A flexible energy-absorbing structure based on the interaction of magnetic element groups

Abstract

The present invention relates to a flexible energy-absorbing structure based on the interactive motion of a group of magnetic elements. The structure comprises a magnetic particle element structure and an external flexible wrapping membrane. The magnetic particle element structure comprises multiple magnetic particle elements, which are filled within the external flexible wrapping membrane, which is sealed using a hot melt method. Compared with existing technologies, the present invention offers advantages such as lightweight, high impact resistance, extensive design and performance control options, strong environmental adaptability, and excellent self-repair capabilities. It is widely applicable to applications such as aircraft impact-resistant structures and vibration-damping protective structures.

Description

Technical Field

[0001] The present invention relates to the field of energy absorption devices, and in particular to a flexible energy absorption structure based on the interactive motion of a group of magnetic elements. Background Art

[0002] Aerospace, unmanned aerial vehicle (UAV) systems, and other fields share a common need for energy-absorbing structures that can resist impact, absorb and dissipate kinetic energy, and adapt to complex terrain environments. Applications such as spacecraft recovery and landing, and UAV collision avoidance, for example, are crucial. The design goals of these energy-absorbing structures are to effectively absorb impact energy, improve absorption efficiency, and maintain low weight.

[0003] However, current conventional energy-absorbing structure designs primarily focus on structural adjustments, resulting in a relatively single function and a lack of self-repair. They also struggle to balance multiple functions, such as lightweighting, flexibility, energy dissipation, and absorption of external impact energy, and are difficult to adapt to complex environmental changes. For example, patent application CN 115899131 A discloses a bistable flexible energy-absorbing protective structure and its preparation method. The structure comprises two rigid horizontal layers, upper and lower, with a flexible intermediate layer disposed between them. The flexible intermediate layer comprises a trapezoidal self-locking structure, with flexible elastic rods connecting the spaced-apart trapezoidal self-locking structures. The fabrication steps include: printing the upper and lower rigid horizontal layers using a resin material using a 3D printer; preparing an intermediate layer female mold using acrylic sheet to match the flexible intermediate layer composed of the flexible elastic rods and trapezoidal self-locking structure; pouring a silicone rubber mixture into the female mold for curing and forming; and finally bonding the rigid horizontal layer to the cured flexible intermediate layer. This method is simple, reliable, and easy to prepare, but it only provides adequate low-speed impact protection. Under rapid impact, conventional elastic structures are prone to rebound, causing secondary impacts and damage to equipment and components. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a flexible energy-absorbing structure based on the interactive motion of a group of magnetic elements, so as to effectively realize the conversion of impact energy, prevent damage caused by secondary rebound, and protect the safety of equipment and devices under impact loads.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A flexible energy-absorbing structure based on the interactive motion of a group of magnetic elements comprises a magnetic particle element structure and an external flexible wrapping film, wherein the magnetic particle element structure comprises a plurality of magnetic particle elements, the magnetic particle element structure is filled in the external flexible wrapping film, and the external flexible wrapping film is sealed by hot melting.

[0007] Furthermore, the magnetic particle element is a hollow structure.

[0008] Furthermore, the magnetic particle element includes an upper and lower part, and the upper and lower parts have the same shape but opposite magnetization directions.

[0009] Furthermore, the upper and lower parts of the magnetic particle element are stably bonded by magnetic force, and a snap-fit ​​design is used to prevent relative rotation.

[0010] Furthermore, the plurality of magnetic particle elements are attracted to each other and stacked and constrained by the mutual attraction generated by their own magnetic materials, and are arranged in a topological manner such as a grid.

[0011] Furthermore, the mutual attraction between any two of the magnetic particle elements is as follows:

[0012]

[0013] Where, subscripts i and j represent two particles, μ0 is the spatial magnetic permeability, r ij is the relative position vector between magnetic particles i and j, pointing to i, m ir and m jr is the component of the magnetic moment along the relative position vector.

[0014] Furthermore, the plurality of magnetic particle elements are in a densely stacked state, and the contact force exerted on a single magnetic particle element by the surrounding magnetic particle elements is as follows:

[0015] P=2Rwp0

[0016] Where P is the contact force, R is the radius of the magnetic particle, w is the number of magnetic particles, and p0 is the surface stress on the magnetic particles.

[0017] Furthermore, when subjected to an external impact load, the external flexible wrapping membrane constrains the overall deformation of the structure to be within a designed range.

