A method and system for calculating the scanning rate of a reusable spacecraft sine vibration test

Abstract

The application discloses a kind of reuse spacecraft sinusoidal vibration test scanning rate calculation method and system, comprising: selecting observation point on spacecraft, obtaining scanning rate and frequency domain sinusoidal vibration condition;The frequency domain sinusoidal vibration condition is converted into time domain sinusoidal vibration condition;Time history analysis is carried out to observation point, and stress time domain response is obtained;The rainflow counting is carried out to the stress time domain response, and rainflow counting result is obtained;Single fatigue damage of observation point is calculated;M fatigue damage of observation point is calculated;The scanning rate of the observation point is adjusted, and the scanning rate when single test fatigue damage is equal to M fatigue damage of the observation point is calculated;The relationship between scanning rate and spacecraft reuse frequency is obtained, for calculating the test scanning rate corresponding to any reuse frequency.The application realizes once test to check multiple flights, avoids the damage risk of multiple tests to product, and can provide support for the development of reusable spacecraft.

Description

Technical Field

[0001] This invention relates to a method and system for calculating the scan rate of sinusoidal vibration tests on reusable spacecraft, belonging to the field of vibration dynamics analysis of reusable spacecraft. Background Technology

[0002] In recent years, reusable spacecraft have seen rapid development both domestically and internationally. SpaceX's Dragon spacecraft, Falcon 9 rocket, and my country's new-generation spacecraft have all made significant progress in recent years, attracting widespread attention, especially due to their reusability. At the same time, reusable spacecraft, by undergoing multiple launch and return phases, face higher requirements for vibration conditions.

[0003] Spacecraft mechanical environment testing is an essential part of all spacecraft development, and sinusoidal vibration testing is one of the main components of this testing. Sinusoidal vibration test conditions are a crucial part of the mechanical environment for reusable spacecraft. Traditional design methods for expendable spacecraft sinusoidal vibration test conditions involve extracting the envelope from satellite-launch coupling load analysis and flight telemetry data through statistical analysis and impact response spectrum transformation. This design method inherently carries a tendency to "over-test," increasing development costs. Its design logic is "one test, one flight."

[0004] In the development of reusable spacecraft, testing needs to cover multiple dynamic environments. If the traditional logic is followed, it becomes "multiple tests, multiple flights," simply repeating the tests corresponding to a single launch. The test time will increase by M times with the number of reuses (M), and the test cost will increase dramatically. If M is large, such as M = 10, 50, 100… the test cost will rise to an unacceptable or even unfeasible level with the number of reuses (M). In short, the experience in developing traditional single-use spacecraft is very limited and can hardly support the development of reusable spacecraft.

[0005] Therefore, there is an urgent need to propose a design method for sinusoidal vibration test conditions of reusable spacecraft, reducing test costs and logically transforming the process into "one test evaluating multiple flights." Among these, the scan rate is the core parameter of the sinusoidal vibration test conditions, and also the most difficult to obtain, requiring in-depth research and calculation. Once the scan rate is determined, the sinusoidal vibration test conditions are essentially determined as well.

[0006] Traditional experience in developing disposable spacecraft has become extremely limited and cannot provide sufficient support. Domestic research foundation is weak, and no publicly available literature reports on this topic. Summary of the Invention

[0007] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a method and system for calculating the scan rate of sinusoidal vibration tests on reusable spacecraft, enabling multiple flights to be tested in a single test, avoiding the risk of damage to the product from multiple tests, reducing development costs, shortening product testing time, and improving development efficiency.

[0008] The technical solution of this invention is:

[0009] This invention discloses a method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft, characterized by comprising:

[0010] (1) Select observation points on the spacecraft to obtain the scan rate and frequency domain sinusoidal vibration conditions;

[0011] (2) Based on the scan rate, the frequency domain sinusoidal vibration condition is converted into a time domain sinusoidal vibration condition;

[0012] (3) Based on the time-domain sinusoidal vibration conditions, time history analysis is performed on the observation points to obtain the stress time-domain response;

[0013] (4) Perform rainflow counting on the stress time-domain response to obtain the rainflow counting results;

[0014] (5) Calculate the single fatigue damage at the observation point based on the rainflow counting results and the SN curve of the material;

[0015] (6) Calculate the M fatigue damages at the observation point based on the single fatigue damage;

[0016] (7) Adjust the scanning rate of the observation point and repeat steps (2) to (5) until the fatigue damage in a single test is equal to the fatigue damage in M ​​tests at the observation point, and obtain the adjusted scanning rate.

