A flow-induced vibration suppression method based on modal matching

Abstract

A flow-induced vibration suppression method based on modal matching disclosed by the present invention belongs to the field of structural dynamics. The implementation method of the present invention is as follows: perform natural frequency analysis on the structure that needs to suppress vibration to obtain its natural frequencies of each order, select the mode that needs to suppress vibration, and construct a matching condition based on the dynamic response characteristics of the structure under dynamic load between the dynamic load mode and the structural vibration mode according to the mode; optimize the structure that needs to suppress vibration according to the constructed matching condition, adjust the natural frequency of the structure that needs to suppress vibration, so that the optimized natural frequency of the structure satisfies the modal matching condition, and utilize the spatial correlation of the dynamic load and the coupling effect between the dynamic load mode and the structural vibration mode to realize the suppression of structural vibration, and further realize the flow-induced vibration suppression of the structure based on modal matching under the action of the dynamic load. The field of the flow-induced vibration suppression of the structure includes the flow-induced vibration suppression of the aircraft structure and the flow-induced vibration suppression of the ship structure.

Description

Technical Field

[0001] The present invention belongs to the field of structural dynamics and relates to a method for suppressing fluid-induced vibration based on modal matching. Background Art

[0002] During the high-speed flight of an aircraft, the interaction between the high-speed airflow and the aircraft structure will generate a severe fluid-induced dynamic load environment on the aircraft surface. On the one hand, the fluid-induced dynamic load environment will generate a strong in-cabin noise environment, thus interfering with the normal operation of the acoustic-sensitive equipment inside the aircraft; on the other hand, the buffeting of the aircraft structural components induced by the dynamic load will, to a certain extent, also threaten the structural safety and flight stability of the aircraft, and excessive structural vibration may even directly lead to the structural damage of the aircraft. In addition, during the navigation of a ship, the interaction between the water flow and the ship structure in the water will also generate a fluid-induced dynamic load environment. The vibration induced by the fluid-induced dynamic load will cause excessive noise of the ship, which will not only affect the structural safety and normal operation of the equipment, but also increase the exposure risk of the ship. In order to reduce the adverse effects of the structural vibration caused by the fluid-induced dynamic load on the safety of the aircraft and the ship, it is urgent to carry out research on suppressing the dynamic response of the structure under the action of the dynamic load, develop effective methods for controlling fluid-induced vibration, and provide a technical approach for the structural safety design of the aircraft and the ship.

[0003] The structural vibration control methods mainly include several methods such as passive control, active control, and semi-active control. Passive control is easy to implement, does not require external energy input, and has high reliability and robustness. However, it also has the disadvantages of being unable to flexibly adjust the damping characteristics and possibly bringing a large additional mass. Active control is to use a control loop to achieve the control of the structure through a specific algorithm, which has better control effects than passive control. However, it also has problems such as the need for external energy input and possible control overflow. The existing research results show that the common passive methods such as increasing the structural mass, adjusting the structural stiffness, designing the structural natural frequency, increasing the structural damping, and installing a dynamic vibration absorber are often the most effective methods for fluid-induced vibration control in engineering.

[0004] Generally, the vibration passive control method changes the dynamic characteristics of the structure by changing the mass and stiffness of the structure, so that the natural frequency of the aircraft structure can be avoided as much as possible from the external excitation frequency of the load, thereby avoiding the occurrence of large-amplitude structural vibration. However, for fluid-induced vibration, the frequency range of the dynamic load energy distribution generated by high-speed flow is relatively wide, and it is not feasible to avoid structural resonance by the traditional method of adjusting the structural natural frequency range. Summary of the Invention

[0005] The technical problem to be solved by a flow-induced vibration suppression method based on modal matching disclosed by the present invention is as follows: perform natural frequency analysis on a structure that needs to suppress vibration to obtain its natural frequencies of each order, select the mode that needs to suppress vibration, and construct a matching condition between the dynamic load mode and the structural vibration mode according to the structural dynamic response characteristics of the mode under dynamic load; optimize the structure that needs to suppress vibration according to the constructed matching condition, adjust the natural frequency of the structure that needs to suppress vibration, so that the optimized natural frequency of the structure satisfies the modal matching condition, and utilize the spatial correlation of the dynamic load and the coupling effect between the dynamic load mode and the structural vibration mode to achieve structural vibration suppression, and further achieve flow-induced vibration suppression based on modal matching under dynamic load.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] A flow-induced vibration suppression method based on modal matching disclosed by the present invention includes the following steps:

