Aircraft pipeline double-layered clamp with nonlinear damping function

Abstract

This invention discloses a double-layer clamp for aircraft piping with nonlinear vibration reduction function. The device includes an inner clamp, an outer clamp, clamp gaskets, fastening bolts, and fastening nuts. A certain constraint gap exists between the inner and outer clamps. Both the inner and outer clamps are assembled to the aircraft body using fastening bolts and nuts. The inner clamp consists of an inner clamp metal band and an inner clamp bushing; the outer clamp also consists of an outer clamp metal band and an outer clamp bushing. Both the inner and outer clamp bushings are made of nitrile rubber-organic small molecule hybrid composite material, exhibiting excellent damping performance. This invention utilizes the outer clamp to provide nonlinear constraint stiffness and nonlinear constraint damping to achieve nonlinear vibration reduction, enabling wide-frequency vibration reduction and effectively improving the vibration reduction performance of traditional single-layer clamps. This device is easy to manufacture and install, employs a nonlinear passive vibration control strategy, and achieves high efficiency at low cost.

Description

Technical Field

[0001] This invention relates to the field of clamp design for aircraft pipelines, specifically a double-layer clamp for aircraft pipelines with nonlinear vibration reduction function. Background Technology

[0002] Aircraft piping systems play a crucial role in transmitting power and transporting media, much like the "blood vessels" of the human body, densely distributed throughout the aircraft. Clamps are essential components for constraining these piping systems, and their small size makes them suitable for installation in the space-constrained airframe. Traditional single-layer clamps for aircraft piping mainly consist of a metal band and a rubber bushing, primarily generating linear constraint stiffness and damping. By adjusting the constraint stiffness and position of traditional clamps, the natural frequency of the aircraft piping can be moved away from the excitation frequency, thus preventing resonance to some extent. However, aero-engines rotate at different speeds under varying operating conditions, resulting in broadband excitations on the piping. Furthermore, the natural frequency of the piping changes with variations in fluid velocity or pressure. Therefore, simply adjusting the constraint stiffness and position of traditional clamps is insufficient to completely prevent resonance. The alternating stress generated by piping resonance can cause fatigue damage and even system failure, seriously impacting flight safety. To address the above issues, nonlinear constraint stiffness and nonlinear constraint damping can be incorporated as an outer layer into traditional single-layer clamps, thereby improving the vibration reduction performance of traditional clamps.

[0003] Currently, although some researchers have made many beneficial attempts in the innovative design of clamps for aircraft air supply lines, some problems still need to be solved. For example, patent CN 204300557 U designed an integral damping clamp; however, the damping effect of this clamp needs to be achieved by installing an external damper, which is not suitable for installation in the space-constrained aircraft fuselage. Patent CN 111750200 B designed an intelligent clamp for aero-engines with vibration reduction and anti-loosening functions, using an active control method to achieve vibration reduction; however, its structure is very complex and requires energy input, which will inevitably increase the manufacturing and application costs of the clamp and increase the difficulty of mass production and practical engineering applications. Patent CN 113669543B invented a double clamp for aero-engines with vibration reduction and temperature resistance functions, using magnetorheological fluid and piezoelectric composite materials to achieve active and passive vibration reduction performance; however, its structure is still too complex and difficult to manufacture. Patent CN 115013597 B describes a high-damping clamp for aero-engines based on the co-curing and winding of fibers and metal wires, achieving high damping through composite materials. However, this patent does not address the nonlinear vibration reduction function of the clamp, and its clamp fabrication process is quite complex. Patent CN115680883 A invented a three-pipe clamp for aero-engines, reducing the assembly time for clamps with numerous pipes. However, this patent does not focus on the clamp's vibration reduction performance.

[0004] In summary, current patents related to the improved design of clamp structures still have certain technical limitations, making it difficult to achieve the nonlinear vibration reduction function of clamps, and the manufacturing cost is high and the assembly process is complex. Summary of the Invention

[0005] The purpose of this invention is to provide a low-cost, easy-to-manufacture, and nonlinear vibration-damping double-layer clamp for aircraft pipelines, which effectively broadens the vibration-damping frequency bandwidth of the clamp and improves the vibration-damping performance of traditional single-layer clamps.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A double-layer clamp for aircraft piping with nonlinear vibration reduction function includes: an inner clamp, an outer clamp, a clamp gasket, a fastening bolt, and a fastening nut. A certain constraint gap exists between the inner and outer clamps. Both the inner and outer clamps are assembled onto the aircraft fuselage using fastening bolts and fastening nuts. The inner clamp consists of an inner clamp metal band and an inner clamp bushing. The outer clamp consists of an outer clamp metal band and an outer clamp bushing.

[0008] The inner and outer clamp metal bands are both metal sheets bent into 3 / 4 arcs, extending in straight lines at both ends, with bolt holes at both ends that match the shape and size of the fastening bolts. The matching shape and size means that the fastening bolts and bolt holes can fit tightly together.

