Water elasticity response analysis method of water platform under impact load effect
By analyzing the water elastic response analysis method of the water platform under the impact load, the impact load data is collected and processed and loaded into the time domain water elastic motion equation to solve the motion response forecast problem of ships and offshore floating platforms under the dynamic impact load, and a rapid and accurate water elastic response analysis is achieved, which improves the safety and success rate of the launch process.
Patent Information
- Application Number
- CN202411693678.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-03-04
AI Technical Summary
When ships and offshore floating platforms are subject to power impact loads, it is difficult to accurately predict motion response and evaluate safety, affecting structural strength and safety, and thus affecting the launch success rate of the emitter.
A water elastic response analysis method for water platform under impact load is proposed. By collecting the original time curve of impact load, high-pass filtering and data reconstruction, the impact load reconstruction time curve is obtained, and loading it in the time domain water elastic motion equation for solving, and calculating the water elastic response of water platform.
It achieves rapid and accurate acquisition of the water elastic response analysis results of the water platform under the impact load, fills the industry's technical gap, and can provide technical guarantees for the safety assessment of the launch process and improves the launch success rate.
Smart Images
Figure CN119557544A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of ship and ocean engineering technology, and in particular to a method for analyzing the hydroelastic response of an above-water platform under impact load. Background Art
[0002] When ships are sailing and operating in the waves or offshore floating platforms are launching launch vehicles, these water platforms will be subjected to strong dynamic impact loads. Such special loads will have a strong dynamic impact effect on the ships / offshore floating platforms. If this effect is not well studied, controlled and designed, it will affect the structural strength and safety of the ships / offshore floating platforms, and affect the use of equipment on the ships / offshore floating platforms, thereby affecting the vitality of the ships / offshore floating platforms, and will also affect the launch success rate of the launch vehicle.
[0003] Therefore, it is necessary to predict the motion response and conduct safety assessment of ships / sea launch platforms under the impact load of launch. However, the launch impact load has the characteristics of short time (as low as seconds) and huge load (as high as hundreds of tons), which makes it difficult to predict the motion response. Summary of the invention
[0004] In view of the above problems and technical requirements, this application proposes a method for analyzing the hydroelastic response of an above-water platform under impact load. The technical solution of this application is as follows:
[0005] A method for analyzing the hydroelastic response of an above-water platform under an impact load, the method comprising:
[0006] Collect the original time curve of the impact load on the water platform during the launch of the projectile;
[0007] Perform high-pass filtering on the original time curve of the impact load to obtain the filtered time curve of the impact load;
[0008] Based on the principle of consistent impulse of the impact load, the time curve after the impact load is filtered is reconstructed to obtain the reconstructed time curve of the impact load. The reconstructed time curve of the impact load is a curve of the reconstructed impact load changing with time.
[0009] The impact load term is added to the external load term of the time-domain hydroelastic motion equation under irregular waves to obtain the time-domain hydroelastic motion equation containing the impact load term. The obtained impact load reconstruction time curve is substituted into the impact load term and the time-domain hydroelastic motion equation containing the impact load term is solved to obtain the hydroelastic response result of the water platform under the impact load.
[0010] A further technical solution is to reconstruct the time curve of the impact load after filtering based on the principle of consistent impulse of the impact load to obtain the reconstructed time curve of the impact load, including:
[0011] Determine the moment when the impact load starts to increase from 0 in the time curve after impact load filtering as the starting moment T of the launch of the projectile s , determine the moment when the impact load returns to a stable state as the end time of the projectile launch T e ;
[0012] Calculate the impulse of the impact load during the launch of the projectile Among them, S im (t) is the time curve after impact load filtering, t represents time;
[0013] According to the characteristic that the impulse of the impact load reconstruction time curve is also I, the impact load reconstruction time curve is obtained.
[0014] A further technical solution is that, according to the characteristic that the impulse of the impact load reconstruction time curve is also I, the impact load reconstruction time curve is obtained, which includes:
[0015] According to the load characteristics of the impact load during the launch of the projectile, which increases first and then decreases, the impact load reconstruction time curve is determined in a segmented form. Among them, T max is the maximum reconstruction impact load S max moment; s1(t) is an increasing function with time t and s1(T s )=0, s2(t) is a decreasing function with time t and s2(T e ) = -W, W is the weight of the projectile;
[0016] Combining the functional forms of s1(t) and s2(t), and determining T according to the characteristics of the impulse of the reconstructed time curve of the impact load, which is also I max and S max , and reconstruct the impact load reconstruction time curve.
