Coupled negative stiffness pipeline system vibration absorbing multi-stable non-linear energy sink

Abstract

A kind of coupled negative stiffness pipeline system vibration absorption multi-stable non-linear energy sink, using the lightweight device of coupling of clamp and pipeline, its segmented stiffness beam structure provides segmented positive stiffness, magnet group structure provides negative stiffness, both are connected in parallel to realize multi-stable stiffness. The multi-stable stiffness of the non-linear energy sink can be modulated by adjusting the size of linear beam and the size of magnet block, has extremely efficient pipeline system wideband bending vibration suppression capability.

Description

Technical Field

[0001] This invention relates to a technology in the field of vibration absorption, specifically a vibration-absorbing multistable nonlinear energy trap for a coupled negative stiffness pipeline system. Background Technology

[0002] Vibration is a typical hazard to the safe operation of pump-type mechanical piping systems. Multi-frequency vibrations, such as mechanical vibration and medium pressure pulsation, propagate within the piping system, causing severe vibrations that seriously affect the stable operation of pumps. Therefore, efficient vibration control of piping systems is crucial. Installing dynamic vibration absorbers is a common method for vibration control. However, passive vibration absorbers have significant limitations in practical applications due to their narrow damping bandwidth; active vibration absorbers are rarely used in complex piping systems with numerous accessories. Therefore, it is necessary to develop new devices that meet the requirements of modern pipeline broadband vibration damping. Summary of the Invention

[0003] To address the aforementioned shortcomings of existing technologies, this invention proposes a vibration-absorbing multistable nonlinear energy trap for coupled negative stiffness pipeline systems. It employs a lightweight device coupled to the pipeline via clamps. A segmented stiffness beam structure provides segmented positive stiffness, while a magnet assembly structure provides negative stiffness; the two are connected in parallel to achieve multistable stiffness. The multistable stiffness of this nonlinear energy trap can be modulated by adjusting the dimensions of the linear beam and the magnet blocks, resulting in highly efficient suppression of broadband bending vibrations in pipeline systems.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a vibration-absorbing multi-stable nonlinear energy trap for a coupled negative stiffness pipeline system, comprising: a segmented stiffness structure and a magnet assembly structure. The spatial positions from bottom to top are: clamps fixing the invention to the pipeline; the segmented stiffness structure being fixed to the clamps; and the magnet assembly structure being fixed to the segmented stiffness structure.

[0006] The segmented stiffness structure includes: a linear beam assembly, a vibration absorber mass block, and a support, wherein: one end of the linear beam assembly is fixed to the support, and the other end cooperates with the vibration absorber mass block.

[0007] The linear beam assembly includes: two identical connecting beams and four identical stiffness beams arranged in pairs, with the six beams arranged in parallel; one end of the connecting beam is fixed to the support, and the other end is fixed to the vibration absorber mass block; one end of the stiffness beam is fixed to the support, and the other end is in clearance fit with the vibration absorber mass block.

[0008] The magnet assembly structure includes: a large support beam, a small support beam, two magnet slots, and two magnet blocks. The large support beam is fixed to a support at one end and to a magnet slot at the other end, with a magnet block fixed inside the magnet slot. The small support beam is fixed to a vibration absorber mass block at one end and to a magnet slot at the other end, with a magnet block fixed inside the magnet slot. The two magnet blocks are aligned with the same center line and are arranged opposite each other with the same magnetic properties.

