Impact buffering device and buffering method based on shape memory

Abstract

The invention provides an impact buffering device based on shape memory and a buffering method. The impact buffering device comprises a first connecting plate, a second connecting plate, a shape memory alloy elastic piece and a shape memory polymer gasket. The first connecting plate and the second connecting plate are fixedly connected in parallel, and an even number of shape memory polymer gaskets are arranged between the first connecting plate and the second connecting plate; the shape memory polymer gaskets are fixedly connected to the two ends of the memory alloy elastic piece respectively. Under normal conditions, the shape memory polymer gasket is in a folded state, and the shape memory alloy elastic piece is in an extended state; before impact, the temperature is increased, the shape memory polymer gasket is converted into an unfolded state, the shape memory alloy elastic piece is converted into a contracted state, and the shape memory polymer gasket is separated from the first connecting plate and the second connecting plate to generate gaps. Impact generated by an impact source can be effectively isolated through the device, and a multi-stage impact reduction scheme can be formed through parallel connection or series connection according to actual conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of cushioning and vibration reduction, and in particular relates to an impact mitigation device and a cushioning method based on shape memory. Background Art

[0002] Large, complex aircraft typically integrate multiple components and equipment, such as solar panels, data transmission antennas, microwave radars, robotic arms, and SAR antennas. Compared to other components, these components are typically retracted and compacted during the ascent phase. During their on-orbit service, they must perform tasks such as solar and Earth orientation, and target tracking. Therefore, they must be unlocked, deployed, or separated after entering orbit, significantly increasing the demand for on-orbit unlocking devices. Pyrotechnic connections offer rapid response, high reliability, and high connection stiffness, ensuring that the components and aircraft meet the frequency requirements of the ascent phase. Therefore, currently, pyrotechnic connections are commonly used for single-stage unlocking, deployment, or separation.

[0003] However, the pyrotechnic connection generates significant shock during single-stage unlocking, deployment, or separation. The shock generated by a pyrotechnic connection is complex and has three key characteristics: a very short duration, typically under 20ms; a very high acceleration amplitude, typically ranging from 300 to 300,000g; and a very high frequency over a wide range, typically from 100Hz to 100kHz. For example, when the compression release mechanism of a certain solar wing is unlocked, the shock magnitude near the pyrotechnic device is approximately 3,000 to 5,000g. Within a distance of 130mm to 160mm, the shock is attenuated to 1,500 to 2,500g, still a significant level. However, the shock test capacity of common single-unit devices is generally no greater than 1,200g, significantly lower than the shock load level of a pyrotechnic device. To protect the single-unit device and prevent internal damage from shock, the shock magnitude must be limited.

[0004] With the development of the aerospace industry, space services are becoming increasingly diverse and personalized, and the demand for both the number and types of pyrotechnic connection devices for various satellites and stand-alone products is increasing simultaneously. To meet the needs of different satellites and stand-alone products and reduce the impact of pyrotechnic connection devices on the main structure and stand-alone products during explosive actuation, impact mitigation measures must be considered. With the rapid development of the aerospace industry, the number of components on satellites, such as solar panels and microwave radars, that require pyrotechnic unlocking to deploy or separate is increasing. Precision electronic equipment is becoming more sensitive to shock loads, placing new demands on the design of isolation materials and structures for the pyrotechnic impact mechanics of aircraft. Summary of the Invention

[0005] The present invention provides an impact mitigation device and a buffering method based on shape memory. The device has an efficient, stable and reliable active impact mitigation effect. The impact generated by the impact source can be effectively isolated through the device, and a multi-stage impact reduction scheme can be formed in parallel or series according to actual conditions.