[0017] (8) Based on the adjusted scan rate, obtain the relationship between the scan rate and the number of times the spacecraft can be reused, and use it to calculate the test scan rate corresponding to any number of reuses.

[0018] In the above scan rate calculation method, step (2) converts the frequency domain sinusoidal vibration condition into a time domain sinusoidal vibration condition. The specific method is as follows:

[0019]

[0020]

[0021] R=2 n

[0022] Where n is the scan rate; R is the octave band; f0 is the lower frequency limit of the sine wave test; φ is the phase at a certain moment; t is a certain moment; M fThe amplitude of the frequency domain curve is a function of frequency f, and the corresponding curve represents the sinusoidal vibration condition in the frequency domain; M t The amplitude of the time-domain curve is a function of time t, and the corresponding curve represents the time-domain sinusoidal vibration condition.

[0023] In the above scan rate calculation method, step (3) involves performing time history analysis on the observation point based on the time-domain sinusoidal vibration condition to obtain the stress time-domain response. The specific method is as follows:

[0024] Based on the spacecraft structure, a finite element model of the spacecraft is established. The parts of the spacecraft connected to the vibration table and fixture are fixed and constrained. The sinusoidal vibration condition in the time domain is used as the load to perform vibration time domain response analysis, complete the time history analysis, and obtain the stress time domain response.

[0025] In the above scan rate calculation method, step (4) involves performing rainflow counting on the stress time-domain response to obtain the rainflow counting results. The specific method is as follows:

[0026] Using a rainflow counting algorithm, the same stress time-domain response is grouped into the same group, forming several groups of response results;

[0027] Several sets of response results are plotted into a bar chart to obtain the rainflow count results. The horizontal axis of the bar chart represents the data size of each group, and the vertical axis of the bar chart represents the number of response results in each group.

[0028] Based on the rainflow count, the actual number of load cycles is obtained.

[0029] In the above scan rate calculation method, step (5) calculates the single fatigue damage at the observation point based on the rainflow count results and the SN curve of the material. The specific method is as follows:

[0030] D = n1 / N1 + n2 / N2 + n3 / N3 + ... + n i / N i

[0031] Where D represents single-instance fatigue damage, and n i The stress at the observation point is S. i The actual number of load cycles, N i S on the SN curve of the corresponding material i The corresponding fatigue life, where i = 1, 2, 3, ...

[0032] In the above scanning rate calculation method, step (6) calculates the M fatigue damages at the observation point based on the single fatigue damage. The specific method is as follows:

[0033] D m =M×D

[0034] Among them, D m Let M represent fatigue damage, D represent single fatigue damage, and M represent the number of tests.

[0035] In the above scan rate calculation method, step (7) adjusts the scan rate of the test observation point so that the fatigue damage in a single test is equal to the M fatigue damages at the observation point, thus obtaining the adjusted scan rate. The specific method is as follows:

[0036] S71: Based on the simulation results of fatigue damage and scan rate at multiple observation points, the formula for the relationship between scan rate n and fatigue damage f(n) is obtained.

[0037] S72: Solve the equation g(n)=f(n)-D according to the relational formula. m =0, where D m The fatigue damage is measured in M ​​tests.

[0038] S73: Plot the curve showing the relationship between g(n) and n;

[0039] S74: According to the relational formula curve, take (n0, g(n0)) as the tangent line, and the tangent line intersects the coordinate horizontal axis at the point (n1, 0); draw the tangent line again through (n1, g(n1));

[0040] S75: Repeat step S74 to calculate the scan rate n when g(n) = 0.

[0041] In the above scan rate calculation method, the relationship between the scan rate and the number of times the spacecraft can be reused is obtained based on the adjusted scan rate, as shown in the formula:

[0042] nM b =c

[0043] Where b and c are constants, M is the number of times the spacecraft can be reused, and n is the adjusted scan rate.

[0044] In the above method for calculating the scan rate, the formula relating the scan rate n to the fatigue damage f(n) is as follows:

[0045] f(n)=a×ln(n)+d / (n 2 )+h

[0046] Where f(n) represents fatigue damage, n is the scan rate; a, d, and h are all constants; ln(n) represents the logarithm of n to the base e.

