CN-122009454-A - Composite flapping wing structure based on chiral/anti-chiral core layer

CN122009454ACN 122009454 ACN122009454 ACN 122009454ACN-122009454-A

Abstract

The invention discloses a composite flapping wing structure based on a chiral/anti-chiral core layer, relates to the technical fields of advanced composite material structural design, metamaterial structural design, application and the like, and aims to solve the problems of stress concentration, complex driving, low efficiency and the like in underwater flapping wing propulsion. The structure comprises chiral/anti-chiral core layers, flexible skin layers and the like which are alternately arranged, wherein the chiral/anti-chiral core layers realize uniform stress distribution during deformation through the negative Poisson ratio characteristic, and the flexible skin layers enhance shear transfer and reduce flow resistance. Compared with the traditional connecting rod flapping wing mechanism, the structure driving efficiency and reliability are improved, the driving structure is simplified, and the deformation characteristics of the structure are more flexible, so that the structure can adapt to more complex and multi-mode working environments.

Inventors

ZHANG QICHENG
ZHANG SHUHANG
WANG ZHIYANG
YUAN MINGYI
ZHANG DAYI

Assignees

北京航空航天大学

Dates

Publication Date: 20260512
Application Date: 20260401

Claims (10)

1. A composite flapping wing structure based on a chiral/anti-chiral core layer is characterized by comprising a connecting frame, a composite beam core layer arranged in the connecting frame, a core layer structure formed by the chiral core layer or the anti-chiral core layer and a flexible skin layer coated on the outer surface of the core layer structure, wherein the chiral core layer or the anti-chiral core layer consists of a plurality of chiral units or anti-chiral units and the beam structure which are alternately arranged along the span direction, each chiral unit or anti-chiral unit comprises a central rigid node and flexible ligaments which are connected with the central rigid node and are distributed in a spiral shape or a mirror image spiral shape, and the flexible skin layer is attached to and covers the outer surfaces of the core layer structure and the connecting frame to form the whole shape of the flapping wing.
2. The composite ornithine structure based on chiral/anti-chiral core of claim 1, wherein the chiral core and the anti-chiral core are alternately arranged in a spanwise direction to form a core configuration having a negative poisson's ratio characteristic.
3. A composite flapping wing structure based on chiral/anti-chiral core according to claim 1, further comprising adjusting ribs provided on both sides of the bottom and slidable along the length of the flapping wing for adjusting the overall bending stiffness and vibration frequency of the flapping wing.
4. The composite flapping wing structure based on the chiral/anti-chiral core layer according to claim 1, wherein the flexible skin layer is made of single-layer or multi-layer flexible materials, and the outer surface of the flexible skin layer is provided with a bionic micro-nano texture structure.
5. The composite flapping wing structure based on the chiral/anti-chiral core layer according to claim 1, wherein the connecting frame is connected with an external driving mechanism through a spherical hinge, so that the flapping wing has free rotation capability in a three-dimensional space.
6. A composite ornithine structure based on chiral/anti-chiral core according to claim 1, wherein the chiral unit is integrally formed with the flexible ligament and the central rigid node in the anti-chiral unit using the same flexible material.
7. A composite ornithine structure based on chiral/achiral cores according to claim 1, wherein the composite Liang Xin layer is located at one end of the chiral or achiral core.
8. A composite ornithine structure based on chiral/anti-chiral core according to claim 1, wherein the chiral or anti-chiral units are distributed in an orthogonal array and are interconnected to form a continuous core structure.
9. A composite ornithine structure based on chiral/anti-chiral core according to claim 1, wherein it is integrally formed by an additive manufacturing process.
10. The composite flapping wing structure based on the chiral/anti-chiral core layer according to claim 1, wherein the flexible skin layer and the core layer structure are tightly attached through a mould pressing process, so that no bubbles or gaps are formed at the interface.

Description

Composite flapping wing structure based on chiral/anti-chiral core layer Technical Field The invention relates to the technical fields of advanced composite material structural design, metamaterial structural design, application and the like, in particular to a composite flapping wing structure based on a chiral/anti-chiral core layer. Background With the development of bionics and automatic control in recent years, the underwater bionic unmanned aerial vehicle receives attention, and has a series of advantages of high propulsion efficiency, high maneuverability, long endurance and the like, so that the underwater bionic unmanned aerial vehicle has great potential. The bionic flapping wing structure is an important scheme of the bionic underwater unmanned aerial vehicle. However, most of the existing research flapping wing structures adopt a connecting rod mechanism design, so that the structure is complex, the control is difficult, and the reliability is low. Disclosure of Invention Aiming at the defects of low propulsion efficiency, complex flapping wing structure, difficult control, difficult manufacture and the like of the existing underwater unmanned underwater vehicle, the invention provides a composite flapping wing structure based on a chiral/anti-chiral core layer. The chiral structure has the advantages of stress dispersion, light weight, controllable deformation characteristic and the like while ensuring high strength. Furthermore, chiral mechanical metamaterials typically have Negative Poisson's Ratio (NPR) characteristics, unlike conventional materials, which elongate in a direction perpendicular to the direction of stretching when subjected to stretching. This property imparts enhanced in-plane dent resistance, fracture toughness, transverse shear modulus, and good dynamic properties to the material, with a variety of unique advantages such as efficient dispersion and absorption of energy when impacted or compressed, higher strength and toughness under shear and fracture loads, facilitating uniform stress distribution, reducing localized stress concentrations, and the like. Based on the structure, the flapping wing with the flexible characteristic comprises a chiral core layer or an anti-chiral core layer arranged inside, a composite beam core layer and a connecting frame, wherein the composite beam core layer forms a mechanical reinforcing structure through specific geometric arrangement, and the connecting frame is used for connecting the flapping wing with an external driving mechanism so as to realize the reciprocating motion of the flapping wing in an underwater environment, the uniform stress distribution during the controlled deformation, the energy efficient conversion and the self-adaptive optimization of a motion track, thereby obviously improving the propulsion efficiency and the structural reliability on the premise of simplifying the driving mechanism. The invention can improve the propulsion efficiency of the flapping wing structure, simplify the design of the driving mechanism and enhance the flexibility of movement by combining the unique mechanical properties of chiral and anti-chiral structures and the nonlinear deformation characteristic of flexible materials. In order to achieve the above purpose, the invention adopts the following technical scheme: A composite flapping wing structure based on a chiral/anti-chiral core layer comprises a connecting frame, a composite beam core layer arranged in the connecting frame, a core layer structure formed by the chiral core layer or the anti-chiral core layer, and a flexible skin layer coated on the outer surface of the core layer structure, wherein the chiral core layer or the anti-chiral core layer consists of a plurality of chiral units or anti-chiral units and the beam structure which are alternately arranged along the span direction, each chiral unit or anti-chiral unit comprises a central rigid node and flexible ligaments which are connected with the central rigid node and are spirally distributed or mirror-image spirally, and the flexible skin layer is attached to and covers the outer surfaces of the core layer structure and the connecting frame to form the whole shape of the flapping wing. The beneficial effects are that: 1. By combining the unique mechanical properties of chiral and anti-chiral core layers and the nonlinear deformation characteristics of flexible materials, the controllable deformation of the flapping wing with multiple degrees of freedom is realized on the premise of simplifying a connecting rod mechanism, the propulsion efficiency and the movement flexibility of the flapping wing structure are obviously improved, and the control complexity is reduced. 2. The invention utilizes the negative poisson ratio characteristic to realize the uniform stress distribution of the flapping wing in the deformation process, effectively avoids fatigue fracture caused by local stress concentration, and improves the structura