Numerical Simulation Study Of Fretting Wear Of DLC Coating Materials

Fretting is a relative movement of micro and nano-scales occurs at two connected parts.Because the displacement amplitude is very small,it has often been overlooked in industry.The fretting damage caused by fretting wear will threaten the service life of machines,and the occurrence of fretting wear is unavoidable.Therefore,it is called the “undead cancer” in industry.With the development of surface engineering technology,a layer of wear-resistant material is coated on the surface of important parts to achieve the purpose of extending service life.Diamond-like Carbon(DLC)materials are widely used due to their excellent tribological properties.However,the wear performance of DLC materials is mostly studied by experimental research: designing and manufacturing the DLC overcoat and testing its performance.Numerical simulation of DLC overcoat is rarely investigated,especially the DLC overcoat is partially penetrated.Based on the existing fretting damage theory,the distribution of contact stress at spherical/plane interface was calculated.In the prediction of fretting damage,the effects of friction coefficient of material and shear stress on the comprehensive coefficient were analyzed by Ruiz criterion.In addition,a node updating method used for large wear depth was proposed,which can avoid the termination of finite element analysis when the wear depth is large than the element length.Therefore,an adaptive cycle jump method for accelerating numerical calculation was proposed.This method can significantly i reduce computer cost.The two-dimensional fretting wear model of cylinder and plane was developed.The wear profile of the plane was calculated by the local wear equation derived from the Archard wear equation.Using this model,the effects of cylinder geometry radius,load and elastic modulus on wear profile of the plane were studied.The orthogonal experiment was used to analyze the significance of the parameters,which provides a theory guidance for industry.Based on the two-dimensional cylindrical and planar fretting wear model,a fretting wear model with DLC coating was developed.In order to study the effect of partial penetration of DLC on wear performance,a node updating method suitable for coatings was proposed.The effects of coating thickness and slip amplitude on wear performance were studied.The results provide reliable theoretical analysis and reference for the design of DLC coating.