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Preparation And Properties Of Biomimetic Fiber Reinforced Composites Inspired By The Strength-toughness Coordination Mechanism Of Feathers’ Microstructures

Posted on:2024-10-02Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y F WangFull Text:PDF
GTID:1520307340978629Subject:Bionic science and engineering
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With the deepening of our country’s "Manufacturing Power" strategy,the requirements for the comprehensive performance of materials in national major projects continue to increase.For example,many large-scale projects in important fields such as national defense security,marine development,aerospace,and rail transportation urgently need strategic new materials such as high-performance fiber composites.Fiber composites are widely used in fields such as aerospace,automotive,construction,and sports equipment due to their high strength,light weight,corrosion resistance,and high temperature resistance.They are of great significance for improving product performance,reducing energy consumption,and promoting sustainable development.Since fiber composites are mainly composed of fibers and matrices,a strong heterogeneous interface can ensure good stress transfer between fibers and matrices,thereby improving the strength and stiffness of the composite materials.The higher toughness of the matrix enables the composite material to have better impact resistance and crack propagation resistance.The interface strength between fibers and matrices and the fracture toughness of the matrix itself are key factors affecting the mechanical properties of fiber composites.However,excessively high interface strength may cause the composite material to fracture brittlely under external impact or load;excessively high matrix toughness may reduce the interface strength and weaken the bonding strength between fibers and matrices.Therefore,from the perspective of interface strengthening and matrix toughening,it is of great academic value and practical significance to break through the design bottleneck of material comprehensive performance improvement relying on regulating material composition and carry out research on the design,preparation,and performance of strong and tough coordinated fiber composites and fiber composite components.Natural selection and survival of the fittest.After millions of years of evolution and optimization,typical biological materials in the natural world have broken through the intrinsic limitations of natural materials and achieved the leap of material performance through unique structural configurations.They possess excellent functional adaptability and strong toughness coordination,providing important inspiration for the design of modern high-performance composites.Bird feathers are typical examples.Birds face extremely complex aerodynamic loads during flight,but their flight efficiency and duration far exceed other flying creatures,mainly due to the unique mechanical properties of bird feathers.Research shows that bird feathers are a natural fiber composite material,and the synergistic action of the feather shaft cortex,feather shaft medulla,and feather branches enables stable heterogeneous interface connection and energy dissipation toughening,ensuring that bird feathers have sufficient strength and toughness to resist potential destructive loads and excessive deformation during flight.Therefore,systematically exploring the structural characteristics of bird feathers and revealing the strong-tough coordination mechanism of bird feathers can provide innovative inspiration for the biomimetic design of the next generation of high-performance fiber composites.This article selects the wing feathers of the large raptor Black Kite(Milvus migrans)as the research object,and in-depth studies the hierarchical structure,material chemical composition,and macro/micro mechanical response characteristics of the wing feathers.It reveals the strength-toughness coordination mechanism of the wing feathers,proposes a biomimetic engineering mapping model based on the microstructure of the wing feathers,carries out interface-enhanced design of fiberreinforced composite materials mimicking the branching of feather shafts and matrixenhanced design of graded porous bone microstructure,and produces biomimetic fiber-reinforced composite materials and components based on the strength-toughness coordination mechanism of the wing feather microstructure.By combining methods such as mechanical property testing,material mechanics theory analysis,macromicroscopic morphology characterization of failure,and finite element calculation simulation,it reveals the strength-toughness coordination mechanism of biomimetic fiber-reinforced composite materials and components.The main research conclusions obtained are as follows:In terms of the study of the strength-toughness coordination mechanism of feathers,it has been found that the feather branches achieve their high strength characteristics through a remodelable interlocking microstructure.The interlocking between adjacent barbs of the feathers is achieved through a process of stretching,sliding,unhooking,and remodeling,which absorbs and dissipates the load energy,endowing the feather with excellent fatigue properties and resistance to damage.The graded porous skeletal microstructure of the rachis enables the feather to have high toughness.The randomly oriented keratin fibers evenly distribute the energy to the interior of the rachis,and the overall flexural deformation and progressive damage of the skeletal structure avoid localized catastrophic failure of the rachis.The microstructure of the cortical layer of the rachis achieves the coordination and balance between strength and toughness of the rachis.The gradual distribution of mechanical properties improves both the overall strength and energy dissipation capacity of the cortical layer of the rachis.The analysis and study of the strength-toughness coordination mechanism of feathers provides a solid theoretical support and biological basis for the design and preparation of biomimetic composite materials.In the design and preparation of biomimetic composite materials,inspired by the reinforcing mechanism of the reshaping and interlocking microstructure of feather barbs,a two-step hydrothermal modification strategy was adopted to construct a biomimetic mechanical interlocking interface based on dopamine-functionalized carbon fibers and zinc oxide nanorods.The flexural strength and interlaminar shear strength(ILSS)of the fiber laminated board were increased by 40.02% and 101.63%respectively.Inspired by the toughening mechanism of the graded porous bone structure of feather shaft medullary,a three-dimensional interconnected biomimetic skeleton structure was constructed in brittle epoxy resin.The flexural strength and fracture toughness of the epoxy resin were increased by 43.92% and 111.43%respectively,and the brittle catastrophic failure mode was transformed into a stable crack propagation mode.Inspired by the interlocking structure enhancement and skeleton structure toughening,strong and tough coordinated fiber composites were prepared using freeze-thaw cycles and freeze-drying methods.The bending strength and ILSS were increased by 99.85% and 30.97% respectively,and the type II interlaminar fracture toughness was increased by 25.78%.Aiming at the strengthtoughness coordination mechanism of the gradation fiber microstructure of feather shaft cortex,strong and tough biomimetic fiber composite components were prepared,and the coupling effect of different fiber types,fiber hybrid structures,and hybrid ratios on the strong and tough indicators of fiber composite components was investigated.In summary,this article takes the wing feather of a typical large raptor,the black kite,as a biomimetic prototype to study and reveal the strength-toughness coordination mechanism of the microstructure of black kite’s wing feather.Inspired by this,high-strength,high-toughness,and strength-toughness coordinated fiber composite materials have been designed and prepared,providing new design ideas and technical support for improving the overall mechanical performance of traditional fiber composite materials and components.
Keywords/Search Tags:Flying feathers, Microstructure, Biomimetic design, Fiber reinforced composite, Strength-toughness coordination mechanism
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