Metamaterial bolt connection structure capable of transmitting static state and restraining motion

Abstract

The invention discloses a metamaterial bolt connection structure capable of transmitting static and restraining motion, and relates to the technical field of vibration reduction of bolt connection structures of aero-engines and fuselages. The bolt connection structure comprises two local resonance type metamaterial plates, bolts and nuts. The local resonance type metamaterial plate is formed by integrating a spiral resonance system into a variable-wall-thickness multi-stage honeycomb structure, the spiral resonance system is periodically distributed, and a bolt hole is formed in the spiral resonance system and used for installing a bolt and a nut. According to the spiral resonance system, spiral elastic beams are cut on the upper face and the lower face of a plate, a cylindrical vibrator is vertically installed between the spiral elastic beams, and a local resonance type metamaterial is formed. According to the invention, a plate of a bolt connection structure is designed into a variable-wall-thickness multi-stage honeycomb structure, so that the plate has stronger compressive mechanical property and higher energy absorption rate, and transmission of static load is completed; a spiral resonance system is periodically embedded in a plate of a bolt connection structure, the vibration reduction frequency band is flexible and adjustable, efficient elastic wave control is achieved, and dynamic load suppression is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration reduction of bolted connection structures between aircraft engines and fuselages, and more specifically to a metamaterial bolted connection structure that "transmits static and suppresses vibration". Background Art

[0002] The connection structure is an indispensable component in the mechanical system. Since the flight profile of an aircraft spans a wide speed range and a large airspace, it will experience complex mechanical environments such as strong thrust, high lift, vibration, and impact. The bolted connection structure between the aircraft engine and the aircraft is the weak link in the mechanical performance of the aircraft. It carries the transmission of static and dynamic loads, participates in the vibration of the whole machine, and is the key path for energy flow. Taking the typical whole machine vibration of a certain type of aircraft engine as an example, the low-voltage fundamental frequency and high-voltage fundamental frequency are approximately 95Hz and 179Hz, respectively. How to make the connection structure suppress the transmission of dangerous vibrations of the aircraft engine at the fundamental frequency to the aircraft is of great significance to improving the service life of aircraft and reducing cabin noise.

[0003] In the Chinese invention patents with publication numbers CN 112382461 A and CN 113775064 B, rubber pads are used in bolt connection structures to achieve vibration reduction and noise reduction. In the Chinese invention patents with publication numbers CN 113775231 B and CN 117432078A, a vibration reduction assembly designed with springs and rubber is used to achieve vibration attenuation. In the US invention patent with publication number US10,274,037B2, rubber parts are also used to dissipate vibration energy to achieve the vibration reduction effect of the connection structure. However, the use of elastic bodies such as rubber or springs has a low vibration attenuation effect, only dissipating a part of the energy, and cannot achieve a large degree of vibration attenuation.

[0004] In order to meet the strict requirements of vibration control in the aerospace field, it is urgent to design a new type of connection structure to achieve efficient control of dangerous vibrations of aircraft engines in the fundamental frequency range without destroying the integrity of the connection structure and without conflicting with the strength and stiffness requirements of the connection structure itself. Summary of the invention

[0005] In order to solve the problem of dangerous vibration of aircraft engines at fundamental frequency being transmitted to the aircraft, the present invention integrates the elastic wave manipulation capability of the spiral resonance system into the lightweight and high-strength mechanical properties of the variable-wall-thickness multi-stage honeycomb structure, and designs a "static transmission and vibration suppression" metamaterial bolt connection structure.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a "static transmission and motion suppression" metamaterial bolt connection structure, comprising an upper plate and a lower plate of a local resonance type metamaterial, wherein the plates are provided with bolt holes, and the upper plate and the lower plate of the local resonance type metamaterial can be overlapped and fixed by bolts and nuts.

[0007] Preferably, the upper plate and the lower plate of the local resonance type metamaterial have the same structure, and both integrate the spiral resonance system into the variable wall thickness multi-level honeycomb structure. The spiral resonance system realizes efficient elastic wave manipulation capability through the resonance of the local oscillator, and the variable wall thickness multi-level honeycomb structure has light weight and high strength mechanical properties through gradient design and multi-level design.