[0009] The inner clamp bushing is tightly nested on the inner clamp metal band, and its main body length is slightly less than the main body length of the inner clamp metal band.

[0010] The outer clamp bushing can fit tightly against the inner side of the outer clamp metal band, and its main body length is slightly smaller than the main body length of the outer metal band.

[0011] The inner and outer clamp bushings are made of nitrile rubber-organic small molecule hybrid composite material.

[0012] The clamp washer is a metal sheet with a certain thickness, and a bolt hole with a shape and size that matches the fastening bolt is left in the center. The shape and size matching means that the fastening bolt and the bolt hole can fit tightly together.

[0013] The width of the outer clamp is slightly smaller than the width of the inner clamp.

[0014] The gap between the inner and outer clamps enables the outer clamp to generate nonlinear constraint stiffness and nonlinear constraint damping, thereby realizing the nonlinear vibration reduction function of the clamp.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. Compared with traditional single-layer clamps, this invention utilizes the outer clamp to provide nonlinear constraint stiffness and nonlinear constraint damping to achieve nonlinear vibration reduction function. It can play a vibration reduction role in a wider excitation frequency range, effectively broadening the vibration reduction bandwidth of the clamp and improving the vibration reduction performance of the clamp.

[0017] 2. Compared with traditional single-layer clamps, the inner and outer clamp bushings of this invention are both made of nitrile rubber-organic small molecule hybrid composite material. The highly polar nitrile groups in nitrile rubber interact with the hydroxyl groups in the organic small molecules, resulting in a large number of intermolecular hydrogen bonds inside the hybrid composite material. When the pipeline vibrates, the intermolecular hydrogen bonds are continuously broken and regenerated under alternating stress, converting a large amount of mechanical energy into heat energy. This results in the hybrid composite material generating significant energy dissipation, exhibiting excellent damping performance, effectively increasing the damping of the clamp, and improving the clamp's vibration reduction capability.

[0018] 3. Compared with other new types of clamps, this invention only requires adding an outer clamp layer on the basis of the traditional single-layer clamp. Its manufacturing and installation are very simple, and high efficiency is achieved with low cost.

[0019] 4. This invention uses a nonlinear passive vibration control strategy, which is easy to maintain and durable.

[0020] 5. This invention occupies little space and has a defined movement space, eliminating the possibility of collision or interference with other devices on the aircraft, making it safe and reliable. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of a double-layer clamp for aircraft pipelines with nonlinear vibration reduction function according to the present invention.

[0022] Figure 2 This is a schematic diagram of the inner clamp structure of the present invention.

[0023] Figure 3 This is a schematic diagram of the outer clamp structure of the present invention.

[0024] Figure 4 This is a comparison graph of the amplitude-frequency response curves of embodiments and comparative examples of the present invention.

[0025] In the diagram: 1-Outer clamp; 2-Inner clamp; 3-First clamp washer; 4-Second clamp washer; 5-Fasting bolt; 6-Fasting nut; 1.1-Outer clamp metal band; 1.2-Outer clamp bushing; 1.3-Outer clamp bolt hole; 2.1-Inner clamp metal band; 2.2-Inner clamp bushing; 2.3-Inner clamp bolt hole. Detailed Implementation

[0026] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] like Figure 1 As shown, a double-layer clamp for aircraft piping with nonlinear vibration reduction function includes an outer clamp 1, an inner clamp 2, a first clamp gasket 3, a second clamp gasket 4, a fastening bolt 5, and a fastening nut 6; there is a certain gap between the outer clamp 1 and the inner clamp 2, which are separated by the first clamp gasket 3 and the second clamp gasket 4; both the outer clamp 1 and the inner clamp 2 are assembled to the aircraft fuselage by the fastening bolt 5 and the fastening nut 6.

[0028] like Figure 2 As shown, the outer clamp 1 consists of an outer clamp metal band 1.1 and an outer clamp bushing 1.2. The main body length of the outer clamp bushing 1.2 is less than the main body length of the outer clamp metal band 1.1. The outer clamp bushing 1.2 is tightly attached to the inner side of the metal band 1.1 by adhesive.

[0029] The outer clamp metal band 1.1 is a metal sheet bent into a 3 / 4 arc, extending along straight lines at both ends, with bolt holes 1.3 at both ends that match the shape and size of the fastening bolt 5. The matching shape and size means that the fastening bolt 5 and the bolt holes 1.3 can fit tightly together.

[0030] like Figure 3 As shown, the inner clamp 2 consists of an inner clamp metal band 2.1 and an inner clamp bushing 2.2. The inner clamp bushing 2.2 is tightly fitted onto the inner clamp metal band 2.1 by nesting, and the inner clamp bushing 2.2 is in direct contact with the aircraft piping.

[0031] The main body of the inner clamp metal band 2.1 is a metal sheet bent into a 3 / 4 arc, extending along a straight line at both ends, and bolt holes 2.3 that match the shape and size of the fastening bolt 5 are left at the extension points at both ends. The matching shape and size means that the fastening bolt 5 and the bolt holes 2.3 can fit tightly together.

