Research On The Tangential Fretting Wear Properties Of Nickel-Aluminum Bronze Under Ball-on-flat Contact Configuration

Fretting wear,known as the"cancer of modern industry,"is the damage caused by the relative motion of contact surfaces with extremely small displacement amplitudes under alternating loads such as mechanical vibration,fatigue loads,and electromagnetic vibration.Fretting wear is often insidious and difficult to detect,but it can lead to serious consequences such as loose connections and pose a significant hazard.This paper focuses on the material of the adjustable pitch propeller hub-nickel-aluminum bronze（NAB）and investigates the damage mechanism,evolution law,and protective measures of its fretting wear performance using experimental analysis and numerical simulation.The main research contents of this paper are as follows:In order to address the severe wear issue under the operating condition of the hub,ultrasonic rolling process was attempted to improve the physical,chemical,and mechanical properties of nickel aluminum bronze material,and thereby enhance its wear resistance and corrosion resistance.Using a tangential fretting wear test platform,a comparative analysis was first conducted on the microstructure,surface roughness,and surface hardness of pre-and post-treated Cu Ni Al samples by ultrasonic rolling process.Then,the wear resistance and corrosion resistance of the material under different displacement amplitudes,cycle numbers,and lubrication conditions were experimentally investigated.The results showed that the ultrasonic rolling process reduced the surface roughness by 58.0%and increased the surface hardness by 61.8%.The grain size was refined and the friction and wear properties were improved.The study of wear mechanisms under different lubrication conditions revealed that the improvement of wear resistance by ultrasonic rolling process was mainly due to the increase of surface hardness under dry sliding condition,the enhancement of sulfide generation rate of solid lubricant under oil lubrication condition,and the generation of more stable Cu²⁺replacing Cu⁺under seawater lubrication condition.A finite element simulation study of fretting wear under different normal loads,displacement amplitudes,cycle numbers and other parameters was carried out.Firstly,a 3D spherical contact model was established,and then the UMESHMOTION user subroutine was introduced by Fortran to establish a fretting wear analysis model,which was experimentally verified for its correctness.The simulation analysis showed that the wear profile of partial slip and mixed slip would gradually transform from a"W"shape to a"U"shape.Under the same displacement amplitude,as the normal load increases,the wear regime changes from gross slip to partial slip,and during this process,the wear depth exhibits a maximum value.Therefore,it can be deduced that regulating the working conditions to induce gross slip wear regime under low normal loads or partial slip wear regime under high normal loads is advantageous in mitigating surface wear.