A low-vibration high-frequency modal vehicle body structure

Abstract

The present invention relates to a low-vibration high-frequency modal vehicle body structure, comprising a vehicle body base plate (1), a modal adjustment rib (2), and a composite damping layer (3), wherein the modal adjustment rib (2) is arranged on the vehicle body base plate (1) according to the modal adjustment stiffness and position, and is rigidly connected to the vehicle body base plate (1); the composite damping layer (3) is composed of a sound absorbing layer (4), a constraint layer (5), a damping layer (6), and a bonding layer (7) from the outside to the inside, wherein the bonding layer (7) is bonded to the vehicle body base plate (1). Compared with the prior art, the present invention fully considers the structural vibration of the vehicle and the structural noise characteristics caused by the vibration and the frequency effectiveness of damping vibration reduction and noise reduction control, and proposes a low-vibration high-frequency modal vehicle body structure that can effectively reduce structural noise based on the structural characteristics of various types of special vehicles.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle noise control, and in particular to a low-vibration high-frequency modal vehicle body structure. Background Art

[0002] Special vehicles refer to vehicles that exceed the design vehicle limits in terms of external dimensions and weight and are used for special purposes. Or they refer to motor vehicles that are specially made or specially modified, equipped with fixed devices and equipment, and whose main function is not to carry people or goods. They refer to vehicles that are responsible for special duties and hang special vehicle license plates, and are equipped with sirens and sign lights. Such as money transporters, ambulances, fire trucks, police cars, engineering rescue vehicles, military supervision vehicles, etc. They refer to various wheeled or tracked special vehicles used for towing, obstacle removal, cleaning, lifting, loading and unloading, lifting, mixing, excavating, bulldozing, rolling, etc., or vehicles equipped with fixed special instruments and equipment in the vehicle for professional work such as monitoring, fire fighting, cleaning, medical treatment, television broadcasting, radar, X-ray inspection, etc.

[0003] At present, most special vehicle cabs have different degrees of poor noise environment problems, or abnormal noise occurs at a certain speed, or the average noise is too large under most working conditions. There are many reasons for this situation. For special vehicles, there are many axles and suspensions, and the vehicle modal matching problem is not considered in depth and detail; the cab system design is unreasonable, and the structural mode and acoustic cavity mode are prone to resonance and roar. From the perspective of cab noise control, special vehicles are a complex electromechanical system with many axles and complex vibration transmission paths, but they will eventually excite the body structure, thereby generating structural radiation noise (referred to as "structural noise"), which has a significant impact on the low-frequency noise in the cab. Effective and accurate optimization design of the modes and vibration shapes of the body structure and vibration reduction and noise reduction measures are the fundamental way to solve structural noise.

[0004] In terms of research progress, most of the research objects in the field of noise in China are passenger cars, while there are few studies on the NVH performance of special vehicles. The vibration and noise levels of relevant domestic vehicles are still far from the requirements, which has become a limiting factor restricting the development of the body structure of special vehicles. In addition, in a noisy environment, the occupants will be nervous, easily fatigued, irritable and inattentive. Long-term exposure to a noisy environment is more likely to cause adverse reactions such as dizziness, mental distraction, nausea, and even cardiovascular and cerebrovascular diseases. Special vehicles are mostly driven on terrain with poor road conditions or no roads, and may encounter many types of excitations. The vibration and noise in the cab are relatively serious. The noise in special vehicles during combat has a fatal impact on soldiers. Therefore, conducting research on NVH-related technologies in the cab of special vehicles is of great significance in terms of economic value and national interests. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a low-vibration high-frequency modal body structure that can effectively adjust the local modal frequency and vibration type of the body structure, effectively control the structural noise of special vehicles, and has high reliability.

[0006] The object of the present invention can be achieved through the following technical solutions: a low-vibration high-frequency modal vehicle body structure, including a vehicle body base plate, modal adjustment ribs, and a composite damping layer, wherein the modal adjustment ribs are arranged on the vehicle body base plate according to the modal adjustment stiffness and position, and are rigidly connected to the vehicle body base plate; the composite damping layer is composed of a sound absorbing layer, a constraint layer, a damping layer, and a bonding layer from the outside to the inside, wherein the bonding layer is bonded to the vehicle body base plate.

[0007] Furthermore, the arrangement of the modal adjustment ribs is included at the position of the modal response corresponding to the peak of the adjustment mode of the original vehicle body base plate, and the ratio of the additional stiffness of the modal adjustment ribs to the accessory mass is greater than 1.