[0017] A further technical solution is that both s1(t) and s2(t) are in the form of linear equations, and the impact load reconstruction time curve is in the form of According to the characteristics of the impulse of the reconstructed time curve of the impact load, T is determined by I. max and S max include:
[0018] The expression for determining the impulse of the impact load reconstruction time curve is: Calculate the maximum reconstruction impact load And calculate the maximum reconstruction impact load S max Moment Among them, T0 is the moment when the impact load drops to zero in the time curve after impact load filtering.
[0019] A further technical solution is that when solving the time-domain hydroelastic motion equation containing the impact load term, the time step dt in the time-domain hydroelastic method is less than the impact load action time T e -T s And count the steps
[0020]
[0021] A further technical solution is to include the time domain hydroelastic motion equation of the impact load term:
[0022]
[0023] Where {S(t)} represents the impact load term; [a] is the generalized mass matrix of the structure, [b] is the generalized damping matrix, [c] is the generalized stiffness matrix, [A ∞ ] is a matrix with additional mass constants as elements, [K'] is a matrix with radiation force impulse response function as elements, and {q(t)} is the principal coordinate response; the external load terms of the time-domain hydroelastic motion equation under irregular waves include generalized wave excitation force {F(t)}, generalized hydrostatic restoring force {K(t)} and generalized gravity {Q(t)}.
[0024] The beneficial technical effects of this application are:
[0025] The present application discloses a method for analyzing the hydroelastic response of an underwater platform under an impact load. The method performs high-pass filtering on the acquired original time curve of the impact load, performs data smoothing to remove burrs while retaining the characteristics of the impact load, and then reconstructs the data according to the equal impulse principle to obtain a function expression of the reconstructed time curve of the impact load. The reconstructed time curve of the impact load is loaded into the impact load term in the time-domain hydroelastic motion equation containing the impact load term for solving, thereby realizing the calculation and analysis of the motion response and the structural response, thereby quickly and accurately obtaining the hydroelastic response analysis results, which fills the technical gap in the industry and can perform safety assessment for the launch process, thereby providing technical guarantee for the safety of the underwater platform and the launch success rate of the launch body. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 It is a method flow chart of a hydroelastic response analysis method according to an embodiment of the present application.
[0027] Figure 2 It is a schematic diagram of an original time curve of an impact load collected in an example and a filtered time curve of the impact load obtained after high-pass filtering.
[0028] Figure 3 yes Figure 2 Schematic diagram of the reconstructed time curve of the impact load obtained by reconstructing the time curve after filtering the impact load in the example.
[0029] Figure 4 The figure is a comparison diagram of the hydroelastic response result predicted by the hydroelastic response analysis method of the present application and the test result in an example. DETAILED DESCRIPTION
[0030] The specific implementation of the present application is further described below in conjunction with the accompanying drawings.
[0031] This application discloses a method for analyzing the hydroelastic response of a water platform under impact load. Please refer to Figure 1 As shown in the flowchart, the hydroelastic response analysis method includes the following steps:
[0032] Step 1: Collect the original time curve of the impact load received by the water platform during the launch of the launcher. The original time curve of the impact load is data directly collected by sensors and other equipment, and can be obtained by actual measurement during the test or the actual launch process.
[0033] Step 2: Perform high-pass filtering on the original time curve of the impact load to obtain the filtered time curve of the impact load. Since the impact load generated by the launch has the characteristics of extremely large time period and load, in order to accurately capture and collect the impact load generated by the launch, the acquisition frequency is usually very high, such as often reaching 10kHz. Therefore, the original time curve of the impact load has a large number of data glitches, and the time step is extremely short and the data volume is large. For example, in one example, the original time curve of the impact load collected is as follows: Figure 2 The black curve in .
[0034] These data characteristics make it impossible to directly use the original time curve of the impact load for response analysis. Therefore, this application first performs high-pass filtering on the original time curve of the impact load to remove data glitches while retaining the characteristics of the impact load. Figure 2 The original time curve of the impact load shown in the black curve is subjected to high-pass filtering to obtain the filtered time curve of the impact load. Figure 2 The red curve in .
[0035] Step 3, based on the principle of consistent impulse of the impact load, data of the filtered time curve of the impact load is reconstructed to obtain a reconstructed time curve of the impact load. The obtained reconstructed time curve of the impact load is a curve of the reconstructed impact load changing with time.
[0036] Although the impact load filtered time curve has removed data burrs compared to the original impact load time curve, it still has the characteristics of extremely short time step and large data volume, which makes it difficult to accurately simulate digitally and difficult to use for response analysis. Therefore, the impact load filtered time curve is further reconstructed. When reconstructing the data, the data is reconstructed based on the principle of equal impulse with consistent impulse, so as to ensure that the impact load characteristics are consistent before and after reconstruction.
