Modeling and Analysis of the Time-Dependent Contact Behavior of Multiscale Rough Surfaces Subjected to Random Shocks

摘要

In complex operational environments, random shocks change the contact behavior of rough surfaces, resulting in time-dependent and uncertain characteristics, which further affect their friction, wear, and lubrication properties. However, in the currently available impact models, only deterministic shocks are considered at surfaces in contact and the evolution of contact behavior over time is ignored, which is detrimental in many engineering applications. Therefore, in the current study, a model based on elastic-plastic deformation and the loading/unloading contact theory is proposed to analyze the time-dependent behavior of contacting asperities; this model is affected by two characteristic parameters of random shocks, viz. shock magnitude and interarrival time. The corresponding contact variables of surfaces were deduced using the multiscale Jackson and Streator model while individual asperities were assumed to be power law hardening materials under stick contact conditions to comply better with physical reality. Furthermore, experimental results on AISI 1045 steel ring contact pairs considering the shock effect were compared with predictions made by the theoretical model; the reasonable difference between the two sets of results illustrates the effectiveness of the current approach. In addition, the impact of the strain hardening exponent, shock properties, and sample size on the time-dependent surface load is discussed. These insights can potentially help in analyzing the time-dependent wear behavior of multiscale rough surfaces.