When the dynamics of a cable are included in the analysis of cable motion, the effects of the cable mass and drag forces are considered, and tensions are no longer quasi static, i.e. forces on the cable are time varying and have 'memory'. The cable will, in general, respond in a nonlinear manner. The solution during a time history and the solution in the frequency domain are fully coupled, i.e. the cable tensions and motions of the vessel are considered to be mutually interactive where cables affect vessel motion and vice versa.
The following key points should be noted:
Cable dynamics can only be associated with non-linear composite catenary lines.
Cables are semi-taut/taut during the analysis i.e. they have a minimum tension.
The sea bed is considered horizontal at the anchor.
The cable is modeled with a fixed number of elements.
Inline dynamics (along the line of the cable) is included.
Inline stiffness i.e. AE/DL (DL = segment length) is limited.
Morison Drag forces are included (wave particle velocity ignored).
Wave kinematics is ignored although current is included.
Full animation of cable dynamics is not included.
Sea bed friction is ignored.
The AGS Model Visualisation is based on the quasi-static configuration and tensions for any particular position of the fairlead.