Computational aspects in creep rupture modelling of polypropylene using an energy failure criterion in conjunction with a mechanical model

Abstract

The creep rupture time of polypropylene (PP) was modelled successfully using the Reiner-Weissenberg energy criterion with a mechanical model. The computational aspects were discussed with respect to the software routine used, the equation relating time to rupture and stress, and the various problems associated with non-linear regression analysis for parameters optimization. The predicted upper stress limit for PP homopolymer and copolymer was 30 and 24 MPa, respectively. The predicted lower stress limit was 10 MPa and was independent of polymer type. Short term results can only be used to predict the stress limits if reasonable bounds were imposed on all the parameters. The above approach also predicted reasonable values for the resilience of polypropylene. © 1990.