Multi-frequency cantilever beam superstructure reinforced wallboard

Abstract

The present application relates to the technical field of vibration passive control, and provides a multi-frequency cantilever beam superstructure stiffened panel, which comprises a base stiffened panel and a plurality of resonance units; the base stiffened panel is provided with a rib on the surface, and the rib divides the base stiffened panel into a plurality of periodic structure units; a plurality of resonance units are arranged in each periodic structure unit and fixedly installed on the rib; the plurality of resonance units have a plurality of different natural frequencies, and the plurality of different natural frequencies are distributed in a preset neighborhood of a target modal frequency of the base stiffened panel, and are used for generating local resonance when an external excitation frequency approaches the target modal frequency. The present application widens an effective vibration suppression frequency band through a multi-frequency local resonance superposition effect, and realizes wide-frequency vibration reduction and sound radiation collaborative suppression.

Description

Technical Field

[0001] This invention belongs to the field of passive vibration control technology and provides a multi-frequency cantilever beam superstructure stiffened wall panel. Background Technology

[0002] With the development of green aviation, the problem of vibration reduction and noise reduction of aircraft fuselage panels has become increasingly prominent. Panel vibration and its radiated noise not only directly affect the structural fatigue life and passenger comfort, but also reduce the reliability of airborne precision equipment. Therefore, how to effectively suppress the low-frequency vibration and sound radiation of aircraft fuselage panels has become an important research direction.

[0003] Currently, local resonant superstructures achieve dynamic coupling between the resonator and the matrix structure by periodically adding a resonator to the matrix structure. When the external excitation frequency approaches the natural frequency of the resonator, some vibrational energy is transferred to the resonator, thereby reducing the vibration response of the matrix structure and suppressing acoustic radiation.

[0004] However, existing local resonant structures are usually designed with a single type of resonator for a single discrete natural frequency of the matrix structure, resulting in an excessively narrow local resonant bandgap. When the external excitation frequency deviates from the design frequency, the vibration reduction and noise reduction effect drops sharply, making it difficult to adapt to complex and variable multi-frequency excitation environments. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a multi-frequency cantilever beam superstructure stiffened wall panel that can achieve broadband vibration suppression and sound radiation control within the target frequency band.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A multi-frequency cantilever beam superstructure stiffened wall panel includes a base stiffened wall panel and multiple resonant units. The surface of the base stiffened wall panel is provided with ribs, which divide the base stiffened wall panel into multiple periodic structural units. Each periodic structural unit is provided with multiple resonant units, which are fixedly installed on the ribs. The multiple resonant units have a variety of different natural frequencies, which are distributed within a preset neighborhood of the target modal frequency of the base stiffened wall panel, and are used to generate local resonance when the external excitation frequency is close to the target modal frequency.

[0007] The above solution solves the problem of the narrow bandgap of a single-frequency resonator by densely distributing multiple resonant units with different natural frequencies in the neighborhood of the target modal frequency of the reinforced wall plate.

[0008] Optionally, the ribs are arranged in a crisscross pattern to divide the reinforced wall panel into multiple periodic structural units in rectangular cell regions; multiple resonant units within each periodic structural unit are arranged radially or in a cross shape.

[0009] Optionally, the resonant unit includes a cantilever beam resonator and an additional mass block; one end of the cantilever beam resonator is fixed to the reinforcing bar, and the other end is a free end extending toward the center of the periodic structural unit; the additional mass block is fixedly connected to the free end.

[0010] Optionally, the target modal frequency is the main modal response peak of the matrix stiffened wall panel in the target low-frequency range; the natural frequencies of the multiple resonant units correspond to multiple target tuning frequencies distributed around the main modal response peak.

[0011] Optionally, the resonant unit includes a cantilever beam resonator and an additional mass block; the cantilever beam resonator has an effective length and cross-sectional dimensions, and its natural frequency is determined based on the effective length, cross-sectional dimensions, and the mass of the additional mass block.

[0012] Optionally, the periodic structural unit contains two, four, or eight resonant units with different natural frequencies to form a dual-frequency, four-frequency, or eight-frequency local resonant layout, respectively; the resonant units corresponding to different natural frequencies are allocated in the periodic structural unit according to a preset quantity ratio.

[0013] Optionally, the cantilever beam resonator is fixed to the reinforcing bars by adhesive bonding or welding; an additional mass block is fixedly connected to the top of the free end.