[0006] To achieve the above object, the technical solution of the present invention is: A first aspect of the present invention provides a shape memory-based impact mitigation device comprising a first connecting plate, a second connecting plate, a shape memory alloy elastic member, and a shape memory polymer gasket; The first connecting plate and the second connecting plate are fixedly connected in parallel, and an even number of the shape memory polymer gaskets are provided between the first connecting plate and the second connecting plate; The shape memory polymer gaskets are respectively fixed to both ends of the memory alloy elastic member to form an impact mitigation unit; Under normal circumstances, the shape memory polymer gasket is in a folded state, providing support for the vertical direction of the plane where the first connecting plate and the second connecting plate are located, and the shape memory alloy elastic part is in an extended state; before the impact, the temperature of the impact mitigation unit is increased, the shape memory polymer gasket is transformed into an expanded state, and the shape memory alloy elastic part is transformed into a contracted state, the shape memory polymer gasket is disengaged from the first connecting plate and the second connecting plate to produce a gap, and the supporting effect of the shape memory polymer gasket is reduced.

[0007] Preferably, a heater is provided on the impact mitigation unit, and the heater is used to heat the impact mitigation unit.

[0008] Preferably, the heater is a heating plate, and the heating plates are respectively fixed on the shape memory polymer gaskets.

[0009] Preferably, the heating plate is adhered and fixed on the shape memory polymer gasket.

[0010] Preferably, the shape memory alloy elastic member is a shape memory alloy spring.

[0011] Preferably, the shape memory alloy elastic member is a nickel-titanium alloy elastic member.

[0012] Preferably, the shape memory polymer gasket is provided at a fixing location between the first connecting plate and the second connecting plate.

[0013] Preferably, a plurality of first threaded holes are provided on the first connecting plate, a plurality of second threaded holes are provided on the second connecting plate, a through hole is provided on the shape memory polymer gasket, and the connecting bolts are connected in sequence through the first threaded hole of the first connecting plate, the through hole of the shape memory polymer gasket and the second threaded hole of the second connecting plate.

[0014] Based on the same inventive concept, a second aspect of the present invention provides a buffering method using the above-mentioned shape memory-based impact mitigation device, wherein an impact source is connected to a side of the first connecting plate away from the second connecting plate, or an impact source is connected to a side of the second connecting plate away from the first connecting plate; Before the impact source generates an impact, the temperature of the rising impact mitigation unit increases, the shape memory polymer gasket reaches the glass transition temperature, the elastic modulus decreases, and the shape memory alloy elastic member recovers to a contracted state under the action of temperature, and drags the shape memory polymer gasket, so that the shape memory polymer gasket reaches an expanded state, thereby creating a gap between the shape memory polymer gasket and the first connecting plate and the second connecting plate until they lose contact.

[0015] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: The present invention employs a shape-memory polymer gasket disposed between a first connecting plate and a second connecting plate, and a shape-memory alloy elastic member disposed between the shape-memory polymer gasket. The shape-memory polymer gasket is in an extended state and in a folded state in a normal state. Based on the characteristics of the shape-memory polymer gasket's elastic modulus decreasing at high temperatures and the shape-memory alloy elastic member's ability to recover its original contracted shape at high temperatures, the temperature is raised before an impact occurs, causing the elastic modulus of the shape-memory polymer gasket to decrease. By causing the shape-memory alloy elastic member to contract and recover to its original contracted shape, the shape-memory polymer gasket is pulled from its folded state to a nearly flat, expanded state, thereby reducing the connection stiffness between the first and second connecting plates. If the side of the first connecting plate facing away from the second connecting plate is connected to an impact source, and the side of the second connecting plate facing away from the first connecting plate is connected to a sensitive device, the impact transmitted from the impact source to the sensitive device is significantly attenuated. Therefore, compared to prior art impact mitigation devices, the present invention is highly efficient, stable, and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of an application example of the impact mitigation device according to Example 1 of the present invention; Figure 2 This is a schematic diagram of an impact mitigation device according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a first connecting plate in an impact mitigation device according to an embodiment of the present invention; Figure 4 Schematic diagram of the second connecting plate in the impact mitigation device according to an embodiment of the present invention; Figure 5 Schematic diagram of a heating plate in an impact mitigation device according to an embodiment of the present invention; Figure 6 This is the state when the temperature of the impact mitigation unit in the impact mitigation device according to the embodiment of the present invention is low; Figure 7 This is a schematic diagram of the impact mitigation device according to an embodiment of the present invention when the temperature is high; Figure 8 Schematic diagram of a shape memory polymer gasket in an impact mitigation device according to an embodiment of the present invention transitioning from a folded state to an extended state; Figure 9 Schematic diagram of a shape memory gasket in an impact mitigation device according to an embodiment of the present invention transitioning from an extended state to a compressed state; Figure 10 This is a schematic diagram of an application example of the impact mitigation device according to embodiment 2 of the present invention; Explanation of the accompanying drawings: 1-first connecting plate; 101-first threaded hole; 102-first fixing hole; 2-second connecting plate; 201-second threaded hole; 202-second fixing hole; 3-connecting bolt; 4-heater; 5-shape memory alloy elastic part; 6-shape memory polymer gasket; 601-through hole; 7-impact source; 8-main structure box plate; 9-sensitive unit. DETAILED DESCRIPTION

