Asperities on asperities

Steffensen, Henrik; Wanheim, Tarras

doi:10.1016/0043-1648(77)90045-x

Cited by 18 publications

(7 citation statements)

References 1 publication

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“…It is postulated that the workpiece surface irregularities reflect the lubricant film thickness even in boundary lubrication. The existence of lubricant pockets on top of flattened asperities has already been postulated by Steffensen et al [21] with idealized asperities. Sutcliffe [22] developed a multi-scale model of roughness taking into account primary roughness with a relatively long wavelength as well as a secondary roughness with a short wavelength.…”

Section: Introductionmentioning

confidence: 88%

Basic investigations on boundary lubrication in metal forming processes by in situ observation of the real contact area

Weidel

Engel

Merklein

et al. 2009

Prod. Eng. Res. Devel.

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In metal forming processes tribology plays a significant role for process feasibility and tool lifetime. Boundary and mixed lubrication conditions are predominant in metal forming processes. Hence the appearing real contact area which is mainly influenced by the topography of tool and workpiece has a major impact on friction conditions. For an improved understanding of friction at the interface between tool and workpiece, the flattening behavior of idealized asperities under boundary lubrication conditions is investigated by applying a translucent tool. Various liquid lubricants have been used. It has been revealed that the usage of certain lubricants leads to higher resistance of the asperity against flattening which would be in favor of reduced friction. Topography analysis and finite element simulations have been performed in order to get more insight into the mechanisms leading to this effect. The findings have been transferred to real topographies by micro upsetting tests with ground surfaces.

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Section: Introductionmentioning

confidence: 88%

Basic investigations on boundary lubrication in metal forming processes by in situ observation of the real contact area

Weidel

Engel

Merklein

et al. 2009

Prod. Eng. Res. Devel.

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“…The model was verified by Bay and Wanheim (1976) in controlled, high pressure sliding contact experiments between model asperities and a plane tool surface. The effect of trapped lubricant was studied by Nellemann et al (1977), the resulting surface roughness and average effective strain of the deformed asperities were predicted by Bay et al (1975), and the effect of asperities on asperities was analyzed by Steffensen and Wanheim (1977). Wanheim and Bay (1978) gave an overview of the model.…”

Section: Contributions In the 1970smentioning

confidence: 99%

Review of friction modeling in metal forming processes

Nielsen

Bay

2018

Journal of Materials Processing Technology

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“…The function of is to introduce the additional equations necessary to evaluate the frictional contact forces according to (6,8).…”

Section: Mixed Formulation For Curved Contactmentioning

confidence: 99%

“…For a complete formulation of the frictional contact problem, the differential inclusions (6) and (8) have to be added to the equilibrium equations of the deformable body. Assuming formally the existence of a differentiable total energy functional Φ(v) for characterizing the elastic response of the deformable body, as well as the external forces, coulping contact and friction reduces to adding the two corresponding pseudo-potentials to the potential Φ(v):…”

Section: Mixed Formulation For Curved Contactmentioning

confidence: 99%

“…The state conditions of surfaces in contact and consequently the friction behaviour, are influenced by a number of complex phenomena related to wear such as chemical reactions, abrasion of coatings etc. [5][6][7][8] . Especially for configurations involving large sliding paths, or many repetitions of the same process which is typical for many metal forming operations, the evolution of surface characteristics may become particularly important in the definition of the friction behaviour.…”

Section: Introductionmentioning

confidence: 99%

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Numerical modelling and simulation of frictional contact using a generalised coulomb law

Heege¹,

Alart

Oñate

1995

Engineering Computations

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A consistent formulation for unilateral contact problems including frictional work hardening or softening is proposed. The approach is based on an augmented Lagrangian approach coupled to an implicit quasi-static Finite Element Method. Analogous to classical work hardening theory in elasto-plasticity, the frictional work is chosen as the internal variable for formulating the evolution of the friction convex. In order to facilitate the implementation of a wide range of phenomenological models, the friction coefficient is defined in a parametrised form in terms of Bernstein polynomials. Numerical simulation of a 3D deep-drawing operation demonstrates the performance of the methods for predicting frictional contact phenomena in the case of large sliding paths including high curvatures.

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Asperities on asperities

Cited by 18 publications

References 1 publication

Basic investigations on boundary lubrication in metal forming processes by in situ observation of the real contact area

Basic investigations on boundary lubrication in metal forming processes by in situ observation of the real contact area

Review of friction modeling in metal forming processes

Numerical modelling and simulation of frictional contact using a generalised coulomb law

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