Sma bionic honeycomb sandwich structure

Abstract

The application relates to the technical field of anti-seismic design in civil engineering, and discloses an SMA bionic honeycomb sandwich structure, which comprises an outer honeycomb and an inner honeycomb, the wall thickness of the outer honeycomb can be expressed as: lambda L h1 , wherein Lh1 is the side length of the outer honeycomb, L h2 is the side length of the inner honeycomb, and lambda is the wall thickness side length ratio of the honeycomb; the gap 0.5u1 between the outer honeycomb and the inner honeycomb can be expressed as: 0.5u1=L h1 cos 30 DEG - lambda L h1 -L h2 cos 30 DEG, wherein Lh1 is the side length of the outer honeycomb, L h2 is the side length of the inner honeycomb, and lambda is the wall thickness side length ratio of the honeycomb; the gap 0.5u1 between the outer honeycomb and the inner honeycomb can be expressed as: 0.5u1=L h1 cos 30 DEG - lambda L h1 -L h2 cos 30 DEG, the multistage honeycomb sandwich structure can adapt to different levels of earthquake intensity, the honeycomb structure has different stiffness levels while having the geometric large deformation capacity, the embedded solid hexagonal block protection structure is damaged when the displacement is too large, self-resetting after the earthquake is realized, and the super-elasticity of the SMA material has strong self-resetting performance under strong earthquakes.

Description

Technical Field

[0001] This invention relates to the field of seismic design technology in civil engineering, specifically to an SMA biomimetic honeycomb sandwich structure. Background Technology

[0002] In recent years, earthquake-resistant design concepts have evolved from "performance-based earthquake-resistant design" to "post-earthquake recoverability." Devices based on superelastic shape memory alloys (SMAs), with their excellent self-resetting properties, have become one of the main means of achieving post-earthquake recoverability.

[0003] Hyperelastic shape memory alloys (SMAs) are widely used in fields such as biomedicine, mechanical manufacturing, aerospace, and civil engineering. Currently, commonly used shape memory alloys include iron-based, copper-based, and nickel-titanium alloys. Among them, nickel-titanium alloys have the most stable hyperelastic properties. With advantages such as large ultimate strain, self-recovery, material hysteresis energy dissipation, good fatigue resistance, and high corrosion resistance, nickel-titanium SMAs have become an ideal material for constructing recoverable structural systems and are widely used in actuators, dampers, supports, limiters, steel reinforcement in concrete, and vibration damping devices.

[0004] However, the deformation capacity of current SMA (Superficial Motion Acetate) restraint devices is far from meeting the displacement requirements of bridge structures under strong earthquakes. Under strong earthquakes or near-field ground motion, these SMA restraint devices are very likely to be destroyed. Consequently, the bridge will lose its self-resetting ability. Honeycomb structures, composed of hexagonal cells, are the optimal topological structure covering a two-dimensional plane, possessing advantages such as lightweight, high strength, wave absorption, energy absorption, and large deformation capacity. They are used in spacecraft shells, energy-absorbing panels, and dampers. Existing honeycomb structures are prone to failure under large displacements, and their stiffness cannot change with displacement, failing to effectively restrict displacement when subjected to earthquakes of different magnitudes. Excessive compressive displacement leads to structural collapse, while excessive tensile displacement leads to structural fracture; both situations result in structural failure. Based on honeycomb structures, we propose an SMA biomimetic honeycomb sandwich structure. This is proposed for bridge damping devices but can be extended to other structures such as buildings. The large geometric deformation of the honeycomb structure can meet the large displacement requirements of bridge seismic resistance while improving energy dissipation efficiency. Simultaneously, the self-resetting ability of SMA material can provide protection for bridge structures under extremely rare earthquakes. Summary of the Invention

[0005] The purpose of this invention is to provide an SMA biomimetic honeycomb sandwich structure that solves the problem of easy failure of existing honeycomb structures under large displacement conditions, while also providing multi-level stiffness variation and failure prevention design to adapt to different earthquake levels and overloads.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an SMA biomimetic honeycomb sandwich structure, wherein the SMA biomimetic honeycomb sandwich structure includes an outer honeycomb and an inner honeycomb, and the wall thickness of the outer honeycomb can be expressed as:

[0007]

[0008] in The outer honeycomb side length, The inner honeycomb side length, This represents the ratio of the wall thickness to the side length of the honeycomb.

