the parameter index determination is specifically as follows: Perform mass characteristic analysis and finite element modal analysis. If the mass, center of mass position, transverse and longitudinal fundamental frequencies of the structural simulation star meet the design index requirements, solidify the structural parameters selected in step 3; otherwise, adjust the structural parameters and return to step (3) until the mass, center of mass position, transverse and longitudinal fundamental frequencies meet the design index requirements; The principles for selecting the initial values ​​of structural parameters are: the thickness of the cabin plate is selected from the standard steel plate thickness specification model table to save costs; for the structural simulation star with a central bearing cylinder, the diameter of the lower bearing cylinder is determined by the diameter of the real star-rocket interface; the diameter of the upper bearing cylinder is smaller than the diameter of the real bearing cylinder; (5) Carry out structural detail design according to the design task requirements of the structural simulation star; In step (5), the structural detail design is specifically as follows: Determine the design of the counterweight position, the connection design of the angle strips and screws between the cabin plates, and the design of the operation holes, and optimize the finite element model based on the determined design parameters; The design principle of the counterweight position is: the fixed counterweight is designed inside the structure simulation star, and the counterweight that may be adjusted later is designed outside the structure simulation star to facilitate the adjustment of the counterweight; The design principle of the operation hole is: refer to the configuration of the real satellite, open a circular or semicircular and rectangular operation hole on the +X and -X cabin plates, and the area should be based on the convenience of structural assembly operation; (6) Based on the satellite quasi-static design load conditions and sinusoidal vibration test conditions given by the launch vehicle, static analysis and sinusoidal vibration analysis are performed on the structural simulation satellite, and the strength of the cabin plate and screws is checked; (7) Design the structural simulation star lifting interface and supporting lifting equipment, and conduct static analysis of the lifting state and the parking state of the support vehicle; (8) Complete the design drawings of the structural simulation star, counterweight block, and sling.

2. The design method of a low-cost structural simulation star according to claim 1, characterized in that: In the step (2), the design method of the structure simulation satellite configuration is specifically as follows: the star body dimensions and the satellite-rocket interface of the structure simulation satellite are consistent with those of the real satellite; the solar wing, antenna, gas cylinder, and tank are eliminated, and the satellite internal and external accessories, satellite internal equipment, and chemical propellant are simulated by the weight of the cabin plate and the weight of the counterweight block; a circle of reinforcing ribs are arranged on the cabin plate to increase the local vibration frequency of the cabin plate; the internal configuration of the structure simulation satellite is freely adjusted based on the internal configuration design of the real satellite; The method for selecting processing materials for the structural simulation satellite is as follows: the material at the satellite-rocket interface is consistent with the real satellite, and steel is selected for the rest of the structural simulation satellite.

3. The design method of a low-cost structural simulated star according to claim 1, characterized in that: In step (6), the sinusoidal vibration test conditions are tailored according to the design status of the real satellite, and the analysis results of the static analysis and the sinusoidal vibration analysis are valid when the structural strength of the structural simulation satellite is not lower than that of the real satellite.

4. The design method of a low-cost structural simulation star according to claim 1, characterized in that: In step (7), the design principle of the lifting interface structure is: the lifting point is selected at the connection between the outer surface of the plate on the structural simulation star and the main load-bearing structure, the number of lifting points is 4, and the load condition of the lifting static analysis is 1.3g in the longitudinal direction multiplied by 2 times the safety factor.

Images