Trigonometric function truss type buoyant raft vibration isolation device with low-frequency vibration reduction characteristic and preparation method of trigonometric function truss type buoyant raft vibration isolation device

Abstract

The trigonometric function truss type floating raft vibration isolation device with the low-frequency vibration reduction characteristic comprises a trigonometric function truss type floating raft, the trigonometric function truss type floating raft comprises an upper-layer raft frame and a lower-layer raft frame, and a plurality of trigonometric function structure oblique beams are arranged between the upper-layer raft frame and the lower-layer raft frame; the center line of the trigonometric function structure cant beam is a periodic trigonometric function curve, and the trigonometric function structure cant beam is used for attenuating vibration propagating in the thickness direction of the buoyant raft through wave transmission and conversion. The overall rigidity and inherent frequency of the system are remarkably reduced, and specific low-frequency vibration energy is effectively dispersed and dissipated through reflection, interference and energy localization effects of waves, so that excellent vibration isolation performance is realized in a wide low-frequency range, and a vibration transmission curve shows a remarkable narrow-band valley value in a target frequency band.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vibration reduction and isolation structure for ships and submarines, and particularly relates to a trigonometric function truss type floating raft vibration isolation device with low frequency vibration reduction characteristics and a preparation method thereof. BACKGROUND

[0002] The core combat effectiveness of modern ships, especially submarines, is stealth. One of the main sources of noise of a submarine is the vibration generated by the mechanical equipment (such as diesel generators, water pumps, compressors, etc.) working inside the submarine. When the submarine is sailing underwater, a certain amount of noise is emitted due to the propeller hitting the water, the operation of various mechanical and electrical equipment, the friction and impact of the ship body with the water flow, which is radiated to the water through the ship body, resulting in a significant increase in the sound field intensity of the sailing sea area, becoming the target of enemy underwater detection equipment. Therefore, the noise level of a submarine is a key factor that determines its survival and success in combat. Large submarine noise not only exposes itself and destroys its stealth, but also seriously interferes with the work of the submarine's underwater equipment, making the submarine lose its senses and completely passive.

[0003] Vibration isolation technology is a technology that aims to reduce various vibrations and shocks experienced by ships when operating at sea. It improves the comfort and stability of ships and also improves the service life and reliability of equipment and structural components. There are many types and methods of ship vibration isolation technology, among which the most common is the vibration isolation method based on floating rafts and shock absorbers. Floating rafts need to face many challenges when working at sea, including the influence of sea waves and marine environment. Sea waves and wind waves can cause various vibrations and shocks of the floating raft, seriously affecting work efficiency and quality, and also accelerating the damage of the floating raft and equipment.

[0004] Currently, the traditional truss type floating raft vibration isolation device used in floating raft vibration isolation devices has a high natural frequency, which is difficult to optimize. The structural stiffness distribution is fixed, the dynamic characteristics are single, and the effect of isolating medium and low frequency vibrations is poor. The metal truss itself has small damping, and the vibration energy is mainly dissipated by the shock absorber, and the truss itself will "ring" for a long time. SUMMARY

[0005] The present application aims to solve the problems in the prior art and provides a trigonometric function truss type floating raft vibration isolation device with low frequency vibration reduction characteristics and a preparation method thereof, to solve the technical problem of poor medium and low frequency vibration isolation effect caused by the high natural frequency of the traditional floating raft truss in the prior art.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is: a triangular function truss type floating raft vibration isolation device with low frequency damping characteristics, comprising a triangular function truss type floating raft, the triangular function truss type floating raft comprises an upper raft frame and a lower raft frame, the upper raft frame and the lower raft frame are fixedly connected through a plurality of vertical vertical beams, and a plurality of triangular function structure inclined beams are arranged between the upper raft frame and the lower raft frame; the center line of the triangular function structure inclined beam is a periodic triangular function curve, which is used for transmitting and converting waves and attenuating vibration propagating along the thickness direction of the floating raft.

[0007] Preferably, the upper raft frame and the lower raft frame are frame body structures composed of a plurality of cross beams and a plurality of straight beams.

[0008] Preferably, the top and bottom of the triangular function truss type floating raft are provided with a plurality of vibration isolator assemblies for installing equipment.

[0009] Preferably, the vibration isolator assembly comprises an upper vibration isolator and a lower vibration isolator arranged on the top of the upper raft frame and the bottom of the lower raft frame, respectively.