[0008] Step 1: Perform natural frequency analysis on a structure that needs to suppress vibration to obtain its natural frequencies of each order, and select the mode that needs to suppress vibration. According to the wavelength λ of the structural resonance mode s and the wavelength λ of the dynamic load f and the relationship with the structural flow direction length a, define the structural modal characteristic number N s and the load modal characteristic number N f , and obtain the natural frequency f of the mode that the structure needs to suppress vibration through natural frequency analysis.

[0009] The expression of the structural modal characteristic number N s is shown in formula (1)

[0010]

[0011] where N s is the structural modal characteristic number, a is the structural flow direction length, and λ s is the wavelength of the structural resonance mode.

[0012] The expression of the load modal characteristic number N f is shown in formula (2)

[0013]

[0014] where N f is the load modal characteristic number, and λ f is the wavelength of the dynamic load.

[0015] Step 2: Since the flow-induced dynamic load has spatial modal characteristics, the coupling effect between the dynamic load mode and the structural vibration mode will cause the structural dynamic response to show periodic fluctuations. Based on the structural dynamic response characteristics of the mode to be vibration-suppressed selected in Step 1 under the action of the dynamic load, a modal matching condition based on the dynamic load mode and the structural vibration mode is constructed; the modal matching condition is obtained by determining the dynamic load modal characteristic number N f and the structural modal characteristic number N s between the matching relationship, and the ideal natural frequency f′ of the structure when the modal matching condition is satisfied is obtained according to the matching relationship, so that the structural dynamic response is located at the trough of the periodic fluctuation of the dynamic response.

[0016] Based on the structural dynamic response characteristics of the mode to be vibration-suppressed selected in Step 1 under the action of the dynamic load, a modal matching condition based on the dynamic load mode and the structural vibration mode is constructed. The modal matching condition is that when the structural modal characteristic number N s is an odd multiple of 0.5, the structural dynamic response will be at the trough of the periodic fluctuation of the dynamic response when the load modal characteristic number N f is an odd multiple of 0.5 and the load modal characteristic number N f is not equal to the structural modal characteristic number N s ; when the structural modal characteristic number N s is an even multiple of 0.5, the structural dynamic response will be at the trough of the periodic fluctuation of the dynamic response when the load modal characteristic number N f is an even multiple of 0.5 and the load modal characteristic number N f is not equal to the structural modal characteristic number N s .

[0017] Calculate the dynamic load wavelength λ f according to the dynamic load modal characteristic number N f and the flow direction length a of the structure, and the dynamic load wavelength λ f is obtained from formula (2). When the modal matching condition is reached, the relationship between the dynamic load wavelength λ f , the convection velocity U c and the ideal natural frequency f′ of the structure satisfies formula (3)

[0018]

[0019] where f′ is the ideal natural frequency of the structure, U c is the convection velocity, and the convection velocity U c is obtained from the free flow velocity U ∞ , and the relationship between the two is shown in formula (4).

[0020] U c = 0.65U ∞ (4)

[0021] Among them, U c is the convective velocity, and U ∞ is the free stream velocity.

[0022] According to the relationship between the dynamic load wavelength λ f and the convective velocity U c and the frequency, the ideal natural frequency f′ of the structure when the modal matching condition is satisfied is obtained, that is, according to the matching relationship (3), the ideal natural frequency f′ of the structure when the modal matching condition is satisfied is obtained, so that the dynamic response of the structure is located at the trough of the periodic fluctuation of the dynamic response.

[0023] Step 3: According to the ideal natural frequency f′ of the structure required in the modal matching condition constructed in Step 2, the structure to be vibration-suppressed is structurally optimized, so that the natural frequency f of the structure reaches the ideal natural frequency f′ when the modal matching condition is satisfied, and the structural vibration suppression is realized by using the spatial correlation of the dynamic load and the coupling effect between the dynamic load mode and the structural vibration mode, and then the fluid-induced vibration suppression based on modal matching is realized under the action of the dynamic load.

[0024] Preferably, the structural optimization includes stiffening or grooving, and the structural optimization parameters include the position of the stiffening or grooving, the aspect ratio of the rib or groove, and the mass ratio of the rib or groove.

