Composite material for regulating and controlling pre-tightening force based on shape memory behavior and regulating and controlling method thereof

Abstract

The invention discloses a composite material for regulating and controlling pre-tightening force based on shape memory behaviors and a regulating and controlling method of the composite material. The composite material comprises a superelastic foam layer and a shape memory porous structure layer which are overlapped layer by layer or alternately overlapped, the material of the shape memory porous structure layer adopted by the composite material has the characteristics of programmability, intelligent regulation and control performance and the like, regulation and control of the pre-tightening state between assemblies can be achieved through compounding of the shape memory porous structure layer and the hyperelastic foam layer, the composite material is used for replacing a traditional hyperelastic porous foam layer, and the composite material has the advantages of being simple in structure and convenient to use. On the premise that original protection and pre-tightening effects are guaranteed, the problem that the pre-tightening state changes due to the external environment in the service process can be solved, the tedious step that after the pre-tightening state changes, the pre-tightening state is regulated and controlled by disassembling an assembly body is avoided, and a more intelligent, more convenient and more controllable regulation and control mode is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of shape memory materials, and in particular to a composite material for regulating preload based on shape memory behavior and a regulation method thereof. Background Art

[0002] In the packaging structure of special equipment, superelastic foam is usually used to connect the packaging contents and the protective shell. The superelastic porous foam plays the role of pre-tightening the internal and external structures on the one hand, absorbing energy and reducing vibration on the other hand, which is used to prevent the packaging structure from being damaged under the action of external loads, and regulating the gap changes between the contents and the protective shell caused by external loads and environmental changes. In actual application, the external environment inevitably changes. For example, when the temperature changes, the gap between the assembly structure changes due to the different thermal expansion coefficients of the contents and the shell, resulting in a change in the pre-tightening state, thereby reducing the protection capability under vibration or impact loads, causing damage to the contents under external loads.

[0003] In order to solve the above-mentioned problem of change in preload state, it is necessary to develop a composite material that regulates preload force based on shape memory behavior and a regulation method thereof to solve the above-mentioned problem. Summary of the invention

[0004] The purpose of the present invention is to design a composite material and a control method thereof for regulating preload based on shape memory behavior in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions: A composite material for regulating preload based on shape memory behavior, comprising a superelastic foam layer and a shape memory porous structure layer stacked layer by layer or alternately stacked.

[0006] Furthermore, the shape memory porous structure layer activates the shape memory effect through external stimulation, and generates a driving force through the recovery behavior to drive the deformation of the super elastic foam layer.

[0007] Preferably, the external excitation in the shape memory porous structure layer is at least one of thermal excitation, magnetic excitation, optical excitation and electrical excitation.

[0008] The method for regulating a composite material for regulating preload based on shape memory behavior comprises the following steps: (1) Design the size and microstructure of the composite material based on the gap size and preload requirements of the assembly; (2) Shape memory programming of composite materials to store programmed deformation; (3) Assembling the pre-deformed composite material into the assembly and applying the preload force according to the actual requirements of the assembly; (4) By applying the excitation conditions of shape memory behavior, the shape memory porous structure layer programmed in the composite material is prompted to recover. The driving force generated by the recovery drives the deformation of the superelastic foam layer, thereby realizing the regulation of the preload force; (5) After reaching the predetermined preload force, remove the excitation and resume normal operation; (6) After a period of service, if the preload force is relaxed again, repeat steps (4) and (5) to continue preload force regulation; (7) Until the predetermined preload force requirement is reached, remove the excitation and resume normal operation.

[0009] The beneficial effects of the present invention are: The material of the shape memory porous structure layer used in the composite material in the present application has the characteristics of programmability and intelligent control performance. Through the composite of the shape memory porous structure layer and the super elastic foam layer, the pre-tightening state between assemblies can be regulated. The composite material is used to replace the traditional super elastic porous foam layer. On the premise of ensuring the original protection and pre-tightening effects, it can also solve the problem of pre-tightening state changes caused by the external environment during service, avoiding the tedious steps of dismantling the assembly to regulate the pre-tightening state after the pre-tightening state changes, and realizing a smarter, more convenient and more controllable regulation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic diagram of the steps of a method for regulating a composite material for regulating preload based on shape memory behavior; Figure 2 is a schematic diagram of the structure of the composite material; Figure 3 A schematic diagram of the process of controlling the preload of a composite material based on shape memory behavior; Figure 4 It is a schematic diagram of the temperature excitation and force change process during the intelligent control of the preload force of the composite material; Figure 5 This is the curve of force changing with time in the preload force control result.