[0009] The multi-steady-state stiffness of the present invention is formed as follows: When the oscillator mass block and the piping system vibrate relative to each other, the two connecting beams first generate bending stiffness; then, the two identical stiffness beams with slightly larger diameters generate bending stiffness; finally, the two identical stiffness beams with the largest diameters generate bending stiffness. That is, during relative vibration within a small displacement range, the segmented stiffness structure generates one segment of linear stiffness; during relative vibration within a medium displacement range, the segmented stiffness structure generates two segments of linear stiffness; and during relative vibration within a large displacement range, the segmented stiffness structure generates three segments of linear stiffness. The relationship between the segmented bending force and the relative displacement can be solved as a piecewise linear function, exhibiting a piecewise linear positive stiffness characteristic. Simultaneously, when the oscillator mass block and the piping system vibrate relative to each other, the two magnet blocks generate relative tangential motion, and the resulting magnetic force and displacement relationship can be fitted as a linear function, exhibiting a negative stiffness characteristic. The positive and negative stiffnesses are coupled in parallel and superimposed to achieve the multi-steady-state stiffness of the present invention. Technical effect

[0010] By replacing different vibration absorber mass blocks, the diameter of the hole and the mass of the mass block can be adjusted, making the clearance between the vibration absorber mass and the stiffness beam adjustable, thereby adjusting the resulting piecewise linear positive stiffness. By replacing different linear beam assemblies, the length and diameter of the connecting beam and the stiffness beam can be adjusted, which can also adjust the resulting piecewise linear positive stiffness. By replacing different magnet blocks and the distance between the opposite faces of the magnet blocks, the resulting negative stiffness can be adjusted.

[0011] The multistable stiffness of this invention is generated by the relative motion between the oscillator mass block and the pipeline. To adjust the multistable stiffness of this invention, it is necessary to adjust the dimensions of the linear beam assembly and the oscillator mass, as well as the dimensions of the magnet block and the distance between their opposing surfaces. The multistable stiffness adjusted in this process enables the multistable nonlinear energy trap of this invention, coupled with a negative stiffness pipeline system, to achieve efficient vibration suppression for bending vibrations in broadband pipeline systems across different frequency ranges. Attached Figure Description

[0012] Figure 1 and Figure 2 This is a schematic diagram of the structure of the present invention;

[0013] Figure 3 This is a schematic diagram of a segmented stiffness structure;

[0014] Figure 4A schematic diagram of a segmented stiffness structure with a set of diameter linear beam components;

[0015] Figure 5 Schematic diagram of the oscillator mass block;

[0016] Figure 6 A schematic diagram showing a certain fitting clearance between the hole in the oscillator mass block and the linear component;

[0017] Figure 7 This is a schematic diagram of a segmented stiffness structure support;

[0018] Figure 8 This is a schematic diagram of the magnet assembly structure;

[0019] Figure 9 Schematic diagram of the large and small support beams of the magnet assembly structure;

[0020] Figure 10 This is a schematic diagram of the magnet slot in the magnet assembly structure;

[0021] Figure 11 This is a schematic diagram of the magnet block structure of the magnet assembly;

[0022] Figure 12 This is a schematic diagram of a clamp;

[0023] Figure 13 (a) Figure 13 (b) Figure 13 (c) are the positive stiffness curves of the segmented stiffness structure, the negative stiffness curves of the magnet group structure, and the multi-stable stiffness curves, respectively.

[0024] Figure 14 Amplitude-frequency response curves of bending vibration before and after applying the present invention to the pipeline system; In the diagram: 1. Pipeline, 2. Clamp, 3. Segmented stiffness structure support, 4. Connecting beam, 5. Stiffness beam, 6. Stiffness beam, 7. Main support beam, 8. Magnet slot, 9. Magnet block, 10. Magnet block, 11. Magnet slot, 12. Small support beam, 13. Vibration absorber mass block. Detailed Implementation

[0025] like Figure 1 and Figure 2 As shown in this embodiment, a vibration-absorbing multi-stable nonlinear energy trap for a coupled negative stiffness pipeline system includes: a segmented stiffness structure support 3 on a fixed clamp 2; stiffness beams 5 and 6 fixed to the segmented stiffness structure support 3; a connecting beam 4 fixed to the segmented stiffness structure support 3; a vibration-absorbing mass block 13 fixed to the connecting beam 4 and clearance-fitted with the stiffness beams 5 and 6; a large support beam 7 fixed to the segmented stiffness structure support 3; and a small support beam 12 fixed to the vibration-absorbing mass block 13. Magnet blocks 9 and 10 are respectively disposed in magnet slots 8 and 11 fixed to the large support beam 7 and the small support beam 12.

