Study On The Fretting Wear Dynamics And The State Of Third-body Wear For Dimple Of Hard Disk Suspension

At operational/non-operational state, because of either hard disk drive's own work theory or the external shock or libration, the dimple of suspension and the tongue of flexure will have elastic-plastic contact and micro-slip of displacement, and fretting wear and fretting fatigue will happen on the dimple of suspension and the tongue of flexure if alternating deformation or relative slip existence in long-term,the debris produced by such wear will fall on the hard disk drive and become deadly pollution, and cause error when the magnetic read and write data,even physical damage of the disc will lead to failure of entire hard disk.Aim at the fretting wear of the dimple and tongue, This paper have constructed a model of hard disk drive,and used the finite element simulation to study the wear of tongue and dimple when hard disk drive suffered external shocks and vibrations.In addition,this paper studied the impact of external load on the dimple and tongue after the debris was produced,can lay a foundation to the research on the production mechanism and controlling method of fretting wear and fretting fatigue,and also serve the instructional function to optimal design of dimple of tongue.This paper constructed finite element model of head disk assembly in Solidworks,and then imported into HyperMesh,restored and optimized,midsurfed and meshed the model,and then the boundary conditions was applicatied.This paper studied the effect of single half-sine acceleration pulse amplitude and pulse width of the tongue and dimple's fretting wear at operational/non-operational state: As the pulse amplitude increase, the relative displacement between dimple and tongue will become greater, and the micro-slip and wear between dimple and tongue would be more serious; as pulse width increase, the relative displacement between dimple and tongue will become greater too, However, the changes in the displacement rate is not significant. We also simulatied the regular of amplitude and frequency of sinusoidal acceleration at operational/non-operational state:as the amplitude of sinusoidal acceleration increase, the relative displacement between dimple and tongue will become greater, and the wear would be more serious; as the frequency of sinusoidal acceleration excitation was close to the natural frequency of the hard drive, the relative displacement and wear between dimple and tongue will become greater.After compared the relative displacement of dimple and tongue when the hard disk drive suffer pulse or shock at operational state with that an non-operational state,the impact of preload on the shock-resistant ability was known. In addition, the impact of Young's Modulus and poisson's ratio of dimple and tougue was investigated.Third-body model of fretting between dimple and tongue in the situations of elastic contact and plastic contact was constructed,and through therory discursion,the relationship among the shock and the distance between dimple and tongue and the total contact area under elastic contact state and the total volume of the plastic deformation region under plastic contact state was shown as the external load increase, the distance between dimple and tongue reduce,and the total contact area under elastic contact state increase in direct ratio,just as the total volume of the plastic deformation region under plastic contact state.