[0008] Preferably, the spiral resonant system is periodically embedded in the upper and lower plates of the connecting structure, and the spiral resonant system is mainly composed of two upper and lower spiral elastic beams and a cylindrical vibrator in the middle; the spiral elastic beam is cut by two Archimedean spirals, and the cylindrical vibrator and the spiral elastic beam are connected by welding.

[0009] Preferably, the variable wall thickness multi-level honeycomb structure includes inner circular holes and outer rounded corners, so that the honeycomb structure has variable wall thickness and multi-level characteristics, and has stronger compressive mechanical properties and higher energy absorption rate compared to conventional honeycomb structures.

[0010] Preferably, the helical resonant system can change the equivalent stiffness K of the system by adjusting the height, width and helical angle of the helical elastic beam, or change the equivalent mass M of the system by adjusting the diameter, height and material of the cylindrical vibrator. According to the resonant frequency f=1 / 2πK / M of the resonant system, 1 / 2 , thereby realizing the flexible and adjustable vibration reduction frequency band of the bolted connection structure, which can be expanded to the vibration control of other precision equipment.

[0011] Preferably, the material density of the cylindrical vibrator generally needs to be greater than the material density of the helical elastic beam; if the material of the helical elastic beam is structural steel, the material of the cylindrical vibrator can preferably be designed to be lead; a larger vibrator material density can obtain a relatively higher equivalent mass and achieve a low-frequency vibration reduction band.

[0012] Preferably, according to the VDI 2230 standard, the flexibility of the bolt is much greater than the flexibility of the lower plate and the upper plate of the local resonance metamaterial, that is, the lattice constant a and the height h of the spiral resonance system must satisfy: a>dw+h; wherein dw represents the supporting surface diameter of the bolt.

[0013] Preferably, the “transmitting static load” means that the bolt connection structure can transmit static load in the vertical direction; and the “suppressing dynamic load” means that the bolt connection structure can suppress dynamic load in the horizontal direction.

[0014] Preferably, the spiral resonance system is embedded in a variable wall thickness multi-stage honeycomb structure, which is more compact than an external resonance system; and lighter than a solid connection structure, and can be better applied in the aerospace field.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention periodically embeds the spiral resonant system into the plate of the connection structure without destroying the integrity of the connection structure, and the first-order mode of the spiral elastic beam is a bending mode, which can suppress the transmission of bending waves in the connection structure at low frequencies.

[0017] 2. The main body of the present invention uses a variable wall thickness multi-stage honeycomb configuration, which can achieve lightweight while meeting the strength and stiffness requirements of the bolt connection structure in the aircraft engine.

[0018] 3. The present invention can easily achieve low-frequency adjustable band gap by changing the geometric parameters and material parameters of the spiral elastic beam or the vibrator, and expand to the vibration control needs of other precision equipment.

[0019] 4. The present invention is a multifunctional combination of metamaterials and honeycomb structures. Compared with the use of elastic elements for vibration reduction in disclosed patents, the bolt connection structure of the present invention has a more significant vibration reduction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Axial view of the overall structure provided by the present invention;

[0021] Figure 2 A top view of the overall structure provided by the present invention;

[0022] Figure 3 The side sectional view of the overall structure provided by the present invention

[0023] Figure 4 for Figure 3 Schematic diagram of the enlarged structure at B in FIG.

[0024] Figure 5 It is a schematic diagram of the spiral resonance system of the present invention;

[0025] Figure 6 A schematic diagram of a variable wall thickness multi-stage honeycomb structure of the present invention;

[0026] Figure 7 It is a time history response curve diagram of the present invention when the excitation frequency is 95Hz;

