A nonlinear energy trap device capable of harvesting energy of arbitrary stiffness and order.

Abstract

This invention relates to a nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting, comprising a mechanical spring unit, a mass block, a friction slide rail, a pulley, a nonlinear shaped track, constraint baffles, a base plate, and a power storage unit. Force transmission rods are provided on both sides of the mass block, connecting to the pulleys. The mass block slides and rubs against the friction slide rail. There are two pairs of constraint baffles, one on the left and one on the front and back. Nonlinear shaped tracks are provided on both sides of the mass block, with one curved side contacting the pulley and the other flat side connected to the left or right constraint baffles, on which piezoelectric plates are attached, via the mechanical spring unit. The front and back ends of the nonlinear shaped tracks slide against the constraint baffles on the front and back sides. The power storage unit is electrically connected to the piezoelectric plates. This nonlinear energy trap device can achieve arbitrary stiffness and energy harvesting. For different vibration control targets, the nonlinear restoring force can be optimized through structural adjustments to achieve the best vibration control effect.

Description

Technical Field

[0001] This invention relates to the field of vibration control technology, and more specifically to a nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting. Background Technology

[0002] Since its initial introduction in 1972, the concept of structural vibration control has seen rapid development, and the technology is now widely used in infrastructure and engineering structures. Structural vibration control technology has shifted away from the traditional design approach in civil engineering, which involved altering parameters such as damping and stiffness of the structure itself. Instead, it employs vibration damping devices to apply control forces opposite to the direction of motion to the main structure, thereby reducing its dynamic response. Among these technologies, the tuned mass damper (TMD) is a mature vibration control technique widely used for vibration reduction in practical engineering structures. However, traditional tuned mass damping technology, due to its fixed natural frequency, can only achieve control of a single mode. This results in drawbacks such as a narrow damping bandwidth, a large working stroke, and poor robustness, significantly limiting its vibration reduction effect in practical engineering applications.

[0003] To address the limitations of traditional tuned mass damping techniques, researchers have introduced nonlinear characteristics into the field of vibration control, proposing a nonlinear energy trap technology with nonlinear stiffness. Its basic principle is to utilize the internal resonance characteristics of nonlinear systems, enabling the nonlinear energy trap to capture the dynamic behavior of the main structure through internal resonance. Since the nonlinear energy trap does not have a fixed natural frequency, it can momentarily resonate with any mode of a multi-degree-of-freedom system. As the natural frequency of the nonlinear energy trap changes, the internal resonance behavior is disrupted, preventing the energy transferred to the substructure from returning to the main structure. This unidirectional energy transfer behavior is called targeted energy transfer.

[0004] The restoring force of existing nonlinear energy traps generally exhibits a cubic nonlinear relationship with the oscillator displacement, thus offering a wider damping bandwidth and a shorter working stroke compared to tuned mass dampers. However, due to the increasing complexity of building structures and the uncertainties of earthquakes and wind-induced vibrations, traditional nonlinear energy traps with fixed nonlinear order stiffness cannot meet the vibration control requirements of various structures and excitation conditions, thus limiting the practical application of this technology. Furthermore, converting and storing the mechanical energy generated during structural vibration could power monitoring equipment and other devices; however, existing nonlinear energy traps often lack this energy harvesting capability. Summary of the Invention

[0005] The purpose of this invention is to provide a nonlinear energy trap device that can achieve arbitrary stiffness and energy harvesting. This nonlinear energy trap device can achieve arbitrary stiffness and energy harvesting. For different vibration control objectives, the nonlinear restoring force can be optimized by structural adjustment to achieve the best vibration control effect.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting, comprising a mechanical spring unit, a mass block, a friction slide rail, a pulley, a nonlinear shaped track, a constraint baffle, a base plate, and an energy storage unit; the mass block is provided with force transmission rods on its left and right sides, the ends of which are connected to the pulleys; a first sliding connection part is provided in the middle of the bottom of the mass block, and first friction parts are provided on the left and right sides of the bottom, respectively; the friction slide rail is mounted on the base plate, and a second sliding connection part is provided in the middle of the top of the friction slide rail, which cooperates with the first sliding connection part; second friction parts are provided on the left and right sides, respectively, to interact with the first friction parts to form two pairs of friction pairs. The constraint baffles consist of two pairs, located on the left and right sides and front and rear sides of the mass block, respectively, and are fixedly connected to the base plate. Nonlinear shaped tracks are provided on the left and right sides of the mass block. The curved side of each track faces the mass block and contacts a pulley, while the flat side is connected to the left or right constraint baffle via a mechanical spring unit. Piezoelectric sheets are attached to the side of the constraint baffles connected to the mechanical spring unit on both sides. A third sliding connection is provided at both the front and rear ends of the nonlinear shaped track. A fourth sliding connection, cooperating with the third sliding connection, is provided on the side of the constraint baffles facing the nonlinear shaped track on both sides. The energy storage unit is electrically connected to the piezoelectric sheet.

