Abstract: Derail phenomenon and impact events between horizontal wheels and circular track are the most important issues for contact analysis under strong earthquake. Traditional response spectrum method requires the wheel-rail to be bundled, therefore different structure parts cannot be separated from each other, thus the mentioned phenomenon are difficult to be simulated. First, the kinetic equations are set based on the non-smooth dynamic methods reflecting the contact/impact effect between different structure parts of the nuclear polar crane. Second, model smoothing method is used to filter out the high frequency elastic component, which makes the simulation of the system equations have both simplicity and convenience. Then, the contact force between wheel and rail is simplified as normal forces and frictional forces of contact points. Moreover, modified Coulomb's law for dry friction is employed to describe frictional forces. A smoothing linear complementarity formula is raised to calculate the dynamic contact forces between flexible bodies, the presented method can comprehensive consider the smooth contact and impact without changing contact force model when the contact status change. Meanwhile, the discontinuity of the resistance force is smoothed according to the method of dealing with the switching effects in the Coulomb's law, hence the numerical difficulties have been overcome. Finally, numerical results detect the derail phenomenon under strong earthquake. These results prove the feasibility and possibility of this algorism and program being used for guiding development of the design process of the nuclear polar crane.

Key words: nuclear polar crane, non-smooth, linear complementarity problem, contact/impact, flexible multibody system