An autonomous morphing skin that fuses 4D printing technology

Abstract

The application provides an autonomous deformation skin, comprising a composite lattice microstructure, a connecting sheet, a surface elastomer and a driving motor; the composite lattice structure comprises at least one layer of zero Poisson's ratio lattice structure and at least one layer of corrugated lattice structure arranged alternately in rows; the connecting sheet bridges the lattice structures; the surface elastomer covers the surface of the composite lattice microstructure and the connecting sheet; and the driving motor is fixed to the wing root and driven by power control to drive the skin structure to contract or expand. The autonomous deformation skin is manufactured finely and quickly through "composite lattice structure + shape memory polymer composite stress deformation + 3D printing", and the structure of the deformation skin is driven efficiently through the mode of "piezoelectric driving main driving force + corrugated lattice structure autonomous deformation auxiliary driving force", so that the problem of the internal structure of the skin as a load reducing the driving efficiency is eliminated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of intelligent morphing skin, and particularly relates to an autonomous morphing skin fusing 4D printing technology and dot matrix microstructure. BACKGROUND

[0002] Traditional aircrafts are optimally designed according to tasks on demand, and can only meet one or several design requirements. With the change of flight task requirements, the aircraft is required to adjust its aerodynamic layout according to the flight task and environment, so as to realize the optimal state of the whole flight profile. The morphing wing is an important part to support the optimal flight profile of the aircraft, and the morphing skin technology is one of the basic technologies to support the morphing of the wing.

[0003] The morphing skin needs to meet the following requirements: 1. sufficient elastic deformation; 2. without excessive driving force; 3. capable of bearing sufficient aerodynamic load without adding excessive stringers, ribs and other support structures to avoid excessive weight. At present, the morphing skin mainly includes polymer morphing skin relying on the elastic deformation of the material itself and rigid morphing mechanism morphing skin. However, the pure polymer skin is difficult to meet the high bearing requirement, and the rigid morphing skin also has the problem of heavy weight. Therefore, it is necessary to study the skin with light weight, high bearing capacity and large deformation capacity. SUMMARY

[0004] In order to overcome the deficiencies in the prior art, the application provides an autonomous morphing skin, which realizes fine and rapid manufacturing of the morphing skin structure and autonomous deformation through "composite dot matrix structure + shape memory polymer composite material stress deformation + 3D printing", eliminates the problem of the internal structure of the skin as a load to reduce the driving efficiency by cooperating with piezoelectric ultrasonic driving, realizes efficient driving of the structure of the morphing skin, and thus completes the application.

[0005] The technical scheme provided by the application is as follows:

[0006] An autonomous morphing skin, comprising a composite dot matrix microstructure, a connecting sheet, a surface elastomer and a driving motor.

[0007] The composite dot matrix structure comprises at least one layer of zero Poisson's ratio dot matrix structure and at least one layer of corrugated dot matrix structure arranged alternately in rows, the corrugated dot matrix structure is a corrugated plate structure formed by continuous arc-shaped plate cells, the arc degrees of the arc-shaped plate cells are the same, and the cell width of the corrugated dot matrix structure and the zero Poisson's ratio dot matrix structure in the stretching and contraction deformation direction of the skin is the same.

[0008] The connecting sheet bridges the dot matrix structures;

[0009] The surface elastomer is coated on the surface of the composite dot matrix microstructure and the connecting sheet.

[0010] The driving motor is fixed to the wing root and driven by power control to drive the skin structure to contract or expand.

[0011] The autonomous deformation skin has the following beneficial effects:

[0012] (1) The autonomous deformation skin provided by the application adopts a composite lattice structure design of "zero Poisson ratio lattice + corrugated lattice", the zero Poisson ratio lattice structure does not expand or contract in the transverse direction when stretched in one direction due to its zero Poisson characteristic, which is beneficial to maintaining the overall contour structure of the airfoil; the corrugated lattice structure conforms to the deformation trajectory of the shape memory composite polymer, which is beneficial to the stress self-driven deformation characteristics of the shape memory composite material.

[0013] (2) The autonomous deformation skin provided by the application integrates 4D printing into the manufacturing of the deformation skin lattice structure, and realizes the reciprocating self-driven deformation of the corrugated lattice structure under the loading and unloading of external heat source / power source by 3D printing the corrugated lattice structure composed of shape memory polymer composite material. The traditional lattice structure is mainly composed of polymer, metal and other materials, which is passively driven and does not have self-driving capability, and relies entirely on an external driver to drive deformation. The lattice structure as a load is not conducive to the efficient driving of the driver. The application adopts a lattice structure manufactured based on a shape memory polymer composite material to meet the requirement of efficient driving.

