Reduced-Order Modelling for Investigating Nonlinear FEM Systems

Modern finite element (FE) packages are capable of capturing nonlinear behaviour in extremely complex structures. However, due to the scale of these models, full dynamic analysis is often prohibitively expensive. An alternative approach is to use the FE models to derive reduced-order models (ROMs) which capture the dynamic behaviour of interest at a significantly lower computational cost. An automatic identification of the stated ROMs is powerful and desirable when parametric, sensitivity and uncertainty analysis is of interest. The authors implemented in Matlab a strategy to automatically compute the reduced order model and investigate the effects of parametric variation exchanging information with FEM software. In the strategy it is adopted the Applied Modal Force (AMF) approach, where a force is applied to the FE model and the resulting displacements are used to identify coefficients of the ROM, as is done in the ICE method. The developed techniques are presented in the paper and validated considering a crossed beam structure modelled in Abaqus.