[0047] This invention discloses a system for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft, comprising:

[0048] Time-frequency conversion module: Selects an observation point on the spacecraft to obtain the scan rate and frequency domain sinusoidal vibration conditions; converts the frequency domain sinusoidal vibration conditions into time domain sinusoidal vibration conditions based on the scan rate; and sends the time domain sinusoidal vibration conditions to the stress response calculation module.

[0049] Stress response calculation module: Based on the time-domain sinusoidal vibration conditions sent by the time-frequency conversion module, the module performs time history analysis on the observation points to obtain the stress time-domain response; and sends the stress time-domain response to the fatigue damage calculation module.

[0050] Fatigue damage calculation module: Performs rainflow counting on the stress time-domain response sent by the stress response calculation module to obtain rainflow counting results; calculates single-fatigue damage at the observation point based on the rainflow counting results and the material's SN curve; calculates M-times fatigue damage at the observation point based on the single-fatigue damage; calculates the scan rate when the single-test fatigue damage equals the M-times fatigue damage; obtains the relationship between the scan rate and the number of times the spacecraft can be reused based on the adjusted scan rate, which is used to calculate the test scan rate corresponding to any number of reuses.

[0051] The advantages of this invention over the prior art are as follows:

[0052] (1) This invention proposes a method for calculating sinusoidal vibration scanning rate, enabling multiple flights to be tested in one test, avoiding the risk of damage to the product from multiple tests, significantly reducing development costs, shortening product testing time, and improving development efficiency. It can be used to guide the design of sinusoidal vibration test conditions for reusable spacecraft and has strong engineering innovation and practicality.

[0053] (2) This invention can be widely applied to the mechanical testing of reusable spacecraft, providing a reference for the design of mechanical testing conditions for spacecraft; in addition to sinusoidal vibration testing, it can also be applied to the assessment of random vibration testing, noise testing and shock testing of reusable spacecraft; it can greatly reduce the test cycle of each stage, reduce test risks and improve test results. Attached Figure Description

[0054] Figure 1 This is a flowchart of the calculation method of the present invention;

[0055] Figure 2 This is a schematic diagram of the flat panel of the present invention;

[0056] Figure 3 (a) represents the sinusoidal vibration condition of this invention; (b) represents the frequency domain vibration condition; and (c) represents the time domain load.

[0057] Figure 4 The results of the stress response rainflow counting in this invention are shown; (a) is the amplitude, and (b) is the mean.

[0058] Figure 5 The SN curve obtained by fitting the experimental data of this invention;

[0059] Figure 6 This is a curve showing the fatigue damage and scanning rate of the present invention. Detailed Implementation

[0060] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] The embodiments of the present invention will be further described below with reference to the accompanying drawings. These descriptions are merely exemplary and are not intended to limit the scope of protection of the present invention.

[0062] This invention discloses a method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft, comprising:

[0063] Step (1) Select the observation point on the spacecraft and obtain the scan rate and frequency domain sinusoidal vibration conditions;

[0064] Step (2) Based on the scan rate, convert the frequency domain sinusoidal vibration condition into the time domain sinusoidal vibration condition. The specific method is as follows:

[0065]

[0066]

[0067] R=2 n

[0068] Where n is the scan rate; R is the octave band; f0 is the lower frequency limit of the sine wave test; φ is the phase at a certain moment; t is a certain moment; M f The amplitude of the frequency domain curve is a function of frequency f, and the corresponding curve represents the sinusoidal vibration condition in the frequency domain; M t The amplitude of the time-domain curve is a function of time t, and the corresponding curve represents the time-domain sinusoidal vibration condition.

[0069] Step (3) Based on the sinusoidal vibration conditions in the time domain, perform time history analysis on the observation points to obtain the stress time domain response. The specific method is as follows:

[0070] Based on the spacecraft structure, a finite element model of the spacecraft is established. The parts of the spacecraft connected to the vibration table and fixture are fixed and constrained. The time-domain sinusoidal vibration condition is used as the load to perform vibration time-domain response analysis, complete the time history analysis, and obtain the stress time-domain response.

[0071] Step (4) Perform rainflow counting on the stress time-domain response to obtain the rainflow counting results. The specific method is as follows:

[0072] Using the rainflow counting algorithm, the time-domain responses of the same stress are grouped into the same group, forming several groups of response results;

[0073] Several sets of response results are plotted into a bar chart to obtain the rainflow count results. The horizontal axis of the bar chart represents the data size of each group, and the vertical axis of the bar chart represents the number of response results in each group.

