Fatigue Damage Mechanism and Deformation Behaviour of Granite Under Ultrahigh-Frequency Cyclic Loading Conditions

Ultrasonic vibration-assisted rock breaking is a potentially effective technique to accelerate hard drilling processes. Fatigue damage primary factor that governs fragmentation subject ultrasonic vibration, and when such accumulates critical level via crack initiation propagation, macro-damage (e.g., macro-cracks) will occur. To date, however, the specific fatigue mechanism of materials under high-frequency low-amplitude cyclic loading conditions still unclear. In present study, we applied 2D digital image correlation (2D-DIC) method measure full-field strain in granite samples with different amplitudes. From these deformation data, threshold value for vibration was obtained, it also found logarithm time required meet this decreases linearly an increasing amplitude coefficient. Then, conducted numerical simulation based on particle flow code (PFC2D) reproduce propagation processes explore their mechanisms. The results from show due irreversible sliding difference displacement between particles either side tip increase, which leads increase concentrated lateral tensile stress. When stress exceeds strength limit, initiate propagate, resulting rocks.