[0008] Furthermore, the arrangement of the modal adjustment ribs forms a new high-order mode, the new high-order modal frequency is higher than the modal frequency of the corresponding order mode of the original vehicle body substrate, and the corresponding modal response amplitude is smaller than the response amplitude of the corresponding order mode of the original vehicle body substrate.

[0009] Furthermore, the lower end surface of the modal adjustment rib is located on the same horizontal plane as the surface of the vehicle body base plate.

[0010] Furthermore, the upper end surface of the modal adjustment rib protrudes from the surface of the vehicle body base plate and may not be on the same horizontal plane.

[0011] Furthermore, a plurality of modal adjustment ribs are arranged on the vehicle body base plate, and the cross-section of the modal adjustment ribs is "T"-shaped, "┏"-shaped, "┏┓"-shaped, "Π"-shaped, "I"-shaped or "O"-shaped, and the modal adjustment ribs with one or more cross-sectional shapes are combined into a high bending modulus.

[0012] Furthermore, the layout of the multiple modal adjustment ribs is one or more of an I-shape, a jing-shape, a M-shape, a diamond-shape, a triangle or a mesh.

[0013] Furthermore, the damping layer of the composite damping layer is a viscoelastic material or a polymer damping material having a modulus lower than that of the vehicle body substrate, and the damping material is a non-metallic damping material or a metal damping material having a damping loss factor greater than 0.3 within the adjustment frequency band and use environment.

[0014] Furthermore, the constraint layer of the composite damping layer is made of a metal or non-metal material having a modulus equivalent to or higher than that of the vehicle body substrate plate and the damping layer.

[0015] Furthermore, the average sound absorption coefficient of the sound absorbing material of the sound absorbing layer of the composite damping layer is above 0.3.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention is a noise reduction structure for the body of a special vehicle with a high-power engine. This body structure is mainly composed of a body base plate, a modal adjustment rib, and a composite damping layer. The modal adjustment rib is arranged according to the modal adjustment stiffness and position and is rigidly connected to the body base plate. The composite damping layer adopts a multi-layer constrained damping structure or a damping coating structure and is attached to the body base plate according to the modal distribution. It can be used in typical positions of vehicles, and fully considers the structural vibration of the vehicle and the structural noise characteristics caused by vibration and the effectiveness of damping vibration reduction and noise reduction control frequency. Based on the body structure characteristics of various types of special vehicles, it can effectively improve the body structure stiffness, increase the modal frequency, avoid the generation of structural resonance, and suppress the radiation of low-frequency structural noise. At the same time, damping treatment is used to give full play to the medium and high frequency characteristics of the damping structure and the sound-absorbing material, so as to achieve the purpose of reducing the wide-band structural noise of the vehicle.

[0018] 2. Compared with the traditional special vehicle body structure, the present invention is a composite structure, which is a composite of metal or non-metal materials with different characteristics. The stiffness is adjustable, the modal frequency is significantly improved, the noise reduction band is wider, and the characteristics of simple structure and strong design are retained. It is suitable for use in various types of special vehicles.

[0019] 3. The low-vibration and high-frequency vehicle body structure proposed in the present invention can effectively overcome the defects existing in the prior art, is easy to implement, has strong adaptability, high reliability, and is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A side view schematic diagram of the overall structure of the present invention;

[0021] Figure 2 A schematic diagram of the structure of the composite damping layer in the structure of the present invention;

[0022] Figure 3 Numerical simulation results of the original vehicle body structure mode in the embodiment;

[0023] Figure 4 A schematic top view of the structure of a novel embodiment 1 of the present invention;

[0024] Figure 5 Numerical simulation results of the vehicle body structure mode in Example 1;

[0025] Figure 6 A schematic top view of the structure of a novel embodiment 2 of the present invention;

[0026] Figure 7Numerical simulation results of the vehicle body structure mode in Example 2;

[0027] Figure 8 A schematic top view of the structure of a novel embodiment 3 of the present invention;

[0028] Fig. 9 Numerical simulation results of vehicle body structure modes in Example 3;

[0029] Fig.10 Schematic diagram of the locations of excitation points and response points for frequency response calculation of vehicle structure;

[0030] Fig.11 (a) Simulation calculation results of the frequency response characteristics of the original vehicle body structure in the embodiment;

[0031] Fig.11 (b) The simulation calculation results of the vehicle body structure frequency response characteristics in Example 1;

[0032] Fig.11 (c) Simulation calculation results of the vehicle body structure frequency response characteristics in Example 2;

[0033] Fig.11 (d) Simulation calculation results of the vehicle body structure frequency response characteristics in Example 3.