[0025] The structural optimization selects stiffening or grooving according to the magnitude relationship between the structural natural frequency f and the ideal natural frequency f′ when modal matching is achieved, and the implementation method is as follows:

[0026] The structural natural frequency f is increased by stiffening: when the structural natural frequency f is less than the ideal natural frequency f′, the structural natural frequency f is increased by stiffening. According to the influence law of different parameters on the structural natural frequency f, the position of the rib, the aspect ratio δ j of the rib and the mass ratio ω j .

[0027] The aspect ratio δ j of the rib is obtained from formula (5)

[0028]

[0029] where b j is the width of the rib, and h j is the height of the rib.

[0030] The mass ratio ω j of the rib is obtained from formula (6)

[0031]

[0032] where m jwhere \(m_{s}\) is the rib quality and \(m\) is the flat structure quality.

[0033] The natural frequency \(f\) of the structure is reduced by grooving: when the natural frequency \(f\) of the structure is greater than the ideal natural frequency \(f'\), the natural frequency \(f\) of the structure is reduced by grooving. The position of the groove, the width-to-height ratio \(\delta\) of the groove c and the mass ratio \(\omega\) of the groove are determined according to the influence law of different parameters on the natural frequency \(f\) of the structure. c .

[0034] The width-to-height ratio \(\delta\) of the groove c is obtained from formula (7)

[0035]

[0036] where \(b\) c is the width of the groove and \(h\) c is the height of the groove.

[0037] The mass ratio \(\omega\) of the groove c is obtained from formula (8)

[0038]

[0039] where \(m_{g}\) c is the mass of the groove and \(m\) is the flat structure quality.

[0040] The field of suppressing fluid-induced vibration of the structure includes suppressing fluid-induced vibration of aircraft structures and suppressing fluid-induced vibration of ship structures. By suppressing fluid-induced vibration of aircraft structures, the vibration reduction efficiency of aircraft structures is improved, the refinement and lightweight of aircraft structures are realized, and the structural safety of aircraft during high-speed flight is improved. By suppressing fluid-induced vibration of ship structures, the vibration reduction efficiency of ship structures is improved, the stealth performance of ships is optimized, the exposure risk is reduced, and the structural safety of ships is improved.

[0041] Beneficial effects:

[0042] 1. A fluid-induced vibration suppression method based on modal matching disclosed by the present invention analyzes the natural frequencies of a structure that needs to suppress vibration to obtain its natural frequencies of each order, selects the mode that needs to suppress vibration, and constructs a modal matching condition based on the dynamic response characteristics of the structure under dynamic load according to the mode; optimizes the structure that needs to suppress vibration according to the constructed modal matching condition, adjusts the natural frequency of the structure that needs to suppress vibration, so that the optimized natural frequency of the structure satisfies the modal matching condition, and realizes the suppression of structural vibration by using the spatial correlation of dynamic load and the coupling effect between dynamic load mode and structural vibration mode, thereby realizing fluid-induced vibration suppression based on modal matching under dynamic load.

[0043] 2. For fluid-induced vibration, the frequency range of the dynamic load energy distribution generated by high-speed flow is relatively wide, and it is not feasible to avoid structural resonance by the conventional method of adjusting the natural frequency range of the structure. A fluid-induced vibration suppression method based on mode matching disclosed in the present invention realizes structural vibration suppression by utilizing the spatial correlation of the dynamic load and the coupling effect between the dynamic load mode and the structural vibration mode. As long as the spatial mode of the fluid-induced dynamic load and the structural vibration mode meet the mode matching conditions constructed in the present invention, a significant suppression of the structural fluid-induced vibration can be achieved without caring whether the frequency of the external excitation is consistent with the natural frequency of the structure. On the premise of improving the accuracy of structural vibration suppression, it is easy to realize the fluid-induced vibration suppression of the structure under the action of the dynamic load.

