An automatic sub-structuring method applicable in the low- and medium-frequency ranges is proposed. This method is developed using a simplified model constructed using an energy method in a stochastic context. The proposed energy method, although inspired from the Statistical Energy Analysis (SEA), it differs from it and is applicable in the low- and medium-frequency ranges when using a statistical computational model. The nonparametric probabilistic approach for system parameters and model uncertainties is used to construct this statistical model. Main results of the energy method are ; dimensionless random frequency response functions (FRF) which are shown to be less dispersed than the usual dimensional ones and independent of the direction of excitation, a simplified vibroacoustic model, and finally the automatic sub-structuring method which is obtained from the simplified model using the theory of information.