[0017] The following is a further detailed description of the shape memory-based impact mitigation device and buffering method proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description.

[0018] Example 1 See Figure 1-2 , an impact mitigation device based on shape memory, specifically comprising a first connecting plate 1, a second connecting plate 2, a shape memory alloy elastic member 5, and a shape memory polymer gasket 6; The first connecting plate 1 and the second connecting plate 2 are fixedly connected in parallel, and an even number of shape memory polymer gaskets 6 are provided between the first connecting plate 1 and the second connecting plate 2; The shape memory polymer gaskets 6 are respectively fixed to both ends of the memory alloy elastic member to form an impact reduction unit.

[0019] In this embodiment, one side of the first connecting plate 1 away from the second connecting plate 2 can be connected to the impact source 7, and one side of the second connecting plate 2 away from the first connecting plate 1 is connected to the mechanism to be protected (hereinafter, the first connecting plate or the second connecting plate is externally connected to the impact source or the mechanism to be protected, which means the side away from the other connecting plate). For example, it is applied to the unlocking impact occasion of satellite or aircraft pyrotechnics, such as Figure 1 shown, the first connecting plate 1 is connected to the impact source 7, and the second connecting plate 2 is connected to the main structure box plate 8.

[0020] Under normal circumstances, as Figure 1 and Figure 6 shown, the shape memory polymer gasket 6 is in a folded state, and the shape memory polymer gasket 6 plays a strong supporting role in the vertical direction of the plane where the first connecting plate 1 and the second connecting plate 2 are located, and the shape memory alloy elastic member 5 is in an extended state; before the impact source 7 generates an impact, first raise the temperature of the impact mitigation unit. When the temperature reaches the glass transition temperature of the shape memory polymer gasket 6, the elastic modulus decreases and the hardness decreases. At the same time, the temperature of the shape memory alloy elastic member 5 also increases. Under the action of high temperature, the shape memory alloy elastic member 5 shrinks and returns to its original contracted shape (as Figure 9 shown). Since the shape memory polymer is arranged at both ends of the shape memory alloy elastic member 5, the shape memory polymer gasket 6 is pulled from the folded state to an approximately flat unfolded state (as Figure 8 shown), resulting in a gap between the shape memory polymer gasket 6 and the first connecting plate 1 and the second connecting plate 2 until they are out of contact (as Figure 7 shown). The supporting effect on the first connecting plate 1 and the second connecting plate 2 is reduced, and then the connection stiffness between the first connecting plate 1 and the second connecting plate 2 is reduced, resulting in a significant attenuation of the impact transmission ability, a reduction in the impact transmitted to the second connecting plate 2, and the effect of attenuating the impact and protecting the main structure box plate 8. [[ID=十六]] [[ID=十七]]

