Acoustic black hole vibration reduction structure

Abstract

The invention discloses an acoustic black hole vibration reduction structure, and relates to the technical field of vibration reduction and noise reduction, the acoustic black hole vibration reduction structure comprises an acoustic black hole beam, a supporting part and a damping layer, the thickness of the longitudinal section of the acoustic black hole beam is gradually increased in a power function mode in the length direction of the acoustic black hole beam, and the damping layer is arranged on the acoustic black hole beam; one end face, in the thickness direction, of the acoustic black hole beam is a plane end, one end of the supporting part makes contact with the plane end, and the contact end face, making contact with the acoustic black hole beam, of the supporting part is arc-shaped. The effective length of the acoustic black hole beam is changed through contact between the arc shape of the supporting part and the acoustic black hole beam, then the inherent frequency of the acoustic black hole beam is changed, widening of the working frequency band is achieved, the nonlinear acoustic black hole vibration reduction structure with the variable rigidity is provided, the certain working frequency band is achieved, and the vibration reduction effect is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration reduction and noise reduction, and particularly to an acoustic black hole vibration reduction structure. Background Art

[0002] Vibration is a standing wave generated by multiple reflections at the boundary in a structure, and noise is the wave energy radiated from the structure vibration into the air. Therefore, controlling the wave behavior in the structure is an effective means to achieve vibration reduction and noise reduction of the structure. Nowadays, the common manipulation of waves is mainly divided into two methods: active and passive.

[0003] Active methods generally require external energy supply, and the design of the system is very cumbersome, so they have not been widely promoted at present; in addition, for passive methods, the most basic form is to attach damping materials, and some viscoelastic materials can effectively absorb vibration energy. However, for some major equipment, a large amount of damping materials need to be pasted on the surface for vibration reduction. Although this can achieve the effect of vibration reduction and noise reduction, it is not conducive to the lightweight of the structure, not only increasing the economic cost, but also adding too much additional mass.

[0004] A dynamic vibration absorber is a device that uses a resonance system to absorb the vibration energy of an object. It attaches a mass-spring resonance system to the vibrating object. When the additional system resonates, the reaction force generated can reduce the vibration of the vibrating object. The dynamic vibration absorber is particularly suitable for occasions where the excitation force is mainly single-frequency or the frequency is very low. The concept of the Acoustic Black Hole (ABH) effect has opened a new chapter in the research on realizing the artificial control of the propagation of flexural waves in elastic media and structures. As a new type of passive control method, the acoustic black hole controls the wave propagation through the design and optimization of the structure's own shape, and has the advantages of simple and flexible implementation and small mass. It has great potential and broad application prospects in thin-walled structures. Applying the acoustic black hole principle to the dynamic vibration absorber can design a dynamic vibration absorber with a special structure.

[0005] This dynamic vibration absorber combines the broadband effect of the acoustic black hole and the characteristics of the dynamic vibration absorber. When the flexural wave propagates on this dynamic vibration absorber, as the thickness of the structure decreases, the wave amplitude increases, the wave speed decreases, and the wave energy can be concentrated in the area with the smallest thickness and dissipated through the damping material, achieving the purpose of energy absorption or vibration reduction and noise reduction.

[0006] However, the traditional dynamic vibration absorber based on the acoustic black hole principle is usually a linear system and can only achieve the best effect when the dynamic vibration absorber and the controlled object have frequency matching, which limits its application range.

[0007] Therefore, there is an urgent need for an acoustic black hole vibration reduction structure that can broaden the effective frequency band of vibration suppression and improve the vibration reduction effect. Summary of the Invention

[0008] The object of the present invention is to provide an acoustic black hole vibration damping structure to solve the problems existing in the above-mentioned prior art. A support part that can move linearly along the planar end is in contact with the planar end of the acoustic black hole beam, and the contact end face of the support part is arc-shaped. By adjusting the position of the support part, the initial effective vibration length of the acoustic black hole beam can be changed, so as to achieve the change of the working frequency band range and improve the vibration damping effect.

[0009] To achieve the above object, the present invention provides the following solution: The present invention provides an acoustic black hole vibration damping structure, including an acoustic black hole beam, a support part, and a damping layer. Along the length direction of the acoustic black hole beam, the longitudinal section thickness of the acoustic black hole beam increases in the form of a power function. The end with the largest longitudinal section thickness of the acoustic black hole beam is the vibration input end. A damping layer is provided on the acoustic black hole beam. One end face of the acoustic black hole beam in the thickness direction is a planar end. One end of the support part is in contact with the planar end, and the contact end face of the support part in contact with the acoustic black hole beam is arc-shaped along the length direction of the acoustic black hole beam.

