Spatial Reduced Dynamic Model of a Bucket Wheel Excavator with Two Masts

A holistic approach to analyzing the dynamic behaviour of a bucket wheel excavator (BWE) superstructure, which is practically neglected by technical regulations but nowadays widely used during their design and redesign, is presented in the paper. The procedure for determining the potential and kinetic energy and the vector of generalized non-potential forces of the system, leading to the development of a reduced spatial dynamic (RD) model of the BWE with two masts is presented in detail. Direct validation of the established model has been performed by comparing the values obtained for the first ten natural frequencies (NFs) of the finite element (FE) model to those obtained by the RD model. Percent deviations of values of the NFs obtained for the RD model are very low compared to those obtained by the FE model (~1% for three fundamental NFs). Indirect validation of the RD model used in this research i.e. validation of values of the NFs which have been obtained by calculation and the respective modal deflection shapes has been achieved by comparing them to the studies containing the results of numerical-experimental research on the dynamic characteristics of BWEs of the same design concept. The values of NFs are of the same order of magnitude and the corresponding deflection shapes are in full compliance with those of the experimentally-analyzed BWEs.