HydroD stability tutorial - home.hib.nohome.hib.no/ansatte/tct/ftp/H2017 Marinteknisk... · • HydroD may do a compartment balancing to ensure that the draft, trim and heel specified

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Sesam – HydroD Tutorial

© DNV GL - Software. All rights reserved 21 December 2016

SESAM User Course in Stability and Hydrostatic Analysis

HydroD Workshop:

Perform the analysis in HydroD

• The text in this workshop describes the necessary steps to do stability and hydrostatic

analysis of a barge with a jacket on top.

• The barge has 8 tanks which can be filled independently – in this workshop you are asked

to do various tank fillings to see the effect on both equilibrium position and the computed

GZ-curves.

• The panel model, structure model (used to describe the tanks) and the mass model has been

created in GeniE. The total mass of the structure (mass model) is 9011 tonnes. The file

describing the model is called HydroD_Stab_Ex1_T1.FEM. If you have used the default

installation, this file is located C:\Program Files (x86)\DNVGL\HydroD V4.*-

**\Examples\Barge

• In x-direction the max and min x-values are -45.72m and 45.72m

• In addition to the text input, there is also a journal file Barge_Jacket_Stability_in.js that you

can read into HydroD to rapidly reproduce the workshop. Please make sure that the journal

file and the FEM file has been copied to the project directory set up by HydroD.

• This workshop should be viewed on-line or on colour print out to best see the property

colour coding.

Stability and Hydrostatic analysis

Xmin = -45.72mXmax = 45.72m

The model created in GeniE

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Important notes:

• The barge has eight tanks as shown above. The

tank filling is done in HydroD by the user (or

from using the feature for tank balancing).

• The wetted surface to describe the panel model

has also been defined in GeniE.

• Any of the structures are fictitious model and

the sea fastening arrangement has been

simplified from a conventional arrangement –

the main purpose of this workshop is not

structure but hydrostatics

• The units are meter and kg.

• All pictures created by GeniE and HydroD are

shown using white background

(View|Options|General|Paper

Background). This may be different from your

background.

Part 0 - General

Tank 1

Tank 2

Tank 3

Tank 4

Tank 5

Tank 6

Tank 7

Tank 8

The internal tanks as defined in

GeniE

Model origin at (0m, 0m, 0m) as

shown above

All tanks have the same volume

Vtank = 832.895 m3

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The workshop is split as follows (start modelling from Part 1 and onwards)

• Part 0 – General introduction to the workshop and start HydroD

Pages 1-4

• Part 1 – using the stability wizard to make model and do initial analysis

For new users the wizards will guide you through all necessary steps to make a model fit

for stability and hydrostatic computations. For more experienced users, similar modelling

and analysis are done by using pull-down menus, tool-buttons or from the context sensitive

menu in the browser.

Pages 5-35

• Part 2 – Create a new loading condition with changed compartment filling

How to copy a loading condition, change the compartment fillings and find a new

equilibrium position

Pages 36-38

• Part 3 – Create damaged loading condition

This part uses the previously generated loading condition as the starting point of a damaged

loading condition

Pages 39-41

• Part 4 – Execute multiple stability analysis

Generate multiple hydrostatic analysis and execute them. View the results.

Pages 42-50

• Part 5 – Make a clean journal file

Save the input files (journal files) for later use

Pages 51

Part 0 - General

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Start HydroD and make a new workspace

• You start HydroD from

Desktop

From Start menu

• You make a new workspace (or a project) from File|New Workspace and give it a

name

For this workspace we use units meters and Newton

Part 0 - General

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Activate the wizard

• You activate the wizard from the tool-button

• You need to specify what type of model you will be working with, this workshop

assumes a pure panel model.

Part 1 – The stability wizard

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• You may also change the default settings (i.e. filter out steps in the wizards) by

clicking on “Settings”. In this tutorial we will not do an allowable VCG analysis, so

untick this.

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Step 1 in the wizard

• Create a location

• Specify name (“Doggerbank” in this case), water density, kinematic visosity and water

depth. Remember also to add details for the air

• Step 2 in the wizard

• Create a hydro model

• Specify a name and decide fixed or floating structure. Baseline, AP and FP positions

are only relevant for Wasim analysis, so you don’t need to change these.


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• Create a panel model

• The panel model specifies the outer wetted surface. The wetted surface is being used to

calculate the floater buoyancy.

