Prediction of yield and long‐term failure of oriented polypropylene: Kinetics and anisotropy

Abstract

ABSTRACT:The time-dependent yield and failure behavior of off-axis loaded uniaxially oriented polypropylene tape is investigated. The yield and failure behavior is described with an anisotropic viscoplastic model. A viscoplastic flow rule is used with an equivalent stress, based on Hill's anisotropic yield criterion, and the Eyring flow theory combined with a critical equivalent strain definition. This model is based on factorization of the rate and draw ratio dependence and is capable of quantitatively predicting the rate, angle and draw ratio dependence of the yield stress as well as time-to-failure in various off-axis tensile loading conditions characterized solely from the transverse direction.

Contact mechanics of isotactic polypropylene: Effect of pre-stretch on the frictional response

“…The goal of this research is to relate orientation of semi-crystalline isotactic polypropylene to its frictional resistance. The yield/maximum stress of polypropylene increases with increasing draw ratio (DR) as was shown by Van Erp [1]. A schematic representation of the pre-stretched systems considered is shown in Figure 1.…”

Mechanical Performance of Injection‐Molded Poly(propylene): Characterization and Modeling

“…The rate of flow at which plastic deformation accumulates depends strongly on temperature and applied stress. Since, due to intrinsic and geometric softening, the material can only flow up to a limited and fixed strain level, the stress dependence of the time‐to‐failure and the rate dependence of plastic flow are linked 23, 24. This is understood by looking at Figure 6 where the yield stress is linearly dependent on the logarithm of strain rate with slope α and the applied stress is linearly dependent on the logarithm of the time‐to‐failure with similar slope α , albeit negative.…”

Time-dependent failure of amorphous poly-d,l-lactide: Influence of molecular weight

“…The focus in this research area has largely been on glassy polymers and has been successful for e.g. polycarbonate (PC) (van Breemen, 2011;Boyce and Arruda, 1990;Klompen et al, 2005a, b), polystyrene (PS) (Wu and Buckley, 2004;van Melick, 2003a, b), and poly(methyl methacrylate) (PMMA) (Arruda et al, 1995;van Breemen, 2009), but also proved to be applicable to semi-crystalline polymers (van Erp et al, 2009) and composites (Govaert and Peijs, 2000;Govaert et al, 2001). These models do not incorporate a dependence of the intrinsic deformation kinetics on molecular weight of the polymer.…”