Scripting for modeling local buckling of a spiral welded pipe

Susilo, Adhi (2014) Scripting for modeling local buckling of a spiral welded pipe. Masters thesis, Memorial University of Newfoundlnad.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (9MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The demand of large diameter pipes is significant. In the offshore industry, seamless and UOE (U-ing, O-ing, and Expanding) pipes are used commonly, but the production costs of these kind of pipes is not low. The spiral welded pipe (SWP) is considered the answer to this challenge. The SWP has a low cost of production and yet it can be said that the SWP is as good as the UOE pipe. However, some opinions give bad impressions about a SWP. Later, studies show that weaknesses found with SWPs are due to poor manufacturing processes. This work is developing a model to stimulate SWP strength with a finite element analysis tool called ABAQUS. The pipe is loaded by internal pressure and bending moment and there is imperfection on the pipe geometry. Therefore, local buckling is expected. The model is built mainly by a Python script. This work emphasizes the use of scripting for simulating a model, but some people may be not familiar with Python. Therefore, other programs (e.g. FORTRAN and GNUPLOT) are involved. There are two main models for this work. The first model is a UOE pipe; it is called the Benchmark Pipe (BMP) model, this model of this pipe has been calibrated and verified against large-scale physical tests, and the second model is for the SWP model. Referring to the tested model, confidence in the SWP modelling procedures can be established. Both models have the same dimensions, the same material properties, and are isotopic. In this work, the SWPs with different setting are also examined. The main conclusions from this study include: 1. The SWP modelling procedures provided consistent results with the BMP model in terms of displacement response, moment-curvature behaviour and local deformation mechanisms. 2. The use of scripting provide an effective tool for the pre- and post-processing of the simulation. The main pre-processing attributes included generation of the pipe diameter, wall thickness, pitch, and initial geometric imperfections. The post-processing script facilitates the analysis by transforming field variables such as displacement, rotation and section forces into section moment, curvature, deflection and axial strain. 3. The use of partitioning was found to have detrimental effects on the pipe mechanical response that resulted in non-intuitive behaviour. This further supports the need for scripting tools in the simulation and analysis.

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