[0034] Numbers in the figure: 1. vehicle body base plate, 2. modal adjustment ribs, 3. composite damping layer, 4. sound absorption layer, 5. constraint layer, 6. damping layer, 7. bonding layer, 8. modal adjustment module A, 9. modal adjustment module B, 10. modal adjustment module C, 11. modal adjustment module D. DETAILED DESCRIPTION

[0035] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0036] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] like Figure 1As shown, a low-vibration high-frequency modal vehicle body structure includes a vehicle body base plate 1, a modal adjustment rib 2, and a composite damping layer 3. The modal adjustment rib 2 is arranged according to the modal adjustment stiffness and position and is rigidly connected to the vehicle body base plate 1. The lower end surface of the modal adjustment rib 2 and the upper end surface of the vehicle body structure 1 are located on the same horizontal plane. The upper end surface of the modal adjustment rib 2 is protruding from the vehicle body structure 1. The arrangement of the modal adjustment rib 2 is included in the position of the modal response corresponding to the modal response peak of the original vehicle body base plate 1, and the ratio of the additional stiffness of the modal adjustment rib 2 to the accessory mass is greater than 1. The arrangement of the modal adjustment rib 2 forms a new high-order mode, the new high-order modal frequency is higher than the modal frequency of the corresponding order mode of the original vehicle body base plate 1, and the corresponding modal response amplitude is smaller than the response amplitude of the corresponding order mode of the original vehicle body base plate 1.

[0038] like Figure 2 As shown, the composite damping layer 3 is composed of a sound absorbing layer 4, a constraint layer 5, a damping layer 6, and a bonding layer 7 from outside to inside, wherein the bonding layer 7 is bonded to the vehicle body substrate 1. The damping layer 6 is a viscoelastic material or a polymer damping material with a modulus lower than that of the vehicle body substrate 1. The damping material is a non-metallic damping material or a metal damping material with a damping loss factor greater than 0.3 in the adjustment frequency band and the use environment. The constraint layer 5 is made of a metal or non-metallic material with a modulus equivalent to or higher than that of the vehicle body substrate 1. The average sound absorption coefficient of the sound absorbing material of the sound absorbing layer 4 is above 0.3.

[0039] like Figure 3 As shown, the modal frequency and modal vibration shape of the original vehicle body structure 1 under the fixed boundary condition (the displacement in the three directions of X, Y and Z is 0) are numerically simulated and calculated. The calculation results of the modal frequency within 500 Hz are shown in Table 1. The first-order modal frequency of the original vehicle body structure 1 is 22.7 Hz, and the fifth-order modal frequency is 99.9 Hz, wherein a is the first-order modal vibration shape of the original vehicle body structure 1, and b is the fifth-order modal vibration shape of the original vehicle body structure 1. The implementation effect of the present invention on the structural mode and structural response is now described in detail through the following embodiments.

[0040] Table 1 shows the calculation results of the modal frequencies of the original vehicle body structure.

[0041] Table 1

[0042] Order Frequency / Hz Order Frequency / Hz Order Frequency / Hz Order Frequency / Hz 1 22.7 11 185.1 21 322.1 31 466.0 2 38.3 12 198.2 22 339.0 32 477.8 3 63.9 13 199.8 23 347.2 33 482.5 4 76.1 14 216.8 24 347.5 34 497.1 5 99.9 15 245.8 25 384.5 6 100.0 16 260.1 26 399.5 7 120.1 17 264.7 27 406.8 8 144.5 18 286.3 28 423.8 9 155.1 19 294.1 29 433.4 10 164.7 20 311.7 30 448.6

[0043] Embodiment 1:

[0044] like Figure 4As shown, the number of the modal adjustment ribs 2 is several, and several of the modal adjustment ribs can be stacked or laid flat together to form a modal adjustment module A8 and a modal adjustment module B9. The modal adjustment module A8 and the modal adjustment module B9 are welded to an integrated structure with the vehicle body base plate 1. The modal adjustment module A8 and the modal adjustment module B9 are made of steel. The layout of the modal adjustment module A8 and the modal adjustment module B9 is in a "well" shape. The cross-sectional configuration of the modal adjustment module A8 and the modal adjustment module B9 is "T"-shaped. The modal adjustment module A8 and the modal adjustment module B9 are designed based on the modal adjustment stiffness and the modal peak position. The composite damping layer 3 is composed of a sound absorbing layer 4 composed of a porous sound absorbing material, a constraint layer 5 and a damping layer 6 composed of an inorganic polymer material, and a bonding layer 7 composed of an epoxy adhesive from the outside to the inside.

