ssc-367 - Ship Structure Committee

hydrostatic stiffness is introduced and (3) the make-up of applied
forces differs.
The terms given represent:
[M] = 6x6 structuremass matrix
[Ma] = 6x6 added mass matrix
[CR] = 6x6wave radiation damping matrix
[Cv] = 6x6 linearized viscous damping matrix
[KH] = 6x6 hydrostatic stiffness matrix
(FD) = 6x1 linearizedwave drag force vector
(F,) = 6x1 wave inertia force vector
(F~~) = 6x1 diffracted wave inertia force vector
{x}, {x}, {x} = 6x1 structure displacement, velocity and
acceleration
If a structure such as a TLP is tethered to the seafloor, the
stiffness matrix is modified from:
[&J {x} to [[&-J + [K~l1 {x}
where, the [KT]represents 6x6 tether stiffness matrix.
As discussed in previous sections,the structureconfigurationsand
the motion characteristics (i.e., steady state harmonic motion)
facilitate the 6 x 6 motions equations solution over the frequency
domain.
It is recommended that the significant wave height in the wave
scatter diagram that is likely to contribute most to the fatigue
damage be chosen to linearize the drag forces for all wave
frequencies.
The basic approach discussed here has been utilized frequently in
recent years, and is discussed herein as it was implementedon the
design and analysis of a TLP by $ircar et al (Reference5.8). The