[0014] Optionally, the base reinforcement panels and stiffeners are made of aluminum alloy; the stiffeners have a C-shaped cross-section.

[0015] The technical solution provided by this invention has the following advantages compared with the prior art: The multi-frequency cantilever beam superstructure stiffened wall panel provided by this invention sets multiple resonant units with different natural frequencies within a preset neighborhood of the main modal response peak of the stiffened wall panel, and integrates these resonant units into a single periodic structural unit for periodic arrangement, forming a multi-frequency supercellular periodic integrated structure. Compared with traditional local resonance structures designed for a single discrete frequency, this structure utilizes the superposition and dynamic coupling of local resonances of multiple resonant units in the target frequency band to effectively transfer the vibration energy of the stiffened wall panel to the resonant units and dissipate it through damping, thereby significantly broadening the effective vibration suppression frequency band. This frequency configuration ensures that the stiffened wall panel always has matching resonant units in operation when facing external multi-frequency or variable-frequency excitations, greatly improving the structure's adaptability to complex vibration environments. Simultaneously, the reduction in vibration response directly reduces the normal vibration velocity on the wall panel surface, thereby achieving synchronous suppression of the structure's acoustic radiation level, achieving the technical effect of broadband vibration reduction and noise reduction synergistic control.

[0016] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the multi-frequency cantilever beam superstructure reinforced wall panel according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the layout of the periodic structural unit according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the cantilever beam resonator and the additional mass block structure according to an embodiment of the present invention.

[0021] Figure 4 This is a comparison diagram of the vibration displacement response of the superstructure reinforced wall panel and the base wall panel in an embodiment of the present invention.

[0022] Figure 5 This is a comparison diagram of the sound pressure level distribution between the superstructure reinforced wall panel and the base wall panel in an embodiment of the present invention.

[0023] Figure 6 This is a comparison graph of the vibration acceleration frequency response functions of stiffened wall panels with different layouts according to embodiments of the present invention.

[0024] Figure 7 This is a comparison diagram of the sound pressure level frequency response of reinforced wall panels with different layouts according to embodiments of the present invention.

[0025] Figure 8 This is a comparison diagram of the vibration acceleration response of the stiffened wall panel and the superstructure panel in an embodiment of the present invention.

[0026] Figure 9 This is a diagram showing the experimental setup for acoustic radiation testing according to an embodiment of the present invention.

[0027] Figure 10 This is a comparison chart of sound pressure level versus frequency in an embodiment of the present invention.

[0028] Among them, 1-base reinforced wall panel, 2-stiffener, 3-cantilever beam resonator, 4-additional mass block, 5-four-sided fixed support clamp, 6-microphone array. Detailed Implementation

[0029] The following detailed description of a specific embodiment of the present invention is provided in conjunction with the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0030] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] In the description of the embodiments of the present invention, unless otherwise stated, "a plurality of" means two or more.

[0032] Example 1: like Figure 1 As shown, this embodiment provides a multi-frequency cantilever beam superstructure stiffened wall panel. This stiffened wall panel, as a typical superstructure, aims to solve the problem of difficult vibration and noise control under low-frequency broadband excitation in traditional stiffened wall panels. The multi-frequency cantilever beam superstructure stiffened wall panel mainly includes a base stiffened wall panel 1 and multiple resonant units.

[0033] Specifically, the base-reinforced wall panel 1 serves as the basic load-bearing structure, and its surface is provided with ribs 2. These ribs 2 not only enhance the rigidity of the wall panel but also regularly divide the surface space of the base-reinforced wall panel 1 into multiple periodic structural units. This periodic division is the physical basis for constructing the superstructure, allowing additional functional units to be arranged in an orderly array. It should be understood that although the figure shows the ribs 2 in a crisscrossing grid pattern, in other embodiments, the ribs 2 can also be arranged in triangular, hexagonal, or other topological forms, as long as the wall panel can be divided into repeatable periodic structural units.

