Research On Mechanical Properties Of Functionally Graded Shape Memory Polymer Composites And Its Application In Deformable Aircraft Skins

Functionally graded material(FGM)and shape memory material(SMM),as intelligent materials,are both emerging hot topics in the material field.It has a wide range of applications in engineering,aerospace and other fields.This paper proposes a new type of smart material,that is,Functional Graded Shape Memory Polymer Composites(FG-SMPC),which is characterized by the SMP matrix and the reinforcement phase present in the spatial position of the composition Gradually change.The contents of the research are as follows:In this paper,random shorted carbon fiber was used as reinforcement phase,and the function Vf(z)of the volume fraction of reinforcement phase with the position of the material thickness layer was given.FG-SMPC material was designed flexibly by setting the equivalent value of the gradient change factor P and the upper limit of carbon fiber content Vfmax.According to Halpin-Tsai composite material formula and elastic mechanics theory,the mechanical models of FG-SMPC material structure model under different conditions,such as uniaxial tension,pure bending and linear load,are presented.Through numerical analysis,the expressions of the elastic modulus,thermal expansion coefficient and other parameters of FG-SMPC with the position of the thickness layer were derived.The stress and strain distributions of FG-SMPC in different stages of shape memory under uniaxial tensile and pure bending conditions were obtained,and the influence of related variables on the mechanical properties of FG-SMPC under different conditions was discussed.In addition,in order to further explain the potential of FG-SMPC material,this paper explores the application of FG-SMPC material in the field of deformable wing skin material,and compiles a random staple fiber production program to model the deformable skin structure based on FG-SMPC material and analyze the deformation under static state.It was compared with the deformed skin of SMP and SMPC.The influences of pre-strain type,Vfmax of carbon fiber content and temperature on the stress and shape memory behavior were discussed.