[0044] 3. A fluid-induced vibration suppression method based on mode matching disclosed in the present invention optimizes the structure of the structure that needs to suppress vibration, so that the natural frequency f of the structure reaches the ideal natural frequency f' when the mode matching conditions are satisfied. The structure optimization corresponds to adding ribs or grooving according to the magnitude relationship between the natural frequency f of the structure and the ideal natural frequency f' when the mode matching is achieved. The structure optimization parameters include the position of adding ribs or grooving, the width-to-height ratio of the rib or groove, and the mass ratio of the rib or groove. By adding ribs, the natural frequency f of the structure is increased, and by grooving, the natural frequency f of the structure is decreased, making it easy to realize the mode matching conditions and adapting to the structural vibration suppression of aircraft and ships in complex dynamic load environments.

[0045] 4. A fluid-induced vibration suppression method based on mode matching disclosed in the present invention, on the basis of achieving the above beneficial effects 1, 2, and 3, has a better effect on suppressing the structural vibration under the action of the dynamic load than the traditional vibration suppression method of simply increasing the mass on the premise of increasing the same mass to the structure, thereby improving the vibration reduction efficiency of the aircraft and ship structures and realizing the refinement and lightweight of the aircraft and ship structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic flow chart of a fluid-induced vibration suppression method based on mode matching disclosed in the present invention.

[0047] Figure 2 is a schematic diagram of the mode matching conditions when vibration suppression is achieved, where Figure 2 a) is a graph of the velocity response results of the flat plate structure under different load characteristic numbers in the first-order mode, Figure 2 b) is a schematic diagram of the mode matching conditions.

[0048] Figure 3 is a schematic diagram of ribbing the flat plate structure, where Figure 3 a) is ribbing on the long side of the flat plate structure, Figure 3 b) is ribbing on the short side of the flat plate structure.

[0049] Figure 4 is the diagram of the first-order natural frequency results of the flat structure under different structural design forms, where Figure 4 a) are the first-order natural frequency results of the structure with different rib width-to-height ratios, Figure 4 b) are the first-order natural frequency results of the structure with different rib mass ratios.

[0050] Figure 5 is the frequency response curve diagram of the structural dynamic response after adopting the vibration suppression method of the present invention, where Figure 5 a) is the average response of the flat structure, Figure 5 b) is the average stress of the flat structure. Specific implementation manner

[0051] To better illustrate the purpose and advantages of the present invention, the following further describes the content of the invention in conjunction with the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of the present invention and cannot be used to limit the protection scope of the present invention.

[0052] In this embodiment, a certain flat structure is selected for suppressing fluid-induced vibration. The flat plate model uses an aluminum structure, and the corresponding material parameters are: the Young's modulus E of the plate is 7.0×10 10 Pa, the Poisson's ratio ν of the plate is 0.33, the density ρ of the plate is 2.7×10 3 kg / m 3 , and the damping coefficient η of the plate is 0.02. The size of the flat structure is 0.768 m in length, 0.328 m in width, and 0.0132 m in height. The flow direction is along the length direction of the flat structure, that is, the flow direction length a of the flat structure is 0.768 m. In this embodiment, the finite element solver in the software COMSOL Multiphysics is used to solve the natural frequency of the flat structure and the structural dynamic characteristic response and stress of the flat plate model under dynamic load.

[0053] As Figure 1 shown, a fluid-induced vibration suppression method based on modal matching disclosed in this embodiment is specifically implemented as follows:

[0054] Step 1: Perform natural frequency analysis on the structure that needs to suppress vibration and obtain its natural frequencies of each order. Select the first-order mode of the structure as the mode that needs to suppress vibration. Define the structural modal characteristic number N s and the load modal characteristic number N f according to the relationship between the resonance modal wavelength λ s of the structure, the dynamic load wavelength λ f and the flow direction length a of the structure, and obtain the first-order natural frequency f of the vibration suppression mode of the structure through natural frequency analysis as 353.87 Hz.

[0055] The structural modal characteristic number N sThe expression is as shown in formula (1).

[0056]

[0057] Where N s is the number of structural modal characteristics, a is the structural flow length, and λ s is the wavelength of the structural resonance mode.

[0058] The number of load modal characteristics N f has an expression as shown in formula (2).

[0059]

[0060] Where N f is the number of load modal characteristics, and λ f is the wavelength of the dynamic load.

