*LINE PATHS |
 
|
*LINE PATHS |
|
To define a line with an arbitrary geometrical configuration (e.g. such as a rigid spool). This keyword is closely linked to *LINE PATH SECTIONS.
*LINES is better suited to modelling a straight line or a simple catenary section. Several connecting catenaries, created by weight and buoyancy distributions (e.g. such as a lazy-wave catenary), may also be modelled using *LINES.
Refer to Line Paths for further information on this feature.
A block of lines defining an individual line and its associated settings. The block begins with a line defining the line name. This is followed by an optional line defining a default set name for elements within the line which are not part of any sub-sections (if present). The next line defines a node label for the start of the line, along with its coordinates, followed by a node label for the end of the line. The next line contains suggested minimum and maximum element lengths for the line to be used during mesh generation. This is followed by an optional line defining undeformed orientation of the elements used to model the line. A mandatory block consisting of one to three lines defining line segments then follows, and this block may be repeated as often as necessary to define all the required segments of the line. Line segments govern the physical geometry and finite element meshing of the line path. They also result in the automatic creation of element sets (and node/element labels), facilitating the subsequent assignment of geometric and hydrodynamic properties. Additional element sets may be created via *LINE PATH SECTIONS if required.
Opening Block (mandatory):
Line defining the line name.
LINE=Line Name
Optional line defining a default set name for elements within the line which are not part of any line sections (if present):
[NON SECTION=Default Set Name]
Line defining a node label for the start of the line, along with its coordinates:
START=Start Node Label, X [,Y] [,Z]
Line defining a node label for the end of the line:
END=End Node Label
Line defining suggested minimum and maximum element lengths for the line to be used during mesh generation:
Minimum Element Length (at line start) [, Maximum Element Length] [Minimum Element Length (at line end)] [, RATIO=Aspect Ratio]
Optional line defining undeformed orientation of the elements used to model the line:
[v1, v2, v3, w1, w2, w3]
Segment Block (mandatory):
Line defines the line segment name, the location of the corner point at the end of the segment, the corner radius, the tangent length, and the element lengths around the corner.
SEGMENT=Segment Name, Corner X, Corner Y, Corner Z [, Corner Radius] [, Tangent Length] [, Element Length at Bend]
Optional line defining suggested minimum and maximum element lengths for the line segment to be used during mesh generation:
Minimum Element Length (at line start) [, Maximum Element Length] [Minimum Element Length (at line end)] [, RATIO=Aspect Ratio]
Optional line defining undeformed orientation of the elements used to model the line segment:
[v1, v2, v3, w1, w2, w3]
To define a line path, by specifying the start location, and mesh generation settings.
Input: |
Description |
Line Name: |
The name of the line. |
Non-Section Set Name: |
The element set name for any portions of the line which are not included in any line section definitions. Sections are defined using the Line Path Sections table. |
Start Node Label: |
The node label for the start of the line. |
Start (X): |
The global X coordinate of the start of the line. |
Start (Y): |
The global Y coordinate of the start of the line. This entry is optional and defaults to zero if omitted. |
Start (Z): |
The global Z coordinate of the start of the line. This entry is optional and defaults to zero if omitted. |
End Node Label: |
The node label for the end of the line. |
Min. Element Length at Start: |
The (approximate) minimum element length at the start of the line. |
Max. Element Length: |
The (approximate) maximum element length used in the line mesh. The lengths of successive elements beginning from the start and end of the line are gradually increased up to this value. This entry is optional, and if omitted, a uniform mesh density is typically created, based on the specified Min. Element Length at Start. |
Min. Element Length at End: |
The (approximate) minimum element length at the end of the line. This entry is optional, and if omitted, it defaults to the corresponding Min. Element Length at Start entry. |
Mesh Ratio: |
The meshing algorithm ensures that the ratio between the lengths of adjacent elements cannot exceed a certain value. This option allows you to set the value of an optimum ratio. |
V1, V2, V3: |
The components in the global coordinate axes of a vector V, (one of two) defining the undeformed orientation of the elements used to model the line. These entries are optional and will not be invoked in the vast majority of cases. See Note (e). |
W1, W2, W3: |
The components in the global coordinate axes of a vector W, (one of two) defining the undeformed orientation of the elements used to model the line. These entries are optional and will not be invoked in the vast majority of cases. See Note (e). |
(a)It is important to define meaningful names (for Line Name and Non-Section Set Name entries), as these names will be used by the program to automatically create relevant element sets for you, which you can subsequently reference when you are assigning structural and hydrodynamic properties to your model.