[0007] Furthermore, the first sliding connection of the mass block is a protrusion, and the second sliding connection of the friction slide rail is a groove. The protrusion of the mass block and the groove of the friction slide rail cooperate with each other to limit and guide the movement direction of the mass block; the third sliding connection of the nonlinear shape track is a protrusion, and the fourth sliding connection of the constraint baffles on the front and rear sides is a groove. The protrusions at the front and rear ends of the nonlinear shape track cooperate with the grooves of the constraint baffles on the front and rear sides to limit and guide the movement direction of the nonlinear shape track; the grooves of the constraint baffles on the front and rear sides are at a certain height from the bottom plate so that the nonlinear shape track does not contact the bottom plate during movement.

[0008] Furthermore, the first friction part of the mass block is made of high-carbon steel, and the second friction part of the friction slide rail is made of semi-metallic friction material. The high-carbon steel and the semi-metallic friction material on the same side interact to form a friction pair, which plays a damping role, so that the mass block continuously dissipates its own energy during the movement, while ensuring the stability of the mass block's movement.

[0009] Furthermore, the mass block and the force transmission rods on both sides are integrally constructed to stably apply the restoring force transmitted by the pulley to the mass block; the length of the force transmission rod is long enough to ensure that the mechanical spring is in a compressed state at the equilibrium position.

[0010] Furthermore, the mechanical spring unit consists of a spring base and multiple mechanical springs evenly distributed on the spring base. One end of each mechanical spring is connected to one side of the plane of the nonlinear shaped track, and the other end is connected to one side of the spring base. The other side of the spring base, which is not connected to the mechanical spring, is in contact with the piezoelectric sheet on the surface of the constraint baffle, and a constantly changing pressure is applied to the piezoelectric sheet to generate electrical energy.

[0011] Furthermore, the two pairs of constraint baffles are perpendicular to each other, and each constraint baffle is fixedly connected to the base plate by bolts. Each constraint baffle is provided with stiffening ribs on its back to ensure that the constraint baffles can stably support the movement of the mechanical spring and the nonlinear shape track.

[0012] Furthermore, the energy storage unit consists of a battery and connecting wires. The battery is electrically connected to a corresponding piezoelectric element through the connecting wires. The piezoelectric element generates electrical energy through the continuous change of pressure and transmits the electrical energy to the battery for storage through the connecting wires.

[0013] Furthermore, the surface of the nonlinear shaped track is smooth and continuous and maintains contact with the pulley, transmitting the horizontal force exerted by the mechanical spring to the pulley in the form of a nonlinear restoring force through the surface; the specific form of the nonlinear restoring force depends on the shape of the surface, and any form of restoring force can be achieved by adjusting the shape of the surface, thereby achieving any order of stiffness.

[0014] Furthermore, the specific implementation method for arbitrary order stiffness is as follows:

[0015] Let the stiffness of the mechanical springs on both sides be k, and the mass block have a pre-compression Δ when it is in the initial position; with the initial position of the mass block as the origin and the direction of motion as the x-axis, the surface expression of the nonlinear orbit is y(x); the motion of the mass block will cause a change in the compression of the mechanical springs, and the following relationship holds when the mass block is in any position:

[0016] The horizontal elastic force provided by the mechanical springs on both sides is:

[0017] f s =k*(Δ+y(x)) (1)

[0018] The restoring force on the mass block is related to the horizontal force provided by the mechanical spring as follows:

[0019] F NES =2*fs*tanθ (2)

[0020] Combining equations (1) and (2), we get:

[0021] F NES =2k(Δ+y(x))*y′(x) (3)

[0022] Where θ is the angle between the normal at the contact point between the surface of the nonlinear track and the pulley and the y-direction, y′(x) is the derivative of y(x), y′(x) = tanθ; k and Δ are adjusted according to actual needs, for any form of restoring force F NES Any expression of the nonlinear shape orbit can be obtained by solving equation (3) to obtain the surface expression y(x).