The panel model has been made in GeniE

To import, locate the file HydroD_Stab_Ex1_T1.FEM stored under C:\Program

Files (x86)\DNVGL\HydroD V4.*-**\UserExamples\Barge\inp. The path name

assumes you have installed the program HydroD using default values when installing

There are no symmetry planes in this model and the coordinate system of the

imported model coincides with the coordinate system of the hydro model


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Cont’d

• The panel model is now shown in your display window


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• Create load cross sections

(Press next)

• Cross-sections must be defined where you want

HydroD to compute still water forces and moments

The wizard will guide you to define several cross

sections one by one

This workshop will instead use the “Multiple load crossections” option. This is

reached by right clicking the LoadCrossections folder and choosing “Multiple load

cross sections”.

Define cross sections as shown below


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• Create the structure

model. The tank

definitions are now

imported

• Similar to the panel model, the structure model has been created in GeniE.

To import, locate the file HydroD_Stab_Ex1_T1.FEM stored under

C:\Program Files (x86)\DNVGL\HydroD V4.*-**\UserExamples\Barge\inp.

• The panel model, the structure

model and the crossections are are now being

shown in the graphical window


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Cont’d

• Hint: You may switch your focus view by using the “Modelling Draw Style” feature

Below is shown how to look at the structure model only and also how to change

colours of the beams to dark blue

Remove the panel model

and LoadCrossSections

from view


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Cont’d

• Hint: You may switch your focus view by using the “Modelling Draw Style” feature

The beams are now shown with dark blue colour.

Plates are shown with grey colour


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• Create permeability

factors

• Permeability factors are used to specify whether a tank (or compartment) is filled with

solid content.

A permeability factor of e.g. 0.9 indicates that the compartment can be filled with

90% of the total compartment volume.

In this model, a permeability factor of 1.0 is used. This means that all tanks are

“clean” inside and can be filled to 100% of tank volumes.

Click OK to proceed to next step.


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• Create compartments

• The compartments are automatically found from the structure model. The

compartments will receive properties for permeability and deck tanks.

In this case, there are no permeability or deck tank factors to add, hence click OK to

proceed..


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• Create loading

conditions

• A loading condition is set up by defining the draught, trim and heel

Manually, often used to create a

temporary equilibrium position prior to a

stability analysis.

From a known mass

For this workshop, please use 5 m as draught


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• Create fluid

properties

• There may be several fluid types that fill the compartments

Examples may be water, oil, sea water

In this workshop one fluid type is used – define Sea_water with density 1025 kg/m3

Click OK to proceed to next step


• Create flooded

properties

• The flooding compartment property is used to specify whether a compartment is to be

considered flooded or not

Create one property for flooding as shown

Click OK to proceed to next step


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• Specify filling

fractions

• The filling fractions are used to specify the degree of filling for each compartment

Remember, the compartment filling is built up from fluid property, permeability and

filling

For this workshop, specify 10 filling fractions 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9

and 1.0

You may also edit these values from the browser....


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• Create the compartment

content

• The content of the compartments is now defined, both for intact and damaged conditions

Define as shown below

Click OK to proceed


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Cont’d

• Display the tank filling

You may edit the visual settings of the compartment content by using the “Modeling

Draw Style” as shown.

The panel model transparency has been set to 90% below (from the “Modeling Draw

Style” dialog on the panel model)


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• Specify the mass

• Various ways of defining the mass

The various options are shown below

For this workshop, use “From File” and import the file HydroD_Stab_Ex1_T1.FEM

stored under C:\Program Files (x86)\DNVGL\HydroD V4.7-

**\UserExamples\Barge\inp

A total mass of 9011 tonnes is now imported. In addition comes mass of fluid in tanks


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• Automatic compartment

balancing

• HydroD may do a compartment balancing to ensure that the draft, trim and heel

specified are met

We select compartments 2, 3, 8 and 9 and press the “Compute filling fractions”

button.


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Step 14 cont.

• The filling fractions and compartment contents should now look like:


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• Define flooding

openings

• You may specify flooding openings to track whether they are above or below the water

surface during a hydrostatic computation and connect them to different

compartments

In this workshop 2 openings are defined, Point_1 and Point_2 at the barge corners

as indicated

The flooding openings are defined by graphic selection, but you may also enter the

explicit coordinates

No compartments are connected with openings in this workshop


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• Create stability

analysis

• Define hydrostatic analysis with the purpose of computing GZ curves and other

hydrostatic data.

There may be many hydrostatic analyses reflecting various loading conditions

and/or rotation axis.

Typically there will be several loading conditions simulating various intact and

damaged conditions. See later in this workshop how to make multiple loading

conditions and hydrostatic analyses

Make one loading condition as shown below


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• Create wind profile

• Wind influences stability as heeling moments and it is thus necessary to include it in

the stability calculations.

The wind contribution is a combination of wind profile, drag coefficients, block

coefficients and active structure area.

