Abstract
This paper presents a new modelling approach for liquid lubricant behavior in metal forming operations by focusing on the hydrodynamic pressure build-up in micro pockets. Theoretical and numerical fundamentals of the proposed approach are introduced, and upsetting of an aluminum cylinder with an artificial lubricant pocket is presented as a validation case. The proposed numerical framework splits the fluid-solid interaction model into a computational fluid dynamics and solid mechanics part. While the solid mechanics part employs the Lagrangian finite element flow formulation for plastic deformation, the fluid dynamics part is built upon the set of Navier-Stokes equations applying an Eulerian finite element method in combination with an Arbitrary Langagian Eulerian formalism. The latter enables the displacement based coupling from the solid to the fluid. The fluid-to-solid coupling is pressure based and enabled by the finite element flow formulation’s inherent velocity-pressure characteristics. The weak coupling avoids ill-conditioning of the system matrix and makes it possible to benefit from both Lagrangian and Eulerian meshes.
Highlights
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It is desirable to utilize both MPHSL and MPHDL such that workpieces can be tailored towards optimal lubrication behaviour along the entire process
MPHSL and MPHDL were investigated by Üstünyagiz et al [16, 17] by simulating plane strip drawing with a fully coupled fluid-solid interaction approach by employing a rigid-viscoplastic finiteelement formulation
Summary
Upsetting of a cylinder with an artificial lubricant pocket was chosen as an initial validation case for the proposed numerical coupling of the solid and fluid models. The workpiece was manufactured of aluminium 1050 and the applied lubricant was CR5 by Houghton with a density ρa=920 kg/m3 at ambient pressure and a pressure dependent density as shown in Figure 1 (b). They conducted upsetting up to a reduction of 56% while applying a die velocity v=0.1mm/s. The contour of the pocket was measured at 16%, 27% and 56% reduction, which was used to validate the presented numerical coupling
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