[0034] Within each periodic structural unit, multiple resonant units are provided, and these resonant units are fixedly mounted on stiffener 2. Mounting the resonant units on stiffener 2, rather than directly on the wall panel skin, utilizes the high local stiffness of stiffener 2, ensuring the reliability of the connection and the stability of the boundary conditions; it also avoids direct perforation or damage to the main body of the base wall panel, maintaining the integrity of the original structure. In this embodiment, the resonant unit is a higher-level concept, and its specific physical implementation is not limited to the cantilever beam structure shown in the figure. It can also be a diaphragm resonator, a mass-spring oscillator, a Helmholtz resonant cavity, or any other dynamic structure capable of generating a strong local vibration response near its natural frequency. Regardless of the specific form adopted, its core function is to act as an independent dynamic oscillator system, controlling wave propagation or dissipating vibrational energy through dynamic coupling with the base structure.

[0035] The core feature of this embodiment is that multiple resonant units have various natural frequencies, and these different natural frequencies are distributed within a preset neighborhood of the target modal frequency of the stiffened substrate 1. This is used to generate local resonance when the external excitation frequency approaches the target modal frequency. Here, "preset neighborhood" refers to a continuous frequency range extending outwards from the main modal response peak of the stiffened substrate 1 in a specific low-frequency range. This is fundamentally different from the "point-to-point" matching strategy in the prior art, which designs a single-frequency resonator for each discrete natural frequency of the structure. In this invention, the natural frequencies of multiple resonant units do not correspond to different modal orders in isolation, but are densely clustered around the same main response peak, forming a frequency cluster.

[0036] With this frequency configuration method, when external broadband or variable frequency excitation is applied to the wall panel, as long as the excitation frequency falls within the preset neighborhood range, a portion of the resonant units within the periodic structural unit will have natural frequencies that match or approach the current excitation frequency, thus generating local resonance. Since resonant units with different natural frequencies are closely adjacent in the frequency domain, their local resonance effects overlap and merge in the frequency band, thereby constructing a continuous, broadband equivalent bandgap or high-damping region. This multi-frequency local resonance superposition mechanism effectively overcomes the shortcomings of single-frequency local resonance structures, such as excessively narrow bandgap and sensitivity to frequency deviations. It significantly improves the stiffened wall panel's adaptability to complex and variable vibration environments, achieving continuous and efficient transfer and dissipation of vibration energy within the target frequency band.

[0037] Example 2: In some embodiments, the ribs 2 are arranged in a crisscross pattern to divide the base reinforced wall panel 1 into multiple periodic structural units that are rectangular cell regions; multiple resonant units within each periodic structural unit are arranged radially or in a cross shape. Specifically, as... Figure 2As shown, the crisscrossing ribs 2 form a regular grid framework. This rectangular cell division not only conforms to the typical structural features of aerospace stiffened panels but also provides a standardized minimum repeating unit, or supercell, for the periodic array of the superstructure. Within each rectangular cell, multiple resonant units are arranged in a radial or cross-shaped symmetrical layout. This arrangement makes full use of the limited space within the cell, ensuring structural compactness while giving the resonant units uniform dynamic response characteristics in all directions, avoiding coupling mode splitting caused by asymmetrical layout. It should be understood that although the figure shows rectangular cells and a specific arrangement, in other embodiments, as long as periodic arrangement can be achieved and sufficient installation space is provided, other topological cell forms such as triangles and hexagons, and corresponding asymmetrical arrangements, are also feasible.

[0038] Furthermore, the resonant unit includes a cantilever beam resonator 3 and an additional mass block 4; one end of the cantilever beam resonator 3 is fixed to the stiffener 2, and the other end is a free end extending towards the center of the periodic structural unit; the additional mass block 4 is fixedly connected to the free end. Figure 3 As shown, this is a specific physical implementation of the resonant unit. The cantilever beam resonator 3, as an elastic element, is firmly anchored at its root to the stiff rib 2, while its free end is suspended pointing towards the geometric center of the cell. This spatial orientation design extending towards the center is crucial. On the one hand, it avoids mechanical interference between the resonant unit and the structure within adjacent cells, ensuring the degree of freedom of vibration; on the other hand, by using the distance from the edge of rib 2 to the center of the cell as the effective cantilever length, a large flexible lever arm is obtained without increasing the additional area occupied, which is beneficial for obtaining a lower natural frequency in the low-frequency range. The additional mass block 4, as an inertial element, is fixed to the free end to adjust the equivalent mass of the resonant unit, thereby precisely tuning its resonant frequency.