[0011] In the figure: 1. Super elastic foam layer; 2. Shape memory porous structure layer. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0013] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0015] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0016] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0017] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0018] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0019] like Figure 2 and 3 As shown, the composite material for regulating preload based on shape memory behavior includes a superelastic foam layer 1 and a shape memory porous structure layer 2 which are stacked layer by layer or alternately.

[0020] The pore form of the superelastic foam layer is not restricted, specifically, it has superelastic properties, and its structural design meets the actual mechanical requirements; the porous structure design of the shape memory porous structure layer is also not restricted by the pore characteristics, specifically, it is designed to meet the required restoring force; the restoring force required by the shape memory porous structure layer can drive the deformation of the superelastic foam; The contact surface of the assembly gap is not limited to regular planes and curved surfaces, but also includes more complex irregular surfaces and surfaces with microstructure morphology; There is a certain relationship between the size of the assembly gap and the size of the composite layer. The size of the composite layer should be larger than the gap size to meet the preload requirements during preload assembly. In the assembly, the preload force is generated from the deformation of the superelastic foam layer, and the deformation of the superelastic foam layer is driven by the restoring force generated by the shape memory recovery of the shape memory porous structure layer; The composite material layer needs to be programmed with shape memory pre-compression deformation before assembly, and then the programmed composite material layer can be assembled; during assembly, the super elastic foam layer needs to be compressed so that its compression deformation generates pre-tightening force on the assembly; The shape memory porous structure layer in the assembly needs to activate the shape memory effect through external stimulation, and generate a driving force through the recovery behavior to drive the deformation of the super elastic foam layer.

[0021] The external excitation in the shape memory porous structure layer is at least one of thermal excitation, magnetic excitation, optical excitation and electrical excitation.

[0022] like Figure 1 and 3 As shown, a method for regulating a composite material for regulating preload based on shape memory behavior comprises the following steps: (1) Design the size and microstructure of the composite material based on the gap size and preload requirements of the assembly; (2) Shape memory programming of composite materials to store programmed deformation; (3) Assembling the pre-deformed composite material into the assembly and applying the preload force according to the actual requirements of the assembly; (4) By applying the excitation conditions of shape memory behavior, the shape memory porous structure layer programmed in the composite material is prompted to recover. The driving force generated by the recovery drives the deformation of the superelastic foam layer, thereby realizing the regulation of the preload force; (5) After reaching the predetermined preload force, remove the excitation and resume normal operation; (6) After a period of service, if the preload force is relaxed again, repeat steps (4) and (5) to continue preload force regulation; (7) Until the predetermined preload force requirement is reached, remove the excitation and resume normal operation.

[0023] Example: In this embodiment, a pre-tightening and anti-loosening parallel surface gap is filled with a composite material composed of a 3D printed shape memory polymer porous structure layer and a super elastic porous structure layer, and its thickness is obtained by design so that it can achieve the purpose of pre-tightening and anti-loosening. Figure 2 The figure shows the design of a double-layer composite material. The composite material is assembled into a gap between parallel surfaces, and the preload force is intelligently regulated through a thermal-mechanical process. The specific implementation process is detailed in Figure 3 The external excitation method used in this embodiment is thermal excitation, and the corresponding shape memory material is a thermally excited shape memory material. Figure 4 The figure is a schematic diagram of the temperature excitation and force change process during the intelligent control of the preload force of the composite material. The control method of the present invention realizes the control of the preload force. The evolution curve of the preload force in this case is shown in FIG. Figure 5 The operation of the embodiment of the control method of the composite material for controlling the preload force based on shape memory behavior is as follows: Step 1: Composite material microstructure and size design In this embodiment, according to the requirements of the embodiment, the dimensions of the assembly and its gap are first obtained, which are D 1 and L 1 , where the size of the shape memory porous structure layer is D S1 , Super elastic foam layer size D H1 The required preload force of the structures on both sides of the gap is calculated to be F1, and then the microstructure of the composite material layer is designed so that its size after assembly has a certain deformation control range and can reach the preload force of F1. Usually, the structure-activity relationship of the composite material is obtained through early thermal-mechanical experiments on composite materials, and even machine learning is used to reversely design the microstructure and size of the composite material that meets the required preload force.

