The pull-in instability and eigenfrequency variations of a graphene resonator under electrostatic loading

A continuum membrane model is presented to describe the pull-in instability and eigenfrequency variations of a graphene resonator under an electrostatic loading. The pull-in instability leads to the device failure and the eigenfrequency variation determines its frequency tuning range, which are among the most important aspects in a micro/nanomechanical resonator design. The von Karman kinematic assumptions are used for the membrane large deflection. The geometric nonlinearity resulting from a large deflection and the physical nonlinearity resulting from an electrostatic loading are the two competing mechanisms: the geometric nonlinearity stiffens the membrane structure and the physical nonlinearity softens it. The effects of these two competing mechanisms together with the initial tensile strain on the pull-in instability and eigenfrequency variations are vividly demonstrated. With the aim of achieving a higher accuracy, a multimodal computation method together with its convergence study and error analysis is also presented.