[0074] Based on the rainflow count, the actual number of load cycles is obtained.

[0075] Step (5) Calculate the single-cycle fatigue damage at the observation point based on the rainflow count results and the material's SN curve. The specific method is as follows:

[0076] D = n1 / N1 + n2 / N2 + n3 / N3 + ... + n i / N i

[0077] Where D represents single-instance fatigue damage, and n i The stress at the observation point is S. i The actual number of load cycles, N i S on the SN curve of the corresponding material i The corresponding fatigue life, where i = 1, 2, 3, ...

[0078] Step (6) Calculate the M fatigue damages at the observation point based on the single fatigue damage. The specific method is as follows:

[0079] D m =M×D

[0080] Among them, D m Let M represent fatigue damage, D represent single fatigue damage, and M represent the number of tests.

[0081] Step (7) Adjust the scan rate of the observation point, and repeat steps (2) to (5) to make the fatigue damage in a single test equal to the fatigue damage in M ​​tests at the observation point, and obtain the adjusted scan rate. The specific method is as follows:

[0082] Step S71: Based on the simulation results of fatigue damage and scan rate at multiple observation points, obtain the formula relating scan rate n to fatigue damage f(n);

[0083] Step S72: Solve the equation g(n)=f(n)-D according to the relational formula. m =0, where D m The fatigue damage is measured in M ​​tests.

[0084] Step S73: Plot the curve showing the relationship between g(n) and n;

[0085] Step S74: According to the relational formula curve, take (n0, g(n0)) as the tangent line, and the tangent line intersects the coordinate horizontal axis at the point (n1, 0); draw the tangent line again through (n1, g(n1));

[0086] S75: Repeat step S74 to calculate the scan rate n when g(n) = 0.

[0087] Step (8) Based on the adjusted scan rate, obtain the relationship between the scan rate and the number of times the spacecraft can be reused, which is used to calculate the test scan rate corresponding to any number of reuses.

[0088] The formula relating the scan rate n to fatigue damage f(n) is as follows:

[0089] f(n)=a×ln(n)+d / (n 2 )+h

[0090] Where f(n) represents fatigue damage, n is the scan rate; a, d, and h are all constants; ln(n) represents the logarithm of n to the base e.

[0091] This invention discloses a system for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft, comprising:

[0092] Time-frequency conversion module: Selects observation points on the spacecraft to obtain the scan rate and frequency domain sinusoidal vibration conditions; converts the frequency domain sinusoidal vibration conditions into time domain sinusoidal vibration conditions based on the scan rate; and sends the time domain sinusoidal vibration conditions to the stress response calculation module.

[0093] Stress response calculation module: Based on the time-domain sinusoidal vibration conditions sent by the time-frequency conversion module, time history analysis is performed on the observation points to obtain the stress time-domain response; the stress time-domain response is then sent to the fatigue damage calculation module.

[0094] Fatigue damage calculation module: Performs rainflow counting on the stress time-domain response sent by the stress response calculation module to obtain the rainflow counting results; calculates the single-fatigue damage at the observation point based on the rainflow counting results and the material's SN curve; calculates the M-times fatigue damage at the observation point based on the single-fatigue damage; calculates the scan rate when the single-test fatigue damage equals the M-times fatigue damage; and obtains the relationship between the scan rate and the number of times the spacecraft can be reused based on the adjusted scan rate, which is used to calculate the test scan rate corresponding to any number of reuses.

[0095] Example 1

[0096] like Figure 1 The diagram shown is a flowchart of the calculation method of the present invention. The calculation process is explained in detail below; wherein, Figure 1 The first step, the "preprocessing" module, such as Figure 2 As shown, observation points are typically chosen based on the weakest points in the experiment. Modal analysis reveals that the fundamental frequency of the aluminum alloy plate shown in the figure is 23Hz, and the response within the circled area is relatively large. The step of "taking any frequency domain sinusoidal vibration condition and converting it to the time domain" refers to... Figure 3 . Figure 3 (a) represents the vibration test conditions of a satellite, with acceleration and frequency as the physical quantities used as inputs; Figure 3 (b) is the time-domain excitation calculated under this condition, where the physical quantity is acceleration versus time. Wherein, Figure 3 (a) represents the known conditions that are readily available in the project, with a frequency range (horizontal axis) of 5 to 100 Hz. The scan rate for the spacecraft acceptance-level vibration test is 4 (oct / min). Figure 3 (a) represents the curve corresponding to the function M of f. f In this embodiment, the value is:

[0097]

[0098] Where f represents frequency, in Hz; M f This represents the amplitude, measured in grams (g).

