Effect of frequency on rock's mechanical responses under multi-level compressive cyclic loading: an experimental investigation

This article aims to investigate the impact of frequency sequence on mechanical responses of sandstone exposed to multi-level compressive cyclic loading. Two modes were used with three levels of low frequencies (0.1, 0.2, and 0.4 Hz) in incremental or decremental sequences. The analysis was made on rock deformation, energy characteristics and stress-strain phase shift. The experimental results show that frequency sequence has a significant effect on various types of mechanical properties. The decremental frequency causes a greater growth in axial strain at maximum cyclic stress than at the minimum stress. The input and elastic energy are enhanced under incremental frequency sequence, while decremental frequency results in a higher occurrence ratio of phase lag, particularly in the radial direction. These experimental findings can help to deepen the understanding of rock fatigue from the view of frequency sequence.

Automated summary

This article investigates the impact of frequency sequence on mechanical responses of sandstone under multi-level compressive cyclic loading. Experimental results show that frequency sequence significantly affects various mechanical properties. Decremental frequency leads to a greater growth in axial strain at maximum cyclic stress compared to the minimum stress. Incremental frequency enhances input and elastic energy, while decremental frequency results in a higher occurrence ratio of phase lag, particularly in the radial direction. These findings deepen the understanding of rock fatigue from the perspective of frequency sequence.