[0045] As shown in Table 2 and Figure 5 As shown, the modal frequency of the original car body structure of 22.7 Hz can be increased to 70.6 Hz, and the modal frequency of the original car body structure of 99.9 Hz can be increased to 153.0 Hz. Where a is the first-order modal vibration shape of the car body structure 1 of Example 1, and b is the fifth-order modal vibration shape of the car body structure 1 of Example 1.

[0046] Table 2 is the calculation results of the modal frequency of the vehicle body structure in Example 1

[0047] Table 2

[0048]

[0049]

[0050] Embodiment 2:

[0051] like Figure 6 As shown, the number of the modal adjustment ribs is several, and several of the modal adjustment ribs can be stacked or laid flat together to form a modal adjustment module A8 and a modal adjustment module C10. The modal adjustment module A8 and the modal adjustment module C10 are welded to an integrated structure with the vehicle body structure. The modal adjustment module A8 and the modal adjustment module B9 are made of steel. The layout of the modal adjustment module A8 is formed in a "well" shape, and the layout of the modal adjustment module C10 is formed in a "well" shape and a diamond shape. The cross-sectional configuration of the modal adjustment module A8 and the modal adjustment module C10 is a "T" shape. The modal adjustment module A8 and the modal adjustment module C10 are designed based on the modal adjustment stiffness and the modal peak position. The composite damping layer 3 is composed of a sound absorbing layer 4 composed of a porous sound absorbing material, a constraint layer 5 and a damping layer 6 composed of an inorganic polymer material, and a bonding layer 7 composed of an epoxy adhesive from the outside to the inside.

[0052] As shown in Table 3 and Figure 7 As shown, the modal frequency of the original body structure of 22.7 Hz can be increased to 110.5 Hz, and the modal frequency of the original body structure of 99.9 Hz can be increased to 211.6 Hz. Where a is the first-order modal vibration shape of the body structure 1 of Example 2, and b is the fifth-order modal vibration shape of the body structure 1 of Example 2.

[0053] Table 3 is the calculation results of the modal frequencies of the vehicle body structure in Example 2.

[0054] Table 3

[0055] Order Frequency / Hz Order Frequency / Hz 1 110.5 11 339.8 2 116.6 12 368.3 3 137.2 13 397.5 4 168.5 14 417.4 5 211.6 15 422.2 6 239.1 16 484.7 7 259.6 17 495.3 8 289.2 9 305.6 10 311.8

[0056] Embodiment 3:

[0057] like Figure 8 As shown, the number of the modal adjustment ribs is several, and several of the modal adjustment ribs can be stacked or laid flat together to form a modal adjustment module A8 and a modal adjustment module D11. The modal adjustment module A8 and the modal adjustment module D11 are welded with the vehicle body structure into an integrated structure. The modal adjustment module A8 and the modal adjustment module B9 are made of steel. The layout of the modal adjustment module A8 is in the shape of a "well", and the layout of the modal adjustment module D11 is in the shape of a "well" and a "rice". The cross-sectional configuration of the modal adjustment module A8 and the modal adjustment module D11 is "T"-shaped. The modal adjustment module A8 and the modal adjustment module D11 are designed based on the modal adjustment stiffness and the modal peak position. The composite damping layer 3 is composed of a sound absorbing layer 4 made of porous sound absorbing material, a constraining layer 5 and a damping layer 6 made of inorganic polymer material, and a bonding layer 7 made of epoxy adhesive in sequence from outside to inside.

[0058] As shown in Table 4 and Fig. 9 As shown, the modal frequency of the original body structure of 22.7 Hz can be increased to 136.5 Hz, and the modal frequency of the original body structure of 99.9 Hz can be increased to 260.1 Hz. Where a is the first-order modal vibration shape of the body structure 1 of Example 3, and b is the fifth-order modal vibration shape of the body structure 1 of Example 3.

[0059] Table 4 is the calculation results of the modal frequencies of the vehicle body structure in Example 3.

