Analysis of Dynamic Variable Mass and Variable Parameter Systems Applying Semi-analytic Time-Integration

For open dynamic systems with moving boundaries the derivation of the equations of motion and the computation of the solution for the vibrations is discussed. The mechanical model has to consider the variable mass by the flow of mass through the boundary of the applied control volume and the variable parameter of the system in the derivation of the equations of motion. An efficient semi-analytic time-integration algorithm is introduced, analysed with respect to the numerical behaviour and applied to compute the solution of the non-symmetric and non-linear equations of motion. As an example a defined winding process in a Steckel mill is considered and the computed results of some characteristic forces and displacements are shown for given operation conditions.