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Importing lines data from external file

An import feature allows to import external meshes into a DSK file. The import is based on a ASCII file where nodes positions and elements are defined. This is generally but not necessarilty a file with the .tdl extension for DeepLines

Note

This feature is for instance useful to import all lines or bars assembly required to model truss structures such as jackets.

Starting with version 5.4.3, this feature is also used for multistructure floaters (see Multistructure floater

It is possible to define a mesh in an external ASCII file and to import it into a DeepLines model by two ways:

Click the arrow placed on the right-hand side of the New Line button placed in the tools bar and select the Create from mesh item.

The following dialog box then displays, which allows to select the text file detailing all lines data to be imported to the GUI.

This allows the user to create simultaneously several lines with their respective properties.

Applications

The mesh may be associated with a rigibody: in that case, all elements (beams and ancillaries) are rigidly linked to the rigid body center of motion. Their mechanical properties (mass, inertia, submerged weight), their hydrodynamic coefficients and the resulting forces and moments are calculated and applied onto the center of motions.

The mesh may be split into different lines and lump masses: in that case, all elements are created in the model as Generic Lines and stored in a specific sub-repertory which name is the ASCII file name. Note that unless defined in the ASCII file with the keyword *CONNECTION, these elements are not connected to each other, so the connections must be defined in the DeepLines model.

This function may be useful to define structures like Jackets or trusses composed of series of beam/bar elements as shown in the following examples:

Jacket model in a rigid body (with ballasted LEGs)

Metocean mast structural model

File format

The .tdl file is an ASCII file with alist of keyword to enter nodes, bar and beam properties as well as connections. The file can be generted automatically from an ISYMOST model. ISYMOST being able to read other softwre mesh (Abaqus, ANSYS,...) it is also possible to create the .tdl from a mesh of one of this softwares via ISYMOST).

The list of keywords that can be used in .tdl files are:

Note that the keyword TRIANGLE is used to define surface (used for visualisation and potentially line to surface contact) and TRIANGLE / *QUAD are used to define hydrodynamic floater mesh (used for visualisation and potentially non linear hydrodynamic). See surface mesh.

The general philosophy of the file is presented below. Refer to the keywords above for more detailed information.

Definition of nodes

Nodes positions are defined as such:

*NODE

INO1 X1 Y1 Z1

INO2 X2 Y2 Z2

.....

INO1 is an integer, X, Y, Z are reals.

In the GUI, the nodes are created as PRIMARY nodes with the name associated to their numbers.

Definition of line's elements

An extension to the existing feature is that we want to distinguish the types of elements to be created. Elements are then defined on three different ways:

  • Bar/cable elements : *BAR

  • Flexible beams elements : *FLEXIBLE

  • Rigid beam elements : *RIGID

Whatever the type, the following syntax is used :

BAR or FLEXIBLE or *RIGID

IEL1 INO1 INO2 PROP1_NAME

....

where IEL1, INO1 and INO2 are integers and PROP1_NAME is a string of characters.

In the GUI, the elements are created with the name associated to their numbers.

When the keyword *BAR is used, a property cable/chain type named PROP1_NAME is to be created;

When the keyword *FLEXIBLE is used, a property flexible type named PROP1_NAME is to be created;

When the keyword *RIGID is used, a property rigid type named PROP1_NAME is to be created.

Note

If no name is defined, the default property associated to the type is created: FlexPipe_1, RigidPipe_1 or CableChain_1. The partition of each element is 1. If the same property is used for several elements, a single property must be created.

Definition of Groups of elements

The gather the elements that belong to the same line, the keyword *LINE is used.

*LINE

NAME IEL1 IELI IELA IELB

Where NAME is the name of the line to be created and IELI are the elements numbers.

We suggest to use the same syntax as for the LOG file (any equivalent proposition is welcome):

  • Elements numbers are separated by blanks;

  • -is used to define consecutive element numbers : 1 10 means 1 2 3 4 5 6 7 8 9 10.

The following rules will be applied:

  • NODE that belong to ELEMENTS of the same LINE and which have the same name are merged into a single node;

  • The elements of a LINE define the sections of the LINE;

  • ELEMENTS that belong to no LINE are created as independent lines in the GUI;

  • All the lines with at least a FLEXIBLE or a RIGID element is affected an internal fluid with the Pressure = 100000 Pa and the specific gravity = 0.

Properties definition

This part may be optional as the quick data access allows to quickly define a set of properties. Four keywords are created to define the properties:

*RIGIPRO

*FLEXPRO

*FLEXPRO2

*BARPRO

Material definition

This part may be optional as the quick data access allows to quickly define a set of properties. The *MATERIAL keyword is usedto define the properties.

Definition of lines

When imported into DeepLines GUI, the elements are created with the name associated to their numbers unless they are gathered in one LINE with the following keywords:

*LINE

LINE_NAME IEL1 IEL2 IELn

In that case, a generic line named LINE_NAME is created in DeepLInes GUI gathering all the elements.

If a LINE gathers a long list of elements, several lines may be necessary. In that case, the symbol & means return to line. The symbol - also allows to short cut series of successive numbers of elements.

Note

Then LINEs are created, they may be used to define a ballasted part of a rigid body.

Example:

*LINE
LEG1   1 **100    200 **250    300 **350    400 450  500 **550
1000   1100   **&**
  1300  1650.

Definition of ancillaries

Ancillaries may be introduced on any node(s) of the mesh.

An ancillary is defined by a mass (kg), three inertia momenta (Ixx, Iyy, Izz) and a buoyancy force (N).

*ANCILLARY

$Node M_tot (kg) Ixx (kg.m2) Iyy (kg.m2) Izz (kg.m2) Buoyancy (N)

If the node on which the ancillary is defined is in the air, the weight Mg will be applied on the node; If this node is under water, the submerged weight Mg Buoyancy will be applied.

When imported into the user interface, an ancillary will be defined as a LUMP MASS loading.

Example:

*ANCILLARY
$Node    M_tot (kg)  Ixx (kg.m2) Iyy (kg.m2) Izz (kg.m2) Buoyancy (N)
1         115         0           0           0           0
4         115         0           0           0           0
8         115         0           0           0           0

Definition of connections

Connections between nodes are defined with the keyword *CONNECTION.

The syntax is the following:

*CONNECTION

The nodes must be previously defined

Example:

*CONNECTION
CON000 1 2 3 4 5

Here the connection name is CON000. When imported into the user interface, a Rigid Body RB_CON000 will be created. The reference node will the position of node 1 and five fairleads will be created based on nodes 1, 2, 3, 4 and 5. Beam with those nodes will be connected to the rigid body