A COMBINED DYNAMIC-STATIC FINITE-ELEMENT MODEL FOR THE CALCULATION OFDYNAMIC STRESSES AT CRITICAL LOCATIONS

The following paper addresses the validation of a dynamic-static finit e element model for calculating stresses at critical locations of a st ructure to be used for fatigue life prediction. The method combines a dynamic finite element model of the global structure and a static fini te element model of the critical part(s). The global dynamic model yie lds the internal forces at the global-local interface which are applie d at the boundaries of the static finite element model and yields the displacements of the local model which are transformed into nodal iner tial forces through an appropriate interpolation of the mass distribut ion. Frequency response functions (FRFs) regarding stress/excitation c an then be obtained by a static finite element calculation on the loca l model. The global-local approach presented in this paper to calculat e stresses is compared to a superelement approach. The superelement ap proach is based on the division of the global model into submodels and on the application of efficient reduction techniques. It is shown tha t if an accurate finite element model (as far as the dynamical behavio ur is concerned) of the global structure can be built then the combine d dynamic-static method (or global-local method) should be preferred b ecause simple models are involved, less CPU time is required, sensitiv ity analysis with respect to local structural modifications is straigh tforward. Still the results are accurate compared to the one obtained from the classical methods. (C) 1997 Elsevier Science Ltd.