[0010] Preferably, a constant-thickness beam is connected to the end with the largest longitudinal section thickness of the acoustic black hole beam. Along the length direction of the constant-thickness beam, the longitudinal section thickness of the acoustic black hole beam remains unchanged.

[0011] Preferably, the constant-thickness beam and the acoustic black hole beam are integrally provided.

[0012] Preferably, the constant-thickness beam has the same width as the acoustic black hole beam.

[0013] Preferably, the damping layer is provided at the end with the smallest longitudinal section thickness of the acoustic black hole beam.

[0014] Preferably, the width of the damping layer is the same as the width of the acoustic black hole beam, and the end face of the damping layer is flush with the end face of the end with the smallest longitudinal section thickness of the acoustic black hole beam.

[0015] Preferably, the support part includes a contact block for abutting against the acoustic black hole beam and an adjustment block. The adjustment block and the contact block are connected by an adjustment bolt, and the screw rod of the adjustment bolt is parallel to the planar end.

[0016] Preferably, the support part moves linearly along the length direction of the acoustic black hole beam through an adjustment mechanism. The adjustment mechanism includes a bottom plate, an adjustment screw rod, and a locking nut. A strip-shaped hole for the adjustment screw rod to pass through is opened on the bottom plate. The width of the strip-shaped hole matches the outer diameter of the screw rod part of the adjustment screw rod. The adjustment screw rod sequentially passes through the strip-shaped hole and the support part and is connected to the locking nut.

[0017] Preferably, a strip-shaped accommodation groove for accommodating the head of the adjusting screw is provided on the end face of the bottom plate away from the supporting part, and the thickness of the strip-shaped accommodation groove is not less than the thickness of the head of the adjusting screw.

[0018] Preferably, a connecting part is provided at one end of the bottom plate, and the connecting part is connected to the end with the largest longitudinal section thickness of the acoustic black hole beam.

[0019] The present invention mainly achieves the following technical effects compared with the prior art:

[0020] The position where the acoustic black hole beam contacts the supporting part can be regarded as the fixed end of the acoustic black hole beam. That is to say, the change in the position of the supporting part can be regarded as the change in the fixed end position of the acoustic black hole beam. The change in the fixed end position represents the change in the effective vibration length and stiffness of the acoustic black hole beam, thereby realizing the adjustment of the frequency of the acoustic black hole beam. On this basis, since the contact end face of the supporting part is arc-shaped, when the acoustic black hole beam vibrates, the contact area between the acoustic black hole beam and the arc-shaped contact end face of the supporting part will change. The change in the contact area represents the change in the effective vibration length of the acoustic black hole beam, and the frequency will also change accordingly, so that the acoustic black hole beam has a certain working frequency band. That is, the present invention provides a variable-stiffness non-linear acoustic black hole vibration damping structure with a certain working frequency band, improving the vibration damping effect.

[0021] The following technical effects are also achieved by other solutions of the present invention compared with the prior art:

[0022] By adjusting the position of the supporting part, the working frequency band can be adjusted. The position of the supporting part can be adjusted according to the frequency characteristics of the controlled object, etc., to realize the adjustment of the working frequency band range, and a wide-frequency vibration damping effect can be achieved for different controlled objects, with a wide application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic structural diagram of the acoustic black hole vibration damping structure from the first perspective in the embodiment of the present invention;

[0025] Figure 2 It is a schematic structural diagram of the acoustic black hole vibration damping structure from the second perspective in the embodiment of the present invention;

[0026] Figure 3 It is the front view of the acoustic black hole vibration damping structure in the embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the propagation of vibration waves in an acoustic black hole beam in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the principle of bandwidth broadening of the acoustic black hole vibration damping structure in an embodiment of the present invention (where the relative displacement refers to the vertical displacement from the deformed beam tip to the undeformed beam tip);

[0029] Figure 6 This is a comparison diagram of the frequency response curves of the controlled structure with the acoustic black hole vibration damping structure installed and the controlled structure without the acoustic black hole installed in an embodiment of the present invention;

[0030] Wherein, 1. Acoustic black hole beam; 2. Damping layer; 3. Constant-thickness beam; 4. Contact block; 5. Adjusting block; 6. Adjusting bolt; 7. Bottom plate; 8. Adjusting screw; 9. Locking nut; 10. Strip-shaped hole; 11. Connecting part; 12. L-shaped connecting plate; 13. Strip-shaped accommodating groove. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] The object of the present invention is to provide an acoustic black hole vibration damping structure to solve the problems existing in the prior art. A support part that can move linearly along the plane end is in contact with the plane end of the acoustic black hole beam, and the contact end face of the support part is arc-shaped. By adjusting the position of the support part, the initial effective vibration length of the acoustic black hole beam can be changed, thereby realizing the change of the working frequency band range and improving the vibration damping effect.

