Anisotropic Elastic-Viscoplastic Properties at Finite Strains of Injection-Moulded Low-Density Polyethylene

Anisotropic Elastic-Viscoplastic Properties at Finite Strains of Injection-Moulded Low-Density Polyethylene

ABSTRACT

Injection-moulding is one of the most common manufacturing processes used for polymers. In many applications, the mechanical properties of the product is of great importance. Injection-moulding of thin-walled polymer products tends to leave the polymer structure in a state where the mechanical properties are anisotropic, due to alignment of polymer chains along the melt flow direction. The anisotropic elastic-viscoplastic properties of low-density polyethylene, that has undergone an injection-moulding process, are therefore examined in the present work. Test specimens were punched out from injection-moulded plates and tested in uniaxial tension. Three in-plane material directions were investigated. Because of the small thickness of the plates, only the in-plane properties could be determined. Tensile tests with both monotonic and cyclic loading were performed, and the local strains on the surface of the test specimens were measured using image analysis. True stress vs. true strain diagrams were constructed, and the material response was evaluated using an elastic-viscoplasticity law. The components of the anisotropic compliance matrix were determined together with the direction-specific plastic hardening parameters

KEYWORDS

Anisotropic, Constitutive behaviour, Elasticity, Injection-moulding, LDPE, Polyethylene, Tensile, Viscoplasticity, Anisotropy, Low density polyethylenes, Mechanical properties, Molding, Plasticity, Plates (structural components), Polyethylenes, Polymers, Strain, Tensile testing, Thin walled structures, Anisotropic elastic, Compliance matrixes, Elastic-viscoplasticity, Manufacturing process, Monotonic and cyclic loading, Injection molding

CITATION

Kroon, M., Andreasson, E., Persson Jutemar, E. et al. (2018) Anisotropic Elastic-Viscoplastic Properties at Finite Strains of Injection-Moulded Low-Density Polyethylene. Exp Mech (2018) 58: 75. https://doi.org/10.1007/s11340-017-0322-y

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