Analysis Of FG-SMA Micro-Beam Instability Under The Thermal-Mechanical-Electrical Multifield Coupling

Micro-components are the important parts of the Micro-Electro-Mechanical System(MEMS),which mainly consists of micro-beam,micro-plate,micro-film and micro-shell,et al.Through their deformation and displacement,MEMS can achieve sensing and executing.In recent years,with the development of new intelligent materials,researchers have proposed to use Functional Graded Shape Memory Alloy(FG-SMA)into MEMS.As a new type of intelligent material,FG-SMA not only has the property of gradient effect of Functionally Graded Material(FGM),which can avoid or weaken the stress concentration of traditional composite materials caused by component change,but also has the shape memory effect and superelastic properties of Shape Memory Alloy(SMA).Therefore,the research on the pull-in instability,buckling and thermal buckling in thermal-mechanical-electrical mulitifield coupling of the FG-SMA micro-beam,is of great significance to promote the application of FG-SMA into MEMS.This paper will start from the following three aspects:(1)Based on the size effect,create a clamped-clamped FG-SMA micro-beam under the thermal-mechanical-electrical mulitifield coupling.Analyze the geometric parameters,physical parameters,temperature change and the applied load on the model.The governing equations and boundary conditions are derived based on the von Kármán geometric nonlinear theory and the modified coupling stress theory,then,use the Differential Quadrature Method to solve them.(2)Study the mechanical properties of the FG-SMA micro-beam.Based on the model aboved,analyze the micro-beam pull-in instability,buckling and thermal buckling with the effect of size effect parameter,volume fraction index,slenderness ratio,initial gap ratio,electrode shape parameter,temperature change,nonlinear electric force and intermolecular Casimir force.(3)Analyze comprehensively of FG-SMA micro-beam with the effect of geometric parameters,physical parameters,temperature change and applied load on pull-in instability,buckling and thermal buckling.