[0033] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0034] Please refer to as Figures 1 to 6 As shown, an acoustic black hole vibration damping structure is provided, including an acoustic black hole beam 1, a support part, and a damping layer 2. Along the length direction of the acoustic black hole beam 1, the thickness of the longitudinal section of the acoustic black hole beam 1 increases in the form of a power function. The end with the largest thickness of the longitudinal section of the acoustic black hole beam 1 is the vibration input end. A damping layer 2 is provided on the acoustic black hole beam 1. One end face of the acoustic black hole beam 1 in the thickness direction is a plane end. One end of the support part is in contact with the plane end, and the contact end face of the support part in contact with the acoustic black hole beam 1 is arc-shaped along the length direction of the acoustic black hole beam 1.

[0035] The vibration reduction principle of the acoustic black hole beam 1 itself is: based on the principle that the bending waves in the solid medium decrease according to a certain power function as the thickness of the structure decreases, and its corresponding phase velocity and group velocity also decrease, thereby concentrating the wide-band bending waves in the area where the thickness of the structure becomes thinner on a certain spatial scale. The propagation speed of the waves in the acoustic black hole beam 1 decreases as the thickness decreases, the wavelength decreases, the vibration amplitude of the wave increases, and the energy is concentrated in the area where the thickness becomes smaller, and then most of the bending wave energy is consumed by the damping layer 2, thereby achieving vibration reduction and noise reduction.

[0036] Provided in this embodiment is a nonlinear acoustic black hole vibration reduction structure with variable stiffness, which has a certain working frequency band, and the working frequency band can be adjusted by adjusting the position of the support part, which is beneficial to improving the vibration reduction effect. The variable stiffness and nonlinearity are achieved by introducing the support part. The specific principle is: the position where the acoustic black hole beam 1 contacts the support part can be regarded as the fixed end of the acoustic black hole beam 1, that is, the change in the position of the support part can be regarded as the change in the position of the fixed end of the acoustic black hole beam 1. The change in the position of the fixed end represents the change in the effective vibration length of the acoustic black hole beam 1 and the change in stiffness (the effective vibration length refers to: the distance between the point closest to the small area end face of the acoustic black hole beam 1 in the contact area between the acoustic black hole beam 1 and the support part and the small area end face of the acoustic black hole beam 1), thereby realizing the adjustment of the frequency of the acoustic black hole beam 1. On this basis, due to The contact end face of the support part is arc-shaped. When the acoustic black hole beam 1 vibrates, the contact area between the acoustic black hole beam 1 and the arc-shaped contact end face of the support part will change. The change in the contact area represents the change in the effective vibration length of the acoustic black hole beam 1, that is, the point position of the small-area end face closest to the acoustic black hole beam 1 in the contact area between the acoustic black hole beam 1 and the support part changes, and the frequency will also change accordingly, so that the acoustic black hole beam 1 has a certain working frequency band; the closer the support part is to the end of the acoustic black hole beam 1 with the smallest longitudinal section thickness (the end most prone to deformation), the easier it is for the acoustic black hole beam 1 to contact the arc-shaped contact end face of the support part, and the stronger the nonlinear effect; the acoustic black hole vibration reduction structure in this embodiment cleverly combines nonlinear characteristics and acoustic black hole energy aggregation characteristics, avoids the limitations of traditional acoustic black holes, realizes broadband control of vibration, and achieves efficient vibration reduction effect.

[0037] A constant thickness beam 3 can be connected to the end of the acoustic black hole beam 1 with the largest longitudinal section thickness. Along the length direction of the constant thickness beam 3, the longitudinal section thickness of the acoustic black hole beam 1 remains unchanged. The setting of the constant thickness beam 3 can enable waves to enter the acoustic black hole beam 1 smoothly, thereby improving the vibration reduction effect.

[0038] The constant thickness beam 3 is integrated with the acoustic black hole beam 1 to improve the structural strength.

