Hydrodynamic lubrication in hemispherical punch stretch forming—Modified theory and experimental validation

Sun, Dah-chen; Chen, Kuo-Kuang; Nine, Harmon D.

doi:10.1016/0020-7403(87)90061-0

Cited by 22 publications

(14 citation statements)

References 6 publications

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“…In order to confirm the feasibility of the new lubrication/ friction model, Sun et al [3] axisymmetric stretch forming process, as shown in Fig. 5, is simulated and demonstrated …”

Section: Resultsmentioning

confidence: 98%

“…4 Flowchart of the solution procedure as a ''bench mark'' test. The current lubrication/friction model combined with a finite element membrane code of stretch forming to predict the strain distribution, and compared with the experimental measurement of Sun et al [3]. The elastic-plastic finite element membrane code of stretching forming developed by Hsu and Wilson [5] is adopted in this article.…”

Section: Inlet Film Thickness Ht1mentioning

confidence: 99%

“…The elastic-plastic finite element membrane code of stretching forming developed by Hsu and Wilson [5] is adopted in this article. The experimental conditions of Sun et al [3] are adopted as the input parameters of the simulation. The blank is 70:30 brass of 180 mm diameter, 0.81 mm thickness and 2.5 lm surface roughness (R q ).…”

Section: Inlet Film Thickness Ht1mentioning

confidence: 99%

“…The availability of the new friction model was proved by a published problem and an axisymmetric stretch forming process was therefore adopted as a benchmark. The numerical results are compared with the measured strain distribution by Sun et al [3].…”

Section: Introductionmentioning

confidence: 97%

“…They separated the lubricant film into two regions: the work zone near the center of the punch where the pressure gradient has negligible influence on lubricant flow, and the relatively short inlet zone which is adjacent to work zone and controls the formation of the lubricant film. Sun et al [3], Wilson and Hector [4], Hsu and Wilson [5] further combined the thick film lubrication theoretical model with the finite element analysis of sheet deformation. The works of above mentioned assumed a thick regime, in which the surface topography does not influence the lubrication.…”

Section: Introductionmentioning

confidence: 98%

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A Refined Friction Modeling for Lubricated Metal Forming Process

Yang

2007

Tribol Lett

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In spite of the existence of a well-developed realistic friction model, it has only been applied to the simple geometric problems, such as the axisymmetric and plane strain conditions, where the formulations of lubricant transport can be decomposed into two characteristic equations. Accordingly, a unified procedure of combining the current lubrication/friction model and finite element code of metal forming has been developed in this article for either steady or unsteady three-dimensional process including both axisymmetric and plane strain cases. In the part of the lubrication analysis, a finite element method is derived for the average Reynolds equation that is appropriated for 3-D metal forming process, and regardless of whether the tooling/workpiece surfaces are in contact or not. With regard to the theory of asperity contact, in addition to the well-known smoothing and roughening effects, significant deformation of asperities could be caused by the elastic microwedges on the tool surface. The availability of the new friction model was proved by a published problem and an axisymmetric stretch forming process was therefore adopted as a benchmark. Numerical results showed that the present analysis provides a good agreement with the measured strain distributions. Keywords Friction model Á Finite element method Á Lubrication Á Asperity contact Nomenclatures A contact area ratio (fractional contact area) ¶A increasing rate of contact area ratio; dA/dt ¶A I component of ¶A induced by indentation effect ¶A M component of ¶A induced by microwedge effect ¶A R component of ¶A induced by roughening effect B geometric matrix C coefficient of microwedge model C R coefficient of surface roughening model dA 0 differential undeformed area D material matrix E t tangent modulus E w

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“…In order to confirm the feasibility of the new lubrication/ friction model, Sun et al [3] axisymmetric stretch forming process, as shown in Fig. 5, is simulated and demonstrated …”

Section: Resultsmentioning

confidence: 98%

Section: Inlet Film Thickness Ht1mentioning

confidence: 99%

Section: Inlet Film Thickness Ht1mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

See 3 more Smart Citations

A Refined Friction Modeling for Lubricated Metal Forming Process

Yang

2007

Tribol Lett

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ALE finite element formulation for ring rolling analysis

Liu

1992

Numerical Meth Engineering

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SUMMARYIn this paper, a ring rolling process is analysed by the Arbitrary Lagrangian Eulerian (ALE) finite element method. Phenomena associated with the process, such as large deformations, elastoplastic material behaviour and the friction on the interface, are included in the analysis. Special modelling on driven, idle and guide rolls is given. Results which include the overall shape of the formed ring, the time histories of roll separating force and driving torque, the distribution of the normal pressure on the ring-roll interface as well as the distribution of effective stresses in the formed ring, are also presented.

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An ALE hydrodynamic lubrication finite element method with application to strip rolling

Liu

1993

Numerical Meth Engineering

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A method that incorporates the hydrodynamic lubrication analysis into the arbitrary Lagrangian Eulerian (ALE) finite element analysis is developed for steady-state strip rolling simulation. By employing the ALE formulation, only part of thc workpiece, which is subjected to large plastic deformation within the roll-bite region, is modelled, so that thc computational cost is substantially reduced. In the hydrodynamic lubrication formulation, the effect of surface roughness on the lubricant flow is taken into consideration by the use of an average flow model. The friction stress is expressed in terms of forming variables such as surface roughness, lubricant and workpiece properties, film thickness, forming speed and process geometry. Furthermore, the elastic deformation of rolls is also analysed by the boundary element method to avoid the finite element discretization insidc the rolls. Two numerical examples. aluminium and steel strip rolling processes, are presented to demonstrate the merits of the proposed method.

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Hydrodynamic lubrication in hemispherical punch stretch forming—Modified theory and experimental validation

Cited by 22 publications

References 6 publications

A Refined Friction Modeling for Lubricated Metal Forming Process

A Refined Friction Modeling for Lubricated Metal Forming Process

ALE finite element formulation for ring rolling analysis

An ALE hydrodynamic lubrication finite element method with application to strip rolling

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