[0026] like Figures 3-7 As shown, the six holes at the upper end of the segmented stiffness structure support 3 of the segmented stiffness structure are, from the outside to the inside, fixed to two connecting beams 4, two stiffness beams 5, and two stiffness beams 6 in sequence. The other end of the connecting beam 4 is fixed to a vibration-absorbing mass block 13. The other ends of the stiffness beams 5 and 6 are fitted with the vibration-absorbing mass block 13 with a clearance fit; the two clearances are unequal and gradually increase in size, as shown in the diagram. Figure 6 As shown. Figure 4 As shown, the two connecting beams 4 are identical, with smaller diameters and lower bending stiffness; the two stiffness beams 5 are identical, with medium diameters and medium bending stiffness; the two stiffness beams 6 are identical, with larger diameters and higher bending stiffness. Figure 6 As shown, the clearance between stiffness beams 5 and 6 and vibration absorber mass block 13 is unequal and gradually increases.

[0027] like Figure 8-11 As shown, the large support beam 7 and the small support beam 12 of the magnet assembly structure are fixed to the segmented stiffness structure support 3 and the vibration absorber mass block 13, respectively; the magnet blocks 9 and 10 are respectively set in the magnet slots 8 and 11 fixed to the large support beam 7 and the small support beam 12; the two magnet blocks are the same and are set opposite each other with the same magnetism, and when the vibration absorber mass block and the pipeline system generate relative vibration, the two magnet blocks generate relative tangential motion.

[0028] like Figure 12 As shown, the clamp 2 secures the invention to the pipeline.

[0029] When the nonlinear energy trap is in operation, the vibration of pipe 1 transmits the vibrational force to the segmented stiffness structure support 3, linear beam assemblies 4-6, and vibration-absorbing mass block 13 via clamp 2. The linear beam assembly 4-6 and the vibration-absorbing mass block 13 generate segmented bending vibrations, forming segmented linear normal stiffness, as shown in the stiffness curve. Figure 13 As shown in (a); simultaneously, the vibration force of pipe 1 is also transmitted to the large support beam 7, and the vibration-absorbing mass block 13 also transmits the vibration force to the small support beam 12. The bending support beams 7 and 12 drive the two magnet blocks 9 and 10 to generate tangential motion in the vibration direction, forming negative stiffness, and the stiffness curve is as follows. Figure 13 As shown in (b); after parallel superposition, a multi-stable stiffness is formed, and the stiffness curve is as follows. Figure 13As shown in (c), e1 and e2 are two gradually increasing fit gaps between stiffness beams 5 and 6 and vibration absorber mass block 13, respectively, with e2 > e1. Points a, b, c, d, and e in the figure represent different steady-state points. When the relative vibration between vibration absorber mass block 13 and pipe 1 is less than e1, the two connecting beams 4 generate bending stiffness; when the relative vibration between vibration absorber mass block 13 and pipe 1 is greater than e1 but less than e2, the two stiffness beams 5 generate bending stiffness; when the relative vibration between vibration absorber mass block 13 and pipe 1 is greater than e2, the two stiffness beams 6 generate bending stiffness. These piecewise linear stiffnesses are plotted together; simultaneously, magnet blocks 9 and 10 consistently generate negative stiffness. Figure 13 (a) and Figure 13 (b) The parallel superposition of positive and negative stiffness is the multistable stiffness that forms the nonlinear energy trap.

[0030] Based on specific practical experiments, the pipeline parameters are set as shown in Table 1; the dimensional parameters of the linear components are shown in Table 2; and the dimensions of the cylindrical magnet blocks are shown in Table 3.

