Stiffness-variable metamaterial and working method thereof

Abstract

The application provides a variable stiffness metamaterial and a working method thereof, comprising a bistable unit and an active control unit, the bistable unit is composed of an elastic structure, the elastic structure can be converted between two stable geometric configurations under different trigger conditions, and has different stiffness characteristics in the stable state, and the active control unit can drive the bistable unit to convert between the two stable geometric configurations, the variable stiffness metamaterial provided by the application can quickly realize the state conversion of the bistable unit through the accurate driving of the active control unit, so that the rapid adjustment of the stiffness of the material is realized, and some time-sensitive application requirements, such as automobile collision protection, mechanical vibration control and the like, are met.

Description

Technical Field

[0001] This application relates to the field of metamaterials technology, and in particular to a variable stiffness metamaterial and its working method. Background Technology

[0002] In many engineering and technological applications, there are diverse requirements for the stiffness properties of materials. The stiffness of traditional materials is usually fixed, which presents significant limitations in scenarios where structural performance needs to be flexibly adjusted according to different operating conditions. For example, in aerospace structures, the stiffness requirements vary depending on the flight phase (such as takeoff, cruise, and landing); in automotive crash safety design, materials are expected to maintain a certain degree of flexibility during normal driving to provide comfort, while rapidly increasing stiffness at the moment of impact to provide better protection; in the biomedical field, materials implanted in the human body sometimes need to adjust their stiffness according to the body's motion and stress conditions to achieve better adaptability and safety. Existing variable stiffness materials mostly employ passive adjustment methods, such as changing the material's stiffness through environmental factors like temperature and humidity. However, these methods are insufficient in terms of adjustment speed, range, and precision, and lack active control capabilities.

[0003] Therefore, there is a need to develop a new type of metamaterial with actively adjustable stiffness and superior performance. Summary of the Invention

[0004] In view of this, the present invention provides a variable stiffness metamaterial and its working method to overcome the shortcomings of existing variable stiffness materials, such as slow adjustment speed, narrow range, low precision and lack of active control capability, so as to achieve fast, accurate, wide-range and active control of material stiffness to meet the complex and ever-changing engineering and application needs in different fields.

[0005] To solve the above problems, this application adopts the following technical solution:

[0006] One of the objectives of this application is to provide a variable stiffness metamaterial, comprising:

[0007] A bistable element, wherein the bistable element is composed of an elastic structure that can switch between two stable geometric configurations under different triggering conditions and has different stiffness characteristics in the stable state; and

[0008] An active control unit is connected to the bistable unit and can drive the bistable unit to switch between two stable geometric configurations.

[0009] In some embodiments, the elastic structure includes a pre-deformed thin plate, a rod structure, or a micro / nano structure.

[0010] In some embodiments, the active control unit includes a sensor, a controller, and a driver. The sensor is used to sense external environmental information or receive external control commands. The controller generates a drive signal based on the external environmental information or external commands fed back by the sensor. The driver drives the state transition of the bistable unit based on the drive signal.

[0011] In some embodiments, the external environment information includes stress or strain or temperature or electric or magnetic field.

[0012] In some embodiments, the actuator is a drive device based on electromagnetic, piezoelectric, shape memory alloy, electrostatic hydraulic, or other effects.

[0013] In some embodiments, a matrix material is also included to support and carry the bistable unit.

[0014] In some embodiments, the matrix material includes polymers, metals, ceramics, or composite materials.

[0015] A second objective of this application is to provide a method for working the aforementioned variable stiffness metamaterial, comprising the following steps:

[0016] The active control unit drives the bistable unit to switch between two stable geometric configurations based on external environmental information or external control commands, and the bistable unit has different stiffness characteristics in the stable state.

[0017] The present application adopts the above technical solution, and its beneficial effects are as follows:

[0018] The variable stiffness metamaterial and its working method provided in this application include a bistable unit and an active control unit. The bistable unit is composed of an elastic structure, which can switch between two stable geometric configurations under different triggering conditions and has different stiffness characteristics in the stable state. The active control unit can drive the bistable unit to switch between the two stable geometric configurations. The variable stiffness metamaterial provided in this application can quickly realize the state transition of the bistable unit through the precise drive of the active control unit, thereby realizing the rapid adjustment of material stiffness and meeting some time-sensitive application requirements, such as automotive collision protection and mechanical vibration control.

