Trans-scale rough surface contact model based on molecular dynamics method: Simulation, modeling and experimental verification

Abstract

Contact interfaces widely exist in mechanical structures from macroscopic to microscopic scales and play an important role in understanding the properties and dynamics of the structures. To obtain the contact behavior, it is essential to include the plastic deformation characteristics on rough surfaces (caused by dislocation in asperity), while they are not properly considered in the traditional macroscopic models. This work presents a trans-scale rough surface contact model with the combination of the macroscopic model and the microscopic deformation mechanism by MD simulation. (I) Based on the molecular dynamics (MD) simulation results of a single-asperity normal contact, the relationship between the critical interference and the asperity size is fitted. The results show that the critical interference of the asperity is affected by its size, especially at the microscopic scale. Large asperity produces small critical interference. (II) A trans-scale rough surface contact model was established based on the fitted curves, which considered the joint distribution of asperity radius and height and the asperity size effect. (III) The influence of parameters was analyzed, and the predicted results of the proposed model and the traditional models were compared with the experimental results and MD simulation results. The results show that compared with other traditional models, the proposed trans-scale model has better performance in describing the normal contact characteristics of rough surfaces at both macroscopic and microscopic scales, showing the ability of full-scale description.