[0032] Both the first clamp washer 3 and the second clamp washer 4 are metal sheets with a certain thickness, and a bolt hole with a shape and size that matches the fastening bolt 5 is left in the center of the clamp washer. The shape and size matching means that the fastening bolt 5 and the bolt hole of the clamp washer can fit tightly together.

[0033] The width of the outer clamp 1 is slightly smaller than the width of the inner clamp 2.

[0034] Both the outer clamp bushing 1.2 and the inner clamp bushing 2.2 are made of nitrile rubber-organic small molecule hybrid composite material, wherein the organic small molecules are hindered phenols, hindered amines and other organic small molecule substances with polar functional groups.

[0035] The gap reserved between the outer clamp 1 and the inner clamp 2 enables the outer clamp 1 to generate nonlinear constraint stiffness and nonlinear constraint damping, thereby realizing the nonlinear vibration reduction function of the double clamp.

[0036] The working process of this invention is as follows:

[0037] Because the inner clamp bushing 2.2 is in direct contact with the aircraft piping, the inner clamp 2 always exerts a constraint force on the piping. When the aircraft piping vibrates, under alternating stress, the intermolecular hydrogen bonds inside the inner clamp bushing 2.2 are continuously broken and regenerated, converting a large amount of mechanical energy into heat energy, thus causing significant energy dissipation from the clamp. When the vibration amplitude of the part of the piping constrained by the clamp is less than the constraint gap of the double clamps, the inner clamp 2 does not contact the outer clamp 1, and the outer clamp 1 does not exert a constraint force on the piping. When the vibration amplitude of the part of the piping constrained by the clamp exceeds the constraint gap of the double clamps, the inner clamp 2 will contact the outer clamp 1, and the outer clamp 1 will exert a constraint force on the piping. Therefore, the constraint effect of the outer clamp 1 on the piping is a nonlinear constraint effect that can be described by a piecewise function. The nonlinear constraint effect generated by the outer clamp 1 includes both nonlinear constraint stiffness and nonlinear constraint damping. The outer clamp 1 achieves the nonlinear vibration reduction function of the double clamp by generating a nonlinear constraint effect.

[0038] like Figure 4 As shown, the amplitude-frequency response curves of the embodiments and comparative examples of the present invention are shown. It can be seen that after adopting the new double-layer clamp constraint, compared with the traditional single-layer clamp constraint, the amplitude of the constrained part when the pipeline experiences different orders of principal resonance decreased by 61.8% and 76.8% respectively, indicating that the present invention can more effectively reduce the vibration of the pipeline in a wide frequency range.

[0039] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made based on the spirit and principle of the technical solution of the present invention shall be equivalent substitutions. As long as they meet the purpose of the invention and do not deviate from the technical principle and inventive concept of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A double-layer clamp for aircraft piping with nonlinear vibration reduction function, characterized in that, It includes an outer clamp, an inner clamp, a first clamp washer, a second clamp washer, a fastening bolt, and a fastening nut; The outer clamp consists of an outer clamp metal band and an outer clamp bushing. The main body of the outer clamp metal band is a metal sheet bent into a 3 / 4 arc, with both ends extending in a straight line, and bolt holes for the fastening bolts to extend at both ends. The outer clamp bushing is fitted to the inner side of the main body of the outer clamp metal band. The inner clamp consists of an inner clamp metal band and an inner clamp bushing. The main body of the inner clamp metal band is a metal sheet bent into a 3 / 4 arc, with both ends extending in a straight line, and bolt holes for the fastening bolts to extend at both ends. The inner clamp bushing is nested on the outside of the main body of the inner clamp metal band. The outer clamp is fitted over the inner clamp, and there is a certain gap between the outer clamp and the inner clamp. The two clamps are separated at their ends by the first clamp washer and the second clamp washer, and are connected to the aircraft body by fastening bolts and fastening nuts. The main body of the inner clamp bushing contacts the aircraft piping and exerts a restraining force on the aircraft piping. When the vibration amplitude of the part of the aircraft piping constrained by the clamp is greater than the gap between the outer clamp and the inner clamp, the inner clamp will contact the outer clamp, thereby causing the outer clamp to exert a restraining force on the aircraft piping.

2. The aircraft pipeline double-layer clamp with nonlinear vibration reduction function according to claim 1, characterized in that, There is a certain gap between the outer clamp and the inner clamp, which enables the outer clamp to generate nonlinear constraint stiffness and nonlinear constraint damping, thereby achieving nonlinear vibration reduction.

3. The aircraft pipeline double-layer clamp with nonlinear vibration reduction function according to claim 1, characterized in that, Both the outer and inner clamp bushings are made of nitrile rubber-organic small molecule hybrid composite material, wherein the organic small molecules are hindered phenols, hindered amines, and other organic small molecule substances with polar functional groups.

4. The aircraft pipeline double-layer clamp with nonlinear vibration reduction function according to claim 1, characterized in that, The width of the outer clamp is slightly smaller than the width of the inner clamp.

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