[0014] (3) The autonomous deformation skin provided by the application realizes efficient driving deformation of the deformation skin by using the dual driving design concept of "piezoelectric ultrasonic main driving + lattice structure sub-driving auxiliary driving". BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a top view of the autonomous deformation skin;

[0016] Figure 2 is a sectional view of the autonomous deformation skin;

[0017] Figure 3 is a bottom view of the autonomous deformation skin (without surface elastomer).

[0018] REFERENCE SIGNS

[0019] 1 - zero Poisson ratio lattice structure; 2 - corrugated lattice structure; 3 - connecting piece; 4 - surface elastomer; 5 - driving motor; 6 - rack rail. DETAILED DESCRIPTION

[0020] The features and advantages of the application will become more apparent from the following detailed description.

[0021] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The disclosure can lie in various sub-combinations of the various features described herein, not solely the combinations specifically set out in the examples.

[0022] The present application provides an autonomous morphing skin, which is driven by a hybrid double drive of "piezoelectric drive as the main drive and 4D printed corrugated lattice structure drive as the auxiliary drive", realizing efficient drive of the morphing skin.

[0023] With reference to Figure 1 , Figure 2 and Figure 3 , an autonomous morphing skin includes at least one layer of zero Poisson's ratio lattice 1, at least one layer of corrugated lattice structure 2, connecting pieces 3 connecting each layer of lattice structure, a flexible surface elastomer 4 covering the upper surface of the zero Poisson's ratio lattice structure 1, the corrugated lattice structure 2, and the connecting pieces 3, and a drive motor 5 serving as the main drive, wherein the corrugated lattice structure 2 is a corrugated plate structure formed by continuous arc-shaped plate cells, each arc-shaped plate cell has the same curvature and the same arc direction, and the corrugated lattice structure 2 has the same cell width as the zero Poisson's ratio lattice 1 in the stretching and shrinking direction of the skin, facilitating the connection of the composite lattice structure by the conductive connecting pieces 3. The drive motor 5 serves as the main drive, the corrugated lattice structure 2 composed of shape memory polymer composite material serves as the auxiliary drive, and the two driving modes work together to realize the deformation drive of the skin, eliminate the disadvantage of the lattice structure as a load that is not conducive to efficient driving of the driver, and realize high-performance driving.

[0024] With reference to Figure 1 and Figure 3 , the lattice structure as the drive action execution component is a composite lattice structure composed of two different lattice structures, one being a zero Poisson's ratio lattice structure 1 and the other being a corrugated lattice structure 2, the two lattice structures are arranged alternately and are both manufactured by 3D printing rapid prototyping. Among them, the corrugated lattice structure 2 is composed of short-cut fiber reinforced shape memory polymer composite material, preferably short-cut glass fiber, short-cut carbon fiber reinforced shape memory polymer composite material. The zero Poisson's ratio lattice structure 1 is made of metal material or fiber reinforced polymer composite material, which is a six-sided zero Poisson's ratio lattice structure.

[0025] Each layer of the zero-poisson ratio lattice structure 1 and the corrugated lattice structure 2 is connected to the connecting sheet 3 by mortise and tenon or adhesion, the connecting sheet 3 is a sheet layer structure with a certain thickness and is processed by carbon fiber, copper or alloy material and the like conductive material. The connecting sheet 3 has good conductivity, is conducive to conducting the electricity / heat of the external power source / heat source applied to one end of the skin, and loads the electricity / heat on the corrugated lattice structure 2 composed of the short-cut fiber reinforced shape memory polymer composite, and is conducive to the corrugated lattice structure 2 to realize the self-driven deformation. When the external power source / heat source is loaded, the corrugated lattice structure 2 will produce stress deformation, and when the external power source / heat source is unloaded, the deformation is restored. Through the repeated stimulation source loading / unloading process, reciprocating contraction / extension movement is realized, so as to drive the composite lattice structure to move together and realize the efficient deformation of the deformed skin. When the control source is an external heat source, the temperature range is 30-150℃.

[0026] The surface elastomer 4 is preferably an elastic silicone rubber and has good ductility.

[0027] The driving motor 5 is fixed to the wing root, a reducer gear on the driving motor 5 is engaged with a rack rail 6, the rack rail 6 is fixedly connected with the wing, and the driving motor 5 is operated to drive the reducer gear to rotate, the rack rail 6 engaged with the reducer gear moves, and then the skin structure is driven to contract from the wing tip or to extend and restore from the wing root. The rack rail 6 can be supported by a guide support shaft to ensure stable movement. The number of driving motors is selected according to the size of the driving skin and the input force requirement. The driving motor 5 is a piezoelectric ultrasonic driving motor, has the advantages of compact structure and large thrust-to-weight ratio, and can meet the requirements of being the main driving force of the skin deformation.

