  Conversion of heat-flux, from a steady state temperature difference, to
mechanical vibration is demonstrated in graphene nanoribbons using direct
non-equilibrium molecular dynamics (NEMD). We observe that this effect is
independent of the method of imposing the temperature gradient, heat flux as
well as imposed boundary conditions. We propose that simply dividing the
nanoribbon in long and short sections using a partially immobilized area will
lead to excitation of long-wavelength vibrations in the long section of the
nanoribbon. This results in simpler architectures for heat-to-vibration
converter devices based on graphene or other 2D materials. Furthermore we
observe that applying tensile axial strain to nanoribbons, facilitates
vibrational instability by reducing the required threshold heat flux or
temperature gradient. Finally, we discuss the role played by Umklapp scattering
for physical mechanisms behind these observations.
