<p>While a great deal of research has been devoted to the theoretical analysis of micro and nanoelectromechanical (M/NEMS) resonators operating in the nonlinear periodic and chaotic regimes, only recently the relevance of including the contribution of nonlinear damping in the modeling has become more evident. In this work we perform a review and critical analysis of the known nonlinear damping mechanisms for suspended beam resonators, concluding that the nonlinear damping can easily dominate over the linear one when operating in a chaotic regime. Motivated by these results, we extended previous theoretical analysis of chaotification in M/NEMS beam resonators actuated electrostatically by two-sided electrodes and included the contribution of different types of nonlinear damping mechanisms, ignored so far. Two types of effective cubic nonlinear damping terms and the nonlinear squeeze film damping are considered. We investigate the chaotification considering single and two excitation frequencies. It is concluded that nonlinear damping has the potential to change significantly the regions in the relevant phase space of the system where chaos is observed, as well as, the complexity of the chaotic dynamics. The analysis favors the use of systems excited by two different frequencies and with small linear and nonlinear damping as sources of chaotic signals.</p>