[0039] The constant thickness beam 3 has the same width as the acoustic black hole beam 1, which ensures the stability of wave transmission.

[0040] The damping layer 2 is arranged at one end of the acoustic black hole beam 1 with the smallest longitudinal cross-sectional thickness. Combining with the characteristic of the acoustic black hole beam 1 to concentrate energy at the end, it can effectively absorb vibration energy, achieving a good vibration damping effect and reducing costs at the same time.

[0041] In an ideal state, the thickness of the tip of the acoustic black hole is zero. At this time, when the wave propagates to the tip, the wave speed is zero, and the wave can gather at the tip and cannot be reflected. However, due to processing technology limitations, there will be a certain thickness at the tip of the acoustic black hole, which is the cut-off thickness. Due to the existence of the cut-off thickness, the wave speed cannot be reduced to zero, which will cause the wave to be reflected and affect the acoustic black hole effect. Therefore, the width of the damping layer 2 is set to be the same as the width of the acoustic black hole beam 1, and the end face of the damping layer 2 is flush with the end face of the end with the smallest longitudinal cross-sectional thickness of the acoustic black hole beam 1, which can reduce the boundary reflection caused by the cut-off thickness due to the processing technology limitations of the acoustic black hole beam 1.

[0042] In this embodiment, the support part includes a contact block 4 for abutting against the acoustic black hole beam 1 and an adjusting block 5. The adjusting block 5 is connected to the contact block 4 through an adjusting bolt 6. The screw rod of the adjusting bolt 6 is parallel to the flat end of the acoustic black hole beam 1. By loosening the adjusting bolt 6, the contact block 4 can rotate relative to the adjusting block 5, so that different positions of the arc-shaped contact end face of the contact block 4 are in contact with the flat end of the acoustic black hole beam 1, making it easier for the contact block 4 to achieve good fitting contact with the flat end of the acoustic black hole beam 1.

[0043] In this embodiment, the support part moves linearly along the length direction of the acoustic black hole beam 1 through an adjusting mechanism. The adjusting mechanism includes a bottom plate 7, an adjusting screw rod 8 and a locking nut 9. A strip-shaped hole 10 for the adjusting screw rod 8 to pass through is opened on the bottom plate 7. The width of the strip-shaped hole 10 matches the outer diameter of the screw rod part of the adjusting screw rod 8. The adjusting screw rod 8 passes through the strip-shaped hole 10 and the support part in sequence and is connected to the locking nut 9. Specifically, the adjusting block 5 of the support part can be set in an inverted T shape to provide space for the adjusting screw rod 8 to pass through and connect the locking nut 9. The adjustment principle in this embodiment is: loosen the adjusting screw rod 8, and at this time, the support part can be controlled to move along the strip-shaped hole 10; tighten the adjusting screw rod 8, and the position of the support part is locked.

[0044] In other embodiments, a telescopic cylinder or other linear motion mechanisms can also be used to control the movement of the support part, as long as it can achieve the linear movement of the support part along the length direction of the acoustic black hole beam 1.

[0045] By adjusting the position of the support part, the working frequency band can be adjusted. The position of the support part can be adjusted according to the frequency characteristics of the controlled object, etc., to achieve the adjustment of the working frequency band range. For different controlled objects, a wide-band vibration damping effect can be achieved, and the applicable range is wide.

[0046] A connecting portion 11 is provided at one end of the bottom plate 7, and the connecting portion 11 is connected to the end of the acoustic black hole beam 1 with the largest longitudinal section thickness (when a constant thickness beam 3 is provided, the connecting portion 11 is connected to the constant thickness beam 3). At this time, the bottom plate 7 can be used as a vibration input end, and the vibration is transmitted to the acoustic black hole beam 1 through the connecting portion 11 in turn.

[0047] When the acoustic black hole beam 1 is connected to the connecting part 11, bolts can be used to directly penetrate the connecting part 11 and threadedly connect with the acoustic black hole beam 1; when the constant thickness beam 3 is connected to the connecting part 11, bolts can be used to directly penetrate the connecting part 11 and threadedly connect with the constant thickness beam 3, or L-shaped connecting plates 12 are arranged on the upper and lower sides of the constant thickness beam 3, the L-shaped connecting plates 12 are bolted to the connecting part 11, and the L-shaped connecting plates 12 on both sides and the constant thickness beam 3 are bolted together.