[0099] like Figure 1 The "Time History Analysis for Stress Response" step involves performing dynamic simulation calculations (time history analysis) on the plate to obtain the output, which shows the response at node 265, with the physical quantities being stress versus time.

[0100] like Figure 1 The "Discretization: Rainflow Counting" step in the document. (See reference...) Figure 4 (a) and Figure 4 (b) Rainflow counting is performed on the simulation results to obtain a histogram. Rainflow counting is a widely used counting method that can discretize the curve of any physical quantity changing along time, group and statistically analyze it to obtain a histogram, and obtain the actual number of load cycles from the histogram.

[0101] like Figure 1 The section on "Vibration Fatigue Damage" uses Miner's method to calculate fatigue damage based on rainflow counts and the material's SN curve (obtained from material handbooks). The SN curve is only related to the material's intrinsic properties. The material's SN curve can be obtained from material handbooks and literature. Figure 5 The formula for Miner's rule is:

[0102] D = n1 / N1 + n2 / N2 + n3 / N3 + ... + n i / N i (i = 1, 2, 3...)

[0103] Where, n i The physical meaning is the actual number of cycles of a load with stress Si applied to the product, N. i The physical meaning is that on the SN curve of the corresponding material, S i The corresponding fatigue life, that is, once under stress Si The cycle exceeds N under the action i This will damage the product; the data from the completed rainflow counting, each group represents a stress S. i A corresponding fatigue life N can be found on the SN curve. i ; for each stress S i Damage n under action i / N i The total damage, D, is obtained by summing the results.

[0104] The "Single Vibration Fatigue Damage Calculation" module has ended. This yields the data in row 2 of Table 1: when the scan rate is 4 (oct / min), the corresponding fatigue damage is D = 8.47 × 10⁻⁶. -17 Once the frequency range (known, 5–100 Hz) and scan rate are determined, the test time can be uniquely determined.

[0105] Furthermore, Figure 1 The "Obtain Scan Rate" module corresponds to Table 1. Let's take the number of times the tablet can be repeatedly emitted, M, as an example to illustrate the calculation method of the scan rate n (dimension oct / min), as shown in Table 1.

[0106] Table 1. Numerical fitting of scan rate and number of repeated uses in the flat plate sinusoidal sweep frequency test.

[0107]

[0108] The method proposed in this embodiment, which covers the entire product lifecycle with a single test, is defined as method (a), and the method of repeatedly performing sinusoidal tests on traditional spacecraft is defined as method (b). Both are based on the fatigue damage calculation method described above. According to the results of the "Single Vibration Fatigue Damage Calculation" module, the single-instance damage is multiplied by M; therefore, when M = 1 to 10, the damage is D. m = (1~10)×D, which is the result of method (b), and the fatigue damage in column 3 of Table 1 is obtained.

[0109] Adjust the scan rate n of method (a) so that the fatigue damage of method (a) is related to D. m If the values ​​are roughly equivalent, then an appropriate scan rate is considered to have been achieved. In this embodiment, a stepwise approximation method is used to adjust method (a) the scan rate n. The steps are described in detail below. See Figure 6 .

[0110] (1) Assuming the fatigue damage of method (a) is f(n), then when M = 10, after multiple simulations, the relationship between the two can be obtained as f(n) = a × ln(n) + d / (n 2 )+h, where f(n) is fatigue damage and n is the scan rate; a and d are constants; when M=10, a=-10 -15d = 5.28 × 10 -15 h = 10 -15 The problem then becomes: finding the equation f(n) = D m The root. Let g(n) = f(n) - D m The problem then becomes: find the root of the equation g(n) = 0; this equation is difficult to solve analytically directly, but we can refer to Newton's iteration method to gradually approximate the exact solution;

[0111] (2) Select any point on the curve with an abscissa greater than 4 and denote it as (n0, g(n0));

[0112] (3) Let the derivative at this point be g'(n0). Then draw the tangent line L0 through this point: y=g(n0)+(x-n0)g'(n0), and the x-coordinate of the intersection of L0 and the x-axis is x1=n0-g(n0) / g'(n0); it can be seen that in order to find the root of g(n)=0 in step (1), x1 is more accurate than x0;

[0113] (4) Draw the tangent line L1 again through the point (n1, g(n1)): y = g(n1) + (x - n1)g'(n1). The x-coordinate of the intersection of L1 and the x-axis is x2 = n1 - g(n1) / g'(n1). It can be seen that x2 is more accurate than x1 in order to find the root of g(n) = 0 in step (1).

