Analysis Component

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Analysis Component

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The Analysis component is used to specify the various inputs for a PipeLay analysis. The Analysis component allows you to gather together a set of components of various types, such as pipelines, vessels, waves and so on, from all of those defined in a project file, and to perform various types of analyses using these components. In this example, the Analysis component is named ‘Reel-Lay Analysis’. The following sections provide a description of the various inputs for the analysis.

 

Properties Tab

The Properties tab allows you to specify the options that are to be applied to all analysis stages of a particular model. In this example, the Model is selected as ‘Model’ and the Contact Modelling option is defined as Simple.

The Tolerance dialog in the Dynamic section has the properties listed in the table below specified.

Table: Dynamic Tolerance Properties

Property

Value

Tolerance Measure

0.001

Maximum Number of Iterations

1000

Small Torque Value

1 x 106 Nm

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Installation Stages Tab

The Installation Stages tab is where you define the various stages in your analysis. In this example, there are two static stages and one dynamic stage. Both a static and a dynamic reel-lay stage restart from an initial static stage. In the static reel-lay stage, the Number of Increments is set to 100 in the Time dialog. The table below lists the time variables used in Stage 3, the dynamic reel-lay stage.

Table: Time Variables for Dynamic Analysis

Property

Value

Time Step Type

Fixed

Start Time

0.0 s

End Time

1000 s

Time Step

0.05 s

Ramp Type

Nonlinear

Ramp Time

20 s

 

In order to optimise efficiency, no Automated Postprocessing or Tabular Output is requested (i.e. No is selected in both the Automated Postprocessing and Tabular Output drop-down lists) for the dynamic stage. Customised postprocessing is requested for this stage instead, by referencing an appropriate Custom Postprocessing component as described in the following sub-section.

 

Custom Postprocessing Component

The Custom Postprocessing component allows you to request specific results in addition to those provided automatically by PipeLay. It is useful in this instance, as it allows you to obtain structural, effective tension, bending moment and Von Mises strain snapshots of the final configuration for the dynamic reel-lay analysis i.e. the final time of the dynamic analysis, 1000 seconds.

Therefore, one Custom Postprocessing component entitled ‘Dynamic Structure Snapshot’ is created in the Postprocessing folder, and is referenced on the Installation Stages tab of ‘Reel-Lay Analysis’. The customised postprocessing is requested for the dynamic analysis only.

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Parameters Tab

The Parameters tab allows you to specify which parameters you want to change during each analysis stage defined on the Installation Stages tab. In this example, parameter changes are made only in Installation Stage 2, the restart static stage. A summary of the parameters changed is provided in the table below.

Table: Summary of Parameter Changes

Parameter

Component

Value

Active Length Change

Pipeline(1)

100 m

Vessel Surge

Lay Vessel(1)

100 m

 

Criteria Tab

On the Criteria tab, you can specify installation criteria for each installation stage that is created in the Installation Stages tab. In this example, criteria are only applied to the initial static stage as the other stages restart from this stage. The table below provides details of the specified criteria.

Table: Criteria Properties for Initial Static Stage

Property

Value

Criteria

Tip Separation

Component Name

Lay Vessel(1)

Minimum Value

0.344 m

Maximum Value

0.345 m

Iterate On - Type

Seabed Connection Point

Iterate On - Name

Seabed Connection

Iterate On - Vector

Global Y

Tolerance – Max Iterations

1000

Tolerance – Min Adjustment

0.001 m

Tolerance – Max Adjustment

1 m

Tolerance - Multi-Pass

Yes

 

Code Checking Tab

The Code Checking tab allows local buckling unity checks to be requested on different sections of pipeline over various installation stages in the analysis. In this example, DNV code checking is to be completed so specifications for the local buckling unity checks are made under DNV Postprocessing. The Functional Stage on the Load Data dialog is specified as Installation Stage 1. The pipe section that the checks are to be carried out on is selected as ‘Line(1)_12’’ Pipe Section(1)’ from the drop-down list where the Section Properties described in the table below are specified. The General Data dialog is used to specify a Transience Period of 10%. All other inputs are as per default.

Table: DNV Postprocessing Section Properties

Property

Value

SMYS

415 MPa

SMTS

520 MPa

 

Running the Analysis

You are now ready to run the analysis. While the analysis is running, you can observe the analysis progress and check for warnings or errors on the Progress tab.

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