[0048] In order to prevent the head of the adjusting screw 8 from occupying the space below the base plate 7 and affecting the assembly of the base plate 7 on the vibration source, a strip-shaped receiving groove 13 for receiving the head of the adjusting screw 8 is provided on the end surface of the base plate 7 away from the supporting portion. The thickness of the strip-shaped receiving groove 13 is not less than the thickness of the head of the adjusting screw 8.

[0049] In this embodiment, the power function expression of the thickness change of the longitudinal section of the acoustic black hole beam 1 is h(x)=εx m , where h(x) represents the thickness of the acoustic black hole beam 1, x represents the distance from any point of the acoustic black hole beam 1 to the point where the thickness of the acoustic black hole beam 1 is the smallest, ε represents the coefficient, and m is greater than or equal to 2.

[0050] During actual use, vibration is transmitted to the acoustic black hole beam 1 through the base plate 7, the connecting part 11 and the constant thickness beam 3. The vibration wave is transmitted in the acoustic black hole beam 1 and gathered in the area with the smallest thickness of the acoustic black hole beam 1. The damping layer 2 can absorb the vibration energy and achieve the effect of vibration reduction. Moreover, the contact area of the arc-shaped contact end face of the acoustic black hole beam 1 with the supporting part changes continuously during the vibration process, so that the acoustic black hole beam 1 has a certain working frequency band, which is beneficial to improving the vibration reduction effect.

[0051] Adaptive changes made according to actual needs are all within the protection scope of the present invention.

[0052] It should be noted that 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-restrictive 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. Any reference numerals in the claims should not be regarded as limiting the claims involved.

[0053] In the present invention, specific examples are used to illustrate the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An acoustic black hole vibration damping structure, characterized in that It includes an acoustic black hole beam, a support portion and a damping layer. Along the length direction of the acoustic black hole beam, the thickness of the longitudinal section of the acoustic black hole beam increases in the form of a power function. The end with the largest thickness of the longitudinal section of the acoustic black hole beam is the vibration input end. A damping layer is provided on the acoustic black hole beam. One end face of the acoustic black hole beam in the thickness direction is a flat end face. One end of the support portion is in contact with the flat end face, and the contact end face of the support portion in contact with the acoustic black hole beam is arranged in an arc along the length direction of the acoustic black hole beam.

2. The acoustic black hole vibration damping structure according to claim 1, wherein A constant-thickness beam is connected to the end with the largest thickness of the longitudinal section of the acoustic black hole beam. Along the length direction of the constant-thickness beam, the thickness of the longitudinal section of the acoustic black hole beam remains unchanged.

3. The acoustic black hole vibration damping structure according to claim 2, characterized in that, The constant-thickness beam and the acoustic black hole beam are integrally provided.

4. The acoustic black hole vibration damping structure according to claim 2, characterized in that, The constant-thickness beam has the same width as the acoustic black hole beam.

5. The acoustic black hole vibration damping structure according to claim 1, characterized in that The damping layer is provided at the end with the smallest thickness of the longitudinal section of the acoustic black hole beam.

6. The acoustic black hole vibration damping structure according to claim 5, wherein, The width of the damping layer is the same as the width of the acoustic black hole beam, and the end face of the damping layer is flush with the end face of the end with the smallest thickness of the longitudinal section of the acoustic black hole beam.

7. The acoustic black hole vibration damping structure according to claim 1, wherein, The support portion includes a contact block for abutting against the acoustic black hole beam and an adjustment block. The adjustment block and the contact block are connected by an adjustment bolt, and the screw rod of the adjustment bolt is parallel to the flat end face.

8. The acoustic black hole vibration damping structure according to claim 1, wherein, The support portion moves linearly along the length direction of the acoustic black hole beam through an adjustment mechanism. The adjustment mechanism includes a bottom plate, an adjustment screw rod and a locking nut. A strip-shaped hole for the adjustment screw rod to pass through is formed on the bottom plate. The width of the strip-shaped hole matches the outer diameter of the screw rod portion of the adjustment screw rod. The adjustment screw rod sequentially passes through the strip-shaped hole and the support portion and is connected to the locking nut.

9. The acoustic black hole vibration damping structure according to claim 8, characterized in that, A strip-shaped accommodation groove for accommodating the head of the adjustment screw rod is provided on the end face of the bottom plate away from the support portion, and the thickness of the strip-shaped accommodation groove is not less than the thickness of the head of the adjustment screw rod.

10. The acoustic black hole vibration damping structure according to claim 8, characterized in that, A connection portion is provided at one end of the bottom plate, and the connection portion is connected to the end with the largest thickness of the longitudinal section of the acoustic black hole beam.

Images