[0023] Furthermore, for different working conditions, the surface shape of the nonlinear orbit is designed according to the following steps:

[0024] 1) Select the order combination of nonlinear restoring forces according to actual needs, and construct the dynamic model and motion equations of the main structure coupled with the nonlinear energy trap device;

[0025] 2) Determine different external excitations based on actual vibration reduction requirements, while considering robustness, and apply external excitations under different changes in the stiffness of the main structure.

[0026] 3) Select a suitable objective function and optimize the coefficients of each order of the selected nonlinear restoring force through an optimization algorithm to obtain a nonlinear restoring force expression with good control effect; substitute the optimized nonlinear restoring force expression into equation (3) to obtain the surface expression of the nonlinear shape track.

[0027] Compared with existing technologies, this invention has the following advantages: This invention proposes a nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting. This nonlinear energy trap device can achieve arbitrary forms of nonlinear restoring force by selecting different track surfaces. For vibration reduction requirements under different working conditions, such as wind-induced vibration, earthquakes, and micro-vibrations, control of different vibrations can be achieved by designing a suitable form of nonlinear restoring force. Simultaneously, the vibration control effect of this nonlinear energy trap device on the main structure is not limited by the form of nonlinear stiffness. By rationally designing and optimizing the form and parameters of the nonlinear restoring force, the best control effect can be obtained. Furthermore, this nonlinear energy trap device achieves the function of energy harvesting. This invention has a simple and stable structure, flexible installation location, and can be installed horizontally or vertically in practical engineering, effectively controlling both horizontal and vertical vibrations. Therefore, this invention has strong practicality and broad application prospects. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the nonlinear energy trap device in a static state according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the nonlinear energy trap device in motion according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the cooperation structure between the mass block and the friction slide rail in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the connection structure between the mechanical spring unit and the nonlinear shape track in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the constraint baffle in an embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of the connection structure between the energy storage unit and the piezoelectric element in an embodiment of the present invention;

[0034] Figure 7 This is a force analysis diagram of the nonlinear restoring force in an embodiment of the present invention;

[0035] Figure 8 This is a schematic diagram of a single-degree-of-freedom system motion model in an embodiment of the present invention;

[0036] Figure 9 This is the root mean square displacement diagram of the main structure under a certain earthquake in an embodiment of the present invention.

[0037] In the diagram: 1. Mechanical spring unit; 1-1. Mechanical spring; 1-2. Spring base; 2. Mass block; 2-1. Mass block protrusion; 2-2. Friction high-carbon steel; 2-3. Force transmission rod; 3. Friction slide rail; 3-1. Friction slide rail groove; 3-2. Semi-metallic friction material; 4. Pulley; 5. Non-linear shape track; 5-1. Non-linear shape track protrusion; 5-2. Non-linear shape track curved surface; 5-3. Non-linear shape track plane; 6. Constraint baffle; 6-1. Planar baffle; 6-2. Opening baffle; 6-3. Constraint baffle groove; 7. Base plate; 8. Energy storage unit; 8-1. Battery; 8-2. Connecting wire; 9. Piezoelectric sheet. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] like Figure 1-6 As shown, this embodiment provides a nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting, including a mechanical spring unit 1, a mass block 2, a friction slide rail 3, a pulley 4, a nonlinear shape track 5, a constraint baffle 6, a base plate 7, and an energy storage unit 8; the mass block 2 has force transmission rods 2-3 on its left and right sides, the ends of which are connected to the pulley 4; the mass block 2 has a first sliding connection part in the middle of its bottom, and first friction parts on its left and right sides respectively; the friction slide rail 3 is mounted on the base plate 7, and the friction slide rail 3 has a second sliding connection part in the middle of its top that cooperates with the first sliding connection part, and second friction parts on its left and right sides respectively, so as to interact with the first friction parts to form two pairs of friction pairs; the constraint baffle 6 has a total of Two pairs of nonlinear tracks are located on the left and right sides and front and rear sides of the mass block 2, respectively, and are fixedly connected to the base plate 7. Nonlinear track 5 is provided on the left and right sides of the mass block 2. The curved side 5-2 of the nonlinear track 5 faces the mass block 2 and contacts the pulley 4. The flat side 5-3 is connected to the left or right constraint baffle 6-1 via the mechanical spring unit 1. Piezoelectric sheet 9 is attached to the side of the constraint baffle 6-1 on the left and right sides connected to the mechanical spring unit 1. The front and rear ends of the nonlinear track 5 are provided with a third sliding connection part. The side of the constraint baffle 6-2 on the front and rear sides facing the nonlinear track 5 is provided with a fourth sliding connection part that cooperates with the third sliding connection part. The energy storage unit 8 is electrically connected to the piezoelectric sheet 9.

