Modeling of nonlinear interaction and its effects on the dynamics of a vibrator-ground system

Abstract

The nonlinear interaction between a vibrator and the ground is one of the main sources of signal distortion in land exploration. So, it is crucial to describe this nonlinear interaction and study how it affects the outgoing wave radiated by the vibrator. For this purpose, an approach is developed to obtain the equivalent ground stiffness and damping using a fractal contact model with the half-space method. Both the impacts of surface topography and the dynamics of ground are accounted for innovatively in this approach. The results show that both the ground stiffness and damping increase with the total deformation load but decrease with the excitation frequency and roughness. In addition, a modified two-degree-of-freedom vibration model of the vibrator–ground system is proposed to calculate the output force of the vibrator for different rough surface topographies. A field test is used to verify the theoretical model, and it is concluded that compared with the theoretical excitation signal, the output force varies with the excitation frequency. The amplitude of the output force in the high-frequency phase decreases for a rougher contact surface, as does the resonance frequency of the system. Moreover, reducing the mass of the baseplate is an efficient way to improve the high-frequency output.