Energy evolution and failure characteristics of red sandstone under discontinuous multilevel fatigue loading

This paper explores the energy storage and dissipation, damage evolution and failure mode characteristics of red sandstone with prefabricated cracks under discontinuous multilevel fatigue (DMLF) loading. It was found that the three energy density parameters increase quadratic polynomial with the increase of stress level. The insertion of creep loading increased energy dissipation during fatigue deformation, but had no significant effect on elastic energy. There was a linear energy storage and dissipation law in the sample loading process, and the strength variation laws of samples with different angles were explained in terms of energy. Fatigue damage accumulated slowly and then increased rapidly with loading, and a damage evolution model was established based on dissipated energy. Moreover, the 0 degrees and 30 degrees samples showed shear failure, while the 45 degrees, 60 degrees, and 90 degrees samples showed tensile-shear composite failure. Combined with macro-micro analysis, the damage mechanism of the samples under DMLF loading was further revealed.

Automated summary

This paper investigates the energy storage and dissipation, damage evolution, and failure mode characteristics of red sandstone with prefabricated cracks under discontinuous multilevel fatigue (DMLF) loading. The results show that the energy density parameters increase quadratically with the increase of stress level. Creep loading enhances energy dissipation during fatigue deformation, but has no significant effect on elastic energy. The accumulation of fatigue damage is initially slow and then rapidly increases with loading, and a damage evolution model based on dissipated energy is introduced.