[0010] Preferably, the triangular function structure inclined beam is fixedly connected with the cross beam of the upper raft frame and the lower raft frame through welding, respectively.

[0011] Preferably, the cross beam and the straight beam are made of metal material, and the triangular function structure inclined beam is made of light metal.

[0012] Preferably, the cross beam and the straight beam are made of carbon steel, and the triangular function structure inclined beam is made of aluminum alloy.

[0013] Preferably, the vertical beam is made of elastic material.

[0014] Preferably, the plurality of triangular function inclined beams are arranged along the length direction and the width direction of the triangular function truss type floating raft, respectively.

[0015] Preferably, the present application also relates to a preparation method of a triangular function truss type floating raft vibration isolation device with low frequency damping characteristics, comprising the following steps: S1, using a combination of ABAQUS and MATLAB simulation to calculate the structure parameters of the triangular function structure inclined beam; S2, using 3D modeling software to establish a whole model of the triangular function truss type floating raft vibration isolation device, and completing the raft frame design; S3, installing the vibration isolator on the upper part and the lower part of the triangular function truss type floating raft vibration isolation device, and completing the preparation of the triangular function truss type floating raft vibration isolation device.

[0016] The present application has the following advantages: The present application adopts the triangular function structure inclined beam with continuous gradual curvature, which can ensure high bearing capacity, significantly reduce the overall stiffness and natural frequency of the system, and effectively disperse and dissipate the specific low-frequency vibration energy through wave reflection, interference and energy localization effect, so as to realize excellent vibration isolation performance in a wide low-frequency range, and the vibration transmission curve presents a significant narrow-band valley value in the target frequency band. BRIEF DESCRIPTION OF DRAWINGS

[0017] The present application will be further described below in combination with the drawings and embodiments.

[0018] Figure 1 Fig. 1 is a perspective view of the triangular function truss type floating raft vibration isolation device of the present application; Figure 2 Fig. 2 is another perspective view of the triangular function truss type floating raft vibration isolation device of the present application; Figure 3 Fig. 3 is a top view of the truss structure of the present application; Figure 4 Fig. 4 is a side view of the truss structure of the present application; Figure 5 Fig. 5 is a schematic view of the triangular function inclined beam in the truss structure of the present application; Figure 6 (a) and (b) are two structural forms of the triangular function inclined beam; Figure 6 In the figure: 1, triangular function truss type floating raft; 11, vertical beam; 12, horizontal beam; 13, triangular function structure inclined beam; 14, straight beam; 2, vibration isolator assembly; 21, upper layer vibration isolator; 22, lower layer vibration isolator; 101, upper layer raft frame; 102, lower layer raft frame. DETAILED DESCRIPTION

[0019] The present application will be further described below in combination with the drawings and embodiments.

[0020] As Figures 1-5 ​As shown, a trigonometric function truss type floating raft vibration isolation device with low frequency damping characteristics, including a trigonometric function truss type floating raft 1, the trigonometric function truss type floating raft 1 includes upper raft frame 101 and lower raft frame 102, the upper raft frame 101 and lower raft frame 102 are fixedly connected by a plurality of vertical vertical beams 11, a plurality of trigonometric function structure inclined beams 13 are arranged between the upper raft frame 101 and the lower raft frame 102; the center line of the trigonometric function structure inclined beam 13 is a periodic trigonometric function curve, which is used to attenuate the vibration propagating along the thickness direction of the floating raft through the transmission and conversion of the wave, and this embodiment lays the foundation for the core structure of the application. This "upper raft frame 101-lower raft frame 102-vertical beam-inclined beam" constitutes a stable space truss system. Among them, the "trigonometric function structure inclined beam" is the core element to realize the low frequency vibration isolation function. It needs to be further clarified that the "vibration propagating along the thickness direction of the floating raft" specifically refers to the path of vibration energy transmission from the upper raft frame 101 (equipment installation side) to the lower raft frame 102 (ship body foundation side), and vice versa. The traditional straight inclined beam or plate type structure mainly relies on the damping and overall stiffness of the material to hinder the vibration on this path, and the inhibition effect on medium and low frequency vibration is limited. The periodic trigonometric function curve inclined beam introduced in the present application is based on the phononic crystal and elastic wave band gap theory. When the vibration wave (elastic wave) propagates in such a periodic structure, it will produce Bragg scattering due to the periodic disturbance of the structure, resulting in the inability of elastic waves in a specific frequency range to pass through, forming a so-called "band gap". Compared with the traditional truss type floating raft, the present application has better static advantages. In the static analysis, the dynamic stiffness of the proposed trigonometric function truss type floating raft remains lower than that of the traditional truss type floating raft within a relatively large displacement range close to static equilibrium. This makes the proposed isolator have a larger low stiffness displacement range, enhancing its ability to achieve low frequency isolation under large amplitude excitation.

