Cyclic viscoplasticity of semicrystalline polymers with finite deformations

Published Date
Mechanics of Materials
January 2013, Vol.56:53–64, doi:10.1016/j.mechmat.2012.09.005

• Author 

• A.D. Drozdov ^a,,
• R. Klitkou ^b
• J.deC. Christiansen ^b

• aDepartment of Plastics Technology, Danish Technological Institute, Gregersensvej 1, Taastrup 2630, Denmark
• bDepartment of Mechanical and Manufacturing Engineering, Aalborg University, Fibigerstraede 16, Aalborg 9220, Denmark

Received 7 April 2012. Revised 25 July 2012. Available online 23 September 2012. 

Abstract

Observations are reported on low density polyethylene (LDPE) in uniaxial tensile cyclic tests (oscillations between maximum elongation ratios   and the zero minimum stress   when   increases monotonically with number of cycles n). Experimental data demonstrate fading memory of deformation history: when specimens are subjected to two loading programs that differ along the first  cycles of deformation and coincide afterwards, their stress–strain diagrams become identical starting from the nth cycle. A constitutive model is developed in cyclic viscoplasticity of semicrystalline polymers with finite deformations, and its adjustable parameters are found by fitting the observations. Ability of the stress–strain relations to describe the fading memory phenomenon and to predict the mechanical response of LDPE in cyclic tests with various deformation programs is confirmed by numerical simulation.

Highlights

► Fading memory of deformation history is observed in cyclic tests on LDPE. ► A model are derived in cyclic viscoplasticity with finite deformations. ► Its ability to predict the observed phenomena is confirmed by simulation.

Keywords

Low density polyethylene

Cyclic viscoplasticity

Finite deformations

Fading memory

Constitutive model

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