A composite material structure with adaptive stiffness under different stress rates

Abstract

The present invention discloses a composite material structure with adaptive stiffness under different stress rates, comprising two side plates and m elastic units arrayed between the two side plates; the elastic unit comprises two composite beams; the composite beam comprises a first elastic beam and a second elastic beam whose side walls are glued to each other, and the strain rate dependence of the first elastic beam is higher than that of the second elastic beam. The present invention combines the performance characteristics of the composite beams and arranges them in an array to achieve free bending of the elastic units without contacting each other at low stress rates, and the structural stiffness is low, so as to absorb the energy in the collision and play a protective role. However, at high stress rates, the two composite beams of the elastic unit will bend and contact, and the structural stiffness will be enhanced locally or as a whole, playing a supporting role and avoiding structural damage caused by a surge in stress in a short period of time.

Description

Technical Field

[0001] The present invention relates to the field of metamaterial structures, and in particular to a composite material structure with adaptive stiffness under different stress rates. Background Art

[0002] In recent years, metamaterial structures have developed rapidly. Metamaterials are defined as artificial composite structures or composite materials with extraordinary physical properties that natural materials do not have. Metamaterials have superior properties and performances that are different from traditional materials. In recent years, they have received increasing attention for their potential applications in sound absorption, optical components, thermal insulation, semiconductor devices, electromagnetic devices, antenna applications, and wireless communications.

[0003] In addition, the large, reversible, and nonlinear deformations exhibited by flexible metamaterials provide fertile soil for cultivating unique functionalities. On the other hand, flexible mechanical metamaterials share multiple organic intersections with other current research fields, including soft robotics and flexible electronics. Therefore, they have received the most attention in the past few years.

[0004] The structural stiffness of materials is widely used in safety protection equipment. High stiffness is more conducive to bearing loads, and low stiffness is more conducive to absorbing energy in collisions. However, the stiffness characteristics of traditional safety protection equipment are usually fixed, which may be limited when facing the needs of multiple functional tasks in complex environments. Therefore, an adaptive structure with variable stiffness under different working conditions is designed, which can be applied to automobiles, aerospace and other fields.

[0005] However, there are few reports on systematic methods for designing units with variable stiffness. Applying flexible metamaterials in variable stiffness structures is a new idea. Compared with other methods, the advantage of this method is that variable stiffness is achieved by utilizing the performance characteristics of composite materials. The designed composite material has a simple structure, low cost and transportation cost, and is more widely applicable. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a composite material structure with adaptive stiffness under different stress rates in view of the defects involved in the background technology. At low strain rates, the composite material units in the structure do not contact each other and are free to bend. The structure is soft to absorb the energy in the collision and play a protective role. At high strain rates, the composite material units in the structure bend and contact each other, increasing the structural stiffness, playing a supporting role, and avoiding structural damage caused by sudden stress changes.

[0007] The present invention adopts the following technical solutions to solve the above technical problems:

[0008] A composite material structure with adaptive stiffness under different stress rates comprises a first side plate, a second side plate and m elastic units, where m is a natural number greater than or equal to 4;

[0009] The elastic unit comprises a first composite beam and a second composite beam;

[0010] The first composite beam and the second composite beam are rectangular parallelepipeds with the same structure, and both include a first elastic beam and a second elastic beam, wherein the first elastic beam and the second elastic beam are rectangular parallelepipeds with the same structure, and both include two end walls and first to fourth side walls which are vertically fixedly connected in sequence from head to tail, and the strain rate dependence of the first elastic beam is higher than that of the second elastic beam; the third side wall of the first elastic beam is glued to the first side wall of the second elastic beam;

[0011] The first composite beam and the second composite beam in the elastic unit are arranged in parallel, wherein the first elastic beam of the first composite beam and the first elastic beam of the second composite beam are located between the second elastic beam of the first composite beam and the second elastic beam of the second composite beam, the second side wall of the first elastic beam in the first composite beam and the second side wall of the first elastic beam in the second composite beam are coplanar; the distance between the first elastic beam of the first composite beam and the first elastic beam of the second composite beam is less than twice the maximum inward deformation of the first composite beam;

[0012] The m elastic unit arrays are arranged between the first side plate and the second side plate, each having one end vertically fixed to the first side plate and the other end vertically fixed to the second side plate; the distance between the coplanar elastic units is greater than twice the maximum outward variable of the first composite beam in the elastic unit.

