Written by Martin Teigen.
The following is a presentation of a tool / platform / interface for performing in-place lateral buckling analysis of pipelines installed with residual curvature. The tool has been developed by Martin Teigen and Malik Ibrahim.
- Fully automated input file preparation for SIMLA or ABAQUS.
- Formatting the relevant analysis results into a format that is understandable for the engineer, and visually presentable for reporting.
- Facilitating for decision making:
- Robust and easy to use tool
- Reducing the effort in considering a great range of analysis configurations
- This gives confidence in the design hence facilitating for decision making.
- Relevant to a range of project phases:
- Concept / pre-FEED: Evaluating feasibility. Simplified inputs.
- FEED: Decision making, RCM as an alternative or not.
- Detailed Design: Takes a level of input commonly applied in detailed design.
- Follow-on engineering: Assessment of changed circumstances and unforeseen events.
- Validated methodology from the peer-reviewed paper by Teigen and Ibrahim [OMAE2015].
- Pipe (beam) elements.
- Plastic material properties.
- Residual strains resulting from installation loads are represented by bending the pipe.
- Other ways of imposing the residual strains may offer higher accuracy, at the cost of efficiency. An example is simulating the entire reeling – un-reeling process.
- The inputs are specified in an Excel Spreadsheet.
- Fully automated input file preparation via Python scripts (SIMLA)/ C# programming (ABAQUS).
- Post-processing using Python.
- The implementation is validated.
Three levels of validation:
- Step 1: Comparison with an analytical solution.
- Effective axial force μax * Wsub = 0.75 * 1194 [N/m] = 896 [N/m].
- Slope corresponds with FE results.
- Step 2: The FE Tool is validated against the peer-reviewed OMAE2015 paper by Teigen and Ibrahim.
- Figure shows excellent correspondence.
- Step 3: Validation between the two different tools for SIMLA and ABAQUS.
- There are two independent FE Tools; one for SIMLA and one for ABAQUS.
- These are implemented in two completely different programming languages; Python for SIMLA and C# for ABAQUS.
- The two different tools yield the same results.
- These are some examples, similar correspondence in the other results!
Some examples of the features, and the associated input formats are presented below.
Pipeline Properties / Friction
- Pipeline Properties / Friction
- Different material properties and friction can be specified to sections along the pipeline
- Model Discretisation
- Efficient model discretisation allows for analysing large models with many imperfections.
- No more elements than needed!
- Example 1: Residual curvature for freespan mitigation
- Example 2: Residual curvature on a typical seabed.
- 14-inch OD, imperfection spacing 1000 m
- Imperfections by under-straightening
- Strain profile of Subsea 7’s Seven Oceans
- Automated post-processed results.
- The engineer can explore the sensitivity of the following with the click of a button:
- Diameter, WT, submerged weights, material properties, pipe-soil friction etc.
- Loads: Temperature, pressure, load steps.
- Residual curvature location along the pipeline, level of residual strain and the strain profile.
- Robust tool that can easily perform sensitivities, reducing the effort in considering a great range of analysis configurations, hence giving confidence in the design and thereby facilitating for early decision making.
Summary and Overview
- Tool for performing lateral buckling analysis using residual curvature as the control method.
- ABAQUS automated input file generation, allows the engineer to focus on producing results instead of dealing with the complex code of input files.
- Results of high quality in a short amount of time.
- Validated implementation and methodology.
- The automated process removes many complexities, giving the engineer the ability to complete the work efficiently – reducing cost.
- Robust and easy to use tool, reducing the effort in considering a great range of analysis configurations, hence giving confidence in the design and thereby facilitating for early decision making.
- The tool represents a significant amount of work, it has taken a long time to develop something that is not only functioning, but is robust.
- Other ways of imposing the residual strains may offer higher accuracy, at the cost of efficiency.