Analysis Of Wrinkles On The Surface Of Stiff Film/Soft Substrate System

Soft substrate coated with stiff thin film,subjected to axial compression,will buckle and form surface wrinkles.Recent years,surface wrinkles receive huge attention from academic community for wide applications including MEMS.In this paper,we introduced the mechanical background and experimental preparation methods of stiff film/soft system,as well as the induction methods.We also followed Kirchhoff-Love theory,treating film as the thin plate on elastic base,then calculated the corresponding buckling critical strain,and analyzed how this critical value is affected by material parameters including Young's modulus,Poisson's ratio and geometric parameters including length of film,width of film,and thickness of film.As to the case applied strain is larger than critical strain,we used finite deformation theory and energy method to calculate the central amplitude and marginal amplitude,that illustrated how surface morphology is affected by material and geometric parameters.Furthermore,we started from point of view of propagation of elastic wave,treated wrinkles as the special case when surface wave speed is down to zero,and tended to establish the theoretical model of orthogonal film/hyperelastic substrate system,as the base for further research.At last,using linear perturbation analysis of ABAQUS,we calculated first several buckling modes,and selected appropriate modes as initial imperfection to be introduced into post-buckle analysis,and used Riks method and explicit dynamics method to calculate the morphology;compared results of 3D simulation with our theoretical analysis.