[0021] The shape memory alloy material originates from the reversible phase change between the austenite phase (a cubic crystal structure at high temperature (>Af, austenite finish temperature) or in the absence of external force, hard and shape-stable) and the martensite phase (a monoclinic crystal structure at low temperature (<Mf, martensite finish temperature) or under external force, soft and easy to deform). When the temperature rises and exceeds the austenite finish temperature (Af), the shape memory alloy elastic member 5 will undergo a reverse phase change, driving the material to restore its high-temperature shape. That is, in this embodiment, after the temperature rises, the extended memory alloy elastic member will return to its original contracted state; when the temperature drops and is lower than the martensite finish temperature (Mf), the shape memory alloy elastic member 5 enters the martensite state and exhibits superelasticity. That is, in this embodiment, after the temperature drops, the contracted memory alloy elastic member will return to the extended state. In this embodiment, the shape memory alloy elastic member 5 is preferably a nickel-titanium alloy elastic member.

[0022] Shape memory polymers can change shape and fix under specific conditions, then return to their original shape in response to external stimuli (such as temperature in this embodiment). In this embodiment, when the temperature rises to the polymer's glass transition temperature, it softens reversibly. The shape memory alloy elastic member 5 causes the shape memory polymer gasket 6 to deform and transform into an expanded state, causing it to break contact with the first and second connecting plates. This reduces the support provided by the shape memory polymer gasket 6 between the first and second connecting plates 1 and 2, thereby reducing the stiffness of the connection between the first and second connecting plates 1 and 2 and, in turn, reducing the impact of the first and second connecting plates 1 and 2. When the temperature drops to the polymer's glass transition temperature, it solidifies reversibly, transforming into a folded state. This state, which is the normal state of this embodiment, is relatively high, providing strong support perpendicular to the plane of the first and second connecting plates 1 and 2. In this embodiment, the shape memory polymer gasket 6 can be made of either polylactic acid or epoxy resin. The glass transition temperature of polylactic acid is approximately 60°C, while that of epoxy resin is approximately 50°C.

[0023] Therefore, in this embodiment, the impact reduction device designed based on the elastic modulus reduction characteristics of the shape memory polymer gasket 6 at high temperatures and the characteristic of the shape memory alloy elastic part 5 restoring its original contracted shape at high temperatures has a reliable active impact reduction effect under temperature stimulation.

[0024] In a preferred embodiment, a heater 4 is provided on the impact mitigation unit, and the heater 4 is used to heat the impact mitigation unit. Figure 5 As shown, the heater 4 is a heating plate, and the heating plates are respectively fixed on the shape memory polymer gaskets 6.

[0025] Preferably, the heating plate is fixed on the shape memory polymer gasket 6 by means of fixing glue.

[0026] Preferably, the shape memory alloy elastic member 5 is a shape memory alloy spring, for example Figure 6 Two shape memory alloy springs are arranged between the two shape memory polymer spacers 6 shown.

[0027] A preferred embodiment is as follows Figure 2 As shown, the shape memory polymer gasket 6 is provided at a fixing location between the first connecting plate 1 and the second connecting plate 2 .

[0028] Preferably, if Figure 2-4 and Figure 8As shown, a plurality of first threaded holes 101 are provided on the first connecting plate 1, a plurality of second threaded holes 201 are provided on the second connecting plate 2, a through hole 601 is provided on the shape memory polymer gasket 6, and the connecting bolts 3 are sequentially provided through the first threaded hole 101 of the first connecting plate 1, the through hole 601 of the shape memory polymer gasket 6 and the second threaded hole 201 of the second connecting plate 2.

[0029] Considering that the first connecting plate 1 is connected to the impact source 7 , a first fixing hole 102 is opened on the first connecting plate 1 ; similarly, the second connecting plate 2 is connected to the protected structure (such as the main structure box plate 8 ), and a second fixing hole 202 is opened on the second connecting plate 2 .

