By means of Hamilton variational principle, a nonlinear flexural wave equation for beams taking account of the geometric nonlinearity caused by the large deflection and the dispersive effect of rotational inertia in the beams is derived in this paper. Results of qualitative analysis of the nonlinear evolution equation show that for the equation there exists homoclinic or heteroclinic orbits on the phase plane, which correspond to a solitary wave or shock wave solution, respectively. Nonlinear flexural wave ...