Experimental and numerical study of ECAE deformation of polyolefins

Aour, Benaoumeur; Zaïri, Fahmi; Boulahia, Ramdane; Naït-Abdelaziz, Moussa; Gloaguen, Jean‐Michel; Lefebvre, Jean‐Marc

doi:10.1016/j.commatsci.2008.08.020

Cited by 16 publications

(20 citation statements)

References 29 publications

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“…6). For these two stages, the numerical pressing load decreases continuously; this is not observed in their ECAE experimental results or in results of similar experiments conducted by Son et al 18) , and Aour et al 30) The disparities observed can be attributed to the Coulomb friction model employed in their numerical study. This approach assumes that the frictional effects are a speci c function of the normal contact stresses, which keep these forces constant for the entire process.…”

Section: )mentioning

confidence: 50%

Numerical Estimation of Frictional Effects in Equal Channel Angular Extrusion

2016

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The purpose of this study is to numerically estimate the friction coef cient for equal channel angular extrusion with and without back pressure. Three-dimensional nite element analysis is employed to estimate the coef cient of friction from the maximum pressing load, a crucial variable in die design. The nite element model consists of a billet, a plunger, a ram, and a die, where the interface between the billet and the die is modeled by the Coulomb friction model with truncated shear stress. The numerical model was validated by comparing the grid deformation patterns in the extrusion symmetry plane, and by comparing the load versus stroke curves for the ram (pressing load) and for the plunger (back pressure). Results indicate that the coef cient of friction can be accurately estimated from the maximum pressing load, but it is necessary to modify the traditional Coulomb friction model.

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Section: )mentioning

confidence: 50%

Numerical Estimation of Frictional Effects in Equal Channel Angular Extrusion

2016

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“…This technique was applied to a polymer (low density polyethylene) for the first time by Sue and Li. [2] Since this first work, a number of investigations have been conducted relating to the flow behavior [3][4][5] and morphology evolution during ECAE [6][7][8][9] and to the subsequent increase in toughness and ductility of polymers. [10][11][12][13][14][15] Relatively little research has been performed to discuss the influence of extrusion temperatures on polymer ECAE.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Evolution and Its Effect on Mechanical Properties of Isotactic Polypropylene by Shear Plastic Deformation at Elevated Temperatures

Wang

Tang

Chen

2015

Journal of Macromolecular Science, Part B

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Isotactic polypropylene (iPP) was plastically shear deformed by equal channel angular extrusion (ECAE) at extrusion temperatures varied from 45 to 125 C (25 mm/min). The evolutions of morphology and crystal orientation were studied by reflected optical microscopy (ROM), scanning electron microscopy (SEM), and X-ray diffraction. It was found that the original spherulites were deformed into nearly ellipsoids with their long axis tilted at an angle away from the flow direction. Azimuthal scanning results revealed that two preferred crystal orientations were formed after ECAE. The crystal plasticity was activated by increasing the extrusion temperature, followed by fast rotation of crystallites toward the shear direction. The thermal mechanical analysis (TMA) indicated that low extrusion temperature was favorable to fix the molecular orientation. The iPP samples processed at the investigated temperatures displayed a significant increase in the impact strength, especially for those extruded at 45 C and 65 C. The tensile results revealed a greater elongation at break in the samples deformed at low temperatures (45 C and 65 C) but not in those deformed at high temperatures (85 C or above).

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“…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.…”

Section: Introductionmentioning

confidence: 99%

“…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. Aour et al (2009) have used MSC's FEA proprietary software MSC.Marc to numerically model local flow of a high-density polyethylene workpiece through a generalized Iwahashigeometry angular die with a right angle 2 = 90 ∘ channel intersection and external and internal radii in channel intersection zone and with Coulomb's friction law between the polymer workpiece model and the die walls [1]. The advantage of Aour et al 's (2009) approach includes the availability of experimental-theoretical analysis of multipass ECAE using different deformation routes [1].…”

Section: Introductionmentioning

confidence: 99%

“…Aour et al (2009) have used MSC's FEA proprietary software MSC.Marc to numerically model local flow of a high-density polyethylene workpiece through a generalized Iwahashigeometry angular die with a right angle 2 = 90 ∘ channel intersection and external and internal radii in channel intersection zone and with Coulomb's friction law between the polymer workpiece model and the die walls [1]. The advantage of Aour et al 's (2009) approach includes the availability of experimental-theoretical analysis of multipass ECAE using different deformation routes [1]. However Aour et al 's (2009) phenomenological research does not fully address the macroscopic dynamics of formation and development of rotational modes of ECAE-induced large deformations during pressuredriven local flow of HDPE and PE polymer workpieces [1].…”

Section: Introductionmentioning

confidence: 99%

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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

Golodenko

2017

Advances in Materials Science and Engineering

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The present article is focused on a phenomenological description of a polymer workpiece Equal Channel Angular Extrusion (ECAE) through 2 -dies of Segal and Iwahashi geometries with a channel intersection angle 2 = 105 ∘ with fixed and movable external inlet and outlet die walls. The local flow dynamics, including the formation of macroscopic rotation and a dead zone appearance during the flow of plasticine, paraffin, and wax workpiece models through the subject die configuration was studied using physical simulation techniques. The present article utilizes a Computational Fluid Dynamics (CFD) numerical approach to a theoretical description of 2D viscous flow of incompressible Newtonian continuum through the stated die geometries. The boundary value problem for the Navier-Stokes equations in the curl transfer form for the local viscous flow was formulated and numerically solved with a finite-difference method. Theoretical CFD-derived plots with computational flow lines, dimensionless flow and curl functions, flow velocities, and tangential stresses for viscous material flow through the stated die geometries have been generated and described. As a first rheological approximation the derived computational results provide the theoretical description of physical simulation experiments and visualize the formation of ECAE-induced rotational modes of large deformations like macroscopic rotation and rotational inhomogeneity.

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Experimental and numerical study of ECAE deformation of polyolefins

Cited by 16 publications

References 29 publications

Numerical Estimation of Frictional Effects in Equal Channel Angular Extrusion

Numerical Estimation of Frictional Effects in Equal Channel Angular Extrusion

Microstructural Evolution and Its Effect on Mechanical Properties of Isotactic Polypropylene by Shear Plastic Deformation at Elevated Temperatures

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

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