Description Fitness-for-service FFS assessments evaluate the structural integrity of damaged or flawed critical pressure components and determine their suitability for continuing service. FFS procedures such as API-579/ASME-FFS-1 are used in a range of industries, including power generation, oil & gas, chemical processing and aerospace. Level 3 FFS assessment requires detailed structural analysis of components to establish safe design and operating loads.  One of the failure modes to be assessed is global ductile failure of the compoonent under static load. This may be assessed by various analysis routes.  This project will investigate assessment based on elastic-plastic analysis of the damaged component, considering the effect of material model, large deformation response and Code assessment criteria on the calculated safe working load. Key Objectives Commercial FE programs provide users with a variety of elastic-plastic material models for structural analysis. The objective of this project is to review FFS requirements with respect to modelling ductile failure, identify appropriate material models for use in FE analysis and investigate the effect of material model choice on the calculated allowable pressure for a damaged component. The component to be studied is not specified prior to the project start but is likely to be an Oil & Gas industry piping component, in which such problems are common. The project will use the FE programme ANSYS APDL to develop a parametric model of a damaged pipe and investigate the effect of plasticity material model and other modelling assumptions on the calculated static ductile strength of the component.