[0042] like Figure 2 As shown, when the mass block 2 moves along the friction slide rail 3, the point of contact between the pulley 4 and the curved surface 5-2 changes, causing the nonlinear shape track 5 on both sides to slide along the constraint baffle 6-2 with groove 6-3, which in turn changes the compression of the mechanical spring 1-1. This results in changes in both the direction and magnitude of the force on the mass block 2, thereby generating a nonlinear restoring force. At the same time, the pressure on the piezoelectric sheet 9 also changes, thereby generating electrical energy that is transferred to the battery 8-1 through the connecting wire 8-2 for energy harvesting.

[0043] like Figure 3As shown, the first sliding connection of the mass block 2 is a protrusion 2-1, and the second sliding connection of the friction slide rail 3 is a groove 3-1. The protrusion 2-1 of the mass block 2 and the groove 3-1 of the friction slide rail 3 cooperate with each other to limit and guide the movement direction of the mass block 2. The third sliding connection of the nonlinear shape track 5 is a protrusion 5-1, and the fourth sliding connection of the constraint baffles 6-2 on the front and rear sides is a groove 6-3. The protrusions 5-1 at the front and rear ends of the nonlinear shape track 5 cooperate with the grooves 6-3 of the constraint baffles 6-2 on the front and rear sides to limit and guide the movement direction of the nonlinear shape track 5. The grooves of the constraint baffles 6-2 on the front and rear sides are at a certain height from the bottom plate 7 so that the nonlinear shape track 5 does not contact the bottom plate 7 during movement.

[0044] The first friction part of the mass block 2 is high-carbon steel 2-2, and the second friction part of the friction slide rail 3 is semi-metallic friction material 3-2. The high-carbon steel 2-2 and the semi-metallic friction material 3-2 on the same side interact to form a friction pair, which plays a damping role, so that the mass block 2 continuously dissipates its own energy during the movement, while ensuring the stability of the movement of the mass block 2.

[0045] The mass block 2 and the force transmission rods 2-3 on both sides are integrally constructed. The force transmission rods 2-3 are used to stably apply the restoring force transmitted by the pulley 4 to the mass block 2. At the same time, the length of the force transmission rods 2-3 is long enough to ensure that the mechanical spring is in a compressed state at the equilibrium position.

[0046] like Figure 4 As shown, the mechanical spring unit 1 consists of a spring base 1-2 and multiple mechanical springs 1-1 evenly distributed on the spring base 1-2. One end of each mechanical spring 1-1 is connected to one side of the plane of the nonlinear shape track 5, and the other end is connected to one side of the spring base 1-2. The specific connection method is as follows: the bottom of the mechanical spring is first flattened, and holes matching the size of the mechanical spring 1-1 are provided in the plane 5-3 of the spring base 1-2 and the nonlinear shape track. The mechanical spring 1-1 is embedded in the holes. Since the mechanical spring 1-1 is in a compressed state under any movement, the device can be kept stable through the above structure. The other side of the spring base that is not connected to the mechanical spring is kept flat and is in contact with the piezoelectric sheet 9 on the surface of the constraint baffle 6-1. At the same time, a constantly changing pressure is applied to the piezoelectric sheet 9 to generate electrical energy.

[0047] Two pairs of constraint baffles 6 are perpendicular to each other. Each constraint baffle 6 is fixed to the base plate 7 by bolts, and each constraint baffle has stiffening ribs on its back to ensure that the constraint baffle can stably support the movement of the mechanical spring and the nonlinear track. One pair of constraint baffles has a flat surface with piezoelectric sheets attached and bears the compressive load of the mechanical spring; the other pair of constraint baffles has a groove in the middle to connect the nonlinear track and lock its direction of movement. The groove is at a certain height from the base plate so that the nonlinear track does not contact the base plate during movement.

