  We study the analogue of optical frequency combs in driven nonlinear phononic
systems, and present a new generation mechanism for phononic frequency combs
via nonlinear resonances. The nonlinear resonance refers to the simultaneous
excitation of a set of phonon modes by the external driving, and thereby
generated frequency combs are characterized by an array of equidistant spectral
lines in the spectrum of each nonlinearly excited phonon mode. Frequency combs
via nonlinear resonance of different orders are investigated, and particularly
we reveal the possibility for correlation tailoring in higher order cases. The
investigation contributes to potential applications in various nonlinear
acoustic processes, such as harvesting phonons and generating phonon
entanglements, and can also be generalized to other nonlinear systems.
