Highly Accurate Rock Simulation System Based on Gas-Liquid Coupling Mechanism with Non- Harmonic Impact of Variable Stiffness and Damping Characteristics

Abstract The rock simulation system is of great significance for the development of high-frequency high-power hydraulic rock drills. It can simulate different rock drilling conditions in specific environments and observe the drilling effects under multi-scale conditions. This paper proposes a multi-stage adjustable rock simulation system with variable stiffness and damping. Firstly, based on the Kelvin rock theory, a rock vibration model under non-harmonic excitation is established. Combining the characteristics of adaptive oil-gas suspension rigidity locking, the rock simulation system and rock drilling impact system are designed. A nonlinear stiffness and damping model of the simulation system is established based on fluid mechanics theory. The drilling dynamic characteristics of the simulation system are studied using Amesim software, and nonlinear stiffness and damping curves of granite and the simulation system are drawn according to the dynamic parameters of rock drilling. Secondly, a drop hammer calibration experiment and an impact rock drilling experiment of the simulation system are designed. Finally, the nonlinear stiffness and damping characteristics of the simulation system in actual rock drilling are studied, and the validity of the simulation model is verified. The method proposed uses hydraulic oil as the supporting medium and nitrogen as the elastic medium, effectively addressing the challenge of detecting the impact characteristics of rock drills under specific operating conditions. Simulation results indicate that as the stiffness of granite and the simulation system decreases, the drilling displacement increases, while increasing damping coefficients lead to smaller drilling displacements. Experimental results demonstrate that the stiffness-damping error between the simulation system and granite does not exceed 10%. And the movement frequency of the simulation system's hydraulic cylinder is closely aligned with the impact frequency of the rock drill.