[0031] Table 1 Piping Parameters parameter value parameter value Pipe length (mm) 1400 <![CDATA[density (kg / m 3 )]]> 8 Outer diameter (mm) 40 Poisson's ratio 0.3 Inner diameter(mm) 30 Elastic modulus (GPa) 190

[0032] Table 2 Dimensions of Linear Beam Components parameter value parameter value length 90mm Diameter 1 3.29mm Diameter 2 2.89mm Diameter 3 3.91mm

[0033] Table 3 Dimensions of Cylindrical Magnet Blocks parameter value parameter value thickness 8mm diameter 26mm spacing 2.6mm Vacuum permeability <![CDATA[4π×10 -7 T·mA]]> magnetic flux density 1.34T

[0034] Under the specific environment of steady-state lateral bending vibration of pipeline 1, this invention is designed with the dimensional parameters in Tables 2 and 3 and attached to pipeline 1, enabling simulation to obtain the following results: Figure 14 The vibration suppression effect is evident. It can be seen that with the installation of the nonlinear energy trap of the present invention on pipe 1, the steady-state lateral bending vibration of pipe 1 decreases significantly, the vibration suppression rate is outstanding, and the vibration suppression effect is present over a wide frequency band, demonstrating the broadband vibration suppression characteristics of the present invention, and the effect is significant. This can reduce the failures of the overall pipeline system during operation and compensate for the shortcomings of current pipeline system vibration suppression technologies.

[0035] Compared with existing technologies, this invention can achieve the required segmented positive stiffness by using different segmented stiffnesses of the stiffness beam during bending; and achieve the required negative stiffness by using the tangential motion of the magnet pair. The superposition of the two forms a multi-stable stiffness, based on which this invention can effectively suppress the positive bending vibration of pipeline 1. In addition, it should be noted that the structural design of this invention is unprecedented.

[0036] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A vibration-absorbing multi-stable nonlinear energy trap for a coupled negative stiffness pipeline system, characterized in that, include: Segmented stiffness structure and magnet assembly structure; The lower end of the segmented stiffness structure support is fixed to the clamp; the upper end of the support is fixed to one end of the stiffness beam and the connecting beam, and the other end of the connecting beam is fixed to the vibration absorber mass block. The fit clearance between the other end of the stiffness beam and the vibration absorber mass block is unequal and gradually increases; the upper plane of the segmented stiffness structure support is fixed to one end of the large support beam; the upper plane of the vibration absorber mass block is fixed to one end of the small support beam; the other ends of the two large / small support beams are respectively fixed to two magnet slots; each of the two magnet slots fixes a magnet block; when the pipeline undergoes lateral bending vibration, the bending vibration of the connecting beam and the stiffness beam drives the vibration absorber mass block to vibrate, while the two magnet blocks move tangentially.

2. The vibration-absorbing multi-steady nonlinear energy trap for a coupled negative stiffness pipeline system according to claim 1, characterized in that, The linear beam is supported and fixed to the vibration absorber mass block and the segmented stiffness structure, respectively.

3. The vibration-absorbing multi-steady nonlinear energy trap for a coupled negative stiffness pipeline system according to claim 1, characterized in that, One end of the stiffness beam is fixed to the segmented stiffness structure, and the other end is fitted with a vibration absorber mass block with a gap that gradually increases.

4. The vibration-absorbing multi-stable nonlinear energy trap for a coupled negative stiffness pipeline system according to claim 1, characterized in that, The segmented stiffness structure is supported and fixed by clamps, which secure the invention to the pipeline.

5. The vibration-absorbing multi-steady nonlinear energy trap for a coupled negative stiffness pipeline system according to claim 1, characterized in that, The segmented stiffness structure support and vibration absorber mass block are connected to a pair of magnets through a large support beam and a small support beam, respectively. A magnet slot is fixed at the other end of the large support beam, and a magnet block is fixed in the magnet slot. A magnet slot is fixed at the other end of the small support beam, and a magnet block is fixed in the magnet slot.

6. The vibration-absorbing multi-stable nonlinear energy trap for a coupled negative stiffness pipeline system according to claim 5, characterized in that, The two magnet blocks are arranged opposite each other along the same center line and with the same magnetic poles.

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