[0021] The trigonometric function structure inclined beam proposed in the present application can effectively reduce the overall stiffness of the structure without significantly increasing the mass, thereby reducing the natural frequency of the system. According to the principle of vibration isolation, there is only vibration isolation effect when the excitation frequency is greater than the natural frequency of the system times. Therefore, reducing the natural frequency is a prerequisite for achieving low frequency vibration isolation.

[0022] The trigonometric function truss type floating raft device proposed in the present application has the characteristics of simple structure and high bearing capacity, and can realize vibration isolation in a wide low frequency range.

[0023] The trigonometric function structure inclined beam proposed in the present application, due to the existence of the trigonometric function curve, but when the vibration propagates in it, reflection, refraction and interference occur. This can quickly disperse the vibration energy concentrated in a specific frequency to a wider frequency range and effectively dissipate it.

[0024] This invention combines trigonometric functions with raft frame design, constructing a trigonometric truss-type raft with low-frequency vibration suppression performance by adding trigonometric function inclined beams. Due to the presence of the trigonometric function inclined beams, the curvature of the structure changes continuously, and its stiffness changes smoothly and gradually along the length of the truss. This allows the structure to have different local stiffness at different locations, more effectively guiding and dispersing vibration energy, and achieving vibration reduction.

[0025] The low-frequency vibration isolation characteristics of the trigonometric function inclined beam proposed in this invention are closely related to its geometric parameters and materials. Vibration isolation can be controlled by changing the geometric parameters and materials of the trigonometric function inclined beam, achieving the purpose of on-demand control. Increasing the beam length, amplitude, connection angle, and structural thickness of the trigonometric function inclined beam can reduce the vibration isolation initiation frequency. Trigonometric function curves, such as sine or cosine curves, provide a periodic geometric shape with continuously changing curvature. This shape can more effectively induce the coupling of multiple vibration modes (such as the coupling of bending waves and shear waves) and dissipate vibration energy in a specific area of ​​the curved beam, rather than allowing it to pass smoothly. Therefore, this structure does not passively "block" vibration, but actively "manages" and "transforms" vibration energy, thereby achieving a vibration isolation effect far exceeding that of traditional structures in the target low-frequency range. This design introduces intelligent wave control characteristics while ensuring the overall load-bearing strength of the structure; an upper-level vibration isolator 21 is provided on the upper raft 101, and a lower-level vibration isolator 22 is provided on the lower raft 102. The upper raft 101 and lower raft 102 are connected to the upper and lower vibration isolators 2 via bolt holes, respectively. When vibration is transmitted through the upper raft 101 to the various trigonometric function inclined beams 13, a wave mode conversion effect occurs during the transmission process. This converts the vibration into bending vibration of the trigonometric function inclined beams 13, thus reducing the vibration transmission of the unit equipment and lowering the vibration level and noise radiation level of the foundation structure. This mechanism can also be achieved at low frequencies.

[0026] The trigonometric function truss-type floating raft vibration isolation device of the present invention comprehensively utilizes the wave mode conversion function of the trigonometric function structure. By changing the geometric parameters and materials of the inclined beam 13 of the trigonometric function structure, the stiffness, mass and dynamic characteristics of the structure can be systematically adjusted, thereby adjusting the frequency range of raft vibration suppression, increasing the vibration attenuation effect in the floating raft device, and significantly improving its vibration isolation performance.

[0027] The trigonometric function truss-type floating raft vibration isolation device of the present invention comprehensively utilizes the multi-directional vibration isolation capability generated by the trigonometric function structure and the impedance transformation function of the truss structure. The inclined beam of the trigonometric function structure can not only withstand vertical vibration, but also resist and attenuate horizontal vibration. By adjusting the amplitude, frequency and connection angle of the trigonometric function, the stiffness of the structure in each direction can be accurately designed. Furthermore, the weight of the horizontal floating raft vibration isolation device of the present invention is adjustable, the structure is compact, and it is easy to install.