[0039] In terms of connection technology, the cantilever beam resonator 3 is fixed to the stiffener 2 by adhesive bonding or welding; the additional mass block 4 is fixedly connected to the top of the free end. Specifically, adhesive bonding provides good damping characteristics and reduces stress concentration, making it suitable for scenarios with high fatigue life requirements; welding provides higher connection stiffness and long-term stability, ensuring that the boundary conditions are close to the ideal fixed-support state, thereby improving the accuracy of frequency prediction. The additional mass block 4 is installed at the top of the free end rather than the bottom or side. This arrangement causes the center of mass of the mass block to deviate from the neutral axis of the cantilever beam, introducing a small torsional-bending coupling effect during vibration, which helps to further fine-tune the frequency and increase the modal density. Of course, in addition to top mounting, depending on the actual frequency tuning requirements, the additional mass block 4 can also be placed at the bottom of the free end or embedded inside the free end, as long as the expected mass loading effect can be achieved.

[0040] Furthermore, as a preferred embodiment, the stiffened base panel 1 and the stiffeners 2 are made of aluminum alloy; the stiffeners 2 have a C-shaped cross-section. Aluminum alloy has high specific strength and excellent acoustic properties, enabling it to reduce overall weight while ensuring structural load-bearing capacity, which is particularly crucial for aircraft applications. Compared to flat stiffeners, the C-shaped stiffeners 2 have higher bending and torsional stiffness, providing a more stable mounting base for the cantilever beam resonator 3 and reducing frequency drift caused by base flexibility. Simultaneously, the recessed space formed by the C-shaped cross-section can also be used to arrange cables or other accessories, improving the structural integration. It should be noted that aluminum alloy and the C-shaped cross-section are only exemplary choices; provided that stiffness and weight constraints are met, other materials such as titanium alloys and composite materials, as well as other cross-sectional forms such as T-shaped and I-shaped sections, are also applicable to the technical solution of this invention.

[0041] Example 3: In some embodiments, the target modal frequency is the main modal response peak of the stiffened substrate 1 in the target low-frequency range; the natural frequencies of the multiple resonant units correspond to multiple target tuning frequencies distributed around the main modal response peak. Specifically, when the stiffened substrate 1 is subjected to external excitation, its vibration energy is not uniformly distributed across all natural frequencies, but is concentrated at a few main modal response peaks that are most sensitive to excitation and have the greatest participation mass. This invention addresses this physical characteristic by locking the target modal frequency to these main energy-concentrated peaks, rather than discrete natural frequencies of all orders. Based on this, the natural frequencies of the multiple resonant units do not simply coincide with this peak, but are densely arranged within a preset frequency range on both sides of the peak, forming a cluster of target tuning frequencies distributed around the main peak. This distribution pattern ensures that when the external excitation frequency drifts or fluctuates near the main peak, there will always be a corresponding frequency resonant unit that can be excited to generate local resonance. Thus, through the superposition and fusion of multi-frequency resonance effects, a wideband gap covering the entire main response region is constructed, effectively overcoming the limitation that traditional single-frequency vibration absorbers can only be effective in extremely narrow frequency bands.

[0042] Furthermore, the resonant unit includes a cantilever beam resonator 3 and an additional mass block 4; the cantilever beam resonator 3 has an effective length and cross-sectional dimensions, and its natural frequency is determined based on the effective length, cross-sectional dimensions, and the mass of the additional mass block 4. In this embodiment, the cantilever beam resonator 3 can be equivalently represented as a spring-mass system, and its dynamic characteristics are determined by its equivalent stiffness and equivalent mass. According to the Euler-Bernoulli beam bending theory, the equivalent stiffness of the cantilever beam resonator 3... Represented as:

[0043] In the formula, The elastic modulus of the cantilever beam material. Let be the moment of inertia of the cross section of the cantilever beam harmonic oscillator. Let be the length of the cantilever beam harmonic oscillator. Where is the moment of inertia. , The width of the cross section of the cantilever beam harmonic oscillator. The thickness of the cross section of the cantilever beam resonator.

[0044] Considering the combined effect of the cantilever beam's own mass and the additional mass at its ends, the equivalent mass is calculated using its first-order mode shape function. Represented as: In the formula, The density of the cantilever beam material, The cross-sectional area of ​​the cantilever beam is and , Let be the first-order mode shape function of the cantilever beam. The mass of the added mass block 4. First-order mode shape function. Specifically, it can be expressed as follows:

[0045] In the formula, The coordinates are along the length of the cantilever beam. The wavenumber parameter is satisfied. .

