Third Particle Ejection Effects on Wear with Quenched and Tempered Steel Fretting Contact

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This article presents a robust Finite-Element-Method-based wear simulation method, particularly suitable for fretting contacts. This method utilizes the contact subroutine in a commercial finite element solver Abaqus. It is based on a user-defined contact formulation for both normal and tangential directions. For the normal contact direction, a nodal gap field is calculated by using a simple Archard's wear equation to describe the depth of material removal due to wear. The wear field is included in the contact pressure calculation to allow simulation of wear and contact stress evolution during the loading cycles. The main advantage of this approach is that all contact variables are accessible inside the routine, which allows full coupling between normal and tangential contact variables. Also, there is no need for mesh modifications during the solution. This makes the implementation flexible, robust and particularly suitable for fretting cases where friction and tangential contact stiffness play an essential role. The method is applied to the bolted joint type fretting test case. The methodology is also fully applicable to complex real component simulations.

Section: Methodsmentioning

confidence: 99%

FEM-based wear simulation for fretting contacts

Mäntylä

Juoksukangas

Hintikka

et al. 2020

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“…The generation of fretting debris (third body layer) in the contact may affect COF and wear behavior [1]. Previous experiments using the same quenched and tempered steel in dry contact conditions have revealed that the third body layer can notably decrease wear rate, but COF behavior was unaffected [5]. COF has been measured to decrease [17] and the wear mechanisms have been affected in corrosive conditions [18].…”

Section: Introductionmentioning

confidence: 99%

Avoiding the high friction peak in fretting contact

Juoksukangas

Hintikka

Lehtovaara

et al. 2020

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Fretting fatigue and wear may exist if two parts have small amplitude relative rubbing between the contacting surfaces. A peak in the coefficient of friction typically occurs during the first thousands of loading cycles in dry fretting contact with quenched and tempered steel. This peak is related to adhesive friction and wear causing non-Coulomb friction and high local contact stresses possibly leading to cracking. The focus of the study is the effect of different experimental methods on the frictional behavior of the fretting contact between the steel surfaces. The use of pre-corroded specimens and contact lubrication delayed and reduced the initial peak. However, a pre-added third body layer removed the peak completely.

“…At this stage, wear behaviour is strongly governed by ejection of wear debris, rather than forces and displacements. Experiments made with QT-steel contact showed that manual removal of entrapped wear debris lead to considerable increase in total wear [7]. …”

Section: Non-idealities In Fretting Wearmentioning

confidence: 99%

“…This behaviour can be explained at least partially by velocity accommodation in entrapped oxide third bodies. [5,7] Non-idealities in fretting fatigue Dimensioning of fatigue prone components is often done using measured SN-curves. In case of QT-steel, a component can be designed to last for finite or infinite amount of load cycles.…”

Section: Non-idealities In Fretting Induced Frictionmentioning

confidence: 99%

Non-idealities in fretting contacts

Hintikka¹,

Juoksukangas²,

Lehtovaara³

et al. 2017

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Summary. There is direct link between non-idealities in fretting wear, friction and fretting fatigue, especially in the case of adhesion spots. Friction is not a constant and varies as a function of load cycles and non-Coulomb friction may occur. Fretting wear may lead to material transfer, resulting in tangential fretting scar interactions, and in the long run, wear debris is entrapped and cumulated in the interface. Fatigue failure can occur at low nominal stress amplitudes due to nonCoulomb effects. Novel tools are required in component design to fully capture these non-ideal phenomena.Key words: fretting, friction, fretting wear, fretting fatigue DescriptionFretting stands for the action of small amplitude reciprocating surface sliding, causing fretting wear and fretting fatigue. Slip amplitude is orders of magnitude smaller than the size of the contact, especially in engineering applications where large flat-on-flat contacts are common and sliding is typically undesired condition. The appearance and severity of fretting fatigue is dependent on stress field but also essentially on tribological features, such as friction and wear, which may generate surface micro-cracks and accelerate the initial stages of fatigue. Damage may appear below the pure fatigue based stress limits inside the contact that cannot be inspected visually without opening the joint [2,14]. Modelling of contacts is largely based on simple assumptions considering friction, wear and geometry [11].This study investigates fretting induced non-idealities in wear, friction and fatigue cracking, observed with quenched and tempered steel specimens in self contact (34CrNiMo6+QT, abbreviated as QT-steel). Result obtained using three different kinds of fretting apparatuses with different contact and loading types [4,5,8,9].