[0114] (5) Draw the tangent line again through the point (n2, g(n2))... Repeat this process k times to obtain the formula: x k+1 =n k -g(n k ) / g'(n k );

[0115] (6) By gradually approximating the exact value, the root of the equation is finally obtained, which is 1.25.

[0116] The significance of gradually approximating the final scan rate is that, for a plate used 10 times in repeated firing, when the scan rate of method (a) is 1.25, the fatigue damage of method (a) and method (b) is roughly equivalent. As shown in Table 1, method (a) takes 207 seconds at this point, saving time compared to 650 seconds for method (b). This invention solves the problem of accurately calculating the scan rate and establishes a functional relationship between the scan rate and fatigue damage.

[0117] When M = 2 to 9, and so on, the corresponding scan rates n can be obtained respectively, forming j sets of data (M j n j j = 1, 2, 3, ..., j ≤ 10. If the horizontal axis is M and the vertical axis is the scan rate n, then j sets of data correspond to j points on the plane. The formula nM is obtained through numerical fitting. b=c. Where b and c are constants. It should be noted that even if j takes any 2 to 3 values ​​from 2 to 9, this formula can still be fitted. The more values ​​j takes, the more accurate the formula becomes.

[0118] Using the formula nM b =c, when M takes any value from 2 to 9 or >10, a suitable scan rate n can be obtained to guide the sinusoidal vibration test. This formula can guide the selection of the core parameter scan rate in the test, thus providing a sinusoidal condition design method, thereby achieving a single test covering the entire product life cycle. Compared with method (b), it can greatly save test time, reduce test costs, and achieve the same assessment effect.

[0119] In practical engineering, the method described in this embodiment can be applied by replacing the flat plate with a reusable spacecraft and taking any value for the number of repetitions M (even if M>10).

[0120] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by the inventive law as long as they are within the scope of the claims of the invention.

Claims

1. A method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft, characterized in that, include: (1) Select observation points on the spacecraft to obtain the scan rate and frequency domain sinusoidal vibration conditions; (2) Based on the scan rate, convert the frequency domain sinusoidal vibration condition into a time domain sinusoidal vibration condition; (3) Based on the time-domain sinusoidal vibration conditions, time history analysis is performed on the observation points to obtain the stress time-domain response; (4) Perform rainflow counting on the stress time-domain response to obtain the rainflow counting results; (5) Calculate the single fatigue damage at the observation point based on the rainflow counting results and the SN curve of the material; (6) Calculate the M fatigue damages at the observation point based on the single fatigue damage; (7) Adjust the scanning rate of the observation point and repeat steps (2) to (5) until the fatigue damage in a single test is equal to the fatigue damage in M ​​tests at the observation point, and obtain the adjusted scanning rate; (8) Based on the adjusted scan rate, obtain the relationship between the scan rate and the number of times the spacecraft can be reused, and use it to calculate the test scan rate corresponding to any number of reuses; In step (7), the scan rate of the observation point is adjusted so that the fatigue damage in a single test is equal to the fatigue damage in M ​​tests at the observation point, thus obtaining the adjusted scan rate. The specific method is as follows: S71: Based on multiple simulations of fatigue damage and scan rate at the observation points, the scan rate is obtained. n With fatigue damage f(n) Relationship formulas; S72: Solve the equation using the relational formula. g ( n ) =f ( n ) - D m =0 The root, of which, D m The fatigue damage is measured in M ​​tests. S73: Drawing g ( n )and n The relationship formula curve; S74: Based on the relational formula curve, take ( n 0, g ( n Draw a tangent line at point (0) and the tangent line intersects the x-axis at point (0). n 1 , 0); Pass ( n 1 ，g ( n 1) Draw the tangent again; S75: Repeat step S74 to calculate... g ( n ) =0 The scan rate n at that time.