[0061] Step 2: Since the flow-induced dynamic load has spatial modal characteristics, the coupling effect between the dynamic load mode and the structural vibration mode will cause the structural dynamic response to show periodic fluctuations. According to the structural dynamic response characteristics of the first-order mode selected in Step 1 that needs to suppress vibration under the action of the dynamic load, construct the modal matching condition between the dynamic load mode and the structural vibration mode; the modal matching condition is obtained by determining the matching relationship between the number of dynamic load modal characteristics N f and the number of structural modal characteristics N s and, according to the matching relationship, obtain the ideal first-order natural frequency f′ of the structure when the modal matching condition is satisfied, so that the structural dynamic response is at the trough of the periodic fluctuations of the dynamic response.

[0062] According to the structural dynamic response characteristics of the first-order mode selected in Step 1 that needs to suppress vibration under the action of the dynamic load, the structural dynamic response characteristics are as Figure 2 shown in a), construct the modal matching condition between the dynamic load mode and the structural vibration mode. The modal matching condition is that when the number of structural modal characteristics N s is an odd multiple of 0.5, the structural dynamic response will be at the trough of the periodic fluctuations of the dynamic response when the number of load modal characteristics N f is an odd multiple of 0.5 and the number of load modal characteristics N f is not equal to the number of structural modal characteristics N s ; when the number of structural modal characteristics N s is an even multiple of 0.5, the structural dynamic response will be at the trough of the periodic fluctuations of the dynamic response when the number of load modal characteristics N f is an even multiple of 0.5 and the number of load modal characteristics N f is not equal to the number of structural modal characteristics N s . Set the modal matching condition as the number of structural modal characteristics N s is 0.5, and the number of load modal characteristics Nf is 1.5, and the schematic diagram of the modal matching condition is as Figure 2 shown in b).

[0063] According to the modal characteristic number N of the dynamic load f and the flow length a of the structure, calculate the dynamic load wavelength λ f , the dynamic load wavelength λ f is obtained from formula (2). The dynamic load wavelength λ f is 0.512 m. When the modal matching condition is reached, the dynamic load wavelength λ f , the convection velocity U c and the relationship between the ideal first natural frequency f′ of the structure satisfy formula (3)

[0064]

[0065] where f′ is the ideal first natural frequency of the structure, and U c is the convection velocity. The convection velocity U c is obtained from the free stream velocity U ∞ . The obtained convection velocity U c is 199 m / s, and the relationship between the two is shown in formula (4).

[0066] U c = 0.65U ∞ (4)

[0067] where U c is the convection velocity, and U ∞ is the free stream velocity.

[0068] According to the relationship between the dynamic load wavelength λ f and the convection velocity U c and the frequency, obtain the ideal first natural frequency f′ of the structure when the modal matching condition is satisfied. The ideal first natural frequency f′ of the flat plate structure is 388.67 Hz, that is, according to the matching relationship (3), obtain the ideal first natural frequency f′ of the structure when the modal matching condition is satisfied, so that the dynamic response of the structure is located at the trough of the periodic fluctuation of the dynamic response.

[0069] Step 3: According to the ideal first natural frequency f′ of the structure required in the modal matching condition constructed in Step 2, perform structural optimization on the structure that needs to suppress vibration, so that the first natural frequency f of the structure reaches the ideal first natural frequency f′ when the modal matching condition is satisfied, and utilize the spatial correlation of the dynamic load and the coupling effect of the dynamic load mode and the structural vibration mode to realize structural vibration suppression, and then realize flow-induced vibration suppression based on modal matching under the action of the dynamic load.

[0070] The structural optimization includes stiffening or grooving, and the structural optimization parameters include the position of the stiffening or grooving, the aspect ratio of the rib or groove, and the mass ratio of the rib or groove.

[0071] The structural optimization selects stiffening or grooving according to the magnitude relationship between the first-order natural frequency f of the structure and the ideal first-order natural frequency f' when achieving modal matching. In this embodiment, stiffening is selected to increase the first-order natural frequency f of the structure, and the implementation method is as follows:

[0072] Increase the first-order natural frequency f of the structure by stiffening: when the first-order natural frequency f of the structure is less than the ideal first-order natural frequency f', increase the first-order natural frequency f of the structure by stiffening. Determine the position of the rib, the aspect ratio δ of the rib j and the mass ratio ω of the rib according to the influence law of different parameters on the first-order natural frequency f of the structure j . The schematic diagram of stiffening at different positions of the flat plate structure is as shown in Figure 3 shown, and the influence of different rib parameters on the natural frequency of the structure is as shown in Figure 4 shown. It can be seen from Figure 4 that the smaller the aspect ratio of the rib width to thickness and the larger the mass ratio, the more obvious the improvement effect on the natural frequency of the structure, and the improvement effect of stiffening at the middle position of the short side of the flat plate structure is better than that of other positions. Considering the improvement effect on the natural frequency and the limitation of the stiffening mass and other factors, it is finally determined that the rib is set at the middle position of the short side of the flat plate structure, and the stiffening method is as shown in Figure 3 b). The aspect ratio δ of the rib j is 0.2, and the mass ratio ω of the rib j is 0.9097%.

