Laboratory for Dynamics of Machines and Structures 
Nonlinear Model Reduction in Dynamic Substructuring

Dynamic analysis of complex structures can be very demanding, therefore such structures are being divided into several substructures. Each of the substructures is analysed separately and the number of degrees of freedom is reduced using model order reduction methods. Then the initial structure is obtained by assembly of the reduced substructures, providing faster analysis. In the first part of the dissertation geometrically linear formulation of the finite element and Craig–Bampton model reduction method is presented. In the second part of the dissertation the finite element formulation is upgraded using nonlinear displacement – deformation relations. Due to the geometrical nonlinearity of the system also reduction methods have to be upgraded. The comparison of the beam dynamic responses, obtained by analytical equations, finite element analysis of the complete structure and use of model reduction method indicates good correspondence within the selected frequency interval.