On the molecular dynamics simulation of fatigue behavior of pre-cracked aluminum chip for NEMS application: Effect of cyclic loading mode and surface roughness geometry

摘要

This study focuses on investigating the dependency of fatigue nanomechanisms to the cyclic loading mode and notch shape in single-crystal aluminum nanoplates by molecular dynamics simulation. Fatigue damage in tension-tension mode is extensively dominated by nanovoids formation and persistent slip bands. Surprisingly, the tension-compression mode leads to nanovoids formation with twofold behavior, de-voiding process and substructure development preventing crack propagation stemming from the reversal strain path. It is proved that crack propagation rate is not sensitive to the notch shape in tension-tension mode. Conversely, sharp notch results in longer fatigue life than blunt notch in tension-compression mode.