[0027] In the figure: 1. Local resonance metamaterial lower plate; 2. Local resonance metamaterial upper plate; 3. Bolts; 4. Nuts; 5. Cylindrical vibrator; 6. Spiral resonance system; 7. Variable wall thickness multi-level honeycomb structure; 11. Spiral elastic beam; 12. Inner circular hole; 13. Outer round corner; 14. Bolt hole. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figure 1 , 2 As shown in Figure 3, a metamaterial bolt connection structure for "transmitting static and suppressing motion" includes a local resonance metamaterial lower plate 1, a local resonance metamaterial upper plate 2, bolts 3 and nuts 4; the local resonance metamaterial lower plate 1 and the local resonance metamaterial upper plate 2 have the same structure, both of which integrate the spiral resonance system 6 into the variable wall thickness multi-level honeycomb structure 7, and are provided with bolt holes 14, and the local resonance metamaterial lower plate 1 and the local resonance metamaterial upper plate 2 are overlapped by bolts 3 and nuts 4. The spiral resonance system 6 is distributed periodically, including two upper and lower spiral elastic beams 11 and a cylindrical vibrator 5; wherein the spiral elastic beam 11 is cut by two Archimedean spirals, and the cylindrical vibrator 5 and the spiral elastic beam 11 are connected by welding.

[0030] like Figure 4 , 5 As shown in 6, the variable wall thickness multi-level honeycomb structure 7 includes an inner circular hole 12 and an outer rounded corner 13, so that the honeycomb structure has the characteristics of variable wall thickness and multi-level; the spiral resonant system 6 can change the equivalent stiffness of the system by adjusting the height, width and spiral angle of the spiral elastic beam 11, or change the equivalent mass of the system by adjusting the diameter, height and material of the cylindrical vibrator 5, thereby realizing the characteristics of flexible and adjustable vibration reduction frequency band of the bolt connection structure; the material density of the cylindrical vibrator 5 generally needs to be greater than the material density of the spiral elastic beam 6 to obtain a relatively high equivalent mass and a low-frequency vibration reduction frequency band. According to the VDI 2230 standard, the flexibility of the bolt 3 is much greater than the flexibility of the local resonance type metamaterial lower plate 1 and the local resonance type metamaterial upper plate 2, that is, the lattice constant a and height h of the spiral resonant system 6 need to satisfy: a>d w +h; where d w Indicates the bearing surface diameter of the bolt.

[0031] Embodiment 1:

[0032] In view of the low-pressure fundamental frequency of a typical whole-machine vibration of a certain type of aircraft engine, which is about 95Hz, the dimensional parameters and material parameters of the "static transmission and vibration suppression" metamaterial bolt connection structure are designed.

[0033] The material of the local resonance type metamaterial lower plate 1, the local resonance type metamaterial upper plate 2, the bolts 3 and the nuts 4 is preferably structural steel, and its density is 7850kg / m 3 , Young's modulus is 210GPa, Poisson's ratio is 0.3; the material of the cylindrical vibrator 5 is lead, and its density is 11340kg / m 3 , Young's modulus is 17GPa, and Poisson's ratio is 0.42. The height of the cylindrical vibrator 5 is 20mm, and the radius is 7.5mm; the height of the spiral resonant system 6 is 23mm, and the lattice constant is 50mm; the height of the spiral elastic beam 11 is 1.5mm, the width is 3.5mm, and the spiral angle is 2.25π; the thickness of the variable wall thickness multi-level honeycomb structure 7 is 1.5mm, the radius of the inner circular hole 12 is 4mm, and the radius of the outer round corner is 10mm.

[0034] like Figure 1 , 7 As shown in the figure, a metamaterial bolt connection structure that "transmits static and suppresses vibration" is applied with a point excitation harmonic load at a position 20mm away from the edge of the local resonance metamaterial lower plate 1, and the response load is recorded at a position 20mm away from the edge of the local resonance metamaterial upper plate 2. When the excitation frequency is 95Hz, the acceleration response amplitude of the output signal is significantly smaller than the input signal, and the vibration reduction effect reaches 83%.