[0028] The preferred dimensions and material parameters of the trigonometric truss-type floating raft described in this invention are as follows: the cross-sectional shape of each horizontal and vertical beam is square; the height of the horizontal beam is 275mm, and the length and width are 15mm; the height of the vertical beam is 165mm, and the length and width are 15mm. In this embodiment, the mathematical formula for the trigonometric inclined beam is 6.42*sin( The beam is 200mm long, has an amplitude of 12.84mm, a connection angle of 38°, and a structural thickness of 15mm. Figure 4 As shown; the trigonometric function structure inclined beams are all made of aluminum alloy with a Young's modulus of 71,000 MPa, a Poisson's ratio of 0.33, and a density of 2,770 kg / m³; the crossbeams are all made of ordinary carbon steel with a Young's modulus of 205,000 MPa, a Poisson's ratio of 0.29, and a density of 7,800 kg / m³. The vertical beams are all made of rubber with a Young's modulus of 10 MPa, a Poisson's ratio of 0.49, and a density of 1,300 kg / m³. This embodiment provides the dimensions and material parameters of the defined trigonometric function truss-type floating raft, but is not limited to these dimensions. The beam length, amplitude, connection angle, and structural thickness of the trigonometric function structure inclined beam 13 can be arbitrary. The frequency range for raft vibration suppression can be adjusted by changing the materials of the crossbeams 12 and vertical beams 11 or the geometric parameters of the trigonometric function structure inclined beam 13.

[0029] Preferably, the upper raft frame 101 and the lower raft frame 102 are frame structures composed of several horizontal beams 12 and several vertical beams 14, such as... Figure 1 As shown, the trigonometric truss-type floating raft 1 described in this application mainly includes an upper raft frame 101 and a lower raft frame 102 located on two layers. The upper raft frame 101 and the lower raft frame 102 are connected by several vertical beams 14. The beams 14, the upper raft frame 101 and the lower raft frame 102 together constitute the frame of the raft. This structure belongs to the conventional frame structure in this field.

[0030] Preferably, the top and bottom of the trigonometric truss-type floating raft 1 are provided with a plurality of vibration isolator assemblies 2 for installing equipment.

[0031] Preferably, the vibration isolator assembly 2 includes an upper vibration isolator 21 and a lower vibration isolator 22 respectively disposed on the top of the upper raft 101 and the bottom of the lower raft 102. The vibration isolator 2 is a conventional technical solution in the art. In this application, the upper vibration isolator 21 and the lower vibration isolator 22 are respectively installed on the top of the upper raft 101 and the bottom of the lower raft 102.

[0032] Preferably, the trigonometric function structure inclined beam 13 is fixedly connected to the crossbeams 12 of the upper raft 101 and the lower raft 102 respectively by welding, such as... Figure 1 As shown, the trigonometric function structure inclined beam 13 described in this application is fixedly connected to the trigonometric function truss-type floating raft 1 by welding. Welding can form a continuous and rigid connection node, which is crucial to ensuring that no energy loss or mode distortion occurs during the transmission of vibration waves from the crossbeam to the inclined beam.

[0033] Preferably, the crossbeams 12 and 14 are made of metal, while the trigonometric function structure inclined beam 13 is made of lightweight metal. The crossbeams 12 and 14, as the main load-bearing frame, need to possess high rigidity and strength to support the weight of the equipment and maintain the overall structural form; therefore, metal materials such as various structural steels (carbon steel, low-alloy steel) are typically chosen. The trigonometric function structure inclined beam 13 is the core component for achieving vibration isolation; using lightweight metals (such as aluminum alloy, titanium alloy, or magnesium alloy) can effectively reduce the overall mass of the raft frame without significantly sacrificing strength and rigidity. Preferably, the horizontal beam 12 and the vertical beam 14 are made of carbon steel, and the trigonometric function structure inclined beam 13 is made of aluminum alloy. Carbon steel is an extremely mature engineering structural material with excellent weldability, high strength and rigidity, and relatively low cost, making it very suitable for manufacturing the horizontal beam 12 and vertical beam 11 as the main load-bearing structure. Stainless steel or aluminum alloy can also be used, with aluminum alloy having high specific strength (strength to density ratio) and excellent corrosion resistance.