[0019] The variable stiffness metamaterial and its working method provided in this application include an active control unit comprising a sensor, a controller, and a driver. The sensor is used to sense external environmental information or receive external control commands. The controller generates a drive signal based on the external environmental information or external commands fed back by the sensor. The driver drives the state transition of the bistable unit according to the drive signal. This application utilizes the precise feedback of the sensor and the intelligent algorithm of the controller to accurately control the change in material stiffness. It can adjust the stiffness to the required precise value according to different working conditions and requirements, thereby improving the adaptability and performance of the material under various complex working conditions.

[0020] The variable stiffness metamaterial and its working method provided in this application can achieve a wide range of stiffness adjustment because the bistable unit has significantly different stiffness characteristics under different stable states. It can achieve a leap from a relatively soft to a relatively stiff state and is suitable for a variety of application scenarios from flexible structures to rigid structures.

[0021] The variable stiffness metamaterial and its working method provided in this application can actively adjust the stiffness of the material according to real-time changes in the external environment or active instructions from the user, rather than relying on passive environmental factors. This greatly expands the application flexibility and applicability of the material and can be used in various occasions where dynamic adjustment of structural performance is required. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the rigid support structure in the bistable unit of the present invention;

[0024] Figure 2 This is a schematic diagram of the elastic structure (for laser cutting) in the bistable unit of the present invention;

[0025] Figure 3 This is a schematic diagram of the first steady state of the metamaterial unit cell of the present invention;

[0026] Figure 4 This is a schematic diagram of the second steady state of the metamaterial unit cell of the present invention;

[0027] Figure 5 This is a schematic diagram of the first steady state of the metamaterial unit cell in unidirectional (x-direction) series connection.

[0028] Figure 6This is a schematic diagram of the second steady state of the metamaterial unit cell in unidirectional (x-direction) series connection.

[0029] Figure 7 This is a schematic diagram of the bidirectional (x, y direction) tandem structure of the metamaterial unit cell of the present invention;

[0030] Figure 8 This is a schematic diagram of the three-dimensional (x, y, z) tandem structure of the metamaterial unit cell of the present invention. Detailed Implementation

[0031] The embodiments of this application are described in detail below. Examples of these 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 this application, and should not be construed as limiting this application.

[0032] In the description of this application, it should be understood that the terms "upper", "lower", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments.

[0035] Please see Figure 1 and Figure 2 This is a schematic diagram of the structure of the variable stiffness metamaterial provided in the embodiments of this application, including a bistable element 100 and an active control unit 200. The technical solution for its implementation is described in detail below.

[0036] In this embodiment, the bistable element 100 can switch between two stable geometric configurations under different triggering conditions, and has different stiffness characteristics in the stable state, such as... Figure 1 State A is one of the stable geometric configurations, and state B is another stable geometric configuration. The system transitions between state A and state B under different triggering conditions, and has different stiffness characteristics in state A and state B.

[0037] In this embodiment, the active control unit 200 is connected to the bistable unit 100, and the active control unit 200 can drive the bistable unit 100 to switch between two stable geometric configurations.

[0038] Please see Figure 3 The bistable unit 100 is composed of an elastic structure 110, which can switch between two stable geometric configurations under different triggering conditions and has different stiffness characteristics in the stable state, such as... Figure 4 The middle part is a schematic diagram of the rigid support structure 120 in the stable state of the bistable unit.

[0039] It should be noted that the bistable unit 100 is composed of elastic structures with two stable geometric configurations, capable of switching between these two stable states under different triggering conditions. This bistable characteristic is the basis for realizing changes in material stiffness; by altering the state of the bistable unit, a significant change in the overall stiffness of the material can be achieved.

[0040] Please see Figures 5 to 8 The bistable element 100 can take many forms, such as by elastic members of a specific shape (e.g., thin plates, rod structures or micro / nano structures with pre-deformation), which can transform from one stable state to another under stress or other external excitation, and have different stiffness characteristics in the stable state.

[0041] It is understood that the variable stiffness metamaterial provided in this embodiment has significantly different stiffness characteristics of bistable units under different stable states. Therefore, the metamaterial of the present invention can achieve a wide range of stiffness adjustment, and can achieve a leap from a relatively soft to a relatively stiff state. It is suitable for a variety of application scenarios from flexible structures to rigid structures and can achieve a wide range of adjustment.

[0042] The active control unit 200 is connected to the bistable unit 100, and the active control unit 200 can drive the bistable unit 100 to switch between two stable geometric configurations.

