Steady Plastic Flow of a Polymer during ECAE Process: Experiments and Modelling

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

doi:10.1002/9780470610794.ch60

Cited by 1 publication

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“…A fruitful discussion was reported by Wang et al (2006) on lamellar formation and relaxation in simple sheared polyethylene terephthalate (PET) using the in-situ time resolved synchrotron Small-Angle X-ray Scattering (SAXS) technique. Recently, numerical and experimental investigations were achieved to highlight the effects of the main geometrical and processing parameters on the viscoplastic behaviour of polymers during the ECAE process (Zaïri et al, 2008;Aour et al, 2009;Bouaksa et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Analysis of plastic deformation of semi-crystalline polymers during ECAE process using 135° die

Aour¹,

Mitsak²

2016

jtam

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In this paper, analysis of plastic deformation of high density polyethylene (HDPE) and polypropylene (PP) during an equal channel angular extrusion (ECAE) process is investigated. The effects of ram speed, number of passes, processing route and temperature are tested experimentally using a 135 • die. The results show that the pressing force decreases with an increase in the number of passes and reaches a saturation state rapidly for routes A and C compared to routes B A and B C. Furthermore, it is found that the reduced curvature of the extruded samples is obtained by route C, however, the maximum warping is obtained by route A. A slight influence of temperature on the reduction of the warping is observed on the extruded samples. In order to predict the plastic strain inside the extruded samples, an elastic viscoplastic model is identified using compressive tests at different strain rates and coupled with the finite element method (FEM). A good correlation is found between the numerical modeling and experimental findings. FEM results show that the PP samples display a higher level of plastic strain compared to HDPE samples. However, almost the same degree of strain heterogeneity is obtained for both polymers. Finally, in order to reduce the warping and improve the strain homogeneity, a controlled back-pressure with small corner angle is expected to be an adequate solution.

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