Displacement rate effect in the fracture toughness of glass fiber reinforced polyurethane

Abstract

Composite structures currently used in the oil industry must meet strict requirements for design and safety reasons. They need to maintain strength under varied displacement rates throughout its lifetime. It is therefore critical to fully understand the fracture behavior of such composites. This work presents experimental results regarding the influence of a range of displacement rates on the fracture energy in mode I, GIc, of glass fiber reinforced polyurethane used in the oil industry to repair and reinforce pipelines with corrosion damage. To determine GIc as a function of displacement rate, double cantilever beam specimens were tested, with displacement rates of 2, 20 and 200 mm/min with different thicknesses. A complementary numerical study was performed with the aim of predicting strength using the measured values. This work has demonstrated a significant influence of the strain rate and composite thickness on GIC of the composite materials, with higher rates and thicker specimens causing an increase in the GIC values.