[0034] Preferably, the vertical beam 11 is made of an elastic material. Designing the vertical beam 11 to be made of an elastic material (such as high-damping rubber, polyurethane elastomer, or high-damping composite material) introduces distributed damping into the entire truss system. Its working principle is as follows: when vibration propagates in the structure, the vibration of the rigid main structure (horizontal beams, diagonal beams) drives the elastic vertical beam to undergo reciprocating tensile, compressive, and shear deformation. During this deformation, the elastic material generates significant internal friction between its internal polymer chains or specific fillers, thereby irreversibly converting mechanical vibration energy into heat energy and dissipating it. In this application, the material of the vertical beam 11 is preferably rubber.

[0035] Preferably, the plurality of trigonometric function inclined beams 13 are arranged along the length and width directions of the trigonometric function truss-type floating raft 1, as shown in this embodiment. Figure 1, 2 The aforementioned horizontal beams 12 and vertical beams 11 and straight beams 14 are combined to form a square frame structure. The number of trigonometric function inclined beams 13 are arranged along the length and width directions of the trigonometric function truss floating raft 1.

[0036] Preferably, the present invention also relates to a method for preparing a trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics, comprising the following steps: S1. Use a combination of ABAQUS and MATLAB to simulate and calculate the structural parameters of the trigonometric function structure inclined beam 13; S2. Use 3D modeling software to create an overall model of the trigonometric function truss floating raft vibration isolation device and complete the raft design. S3. Install the vibration isolator 2 on the upper part 14 and lower part 15 of the trigonometric function truss type floating raft vibration isolation device to complete the preparation of the trigonometric function truss type floating raft vibration isolation device.

[0037] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics, characterized in that, The system includes a trigonometric truss-type floating raft (1), which includes an upper raft frame (101) and a lower raft frame (102). The upper raft frame (101) and the lower raft frame (102) are fixedly connected by several vertically arranged vertical beams (11). Several trigonometric structural inclined beams (13) are arranged between the upper raft frame (101) and the lower raft frame (102). The center line of the trigonometric structural inclined beams (13) is a periodic trigonometric function curve, which is used to attenuate the vibration propagating along the thickness direction of the floating raft through wave transmission and conversion.

2. The trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics according to claim 1, characterized in that: The upper raft (101) and the lower raft (102) are frame structures composed of several crossbeams (12) and several straight beams (14).

3. The trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics according to claim 1, characterized in that: The top and bottom of the trigonometric truss raft (1) are provided with several vibration isolator assemblies (2) for installing equipment.

4. The trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics according to claim 3, characterized in that: The vibration isolator assembly (2) includes an upper vibration isolator (21) and a lower vibration isolator (22) respectively disposed at the top of the upper raft (101) and the bottom of the lower raft (102).

5. A trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics according to claim 3, characterized in that: The trigonometric function structure inclined beam (13) is fixedly connected to the crossbeam (12) of the upper raft (101) and the lower raft (102) by welding.

6. The trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics according to claim 2, characterized in that: The crossbeam (12) and the straight beam (14) are made of metal, and the trigonometric function structure inclined beam (13) is made of lightweight metal.

7. A trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics according to claim 6, characterized in that: The crossbeam (12) and the straight beam (14) are made of carbon steel, and the trigonometric function structure inclined beam (13) is made of aluminum alloy.

8. The trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics according to claim 1, characterized in that: The vertical beam (11) is made of an elastic material.

9. A trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics according to claim 1, characterized in that: The aforementioned trigonometric function inclined beams (13) are arranged along the length and width directions of the trigonometric function truss raft (1), respectively.

10. The method for preparing a trigonometric truss-type floating raft vibration isolation device with low-frequency vibration reduction characteristics according to any one of claims 1-9, characterized in that, Includes the following steps: S1. The structural parameters of the trigonometric function structure inclined beam (13) are calculated using a combination of ABAQUS and MATLAB simulations. S2. Use 3D modeling software to create an overall model of the trigonometric function truss floating raft vibration isolation device and complete the raft design. S3. Install the vibration isolator (2) on the upper (14) and lower (15) parts of the trigonometric function truss floating raft vibration isolation device to complete the preparation of the trigonometric function truss floating raft vibration isolation device.

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