[0043] In this embodiment, the active control unit 200 includes a sensor, a controller, and a driver. The sensor is used to sense external environmental information (such as stress, strain, temperature, electric field, magnetic field, etc.) or receive external control commands. The controller determines the driving signal for the bistable unit based on the information fed back by the sensor or the external command through a preset algorithm. The driver is responsible for driving the state transition of the bistable unit 100 according to the driving signal.

[0044] Specifically, the actuator can be a drive device based on electromagnetic, piezoelectric, shape memory alloy, electrostatic (hydraulic) or other effects, and can be selected and designed according to different application scenarios and requirements to achieve fast and accurate driving of bistable units.

[0045] It is understood that the variable stiffness metamaterial provided in this embodiment can actively adjust the stiffness of the material according to real-time changes in the external environment or active commands from the user, rather than relying on passive environmental factors. This greatly expands the application flexibility and applicability of the material and can be used in various occasions where dynamic adjustment of structural performance is required.

[0046] In this embodiment, the variable stiffness metamaterial also includes a matrix material. The matrix material, as the medium supporting and bearing the bistable units, plays a role in protecting and connecting the bistable units, while also having a certain impact on the overall performance of the material.

[0047] Furthermore, the matrix material can be a polymer, metal, ceramic, or composite material. The appropriate matrix material is selected according to the specific application requirements to ensure its compatibility and synergistic working ability with the bistable unit.

[0048] For example, the matrix material can be carbon fiber, Kevlar, glass fiber, aluminum alloy, 3D printed metal, PLA, ABS, etc.

[0049] This application also provides a method for operating a variable stiffness metamaterial, comprising the following steps: the active control unit 200 can drive the bistable unit 100 to switch between two stable geometric configurations according to external environmental information or external control commands, and has different stiffness characteristics in the stable state.

[0050] The variable stiffness metamaterial and its working method provided in the above embodiments of this application consist of a bistable element, an active control unit, and a matrix material. The bistable element is the core, possessing two stable geometric configurations that can switch states under different triggering conditions, laying the foundation for stiffness changes. The active control unit includes sensors, a controller, and an actuator. The sensors perceive external environmental information or receive commands, and the controller controls the actuator according to a preset algorithm. The actuator drives the state transition of the bistable element. The matrix material is used to support and connect the bistable element. This metamaterial overcomes the shortcomings of existing variable stiffness materials, such as slow adjustment speed, narrow range, low precision, and lack of active control capabilities. It enables rapid, accurate, wide-range, and active adjustment of material stiffness, applicable to numerous fields including active healthcare devices, aerospace, automotive industry, machinery manufacturing, construction engineering, biomedicine, and smart structures. It has diverse application examples in different fields, such as different flight stages of airfoils in aerospace, state adjustment of bumpers and frames during driving and collisions in the automotive industry, and adaptation of implanted structures to human activity in biomedicine. It provides innovative solutions for dynamic adjustment of structural performance in various fields, demonstrating broad application prospects and significant practical value.

[0051] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A variable stiffness metamaterial, characterized in that, include: A bistable unit, which is composed of an elastic structure that can switch between two stable geometric configurations under different triggering conditions and has different stiffness characteristics in the stable state; and An active control unit is connected to the bistable unit and can drive the bistable unit to switch between two stable geometric configurations; The active control unit includes a sensor, a controller, and a driver. The sensor is used to sense external environmental information or receive external control commands. The controller generates a drive signal based on the external environmental information or external commands fed back by the sensor. The driver drives the state transition of the bistable unit based on the drive signal. The external environmental information includes stress or strain, temperature, electric field, or magnetic field.

2. The variable stiffness metamaterial as described in claim 1, characterized in that, The elastic structure includes pre-deformed thin plates, rod structures, or micro / nano structures.

3. The variable stiffness metamaterial as described in claim 1, characterized in that, The actuator is a drive device based on electromagnetic, piezoelectric, shape memory alloy, electrostatic hydraulic or other effects.

4. The variable stiffness metamaterial as described in claim 1, characterized in that, It also includes a matrix material used to support and bear the bistable unit.

5. The variable stiffness metamaterial as described in claim 4, characterized in that, The matrix material includes polymers, metals, ceramics, or composite materials.

6. A method for operating a variable stiffness metamaterial as described in claim 1, characterized in that, Includes the following steps: The active control unit drives the bistable unit to switch between two stable geometric configurations based on external environmental information or external control commands, and the bistable unit has different stiffness characteristics in the stable state.

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