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*Drag Chain |
 
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*Drag Chain
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*Drag Chain |
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To include drag chains in the structural model.
Refer to Drag Chains for further information on this feature.
Two types of line repeated as often as necessary.
Line defining a single drag chain:
Node (Number or Label), Total Chain Length, Mass/Unit Length [, Lift Coefficient]
Line generating a number of drag chains:
GEN=Master Node (Number or Label), No. of Chains [, Node Increment]
When generating a number of drag chains a drag chain must have been previously defined at the master node. If you specify a node label rather than a node number, it must be enclosed in {} brackets. Node Increment defaults to 1.
Input: |
Description |
Node Number: |
The node (number or label) at which the drag chain is being attached. If you specify a node label rather than a node number, it must be enclosed in {} brackets. |
Total Chain Length: |
The total length of the drag chain. |
Mass/Unit Length: |
The mass per unit length of the drag chain. |
Lift Coefficient: |
The drag chain lift coefficient CL, used to calculate the lift force per unit length of the drag chain. See Note (b). |
Input: |
Description |
Master Node: |
The node (number or label) at which the drag chain properties for the master chain are defined. The properties of this chain are assigned to all of the chains that are generated here. If you specify a node label rather than a node number, it must be enclosed in {} brackets. |
Number of Chains: |
The number of chains to be generated, where this includes the master chain. |
Node Increment: |
The node number increment between nodes at which drag chains are to be positioned. This defaults to a value of 1. |
(a)Gravity and lift forces for the drag chain are computed and applied as point loads at the specified node of the structure. The gravity load is calculated from the length of drag chain not lying on the seabed.
(b)The lift force on each chain is calculated from the relative fluid/structure velocity at the node at which the drag chain is attached, and the lift coefficient that you specify here. The lift force is computed using the following equation
where FL is the total lift force, CL is the specified drag chain lift coefficient, ΡW is the mass density of seawater, U is the magnitude of the horizontal component of relative fluid/structure velocity at the drag chain node, and l is the length of drag chain not lying on the seabed.