Modal analysis and estimation of the calculation errors

The integration of the system equations with modal analysis must be carried out for the lower modes, which excite the system in a dynamical manner. An upper value for this eigenfrequencies can be given by the load function. To integrate the modal differential equations the exact solution as a transfer method is used. This time saving formulation is unconditional stable. The error-influence of the non considered modes for the displacements, accelerations and stresses is predicted with a simple static solution, because for the high modes the system response is quasi static. It is not necessary to know the higher modes. (orig.)