Fatigue crack growth in PE-HD pipe grades

In this work, fatigue crack growth (FCG) experiments were used to evaluate the long term performance of pipe grade polyethylene (PE). The parameters for the ranking tests were defined based on basic investigations of the influence of test frequency, R-ratio (F-min/F-max) and specimen configuration on FCG in PE at room temperature. Eight different commercial pipe grades (PE-80 and PE-100) were included in the investigations and two different specimen configurations [Compact Type (CT) and Cracked Round Bar (CRB)] were used. A procedure was established to initiate quasi-brittle cracks that led to failure within 60 h. Crack-growth initiation times were determined from crack-opening displacement data and crack growth kinetics were analysed using linear elastic fracture mechanics (LEFM). A ranking of the materials investigated by their FCG behaviour was possible and compared with results from Full Notch Creep Tests (FNCT).