[0048] like Figure 6 As shown, the energy storage unit 8 consists of a battery 8-1 and connecting wires 8-2. The battery 8-1 is electrically connected to the corresponding piezoelectric element 9 via the connecting wires 8-2. The piezoelectric element 9 is subjected to horizontal pressure from a mechanical spring. As the compression of the mechanical spring changes, the horizontal pressure on the piezoelectric element also changes, thereby generating electrical energy, which is then transmitted to the battery 8-1 for storage via the connecting wires 8-2.

[0049] The nonlinear track 5 has protrusions 5-1 on its upper and lower sides. These protrusions 5-1 connect with the grooves 6-3 of the constraint baffles on the front and rear sides, ensuring that the nonlinear track moves along the grooves without contacting the base plate. The back of the nonlinear track 5 is a flat surface with an opening, which connects to one end of a mechanical spring and receives the horizontal force exerted by it.

[0050] The nonlinear shape track 5 has a smooth and continuous curved surface that keeps in contact with the pulley 4. The horizontal force exerted by the mechanical spring is transmitted to the pulley 4 through the curved surface in the form of a nonlinear restoring force. The specific form of the nonlinear restoring force depends on the shape of the curved surface. Any form of restoring force can be achieved by adjusting the shape of the curved surface, thereby achieving any order of stiffness.

[0051] In this embodiment, the mechanical model for the force analysis of the nonlinear restoring force is as follows: Figure 7 As shown. The specific implementation method for arbitrary order stiffness is as follows:

[0052] Let the stiffness of the mechanical springs on both sides be k, and the mass block have a pre-compression Δ when it is in the initial position; with the initial position of the mass block as the origin and the direction of motion as the x-axis, the surface expression of the nonlinear orbit is y(x); the motion of the mass block will cause a change in the compression of the mechanical springs, and the following relationship holds when the mass block is in any position:

[0053] The horizontal elastic force provided by the mechanical springs on both sides is:

[0054] f s =k*(Δ+y(x)) (1)

[0055] The restoring force on the mass block is related to the horizontal force provided by the mechanical spring as follows:

[0056] F NES =2*fs*tanθ (2)

[0057] Combining equations (1) and (2), we get:

[0058] F NES =2k(Δ+y(x))*y′(x) (3)

[0059] Where θ is the angle between the normal at the contact point between the surface of the nonlinear track and the pulley and the y-direction, y′(x) is the derivative of y(x), y′(x) = tanθ; k and Δ are adjusted according to actual needs, for any form of restoring force F NES Any expression of the nonlinear shape orbit can be obtained by solving equation (3) to obtain the surface expression y(x).

[0060] For different working conditions, design the surface shape of the nonlinear orbit according to the following steps:

[0061] 1) Select the order combination of nonlinear restoring forces according to actual needs, and construct the dynamic model and motion equations of the main structure coupled with the nonlinear energy trap device.

[0062] 2) Determine different external excitations based on actual vibration reduction requirements, while considering robustness, and apply external excitations under different changes in the stiffness of the main structure.

[0063] 3) Select a suitable objective function, such as energy dissipation, average displacement, maximum displacement, etc., and optimize the coefficients of each order of the selected nonlinear restoring force through an optimization algorithm to obtain a nonlinear restoring force expression with good control effect; substitute the optimized nonlinear restoring force expression into equation (3) to obtain the surface expression of the nonlinear shape track.

[0064] The mechanical model is described below using a single-degree-of-freedom system model to illustrate how to control seismic motion using the arbitrary-order stiffness characteristics of this invention. Figure 8 As shown. The parameters of the single-degree-of-freedom system are: m1 = 160 kg, c1 = 3.84 N*s / m, k1 = 23040 N / m, which are the main structure mass, damping, and stiffness, respectively. Taking a mass ratio of 0.01, the mass of the mass block is m2 = 1.6 kg.

[0065] Its equation of motion is:

[0066]

[0067]

[0068] Among them, F N(x) is the expression for the nonlinear restoring force.

[0069] Through simple analysis, the combination of first-order linear stiffness and second- and third-order nonlinear stiffness can realize most forms of restoring force. In practical engineering applications, the form of nonlinear restoring force can be designed into a more complex form to achieve better control effect.

