Coupled fluid-dynamical and structural analysis of a mono-axial mems accelerometer

This study is aimed to numerically investigate the elastodynamicalbehavior of a mono-axial MEMS accelerometer. The vibrating part of thedevice is dipped into a fluid micro-channel and made of a proof massconnected to the frame by two flexible legs. The adopted mathematicalmodel lies on a linearized motion equations system, where the massmatrix is obtained by means of both lumped and distributed approach.The stiffness matrix is otherwise derived through FEA, in which the proofmass and the compliant legs are modeled as rigid and flexible bodies,respectively. The squeezed-film damping effect is evaluated by a fluiddynamicalFE model based on a modified Reynolds formulation. Theensuing analyses are carried-out for three pressure levels of the narrowgas film surrounding the device, by applying a logarithmic decrementmethod for evaluating the damping ratio. Numerical results, in terms ofacceleration, frequency range and noise disturbance, are successfullycompared to analytical and experimental ones previously published inliterature. Our model completely characterizes the accelerometerdynamics in space, allowing in addition to assess translational motionerrors along directions apart the working one.