[0013] As a further optimization solution of the composite material structure with adaptive stiffness under different stress rates of the present invention, the elastic unit and the first side plate and the second side plate are fixedly connected by gluing.

[0014] As a further optimization solution of the composite material structure with adaptive stiffness under different stress rates of the present invention, the first side plate and the second side plate are both made of plastic or rubber.

[0015] Under quasi-static conditions, the second elastic beam is stiffer than the first elastic beam. When subjected to sufficiently high compressive forces, the first and second composite beams will predictably bend to the left or right, depending on the applied strain rate. Due to the higher stiffness of the second elastic beam, the dual elastic beam will buckle toward the second elastic beam when slowly loaded during compression. At high strain rates, the stiffness of the first elastic beam may exceed that of the second elastic beam, causing the dual beam to bend toward the first elastic beam.

[0016] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0017] 1. Compared with the existing technology, the flexible metamaterial is applied to the variable stiffness structure. The designed composite beam has a simple structure, low construction and transportation costs, wider practicability, and further realizes the lightweight structure, saves the internal layout space of the structure, makes the stiffness variable and the layout reasonable;

[0018] 2. Through array arrangement, the composite beams can bend freely without contacting each other at low stress rates, and the structure is soft to absorb the energy in the collision and play a protective role. However, at high stress rates, they will bend and contact. Through the bending contact of the two composite beams in the elastic unit, the structural stiffness can be enhanced locally or as a whole, playing a supporting role and avoiding structural damage caused by a surge in stress in a short period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 It is a structural schematic diagram of the composite elastic beam in the present invention;

[0021] Figure 3 It is a schematic diagram of the effect of the structure of the present invention under low rate strain;

[0022] Figure 4 It is a schematic diagram of the effect of the structure of the present invention under high rate strain.

[0023] In the figure, 1-first side plate, 2-first composite elastic beam, 3-second elastic beam, 4-first elastic beam. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings:

[0025] The present invention can be implemented in many different forms and should not be considered to be limited to the embodiments described herein. On the contrary, these embodiments are provided to make this disclosure thorough and complete, and will fully express the scope of the present invention to those skilled in the art. In the accompanying drawings, components are enlarged for clarity.

[0026] It should be understood that although the terms first, second, third, etc. can be used here to describe various elements, components and / or parts, these elements, components and / or parts are not limited by these terms. These terms are only used to distinguish elements, components and / or parts from each other. Therefore, the first element, component and / or part discussed below can become the second element, component or part without departing from the teaching of the present invention.

[0027] like Figure 1As shown, the present invention discloses a composite material structure with adaptive stiffness under different stress rates, comprising a first side plate, a second side plate and m elastic units, where m is a natural number greater than or equal to 4;

[0028] The elastic unit comprises a first composite beam and a second composite beam;

[0029] like Figure 2 As shown, the first composite beam and the second composite beam are rectangular parallelepipeds with the same structure, and both include a first elastic beam and a second elastic beam, wherein the first elastic beam and the second elastic beam are rectangular parallelepipeds with the same structure, and both include two end walls and first to fourth side walls that are vertically fixedly connected head to tail in sequence, and the strain rate dependence of the first elastic beam is higher than that of the second elastic beam; the third side wall of the first elastic beam is glued to the first side wall of the second elastic beam;

