Analysis of the primary and superharmonic contact resonances – Part 1

This paper presents results of numerical and analytical investigations of non-linear normal contact microvibrations excited by a harmonic force in a system of two bodies in planar contact. The system models, for example, the slide unit of machine tools or positioning systems. The main aim of the computational analysis is to present the evolution of the resonance phenomena under various amplitudes of the excitation force. The studies show that, beside the primary resonance, a number of superharmonic resonances appear, which take place in the single-degree-of-freedom non-linear system excited by a harmonic force. Thus, in a resonance plot, a number of peaks is observed. The superharmonic (ultraharmonic) resonances take place at excitation frequencies being below the natural frequency, and becoming stronger with the increase of the excitation amplitude. The resonances are coupled with complex non-linear phenomena like: asymmetry of vibrations, bending resonance peak, bi-stability, multi-stability and loss of contact, which are presented and described in this paper.