SLOW CRACK GROWTH IN POLYETHYLENE PIPES: FRACTURE SURFACE EVIDENCE FOR THE SLOW CRACK GROWTH MECHANISM IN ACCELERATED TESTS

Maret 27, 2023 by admin in Uncategorized

Mark Boerakker, Rudy Deblieck, a Harm Caelers, Arno Wilbers, Tine Boonen a DSM, Britta Gerets, Mirko Wenzel

# 2021 Amsterdam

Components made of plastic are facing ever-increasing demands with respect to their production, use and durability. This also holds for gas and drinking water pressure pipes made of high-density polyethylene (PE-HD), where service lifetimes of up to 50 years and in some cases even 100 years are required. One of the most important failure modes determining the lifetime is slow crack growth induced failure. This failure mode needs to be assessed by means of accelerated test methods. Several accelerated methods have been developed recently. Decent correlations between these recent tests and the earlier established (slower) methods have been reported. In the absence of real life examples the validation of the above-mentioned tests is examined in this paper through the use of existing deformation and failure models of craze propagation and craze-crack transition, coupled to crack growth kinetics, the outcome of which can be translated into the molecular network condition via the surface energy. The validity of these deformation and failure models for acceleratedtests will be connected to the analysis of the fracture surface textures found in accelerated Full-Notch Creep Tests (aFNCT) for a set of polyethylene materials and further to the results of the Strain Hardening Test (SHT).

source: https://www.pe100plus.com/PPCA/SLOW-CRACK-GROWTH-IN-POLYETHYLENE-PIPES-FRACTURE-SURFACE-EVIDENCE-FOR-THE-SLOW-CRACK-GROWTH-MECHANISM-IN-ACCELERATED-TESTS-p1745.html