Design,Modeling And Analysis Of Biomimetic Staggered Composite Structures

The spacecraft will be excited by vibration as low as several hertz and as high as thousands of hertz in the process of launching.The severe vibration and impact load make the safety and reliability of the space mission seriously threatened.With the increasing requirement of spacecraft for structural vibration reduction,it is more and more difficult for traditional engineering structures to balance the contradiction between bearing capacity and mass constraints.In order to solve this problem,inspired by the fact that goats can easily deal with the impact of landing when running and jumping between cliffs,this paper proposes a bionic vibration damping structure design idea based on the microstructure of goat’s leg bones.In this study,a systematic research on structure investigation of cortical bone,composite structure design,mechanical modeling,numerical simulation and bioinspired staggered composite structure experiment is carried out.The main work of this dissertation can be summarized as follows:1.The microscopic structure of cortical bone in goat tibia is investigated,and the main structural characteristics related to the mechanical properties of bone are extracted.A novel biomimetic staggered composite structure with porosity is preliminarily designed.(1)Bone samples capable of displaying the transverse and longitudinal cross sections of cortical bone in goat tibia are prepared.The multi-scale structural characteristics of cortical bone in different growth directions are observed by scanning electron microscope.Then three-dimensional hierarchical structure of cortical bone is obtained.(2)The relationships between the microstructure of cortical bone and its mechanical properties are analyzed to extract the main structural features.Based on the staggered composite structure,a partial self-similar hierarchical structure model is proposed for cortical bone.At last,a novel biomimetic staggered composite structure with porosity is preliminarily designed.2.The constitutive models of biomimetic staggered composite structures are established,and the influence of structural parameters on the mechanical properties is analyzed.Numerical simulations validate the the constitutive models.(1)A linear elastic constitutive model of the 2D biomimetic staggered composite structure is established based on the tension-shear chain model,and the strength of the structure is obtained according to the material strength theory.Then the biomimetic staggered composite structure design is completed.The linear elastic constitutive model of the novel 2D biomimetic staggered composite structure with pores is also established.Effect of the structural parameters on the mechanical properties of biomimetic staggered composite structures is analyzed and the verification of the constitutive models is carried out by numerical simulations.(2)Based on the shear-lag model,linear elastic constitutive model of the 3D biomimetic staggered composite structure is established,and stress distribution and mechanical properties of the structure are analyzed.A novel 3D biomimetic staggered composite structure with pores is designed,and the shear-lag model is extended to obtain the stress distribution law in the new structure.The verification for theoretical analysis is conducted by numerical simulations.The results show that the pores designed can significantly improve the uniformity of stress distribution in the biomimetic staggered composite structure,and the novel composite structure has higher specific elastic modulus,specific strength and specific energy storage capacity.(3)Linear viscoelastic constitutive models of 2D biomimetic staggered composite structures are established,and variation regularities of the loss modulus and the loss factor of different composite structures with structural parameters are compared.It is found that both the biomimetic staggered composite structures have high damping density ratio.Numerical simulations are carried out to validate the constitutive models.3.In order to verify the feasibility of biomimetic staggered composite structure design,the test specimens of biomimetic composite structures are manufactured and their mechanical properties are tested.(1)According to whether there are pores,two kinds of bioinspired staggered composite structures specimens are designed,and they are manufactured by highprecision multi-component 3D printing technology.(2)The mechanical properties of the biomimetic staggered composite structures are tested.The experimental phenomena and data are analyzed.At last,the test results are compared with the values calculated from the constitutive models.The feasibility of biomimetic staggered composite structure design is preliminarily verified.Through the study of this paper,the brief development process of a novel biomimetic composite structure from design to experiment is completed,and relationship between the structure parameters and the mechanical properties including strength,elastic modulus and damping is achieved for the new composite.This reaserch can provide a theoretical reference for the application of biomimetic composite structures in the field of aerospace engineering.