[0073] The aspect ratio δ of the rib j is obtained from formula (5)

[0074]

[0075] where b j is the width of the rib, and h j is the height of the rib.

[0076] The mass ratio ω of the rib j is obtained from formula (6)

[0077]

[0078] where m j is the mass of the rib, and m is the mass of the flat plate structure.

[0079] The frequency response curve of the structural dynamic response after adopting the vibration suppression method of the present invention is as shown in Figure 5as shown, where the dashed line represents the result of the original plate without vibration suppression, the dotted line represents the result of the flat plate after being processed by the traditional method of uniform thickening with equal mass, and the solid line with square marks represents the result of the flat plate after being processed by the vibration suppression method proposed in the present invention. From Figure 5 The results show that the vibration suppression method based on mode matching proposed in the present invention has a 25.39% better suppression effect on the peak value of the average response of the structure compared with the traditional thickening method, and a 32.25% better suppression effect on the peak value of the average stress of the structure compared with the traditional thickening method.

[0080] The field of structural fluid-induced vibration suppression described above includes the suppression of fluid-induced vibration of aircraft structures and the suppression of fluid-induced vibration of ship structures. By suppressing the fluid-induced vibration of aircraft structures, the vibration reduction efficiency of aircraft structures can be improved, the refinement and lightweight of aircraft structures can be achieved, and the structural safety of aircraft during high-speed flight can be improved. By suppressing the fluid-induced vibration of ship structures, the vibration reduction efficiency of ship structures can be enhanced, the stealth performance of ships can be optimized, the exposure risk can be reduced, and the structural safety of ships can be improved.

[0081] The above specific description further elaborates on the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above is only a specific embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A flow-induced vibration suppression method based on modal matching, characterized in that: including the following steps, Step 1: Conduct a natural frequency analysis on the structure that needs to suppress vibration and obtain its natural frequencies of each order, and select the mode that needs to suppress vibration; according to the wavelength λ of the structural resonance mode s and the wavelength λ of the dynamic load f Define the structural modal characteristic number N based on the relationship with the structural flow length a s and the load modal characteristic number N f , and obtain the natural frequency f of the vibration suppression mode of the structure through natural frequency analysis; Step 2: Since the flow-induced dynamic load has spatial modal characteristics, the coupling effect between the dynamic load mode and the structural vibration mode will cause the structural dynamic response to exhibit periodic fluctuations. According to the structural dynamic response characteristics of the mode to be vibration-suppressed selected in Step 1 under the action of the dynamic load, a modal matching condition based on the modal matching between the dynamic load mode and the structural vibration mode is constructed. The modal matching condition is obtained by determining the matching relationship between the dynamic load modal characteristic number N f and the structural modal characteristic number N s and obtaining the ideal natural frequency f' of the structure when the modal matching condition is satisfied according to the matching relationship, so that the structural dynamic response is located at the trough of the periodic fluctuations of the dynamic response; Step 3: Optimize the structure of the structure that needs to suppress vibration according to the ideal natural frequency f' of the structure required in the modal matching condition constructed in Step 2, so that the natural frequency f of the structure reaches the ideal natural frequency f' when the modal matching condition is satisfied. Utilize the spatial correlation of the dynamic load and the coupling effect between the dynamic load mode and the structural vibration mode to achieve structural vibration suppression, and then achieve fluid-induced vibration suppression based on modal matching under the action of the dynamic load.

2. The flow-induced vibration suppression method based on modal matching according to claim 1, wherein: The number N of structural modal characteristics s is expressed as shown in formula (1) Among them, N s is the number of structural modal characteristics, a is the structural flow length, and λ s is the structural resonance modal wavelength; The load modal characteristic number N f has an expression as shown in formula (2) Among them, N f is the number of load mode characteristics, and λ f is the wavelength of the dynamic load.