[0018] Furthermore, under an external impact load, the magnetic particle elements convert impact energy into energy for separation of the magnetic particle elements and energy for contact friction and sliding between a plurality of the magnetic particle elements.

[0019] Furthermore, when friction occurs in the magnetic particle element structure, the relationship between the friction force between the plurality of magnetic particle elements and the stress they bear is as follows:

[0020]

[0021] Among them, f is the friction force, α is the function related to the friction sliding surface, σ a is the impact stress, σ R is the normal stress, and p0 is the surface stress on the magnetic particles.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention utilizes the blocking effect induced by the magnetic constraint between magnetic elements and the overall boundary constraint to absorb and dissipate the energy of the external load, generate surface constraint force, and effectively improve the kinetic energy absorption performance of the structure.

[0024] 2. The present invention utilizes the reshapeable magnetic field between magnetic elements to construct mutual dynamic constraints, realize the fluid plasticity of the structure and its adaptability to various dynamic loads, avoid damage caused by secondary impact caused by rebound, and achieve the purpose of protecting the onboard equipment.

[0025] 3. The present invention only uses common magnetic materials and flexible outer films. The magnetic particles can be directly manufactured by 3D printing. They are composed of two parts with the same structure and opposite magnetization directions. The two parts are stably bonded due to magnetic force, which facilitates mass production and application.

[0026] 4. The present invention is based on the characteristics of magnetic potential interaction and exhibits overall flexibility. After impact, the main change occurs in the shape, and the shape can be restored to achieve the purpose of reusing the energy-absorbing structure and saving resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention;

[0028] Figure 2 This is a single-body perspective view of the magnetic unit energy absorption structure.

[0029] Figure numerals: 1. Magnetic particle element structure; 2. External flexible wrapping film. DETAILED DESCRIPTION

[0030] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0031] This embodiment provides a flexible energy-absorbing structure based on the interaction of magnetic body group motion, such as Figure 1 As shown, the structure comprises a magnetic granular element structure 1 and an external flexible wrapping film 2. The magnetic granular element structure 1 comprises multiple magnetic granular elements, which are filled within the external flexible wrapping film 2, which is sealed using a hot melt method. The external flexible wrapping film 2 imposes flexible constraints on the magnetic granular elements, further enhancing energy dissipation between the elements and preventing some elements from escaping under high-speed impacts, thereby achieving adaptive structural morphology.

[0032] like Figure 2As shown, the magnetic particle element is composed of two parts with identical structures but opposite magnetization directions. The hollow structure is stably bonded by magnetic force, and a snap-fit ​​design prevents relative rotation, making it difficult to separate under external impact. The magnetic particle element can be directly manufactured through 3D printing. If it separates due to impact, it will need to overcome the close-range magnetic attraction to further absorb the dissipated energy.

[0033] Multiple magnetic particle elements rely on the mutual attraction generated by their own magnetic materials to attract each other and form stacking constraints, and are arranged in a grid topology.

[0034] The mutual attraction between any two magnetic particle elements is as follows:

[0035]

[0036] Where, subscripts i and j represent two particles, μ0 is the spatial magnetic permeability, r ij is the relative position vector between magnetic particles i and j, pointing to i, m ir and m jr is the component of the magnetic moment along the relative position vector.

[0037] It can be seen that the attraction of magnetic materials will decay with the distance at a high power. The hollow structure greatly reduces the mass of magnetic particles while retaining most of the magnetic force. The average density of the finished product is 2.12g / mm 3 , which is close to the density of carbon fiber resin commonly used in aircraft.

[0038] When multiple magnetic particle elements are densely stacked, the contact force exerted on a single magnetic particle element by the surrounding magnetic particle elements is as follows:

[0039] P=2Rwp0

[0040] Where P is the contact force, R is the radius of the magnetic particle, w is the number of magnetic particles, and p0 is the surface stress on the magnetic particles.

[0041] When a magnetic particle element is subjected to an external impact load, the impact energy is converted into the energy of separation of the magnetic particle element and the energy of contact friction and sliding between the magnetic particle elements. The internal magnetic particle element structure 1 will undergo motion modes such as friction, extrusion, collision, and separation. The energy of the external load is absorbed and dissipated during these motions. First, friction will convert the impact energy into frictional heat energy caused by the relative displacement of the particle surface. At the same time, relative extrusion will occur between the magnetic particles. This relative displacement between the particles will bring about a change in magnetic potential, thereby converting part of the impact energy into magnetic potential energy dissipation. Furthermore, when a large displacement occurs between the particles, it will cause the movement of the magnetic particles, converting part of the impact energy into kinetic energy, causing separation between the magnetic particles. At the same time, in order to overcome the mutual attraction of magnetic forces at close range, separation requires a large amount of energy. In addition, if the upper and lower parts of the magnetic particle unit are separated, further energy will be absorbed.