[0024] Step 2: Composite material pre-deformation programming In this embodiment, the glass transition temperature of the shape memory polymer used is Tg, which is higher than room temperature. At room temperature (low temperature) below Tg, it exhibits the characteristics of hard plastic, such as good toughness and high strength; at a temperature above Tg (high temperature), it exhibits the characteristics of a superelastic rubber material, such as good elasticity, good flexibility, low strength, and easy deformation. The high temperature in this embodiment is only for the high temperature of the glass transition temperature of the shape memory polymer, and it is a temperature that will not affect other components of the assembly. The shape memory material is easy to deform at high temperatures, can fix its shape at low temperatures, and has a high bearing capacity. The composite material is placed at high temperature, and pre-deformation programming is performed on the composite material according to the design requirements of the assembly; the deformation is fixed and the temperature is lowered to ambient temperature; the external force is removed, and the deformation is fixed. At this time, the size of the composite material is D 2, where the main change is the change in the programmed deformation of the shape memory porous structure layer, and the size of the shape memory structure layer changes from D S1 Change to D S2 . The pre-deformation programming of the composite material is completed.

[0025] Step 3: Assemble the composite material in the assembly according to the preload requirements In this embodiment, the composite material with pre-programmed deformation is assembled into the gap of the assembly to be assembled. At this time, due to the size D of the composite material 2 Still larger than the dimension L of the assembly clearance 1 , the assembly process needs to be compressed. This compression deformation provides preload for the assembly. The size of the composite material after preload becomes D 3 , equal to the abbreviated size L 1 At this time, the change in the size of the composite material is mainly provided by the change in the size of the superelastic foam, and the size of the superelastic foam layer becomes D H2 .

[0026] Step 4: Control the preload of the assembly through external excitation Due to changes in the external environment, the gap between the assemblies changes from L 1 Change to L 1 +Δ 1 , at this time the size of the superelastic foam layer becomes D H3 , greater than D H2 The unloading deformation causes the preload force to decrease to F 2 , less than F 1 In this embodiment, a thermal stimulus is applied to the assembly after the preload is relaxed, and the temperature rises by ΔT 1 , causing the shape memory porous structure layer to deform and recover. This recovery will generate a driving force to drive the deformation of the super elastic foam layer, thereby regulating the size of the preload force until the preload force reaches F 1 At this time, the size of the double-layer material has changed to D S4 (greater than D S2 ) and D H4 (less than D H3 ). In this step, ΔT 1 Temperature regulation requires establishing the correlation between temperature changes and restoring force changes in order to better regulate the preload.

[0027] Step 5: Remove external excitation and stabilize the preload state In this embodiment, for the assembly structure after adjustment, the stimulus is removed and the normal use environment is restored. At this time, the composite material maintains the preload force of the assembly. If the preload force continues to relax during the subsequent service process, the adjustment in step 4 is repeated. The assembly after adjustment continues to maintain the preload and loosening prevention purpose of the packaging structure.

[0028] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A composite material for regulating preload based on shape memory behavior, characterized in that: It includes super elastic foam layers and shape memory porous structure layers which are stacked layer by layer or alternately.

2. The composite material for regulating preload based on shape memory behavior and the regulating method thereof according to claim 1, characterized in that: The shape memory porous structure layer activates the shape memory effect through external stimulation, and generates a driving force through the recovery behavior to drive the deformation of the super elastic foam layer.

3. The composite material for regulating preload based on shape memory behavior and the regulating method thereof according to claim 1, characterized in that: The external excitation in the shape memory porous structure layer is at least one of thermal excitation, magnetic excitation, optical excitation and electrical excitation.

4. The method for controlling the preload of a composite material based on shape memory behavior according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Design the size and microstructure of the composite material based on the gap size and preload requirements of the assembly; (2) Shape memory programming of composite materials to store programmed deformation; (3) Assembling the pre-deformed composite material into the assembly and applying the preload force according to the actual requirements of the assembly; (4) By applying the excitation conditions of shape memory behavior, the shape memory porous structure layer programmed in the composite material is prompted to recover. The driving force generated by the recovery drives the deformation of the superelastic foam layer, thereby realizing the regulation of the preload force; (5) After reaching the predetermined preload force, remove the excitation and resume normal operation; (6) After a period of service, if the preload force is relaxed again, repeat steps (4) and (5) to continue preload force regulation; (7) Until the predetermined preload force requirement is reached, remove the excitation and resume normal operation.

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