[0030] The first composite beam and the second composite beam in the elastic unit are arranged in parallel, wherein the first elastic beam of the first composite beam and the first elastic beam of the second composite beam are located between the second elastic beam of the first composite beam and the second elastic beam of the second composite beam, the second side wall of the first elastic beam in the first composite beam and the second side wall of the first elastic beam in the second composite beam are coplanar; the distance between the first elastic beam of the first composite beam and the first elastic beam of the second composite beam is less than twice the maximum inward deformation of the first composite beam;

[0031] The m elastic unit arrays are arranged between the first side plate and the second side plate, each having one end vertically fixed to the first side plate and the other end vertically fixed to the second side plate; the distance between the coplanar elastic units is greater than twice the maximum outward variable of the first composite beam in the elastic unit.

[0032] As a further optimization solution of the composite material structure with adaptive stiffness under different stress rates of the present invention, the elastic unit and the first side plate and the second side plate are fixedly connected by gluing.

[0033] As a further optimization solution of the composite material structure with adaptive stiffness under different stress rates of the present invention, the first side plate and the second side plate are both made of plastic or rubber.

[0034] Under quasi-static conditions, the second elastic beam is stiffer than the first elastic beam. When subjected to sufficiently high compressive forces, the first and second composite beams will predictably bend to the left or right, depending on the applied strain rate. Due to the higher stiffness of the second elastic beam, the dual elastic beam will buckle toward the second elastic beam when slowly loaded during compression. At high strain rates, the stiffness of the first elastic beam may exceed that of the second elastic beam, causing the dual beam to bend toward the first elastic beam.

[0035] When the present invention is subjected to a frontal collision, the impact generated by the collision is transmitted to the elastic unit, and the elastic unit generates a bending deformation to absorb the collision energy. When the stress rate is low, the elastic units are free to bend without contacting each other, such as Figure 3 As shown in , the structural stiffness is low at this time, so it can absorb the energy in the collision and play a protective role. At high stress rates, the two composite beams in the elastic unit will bend and contact each other, as shown in Figure 4 As shown. Through the bending contact of multiple groups of composite material units, the structural stiffness can be enhanced locally or as a whole, playing a supporting role and avoiding structural damage caused by a surge in stress in a short period of time.

[0036] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0037] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite material structure with adaptive stiffness at different stress rates, characterized in that: It comprises a first side plate, a second side plate and m elastic units, where m is a natural number greater than or equal to 4; The elastic unit comprises a first composite beam and a second composite beam; The first composite beam and the second composite beam are rectangular parallelepipeds with the same structure, and both include a first elastic beam and a second elastic beam, wherein the first elastic beam and the second elastic beam are rectangular parallelepipeds with the same structure, and both include two end walls and first to fourth side walls which are vertically fixedly connected in sequence from head to tail, and the strain rate dependence of the first elastic beam is higher than that of the second elastic beam; the third side wall of the first elastic beam is glued to the first side wall of the second elastic beam; The first composite beam and the second composite beam in the elastic unit are arranged in parallel, wherein the first elastic beam of the first composite beam and the first elastic beam of the second composite beam are located between the second elastic beam of the first composite beam and the second elastic beam of the second composite beam, the second side wall of the first elastic beam in the first composite beam and the second side wall of the first elastic beam in the second composite beam are coplanar; the distance between the first elastic beam of the first composite beam and the first elastic beam of the second composite beam is less than twice the maximum inward deformation of the first composite beam; The m elastic unit arrays are arranged between the first side plate and the second side plate, each having one end vertically fixed to the first side plate and the other end vertically fixed to the second side plate; the distance between the coplanar elastic units is greater than twice the maximum outward variable of the first composite beam in the elastic unit.

2. The composite material structure with adaptive stiffness under different stress rates according to claim 1, characterized in that: The elastic unit and the first side plate and the second side plate are fixedly connected by gluing.

3. The composite material structure with adaptive stiffness under different stress rates according to claim 1, characterized in that: The first side plate and the second side plate are both made of plastic or rubber.

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