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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.

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Cover: Using dilatometry combined with shear flow at conditions comparable to realistic processing conditions, a flow induced crystallization model is employed for the kinetics of quiescent nucleation, flow enhanced nucleation, fibrillar growth, and the time evolution of the dimensions of the resulting crystalline structures. Three important model parameters are determined over a broad range of temperatures, pressures, and shear rates; pre‐factors to the creation rate of nucleation and to the shish growth rate and a critical molecular stretch defining the transition between flow‐enhanced nucleation and oriented structures. Further details can be found in the article by Tim B. van Erp, Peter C. Roozemond, and Gerrit W. M. Peters* on page 309.