(a)It is important to associate meaningful labels with the line start and end locations, as these labels will be used by the program to automatically create relevant node labels for you, which you can subsequently reference when you are applying boundary conditions to your model.
(b)You have control over the distribution of the elements along the line, via the specification of desired maximum and minimum element lengths, and also the division of the line into several sections if required. The meshing algorithm automatically generates a finite element discretisation based on the guidelines you provide. It also attempts to prevent large changes in relative element length across the finite element mesh by gradually stepping up and down element lengths along the structure, and to avoid over-meshing by using longer elements in the middle of long sections of continuous properties. The specified element lengths are approximate as the automatic line meshing may use slightly different lengths in practice.
(c)Refer to Line Paths for a discussion of the automatic mesh creation facility.
(d)Refer to Lines & Local Undeformed Axes for a discussion on the significance of the V and W vectors (which define local undeformed element axes) in relation to lines.
To define segments within a line path, by specifying segment names, locations of corner points, corner radii, tangent lengths, and the element lengths around the corners. Plus mesh generation settings. Line segments govern the physical geometry and finite element meshing of the line path. They also result in the automatic creation of element sets (and node/element labels), facilitating the subsequent assignment of geometric and hydrodynamic properties. Additional element sets may be created via *LINE PATH SECTIONS if required.
Input: |
Description |
Line Name: |
The name of the line. See Note (b). |
Segment Set Name: |
The element set name for the line segment definition. |
Corner X: |
The X location of the end point of the segment, specified with respect to the end point of the previous segment (or the line start point in the case of the first segment). |
Corner Y: |
The Y location of the end point of the segment, specified with respect to the end point of the previous segment (or the line start point in the case of the first segment). |
Corner Z: |
The Z location of the end point of the segment, specified with respect to the end point of the previous segment (or the line start point in the case of the first segment). |
Corner Radius: |
The bend radius at the corner point. This entry is optional and the corner radius defaults to 3 times the local element diameter if omitted. |
Tangent Length: |
The length, before and after the bend, to which the corner meshing settings apply. This allows you to use the refined mesh beyond the extents of the bend radius. This entry is optional and the tangent length defaults to 500mm or 20inch if omitted. |
Element Length at Corner: |
The (approximate) element length around the corner section. This entry is optional and the default element length is such that there is approximately 1 element for every 5 degrees of bend. |
Min. Element Length at Start: |
The (approximate) minimum element length at the start of the line segment. |
Max. Element Length: |
The (approximate) maximum element length used in the line segment mesh. The lengths of successive elements beginning from the start of the line segment are gradually increased up to this value. This entry is optional, and if omitted, a uniform mesh density is typically created, based on the specified Min. Element Length at Start. |
Min. Element Length at End: |
The (approximate) minimum element length at the end of the line segment. This entry is optional, and if omitted, it defaults to the Min. Element Length at Start entry for the next segment (or the Min. Element Length at End of the line itself, if it is the last section). |
Mesh Ratio: |
The meshing algorithm ensures that the ratio between the lengths of adjacent elements cannot exceed a certain value. This option allows you to set the value of an optimum ratio. |
V1, V2, V3: |
The components in the global coordinate axes of a vector V, (one of two) defining the undeformed orientation of the elements used to model the line segment. These entries are optional and will not be invoked in the vast majority of cases. See Note (c). |
W1, W2, W3: |
The components in the global coordinate axes of a vector W, (one of two) defining the undeformed orientation of the elements used to model the line segment. These entries are optional and will not be invoked in the vast majority of cases. See Note (c). |
(a)It is important to define meaningful names (for Segment Set Name entries), as these names will be used by the program to automatically create relevant element sets for you, which you can subsequently reference when you are assigning structural and hydrodynamic properties to your model.
(b)Refer to Line Paths for a discussion of the automatic mesh creation facility.
(c)Refer to Lines & Local Undeformed Axes for a discussion on the significance of the V and W vectors (which define local undeformed element axes) in relation to lines.