On the basis of the proper orthogonal mode (POM) energy, the physical interpretation of the transient proper orthogonal decomposition (TPOD) method is proposed in this paper. A 15-degrees-of-freedom (DOF) rotor-bearing model with looseness at one end is established by the Newton’s second law. The optimal reduced model can be provided based on the physical significance of the TPOD method. The TPOD method is compared with the original POD (OPOD) method, and the first two order POMs verify that the TPOD method is much better. The energy of the first three order POMs obtained by the TPOD method is about 99.99%, however, the OPOD method is less than 70%. The efficiency of the TPOD method is verified by comparing the bifurcation diagram of the original and reduced rotor system. The POM energy method can provide the theoretical guidance to obtain the reduced model.

proper orthogonal decomposition, proper orthogonal mode, rotor-bearing, energy, order reduction.