[0070] In this embodiment, the nonlinear restoring force is taken as follows:

[0071] F NES =ax + bx 2 +cx 3

[0072] Therefore, four parameters need to be designed for this nonlinear restoring force: the coefficients a, b, and c of each stiffness order, and the damping coefficient c2 of the nonlinear energy trap. Next, an optimization scheme will be designed to find the optimal values ​​for these four parameters.

[0073] The specific parameter optimization scheme is as follows:

[0074] This embodiment considers controlling seismic motion, therefore applying a base harmonic acceleration excitation to the motion system. It also takes into account the wide frequency range of seismic action and the potential stiffness degradation caused by structural failure under seismic action, including minor changes in the main structure's stiffness due to uncertainties during construction.

[0075] The specific considerations mentioned above are as follows:

[0076] 1) The stiffness of the main structure changes to 0.4-1.0 times the original design stiffness;

[0077] 2) The ratio of the frequency of the base harmonic excitation to the natural frequency of the main structure is 0.6-1.4 times;

[0078] For combinations of the above scenarios, the root mean square displacement and maximum displacement of the main structure are used as the objective functions:

[0079]

[0080] For the above optimization process, a suitable optimization algorithm is selected to solve the problem. In this embodiment, a genetic algorithm is used. The final optimized results for each parameter are c2 = 3.24, a = 191.8, b = -16.8, and c = 9.1. That is, the expression for the nonlinear restoring force in this embodiment is:

[0081] F NES =191.8x - 16.8x 2 +9.1x 3

[0082] To demonstrate the superior vibration reduction performance and robustness of this invention, it will be compared with a tuned mass damper that has excellent control performance under a single degree of freedom. The parameter values ​​of the tuned mass damper are obtained according to the optimal parameter design formula proposed by Den Hartog based on the fixed-point theory, specifically c2 = 3.24 and a = 224.7. Since the tuned mass damper is a linear system, its parameters do not contain nonlinear terms b and c.

[0083] This paper compares the vibration control effects of a parametrically designed nonlinear energy trap with arbitrary stiffness and a tuned mass damper on the main structure under a specific earthquake. The root mean square (RMS) displacement of the main structure is used as the evaluation index for vibration reduction, and the RMS at stiffness decay is used as the robustness evaluation index. The displacement response of the main structure after the earthquake input is as follows: Figure 9 As shown, the present invention, by setting a third-order stiffness combination and after certain parameter optimization, has excellent vibration reduction control effect and robustness.

[0084] In this embodiment, excellent vibration reduction is achieved by constructing only a combination of first, second, and third-order stiffnesses. However, the present invention can achieve stiffness effects of any order, and is not limited to the stiffness form of this embodiment. Depending on actual needs, the present invention can be configured with more orders and more complex stiffness forms to achieve even better control performance.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A nonlinear energy trap device capable of harvesting energy of arbitrary stiffness and order, characterized in that, The system includes a mechanical spring unit, a mass block, a friction slide rail, pulleys, a non-linear shape track, constraint baffles, a base plate, and a power storage unit. The mass block has force transmission rods on its left and right sides, with the ends of the rods connected to pulleys. A first sliding connection portion is located in the center of the bottom of the mass block, and first friction portions are located on the left and right sides of the bottom. The friction slide rail is mounted on the base plate. A second sliding connection portion, cooperating with the first sliding connection portion, is located in the center of the top of the friction slide rail, and second friction portions are located on the left and right sides to interact with the first friction portions and form two pairs of friction pairs. There are two pairs of constraint baffles, located on the left and right sides of the mass block. The mass block is fixedly connected to the base plate on both sides and front and back. Non-linear shaped tracks are provided on the left and right sides of the mass block. The curved side of the non-linear shaped track faces the mass block and contacts the pulley, while the flat side is connected to the left or right constraint baffle via a mechanical spring unit. Piezoelectric sheets are attached to the side of the constraint baffle connected to the mechanical spring unit on both sides. A third sliding connection is provided at both the front and rear ends of the non-linear shaped track. A fourth sliding connection is provided on the side of the constraint baffle facing the non-linear shaped track on both sides, cooperating with the third sliding connection. The energy storage unit is electrically connected to the piezoelectric sheet. The first sliding connection of the mass block is a protrusion, and the second sliding connection of the friction slide rail is a groove. The protrusion of the mass block and the groove of the friction slide rail cooperate with each other to limit and guide the movement direction of the mass block. The third sliding connection of the nonlinear shape track is a protrusion, and the fourth sliding connection of the constraint baffles on the front and rear sides is a groove. The protrusions at the front and rear ends of the nonlinear shape track cooperate with the grooves of the constraint baffles on the front and rear sides to limit and guide the movement direction of the nonlinear shape track. The grooves of the constraint baffles on the front and rear sides are at a certain height from the bottom plate so that the nonlinear shape track does not contact the bottom plate during movement. The nonlinear track has a smooth and continuous curved surface that maintains contact with the pulley. The horizontal force exerted by the mechanical spring is transmitted to the pulley through the curved surface in the form of a nonlinear restoring force. The specific form of the nonlinear restoring force depends on the shape of the curved surface. Arbitrary forms of restoring force can be achieved by adjusting the shape of the curved surface, thereby realizing any order of stiffness. The specific method for achieving arbitrary order stiffness is as follows: Assume the stiffness of the mechanical springs on both sides is There is a pre-compression when the mass block is in its initial position. ; With the initial position of the mass block as the origin, the direction of motion is... The surface expression for the axis, nonlinear shape orbit is: The movement of the mass will cause a change in the compression of the mechanical spring. When the mass is in any position, the following relationship holds: The horizontal elastic force provided by the mechanical springs on both sides is: The restoring force on the mass block is related to the horizontal force provided by the mechanical spring as follows: Combining equations (1) and (2), we get: in, It is the angle between the normal at the contact point between the curved surface of the non-linear track and the pulley and the y-direction. for The derivative, ; and Adjustments can be made based on actual needs, for any form of resilience. Any expression of the nonlinear shape orbit can be obtained by solving equation (3). .

