Atomistic scale fracture behavior of the bcc iron with {1 1 0} crack under dynamic rectangular loading rate

Abstract

Dynamic rectangular loading rate is a typical characteristic of the load on tooth root with gear transmission. Upload ratio and contact ratio are its key engineering factors. This work investigates the atomistic scale fracture behavior of bcc iron with {1 1 0} crack under dynamic rectangular loading rate through molecular dynamics simulation, where four crack fronts are considered to illustrate the orientation effect induced by the anisotropy of bcc iron at atomistic scale. The behavior of engineering stress-strain and atomistic scale behavior of crack propagation under various upload ratios and contact ratios are identified to clarify the effect of dynamic load. The {1 1 0} cracks with fronts of [1¯1¯2], [101¯], and [1¯1¯1¯] can propagate not only at model plastic deformation stage under low upload ratio or high contact ratio but also at model elastic deformation stage under high upload ratio or low contact ratio. However, the {1 1 0} crack with front of [01¯0] can propagate at model elastic deformation stage whatever the upload ratio and contact ratio are. According to the critical stress intensity factor for first partial dislocation nucleation and the variation of initiation stress with upload ratio and contact ratio, [01¯0] is proved to be the most dangerous crack front. Considering orientation and key engineering factor effects, this work can well satisfy engineering practice to analyze the atomistic scale mechanism of gear tooth breakage.