[0035] The following is an explanation of the mechanism and advantages of the metamaterial bolt connection structure of "transmitting static and inhibiting motion" proposed by the present invention. The cylindrical vibrator 5 is fixed between the upper and lower spiral elastic beams 11, which is equivalent to a single-degree-of-freedom spring-mass system; when the bolt connection structure is subjected to external excitation, if the excitation frequency is close to the natural frequency of the single-degree-of-freedom system, the single-degree-of-freedom system will produce anti-phase vibration with the bolt connection structure; this anti-phase motion will generate a force opposite to the vibration direction of the bolt connection structure, thereby offsetting part of the vibration energy of the external excitation acting on the bolt connection structure and reducing the amplitude of the bolt connection structure. The metamaterial bolt connection structure of "transmitting static and inhibiting motion" periodically embeds the spiral resonant system 6 into the plate of the connection structure without destroying the integrity of the connection structure; the main body of the bolt connection structure uses a variable wall thickness multi-stage honeycomb configuration, which can achieve lightweight while meeting the strength and stiffness requirements of the connection structure in the aeroengine. By changing the geometric parameters and material parameters of the spiral elastic beam 11 or the cylindrical vibrator 5, it is easy to achieve low-frequency adjustable band gap and expand to the vibration control needs of other precision equipment. The present invention is a multifunctional combination of metamaterials and honeycomb structures. Compared with the use of elastic elements for vibration reduction in disclosed patents, the bolt connection structure of the present invention has a more significant vibration reduction effect, a more compact space than an external resonance system, and a lighter weight than a physical connection structure.

[0036] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any reference numerals in the claims should not be regarded as limiting the claims involved.

Claims

1. A "static transmission and motion suppression" metamaterial bolt connection structure, comprising a local resonance type metamaterial lower plate (1), a local resonance type metamaterial upper plate (2), bolts (3) and nuts (4); characterized in that: The local resonance type metamaterial lower plate (1) and the local resonance type metamaterial upper plate (2) are provided with bolt holes (14), and the local resonance type metamaterial lower plate (1) and the local resonance type metamaterial upper plate (2) are overlapped by bolts (3) and nuts (4) through the bolt holes (14).

2. According to claim 1, a metamaterial bolt connection structure of "transmitting static and suppressing motion" is characterized in that: The local resonance metamaterial lower plate (1) and the local resonance metamaterial upper plate (2) have the same structure, both of which integrate the spiral resonance system (6) into the variable wall thickness multi-level honeycomb structure (7); the spiral resonance system (6) has a highly efficient elastic wave manipulation capability, and the variable wall thickness multi-level honeycomb structure (7) has light weight and high strength mechanical properties.

3. According to claim 2, a metamaterial bolt connection structure of "transmitting static and suppressing motion" is characterized in that: The spiral resonant system (6) is periodically distributed and comprises two upper and lower spiral elastic beams (11) and a cylindrical vibrator (5); wherein the spiral elastic beam (11) is cut from two Archimedean spirals, and the cylindrical vibrator (5) and the spiral elastic beam (11) are connected by welding.

4. According to claim 2, a metamaterial bolt connection structure of "transmitting static and suppressing motion" is characterized in that: The variable wall thickness multi-level honeycomb structure (7) comprises an inner circular hole (12) and an outer rounded corner (13), so that the honeycomb structure has the characteristics of variable wall thickness and multi-level.

5. According to claim 2, a metamaterial bolt connection structure of "transmitting static and suppressing motion" is characterized in that: The spiral resonant system (6) changes the equivalent stiffness of the system by adjusting the height, width and spiral angle of the spiral elastic beam (11), or changes the equivalent mass of the system by adjusting the diameter, height and material of the cylindrical vibrator (5), thereby achieving the characteristic of flexible and adjustable vibration reduction frequency band of the bolt connection structure.

6. The "static transmission and motion suppression" metamaterial bolt connection structure according to claim 5 is characterized in that: The material density of the cylindrical vibrator (5) is greater than the material density of the spiral elastic beam (6), thereby obtaining a relatively high equivalent mass and achieving a low-frequency vibration reduction band.

7. The "static transmission and motion suppression" metamaterial bolt connection structure according to claim 1 is characterized in that: According to the VDI 2230 standard, the flexibility of the bolt (3) is greater than the flexibility of the local resonance type metamaterial lower plate (1) and the local resonance type metamaterial upper plate (2), that is, the lattice constant a and the height h of the spiral resonance system (6) must satisfy: a>dw+h; wherein dw represents the supporting surface diameter of the bolt.

8. The "static transmission and motion suppression" metamaterial bolt connection structure according to claim 1 is characterized in that: The "transmission of static" is in the vertical direction, and the "suppression of motion" is in the horizontal direction.

9. The "static transmission and motion suppression" metamaterial bolt connection structure according to claim 1 is characterized in that: The spiral resonant system (6) is embedded in a variable wall thickness multi-level honeycomb structure (7).

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