2. The nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting according to claim 1, characterized in that, The first friction part of the mass block is made of high-carbon steel, and the second friction part of the friction slide rail is made of semi-metallic friction material. The high-carbon steel and the semi-metallic friction material on the same side interact to form a friction pair, which plays a damping role, so that the mass block continuously dissipates its own energy during the movement, while ensuring the stability of the mass block's movement.

3. A nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting according to claim 1, characterized in that, The mass block and the force transmission rods on both sides are integrally constructed to stably apply the restoring force transmitted by the pulley to the mass block; the length of the force transmission rods is long enough to ensure that the mechanical spring is in a compressed state at the equilibrium position.

4. A nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting according to claim 1, characterized in that, The mechanical spring unit consists of a spring base and multiple mechanical springs evenly distributed on the spring base. One end of each mechanical spring is connected to one side of the plane of the nonlinear shaped track, and the other end is connected to one side of the spring base. The other side of the spring base, which is not connected to the mechanical spring, is in contact with the piezoelectric sheet on the surface of the constraint baffle, and a constantly changing pressure is applied to the piezoelectric sheet to generate electrical energy.

5. A nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting according to claim 1, characterized in that, The two pairs of constraint baffles are perpendicular to each other. Each constraint baffle is fixed to the base plate by bolts, and each constraint baffle has stiffening ribs on its back to ensure that the constraint baffle can stably support the movement of the mechanical spring and the nonlinear shape track.

6. A nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting according to claim 1, characterized in that, The energy storage unit consists of a battery and connecting wires. The battery is electrically connected to a corresponding piezoelectric element through the connecting wires. The piezoelectric element generates electrical energy through the continuous change of pressure and transmits the electrical energy to the battery for storage through the connecting wires.

7. A nonlinear energy trap device capable of achieving arbitrary stiffness and energy harvesting according to claim 1, characterized in that, For different working conditions, design the surface shape of the nonlinear orbit according to the following steps: 1) Select the order combination of nonlinear restoring forces according to actual needs, and construct the dynamic model and motion equations of the main structure coupled with the nonlinear energy trap device; 2) Determine different external excitations based on actual vibration reduction requirements, while considering robustness, and apply external excitations under different changes in the stiffness of the main structure; 3) Select a suitable objective function and optimize the coefficients of each order of the selected nonlinear restoring force through an optimization algorithm to obtain a nonlinear restoring force expression with good control effect; substitute the optimized nonlinear restoring force expression into equation (3) to obtain the surface expression of the nonlinear shape track.

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