CFD 2D Description of Local Flow of Polymer Workpiece through a modified U-Shaped Die During Equal Channel Multiple Angular Extrusion

Abstract

The present article is focused on a 2D computational fluid mechanics study of local viscous flow dynamics and the formation character of rotary modes of deformation during Equal Channel Multiple Angular Extrusion (ECMAE) of a polymer workpiece fluid model through a U-shaped die with parallel slants in channel intersection zones. The present local flow problem was experimentally analyzed using physical simulation methods and theoretically studied with numerical fluid mechanics techniques. The computational approach has been grounded on the numerical finite difference solution of the boundary value problem for the Navier-Stokes equations in the curl transfer form for the local viscous flow of incompressible Newtonian fluid through a U-shaped rectangular die with parallel slants. The derived research results allow us to draw a conclusion that the implementation of a geometric design of parallel slants within a 2-turn U-shaped die results in localization of the maximum tangential stresses within the workpiece volume to the vicinity of these parallel slants during ECMAE.

Effects of Material Rheology and Die Walls Translational Motions on the Dynamics of Viscous Flow during Equal Channel Angular Extrusion through a Segal 2θ-Die: CFD 2D Solution of a Curl Transfer Equation

“…Perig et al, 2010, have applied a continuum mechanics-based approach and fluid dynamics techniques for simple phenomenological description of growth, formation and transformation of rotational modes of large deformations (e.g., macroscopic rotation and rotational inhomogeneity) within the volume of a viscous workpiece model in the process of ECAE [9,13,14,17,19,20]. Finitedifference-based 2D computer hydrodynamic modeling of viscous ECAE flows of incompressible fluid through angular domains with different die geometries [9,13,14,17,19,20] was based on the difference approximation and numerical solution of curl (vorticity) transfer form of the Navier-Stokes difference equations with an introduction of the curl (vorticity) and flow (stream) function formulation [9,13,14,17,19], and flow velocities punching pressure formulation [20]. Computational diagrams of flow lines and flow velocities for correspondent ECAE-stipulated flows have been determined with an application of Computational Fluid Dynamics (CFD) modeling to flow of viscous fluids through the angular and multiple-angular dies [9,13,14,17,19,20].…”

“…Finitedifference-based 2D computer hydrodynamic modeling of viscous ECAE flows of incompressible fluid through angular domains with different die geometries [9,13,14,17,19,20] was based on the difference approximation and numerical solution of curl (vorticity) transfer form of the Navier-Stokes difference equations with an introduction of the curl (vorticity) and flow (stream) function formulation [9,13,14,17,19], and flow velocities punching pressure formulation [20]. Computational diagrams of flow lines and flow velocities for correspondent ECAE-stipulated flows have been determined with an application of Computational Fluid Dynamics (CFD) modeling to flow of viscous fluids through the angular and multiple-angular dies [9,13,14,17,19,20]. Perig et al (2010) have applied an experimentaltheoretical approach to a phenomenological continuum mechanics-based description of polymer workpiece viscous flow through an angular domain of Segal geometry with a right angle 2 = 90 ∘ die channel intersection through a numerical CFD-based solution of Navier-Stokes equations in curl (vorticity) transfer form [9].…”

“…Perig and Golodenko (2016) have addressed the technological problem of angular extrusion of viscous continuum through a multiple-angled U-shaped angular die with an application of physical simulation and CFD techniques [19].…”

“…In recent years materials science and materials pressure working also deal with the continuum mechanics-based description of the dynamics of macroscopic and microscopic phenomena in the rheologically complex composite and polymeric systems under external perturbations of pressure worked materials [1-5, 7-9, 13, 14, 17, 19-34]. Macroscopic phenomenological description of local materials flow within polymeric systems under external working by pressure is closely associated with modern problems of nonequilibrium thermodynamics of irreversible processes, classical continuum mechanics, Computational Fluid Dynamics (CFD) [9,13,14,17,19,20,30,32,34,35], rheodynamics and rheology [29], rheomechanics and rheophysics [30], polymer physics and chemistry [32,34], material kinetics [31], complex macromolecule networks, chemical engineering of polymers, chemical technology of complex fluids, material working by pressure , medical applications, and phenomenological continuum-based theories of polymer viscous flow [29][30][31][32]34]. So the rheodynamics and rheology of polymer pressure working is also within the aims and scopes of such 2 Advances in Materials Science and Engineering Severe Plastic Deformation (SPD) problems as Equal Channel Angular Extrusion (ECAE) or Equal Channel Angular Pressing (ECAP).…”

“…Today rheologically complex problems of pressureinduced polymer dynamics during SPD by ECAE attract the attention of such researchers as Aour et al (2009) [1], Beloshenko et al (2013) [2], [3], Creasy and Kang (2004) [4], Han et al (2008) [5], Li et al (2012) [7], Minakowski (2014) [8], Perig et al (2010 [9,13,14,17,19,20], Qiu et al (2012) [21], Seo and Weon (2013) [22], Sue et al (1999) [23], Weon et al (2005) [24], Xia et al (2000) [26], [27], and others. Research efforts of these scientists have been focused on physicalmechanical investigations into the engineering problems of polymer materials local flow in angular domains during SPD ECAE material pressure forming.…”