[0060] Table 4

[0061] Order Frequency / Hz Order Frequency / Hz 1 136.5 11 385.9 2 192.3 12 414.5 3 213.9 13 427.6 4 243.4 14 489.9 5 260.1 6 289.7 7 310.6 8 317.5 9 351.1 10 381.2

[0062] like Figures 10-11 As shown in the figure, it simulates the actual vehicle body structure excitation position. Fig.10A force of 1N perpendicular to the plate surface is applied at the four excitation positions, and the original vehicle body structure, the vehicle body structure of Example 1, the vehicle body structure of Example 2, and the vehicle body structure of Example 3 under the fixed boundary condition (the displacement in the three directions of X, Y, and Z is 0) are calculated. Fig.10 The frequency response characteristics of the response point in the middle. Fig.11 (a) Simulation calculation results of the frequency response characteristics of the original vehicle body structure in the embodiment; Fig.11 (b) The simulation calculation results of the vehicle body structure frequency response characteristics in Example 1; Fig.11 (c) Simulation calculation results of the vehicle body structure frequency response characteristics in Example 2; Fig.11 (d) Simulation calculation results of the vehicle body structure frequency response characteristics in Example 3. It can be seen that the maximum vibration response peak of the original vehicle body structure 1 is as high as 150dB, the maximum vibration peak in implementation case 1 can be reduced to 135dB, and the vibration can be reduced by 15dB; the maximum vibration peak in implementation case 1 can be reduced to 132dB, and the vibration can be reduced by 18dB; the maximum vibration peak in implementation case 1 can be reduced to 128dB, and the vibration can be reduced by 22dB.

[0063] The above description is only an explanation of the preferred embodiments of the present application and the technical principles and other schemes used. At the same time, the scope of the invention involved in the present application is not limited to the technical scheme formed by a specific combination of the above technical features, but also should cover other technical schemes formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) by each other to form a technical scheme.

Claims

1. A low-vibration high-frequency modal vehicle body structure, characterized in that: It includes a vehicle body base plate (1), modal adjustment ribs (2), and a composite damping layer (3). The modal adjustment ribs (2) are arranged on the vehicle body base plate (1) according to the modal adjustment stiffness and position and are rigidly connected to the vehicle body base plate (1). The composite damping layer (3) is composed of a sound absorption layer (4), a constraint layer (5), a damping layer (6), and an adhesive layer (7) from outside to inside. The adhesive layer (7) is bonded to the surfaces of the vehicle body base plate (1) and the modal adjustment ribs (2). The arrangement of the modal adjustment ribs (2) is at the positions corresponding to the peaks of the modal responses for adjusting the modes of the original vehicle body base plate (1), and the ratio of the additional stiffness to the additional mass of the modal adjustment ribs (2) is greater than 1. The arrangement of the modal adjustment ribs (2) forms a new high-order mode. The frequency of this new high-order mode is higher than the modal frequency of the corresponding order mode of the original vehicle body base plate (1), and the corresponding modal response amplitude is smaller than the response amplitude of the corresponding order mode of the original vehicle body base plate (1). A plurality of modal adjustment ribs (2) are arranged on the vehicle body base plate (1). The cross-section of the modal adjustment ribs (2) is in the shape of "T", "┏", "┏┓", "Π", "工", or "口". The modal adjustment ribs (2) with one or more cross-sectional shapes are combined to form a high bending modulus. The damping layer (6) of the composite damping layer (3) is a viscoelastic material or a polymer damping material with a modulus lower than that of the vehicle body base plate (1). This damping material is a non-metallic damping material or a metallic damping material with a damping loss factor greater than 0.3 in the adjustment frequency band range and the use environment. The constraint layer (5) of the composite damping layer (3) is made of a metal or non-metal material with a modulus equivalent to or higher than that of the vehicle body base plate (1) and higher than that of the damping layer (6).

2. A low-vibration high-frequency modal vehicle body structure according to claim 1, characterized in that: The lower end surface of the modal adjustment ribs (2) is on the same horizontal plane as the upper end surface of the vehicle body base plate (1).

3. A low-vibration high-frequency modal vehicle body structure according to claim 1, characterized in that: The upper end surface of the modal adjustment ribs (2) protrudes from the surface of the vehicle body base plate (1) and may not be on the same horizontal plane.

4. A low-vibration high-frequency modal vehicle body structure according to claim 1, characterized in that: The layout of a plurality of modal adjustment ribs (2) is one or more of the shapes of "工", "井", "米", diamond, triangle, or mesh.

5. A low-vibration high-frequency modal vehicle body structure according to claim 1, characterized in that: The average sound absorption coefficient of the sound absorption material of the sound absorption layer (4) of the composite damping layer (3) is above 0.3.

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