3. The flow-induced vibration suppression method based on modal matching according to claim 2, characterized in that: The implementation method of Step 2 is, Based on the structural dynamic response characteristics of the mode to be suppressed under dynamic loads selected in Step 1, construct a mode matching condition between the dynamic load mode and the structural vibration mode; the mode matching condition is that when the structural mode characteristic number N s is an odd multiple of 0.5, the structural dynamic response will be at the trough in the periodic fluctuation of the dynamic response when the load mode characteristic number N f is an odd multiple of 0.5 and the load mode characteristic number N f is not equal to the structural mode characteristic number N s ; when the structural mode characteristic number N s is an even multiple of 0.5, the structural dynamic response will be at the trough in the periodic fluctuation of the dynamic response when the load mode characteristic number N f is an even multiple of 0.5 and the load mode characteristic number N f is not equal to the structural mode characteristic number N s ; According to the dynamic load modal characteristic number N f and the flow direction length a of the structure, calculate the dynamic load wavelength λ f , the dynamic load wavelength λ f is obtained from formula (2), and when the modal matching condition is reached, the dynamic load wavelength λ f , the convection velocity U c and the relationship between the ideal natural frequency f′ of the structure satisfy formula (3) where f′ is the ideal natural frequency of the structure, and U c is the convection velocity, and the convection velocity U c is obtained from the free stream velocity U ∞ The relationship between them is shown in Equation (4); U c = 0.65U ∞ (4) where U c is the convective velocity and U ∞ is the free-stream velocity; According to the wavelength λ of the dynamic load f and the convection velocity U c and the relationship of the frequency, the ideal natural frequency f′ of the structure when the modal matching condition is satisfied is obtained, that is, according to the matching relationship (3), the ideal natural frequency f′ of the structure when the modal matching condition is satisfied is obtained, so that the dynamic response of the structure is located at the trough of the periodic fluctuation of the dynamic response.

4. The flow-induced vibration suppression method based on modal matching according to claim 3, characterized in that: The structural optimization includes stiffening or grooving. The structural optimization parameters include the position of stiffening or grooving, the width-to-height ratio of the rib or groove, and the mass ratio of the rib or groove.

5. The flow-induced vibration suppression method based on modal matching according to claim 4, characterized in that: The structural optimization selects stiffening or grooving according to the magnitude relationship between the structural natural frequency f and the ideal natural frequency f' when modal matching is achieved. The implementation method is as follows, Increasing the structural natural frequency \(f\) by stiffening: When the structural natural frequency \(f\) is less than the ideal natural frequency \(f'\), increase the structural natural frequency \(f\) by stiffening; determine the position of the rib, the rib width-to-height ratio \(\delta\) j and the rib mass ratio \(\omega\) j ; The width-to-height ratio δ of the rib j Obtained from formula (5) Among them, b j is the rib width, h j is the rib height; The mass ratio ω of the rib j Obtained from formula (6) where m j is the mass of the rib and m is the mass of the flat structure; Lowering the natural frequency f of the structure by grooving: When the natural frequency f of the structure is greater than the ideal natural frequency f′, lower the natural frequency f of the structure by grooving; determine the position of the groove, the width-to-height ratio δ of the groove c and the mass ratio ω of the groove c ; The groove width-to-height ratio δ c Obtained from formula (7) Among them, b c is the groove width, and h c is the groove height; The groove mass ratio ω c Obtained from formula (8) where m c is the groove quality and m is the flat structure quality.

6. A flow-induced vibration suppression method based on modal matching according to claim 1, 2, 3, 4 or 5, characterized in that: The field of fluid-induced vibration suppression of the structure includes fluid-induced vibration suppression of aircraft structures and fluid-induced vibration suppression of ship structures; by suppressing the fluid-induced vibration of the aircraft structure, the vibration reduction efficiency of the aircraft structure is improved, the refinement and lightweight of the aircraft structure are realized, and the structural safety of the aircraft during high-speed flight is improved; by suppressing the fluid-induced vibration of the ship structure, the vibration reduction efficiency of the ship structure is improved, the concealment of the ship is optimized, the exposure risk is reduced, and the structural safety of the ship is improved.

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