[0042] When friction occurs in the magnetic particle element structure 1, the relationship between the friction force between the magnetic particle elements and the stress they bear is as follows:

[0043]

[0044] Among them, α is a function related to the friction sliding surface, σ a is the impact stress, σ R is the normal stress, and p0 is the surface stress on the magnetic particles.

[0045] The constraint of the flexible wrapping membrane 2 will limit the overall deformation within the design range, and at the same time generate surface constraint force. By combining the magnetic constraint between the elements and the blocking effect induced by the overall boundary constraint, such a blocking effect will further hinder the relative movement inside the magnetic particle unit, thereby further improving the energy absorption effect.

[0046] The flexible energy-absorbing structure based on the interactive motion of a group of magnetic elements exhibits flow plasticity on a macroscopic scale when subjected to impact loads. The elements adjust their relative positions and utilize the reshapeable magnetic field to construct dynamic constraints on each other, thereby achieving flexible flow plasticity of the structural system, making it easy to match various dynamic loads, achieve adaptability to dynamic loads and service environments, and be reusable. At the same time, this flow plasticity also makes it easy to switch forms in time when impacted to adapt to complex and changing environmental conditions. In addition, the performance of plastic flow can suppress the rebound effect of the system when impacted, thereby avoiding damage to the system caused by secondary impacts caused by elastic rebound, and achieving the purpose of protecting the onboard equipment.

[0047] Density is an important parameter in the design of impact-resistant structures. Impact-resistant design schemes of different densities directly determine whether related equipment can be carried. The magnetic particle element manufactured in this embodiment has a hollow design and reduces the density to approximately the same as that of carbon fiber without sacrificing its own magnetic attraction to a large extent, which is convenient for carrying when used in aerospace and other fields.

[0048] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A flexible energy-absorbing structure based on the interaction of magnetic element groups, characterized in that: The invention comprises a magnetic particle element structure (1) and an external flexible wrapping film (2), wherein the magnetic particle element structure (1) comprises a plurality of magnetic particle elements, the magnetic particle element structure (1) is filled in the external flexible wrapping film (2), the external flexible wrapping film (2) is sealed by hot melting, the magnetic particle element is a hollow structure, comprising an upper and lower part, the upper and lower parts have the same shape but opposite magnetization directions, the upper and lower parts are stably bonded by magnetic force, and a snap-fit ​​design is used to prevent relative rotation, the plurality of magnetic particle elements are attracted to each other and stacked and constrained by the mutual attraction generated by their own magnetic materials, presenting a grid topological arrangement, when subjected to an external impact load, the external flexible wrapping film (2) constrains the overall deformation of the structure within a design range, the magnetic particle element converts the impact energy into the kinetic energy of the magnetic particle element, the frictional heat energy between the magnetic particle elements and the magnetic potential energy between the magnetic particle elements under the external impact load, and the mutual attraction between any two magnetic particle elements is as follows: Where, For mutual attraction, subscript and Represents two particle elements, is the spatial magnetic permeability, Magnetic particle element Magnetic particle elements The relative position vector between Magnetic particle element The magnetic moment of Magnetic particle element The magnetic moment of and is the component of the magnetic moment along the relative position vector.

2. The flexible energy-absorbing structure based on the interaction of magnetic body group motion according to claim 1 is characterized in that: The plurality of magnetic particle elements are in a densely stacked state, and the contact force exerted on a single magnetic particle element by the surrounding magnetic particle elements is as follows: Where, is the contact force, is the radius of the magnetic particle element, is the number of magnetic particle elements, is the surface stress on the magnetic particle element.

3. The flexible energy-absorbing structure based on the interaction of magnetic element groups according to claim 1 is characterized in that: When the magnetic particle element structure (1) is subjected to friction, the relationship between the friction force between the magnetic particle elements and the stress they bear is as follows: in, is the friction force, is a function related to the friction slip surface, is the impact stress, is the normal stress, is the surface stress on the magnetic particle element.

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