Analysis And Design Of Light-weight Material System With Special Dynamics Characteristic

With contemporary shortage of energy and resources,research and design of lightweight structure have drawn great attention.Systems of light-weight material have been a research focus both at home and abroad and found wide background of applications in aerospace and transportation industries.Among them cellular-type structure has been widely applied to structural design as an important part of lightweight material.Traditionally,the study of light-weight material is concentrated on pursuing high strength and stiffness per unit volume.Recently,people start to focus on multi-functional,such as insulation,noise reduction and so on.However,the dynamic design for the light-weight system is rare to find,and investigation on designing specific dynamic properties is almost nowhere to find which needs further efforts.This thesis is funded by The National Science Foundation of China(projects 90816025, 10721062) and The National Basic Research Program of China(project 2006CB601205).The lightweight planar cellular structures are studied in this thesis.A light porous structure with particular dynamic characteristics is proposed to be designed which provides a theoretical basis for the future non-linear dynamic design of light-weight systems.The research work can be summarized as follows:(1)The infinite cellular(honeycomb-shaped) plate is modeled as spring with nonlinear load-displacement relationship under external force.Each coefficient of the non-linear stiffness in a polynomial expression is fitted by using ANSYS software to simulate the spring's loading process.(2)Based on the polynomial expression,the dynamic model of the equivalent spring-mass system is composited,and then solved to obtain the equilibrium points of system and analyzed for stability of those points(3) Dynamics in a non-damping case of free vibration is discussed at first using an analytical method.Then,the dynamic equation of a damped,forced vibration system is developed.The amplitude-frequency response curves of the principal resonance, sub-harmonic resonance and super-harmonic resonance are determined,while the stability of periodic solutions is discussed.Appearance of unique behavior of non-linear system dynamics is analyzed,such as the jump phenomenon.