[0028] In a preferred embodiment, the preparation process of the 3D printed shape memory composite corrugated lattice structure 2 is as follows:

[0029] Short-cut fibers such as short-cut carbon fibers and memory polymers such as polylactic acid are selected as raw materials, the content of the short-cut fibers is 5%-20%; the short-cut fibers, polylactic acid and a solvent such as acetone are mixed, and are uniformly stirred at a high temperature of 40-100℃ until cooled to room temperature, and then are crushed by a crusher for standby use; finally, a 3D printing device is used to print the shape memory composite corrugated lattice structure.

[0030] The self-driven deformation skin of the present application integrates the 4D printing technology, designs a "mixed double driving mode of piezoelectric driving as the main mode + 4D printing driving as the auxiliary mode", and adopts a "zero-poisson ratio structure + corrugated lattice" composite lattice structure. The zero-poisson ratio lattice structure has the zero-poisson characteristic, and one-way stretching is conducive to maintaining the contour structure in other non-stretching directions; the corrugated lattice structure can realize self-driven stress through external power source / heat source loading, auxiliary piezoelectric main drive of one end of the skin, and efficient driving of the whole skin structure.

[0031] The present application is described in detail above in connection with specific embodiments and exemplary examples, but it is not understood that these descriptions and examples are intended to limit the present application. It is understood by those skilled in the art that various equivalent substitutions, modifications or improvements can be made to the technical solutions and embodiments of the present application without departing from the spirit and scope of the present application, and these all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims.

[0032] The contents not described in detail in the specification of the present application are the known technology of those skilled in the art.

Claims

1. A self-deforming skin, characterized in that, It includes a composite lattice microstructure, a connecting piece (3), a surface elastomer (4), and a drive motor (5); The composite lattice microstructure includes at least one layer of zero Poisson's ratio lattice structure (1) and at least one layer of corrugated lattice structure (2) arranged in alternating rows. The corrugated lattice structure (2) is a corrugated plate structure formed by continuous arc plate cells. Each arc plate cell has the same curvature, and the cell width of the corrugated lattice structure (2) and the zero Poisson's ratio lattice structure (1) is the same in the direction of skin stretching and deformation. The corrugated lattice structure (2) is made of short-cut fiber reinforced shape memory polymer composite material. It undergoes stress-induced autonomous deformation when an external power source / heat source is applied, and recovers its deformation after the external power source / heat source is unloaded. The connecting piece (3) bridges the lattice structure of each layer; The surface elastomer (4) is coated on the surface of the composite lattice microstructure and the connecting piece (3); The drive motor (5) is fixed at the root of the wing and is driven by power supply to cause the skin structure to contract or extend.

2. The self-deforming skin according to claim 1, characterized in that, The zero Poisson's ratio lattice structure (1) and the corrugated lattice structure (2) are manufactured by 3D printing.

3. The self-deforming skin according to claim 1, characterized in that, The zero Poisson ratio lattice structure (1) is a hexagonal zero Poisson ratio lattice structure.

4. The self-deforming skin according to claim 1, characterized in that, When the corrugated lattice structure (2) is prepared from short-cut fiber reinforced shape memory polymer composite material, the preparation process is as follows: Short-cut fibers and shape memory polymers are selected as raw materials, with short-cut fibers accounting for 5% to 20% of the total content. The short-cut fibers, shape memory polymers, and organic solvents are mixed and stirred evenly at 40 to 100°C until cooled to room temperature. Then, they are crushed using a crusher for later use. Finally, the shape memory composite material corrugated lattice structure is printed using 3D printing equipment.

5. The self-deforming skin according to claim 1, characterized in that, The connecting piece (3) is made of conductive material.

6. The self-deforming skin according to claim 1, characterized in that, The surface elastomer (4) is elastic silicone rubber.

7. The self-deforming skin according to claim 1, characterized in that, The drive motor (5) is a piezoelectric ultrasonic drive motor.

8. The self-deforming skin according to claim 1, characterized in that, The reducer gear on the drive motor (5) meshes with the rack and pinion rail (6) installed on the wing. The length direction of the rack and pinion rail (6) is the direction of skin expansion and contraction deformation. The drive motor (5) drives the reducer gear to rotate, and the rack and pinion rail (6) meshing with the reducer gear moves, causing the skin structure to expand and contract.

9. The self-deforming skin according to claim 1, characterized in that, The number of drive motors (5) is determined according to the size of the drive skin and the input force requirements.

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