[0046] Therefore, the first natural frequency of the cantilever beam resonator 3 Represented as: In the formula, The equivalent stiffness of the cantilever beam harmonic oscillator. This represents the equivalent mass of the cantilever beam resonator. The above formula reveals the mapping relationship between the inherent structural parameters and frequency of this product. Specifically, by adjusting the effective length of the cantilever beam resonator 3... Cross-sectional dimensions (width) ,thickness ) and the mass of additional mass block 4 This allows for precise control of its inherent frequency to match a preset target tuning frequency. For example, increasing the effective length... Or increase the mass of the additional mass block 4 It will lower the natural frequency and increase the cross-sectional thickness. This will increase the natural frequency. This frequency determination mechanism based on geometric and mass parameters makes it possible to integrate multiple resonant units with different frequencies within the same periodic structural unit. Moreover, the frequency value of each resonant unit is a stable property directly determined by its physical structure, ensuring the consistency and reliability of the frequency configuration of the multi-frequency cantilever beam superstructure stiffened panel during long-term use.

[0047] Example 4: In some embodiments, the periodic structural unit contains resonant units with two, four, or eight natural frequencies to form dual-frequency, four-frequency, or eight-frequency local resonance layouts, respectively; the resonant units corresponding to different natural frequencies are allocated within the periodic structural unit according to a preset quantity ratio. This feature reveals the flexibility and adaptability of the frequency configuration strategy for multi-frequency cantilever beam superstructure stiffened wall panels. Specifically, although the foregoing embodiments illustrate the general principle of dense arrangement within the target modal frequency neighborhood, in actual engineering applications, the frequency points within this neighborhood do not necessarily have to be uniformly distributed or fixed to a specific number. Instead, a trade-off can be made between the richness of frequency types and the suppression depth at a single frequency, depending on the specific vibration reduction and noise reduction requirements.

[0048] To more intuitively illustrate the differences in technical effects between different layout modes, this embodiment compares and analyzes three typical layouts—dual-frequency (2F), quad-frequency (4F), and eight-frequency (8F)—based on numerical simulation results. In the simulation model, each periodic structural unit contains the same total of 16 cantilever beam resonators 3, differing only in the number of natural frequencies and the distribution of each type of resonator. For the 2F layout, the unit contains only two natural frequencies, with eight resonators for each frequency; for the 4F layout, it contains four natural frequencies, with four resonators for each frequency; and for the 8F layout, it contains eight natural frequencies, with two resonators for each frequency. This variable control, under the premise of a basically consistent total added mass ratio, can effectively isolate the mass effect and purely reflect the influence of the frequency topology on the dynamic response.

[0049] like Figure 6The comparison of vibration acceleration frequency response functions shows that different frequency configuration strategies exhibit significant performance trade-offs. The 2F layout, by concentrating limited resonator resources on two target frequency points, demonstrates extremely strong local vibration suppression capabilities near these specific frequencies. For example, near 60.7Hz, the 2F layout reduces the vibration acceleration transmissivity by approximately 95.6% compared to the unstiffened substrate 1, creating a very deep suppression valley. However, this high depth of suppression comes at the cost of sacrificing effective bandwidth; once the external excitation frequency deviates from these two design frequencies, the suppression effect rapidly diminishes, and may even induce new secondary response peaks in adjacent frequency bands. In contrast, the 4F and 8F layouts, by distributing the resonator to more target frequency points, make the local resonance effects more dispersed and overlapping in the frequency domain. Although the maximum suppression amplitude at a single frequency is slightly lower than that of the 2F layout, their frequency response curves are generally flatter in the target low-frequency range, and the effective suppression bandwidth is significantly broadened. This means that when the external excitation has wide frequency characteristics or the frequency is uncertain, the 4F and 8F layouts can provide more robust and uniform vibration control.

