Damage and fracture of polyvinylidene fluoride (PVDF) at 20 °C: Experiments and modelling

Flexible oil pipelines are multilayered structures used for the transport of crude oil or natural gas from the seabed to the surface in offshore oil fields. Because of severe service conditions, composite structures made of metallic and polymeric layers must be used. PVDF is a good candidate as it accommodates tensile and flexural deformations and guarantees water tightness. The present paper focuses on the mechanical properties of PVDF at 20 °C. Several specimens with different geometries were tested: smooth specimens, notched specimens and cracked specimens under tension and bending. Fracture surfaces were examined to determine fracture mechanisms. Based on mechanical testing and microscopic observations, a modified Gurson–Tvergaard–Needleman model for semi-crystalline polymers is proposed. The model allows both the non-linear behavior and the cracking of polymer structures to be represented.