[0009] The gaps between the outer and inner honeycomb It can be expressed by the following formula:

[0010]

[0011] The transformation yields:

[0012]

[0013] Similarly, the wall thickness of the inner honeycomb is:

[0014]

[0015] in According to Equation 4-3, the side length of the solid hexagonal block can be determined. It can be represented as:

[0016]

[0017] Preferably, the deformation of the SMA biomimetic honeycomb sandwich structure includes the geometric nonlinear deformation of the multi-layer honeycomb and the nonlinear deformation of the SMA material.

[0018] Preferably, the SMA biomimetic honeycomb sandwich structure includes an SMA honeycomb panel, with one or more honeycomb structures embedded in each honeycomb, and the innermost layer being a solid hexagonal panel.

[0019] Preferably, the SMA biomimetic honeycomb sandwich structure includes a superelastic SMA sheet, which is cut into a corresponding honeycomb structure using a laser, and the end steel plate and the SMA honeycomb are integrated as a whole.

[0020] This invention provides an SMA biomimetic honeycomb sandwich structure. It has the following beneficial effects:

[0021] (1) The present invention can adapt to different levels of earthquake intensity through a multi-level honeycomb sandwich structure. While utilizing the large geometric deformation capability of the honeycomb structure, it also has different stiffness levels. The embedded solid hexagonal block protects the structure from damage when the displacement is too large, thus achieving self-resetting after the earthquake. The superelasticity of SMA material has strong self-resetting performance under strong earthquakes.

[0022] (2) This invention not only adapts to large deformations, but also has different stiffnesses at different displacement levels, adapting to different seismic requirements. The SMA material ensures that the structure maintains its self-recovery ability when the apparent strain is large, and also ensures that the structure will not completely collapse and fail when the displacement is too large.

[0023] (3) The present invention can continue to work under extremely rare earthquake conditions. Under extremely rare earthquake conditions, the multi-layered honeycomb structure gradually increases the restriction on support displacement. The multi-layered geometric nonlinearity and material nonlinearity jointly consume seismic energy. The self-recovery ability and energy dissipation ability are stronger than those of ordinary honeycomb structures, effectively improving the seismic resistance of bridges. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a single cell of the SMA sandwich honeycomb structure of the present invention;

[0025] Figure 2 This is a single-cell view of the SMA honeycomb structure of the present invention;

[0026] Figure 3 This is a view of the SMA biomimetic honeycomb sandwich structure of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0029] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] like Figure 1-3 As shown, the present invention provides a technical solution: an SMA biomimetic honeycomb sandwich structure, wherein the SMA biomimetic honeycomb sandwich structure includes an outer honeycomb and an inner honeycomb, and the wall thickness of the outer honeycomb can be expressed as:

[0032]

[0033] in The outer honeycomb side length, The inner honeycomb side length, This represents the ratio of the wall thickness to the side length of the honeycomb.

[0034] The gaps between the outer and inner honeycomb It can be expressed by the following formula:

[0035]

[0036] The transformation yields:

[0037]

[0038] Similarly, the wall thickness of the inner honeycomb is:

[0039]

[0040] in According to Equation 4-3, the side length of the solid hexagonal block can be determined. It can be represented as:

[0041]

[0042] The deformation of the SMA biomimetic honeycomb sandwich structure includes the geometric nonlinear deformation of the multi-layer honeycomb and the nonlinear deformation of the SMA material. Analysis was performed using Abaqus software, following a progression from simple to complex, focusing on axial tension / compression and horizontal shear analysis of the unit cell structure.