[0050] Further integration Figure 7 The comparison of sound pressure level frequency response results shows that the aforementioned vibration response variation directly maps to the sound radiation characteristics. At 58.9Hz, the 2F layout, with its strong suppression of the main resonance peak, significantly reduces the sound pressure level from 119.88dB to 98.99dB, a reduction of 20.89dB, demonstrating its precise noise reduction capability targeting specific annoying noise frequencies. While the 4F and 8F layouts have slightly lower absolute noise reduction at the peak, they maintain low sound radiation levels over a wider frequency range, avoiding noise reduction failure due to frequency drift. This differentiated technical effect indicates that the multi-frequency cantilever beam superstructure stiffened wall panel provided by this invention is not limited to a fixed frequency configuration, but rather constructs a design space that can be customized according to actual working conditions. If there is a clear and stable dominant interference frequency in the application scenario, the 2F layout can be preferentially selected to obtain the ultimate suppression effect; if facing a complex and variable random vibration environment with a wide frequency spectrum, the 4F or 8F layout is a more suitable choice. It should be understood that the above 2F, 4F, and 8F are merely illustrative examples. In other embodiments, depending on the actual modal density and vibration reduction index requirements of the base reinforced wall panel 1, a combination of three-frequency, six-frequency, or other frequencies can be adopted. As long as the core condition that multiple natural frequencies are distributed within the preset neighborhood of the target modal frequency is met, they all fall within the protection scope of this invention.

[0051] Example 5: In some embodiments, an aircraft is provided, including a fuselage with fuselage panels. These fuselage panels are multi-frequency cantilever beam superstructure stiffened panels as described in any of the preceding embodiments. Specifically, the aircraft can be an airplane, helicopter, or unmanned aerial vehicle (UAV); the fuselage panels can be fuselage skin or bulkheads. During aircraft operation, external excitations such as engine operation and aerodynamic turbulence often exhibit broadband characteristics and easily excite the main modal responses of the fuselage panels in the low-frequency range, thereby generating strong structural vibrations and cabin noise. Applying the aforementioned multi-frequency cantilever beam superstructure stiffened panels to the fuselage panels of an aircraft can utilize their multi-frequency local resonance superposition mechanism to achieve synergistic suppression of vibrations and sound radiation in the target low-frequency range without significantly increasing structural weight. It should be understood that although this embodiment lists airplanes, helicopters or drones as typical application objects, the applicability of this technical solution is not limited to these. Any aerospace vehicle or other vehicle facing similar low-frequency broadband vibration and noise control needs can use the multi-frequency cantilever beam superstructure stiffened wall panel provided by this invention as its body wall panel or key load-bearing partition.

[0052] To verify the actual vibration reduction and noise reduction effect of the multi-frequency cantilever beam superstructure stiffened panel under simulated aircraft operating conditions, this embodiment further provides performance verification based on experimental testing. An experimental component of the multi-frequency cantilever beam superstructure stiffened panel was fabricated and fixed using a four-sided fixed support clamp 6 to simulate the boundary constraints of an aircraft fuselage panel during actual assembly. The dimensions and material parameters of the base stiffened panel 1 and stiffeners 2 of the experimental component are consistent with the aforementioned simulation model. The cantilever beam resonator 3 was specifically designed and glued based on the measured modal frequencies, with an added mass ratio of approximately 7.17%. This frequency tuning method based on measured modes ensures that the resonant unit can effectively cover the main energy concentration area of ​​the experimental component in the target low-frequency range.

[0053] In vibration response testing, such as Figure 8 The experimental results show that after installing the cantilever beam resonator 3, the vibration acceleration response of the superstructure stiffened panel in the target low-frequency range is significantly lower than that of the base stiffened panel without the resonator. Particularly in the two main modal response ranges of 62Hz to 70Hz and 86Hz to 90Hz, the amplitude of the frequency response curve of the superstructure panel shifts significantly downward, demonstrating excellent vibration damping performance. Notably, even at non-design frequency points (e.g., near 77.4Hz), the superstructure panel still exhibits a response reduction of approximately 9.06%. This phenomenon strongly demonstrates the advantages of the multi-frequency local resonance layout compared to traditional single-frequency vibration absorbers: because the natural frequencies of multiple resonant units are densely distributed in the neighborhood of the target modal frequency, the resonance effects of adjacent frequencies overlap and merge, forming an equivalent damping band of a certain width, making the structure more robust and adaptable to the drift or fluctuation of external excitation frequencies.

