Study On The Intelligent Mechanical Characteristic Of Shape Memory Epoxy Polymers And Experimental Investigation

As a new kind of smart shape memory material,Shape Memory Epoxy Polymers(SMEPs)have excellent features such as chemical stability and multipurpose applications.When stimulated by external optical,electrical,mechanical and thermal factors,SMEPs can carry out the smart shape memory process of ‘deformation-memory-recovery’,which entitles it to some beneficial characteristics such as heat distortion,tunable stiffness and large deformation.Thus,SMEPs exist on the expansive engineering application and intelligent memory function in the medical instruments,flexible electronic devices and aerospace components.Taking SMEPs as the research object,this dissertation conducts experimentally and numerically to study the memory characteristics,viscoelasticity and buckling behavior of SMEPs plates through adjusting the content of curing agent.Then,the buckling features of the bilayer cylinder are investigated with theory and measure.The main contents are as follows:(1)The monolayer plates of the SMEPs with four curing agents have are compounded and their circular bending shapes are obtained by means of high temperature experimental fixation method.Then,four kinds of monolayer plates are restored their initial shapes with the dynamic and static ways from indoor to high temperature.At the same time,Deformation data of the online photographs by the industrial camera are computed for the dynamic/static recovery rate.Some curves of the fixed rates at different curing agents and the dynamic/static recovery rates at different temperature are obtained by these deformation data to achieve the intelligent memory function of from ‘bending to unfolding’ for the plates.Furthermore,the viscoelasticity of these monolayer plates for the stress cycle,such as stress relaxation and creep,is investigated experimentally,and their stress-strain curves and Young’s moduli at different temperature are analyzed.Then,the stress-time curves at the glass/high elastic state of stress relaxation and the strain-time curves at the glass/high elastic state of creep stress relaxation are discussed comprehensively.(2)The preparation steps of manufacturing trilayer SMEPs plate and four-point bending-buckling experimental loading process have been shown.The buckling recovery process with rising temperature is observed experimentally.The experimental results of the stress relaxation of thin film and substrates are obtained experimentally to decide the by Pony series in the finite element.These results provide a correct calculation basis for obtaining the buckling morphology of finite element numerical simulation of SMEPs multiplayer plate.The trilayer SMEPs plate model is established with the finite element software and the respective parameters are setting up to simulate its buckling morphology under heating process.And the effects of temperature,displacements,film thickness and substrate thickness on the buckling amplitude and the buckling wave number are studied.These numerical and experimental results are compared to provide a scientific proof for designing new types of shape memory components.(3)Bilayer SMEPs cylinders are designed by good method.It is reasonable data that the displacement loading rate,loading temperature and prestrain are gained through numerous and enough experiments.In the recovering the buckling morphology of bilayer cylinder with heating measure,it is found that it is easier to generate the better buckling morphology almost at a temperature of the glass transition and the appropriate prestrain and the thickness of thin film can produce the excellent buckling morphology at a relative low glass transition temperature.In addition,the effects on the bilayer cylinder morphology,which are caused by the parameters such as prestrain,the diameter of substrate and the thickness of thin film,are discussed.It is concluded that the appropriate parameters are necessary to generate buckling morphology with the comparison between experiments and theoretical results.