Comprehensive nonlinear electromechanical analysis of nanobeams under DC/AC voltages based on consistent couple-stress theory

The paper analyzes the nonlinear electromechanical behavior of nanobeams under electrostatic actuation based on the recently developed consistent couple stress theory. The effects of interatomic forces including the Casimir force and van der Waals interaction are analyzed. The static and dynamic pull-in instabilities are investigated for the nanobeams with cantilever and doubly clamped boundary conditions. According to the results, the applied theory leads to models with higher stiffness and consequently, higher frequencies and pull-in voltages. The results prove that, for large gaps, the cantilever nanobeams show softening behavior and the doubly clamped ones presents hardening characteristics. In the nonlinear dynamic part of the research, bifurcation and chaos appear in the latter. Moreover, the formulation and physical concepts applied in some literature are scrutinized and the sources of errors are studied. (C) 2015 Elsevier Ltd. All rights reserved.