[0054] In terms of verifying the effectiveness of sound radiation suppression, such as Figure 9 As shown, a sound radiation testing platform, including a vibration system, a data acquisition system, and a microphone array 6, was built in an anechoic chamber to eliminate interference from environmental noise and reflected sound. Figure 10 The comparison curves showing the change in sound pressure level with frequency demonstrate that, within the effective analysis frequency band, the sound radiation level of the superstructure wall panel after installing the cantilever beam resonator 3 was significantly improved near multiple target frequencies. Specifically, the data shows that at 59.81 Hz, the sound pressure level of the unstiffened wall panel was 43.21 dB, which decreased to 33.56 dB after installing the cantilever beam resonator, a reduction of 9.65 dB; at 77.51 Hz, the sound pressure level decreased from 55.78 dB to 41.82 dB, a reduction of 13.96 dB. These experimental results reveal the physical mechanism by which the multi-frequency cantilever beam superstructure stiffened wall panel achieves coordinated control of vibration reduction and noise reduction: the local resonance effect transfers the vibration energy of the stiffened wall panel 1 to the cantilever beam resonator 3 and dissipates it through damping, directly reducing the normal vibration velocity of the wall panel surface. Since the structural sound radiation power is proportional to the square of the surface normal vibration velocity, the reduction in vibration response inevitably leads to a synchronous decrease in the sound radiation level. This vibration-sound synergistic suppression effect has significant engineering application value for improving acoustic comfort inside aircraft cabins and the reliability of airborne equipment. It should be noted that the above experimental data is only a verification example of the technical solution of this invention under specific experimental conditions. In actual aircraft applications, the types, proportions, and geometric parameters of the natural frequencies of the resonant units within the periodic structural unit can be flexibly adjusted according to the main modal frequency distribution and vibration reduction / noise reduction requirements of the specific aircraft model to obtain optimal overall performance.

[0055] It should be noted that any parts not disclosed or specifically described in this invention are existing technology or conventional configurations, and their specific structures and working principles will not be elaborated further. In this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0056] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily implemented by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A multi-frequency cantilever beam superstructure reinforced wall panel, characterized in that, include: A base-reinforced wall panel, wherein the surface of the base-reinforced wall panel is provided with ribs, the ribs dividing the base-reinforced wall panel into multiple periodic structural units; Multiple resonant units are provided in each periodic structural unit, and the resonant units are fixedly connected to the ribs. The plurality of resonant units have a variety of different natural frequencies, which are distributed within a preset neighborhood of the target modal frequency of the stiffened wall panel of the substrate, and are used to generate local resonance when the external excitation frequency is close to the target modal frequency.

2. The multi-frequency cantilever beam superstructure reinforced wall panel according to claim 1, characterized in that, The ribs are arranged in a crisscross pattern to divide the base reinforced wall panel into multiple periodic structural units that are rectangular cell regions; The resonant units within each periodic structural unit are arranged radially or in a cross shape.

3. The multi-frequency cantilever beam superstructure reinforced wall panel according to claim 2, characterized in that, The resonant unit includes a cantilever beam resonator and an additional mass block; One end of the cantilever beam resonator is fixed to the rib, and the other end is a free end extending toward the center of the periodic structural unit; The additional mass block is fixedly connected to the free end.

4. The multi-frequency cantilever beam superstructure reinforced wall panel according to claim 1, characterized in that, The target modal frequency is the main modal response peak of the matrix-reinforced wall panel in the target low-frequency range; The natural frequencies of the plurality of resonant units correspond to a plurality of target tuning frequencies distributed around the main modal response peak.

5. A multi-frequency cantilever beam superstructure reinforced wall panel according to claim 4, characterized in that, The resonant unit includes a cantilever beam resonator and an additional mass block; The cantilever beam resonator has an effective length and a cross-sectional dimension, and the natural frequency is determined based on the effective length, the cross-sectional dimension, and the mass of the additional mass block.

6. The multi-frequency cantilever beam superstructure reinforced wall panel according to claim 4, characterized in that, The periodic structural unit contains two, four, or eight resonant units with the inherent frequencies, so as to form a dual-frequency, four-frequency, or eight-frequency local resonant layout, respectively. The resonant units corresponding to different inherent frequencies are distributed in the periodic structure unit according to a preset quantity ratio.

7. A multi-frequency cantilever beam superstructure reinforced wall panel according to claim 3, characterized in that, The cantilever beam resonator is fixed to the reinforcing bar by adhesive bonding or welding. The additional mass block is fixedly connected to the top of the free end.

8. A multi-frequency cantilever beam superstructure reinforced wall panel according to claim 1, characterized in that, The base reinforced wall panel and the ribs are made of aluminum alloy. The reinforcing bars have a C-shaped cross-section.

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