Abstract: In this paper the problem of a circular beam subjected to radial impact by a rigid mass at its lip in its own plane is investigaleil on the basis of rigid-perfectly plastic assumption. The analytical solution of the particle velocities is obtained as the junction of travelling plastic hinge location. Ky analysing the solution, some special properties oj circular beam problem are found.

Key words: streamline diffusion method, finite difference method, nonconforming finite element method, time-dependent linearized Navier-Stokes equations, error estimate