[0037] When reconstructing data, the following steps are included:
[0038] (1) Please combine Figure 2 The original time curve of the impact load and the time curve after the impact load is filtered. The change characteristics of the impact load during the launch of the projectile are that it increases from 0 and then gradually decreases. After it drops to zero, it continues to decrease and finally reaches stability. The final stable impact load is the weight of the projectile. Based on this change characteristic, several important time nodes are first determined from the time curve after the impact load is filtered, including: determining the moment when the impact load starts to increase from 0 as the starting time T of the projectile launch s , and determine the moment when the impact load returns to a stable state as the end moment of the launch of the projectile T e .
[0039] Please refer to Figure 2 Even the filtered impact load time curve is not a monotonic curve. The impact load will fluctuate continuously. Therefore, when determining the starting time T s The moment when the impact load first starts to mutate from 0 can be taken as the starting moment T s , or calculate the statistical results of the impact load within a custom time step, and take the time when the statistical results start to increase from 0 as the starting time T s Similarly, when determining the end time T e When the impact load is maintained at a dynamic stable state, the impact load does not remain unchanged, but only maintains a dynamic stable state. The statistical results of the impact load within the custom time step can be used to determine whether the stable state is reached.
[0040] In addition, it is necessary to determine the time T0 when the impact load drops to zero in the time curve after impact load filtering. Similarly, the time when the impact load first drops to zero is taken as T0, or the time when the statistical results of the impact load within the custom time step are returned to zero during the fluctuation process is taken as T0.
[0041] (2) Then the impulse of the impact load during the launch of the projectile can be calculated Among them, S im (t) is the time curve of impact load after filtering, and t represents time.
[0042] (3) The impact load reconstruction time curve is obtained according to the characteristic that the impulse of the impact load reconstruction time curve is also I. Since the impact load during the launch of the projectile has the load characteristic of increasing first and then decreasing, it is determined that the load reconstruction time curve is in a segmented form and
[0043] Among them, T max is the maximum reconstruction impact load S max moment. s1(t) is an increasing function with time t and s1(T s )=0, s2(t) is a decreasing function with time t and s2(T e )=-W, and s1(T max )=s2(T max ), W is the weight of the projectile.
[0044] After determining the functional form of s1(t) and s2(t), we can construct the expression of the impulse of the load reconstruction time curve. Then, based on the characteristic that the impulse of the impact load reconstruction time curve is also I, we can determine T max and S max , and finally reconstruct the impact load reconstruction time curve.
[0045] In one embodiment, s1(t) and s2(t) are both in the form of linear equations, and the impact load reconstruction time curve can be written as Based on this, the expression of the impulse of the impact load reconstruction time curve can be determined as follows:
[0046] By calculation The maximum reconstruction impact load can be obtained And calculate the maximum reconstruction impact load S max Moment Substituting the above function form into the final impact load reconstruction time curve can be obtained. Figure 2 In the example of , the impact load reconstructed time curve obtained by data reconstruction of the impact load filtered time curve is as follows Figure 3 The green curve in .
[0047] Step 4: Add the impact load term to the external load term of the time-domain hydroelastic motion equation under irregular waves to obtain the time-domain hydroelastic motion equation including the impact load term, substitute the obtained impact load reconstruction time curve into the impact load term and solve the time-domain hydroelastic motion equation including the impact load term to obtain the hydroelastic response result of the water platform under the impact load.
[0048] The traditional equation of motion of hydroelasticity in time domain under irregular waves is as follows:
[0049]
[0050] Where, [a] is the generalized mass matrix of the structure, [b] is the generalized damping matrix, [c] is the generalized stiffness matrix, [A ∞ ] is a matrix with the added mass constant as its element, [K'] is a matrix with the radiation force impulse response function as its element. {q(t)} is the principal coordinate response, represents the first derivative of the principal coordinate response, represents the second derivative of the principal coordinate response. τ is the time parameter.
[0051] It can be seen from the above formula that the external load terms of the traditional time-domain hydroelastic motion equation under irregular waves include three terms, namely, generalized wave excitation force {F(t)}, generalized hydrostatic restoring force {K(t)} and generalized gravity {Q(t)}. Among them, the generalized wave excitation force {F(t)} includes the generalized incident wave force and the generalized diffraction wave force.
[0052] On this basis, this application adds an impact load term to the external load term of the time-domain hydroelastic motion equation under irregular waves, and obtains the time-domain hydroelastic motion equation containing the impact load reconstruction time curve:
[0053]
[0054] where {S(t)} represents the impact load term added to the external load term of the time-domain hydroelastic motion equation under irregular waves.
