scope:

Scope and Overview of these Guidance Notes

The objective of these Guidance Notes is to provide the best practices and general recommendations for analyzing marine and offshore structures using NLFEA. The main technical aspects of NLFEA are addressed in these Guidance Notes to help the reader to better understand and evaluate the analysis results and to aid in troubleshooting possible issues with solution convergence.

These Guidance Notes cover:

• Different sources of structural nonlinearities.

• Main technical aspects of NLFEA, such as analysis type, iterative algorithm, time-domain integration, model extent, mesh size, element type, boundary conditions, load application, geometric imperfections, contact, numerical solution stabilization, etc.

• Quality control.

• Application examples.

 The recommendations of these Guidance Notes for using NLFEA are applicable to marine and offshore structures made of steel. All types of structural failures listed in 1/1.3 are covered except for brittle failure and high-cycle fatigue. Brittle failure rarely occurs in marine and offshore structures due to high quality control of the steel manufacturing and construction processes. Linear high-cycle fatigue analysis procedure and the associated acceptance criteria may be found in ABS Guide for Spectral-Based Fatigue Analysis for Vessels and ABS Guide for Spectral-Based Fatigue Analysis for Floating Production, Storage and Offloading (FPSO) Installations.

Design loads and acceptance criteria for NLFEA results regarding various failure modes may be found in ABS Rules or other applicable Standards.