The screw flight, spiral blade welded on the axial cylinder, is the core component of the screw ship unloader and can be seriously worn by the materials during long-term conveying. The damaged screw flight will make the screw ship unloader unable to unload materials or even lead to an accident. However, the existing wear model cannot be directly applied to predict the wear of the screw flight under different working conditions. Hence, we established a new screw flight wear model based on the Archard wear model and Continuous Medium Hypothesis to predict the service life of the screw flight. Three influencing factors, including speed, filling rate, and pitch, were selected to study the wear law of the screw flight, and the wear law was verified by EDEM simulation. Results indicate that the simulation results affected by the changes in various factors were consistent with the calculation model. With the increase of rotation speed and filling rate, the screw flight wear rate increased. Nevertheless, with the increase of pitch, the screw flight wear rate first increased and then decreased. The screw flight wear model can be used to calculate the wear rate under different working conditions for the screw flight life prediction.

This study employed a three-level cyclic loading path to investigate the mechanical behavior of sandstone across different failure stages under constant-amplitude cyclic loading. The loading path encompassed the initial crack closure, elastic deformation, and crack propagation stages. The mechanical behavior at each stage was characterized by analyzing deformation response, energy evolution, and acoustic emission (AE) characteristics. The results indicated that the mechanical response of the rock sample exhibited distinct stage-specific characteristics. In the unstable crack propagation stage, the elastic modulus decreased rapidly, the damage energy increased continuously, and both the number of AE events and the associated energy increased significantly. The average peak stress reduction per unit cycle during the unstable crack propagation stage exceeded that during the elastic deformation stage by more than two orders of magnitude. The elastic modulus was highest in the stable crack propagation stage, followed by the elastic deformation stage, and lowest in the initial crack closure stage. Throughout the crack propagation stage, each stress drop was accompanied by a pronounced surge in AE counts and energy, indicating that these stress reductions resulted from the localized propagation and coalescence of internal cracks.

Numerical study was performed to determine the fatigue limit of metallic glass under tension-compression cyclic loading. A revised free-volume theory which considers the hydrostatic stress was utilized to make the predictions. Systematical simulations showed that a higher strain amplitude is prone to making the sample completely damaged earlier. However, lower strain fluctuations could result in a longer fatigue life. Shear banding evolution history described by free-volume localization could reasonably explain the mechanical responses of different samples. In addition, compressive loading could give rise to a higher stress than that under tensile loading because of hydrostatic stress contribution. In the end, a correlation between fatigue life and applied strain amplitude was plotted which could supply a guidance for designing the engineering application of metallic glass under periodic loading.