Running fracture in a H2 pressurized pipeline: characterization and simulation of dynamic ductile fracture in two X65 pipeline steels

Abstract

Long running fractures in pipelines pose great danger to humans, as well as leading to significant economical losses. Current methods of predicting crack arrest require cumbersome re-calibration when new pressurized media inside the pipe, or when new material qualities are introduced.

A new method is being developed by SINTEF, where a coupling of fluid and solid mechanics in the finite element software LS-DYNA describes the fracture propagation, driving forces and crack arrest in gas pressurized pipelines.

The type of work detailed in this report gives valuable knowledge about material properties and behaviour, and is of paramount importance to accurately formulate the problem of running ductile fracture. Different material definitions can be used with this coupled model, and calibrating one type of material model will bedetailed in this report. The coupled model itself will not be evaluated

A widely applied test in the industry is the Charpy v-notch test, which is a standardized high strain rate testwhich determines the amount of energy absorbed by a material specimen during fracture. Being able to use the well established Charpy test for accurately predicting material properties and behaviour is a much studied subject, and at the end of this report, a finite element model of a Charpy specimen will be used to attempt toverify the material definitions found during this work.