[0043] The honeycomb wall is simplified as shown in the figure, with a thickness of [missing information] in the local coordinate system. Consider a straight beam of length l. When the honeycomb is subjected to stress, the honeycomb walls deform and displace. In the local coordinate system, point a moves to point b. The displacement vectors of point a along the longitudinal and transverse directions are represented by v(x) and h(x). Based on the assumptions of the Euler-Bernoulli beam theory and the research of Shaw, JA, et al.,

[0044] The cross-section remains perpendicular to the central axis before and after deformation. This means that the transverse normal strain can be neglected when the beam-type member undergoes transverse shear deformation and warping. The surface perpendicular to the beam's central axis before deformation remains planar and perpendicular to the central axis after deformation. Based on these assumptions, the axial strain at the initial coordinates (x, y) is:

[0045]

[0046] Where e(x) is the axial strain function at each point on the central axis. Let be the curvature. The longitudinal and transverse displacement vectors can be expressed as v(x) and h(x):

[0047]

[0048]

[0049] The virtual work contribution at each intersection point in the weak-form equilibrium equation is expressed as:

[0050]

[0051] Where N(x) and M(x) are the resultant forces of the axial force and bending moment of the honeycomb wall, respectively. Let N(x) be the axial strain of the honeycomb wall. N(x) and M(x) can be given by the following equations:

[0052]

[0053] .

[0054] The SMA biomimetic honeycomb sandwich structure includes SMA honeycomb panels, with one or more honeycomb structures embedded in each cell. The innermost layer is a solid hexagonal plate, which limits the maximum displacement that the structure can generate, preventing structural failure due to excessive displacement.

[0055] The SMA biomimetic honeycomb sandwich structure includes a super-elastic SMA sheet, which is cut into a honeycomb structure using laser. The end steel plate and the SMA honeycomb are integrated as a whole.

[0056] In summary, the multi-level honeycomb sandwich structure can adapt to different levels of earthquake intensity. It utilizes the large geometric deformation capacity of the honeycomb structure while having different stiffness levels. The embedded solid hexagonal blocks protect the structure from damage when the displacement is too large, achieving self-resetting after the earthquake. The hyperelastic properties of SMA material have strong self-resetting performance under strong earthquakes.

[0057] Not only can it adapt to large deformations, but it also has different stiffnesses at different displacement levels to meet different seismic requirements. SMA material ensures that the structure maintains its self-recovery ability when the apparent strain is large, and also ensures that the structure will not completely collapse and fail in the event of excessive displacement.

[0058] It can continue to function even under extremely rare earthquake conditions. Under extremely rare earthquake conditions, the multi-layered honeycomb structure gradually increases the restriction on support displacement. The multi-layered geometric nonlinearity and material nonlinearity jointly dissipate seismic energy, resulting in stronger self-recovery and energy dissipation capabilities than ordinary honeycomb structures, effectively improving the seismic resistance of bridges.

[0059] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0060] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An SMA bionic honeycomb sandwich structure, characterized in that: The SMA bionic honeycomb sandwich structure comprises an outer honeycomb and an inner honeycomb, and the wall thickness of the outer honeycomb is represented as: wherein is the outer honeycomb edge length, is the inner honeycomb edge length, is the wall thickness edge length ratio of the honeycomb; The outer cell, inner cell gap is represented by the following formula: The transformation formula is: Similarly, the wall thickness of the inner honeycomb is: wherein ; Side length of solid hexagonal blocks is represented as: The deformation of the SMA bionic honeycomb sandwich structure comprises geometric nonlinear deformation of the multi-layer honeycomb and nonlinear deformation of the SMA material; The SMA bionic honeycomb sandwich structure comprises an SMA honeycomb plate, each honeycomb is embedded with one or more layers of honeycomb structure, and the innermost layer is a solid hexagonal plate; The SMA bionic honeycomb sandwich structure comprises a super-elastic SMA plate, which is cut into a corresponding honeycomb structure by laser, and the end steel plate and the SMA honeycomb are an integral whole.

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