超高周疲劳作用下花岗岩裂纹演化过程研究

Study on Crack Evolution Process of Granite under Ultra-high Cycle Fatigue

为探索超高周疲劳作用下花岗岩内部裂纹的演化机理,构建符合矿物实际分布特征的颗粒流模型,对其进行超声疲劳加载,通过超声疲劳试验加以验证。结果表明:超高周疲劳作用下,花岗岩微裂纹主要由拉张应力机制产生的。在宏观裂纹出现前,矿物晶体边界微裂纹占主导,随宏观裂纹出现,晶内裂纹占比逐渐增大并处于主导地位。

To explore the evolution mechanism of cracks inside granite under ultra-high cycle fatigue, the particle flow code (PFC) in line with actual distribution characteristics of minerals, was established, and then was loaded by ultrasonic fatigue and verified by ultrasonic fatigue test. The result shows that, under the action of ultra-high cycle fatigue, the microcracks inside granite are caused by tensile stress mechanism mainly and, before the occurrence of macrocracks, the microcracks dominate over the boundary of mineral crystal, and then as the macrocracks arise, the intragranular cracks gradually have more share till play a dominant role.