[0055] Then substitute the reconstructed impact load reconstruction time curve into the above impact load term {S(t)}, and the other terms can be substituted into the corresponding values according to the solution method of each matrix term in the time-domain hydroelastic motion equation under traditional irregular waves, which is not described in detail in this application. Then, by solving the time-domain hydroelastic motion equation containing the impact load term, the hydroelastic response results of the water platform under the impact load can be obtained, including motion response and structural response. In addition, when solving, the time step dt in the time-domain hydroelastic method is less than the duration T of the impact load. e -T s And count the steps This ensures that the impact load acts reasonably on the time-domain hydroelastic calculation.
[0056] In one example, the comparison between the hydroelastic heave response of the water platform under the impact load obtained by the hydroelastic response analysis method of the present application and the test result is as follows: Figure 4 As shown by Figure 4 It can be seen that the hydroelastic response results obtained using the method of the present application are highly consistent with the test results, which verifies the accuracy and effectiveness of the method of the present application.
[0057] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.
Claims
1. A method for analyzing the hydroelastic response of an above-water platform under impact load, characterized in that: The hydroelastic response analysis method comprises: Collect the original time curve of the impact load on the water platform during the launch of the projectile; Performing high-pass filtering on the original time curve of the impact load to obtain a filtered time curve of the impact load; Based on the principle of consistent impulse of the impact load, the time curve after the impact load is filtered is reconstructed to obtain the reconstructed time curve of the impact load. The reconstructed time curve of the impact load is a curve of the reconstructed impact load changing with time. An impact load term is added to the external load term of the time-domain hydroelastic motion equation under irregular waves to obtain the time-domain hydroelastic motion equation containing the impact load term. The obtained impact load reconstruction time curve is substituted into the impact load term and the time-domain hydroelastic motion equation containing the impact load term is solved to obtain the hydroelastic response result of the water platform under the impact load.
2. The hydroelastic response analysis method according to claim 1, characterized in that: Based on the principle of consistent impulse of the impact load, the data of the time curve after the impact load filtering is reconstructed to obtain the reconstructed time curve of the impact load, including: Determine the moment when the impact load starts to increase from 0 in the time curve after impact load filtering as the starting moment T of the launch of the projectile s , determine the moment when the impact load returns to a stable state as the end time of the projectile launch T e ; Calculate the impulse of the impact load during the launch of the projectile Among them, S im (t) is the time curve after impact load filtering, t represents time; According to the characteristic that the impulse of the impact load reconstruction time curve is also I, the impact load reconstruction time curve is obtained.
3. The hydroelastic response analysis method according to claim 2, characterized in that: According to the characteristic that the impulse of the impact load reconstruction time curve is also I, the impact load reconstruction time curve includes: According to the load characteristics of the impact load during the launch of the projectile, which increases first and then decreases, the impact load reconstruction time curve is determined in a segmented form. Among them, T max is the maximum reconstruction impact load S max moment; s1(t) is an increasing function with time t and s1(T s )=0, s2(t) is a decreasing function with time t and s2(T e ) = -W, W is the weight of the projectile; Combining the functional forms of s1(t) and s2(t), and determining T according to the characteristics of the impulse of the reconstructed time curve of the impact load, which is also I max and S max , and reconstruct the impact load reconstruction time curve.
4. The method for analyzing hydroelastic response according to claim 3, characterized in that: Both s1(t) and s2(t) are in the form of linear equations, and the impact load reconstruction time curve is in the form of According to the characteristics of the impulse of the reconstructed time curve of the impact load, T is determined as I max and S max include: The expression for determining the impulse of the impact load reconstruction time curve is: Calculate the maximum reconstruction impact load And calculate the maximum reconstruction impact load S max Moment Among them, T0 is the moment when the impact load drops to zero in the time curve after impact load filtering.
5. The method for analyzing water elastic response according to claim 2, characterized in that: When solving the time-domain hydroelastic motion equations including the impact load term, the time step dt in the time-domain hydroelastic method is smaller than the duration of the impact load T. e -T s And count the steps 6. The method for analyzing hydroelastic response according to claim 1, characterized in that: The time domain hydroelastic motion equation including the impact load term is: Where {S(t)} represents the impact load term; [a] is the generalized mass matrix of the structure, [b] is the generalized damping matrix, [c] is the generalized stiffness matrix, [A ∞ ] is a matrix with additional mass constants as elements, [K'] is a matrix with radiation force impulse response function as elements, and {q(t)} is the principal coordinate response; the external load terms of the time-domain hydroelastic motion equation under irregular waves include generalized wave excitation force {F(t)}, generalized hydrostatic restoring force {K(t)} and generalized gravity {Q(t)}.