[0030] Example 2 In practical applications, the first connecting plate 1 can also be connected to the protected structure, and the second connecting plate 2 can be connected to the impact source 7. For example, in this embodiment, Figure 10 As shown, the first connecting plate 1 is connected to the sensitive unit 9 (protected mechanism) and the main structure box plate 8 (equivalent to the impact source 7). The second connecting plate 2 is connected to the main structure box plate 8. One side of the main structure box plate 8 is connected to the impact source 7, isolating the impact and protecting the sensitive unit 9. Before the impact generated by the impact source 7 passes through the main structure box plate 8 and is then transmitted by the main structure box plate 8, or before the generated impact reaches the main structure box plate 8, the heater 4 starts to operate and raises the impact mitigation unit, reducing the elastic modulus of the shape memory polymer gasket 6. Under the drag of the shape memory alloy elastic member 5 returning to its original contracted shape, the shape memory polymer gasket 6 reaches a nearly flat, expanded state, and a gap is created between the shape memory polymer gasket 6 and the first connecting plate 1 and the second connecting plate 2. This reduces the stiffness between the first and second connecting plates 1 and 2, reduces the impact transmitted from the main structure box plate 8 to the second connecting plate 2 and the sensitive unit 9, and thus isolates and protects the sensitive unit 9.

[0031] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the scope of protection of the present invention.

Claims

1. A shape memory-based impact mitigation device, characterized in that: It includes a first connecting plate, a second connecting plate, a shape memory alloy elastic member, and a shape memory polymer gasket; The first connecting plate and the second connecting plate are fixedly connected in parallel, and an even number of the shape memory polymer gaskets are provided between the first connecting plate and the second connecting plate; The shape memory polymer gaskets are respectively fixed to both ends of the memory alloy elastic member to form an impact mitigation unit; Under normal circumstances, the shape memory polymer gasket is in a folded state, providing support for the vertical direction of the plane where the first connecting plate and the second connecting plate are located, and the shape memory alloy elastic part is in an extended state; before the impact, the temperature of the impact mitigation unit is increased, the shape memory polymer gasket is transformed into an expanded state, and the shape memory alloy elastic part is transformed into a contracted state, the shape memory polymer gasket is disengaged from the first connecting plate and the second connecting plate to produce a gap, and the supporting effect of the shape memory polymer gasket is reduced.

2. The shape memory-based impact mitigation device according to claim 1, characterized in that: A heater is provided on the impact mitigation unit, and the heater is used to heat the impact mitigation unit.

3. The shape memory-based impact mitigation device according to claim 2, characterized in that: The heaters are heating plates, and the heating plates are respectively fixed on the shape memory polymer pads.

4. The shape memory-based impact mitigation device according to claim 3, characterized in that: The heating plate is adhered and fixed on the shape memory polymer gasket.

5. The shape memory-based impact mitigation device according to claim 1, characterized in that: The shape memory alloy elastic member is a shape memory alloy spring.

6. The shape memory-based impact reduction device according to claim 1 or 5, characterized in that: The shape memory alloy elastic member is a nickel-titanium alloy elastic member.

7. The shape memory-based impact mitigation device according to claim 1, characterized in that: The shape memory polymer gasket is disposed at a fixed location between the first connecting plate and the second connecting plate.

8. The shape memory-based impact reduction device according to claim 7, characterized in that: A plurality of first threaded holes are provided on the first connecting plate, a plurality of second threaded holes are provided on the second connecting plate, a through hole is provided on the shape memory polymer gasket, and connecting bolts are sequentially provided through the first threaded hole, the through hole and the second threaded hole.

9. A buffering method of the impact mitigation device based on shape memory according to any one of claims 1 to 8, characterized in that: A side of the first connecting plate away from the second connecting plate is connected to an impact source, or a side of the second connecting plate away from the first connecting plate is connected to an impact source; Before the impact source generates an impact, the temperature of the rising impact mitigation unit increases, the shape memory polymer gasket reaches the glass transition temperature, and the elastic modulus decreases. At the same time, the shape memory alloy elastic member recovers to a contracted state under the action of temperature and drags the shape memory polymer gasket, so that the shape memory polymer gasket reaches an expanded state, thereby creating a gap between the shape memory polymer gasket and the first connecting plate and the second connecting plate until they lose contact.

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