2. The method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft according to claim 1, characterized in that: In step (2), the frequency domain sinusoidal vibration condition is converted into a time domain sinusoidal vibration condition. The specific method is as follows: in, n For scan rate; R It is an octave; f 0 represents the lower frequency limit of the sine wave test; φ The phase at a certain moment; t For a certain moment; M f The amplitude of the frequency domain curve is the frequency. f The function corresponds to the curve representing the sinusoidal vibration condition in the frequency domain; M t The amplitude of the time-domain curve is the time... t The function is given by the curve representing the sinusoidal vibration condition in the time domain.

3. The method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft according to claim 1, characterized in that: In step (3), based on the sinusoidal vibration condition in the time domain, time history analysis is performed on the observation point to obtain the stress time domain response. The specific method is as follows: Based on the spacecraft structure, a finite element model of the spacecraft is established. The parts of the spacecraft connected to the vibration table and fixture are fixed and constrained. The sinusoidal vibration condition in the time domain is used as the load to perform vibration time domain response analysis, complete the time history analysis, and obtain the stress time domain response.

4. The method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft according to claim 1, characterized in that: In step (4), rainflow counting is performed on the stress time-domain response to obtain the rainflow counting results. The specific method is as follows: Using a rainflow counting algorithm, the same stress time-domain response is grouped into the same group, forming several groups of response results; Several sets of response results are plotted into a bar chart to obtain the rainflow count results. The horizontal axis of the bar chart represents the data size of each group, and the vertical axis of the bar chart represents the number of response results in each group. Based on the rainflow count, the actual number of load cycles is obtained.

5. The method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft according to claim 1, characterized in that: In step (5), the single fatigue damage at the observation point is calculated based on the rainflow counting results and the SN curve of the material. The specific method is as follows: D=n 1 / N 1 + n 2 / N 2 + n 3 / N 3 +…n i / N i in, D For single-instance fatigue injury, n i The stress at the observation point is S i The actual number of load cycles, N i For the corresponding materials SN On the curve S i The corresponding fatigue life, of which, i=1,2,3,…. .

6. The method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft according to claim 1, characterized in that: In step (6), the M fatigue damages at the observation point are calculated based on the single fatigue damage. The specific method is as follows: D m =M×D in, D m for M Secondary fatigue injury. D For single-instance fatigue injury, M The number of trials.

7. The method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft according to claim 1, characterized in that: Based on the adjusted scan rate, the relationship between the scan rate and the number of times the spacecraft can be reused is obtained, using the following formula: nM b =c Where b and c are constants, M is the number of times the spacecraft can be reused, and n is the adjusted scan rate.

8. The method for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft according to claim 1, characterized in that: The scan rate n With fatigue damage f(n) The relationship formula is as follows: f(n) = a × ln ( n ) + d / ( n 2 ) +h in, f(n) For fatigue damage, n For scan rate; a , d, h All are constants; ln ( n ) indicates with e as bottom n The logarithm of .

9. A system for calculating the scan rate of a sinusoidal vibration test on a reusable spacecraft, characterized in that, The method for calculating the scan rate of a sinusoidal vibration test of a reusable spacecraft as described in any one of claims 1 to 8 includes: Time-frequency conversion module: Selects an observation point on the spacecraft to obtain the scan rate and frequency domain sinusoidal vibration conditions; converts the frequency domain sinusoidal vibration conditions into time domain sinusoidal vibration conditions based on the scan rate; and sends the time domain sinusoidal vibration conditions to the stress response calculation module. Stress response calculation module: Based on the time-domain sinusoidal vibration conditions sent by the time-frequency conversion module, the module performs time history analysis on the observation points to obtain the stress time-domain response; and sends the stress time-domain response to the fatigue damage calculation module. Fatigue damage calculation module: Performs rainflow counting on the stress time-domain response sent by the stress response calculation module to obtain rainflow counting results; calculates single-fatigue damage at the observation point based on the rainflow counting results and the material's SN curve; calculates M-times fatigue damage at the observation point based on the single-fatigue damage; calculates the scan rate when the single-test fatigue damage equals the M-times fatigue damage; obtains the relationship between the scan rate and the number of times the spacecraft can be reused based on the adjusted scan rate, which is used to calculate the test scan rate corresponding to any number of reuses.

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