Elaso-plastic behavior of micro strings loaded by distributed electrostatic force

The behavior of a micro string (one-dimensional membrane) made of nonlinear inelastic material and subjected to electrostatic force is analyzed. The present work introduces the coupling between material nonlinearity and the commonly considered geometric and electrostatic nonlinearities. The effects of the material softening behavior on the string response and pull-in instability are studied analytically and numerically. Moreover, the accumulation of irreversible stretching and the residual state of the string after unloading are examined. It is suggested that the residual string elongation can be exploited for various applications, including cold forming and residual stress tuning. Analytical and numerical results show that inelastic irreversible deformation can be achieved in strings of realistic dimensions actuated by feasible voltages.