• Wind profiles may be user defined or standard IMO MODU Wind Profile

This tutorial assumes usage of standard wind profile with wind velocity 75 m/s

The wind profiles may be edited from the browser as indicated below


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• Create drag coefficient

curve

• Specify the drag coefficient curve as a relation between diameters and drag

coefficients.


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• Create drag block

coefficient curve

• Specify the drag block coefficient curve as a relation between cross sectional block

coefficient and drag coefficients.


Drag as function of cross-sectional area divided by circumscribed area

(i.e. is it a round shape or is it something more square

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• Create heeling moment

• The heeling moment is now defined as a combination of:

This heeling moment is perpendicular to the heeling axis

• You may also specify the wind heeling moments by a user definition

This tutorial assumes empiric flow as defined above


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• Run the hydrostatic

analysis


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• Look at the results

• Examples on results to look at – the GZ curve

You may find the exact GZ values for each angle by saving a report (File|Save

Report) or from information (right click an analysis and choose Information)

Note that the z-level of the lowest flooding opening is displayed together with the

GZ-curve


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Examples on results to look at – Moment of force

You may compute the righting moment integral by changing start and end angles

Note that for the 75m/s wind the overturning wind moment exceeds the righting

moment (meaning that it will capsize)!


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• Examples on results to look at – Flooding openings


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• Examples on results to look at – Cross section data shear force


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• Examples on results to look at – Cross section data bending moment


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• Examples on results to look at – Model Information

You find typical model data here

More information will be produced by “Save report”


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Copy the transit loading condition

• Right click the Transit loading condition in the browser and select “Copy”

• Right click the “LoadingConditions” folder and choose paste

• A new loading condition called Transit_1 should now emerge in the browser (inheriting the

name from the original loading condition)

Part 2 – New loading condition

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Change the compartment filling

• Right click the “CompartmentContents2” folder and choose “Compartment contents”

• Change the filling fractions for compartment number 8 and 9


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Recompute the equillibrium position

• Right click “Transit_1” and choose “Edit”

• Press the “Compute from mass” button and compute the new equillibrium position based

on the mass model

• Press OK to apply the new position


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Copy the Transit loading condition and damage compartments

• Again we start by copying the transit loading condition to create Transit_2 (right click

Transit and choose “Copy”, right click LoadingConditions1 and choose “Paste”)

• Rename the loading condition to TransitDamage

• Right click the “CompartmentContents3” folder and choose “Compartment contents”

• Flood compartments 1 and 3 by selecting the flooded property and pressing OK

Part 3 – Damaged loading condition

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Recompute the equillibrium position

• Select “Edit” on the TransitDamage” loading condition and recompute the equilibrium

position from the mass. Press OK.


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View the new equillibrium position.


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Create stability analysis for the Transit_1 loading condition

• Right click “StabilityTransit” and choose “Copy”

• Right click the “StablityAnalysis” folder and choose “Paste”

• Select “Edit” on the new “StabilityTransit_1” and change the loading condition. Press

OK.

Part 4 – Multiple analysis

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Create stability analysis for the TransitDamage condition

• Right click the “StabilityAnalysis” folder and choose “New Stability Analysis”

• Select loading conditions and location as shown below. Note that also the undamaged

condition is specified.

• Press the “Auto detect damage rotation axis” to detect the rotation axis

• Make the remaining settings as below and press OK


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Execute multiple analysis

• Right click the “StabilityAnalysis” folder and choose “Execute Stability Analysis”

• Select the analysis you want to execute by clicking on the icons in the list

• Press “Start” to execute


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View the results

• As previously the results can be viewed from the stability report dialog reached by

right clicking an analysis in the browser

• More details can be viewed by selecting “Information” on an analysis


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View the results


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View the results

• Note that the left browser pane tree can be expanded and more information is

revealed


49



View the results

• The most extensive amount of information is created by save report (either from an

object in the browser or from the File menu)

• We employ the XML word format


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Make a clean journal file

• Save the work for later use

When save or exit, all data is stored and you can open the workspace later on

• Save the journal file for later use

You can import the journal file created during this session into a new workspace.

This file contains all historical data such as copy, rename and so on.

It is recommended to make a “Clean Journal file”. This journal file will create a

minimum of commands to regenerate the actual model.

From the File|Save Clean JS please give the name Transport_stability_in.

You can look at this file – it is stored on the project directory specified by you.

The file may be edited and re-used in other projects

Part 5 – Save the work

Documents

HydroD stability tutorial - home.hib.nohome.hib.no/ansatte/tct/ftp/H2017 Marinteknisk... · • HydroD may do a compartment balancing to ensure that the draft, trim and heel specified